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Reaction of bis(bis(trimethylsilyl)amido)mercury(II) with 3,3′-disubstituted binaphthols: Cyclization via an intramolecular electrophilic aromatic substitution reaction
Inorganica Chimica Acta 360 (2007) 1977–1986 www.elsevier.com/locate/ica
Reaction of bis(bis(trimethylsilyl)amido)mercury(II) with 3,3 0-disubstituted binaphthols: Cyclization via an intramolecular electrophilic aromatic substitution reaction Anthony E. Wetherby Jr., Stacy D. Benson, Charles S. Weinert
*
Department of Chemistry, Oklahoma State University, 316 Physical Science, Stillwater, OK 74078, United States Received 5 September 2006; accepted 14 October 2006 Available online 21 October 2006
Abstract Reaction of the mercury(II) amide Hg[N(SiMe3)3]2 with 3,3 0 -disubstituted binaphthols (HO)2C20H10(R)2-3,3 0 (R = SiMe3, SiMe2Ph, SiMePh2, SiPh3) in a 2:1 stoichiometric ratio furnishes four hexacyclic 1,7-disilylsubstituted derivatives of peri-xanthenoxanthene (PXX). Reaction of these two reagents in a 1:1 ratio results in a mixture of the hexacyclic products as well as the related pentacyclic species which contain one hydroxyl group and only one C–O–C ring fusion. The structures of three of the hexacyclic products (R = SiMe3, SiMe2Ph, SiMePh2) and one of the pentacyclic products (R = SiMe3) have been obtained. The reaction of Hg[N(SiMe3)3]2 with the 3,3 0 -disubstituted binaphthols proceeds via an intramolecular electrophilic aromatic substitution reaction and several intermediates in this process have been detected using NMR (1H and 199Hg) spectroscopy. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Mercury compounds; Electrophilic aromatic substitution; Mercury-199 NMR spectroscopy; X-ray crystal structures; Substituted binaphthols; Wheland intermediates; UV–Vis spectroscopy; Fluorescence spectroscopy
1. Introduction The synthesis of polycyclic aromatic and heteroaromatic compounds and their complexes is of interest due to their electronic properties and potential utility as organic conductors [1–7]. The long-known hetroaromatic species peri-xanthenoxanthene (6,12-dioxaanthanthrene, PXX) has recently been employed for the formation of charge transfer complexes involving organic [8,9] and inorganic species [8] and also in conductive salt complexes containing cobalt [8,10–14] and iron [15–17] phthalocyaninato ions. The utility of PXX and its derivatives as organic conductors [18–20] has also been investigated and derivatives of PXX have also been employed as ingredients in pigments. This hexacyclic species was originally prepared by the
*
Corresponding author. Tel.: +1 405 744 6543; fax: +1 405 744 6007. E-mail address: [email protected] (C.S. Weinert).
0020-1693/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2006.10.005
reaction of 1,1 0 -bi-2-naphthol with copper(II) acetate and synthetic methods for the preparation of substituted derivatives of PXX are not known. We have found that the sterically encumbered mercury(II) amide Hg[N(SiMe3)2]2 (1) [21] cleanly reacts with 1,1 0 -bi-2-naphthol to furnish PXX and also with 3,3 0 -disubstituted-1,1 0 -bi-2-naphthols to yield 1,7-disubstitued derivatives of PXX in high yield, the latter of which might find use in combination with inorganic complexes to furnish conductive materials. Using this method, we have prepared and characterized four disubstituted silyl derivatives of PXX and have probed the reaction pathway using NMR (1H and 199Hg) spectroscopy. 2. Results and discussion The mercury(II) amide Hg[N(SiMe3)2]2 (1) reacts with the 3,3 0 -disubstituted binaphthols (2a–d) and also the parent 1,1 0 -bi-2-naphthol (2e) to furnish pentacyclic or hexacyclic fused species depending on the reaction stoichiometry
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(Schemes 1 and 2). The reaction occurs via an intramolecular electrophilic aromatic substitution reaction involving mercuration of the hydroxyl groups followed by attack at the 9-position of the adjacent naphthyl ring and subsequent extrusion of elemental mercury. The reaction of 1 equiv. of 1 and 2a in benzene on a preparative scale was carried out at 85 °C over 12 h. The reaction mixture became dark yellow upon initial addition of a solution of 2a to a solution of 1 and after heating for 5 min the reaction mixture was dark purple/red in color. After 12 h the solution had become green/yellow in color and beads of mercury metal were clearly visible at the bottom of the reaction vessel. Filtration of the reaction mixture in air and removal of the solvent in vacuo yielded an orange/yellow solid. The 1H NMR spectrum of the crude product exhibited four resonances in the –SiMe3 region at d 0.54, 0.52, 0.46, 0.44 ppm indicating the presence of 2a (d 0.46 ppm) and two other species. Recrystallization of the crude material from a hot benzene solution furnished the pentacyclic compound 3a in
SiMe3
˚ , respectively) are nearly identical to the exocy1.380(2) A ˚ . The five-ring clic O(2)–C(20) bond distance of 1.378(2) A system of 3a is puckered rather than planar, as shown by the angles of 6.64° and 4.44° in the central OC5 ring about O(1)–C(10)–C(9)–C(11) and O(1)–C(13)–C(12)–C(11), respectively. Further recrystallization of the mother liquor furnished crystals which differed in appearance from those of 3a and were found to be the hexacyclic compound 4a using X-ray diffraction. An ORTEP diagram of 4a is shown in Fig. 2 and bond distances and angles are collected in Table 2. ˚ , which are substanThe C–O distances in 4a are 1.393(3) A tially elongated relative to those of 3a, and the overall sixring system in 4a is completely planar. Compound 4a is highly symmetric with the two halves of the molecule being interrelated by a center of inversion. Reaction of an additional equivalent of 1 with 3a at 85 °C results in quantitative conversion of 3a to 4a after 18 h as shown by 1H NMR spectroscopy. A preparative scale reaction under the same conditions furnishes 4a in 85% yield as shown in Eq. (1)
SiMe3
OH
O
1 eq. Hg[N(SiMe3)2]2 (1) C6H6, 24 h, 85 oC
O Me3Si
+ 2 HN(SiMe3)2 + Hg
O
ð1Þ
Me3Si 4a
3a
85 %
37% yield as yellow crystals. The identity of 3a was determined using NMR (1H and 13C) spectroscopy and elemental analysis and the X-ray crystal structure of 3a was also obtained to confirm its identity. An ORTEP diagram of 3a shown in Fig. 1 and bond distances and angles are collected in Table 1. The intracyclic C–O bond distances of 3a between O(1) and C(10) and O(1) and C(13) (1.383(2) and
R
R
OH
1 eq. Hg[N(SiMe3)2]2 (1)
OH
C6H6, 24 h, 85 oC
R 2a R = SiMe3 2b R = SiMe2Ph 2c R = SiMePh2 2d R = SiPh3 2e R = H
Both 3a and 4a were further characterized by NMR spectroscopy and elemental analysis. The 1H NMR spectrum of 3a exhibits a resonance at d 4.20 ppm arising from the single hydroxyl group and two features at d 0.54 and 0.52 ppm corresponding to the two non-equivalent –SiMe3 groups. The 13C NMR spectrum of 3a contains the expected 22 resonances with two signals at d 0.6 and d
OH O R 3a 3b 3c 3d 3e
R
+
O O R
R = SiMe3 R = SiMe2Ph R = SiMePh2 R = SiPh3 R=H
Scheme 1.
4a 4b 4c 4d 4e
R = SiMe3 R = SiMe2Ph R = SiMePh2 R = SiPh3 R = H (PPX)
+ 2 HN(SiMe3)2 + Hg
A.E. Wetherby Jr. et al. / Inorganica Chimica Acta 360 (2007) 1977–1986
R OH OH
R 2 eq. Hg[N(SiMe3)2]2 (1) C6H6, 24 h, 85 oC
O O
+ 4 HN(SiMe3)2 + 2 Hg
R
R 2a 2b 2c 2d 2e
1979
R = SiMe3 R = SiMe2Ph R = SiMePh2 R = SiPh3 R=H
4a 4b 4c 4d 4e
R = SiMe3 R = SiMe2Ph R = SiMePh2 R = SiPh3 R = H (PXX)
Scheme 2.
Table 1 ˚ ) and angles (°) for compound 3a Selected bond distances (A O(1)–C(10) O(1)–C(13) O(2)–C(20) C(1)–C(2) C(1)–C(10) C(2)–C(3) C(3)–C(4) C(3)–C(8) C(4)–C(5) C(5)–C(6) C(6)–C(7) C(7)–C(8) C(8)–C(9) C(9)–C(10)
Fig. 1. ORTEP diagram of compound 3a. Thermal ellipsoids are drawn at 50% probability.
0.7 arising from the trimethylsilyl groups and a signal at d 120.4 corresponding to the carbon atom attached to the hydroxyl group. The 1H and 13C NMR spectra of 4a exhibit single resonances at d 0.44 and 0.9 ppm (respectively) attributable to the symmetry-related trimethylsilyl groups. The 13C NMR spectrum of 4a contains ten additional features for the ring carbons with two distinct features at d 153.0 and 111.0 ppm attributable to the oxygen bound atoms C(7) and C(10), respectively. Analysis of the crude product mixture obtained from the reaction of 2a with one and two equiv. of 1 by GC/MS also confirms the formation of a mixture of 3a and 4a. The chromatogram resulting from the crude product obtained using 2 equiv. of 1 (Scheme 2) contained a single peak with a retention time of 95.5 min. The base peak in the mass spectrum of the eluted material appeared at m/z = 426 and a feature at m/z = 428 corresponding to the parent ion of 4a was also visible. A fragmentation pattern corresponding to sequential loss of all six methyl groups was
O(1)–C(10)–C(1) O(1)–C(13)–C(14) O(2)–C(20)–C(19) Si(1)–C(19)–C(20) Si(2)–C(1)–C(10) C(1)–C(2)–C(3) C(2)–C(3)–C(4) C(2)–C(3)–C(8) C(3)–C(4)–C(5) C(3)–C(8)–C(9) C(4)–C(5)–C(6) C(5)–C(6)–C(7) C(6)–C(7)–C(8) C(7)–C(8)–C(8) C(7)–C(8)–C(3) C(8)–C(3)–C(4) C(8)–C(9)–C(10) C(8)–C(9)–C(11) C(9)–C(10)–C(1) C(9)–C(10)–O(1) C(9)–C(11)–C(12) C(9)–C(11)–C(20)
1.383(2) 1.380(2) 1.378(2) 1.373(3) 1.416(3) 1.411(3) 1.412(3) 1.421(3) 1.343(4) 1.380(4) 1.381(3) 1.412(3) 1.447(2) 1.380(3) 113.1(2) 117.5(2) 112.9(2) 119.2(2) 121.1(2) 122.8(2) 121.4(2) 119.4(2) 121.6(2) 118.9(2) 119.9(2) 121.1(2) 120.5(2) 117.5(2) 123.4(2) 119.1(2) 116.5(2) 124.8(2) 125.2(2) 121.7(2) 116.1(2) 127.7(2)
C(9)–C(11) Si(1)–C(19) Si(2)–C(1) C(11)–C(12) C(11)–C(20) C(12)–C(13) C(12)–C(17) C(13)–C(14) C(14)–C(15) C(15)–C(16) C(16)–C(17) C(17)–C(18) C(18)–C(19) C(19)–C(20) O(1)–C(13)–C(12) O(2)–C(20)–C(11) Si(1)–C(19)–C(18) Si(2)–C(1)–C(2) C(10)–C(1)–C(2) C(10)–C(9)–C(11) C(11)–C(12)–C(13) C(11)–C(12)–C(17) C(12)–C(13)–C(14) C(12)–C(17)–C(16) C(12)–C(17)–C(18) C(13)–O(1)–C(10) C(13)–C(12)–C(17) C(13)–C(14)–C(15) C(14)–C(15)–C(16) C(15)–C(16)–C(17) C(16)–C(17)–C(18) C(17)–C(18)–C(19) C(18)–C(19)–C(20) C(19)–C(20)–C(11) C(20)–C(11)–C(12)
1.473(2) 1.883(2) 1.882(2) 1.428(2) 1.386(2) 1.404(2) 1.414(2) 1.367(3) 1.401(3) 1.355(3) 1.420(3) 1.413(3) 1.371(3) 1.425(3) 120.0(2) 124.6(2) 122.8(2) 122.8(2) 116.0(2) 118.4(2) 120.1(2) 121.9(2) 122.3(2) 119.1(2) 117.4(2) 119.6(2) 117.8(2) 119.3(2) 120.7(2) 120.7(2) 123.4(2) 122.3(2) 118.0(2) 122.6(2) 116.0(2)
also present. The chromatogram obtained using 1 equiv. of 1 (Scheme 1) exhibited two features having retention times of 29.8 and 95.2 min. The mass spectrum of the material eluted first exhibits a base peak at m/z = 430 corresponding to the parent ion of 3a and a second feature at m/z = 398 resulting from loss of two oxygen atoms. Peaks
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Fig. 2. ORTEP diagram of compound 4a. Thermal ellipsoids are drawn at 50% probability.
Table 2 ˚ ) and angles (°) for compounds 4a–c Selected bond distances (A 4a O(1)–C(10) O(1 0 )–C(7) Si(1)–C(1) C(1)–C(2) C(1)–C(10) C(2)–C(3) C(3)–C(4) C(3)–C(8) C(4)–C(5) C(5)–C(6) C(6)–C(7) C(7)–C(8) C(8)–C(9) C(9)–C(9 0 ) C(9)–C(10) O(1)–C(10)–C(1) O(1)–C(10)–C(9) O(1 0 )–C(7)–C(6) O(1 0 )–C(7)–C(8) Si(1)–C(1)–C(2) Si(1)–C(1)–C(10) C(1)–C(2)–C(3) C(2)–C(3)–C(4) C(2)–C(3)–C(8) C(3)–C(4)–C(5) C(3)–C(8)–C(7) C(3)–C(8)–C(9) C(4)–C(5)–C(6) C(4)–C(3)–C(8) C(5)–C(6)–C(7) C(6)–C(7)–C(8) C(7)–C(8)–C(9) C(8)–C(9)–C(10) C(8)–C(9)–C(9 0 ) C(9)–C(10)–C(1) C(10)–C(1)–C(2) C(10)–C(9)–C(9 0 ) C(10)–O(1 0 )–C(7 0 )
1.394(3) 1.393(3) 1.888(3) 1.386(4) 1.419(4) 1.419(4) 1.417(4) 1.417(4) 1.358(5) 1.407(5) 1.358(4) 1.404(4) 1.404(4) 1.439(5) 1.366(4) 116.9(3) 121.2(2) 118.0(3) 120.8(2) 123.0(2) 120.8(2) 124.3(3) 125.8(3) 117.1(3) 120.8(3) 120.6(3) 119.2(3) 121.9(3) 117.0(3) 118.5(3) 121.2(3) 120.2(3) 121.4(3) 117.8(3) 121.9(3) 116.0(3) 120.8(3) 119.2(2)
4b 1.416(2) 1.402(2) 1.896(2) 1.384(2) 1.416(2) 1.427(2) 1.408(2) 1.411(2) 1.365(2) 1.401(2) 1.344(2) 1.417(2) 1.398(2) 1.440(3) 1.372(2) 117.3(2) 120.4(2) 120.7(2) 118.5(2) 121.9(2) 122.2(2) 124.5(2) 125.2(2) 116.3(2) 119.9(2) 119.6(2) 120.5(2) 121.7(2) 118.4(2) 119.5(2) 120.8(2) 119.9(2) 120.5(2) 118.1(2) 122.3(2) 115.9(2) 121.4(2) 119.6(2)
4c 1.399(3) 1.402(3) 1.879(3) 1.394(3) 1.416(3) 1.422(3) 1.408(3) 1.415(3) 1.363(4) 1.407(3) 1.356(3) 1.395(3) 1.405(3) 1.439(5) 1.362(3) 116.6(2) 120.6(2) 117.6(2) 121.1(2) 122.7(2) 121.9(2) 124.4(2) 125.3(2) 116.8(2) 120.0(2) 120.2(2) 119.7(2) 121.9(3) 118.0(2) 118.6(3) 121.3(2) 120.1(2) 120.9(2) 117.7(3) 122.8(2) 115.4(2) 121.4(3) 119.1(2)
resulting from fragmentation of all six methyl groups of 3a are also clearly visible. The mass spectrum of the material eluting at 95.2 min is identical to that obtained for 4a, and GC/MS analysis of the product prepared according to Eq. (1) also indicates the presence of only 4a. In order to probe the reaction pathway involved in the formation of 3a and 4a a 1:1 stoichiometric amount of 1 and 2a were combined in C6D6 and the progress of the reaction was monitored by 1H NMR spectroscopy at 25 °C. A proposed reaction pathway is illustrated in Schemes 3 and 4. After 5 min the reaction mixture had become intensely colored and a resonance at d 5.41 ppm was clearly visible. This is shifted downfield from the hydroxyl resonance of 2a (d 4.81 ppm) and the integrated intensity of the new feature was approximately one-third that of the –OH peak of 2a. The feature at d 5.41 ppm is due to formation of the intermediate p-complex A which results from displacement of one –N(SiMe3)2 ligand from 1 upon reaction with a single –OH group of 2a. The alkylsilyl region of the 1H NMR spectrum contained three intense features at this time including one for the –SiMe3 groups of 1 at d 0.24 ppm, a second feature at d 0.46 ppm due to the –SiMe3 groups of 2a, and a third feature at d 0.10 ppm corresponding to HN(SiMe3)2 generated in the reaction. The integrated intensity ratio of the peaks corresponding to 1 and HN(SiMe3)2 was approximately 2:1. Three less intense peaks at d 0.61, 0.04, and 0.15 ppm (relative intensities of 1:1:2) were also present due to formation of the intermediate p-complexes A and B. The peak at d 0.15 ppm corresponds to the symmetrical intermediate B while the other two peaks arise from the presence of the unsymmetrical intermediate A. After 3 h at 25 °C the reaction mixture was dark purple/ red in color and the two resonances at d 0.24 and 0.10 ppm were present in a 1:1 ratio indicating that half the initial amount of 1 present had been converted to HN(SiMe3)2. The resonance at d 5.41 ppm was absent at this time. After 12 h at 25 °C the intense color of the reaction mixture had faded to dark yellow and small beads of mercury metal were visible in the bottom of the NMR tube. A mixture of the pentacyclic species 3a, the hexacylic species 4a, and the starting binaphthol 2a were present in solution as shown by 1H NMR spectroscopy. The hydroxyl and trimethylsilyl resonances of 2a were present at d 4.81 and 0.46 ppm. The –OH group of 3a resulted in a resonance at d 4.20 ppm, and two features at d 0.54 and 0.52 arising from the chemically and magnetically non-equivalent sets of –SiMe3 groups of 3a were also visible. The presence of 4a resulted in one feature at d 0.44 ppm arising from the 2 equivalent –SiMe3 groups. Integration of the peaks attributed to each individual species indicated that 2a, 3a, and 4a were present in approximately a 2:2:1 ratio. In a separate experiment, the reaction of 2 equiv. of 1 with 2a in C6D6 at 25 °C was monitored by 199Hg NMR spectroscopy. The 199Hg NMR spectrum of 1 contains a single resonance at d 992.4 ppm relative to Hg(CH3)2. The half-height linewidth (Dm1/2) of this feature is 242 Hz
A.E. Wetherby Jr. et al. / Inorganica Chimica Acta 360 (2007) 1977–1986
SiMe3
SiMe3
OH
1 +
1981
SiMe3
OH
OH
OH [(Me3Si)2N]HgO
[(Me3Si)2N]HgO
SiMe3
Me3Si
2a
H
Me3Si
A, π-complex
C, σ-complex
SiMe3
SiMe3
OHg[N(SiMe3)2] [(Me3Si)2N]HgO
[(Me3Si)2N]HgO Me3Si
H
H OHg[N(SiMe3)2]
Me3Si
B, π-complex
D, σ-complex
Scheme 3.
SiMe3 C
- HN(SiMe3)2
OH
Hg
- Hg
3a
O Me3Si E SiMe3 D
- 2 HN(SiMe3)2
O Hg
Hg
- 2 Hg
4a
O Me3Si F Scheme 4.
resulting from coupling of the 199Hg nucleus (I = 1/2) to the quadrupolar 14N nucleus (I = 1). The 199Hg NMR spectrum of the reaction mixture after 20 min exhibited a resonance for 1 as well as two sharper features at d 1408 ppm (Dm1/2 = 92 Hz) and d 1452 ppm (Dm1/2 = 95 Hz) in approximately equal intensities. The presence of these two peaks results from the formation of the two intermediates A and B (Scheme 3) which correlates with the related 1H NMR spectroscopic study. After 2 h, both of these resonances had decreased significantly in intensity, after 3 h both were only slightly visible above the baseline, and after 4 h both had disappeared. Similarly, the 199Hg NMR spectrum of the reaction of 1 equiv. of 1 with 2a in C6D6 at 25 °C after 20 min exhibits these same two resonances at d 1408 ppm (Dm1/2 =
102 Hz) and d 1452 ppm (Dm1/2 = 100 Hz). However, the intensity of the upfield peak at d 1452 ppm is approximately twice that of the feature at d 1408 ppm indicating the former is due to the monomercurated intermediate A. Both of these resonances are no longer visible after a reaction time of 4 h and additional spectra measured at regular 1 h intervals in reactions of 2a with both one or two equiv. of 1 over 24 h contained no additional spectral features. The proposed intermediates formed by the intramolecular reaction of the –OHg[N(SiMe3)2] moiety with the carbon center at the 9-position of the adjacent naphthyl ring are shown in Scheme 3 and are based on observations reported for a number of related systems. The first step in the two electrophilic aromatic substitution processes involves formation of two donor–acceptor complexes (pcomplexes) which are formed in an intermolecular fashion (A and B) that are responsible for the intense color observed during the initial phase of the reactions. Our spectroscopic studies suggest that the p-complexes A and B are present in solution for a few hours while they undergo slow conversion to the corresponding Wheland intermediates (r-complexes, C and D), which proceeds as expected since the conversion of a p-complex to a r-complex has been shown to be the slow step in several electrophilic aromatic substitution reactions [22–24]. The formation of these two types of complexes are known to occur in a stepwise fashion [23–27] and the properties of charge transfer p-complexes involving mercury(II) have been investigated [28,29]. The formation of radical ions is also possible in related processes but does not appear to occur in this case since irradiation by UV light is not required for the reaction to occur [30] and no magnetic anomalies were observed when probing these reactions by 1H NMR spectroscopy.
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Absorbance spectra of the intensely colored reaction mixtures of 2a–d and 2 equiv. of 1 were acquired after 1.5 h. In each case, an intense peak was observed at k 342 nm (2a), 345 nm (2b), 347 nm (2c), and 348 nm (2d) arising from the p-complexes A and B. These maxima exhibit a slight bathochromic shift as the number of phenyl groups attached to the silicon atom is increased. Upon their formation, the Wheland intermediates C and D presumably eliminate HN(SiMe3)2 in a rapid reaction to give the C–Hg–O fused species E and F which undergo extrusion of mercury metal resulting in formation of the interannular C–O bonds of 3a and 4a (Scheme 4). A similar process has been reported for several phenolic systems bearing O-vinylmercury substituents [31] as well as for systems employing fluorinated benzene [32] or alkenyl acetates [33] as reagents. Reactions of 1 with the more sterically encumbering binaphthols 2b (R = SiMe2Ph), 2c (R = SiMePh2), and 2d (R = SiPh3) proceed in an identical fashion to the reaction involving 2a (Schemes 1 and 2). The 1H NMR spectra obtained for the crude reaction products of 2b–d and 1 equiv. of 1 indicate the presence of a mixture of the pentacyclic derivatives 3b–d and the hexacylic species 4b–d in all cases as well as the starting materials 2b–d. For 3b the resonance for the hydroxyl proton appears at d 4.19 ppm and for 3c and 3d this feature appears at d 4.15 and 4.36 ppm (respectively). When 2 equiv. of 1 are reacted with binaphthols 2b–d no pentacyclic species are observed in the crude product mixture, the hexacyclic derivatives 4b–d are cleanly formed in each case, and no starting binaphthols 2b–d remain. The hexacyclic derivatives 4b–d were isolated in yields of 84% (4b), 85% (4c) and 49% (4d).
Fig. 4. ORTEP diagram of compound 4c. Thermal ellipsoids are drawn at 50% probability.
Recrystallization of these three compounds from hot benzene provided X-ray quality crystals of 4b and 4c while 4d could only be obtained as an amorphous powder. The ORTEP diagrams of 4b and 4c are shown in Figs. 3 and 4 and bond distances and angles for each are collected in Table 2. Like the structure of 4a, the six ring systems of both 4b and 4c are completely planar. The presence of increasingly bulky –SiR3 groups has very little effect on the overall structure of the hexacyclic ring system as the bond lengths and angles in 4a–c are all similar. The C–O bonds of 4a–c are substantially longer than the two intra˚ ) since cyclic C–O bonds of 3a (1.383(2) and 1.380(2) A
Table 3 UV–Vis data for PXX and 4a–d (in C6H6 solution)
Fig. 3. ORTEP diagram of compound 4b. Thermal ellipsoids are drawn at 50% probability.
kmax (nm)
log e
PXX
313 327 371 392 416 443
3.67 3.83 3.38 3.71 4.05 4.17
4b
281 293 321 335 404 428 457
4.25 4.17 3.74 3.92 3.72 4.09 4.22
4d
279 293 323 337 407 432 462
4.21 4.07 3.67 3.70 3.29 3.38 3.36
kmax (nm)
log e
4a
282 293 319 334 400 425 454
4.28 4.26 3.72 3.92 3.83 4.20 4.33
4c
278 293 322 337 406 431 460
4.15 4.06 3.63 3.83 3.58 3.96 4.10
A.E. Wetherby Jr. et al. / Inorganica Chimica Acta 360 (2007) 1977–1986
the hexacyclic ring system is planar which requires an elongated carbon–oxygen contact. The bulky trialkylsilyl substituents also result in longer C–O bonds in 4a–c versus ˚ ) [8]. Each of the the parent compound PXX (1.381(9) A structures of 4a–c contain individual molecules packed through a p-stacking interaction such that they are arranged into columns stacked along each of the three crystallographic axes, which results in the three individual columns being rotated 90° with respect to one another. The unsubstituted binaphthol 2e reacts with 2 equiv. of 1 to furnish peri-xanthenoxanthene (6,12-dioxaanthanthrene, PXX) in 79% yield as confirmed by 1H NMR and UV–Vis spectroscopy [34]. This species was originally obtained via the reaction of 1,1 0 -bi-2-naphthol with Cu(O2CCH3) in 52% yield [35] and has recently found significant technological applications (vide supra). Compounds 4a–d can be regarded as 1,7-disubstituted derivatives of PXX and absorbance data for 4a–d and PXX [34] are collected in Table 3. As expected, the structurally similar compounds 4a–c (and likely 4d) have very similar absorbance spectra which contain several pronounced absorbance bands resulting from p ! p* transitions (Fig. 5). These four spectra also closely resemble that of the parent compound PXX due to the similarity of their hexacyclic ring systems. The absorbance features of the functionalized derivatives 4a–d are red shifted relative to those of the parent PXX species and their absorbance maxima undergo a slight bathochromic shift with increasing steric bulk at the silicon atoms. Compounds 4a–d also fluoresce in solution and emission data are collected in Table 4. Compound 4a exhibits four well-defined emission maxima in the range 450–500 nm as well as an additional defined feature at 529 nm, while the
1983
Table 4 Fluorescence data for compounds 4a–d (in C6H6 solution) Compound
kexcitation
kemission
Compound
kexcitation
kemission
4a
334
452 471 483 500 529 566 (sh)
4b
335
452 482 515 534 573 (sh)
4c
337
459 489 517 537 (sh) 582 (sh)
4d
338
459 490 519 538 (sh) 583 (sh)
emission maxima of compounds 4b–d are slightly red shifted relative to those of 4a and these species lack the defined bands at 500 and 529 nm. Benzene solutions of all four compounds appear yellow–green in color when irradiated with a shortwave UVP lamp, and compounds 4c and 4d appear the most intensely yellow in color likely due to the larger number of phenyl groups attached to the silyl substituents. The lighter congeners of 1 M[N(SiMe3)2]2 (M = Zn, Cd) also react with binaphthol 2a but exhibit different reactivity. Similar to the mercury amide, reaction of 1 equiv. of Cd[N(SiMe3)2]2 with 2a furnishes both 3a and 4a as shown by 1H NMR spectroscopy. However, a resonance at d 5.16 ppm indicates the cadmium analog of the intermediate species A (Scheme 1) remains in solution even after heating the reaction mixture at 85 °C for 48 h. An intractable gelatinous precipitate also was formed in the reaction which likely is a polymeric cadmium/binaphthol species. Reaction of Cd[N(SiMe3)2]2 with 2 equiv. of 2a also results in the
Fig. 5. Absorbance spectra for compounds 4a–d.
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formation of an intractable polymeric material although some formation of 4a was observed by 1H NMR spectroscopy. The outcome of the reaction of Zn[N(SiMe3)2]2 with 2a is drastically different than that of its cadmium or mercury congeners. Regardless of the stoichiometry employed, the reaction of 2a with Zn[N(SiMe3)2]2 results in the formation of HOC20H10(OSiMe3)-2 0 -(SiMe3)2-3,3 0 , where a trimethylsilyl group has been transferred from the –N(SiMe3)2 ligand to one hydroxyl group of 2a. Other analogous metal(II) amides, including Ge[N(SiMe3)2]2 [36] and the group 2 and 14 compounds M[N(SiMe3)2]2 (M = Be, Mg, Ca, Sn, Pb), [37] also transfer a silyl group in this fashion to 2a. In conclusion, we have employed the mercury(II) amide Hg[N(SiMe3)2]2 (1) to promote single and double annulation reactions of 3,3 0 -disubstitituted-1,1 0 -bi-2-naphthols resulting in five new compounds which have been structurally characterized. Compound 1 also serves for the conversion of 1,1 0 -bi-2-naphthol to the useful species PXX. We have probed the mechanism of this interconversion and determined that the annulation reactions proceed via an intramolecular electrophilic aromatic substitution reaction. The four new hexacyclic species prepared in this study might be useful as components for conductive materials. 3. Experimental 3.1. General considerations Caution: All compounds containing mercury or cadmium should be regarded as extremely toxic. Proper personal protective equipment is essential when handling these materials. All air-sensitive compounds were manipulated using standard Schlenk, syringe, and glovebox techniques [38]. The starting materials 1 [21] and 2a–d [39] were prepared according to literature methods or slight variations thereof. Solvents were dried using a Glass Contour solvent purification system. 1H and 13C NMR spectra were recorded using a Varian Gemini 2000 instrument operating at 300 MHz (1H) or 75.5 MHz (13C), and 1H NMR spectral assignments for 4a–d are listed according to the numbering scheme in Fig. 6. 199Hg NMR spectra were recorded using H11
H12
R
H13
O
H14
H6
O
H5
R H4
H2
Fig. 6. Numbering scheme for the 1H NMR spectra of 4a–d.
a Varian Inova 400 instrument operating at 71.5 MHz and were referenced to a 1.0 M solution of Hg(NO3)2 in D2O set at d 2400 ppm (relative to neat Hg(CH3)2 at d 0 ppm) [40,41]. UV–Vis spectra were acquired employing blank benzene solutions using a Perkin Elmer Agilent UV–Vis spectroscopy system. Fluorescence spectra were acquired employing blank benzene solutions using a Horaba Fluorolog-3 instrument. Samples for GC/MS were run on a Shimadzu QP2010S instrument operating at 250 °C. Elemental analyses were conducted by Desert Analytics (Tucson, AZ). 3.2. Preparation of 3a To a solution of 1 (0.310 g, 0.594 mmol) in benzene (10 mL) in a Schlenk tube was added a solution of 2a (0.258 g, 0.599 mmol) in benzene (10 mL) under N2. The reaction mixture became dark yellow in color and turned dark purple/red after stirring for 2 h at 85 °C. Heating was continued for 12 h after which time the reaction mixture had become yellow in color and beads of mercury metal were visible in the reaction vessel. The Schlenk tube was opened in air, the reaction mixture was filtered through Celite and the volatiles were removed in vacuo to yield an orange/yellow solid. Recrystallization of the crude product from hot benzene (5 mL) furnished 3a (0.117 g, 45%) as transparent yellow crystals. 1H NMR (C6D6, 25 °C) d 7.87 (s, 1H, C18-H), 7.76 (s, 1H, C2-H), 7.63 (d, J = 8.4 Hz, 1H, C14-H), 7.38–7.19 (m, 4H, aromatics), 7.06 (t, J = 7.5 Hz, 1H, C15-H), 6.85 (d, J = 7.5 Hz, 1H, C16-H), 4.20 (s, 1H, –OH), 0.54 (s, 9H, –Si(CH3)3), 0.52 (s, 9H, –Si(CH3)3) ppm. 13C NMR (C6D6, 25 °C) d 136.9, 133.9, 130.5, 129.3, 128.2, 128.1, 127.9, 127.8, 127.5, 127.4, 127.3, 127.1, 124.7, 124.5, 124.2, 120.4, 119.6, 108.1, 10.1, 7.2, 0.6, 0.7 ppm. UV–Vis (C6H6, 25 °C): kmax 282, 293, 319, 334, 400, 425, 454 nm. Anal. Calc. for C26H29O2Si2: C, 72.70; H, 6.81. Found: C, 72.62; H, 6.69%. 3.3. Preparation of 4a To a solution of 1 (0.242 g, 0.465 mmol) in benzene (10 mL) was added a solution of 2a (0.100 g, 0.233 mmol) in benzene (10 mL) in a Schlenk tube under N2. The solution became dark yellow in color and was dark purple/red after stirring for 1 h at 85 °C. Heating was continued for an additional 24 h after which time the solution was green/yellow in color. The tube was opened in air, the reaction mixture was filtered through Celite, and the volatiles were removed in vacuo to yield a yellow solid which was recrystallized from hot benzene (5 mL) to furnish 4a (0.0967 g, 97%) as transparent yellow crystals. 1H NMR (C6D6, 25 °C) d 7.38 (s, 2H, 2,11-H), 6.89 (m, 4H, 4,12-H and 5,13-H), 6.47 (d, J = 7.2 Hz, 2H, 6,14-H), 0.44 (s, 18H, – Si(CH3)3) ppm. 13C NMR (C6D6, 25 °C) d 153.0, 132.3, 131.4, 129.1, 127.0, 122.9, 120.1, 111.0, 108.5, 1.3, 0.9 ppm. Anal. Calc. for C26H26O2 Si2: C, 73.21; H, 6.15. Found: C, 73.33; H, 6.21%.
A.E. Wetherby Jr. et al. / Inorganica Chimica Acta 360 (2007) 1977–1986
1985
13
3.4. Reaction of 3a with an additional equivalent of 1 To a solution of 3a (0.037 mg, 0.086 mmol) in benzene (5 mL) in a Schlenk tube was added a solution of 1 (0.045 g, 0.086 mmol) in benzene (5 mL) under N2. The tube was sealed and heated for 18 h at 85 °C. The tube was opened in air, the solution was filtered through Celite, and the volatiles were removed in vacuo to yield 4a (0.032 g, 86%). 3.5. Preparation of 3b/4b Compound 2b was reacted with 1 in an identical fashion as for 2a, using 2b (0.100 g, 0.180 mmol) and 1 (0.094 g, 0.180 mmol) resulting in a mixture of 3b and 4b as shown by 1H NMR spectroscopy. 3.6. Preparation of 3c/4c Compound 2c was reacted with 1 in an identical fashion as for 2a, using 2c (0.100 g, 0.147 mmol) and 1 (0.077 g, 0.148 mmol) resulting in a mixture of 3c and 4c as shown by 1H NMR spectroscopy. 3.7. Preparation of 3d/4d Compound 2d was reacted with 1 in an identical fashion as for 2a, using 2d (0.100 g, 0.125 mmol) and 1 (0.065 g, 0.125 mmol) resulting in a mixture of 3d and 4d as shown by 1H NMR spectroscopy.
C NMR (C6D6, 25 °C) d 137.8, 134.5, 133.4, 131.3, 129.4, 128.1, 127.6, 127.0, 123.0, 120.2, 111.1, 108.6, 102.6, 1.3, 2.1 ppm. 3.9. Preparation of 4c
Compound 4c was prepared in an analogous fashion as for 4a using 2c (0.250 g, 0.368 mmol) and 1 (0.384 g, 0.737 mmol). Yield of 4c: 0.213 g (85%). 1H NMR (C6D6, 25 °C) d 7.66–7.63 (m, 8H, –SiMePh2 meta-H), 7.47–7.30 (m, 18H, aromatics), 6.98 (s, 2H, 2,11-H), 1.01 (s, 6H, SiMePh2). 13C NMR (CDCl3, 25 °C) d 135.5, 135.2, 134.6, 134.3, 134.2, 129.9, 129.7, 128.1, 127.9, 127.8, 127.2, 120.4, 109.0, 1.3, 2.6 ppm. UV–Vis (C6H6, 25 °C): kmax 278, 293, 322, 337, 406, 431, 460 nm. Anal. Calc. for C46H34O2Si2: C, 81.87; H, 5.08. Found: C, 81.60; H, 5.54%. 3.10. Preparation of 4d Compound 4d was prepared in an analogous fashion as for 4a using 2d (0.250 g, 0.312 mmol) and 1 (0.325 g, 0.624 mmol). Yield of 4d: 0.121 g (49%). 1H NMR (CDCl3, 25 °C) d 7.85–7.63 (m, 12H, –SiPh3 meta-H), 7.61–7.10 (m, 26H, aromatics). 13C NMR (CDCl3, 25 °C) d 136.7, 136.0, 125.8, 135.7, 135.6, 135.4, 130.5, 130.3, 129.9, 129.6, 128.4, 128.2, 128.0, 1.4 ppm. UV–Vis (C6H6, 25 °C): kmax 279, 293, 323, 337, 407, 432, 462 nm. 3.11. Reaction of 1 with 2e
3.8. Preparation of 4b Compound 4b was prepared in an analogous fashion as for 4a using 2b (0.254 g, 0.368 mmol) and 1 (0.477 g, 0.737 mmol). Yield of 4c: 0.131 g (84%). 1H NMR (C6D6, 25 °C) d 7.65–7.63 (m, 4H, (m-C6H5)SiMe2), 7.34 (s, 2H, 2,11-H), 7.32–7.20 (m, 8H, (o-C6H5)SiMe2, (p-C6H5)SiMe2, and 4,12-H), 6.77 (d, J = 4.8 Hz, 2H, 6,14-H), 6.38 (t, J = 4.8 Hz, 2H, 5,13-H), 0.68 (s, 12H, –SiPh(CH3)2) ppm.
As for 4a, compound 1 (0.728 g, 1.40 mmol) and 1,1 0 -bi2-naphthol 2e (0.200 g, 0.699 mmol) were reacted to furnish peri-xanthenoxanthene (PXX, 0.156 g, 79%). 1H NMR (C6D6, 25 °C) d 6.88 (d, J = 9.0 Hz, 2H, H1), 6.81 (d, J = 4.8 Hz, 2H, H6), 6.80 (d, J = 3.6 Hz, 2H, H4), 6.69 (d, J = 9.0 Hz, 2H, H2), 6.56 (dd, J = 3.6 Hz, J = 4.8 Hz, 2H, H5) ppm. UV–Vis (C6H6, 25 °C): kmax 290, 313, 327, 392, 416, 443 nm.
Table 5 Crystallographic data for compounds 3a and 4a–c
Formula Space group ˚) a (A ˚) b (A ˚) c (A a (°) B (°) c (°) ˚ 3) V (A Z qcalc (g cm3) Temperature (K) Radiation ˚) Wavelength (A R Rw
3a
4a
4b
4c
C26H28O2Si2 P21/c 14.821(3) 12.578(3) 14.290(4) 90 115.47(1) 90 2404.9(1) 4 1.184 293 Mo Ka 0.71073 0.0473 0.1126
C26H26O2Si2 P21/c 6.6114(7) 8.5488(9) 20.676(2) 90 94.993(8) 90 1164.2(2) 2 1.217 293 Mo Ka 0.71073 0.0513 0.1504
C36H30O2Si2 P 1 8.3392(6) 9.3961(7) 10.1356(6) 70.071(4) 71.293(4) 73.480(4) 716.93(9) 1 1.276 293 Mo Ka 0.71073 0.0531 0.1078
C46H34O2Si2 Pbca 16.751(4) 12.492(3) 17.074(3) 90 90 90 3572.9(1) 4 1.258 293 Mo Ka 0.71073 0.059 0.1110
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3.12. Reaction of Cd[N(SiMe3)2]2 with 2a 3.12.1. Reaction using 1 equiv. Cd[N(SiMe3)2]2 A solution of Cd[N(SiMe3)2]2 (0.025 g, 0.0578 mmol) in C6D6 (0.3 mL) was added to a solution of 2a (0.025 g, 0.0580 mmol) in C6D6 (0.3 mL) and the progress of the reaction was monitored by 1H NMR spectroscopy. 3.12.2. Reaction using 2 equiv. Cd[N(SiMe3)2]2 A solution of Cd[N(SiMe3)2]2 (0.201 g, 0.464 mmol) in C6D6 (0.5 mL) was added to a solution of 2a (0.100 g, 0.232 mmol) in C6D6 (0.3 mL) and the progress of the reaction was monitored by 1H NMR spectroscopy. 3.13. X-ray structure determination Diffraction intensity data were collected with a Bruker SMART APEX II diffractometer. Crystallographic data and details of X-ray studies are shown in Table 5. Absorption corrections were applied for all data by SADABS. The structures were solved using direct methods, completed by difference Fourier syntheses, and refined by full matrix least squares procedures on F2. All non-hydrogen atoms were refined with anisotropic displacement coefficients and hydrogen atoms were treated as idealized contributions. All software and sources of scattering factors are contained in the SHEXTL (6.1) program package (G. Sheldrick, Bruker AXS, Madison, WI). ORTEP diagrams were drawn using the ORTEP3 program (L. J. Farrugia, Glasgow). Acknowledgements Funding for this work was provided by Oklahoma State University. A.E.W. gratefully acknowledges the assistance of Gianna Bell-Eunice (Oklahoma State University) for her assistance with the 199Hg NMR studies. Appendix A. Supplementary material CCDC 619634, 619635, 619636 and 619637 contain the supplementary crystallographic data for 3a, 4a, 4b and 4c. These data can be obtained free of charge via http:// www.ccdc.cam.ac.uk./conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or email: [email protected]. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.ica.2006.10.005. References [1] V. Ramamurthy, K.S. Schanze (Eds.), Solid State and Surface Photochemistry, CRC Press, New York, 2000. [2] T. Mori, H. Takeuchi, H. Fujikawa, J. Appl. Phys. 97 (2005) 066101. [3] C.D. Dimitrakopoulos, P.R.L. Malenfant, Adv. Mater. 14 (2002) 99.
[4] H. Klauk, M. Halik, U. Zschieschang, G. Schmid, W. Radlik, W. Weber, J. Appl. Phys. 92 (2002) 5259. [5] M.S. Deleuze, J. Chem. Phys. 116 (2002) 7012. [6] F. Do¨tz, J.D. Brand, S. Ito, L. Gherghel, K. Mu¨llen, J. Am. Chem. Soc. 122 (2000) 7707. [7] M. Mu¨ller, C. Ku¨bel, K. Mu¨llen, Chem. Eur. J. 4 (1998) 2099. [8] T. Asari, N. Kobayashi, T. Naito, T. Inabe, Bull. Chem. Soc. Jpn. 74 (2001) 53. [9] M. Hjorth, N. Thorup, P. Frederiksen, K. Bechgaard, Acta Chem. Scand. 48 (1994) 139. [10] T. Asari, M. Ishikawa, T. Naito, M. Matsuda, H. Tajima, T. Inabe, Chem. Lett. 34 (2005) 936. [11] T. Asari, T. Naito, T. Inabe, M. Matsuda, H. Tajima, Chem. Lett. 33 (2004) 128. [12] S. Takano, T. Naito, T. Inabe, Chem. Lett. (1998) 1249. [13] T. Inabe, T. Asari, H. Hasegawa, M. Matsuda, E.H. Gacho, N. Matsumura, S. Takeda, K. Takeda, T. Naito, Synth. Met. 133–134 (2003) 515. [14] T. Inabe, Mol. Cryst. Liq. Cryst. 376 (2002) 225. [15] M. Matsuda, T. Asari, T. Naito, T. Inabe, N. Hanasaki, H. Tajima, Bull. Chem. Soc. Jpn. 76 (2003) 1935. [16] M. Matsuda, N. Hanasaki, H. Tajima, T. Naito, T. Inabe, J. Chem. Phys. Solids 65 (2004) 749. [17] N. Hanasaki, M. Matsuda, H. Tajima, T. Naito, T. Inabe, Synth. Met. 133–134 (2003) 519. [18] A. Sugimoto, S. Kato, H. Inoue, E. Imoto, Bull. Chem. Soc. Jpn. 49 (1976) 337. [19] S. Doi, A. Fujita, S. Ikeura, T. Inabe, Y. Matsunaga, Bull. Chem. Soc. Jpn. 52 (1979) 2494. [20] K. Ikegami, Y. Matsunaga, K. Osafune, E. Osawa, Bull. Chem. Soc. Jpn. 48 (1975) 341. [21] H. Bu¨rger, W. Sawodny, U. Wannagat, J. Organomet. Chem. 3 (1965) 113. [22] T.M. Bockman, D. Kosynkin, J.K. Kochi, J. Org. Chem. 62 (1997) 5811. [23] S.M. Hubig, J.K. Kochi, J. Org. Chem. 65 (2000) 6807. [24] C. Boga, E. Del Vecchio, L. Forlani, Eur. J. Org. Chem. (2004) 1567. [25] S.M. Hubig, J.K. Kochi, J. Am. Chem. Soc. 122 (2000) 8279. [26] J.O. Morley, D.W. Roberts, J. Org. Chem. 62 (1997) 7358. [27] J.H. Atherton, R.B. Moodie, D.R. Noble, J. Chem. Soc., Perkin Trans. 2 (1999) 699. [28] W. Lau, J.K. Kochi, J. Org. Chem. 51 (1986) 1801. [29] W. Lau, J.K. Kochi, J. Am. Chem. Soc. 108 (1986) 6720. [30] R. Taylor, Electrophilic Aromatic Substitution, John Wiley & Sons, Chichester, 1991. [31] D.J. Foster, E. Tobler, J. Am. Chem. Soc. 83 (1961) 851. [32] R. Fields, R.N. Haszeldine, P.J. Palmer, Tetrahedron Lett. (1971) 1879. [33] D.J. Foster, E. Tobler, J. Org. Chem. 27 (1962) 834. [34] G.M. Blackburn, D.W. Cameron, H.W.-S. Chan, J. Chem. Soc. C (1966) 1836. [35] R. Pummerer, E. Prell, A. Rieche, Chem. Ber. 59 (1926) 2159. [36] C.S. Weinert, P.E. Fanwick, I.P. Rothwell, J. Chem. Soc., Dalton Trans. (2002) 2948. [37] A.E. Wetherby Jr., L.R. Goeller, C.K. Diedrich, C.S. Weinert, in preparation. [38] D.F. Shriver, M.A. Drezdzon, The Manipulation of Air Sensitive Compounds, 2nd ed., John Wiley and Sons, New York, 1986. [39] G.J.H. Buisman, L.A. van der Veen, A. Klootwijk, W.G.J. de Lange, P.C.J. Kamer, P.W.N.M. van Leeuwen, D. Vogt, Organometallics 16 (1997) 2929. [40] C. Brevard, P. Granger, Handbook of High Resolution Multinuclear NMR, John Wiley & Sons, New York, 1981. [41] M.A. Sens, N.K. Wilson, P.D. Ellis, J.D. Odom, J. Mag. Reson. 19 (1975) 323.
Reaction of bis(bis(trimethylsilyl)amido)mercury(II) with 3,3 0-disubstituted binaphthols: Cyclization via an intramolecular electrophilic aromatic substitution reaction Anthony E. Wetherby Jr., Stacy D. Benson, Charles S. Weinert
*
Department of Chemistry, Oklahoma State University, 316 Physical Science, Stillwater, OK 74078, United States Received 5 September 2006; accepted 14 October 2006 Available online 21 October 2006
Abstract Reaction of the mercury(II) amide Hg[N(SiMe3)3]2 with 3,3 0 -disubstituted binaphthols (HO)2C20H10(R)2-3,3 0 (R = SiMe3, SiMe2Ph, SiMePh2, SiPh3) in a 2:1 stoichiometric ratio furnishes four hexacyclic 1,7-disilylsubstituted derivatives of peri-xanthenoxanthene (PXX). Reaction of these two reagents in a 1:1 ratio results in a mixture of the hexacyclic products as well as the related pentacyclic species which contain one hydroxyl group and only one C–O–C ring fusion. The structures of three of the hexacyclic products (R = SiMe3, SiMe2Ph, SiMePh2) and one of the pentacyclic products (R = SiMe3) have been obtained. The reaction of Hg[N(SiMe3)3]2 with the 3,3 0 -disubstituted binaphthols proceeds via an intramolecular electrophilic aromatic substitution reaction and several intermediates in this process have been detected using NMR (1H and 199Hg) spectroscopy. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Mercury compounds; Electrophilic aromatic substitution; Mercury-199 NMR spectroscopy; X-ray crystal structures; Substituted binaphthols; Wheland intermediates; UV–Vis spectroscopy; Fluorescence spectroscopy
1. Introduction The synthesis of polycyclic aromatic and heteroaromatic compounds and their complexes is of interest due to their electronic properties and potential utility as organic conductors [1–7]. The long-known hetroaromatic species peri-xanthenoxanthene (6,12-dioxaanthanthrene, PXX) has recently been employed for the formation of charge transfer complexes involving organic [8,9] and inorganic species [8] and also in conductive salt complexes containing cobalt [8,10–14] and iron [15–17] phthalocyaninato ions. The utility of PXX and its derivatives as organic conductors [18–20] has also been investigated and derivatives of PXX have also been employed as ingredients in pigments. This hexacyclic species was originally prepared by the
*
Corresponding author. Tel.: +1 405 744 6543; fax: +1 405 744 6007. E-mail address: [email protected] (C.S. Weinert).
0020-1693/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2006.10.005
reaction of 1,1 0 -bi-2-naphthol with copper(II) acetate and synthetic methods for the preparation of substituted derivatives of PXX are not known. We have found that the sterically encumbered mercury(II) amide Hg[N(SiMe3)2]2 (1) [21] cleanly reacts with 1,1 0 -bi-2-naphthol to furnish PXX and also with 3,3 0 -disubstituted-1,1 0 -bi-2-naphthols to yield 1,7-disubstitued derivatives of PXX in high yield, the latter of which might find use in combination with inorganic complexes to furnish conductive materials. Using this method, we have prepared and characterized four disubstituted silyl derivatives of PXX and have probed the reaction pathway using NMR (1H and 199Hg) spectroscopy. 2. Results and discussion The mercury(II) amide Hg[N(SiMe3)2]2 (1) reacts with the 3,3 0 -disubstituted binaphthols (2a–d) and also the parent 1,1 0 -bi-2-naphthol (2e) to furnish pentacyclic or hexacyclic fused species depending on the reaction stoichiometry
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(Schemes 1 and 2). The reaction occurs via an intramolecular electrophilic aromatic substitution reaction involving mercuration of the hydroxyl groups followed by attack at the 9-position of the adjacent naphthyl ring and subsequent extrusion of elemental mercury. The reaction of 1 equiv. of 1 and 2a in benzene on a preparative scale was carried out at 85 °C over 12 h. The reaction mixture became dark yellow upon initial addition of a solution of 2a to a solution of 1 and after heating for 5 min the reaction mixture was dark purple/red in color. After 12 h the solution had become green/yellow in color and beads of mercury metal were clearly visible at the bottom of the reaction vessel. Filtration of the reaction mixture in air and removal of the solvent in vacuo yielded an orange/yellow solid. The 1H NMR spectrum of the crude product exhibited four resonances in the –SiMe3 region at d 0.54, 0.52, 0.46, 0.44 ppm indicating the presence of 2a (d 0.46 ppm) and two other species. Recrystallization of the crude material from a hot benzene solution furnished the pentacyclic compound 3a in
SiMe3
˚ , respectively) are nearly identical to the exocy1.380(2) A ˚ . The five-ring clic O(2)–C(20) bond distance of 1.378(2) A system of 3a is puckered rather than planar, as shown by the angles of 6.64° and 4.44° in the central OC5 ring about O(1)–C(10)–C(9)–C(11) and O(1)–C(13)–C(12)–C(11), respectively. Further recrystallization of the mother liquor furnished crystals which differed in appearance from those of 3a and were found to be the hexacyclic compound 4a using X-ray diffraction. An ORTEP diagram of 4a is shown in Fig. 2 and bond distances and angles are collected in Table 2. ˚ , which are substanThe C–O distances in 4a are 1.393(3) A tially elongated relative to those of 3a, and the overall sixring system in 4a is completely planar. Compound 4a is highly symmetric with the two halves of the molecule being interrelated by a center of inversion. Reaction of an additional equivalent of 1 with 3a at 85 °C results in quantitative conversion of 3a to 4a after 18 h as shown by 1H NMR spectroscopy. A preparative scale reaction under the same conditions furnishes 4a in 85% yield as shown in Eq. (1)
SiMe3
OH
O
1 eq. Hg[N(SiMe3)2]2 (1) C6H6, 24 h, 85 oC
O Me3Si
+ 2 HN(SiMe3)2 + Hg
O
ð1Þ
Me3Si 4a
3a
85 %
37% yield as yellow crystals. The identity of 3a was determined using NMR (1H and 13C) spectroscopy and elemental analysis and the X-ray crystal structure of 3a was also obtained to confirm its identity. An ORTEP diagram of 3a shown in Fig. 1 and bond distances and angles are collected in Table 1. The intracyclic C–O bond distances of 3a between O(1) and C(10) and O(1) and C(13) (1.383(2) and
R
R
OH
1 eq. Hg[N(SiMe3)2]2 (1)
OH
C6H6, 24 h, 85 oC
R 2a R = SiMe3 2b R = SiMe2Ph 2c R = SiMePh2 2d R = SiPh3 2e R = H
Both 3a and 4a were further characterized by NMR spectroscopy and elemental analysis. The 1H NMR spectrum of 3a exhibits a resonance at d 4.20 ppm arising from the single hydroxyl group and two features at d 0.54 and 0.52 ppm corresponding to the two non-equivalent –SiMe3 groups. The 13C NMR spectrum of 3a contains the expected 22 resonances with two signals at d 0.6 and d
OH O R 3a 3b 3c 3d 3e
R
+
O O R
R = SiMe3 R = SiMe2Ph R = SiMePh2 R = SiPh3 R=H
Scheme 1.
4a 4b 4c 4d 4e
R = SiMe3 R = SiMe2Ph R = SiMePh2 R = SiPh3 R = H (PPX)
+ 2 HN(SiMe3)2 + Hg
A.E. Wetherby Jr. et al. / Inorganica Chimica Acta 360 (2007) 1977–1986
R OH OH
R 2 eq. Hg[N(SiMe3)2]2 (1) C6H6, 24 h, 85 oC
O O
+ 4 HN(SiMe3)2 + 2 Hg
R
R 2a 2b 2c 2d 2e
1979
R = SiMe3 R = SiMe2Ph R = SiMePh2 R = SiPh3 R=H
4a 4b 4c 4d 4e
R = SiMe3 R = SiMe2Ph R = SiMePh2 R = SiPh3 R = H (PXX)
Scheme 2.
Table 1 ˚ ) and angles (°) for compound 3a Selected bond distances (A O(1)–C(10) O(1)–C(13) O(2)–C(20) C(1)–C(2) C(1)–C(10) C(2)–C(3) C(3)–C(4) C(3)–C(8) C(4)–C(5) C(5)–C(6) C(6)–C(7) C(7)–C(8) C(8)–C(9) C(9)–C(10)
Fig. 1. ORTEP diagram of compound 3a. Thermal ellipsoids are drawn at 50% probability.
0.7 arising from the trimethylsilyl groups and a signal at d 120.4 corresponding to the carbon atom attached to the hydroxyl group. The 1H and 13C NMR spectra of 4a exhibit single resonances at d 0.44 and 0.9 ppm (respectively) attributable to the symmetry-related trimethylsilyl groups. The 13C NMR spectrum of 4a contains ten additional features for the ring carbons with two distinct features at d 153.0 and 111.0 ppm attributable to the oxygen bound atoms C(7) and C(10), respectively. Analysis of the crude product mixture obtained from the reaction of 2a with one and two equiv. of 1 by GC/MS also confirms the formation of a mixture of 3a and 4a. The chromatogram resulting from the crude product obtained using 2 equiv. of 1 (Scheme 2) contained a single peak with a retention time of 95.5 min. The base peak in the mass spectrum of the eluted material appeared at m/z = 426 and a feature at m/z = 428 corresponding to the parent ion of 4a was also visible. A fragmentation pattern corresponding to sequential loss of all six methyl groups was
O(1)–C(10)–C(1) O(1)–C(13)–C(14) O(2)–C(20)–C(19) Si(1)–C(19)–C(20) Si(2)–C(1)–C(10) C(1)–C(2)–C(3) C(2)–C(3)–C(4) C(2)–C(3)–C(8) C(3)–C(4)–C(5) C(3)–C(8)–C(9) C(4)–C(5)–C(6) C(5)–C(6)–C(7) C(6)–C(7)–C(8) C(7)–C(8)–C(8) C(7)–C(8)–C(3) C(8)–C(3)–C(4) C(8)–C(9)–C(10) C(8)–C(9)–C(11) C(9)–C(10)–C(1) C(9)–C(10)–O(1) C(9)–C(11)–C(12) C(9)–C(11)–C(20)
1.383(2) 1.380(2) 1.378(2) 1.373(3) 1.416(3) 1.411(3) 1.412(3) 1.421(3) 1.343(4) 1.380(4) 1.381(3) 1.412(3) 1.447(2) 1.380(3) 113.1(2) 117.5(2) 112.9(2) 119.2(2) 121.1(2) 122.8(2) 121.4(2) 119.4(2) 121.6(2) 118.9(2) 119.9(2) 121.1(2) 120.5(2) 117.5(2) 123.4(2) 119.1(2) 116.5(2) 124.8(2) 125.2(2) 121.7(2) 116.1(2) 127.7(2)
C(9)–C(11) Si(1)–C(19) Si(2)–C(1) C(11)–C(12) C(11)–C(20) C(12)–C(13) C(12)–C(17) C(13)–C(14) C(14)–C(15) C(15)–C(16) C(16)–C(17) C(17)–C(18) C(18)–C(19) C(19)–C(20) O(1)–C(13)–C(12) O(2)–C(20)–C(11) Si(1)–C(19)–C(18) Si(2)–C(1)–C(2) C(10)–C(1)–C(2) C(10)–C(9)–C(11) C(11)–C(12)–C(13) C(11)–C(12)–C(17) C(12)–C(13)–C(14) C(12)–C(17)–C(16) C(12)–C(17)–C(18) C(13)–O(1)–C(10) C(13)–C(12)–C(17) C(13)–C(14)–C(15) C(14)–C(15)–C(16) C(15)–C(16)–C(17) C(16)–C(17)–C(18) C(17)–C(18)–C(19) C(18)–C(19)–C(20) C(19)–C(20)–C(11) C(20)–C(11)–C(12)
1.473(2) 1.883(2) 1.882(2) 1.428(2) 1.386(2) 1.404(2) 1.414(2) 1.367(3) 1.401(3) 1.355(3) 1.420(3) 1.413(3) 1.371(3) 1.425(3) 120.0(2) 124.6(2) 122.8(2) 122.8(2) 116.0(2) 118.4(2) 120.1(2) 121.9(2) 122.3(2) 119.1(2) 117.4(2) 119.6(2) 117.8(2) 119.3(2) 120.7(2) 120.7(2) 123.4(2) 122.3(2) 118.0(2) 122.6(2) 116.0(2)
also present. The chromatogram obtained using 1 equiv. of 1 (Scheme 1) exhibited two features having retention times of 29.8 and 95.2 min. The mass spectrum of the material eluted first exhibits a base peak at m/z = 430 corresponding to the parent ion of 3a and a second feature at m/z = 398 resulting from loss of two oxygen atoms. Peaks
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Fig. 2. ORTEP diagram of compound 4a. Thermal ellipsoids are drawn at 50% probability.
Table 2 ˚ ) and angles (°) for compounds 4a–c Selected bond distances (A 4a O(1)–C(10) O(1 0 )–C(7) Si(1)–C(1) C(1)–C(2) C(1)–C(10) C(2)–C(3) C(3)–C(4) C(3)–C(8) C(4)–C(5) C(5)–C(6) C(6)–C(7) C(7)–C(8) C(8)–C(9) C(9)–C(9 0 ) C(9)–C(10) O(1)–C(10)–C(1) O(1)–C(10)–C(9) O(1 0 )–C(7)–C(6) O(1 0 )–C(7)–C(8) Si(1)–C(1)–C(2) Si(1)–C(1)–C(10) C(1)–C(2)–C(3) C(2)–C(3)–C(4) C(2)–C(3)–C(8) C(3)–C(4)–C(5) C(3)–C(8)–C(7) C(3)–C(8)–C(9) C(4)–C(5)–C(6) C(4)–C(3)–C(8) C(5)–C(6)–C(7) C(6)–C(7)–C(8) C(7)–C(8)–C(9) C(8)–C(9)–C(10) C(8)–C(9)–C(9 0 ) C(9)–C(10)–C(1) C(10)–C(1)–C(2) C(10)–C(9)–C(9 0 ) C(10)–O(1 0 )–C(7 0 )
1.394(3) 1.393(3) 1.888(3) 1.386(4) 1.419(4) 1.419(4) 1.417(4) 1.417(4) 1.358(5) 1.407(5) 1.358(4) 1.404(4) 1.404(4) 1.439(5) 1.366(4) 116.9(3) 121.2(2) 118.0(3) 120.8(2) 123.0(2) 120.8(2) 124.3(3) 125.8(3) 117.1(3) 120.8(3) 120.6(3) 119.2(3) 121.9(3) 117.0(3) 118.5(3) 121.2(3) 120.2(3) 121.4(3) 117.8(3) 121.9(3) 116.0(3) 120.8(3) 119.2(2)
4b 1.416(2) 1.402(2) 1.896(2) 1.384(2) 1.416(2) 1.427(2) 1.408(2) 1.411(2) 1.365(2) 1.401(2) 1.344(2) 1.417(2) 1.398(2) 1.440(3) 1.372(2) 117.3(2) 120.4(2) 120.7(2) 118.5(2) 121.9(2) 122.2(2) 124.5(2) 125.2(2) 116.3(2) 119.9(2) 119.6(2) 120.5(2) 121.7(2) 118.4(2) 119.5(2) 120.8(2) 119.9(2) 120.5(2) 118.1(2) 122.3(2) 115.9(2) 121.4(2) 119.6(2)
4c 1.399(3) 1.402(3) 1.879(3) 1.394(3) 1.416(3) 1.422(3) 1.408(3) 1.415(3) 1.363(4) 1.407(3) 1.356(3) 1.395(3) 1.405(3) 1.439(5) 1.362(3) 116.6(2) 120.6(2) 117.6(2) 121.1(2) 122.7(2) 121.9(2) 124.4(2) 125.3(2) 116.8(2) 120.0(2) 120.2(2) 119.7(2) 121.9(3) 118.0(2) 118.6(3) 121.3(2) 120.1(2) 120.9(2) 117.7(3) 122.8(2) 115.4(2) 121.4(3) 119.1(2)
resulting from fragmentation of all six methyl groups of 3a are also clearly visible. The mass spectrum of the material eluting at 95.2 min is identical to that obtained for 4a, and GC/MS analysis of the product prepared according to Eq. (1) also indicates the presence of only 4a. In order to probe the reaction pathway involved in the formation of 3a and 4a a 1:1 stoichiometric amount of 1 and 2a were combined in C6D6 and the progress of the reaction was monitored by 1H NMR spectroscopy at 25 °C. A proposed reaction pathway is illustrated in Schemes 3 and 4. After 5 min the reaction mixture had become intensely colored and a resonance at d 5.41 ppm was clearly visible. This is shifted downfield from the hydroxyl resonance of 2a (d 4.81 ppm) and the integrated intensity of the new feature was approximately one-third that of the –OH peak of 2a. The feature at d 5.41 ppm is due to formation of the intermediate p-complex A which results from displacement of one –N(SiMe3)2 ligand from 1 upon reaction with a single –OH group of 2a. The alkylsilyl region of the 1H NMR spectrum contained three intense features at this time including one for the –SiMe3 groups of 1 at d 0.24 ppm, a second feature at d 0.46 ppm due to the –SiMe3 groups of 2a, and a third feature at d 0.10 ppm corresponding to HN(SiMe3)2 generated in the reaction. The integrated intensity ratio of the peaks corresponding to 1 and HN(SiMe3)2 was approximately 2:1. Three less intense peaks at d 0.61, 0.04, and 0.15 ppm (relative intensities of 1:1:2) were also present due to formation of the intermediate p-complexes A and B. The peak at d 0.15 ppm corresponds to the symmetrical intermediate B while the other two peaks arise from the presence of the unsymmetrical intermediate A. After 3 h at 25 °C the reaction mixture was dark purple/ red in color and the two resonances at d 0.24 and 0.10 ppm were present in a 1:1 ratio indicating that half the initial amount of 1 present had been converted to HN(SiMe3)2. The resonance at d 5.41 ppm was absent at this time. After 12 h at 25 °C the intense color of the reaction mixture had faded to dark yellow and small beads of mercury metal were visible in the bottom of the NMR tube. A mixture of the pentacyclic species 3a, the hexacylic species 4a, and the starting binaphthol 2a were present in solution as shown by 1H NMR spectroscopy. The hydroxyl and trimethylsilyl resonances of 2a were present at d 4.81 and 0.46 ppm. The –OH group of 3a resulted in a resonance at d 4.20 ppm, and two features at d 0.54 and 0.52 arising from the chemically and magnetically non-equivalent sets of –SiMe3 groups of 3a were also visible. The presence of 4a resulted in one feature at d 0.44 ppm arising from the 2 equivalent –SiMe3 groups. Integration of the peaks attributed to each individual species indicated that 2a, 3a, and 4a were present in approximately a 2:2:1 ratio. In a separate experiment, the reaction of 2 equiv. of 1 with 2a in C6D6 at 25 °C was monitored by 199Hg NMR spectroscopy. The 199Hg NMR spectrum of 1 contains a single resonance at d 992.4 ppm relative to Hg(CH3)2. The half-height linewidth (Dm1/2) of this feature is 242 Hz
A.E. Wetherby Jr. et al. / Inorganica Chimica Acta 360 (2007) 1977–1986
SiMe3
SiMe3
OH
1 +
1981
SiMe3
OH
OH
OH [(Me3Si)2N]HgO
[(Me3Si)2N]HgO
SiMe3
Me3Si
2a
H
Me3Si
A, π-complex
C, σ-complex
SiMe3
SiMe3
OHg[N(SiMe3)2] [(Me3Si)2N]HgO
[(Me3Si)2N]HgO Me3Si
H
H OHg[N(SiMe3)2]
Me3Si
B, π-complex
D, σ-complex
Scheme 3.
SiMe3 C
- HN(SiMe3)2
OH
Hg
- Hg
3a
O Me3Si E SiMe3 D
- 2 HN(SiMe3)2
O Hg
Hg
- 2 Hg
4a
O Me3Si F Scheme 4.
resulting from coupling of the 199Hg nucleus (I = 1/2) to the quadrupolar 14N nucleus (I = 1). The 199Hg NMR spectrum of the reaction mixture after 20 min exhibited a resonance for 1 as well as two sharper features at d 1408 ppm (Dm1/2 = 92 Hz) and d 1452 ppm (Dm1/2 = 95 Hz) in approximately equal intensities. The presence of these two peaks results from the formation of the two intermediates A and B (Scheme 3) which correlates with the related 1H NMR spectroscopic study. After 2 h, both of these resonances had decreased significantly in intensity, after 3 h both were only slightly visible above the baseline, and after 4 h both had disappeared. Similarly, the 199Hg NMR spectrum of the reaction of 1 equiv. of 1 with 2a in C6D6 at 25 °C after 20 min exhibits these same two resonances at d 1408 ppm (Dm1/2 =
102 Hz) and d 1452 ppm (Dm1/2 = 100 Hz). However, the intensity of the upfield peak at d 1452 ppm is approximately twice that of the feature at d 1408 ppm indicating the former is due to the monomercurated intermediate A. Both of these resonances are no longer visible after a reaction time of 4 h and additional spectra measured at regular 1 h intervals in reactions of 2a with both one or two equiv. of 1 over 24 h contained no additional spectral features. The proposed intermediates formed by the intramolecular reaction of the –OHg[N(SiMe3)2] moiety with the carbon center at the 9-position of the adjacent naphthyl ring are shown in Scheme 3 and are based on observations reported for a number of related systems. The first step in the two electrophilic aromatic substitution processes involves formation of two donor–acceptor complexes (pcomplexes) which are formed in an intermolecular fashion (A and B) that are responsible for the intense color observed during the initial phase of the reactions. Our spectroscopic studies suggest that the p-complexes A and B are present in solution for a few hours while they undergo slow conversion to the corresponding Wheland intermediates (r-complexes, C and D), which proceeds as expected since the conversion of a p-complex to a r-complex has been shown to be the slow step in several electrophilic aromatic substitution reactions [22–24]. The formation of these two types of complexes are known to occur in a stepwise fashion [23–27] and the properties of charge transfer p-complexes involving mercury(II) have been investigated [28,29]. The formation of radical ions is also possible in related processes but does not appear to occur in this case since irradiation by UV light is not required for the reaction to occur [30] and no magnetic anomalies were observed when probing these reactions by 1H NMR spectroscopy.
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Absorbance spectra of the intensely colored reaction mixtures of 2a–d and 2 equiv. of 1 were acquired after 1.5 h. In each case, an intense peak was observed at k 342 nm (2a), 345 nm (2b), 347 nm (2c), and 348 nm (2d) arising from the p-complexes A and B. These maxima exhibit a slight bathochromic shift as the number of phenyl groups attached to the silicon atom is increased. Upon their formation, the Wheland intermediates C and D presumably eliminate HN(SiMe3)2 in a rapid reaction to give the C–Hg–O fused species E and F which undergo extrusion of mercury metal resulting in formation of the interannular C–O bonds of 3a and 4a (Scheme 4). A similar process has been reported for several phenolic systems bearing O-vinylmercury substituents [31] as well as for systems employing fluorinated benzene [32] or alkenyl acetates [33] as reagents. Reactions of 1 with the more sterically encumbering binaphthols 2b (R = SiMe2Ph), 2c (R = SiMePh2), and 2d (R = SiPh3) proceed in an identical fashion to the reaction involving 2a (Schemes 1 and 2). The 1H NMR spectra obtained for the crude reaction products of 2b–d and 1 equiv. of 1 indicate the presence of a mixture of the pentacyclic derivatives 3b–d and the hexacylic species 4b–d in all cases as well as the starting materials 2b–d. For 3b the resonance for the hydroxyl proton appears at d 4.19 ppm and for 3c and 3d this feature appears at d 4.15 and 4.36 ppm (respectively). When 2 equiv. of 1 are reacted with binaphthols 2b–d no pentacyclic species are observed in the crude product mixture, the hexacyclic derivatives 4b–d are cleanly formed in each case, and no starting binaphthols 2b–d remain. The hexacyclic derivatives 4b–d were isolated in yields of 84% (4b), 85% (4c) and 49% (4d).
Fig. 4. ORTEP diagram of compound 4c. Thermal ellipsoids are drawn at 50% probability.
Recrystallization of these three compounds from hot benzene provided X-ray quality crystals of 4b and 4c while 4d could only be obtained as an amorphous powder. The ORTEP diagrams of 4b and 4c are shown in Figs. 3 and 4 and bond distances and angles for each are collected in Table 2. Like the structure of 4a, the six ring systems of both 4b and 4c are completely planar. The presence of increasingly bulky –SiR3 groups has very little effect on the overall structure of the hexacyclic ring system as the bond lengths and angles in 4a–c are all similar. The C–O bonds of 4a–c are substantially longer than the two intra˚ ) since cyclic C–O bonds of 3a (1.383(2) and 1.380(2) A
Table 3 UV–Vis data for PXX and 4a–d (in C6H6 solution)
Fig. 3. ORTEP diagram of compound 4b. Thermal ellipsoids are drawn at 50% probability.
kmax (nm)
log e
PXX
313 327 371 392 416 443
3.67 3.83 3.38 3.71 4.05 4.17
4b
281 293 321 335 404 428 457
4.25 4.17 3.74 3.92 3.72 4.09 4.22
4d
279 293 323 337 407 432 462
4.21 4.07 3.67 3.70 3.29 3.38 3.36
kmax (nm)
log e
4a
282 293 319 334 400 425 454
4.28 4.26 3.72 3.92 3.83 4.20 4.33
4c
278 293 322 337 406 431 460
4.15 4.06 3.63 3.83 3.58 3.96 4.10
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the hexacyclic ring system is planar which requires an elongated carbon–oxygen contact. The bulky trialkylsilyl substituents also result in longer C–O bonds in 4a–c versus ˚ ) [8]. Each of the the parent compound PXX (1.381(9) A structures of 4a–c contain individual molecules packed through a p-stacking interaction such that they are arranged into columns stacked along each of the three crystallographic axes, which results in the three individual columns being rotated 90° with respect to one another. The unsubstituted binaphthol 2e reacts with 2 equiv. of 1 to furnish peri-xanthenoxanthene (6,12-dioxaanthanthrene, PXX) in 79% yield as confirmed by 1H NMR and UV–Vis spectroscopy [34]. This species was originally obtained via the reaction of 1,1 0 -bi-2-naphthol with Cu(O2CCH3) in 52% yield [35] and has recently found significant technological applications (vide supra). Compounds 4a–d can be regarded as 1,7-disubstituted derivatives of PXX and absorbance data for 4a–d and PXX [34] are collected in Table 3. As expected, the structurally similar compounds 4a–c (and likely 4d) have very similar absorbance spectra which contain several pronounced absorbance bands resulting from p ! p* transitions (Fig. 5). These four spectra also closely resemble that of the parent compound PXX due to the similarity of their hexacyclic ring systems. The absorbance features of the functionalized derivatives 4a–d are red shifted relative to those of the parent PXX species and their absorbance maxima undergo a slight bathochromic shift with increasing steric bulk at the silicon atoms. Compounds 4a–d also fluoresce in solution and emission data are collected in Table 4. Compound 4a exhibits four well-defined emission maxima in the range 450–500 nm as well as an additional defined feature at 529 nm, while the
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Table 4 Fluorescence data for compounds 4a–d (in C6H6 solution) Compound
kexcitation
kemission
Compound
kexcitation
kemission
4a
334
452 471 483 500 529 566 (sh)
4b
335
452 482 515 534 573 (sh)
4c
337
459 489 517 537 (sh) 582 (sh)
4d
338
459 490 519 538 (sh) 583 (sh)
emission maxima of compounds 4b–d are slightly red shifted relative to those of 4a and these species lack the defined bands at 500 and 529 nm. Benzene solutions of all four compounds appear yellow–green in color when irradiated with a shortwave UVP lamp, and compounds 4c and 4d appear the most intensely yellow in color likely due to the larger number of phenyl groups attached to the silyl substituents. The lighter congeners of 1 M[N(SiMe3)2]2 (M = Zn, Cd) also react with binaphthol 2a but exhibit different reactivity. Similar to the mercury amide, reaction of 1 equiv. of Cd[N(SiMe3)2]2 with 2a furnishes both 3a and 4a as shown by 1H NMR spectroscopy. However, a resonance at d 5.16 ppm indicates the cadmium analog of the intermediate species A (Scheme 1) remains in solution even after heating the reaction mixture at 85 °C for 48 h. An intractable gelatinous precipitate also was formed in the reaction which likely is a polymeric cadmium/binaphthol species. Reaction of Cd[N(SiMe3)2]2 with 2 equiv. of 2a also results in the
Fig. 5. Absorbance spectra for compounds 4a–d.
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formation of an intractable polymeric material although some formation of 4a was observed by 1H NMR spectroscopy. The outcome of the reaction of Zn[N(SiMe3)2]2 with 2a is drastically different than that of its cadmium or mercury congeners. Regardless of the stoichiometry employed, the reaction of 2a with Zn[N(SiMe3)2]2 results in the formation of HOC20H10(OSiMe3)-2 0 -(SiMe3)2-3,3 0 , where a trimethylsilyl group has been transferred from the –N(SiMe3)2 ligand to one hydroxyl group of 2a. Other analogous metal(II) amides, including Ge[N(SiMe3)2]2 [36] and the group 2 and 14 compounds M[N(SiMe3)2]2 (M = Be, Mg, Ca, Sn, Pb), [37] also transfer a silyl group in this fashion to 2a. In conclusion, we have employed the mercury(II) amide Hg[N(SiMe3)2]2 (1) to promote single and double annulation reactions of 3,3 0 -disubstitituted-1,1 0 -bi-2-naphthols resulting in five new compounds which have been structurally characterized. Compound 1 also serves for the conversion of 1,1 0 -bi-2-naphthol to the useful species PXX. We have probed the mechanism of this interconversion and determined that the annulation reactions proceed via an intramolecular electrophilic aromatic substitution reaction. The four new hexacyclic species prepared in this study might be useful as components for conductive materials. 3. Experimental 3.1. General considerations Caution: All compounds containing mercury or cadmium should be regarded as extremely toxic. Proper personal protective equipment is essential when handling these materials. All air-sensitive compounds were manipulated using standard Schlenk, syringe, and glovebox techniques [38]. The starting materials 1 [21] and 2a–d [39] were prepared according to literature methods or slight variations thereof. Solvents were dried using a Glass Contour solvent purification system. 1H and 13C NMR spectra were recorded using a Varian Gemini 2000 instrument operating at 300 MHz (1H) or 75.5 MHz (13C), and 1H NMR spectral assignments for 4a–d are listed according to the numbering scheme in Fig. 6. 199Hg NMR spectra were recorded using H11
H12
R
H13
O
H14
H6
O
H5
R H4
H2
Fig. 6. Numbering scheme for the 1H NMR spectra of 4a–d.
a Varian Inova 400 instrument operating at 71.5 MHz and were referenced to a 1.0 M solution of Hg(NO3)2 in D2O set at d 2400 ppm (relative to neat Hg(CH3)2 at d 0 ppm) [40,41]. UV–Vis spectra were acquired employing blank benzene solutions using a Perkin Elmer Agilent UV–Vis spectroscopy system. Fluorescence spectra were acquired employing blank benzene solutions using a Horaba Fluorolog-3 instrument. Samples for GC/MS were run on a Shimadzu QP2010S instrument operating at 250 °C. Elemental analyses were conducted by Desert Analytics (Tucson, AZ). 3.2. Preparation of 3a To a solution of 1 (0.310 g, 0.594 mmol) in benzene (10 mL) in a Schlenk tube was added a solution of 2a (0.258 g, 0.599 mmol) in benzene (10 mL) under N2. The reaction mixture became dark yellow in color and turned dark purple/red after stirring for 2 h at 85 °C. Heating was continued for 12 h after which time the reaction mixture had become yellow in color and beads of mercury metal were visible in the reaction vessel. The Schlenk tube was opened in air, the reaction mixture was filtered through Celite and the volatiles were removed in vacuo to yield an orange/yellow solid. Recrystallization of the crude product from hot benzene (5 mL) furnished 3a (0.117 g, 45%) as transparent yellow crystals. 1H NMR (C6D6, 25 °C) d 7.87 (s, 1H, C18-H), 7.76 (s, 1H, C2-H), 7.63 (d, J = 8.4 Hz, 1H, C14-H), 7.38–7.19 (m, 4H, aromatics), 7.06 (t, J = 7.5 Hz, 1H, C15-H), 6.85 (d, J = 7.5 Hz, 1H, C16-H), 4.20 (s, 1H, –OH), 0.54 (s, 9H, –Si(CH3)3), 0.52 (s, 9H, –Si(CH3)3) ppm. 13C NMR (C6D6, 25 °C) d 136.9, 133.9, 130.5, 129.3, 128.2, 128.1, 127.9, 127.8, 127.5, 127.4, 127.3, 127.1, 124.7, 124.5, 124.2, 120.4, 119.6, 108.1, 10.1, 7.2, 0.6, 0.7 ppm. UV–Vis (C6H6, 25 °C): kmax 282, 293, 319, 334, 400, 425, 454 nm. Anal. Calc. for C26H29O2Si2: C, 72.70; H, 6.81. Found: C, 72.62; H, 6.69%. 3.3. Preparation of 4a To a solution of 1 (0.242 g, 0.465 mmol) in benzene (10 mL) was added a solution of 2a (0.100 g, 0.233 mmol) in benzene (10 mL) in a Schlenk tube under N2. The solution became dark yellow in color and was dark purple/red after stirring for 1 h at 85 °C. Heating was continued for an additional 24 h after which time the solution was green/yellow in color. The tube was opened in air, the reaction mixture was filtered through Celite, and the volatiles were removed in vacuo to yield a yellow solid which was recrystallized from hot benzene (5 mL) to furnish 4a (0.0967 g, 97%) as transparent yellow crystals. 1H NMR (C6D6, 25 °C) d 7.38 (s, 2H, 2,11-H), 6.89 (m, 4H, 4,12-H and 5,13-H), 6.47 (d, J = 7.2 Hz, 2H, 6,14-H), 0.44 (s, 18H, – Si(CH3)3) ppm. 13C NMR (C6D6, 25 °C) d 153.0, 132.3, 131.4, 129.1, 127.0, 122.9, 120.1, 111.0, 108.5, 1.3, 0.9 ppm. Anal. Calc. for C26H26O2 Si2: C, 73.21; H, 6.15. Found: C, 73.33; H, 6.21%.
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1985
13
3.4. Reaction of 3a with an additional equivalent of 1 To a solution of 3a (0.037 mg, 0.086 mmol) in benzene (5 mL) in a Schlenk tube was added a solution of 1 (0.045 g, 0.086 mmol) in benzene (5 mL) under N2. The tube was sealed and heated for 18 h at 85 °C. The tube was opened in air, the solution was filtered through Celite, and the volatiles were removed in vacuo to yield 4a (0.032 g, 86%). 3.5. Preparation of 3b/4b Compound 2b was reacted with 1 in an identical fashion as for 2a, using 2b (0.100 g, 0.180 mmol) and 1 (0.094 g, 0.180 mmol) resulting in a mixture of 3b and 4b as shown by 1H NMR spectroscopy. 3.6. Preparation of 3c/4c Compound 2c was reacted with 1 in an identical fashion as for 2a, using 2c (0.100 g, 0.147 mmol) and 1 (0.077 g, 0.148 mmol) resulting in a mixture of 3c and 4c as shown by 1H NMR spectroscopy. 3.7. Preparation of 3d/4d Compound 2d was reacted with 1 in an identical fashion as for 2a, using 2d (0.100 g, 0.125 mmol) and 1 (0.065 g, 0.125 mmol) resulting in a mixture of 3d and 4d as shown by 1H NMR spectroscopy.
C NMR (C6D6, 25 °C) d 137.8, 134.5, 133.4, 131.3, 129.4, 128.1, 127.6, 127.0, 123.0, 120.2, 111.1, 108.6, 102.6, 1.3, 2.1 ppm. 3.9. Preparation of 4c
Compound 4c was prepared in an analogous fashion as for 4a using 2c (0.250 g, 0.368 mmol) and 1 (0.384 g, 0.737 mmol). Yield of 4c: 0.213 g (85%). 1H NMR (C6D6, 25 °C) d 7.66–7.63 (m, 8H, –SiMePh2 meta-H), 7.47–7.30 (m, 18H, aromatics), 6.98 (s, 2H, 2,11-H), 1.01 (s, 6H, SiMePh2). 13C NMR (CDCl3, 25 °C) d 135.5, 135.2, 134.6, 134.3, 134.2, 129.9, 129.7, 128.1, 127.9, 127.8, 127.2, 120.4, 109.0, 1.3, 2.6 ppm. UV–Vis (C6H6, 25 °C): kmax 278, 293, 322, 337, 406, 431, 460 nm. Anal. Calc. for C46H34O2Si2: C, 81.87; H, 5.08. Found: C, 81.60; H, 5.54%. 3.10. Preparation of 4d Compound 4d was prepared in an analogous fashion as for 4a using 2d (0.250 g, 0.312 mmol) and 1 (0.325 g, 0.624 mmol). Yield of 4d: 0.121 g (49%). 1H NMR (CDCl3, 25 °C) d 7.85–7.63 (m, 12H, –SiPh3 meta-H), 7.61–7.10 (m, 26H, aromatics). 13C NMR (CDCl3, 25 °C) d 136.7, 136.0, 125.8, 135.7, 135.6, 135.4, 130.5, 130.3, 129.9, 129.6, 128.4, 128.2, 128.0, 1.4 ppm. UV–Vis (C6H6, 25 °C): kmax 279, 293, 323, 337, 407, 432, 462 nm. 3.11. Reaction of 1 with 2e
3.8. Preparation of 4b Compound 4b was prepared in an analogous fashion as for 4a using 2b (0.254 g, 0.368 mmol) and 1 (0.477 g, 0.737 mmol). Yield of 4c: 0.131 g (84%). 1H NMR (C6D6, 25 °C) d 7.65–7.63 (m, 4H, (m-C6H5)SiMe2), 7.34 (s, 2H, 2,11-H), 7.32–7.20 (m, 8H, (o-C6H5)SiMe2, (p-C6H5)SiMe2, and 4,12-H), 6.77 (d, J = 4.8 Hz, 2H, 6,14-H), 6.38 (t, J = 4.8 Hz, 2H, 5,13-H), 0.68 (s, 12H, –SiPh(CH3)2) ppm.
As for 4a, compound 1 (0.728 g, 1.40 mmol) and 1,1 0 -bi2-naphthol 2e (0.200 g, 0.699 mmol) were reacted to furnish peri-xanthenoxanthene (PXX, 0.156 g, 79%). 1H NMR (C6D6, 25 °C) d 6.88 (d, J = 9.0 Hz, 2H, H1), 6.81 (d, J = 4.8 Hz, 2H, H6), 6.80 (d, J = 3.6 Hz, 2H, H4), 6.69 (d, J = 9.0 Hz, 2H, H2), 6.56 (dd, J = 3.6 Hz, J = 4.8 Hz, 2H, H5) ppm. UV–Vis (C6H6, 25 °C): kmax 290, 313, 327, 392, 416, 443 nm.
Table 5 Crystallographic data for compounds 3a and 4a–c
Formula Space group ˚) a (A ˚) b (A ˚) c (A a (°) B (°) c (°) ˚ 3) V (A Z qcalc (g cm3) Temperature (K) Radiation ˚) Wavelength (A R Rw
3a
4a
4b
4c
C26H28O2Si2 P21/c 14.821(3) 12.578(3) 14.290(4) 90 115.47(1) 90 2404.9(1) 4 1.184 293 Mo Ka 0.71073 0.0473 0.1126
C26H26O2Si2 P21/c 6.6114(7) 8.5488(9) 20.676(2) 90 94.993(8) 90 1164.2(2) 2 1.217 293 Mo Ka 0.71073 0.0513 0.1504
C36H30O2Si2 P 1 8.3392(6) 9.3961(7) 10.1356(6) 70.071(4) 71.293(4) 73.480(4) 716.93(9) 1 1.276 293 Mo Ka 0.71073 0.0531 0.1078
C46H34O2Si2 Pbca 16.751(4) 12.492(3) 17.074(3) 90 90 90 3572.9(1) 4 1.258 293 Mo Ka 0.71073 0.059 0.1110
1986
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3.12. Reaction of Cd[N(SiMe3)2]2 with 2a 3.12.1. Reaction using 1 equiv. Cd[N(SiMe3)2]2 A solution of Cd[N(SiMe3)2]2 (0.025 g, 0.0578 mmol) in C6D6 (0.3 mL) was added to a solution of 2a (0.025 g, 0.0580 mmol) in C6D6 (0.3 mL) and the progress of the reaction was monitored by 1H NMR spectroscopy. 3.12.2. Reaction using 2 equiv. Cd[N(SiMe3)2]2 A solution of Cd[N(SiMe3)2]2 (0.201 g, 0.464 mmol) in C6D6 (0.5 mL) was added to a solution of 2a (0.100 g, 0.232 mmol) in C6D6 (0.3 mL) and the progress of the reaction was monitored by 1H NMR spectroscopy. 3.13. X-ray structure determination Diffraction intensity data were collected with a Bruker SMART APEX II diffractometer. Crystallographic data and details of X-ray studies are shown in Table 5. Absorption corrections were applied for all data by SADABS. The structures were solved using direct methods, completed by difference Fourier syntheses, and refined by full matrix least squares procedures on F2. All non-hydrogen atoms were refined with anisotropic displacement coefficients and hydrogen atoms were treated as idealized contributions. All software and sources of scattering factors are contained in the SHEXTL (6.1) program package (G. Sheldrick, Bruker AXS, Madison, WI). ORTEP diagrams were drawn using the ORTEP3 program (L. J. Farrugia, Glasgow). Acknowledgements Funding for this work was provided by Oklahoma State University. A.E.W. gratefully acknowledges the assistance of Gianna Bell-Eunice (Oklahoma State University) for her assistance with the 199Hg NMR studies. Appendix A. Supplementary material CCDC 619634, 619635, 619636 and 619637 contain the supplementary crystallographic data for 3a, 4a, 4b and 4c. These data can be obtained free of charge via http:// www.ccdc.cam.ac.uk./conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or email: [email protected]. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.ica.2006.10.005. References [1] V. Ramamurthy, K.S. Schanze (Eds.), Solid State and Surface Photochemistry, CRC Press, New York, 2000. [2] T. Mori, H. Takeuchi, H. Fujikawa, J. Appl. Phys. 97 (2005) 066101. [3] C.D. Dimitrakopoulos, P.R.L. Malenfant, Adv. Mater. 14 (2002) 99.
[4] H. Klauk, M. Halik, U. Zschieschang, G. Schmid, W. Radlik, W. Weber, J. Appl. Phys. 92 (2002) 5259. [5] M.S. Deleuze, J. Chem. Phys. 116 (2002) 7012. [6] F. Do¨tz, J.D. Brand, S. Ito, L. Gherghel, K. Mu¨llen, J. Am. Chem. Soc. 122 (2000) 7707. [7] M. Mu¨ller, C. Ku¨bel, K. Mu¨llen, Chem. Eur. J. 4 (1998) 2099. [8] T. Asari, N. Kobayashi, T. Naito, T. Inabe, Bull. Chem. Soc. Jpn. 74 (2001) 53. [9] M. Hjorth, N. Thorup, P. Frederiksen, K. Bechgaard, Acta Chem. Scand. 48 (1994) 139. [10] T. Asari, M. Ishikawa, T. Naito, M. Matsuda, H. Tajima, T. Inabe, Chem. Lett. 34 (2005) 936. [11] T. Asari, T. Naito, T. Inabe, M. Matsuda, H. Tajima, Chem. Lett. 33 (2004) 128. [12] S. Takano, T. Naito, T. Inabe, Chem. Lett. (1998) 1249. [13] T. Inabe, T. Asari, H. Hasegawa, M. Matsuda, E.H. Gacho, N. Matsumura, S. Takeda, K. Takeda, T. Naito, Synth. Met. 133–134 (2003) 515. [14] T. Inabe, Mol. Cryst. Liq. Cryst. 376 (2002) 225. [15] M. Matsuda, T. Asari, T. Naito, T. Inabe, N. Hanasaki, H. Tajima, Bull. Chem. Soc. Jpn. 76 (2003) 1935. [16] M. Matsuda, N. Hanasaki, H. Tajima, T. Naito, T. Inabe, J. Chem. Phys. Solids 65 (2004) 749. [17] N. Hanasaki, M. Matsuda, H. Tajima, T. Naito, T. Inabe, Synth. Met. 133–134 (2003) 519. [18] A. Sugimoto, S. Kato, H. Inoue, E. Imoto, Bull. Chem. Soc. Jpn. 49 (1976) 337. [19] S. Doi, A. Fujita, S. Ikeura, T. Inabe, Y. Matsunaga, Bull. Chem. Soc. Jpn. 52 (1979) 2494. [20] K. Ikegami, Y. Matsunaga, K. Osafune, E. Osawa, Bull. Chem. Soc. Jpn. 48 (1975) 341. [21] H. Bu¨rger, W. Sawodny, U. Wannagat, J. Organomet. Chem. 3 (1965) 113. [22] T.M. Bockman, D. Kosynkin, J.K. Kochi, J. Org. Chem. 62 (1997) 5811. [23] S.M. Hubig, J.K. Kochi, J. Org. Chem. 65 (2000) 6807. [24] C. Boga, E. Del Vecchio, L. Forlani, Eur. J. Org. Chem. (2004) 1567. [25] S.M. Hubig, J.K. Kochi, J. Am. Chem. Soc. 122 (2000) 8279. [26] J.O. Morley, D.W. Roberts, J. Org. Chem. 62 (1997) 7358. [27] J.H. Atherton, R.B. Moodie, D.R. Noble, J. Chem. Soc., Perkin Trans. 2 (1999) 699. [28] W. Lau, J.K. Kochi, J. Org. Chem. 51 (1986) 1801. [29] W. Lau, J.K. Kochi, J. Am. Chem. Soc. 108 (1986) 6720. [30] R. Taylor, Electrophilic Aromatic Substitution, John Wiley & Sons, Chichester, 1991. [31] D.J. Foster, E. Tobler, J. Am. Chem. Soc. 83 (1961) 851. [32] R. Fields, R.N. Haszeldine, P.J. Palmer, Tetrahedron Lett. (1971) 1879. [33] D.J. Foster, E. Tobler, J. Org. Chem. 27 (1962) 834. [34] G.M. Blackburn, D.W. Cameron, H.W.-S. Chan, J. Chem. Soc. C (1966) 1836. [35] R. Pummerer, E. Prell, A. Rieche, Chem. Ber. 59 (1926) 2159. [36] C.S. Weinert, P.E. Fanwick, I.P. Rothwell, J. Chem. Soc., Dalton Trans. (2002) 2948. [37] A.E. Wetherby Jr., L.R. Goeller, C.K. Diedrich, C.S. Weinert, in preparation. [38] D.F. Shriver, M.A. Drezdzon, The Manipulation of Air Sensitive Compounds, 2nd ed., John Wiley and Sons, New York, 1986. [39] G.J.H. Buisman, L.A. van der Veen, A. Klootwijk, W.G.J. de Lange, P.C.J. Kamer, P.W.N.M. van Leeuwen, D. Vogt, Organometallics 16 (1997) 2929. [40] C. Brevard, P. Granger, Handbook of High Resolution Multinuclear NMR, John Wiley & Sons, New York, 1981. [41] M.A. Sens, N.K. Wilson, P.D. Ellis, J.D. Odom, J. Mag. Reson. 19 (1975) 323.