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Synthesis, structural and optical studies of several new ditelluroether iodides
Polyhedron 39 (2012) 106–112
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Polyhedron journal homepage: www.elsevier.com/locate/poly
Synthesis, structural and optical studies of several new ditelluroether iodides Roberta Cargnelutti a, Ernesto Schulz Lang a,⇑, Gelson Manzoni de Oliveira a,⇑, Paulo Cesar Piquini b a b
Departamento de Química, Laboratório de Materiais Inorgânicos, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil Departamento de Física, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil
a r t i c l e
i n f o
Article history: Received 29 December 2011 Accepted 20 March 2012 Available online 29 March 2012 Keywords: Telluroether iodides Supramolecular assembling DFT-calculations
a b s t r a c t The ditelluroethers RTe(CH2)nTeR (R = phenyl, 4-CH3OAC6H4; n = 1, 3, 4) react with iodine to give [(PhTeI)2(C3H6)(l-O)], [(PhTeI2)2(CH2)], [(PhTeI2)2(C4H8)] and [(4-MeO-C6H4-TeI2)2(C4H8)]CH2Cl2. The structures of the new compounds follow, in principle, the same model as those observed in polymers derived from T-shaped Te(III) monomers, and in supramolecular compounds already obtained with diarylditellurides (RTe)2. Density functional theory studies of the optical and electronic properties of this class of compounds are also presented, with emphasis to the orbitals involved in the electronic transitions of the UV–Vis absorption spectra. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction It is well known that uncommon compositions and configurations are characteristic for the reaction products of diarylditellurides (RTe)2 with iodine [1,2], since tellurium(II) and tellurium(IV) iodide compounds are able to attain all possible combinations of secondary, interionic interactions. Single monomers and dimers, but also polymeric chains attaining 1D, 2D and 3D networks, as well as rare polymeric structures with chalcogene atoms presenting mixed-valence states are often described [3–5]. If CH2 groups are inserted between the tellurium atoms of diarylditellurides, the resulting compounds are called ditelluroethers, RTe(CH2)nTeR. The simplest components of this series of compounds, RTeCH2TeR, have been known since 1970, when they were synthesized by reacting diazomethane with diorganoditelluride [6]. Several other routes have been described for the preparation of these species [7–10], which have been used as ligands in many transition metal complexes [11,12]. Closer to our research in the synthesis of halides of diarylditellurides are the results obtained by Reid and coworkers [13], with the preparation of the m- and p-ditelluroethers C6H4(CH2TeMe)2 and their Te(IV)/I2 derivatives, PhTeI2(CH2)3TeI2Ph, m-C6H4(CH2TeI2Me)2 and p-C6H4(CH2TeI2Me)2. With the aim to revisit some reactions already attained with (RTe)2 and I2 [1,2,5], i.e., to investigate the structural results as well as the optical features when the reactions are performed with a modified diarylditelluride, we have prepared the ditelluroethers RTe(CH2)nTeR (R = phenyl, 4-CH3OAC6H4; n = 1, 3, 4) and studied experimentally their reactions with iodine.
We report now the synthesis, the structure and some optical characteristics of the new (l-oxo-l-propyl)-(bis-tellurium(IV) phenyl-iodo) complex [(PhTeI)2(C3H6)(l-O)] (1) and of the new ditelluroether iodides [(PhTeI2)2(CH2)] (2), [(PhTeI2)2(C4H8)] (3) and [(4-MeO-C6H4-TeI2)2(C4H8)]CH2Cl2 (4). 2. Experimental All manipulations – with exception of the crystallization process – were conducted under Ar by use of standard Schlenk techniques. The reaction steps involved in the preparation of the compounds referred in this work are summarized in Chart A. 2.1. Preparation of [(PhTeI)2(C3H6)(l-O)] (1) To a solution of 114.00 mg (0.2525 mmol) of PhTe(CH2)3TePh in 10 mL CH2Cl2, 63.45 mg (0.2500 mmol) of I2, also dissolved in 10 mL of CH2Cl2, was added. The mixture was stirred by 3 h. The slow evaporation of the orange solution gave yellow crystals of 1. Yield: 69.75% based on PhTe(CH2)3TePh. 2.1.1. Properties: yellow, crystalline substance Melting point: 138–139 °C. Anal. Calc. for C15H16I2OTe2 (721.28): C, 24.98; H, 2.24. Found: C, 25.05; H, 2.08%. IR (KBr, cm 1): 3040.2 [m(CAH)ar], 2934.1 [ms(CAH)aliph], 2985.1 [mas(CAH)aliph], 1571.6 [m(C@C)], 1470.8 [ds(C@CAH)], 1434.1 [d(CACAH)], 1390.2 [das(CACAH)], 756.3, 652.7 [dout pl(C@CAH)]. 2.2. Preparation of [(PhTeI2)2(CH2)] (2)
⇑ Corresponding authors. Tel.: +55 55 3220 8980; fax: +55 55 3220 8031. E-mail addresses: [email protected] (E. Schulz Lang), manzonideo@smail. ufsm.br (G. Manzoni de Oliveira). 0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.poly.2012.03.030
To a solution of 105.86 mg (0.2500 mmol) of PhTeCH2TePh in 10 mL CH2Cl2, 126.90 mg (0.5000 mmol) of I2, also dissolved in
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(1) O Te I
I2 R=Ph, n=3
O
I Te I O
Te I
I Te I (4)
RTe(CH2)nTeR 2I2 R=4-MeO-C6 H4 , n=4
2I 2 R=Ph, n=1
2I 2 R=Ph, n=4
I Te I
I Te I
I Te I (2)
I Te I (3)
Chart A. Steps involved in the preparation of the compounds reported in this work.
10 mL of CH2Cl2, was added. After 3 h stirring an orange precipitate was formed and separated by filtration from the red mother solution. Its slow evaporation yielded red crystals. Yield: 96.18% based on PhTeCH2TePh.
10 mL of CH2Cl2, was added. The mixture was stirred by 3 h. Thereafter a brownish precipitate was isolated by filtration from the red solution, whose slow evaporation led to the achievement of red crystals. Yield: 87.51% based on PhTe(CH2)4TePh.
2.2.1. Properties: red, crystalline substance Melting point: 134–135 °C. Anal. Calc. for C13H12I4Te2 (931.03): C, 16.77; H, 1.30. Found: C, 17.09; H, 1.28%. IR (KBr, cm 1): 3049.3 [m(CAH)ar], 2926.3 [ms(CAH)aliph], 2986 [mas(CAH)aliph], 1568.4 [m(C@C)], 1472.2 [ds(C@CAH)], 1434.2 [d(CACAH)], 727.6, 679.5 [dout pl(C@CAH)].
2.3.1. Properties: red crystals Melting point: 156–157 °C. Anal. Calc. for C16H18I4Te2 (973.10): C, 19.75; H, 1.86. Found: C, 19.92; H, 1.71%. IR (KBr, cm 1): 3046 [m(CAH)ar], 2952.2 [ms(CAH)aliph], 2985.1 [mas(CAH)aliph], 1570.4 [m(C@C)], 1469.1 [ds(C@CAH)], 1432.7 [d(CACAH)], 1400.9 [das(CACAH)], 729, 678.1 [dout pl(C@CAH)].
2.3. Preparation of [(PhTeI2)2(C4H8)] (3)
2.4. Preparation of [(4-MeO-C6H4-TeI2)2(C4H8)]CH2Cl2 (4)
To a solution of 116.38 mg (0.2500 mmol) of PhTe(CH2)4TePh in 10 mL CH2Cl2, 126.90 mg (0.5000 mmol) of I2, also dissolved in
To a solution of 131.39 mg (0.2500 mmol) of {(4-MeOC6H4Te(C2H4)}2 in 10 mL CH2Cl2, 126.90 (0.5000 mmol) of I2, also
Table 1 Crystallographic data and refinement parameters for 1, 2, 3 and 4.
Empirical formula Fw T (K) Crystal system Space group Unit cell dimensions a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z qcalc (g cm 3) l (Mo Ka) (mm 1) k (Å) F (0 0 0) Collected reflns. Unique reflns. GOF (F2) R1a wR2b a b
P P R1 = IIF0I IFcII/ IF0I. P P wR2 = { w(F02 Fc2)2/ w(F02)2}1/2.
1
2
3
4
C15H16I2OTe2 721.28 100(2) monoclinic P21/c
C13H12I4Te2 931.03 296(2) triclinic P1
C16H18I4Te2 973.10 296(2) monoclinic P21/c
C19H24Cl2I4O2Te2 1118.08 296(2) monoclinic C2/c
8.93480(10) 25.3322(5) 8.32120(10) 90 94.3600(10) 90 1877.95(5) 4 2.551 6.389 0.71073 1296 18 923 4881 1.027 0.0339 0.0716
8.8774(4) 11.5336(5) 11.6866(5) 63.337(2) 72.737(2) 73.313(2) 1004.40(8) 2 3.078 9.040 0.71073 812 20 252 5630 1.127 0.0347 0.0831
11.5734(4) 11.9398(4) 8.4868(3) 90 96.353(2) 90 1165.54(7) 2 2.773 7.796 0.71073 860 11 642 3280 1.075 0.0321 0.0794
11.5587(4) 11.6679(4) 21.4250(7) 90 90.770(2) 90 2889.24(17) 2.570 6.492 0.71073 2016 15 816 4094 1.070 0.0371 0.0860
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dissolved in 10 mL of CH2Cl2, was added. After 3 h stirring a red solution remained. Red crystals were obtained by its slow evaporation. Yield: 59.23% based on {4-MeO-C6H4Te(C2H4)}2. 2.4.1. Properties: red, crystalline substance Melting point: 108 °C. Anal. Calc. for C19H24Cl2I4O2Te2 (1118.08): C, 20.92; H, 2.15. Found: C, 21.4; H, 2.08%. IR (KBr, cm 1): 3062.7 [m(CAH)ar], 2831.8 [ms(CAH)aliph], 2924 [mas(CAH)aliph], 1582.1 [m(C@C)], 1491.9 [ds(C@CAH)], 1453.4 [d(CACAH)], 1401.1 [das(CACAH)], 1259.9 [mas(CAO)], 1179.7 [das(CAOAC)], 819.7 [dout pl(C@CAH)]. 2.5. X-ray structure determinations Data were collected with a Bruker APEX II CCD area-detector diffractometer and graphite-monochromatized Mo Ka radiation. The structure was solved by direct methods using SHELXS [14]. Subsequent Fourier-difference map analyses yielded the positions of the non-hydrogen atoms. Refinements were carried out with the SHELXL package [14]. All refinements were made by full-matrix least-squares on F2 with anisotropic displacement parameters for all non-hydrogen atoms. Hydrogen atoms were included in the refinement in calculated positions. Crystal data and more details of the data collection and refinements are contained in Table 1. 2.6. Computational details First principles calculations based on the density functional theory (DFT) have been performed using the GAUSSIAN 09 package [15]. The hybrid B3LYP functional has been employed to treat the exchange and correlation functional [16,17], while the molecular orbitals are described by the 3-21G basis set [18–20]. Infrared vibrational frequency calculations have been performed for the molecules at the geometries directly taken from the X-ray experiments. These non-optimized geometries are determined not to be true local minima, presenting imaginary frequencies. Geometry optimizations were then performed and the obtained geometries were verified to show only real infrared frequencies. The UV–Vis spectra of the molecules were then calculated at these optimized geometries through time-dependent DFT [21,22]. All calculations (geometry optimizations, vibrational frequencies and electronic spectra) were performed by taking the molecules embedded in a tetrahydrofuran solvent (dielectric constant = 7.4257), through the Polarizable Continuum Model [23]. 3. Results and discussion 3.1. Structure Fig. 1 represents the pseudodimeric structure of complex 1. The oxygen bridge in [(PhTeI)2(C3H6)(l-O)] (1) probably was formed during the crystallization of the compound. On the other side, this bridge corroborates the remarkable trend of ditelluroethers to give as products Te(IV) compounds, instead of Te(III) ones, like, for example, T-shaped (RTeIIII2) [24]. The dimeric assembly of 1 is achieved through secondary Te–I contacts. Fig. 2 shows the polymeric, one-dimensional arrangement of 2 in the solid state, along the b axis. Fig. 3 displays the molecular structure of 3, which includes an inversion center, and its polymeric assembling (solid state) along the c axis. Fig. 4 depicts the molecular structure of 4, also with an inversion center, and the two-dimensional assembling of the compound in the solid state in the ab plane. Selected bond lengths and angles of 1, 2, 3 and 4, even for secondary bonds, are included in the figures captions.
Fig. 1. ORTEP [26] picture of the pseudodimeric structure of [(PhTeI)2(C3H6)(l-O)] (1), achieved through TeAI secondary interactions, represented by dashed lines. The thermal ellipsoids are drawn at 50% probability level. Hydrogen atoms have been omitted by clarity. Symmetry code: (#1) = x + 1, y + 1, z + 1. Selected bond lengths (Å) and angles (°): Te1AI1 2.9938(5), Te1AO1 2.029(4), Te2AI2 3.2235(5), Te2AO1 1.944(4), Te1 I2#1 3.6383(5), Te2 I2#1 3.5722(5); O1ATe2AI2 172.09(11), I2ATe2 I2#1 93.244(12), O1ATe1AI1 171.91(11), Te2AO1ATe1 128.91(19), Te1 I2#1 Te2 58.946(0).
The polymerization of compounds 2, 3 and 4 is also due to the attainment of Te–I secondary interactions, which range from 3.5203(5) Å in complex 2 to 3.9697(6) Å in 3, hence, smaller than the sum of the Te/I van der Waals radii, 4.04 Å [25]. The ditelluroethers used as starting materials in this work did not change the trend of diarylditellurides (RTeI)2 to give T-shaped products, in the present cases ditelluro(IV)ether iodides. These last, in turn, did not overlook the tendency of T-shaped (RTeIIII2) [24] species to perform dimers through reciprocal Te I secondary bonding. In addition, the well known Te I secondary interactions between neighbor molecules, leading to the formation of n-dimensional polymers in the solid state, are also present in compounds 2, 3 and 4. These trends – the occurrence of intra and intermolecular Te I long range, (secondary) interactions between adjacent molecules, linking them into infinite arrays – were already described in the literature [13] for this kind of ditelluroethers derivatives. 3.2. Optical and electronic features Figs. 5–8 show the calculated (theoretical) absorption spectra (vertical lines are calculated electronic transitions) and the experimental spectra of 1, 2, 3 and 4. These figures show a reasonable agreement between the DFT results and the experimental findings. According to Fig. 5a, the first significant transitions in 1 occur in the wavelengths of 347.64 nm (3.5665 eV) and 330.73 nm (3.7488 eV), relating to transitions between the orbitals HOMO4 ? LUMO (347.64 nm) and HOMO 5 ? LUMO (330.73 nm). The HOMO ? LUMO transition of 2 occurs by 554.49 nm, but its intensity is low, as shown in Fig. 6a. The first transition of significant intensity occurs in 378.45 nm (3.2761 eV) and involves the orbitals HOMO 10 ? LUMO. Other high energy transitions appearing in Fig. 6a are concerned to p orbitals of the aromatic rings and the orbitals LUMO and LUMO+1, which exhibit similar contributions. The transition in 348.56 nm (3.557 eV) of 3, represented in Fig. 7a as the first vertical line, results from an electronic excitation involving the HOMO 10 and HOMO 11 orbitals and the orbitals LUMO and LUMO+1. The transition of very low intensity around 500 nm involves the higher occupied orbitals (HOMO, HOMO 1, etc.) and the orbitals LUMO and LUMO+1. The second transition,
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Fig. 2. (a) Symmetric unit of [(PhTeI2)2(CH2)] (2). The thermal ellipsoids are drawn at 50% probability level. (b) Diamond [27] representation of the polymeric (zig zag), onedimensional structure of 2, achieved through TeAI secondary interactions (represented by dashed lines). Hydrogen atoms have been omitted by clarity. Symmetry code: (#1) = x + 1, y + 1, z + 1. Selected bond lengths (Å) and angles (°): Te2AI3 2.8587(5), Te2AI4 2.9627(5), Te2 I4#1 3.8903(5), Te1AI1 2.8374(6), Te1AI2 2.9831(5), Te1 I4 3.5203(5); I3ATe2AI4 175.103(17), I3ATe2 I4#1 95.438(13), I4ATe2 I4#1 88.012(13). 8.012(13), I1ATe1AI2 170.69(2), I1ATe1 I4 93.962(16), I2ATe1 I4 81.925(13), Te2AI4 Te1 67.882(11), Te2AC13ATe1 116.7(2).
Fig. 3. Molecular structure of [(PhTeI2)2(C4H8)] (3) and its polymeric assembling attained through TeAI secondary bonds (represented by dashed lines). Hydrogen atoms have been omitted by clarity. Symmetry codes: (#1) = x + 1, y, z + 1; (#2) x + 1, y, z + 2. Selected bond lengths (Å) and angles (°): Te1AI2 2.9074(5), Te1AI1 2.8747(4), Te1 I2#2 3.9697(6); I1ATe1AI2 176.917(17), I1ATe1 I2#2 82.205(12), I2ATe1 I2#2 95.194(13).
Fig. 4. Molecular structure of [(4-MeO-C6H4-TeI2)2(C4H8)]CH2Cl2 (4) and the twodimensional assembling attained through TeAI secondary bonds (represented by dashed lines), in the ab plane. The solvate molecule CH2Cl2 and the hydrogen atoms have been omitted by clarity. Symmetry codes: (#1) = x + 1.5, y + 1.5, z + 1; (#2) x + 1, y + 2, z + 1. Selected bond lengths (Å) and angles (°): Te1AI2 2.8917(6), Te1AI1 2.9145(6), Te1 I2#2 3.8649(6); C11ATe1AI2 92.47(15), C11ATe1AI1 93.08(15), I2ATe1AI1 174.446(17), C11ATe1 I2#2 168.64(14), I2ATe1 I2#2 87.645(15), I1ATe1 I2#2 86.890(13).
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Fig. 5. (a) Theoretical absorption spectrum of 1. The vertical lines are the calculated electronic transitions. (b) Experimental absorption spectrum of 1.
Fig. 6. (a) Theoretical absorption spectrum of 2. The vertical lines are the calculated electronic transitions. (b) Experimental absorption spectrum of 2.
Fig. 7. (a) Theoretical absorption spectrum of 3. The vertical lines are the calculated electronic transitions. (b) Experimental absorption spectrum of 3.
at 335.64 nm (3.694 eV), is related to transitions between the orbitals HOMO 12–HOMO 13 and LUMO–LUMO+1. Fig. 9 represents the HOMO/LUMO orbitals of 4 and their contributions for the transitions illustrated in Fig. 8a. The lowest energy transitions should occur in the wavelength of 503.23 nm, involving transitions of the type HOMO ? LUMO and HOMO 1 ? LUMO+1, but according to Fig. 8a their probability of occurrence is very low.
The transition at 442.26 nm engages the orbitals HOMO 8 ? LUMO and HOMO 9 ? LUMO+1. The highest intensity transition appears at 320.59 nm, corresponding chiefly to a HOMO 12 ? LUMO excitation. As a general characteristic of these compounds, the more intense electronic transitions involve an electronic excitation to, at most, the two lowest unoccupied molecular orbitals (LUMO and LUMO+1),
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Fig. 8. (a) Theoretical absorption spectrum of 4. The vertical lines are the calculated electronic transitions. (b) Experimental absorption spectrum of 4.
Fig. 9. HOMO orbitals involved in the electronic transitions of 4 (see Fig. 8a). (a) HOMO: major contributions of the ‘‘p’’ orbitals of the iodine atoms, minor contributions of the aromatic rings; (b) HOMO 8: the same contributions as HOMO; (c) HOMO 12: contributions from the p-type orbitals of the aromatic rings; (d) LUMO: highlighting the ‘‘p’’ orbitals of iodine and tellurium.
which seem to have contributions almost exclusively from iodine and tellurium ‘‘p’’ orbitals. On the other hand, the electronic transitions involving the lowest occupied molecular orbitals, HOMO and HOMO 1, although being the lowest energy ones, present very low intensities. The optically active molecular occupied orbitals come from orbitals deeper in the valence shell (e.g. HOMO 8, HOMO 10). These active orbitals show contributions from ‘‘p’’ orbitals from iodine and tellurium, but also from the aromatic rings. 4. Conclusion New ditelluroether iodides have been treated in this work, starting with their syntheses, followed by structural aspects completed through X-ray diffractometry and infrared spectroscopy, and ending with studies of molecular orbitals responsible for the depicted calculated and experimental UV–Vis absorption spectra. So far, to our knowledge, no studies have yet been performed on the electronic properties of this class of compounds. Acknowledgments This work was supported with funds from CNPq/FAPERGS (PRONEX-10/0005-1). The calculations have been performed at the computational facilities of CPAD/UFSM.
Appendix A. Supplementary data CCDC 841830–841833 contain the supplementary crystallographic data for 1, 2, 3 and 4, respectively. 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) 1223-336033; or e-mail: [email protected]. Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.poly.2012.03.030. References [1] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, Polyhedron 28 (2009) 63. [2] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, J. Organomet. Chem. 694 (2009) 1557. [3] H.M.K.K. Pathirana, J.H. Reibenspies, E.A. Meyers, R.A. Zingaro, Acta Crystallogr., Sect. C 47 (1991) 516. [4] S. Hauge, K. Maroy, T. Odegard, Acta Chem. Scand. Ser. A 42 (1988) 56. [5] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, J. Organomet. Chem. 691 (2006) 5867. [6] N. Petragnani, G. Schill, Chem. Ber. 103 (1970) 2271. [7] C.H.W. Jones, R.D. Sharma, Organometallics 5 (1986) 805. [8] L. Engman, M.P. Cava, Organometallics 1 (1982) 470. [9] A.K. Singh, V. Srivastava, J. Coord. Chem. 27 (1992) 237. [10] K.G.K. De Silva, Z. Mozef-Mirzai, W.R. McWhinnie, J. Chem. Soc., Dalton Trans. (1983) 2143.
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Polyhedron journal homepage: www.elsevier.com/locate/poly
Synthesis, structural and optical studies of several new ditelluroether iodides Roberta Cargnelutti a, Ernesto Schulz Lang a,⇑, Gelson Manzoni de Oliveira a,⇑, Paulo Cesar Piquini b a b
Departamento de Química, Laboratório de Materiais Inorgânicos, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil Departamento de Física, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil
a r t i c l e
i n f o
Article history: Received 29 December 2011 Accepted 20 March 2012 Available online 29 March 2012 Keywords: Telluroether iodides Supramolecular assembling DFT-calculations
a b s t r a c t The ditelluroethers RTe(CH2)nTeR (R = phenyl, 4-CH3OAC6H4; n = 1, 3, 4) react with iodine to give [(PhTeI)2(C3H6)(l-O)], [(PhTeI2)2(CH2)], [(PhTeI2)2(C4H8)] and [(4-MeO-C6H4-TeI2)2(C4H8)]CH2Cl2. The structures of the new compounds follow, in principle, the same model as those observed in polymers derived from T-shaped Te(III) monomers, and in supramolecular compounds already obtained with diarylditellurides (RTe)2. Density functional theory studies of the optical and electronic properties of this class of compounds are also presented, with emphasis to the orbitals involved in the electronic transitions of the UV–Vis absorption spectra. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction It is well known that uncommon compositions and configurations are characteristic for the reaction products of diarylditellurides (RTe)2 with iodine [1,2], since tellurium(II) and tellurium(IV) iodide compounds are able to attain all possible combinations of secondary, interionic interactions. Single monomers and dimers, but also polymeric chains attaining 1D, 2D and 3D networks, as well as rare polymeric structures with chalcogene atoms presenting mixed-valence states are often described [3–5]. If CH2 groups are inserted between the tellurium atoms of diarylditellurides, the resulting compounds are called ditelluroethers, RTe(CH2)nTeR. The simplest components of this series of compounds, RTeCH2TeR, have been known since 1970, when they were synthesized by reacting diazomethane with diorganoditelluride [6]. Several other routes have been described for the preparation of these species [7–10], which have been used as ligands in many transition metal complexes [11,12]. Closer to our research in the synthesis of halides of diarylditellurides are the results obtained by Reid and coworkers [13], with the preparation of the m- and p-ditelluroethers C6H4(CH2TeMe)2 and their Te(IV)/I2 derivatives, PhTeI2(CH2)3TeI2Ph, m-C6H4(CH2TeI2Me)2 and p-C6H4(CH2TeI2Me)2. With the aim to revisit some reactions already attained with (RTe)2 and I2 [1,2,5], i.e., to investigate the structural results as well as the optical features when the reactions are performed with a modified diarylditelluride, we have prepared the ditelluroethers RTe(CH2)nTeR (R = phenyl, 4-CH3OAC6H4; n = 1, 3, 4) and studied experimentally their reactions with iodine.
We report now the synthesis, the structure and some optical characteristics of the new (l-oxo-l-propyl)-(bis-tellurium(IV) phenyl-iodo) complex [(PhTeI)2(C3H6)(l-O)] (1) and of the new ditelluroether iodides [(PhTeI2)2(CH2)] (2), [(PhTeI2)2(C4H8)] (3) and [(4-MeO-C6H4-TeI2)2(C4H8)]CH2Cl2 (4). 2. Experimental All manipulations – with exception of the crystallization process – were conducted under Ar by use of standard Schlenk techniques. The reaction steps involved in the preparation of the compounds referred in this work are summarized in Chart A. 2.1. Preparation of [(PhTeI)2(C3H6)(l-O)] (1) To a solution of 114.00 mg (0.2525 mmol) of PhTe(CH2)3TePh in 10 mL CH2Cl2, 63.45 mg (0.2500 mmol) of I2, also dissolved in 10 mL of CH2Cl2, was added. The mixture was stirred by 3 h. The slow evaporation of the orange solution gave yellow crystals of 1. Yield: 69.75% based on PhTe(CH2)3TePh. 2.1.1. Properties: yellow, crystalline substance Melting point: 138–139 °C. Anal. Calc. for C15H16I2OTe2 (721.28): C, 24.98; H, 2.24. Found: C, 25.05; H, 2.08%. IR (KBr, cm 1): 3040.2 [m(CAH)ar], 2934.1 [ms(CAH)aliph], 2985.1 [mas(CAH)aliph], 1571.6 [m(C@C)], 1470.8 [ds(C@CAH)], 1434.1 [d(CACAH)], 1390.2 [das(CACAH)], 756.3, 652.7 [dout pl(C@CAH)]. 2.2. Preparation of [(PhTeI2)2(CH2)] (2)
⇑ Corresponding authors. Tel.: +55 55 3220 8980; fax: +55 55 3220 8031. E-mail addresses: [email protected] (E. Schulz Lang), manzonideo@smail. ufsm.br (G. Manzoni de Oliveira). 0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.poly.2012.03.030
To a solution of 105.86 mg (0.2500 mmol) of PhTeCH2TePh in 10 mL CH2Cl2, 126.90 mg (0.5000 mmol) of I2, also dissolved in
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(1) O Te I
I2 R=Ph, n=3
O
I Te I O
Te I
I Te I (4)
RTe(CH2)nTeR 2I2 R=4-MeO-C6 H4 , n=4
2I 2 R=Ph, n=1
2I 2 R=Ph, n=4
I Te I
I Te I
I Te I (2)
I Te I (3)
Chart A. Steps involved in the preparation of the compounds reported in this work.
10 mL of CH2Cl2, was added. After 3 h stirring an orange precipitate was formed and separated by filtration from the red mother solution. Its slow evaporation yielded red crystals. Yield: 96.18% based on PhTeCH2TePh.
10 mL of CH2Cl2, was added. The mixture was stirred by 3 h. Thereafter a brownish precipitate was isolated by filtration from the red solution, whose slow evaporation led to the achievement of red crystals. Yield: 87.51% based on PhTe(CH2)4TePh.
2.2.1. Properties: red, crystalline substance Melting point: 134–135 °C. Anal. Calc. for C13H12I4Te2 (931.03): C, 16.77; H, 1.30. Found: C, 17.09; H, 1.28%. IR (KBr, cm 1): 3049.3 [m(CAH)ar], 2926.3 [ms(CAH)aliph], 2986 [mas(CAH)aliph], 1568.4 [m(C@C)], 1472.2 [ds(C@CAH)], 1434.2 [d(CACAH)], 727.6, 679.5 [dout pl(C@CAH)].
2.3.1. Properties: red crystals Melting point: 156–157 °C. Anal. Calc. for C16H18I4Te2 (973.10): C, 19.75; H, 1.86. Found: C, 19.92; H, 1.71%. IR (KBr, cm 1): 3046 [m(CAH)ar], 2952.2 [ms(CAH)aliph], 2985.1 [mas(CAH)aliph], 1570.4 [m(C@C)], 1469.1 [ds(C@CAH)], 1432.7 [d(CACAH)], 1400.9 [das(CACAH)], 729, 678.1 [dout pl(C@CAH)].
2.3. Preparation of [(PhTeI2)2(C4H8)] (3)
2.4. Preparation of [(4-MeO-C6H4-TeI2)2(C4H8)]CH2Cl2 (4)
To a solution of 116.38 mg (0.2500 mmol) of PhTe(CH2)4TePh in 10 mL CH2Cl2, 126.90 mg (0.5000 mmol) of I2, also dissolved in
To a solution of 131.39 mg (0.2500 mmol) of {(4-MeOC6H4Te(C2H4)}2 in 10 mL CH2Cl2, 126.90 (0.5000 mmol) of I2, also
Table 1 Crystallographic data and refinement parameters for 1, 2, 3 and 4.
Empirical formula Fw T (K) Crystal system Space group Unit cell dimensions a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z qcalc (g cm 3) l (Mo Ka) (mm 1) k (Å) F (0 0 0) Collected reflns. Unique reflns. GOF (F2) R1a wR2b a b
P P R1 = IIF0I IFcII/ IF0I. P P wR2 = { w(F02 Fc2)2/ w(F02)2}1/2.
1
2
3
4
C15H16I2OTe2 721.28 100(2) monoclinic P21/c
C13H12I4Te2 931.03 296(2) triclinic P1
C16H18I4Te2 973.10 296(2) monoclinic P21/c
C19H24Cl2I4O2Te2 1118.08 296(2) monoclinic C2/c
8.93480(10) 25.3322(5) 8.32120(10) 90 94.3600(10) 90 1877.95(5) 4 2.551 6.389 0.71073 1296 18 923 4881 1.027 0.0339 0.0716
8.8774(4) 11.5336(5) 11.6866(5) 63.337(2) 72.737(2) 73.313(2) 1004.40(8) 2 3.078 9.040 0.71073 812 20 252 5630 1.127 0.0347 0.0831
11.5734(4) 11.9398(4) 8.4868(3) 90 96.353(2) 90 1165.54(7) 2 2.773 7.796 0.71073 860 11 642 3280 1.075 0.0321 0.0794
11.5587(4) 11.6679(4) 21.4250(7) 90 90.770(2) 90 2889.24(17) 2.570 6.492 0.71073 2016 15 816 4094 1.070 0.0371 0.0860
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dissolved in 10 mL of CH2Cl2, was added. After 3 h stirring a red solution remained. Red crystals were obtained by its slow evaporation. Yield: 59.23% based on {4-MeO-C6H4Te(C2H4)}2. 2.4.1. Properties: red, crystalline substance Melting point: 108 °C. Anal. Calc. for C19H24Cl2I4O2Te2 (1118.08): C, 20.92; H, 2.15. Found: C, 21.4; H, 2.08%. IR (KBr, cm 1): 3062.7 [m(CAH)ar], 2831.8 [ms(CAH)aliph], 2924 [mas(CAH)aliph], 1582.1 [m(C@C)], 1491.9 [ds(C@CAH)], 1453.4 [d(CACAH)], 1401.1 [das(CACAH)], 1259.9 [mas(CAO)], 1179.7 [das(CAOAC)], 819.7 [dout pl(C@CAH)]. 2.5. X-ray structure determinations Data were collected with a Bruker APEX II CCD area-detector diffractometer and graphite-monochromatized Mo Ka radiation. The structure was solved by direct methods using SHELXS [14]. Subsequent Fourier-difference map analyses yielded the positions of the non-hydrogen atoms. Refinements were carried out with the SHELXL package [14]. All refinements were made by full-matrix least-squares on F2 with anisotropic displacement parameters for all non-hydrogen atoms. Hydrogen atoms were included in the refinement in calculated positions. Crystal data and more details of the data collection and refinements are contained in Table 1. 2.6. Computational details First principles calculations based on the density functional theory (DFT) have been performed using the GAUSSIAN 09 package [15]. The hybrid B3LYP functional has been employed to treat the exchange and correlation functional [16,17], while the molecular orbitals are described by the 3-21G basis set [18–20]. Infrared vibrational frequency calculations have been performed for the molecules at the geometries directly taken from the X-ray experiments. These non-optimized geometries are determined not to be true local minima, presenting imaginary frequencies. Geometry optimizations were then performed and the obtained geometries were verified to show only real infrared frequencies. The UV–Vis spectra of the molecules were then calculated at these optimized geometries through time-dependent DFT [21,22]. All calculations (geometry optimizations, vibrational frequencies and electronic spectra) were performed by taking the molecules embedded in a tetrahydrofuran solvent (dielectric constant = 7.4257), through the Polarizable Continuum Model [23]. 3. Results and discussion 3.1. Structure Fig. 1 represents the pseudodimeric structure of complex 1. The oxygen bridge in [(PhTeI)2(C3H6)(l-O)] (1) probably was formed during the crystallization of the compound. On the other side, this bridge corroborates the remarkable trend of ditelluroethers to give as products Te(IV) compounds, instead of Te(III) ones, like, for example, T-shaped (RTeIIII2) [24]. The dimeric assembly of 1 is achieved through secondary Te–I contacts. Fig. 2 shows the polymeric, one-dimensional arrangement of 2 in the solid state, along the b axis. Fig. 3 displays the molecular structure of 3, which includes an inversion center, and its polymeric assembling (solid state) along the c axis. Fig. 4 depicts the molecular structure of 4, also with an inversion center, and the two-dimensional assembling of the compound in the solid state in the ab plane. Selected bond lengths and angles of 1, 2, 3 and 4, even for secondary bonds, are included in the figures captions.
Fig. 1. ORTEP [26] picture of the pseudodimeric structure of [(PhTeI)2(C3H6)(l-O)] (1), achieved through TeAI secondary interactions, represented by dashed lines. The thermal ellipsoids are drawn at 50% probability level. Hydrogen atoms have been omitted by clarity. Symmetry code: (#1) = x + 1, y + 1, z + 1. Selected bond lengths (Å) and angles (°): Te1AI1 2.9938(5), Te1AO1 2.029(4), Te2AI2 3.2235(5), Te2AO1 1.944(4), Te1 I2#1 3.6383(5), Te2 I2#1 3.5722(5); O1ATe2AI2 172.09(11), I2ATe2 I2#1 93.244(12), O1ATe1AI1 171.91(11), Te2AO1ATe1 128.91(19), Te1 I2#1 Te2 58.946(0).
The polymerization of compounds 2, 3 and 4 is also due to the attainment of Te–I secondary interactions, which range from 3.5203(5) Å in complex 2 to 3.9697(6) Å in 3, hence, smaller than the sum of the Te/I van der Waals radii, 4.04 Å [25]. The ditelluroethers used as starting materials in this work did not change the trend of diarylditellurides (RTeI)2 to give T-shaped products, in the present cases ditelluro(IV)ether iodides. These last, in turn, did not overlook the tendency of T-shaped (RTeIIII2) [24] species to perform dimers through reciprocal Te I secondary bonding. In addition, the well known Te I secondary interactions between neighbor molecules, leading to the formation of n-dimensional polymers in the solid state, are also present in compounds 2, 3 and 4. These trends – the occurrence of intra and intermolecular Te I long range, (secondary) interactions between adjacent molecules, linking them into infinite arrays – were already described in the literature [13] for this kind of ditelluroethers derivatives. 3.2. Optical and electronic features Figs. 5–8 show the calculated (theoretical) absorption spectra (vertical lines are calculated electronic transitions) and the experimental spectra of 1, 2, 3 and 4. These figures show a reasonable agreement between the DFT results and the experimental findings. According to Fig. 5a, the first significant transitions in 1 occur in the wavelengths of 347.64 nm (3.5665 eV) and 330.73 nm (3.7488 eV), relating to transitions between the orbitals HOMO4 ? LUMO (347.64 nm) and HOMO 5 ? LUMO (330.73 nm). The HOMO ? LUMO transition of 2 occurs by 554.49 nm, but its intensity is low, as shown in Fig. 6a. The first transition of significant intensity occurs in 378.45 nm (3.2761 eV) and involves the orbitals HOMO 10 ? LUMO. Other high energy transitions appearing in Fig. 6a are concerned to p orbitals of the aromatic rings and the orbitals LUMO and LUMO+1, which exhibit similar contributions. The transition in 348.56 nm (3.557 eV) of 3, represented in Fig. 7a as the first vertical line, results from an electronic excitation involving the HOMO 10 and HOMO 11 orbitals and the orbitals LUMO and LUMO+1. The transition of very low intensity around 500 nm involves the higher occupied orbitals (HOMO, HOMO 1, etc.) and the orbitals LUMO and LUMO+1. The second transition,
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Fig. 2. (a) Symmetric unit of [(PhTeI2)2(CH2)] (2). The thermal ellipsoids are drawn at 50% probability level. (b) Diamond [27] representation of the polymeric (zig zag), onedimensional structure of 2, achieved through TeAI secondary interactions (represented by dashed lines). Hydrogen atoms have been omitted by clarity. Symmetry code: (#1) = x + 1, y + 1, z + 1. Selected bond lengths (Å) and angles (°): Te2AI3 2.8587(5), Te2AI4 2.9627(5), Te2 I4#1 3.8903(5), Te1AI1 2.8374(6), Te1AI2 2.9831(5), Te1 I4 3.5203(5); I3ATe2AI4 175.103(17), I3ATe2 I4#1 95.438(13), I4ATe2 I4#1 88.012(13). 8.012(13), I1ATe1AI2 170.69(2), I1ATe1 I4 93.962(16), I2ATe1 I4 81.925(13), Te2AI4 Te1 67.882(11), Te2AC13ATe1 116.7(2).
Fig. 3. Molecular structure of [(PhTeI2)2(C4H8)] (3) and its polymeric assembling attained through TeAI secondary bonds (represented by dashed lines). Hydrogen atoms have been omitted by clarity. Symmetry codes: (#1) = x + 1, y, z + 1; (#2) x + 1, y, z + 2. Selected bond lengths (Å) and angles (°): Te1AI2 2.9074(5), Te1AI1 2.8747(4), Te1 I2#2 3.9697(6); I1ATe1AI2 176.917(17), I1ATe1 I2#2 82.205(12), I2ATe1 I2#2 95.194(13).
Fig. 4. Molecular structure of [(4-MeO-C6H4-TeI2)2(C4H8)]CH2Cl2 (4) and the twodimensional assembling attained through TeAI secondary bonds (represented by dashed lines), in the ab plane. The solvate molecule CH2Cl2 and the hydrogen atoms have been omitted by clarity. Symmetry codes: (#1) = x + 1.5, y + 1.5, z + 1; (#2) x + 1, y + 2, z + 1. Selected bond lengths (Å) and angles (°): Te1AI2 2.8917(6), Te1AI1 2.9145(6), Te1 I2#2 3.8649(6); C11ATe1AI2 92.47(15), C11ATe1AI1 93.08(15), I2ATe1AI1 174.446(17), C11ATe1 I2#2 168.64(14), I2ATe1 I2#2 87.645(15), I1ATe1 I2#2 86.890(13).
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Fig. 5. (a) Theoretical absorption spectrum of 1. The vertical lines are the calculated electronic transitions. (b) Experimental absorption spectrum of 1.
Fig. 6. (a) Theoretical absorption spectrum of 2. The vertical lines are the calculated electronic transitions. (b) Experimental absorption spectrum of 2.
Fig. 7. (a) Theoretical absorption spectrum of 3. The vertical lines are the calculated electronic transitions. (b) Experimental absorption spectrum of 3.
at 335.64 nm (3.694 eV), is related to transitions between the orbitals HOMO 12–HOMO 13 and LUMO–LUMO+1. Fig. 9 represents the HOMO/LUMO orbitals of 4 and their contributions for the transitions illustrated in Fig. 8a. The lowest energy transitions should occur in the wavelength of 503.23 nm, involving transitions of the type HOMO ? LUMO and HOMO 1 ? LUMO+1, but according to Fig. 8a their probability of occurrence is very low.
The transition at 442.26 nm engages the orbitals HOMO 8 ? LUMO and HOMO 9 ? LUMO+1. The highest intensity transition appears at 320.59 nm, corresponding chiefly to a HOMO 12 ? LUMO excitation. As a general characteristic of these compounds, the more intense electronic transitions involve an electronic excitation to, at most, the two lowest unoccupied molecular orbitals (LUMO and LUMO+1),
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Fig. 8. (a) Theoretical absorption spectrum of 4. The vertical lines are the calculated electronic transitions. (b) Experimental absorption spectrum of 4.
Fig. 9. HOMO orbitals involved in the electronic transitions of 4 (see Fig. 8a). (a) HOMO: major contributions of the ‘‘p’’ orbitals of the iodine atoms, minor contributions of the aromatic rings; (b) HOMO 8: the same contributions as HOMO; (c) HOMO 12: contributions from the p-type orbitals of the aromatic rings; (d) LUMO: highlighting the ‘‘p’’ orbitals of iodine and tellurium.
which seem to have contributions almost exclusively from iodine and tellurium ‘‘p’’ orbitals. On the other hand, the electronic transitions involving the lowest occupied molecular orbitals, HOMO and HOMO 1, although being the lowest energy ones, present very low intensities. The optically active molecular occupied orbitals come from orbitals deeper in the valence shell (e.g. HOMO 8, HOMO 10). These active orbitals show contributions from ‘‘p’’ orbitals from iodine and tellurium, but also from the aromatic rings. 4. Conclusion New ditelluroether iodides have been treated in this work, starting with their syntheses, followed by structural aspects completed through X-ray diffractometry and infrared spectroscopy, and ending with studies of molecular orbitals responsible for the depicted calculated and experimental UV–Vis absorption spectra. So far, to our knowledge, no studies have yet been performed on the electronic properties of this class of compounds. Acknowledgments This work was supported with funds from CNPq/FAPERGS (PRONEX-10/0005-1). The calculations have been performed at the computational facilities of CPAD/UFSM.
Appendix A. Supplementary data CCDC 841830–841833 contain the supplementary crystallographic data for 1, 2, 3 and 4, respectively. 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) 1223-336033; or e-mail: [email protected]. Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.poly.2012.03.030. References [1] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, Polyhedron 28 (2009) 63. [2] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, J. Organomet. Chem. 694 (2009) 1557. [3] H.M.K.K. Pathirana, J.H. Reibenspies, E.A. Meyers, R.A. Zingaro, Acta Crystallogr., Sect. C 47 (1991) 516. [4] S. Hauge, K. Maroy, T. Odegard, Acta Chem. Scand. Ser. A 42 (1988) 56. [5] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, J. Organomet. Chem. 691 (2006) 5867. [6] N. Petragnani, G. Schill, Chem. Ber. 103 (1970) 2271. [7] C.H.W. Jones, R.D. Sharma, Organometallics 5 (1986) 805. [8] L. Engman, M.P. Cava, Organometallics 1 (1982) 470. [9] A.K. Singh, V. Srivastava, J. Coord. Chem. 27 (1992) 237. [10] K.G.K. De Silva, Z. Mozef-Mirzai, W.R. McWhinnie, J. Chem. Soc., Dalton Trans. (1983) 2143.
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