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Reactions of alkyl and aryl sulfides with a monocarbon platinacarbaborane anion
Inorganica Chimica Acta 360 (2007) 3394–3399 www.elsevier.com/locate/ica
Reactions of alkyl and aryl sulfides with a monocarbon platinacarbaborane anion Martin D. Rudd a
a,*
, John C. Jeffery
b
Department of Chemistry, University of Wisconsin – Fox Valley, 1478 Midway Road, Menasha, WI 54952, USA b School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom Received 12 January 2007; accepted 17 April 2007 Available online 4 May 2007
Abstract The reaction of the monocarbon carbaborane complex Na[Pt(PEt3)2(g5-CB10H11)] with some diaryl- and dialkyl disulfides has been investigated. With Ph2S2, two new cage substituted products are formed, [Pt(SPh)(PEt3)(g5-9-SPh-7-CB10H10)] (1) and [Pt(SPh)(PEt3)(g5-8-SPh-11-SPh-7-CB10H9)] (2), whereas with But 2 S2 the main product is the metal substituted complex, [Pt(SBut)(PEt3)(g5-7-CB10H11)] (4). All three new molecules have been identified spectroscopically (1H, 13C, 31P, 11B NMR) and through single crystal X-ray diffraction. 2007 Elsevier B.V. All rights reserved. Keywords: Monocarbon carbaborane; Platinum complex; Sulfur derivative; Crystal structure
1. Introduction In an earlier paper, we described an extensive set of novel monocarbon platinacarborane complexes with selenium and tellurium substitutents synthesized by the reaction of the anion Na[Pt(PEt3)2(g5-CB10H11)] with diphenyl diselenide and diphenyl ditelluride. We found that column chromatography was able to separate a mixture of cage and metal substituted products [1]. With this in mind, investigations into the reactions of some analogous diaryl/ dialkyl disulfides have been carried out. Monocarbon metallacarboranes are substantially less studied that their dicarbon metallacarborane counterparts [2]. A search of the literature reveals that there are several complexes with a platinacarborane closo-PtC2B9 cage system [3–7] but only a few examples of the monocarbon equivalent closo-PtCB10 cage. Before the commencement of this work, those two complexes were [NMe4][Pt(PEt3)2(g5-7-CB10H11)] and [Pt(PEt3)2(g5-7-NMe3-7-CB10H10)] which were synthesized by the expansion of the carborane *
Corresponding author. Tel.: +1 920 832 2694. E-mail address: [email protected] (M.D. Rudd).
0020-1693/$ - see front matter 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2007.04.024
polyhedron [8,9]. We have found in our studies that there are substantial reactivity differences between the anionic [Pt(PEt3)2(g5-7-CB10H11)] species (where the CB10H11 group formally donates three electrons to the platinum atom) and the unreactive (at the metal center) [Pt(PEt3)2(g5-7,8-C2B9H11)] in which the cage behaves as a four electron donor. For instance we found that the nucleophilic platinum atom reacts with a variety of electrophilic transition metal cations, such as Ph3PAu+, PhHg+ and Ph3PCu+ [10] and acids [11] yielding novel dimetallic species. In addition, in Ref. [1], we described the formation of (cage)Pt–Se and (cage)Pt–Te complexes following the addition of the electrophilic ‘‘PhSe+’’ and ‘‘PhTe+’’ species to the [Pt(PEt3)2(g5-7-CB10H11)] anion. As a follow up to this work, we present here some studies of the reaction of diaryl and dialkyl disulfides with this monocarbon platinacarborane anion. 2. Experimental All experiments were conducted under an atmosphere of dry argon using Schlenk tube techniques. Solvents were freshly distilled under nitrogen from appropriate drying
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agents before use. Light petroleum refers to the fraction of boiling point 40–60 C. Tetrahydrofuran was distilled from K/benzophenone under nitrogen and stored over Na/K alloy. Chromatography columns (ca. 30 cm long and 3 cm in diameter) were packed under nitrogen with silica gel (Acros 70–230 mesh). The NMR spectra were recorded at the following frequencies: 1H 360.13 MHz, 13C 90.56 MHz, 31P 145.78 MHz and 11B 115.55 MHz. 7-Me3N-7-CB10H12 [12] and [PtCl2(PEt3)2] [13] were prepared according to the literature methods. [Na]3[CB10H11] was synthesized according to the method of Knoth et al. [14] and Na[Pt(PEt3)2(g5-CB10H11)] [10] was prepared as described in an earlier paper. Ph2S2 and But 2 S2 were purchased from Aldrich and used as supplied. 5
2.1. Synthesis of [Pt(SPh)(PEt3)(g -9-SPh-7-CB10H10)] (1), [Pt(SPh)(PEt3)(g5-8-SPh-11-SPh-7-CB10H9)] (2) and [Pt(SPh)(PEt3)(g5-7-CB10H11)] (3) Into a chilled ( 95 C) solution of Na[Pt(PEt3)2(g5-7CB10H11)] [0.50 mmol, prepared from 0.50 mmol Na3[CB10H11] and 0.50 mmol [PtCl2(PEt3)2] in thf (tetrahydrofuran, 20 mL)] was introduced a solution of Ph2S2 (0.11 g, 0.50 mmol) in thf (15 mL). The reaction was brought to room temperature and stirred for 2 h then warmed at 40 C for a further 2 h during which it turned a deep red color. The thf was removed in vacuo, the residue taken up in CH2Cl2 (25 mL) and filtered through a Whatman 1 lm PTFE membrane affording a deep red solution. Concentration to ca. 3 mL followed by flash column chromatography (silica gel; 3:1 petroleum ether:CH2Cl2 increasing polarity through 5:2 petroleum ether:CH2Cl2, to finally 5:4 petroleum ether:CH2Cl2) gave three fractions: a deep red band of 1 (40 mg), a red band of 2 (30 mg), and a bright red band of 3 (70 mg). Crystals of 1 and 2 were grown by diffusion of pentane into a CH2Cl2 solution at 30 C. For 1: 1H NMR (360 MHz, CD2Cl2): d (ppm): 1.29 (m, 9H, CH2Me, J(HH) = 8, J(PH) = 16), 2.35–2.61 (m, 6H, CH2Me), 3.46 (s, br, 1H cage CH), 7.11–7.51 (m, 10H, SPh); 13C NMR (90 MHz, CD2Cl2): d (ppm): 135.6–127.5 (m, Ph), 56.7 (s, br, cage CH), 18.3 (m, CH2Me), 8.5 (s, CH2Me); 11B NMR (115 MHz, CD2Cl2): d (ppm): 23.2 (1 B, BSPh), 19.7 (1 B), 12.2 (1 B), 9.8 (1 B), 2.7 (2 B), 6.3 (1 B), 7.4 (1 B), 11.6 (1 B), 17.3 (1 B); 31P NMR (145 MHz, CD2Cl2): d (ppm): 33.4 [J(PtP) = 3447]. Anal. Calc. for C19H35B10PPtS2: C, 34.5; H, 5.3. Found: C, 34.8; H, 5.5%. For 2: 1H NMR (360 MHz, CD2Cl2): d (ppm): 1.25 (m, 9H, CH2Me, J(HH) = 8, J(PH) = 16), 2.52 [m, 6H, CH2Me], 2.89 (s, br, 1H cage CH), 7.18–7.46 (m, 15H, SPh); 13C NMR (90 MHz, CD2Cl2): d (ppm): 134.3–128.1 (m, Ph), 44.1 (s, br, cage CH), 17.0 (d, CH2Me, J(PC) = 36), 7.0 (d, CH2Me, J(PC) = 4); 11B NMR (115 MHz, CD2Cl2): d (ppm): 24.2 (1 B, BSPh), 22.0 (1 B, BSPh), 16.1 (1 B), 9.9 (1 B), 2.3 (1 B), 4.1 (2 B),
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7.1 (1 B), 9.3 (1 B), 11.8 (1 B); 31P NMR (145 MHz, CD2Cl2): d (ppm): 41.6 [J(PtP) = 3255]. Anal. Calc. for C25H39B10PPtS3: C, 39.0; H, 5.1. Found: C, 39.1; H, 5.2%. For 3: 1H NMR (360 MHz, CD2Cl2): d (ppm): 1.25 (d of t J(PH) = 16, J(HH) = 8, 9H, CH2Me), 2.55 (d of q, J(PH) = 16, 6H, CH2Me), 2.90 (s, br, 1H cage CH), 7.13–7.41 (m, 5H, SPh); 13C NMR (90 MHz, CD2Cl2): d (ppm): 133.7–127.0 (m,Ph), 47.7 (s, br, cage CH), 16.6 (d, CH2Me, J(PC) = 36), 7.1 (d, CH2Me, J(PC) = 4); 11B NMR (115 MHz, CD2Cl2): d (ppm): 18.1 (1 B), 14.8 (2 B), 7.5 (2 B), 5.7 (1 B), 9.1 (2 B), 12.3 (2 B); 31P NMR (145 MHz, CD2Cl2): d (ppm): 41.5 [J(PtP) = 3294]. Anal. Calc for C13H31B10PPtS: C, 28.2; H, 5.6. Found: C, 28.0; H, 5.5%. 2.2. Synthesis of [Pt(SBut)(PEt3)(g5-7-CB10H11)] (4) Into a chilled ( 95 C) solution of Na[Pt(PEt3)2(g5-7CB10H11)] [0.50 mmol, prepared from 0.50 mmol Na3[CB10H11] and 0.50 mmol [PtCl2(PEt3)2] in thf (20 mL)] was introduced a solution But 2 S2 (0.10 g, 0.50 mmol) in thf (5 mL). The mixture was warmed to room temperature and stirred overnight. It was then heated at 40 C for 3 h during which period the mixture became orange–red in color. The thf was removed in vacuo, the residue taken up in CH2Cl2 (35 mL) and filtered through a Whatman 1 lm PTFE membrane affording a deep orange–red clear solution. Concentration to ca. 3 mL followed by flash column chromatography (hexane) developed a yellow–orange band of 4 (60 mg). Crystals of 4 were grown by slow cooling of a concentrated pentane solution (<0.5 mL) at 30 C. For 4: 1H NMR (360 MHz, CD2Cl2): d (ppm): 1.14 (m, 9H, CH2Me, J(HH) = 8 J(PH) = 16), 1.68 (s, 9H, But), 2.47 (m, 6H, CH2Me), 3.24 (s, br, 1H, cage CH); 13C NMR (90 MHz, CD2Cl2): d (ppm): 50.0 (s, br, cage CH), 47.7 (s, CMe3), 21.2 (s, CMe3), 17.0 (d, CH2Me, J(PC) = 36), 7.0 (d, CH2Me, J(PC) = 4); 11B NMR (115 MHz, CD2Cl2): d (ppm): 18.3 (1 B), 13.0 (2 B), 5.8 (2 B), 6.5 (1 B), 10.3 (2 B), 12.7 (2 B); 31P NMR (145 MHz, CD2Cl2): d (ppm): 45.1 [J(PtP) = 3249]. Anal. Calc. for C11H35B10PPtS: C, 23.3; H, 6.2. Found: C, 23.1; H, 6.4%. 2.3. Crystal structure determinations Crystals of the complexes 1, 2 and 4 were coated in high-vacuum grease and mounted on glass fibers. X-ray measurements were made using a Bruker SMART CCD area-detector diffractometer with Mo Ka radiation ˚ ) [15]. Intensities were integrated [16] from (k = 0.71073 A several series of exposures, each exposure covering 0.3 in x, and the total data set being a sphere. Absorption corrections were applied, based on multiple and symmetry-equivalent measurements [17]. The structures were solved by direct methods and refined by least squares on weighted F2 values for all reflections (see Table 1) [18].
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Table 1 Crystallographic data
Empirical formula Formula weight Temperature (K) ˚) Wavelength (A Crystal system Space group Unit cell dimensions ˚) a (A ˚) b (A ˚) c (A a () b () c () ˚ 3) Volume (A Z Dcalc (g cm 3) Absorption coefficient (mm 1) F(0 0 0) Crystal size (mm) h Range for data collection Reflections collected Independent reflections Refinement method Data/restraints/parameters Goodness-of-fit on F2 Final R indices [F2 > 2r(F2)] R indices (all data) ˚ 3) Largest difference in peak and hole (e/A
1
2
4
C19H35B10PPtS2 661.75 173(2) 0.71073 monoclinic P2(1)/n
C25H39B10PPtS3 769.90 173(2) 0.71073 monoclinic P2(1)/c
C22H70B20P2Pt2S2 1067.22 173(2) 0.71073 triclinic P 1
17.0682(5) 10.2865(3) 17.4439(5) 90 117.1560(10) 90 2725.05(14) 4 1.613 5.370 1296 0.40 · 0.30 · 0.20 2.26–27.49 16 605 6208 full-matrix least squares on F2 6207/0/301 0.960 R1 = 0.0228; wR2 = 0.0408 R1 = 0.0355; wR2 = 0.0437 0.457/ 0.612
10.0454(14) 31.562(3) 10.5178(13) 90 105.277(10) 90 3216.8(7) 4 1.590 4.264 1520 0.30 · 0.15 · 0.10 1.29–27.49 20 603 7354 full-matrix least squares on F2 7352/0/364 1.023 R1 = 0.0376; wR2 = 0.0577 R1 = 0.0679; wR2 = 0.0820 0.670/ 0.913
10.430(3) 14.161(4) 15.972(4) 103.25(3) 97.13(3) 101.27(2) 2216.6(10) 2 1.599 6.488 0.15 · 0.10 · 0.10 1.52–27.48 23 111 10 073 full-matrix least squares on F2 10 073/0/445 1.109 R1 = 0.0602; wR2 = 0.1307 R1 = 0.0847; wR2 = 0.1432 3.746/ 2.971
All non-hydrogen atoms were assigned anisotropic displacement parameters and refined without positional constraints. Hydrogen atoms were constrained to ideal geometries and refined with fixed isotropic displacement parameters. For complex 4 there are two independent molecules of the complex in the asymmetric unit. The C atoms in the cages of 4 are disordered over two sites. 3. Results and discussion 3.1. Synthesis Although it is very sensitive to moisture and subsequent protonation, the anion Na[Pt(PEt3)2(g5-CB10H11)] is readily prepared from [PtCl2(PEt3)2] and [Na]3[CB10H11]. Reaction of this monocarbon platinacarbaborane anion with diphenyl disulfide produced three isolable fractions after column chromatography (1–3). All of these compounds are highly soluble in organic solvents. In an analogous reaction with ditertiary-butyl disulfide, the reaction proceeded in a similar way but yielded 4 as the only isolable product even after repeated attempts and running the remaining fractions through a second column of silica gel. The structures of the compounds prepared in this work are shown in Scheme 1. 3.2. NMR studies The NMR data for all the compounds reported are in accord with the structures established by X-ray crystallography.
Scheme 1.
In 1, the 1H NMR spectrum reveals a characteristic broad singlet at d 3.46 assigned to the cage CH, while the corresponding 13C{1H} spectrum showed a resonance at d 56.7. In the 11B{1H} NMR spectrum there are nine signals (10 peaks) resulting from the asymmetry of the nidoCB10 cage. The peak at d 23.2 arises from the BSPh group – it remained as a singlet in the coupled 11B spectrum
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whereas the other peaks all showed the usual coupling [J(BH) > 100 Hz]. The 31P{1H} spectrum shows an expected singlet at d 33.4 with [J(PtP) 3447 Hz]. These resonances are close to those observed in the analogous selenium complex, [Pt(SePh)(PEt3)(g5-9-SePh-7-CB10H10)] [1]. Similarly in 2, the doubly substituted cage product shows a spectrum akin to that of 1: in this NMR study, the two substituted (BSPh) boron resonances were seen at d 24.2 and 22.0, both appearing as singlets in the fully coupled 11B spectrum. Again, a single peak is found in the 31P{1H} spectrum at d 41.6 with [J(PtP) 3255 Hz]. For compounds 3 and 4, there is no cage substitution and so a simpler series of peaks is observed in the 11 B{1H} NMR spectra. For instance, they both show six peaks in a 1:2:2:1:2:2 integration ratio with all the signals displaying coupling in the 11B spectra, indicative of no cage substituted B atoms. As with the previous two compounds, the 31P{1H} spectra indicates a single phosphorus environment [3: d 41.6 J(PtP) 3294 Hz; 4: d 45.1 J(PtP) 3249 Hz]. 3.3. Structural studies Crystals of 1 and 2 were grown by a slow pentane diffusion into a methylene chloride solution at low temperatures; crystals of 4 were prepared by chilling a concentrated pentane solution. Table 1 lists the data collection parameters and Tables 2–4 list selected bond distances and angles from the X-ray diffraction studies. Fig. 1 shows the molecular structure of 1. The platinum atom is ligated on one side by the open pentagonal face of the substituted g5-CB10H10 ligand and on the Table 2 ˚ ) and angles () for 1 Selected bond lengths (A Pt(1)–B(2) Pt(1)–B(4) Pt(1)–C(1) Pt(1)–P(1) B(2)–Pt(1)–B(4) B(2)–Pt(1)–C(1) B(4)–Pt(1)–C(1) B(2)–Pt(1)–B(5) B(4)–Pt(1)–B(5) C(1)–Pt(1)–B(5) B(2)–Pt(1)–B(3) B(4)–Pt(1)–B(3) C(1)–Pt(1)–B(3) B(5)–Pt(1)–B(3) B(2)–Pt(1)–S(2) B(4)–Pt(1)–S(2) C(1)–Pt(1)–S(2) B(5)–Pt(1)–S(2) B(3)–Pt(1)–S(2) B(2)–Pt(1)–P(1) B(4)–Pt(1)–P(1) C(1)–Pt(1)–P(1) B(5)–Pt(1)–P(1) B(3)–Pt(1)–P(1) S(2)–Pt(1)–P(1)
2.180(3) 2.221(4) 2.232(8) 2.3445(8)
Pt(1)–B(5) Pt(1)–B(3) Pt(1)–S(2) B(4)–S(1)
2.238(3) 2.260(4) 2.2890(8) 1.840(4) 82.73(14) 48.08(12) 80.53(13) 82.11(13) 51.27(13) 44.22(12) 48.55(14) 47.45(13) 81.06(12) 83.98(13) 128.28(11) 139.14(9) 100.56(8) 101.75(9) 173.30(9) 112.60(10) 106.94(10) 159.22(8) 153.55(10) 89.85(9) 86.48(3)
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Table 3 ˚ ) and angles () for 2 Selected bond lengths (A Pt(1)–B(2) Pt(1)–C(1) Pt(1)–B(5) Pt(1)–P(1) S(2)–B(2) S(3)–B(5)
2.195(5) 2.233(4) 2.200(5) 2.3335(12) 1.845(6) 1.855(5)
Pt(1)–B(3) Pt(1)–B(4) Pt(1)–S(1)
B(2)–Pt(1)–B(5) B(2)–Pt(1)–C(1) B(5)–Pt(1)–C(1) B(2)–Pt(1)–B(3) B(5)–Pt(1)–B(3) C(1)–Pt(1)–B(3) B(2)–Pt(1)–B(4) B(5)–Pt(1)–B(4) C(1)–Pt(1)–B(4) B(3)–Pt(1)–B(4) B(2)–Pt(1)–S(1) B(5)–Pt(1)–S(1) C(1)–Pt(1)–S(1) B(3)–Pt(1)–S(1) B(4)–Pt(1)–S(1) B(2)–Pt(1)–P(1) B(5)–Pt(1)–P(1) C(1)–Pt(1)–P(1) B(3)–Pt(1)–P(1) B(4)–Pt(1)–P(1) S(1)–Pt(1)–P(1)
2.233(5) 2.252(5) 2.3148(12)
82.9(2) 47.2(2) 46.7(2) 50.4(2) 84.0(2) 82.4(2) 83.6(2) 50.3(2) 81.9(2) 47.2(2) 112.0(2) 114.50(13) 97.54(12) 154.5(2) 158.24(14) 130.52(14) 133.0(2) 176.84(11) 94.48(14) 95.87(14) 85.38(4)
Table 4 ˚ ) and angles () for 4 Selected bond lengths (A Pt(1)–B(15) Pt(1)–C(11) Pt(1)–B(12) Pt(1)–P(1) Pt(2)–B(23) Pt(2)–C(24) B(15)–Pt(1)–B(13) B(15)–Pt(1)–C(11) B(13)–Pt(1)–C(11) B(15)–Pt(1)–C(14) B(13)–Pt(1)–C(14) C(11)–Pt(1)–C(14) B(15)–Pt(1)–B(12) B(13)–Pt(1)–B(12) C(11)–Pt(1)–B(12) C(14)–Pt(1)–B(12) B(15)–Pt(1)–S(1) B(13)–Pt(1)–S(1) C(11)–Pt(1)–S(1) C(14)–Pt(1)–S(1) B(12)–Pt(1)–S(1) B(15)–Pt(1)–P(1) B(13)–Pt(1)–P(1) C(11)–Pt(1)–P(1) C(14)–Pt(1)–P(1) B(12)–Pt(1)–P(1) S(1)–Pt(1)–P(1)
2.214(12) 2.231(11) 2.250(12) 2.326(2) 2.224(11) 2.241(10)
Pt(1)–B(13) Pt(1)–C(14) Pt(1)–S(1) Pt(2)–B(25) Pt(2)–B(22) Pt(2)–C(21)
2.218(13) 2.239(10) 2.267(3) 2.180(12) 2.234(10) 2.245(11) 81.2(5) 50.6(4) 82.7(5) 45.4(5) 46.2(5) 81.0(4) 83.3(4) 49.3(5) 47.3(5) 80.8(4) 116.1(3) 118.6(3) 154.9(4) 103.8(3) 157.2(3) 132.9(4) 130.3(4) 94.2(3) 174.2(3) 93.7(3) 81.88(9)
other by a PEt3 and phenyl sulfide groups. The lengths of Pt–C and Pt–B bonds to the cage atoms are very similar to those reported in the related Pt–SePh complex,
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Fig. 1. The molecular structure of [Pt(SPh)(PEt3)(g5-9-SPh-7-CB10H10)] (1) showing the crystallographic labeling scheme.
Fig. 2. The molecular structure of [Pt(SPh)(PEt3)(g5-8-SPh-11-SPh-7-CB10H9)] (2) showing the crystallographic labeling scheme.
[Pt(SePh)(PEt3)(g5-8-SePh-7-CB10H10) [1], and are in the ˚ . Likewise, the Pt–P bond length range 2.180(2)–2.260(4) A lies within the typical values seen in monocarbon platina˚ ]: for instance a discarbaborane complexes [2.3445(8) A ˚ tance of 2.349(1) A is observed in the bimetallic molecule, [PtAu(PEt3)2(PPh3)(g5-7-CB10H11)] [10]. The bond angles of the Pt–S(2)–Ph group [109.22(10)] in 1 suggest that the sulfur atom is sp3 hybridized and thus acting as a formal one electron donor to the metal center. Similarly, the B–S(1)–Ph group exhibits a bond angle of 104.6(2) again close to the expected value for sp3 hybridization. Therefore, it is possible to say that the PEt3 ligand and g5-9-SPh-7CB10H10 groups contribute two and three electrons respectively to the overall 16e count at the Pt center. Fig. 2 shows the molecular structure of 2. In this molecule, the cage is doubly substituted by SPh groups, at the 8
and 11 positions. As in 1, the Pt–C and Pt–B bond lengths ˚ ] and the Pt–P disare unremarkable [2.195(5)–2.252(5) A ˚ ]. tance is very close to that described above [2.3335(12) A The S–B distances between the phenyl sulfide groups and ˚ , close the carbaborane cage are 1.845(6) and 1.855(5) A to those in 1 but considerably shorter than the length of the S–B bonds found in the rhodacarbaborane, [3,3(CO)2-4-SMe2-3,1,2-Rh(g5-C2B9H11)] where an Me2S ˚ ] [19]. group is attached to a boron atom [1.893(3) A Fig. 3 shows the molecular structure of one of the independent molecules of 4. The platinum atom is coordinated to the pentahapto face of the unsubstituted g5-7-CB10H11 group in addition to a triethylphosphine and a tert-butyl sulfide group. As expected the Pt–S distance in this complex is somewhat shorter than in the Pt–SPh molecules described above due to the stronger ligating effect of the
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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 e-mail: deposit@ ccdc.cam.ac.uk. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.ica.2007.04.024. References
Fig. 3. The molecular structure of [Pt(SBut)(PEt3)(g5-7-CB10H11)] (4) showing the crystallographic labeling scheme.
alkyl group sulfide. The bond angle of 81.88(9) for S(1)– Pt(1)–P(1) is smaller than either of those in 1 and 2. In summary, a series of monocarbon platinacarbaborane complexes incorporating alkyl and aryl sulfides have been prepared and characterized for the first time. The products obtained from the reaction with diphenyl disulfide include cage substituted molecules that incorporate a phenyl sulfide group. Acknowledgements M.D.R. thanks Prof. F.G.A. Stone (Baylor University) for the use of laboratory and NMR facilities and the Professional Development Committee and Jim Perry at UW Fox for generous financial support of this research. Appendix A. Supplementary material CCDC 608860, 608861, and 617803 contain the supplementary crystallographic data for 1, 2, and 4. These data can be obtained free of charge via http://www.ccdc.cam.
[1] M.D. Rudd, F.G.A. Stone, S.A. Batten, J.C. Jeffery, L.H.J. Rees, Chem. Soc., Dalton Trans. (1998) 2839. [2] R.N. Grimes, in: E.W. Abel, F.G.A. Stone, G. Wilkinson, C.E. Housecroft (Eds.), Comprehensive Organometallic Chemistry II, vol. 1, Pergamon Press, Oxford, UK, 1995 (Chapter 9). [3] (a) D.M.P. Mingos, M.I. Forsyth, A.J.J. Welch, Chem. Soc., Dalton Trans. (1978) 1363; (b) D.R. Baghurst, R.C.B. Copley, H. Fleischer, D.M.P. Mingos, G.O. Kyd, L.J. Yellowlees, A.J. Welch, T.R. Spalding, D.J. O’Connell, Organomet. Chem. 447 (1993) C14. [4] M.L. Colquhoun, T.J. Greenhough, M.G.H. Wallbridge, J. Chem. Soc., Dalton Trans. (1985), 761; N.W. Alcock, J.G. Taylor, M.G.H. Wallbridge, J. Chem. Soc., Dalton Trans. (1987) 1805. [5] (a) M. Green, J.L. Spencer, F.G.A. Stone, A.J. Welch, J. Chem. Soc., Dalton Trans (1975) 179; (b) N. Carr, D.F. Mullica, E.L. Sapenfield, F.G.A. Stone, Inorg. Chem. 33 (1994) 1666. [6] W.A.G. Graham, R. Krentz, Unpublished results. See: R. Krentz, Ph.D. Thesis, University of Alberta, 1989. [7] L.F. Warren, M.F. Hawthorne, J. Am. Chem. Soc. 92 (1970) 1157. [8] F.G.A. Stone, J. Organomet. Chem. 100 (1975) 257. [9] W.E. Carroll, M. Green, F.G.A. Stone, A.J. Welch, J. Chem. Soc., Dalton Trans. (1975) 2263. [10] S.A. Batten, J.C. Jeffery, P.L. Jones, D.F. Mullica, M.D. Rudd, E.L. Sappenfield, F.G.A. Stone, A. Wolf, Inorg. Chem. 36 (1997) 2570. [11] I. Blandford, J.C. Jeffery, H. Redfearn, L.H. Rees, M.D. Rudd, F.G.A. Stone, J. Chem. Soc., Dalton Trans. (1998) 1669. [12] J. Plesk, T. Jelinek, E. Drdakova, B. Stirb, Collect. Czech. Chem. Commun. 49 (1984) 1559. [13] G.W. Parshall, Inorg. Synth. 12 (1970) 26. [14] H.W. Knoth, J.L. Little, J.R. Lawrence, F.R. Scholer, L.J. Todd, Inorg. Synth. 11 (1968) 33. [15] SMART Diffractometer Control Software, Bruker Analytical Instruments Inc., Madison, WI, 1998. [16] SAINT Integration Software, Siemens Analytical Instruments Inc., Madison, WI, 1994. [17] G.M. Sheldrick, SADABS: A Program for Absorption Correction with the Siemens SMART System, University of Go¨ttingen, Germany, 1996. [18] SHELXTL Program System Version 5.1; Bruker Analytical X-ray Instruments Inc., Madison, WI, 1998. [19] N.L. Douek, A.J. Welch, J. Chem. Soc., Dalton Trans. (1993) 1917.
Reactions of alkyl and aryl sulfides with a monocarbon platinacarbaborane anion Martin D. Rudd a
a,*
, John C. Jeffery
b
Department of Chemistry, University of Wisconsin – Fox Valley, 1478 Midway Road, Menasha, WI 54952, USA b School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom Received 12 January 2007; accepted 17 April 2007 Available online 4 May 2007
Abstract The reaction of the monocarbon carbaborane complex Na[Pt(PEt3)2(g5-CB10H11)] with some diaryl- and dialkyl disulfides has been investigated. With Ph2S2, two new cage substituted products are formed, [Pt(SPh)(PEt3)(g5-9-SPh-7-CB10H10)] (1) and [Pt(SPh)(PEt3)(g5-8-SPh-11-SPh-7-CB10H9)] (2), whereas with But 2 S2 the main product is the metal substituted complex, [Pt(SBut)(PEt3)(g5-7-CB10H11)] (4). All three new molecules have been identified spectroscopically (1H, 13C, 31P, 11B NMR) and through single crystal X-ray diffraction. 2007 Elsevier B.V. All rights reserved. Keywords: Monocarbon carbaborane; Platinum complex; Sulfur derivative; Crystal structure
1. Introduction In an earlier paper, we described an extensive set of novel monocarbon platinacarborane complexes with selenium and tellurium substitutents synthesized by the reaction of the anion Na[Pt(PEt3)2(g5-CB10H11)] with diphenyl diselenide and diphenyl ditelluride. We found that column chromatography was able to separate a mixture of cage and metal substituted products [1]. With this in mind, investigations into the reactions of some analogous diaryl/ dialkyl disulfides have been carried out. Monocarbon metallacarboranes are substantially less studied that their dicarbon metallacarborane counterparts [2]. A search of the literature reveals that there are several complexes with a platinacarborane closo-PtC2B9 cage system [3–7] but only a few examples of the monocarbon equivalent closo-PtCB10 cage. Before the commencement of this work, those two complexes were [NMe4][Pt(PEt3)2(g5-7-CB10H11)] and [Pt(PEt3)2(g5-7-NMe3-7-CB10H10)] which were synthesized by the expansion of the carborane *
Corresponding author. Tel.: +1 920 832 2694. E-mail address: [email protected] (M.D. Rudd).
0020-1693/$ - see front matter 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2007.04.024
polyhedron [8,9]. We have found in our studies that there are substantial reactivity differences between the anionic [Pt(PEt3)2(g5-7-CB10H11)] species (where the CB10H11 group formally donates three electrons to the platinum atom) and the unreactive (at the metal center) [Pt(PEt3)2(g5-7,8-C2B9H11)] in which the cage behaves as a four electron donor. For instance we found that the nucleophilic platinum atom reacts with a variety of electrophilic transition metal cations, such as Ph3PAu+, PhHg+ and Ph3PCu+ [10] and acids [11] yielding novel dimetallic species. In addition, in Ref. [1], we described the formation of (cage)Pt–Se and (cage)Pt–Te complexes following the addition of the electrophilic ‘‘PhSe+’’ and ‘‘PhTe+’’ species to the [Pt(PEt3)2(g5-7-CB10H11)] anion. As a follow up to this work, we present here some studies of the reaction of diaryl and dialkyl disulfides with this monocarbon platinacarborane anion. 2. Experimental All experiments were conducted under an atmosphere of dry argon using Schlenk tube techniques. Solvents were freshly distilled under nitrogen from appropriate drying
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agents before use. Light petroleum refers to the fraction of boiling point 40–60 C. Tetrahydrofuran was distilled from K/benzophenone under nitrogen and stored over Na/K alloy. Chromatography columns (ca. 30 cm long and 3 cm in diameter) were packed under nitrogen with silica gel (Acros 70–230 mesh). The NMR spectra were recorded at the following frequencies: 1H 360.13 MHz, 13C 90.56 MHz, 31P 145.78 MHz and 11B 115.55 MHz. 7-Me3N-7-CB10H12 [12] and [PtCl2(PEt3)2] [13] were prepared according to the literature methods. [Na]3[CB10H11] was synthesized according to the method of Knoth et al. [14] and Na[Pt(PEt3)2(g5-CB10H11)] [10] was prepared as described in an earlier paper. Ph2S2 and But 2 S2 were purchased from Aldrich and used as supplied. 5
2.1. Synthesis of [Pt(SPh)(PEt3)(g -9-SPh-7-CB10H10)] (1), [Pt(SPh)(PEt3)(g5-8-SPh-11-SPh-7-CB10H9)] (2) and [Pt(SPh)(PEt3)(g5-7-CB10H11)] (3) Into a chilled ( 95 C) solution of Na[Pt(PEt3)2(g5-7CB10H11)] [0.50 mmol, prepared from 0.50 mmol Na3[CB10H11] and 0.50 mmol [PtCl2(PEt3)2] in thf (tetrahydrofuran, 20 mL)] was introduced a solution of Ph2S2 (0.11 g, 0.50 mmol) in thf (15 mL). The reaction was brought to room temperature and stirred for 2 h then warmed at 40 C for a further 2 h during which it turned a deep red color. The thf was removed in vacuo, the residue taken up in CH2Cl2 (25 mL) and filtered through a Whatman 1 lm PTFE membrane affording a deep red solution. Concentration to ca. 3 mL followed by flash column chromatography (silica gel; 3:1 petroleum ether:CH2Cl2 increasing polarity through 5:2 petroleum ether:CH2Cl2, to finally 5:4 petroleum ether:CH2Cl2) gave three fractions: a deep red band of 1 (40 mg), a red band of 2 (30 mg), and a bright red band of 3 (70 mg). Crystals of 1 and 2 were grown by diffusion of pentane into a CH2Cl2 solution at 30 C. For 1: 1H NMR (360 MHz, CD2Cl2): d (ppm): 1.29 (m, 9H, CH2Me, J(HH) = 8, J(PH) = 16), 2.35–2.61 (m, 6H, CH2Me), 3.46 (s, br, 1H cage CH), 7.11–7.51 (m, 10H, SPh); 13C NMR (90 MHz, CD2Cl2): d (ppm): 135.6–127.5 (m, Ph), 56.7 (s, br, cage CH), 18.3 (m, CH2Me), 8.5 (s, CH2Me); 11B NMR (115 MHz, CD2Cl2): d (ppm): 23.2 (1 B, BSPh), 19.7 (1 B), 12.2 (1 B), 9.8 (1 B), 2.7 (2 B), 6.3 (1 B), 7.4 (1 B), 11.6 (1 B), 17.3 (1 B); 31P NMR (145 MHz, CD2Cl2): d (ppm): 33.4 [J(PtP) = 3447]. Anal. Calc. for C19H35B10PPtS2: C, 34.5; H, 5.3. Found: C, 34.8; H, 5.5%. For 2: 1H NMR (360 MHz, CD2Cl2): d (ppm): 1.25 (m, 9H, CH2Me, J(HH) = 8, J(PH) = 16), 2.52 [m, 6H, CH2Me], 2.89 (s, br, 1H cage CH), 7.18–7.46 (m, 15H, SPh); 13C NMR (90 MHz, CD2Cl2): d (ppm): 134.3–128.1 (m, Ph), 44.1 (s, br, cage CH), 17.0 (d, CH2Me, J(PC) = 36), 7.0 (d, CH2Me, J(PC) = 4); 11B NMR (115 MHz, CD2Cl2): d (ppm): 24.2 (1 B, BSPh), 22.0 (1 B, BSPh), 16.1 (1 B), 9.9 (1 B), 2.3 (1 B), 4.1 (2 B),
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7.1 (1 B), 9.3 (1 B), 11.8 (1 B); 31P NMR (145 MHz, CD2Cl2): d (ppm): 41.6 [J(PtP) = 3255]. Anal. Calc. for C25H39B10PPtS3: C, 39.0; H, 5.1. Found: C, 39.1; H, 5.2%. For 3: 1H NMR (360 MHz, CD2Cl2): d (ppm): 1.25 (d of t J(PH) = 16, J(HH) = 8, 9H, CH2Me), 2.55 (d of q, J(PH) = 16, 6H, CH2Me), 2.90 (s, br, 1H cage CH), 7.13–7.41 (m, 5H, SPh); 13C NMR (90 MHz, CD2Cl2): d (ppm): 133.7–127.0 (m,Ph), 47.7 (s, br, cage CH), 16.6 (d, CH2Me, J(PC) = 36), 7.1 (d, CH2Me, J(PC) = 4); 11B NMR (115 MHz, CD2Cl2): d (ppm): 18.1 (1 B), 14.8 (2 B), 7.5 (2 B), 5.7 (1 B), 9.1 (2 B), 12.3 (2 B); 31P NMR (145 MHz, CD2Cl2): d (ppm): 41.5 [J(PtP) = 3294]. Anal. Calc for C13H31B10PPtS: C, 28.2; H, 5.6. Found: C, 28.0; H, 5.5%. 2.2. Synthesis of [Pt(SBut)(PEt3)(g5-7-CB10H11)] (4) Into a chilled ( 95 C) solution of Na[Pt(PEt3)2(g5-7CB10H11)] [0.50 mmol, prepared from 0.50 mmol Na3[CB10H11] and 0.50 mmol [PtCl2(PEt3)2] in thf (20 mL)] was introduced a solution But 2 S2 (0.10 g, 0.50 mmol) in thf (5 mL). The mixture was warmed to room temperature and stirred overnight. It was then heated at 40 C for 3 h during which period the mixture became orange–red in color. The thf was removed in vacuo, the residue taken up in CH2Cl2 (35 mL) and filtered through a Whatman 1 lm PTFE membrane affording a deep orange–red clear solution. Concentration to ca. 3 mL followed by flash column chromatography (hexane) developed a yellow–orange band of 4 (60 mg). Crystals of 4 were grown by slow cooling of a concentrated pentane solution (<0.5 mL) at 30 C. For 4: 1H NMR (360 MHz, CD2Cl2): d (ppm): 1.14 (m, 9H, CH2Me, J(HH) = 8 J(PH) = 16), 1.68 (s, 9H, But), 2.47 (m, 6H, CH2Me), 3.24 (s, br, 1H, cage CH); 13C NMR (90 MHz, CD2Cl2): d (ppm): 50.0 (s, br, cage CH), 47.7 (s, CMe3), 21.2 (s, CMe3), 17.0 (d, CH2Me, J(PC) = 36), 7.0 (d, CH2Me, J(PC) = 4); 11B NMR (115 MHz, CD2Cl2): d (ppm): 18.3 (1 B), 13.0 (2 B), 5.8 (2 B), 6.5 (1 B), 10.3 (2 B), 12.7 (2 B); 31P NMR (145 MHz, CD2Cl2): d (ppm): 45.1 [J(PtP) = 3249]. Anal. Calc. for C11H35B10PPtS: C, 23.3; H, 6.2. Found: C, 23.1; H, 6.4%. 2.3. Crystal structure determinations Crystals of the complexes 1, 2 and 4 were coated in high-vacuum grease and mounted on glass fibers. X-ray measurements were made using a Bruker SMART CCD area-detector diffractometer with Mo Ka radiation ˚ ) [15]. Intensities were integrated [16] from (k = 0.71073 A several series of exposures, each exposure covering 0.3 in x, and the total data set being a sphere. Absorption corrections were applied, based on multiple and symmetry-equivalent measurements [17]. The structures were solved by direct methods and refined by least squares on weighted F2 values for all reflections (see Table 1) [18].
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Table 1 Crystallographic data
Empirical formula Formula weight Temperature (K) ˚) Wavelength (A Crystal system Space group Unit cell dimensions ˚) a (A ˚) b (A ˚) c (A a () b () c () ˚ 3) Volume (A Z Dcalc (g cm 3) Absorption coefficient (mm 1) F(0 0 0) Crystal size (mm) h Range for data collection Reflections collected Independent reflections Refinement method Data/restraints/parameters Goodness-of-fit on F2 Final R indices [F2 > 2r(F2)] R indices (all data) ˚ 3) Largest difference in peak and hole (e/A
1
2
4
C19H35B10PPtS2 661.75 173(2) 0.71073 monoclinic P2(1)/n
C25H39B10PPtS3 769.90 173(2) 0.71073 monoclinic P2(1)/c
C22H70B20P2Pt2S2 1067.22 173(2) 0.71073 triclinic P 1
17.0682(5) 10.2865(3) 17.4439(5) 90 117.1560(10) 90 2725.05(14) 4 1.613 5.370 1296 0.40 · 0.30 · 0.20 2.26–27.49 16 605 6208 full-matrix least squares on F2 6207/0/301 0.960 R1 = 0.0228; wR2 = 0.0408 R1 = 0.0355; wR2 = 0.0437 0.457/ 0.612
10.0454(14) 31.562(3) 10.5178(13) 90 105.277(10) 90 3216.8(7) 4 1.590 4.264 1520 0.30 · 0.15 · 0.10 1.29–27.49 20 603 7354 full-matrix least squares on F2 7352/0/364 1.023 R1 = 0.0376; wR2 = 0.0577 R1 = 0.0679; wR2 = 0.0820 0.670/ 0.913
10.430(3) 14.161(4) 15.972(4) 103.25(3) 97.13(3) 101.27(2) 2216.6(10) 2 1.599 6.488 0.15 · 0.10 · 0.10 1.52–27.48 23 111 10 073 full-matrix least squares on F2 10 073/0/445 1.109 R1 = 0.0602; wR2 = 0.1307 R1 = 0.0847; wR2 = 0.1432 3.746/ 2.971
All non-hydrogen atoms were assigned anisotropic displacement parameters and refined without positional constraints. Hydrogen atoms were constrained to ideal geometries and refined with fixed isotropic displacement parameters. For complex 4 there are two independent molecules of the complex in the asymmetric unit. The C atoms in the cages of 4 are disordered over two sites. 3. Results and discussion 3.1. Synthesis Although it is very sensitive to moisture and subsequent protonation, the anion Na[Pt(PEt3)2(g5-CB10H11)] is readily prepared from [PtCl2(PEt3)2] and [Na]3[CB10H11]. Reaction of this monocarbon platinacarbaborane anion with diphenyl disulfide produced three isolable fractions after column chromatography (1–3). All of these compounds are highly soluble in organic solvents. In an analogous reaction with ditertiary-butyl disulfide, the reaction proceeded in a similar way but yielded 4 as the only isolable product even after repeated attempts and running the remaining fractions through a second column of silica gel. The structures of the compounds prepared in this work are shown in Scheme 1. 3.2. NMR studies The NMR data for all the compounds reported are in accord with the structures established by X-ray crystallography.
Scheme 1.
In 1, the 1H NMR spectrum reveals a characteristic broad singlet at d 3.46 assigned to the cage CH, while the corresponding 13C{1H} spectrum showed a resonance at d 56.7. In the 11B{1H} NMR spectrum there are nine signals (10 peaks) resulting from the asymmetry of the nidoCB10 cage. The peak at d 23.2 arises from the BSPh group – it remained as a singlet in the coupled 11B spectrum
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whereas the other peaks all showed the usual coupling [J(BH) > 100 Hz]. The 31P{1H} spectrum shows an expected singlet at d 33.4 with [J(PtP) 3447 Hz]. These resonances are close to those observed in the analogous selenium complex, [Pt(SePh)(PEt3)(g5-9-SePh-7-CB10H10)] [1]. Similarly in 2, the doubly substituted cage product shows a spectrum akin to that of 1: in this NMR study, the two substituted (BSPh) boron resonances were seen at d 24.2 and 22.0, both appearing as singlets in the fully coupled 11B spectrum. Again, a single peak is found in the 31P{1H} spectrum at d 41.6 with [J(PtP) 3255 Hz]. For compounds 3 and 4, there is no cage substitution and so a simpler series of peaks is observed in the 11 B{1H} NMR spectra. For instance, they both show six peaks in a 1:2:2:1:2:2 integration ratio with all the signals displaying coupling in the 11B spectra, indicative of no cage substituted B atoms. As with the previous two compounds, the 31P{1H} spectra indicates a single phosphorus environment [3: d 41.6 J(PtP) 3294 Hz; 4: d 45.1 J(PtP) 3249 Hz]. 3.3. Structural studies Crystals of 1 and 2 were grown by a slow pentane diffusion into a methylene chloride solution at low temperatures; crystals of 4 were prepared by chilling a concentrated pentane solution. Table 1 lists the data collection parameters and Tables 2–4 list selected bond distances and angles from the X-ray diffraction studies. Fig. 1 shows the molecular structure of 1. The platinum atom is ligated on one side by the open pentagonal face of the substituted g5-CB10H10 ligand and on the Table 2 ˚ ) and angles () for 1 Selected bond lengths (A Pt(1)–B(2) Pt(1)–B(4) Pt(1)–C(1) Pt(1)–P(1) B(2)–Pt(1)–B(4) B(2)–Pt(1)–C(1) B(4)–Pt(1)–C(1) B(2)–Pt(1)–B(5) B(4)–Pt(1)–B(5) C(1)–Pt(1)–B(5) B(2)–Pt(1)–B(3) B(4)–Pt(1)–B(3) C(1)–Pt(1)–B(3) B(5)–Pt(1)–B(3) B(2)–Pt(1)–S(2) B(4)–Pt(1)–S(2) C(1)–Pt(1)–S(2) B(5)–Pt(1)–S(2) B(3)–Pt(1)–S(2) B(2)–Pt(1)–P(1) B(4)–Pt(1)–P(1) C(1)–Pt(1)–P(1) B(5)–Pt(1)–P(1) B(3)–Pt(1)–P(1) S(2)–Pt(1)–P(1)
2.180(3) 2.221(4) 2.232(8) 2.3445(8)
Pt(1)–B(5) Pt(1)–B(3) Pt(1)–S(2) B(4)–S(1)
2.238(3) 2.260(4) 2.2890(8) 1.840(4) 82.73(14) 48.08(12) 80.53(13) 82.11(13) 51.27(13) 44.22(12) 48.55(14) 47.45(13) 81.06(12) 83.98(13) 128.28(11) 139.14(9) 100.56(8) 101.75(9) 173.30(9) 112.60(10) 106.94(10) 159.22(8) 153.55(10) 89.85(9) 86.48(3)
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Table 3 ˚ ) and angles () for 2 Selected bond lengths (A Pt(1)–B(2) Pt(1)–C(1) Pt(1)–B(5) Pt(1)–P(1) S(2)–B(2) S(3)–B(5)
2.195(5) 2.233(4) 2.200(5) 2.3335(12) 1.845(6) 1.855(5)
Pt(1)–B(3) Pt(1)–B(4) Pt(1)–S(1)
B(2)–Pt(1)–B(5) B(2)–Pt(1)–C(1) B(5)–Pt(1)–C(1) B(2)–Pt(1)–B(3) B(5)–Pt(1)–B(3) C(1)–Pt(1)–B(3) B(2)–Pt(1)–B(4) B(5)–Pt(1)–B(4) C(1)–Pt(1)–B(4) B(3)–Pt(1)–B(4) B(2)–Pt(1)–S(1) B(5)–Pt(1)–S(1) C(1)–Pt(1)–S(1) B(3)–Pt(1)–S(1) B(4)–Pt(1)–S(1) B(2)–Pt(1)–P(1) B(5)–Pt(1)–P(1) C(1)–Pt(1)–P(1) B(3)–Pt(1)–P(1) B(4)–Pt(1)–P(1) S(1)–Pt(1)–P(1)
2.233(5) 2.252(5) 2.3148(12)
82.9(2) 47.2(2) 46.7(2) 50.4(2) 84.0(2) 82.4(2) 83.6(2) 50.3(2) 81.9(2) 47.2(2) 112.0(2) 114.50(13) 97.54(12) 154.5(2) 158.24(14) 130.52(14) 133.0(2) 176.84(11) 94.48(14) 95.87(14) 85.38(4)
Table 4 ˚ ) and angles () for 4 Selected bond lengths (A Pt(1)–B(15) Pt(1)–C(11) Pt(1)–B(12) Pt(1)–P(1) Pt(2)–B(23) Pt(2)–C(24) B(15)–Pt(1)–B(13) B(15)–Pt(1)–C(11) B(13)–Pt(1)–C(11) B(15)–Pt(1)–C(14) B(13)–Pt(1)–C(14) C(11)–Pt(1)–C(14) B(15)–Pt(1)–B(12) B(13)–Pt(1)–B(12) C(11)–Pt(1)–B(12) C(14)–Pt(1)–B(12) B(15)–Pt(1)–S(1) B(13)–Pt(1)–S(1) C(11)–Pt(1)–S(1) C(14)–Pt(1)–S(1) B(12)–Pt(1)–S(1) B(15)–Pt(1)–P(1) B(13)–Pt(1)–P(1) C(11)–Pt(1)–P(1) C(14)–Pt(1)–P(1) B(12)–Pt(1)–P(1) S(1)–Pt(1)–P(1)
2.214(12) 2.231(11) 2.250(12) 2.326(2) 2.224(11) 2.241(10)
Pt(1)–B(13) Pt(1)–C(14) Pt(1)–S(1) Pt(2)–B(25) Pt(2)–B(22) Pt(2)–C(21)
2.218(13) 2.239(10) 2.267(3) 2.180(12) 2.234(10) 2.245(11) 81.2(5) 50.6(4) 82.7(5) 45.4(5) 46.2(5) 81.0(4) 83.3(4) 49.3(5) 47.3(5) 80.8(4) 116.1(3) 118.6(3) 154.9(4) 103.8(3) 157.2(3) 132.9(4) 130.3(4) 94.2(3) 174.2(3) 93.7(3) 81.88(9)
other by a PEt3 and phenyl sulfide groups. The lengths of Pt–C and Pt–B bonds to the cage atoms are very similar to those reported in the related Pt–SePh complex,
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Fig. 1. The molecular structure of [Pt(SPh)(PEt3)(g5-9-SPh-7-CB10H10)] (1) showing the crystallographic labeling scheme.
Fig. 2. The molecular structure of [Pt(SPh)(PEt3)(g5-8-SPh-11-SPh-7-CB10H9)] (2) showing the crystallographic labeling scheme.
[Pt(SePh)(PEt3)(g5-8-SePh-7-CB10H10) [1], and are in the ˚ . Likewise, the Pt–P bond length range 2.180(2)–2.260(4) A lies within the typical values seen in monocarbon platina˚ ]: for instance a discarbaborane complexes [2.3445(8) A ˚ tance of 2.349(1) A is observed in the bimetallic molecule, [PtAu(PEt3)2(PPh3)(g5-7-CB10H11)] [10]. The bond angles of the Pt–S(2)–Ph group [109.22(10)] in 1 suggest that the sulfur atom is sp3 hybridized and thus acting as a formal one electron donor to the metal center. Similarly, the B–S(1)–Ph group exhibits a bond angle of 104.6(2) again close to the expected value for sp3 hybridization. Therefore, it is possible to say that the PEt3 ligand and g5-9-SPh-7CB10H10 groups contribute two and three electrons respectively to the overall 16e count at the Pt center. Fig. 2 shows the molecular structure of 2. In this molecule, the cage is doubly substituted by SPh groups, at the 8
and 11 positions. As in 1, the Pt–C and Pt–B bond lengths ˚ ] and the Pt–P disare unremarkable [2.195(5)–2.252(5) A ˚ ]. tance is very close to that described above [2.3335(12) A The S–B distances between the phenyl sulfide groups and ˚ , close the carbaborane cage are 1.845(6) and 1.855(5) A to those in 1 but considerably shorter than the length of the S–B bonds found in the rhodacarbaborane, [3,3(CO)2-4-SMe2-3,1,2-Rh(g5-C2B9H11)] where an Me2S ˚ ] [19]. group is attached to a boron atom [1.893(3) A Fig. 3 shows the molecular structure of one of the independent molecules of 4. The platinum atom is coordinated to the pentahapto face of the unsubstituted g5-7-CB10H11 group in addition to a triethylphosphine and a tert-butyl sulfide group. As expected the Pt–S distance in this complex is somewhat shorter than in the Pt–SPh molecules described above due to the stronger ligating effect of the
M.D. Rudd, J.C. Jeffery / Inorganica Chimica Acta 360 (2007) 3394–3399
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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 e-mail: deposit@ ccdc.cam.ac.uk. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.ica.2007.04.024. References
Fig. 3. The molecular structure of [Pt(SBut)(PEt3)(g5-7-CB10H11)] (4) showing the crystallographic labeling scheme.
alkyl group sulfide. The bond angle of 81.88(9) for S(1)– Pt(1)–P(1) is smaller than either of those in 1 and 2. In summary, a series of monocarbon platinacarbaborane complexes incorporating alkyl and aryl sulfides have been prepared and characterized for the first time. The products obtained from the reaction with diphenyl disulfide include cage substituted molecules that incorporate a phenyl sulfide group. Acknowledgements M.D.R. thanks Prof. F.G.A. Stone (Baylor University) for the use of laboratory and NMR facilities and the Professional Development Committee and Jim Perry at UW Fox for generous financial support of this research. Appendix A. Supplementary material CCDC 608860, 608861, and 617803 contain the supplementary crystallographic data for 1, 2, and 4. These data can be obtained free of charge via http://www.ccdc.cam.
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