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Organometallics 2009, 28, 2294–2299
From a Stannene and Quinones to Various Tin-Containing Heterocycles Dumitru Ghereg,† Henri Ranaivonjatovo,† Nathalie Saffon,‡ Heinz Gornitzka,*,§ and Jean Escudie´*,† UniVersite´ de Toulouse, UPS, LHFA, 118 Route de Narbonne, F-31062 Toulouse, France, CNRS, LHFA, UMR 5069, F-31062 Toulouse Cedex 09, France, Structure Fe´de´ratiVe Toulousaine en Chimie Mole´culaire, FR 2599, UniVersite´ Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 09, France, and Laboratoire de Chimie de Coordination du CNRS, 205 Route de Narbonne, 31077 Toulouse Cedex 04, France ReceiVed December 19, 2008
Some fused tin-containing heterocycles were prepared from the novel thermally stable stannene Tip2SndCR2 (1; Tip ) 2,4,6-triisopropylphenyl, CR2 ) 2,7-di-tert-butylfluorenylidene) and a series of quinones. Reaction of 1 with 1,4-benzoquinone afforded the unexpected conjugated 1,4-distannoxy-1,3cyclohexadiene 2, according to a double [2+3] cycloaddition. In contrast, in 1,4-naphthoquinone and 9,10-anthraquinone the aromatic ring fused to the quinonic moiety was involved in the reaction, leading to hexahydrodioxadistannapyrene 3 and hexahydrodioxadistannabenzopyrene 4. Ortho-quinones, such as 9,10-phenanthrenequinone, gave by [2+4] cycloaddition the dioxastannacyclohexene 5. All compounds were submitted to detailed 1H and 13C NMR study. The structures of 2, 3, and 5 were determined by X-ray crystallography. Introduction Metallaalkenes of group 14 elements >MdC< (M ) Si, Ge, Sn), heavier congeners of alkenes, have received great attention because of their synthetic challenge as well as of their reactivity and have been the subject of a number of theoretical, structural, and mechanistic studies.1 Although these elements belong to the same periodic group as carbon, they demonstrate much lesser ability to form stable double bonds. Over the past two decades, such derivatives, which for a long time have been characterized * Corresponding author. E-mail:
[email protected]. † UPS, LHFA, Universite´ de Toulouse and CNRS, LHFA, UMR 5069. ‡ Universite´ Paul Sabatier. § Laboratoire de Chimie de Coordination du CNRS. (1) For reviews, see: (a) Power, P. P. Chem. ReV. 1999, 99, 3463. (b) Okazaki, R.; West, R. AdV. Organomet. Chem. 1996, 39, 231. (c) West, R. Polyhedron 2002, 21, 467. (d) Sekiguchi, A.; Lee, V. Ya. Chem. ReV. 2003, 103, 1429. (e) Tokitoh, N. Acc. Chem. Res. 2004, 37, 86. (f) Brook, A. G.; Brook, M. A. AdV. Organomet. Chem. 1996, 39, 71. (g) Mu¨ller, T.; Ziche, W.; Auner, N. In The Chemistry of Organic Silicon Compounds; Rappoport, Z., Apeloig, Y., Eds.; Wiley: New York, 1998; Vol. 2, Chapter 16. (h) Baines, K. M.; Stibbs, W. G. AdV. Organomet. Chem. 1996, 39, 275. (i) Escudie´, J.; Ranaivonjatovo, H. AdV. Organomet. Chem. 1999, 44, 113. (j) Escudie´, J.; Couret, C.; Ranaivonjatovo, H. J. Coord. Chem. ReV. 1998, 178, 565. (k) Lee, V. Ya.; Sekiguchi, A. Organometallics 2004, 23, 2822. (2) Berndt, A.; Meyer, H.; Baum, G.; Massa, W.; Berger, S. Pure Appl. Chem. 1987, 59, 1011. (3) Meyer, H.; Baum, G.; Massa, W.; Berger, S.; Berndt, A. Angew. Chem., Int. Ed. Engl. 1987, 26, 546. (4) Weidenbruch, M.; Kilian, H.; Stu¨rmann, M.; Pohl, S.; Saak, W.; Marsmann, H.; Steiner, D.; Berndt, A. J. Organomet. Chem. 1997, 530, 255. (5) Stu¨rmann, M.; Saak, W.; Weidenbruch, M.; Berndt, A.; Scheschkewitz, D. Heteroat. Chem. 1999, 10, 554. (6) (a) Anselme, G.; Ranaivonjatovo, H.; Escudie´, J.; Couret, C.; Satge´, J. Organometallics 1992, 11, 2748. (b) Anselme, G.; Declercq, J.-P.; Dubourg, A.; Ranaivonjatovo, H.; Escudie´, J.; Couret, C. J. Organomet. Chem. 1993, 458, 49. (7) Mizuhata, Y.; Takeda, N.; Sasamori, T.; Tokitoh, N. Chem. Commun. 2005, 5876. (8) The SndC bond is included in the aromatic structure of a stannanaphthalene: Mizuhata, Y.; Sasamori, T.; Takeda, N.; Tokitoh, N. J. Am. Chem. Soc. 2006, 128, 1050.
only by trapping reactions, have been kinetically stabilized and their chemical behavior has been largely explored. However, this is not the case for the stannenes >SndCGedCMdP-,18 M ) Ge, Sn) with ortho-quinones, such as tetrachloro-o-benzoquinone, 3,5-di-tert-butyl-o-benzoquinone, and 1,2-naphthoquinone. In addition, a similar [2+4] cycloaddition has also been reported between this quinone and a stable fused bicyclic disilene.19 The X-ray structure of 5 displayed a tetracyclic compound with two oxygen and one tin atom; the phenanthrene fragment is perfectly planar, whereas the dioxastannacyclohexene ring adopts a slightly distorted sofa conformation with the C1 atom being 0.733 Å out of the mean planeO2-C23-C22-O1-Sn1.ThetorsionangleC23-C22-O1-Sn1 is 27.3°. Noteworthy is also the elongation of the Sn1-C1 bond (2.225(2) Å) due to the high steric hindrance of the bulky Tip and CR2 groups.20
A dynamic 1H NMR experiment between 213 and 313 K in toluene-d8 allowed the determination of the rotation barrier (18.34 kcal/mol, Tc ) 303 K) of one Tip group around the ipsoC-Sn bond from the evolution of the methyl signals; this rather high rotation barrier reflects the great steric hindrance caused by the large Tip and CR2 groups. The signals in the aliphatic zone appear clearly defined around 263 K, showing 12 doublets between 0.29 and 1.78 ppm for all nonequivalent methyl groups. The high steric hindrance is also probably responsible for the air and moisture stability of 5: addition of water to its THF solution does not cleave the Sn-O bond. Again, the well-known oxophilic character of tin and the formation of the strong C-O bond should be involved as driving forces in this reaction. Furthermore, the formation of sixmembered heterocycle 5 induces aromaticity on the central quinonic ring. In conclusion, depending on the para-quinone used, stannene 1 reacts in two different fashions, whereas in the case of orthoquinones the expected [2+4] cycloadduct is observed. The high reactivity of 1 will allow further investigations on the potential synthetic applications of this powerful building block.
Experimental Section General Experimental Details. All experiments were performed in flame-dried glassware under an argon atmosphere using standard (17) Meiners, F.; Haase, D.; Koch, R.; Saak, W.; Weidenbruch, M. Organometallics 2002, 21, 3990. (18) Kandri-Rodi, A.; Declercq, J.-P.; Dubourg, A.; Ranaivonjatovo, H.; Escudie´, J. Organometallics 1995, 14, 1954. (19) Kobayashi, H.; Iwamoto, T.; Kira, M. J. Am. Chem. Soc. 2005, 127, 15376. (20) MacKay, K. M. In The Chemistry of Organic Germanium, Tin and Lead Compounds; Patai, S., Ed.;Wiley: Chichester, 1995; Vol. 1, Chapter 2.
Organometallics, Vol. 28, No. 7, 2009 2297 vacuum-line, Schlenk, and cannula techniques, with solvents being distilled over standard drying agents and degassed before use. 1,4Naphthoquinone was recrystallized from diethyl ether prior to use. All other reagents were purchased from Aldrich and were used without further purification. Deuterated solvents were dried and stored over 4 Å molecular sieves. NMR spectra were recorded in CDCl3 on a Bruker Avance 300 instrument at the following frequencies: 300.13 MHz (1H, reference TMS), 75.47 MHz (13C{1H}, reference TMS), 111.92 MHz (119Sn{1H}, reference Me4Sn). 1H and 13C{1H} NMR assignments were confirmed by 1H COSY, HSQC (1H-13C), and HMBC (1H-13C) experiments. Mass spectra were measured on a Nermag R10-10 spectrometer by CI (NH3 or CH4). Melting points were determined on a Leitz microscope heating stage 250 or Electrothermal apparatus (capillary). Elemental analyses were performed by the “Service de Microanalyse de l’Ecole de Chimie de Toulouse”. The yields were calculated from the starting precursor Tip2Sn(F)-CHR2. All data for structures were collected at low temperature using an oil-coated shock-cooled crystal on a Bruker-AXS Apex II diffractometer with Mo KR radiation (λ ) 0.7107 Å) and are summarized in Table 1. The structures were solved by direct methods21 and all non-hydrogen atoms were refined anisotropically using the least-squares method on F2.22 For the 1H and 13C NMR study, the carbon atoms of the fluorenyl group are numbered as shown in Chart 1. Some signals of o-CHMeMe′ and m-CH of 2,4,6-triisopropylphenyl groups were not observed because of the coalescence caused by their hindered rotation. Due to many, in part, overlapping signals, or to low solubility of compounds in deuterated solvents, JSnC coupling constants cannot be given in some cases. Synthesis of Stannene 1. Stannene 1 was prepared as previously described11 by dropwise addition of 1 equiv of tert-butyllithium (1.7 M in pentane) to a solution of fluorostannane Tip2Sn(F)CHR2 (1.65 g, 2.00 mmol) in Et2O (20 mL) cooled to -78 °C. Warming to room temperature afforded a purple solution; a 119Sn NMR analysis showed the nearly quantitative formation of stannene 1. Thus, all reactions were performed on the crude reaction mixture of 1 containing LiF. Synthesis of 2. To a crude solution of 1 (2 mmol) in Et2O (20 mL) cooled to -78 °C was added 1 mmol of 1,4-benzoquinone dissolved in 5 mL of Et2O. The reaction mixture was allowed to warm to room temperature, and its color slowly turned from purple to yellow. After overnight stirring and filtration of LiF, the solvent was removed in vacuo and replaced by 10 mL of pentane. Crystallization at -20 °C afforded pure 2 as a crystalline yellow compound (1.47 g, 86%, mp 321 °C). 1H NMR: -0.34 and 0.60 (2d, 3JHH ) 6.0 Hz, 2 × 6H, o-CHMeMe′), -0.09, 0.51, 1.09, and 1.24 (4d, 3JHH ) 6.6 Hz, 4 × 6H, o-CHMeMe′), 0.27 and 0.61 (2d, 3 JHH ) 6.3 Hz, 2 × 6H, o-CHMeMe′), 0.42 and 1.48 (2s, 2 × 18H, tBu), 0.87, 0.89 and 3.57 (3sept, 3 × 2H, 3JHH ) 6.6 Hz, o-CHMeMe′), 1.02 and 1.04 (2d, 3JHH ) 6.6 Hz, 2 × 6H, p-CHMeMe′), 1.06 (d, 3JHH ) 6.6 Hz, 12H, p-CHMeMe′), 2.55-2.72 (m, 6H, o- and p-CHMeMe′), 2.95 (s, 2H, CH-CR2), 5.28 (s, 2H, CHdC-O), 6.05 and 8.78 (2d, 4JHH ) 1.5 Hz, 4JSnH ) 13.2 Hz, 2 × 2H, H1 and H8), 6.33, 6.69, 6.77, and 6.88 (4d, 4JHH ) 1.5 Hz, 4 JSnH ) 22.2 Hz, 4 × 2H, m-CH of Tip), 6.84 and 7.46 (2dd, 3JHH ) 8.1 Hz, 4JHH ) 1.5 Hz, 2 × 2H, H3 and H6), 7.47 and 7.72 (2d, 3 JHH ) 8.1 Hz, 2 × 2H, H4 and H5). 13C NMR: δ 22.89, 22.92, 22.99, 23.43, 24.51, 24.81, 25.55, and 29.37 (o-CHMeMe′), 23.70, 23.81, 23.86, and 23.93 (p-CHMeMe’), 31.48 and 31.84 (CMe3), 32.38 (3JSnC ) 21.0 Hz), 38.05 (3JSnC ) 26.2 Hz), 40.29 (3JSnC ) 31.7 Hz) and 40.42 (3JSnC ) 47.8 Hz) (o-CHMeMe), 34.04 (pCHMeMe), 34.11 and 35.34 (CMe3), 51.59 (2JSnC ) 67.8 Hz, 3JSnC ) 17.5 Hz, CH-CR2), 68.72 (CR2), 98.74 (3JSnC ) 27.0 Hz, (21) Sheldrick, G. M. SHELXS-97. Acta Crystallogr. 1990, A46, 467. (22) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refinement; University of Go¨ttingen, 1997.
2298 Organometallics, Vol. 28, No. 7, 2009
Ghereg et al. Table 1. Crystal Data for 2, 3, and 5
empirical formula fw temperature (K) cryst syst space group a (Å) b (Å) c (Å) β (deg) volume (Å3) Z absorp coeff (mm-1) reflns collected indep reflns absorp corr data/restraints/params goodness-of-fit on F2 final R indices (I > 2σ(I)) R indices (all data) largest diff peak, hole (e Å-3)
2 · 2C5H12
3 · 1.5Et2O
5
C118H168Sn2O2 1855.90 193(2) monoclinic C2/c 39.301(19) 12.990(7) 23.583(12) 118.413(8) 10 590(9) 4 0.519 27 669 6394 [R(int) ) 0.3610] multiscans 6394/183/639 0.936 R1 ) 0.0712, wR2 ) 0.1104 R1 ) 0.2107, wR2 ) 0.1553 0.759, -0.654
C118H161Sn2O3.5 1872.85 193(2) monoclinic P21/n 21.4073(3) 14.5881(2) 34.8664(6) 102.277(1) 10 639.5(3) 4 0.518 129 813 21 591 [R(int) ) 0.0733] multiscans 21 591/253/1268 1.015 R1 ) 0.0386, wR2 ) 0.0805 R1 ) 0.0635, wR2 ) 0.0916 0.559, -0.710
C65H78SnO2 1010.02 193(2) monoclinic P21/c 22.8146(5) 10.7060(2) 23.4538(5) 101.133(1) 5620.9(2) 4 0.496 50 877 11 414 [R(int) ) 0.0387] multiscans 11 414/0/631 1.007 R1 ) 0.0288, wR2 ) 0.0616 R1) 0.0461, wR2 ) 0.0682 0.431, -0.283
Chart 1
CHdC-O), 117.91 and 118.61 (4JSnC ) 11.2 Hz, C4 and C5), 120.42 (3JSnC ) 27.5 Hz) and 124.14 (3JSnC ) 20.2 Hz) (C1 and C8), 121.87, 122.04, 122.39, 123.44 (m-CH of Tip), 123.53 and 123.90 (5JSnC ) 16.1 Hz, C3 and C6), 135.37 (3JSnC ) 21.3 Hz) and 137.37 (3JSnC ) 22.8 Hz) (C12 and C13), 141.44 and 144.45 (ipso-C of Tip), 145.40 (2JSnC ) 21.7 Hz) and 147.68 (2JSnC ) 35.2 Hz) (C10 and C11), 146.89 (4JSnC ) 14.7 Hz) and 149.22 (4JSnC ) 21.3 Hz) (C2 and C7), 149.57 (4JSnC ) 11.2 Hz) and 149.98 (4JSnC ) 12.2 Hz) (p-C of Tip), 152.37, 152.80, 154.68 (2JSnC ) 37.6 Hz) and 155.71 (2JSnC ) 39.8 Hz) (o-C of Tip), 153.30 (C-O). 119Sn NMR: δ -17.90. MS m/z (% relative intensity): 1711 (M + 1, 15), 1508 (M - Tip + 1, 6), 1187 (M - Tip2Sn + 1, 5), 801 (Tip2SndCR2 - 1, 3), 541 (Tip2SnO - 1, 7), 525 (Tip2Sn - 1, 50), 323 (TipSn, 100). Anal. Calcd for C108H144Sn2O2 (1711.758) C, 75.78; H, 8.48. Found: C, 75.61; H, 8.83. Synthesis of 3 and 4. To a solution of stannene 1 (2 mmol) in Et2O (20 mL) cooled to -78 °C was slowly added 1 mmol of 1,4naphthoquinone or 9,10-anthraquinone, respectively, dissolved in 10 mL of diethyl ether. The reaction mixture progressively turned brown after 2 h of stirring at room temperature. After filtration of lithium salts and crystallization from pentane, white crystals of 3 or 4 were obtained. 3 (1.31 g, 74%, mp 332 °C): 1H NMR: δ 0.43, 0.52, 0.54 and 1.50 (4d, 3JHH ) 6.6 Hz, 4 × 6H, o-CHMeMe′), 0.72 (br sept, 2H, 3 JHH ) 7.0 Hz, o-CHMeMe′), 0.82 and 1.31 (2s, 2 × 18H, tBu), 1.10, 1.11, 1.15, and 1.17 (4d, 3JHH ) 6.6 Hz, 4 × 6H, p-CHMeMe′), 2.73 and 2.75 (2sept, 3JHH ) 7.2 Hz, 2 × 2H, p-CHMeMe′), 3.27 (sept, 2H, 3JHH ) 7.0 Hz, o-CHMeMe′), 4.81 (s, 2H, dCH-CHCR2),
4.95 (s, 2H, CHCR2), 6.48 (s, 2H, H1 or H8 of CR2), 6.70 (s, 2H, m-CH of Tip), 6.90 (s, 4H, H1 or H8 of CR2 and 2 m-CH of Tip), 6.95 (s, 2H, CHdC-O), 7.15 and 7.34 (2d, 3JHH ) 8.1 Hz, 2 × 2H, H3 and H6 of CR2), 7.66 and 7.71 (2d, 3JHH ) 8.1 Hz, 2 × 2H, H4 and H5 of CR2). 13C NMR: δ 22.81, 23.13, 25.98, and 28.82 (o-CHMeMe′), 23.74, 23.87, 23.91, and 23.98 (p-CHMeMe′), 31.17 and 32.32 (CMe3), 34.09 (p-CHMeMe′), 34.46 and 35.03 (CMe3), 37.35 (3JSnC ) 27.0 Hz) and 40.39 (3JSnC ) 32.3 Hz) (oCHMeMe′), 39.38 (2JSnC ) 27.7 Hz, CH-CR2), 62.77 (1J119SnC ) 383.1 Hz, 1J117SnC ) 366.0 Hz, CR2), 118.35 and 118.88 (C4 and C5 of CR2), 119.51 (3JSnC ) 12.8 Hz, CHdC-O), 121.87 (m-CH of Tip), 122.02, 122.63, and 123.17 (m-CH of Tip, C1 and C8), 123.34 and 123.68 (C3 and C6), 123.84 (CH-CHCR2), 125.25 (3JSnC ) 23.4 Hz, C-C-O), 136.54 (3JSnC ) 22.6 Hz) and 137.51 (3JSnC ) 25.6 Hz) (C12 and C13 of CR2), 140.85 and 145.28 (ipso-C of Tip), 145.57 and 146.69 (2JSnC ) 19.6 Hz, C10 and C11 of CR2), 148.12 (4JSnC ) 13.6 Hz) and 149.05 (4JSnC ) 12.8 Hz) (C2 and C7 of CR2), 149.68 (4JSnC ) 11.3 Hz) and 150.07 (4JSnC ) 12.1 Hz) (p-C of Tip), 152.41 (2JSnC ) 72.4 Hz) and 155.03 (2JSnC ) 37.7 Hz) (o-C of Tip), 153.02 (2JSnC ) 29.4 Hz, C-O). 119Sn NMR: δ -31.00. MS m/z (% relative intensity): 1761 (M + 1, 100), 1558 (M - Tip + 1, 35), 1236 (M - Tip2Sn, 40), 801 (Tip2SndCR2 1, 12), 525 (Tip2Sn - 1, 65), 323 (TipSn, 80). Anal. Calcd for C112H146Sn2O2 (1761.770): C, 76.36; H, 8.35. Found: C, 76.84; H, 8.16. 4 (1.40 g, 77%, mp 348 °C): 1H NMR: δ 0.28 and 1.64 (2d, JHH ) 6.3 Hz, 2 × 6H, o-CHMeMe′), 0.46 and 0.48 (2d, 3JHH ) 6.6 Hz, 2 × 6H, o-CHMeMe′), 0.60 and 3.46 (2sept,3JHH ) 6.6 Hz, 2 × 2H, o-CHMeMe′), 0.83 and 0.94 (2s, 2 × 18H, tBu), 1.09, 1.10, 1.15, and 1.17 (4d, 3JHH ) 6.6 Hz, 4 × 6H, p-CHMeMe′), 2.71 and 2.76 (2sept, 2 × 2H, 3JHH ) 6.9 Hz, p-CHMeMe′), 4.95 (s, 2H, dCH-CHCR2), 5.17 (s, CHCR2 3JSnH ) 75.9 Hz), 6.03 and 6.85 (2d, 4JHH ) 1.5 Hz, 4JSnH ) 9.9 Hz, 2 × 2H, H1 and H8), 6.65 and 6.90 (2d, 4JHH ) 1.5 Hz, 4JSnH ) 27.4 Hz, 2 × 4H, m-CH of Tip), 7.16 and 7.24 (2dd, 3JHH ) 8.4 Hz, 4JHH ) 1.5 Hz, 2 × 2H, H3 and H6), 7.32-7.34 and 8.50-8.54 (2m, 2 × 2H, arom H), 7.65 and 7.67 (2d, 3JHH ) 8.1 Hz, 2 × 2H, H4 and H5). 13C NMR: δ 22.84, 24.12, 25.96, and 28.39 (o-CHMeMe′), 23.72, 23.83, 23.90, and 24.02 (p-CHMeMe′), 31.16 and 31.89 (CMe3), 34.04 and 34.13 (p-CHMe2), 34.45 and 34.61 (CMe3), 37.46 and 40.37 (o-CHMeMe′), 38.96 (CH-CR2), 61.88 (CR2), 118.20 and 118.96 (C4 and C5), 122.03 and 122.72 (m-CH of Tip), 122.37 (C1 or C8), 123.27 and 123.45 (C3 and C6), 123.36 and 123.84 (arom CH, C1 or C8), 123.93 (CH-CHCR2), 128.50 and 140.56 (CC-O), 136.86 and 137.55 (C12 and C13), 145.31 (ipso-C of Tip), 145.47 3
Tin-Containing Heterocycles and 146.44 (C10 and C11), 148.00 and 148.98 (C2 and C7), 148.41 (C-O), 149.91 and 150.19 (p-C of Tip), 152.37 and 154.89 (o-C of Tip). 119Sn NMR: δ -24.48. MS m/z (% relative intensity): 1811 (M + 1, 100), 1608 (M - Tip + 1, 30), 801 (Tip2SndCR2 - 1, 20), 525 (Tip2Sn - 1, 50), 323 (TipSn, 50). Anal. Calcd for C116H148Sn2O2 (1811.820): C, 76.90; H, 8.23. Found: C, 76.51; H, 8.32. Synthesis of 5. A solution of 9,10-phenanthrenequinone (0.42 g, 2 mmol) in toluene (30 mL) was added by syringe to the crude solution of 1 (2 mmol) cooled to -78 °C. The initially purple reaction mixture turned green on warming to room temperature. After removal of LiF by filtration, diethyl ether was evaporated under vacuum and replaced by pentane (25 mL). The fractional crystallization at -20 °C afforded white crystals of 5 (1.38 g, 68%, mp 262 °C). 1H NMR: δ 0.54-1.67 (m, 56H, CMe3, o- and p-CHMeMe′ and 2 o-CHMeMe′), 2.83, 3.52, and 4.01 (br signals, 4H, 2 o- and 2 p-CHMeMe′), 6.79 (br s, 3H, m-CH of Tip), 7.05 (br s, 1H, m-CH of Tip), 7.19-7.35 (m, 6H), 7.54-7.70 (m, 5H) and 8.67-8.73 (m, 2H) (arom H of CR2 except H4 or H5, arom H of phenanthrenic moiety), 8.57 (d, 3JHH ) 8.1 Hz, 1H, H4 or H5).
Organometallics, Vol. 28, No. 7, 2009 2299 13
C NMR: δ 23.96, 30.93, 34.32 (CMe3, o- or p-CHMeMe′), 92.52 (CR2), 119.19, 121.74, 122.02, 122.07, 122.47, 122.96, 123.49, 125.34, 125.72, 126.08 (arom CH), 129.00, 130.26, 131.32, 134.30, 143.21, 143.39, 145.53, 149.63, 150.92 (arom C). 119Sn NMR: δ -67.57. MS m/z (% relative intensity): 1010 (M, 100), 995 (M CH3, 12), 803 (Tip2SndCR2 + 1, 42), 735 (M - CR2 + 1, 30), 525 (Tip2Sn - 1, 10). Anal. Calcd for C65H78SnO2 (1010.020): C, 77.30; H, 7.78. Found: C, 77.83; H, 7.36.
Acknowledgment. We are grateful to the CNRS (contract CNRS/JSPS no. PRC 450), the Agence Nationale pour la Recherche (contract ANR-08-BLAN-0105-01), and the MENESR for financial support of this work. Supporting Information Available: CIF files for 2, 3, and 5. This material is available free of charge via the Internet at http://pubs.acs.org. OM801198Y
