3920
Organometallics 1995, 14, 3920-3926
Thallium-Stabilized Silsesquioxides: Versatile Reagents for the Synthesis of Metallasilsesquioxanes, Including High-Valent Molybdenum-Containing Silsesquioxanes Frank J. Feher,” Kamyar Rahimian, Theodore A. Budzichowski, and Joseph W. Ziller Department of Chemistry, University of California, Irvine, California 9271 7 Received June 8, 1995@ The reactions of the incompletely-condensed silsesquioxanes (c-CSH~&%O~(OH)~ (la),
(C-C~H~~)~S~~O~(OTMS)(OH)Z (2a), ( c - C ~ H ~ ) ~ S ~ ~ ~ ~ ( O T M(2b), S)(O and H ) (~-CsH11)7Si709Z (OTMS)z(OH) (3a) wit6 thallium(1) ethoxide (1/1 TVOH) result in the formation of the (7a), n [(c-C6Hd7Si709corresponding T1-substituted silsesquioxanes [(c-C6H11)7Si709(OT1)3I (OTMS)(OTl)zI, @a>,[(C-C~H~)~S~~O~(OTMS)(O~)ZI, (8b),and [(C-C~H~~)~S~~O~(OTMS)Z(~T~)I, (9a). These thallium-stabilized silsesquioxides are not prone to cycloelimination reactions or the formation of “ate” complexes, They are versatile anionic equivalents of incompletelycondensed silsesquioxanes which react with a variety of halide complexes, including Poc13 and MoOzClz, to afford high yields of metallasilsesquioxanes. Over the past several years incompletely-condensed silsesquioxanesl have attracted interest as models for ~ i l i c a , ~as , ~ ligands * for main-group4 and transitionmetal element^,^^,^-^ and as comonomers for silsesquioxane-siloxane polymer^.^^^ The key t o success in all of these areas has been the development of a highly @Abstractpublished in Advance ACS Abstracts, July 15, 1995. (1)For reviews concerning incompletely-condensed silsesquioxanes: (a) Voronkov, M. G.; Lavrent’yev, V. I. Top. Curr. Chem. 1982, 102,199-236. (b) Burgy, H.; Calzaferri, G.; Herren, D.; Zhdanov, A. Chimia 1991,45, 3-8. (c) Edelmann, F.T. Angew. Chem., Int. Ed. Engl. 1992,32,586. (2)(a) Feher, F. J.; Newman, D.A,; Walzer, J . F. J . Am. Chem. SOC. 1989,111,1741-8.(b) Feher, F. J.; Newman, D. A . J . Am. Chem. SOC. 1990,112,1931-6. (c) Feher, F. J.; Budzichowski, T. A.; Blanski, R. L.; Weller, K. J.; Ziller, J. W. Organometallics 1991,10,2526-8. (d) Feher, F. J.; Budzichowski, T. A.; Rahimian, K.; Ziller, J. W. J . A m . Chem. SOC.1992,114,3859-66. (3)(a) Hambley, T. W.; Maschmeyer, T.; Masters, A. F. Appl. Organomet. Chem. 1992,6,253-60. (b) Field, L. D.; Lindall, C. M.; Maschmeyer, T.; Masters, A. F. Aust. J. Chem. 1994,47,1127-32. (4)(a)Feher, F. J.; Budzichowski, T. A,; Weller, K. J . J. Am. Chem. SOC.1989,111,7288-9. (b) Feher, F. J.; Weller, K. J . Organometallics 1990,9,2638-40. (c) Feher, F. J.; Weller, K. J. Inorg. Chem. 1991, 30,880-2. (d) Feher, F. J.; Weller, K. J.; Ziller, J. W. J . Am. Chem. (e) Feher, F. J.; Budzichowski, T. A,; Ziller, J. SOC.1992,114,9686-8. W. Inorg. Chem. 1992,31,5100-5. (5)(a) Feher, F. J.; Blanski, R. L. J. Am. Chem. SOC.1992,114, 5886-7. (b) Feher, F. J.; Blanski, R. L. J . Chem. SOC.,Chem. Commun. 1990,1614-6. (c) Feher, F. J.; Walzer, J . F.; Blanski, R. L. J . A m . Chem. SOC.1991,113,3618-9. (d) Liu, J.-C.; Wilson, S. R.; Shapley, J. R.; Feher, F. J. Inorg. Chem. 1990,29, 5138-9. (e) Feher, F. J.; Walzer, J. F. Inorg. Chem. 1991,30,1689-94. (flFeher, F. J. J . A m . ( g )Budzichowski, T.A.; Chacon, S. T.; Chem. SOC.1986,108,3850-2. Chisholm, M. H.; Feher, F. J.; Streib W. J.Am. Chem. SOC.1991,113, 689-91. (h) Feher, F. J.; Walzer, J. F. Inorg. Chem. 1990,29,160411. (i) Feher, F. J.; Gonzales, S. L.; Ziller, J. W. Inorg. Chem. 1988, 27,3440-2. (6)A preliminary report of the synthesis and use of a thalliumcontaining silsesquioxane derived from 2b has been recently reported: Feher, F. J.;Tajima, T. L. J . Am. Chem. SOC.1994,116,21456. (7)(a) Winkhofer, N.; Roesky, H. W.; Noltmeyer, M.; Robinson, W. T. Angew. Chem., Int. Ed. Engl. 1992,31, 599-601. (b) Herrmann, W. A.; Anwander, R.; Dufaud, V.; Schere, W. Angew. Chem., Int. Ed. Engl. 1994,33,1285-6. (c) Winkhofer, N.; Voigt, A.; Dom, H.; Roesky, H. W.; Steiner, A.; Stalke, D.; Reller, A. Angew. Chem., Int. Ed. Engl. 1994,33, 1352-3. (d) Gosink, H.-J.; Roesky, H. W.; Schmidt, H.-G.; Noltemeyer, M.; Irmer, E.; Herbst-Inner,R. Organometallics 1994,13, 3420-6. (8)Lichtenhan, J. D.; Vu, N. Q.;Carter, J . A.; Gilman, J . W.; Feher, F. J. Macromolecules 1993,26,2141.
efficient methodology for constructing and modifying structurally well-defined SUO frameworks. The recent discovery that Me4Sb-stabilized silsesquioxides (e.g., 4-6) can be used as anionic equivalents of incompletely-condensed silsesquioxanes (e.g., la-3a) provided an important tool for preparing metal-contain~ , ~ ~ , ~ ~ ~ the utility ing SUO f r a m e ~ o r k s . ~Unfortunately, of these latent anions is somewhat limited because of their tendency to cycloeliminate andor form anionic “ate” complexes when reacted with high-valent, electrophilic metal halide complexes (e.g., TiX4, MoOzClz, POC13)2d(Chart 1). In this paper we report the synthesis, characterization, and reactivity of thallium-stabilized silsesquioxides, which can be easily obtained from the reactions of incompletely-condensed silsesquioxanes (e.g., 1-3) with thallium ethoxide (TlOEt). These thallium-stabilized silsesquioxides are versatile anionic equivalents of incompletely-condensed silsesquioxanes. They react with a variety of halide complexes to afford high yields of metallasilsesquioxanes, and they are not as prone as MerSb-stabilized silsesquioxides to cycloeliminate or form “ate” complexes.6
Results and Discussion Synthesis and Characterization of ThalliumStabilized Silsesquioxides. The reactions of 1-3 with stoichiometric amounts of TlOEt (TVSiOH = 1:1, 25 “C, C6Hs) afford excellent yields of thallium-containing silsesquioxanes. In each case, spectroscopic and analytical data indicate that all protons available from siloxy groups are completely replaced by thallium (Scheme 1). (9)(a) Lichtenhan, J. D. Comments Inorg. Chem. 1995,17, 11530.(b) Lichtenhan, J. D.; Mantz, R. A,; Jones, P. F.; Carr, M. J. Polym. Prepr. 1994,35,523-4. (c) Haddad, T. S.; Lichtenhan, J. D. Polym. (d) Lichtenhan, J . D.; Otonari, Y. A.; Carr, M. Prepr. 1994,35,708-9. J. Macromolecules, submitted for publication. (e) Lichtenhan, J. D. Silsesquioxane-Based Polymers. In The Polymeric Materials Encyclopedia: Synthesis, Properties and Applications; CRC Press, Inc.: Boca Raton, FL; in press. (0 Haddad, T. S.; Lichtenhan, J. D. J . Inorg. Organomet. Polym., in press.
Q276-7333I95/2314-392Q$Q9.QQlQ0 1995 American Chemical Society
Organometallics, Vol. 14, No. 8, 1995 3921
Thallium-Stabilized Silsesquioxides
Chart 1 R
3a b
2a b
Scheme 1 3 TI(0Et)
- 3EtOH
structure with T1 in a relatively rare, two-coordinate, siloxy-bridged structure (i.e., 10). A dimeric structure R
R
.!
\,,-oTMs 2 TI(0Et)
- 2EtOH
*
TI(0Et) R 7 Si 7 0 9 ( O T M S ) 2 ( OH)
- EtOH
3a R=c-C&I11 b c-Cfi
Considering that Tl(1) has been observed to support coordination numbers ranging from 2 to l2,l0J1 the NMR spectra (25 "C, CsDs) for 7-9 are surprisingly simple. In each case, the spectra of the thalliumsubstituted product and the parent silsesquioxane exhibit the same multiplicity of 29Siand methine (SiCH) 13Cresonances. For 7a, for example, both the 29SiNMR spectrum and the (SiCH) region of the 13C NMR spectrum exhibit three resonances with relative integrated intensities of 3:3:1. These results are consistent with structures analogous to 4-6, and it is convenient t o view 7-9 as T1-substituted derivatives of 1-3, but the structure of each molecule is undoubtedly more complex. In the case of 9a,a preliminary X-ray crystal structure12 indicates that the molecule adopts a dimeric (10) Lee, A. G. Chemisty ofThallium; Elsevier: Amsterdam, 1971, and references cited therein. (11) Examples of coordination environments in T U ) alkoxides or siloxides: (a) Roesky, H. W.; Scholz, M.; Noltemeyer, M.; Edelmann, F. T. Inorg. Chem. 1989,28, 3829-30. (b) Harvey, S.; Lappert, M. F.; Raston, C. L.; Skelton, B. W.; Srivastava, G.; White, A. H. J. Chem. SOC., Chem. Commun. 1988, 1216-7. (c) Brown, I. D.; Faggianai, R. Acta Crystallogr. 1980, B36, 1802-6 and references cited therein.
\
R
TMSO'
\R
is also formed by 8b,but a preliminary X-ray structure13 reveals a more complex siloxy-bridged structure with two- and three-coordinate Tl(1) ions. Unfortunately, it has not been possible to collect enough high-quality data (12) (a) Complex 10 crystallizes from toluenehexanes (-34 "C) a s poorly diffracting, colorless plates in the monoclinic space group C2/c with a = 41.487(8)A, b = 14.613(3)A, c = 24.541(5)A, and p = 109.79(3)". The asymmetric unit consists of one-half of the dimer shown, which is related to the other half by a 2-fold axis of rotation defined by the TI-T1 vector. The structure was solved by direct methods (SHELXTL PLUS), and all non-hydrogen atoms were located by a series of difference-Fourier syntheses. The trimethylsilyl groups appear to be disordered. The current RF is 9.5%(anisotropic parameters for Si, 0, T1; isotropic parameters for C). (b) Budzichowski, T. A,, Ph.D. Thesis, University of California, Imine, CA 1991. (13) Complex 8b crystallizes from benzendacetonitrile as very poorly diffracting crystals in the monoclinic space group P21/n with a = 17.982(4)A, b = 16.338(3) A, c = 19.387(4) A, and /3 = 113.80(3)".The solid-state structure, which contains two silsesquioxane fragments bridged by four T1 atoms, is very complex. The Si/O/Tl framework could be clearly identified, but severe X-ray damage to the crystal, disorder problems with cyclopentyl groups, and failures of the low-temperature unit prevented the collection of enough high-quality data to complete the structure: Feher, F. J.; Rahimian, K.; Ziller, J. W. Unpublished results.
Feher et al.
3922 Organometallics, Vol. 14, No. 8)1995
Scheme 2
15 R=C-C6H11 for satisfactory structural solutions. For reasons that are not yet apparent, these T1-subsituted silsesquioxanes produce either very poorly diffracting crystals (even at -100 "C) or no crystals at all.14 Thallium-StabilizedSilsesquioxides as Anionic Equivalents of Incompletely-CondensedSilsesquioxanes. Metathetical reactions between thalliumstabilized silsesquioxides and halide-containing reagents are very attractive because thallium halides have high lattice energies and are insoluble in almost all common laboratory s01vents.l~ This minimizes any tendency for "ate" complex formation with Lewis acidic metal halides and allows TIX coproducts to be easily separated. Thallium complex 7a reacts quickly with a variety of halide-containing reagents (e.g., CpTiCls, MeSnCl3, SbC13) to afford high yields of metallasilsesquioxanes (i.e., 12-14). In each case, the yield is quantitative by
I
16a R 1 = H
b
SiMe3
-
Scheme 3
R7Si709(OTMS)(OT1)2
Mo02C12 DME
17a M = M o
18
(14)TI-containing silsesquioxanes precipitate from many solvents as amorphous white powders. In those instances where well-formed crystals were obtained, diffraction intensities were very poor (even at -110 "C) and X-ray damage to the crystals was severe. (15)Wade, K.; Banister, A. J. In Comprehensioe Inorganic Chemistry; Bailar, J. C., Emelus, H. J., Nyholm, R., Trotman-Dickenson, A. F., Eds.; Pergamon: Oxford, 1973; Val. 1, pp 1127-37.
Cr
NMR spectroscopy and a crude product of very high purity can be obtained simply by removing the volatiles in vacuo, extracting the residue with benzene or hexane, and evaporating the solvent. In contrast to MerSb-stabilized silsesquioxides 4 and 5, which are prone to intramolecular condensation to 16 when reacted with reagents capable of producing good leaving groups on silicon,2dT1-stabilized silsesquioxides react cleanly to afford high yields of metallasilsesquioxanes. For example, 7a reacts with POc13 to afford a quantitative NMR yield of 15 (Scheme 21, while 4 produces a complex mixture of cyclocondensation products containing trivial amounts of 15. Evidently, intramolecular attack at silicon is not very favorable for T1-stabilized silsesquioxides. Synthesis and Characterization of Molybdenum-Containing Silsesquioxides. The observation that 7a reacts cleanly with POCl3 to afford 15 prompted us to investigate the reaction of 8a with Mo02C12, a reagent known to affect the cyclocondensation of 2a and 5.2dThe reaction Mo02C12 with 8a in the presence of DME occurs rapidly upon mixing to precipitate TlCl and affords a quantitative NMR yield of a new Mo-containing silsesquioxane, which was assigned as 17a on the basis of its 95MoNMR spectrum (6 -70.6, w112 = 220 Hz) and the similarity between its 13C NMR spectrum and the spectrum observed for 18 (Scheme 3). Molybdate 17a is extremely soluble in most organic solvents with which it does not react, and it is very sensitive to traces of water, which appear to catalyze
Organometallics, Vol. 14, No. 8, 1995 3923
Thallium-Stabilized Silsesquioxides Scheme 4
..
8a b
R=c-C6HII c-C&
R /si-o-si
19a 19b 20a 20b its cyclocondensation to the much less soluble 16b. It can be obtained as a spectroscopically (‘H and I3C NMR) and analytically pure, amorphous white powder by extracting the crude reaction mixture with DME and evaporating the volatiles or by allowing DME to diffuse slowly into a pentane solution of 17a a t -35 “C. The analogous reaction of 8b with Mo02C12 appears to follow a different course, and the 13CNMR spectrum of the crude product is very complex. I t is somewhat surprising that such a minor structural change could have such a dramatic effect, but similar results are occasionally observed when l b is substituted for la.16 In most instances, any apparent reactivity difference between cyclohexyl- and cyclopentyl-substituted silsesquioxanes can be traced to a large difference in product solubility, particularly if one derivative is so poorly soluble that its precipitation is the driving force for the r e a ~ t i 0 n . lHowever, ~~ the fact that no metallasilsesquioxanes precipitate from reactions of Mo02C12 with 8a and 8b rules out this explanation and suggests that some other yet-to-be-determined factor is responsible for this difference in reactivity. Molybdate 17a reacts with strong Lewis bases to afford stable five-coordinate adducts. For example, the reactions of 17a with pyridine and Ph3PO occur immediately upon mixing to afford quantitative NMR yields of 19a and 20a, respectively. Lewis adducts 19a and 20a, as well a s stoichiometrically similar adducts which are formally derived from 17b, can be prepared in “one pot” by reacting 8a and 8b with Mo02C12 in the presence of pyridine or Ph3PO (Scheme 4). In all cases, the Lewis adducts adopt distorted trigonal bipyramidal structures with both oxo ligands located in the equatorial plane. The pentane solvate of 19b crystallizes as-well-formed colorless crystals in the space group P(1) with two molecules of 19b and one molecule of pentane in the asymmetric unit. There are subtle structural differences due t o differing cyclopentyl group conformations, but metrical data for both molecules are quite similar, (16) A good example is the reaction of R7Si709(OH)3 with M e a , (i-PrO)dl or AlClg’EtSN (see ref 4a). In the case of la, these reactions O I ~ AisI I ~ , provide virtually quantitative yields of [ ( c - C ~ H ~ I ) ~ S ~ ~ which poorly soluble and precipitates from the reaction mixture. No metallasilsesquioxanes precipitate from analogous reactions of lb, and all attempts to prepare [(c-C5H9)7Si701&]2 have been unsuccessful: Feher, F. J.; Budzichowski, T.A,; Weller, K. J.; Rahimian, K. Unpublished work.
‘R
R = c-C6HI L = C5H5N c - C ~ H ~ CSHSN C-C6H11 Ph3PO Ph3PO c-CSH~ mC41
01
C Y C6
Figure 1. ORTEP drawing of 19b with thermal ellipsoids plotted at the 50% probablility level. For clarity, only one of the crystallographicallyindependent molecules is shown, only the ipso carbons atoms (SiCH) of the cyclopentyl groups are shown, and the pentane of solvation is omitted. Selected interatomic distances (A) and interbond angles (deg) are as follows: Mol-N1, 2.283(9);Mol-01, 1.694(7);M01-02,1.694(5); M01-03,1.905(6); M01-06,1.903(7);Sil-03, 1.621(7);Si5-06, 1.627(7);other Si-0, 1.6021.630; N1-Mol-01, 85.0(3);N1-Mol-02, 83.6(3); N1Mol-03, 78.4(3); N1-Mol-06, 17i.1(3); 01-Mol-02, 111.2(3);01-Mol-03, 120.2(3);01-Mol-06, 101.5(3); 02-Mol-03, 123.1(3);02-Mol-06, 99.4(3); 03-Mol06, 93.0(3);Mol-03-Sil, 150.2(4);Mol-06-Si5, 139.2(4); Si-0-Si , 141.3-159.1. especially within the coordination sphere of Mo. The structure of 19b is illustrated in Figure 1. Dioxomolybdenum(VI) complexes generally adopt sixcoordinate structures with mutually cis oxo ligands.17 The first crystallographically characterized example of a five-coordinate dioxomolybdenum(VI) complex (21) was reported in 1984,18 and the first five-coordinate dioxomolybdenum(VI) bis(alkoxide)(22) appeared shortly aftenvard.lg The only other structurally characterized, (17) Nugent, W. A.; Mayer, J. M. Metal-Ligand Multiple Bonds; Wiley-Interscience: New York, 1988, and references cited therein. (18) Berg, J. M.; Holm, R. H. J . Am. Chem. SOC. 1984, 106, 3035-
6.
Feher et al.
3924 Organometallics, Vol. 14, No. 8, 1995
corresponding T1-substituted silsesquioxanes. These stable, hydrocarbon soluble compounds react with a variety of transition-metal and main-group halide complexes to afford high yields of metallasilsesquioxanes. Unlike MedSb-substituted silsesquioxanes, which are prone to cycloelimination and/or the formation of anionic "ate)' complexes when reacted with highly electrophilic metal halides,2dT1-substituted silsesquioxanes appear to be generally useful for the synthesis of metallasilsesquioxanes. T1-substituted silsesquioxanes are versatile anionic equivalents of incompletely-condensed silsesquioxanes.
22
21
Experimental Section
23
24
monomeric, five-coordinate dioxomolybdenum(VI) complex appears t o be (2,4,6-Me3CsHz)zMoOz(CHzPPh3) (23),20 although an interesting bimetallic cluster with two five-coordinate dioxomolybdenum(VI)centers (i.e., 24)is also known.21 In each of these cases the molecule adopts a distorted trigonal bipyramidal structure with oxo ligands situated in the equatorial plane. For 21 and 22,coordination of a tridentate ligand forces the N-donor ligand to occupy a site within the equatorial plane; but in the case of 19b, the pyridine ligand must occupy an axial site because chelation of the silsesquioxane framework requires mutually cis coordination sites. Axial coordination of pyridine is also observed in 24. At low temperature (C7D8, -60 "0, the 13C NMR spectra of 19 and 20 are consistent with C1-symmetric structures. In the case of 19b,for example, there are seven methine (SiCH) resonances with equal intensity (6 24.55,23.50,23.36,23.09,22.94,22.67,22.34). When the solution is warmed t o 25 "C, two pairs of methine resonances coalesce t o produce a pattern of five resonances with relative integrated intensities of 1:2:2: 1:1 (6 24.95, 23.85,23.68, 23.00,22.85). Any rapid process capable of transiently generating a C,-symmetric silsesquioxane framework can produce the observed coalescence phenomena. Pseudorotation and reversible dissociation of pyridine are particularly attractive mechanisms because they quickly produce C,-symmetric intermediates. However, small amounts of added pyridine or Ph3PO (or any other Lewis base) greatly accelerate the dynamic process, and only one timeaveraged set of resonances is observed for both the free and coordinated ligands. These observations strongly implicate the availability of an associative mechanism with six-coordinate, bis-ligand adducts.
Conclusion The reactions of incompletely-condensedsilsesquioxanes with thallium(1) ethoxide afford high yields of the (19) Hawkins, J. M.; Dewan, J. C.; Sharpless, K. B. Inorg. Chem. 1986,25,1501-3. (20) Lai, R.; Le Bot, S.; Baldy, A.; Pierrot, M.; Arzoumanian, H. J . Chem. SOC.,Chem. Commun. 1986,1208. (21)Gosink, H.-J.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G.; Freire-Erdbrugger, C.; Sheldrick, G. M. Chem. Ber. 1993, 126, 27983.
DANGER Thallium-containing compounds are poisonous. The authors strongly recommend that any work with thalliumcontaining compounds be performed only by experienced technicians educated in the use, disposal, and hazards of thalliumcontaining compounds. General experimental procedures for the synthesis of 1-3, as well as general protocol for the synthesis and characterization of silsesquioxanes and metallasilsesquioxanes, are described in refs 2a-d. CDC13, pyridine, and triethylamine were vacuum distilled (25 "C, 0.1 Torr) from CaH2. CsDs, toluenedg, THF-dg and dimethoxyethane (DME) were vacuum distilled (25 "C, 0.1 Torr) from sodium benzophenone ketyl. TlOEt (Aldrich) and Mo02C12 (AlphdJohnson-Matthey) were used without further purification. Synthesis of [(~-CsH11)7(Si7012)T41(7a):TUOEt) (771 mg, 3.09 mmol) was added to a suspension of la (1.00 g, 1.03 mmol) in toluene (-25 mL). All solids dissolved within 20 min. After the mixture had been stirred for 12 h, the solvent was removed in vacuo (25-45 "C, 0.1 Torr) to afford a white microcrystalline solid, which was washed with hexanes (3 x 15 mL) and dried in vacuo (45 "C, 0.1 Torr, 1 h) to afford 1.35 g (83%) of spectroscopically pure (lH, 13C, 29Si) 7a. Analytically pure material can be obtained by recrystallization from toluene/ hexanes (25 to -34 "C) or by allowing acetonitrile to diffuse into a benzene solution of 7a. Data for 7a: 'H NMR (500.1 MHz, CsH6, 25 "c): 6 2.3-1.15 (br m's, 70H), 1.08 (m, 4H), 0.96 (m, 3H). 13C{lH} NMR (125.03 MHz, CsHs, 25 "C): 6 28.66, 28.47, 28.17, 27.85, 27.71, 27.45, 27.42, 27.27 (CH2); d 27.03,25.25,23.90 (3:3:1 for CHI. 29Si{1H}NMR (99.35 MHz, CsHs, 25 "c): d -60.49, -66.31, -69.18 (3:1:3). MS (70 e v , 200 "C; relative intensity): m l e 1500 (M+ -C6H11; 401, 872 (M+ -3T1, -0, -C&11; 100). Anal. Calcd for C42H~012Si7T13 (found): C, 31.85 (32.04); H, 4.90 (4.73). Mp: 325-30 "C (decomp). Synthesis of [(c-CsH11)7(Si7011)(OTMS)T121 (Sa):Tl(0Et) (460 mg, 1.84 mmol) was added to a solution of 2a (965 mg, 0.923 mmol) in toluene (-25 mL). After the mixture had been stirred for 3.5 h, the volatiles were evaporated in vacuo (25 "C, 0.1 Torr, 3 h) to afford a white solid, which was washed with hexanes ( 3 x 8 mL) and dried (25 "C, 0.1 Torr, 3 h ) to afford 300 mg of Sa as a white microcrystalline solid; a second crop (880 mg)was obtained by cooling the filtrate to -34 "C for 2 days. The total yield of analytically pure material was 1.18 g (88%). Well-formed crystals may be obtained by recrystallization from toluenehexanes (25 to -34 "C). Data for 8a: 'H NMR (500.1 MHz, CsHs, 25 "C): d 2.3-0.8 (br m's, 77H), 0.358 (s, -Si(CH& 9H). I3C{lH} NMR (125.03 MHz, Cs&, 25 "c): 6 28.91, 28.77,28.70, 28.51,28.45, 28.26, 28.20, 28.12, 28.06, 27.94, 27.84, 27.80, 27.70, 27.65, 27.56, 27.48, 27.36 (CH2); 6 27.26, 26.09, 25.46, 24.61, 23.94 (2:1:2:1:1 for CHI; 6 2.74 (--Si(CH&). 29Si{lH} NMR (99.35 MHz, CsHs, 25 "C): d -60.70, -66.62, -66.69, -68.13, -68.90 (2:1:1:1:2 for RSiO312); 6 8.53 (-Si(CH&). MS (70 eV, 200 "C; relative intensity): m l e 943 (M+ -TlzO, -CsH11; 100). Anal. Calcd for C&&&i8T12 (found): C, 37.21 (37.65); H, 5.97 (5.98). Mp: 125-130 "C (decomp).
Thallium-Stabilized Silsesquioxides
Organometallics, Vol. 14, No. 8,1995 3925
(500.1 MHz, C&., 25 "C): 6 8.428 (d, JH-H = 5.1 Hz, o - C ~ H ~ N ) , Synthesis of [ ( c - C ~ H B ) ~ ( S ~ ~ O ~ ~ ) ( O T (8b): M STUOEt) )T~~I = 6.2 Hz, p-CabN), 6.390 (t, JH-H = 6.5 Hz, (2.26 g, 9.06 mmol) was added to a solution of 2b (4.00 g, 4.22 6.697 (t, JH-H m-C5H5N); 2.20-1.00 (br m's, 77H); 0.509 ( s , -Si(CH& SH). mmol) in benzene (-125 mL). After the mixture had been '3C{'H} NMR (125.03 MHz, CsHs, 25 "C): 6 149.08 ( o - C ~ H ~ N ) , stirred for 12 h, the volatiles were removed in vacuo (25 "C, 0.1 Torr, 3 h) to afford Sb as a white solid. Well-formed 138.54 (m-CgHgN), 124.73 @-CsHsN); 28.09, 28.05, 28.00, crystals can be obtained by allowing CH3CN to diffuse into a 27.91, 27.79, 27.63, 27.45, 27.40, 27.36, 27.29, 27.25, 27.19 (CH2); 25.58, 25.03, 24.87, 23.86, 23.83 (1:2:2:1:1, CHI; 2.10 benzene solution of 8b. Yield: 4.00 g (70%). Data for Sb: 'H NMR (500.1 MHz, C6H6, 25 "C): 6 2.1-1.1 (br m's, 63H), 0.282 (-Si(CH&). 95MoNMR (32.58 MHz, CsHs, 25 "C): 6 -4.03 (win = 790 Hz). (s, 9H). 13C{'H} NMR (125.03 MHz, C&e, 25 "C): 6 29.23, 28.97, 28.46, 28.40, 28.31, 28.02, 27.88, 27.80, 27.54, 27.51, ( { [ ( C - C ~ H ~ ) ~ ( S ~ ~ ~ ~ I ) ( O ~ S ) I M(19b): O ( =MoO)~(C~} 27.37 (CH2); 6 26.20, 25.35, 24.23, 23.83, 23.21 (2:1:2:1:1 for 02Cl2 (100 mg, 0.502 mmol) was added to a solution of Sb (680 CHI; 6 2.62 (-Si(CH&). 29Si{1H}NMR (99.35 MHz, C&, 25 mg, 0.502 mmol) and pyridine (0.041 mL, 0.502 mmol) in "C): 6 -59.06, -64.48, -64.99, -65.82, -66.52 (2:1:1:1:2 for benzene (-25 mL). The solution was stirred for 1.5 h, filtered Rsi03/2); 6 8.55 (-Si(CH3)3). Anal. Calcd for C3~H72012Si~T12 through Celite to remove TlCl, and evaporated to dryness (25 (found): C, 33.70 (33.46); H, 5.36 (5.32). Mp: 197-203 "C "C, 0.1 Torr) to afford 19b as a n amorphous white solid. (decomp). Analytically pure product (434 mg, 75%) was obtained by Synthesis of [(C-CSH~~)~(S~~O~O)(OTMS)~T~] (9a):Tl(0Et) cooling a pentane solution of 19b to -35 "C. Data for 19b: 'H NMR (500.1 MHz, C & 3 , 25 "C): 6 8.455 (d, JH-H = 4.4 Hz, (33.5 mg, 0.134 mmol) was added to a solution of 3a (150 mg, = 7.3 Hz, p-C$IsN); 6.467 (t, JH-H = 0.134 mmol) in toluenehexanes (l:l,-4 mL) and cooled to o-C$IsN); 6.762 (t,JH-H 6.6 Hz, m-Ca5N); 2.05-1.15 (br m's, Gag, 63H); 0.470 (s, Si-34 "C for 2 days. The crystalline solid which formed was collected by vacuum filtration, washed with hexanes (-2 mL), (CH3)3, 9H). 13C{'H} NMR (125.03 MHz, C & 3 , 25 "C): 6 149.10 ( o - C ~ H ~ N138.40 ), (m-CsHsN), 124.59 (p-CsH5N);28.30, and dried in vacuo (45 "C, 0.01 Torr) overnight. Yield: 155 mg, 85%. Data for 9a: IH NMR (500.1 MHz, CsH6,65 "C): 6 28.17, 28.13, 28.08, 27.94, 27.54, 27.51, 27.45, 27.39 (CH2); 24.94, 23.81, 23.64, 22.98, 22.82 (1:2:2:1:1, CHI; 2.097 (-Si2.2-0.8 (br m's, 77H), 0.455 (s, -Si(CH3)3, 18H). 13C{IH}NMR (125.03 MHz, Cs&, 65 "C): 6 28.83,28.68, 28.39,28.31,28.19, (CH313). 9 5 M NMR ~ (32.58 MHz, cs&, 25 "C): 6 -3.48 ( ~ 1 1 2 = 1500 Hz). Anal. Calcd for C43H77MoNO14Si8-0.5 pentane 28.13, 27.89, 27.80, 27.77, 27.73, 27.68, 27.43, 27.40, 27.36, 27.28 (CH2); 6 26.08, 25.88, 25.72, 23.95 (2:2:1:1 for CH); 6 (found): C, 45.97 (45.30); H, 7.04 (6.83). Mp: 180 C (decomp). 3.02 (-Si(CH&). MS (70 eV, 200 "C; relative intensity): m l e ~ [ ( C - C ~ H I ~ ) ~ ( S ~ ~ O ~ ~ ) ( O ~ S ) I(20a): M O Mo(=O~~~OPP 944 (M+ -TlOTMS, -CsH11; 80), 466, and 451 (T1 decomposiOzCl2 (86 mg, 0.432 mmol) was added to a solution of Sa (627 tion fragments, 100%). Anal. Calcd for C48H95012Si9T1 mg, 0.432 mmol) and (C6H5)3PO (120 mg, 0.432 mmol) in (found): C, 43.62 (43.79); H, 7.25 (7.11). Mp: 175-80 "C benzene (-25 mL). The solution was stirred for 1.5 h, filtered (decomp). through Celite to remove TlC1, and evaporated (25 "C, 0.1 Torr) Reactions of 7a with SbCls, MeSnCb, and (C5Hs)TiCls. to afford 20a as a n amorphous white solid. Analytically pure Syntheses of 12-14: The reactions of 7a with SbC13, product (439 mg, 70%) was obtained by cooling a pentane solution of 20a to -35 "C. Data for 20a: IH NMR (500.1 MHz, MeSnCl3, and (C5Hb)TiC13 were performed by adding the = 12 Hz, JH~-H,,, = 8.5 Hz, CsHs, 25 "C): 6 7.698 (ddm, JH-P trichloride (1equiv) to a solution of 7a (-65 mg) in benzene (0.40 mL) in a n NMR tube and stirring on a Vortex mixer for 6H), 7.040 (m, m- andp-C&, 9H), 2.20-1.00 (br m's, 1h a t 25 "C. Precipitation of TlCl was noted immediately upon C a l l , 77H), 0.432 (s, -Si(CH& 9H). 13C{lH}NMR (125.03 mixing. After the samples were centrifuged to settle TlCl MHz, CsHs, 25 "C): 6 132.61 (S,p-C&), 132.39 (d, J c - p = 9.7 formed in the reaction, 'H and lC{IH} NMR spectra of the Hz, O - C & , ) ,130.07 (Jc-p = 106.6 Hz, ipSO-C&), 128.79 (d, reaction mixtures were identical in all respects to samples of J c - p = 13.6 Hz, m-CsH5); 28.13, 28.09, 28.06, 28.03, 28.00, 27.88, 27.83, 27.71, 27.65, 27.51, 27.48, 27.42, 27.37, 27.34, 12- 14 prepared by the EtsN-catalyzed r'eactions of l a with 27.25, 27.22 (CH2); 25.55, 25.11, 24.75, 23.92, 23.89 (1:2:2:1: SbCl3, MeSnCls, and (C5H5)TiC13,respectively.2d 1, CHI; 2.11 (-Si(CH&). 31P{1H}NMR (202.2 MHz, CsHs): { [(c-C~~I).I(S~,O~~)(OTMS)IMO(=O)~} (17a):Mo02C12 (213 6 38.11. Anal. Calcd for C63H101Mo015PSi~(found): C, 52.18 mg, 1.033 mmol) was added to a solution of Sa (1.500 g, 1.033 (52.03);H, 7.02 (7.45). Mp: 152 "C (decomp). mmol) and 1,2-dimethoxyethane (-1 mL) in benzene (-50 mL). The solution was stirred for 1.5 h, filtered through Celite to { [ ( C - C ~ H O ) ~ ( S ~ ~ ~ I I ) ( O T M S ) I M O1 ((2Ob): = ~ ) ~MOOT (~PP~~) Clz (100 mg, 0.502 mmol) was added to a solution of Sa (680 remove TlC1, and evaporated (25 "C, 0.1 Torr) to afford a white solid. Analytically pure material can be obtained by washing mg, 0.502 mmol) and (CsH&PO (140 mg, 0.502 mmol) in the crude product with DME and drying in vacuo (25 "C, 0.1 benzene (-25 mL). The solution was stirred for 1.5 h, filtered Torr) or by allowing DME to diffuse into a pentane solution of through Celite to remove TlC1, and evaporated (25 "C, 0.1 Torr) to afford 20b as an amorphous white solid. Analytically pure 17a a t -35 "C. Yield: 968 mg (80%). Analytically pure powder can also be obtained by allowing DME to diffuse into product (508 mg, 75%) was obtained by cooling a pentane solution of 20b to -35 "C. Data for 20b: 'H NMR (500.1 MHz, a pentane solution of 17a a t -35 "C. Data for 17a: 'H NMR (500.1 MHz, C&, 25 "C): 6 2.15-0.90 (br m's, 77H); 0.415 Cs&, 25 "C): 6 7.695 (ddm, JH-P = 12 Hz, JH~-H,,, = 8.5 Hz, O-c*5,6H), 7.033 (m, 9H, m- andp-C*5),2.10-1.15 (br m's, (s, -SifCH3)3, 9H). 13C{lH}NMR (125.03 MHz, CsHs, 25 "C): 6 27.99, 27.86, 27.83, 27.63, 27.59, 27.48, 27.45, 27.34, 27.17, C&g, 63H), 0.410 (s, -Si(CH&, 9H). 13C{IH} NMR (125.03 27.06, 26.92, 26.79 (CH2); 25.37, 24.66, 24.13, 23.55 (1:2:2:2 MHz, C & 3 ,25 "C): 6 132.89 (d, J c - p = 9.6 Hz, o-C+&,), 132.59 (s, p-CsHs), 130.26 (d, Jc-p = 106.6 Hz, ipso-CsHs), 128.76 (d, for CHI; 6 2.01 (-Si(CH3)3). 95MoNMR (32.58 MHz, C&, 25 "C): 6 -70.64 ( ~ 1 1 2= 220 Hz). Anal. Calcd for C4&&fo014J c - p = 13.6 Hz, m-CsH5); 28.30, 28.22, 28.14, 28.00, 27.96, Si8 (found): C, 46.13 (46.22); H, 7.40 (7.51). Mp: 90 "C 27.54, 27.51, 27.40, 27.37, 27.32 (CH2), 24.89, 23.87, 23.04, 22.93 (1:4:1:1 for CH), 2.13 (-Si(CH&). 31P{1H}NMR (202.2 (decomp). CsHs): 6 33.36. Anal. Calcd for C ~ ~ H ~ ~ M O O I ~ P S ~ { [ ( C - C ~ H ~ I ) , ( S ~ ~ ~ I I ) ( ~ S ) I(19a): M O MoOz( ~ ) ~ ( C MHz, ~} (found): C, 49.75 (49.75); H, 6.49 (6.48). Mp: 178 "C (decomp). Clz (75 mg, 0.377 mmol) was added to a solution of 8a (548 Variable Temperature Study of 19a,b: At low tempermg, 0.377 mmol) and pyridine (0.031 mL, 0.377 mmol) in ature (C7D8, -60 "C), the 13C NMR spectra of 19a and 19b benzene (-25 mL). The solution was stirred for 1.5 h and are consistent with C1-symmetric structures. At room temfiltered through Celite to remove TlCl, and then the volatiles perature, the spectra are consistent with time-averaged C,were removed in vacuo (25 "C, 0.1 Torr) to afford 19a as a n symmetric structures. In the case of 19b there are seven amorphous white solid. All attempts to effect recrystallization methine (SiCH) resonances with equal intensity (6 24.55, were unsuccessful because 19a is extremely soluble in common 23.50, 23.36, 23.09, 22.94, 22.67, 22.34). When the solution organic solvents, but the product obtained in this fashion is pure by IH and 13CNMR spectroscopy. Data for 19a: 'H NMR is warmed to 25 "C, two pairs of methine resonances coalesce
3926 Organometallics, Vol. 14, No. 8,1995
Feher et al.
structure was solved by direct methods (SHELXTL PLUS). to produce a pattern of five resonances with relative integrated Full-matrix least-squares refinement of positional and thermal intensities of 1:2:2:1:1(624.95,23.85,23.68,23.00,22.85).The parameters (anisotropic for Si, 0, C, Mo, N) led to convergence same time-averaged spectra can be obtained by adding pyriwith a final R factor of 7.7 % for 777 variables refined against dine (1 equiv) at low temperature. 10 895 data with lFoi > 4.0a(IF0i).All other details regarding Variable Temperature Study of 20a,b: At low temperthe crystal structure are reported in the supporting informaature (C,Ds, -60 "C), the 13C NMR spectra of 20a and 20b tion. are consistent with C1-symmetric structures. At room temperature, the spectra are consistent with time-averaged C,symmetric structures. In the case of 20b there are seven Acknowledgment. These studies were supported by methine (SiCH) resonances with equal intensity (6 24.47, the National Science Foundation (CHE-9011593 and 24.44,23.62,23.17,22.74,22.65,22.51). When the solution CHE-9307750)and an NSF Presidential Young Invesis warmed to 25 "C, two pairs of methine resonances coalesce tigator Award (CHE-8657262).Acknowledgment is also to produce a pattern of four resonances with relative integrated made to the donors of the Petroleum Research Fund, intensities of 1:4:1:1(6 24.90,23.91,23.07,22.96). administered by the American Chemical Society, for X-ray Diffraction Study of 19b. Crystals suitable for a n partial support of this research. X-ray diffraction study were obtained by crystallization from C ~ H ~ ~ ) , Information Available: X-ray crystal data pentane. Crystal data for 19b ( C ~ ~ H , ~ _ N O ~ ~ S ~ ~ M O ' O . ~ (Supporting fw = 1188.8)are as follows: triclinic P1,a = 14.599(2)A, b = for 19b, including experimental procedures, tables of crystal 19.875(2)A, c = 21.826(3)A; a = 96.752(10)", p = 97.452(12)", data, atomic coordinates, thermal parameters, bond lengths, y = 107.282(10)", V = 5914.2(14)A3;Dcalcd= 1.335g/cm3 (2= and bond angles, and ORTEP figures (28 pages). Ordering 4). A total of 16 311 unique reflections with 4.0"5 28 5 45.0" information is given on any current masthead page. were collected on a Nicolet R3mN diffractometer at -110 "C OM950438L with use of graphite-monochromated Mo K a radiation. The
