4014
Organometallics 1996, 14, 4014-4017
Unexpected Reactivity of Functionalized Lewis Base Stabilized Silanediyl Transition Metal Complexes toward Organolithium Nucleophiles Robert J. P. Corriu,* Bhanu P. S. Chauhan, and G6rard F. Lanneau" Laboratoire des Precurseurs Organometalliques de Matiriaux, UMR 44-Universitk Montpellier 11, Case 007, Place Eugkne Bataillon, 34095 Montpellier Cedex 05, France Received March 14, 1995@ Summary: (OrganosilanediyUchromium(0)pentacarbonyl complexes, [2-(MeflCHdCd-lalRSi=Cr(CO)5 (R = Me, Ph, t-Bu, Ph-CEC-, Me3Si--C=C-), are obtained in good yield through the coupling reactions of (arylhydrogenosilanediyl)chromium(O) pentacarbonyl complex [~-(M~ZNCH~)CSH~~HS~=C~(CO)~, with the corresponding organolithium nucleophiles. Unexpectedly, the chloro- and bromosilanediyl complexes [2-(MeflCHdC&lXSi=Cr(CO)s (X = Cl, Br) are unreactive, but the fluorosilanediyl complex is even more reactive than the hydrogenosilanediyl complex with methyllithium. Possible geometries of the intermediate resulting in frontside attack of the nucleophile upon a zwitterionic silicon species are discussed. In recent years, silylene(silanediy1)-transition metal complexes,' [RzSi=ML,] have been elusive synthetic targets in the rapidly developing field of the organometallic chemistry of silicon. This interest is associated with their invoked intermediacy in a number of chemical transformations2 and also derives from the exciting reaction chemistry3 related to them. Since 1987, after discovery of the first stable silylene-transition metal c ~ m p l e x e sa, ~variety of synthetic strategies has been devised5-%oobtain such complexes stabilized by inter or intramolecular coordination of donor groups. The stabilizing influence of thiolate groups was also exploited to synthesize base-free tricoordinated silylene-
* Authors to whom correspondence should be addressed. FAX Number: (33) 67 14 38 88. @Abstractpublished in Advance ACS Abstracts, June 15, 1995. (1)( a ) Zybill, C.; Handwerker, H.; Friedrich, H. Adv. Organomet. Chem. 1994,36,229. (b) Tilley, T. D. Acc. Chem. Res. 1993,26,22. (c) Lickiss, P. D. Chem. SOC.Rev. 1992,271. (d) Tilley, T. D. In The Chemistry of Organic Silicon Compounds; Patai, S., Rappoport, Z., Eds.; Wiley: New York, 1989; pp 1415; Ibid., 1991; pp 309. (e) KeithWoo, L.; Smith, D. A,; Young, V. G., Jr. Organometallics 1991,10,3977. (0 Petz, W. Chem. Rev. 1986,86, 1019. (g) Kawano, Y.; Tobita, H.; Ogino, H. Angew. Chem., Int. Ed. Engl. 1991, 30, 843. (h) Denk, M.; Hayashi, R. K.; West, R. J . Chem. SOC.,Chem. Commun. 1994,33. (hj Jutzi, P.; Mohrke, A. Angew. Chem., Int. Ed. Engl. 1990,29,893. (i) Horng, K.M.; Wang, S. L.; Liu, C. S. Organometallics 1991,10,631. (i)Pi, Z.; Simons, R.; Tessier, C. XXVII Organosilicon Symposium, Troy, NY,1994; A l l . (2) (a) Curtis, M.D.; Epstein, P. S. Adv. Organomet. Chem. 1981, 91,213. (b) Ojima, I. In The Chemistry ofOrganic Silicon Compounds; Patai, S., Rappoport, Z., Eds.; Wiley: Chichester, U.K., 1989; pp 479. ( c ) Harrod, J. F.; Ziegler, T.; Tschinke, V. Organometallics 1990,9, 897. (dj Yamashita, H.; Tanaka, M.; Goto, M. Organometallics 1992, 11, 3227. (e) Hengge, E.; Weinberger, M.; Jammeg, C. J . Organomet. Chem. 1991,410, C1. (0 Corey, J. Y.; Chang, L. S.; Corey, E. R. Organometallics 1987,6, 1595.(g) Brown-Wensley, K. A. Organometallics 1987,6, 1590. (hj Aitken, C.; Harrod, J. F.; Samuel, E. J . Am. Chem. SOC. 1986, 108, 4059. ( i ) Hengge, E.; Weinberger, M. J . Organomet. Chem. 1993,443, 167. (j) Ojima, I.; Inaba, S. I.; Kogure, T.; Nagui, Y. J . Organomet. Chem. 1973,55, C7. (k) Chang, L. S.; Corey, J. Y. Organometallics 1989,8,1885. (1) Aitken, C.; Gill, U. S.; Harrod, J. F. Can. J . Chem. 1987,65,1804. (mj Harrod, J. F. ACS Symp. Ser. 1988,No. 360, 89. (n) Clarke, M. P.; Davidson, I. M. T. J . Organomet. Chem. 1981,408, 149. (0)Clarke, M. P. J . Organomet. Chem. 1989,376,165. ( p )Clarke, M. P.; Davidson, I. M. T.; Eaton, G. Organometallics 1988,7, 2076. (q) Okinoshima, H.; Yamamoto, K.; Kumada, M. J . A m . Chem. SOC.1972,94,9263. 0276-7333/95/2314-4014$09.0OlO
ruthenium or platinum comple~es.~ However, the reactivity of these complexes has not been extensively studied.1° We have recently described the preparation of arylhydrogenosilanediyltransition metal complexes'l through the dehydrogenative coupling reaction of primary silanes ArSiHs with transition metal carbonyls under (3)(a) Pannell, K. H.; Cervantes, J.; Hernandez, C.; Cassias, J.; Vincenti, S. Organometallics 1986,5, 1056. (b) Tobita, H.; Ueno, K.; Ogino, H. Bull. Chem. SOC.Jpn. 1988,61, 2797. (c) Haynes, A.; George, M. W.; Haward, M. T.; Poliakoff, M.; Turner, J. J.; Boag, N. M.; Green, M. J. A m . Chem. SOC.1991,113, 2011. (d) Pannell, K.H.; Wong, L.-J.; Rozell, J. M. Organometallics 1989,(e) Pannell, K. H.; Rozell, J . M.; Hernandez, C. J . Am. Chem. SOC.1989,111, 4482. (0 Seyferth, D.; Shannon, M. L.; Vick, S. C.; Lim, T. F. 0. Organometallics 1985,4, 57. (g) Sakurai, H.; Kamiyama, Y.; Nakadira, Y. J . A m . Chem. SOC. 1977,99,3879. (h) Marinetti-Mignani, A.; West, R. Organometallics 1987,6, 141. (i)Jones, K. L.; Pannell, K. H. J . Am. Chem. SOC.1993, 115,11336. (j)Ueno, K.;Tobita, H.; Ogino, H. Chem. Lett. 1990,369. (kj Denk, M.; Lennon, R.; Hayashi, R.; West, R.; Belyakov, A. V.; Verne, H. P.; Haaland, A.; Wagner, M.; Metzler, N. J. A m . Chem. SOC.1994, 116,2691. (4) ( a ) Straus, D. A.; Tilley, T. D.; Rheingold, A. L. J . Am. Chem. SOC.1987,109,5872. (b) Zybill, C.; Muller, G. Angew. Chem., Int. Ed. Engl. 1987,26,669. (5) ( a )Tilley, T. D. Comments Inorg. Chem. 1990,10,37. (b) Straus, D. A,; Zhang, C.; Quimbita, G. E.; Grumbine, S. D.; Hyne, R. H.; Tilley, T. D.; Rheingold, A. L.; Geib, S. J. J . A m . Chem. SOC.1990,112,2673. (c) Straus, D. A,; Grumbine, S. D.; Tilley, T. D.; J . Am. Chem. SOC. 1990,112,7801. (d) Grumbine, S.D.; Chadha, R. K.; Tilley, T. D. J . Am. Chem. SOC.1992,114, 1518. (6)(a)Zybill, C.; Muller, G. Organometallics 1988,7,1368. (bj Zybill, C.; Wilkinson, D. L.; Muller, G. Angew. Chem., Int. Ed. Engl. 1988, 27, 583. (c) Zybill, C.; Wilkinson, D. L.; Leis, C.; Muller, G. Angew. Chem., Int. Ed. Engl. 1989,28, 203. (dj Leis, C.; Wilkinson, D. L.; Handwerker, H.; Zybill, C. Organometallics 1992,11, 514. (e) Leis, C.; Zybill, C.; Lachmann, J.; Muller, G. Polyhedron 1991,10,1163. (D Handwerker, H.; Leis, C.; Gamper, S.; Zybill, C. Inorg. Chem. Acta. 1992, 200, 763. (g) Zybill, C. Top. Curr. Chem. 1991,160,1. ( h ) Handwerker, H.; Paul, M.; Riede, J.; Zybill, C. J . Organomet. Chem. 1993,459,151. (i)Probst, R.; Leis,C.; Gamper, S.;Herdtweck, E.; Zybill, C.; Auner, N. Angew. Chem., Int. Ed. Engl. 1991,30,1132. (7) (a)Corriu, R. J . P.; Lanneau, G. F.; Priou, C. Angew. Chem., Int. Ed. Engl. 1991,30, 1130. (b) Priou, C. Ph.D. Thesis, U. Montpellier 11, Montpellier, France, 1990. (cj Corriu, R.; Lanneau, G.; Chauhan, B. Miinchner Silicontage Munich, Germany, August, 1992. (d) Corriu, R. J. P.; Lanneau, G. F.; Chauhan, B. P. S. Organometallics 1993,12, 2001. (e) Chauhan B. P. S.; Corriu, R. J. P.; Lanneau, G. F.; Priou, C.; Auner, N.; Handwerker, H.; Herdtweck, E. Organometallics 1995,1414/,1657. ( 8 ) ( a )Uno, K.; Tobita, H.; Shimoi, M.; Ogino, H. J . Am. Chem. SOC. 1988,110,4092. (b) Tobita, H.; Uno, K.; Shimoi, M.; Ogino,H. J . Am. Chem. SOC. 1990, 112,3415. (c) Koi, J. R.; Tobita, H.; Ogino, H. Organometallics 1992,11, 2479. (dj Uno, K.; Tobita, H.; Ogino, H. J . Organomet. Chem. 1992,430,93. (e) Uno, K.; Tobita, H.; Ogino, H. Chem. Lett. 1993, 1723. (0 Uno, K.; Ito, S.; Endo, K.; Tobita, H.; Inomata, S.; Ogino, H. Organometallics 1994,13,3309. (9) (a) Grumbine, S.D.; Tilley, T. D.; Rheingold, A. L. J. A m . Chem. SOC.1993,115,358. (b) Grumbine, S.D.; Tilley, T. D.; Arnold, F. P.; Rheingold, A. L. J . A m . Chem. SOC.1993,115,7884. (c) Grumbine, S. K.; Tilley, T. D.; Arnold, F. P.; Rheingold, A. L. J . A m . Chem. SOC. 1994,116,5495. (10)( a )Kawano, Y.; Tobita, H.; Shimoi, M.; Ogino, H. J . A m . Chem. SOC.1994,116,8575. (bj Grumbine, S.K.; Tilley, T. D. J . A m . Chem. Leis, C.; Probst, R.; Bissinger, SOC.1994,116,6951. (c) Handwerker, H.; P.; Grohmann, A.; Kiprof, P.; Herdtweck, E.; Bliimel, J.; Auner, N.; Zybill, C. Organometallics 1993,12,2162. (dj Handwerker, H.; Paul, M.; Blumel, J.; Zybill, C. Angew. Chem., Int. Ed. Engl. 1993,32,1313. (e)Zhang, C.; Grumbine, S. D.; Tilley, T. D. Polyhedron, 1991,10,1173.
0 1995 American Chemical Society
Notes Si
=Cr-
co
Figure 1. Scheme 1
OoC
j
R.T
R = Ph
2 [+122]a [90%]
b
R=Me 3 [ +126.1] [92%] H,
y,co
R = t-Bu 4
[+138.5] [88%]
Si= Cr- CO
a N M e z
I
R' = SiMe3 5 [+92.3,-18.11a [76%1 R ' = Ph a
6 [ +92.2]
b
[9 1 %]
Legend: (a) 29Si-NMRchemical shifts in ppm (b) yields.
photolytic conditions. The photochemicaldisplacement reactions of complex 1, [2-(MezNCHz)C6H*IHSi=Cr(CO)j, with various phosphines led either to cleavage of the silicon-metal bond [PR3 = PPh3, P(OMeI31or the displacement of two carbonyls on the metal moiety with (dipheny1phosphino)ethane.Exchange reactions of complex 1 with Ph3CX afforded a series of functionalized complexes [2-(Me2NCH2)CsH*]XSi=Cr(CO)j {X = C1(7), Br (81, F (9)) (Figure 1). In the present note, we wish t o report the first successful coupling reactions of these complexes with organometallic nucleophiles. To our knowledge, only one example of attempted12 substitution reaction of a base-stabilized chlorosilanediyl-transition metal carbonyl complex with organolithium reagent has been described, leading merely to decomposition products. Reactions of complex 1 with organolithiums RLi (R = Me, Ph, t-Bu, Ph-CW-, Me3Si-CEC-) at 0 "C in dry toluene, under argon, furnished the corresponding R-substituted silanediyl-chromium(0) pentacarbonyl complexes in good yields (Scheme 1). Complex 2 has also been synthesized by the photochemical insertion reaction of Cr(CO)6 with [2-[(dimethylamino)methyl]phenyl]phenyldihydrosilane7e or by reaction of NazCr(C0)~with [2-[(dimethylamino)methyl]phenyl]phenyldichlorosilane,lOcbut complexes 3-6 would be difficult to obtain by those methods.13J4 Spectroscopic properties of the complexes are consistent with the proposed structures. 29Si-NMRchemical (11)( a ) Corriu, R.; Lanneau, G.; Chauhan, B. P. S. 16th International Conference on Organometallic Chemistry, Brighton, U.K.; Royal Society of Chemistry: Cambridge, U.K., 1994; OB-10. (b)Corriu, R. J. P.; Chauhan, B. P. S.; Lanneau, G. F. Organometallics 1995, 14(41, 1646. ( 1 2 ) Schmid, G.; Welz, E. Angew. Chem., Int. Ed. Engl. 1977, 16, 785. (13) For example, reaction of [2-[(dimethylamino)methyllphenyllmethylsilane with Cr(CO)eunder photolytic conditions in pentane led to the formation of a mixture of three products, along with complex 3 in 10% yield.
shifts of complexes 2-6 fall in the range of +90 to +140 ppm, which is characteristic of Lewis base stabilized silanediyl metal complexes having at least one aromatic group on silicon atom1 As anticipated, 'H-NMR and 13C-NMR data confirmed the rigid coordination of dimethylamino groups to the silicon atom. IH-NMR spectra showed two signals for diastereotopic methyl groups on nitrogen. An AB system was observed for the methylene protons, indicating hindered rotation around the C-N bond. Two signals for diastereotopic methyl groups on nitrogen were also observed in 13C-NMR spectra (see Experimental Section). In light of the above results, we have attempted nucleophilic substitution reactions on the silicon atom of halogen-substituted silanediyl-chromium complexesll 7-9 with several nucleophiles. To our surprise, complexes 7 and 8 showed no reactivity toward organolithiums RLi (R = Me, Ph, t-Bu) and metal methoxides MOCH3 (M = Na, K). For example, when methyllithium was added dropwise to the complex ([2-[(dimethylamino)methyllphenyllchlorosilanediyl)chromium(0)pentacarbonyl, 7,in a one-to-one ratio in toluene at 0 "C followed by stirring at room temperature, no reaction was observed even after 72 h. If the mixture was refluxed for 4 h in toluene, the decomposition of complex 7 t o unidentified products was observed. In the case of the complex ([2-[(dimethylamino)methyllphenyllbromosilanediyl)chromium(O) pentacarbonyl, 8, reaction with methyllithium under identical conditions resulted in less than 10% conversion (calculated on the basis of lH-NMR of the mixture) t o the corresponding methylsilanediyl complex 3, but most of the starting material was recovered (Scheme 2). It should be noted that the nucleophilic addition of RLi onto a CO functionality, a well-known synthetic approach t o carbenes,15 is not observed in the present case. The absence of reactivity of complexes 7 and 8 led us to investigate the chemical behavior of the fluorosubstituted silanediyl-chromium complex 9 toward various nucleophiles. In contrast to the results obtained with 7 and 8, complex 9 reacted smoothly with organolithiums, giving rise to the corresponding organosilanediyl complexes in good yields. For instance, reaction of methyllithium with complex 9 under identical reaction conditions (as for 1, 7, and 8) afforded complex 3 in 98% yield in 12 h. A comparison of the reactivity of complex 1 and complex 9 toward nucleophiles (MeLi as title example) has been carried out. In a complementary experiment, 1 and 9 were dissolved in toluene in equimolar amounts. This mixture was treated with 0.5 equiv of methyllithium at 0 "C and warmed t o room temperature. The (14) For comparison of the characteristic signals of acetylenic groups directly attached to a hypercoordinated silicon atom, see: Boyer-Elma, K.; Corriu, R. J. P.; Douglas, W. E. In Silicon Containing Polymers; Jones, R. G., Ed.; Royal Society of Chemistry: Cambridge, in press. (15) Cardin, D. J.; Cetinkaya, B.; Lappert, M. F. Chem. Reu. 1972, 72, 545.
4016 Organometallics, Vol. 14, No. 8,1995
P\;+117.2'
LL
Notes
3 (+126.1)
Figure 4.
1 (+110.9)
-wdw'
w-
=Si NMR of the mixture before 29Si NMR of the mixture after 12h addition of methyl lithium.
of reaction with methyl lithium.
Figure 2. XO Nu
I
Unfavorable Out of phase Overlap
Figure 3.
course of the reaction was followed by IR and 29Si-NMR. After 12 h, 29Si-NMRof the reaction mixture indicated complete consumption of complex 9 and the appearance of a new peak at d +126.1, due to formation of complex 3 (Figure 2). This reaction clearly demonstrates that fluorosilanediyl-chromium complex 9 is more reactive toward nucleophiles than is the hydrosilanediyl-chromium complex 1. On the basis of the above studies, the following order of reactivity of Lewis base stabilized functional silanediyl-chromium complexes toward various nucleophiles can be proposed:
a
b
C
Figure 5.
Silanediyl-transition metal complexes can be represented by a t least three resonance structures shown in Figure 5. With a and/or b as the formulated reactive species, there are no precedents in the literature for discussing the present data. On the other hand, if one supposes the zwitterionic structure c to be the reactive species involved in the nucleophilic substitution reaction, then geometrical arguments which have been earlier emphasized in the SN2(Si) reactions would favor here a retention pathway. X-ray structure determination of two aminoarylsilanediyl-transition metal complexes [2-(Me2NCH2)C6H4]C&jSi=M(CO),, (M = Cr, n = 5; M = Fe, n = 4) are reported in the l i t e r a t ~ r e . ~In ' . ~the ~ five-membered ring created through coordination of nitrogen to silicon, the bond angle LNSiCl equals 85.7 and 86.8", respectively, which liberates a large cone angle for frontside attack of the nucleophile, giving rise to retention of configuration (Figure 3). Such a pathway is not favorable for chlorine-silicon bond cleavage, which could explain the lower reactivity of chloro-, and bromosilanediyl-chromium complexes. Experimental Section
It is interesting to note that this order is unexpectedly different from the order of reactivity of the corresponding saturated silanes R3SiX with nucleophiles (Br, C1 > F > H), which essentially parallels the polarizability of the leaving group.16 Such behavior could be related to the nature of the bond between the leaving group and the silicon atom of silanediyl complexes. Anh and M i n ~ t have l ~ ~tentatively ~ rationalized the stereochemistry of nucleophilic attack a t tetrahedral silicon by an extension of Salem's treatment of Walden inversion.17c Retention and/or inversion were considered to be the result of a fine balance between the inphase and out-of-phase orbital overlap between the nucleophile and the LUMO of the substrate 8 Si-X (Figure 3). Hybridization arguments also explained the order of reactivity of cyclic systems (Figure 4).18 Ring contraction decreases the s character of the intracyclic Si-C bonds which in turn increases the s character of the exocyclic Si-X bond. Both increased reactivity and displacement toward retention of configuration have been observed with such systems.
General Comments. All manipulations were performed under a n atmosphere of dry argon by standard Schlenk tube techniques. Solvents were distilled from sodium benzophenone ketyl. Starting functionalized silanediyl-transition metal complexes 1 and 7-9 were prepared as previously reported.7c.11 Commercially available chemicals were used as such without any further purification. 29Si, W , 'H, and 131PNMR spectra were recorded on Bruker WP 200 SY or AC 250 spectrometer. chemical shifts were measured against Me4Si using 'H and solvent resonances as standard locks. 29Sichemical shifts were referenced to external MedSi in the same solvent. IR spectra were recorded on Perkin Elmer 1600 FT as KBr pellets, Nujol suspensions, or solutions in CaF2 cells. The mass spectra were obtained on a JEOL JMS DlOO apparatus by E1 ionization at 30 or 70 eV. Elemental analyses were carried out by the Service Central de Microanalyse du CNRS or ENSC Montpellier. Preparation of Complexes 2-6. Freshly prepared complex ( I 2-[(dimethylamino)methyl]phenyllhydrosilanediyl)chromium(0) pentacarbonyl, 1,(1.06 g, 3 mmol) was dissolved in 30 mL of toluene in a Schlenk tube and kept at 0 "C. To this cold solution was added PhLi (3.57 mL, 3 mmol) dropwise for 20 min. After 2 h lithium hydride salt started precipitat-
(16) ( a ) Corriu, R. J. P.; Guerin, C. Adu. Organomet. Chem. 1982, 20,265.(b)Corriu, R.J. P.; Lanneau, G. F. Bull. SOC.Chim. Fr. 1973, 3102.(c) Corriu, R.J. P.; Guerin, C.; Moreau, J. J. E. Top. Stereochem. 1984,15,43. (d) Breliere, C.; Corriu, R. J. P.; DeSaxce, A.; Royo, G. J . Organomet. Chem. 1979,166,153. (17) ( a )Anh, N.T.; Minot, C. J. Am. Chem. Soc. 1980,102,103.(b) Minot, C.; Anh, N. T. Tetrahedron Lett. 1975,3905.(c) Salem, L.Chem. Ber. 1969,5 , 449.
(18)(a)Hommer, G.D.; Sommer, L. H. J. Am. Chem. SOC.1973,95, 7700.(b) Corriu, R. J. P.; Henner, R. J. L. J . Organomet. Chem. 1975, 102,407.(c) Hilderbrandt, R. L.; Hommer, G. D.; Boudjouk, P. J. Am. Chem. SOC.1976,98, 7476. (d) Cartledge, F. K.; McKinnie, R. G.; Wolcott, J. M. J. Organomet. Chem. 1976, 118, 7. (e) Corriu, R.; Fernandez, J. M.; Guerin, C. J. Organomet. Chem. 1978,152,21;25. tf7 Bassindale, A. R.; Taylor, P. In The Chemistry of Organic Silicon Compounds; Patai, S., Rappoport, Z.,Eds.; Wiley: Chichester, U.K., 1989;pp 839.
Organometallics, Vol. 14, No. 8, 1995 4017
Notes ing. The course of the reaction was followed by 'H-NMR, which indicated complete consumption of complex 1 after 24 h of stirring a t room temperature. The LiH salt was filtered out, and toluene was evaporated to give 2 in 90% yield. The same procedure and stoichiometric quantities of reactants were used for the preparation of 3-6. Complex 2: ([2-[(Dimethylamino)methyllphenyllphenylsilanediyl)chromium(O)Pentacarbonyl. Mp: 171 "C. Yield 90%. The compound has been identified by comparison of NMR characteristics with those of a n authentic ~ a m p l e . ~ 29Si-NMR ~J~~ (CDC13): 6 +121.9. W-NMR (CDC13): d 47.3 (N-CH3),48.6 (N-CH3),68.2 (N-CH2),123.8, 128.85, 129.75, 134.6, 139.1, 142.8 (aromatics), 221.3 (CO, equatorial), 224.8 (CO, axial). Complex 3: ([2-[(dimethylamino)methyllphenyllmethylsilanediyl)chromium(O) pentacarbonyl. Yellow powder. Mp: 131 "C(decomp). Yield 92% Anal. Calcd for C15H15N05SiCr: C, 48.78; H, 4.06; N, 3.79. Found: C, 48.82; H, 4.02; N, 3.81. 29Si-NMR (CDC13): d +126.13. W-NMR (CDC13): d 7.36 (Si-CH3), 46.22 (N-CHd, 48.79 (N-CHd, 68.39 (N-CHz), 124.01, 128.96, 129.83, 133.53, 138.52, 145.03 (aromatics), 222.12 (CO, eq), 225.82 (CO, ax). 'H-NMR (CDC13): d 0.47 (s, 3H, Si-CH3), 1.73 (s, 3H, N-CHd, 1.97 (s, 3H, N-CH3), 2.58-2.63, 3.25-3.30 {dd, 2H, AB system, *J(IH-~H! = 14.26 Hz, N-CHz}, 6.67, 7.05, 8.02 (m, 4H, aromatics). MS (EI, 30eV) mle (relative intensity, %) 369 (M+, 25), 341 (-CO, lo), 285 (-3C0,04), 257 (-4C0,46), 252 (15), 235 (181, 200 (38), 178 (loo), 162 (22). IR (CsDs, cm-'1: v(CO) 1910 (br), 2034. Complex 4: ([2-[(Dimethylamino)methyllphenyll-tertbutylsilanediyl)ch"ium(O) Pentacarbonyl. Light brown powder. Mp: 153 "C (decomp) Yield 88%. Anal. Calcd for ClsHzlNOsSiCr: C, 52.55; H, 5.10; N, 3.40. Found: C, 52.58; H, 5.13; N, 3.42. 29Si-NMR (CDC13): d 1139.5. 13C-NMR (CDC13): d 27.44 ("C-CH3), 29.33 (C-C"H3), 45.39 (N-CHs), 47.25 (N-CHs), 63.77 (N-CHz), 125.11,126.82, 130.02,134.13, 139.12, 145.40 (aromatics), 222.55 (CO, eq), 224.84 (CO, ax). MS (EI, 30eV) mle (relative intensity, %) 411 (M+, lo), 383 (-CO, 8),356 (-2C0,06), 327 (-3C0, lo), 299 (-4C0,9), 271 (-5C0, loo), 220 (20), 192 (13), 162 (28), 135 (12), 119 (18), 91 (11). IR (CDC13, cm-'): v(C0) 1907 (br), 2036.
Complex 5 ([2-[(Dimethylamino)methy1lphenylltrimethylsilylethynylsilanediyl)chromium(O)Pentacarbonyl. Yield 76%. Anal. Calcd for C19H21N05Si&r: C, 50.55; H, 4.65; N, 3.10. Found: C, 50.59; H, 4.71; N, 3.02. 29Si-NMR (C&): d f92.31, -18.04. 13C-NMR(CsDs): d 0.26 (Si-CH3), 46.03 (N-CH3), 46.13 (N-CH3), 68.96 (N-CHz), 93.52 (C=C*SiMe3), 113.12 (C*WSiMe3), 124.05, 128.62, 130.24, 134.09, 139.83, 141.66 (aromatics), 220.76 (CO, eq), 224.96 (CO, ax). 'H-NMR (CsDs): d 0.15 (s, 9H, SiMea), 1.85 (s, 3H, N-CH3), 2.10 (s,3H, N-CH3), 2.55-2.65, 4.05-4.15 (dd, 2H, AB system, 'J,~H-IH, = 13.40 Hz, N-CHz}, 6.56, 6.92, 7.98 (m, 4H, aromatics). MS (EI, 30eV) mle (relative intensity, %) 451 (M+, 391, 395 (-2C0, 35), 367 (-3C0, 32), 339 (-4C0, 821, 311 (-5C0, loo), 287 (12), 268 (lo), 244 (81, 162 (22), 135 (9), 119 (lo), 91 (7). IR (C&, cm-'): V(C0) 1831, 1909, 2043; V (C=C) 2025. Complex 6: ([2-[(dimethylamino)methyllphenyllphenylethynylsilanediyl)chromium(O) Pentacarbonyl. Yield 91%. Anal. Calcd for CzzH17N05SiCr: C, 58.02; H, 3.73; N, 3.07. Found: C, 58.14; H, 3.81; N, 3.01. 29Si-NMR (CDC13): d +92.16. 13C-NMR(CDC13): d 46.46 (N-CHs), 46.48 (N-CH3), 69.05 (N-CHz), 92.72 (CmC*Ph), 114.86 (SiC*=CPh), 125.30, 127.61, 128.26, 129.03, 130.97, 132.07, 139.45, 141.47 (aromatics), 220.52 (CO, eq), 224.56 (CO, ax). 'H-NMR (CsDs): 1.78 (s,3H, N-CHz), 2.19 (s, 3H, N-CH3), 2.96-3.01, 3.87-3.92 (dd, 2H, AB system, ' J O H - I H = !12.47 Hz, N-CHz}, 7.19, 7.26, 7.29, 7.31, 7.44, 7.98 (m, 4H, aromatics). MS (EI, 30eV) mle (relative intensity, %) 455 (M+, 9), 399 (-2C0,12), 371 (-3C0,14), 343 (-4C0,21), 315 (-5C0, loo), 272 (12), 262 (81, 248 (51, 219 (51, 162 (12). IR (CsDs, cm-'): v(C0) 1821, 1906, 2044; v(CGC) 2143. Competition Experiment. Compounds 1 (0.89 g, 2.5 mmol) and 9 (0.93 g, 2.5 mmol) were dissolved in 50 mL of toluene and kept a t 0 "C. MeLi (2.4 mL, 3 mmol) was added dropwise to this mixture, and the solution was warmed to room temperature. After 12 h, 29Si-NMRindicated complete disappearance of the signal corresponding to complex 9 [d +117.2 (INVGATE, d, l J , ~ ~ = ~ I398.5 - ~ sHzl, ~ , and a new signal a t (d +126.1) for complex 3 was observed. OM950193C
