Allyl Isomerization Mediated by Cyclopentadienyl Group 6 Metal Compounds
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- 作者：Eva Royo ; Sergio Acebró ; n ; Marta Elena Gonzá ; lez Mosquera ; Pascual Royo
- 刊名：Organometallics
- 出版年：2007
- 出版时间：July 16, 2007
- 年：2007
- 卷：26
- 期：15
- 页码：3831 - 3839
- 全文大小：192K
- 年卷期：v.26,no.15(July 16, 2007)
- ISSN：1520-6041
文摘
Reactions at mild temperatures of the acetonitrile adducts [M(CO)3(NCMe)3] (M = Mo (1), W (2))with various substituted cyclopentadienes in THF give the hydrido derivatives [MH{
5-C5R4Si(CH3)2-(CH2CH=CH2)}(CO)3] (M = Mo, R = H (5a), R = CH3 (6), M = W, R = H (7a), R = CH3 (8a)) and[MoH{5-C5R4R'}(CO)3] (R = CH3, R' = H (16); R = H, R' = SiMe3 (17)) in isolated yields of60-70%. THF solutions of derivatives 5a, 7a, and 8a undergo isomerization of the cyclopentadienyl-tethered-allyl unit to give the corresponding methyl-vinyl-dimethylsilyl-5-cyclopentadienyl hydridocompounds [MH{5-C5R4Si(CH3)2(CH=CHCH3)}(CO)3] (M = Mo, R = H (5b), M = W, R = H (7b),R = CH3 (8b)) in final a:b ratios of ca. 2:1, 2:1, and 1:1, respectively. Solvent polarity seems to becrucial in these transformations. Dehydrogenation and desilylation of 5a in THF solutions to give thedinuclear derivative [Mo{5-C5H4Si(CH3)2(CH2CH=CH2)}(CO)3]2 (9) and [MoH(5-C5H5)(CO)3] (15),respectively, are processes competitive with the allyl isomerization. Treatment of 5a and 7a with equimolaramounts of ONMe3 permits isolation of pure compound 9 and [W{5-C5H4Si(CH3)2(CH2CH=CH2)}(CO)3]2 (10) in isolated yields of 80-90%. Coordination of the olefin pendant unit to the metal was detectable only by reaction of 5a and 7a with [CPh3][B(C6F5)4] to give the cationic species [M{5-C5H4Si-(CH3)2(CH2CH=CH2)}(CO)3][B(C6F5)4] (M = Mo (18), W (19)). Molecular structure determinations byX-ray diffraction methods for derivatives 8a and 9 are also reported.
5-C5R4Si(CH3)2-(CH2CH=CH2)}(CO)3] (M = Mo, R = H (5a), R = CH3 (6), M = W, R = H (7a), R = CH3 (8a)) and[MoH{5-C5R4R'}(CO)3] (R = CH3, R' = H (16); R = H, R' = SiMe3 (17)) in isolated yields of60-70%. THF solutions of derivatives 5a, 7a, and 8a undergo isomerization of the cyclopentadienyl-tethered-allyl unit to give the corresponding methyl-vinyl-dimethylsilyl-5-cyclopentadienyl hydridocompounds [MH{5-C5R4Si(CH3)2(CH=CHCH3)}(CO)3] (M = Mo, R = H (5b), M = W, R = H (7b),R = CH3 (8b)) in final a:b ratios of ca. 2:1, 2:1, and 1:1, respectively. Solvent polarity seems to becrucial in these transformations. Dehydrogenation and desilylation of 5a in THF solutions to give thedinuclear derivative [Mo{5-C5H4Si(CH3)2(CH2CH=CH2)}(CO)3]2 (9) and [MoH(5-C5H5)(CO)3] (15),respectively, are processes competitive with the allyl isomerization. Treatment of 5a and 7a with equimolaramounts of ONMe3 permits isolation of pure compound 9 and [W{5-C5H4Si(CH3)2(CH2CH=CH2)}(CO)3]2 (10) in isolated yields of 80-90%. Coordination of the olefin pendant unit to the metal was detectable only by reaction of 5a and 7a with [CPh3][B(C6F5)4] to give the cationic species [M{5-C5H4Si-(CH3)2(CH2CH=CH2)}(CO)3][B(C6F5)4] (M = Mo (18), W (19)). Molecular structure determinations byX-ray diffraction methods for derivatives 8a and 9 are also reported.