945956-93-4Relevant academic research and scientific papers
Allyl isomerization mediated by cyclopentadienyl group 6 metal compounds
Royo, Eva,Acebron, Sergio,Mosquera, Marta Elena Gonzalez,Royo, Pascual
, p. 3831 - 3839 (2008/10/09)
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{η5- 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{η5-C 5R4R′}(CO)3] (R = CH3, R′ = H (16); R = H, R′ = SiMe3 (17)) in isolated yields of 60-70%. THF solutions of derivatives 5a, 7a, and 8a undergo isomerization of the cyclopentadienyl-tethered-allyl unit to give the corresponding methyl-vinyl-dimethylsilyl-η5-cyclopentadienyl hydrido compounds [MH{η5-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 be crucial in these transformations. Dehydrogenation and desilylation of 5a in THF solutions to give the dinuclear derivative [Mo{η5-C5H 4Si(CH3)2(CH2CH=CH2) }(CO)3]2 (9) and [MoH(η5-C 5H5)(CO)3] (15), respectively, are processes competitive with the allyl isomerization. Treatment of 5a and 7a with equimolar amounts of ONMe3 permits isolation of pure compound 9 and [W{η5-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{η5-C5H4Si(CH3) 2(CH2CH=CH2)}(CO)3][B(C 6F5)4] (M = Mo (18), W (19)). Molecular structure determinations by X-ray diffraction methods for derivatives 8a and 9 are also reported.
