COORDINATION CHEMISTRY OF SILOLES: VINYL-, ALLYL- AND ALKYNYL-SILOLES; SYNTHESIS AND STRUCTURE OF η4,η2-1-ALLYL- AND 1-VINYL-2,5-DIPHENYLSILACYCLOPENTADIENE COMPLEXES

Article abstract of DOI:10.1016/S0022-328X(00)99764-X

The reactions of 1-allyl-1-methyl- (8), 1-vinyl-1-methyl- (10), 1,1-diallyl- (14), 1,1-divinyl- (16), 1-ethenyl-1-methyl- (2a) and 1-propynyl-1-methyl-2,5-diphenylsilacyclopentadiene (2b) (or siloles) with transition metals are described.Competition between complexation of the diene and that of the triple bond of the propynylsilole is observed with Co2(CO)8, but with Fe2(CO)9, the η⁴-complexes are obtained in all cases.Co2(CO)8 reacts with the vinyl- and allyl-siloles to give η⁴-complexes, but Mo(CO)4(COD) (COD = 1,5-cyclooctadiene) or W(CO)3(CH3CN)3 gives η⁴,η²-complexes.The crystal structures of (η⁴-(η²-endo-1-allyl)-exo-1-methyl)- (9a) and (η⁴-(η²-endo-1-vinyl)-exo-1-methyl-2,5-diphenylsilacylopentadiene)tricarbonyl molybdenum (12a) have been determined.They show that the dihedral angle between the diene and the C(1)-Si-C(2) plane is 28 deg in the case of the allyl derivative 9a but only 8.9 deg in the vinyl complex 12a.