Reaction of the η2(4e)-donor alkyne complexes [Mo{η2(4e)-R1C2R2}{P(OMe)3}2(η-C5H5)](R1= R2= Ph or Me; R1= Me, R2= Ph) with the Grignard reagents MgR3(X)(R3= Me, Et, CH2Ph, CH2CHCH2or CHCH2) and CH2(MgI)2
摘要:
Reaction of the complex [Mo{eta(2)(4e)-PhC(2)Ph}{P(OMe)(3)}(2)(eta-C5H5)][BF4]1 with MgR(X) (R = Me, Et or PhCH(2)) afforded good yields of [Mo{eta(2)(4e)-PhC(2)Ph}R{P(OMe)(3)}(eta-C5H5)]. Unexpectedly, reaction of 1 with the 1,1-di-Grignard reagent CH2(MgI)(2) gave the X-ray crystallographically identified zwitterionic complex [Mo{eta(2)(4e)-PhC(2)Ph}{eta(2)-P(OMe)(2)OBF2OP(OMe)(2)}(eta-C5H5)], similar reactions with the but-2-yne and 1-phenylprop-2-yne complexes affording the analogous [Mo{eta(2)(4e)-RC(2)R(2)){eta(2)-P(OMe)(2)OBF2OP(OMe)(2)}(eta-C5H5)] (R = R(2) = Me; R = Me, R(2) = Ph). Treatment of the zwitterionic diphenylacetylene- and 1-phenylprop-2-yne-substituted complexes with K[BHBu(3)(s)] gave the anionic eta(2)(3e)-vinyl complexes K[Mo{=C(R)CH(Ph)}{eta(2)-P(OMe)(2)OBF2OP(OMe)(2)(eta-C5H5)] (R = Ph or Me). Protonation (HBF4 . Et(2)O) of the diphenyl-substituted eta(2)(3e)-vinyl complex followed by addition of carbon monoxide, trimethyl phosphite, or diphenylacetylene afforded trans-stilbene and the complexes [Mo(CO)(2){eta(2)-P(OMe)(2)OBF2OP(OMe)(2)}(eta(2)-C5H5)], [Mo{P(OMe)(3)}(2){eta(2)-P(OMe)(2)OBF2OP(OMe)(2)}(eta-C5H5)] and [Mo{eta(2)(4e)-PhC(2)Ph}{eta(2)P(OMe)(2)OBF2OP(OMe)(2)}(eta-C5H5)] respectively. When CH2=CHCH2MgBr was added to 1 an unstable compound was formed, which on addition of P(OMe)(3) gave [Mo{eta(3)-C(Ph)=C(Ph)CH2CH=CH2}{P(OMe)(3)}(2)(eta-C5H5)], the identity of which was confirmed by X-ray crystallography. This reaction is explained in terms of an unusual metalla-3,3-sigmatropic shift process. A similar reaction between 1 and CH2=CHMgBr followed by addition of P(OMe)(3) surprisingly gave the eta(3)-cyclopropenyl complex [Mo(eta(3)-C(3)Ph(2)Me){P(OMe)(3)}(2)(eta-C5H5)]. The complex [Mo{eta(2)(4e)-PhC(2)Ph}Me{P(OMe)(3)}(eta-C5H5)] reacted thermally (78 degrees C) with an excess of PhC(2)Ph to give the X-ray crystallographically identified complex [MoH(eta(4)-C(5)H(2)Ph(4)){P(OMe)(3)}(eta-C5H5)], which on heating (100 degrees C) afforded the dihydride [MoH2(eta(5)-C(5)HPh(4))(eta-C5H5)].