摘要:
Compound (CpMoCl4)-Mo-Et (Cp-Et= eta(5)-C5Et5) (1) can be transformed into (CpMoH3)-Mo-Et(dppe) (2) and (CpMoD3)-Mo-Et(dppe) (2-d(3)) [dppe = 1,2-(diphenylphosphino)ethane] by reaction with LiAlX4 (X = H and D, respectively). The protonation and oxidation studies of these two compounds, in comparison with previously reported studies on (C5Me5) analogs, show important differences that may be attributed to a kinetic stabilization of the products, which is steric in nature. Protonation of 2 with HBF, in acetonitrile affords [(CpMoH4)-Mo-Et(dppe)](+) (3), which only slowly decomposes to [(CpMoH2)-Mo-Et(MeCN)(dppe)](+) (4). Further protonation of the latter affords the monohydride species [Cp*MoH(dppe)(MeCN)(2)](2+) in three different forms, 5-7. Direct protonation of 2 with 2 equiv, of HBF, shows the formation of all of the above compounds, plus a new compound, [(CpMoH3)-Mo-Et(dppe)(MeCN)](2+) (8), to which a classical structure is assigned. The protonation of 2-d(3) indicates reversibility for the proton transfer processes. The oxidation of 2 in MeCN affords [2](+), which decomposes slowly in MeCN to afford a mixture of 4 and 5 as major products. No compound 8, on the other hand, is obtained by oxidation of 2, neither with 1 nor with 2 equiv. of oxidizing agent. Mechanistic schemes that rationalize all these observations are proposed. (C) 2000 Elsevier Science S.A. All rights reserved.