Hydrogenolysis and Protonation of Polymetallic LutetiumMethylidene and Methyl Complexes.

We report the hydrogenolysis andprotonation reactions of a tetrametalliclutetium tetramethylidene complex [Cp′Lu(μ3-CH2)]4(Cp′ = C5Me4SiMe3) (1) and a trimetallic lutetium hexamethylcomplex [Cp′Lu(μ2-CH3)2]3(2) with H2and ammonium boratecompounds. The hydrogenolysis of 1with H2afforded the corresponding tetrahydride tetramethyl complex [Cp′4Lu4(μ4-H)(μ3-H)(μ2-H)2(μ2-Me)4] (3) in 87% yield. In this transformation, each of the four[Lu-μ2-CH2] methylidene groups in 1reacted with one molecule of H2to give a mixedmethyl/hydride “Lu(H)CH3” unit. The reactionof 1with [PhMe2NH][B(C6F5)4] gave the cationic tetrametallic lutetium monomethyltrimethylidene complex [Cp′4Lu4(μ3-CH2)3(μ3-CH3)][B(C6F5)4] (4) in85% yield, through protonation of one of the four methylidene unitsin 1with the anilinium borate. In contrast, the reactionof the trimetallic hexamethyl complex 2with H2led to formation of a tetrametallic lutetium monohydride heptamethylcomplex [Cp′4Lu4(μ4-H)(μ3-Me)(μ2-Me)6] (5)in 65% yield, while the protonation reaction of 2with3 equiv of [Et3NH][BPh4] gave a monometalliclutetium monomethyl contact-ion-pair complex [Cp′LuMe(η6-Ph)(η1-Ph)BPh2] (6) in 81% yield. Complexes 3–6werefully characterized by 1H and 13C NMR, single-crystalX-ray diffraction, and micro elemental analyses. [ABSTRACT FROM AUTHOR]