Highly selective mono- and di-alkylation of the backbone of complexes of type fac-[M(CO)3{E,Z-PPh2CH2C(But)N–NC(But)CH2PPh2}](M = Mo or W)

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Treatment of the tricarbonylmolybdenum(0) complex, [[graphic omitted]·Ph2}]1a with 1 equivalent of LiBun selectively deprotonated the backbone to give the carbanion [[graphic omitted]Ph2}]–, which on addition of methyl iodide or allyl bromide gave the monoalkyl complexes [[graphic omitted]Ph2}](R = Me 2a or CH2CHCH23a). The tungsten(0) analogues 2b and 3b were similarly prepared from [[graphic omitted]Ph2}]1b. Treatment of the tricarbonyltungsten(0) carbanion with deuterium oxide gave the monodeuteriated complex [[graphic omitted]Ph2}]4. Treatment of 1b with 4 equivalents of LiBun followed by methyl iodide gave the dimethyl complex [[graphic omitted]Ph2}]5a, specifically as R,R and S,S isomers. Complex 5a was also prepared by deprotonating and methylating 2b. The analogous molybdenum complex 5b was similarly prepared from 1a. Proton, 13C-{1H}, 31P-{1H} NMR and infrared data are reported. The crystal structures of 2a and 5a have been determined.