Abstract

The tungsten butatrienylidenes cis-W(CO)(dppe)(2)] (R = SnMe3 (2) and SiMe3 (3); dppe = 1,2-bis(diphenylphosphinoethane)) were prepared from the reactions of trans-W(CO)(N-2)(dppe)(2)] (1) and the respective butadiynes displaying a 1,4-shift of the respective SnMe3 groups along the butadiyne chains. Stannyl deprotection of 2 with NBu4F center dot 3H(2)O led to the anionic butadiyne derivative trans-W(CO)(dppe)(2)(C CC CH)]NBu4] (10). The reaction of 1 with stannylated acetylenes gave the vinylidene derivatives cis-W(CO)(dppe)(2)](R = Ph (5) or SnMe3 (6)), which lost a SnMe3 group, yielding W(I) acetylides of the type trans-W(CO)(dppe)(2)(C CR)] (R = Ph (7), SnMe3 (8), and SiMe3 (9)). They were studied by cyclic voltammetry and EPR spectroscopy.