Stable anionic η1-vinylidene complexes of molybdenum and tungsten

Abstract

Secondary carbanions [CHXY]^–(X,Y = CN, CO₂Et) react with the η¹-chlorocarbyne ligand in [L(CO)₂MCCl][L = hydrotris(3,5-dimethylpyrazol-1-yl)borate, M = Mo, W] to yield the first isolable anionic group 6 η¹-vinylidene complexes [L(CO)₂M(C·CXY)]^– and reaction of the latter (M = Mo, X = CN or CO₂Et, Y = CO₂Et) with a variety of electrophilic or oxidising reagents yields in each case a single neutral product, one example of which has been crystallographically characterised as the 7-co-ordinate oxametallacyclic carbene complex [L(CO)₂[graphic omitted]]; in contrast HgX₂, CuI, and [ArN₂]BF₄ yield novel highly functionalised carbyne complexes [L(CO)₂MC·C(CN)(CO₂Et)(Z)] where Z = HgX, Cu, and N₂Ar respectively.