Formation and Cleavage of C−C, C−O, and O−H Bonds Involving Methoxycarbyne and Hydroxycarbyne Ligands at Unsaturated Dimolybdenum Complexes

Reversible carbyne−carbyne coupling occurs
upon addition of simple ligands L (CO, tBuNC) to
the bis(methoxycarbyne) complex [Mo2Cp2(μ-COMe)2-(μ-PCy2)]BF4 to give the dimethoxyacetylene-bridged
derivatives [Mo2Cp2{μ-η2:η2-C2(OMe)2}(μ-PCy2)L2]BF4.
Upon demethylation, the dicarbonyl cation experiences
a 1,2-methoxyl shift to give the carboxycarbyne derivative
[Mo2Cp2{μ-C(CO2Me)}(μ-PCy2)(CO)2].