Oligomerization of the PH3CuCCCuPH3 Acetylide toward the Formation of (PH3CuC)n (n = 4, 6, 8) Metal Carbides: A Theoretical Study Based on Density Functional Theory

Density functional calculations were performed on a series of Cu(PH3)-substituted cyclopolyenes as simple models of molecular metal carbides. We studied the oligomerization of the copper acetylide PH3CuCCCuPH3 as a possible precursor of these (PH3CuC)n (n = 4, 6, 8) hypothetical species. Special emphasis was placed on the comparison of the main properties of these metal-substituted cyclopolyenes with those of the corresponding cyclopolyenes in an attempt to study the effects of metal substituents on the organic C4, C6, and C8 cyclic moieties. We found comparable geometries of the Cn units and, for n = 3, a thermodynamically stable species with respect to dissociation toward dinuclear copper acetylides.