Oligomerization of the PH3CuC=CCuPH3 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 PH3CuC=CCuPH3 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 or these metal-substituted cyclopolyenes with those of the corresponding cyclopolyenes in an attempt to study the effects of metal substituents on the organic C-4, C-6, and C-8 cyclic moieties. We found comparable geometries of the C-n units and, for n = 3, athermodynamically stable species with respect to dissociation toward dinuclear copper acetylides.