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) hypothetic al 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 meta l substituents on the organic C-4, C-6, and C-8 cyclic moieties. We fo und comparable geometries of the C-n units and, for n = 3, athermodyna mically stable species with respect to dissociation toward dinuclear c opper acetylides.