A comparison of metallophilic attraction in (X-M-PH3)2 (M = Cu, Ag, Au; X = H, Cl)

Energy partitioning schemes have been used to investigate the metallophilic attraction between gold, silver and copper atoms in model dimers of H-M-PH3 and Cl-M-PH3 type. Attraction between the monomers is found to be largest for M = Au, but the reduction from Au to Ag (Cu) is not more than 10-20% (25-35%). Equilibrium M-M distances, r(e) (M-M), decrease by 0.2-0.3 Angstrom from Au to Cu, and by 0.1-0.2 Angstrom from Cl to H. An analysis of the intermolecular interaction energy shows that at r(e) (M-M) dispersive and non-dispersive components are about equally important for all systems considered. However, the contribution due to metal nd-nd interaction falls drastically from 43% (35%) for Au, over 30% (27%) for Ag, to 18% (13%) for Cu in the H (Cl) compounds.