Investigation into the metallophilic interaction in coinage-metal halides: an ab initio study of CMX (CM = Cu and Ag, X = F - I).

Investigation of the metallophilic interactions of the title coinage-metal halide series, CMX (CM = Ag and Cu, X = F - I), and their cationic and anionic systems, were performed at CCSD(T) theoretical level with extended basis sets. Natural bond orbital analysis shows that the interactions come mainly from the overlap of the sp hybrid on the halogen and the spd hybrid on the coinage-metal atom. Electron density deformation analysis demonstrates a pronounced electron accumulation in the interaction region between the heavier X and the coinage-metal atoms, and suggests a covalent character of the interaction. Positive Laplacian values and negative total energy densities at bond critical points (BCPs) show the "intermediate" character of the interactions. Reduced density gradient analysis visualizes the interaction; a linear relationship between energy densities and eigenvalues can be found at BCPs.