Matrix isolated copper and silver halide clusters

Abstract

Infrared absorption spectra are reported for matrix isolated (CuCl)_n, (CuBr)_n, (AgCl)_n, (AgBr)_n and for mixed clusters with composition Cu_nCl_mBr_n–m. Silver halide clusters with n=1 to 3 are already present in the vapor in equilibrium with the melt. The monomer and dimer forms of the copper halides could be produced only by using a two‐stage oven to partially dissociate the predominant trimer. The stable configurations and corresponding infrared active vibrational frequencies are calculated and compared with experiment. By means of this comparison we come to the following tentative conclusions concerning the structure of these clusters: The silver dimers appear to be rhombic with an X–M–X angle differing considerably from 90°. Both the Cu and the Ag halide trimers are deformed six‐rings. The Cu halide tetramer appears to be an eight‐ring, not a cube. Larger clusters, (MX)_6,7,8, formed within the matrix at high halide to argon concentrations also appear to have planar structures.