Production and reactions of triplet CS: matrix infrared and ultraviolet spectra of C2S2

Abstract

Matrix infrared and visible-ultraviolet absorption spectroscopy and ab initio electronic structure calculations have been used to characterize the reaction products from a Tesla coil Ar/CS{sub 2} discharge. The discharge is an excellent source of CS, which reacts with other molecules to form the major C{sub 3}S{sub 2} product and the transient C{sub 2}S{sub 2} species. The spectra of discharged mixed isotopic samples Ar/{sup 12}CS{sub 2}/{sub 13}CS{sub 2} and Ar/C{sup 32}S{sub 2} exhibit triplet patterns in the CS antisymmetric stretching region, which unambiguously identifies the new C{sub 2}S{sub 2} molecule with two equivalent CS subgroups. The magnitudes of the {sup 12,13}C and {sup 32,34}S isotopic shifts further characterize the diatomic CS subgroup nature of C{sub 2}S{sub 2}. Another product contains two equivalent CS subgroups interacting with inequivalent S atom(s). The formation of C{sub 2}S{sub 2}({sup 3}{Sigma}) from the simple CS{sub 2} discharge requires triplet CS. Evidence was also obtained for other transient cumulene species. 32 refs., 8 figs., 7 tabs.