Charge-transfer interactions between sulfur dioxide and group 8 half-sandwich complexes

Abstract

Mulliken-type charge-transfer complexes have been formed between basic half-sandwich compounds and SO2 when [M(η5-C5R5)(CO)2] (M = Rh or Ir; R5 = Me5, H5 or H4CF3), [Ir(η5-C5H5)(CO)(C2H 4)], and [M(η5-C5H5)(C2H 4)2] (M = Co, Rh or Ir) are isolated in SO2-doped argon matrices at 20 K; the ν(CO) bands of the complexes are shifted to high frequency of those of the precursor molecules and prominent charge-transfer bands are observed; the same species have been detected when the compounds [M (η5-C5Me5) (CO)2] (M = Rh or Ir) are embedded in polyethylene discs and treated with SO2 at 213-298 K; the enthalpy of complexation of [Ir(η5-C5Me5)(CO)2] with SO2 is -13 ± 3 kJ mol-1. © Copyright 1994 by the Royal Society of Chemistry.