Rhodium complexes of Group 4B ligands

Abstract

The reactions of the hydrides MMe₃H (M = Si, Ge, or Sn) with [Rh(η-C₅H₅)(CO)₂] have been investigated under both photochemical and thermal conditions. The complex [Rh(η-C₅H₅)(CO)(GeMe₃)₂] is formed in highest yield (ca. 50%) photochemically and [Rh(η-C₅H₅)(CO)(SnMe₃)₂](ca. 80%) thermally (80 °C). Under u.v. irradiation, SnMe₃H and [Rh(η-C₅H₅)(CO)₂] afford [Rh(CO)₃(SnMe₃)₃] principally (ca. 30%), whose reactions with PPh₃, P(OMe)₃, and cyclopentadiene have been studied. The complex [Rh(η-C₅H₅)(CO)(SiMe₃)₂] is formed in only trace amounts by either method. Reduction of [Rh(η-C₅H₅)(CO)₂] or [Rh(η-C₅H₅)(CO)I₂] with sodium amalgam gives an air-sensitive solution with properties characteristic of [Rh(η-C₅H₅)(CO)H]^–. Addition of MMe₃X (M = Ge, Sn, or Pb; X = halide) gives [Rh(η-C₅H₅)(CO)(MMe₃)₂](M = Ge or Sn) in fair (20–50%) yield, and [Rh(η-C₅H₅)(CO)(PbMe₃)₂] in trace amounts. Iodine smoothly cleaves [Rh(η-C₅H₅)(CO)(GeMe₃)₂] to afford [Rh(η-C₅H₅)(CO)(GeMe₃)I], whose chemistry is described. The complex [Rh₂(η-C₅H₅)₂(CO)₃] is formed in 32% yield on irradiation of [Rh(η-C₅H₅)(CO)₂], and its reactions with MMe₃H (M = Si, Ge or Sn) and P(OMe)₃ have been investigated.