Derivatives of tricarbonylmetallates(– III ) of cobalt, rhodium, and iridium

Reduction of [Co(CO)4]– or [M(CO)3]4(M = Rh and Ir) with sodium in liquid ammonia, naphthalene–tetrahydrofuran, or hexamethylphosphoramide (only M = Rh and Ir) gives pyrophoric substances which provide the first main group 4 derivatives of [M(CO)3]3–(M = Co, Rh, and Ir) in 20–90% yields.