Structure and reactivity of transition-metal complexes with polyatomic ligands. Part III. Nitric oxide complexes of cobalt and other transition metals with ν(NO) 1195–1040 cm.–1

Abstract

The red and the black nitrosylpentammines of cobalt, previously considered as having the nitric oxide formally bonded as NO^–, have been reformulated as [(NH₃)₅Co^IIIN₂O₂Co^III(NH₃)₅]⁴⁺(with a trans hyponitrite bridging group and metal–nitrogen bond) and [Co^I(NO)(NH₃)₅]²⁺(with a NO⁺ group), respectively. Similar hyponitrite bridging structures are proposed for the nitrosylpentacyanocobalt anion and for iron and ruthenium nitrosyls. The visible and ultraviolet absorption spectra of the cobalt complexes, and of [Co(NO)(S₂CNEt₂)₂], are discussed.