Inter- and intra-molecular ligand-exchange and -rearrangement reactions of tetra-azadiene complexes of nickel, platinum, and cobalt

Abstract

Tetra-azadiene-exchange and -rearrangement reactions have been observed for both [Ni(R₂N₄)₂] and [Ni(R₂N₄)(η⁵-C₅H₅)](R₂= 1,4-diaryl) complexes. The reactions of [Ni(R₂N₄)₂] or [Co(R₂N₄)(η⁵-C₅H₅)] with aryl azides lead to substitution of the tetra-azadiene ligands. Reactions of [Pt(R₂N₄)(cod)] or [Ni(R₂N₄)(η⁵-C₅H₅)] with aryl azides R′N₃ produced platinum and nickel complexes with non-symmetrical RN₄R′ ligands. All products arising from these reactions were identified by field desorption mass spectrometry and/or h.p.l.c. Four mechanisms which can account for the nature of the observed products, the product distributions, and reaction times are discussed. Transient aryl-nitrene species are proposed as key intermediates in these reactions.