Transition Metal Nitrosyl Complexes

Abstract

In recent years transition metal nitrosyl compounds have attracted considerable interest. This chapter describes the synthesis of transition metal nitrosyl complexes with particular reference to routes that involve common reagents (for example, NO and NOBF 4 ). Methods for their characterization by spectroscopic and structural techniques are critically reviewed in the chapter. The chapter focuses on the application of 15 N nuclear magnetic resonance (NMR) for distinguishing among linear, bent, and bridging nitrosyls. The bonding in metal nitrosyl complexes is reviewed from a molecular orbital and valence-bond point of view. The chapter discusses the reactions of transition metal nitrosyl complexes. The factors that influence the mode of bonding of nitric oxide are important as part of the more general study of how small molecules bond to, and are activated by, transition metals. Concern over the role of nitrogen oxides in air pollution has stimulated the development of catalysts for the removal of nitrogen oxides from exhaust gases. The synthesis of organonitrogen compounds from nitric oxide and unsaturated organic molecules are reactions, catalyzed by transition metal compounds, provide the opportunity of converting nitric oxide from an unwanted pollutant into a feedstock for the chemical industry. A variety of methods are available to the inorganic chemist for the synthesis of nitrosyl complexes: addition reactions, reductive nitrosylation, use of organonitrosyl reagents, and so on. Extreme modes of bonding are found in mononuclear nitrosyl compounds.