Dinitrogen complexes, of molybdenum and tungsten

Dinitrogen Complexes of Molybdenum and Tungsten that Give Ammonia in Acid... 

Figure 9-4 A summary of the protonation chemistry of dinitrogen complexes of molybdenum and tungsten based on a wide range of chemical, electrochemical, and kinetic researches. Species characteristic of all these stages except MVI have been isolated and characterized. In a typical case M = M(Ph2PCH2CH2PPh2)2, X = Q, and M = Mo or W (redrawn from R. R. Eady and G. J. Leigh, J. Chem. Soc., Dalton Trans. 1994, 2739).

Dinitrogen complexes of molybdenum and tungsten with mono-, di - and tii - tertiary phosphine co -ligands are electrosynthesised from molecular nitrogen andMo or precursors vw cleavage of halide or thiolate bonds and from Mo or oxide, imide or hydrazide complexes by... 

Electrochemical oxidation of closed - shell, teitiary phosphine dinitrogen complexes of molybdenum and tungsten give successively 17- and 16 - electron species. The stability of the electron - deficient species is determined by the rate of loss of dinitrogen removal of electrons... 

Redox potential-structure relationships in metal complexes. Part 2. The influence of trans-substituents upon the redox properties of certain dinitrogen complexes of molybdenum and tungsten and some carbonyl analogues inner-sphere versus outer-sphere electron transfer in the alkylation of co-ordinated dinitrogen J.Chem.Soc. Dalton Trans./ (1980)/ 121-127... 

The discovery that dimtrogen was capable of forming stable complexes with transition metals (Chapter 5) led to extensive investigation of the possibility of fixation via such complexes. An imporiant development was the discovery that certain phosphine complexes of molybdenum and tungsten containing dinitrogen readily yield ammonia... 

Dinitrogen binding and electrochemistry in complexes of molybdenum and tungsten... 

The reactivity of coordinated dinitrogen in mononuclear complexes is still not yet fully understood. The reactive complexes are those at the left-hand end (Groups 4, 5, and 6) of the transition series and the reactions are best developed in the case of complexes of molybdenum and tungsten. The first reaction discovered was an acylation of coordinated nitrogen, but it was quickly recognized that protonation is equally, if not more, facile. " ... 

Properties of Molybdenum and Tungsten Na, NNH, NNHa, and NNH3 Complexes with Diphosphine Co-Ligands Insights into the End-on Terminal Reduction Pathway of Dinitrogen Felix Tuczek... 

An in situ 15N-NMR study of the protonation reactions of molybdenum and tungsten dinitrogen complexes has shown that signals arise in the early stages of the reaction which can be assigned to relatively stable hydrazido(2-) species (4). With careful choice of acid and conditions, thermally stable hydrazido(2-) complexes can be isolated. They often yield ammonia and/or hydrazine upon further protonation (4,105), for example, reaction (43). 

ELECTRONIC STRUCTURE AND SPECTROSCOPIC PROPERTIES OF MOLYBDENUM AND TUNGSTEN N2, NNH, NNH2i AND NNH3 COMPLEXES WITH DIPHOSPHINE CO-LIGANDS INSIGHTS INTO THE END-ON TERMINAL REDUCTION PATHWAY OF DINITROGEN... 

However, this work pre-dated the discovery of protonation of dinitrogen in the molybdenum and tungsten complexes and, once this had come to light, we turned our attention to the behaviour of isocyanides and alkynes at those sites that activated dinitrogen to reduction. For isocyanides, the first step was to bind these ligands in place of dinitrogen in the complexes trflns-[M(N2)2(dppe)2], which was done by a displacement reaction [Equation (23)]. ... 

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