Molybdenum hydrazido complexes

Hydrazido and organohydrazido ligands are important intermediates in the reduction or utihzation of N2 in biological and chemical systems, and their molybdenum complexes are potential catalysts for aUcene polymerization and metathesis reactions. 

Another synthesis of alkyldiazenido complexes is due to Chatt et al. (1977 b), and independently to the work of Hidai et al. (1976 b), namely a route by condensation of hydrazido(2 —) metal complexes with aldehydes or ketones. The original work of Hidai et al. (1976 a) concentrated on molybdenum complexes, that of Chatt et al. (1977 b) on tungsten, but both groups used the same type of ligands as their starting material complexes, namely [Mo(NNH2)(dppe)2] X (X = F, Cl, Br or I). The... 

Assuming that a mononuclear hydrazido complex is reduced to 2[NH4]", then intermolecular electron transfer from another molybdenum complex is necessary to account for all molybdenum appearing in the product as molybdenum(III). Intermolecular electron transfer can be ruled out. 

The electrocatalytic properties of several parent dinitrogen or hydrazido-containing molybdenum and tungsten complexes with dppe ligand have also been investigated. Each of these complexes yielded NH3, in chemical yields which ranged from 1% to 36% per mole of complex.318... 

The first step of the mechanism leading The electrochemical study of the seven-to the formation of 8 and free nitrite coordinate complex [Mo(N2RR )(dtc)3]+ from the reaction of 7 with O2 probably 9+ (R, R = alkyl or aryl, dtc = 5 2CNMe2) involved a single electron transfer. Sub- provided an example of electrode-induced sequent radical-radical coupling of the activation of a hydrazido(2—) ligand. Corn-products, to afford a molybdenum-bound plex 9+ was shown to reduce in two nitrate, followed by N—O bond cleavage separate diffusion-controlled one-electron would eventually lead to the observed steps, with the first one reversible on the products (Sch. 8) [27]. CV timescale at room temperature and... 

Despite the fact that hydrazido(2—) complexes are in general restricted to the metals molybdenum, tungsten, and rhenium, a great variety of coordination sites (various coligands) have been realized. Four general routes have been employed to yield this class of compounds (143, 275, 317). 

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). 

Molybdenum Nitrosyl Complexes Containing Bridging Hydrazido Groups X-Ray Analysis of the Structure of [(7t-C5H5)Mo(NO)I]2(Ai-NNMe2), W. G. Kita, J. A. McCleverty, B. E. Mann, D. Seddon, G. A. Sim, and D. I. Wood-house, Chem. Commun., 1974, 132. 

How are the hydrazido complexes of molybdenum converted to ammonia First, the stoichiometry of this latter reaction must be reexamined (Equation 29), since it implies N-N bond cleavage to... 

McCleverty, J.A., (1983) Alkoxy, amido, hydrazido and related complexes of molybdenum and tungsten, Chem.SocJiev., 12, 331-60. 

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