Oxo complexes of molybdenum

S6re6 de Roch and co-workers503 have demonstrated an alternative means of activating molecular oxygen in the liquid phase. The principle depends on the lability of an M=0 bond in oxo-molybdenum complexes. Thus, oxo-dialkyl-thiocarbamate complexes of molybdenum catalyze the oxidation of triphenyl-phosphine via the sequence ... 

The aim of this chapter is to summarize the chemistry of octacyano complexes and oxo- and nitridocyano complexes of molybdenum, tungsten, niobium, tantalum, technetium, and rhenium, with special emphasis on structural and kinetic properties. 

There are many compounds and complexes of molybdenum in the V and VI oxidation states in which there are one or more oxygen atoms bound to the molybdenum by multiple bonds that can be represented Mo=0, since they are evidently approximately double bonds. There are also oxo species with either linear or non-linear M—O—M bridges. While there are certain resemblances in this oxo chemistry to that of Cr, and while tungsten also forms some analogous compounds, by far the most extensive chemistry is known for molybdenum. Some important relationships have been summarized above in Fig. 26-C-9. 

All three members of the electron transfer chain [Mo(CO)2(S2C2Me2)]" (n = 0,1, 2) were isolated and characterized. The complexes have trigonal prismatic geometries, and structural, spectral, and electrochemical properties that are consistent with the redox orbital having predominantly sulfur-ligand based character (>80%) behavior consistent also with DFT calculations. Closely related benzene- and 2,4-di-i-butyl-benzene-dithiolene complexes, [Mo(LL )(bdt)2] (L = 0, L = PPha, L = L = PMeR2 (R = Me or Ph)) were obtained by thioether S-dealkylation of appropriate dttd (22) complexes of molybdenum carbonyls and oxo species. 

Several general conclusions may be made regarding synthesis of reduced pterin complexes of molybdenum. The stability of these complexes depends on formation of a Mo=N bond, which, electronically, replaces one of the two Mo=0 groups of the reagent as detailed in Scheme 2.12. Loss of an oxo ligand is facilitated by protonation by the two equivalents of HCl associated with... 

A. Neuhaus, A. Veldkamp, and G. Frenking, Inorg. Chem., 33, 5278 (1994). Oxo and Nitrido Complexes of Molybdenum, Tungsten, Rhenium and Osmium. A Theoretical Study. Theoretical Studies of Inorganic Compounds. IV. 

Gibson V.C., Graham A.J., Ormsby D.L., Ward B.P., White A.J.P., WiUiams D.J. The effect of Br0nsted acids on the stability of oxo-alkoxide and imido-alkoxide complexes of molybdenum. J. Chem. Soc., Dalton Trans. 2002 2597... 

Bishop, M.W., Butler, G., Chatt, J., Dilworth, J.R, and height, G.J. (1979) The reactions of molybdenum oxo complexes with substituted hydrazines Part 5. The preparation of some organodiazenido complexes of molybdenum. /. Chem. Soc., Dalton Trans., 1843-1850. 

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