Tungsten complexes properties

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 properties and reactions of the molybdenum and tungsten complexes [(Tt-Cp)M(CO)2(N CPhBu )] Ci.sely resemble those of the corresponding di-t-butylmethyleneamino-complexes, steric hindrance preventing bridging by the methyleneamino-groups. The complexes react with iodine to form [(jr-Cp)-M(CO)l2(NCPhBu )] as expected however, in contrast to all other such... 

Tungsten, hexahydridotris(diisopropyiphenylphosphine)-structure, 700 Tungsten alkoxides physical properties, 346 synthesis, 339 Tungsten complexes alkoxy carbonyl reactions, 355 alkyl alkoxy reactions, 358 amides... 

Group 4, surface chemistry on oxides, 12, 515 Group 5, surface chemistry on oxides, 12, 524 molybdenum, surface chemistry on oxides, 12, 529 into nickel complexes, 8, 59-60 with palladium, GO insertion, 8, 200 tungsten, surface chemistry on oxides, 12, 531 on zinc compounds, 2, 366 Alkoxido-imido tungsten complexes structure and properties, 5, 754—755 synthesis, 5, 750/... 

Phosphine-imido tungsten complexes structure and properties, 5, 754—755 synthesis, 5, 749... 

The physical and solubility properties of the tungsten complex are similar to those of the molybdenum analog, except that it is less photosensitive. The HNMR spectrum at room temperature (toluene-tig) shows this complex to be stereochemically rigid, but at 60 °C, a binomial quintet is observed at d — 1.72 for the W—H protons ( ph = 31 Hz). 

CYCLOMETALATED ARYLOXY(CHLORO)NEOPENTYLroENE - TUNGSTEN COMPLEXES. SYNTHESES FROM NEOPENTYLIDYNE COMPLEXES AND CATALYTIC PROPERTIES IN OLEFIN METATHESIS... 

Interestingly, this type of cyclometalated complex can be obtained via an other route starting from the Schrock s neopentylidyne complex W(CCMe3)Cl3(dme) (dme = dimethoxyethane) [25, 26]. The purpose of this paper is to report the main features of this new way of synAesis and to give some examples of the catalytic properties of these cyclometalated aryloxy(chloro)neopentylidene-tungsten complexes in olefin metathesis. 

In mechanistic studies, the molybdacyclobutane of a MAP catalyst was found to break up to ethylene/methylidene intermediates 4500 times faster than the corresponding tungstacycle (at 40°C) [19]. Syn and anti proton exchange were also found to be significantly faster (up to lOOx s) for molybdacycles than for tungsta-cycles. Methylidene rotation about the M=C bond was determined to be comparatively slower for molybdenum complexes (<0.2 s ) than for tungsten complexes (3.6-230 s ). Schrock and coworkers proposed that many of these properties contribute to the superior efficiency of the tungsten MAP catalysts relative to their molybdenum counterparts. 

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