Tungsten complexes carbonyl

Chromium and tungsten carbonyl complexes with 2-phenyl- (L) and 2-methylbenzo-l,3-tell-urazole (L ) were prepared in an argon atmosphere as follows. Cr(CO)6 (0.660 g, 3 mmol) or W(CO)6 (1.05g, 3 mmol) in 100 mL of dried THF saturated with argon was exposed to a mercury lamp until the evolution of 3 mmol of CO. After irradiation, the corresponding benzotellurazole (3 mmol) was added to the solution, and the mixture was stirred for 1 hr. The solution was filtered off, and the solvent was removed in a rotary evaporator. The solid residue was placed in a sublimation apparatus to remove unreacted metal carbonyl in a high vacuum and then recrystallized twice from hexane. 

Base-free alkyl-substituted germyl(germylene)tungsten carbonyl complexes 37 and 38 were synthesized by the photolysis of digermyl complexes of tungsten 39 and 40 in benzene (equation 38). These complexes are formed by the 1,2-germyl migrations after the initial photodissociation of CO from 39 and 40146. 

Tungsten carbonyl complexes are also effective catalysts, showing some preference for nucleophile addition at the more hindered position of an unsymmetrical allyl ligand (equations 69 and 70). Other allylic alkylation reactions... 

The rearrangement of a tungsten carbonyl-complexed 7-phosphanorbomadiene to its 7-phosphatricyclo[3.2.0 ]hept-2-ene complex has been analysed by ab initio MO calculations, and it has been shown that the reactions of molybdenum and tungsten metallates of the type [CpM(CO)2CNR] with methyl iodide yield methyl complexes of the composition [CpM(CO)2(CNR)], which subsequently rearrange to / -iminoacyls and / -l-azaallyls depending on the nature of the metal, the isocyanide R substituent, and the solvent used. ... 

Benzenetellurolates reacted with molybdenum and tungsten carbonyl complexes. 

Typical trends have been observed in two-bond C-P couplings measured by Sanchez et for two series of the new molybdenum and tungsten carbonyl complexes [M(CO)4(o-Ph2PC6H4-CH=NR)] (M = Mo, W R = Aik), the trans couplings ca. 35 Hz) being significantly larger than the cis ones (3-9 Hz). 

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