Tungsten iv Complexes

Molybdenum(i ) and Tungsten(iv) Complexes.—An absorption maximum in the electonic spectrum of WOCI2 at 345 nm has been assigned to and 

A new synthesis of olefins by the reductive deoxygenation of vicinal diols using tungsten(iv) compounds, e.g. K2[WCl6], has been described. The process appears to be the reverse of the reaction of OsO with olefins and to involve transition state (90) since, in corresponding reactions, M0CI4 only forms 

Andruchow, jun. and J. DiLiddo, Inorg. Nuclear Chem. Letters. 1972, 8, 689. 

Bartecki, M. Cieslak, and S. Weglowski, J. Less-Common Metals, 1972, 26, 411. 

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Reaction of the tungsten(IV) complex [W(NPh) o-(Me3SiN)2C6H4 (py)2l with two equivalents of thiophene gave the 5,C-chelated species [W (NPh) o-(Me3SiN)2C6H4 (SC4H4)l (38). 

The reactions of the molybdenum(IV) and tungsten(IV) complexes with cyanide ions proceed via the same scheme as those of other mono-dentate ligands (see Scheme 3) with the formation of the pentacyano complex (155,156). This very fast reaction is followed by a much slower reaction with the production of the octacyano complex in the presence of an excess of cyanide ions. 

The oxocyano tungsten(IV) complex (PPh4)2[WO(CN)3(ensal)] (ensal = A-salicylideneethylene-diaminonato) resulted from reaction between K3Na[W(CN)302] 6H20, salicylaldehyde and ethyl-enediamine.158... 

Extension of these WL4 complexes to complexes not involving 8-quinolinol derivatives has included a number of substituted tetrakis-(picolinato)tungsten (IV) complexes (2, where Z = H, CH3, or C2H5 and the analogous 3-hydroxypicolinato complex) (3). Other species reported previously include the 2-pyrazinecarboxylato and 1-isoquino-linecarboxylato species, W(pzc)4 (3) and W(iqc)4 (4) (3), and the spectrally supported W(nq)4 and W(hqa)4 (2). Complexes not previously reported include W(tbq) 4 and the quadridentate Schiff base chelate W(dsp)2 (5 ), for which at least two isomers have been observed. 

Dichloroiodo)benzene is commonly used as a reagent for the chlorination or oxidation of various transition metal complexes. Numerous examples of oxidative chlorination of various molybdenum and tungsten complexes with PhICl2 have been reported in the literature [67-74]. In a representative example, oxidative decarbonylation of the cyclopentadienyl complexes 83 with one equivalent of PhICh selectively yields the respective molybdenum(IV) or tungsten(IV) complexes 84 in excellent yields (Scheme 3.31) [73]. 

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