Tungsten cyano complexes

By way of example, we can focus on the cyano complexes. Palladium and platinum can form homoleptic complexes with two, four, or six cyanides, depending on the metal oxidation state zero, two, and four, respectively. Rhenium forms heptacyano complexes in its - -3 and -t-4 oxidation states but forms an octacyano complex in its -t-5 state. Molybdenum and tungsten also appear commonly in octacyano complexes for +4 and - -5 oxidation states, and heptacyano analogs for the - -2 and - -3 cases, with only one occurrence of [Mo(CN)6]" anions in two oxidation states (n = 3, 4). Similar situations can be found with phosphine or carbonyl complexes. For instance, the group... 

The [M(CN)3(0)(bipy)] anions, M = Mo or W, are formed from the respective [M(CN)g] anions plus 2,2 -bipyridyl by photoaquation of cyanide followed by thermal substitution by the bipy. [M(0)(CN)5] intermediates were characterized as their Cs" " salts the tungsten product was characterized by X-ray crystal-structure determination. An investigation of the analogous [W(CN)g] plus 1,10-phenanthroline photoreaction over a wide pH range suggested the intermediacy of [HW(CN)7(OH2)] (presumably [W(CN)6(CNH)(OH2)] -) in acid, [W(CN)7(OH)] - in base, prior to the formation of the penta- and tri-cyano complexes analogous to those characterized in the bipyridyl systems just mentioned. 

Tungsten halides, halogeno and 0x0 complexes, as well as cluster compounds are obtained by reaction with halides. W can also form carbonyl, tertiary phosphine, cyano, and dinitrogen complexes. 

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