Tungsten peroxo complexes

Tungsten(VI)-peroxo complexes such as W0(02)2(HMPA)(H20) are also effective reagents for the selective transformation of alkenes to epoxides. cis-Alkenes such as m-2-butene are exclusively converted to cis-epoxides.123... 

The most active d metal peroxo complexes toward nucleophilic substrates, like amines, phosphines, thioethers, double bonds etc., are molybdenum, tungsten and rhenium derivatives vanadium and titanium catalysis is also important, in particular when... 

Mechanistic studies on the behaviour of Mo(VI) peroxo complexes reveal that the anionic peroxospecies of general formula [Mo(02) (OH)(H20), ] are particularly efficacious for the oxidation of secondary alcohols.199 Tungsten(VI)... 

Another well-known but bidentate ion is the peroxo group. Both fluoride and peroxo ions can occupy up to 8 coordination centers at the tungsten ion. Hydrofluoric acid as complexing agent in combination with an oxidizing acid or hydrogen peroxide (which represents both properties) are very important solvents for analytical samples of tungsten metal and several of its compounds. 

Many hydroxylated linalools [including compounds 105, 106, 108, and 110, both (Z)- and ( )-isomers], as well as the epoxides of both furanoid (109) and pyranoid (see section on pyrans) linalyl oxides, have been identified in papaya fruit (Carica papaya). At the same time, the first reported occurrence of die two linalool epoxides (112) in nature was made. These epoxides are well known to be unstable and easily cyclized (see Vol. 2, p. 165) and have been made by careful peracid oxidation of linalool. An interesting new method has now been described. While the vanadium- or titanium-catalyzed epoxidation of geraniol (25) gave the 2,3-epoxide (see above), as does molybdenum-catalyzed epoxidation with hydrogen peroxide, the epoxidation of linalool (28) with molybdenum or tungsten peroxo complexes and hydrogen peroxide led, by reaction on the 6,7-double bond, to 112. ... 

Tungsten(vi) forms afew oxo complexes,e.g., WOF5, W02F , W02C12 and WO3F2" these are not binuclear, but some bent oxo-bridged complex ions are known, e.g., the peroxo species... 

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