Photoinduced insertion of tungsten into aromatic and aliphatic carbon–hydrogen bonds by bis(η-cyclopentadienyl)tungsten derivatives

Photolysis of solutions of [W(η-C5H5)2H2] in fluorobenzene, o-xylene, anisole, p-chlorotoluene, p-xylene, mesitylene, p-methylanisole, and methyl benzoate gives the compounds [W(η-C5H5)2H(C6H4F-3 and -4)], [W(η-C5H5)2H(C6H3Me2-3,4)], [W(η-C5H5)2H(C6H4OMe-4)], [W(η-C5H5)2Cl(C6H4Me-4)], [W(η-C5H5)2(CH2C6H4Me-4)2], [W(η-C5H5)2(CH2C6H3Me2-3,5)2], [W(η-C5H5)2(CH2C6H4OMe-4)2], and [W(η-C5H5)2H(C6H4CO2Me-3 and -4)] together with [W(η-C5H5)2H(OCOPh)], respectively. Thermal decomposition of [W(η-C5H5)2H(Me)] in mesitylene gives [W(η-C5H5)2H(CH2C6H3Me2-3,5)]. Photolysis of this compound in p-xylene gives [W(η-C5H5)2(CH2C6H4Me-4)(CH2C6H3Me2-3,5)]. Photolysis of [W(η-C5H5)2H2] in tetra-methylsilane gives cis- and trans-[H(η-C5H5)W(σ: η5-C5H4)2W(η-C5H5)(CH2SiMe3)]. The photoinduced reaction between [W(η-C5H5)2H2] and toluene, a toluene–mesitylene mixture, and methyl propionate are also described. The mechanisms of these photoinduced insertions of tungsten into aromatic and aliphatic C–H bonds are discussed.