US EPA

8704852 

Journal Article 

Photochemistry of methyl- and n1-benzyl-n5-cyclopentadienyltricarbonyltungstein(II) 

Severson, RG; Wojcicki, A 

1978 

Yes 

Journal of Organometallic Chemistry
ISSN: 0022-328X
EISSN: 1872-8561 

157 

2 

173-185 

English 

10.1016/S0022-328X(00)92286-1 

Irradiation of solutions of n5-C5H5W(CO)3R (R CH3n1-CH2C6H5) in cyclohexane at ca. 310490 nm leads to the formation of [n5-C5H5W(CO)3]2 and methane and of n5-C5H5W5(CO)2(n3-CH2C6H5) and some [n5-C5H5W(CO)3]2, respectively. When the irradiation is carried out in the presence of excess P(C6H5)3, the photoproducts are n5-C5H5W(CO)2[P(C6H5)3]CH3 (R CH3) and n5-C5H5W(CO)2(n3-CH2C6H5) and trace [n5-C5H5W(CO)3]2 (R n1-CH2C6H5). Photolysis of the n5-C5H5W(CO)3R in the presence of benzyl chloride affords n5-C5H5W(CO)3Cl (R CH3) and both n5-C5H5W(CO)2(n3-CH2C2H5) and n5-C5H5W(CO)3Cl (R n1-CH2C6H5), the relative amounts of the latter products depending on the quantity of added C6H5CH2Cl. Irradiation of n5-C5H5W(CO)3-CH3 in the presence of both P(C6h5)3 and C6H5CH2Cl affords n5-C5H5W(CO)2-[P(C6H5)3]CH3, but no n5-C5H5W(CO)3Cl. It is proposed that the primary photo-reaction in these transformations is dissociation of a CO group from n5-C5H5W-(CO)3R to generate n5-C5H5W(CO)2R, which can either combine with L to form a stable 18 electron complex, n5-C5H5W(CO)2(L)R (L CO, P(C5H5)3; LR n3-CH2C6H5), or lose the group R in a competing, apparently slower step. This proposal receives support from the observation that, light intensifies being equal, n5-C5H5W(CO)3CH3 undergoes a considerably faster photoconversion to [n5-C5H5W(CO)3]2 under argon than under carbon monoxide. 1978.