A reaction between diphenyltitanocene and phenyl(pentafluorophenyl)acetylene in refluxing benzene produces 1,1-bis(η5-cyclopentadienyl)-2-phenyl-3-(pentafluorophenyl)benzotitanole in 44% yield. Degradation of the product with HCl/CHCl3 affords titanocene dichloride and Z-1,2-diphenyl-1-(pentafluorophenyl)ethene. Reaction of diphenyltitanocene and phenyl(pentafluorophenyl)acetylene in benzene under photolytic conditions results in the exclusive formation of 1,1-bis(η5-cyclopentadienyl)-2,5-diphenyl-3,4-di(pentafluorophenyl)titanole. The latter product can also be obtained in 77% yield from a reaction between titanocene dicarbonyl and phenyl(pentafluorophenyl)acetylene in hexane solution. Application of 13C NMR spectroscopy to the structural elucidation of these and related metallacycles is discussed.
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Acknowledgement is made to the Donors of the Petroleum Research Fund, administered by the American Chemical Society, and to the National Science Foundation for partial support of this research program (M.D.R.).