TETRAPHENYLZIRCONACYCLOPENTADIENE DERIVATIVES AS SYNTHONS FOR TETRAPHENYLTHIOPHENE-MONOXIDE AND SUBSTITUTED GERMOLES

Improved syntheses for the five-membered heterocycles 2,3,4,5-tetraphenylthiophene-1-monoxide (1), 1,1-dichloro-2,3,4,5-tetraphenylgermole (3) and 1,1-dimethyl-2,3,4,5-tetraphenylgermole (4) are reported. They make use of bis(eta5-cyclopentadienyl)-2,3,4,5-tetraphenyl-1-zirconacyclopentadiene (2), easily prepared in a one-step reaction from Cp2ZrCl2, (n)BuLi and diphenylethyne. Further reaction of 2 with SOCl2, GeCl4 or Me2GeCl2 yields the desired products and allows recovery Of CP2ZrCl2. Crystal structure analyses of 1 and 4 demonstrate folded five-membered rings with a diene system. Starting from 3 the following derivatives have been synthesized: Ph4C4Ge(C=CR)2 (R = H, (t)Bu, Ph), Ph4C4GeCl[FeCp(CO)2] (10) and Ph4C4GeCl[WCp(CO)3]. Moreover spectral data (IR, H-1 NMR, C-13 NMR) of all compounds and the crystal structure of 10 are reported.