(2-Diphenylphosphinoethyl)cyclopentadien complexes of zirconium (IV): synthesis, crystal structure and dynamic behaviour in solutions

The novel [eta(5):eta(1)-(2-diphenylphosphinoethyl)cyclopentadienyl]trichlo rozirconium (IV) 3 has been prepared via (2-diphenylphosphinoethyl)(trimeth ylsilyl)cyclopentadiene 2. The structures of an adduct of 3 with tetrahydro furan (THF) 3b (two crystal modifications) and of an ionic complex derived from 3 and ZrCl4 {[eta(5):eta(1)- (C5H4CH2CH2PPh2)ZrCl](2)(mu - Cl)(3)}(2)[(ZrCl4)(2)(mu - Cl)(2)](2-) 4 have been determined by an X-ray analysis. T he X-ray and NMR data prove the existence of a Zr-P intramolecular coordina tion in 3 both in solid state and in non-solvating media within a broad ran ge of temperatures. In THF solution the flexible equilibrium between adduct s of 3 with one (3b) and two (3c) molecules of THF has been observed by var iable-temperature NMR spectroscopy. The synthetic route to the simplest uns ymmetrically ligated zirconocene (eta(5)-C5H4CH2 CH2PPh2)(eta(5)-C5H5)ZrCl2 5 derived from 3 has also been elaborated. (C) 1998 Elsevier Science Ltd. All rights reserved.