HEMILABILE PROPERTIES OF THE ETA(3)-DIPHENYLVINYLPHOSPHINE (DPVP) PHOSPHAALLYL LIGAND - SYNTHESIS AND REACTIONS OF [(ETA(5)-C5ME5)RU(ETA(3)-DPVP)(ETA(1)-DPVP)]PF6

Pentamethylcyclopentadienyl-ruthenium(II) half-sandwich complexes cont aining the olefinic phosphine ligand diphenylvinylphosphine (DPVP) are described. The hemilabile properties of the eta(3)-DPVP ligand, a neu tral monametallic phosphaallyl, are illustrated by reactions with carb on monoxide and terminal acetylenes. DPVP reacts with [(eta(5)-C5Me5)- RuCl2](2) to give the disubstituted ruthenium(II) compound [(eta(5)-C5 Me5)Ru(eta(3)-DPVP)(eta(1)-DPVP)]-PF6 (1). 1 reacts with NaNCS to form [(eta(5)-C5Me5)Ru(eta(1)-DPVP)(2)(NCS)] (2), 1 reacts with CO, HC=CPh , HC=CCH2CH2OH, and HC=CCH2OH to form [(eta(5)-C5Me5)Ru(eta(1)-DPVP)(2 )(CO)]PF6 (3), [(eta(5)-C5Me5)Ru(eta(1)-DPVP)(2){C=C(H)(Ph)}]PF6 (4), [(eta(5)-C5Me5)Ru(eta(1)-DPVP)(2){C(CH2)(3)O}]PF6 (5), and eta(5)-C5Me 5)Ru(eta(1)-DPVP)(2){C=C(H)(CH2OH)}]PF6 (6), respectively, 6 slowly de cemposes in aerated solutions to form 3, presumably through an allenyl idene intermediate, 6 reacts with excess DPVP and HPF6 to form the nov el, P,P-diphenyltrihydrophospholonium vinylidene compound e5)Ru(eta(1) -DPVP)(2){C=C(CH2)(2)PPh2CH2}][PF6](2) (7). The characteristic H-1, C- 13{H-1}, and P-31{H-1} spectroscopic features of all compounds are des cribed. The molecular structures of compounds 1, 4, 5, and 7 have been determined by single crystal X-ray crystallography.