(ARENE)RUTHENIUM(II) COMPLEXES CONTAINING THE MONOPHOSPHINE RP(CH(2)CO(2)ME)(2) OR THE DEPROTONATED UNSYMMETRICAL DIANION [RP(CHCO(2)ME)(CH=C(OME)O)](2-) AS A TRIPODAL CHELATING LIGAND

Reaction of the dichloro compounds [(mes)RUCl(2){eta(1)(P)-RP(CH(2)CO(2)Me)(2)}] (R = iPr (3a), tBu (3b); mes = mesitylene = C(6)H(3)Me(3)-2,4,6) with 2 equiv of AgPF6 affords the dicationic P,O,O'-chelated complexes [(mes)Ru{eta(3)(P,O,O')-RP(CH2C(OMe)=O)(2)}](PF6)(2)(4a,b) which in CH2Cl2, in, the presence of water, undergo partial hydrolysis to give [(mes)Ru{eta(2)(P,O)-RP(CH2C(OMe)=O)(CH(2)CO(2)Me)}{eta(1)(O)-O2PF2}]PF6 (5a,b). Compounds 4a,b react with 2 equiv of KOtBu in tBuOH to yield the neutral complexes [(mes)Ru{eta(3)(P,C,O)-RP(CHCO(2)Me)(CH=C(OMe)O)}] (6a,b) containing both a five-membered phosphino enolate and a three-membered phosphinomethanide ring. A derivative, 7, of the novel tripodal chelating system is formed by insertion of PhNCO into the C-H bond of the phosphino enolate unit of 6b.