Some new chain-like terdentate phosphines, their ruthenium(II) coordination chemistry and the activity of the cations [Ru(MeCN)3(PhP{CH2CH2P(p-X-C6H4)2}2)]2+ (X = H, F, Me and OMe) as acetalization catalysts

The new chain-like tritertiary phosphines PhP{CH2CH2P(p-X-C6H4)(2)}(2), (X = F, Me and OMe), phetpX, were prepared and characterized. These ligands react with cis-[RuCl2(DMSO)(4)] giving equilibrium mixtures of the eclipsed (ec) and staggered (st) isomers of the dinuclear complexes [Ru-2(mu-Cl)(3)(phetpX)(2)]Cl. The preparation and characterization of the tritertiary phosphines MesP{CH2CH2P(p-X-C6H4)(2)}(2) (Mes = mesityl, X = H and Fl, mesetpX, is also reported. They react with cis-[RuCl2(DMSO)(4)] giving equilibrium mixtures of corresponding uninuclear, [RuCl2(mesetpX)], and dinuclear species, st-[Ru-2(mu-Cl)(3)(mesetpX)(2)]Cl, whose molecularities were established by determining their diffusion coefficients. The dissociation of st -[Ru-2(mu-Cl)(3)(mesetph)(2)]Cl to [RuCl2(mesetph)] (K = 1.8 x 10(-2) mol(-1)) is endothermic (Delta H = 32 kJ mol(-1)) and favored by entropy (Delta S = 75 J mol(-1)). The complexes 'RuCl2(pp(2))' (pp(2) = phetph, and mesetph) react with CO giving fac-[RuCl2(CO)(pp(2))] and fac-[RuCl(CO)(2)(pp(2))]Cl as kinetic products. These complexes slowly rearrange to the thermodynamically stable products mer-[RuCl2(CO)(pp(2))]. The complexes st-[Ru-2(mu-Cl)(3)(phetpX)(2)]Cl react with four equivalents of AgCF3SO3 in MeCN giving the corresponding salts [Ru(MeCN)(3)(phetpX)](CF3SO3)(2). Their activities as catalysts for the acetalization of cyclo-hexanone with 1,2-dihydroxyethane and the trans-acetalization of cyclo-hexanone with 2,2-dimethyl-1,3-dioxolane are described. (C) 1999 Elsevier Science S.A. All rights reserved.