Mesitylene Osmium(II) Complexes Containing the Functional Phosphane ^BuP(CH2C 0 2Me)2 and Anionic Species Derived Thereof as Bi- and Tridentate Ligands

Z. Naturforsch. 53 b, 540-544 (1998); received February 26, 1998 Osmium, Halfsandwich Complexes, Chelate Complexes, Phosphanediyldiester The dichloroosmium(II) compound [(mes)OsCl2(L)] (2) with L = fBuP(CH2C02Me)2 reacts with one or two equivalents of AgPFö to give the monoor dicationic complexes 3 and 4 containing the phosphanediyldiester as a bior tridentate chelating ligand. Complex 4 undergoes, in the presence of water, partial hydrolysis to give the difluorophosphatoosmium(II) derivative 5 in quantitative yield. Treatment of 4 with two equivalents of KOfBu affords by deprotonation at both CH2 groups of L the neutral complex 6, in which one PCHC02Me unit of the dianionic ligand |7BuP(CHC02Me)2]2forms a five-membered and the other PCHC02 Me unit a threemembered ring with the metal. The reaction of 6 with water leads selectively to the formation of the chelate complex 7 containing the phosphanediylbis(carboxylate) [/BuP(CH2C0 2 )2]2~ as a tripodal ligand.