POLYAZOLYL CHELATE CHEMISTRY .3. (SIGMA-ORGANYL)(TRIS(PYRAZOL-1-YL)BORATO)RUTHENIUM COMPLEXES

The reactions of K[HB(pz)3] (pz = pyrazol-1-yl) with the coordinatively unsaturated sigma-vinyl complexes [Ru(CR = CHR)Cl(CO)(PPh3)2] (R = H, Me, C6H5) proceed with loss of a chloride and a phosphine ligand to provide the compounds [Ru(CR = CHR)(CO)(PPh3){HB(pz)3}] in high yield. Similar treatment of the complex [Ru(C6H4Me-4)Cl(CO)(PPh3)2] leads to the related sigma-aryl derivative [Ru(C6H4Me-4)(CO)-(PPh3){HB(pz)3}]. The alpha-(phenylethynyl)-trans-beta-styryl complex [Ru{C(C = CPh) = CHPh}(CO)(PPh3)-{HB(pz)3}] is obtained in high yield via the successive treatment of [RuClH(CO)(PPh3)3] with 1,4-diphenyl-1,3-butadiyne and K[HB(pz)3]. The molecular structure of [Ru{C(C = CPh) = CHPh{(CO)-(PPh3){HB(pz)3}], described as pseudooctahedral with two enantiomeric forms in the asymmetric unit. The vinyl ligand is almost coplanar with the carbonyl ligand aligned in such a way as to maximize pi-retrodative interactions.