Reactivity of a binuclear Ru(II) N 2-bridged complex towards phosphines: facile access to novel mono and binuclear phosphorous derivatives. X-ray structural characterization of two unusual binuclear complexes containing ‘pincer’ ligands: [{RuCl 2(η 3-NN′N)} 2(μ-η 2-P 2)] (NN′N=2,6-bis[(dimethylamino)methyl]pyridine; P 2=1,3-bis[(diphenylphosphino)methyl]benzene or 1,3-bis(diphenylphosphino)propane)

Abstract

Treatment of the dinitrogen bridged complex [{RuCl 2(η 3-NN′N)} 2(μ-N 2)] ( 1, NN′N=2,6-bis[(dimethylamino)methyl]pyridine) with a variety of monodentate phosphorous ligands results in the formation of the corresponding mononuclear derivatives [RuCl 2(η 3-NN′N)(PR 3)] (R 3=Ph 3, 2; Ph 2H, 3; Me 3, 4; (OMe) 3, 5). When potentially bidentate bis-phosphines are used, the results are found to be ligand dependent: with one or two equivalents of bis(diphenylphosphino)methane (dppm), the only product observed is the mononuclear derivative [RuCl 2(η 2-NN′N)(η 2-dppm)] ( 6), which contains the diphosphine acting as a chelating ligand. However, the use of bis-phosphines such as 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp) or 1,1′-bis[di( p-tolyl)phosphino]ferrocene (dtpf), results in the formation of binuclear products: [{RuCl 2(η 3-NN′N)} 2(μ-dppe)] ( 7), [{RuCl 2(η 3-NN′N)} 2(μ-dppp)] ( 8) and [(RuCl 2(η 3-NN′N)) 2(μ-dtpf)] ( 9), respectively. In these cases, the phosphine ligands are bridging between two Ru centered moieties. The X-ray structure of complex 8 is reported. Treatment of complex 1 with the potentially terdentate phosphine ligand 1,3-bis[(diphenylphosphino)methyl]benzene (PCHP) affords the binuclear derivative [{RuCl 2(η 3-NN′N)} 2(μ-η 2-PCHP)] ( 10). Compound 10 has been characterized by X-ray diffraction methods and represents the first example in which a Ru complex contains a bridging and noncyclometallated PCHP ‘pincer’ ligand.