Carbonyl-Carboxylato-Ruthenium Complexes Incorporating Diimine Ligands and Unexpected Cyclometalation of Carboxylate Ligands

We report two new synthetic routes to the dinuclear Ru(I) complexes, [Ru-2(1)(RCO2)(CO)(4)((NN)-N-boolean AND)(2)](+) ((NN)-N-boolean AND = 2,2'-bipyridine or 1,10-phenanthroline derivatives) that use RuCl(3)(.)3H(2)O as a starting material. Direct addition of the bidentate diimine ligand to a methanolic solution of [Ru(CO)(2)Cl-2](n) and sodium acetate yielded a mixture of [Ri(2)(1)(MeCO2)(CO)(4)((NN)-N-boolean AND)(2)](+) ((NN)-N-boolean AND = 4,4'-dmbpy, and 5,6-dmphen), and [Ru-II(MeCO2)(2)(CO)(2)((NN)-N-boolean AND)] ((NN)-N-boolean AND = 4,4'-dmbpy and 5,5'-dmbpy). Single-crystal X-ray studies confirmed that the Ru(II) complexes had a trans-acetate-cis-carbonyl arrangement of the ligands. In contrast, the use of sodium benzoate resulted in the unexpected formation of a Ru-C bond producing ortho-cyclometalated complexes, [Ru-II(O2CC6H4)(CO)(2)((NN)-N-boolean AND)], where (NN)-N-boolean AND = bpy or phen. A second approach used ligand exchange between a bidentate ligand ((NN)-N-boolean AND) and the pyridine ligands of [Ru-I(RCO2)(CO)(2)(py)](2) to convert these neutral complexes into [Ru-2(1)(RCO2)(CO)(4)((NN)-N-boolean AND)(2)](+). This method, although it involved more steps, was applicable for a wider variety of diimine ligands (R = Me and (NN)-N-boolean AND = 4,4'-dmbpy, 5,5'-dmbpy, 5,6-dmphen; R = Ph and (NN)-N-boolean AND = bpy, phen, 5,6-dmphen).