Chemistry of a New Family of Carboxyl-Chelated Ruthenium and Osmium Aryls Incorporating the Imine−Phenol Motif

The reaction of carbonylhalo[4-methyl-6-(NR-iminiomethyl)phenolato- C 2, O ]bis(triphenylphosphine)metal(II), M II (η 2 -RL)(PPh 3 ) 2 (CO)X (M = Ru, Os; X = Cl, Br; R = Ph, p-MeC 6 H 4 ), 1, with sodium carboxylates has afforded carbonyl(carboxylato)[4-methyl-6-(NR-iminomethyl)phenol- C 2 ]bis(triphenylphosphine)metal(II), M II (η 1 -RL)(PPh 3 ) 2 (CO)(η 2 -R‘CO 2 ) (R‘ = Me, Ph), 2 . The reaction is believed to proceed via initial associative cis attack on halide by carboxylate. The reaction 2 → 1 occurs upon treatment of 2 with excess halide. Spectral (UV−vis, IR, 1 H NMR) and electrochemical (metal redox) data for 2 are reported. Structure determination of Ru(η 1 -MeC 6 H 4 L)(PPh 3 ) 2 (CO)(η 2 -MeCO 2 ) and Ru(η 1 -MeC 6 H 4 L)(PPh 3 ) 2 (CO)(η 2 -PhCO 2 )·C 6 H 6 has revealed trans (PPh 3 ) 2 geometry, the MeC 6 H 4 L ligand being bonded via an aromatic carbon atom lying cis to the CO molecule. In the H-bonded phenol−imine function the bond parameters for the acetate complex are as follows: O1−H, 1.14(3) Å; N···H, 1.52(3) Å; O1···N, 2.592(10) Å; O1−H···N, 156(1)°. In the 1 → 2 interconversion, iminium−phenolate to imine−phenol tautomerization and a sterically controlled change in rotational conformation are involved.