A 4-MEMBERED C,O-CHELATE - 2 FAMILIES OF RUTHENIUM ORGANOMETALLICS INCORPORATING N-CENTER-DOT-CENTER-DOT-CENTER-DOT-O HYDROGEN-BONDING

The reaction of mono-Schiff bases of 4-methyl-2,6-diformylphenol and p rimary amines (p-XC(6)H(4)NH(2), X = OMe, Cl, CO(2)Et and NO2) with Ru (PPh(3))(3)Cl-2 in boiling ethanol afforded violet diamagnetic complex es, [Ru(eta(2)-p-XC(6)H(4)L)(PPh(3))(2)(CO)Cl] (eta(2)-p-XC(6)H(4)L = [4-methyl-6-(N-p-Xphenyliminiomethyl) phenolato-C-2,O] incorporating t he unprecedented orthoruthenated phenolate function, which is hydrogen -bonded with the uncoordinated imine nitrogen. These complexes were fo und to react with sodium benzoates (p-ZC(6)H(4)COO, Z = Me, Cl) to gen erate the new aryl complexes of ruthenium, C(6)H(4)L)(PPh(3))(2)(CO)(e ta(2)-p-ZC(6)H(4)COO)]. The spectral (IR, UV-vis and H-1 NMR) features of these two types of complexes and the effect of the X substituent o n electronic and H-1 NMR spectra are scrutinized. The effect of PPh(3) ring currents on the chemical shifts of the metallated ring protons i s semiquantitatively estimated. In these complexes different types of novel intramolecular N...O interaction and the conformational orientat ion of p-XC(6)H(4)L ligands are noted. The redox behaviour of these co mplexes is reported. The E(1/2) values of Ru-III/Ru-II couple correlat e linearly with the Hammett constants (sigma) of X substituent in the halo complexes. A spectro-electrochemical correlation in these complex es is also observed. Copyright (C) 1997 Elsevier Science Ltd.