Optically active transition metal complexes .108. Synthesis, crystal structure and properties of a novel ''quasi-meso'' dinuclear eta(6)-benzene-ruthenium(II) complex with chiral salicylaldiminato ligands

The chloride ligand in the diastereomer mixture (R(Ru),S-C)- and (S-Ru,S-C)-[(eta(6)-C6H6)Ru(LL*)Cl], 1a and 1b (ratio 86:14), was abstracted in acetone at - 30 to - 40 degrees C by AgPF6[HLL* = (S)-(1-phenylethyl)salicylaldimine]. X-ray analysis of crystals of the product [(eta(6)-C6H6)Ru(LL*)](2)(PF6)(2) . 2CO(CH3)(2) 3 shows a dimeric structure with opposite ruthenium configurations. Therefore, the dimer containing two salicylaldiminato ligands with the same chirality can be described as a ''quasi-meso'' stereoisomer. The complex is supposed to be formed from the solvate complexes with coordinated acetone during crystallisation. This assumption is in accord with the reactivity of 3 towards water in acetone, A conformational analysis based on the NMR spectroscopic results shows that the arrangement of the 1-phenylethyl groups relative to the [(eta(6)-C6H6)Ru(LL*)] fragments is determined by the face-on orientation of the phenyl substituent with respect to the pi-bonded benzene ligands.