NEW SYNTHETIC ROUTE TO MONOCARBONYL POLYPYRIDYL COMPLEXES OF RUTHENIUM - THEIR STEREOCHEMISTRY AND REACTIVITY

A new photochemical synthetic route to species of the type [Ru(terpy)( pp)(CO)](2+) has been elaborated [terpy = 2,2': 6',2 ''-tetrapyridine; pp = a bidentate alpha,alpha'-diimine ligand such as 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), 4,4'-dimethyl-2,2'-bipyridine (dmbp y) or 4-(2-methylpropyl)-2,2'-bipyridine (mpbpy)]. For the species [Ru (terpy)(mpbpy)(CO)](2+) containing the new unsymmetrically substituted ligand (mpbpy) the two possible geometric isomers were separated by c ation-exchange chromatography. The carbonyl groups can readily be remo ved and the vacant site substituted with pyridine, triphenylphosphine and chloride, with retention of the stereochemistry at the metal centr e. By the correct choice of monodentate ligand at the sixth co-ordinat ion site, the MLCT absorption maximum in the electronic spectra can be shifted by up to 150 nm, and the Rum-Run redox couple by over 1 V.