Metal complexes of biologically important ligands, CXX.: Half sandwich complexes of ruthenium(II) and Iridium(III) with R-3-(3-pyridyl)-D-alaninate

The reactions of the chloro bridged complexes [(p-cymene)RuCl2](2) and [(C5Me5)IrCl2](2) with the anion of 3-(3-pyridyl)-D-alanine (L) afford the N,O-chelate complexes (p-cymene)Ru(L)(Cl) (1) and (C5Me5)Ir(L)(Cl) (2). Abstraction of chloride from 1 and 2 using AgSbF6 gives the dimers [(p-cymene)Ru(mu-L)(2)Ru(p-cymene)](2+)(SbF6)(2) (3) and [(C5Me5)Ir(mu-L)(2)Ir(C5Me5)](2+)(SbF6)(2) (4) with coordination of the pyridine N atom. Complex 4 is formed in high diastereomeric excess. The structure of (C5Me5)Ir(mu-L)(2)Ir(C5Me5)]Cl-2 (5) which contains the SIrRCRCRIr diastereoisomer in the crystal was determined by X-ray diffraction.