SPECTROPHOTOMETRIC STUDIES OF THE PHOTOLYSIS OF DIAZIDO BIS(PHOSPHINE) METAL(II) COMPLEXES

The photolysis of mixed ligand complexes of the type ML(n)(N3)2 (M=Ni, Pd, Pt; L=phosphane and diphosphane ligands, respectively; n=1, 2) wa s monitored by electronic spectroscopy in absorption, emission and exc itation. Initial quantum yields of these complexes were measured in CH 2Cl2 and EtOH in dependence on the irradiation wavelength. Photochemic ally formed M0I(n) fragments of Pd and Pt are distinguished by an inte nsive emission detected at 77 K. No emission was observed with respect to the appropriate Ni0 fragments. An initial emission at 615 nm detec ted by irradiating Pd(PPh3)2(N3), at 77 K is explained by assuming a p hotochemical cis/trans isomerization. Quenching experiments have been performed by using Ru(bpy)3Cl2, Os(bpy)3Cl2, Re(CO)3(phen)Cl and Cr(bp y)3(ClO4)3 as sensitizers and the mixed-ligand complexes under discuss ion as quenchers.