A STUDY OF PHOTOCHROMIC TUNGSTATES AND PHOTOREACTIVE PALLADIUM COMPLEXES

The photochemistry of certain palladium complexes and the structure of photochromic tungstate glasses have been studied.;Trans PdL(,2)X(,2) complexes (where L = PPh(,3) and PMePh(,2), and X = Cl('-) and Br('-)) undergo trans to cis photoisomerization when irradiated at 405 and 366 nm. The quantum yields are between 10('-1) and 10('-2) and vary with the solvent polarity. A kinetic analysis shows that the reverse photoisomerization reactions can also be photoinduced. The luminescence spectrum and the possible mechanisms of the photoisomerization are discussed.;Raman and luminescence spectroscopy were used to study the structure of alkali borate tungstate glasses (M(,2)O(.)(B(,2)O(,3))(,2)(.)xWO(,3) M = Li, Na 0 < x < 1). Raman scattering results showed the dominant tungstate species in these photochromic glasses to be tetrahedral WO(,4)('=). At high concentrations of WO(,3), WO(,3)(.)H(,2)O and W(,2)O(,7)('=) are also present. These species are thought to contain octahedral tungstate. Luminescence measurements provided evidence for an octahedral WO(,3) structure not identified by the Raman. The results also revealed a possible change in borate structure similar to that found in pure alkali borate glasses and termed the "borate anomoly".;PdL(,2)O(,2) complexes (where L = PPh(,3) and PMePh(,2)) are photochemically active in aryl halide or alkyl halide solutions with added L. When irradiated with 405 or 366 um light, the PdL(,2)O(,2) reacts to produce PPh(,3)O, and (trans)PdL(,2)X(,2) (where X = Cl, Br, I) in alkyl halide solutions, while in aryl halide solutions PdL(,2)X(,2) and PPh(,4)X are produced. The quantum yields in alkyl halide solutions are about .5. Mechanisms for the reactions are discussed.