PHOTOREACTIVITY OF OCTACYANOTUNGSTATE(V) ION IN NONAQUEOUS SOLVENTS

The CTTM photolysis of (TBA)3W(CN)8 has been studied in MeOH, MeCN, DMF and Me2SO. The quantum yields for the photochemical decomposition of W(CN)8(3-) are 0.50 -/+ 0.02, 0.46 -/+ 0.01, 0.42 -/+ 0.02 and 0.29 -/+ 0.03 in MeOH, MeCN, DMF and Me2SO, respectively. The detection of products has proved that photolysis induces a cyano ligand photolabilization in high quantum yield (PHI-CN- 0.33 in Me2SO) concomitant with photoproduction of W(VI) species. The process has been associated with the efficient population of LF excited state via internal conversion from CTTM excited state, leading to photolabilization and followed by inner-sphere redox process between generated reactive W(CN)7(2-) and parent W(CN)8(3-) according to W(CN)7(2-) + W(CN)8(3-) --> (NC)7W(V)-NC-W(V)(CN)7(5-) --> (NC)7W(VI)-NC-W(IV)(CN)7(5-) --> W(CN)7- + W(CN)8(4-), affording W(VI)(CN)7- as the dominant photoproduct.