EARLY-TIME DYNAMICS AND REACTIVITY OF POLYOXOMETALATE EXCITED-STATES - IDENTIFICATION OF A SHORT-LIVED LMCT EXCITED-STATE AND A REACTIVE LONG-LIVED CHARGE-TRANSFER INTERMEDIATE FOLLOWING PICOSECOND FLASH EXCITATION OF [W10O32](4-) IN ACETONITRILE

We report here picosecond flash excitation results on [W10O32](4-), 1, which demonstrate that the initially prepared ligand-to-metal charge-transfer (LMCT) excited state decays within similar to 30 ps to a single intermediate, 2, that persists for > 15 ns. Little or no substrate reaction is derived from the short-lived LMCT excited state. Furthermore, the long-lived intermediate, 2, is not the 1-electron-reduced species [W10O32](5-), 3, or one of its protonated derivatives. This long-lived intermediate, 2, is the primary photoreactant and has substantial charge-transfer character itself. Additionally, 2 and 3 are likely to have similar W-orbital electron density; the principal differences in electronic structure derive from the presence of an oxidized oxygen site in 2 which is lacking in