Pulse radiolytic studies on cis-dichlorobis(1,10-phenanthroline-5,6-dione)Cobalt(III) complex

摘要

Reactions of four reducing radical species namely $e^{-}_{ ext{aq}}$, H-atoms, (CH3)$_{2}^{ullet}$COH and $^{ullet}$CO$^-_2$ radicals with [Co(III)(phendione)2Cl2]Cl (complex) have been studied by electron pulse radiolysis. Time resolved transient absorption spectra for all the four species show two peaks which match with those of phendione anion radical produced by the reaction of e$^{-}_{ ext{aq}}$ with phendione. However, there are some differences in the spectral and kinetic features in the reactions of H-atoms and $^{ullet}CO^{-}_{2}$ radicals with the complex which are elaborated. Steady state absorption spectra on irradiation under reducing conditions indicate breakdown of the complex. The anion radical initially produced has fairly long lifetime of few 100 microseconds. Spectral studies show that initial site of attack for electron transfer is the phendione moiety. Subsequently the electron is transferred to other sites resulting in aquation/decomposition to metal ion. Conductometric studies show that conductance substantially increases on irradiation and could be attributed to aquation/de-ligation of the complex by intramolecular electron transfer.