On the mechanism of formation and spectral properties of radical anions generated by the reduction of –[ReI(CO)3(5-nitro-1,10-phenanthroline)]+ and –[ReI(CO)3(3,4,7,8-tetramethyl-1,10-phenanthroline)]+ pendants in poly-4-vinylpyridine polymers

The electrochemical reduction in aprotic media of –[ReI(CO)3L]+ pendants in poly-4-vinylpyridine polymers is compared to that of [ReI(CO)3L]+ complexes (L = 5-nitro-1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phenanthroline). The UV–Vis absorption spectra of the reduced radical anions of 5-nitro-1,10-phenanthroline (NO2-phen) and 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) were obtained by spectro-electrochemistry of [ReI(CO)3(NO2-phen)(CH3CN)]+ and [ReI(CO)3(tmphen)(CH3CN)]+, respectively. Similar spectra were obtained for the radical anions NO2--phen and tmphen− after pulse radiolysis experiments with –[ReI(CO)3L]+-containing polymers. The analysis of the time-resolved difference spectra was performed using “multivariate curve resolution” (MCR) techniques. Unlike esolv-, CH2OH radicals were unable to reduce tmphen ligands. The reaction of esolv- and/or CH2OH with –[ReI(CO)3(NO2-phen)]+-containing polymers generates –[ReI(CO)3(NO2--phen)] pendants which after disproportionation give rise to products with λmax = 380 nm. The kinetic behavior of –[ReI(CO)3(NO2--phen)] pendants under different experimental conditions is discussed.

Graphical abstractThe electrochemical reduction in aprotic media of-[ReI(CO)3L]+ pendants in poly-4-vinylpyridine polymers is compared to that of [ReI(CO)3L]+ complexes (L= 5-nitro-1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phenanthroline). The reaction of esolv- and/or CH2OHCH2OH with -[ReI(CO)3(NO2-phen)]+ReI(CO)3(NO2-phen)]+ -containing polymers generates -[ReI(CO)3(NO2--phen)] pendants which after disproportionation give rise to products with λmax=380nm. The kinetic behavior of -[ReI(CO)3(NO2--phen)] pendants under different experimental conditions is discussed.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Electrochemical reduction in aprotic media of –[ReI(CO)3L]+ pendants in poly-4-vinylpyridine polymers. ► Pulse radiolysis of –[ReI(CO)3L]+ pendants in poly-4-vinylpyridine polymers. ► Reduced radical anions formed by reaction with solvated electrons and CH2OH radicals. Azodioxy phenanthroline based Re-products.