Structural characterization, electrochemistry, and spectroelectrochemistry of trans-dioxorhenium(V) complex with 4-methoxypyridine, [ReO2(4-MeOpy)4]PF6, and characterization of [ReO2(4-MeOpy)4]2+ generated electrochemically

摘要: Abstract Crystal structure of [ReO2(4-MeOpy)4][PF6] (4-MeOpy = 4-methoxypyridine) complex has been examined by the single crystal X-ray analytical method. This shows a trans-dioxo geometry (average Re–O bond length = 1.766(2) A) and its equatorial plane is occupied four 4-MeOpy molecules Re–N length = 2.156(4) A). Electrochemical reaction [ReO2(4-MeOpy)4]+ in CH3CN solution containing tetra-n-butylammonium perchlorate as supporting electrolyte studied using cyclic voltammetry at 24 °C. Cyclic voltammograms show one redox couple around 0.65 V (Epa) 0.58 V (Epc) [versus ferrocene/ferrocenium ion couple, (Fc/Fc+)]. Potential differences between two peaks (ΔEp) scan rates range from 0.01 to 0.10 V s−1 are 65 mV, which almost consistent with theoretical ΔEp value (59 mV) for reversible electron transfer The ratio anodic peak currents cathodic ones 1.04 ± 0.03 (Epa + Epc)/2 constant, 0.613 ± 0.001 V versus Fc/Fc+, regardless rate. Spectroelectrochemical experiments have also carried out applying potentials 0.40 0.77 V Fc/Fc+ an optically transparent thin layer electrode. It was found that UV–visible absorption spectra clear isosbestic points 228, 276, 384 nm, stoichiometry evaluated 1.03 Nernstian plot. These results indicate oxidized reversibly [ReO2(4-MeOpy)4]2+ complex. Furthermore, it clarified characteristic bands 236, 278, 330, 478, 543 nm their molar coefficients 4.3 × 104, 4.5 × 103, 1.0 × 104, 6.1 × 103 M−1 cm−1 (M = mol dm−3), respectively.