Synthesis and Characterization of a New Cobaloxime-Terpyridine Compound

Abstract

Abstract:A new cobaloxime was synthesized by the reaction of cobalt chloride and diphenylglyoxime in methanol, followed by the addition of 4 -(4-pyridyl)-2,2 :6 ,2 -terpyridine, pytpy. This complex was characterized by UV-Vis spectroscopy, 1 H-NMR spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction analysis. In cyclic voltammetry experiments an irreversible reduction wave assigned to Co(III)/Co(II) at Ecp = −0.31 V vs. Ag/AgCl and a quasi-reversible process assigned to the Co(II)/Co(I) reduction at −0.72 V vs. Ag/AgCl were observed. The crystal of the complex belongs to the triclinic space group P1 with a = 12.4698 (6)

Electrochemistry and Electrocatalytic Activity of Cobaloxime Complexes

“…Wiedner et al in 2016, [42] studied the electrochemistry and electrocatalytic activity of the complex Co(II)(dmgBF 2 ) 2 (CH 3 CN) 2 (33). The cyclic voltammogram of the complex (33) showed a reversible peak for Co(II)/Co(I) couple and the CV was recorded in different scan rates, which confirmed the experiment was purely diffusion controlled.…”

“…The linear plot of the scan rate against peak current revealed that the process was diffusion controlled. [40] Rountree et al, in 2016 [41] performed kinetic analysis of hydrogen production catalyzed by Co(dmgBF 2 ) 2 (CH 3 CN) 2 (33). The CV of the complex showed a reversible one electron reduction process of Co(II)/Co(I) and an irreversible peak attributed to Co(III)/Co(II).…”

“…Pizzaro et al., [33] in 2018 synthesized cobaloxime complex with terpyridine as a base ( 20 ). The presence of terpyridine was confirmed by 1 H‐NMR spectrum, which showed a peak at 7.23–7.34 ppm.…”

“…ClCo(dpgH) 2 PytPy appeared at relatively positive potentials than the ClCo(dpgH) 2 Py which was due to the effect of terpyridine ligand. [33] The electrochemistry of the mononuclear complex ( 21) showed an irreversible one electron reduction corresponding to Co(III)/Co(II) reduction. The CV of the trinuclear complex (22) also showed three irreversible peaks but at more negative potential compared with the dioxime complex that correspond to Co(III)/Co(II), Cu(III)/Cu(II) and Cu(II)/Cu(III).…”

“…As the concentration was increased further the magnitude of the peak 20) taken at 0.1 V/s. Reproduced from [33]. Reprinted (adapted) with permission from Ref.…”