Magnetic study and DFT analysis of a doubly carboxylato-bridged Co(II) derivative anchored with a 'scorpionate' precursor as a potential electrocatalyst for heterogeneous H 2 evolution

• Published in: Dalton transactions : an international journal of inorganic chemistry 2024-06, Vol.53 (22), p.9358
• Main Authors: Das, Kuheli, Beyene, Belete B, Massera, Chiara, Garribba, Eugenio, El Fallah, M S, Frontera, Antonio, Hung, Chen-Hsiung, Datta, Amitabha
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/D4DT00807C

A new doubly carboxylato-bridged Co(II) dinuclear complex, [Co(bdtbpza)(NCS)] (1), was obtained in a satisfactory yield by employing a 'scorpionate'-type precursor, {bis-(3,5-di- -butylpyrazol-1-yl)acetate}, and was then structurally characterized. Single-crystal X-ray diffraction analysis revealed that, in 1, each Co(II) is penta-coordinated, leading to a distorted trigonal-bipyramidal geometry within the coordination environment of N O . Weak antiferromagnetic coupling within the Co(II) ions in 1 was found based on the isotropic spin Hamiltonian = - ( · ) for the = 3/2 system. For evaluating the spin density distribution and the mechanism for the magnetic exchange coupling, DFT analysis was performed, with the calculated result agreeing the experimental magnetic data. A study into electrochemical H evolution, involving cyclic voltammetry (CV), controlled potential electrolysis (CPE), and gas chromatographic (GC) analyses of the graphite electrode modified with the cobalt complex in a neutral aqueous solution revealed the high catalytic activity of the complex with a low overpotential toward H O reduction. The faradaic efficiency of the catalyst was found to be 83.7% and the di-cobalt catalyst-modified electrode displayed quite an interesting H -evolution activity compared with that of bare electrodes. These results are encouraging for the future potential application of 1 in water splitting.