Syntheses, spectroscopic, structural characterization of Co(III) and Co(II) carboxylates and electron transfer reactions with ferrocene derivatives

Herein we report five cobalt compounds; three compounds containing 5-nitroisophthalate viz. Bis{bis(2,2'-bipyridine-kappa(2)-N,N')(carbonato-kappa(2)-O,O')cobalt(III)}5-nitroisophthalate undeca-hydrate, [Co(bpy)(2)(CO3)](2)(5-nip)center dot 11H(2)O 1 synthesized by conventional steam bath reaction, while [Co(H2O)(3)(bpy)(5-nip)]center dot H2O2 and polymeric [Co(5-nip)(bpy)(H2O)] 3 prepared under autoclave conditions. The two compounds of 4-nitrobenzoic acid viz. Bis(2,2'-bipyridine-kappa 2-N,N')(carbonato-kappa(2)-O,O')cobalt(III)} 4-nitrobenzoate pentahydrate, [Co(bpy)(2)(CO3)](4-nba)center dot 5H(2)O 4 and [Co-2(4-nba)(2)(bpy)(2)(H2O)(4)](4-nba)(2) 5 were also obtained by steam bath and autoclave reactions. These compounds were characterized by single crystal X-ray diffractometry, elemental, spectroscopic, magnetic and thermal methods. Compounds 1 and 4 were studied by XPS, NMR, CV and VSM, revealing +3 oxidation state of Co. 1 showed eleven lattice waters while five waters were observed in 4 due to the change in carboxylate ligand. A large number of O-H center dot center dot center dot O and C-H center dot center dot center dot O interactions leading to extended networks were observed in their crystal structures. The thermal behavior of 1-5 was investigated using TG-DTA techniques. Both carbonato Co(III) compounds 1 and 4 were investigated for their oxidizing properties with ferrocene derivatives and the results of these electron transfer reactions are reported. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this report, the synthesis and characterization of five cobalt compounds are presented. The crystal structures, elemental composition, spectroscopic properties, magnetic properties, and thermal behavior of the compounds were analyzed using various techniques. The oxidizing properties of two of the compounds were evaluated through electron transfer reactions with ferrocene derivatives.