Facile synthesis of paramagnetic Co(II)-hexaborate(2-) based semiorganic complexes: A combined investigation on X-Ray crystal structure, Hirshfield surfaces analysis, optical and magnetic properties

Abstract Two new paramagnetic hybrid cobalt(II)-hexaborate(2-) based semiorganic complexes; (2A3MP)2[Co{κ3O-B6O7(OH)6}2].2H2O(1) and (2A4MP)2[Co{κ3O-B6O7(OH)6}2].2H2O (2)(2A3MP = 2-amino-3-methylpyridinium, 2A4MP = 2-amino-4-methylpyridinium)have been obtainedand characterized by X-ray diffraction, FT-IR, TG-DTA, optical and magnetic measurements. X-ray diffraction revealed two isostructural lattices with octahedral coordination of Co(II) complexes of bis(κ3O-donor hexaborate(2-)) ligands, [Co{κ3O-B6O7(OH)6}2]2-. The hydrated oxidopolyborate anions are extensively H-bounded to perform 3D-porous supramolecular anionic frameworks. In both 1 and 2 isostructures, 2A3MP and 2A4MP cations are pendant in the created voids of the inorganic frameworks through a set of H-bonds with 8.5 % and 60.5%H…O/O…H inter-contact contributions, respectively for 1 and 2 as confirmed by Hirshfield surfaces analysis. The optical band gap of Co(II) complexes range between 2.72 and 3.13 eV. Both compounds exhibited well-resolved paramagnetic properties with magnetic susceptibility values ranged between 0.9552 and 0.0088 cm3.mol-1, typical of octahedral Co(II) complexes.