Syntheses and structural studies of the nickel(II) octahedral complexes Ni(N∩N)xL2 with nitrogen-containing and carboxylate ligands

Abstract

A series of new mononuclear octahedral nickel(II) complexes with the Ni(N∩N)_xL₂ framework (x = 2 or 3, N∩N = Рhen (1,10-phenanthroline), AMPy (2-(aminomethyl)pyridine), L is H₂O, anions of carboxylic acids (CF₃CO₂−, CCl₃CO₂−, HCO₂−), chloride ion, and water) is synthesized and described by IR spectroscopy, mass spectrometry, elemental analysis, and X-ray diffraction analysis: [Ni(Рhen)₂(OH₂)Cl]Cl · 2H₂O (I), [Ni(Рhen)₂(OH₂)(O₂CCF₃)](O₂CCF₃) (II, IIa), [Ni(Рhen)₂(HCOO)_1.618(H₂O)_0.382](HCOO)_0.382 · 4.618H₂O (III), ([Ni(Рhen)₂(OH₂)₂](O₂CCCl₃)₂ · 6.2H₂O (IV), [Ni(AMPy)₂(OH₂)₂](HCO₂)₂ · 6H₂O (V), and [Ni(Рhen)₃](CCl₃COO)₂ · 7H₂O (VI). The subunit containing two formate ligands in the inner sphere of the [Ni(Рhen)₂(HCO₂)₂] complex prevails in the crystal structure of complex III, which is not characteristic of the nickel carboxylate complexes of this type. In aqueous solutions complex IV undergoes decarboxylation to form [Ni(Рhen)₂(CO₃)] · 7H₂O. A change in the nature of the N-donor ligands in Ni(N∩N)₂L₂ leads to the change (cis or trans) in the configuration of the whole complex (СIF files CCDC no. 880414 (I), 842336 (II), 1430414 (IIa), 1478111 (III), 1430430 (IV), 1443133 (V), and 1430415 (VI)).