Synthesis, structure, spectroscopy, thermal analysis and electron spin resonance of classical paddle–wheel binuclear and unusual polynuclear copper(II) compounds with benzoate and salicylamide

Abstract

Two copper(II)benzoate compounds formulated in a fashion type of [Cux[RCOO]yLz] which are compound 1 or [Cu(C6H5COO)2(C6H5(OH)CONH2)]2 and compound 2 or [Cu(C6H5COO)(H2O)2]n·n(C6H5COO)·nH2O, {where (C6H5COO) = benzoate or (C6H5(OH)CONH2) = salicylamide}, have been successfully synthesized and characterized. Single crystal X-ray diffraction results confirmed the triclinic unit cell with a space group of P1¯ of the classical paddle–wheel binuclear compound 1 and the monoclinic unit cell with a space group of C2/c of polynuclear compound 2. Novel binuclear 1 has salicylamide as ancillary ligand and consists of a distorted square pyramidal [CuO4 + O] chromophore. Polynuclear 2 consists of the monomeric [Cu(C6H5CO)(H2O)2]n+ moiety which is furthered tribridged by coordinated ligands, generated the octahedral [CuO4 + O2] core and the polymeric [Cu(C6H5CO)(H2O)2]n+ chain. Compound 2 is stabilized by water and benzoate counter parts via CH⋯O and CH⋯π weak hydrogen bondings. The Fourier-Transform infrared spectrometer as well as the solid state ultraviolet visible spectra confirmed their components, geometries and weak interactions. The thermogravimetry analysis of compounds 1 and 2 started with the releasing of water molecules and were followed by the decompositions of the organic ligands. The thermograms also indicated the strong and extensive hydrogen bond interactions. The final thermal decomposition products were copper oxide. The electron spin resonance (ESR) spectra measured at room temperature illustrating the signals of triplet. The broader field ESR spectra of 2 than 1 are also noticed.