Synthesis, molecular structure, and spectral analysis of copper(II) complexes derived from pyridinediols

Abstract

A series of mononuclear copper(II) complexes was synthesized by reaction of different 2,6-disubstituted pyridines with elemental Cu in a CCl₄/DMSO solvent system. Physical properties were analyzed using IR, optical spectroscopy, mass spectrometry, and EPR. Single-crystal X-ray diffraction for complexes 2a and 4a revealed that the molecular structure of 2a is composed of a six-coordinate unit in which two ligands are linked to Cu(II) by oxygen and nitrogen donors. Conversely, in the molecular structure of 4a, the Cu(II) has a slightly distorted trigonal bipyramidal arrangement, where the coordination environment around the copper ion is five-coordinate. EPR spectra of Cu(II) complexes were illustrated elaborately and some theoretical data were abstracted from EPR curves to support the proposed structures.

Keywords:

• Synthesis
• Pyridinediols
• Copper(II) complexes
• Mononuclear
• X-ray diffraction

Acknowledgements

We gratefully acknowledge financial support from Instituto de Química, UNAM. One of the authors, G.M.C., is thankful to The World Academy of Sciences (TWAS) and the Consejo Nacional de Ciencia y Tecnología (CONACYT) for awarding a post-doctoral research fellowship. We also appreciate the technical assistance of Rocío Patiño, María de la Paz Orta Pérez, Alejandra Núñez Pineda, Luis Velasco, and Javier Pérez.