Synthesis, characterization and density functional calculations on dichloro-bis(4-dimethylaminopyridine) cobalt(II) complex [Co(II)(C₇H₁₀N₂)₂Cl₂]

Abstract

The title complex, [Co(II)(C₇H₁₀N₂)₂Cl₂], has been synthesized and characterized by elemental analysis, UV-vis spectra and X-ray single crystal diffraction. It crystallizes in the monoclinic system, space group P2/c, with lattice parameters a = 8.1370(16) Å, b = 6.4990(13) Å, c = 16.416(5) Å, β = 98.99(3)° and Z = 2. The crystal structure of the title compound consists of monomeric molecules of [Co(II)(C₇H₁₀N₂)₂Cl₂] with C ₂ symmetry and the two-fold axis through the Co(II) ion and the mid-point of two Cl⁻ anions. TG/DTG data indicate that thermal decomposition of the compound takes place in two steps and the residue is Co. Density functional theory (DFT) calculations of the structure, electronic spectra, natural population analysis and the thermodynamic properties at different temperatures have been performed. The calculated results show that electronic transitions are mainly derived from the contribution of an intraligand (IL) π → π* transition, metal-to-ligand charge transfer (MLCT) and d–d transition. Bond strength of Co–Cl is stronger than that of Co–N, which agrees with the experimental data. The correlation equations of the thermodynamic properties of and with temperature are also obtained.

Keywords:

• Crystal structure
• Electronic spectra
• Thermal stability
• Thermodynamic property
• DFT calculations

Acknowledgements

This work was supported by the Natural Science Foundation of Shandong Province (No. Y2005B04), P.R. China, the Doctoral Fund of Shandong Province, P.R. China, (No. 2006BS01043) and the Doctoral Fund of Qingdao University of Science & Technology.