Synthesis and characterization of tetrahedrally and octahedrally coordinated mixed-valence Co(II)/Co(III) complex with thiosemicarbazone-based ligand

Abstract

Synthesis, characterization, and X-ray crystal structure for a mixed-valence binuclear Co(II)/Co(III) complex with the dianionic dithiolate form of a pentadentate ligand 2,6-diacetylpyridinebis(thiosemicarbazone) are reported. A new synthetic methodology has been employed replacing usual cobalt(II) salts by [Co(NH₃)₅Cl]Cl₂ as a precursor. The coordination geometry of cobalt(II), CoN₂S₂, was found to be distorted tetrahedral, whereas the cobalt(III) coordination sphere, CoN₄S₂, is slightly distorted octahedral. The magnetic behavior and molar conductivity of the complex are in agreement with the mixed-valence state.

Keywords:

• Thiosemicarbazone
• Mixed-valence Co(II)/Co(III) complex
• X-ray crystal structure
• Tetrahedral and octahedral coordination sphere

Acknowledgements

This work was supported by NIH COBRE Award P20 RR017708 from the National Center for Research Resources (D.M.E.). A.P. would like to thank Professor Pradyot Banerjee, Indian Association for the Cultivation of Science, for providing laboratory facilities and helpful discussions.