Cobalt 2-pyrazinephosphonates: syntheses, structures, and magnetic properties

Abstract

Reactions of Co(ClO₄)₂·6H₂O with 2-pyrazinephosphonic acid (2-paPO₃H₂) under two different hydrothermal conditions gave two new cobalt 2-pyrazinephosphonates, Co(2-paPO₃H)₂ (1) and Co(2-paPO₃)(H₂O) (2). Compound 1 was obtained at 160 °C, while 2 was obtained at 180 °C. In 1, two Co(II) units are bridged by two O–P–O’s into a dimer and the dimers are linked by pyrazinyl groups into a 1-D double chain. In 2, the {CoO₄N₂} and {CPO₃} polyhedra are interconnected via edge and corner-sharing into a metal phosphonate layer, and the layers are pillared by pyrazinyl groups into a 3-D network. Variable-temperature magnetic susceptibility studies reveal that both complexes have weak antiferromagnetic coupling between Co(II) ions.

Keywords:

• Cobalt
• Phosphonate
• Polymer
• Magnetic

Acknowledgments

This work is supported by NSFC (No. 21001018), NSF of Jiangsu Provence (No. BK2012643, No. 12KJA 150001, 11KJB 150001), the State Key Laboratory of Coordination Chemistry of Nanjing University, and Qinglan Project of Jiangsu Province.