Two azido-bridged cobalt(ii) coordination polymers with nicotinate co-ligand: Synthesis, structures and magnetic properties

摘要

By utilizing nicotinic acid as a co-ligand, two new azido-bridged cobalt(ii) complexes with the formulae [Co _2(N _3)(nic) _2Cl(H _2O)] _n (1) and [Co(N _3)(nic)] _n (2) (nic = nicotinate) have been synthesized under solvothermal condition and structurally characterized. Complex 1 exhibits a rare three-dimensional (3D) Kagomé topology with [Co4] units as connecting nodes. Complex 2 is also a 3D structure which contains 1D Co ~(II)-μ- 1,1-azido chains as rod-shaped SBUs. Magnetic data analysis shows that ferromagnetic coupling intra-[Co4]-cluster and antiferromagnetic interaction inter-[Co4]-cluster exists in complex 1, while complex 2 exhibits metamagnetism with a critical field of 5.5 kOe.