Regulation of Structure and Magnetic Properties for Nickel(II)/Cobalt(II) Coordination Polymers with 1,4-Bis(imidazole-1-ylmethyl)benzene Ligand

Graphical Two new three-dimensional coordination polymers based on same semi-flexible ligand 1,4-bis(imidazole-1-ylmethyl)benzene (bix) have been successfully synthesized under hydrothermal condition. Both of them have similar local coordination environments but different magnetic properties due to their different topological structures and spin number S . Two new coordination polymers Ni(bix) 3 ⋅ 2(NO 3 ) ⋅ (H 2 O) 1 and Co(bix) 2 ⋅ 2(NO 3 ) 2 (bix=1,4-bis(imidazole-1-ylmethyl)benzene) have successfully been synthesized via hydrothermal reactions. These two compounds have similar local coordination environments but different topological networks due to the flexibility of the bix ligand. Additionally, magnetic studies reveal that 1 and 2 also exhibit different magnetic behaviors. Although magnetic exchange pathways are same as M II -bix-M II (M=Ni 1 , Co 2 ), 1 shows purely paramagnetic state almost down to 2 K with weak antiferromagnetic interaction; while stronger antiferromagnetic interaction in 2 is suggested. Meanwhile, an anomaly around 38 K in zero-field-cooled mode is observed but suppressed in field-cooled mode, which may be suggesting the spin canting for 2 . The field dependent magnetizations show magnetization of 2.17 μ B and 2.44 μ B at 7 T for 1 and 2 , respectively. Also, the magnetic interaction J / k B of −3.3 K is estimated for 2 .