Magnetic properties of Ni-complexes in a hydrazone structure

The Ni2+ complex with 5-methylsalicylaldehyde 5'-chlorosalicyloyl hydrazone has been studied with electron paramagnetic resonance spectrometer (EPR) and vibrating sample magnetometer (VSM) over the temperature range 2-300 K. The magnetization measurements, performed in the magnetic field of I T,show that at low temperatures the Ni2+ ions are coupled by the antiferromagnetic exchange interactions. Above the Neel temperature T-N = 11.4 K, the temperature dependence of the susceptibility of Ni-complexes follows the Curie-Weiss law. The EPR spectrum observed at room temperature exhibits a broad signal originating from Ni2+ ions. It is also found that at low temperatures the EPR signal experiences a sharp broadening and shifts to the lower field region. The intensity of this signal decreases with lowering the temperature and below I I K this line disappears. It may be attributed to the formation of an antiferromagnetically ordered phase at low temperatures.