Magnetic, spectrochemical and thermal properties of the 2-chloro-5-nitrobenzoates of Co(II), Ni(II) and Cu(II)

Some physico-chemical properties of the 2-chloro-5-nitrobenzoates of Co(II), Ni(II) and Cu(II) were studied. The complexes were obtained as hydrates with a metal ion to ligand ratio of 1:2. All the complexes were polycrystalline com- pounds. Their colours depended on the nature of the central ion: pink for the Co(II) complex, green for the Ni(II) and blue for the Cu(II) compounds. Their thermal de- composition was studied in the range of 293-523 K because it was found that the 2-chloro-5-nitrobenzoates decomposed explosively on heating in air above 523 K. The hydrated complexes lost crystallization water molecules in one step. From the results, it appeared that no transformation of the nitro group to nitrite occurred dur- ing the dehydration process. Their solubilities in water at 293 K were of the order of 10-2 mol dm-3 for the Ni(II) and Co(II) complexes and 10-4 mol dm-3 for that of Cu(II). The magnetic moment values of Co2+ ,N i 2+ and Cu2+ in the 2-chloro-5-ni- trobenzoates, experimentally determined in the range, of 76-303 K ranged from 3.48 to 3.82 B for Co(II), from 2.69 to 3.08 B for the Ni(II) and from 1.87 to 2.00 B for the Cu(II) complex. The 2-chloro-5-nitrobenzoates of Co(II), Ni(II) and Cu(II) followed the Curie-Weiss law.