Synthesis, characterization and magnetochemical studies of some copper(II) complexes derived from 5,5'-methylene bis(N-salicylideneacylhydrazines)

摘要

5,5'-methylene bis(N-salicylideneacetylhydrazine) (H_4LMe) and 5,5'-methylene bis(N-salicylidenebenzoylhydrazine) (H_4LPh) were prepared and characterized by elemental analysis, IR, Uv-Vis, ~1Hnmr and EI mass spectra. These acylhydrazones were found to act as dinucleating bis(tridentate) ligands and a number of copper(II) complexes with formulas: i) [{Cu_2(LMe) H_2O}_x] and [{Cu_2(LPh)0.5H_2O}_x]1.5H_2O, ii) [{Cu_2(H_2LMe)Cl_2}_x] and [{Cu_2(H_2LPh)Cl_2}_x]iii) [{Cu_2(H_2LMe)}_x]x(NO_3)_2 and [{Cu_2(H_2LPh)}_x]x(NO_3)_2 were prepared and characterized. Magnetic susceptibility measurements at different temperatures (4.5-300 K) revealed that both neutral [{Cu_2 (LMe)H_2O}_x] and [{Cu_2(LPh)0.5H_2O}_x]xl.5H_2O (--2J= 197-200cm~(-1)) and nitrate [{Cu_2(H_2LMe)}_x]x(NO_3)_2 and [{Cu_2(H_2LPh)}_x]x(NO_3)_2 (--2J= 199-203 cm~(-1)) complexes show strong antiferromagnetic spin-spin coupling, implying association via phenoxy oxygens and coplanar Cu_2O_2 bridges with the Cu(II) coordination plane. The chloro complexes, on the other hand, show weak antiferromagnetic exchange coupling (-2J = 6-9cm~(-1)) implying association but with perpendicular Cu_2O_2 bridges.