Spectral and structural studies of copper(II) complexes of thiosemicarbazones derived from salicylaldehyde and containing ring incorporated at N(4)-position

Mononuclear and binuclear copper(II) complexes ( 1– 8) with two ONS donor thiosemicarbazone ligands {salicylaldehyde 3-hexamethyleneiminyl thiosemicarbazone [H 2L 1] and salicylaldehyde 3-tetramethyleneiminyl thiosemicarbazone [H 2L 2]} have been prepared and physico-chemically characterized. IR, electronic and EPR spectra of the complexes have been obtained. The thiosemicarbazones bind to metal as dianionic ONS donor ligands in all the complexes except in [Cu(HL 1) 2] ( 2) and [Cu(HL 2) 2] ( 6). In compounds 2 and 6 the ligands are coordinated as monoanionic HL − ones. The magnetic susceptibility measurements indicate that all the complexes are paramagnetic. In complex [(CuL 1) 2] ( 1), the magnetic moment value is lower than the expected spin only value. In all the complexes g || > g ⊥ > 2.0023 and G values within the range 2.5–3.5 are consistent with d x 2 − y 2 ground state. The complexes were given the formula as [(CuL 1) 2] ( 1); [Cu(HL 1) 2] ( 2); [CuL 1bpy] ( 3); [CuL 1phen] ( 4); [CuL 1γ-pic]·2H 2O ( 5); [Cu(HL 2) 2] ( 6); [CuL 2py]·3H 2O ( 7); [CuL 2bipy] ( 8). The structure of the compound 8 have been solved by single crystal X-ray crystallography and was found to be distorted square pyramid around copper(II) ion.