Synthesis, crystal structures and magnetic properties of two bis(μ-phenoxido)dicopper(II) complexes derived from reduced Schiff base ligands

Abstract

Two phenoxido bridged dinuclear Cu(II) complexes, [Cu 2(L 1) 2(NCNCN) 2] ( 1) and [Cu 2(L 2) 2(NCNCN) 2]·2H 2O ( 2) have been synthesized using the tridentate reduced Schiff-base ligands 2-[1-(2-dimethylamino-ethylamino)-ethyl]-phenol (HL 1) and 2-[1-(3-methylamino-propylamino)-ethyl]-phenol (HL 2), respectively. The complexes have been characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. Both the complexes present a diphenoxido bridging Cu 2O 2 core. The geometries around metal atoms are intermediate between trigonal bipyramid and square pyramid with the Addison parameters ( τ) = 0.57 and 0.49 for 1 and 2, respectively. Within the core the Cu–O–Cu angles are 99.15° and 103.51° and average Cu–O bond distances are 2.036 and 1.978 Å for compounds 1 and 2, respectively. These differences have marked effect on the magnetic properties of two compounds. Although both are antiferromagnetically coupled, the coupling constants ( J = −184.3 and −478.4 cm −1 for 1 and 2, respectively) differ appreciably.