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

Two phenoxido bridged dinuclear Cu(II) complexes, [Cu2(L1)2(NCNCN)2] (1) and [Cu2(L2)2(NCNCN)2]·2H2O (2) have been synthesized using the tridentate reduced Schiff-base ligands 2-[1-(2-dimethylamino-ethylamino)-ethyl]-phenol (HL1) and 2-[1-(3-methylamino-propylamino)-ethyl]-phenol (HL2), respectively. The complexes have been characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. Both the complexes present a diphenoxido bridging Cu2O2 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.

Synthesis, crystal structure and magnetic study of two phenoxido bridged dinuclear Cu(II) complexes with two NNO donor tridentate reduced Schiff base ligands are reported. The geometry around Cu(II) is intermediate between trigonal bipyramid and square pyramid in both complexes. The appreciable difference in the magnitude coupling in these two antiferromagnetically coupled compounds can be explained by taking account of both bridging angle and bond distances in the Cu2O2 core.Figure optionsDownload as PowerPoint slideHighlights
► Phenoxido bridged dinuclear Cu(II) complexes of reduced Schiff base ligands.
► Cu(II) is intermediate between trigonal bipyramid and square pyramid.
► The bridging angles and bond distances explain the differences in J values.