Synthesis, Crystal Structures and Magnetic Properties of a Phenoxo‐Bridged Dinuclear CuII Complex and a Dicyanamide Bridged Novel Molecular Rectangle Based on It

The phenoxo‐bridged dinuclear Cu II complex [Cu 2 L 2 (NCNCN) 2 ] ( 1 ) and the dicyanamide‐bridged molecular rectangle [Cu 4 L 4 {μ 1,5 ‐(NCNCN) 2 }] · (ClO 4 ) 2 (H 2 O) 2 ( 2 ) were synthesized using the tridentate reduced Schiff‐base ligand HL {2‐[(2‐dimethylamino‐ethylamino)methyl]phenol}. The complexes were characterized by X‐ray structural analyses and variable‐temperature magnetic susceptibility measurements. Complex 2 was formed through the joining of the phenoxo‐bridged dinuclear Cu 2 O 2 cores of 1 via the μ 1,5 ‐bridging mode of dicyanamide. The structural properties of the Cu 2 O 2 cores in two complexes are significantly different. The geometry of the copper ions is distorted trigonal bipyramid in 1 but is nearly square‐pyramidal in 2 . These differences have a marked effect on the magnetic properties of two compounds. Although both are antiferromagnetically coupled, the coupling constants ( J = –185.2 and –500.9 cm –1 for 1 and 2 , respectively) differ considerably.