Crystal structure, magnetic properties and orbital interactions of the binuclear fumarato-bridged bis[((N-(2-diethylamino)ethyl)-salicylidenaminato)copper(II)] complex

Abstract The title compound of formula [Cu 2 (SalNEt 2 ) 2 (C 4 H 2 O 4 )], where SalNEt 2 = N -(2-(diethylamino)ethyl)- salicylidenaminate, has been synthesized and its structure solved at room temperature. It crystallizes in the monoclinic system, space group P 2 1 / c , with a =10.463(2), b =16.048(2), c =9.434(1) A, β=106.91(1)° and Z =2. In the molecular structure of this centrosymmetric compound the two equivalent copper( II ) ions are bridged by the fumarato ligand coordinated in an amphimonodentate mode. The local geometry around both copper( II ) ions is approximately square planar. Magnetic susceptibility data for the complex as a function of temperature show weak exchange interactions. The fitting of these data to the HDVV ( Ĥ =−2 JŜ 1 Ŝ 2 ), S 1 = S 2 =1/2 spin exchange model, yields a 2 J value of −1.8 cm −1 . An orbital interpretation of the observed weak antiferromagnetic interactions is presented based on the results of extended Huckel calculations on a model compound.