Crystal structure and magnetism of (μ-maleato)bis[(N-(2-(diethylamino)ethyl)-salicylidenaminato)copper(II)]-methanol

The crystal and molecular structure of (mu-maleato)bis[(N-(2-(diethylamino)ethyl)salicylidenaminato)copper(II)-methanol, [Cu(2)(salNet(2))(2)(mu-mal)] . CH(3)OH, where salNet(2) = N-(2-(diethylamino)ethyl)salicylidenaminate, has been determined by single-crystal X-ray analysis. The. compound crystallizes in the monoclinic spacegroup P2(1)/c, with a = 11.994(1), b = 14.723(1), c = 20.0384(1) Angstrom, and beta = 96.145(2)degrees. In the structure two copper(II) ions are bridged by the maleato ligand, which coordinates as a monodentate through its first carboxylato group and as a bis-monodentate ligand through its second carboxylato group. The local geometry around the first copper(II) ion is square planar, whereas that around the second is square pyramidal. Fitting of variable-temperature magnetic susceptibility data to the HDVV ((H) over cap = -2J (S) over cap (1)(S) over cap (2)), S(1) = S(2) = 1/2 spin exchange model, yields of 2J value of -4.56 cm(-1). The mechanism of the observed antiferromagnetic interactions is discussed in the light of extended Huckel calculations. Analysis shows an almost linear dependence of the magnitude of the exchange coupling constant, 2J], upon the calculated energy difference between the two SOMOs for a series of mu-dicarboxylato-bridged bis-Cu(salNet(2)) complexes.