SYNTHESIS AND MAGNETIC-PROPERTIES OF A BINUCLEAR COPPER(II) COMPLEX WITH A MU-1,2-SQUARTO COORDINATION MODE - CRYSTAL-STRUCTURE OF HYLAMINO)ETHYL)SALICYLIDENEAMINATO)AQUACOPPER(II)] HYDRATE

The crystal and molecular structure of thylamino)ethyl)salicylideneami nato)aquacopper(II) hydrate, [Cu2(SalNEt2)2(H2O)(C4O4)].H2O, where Sal NEt2 = N-(2-(diethylamino)ethyl)salicylideneaminate, has been determin ed by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group P2(1), with a = 10.6616(9) angstrom, b = 11.761 (1) angstrom, c = 13.712(1) angstrom, beta = 70.678(2)-degree s, and Z = 2. The structure consists of binuclear units built by two n onequivalent copper(II) moieties, namely [Cu(SalNEt2)H2O] and [Cu(SalN Et2)], bridged by a squarato ligand coordinated to the copper(II) ions in a mu-1,2 mode. The geometry of the first copper(II) ion is distort ed square pyramidal, whereas that of the second one is approximately s quare planar. This complex is the first example of an X-ray structural ly characterized binuclear transition metal complex with the two metal cations being intervened by a single squarato ligand in a mu-1,2-coor dination mode. The intramolecular Cu(1) ... Cu(2) distance (5.210(6) a ngstrom) is the shortest found in squarato-bridged copper(II) complexe s. The magnetic behavior of the complex has been studied over the 4.6- 295 K temperature range. The fitting of experimental magnetic suscepti bilities vs temperature to the HDVV (H = -2JS1S2), S1 = S2 = 1/2, spin exchange model yields a 2J value of -10.3 cm-1. The magnitude of the observed antiferromagnetic interaction, which is one of the largest fo und in copper(II) squarato complexes, has been interpreted in terms of the structural and electronic characteristics of the complex.