A DICOPPER COMPLEX OF N,N'-BIS[2,2-DIMETHYL-4-(2-HYDROXYPHENYL)3-AZA-3-BUTEN] OXAMIDE - STRUCTURE AND MAGNETIC-BEHAVIOR OF THE MONO HYDRATED FORM

The ligand N,N'-bis[2,2-dimethyl-4-(2-hydroxyphenyl(-3-aza-3-buten] oxamide with two identical coordination sites reacts with copper ions in its tetradeprotonated form to yield the dinuclear complex [Cu-2(C24H26N4O4)]. H2O. The structure of this compound has been determined by the X-ray diffraction method. The crystals are orthorhombic with a=11.744(1), b=16.369(2), c=26.340(3) Angstrom, V=5064(1) Angstrom(3), Z = 8, space group Pbca. The oxamide is in a trans conformation with two different environments for the copper centres, a (4+1) coordination mode for the first one and a square planar environment for the other one. The water molecule is not directly bound to a copper centre, but involved in hydrogen bonding with the two oxygen atoms of an N2O2 coordination site. Indeed, extra coordination comes from a phenolic oxygen atom belonging to an adjacent dinnclear unit. Static susceptibility measurements point to a strong intrapair antiferromagnetic exchange interaction of 2J=-520(+/-4) cm(-1) and possibly an interpair ferromagnetic exchange interaction of 10(+/-5) cm(-1).