TETRANUCLEAR COPPER(II) COMPLEXES WITH POLYDENTATE HYDRAZONE LIGANDS - SYNTHESIS AND X-RAY STRUCTURE

The synthesis and X-ray crystal structure of two copper(II) complexes, [Cu2(dappc)(OH2)3]2-[Cu2(dappc)(OH2)2(ClO4)6.2H2O (I) (H2dappc = 2,6-diacetylpyridine bis(2-pyridinecarbonylhydrazone)) and [Cu2(dapip')Br]2.2H2O, (II) (H3dapip' = 2,6-diacetylpyridine 2-pyridinecarbonylhydrazone 2-(2'-pyridine carbonylhydrazono)phenylacetohydrazone) are reported. The interest of both structures pertains mainly to their tetranuclear nature with dimeric units related by an imposed center of symmetry. The structure of compound I is built up from two different complex cations, ClO4- anions and uncoordinated H2O molecules, while that of compound II consists of neutral complex molecules and solvating H2O molecules. During the formation of the latter complex the original H4dapip ligand (H4dapip = 2,6-diacetylpyridine bis[2-(2'-pyridinecarbonylhydrazono)phenylacetohydrazone] has undergone a modification through a hydrolysis process, resulting in partial cleavage of one arm to give H3dapip'.