New copper complexes of diacetyl hydrazone oxime and its acetone azine

571-578Using diacetyl hydrazone oxime (LH), we have synthesised a neutral copper(I) complex of the type Cu(L)(LH). Such stabilisation of copper(I) has not been achieved using the acetone azine (L'H) of LH. Both LH and L'H yield hexanuclear copper(II) complexes - CU6L6(O)(OH)(ClO4)3.3CH3COOH (1a) and CU6L'6(O)(OH)(ClO4)3 (1b), respectively. X-ray crystal structure of 1b (space group PbcZ1; Z = 4) indicates that both 1a and 1b contain an unprecedented Cu3O···H···OCu3 core where the copper atoms are staggered. In 1b, two of the three perchlorate anions are coordinated to the metals. The cationic part in 1b comprises two [(ClO4)Cu3O(L')3] units held together by a proton. The O··:H···O bond (2.428Å) is one of the shortest H-bonds known. Each copper(II) center in 1b is square pyramidal with a perchlorato oxygen occupying the apical position. The average bond distances around each copper(II) center are: Cu-perchlorato O, 2.54; Cu-central O, 1.91; Cu-oximato O, 1.92; Cu-oximato N, 1.95; Cu-azine N, 1.98 A. In a [(ClO4)Cu3O(L')3] unit, the three copper atoms are linked to each other via a centrally bridging oxygen atom and two adjacent copper atoms are further linked by a peripheral oximato bridge. It is indicated that the hexanuclear copper(II) moiety in 1a and 1b represents a case of two unpaired spins interacting through an H-bond