Self association in the structures of two copper (II)–Azo-dye complexes

Abstract

The structures of the copper (II) complexes of two azo-dyes, 1- (2-pyridylazo)-2-naphthol (HPAN) and 2,2′-dihydroxyazobenzene (H 2DAB), Cu (PAN)NO 3 and Cu (DAB) · pyr are reported. In the former the molecules exist as discrete van der Waals pairs whereas in the latter an unusual trimeric unit is found which is held together by long bonding interactions between the copper atom in one molecule and one of the hydroxy oxygen atoms from the adjacent molecule: Cu (2)–O(1B), 2.517; Cu (3)–O(2C), 2.566, Cu (1)– O(2B), 2.622 and Cu (3)–O(1A), 2.768 Å.