Preparation, spectra and crystal structure of a novel NiII complex with a new oxime-functionalized diazamesocyclic ligand

A four-coordinated monomeric NiII complex with a new tetradentate diazamesocyclic ligand funtionalized by oxime donor pendants, [Ni(HL)]ClO4 (1), where H2L ¼ N,N0-bis(acetophenoneoxime)-1,5-diazacyclooctane, has been synthesized and characterized by elemental analyses, IR, UV–vis and X-ray diffraction techniques. The crystal structure of complex 1 reveals that the NiII center has a NiN4 distorted planar environment and the 1,5-diazacyclooctane ring takes the unusual boat–boat configuration. The oxime groups exhibit the only Nbinding mode with NiII ion. A striking structural feature of complex 1 residues in the formation of a two-dimensional (2D) hydrogen-bonding supramolecular architecture with (6,3) topology through intermolecular C–H· · ·O interactions, in which both ClO4 2 counter anions and the coordination cations act as 3-connected nodes. The spectral properties of the title complex have been further analyzed in detail. q 2003 Elsevier B.V. All rights reserved