Synthesis, crystal structure and spectroscopic characterization of a hydrogen-bonded 1D copper(II) complex

Abstract

Novel 1:2 and 1:1 (M:L) copper(II) complexes have been prepared from the tridentate ligand 2-(1-methyl-2-aza-5-oxapentyl)phenol (H2L1). The crystal structure of [Cu(HL1)2] (1) exhibits a noncentrosymmetric square-planar geometry with a slightly tetrahedral distortion. The CuII atom is coordinated by two amino N and two phenoxo O atoms of two (HL1)− ligands. The phenoxo and the alkoxy groups are involved in two strong intramolecular hydrogen bonds. The coordination moieties are further connected to a 1D linear structure by the action of intermolecular hydrogen bonds between the alkoxyl and the amino groups. The importance of steric hindrance introduced by the methyl group in the molecular structure and the packing of the complex molecules has been demonstrated. The e.p.r. parameters of (1) have been obtained: g∥ = 2.231, g⊥ = 2.005, giso = 2.080, A∥ = 185.0 G, Aiso = 86.5 G, A⊥ = (3Aiso − A∥)/2 = 37.3 G. These results confirm a distorted square planar stereochemistry with a (\({\text{d}}_{x^2 - y^2 }\))1 ground state.