Spectroscopic and structural studies of 6-(1-methylbenzimidazol-2-yl)-1 H-pyridin-2-one and of an unusual T4(2)7(2)6(2)7(2) water tape stabilized by the copper(II) coordination polymer

Abstract

The solid-state structures of 6-(1-methylbenzimidazol-2-yl)-1 H-pyridin-2-one ( HL) and the copper(II) complex [Cu( L − ) 2(OH 2)]·2H 2O ( 1) are established by X-ray crystallography and also by means of physicochemical and spectroscopic methods. The molecules of HL form a self-complementary head-to-tail hydrogen-bonded dimer through C–H⋯N and C–H⋯O contacts to give an infinite 1D chain. The copper(II) complex ( 1) is five-coordinate with distorted trigonal-bipyramidal (TBP) geometry of the N 4O donor atoms. The electronic and EPR data are in agreement with the X-ray structure of 1, showing that HL coordinates to copper(II) centre as a mono-anionic ligand through deprotonated pyridone N atom and the tertiary benzimidazole nitrogen atom to form a neutral complex in which the water molecule occupies the fifth position. The 1D water tape, T4(2)7(2)6(2)7(2) is anchored to the host through hydrogen bonds between coordinated water molecule [O(3w)] as acting double H-donor, pyridone carbonyl groups [O(2) and O(1)] as double H-acceptor and the lattice water molecules [O(4w) and O(5w)] as double H-donor and single H-acceptor).