Studies on the metal-amide bond. V. The crystal structure of aqua [N,N′-bis(2′-pyridinecarboxamido)-trans-1,2-cyclohexane] copper(II) monohydrate

Aqual[N,N′-bis(2′-pyridinecarboxamido)-trans-1,2-cylohexane] copper(II) monohydrate, C₁₈H₂₂N₄O₄Cu, is monoclinic, space group C2/c, with a = 19.239(9), b = 12.136(4), c = 16.351(6) Å β = 108.5(1)°, Z = 8. The structure was refined to R = 0.085 for 1812 photograhic reflexions using full-matrix least-squares calculations. The copper atom is five-coordinate with the N₄-tetradentate ligand encompassing the base of a distorted square-based pyramid [average CuN(amide) 1.928(8). CuN (pyridine) 2.044(8) Å, N(amide)CuN(amide) 83.5(3)° N(pyridine)CuN(pyridine) 110.4(3)°] and with the Cu atom displaced 0.21 Å above the N₄-plane towards the apical water molecule (CuO 2.303(8) Å). Both amide nitrogen atoms show significant pyramidal distortions. The cyclohexane ring adopts a 'skew-chair' conformation with the two methine hydrogens in a trans-configuration. The molecules pack in the lattice in layers parallel to (101) and a hydrogen-bond network involving both water molecules and the amide oxygen atoms of the ligand is evident.