Studies on the metalamide bond. II. The crystal structure of the deprotonated copper(II) complex of N,N′-bis-(2′-pyridinecarboxamide)-1,2-benzene

Aqua [N,N′bis(2′-pyridinecarboxamido)-1,2-benzene]copper(II), C₁₈H₁₄N₄O₃Cu, is triclinic, space group P1, with a = 7.443(3), b = 9.560(2), c = 11.197(4), Å, α = 92.63(2), β = 100.02(2), γ = 84.50(2)°, Z = 2. The structure was refined to R = 0.038 for 2813 diffractometer data using least-squares methods. The copper atom is five-coordinate, the ligand acting as a planar N₄ tetradentated in encompassing the base of a distorted square-based pyramid [CuN(amide) 1.933(2) Å, average CuN (pyridine) 2.023(2) Å, N(amide)CuN(amide) 82.8°, N(pyridine)CuN(pyridine) 110.7°] and with the Cu atom raised 0.19 Å above the N₄ plane towards the apical water molecule (CuO 2.286(2) Å). The water molecule hydrogen bonds carbonyl oxygen atoms of adjacent chelate molecules, which are packed in layers parallel to (212. An intra-molecular steric interaction between the two H atoms in the 6-positions of the pyridine rings (H{A figure is presented}H 1.98 Å) is evident.