Syntheses and structures of square-pyramidal acetonitrile coordinated copper(II) complexes with N-(aroyl)-N′-(5-nitrosalicylidene)hydrazines

Abstract

The syntheses and structures of two square-pyramidal acetonitrile coordinated copper(II) complexes, [Cu(HbhsNO2)(CH3CN)2]ClO4 (1) and [Cu(HahsNO2)(CH3CN)(ClO4)] (2), are described. The mononegative ligands are obtained by deprotonation of the phenolic-OH of N-(benzoyl)-N′-(5-nitrosalicylidene)hydrazine (H2bhsNO2) and of N-(anisoyl)-N′-(5-nitrosalicylidene)hydrazine (H2ahsNO2). Crystal data for 1: monoclinic, P21/c (#14), a = 9.7245(14), b = 20.23(4), c = 11.042(3) Å, β = 91.86(2)°, V = 2171.0(7) Å3, and Z = 4 and for 2: triclinic, P1̄ (#2), a = 9.7710(19), b = 9.9687(15), c = 11.062(5) Å, α = 73.10(3), β = 88.77(3), γ = 88.379(14)°, V = 1030.4(5) Å3, and Z = 2. In each complex the planar ligand binds the metal ion via phenolate-O, imine-N, and amide-O. The nitrogen of an acetonitrile molecule satisfies the fourth site of the square-plane containing the metal ion. In 1 the axial coordination is provided by the nitrogen of a second acetonitrile molecule, whereas in 2 one of the oxygen atoms of the perchlorate occupies the fifth axial site. The axial acetonitrile molecule of 1 is bound to the metal center in a bent mode. The other noticeable difference between the two structures is in the geometry at the metal center. A large displacement (0.23 Å) of the metal ion from the ONON basal plane towards the axial coordinating atom is observed in 1. On the other hand, there is no displacement of the metal center from the same ONON basal plane in 2. The EPR and electronic spectral features in acetonitrile solutions are consistent with the solid state structures.