Metal Complexes with Macrocyclic Ligands Part XXX. Synthesis and structure of halocuprates of tetraprotonated 1,4,8,11‐tetraazacyclotetradecane and its Cu2+ complex

Abstract

AbstractBy mixing acidic solutions of 1,4,8,11‐tetraazacyclotetradecane (Cy) with CuX2 (X = Cl−, Br−), either the hexahalocuprates of the tetraprotonated form of the macrocycle ([CyH4] [CuX6]) or the tetrahalocuprates of its Cu2+ complex ([CuCy] [CuX4]) are obtained. The structures of the chloro derivatives are established by X‐ray diffraction analysis. In [CyH4] [CuCl6], the Cu2+ is in a tetragonally distorted octahedral geometry with four short and two long CuCl bonds. The tetraprotonated macrocycle is centrosymmetric, and its conformation is exodentate, so that the four ammonium groups are as far as possible from each other to minimize the electrostatic repulsion. In [CuCy] [CuCl4], the Cu2+ ion complexed by the macrocycle is surrounded by four N‐atoms in a square‐planar arrangement. In addition, the axial positions are occupied by two Cl− ions of two CuCl units, which act as bridges. The macrocycle is in the trans‐III‐configuration. The other Cu2+ ion is coordinated by four Cl− ions in a distorted tetrahedral geometry. IR and VIS spectra of the chloro and bromo derivatives are used to discuss the structure of the bromo species.