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Metal Complexes with Macrocyclic Ligands Part XXX . Synthesis and structure of halocuprates of tetraprotonated 1,4,8,11‐tetraazacyclotetradecane and its Cu 2+ complex
Author(s) -
Studer Martin,
Riesen Andreas,
Kaden Thomas A.
Publication year - 1989
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19890720610
Subject(s) - chemistry , crystallography , octahedron , metal , ion , crystal structure , molecule , copper , stereochemistry , tetrahedral molecular geometry , organic chemistry
By mixing acidic solutions of 1,4,8,11‐tetraazacyclotetradecane (Cy) with CuX 2 (X = Cl − , Br − ), either the hexahalocuprates of the tetraprotonated form of the macrocycle ([CyH 4 ] [CuX 6 ]) or the tetrahalocuprates of its Cu 2+ complex ([CuCy] [CuX 4 ]) are obtained. The structures of the chloro derivatives are established by X‐ray diffraction analysis. In [CyH 4 ] [CuCl 6 ], the Cu 2+ is in a tetragonally distorted octahedral geometry with four short and two long CuCl 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] [CuCl 4 ], the Cu 2+ 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 4 2−units, which act as bridges. The macrocycle is in the trans ‐ III ‐configuration. The other Cu 2+ 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.