Structures of bis(4-aminopyridinium) tetrachlorocuprate(II) monohydrate, [C₅H₇N₂]₂[CuCl₄].H₂O and bis(2-amino-3-hydroxypyridinium) tetrachlorocuprate(II), [C₅H₇N₂O]₂[CuCl₄]: correlation of CuCl₄ ²⁻ geometry with hydrogen bonding and electronic structure

Editorial: A Natural Balance: Communications and Full Papers

“…Sixty two compounds with CuCl 4 2– and various counter cations have been reported 14, with structures, covering the range from nearly tetrahedral to square‐planar (Figure 8). Table 6 summarizes the results of an energy fitting to observed electronic transitions in the cases, where d–d spectra are reported – separately for D 2d ‐distorted CuCl 4 2– entities and the D 4h structures.…”

“…Whereas experimental data overflow for chlorine as the ligand atom, DFT may be used as a data base in the case of the other ligands, in order to provide insight into the properties of the copper(II)–ligand bond. The rich structural and spectroscopic data for CuCl 4 2– 14 are used to link the seemingly naive, but correct AOM description and the vibronic coupling approach with the more rigorous, but still approximate DFT method (see for example ref 30…”

Syntheses, Crystal Structures and Spectroscopic Studies of Bis[1‐methyl‐3‐(methoxycarbonylmethyl)‐benzimidazolium]2+ [CuBr4]2− and [ZnBr4]2− Compounds

“…Another problem is related to the tetrahedron dynamics. It can be due to the Jahn‐Teller effect (vibronic coupling) for high symmetry complexes, which can produce an additional static complex deformation and large librational motions which lead to apparent shortening of Cu−X distance as it was observed for short Cu‐ligand bonds …”

“…Hydrogen bonds tend to remove charge from ligand atom reducing electrostatic repulsion between them and enhancing a tendency to the square‐planar coordination. Symmetric deformations of MX 4 – tetrahedron with defined deformation angles are shown in Figure1 and have been studied experimentally and theoretically both for CuCl 4 and CuBr 4 complexes …”

Ditopic azathioether macrocycles as hosts for transition metal saltsElectronic supplementary information (ESI) available: full experimental details. See http://www.rsc.org/suppdata/cc/b1/b109486f/

“…The observed distorted tetrahedral geometry of [CuCl 4 ] 22 is typical for this dianion. 11 As with L 1 , the monobrachial azathioether L 2 is therefore able to simultaneously bind cationic and anionic halo-metal fragments; this system formally represents a methodology for the extraction and transport of CuCl 2 .…”