The electronic properties and stereochemistry of mono-nuclear complexes of the copper(II) ion

As a consequence of the non-spherical symmetry of the copper(II) ion, d9 configuration, and of the influence of the Jahn-Teller, and pseudo Jahn-Teller effect on six-coordinate geometries, the stereochemistries of the copper(II) ion are characterized by non-rigid geometries (fluxional behaviour), and ranges of distorted geometries (Plasticity Effect) The latter may be connected by a series of Structural Pathways, which may be characterised by an ‘Electronic Criterion of Stereochemistry’ for a related series of complexes, eg the [Cu(bipy)2X] [Y] complexes

A new look at the stereochemistry and electronic properties of complexes of the copper(II) ion

Electron transfer by copper centers.

Tetramethylammonium tetrachlorozincate, {N(CH 3 ) 4 } 2 ZnCl 4 has been found to undergo successive phase transitions at about -112, -92, 3.3, 6.0 and 20°C and to show ferroelectricity along the a axis in the temperature range between 3.3 and 6.0°C.

Ferroelectricity in {N(CH3)4}2ZnCl4

Electron paramagnetic resonance studies of the tetrahedral CuCl4= ion in single crystals of Cs2CuCl4 and Cs2ZnCl4 yield the spectroscopic parameters g1=2.083±0.001, g2=2.103±0.003, g3=2.384±0.006 (Cs2CuCl4) or 2.446±0.002 (Cs2ZnCl4), and | A1 | = (5.1±0.5)×10−3 cm−1, | A2 | = (4.6±0.5)×10−3 cm−1, and | A3 | = (2.5±0.5)×10−3 cm−1. The indicated errors are estimated from the slight asymmetries in the line shapes and from the lack of full resolution of the hyperfine components. The resonances show no resolved superhyperfine structure. It is demonstrated that the linewidths of 2.2×10−3T observed between inflections at low temperatures arise from unresolved superhyperfine interaction and are consistent with the presence of an unpaired electron which spends 1.3% of its time occupying 3s orbitals of the Cl ions of the complex. Comparison with the superhyperfine structure observed in octahedral CuCl64— suggests that this electron also spends 16.7% of its time occupying Cl ion 3p orbitals. Insertion of these numbe...

E. C. Lingafelter

Papers

The configuration of the tetrachlorocuprate(ii) ion