Crystal structures, electronic properties and structural pathways of four [Cu(phen)2Cl][Y] complexes (phen = 1,10-phenanthroline; Y = BF4-·0.5H2 O, PF6-, CF3SO3-·H2O or BPh4-)

Abstract

The crystal structures of [Cu(phen) ₂ Cl][BF ₄ ]·0.5H ₂ O 1 (phen = 1,10-phenanthroline), [Cu(phen) ₂ Cl][PF ₆ ] 2, [Cu(phen) ₂ Cl][CF ₃ SO ₃ ]·H ₂ O 3 and [Cu(phen) ₂ Cl][BPh ₄ ] 4 have been determined by X-ray crystallography. Three of the complexes, 1–3, involve a CuN ₄ Cl chromophore with a square based pyramidal distorted trigonal bipyramidal stereochemistry, while 4 involves a trigonal bipyramidal distorted square based pyramidal stereochemistry. The geometries of the CuN ₄ Cl chromophores in 1–4 were compared by scatter-plot analysis with those of four other [Cu(phen) ₂ Cl][Y] complexes of known structure. The scatter plots of the eight cation distortion isomers of the [Cu(phen) ₂ Cl][Y] complex suggest that all the complexes involve a -A + B route distortion of the CuN ₄ Cl chromophore, -A (ca. 60%) and +B (ca. 40%), The observation of linear and parallel correlations are alternatively interpreted as a direct observation of vibronic coupling of a mixture of the symmetric, ν _sym , C ₂ mode and the asymmetric, ν _asym , non-C ₂ mode of vibration of the CuN ₄ Cl chromophore. This emphasises the need to determine the structure of more than one complex in a series of cation distortion isomers, in which the limits of the range of stereochemistries are indicated by the measurement of the electronic reflectance spectra.