Detailed solvation shell geometry of cupric ion in ethanol determined by electron-spin-echo modulation analysis

Abstract

The analysis of electron-spin-echo modulation patterns for Cu/sup 2 +/ in variously deuterated ethanol glasses shows that Cu/sup 2 +/ is solvated by six approximately equivalent ethanol molecules with their molecular dipoles oriented toward Cu/sup 2 +/. A distance of >0.03 nm between in-plane and out-of-plane molecules should be distinguishable in this analysis, so a single shell analysis is a good approximation. From specific deuteration studies the average orientation of a first solvation shell ethanol molecule with respect to Cu/sup 2 +/ is deduced. The distance from Cu/sup 2 +/ to the ethanol oxygen is 0.21 nm, that to the hydroxyl proton is 0.26 nm, those to the methylene protons are 0.35 and 0.41 nm, and those to the methyl protons are 0.38, 0.49, and 0.49 nm. The HOC plane is perpendicular to the OCC plane in ethanol, giving a molecular conformation intermediate to the trans and gauche forms.