The Temperature-Variable Geometry of the Pseudo-Octahedral CuO₆ Entity in Bis(methoxyacetato) diaquo-Cooper(II) - a Single Crystal EPR Study

Abstract

Abstract The Cu-O bond lengths in the pseudooctahedral bis(methoxvacetato)diaquo-copper(II) com­plex are determined by the Jahn-Teller effect on the one hand and by the bonding properties of the three different oxygen ligator atoms (from a carboxylate. water and ether group) on the other. It is derived from EPR single crystal and powder investigations between 4.2 and 350 K. that the system becomes fluxional above =120 K due to a continuous transition from a static to a (par­tially) dynamic Jahn-Teller distortion. A model is presented, which allows to correlate the EPR results with the Cu-O spacings. if they are calibrated with structural data at two different temperatures. The structure of the ground state potential surface of Cu 2+ is derived from the spectroscopic data.