Experimental and theoretical charge density of hydrated cupric acetate

The charge density of the hydrated cupric acetate Cu2(mu-OOCCH3)4.2H2O has been studied experimentally at 100 K and by DFT calculations on the isolated molecule using the Quantum Theory of Atoms In Molecules (QTAIMs). The bimetallic moiety is bridged by four equivalent acetate groups each other perpendicular and forming penta-atomic rings. The QTAIM parameters of charge density, its Laplacian, potential and kinetic energy density, delocalization indexes, static deformation density have been used to describe all intra- and intermolecular interactions. The topological analysis of the charge density maps shows the expected bond critical points with the corresponding bond paths, Cu-Cu bonding included. The data obtained using the different parameters and functions are consistent for all types of interatomic interactions, i.e. covalent, dative and intermetallic. The unpaired electrons responsible of the magnetic properties of d9 Cu(II) ions occupy the orbitals pointing towards the acetate groups. The valence shell orbital populations of Cu(II) are consistent with the distortion of the octahedral coordination due to the Jahn-Teller effect.