The electron density distribution of the complex monoanion Cu(CF3)(4) in (Bu4N) [Cu(CF3)(4)] has been studied by high-resolution X-ray single-crystal diffraction and augmented with theoretical calculations. The study finds that the central copper bears an atomic charge of close to +1, while the occupancy of its d(x2-y2) orbital is only 1.26. Using topological analysis combined with theoretical calculations, the depopulation of d(x2-y2) is shown to be due to significant covalency in the Cu-C bonds. The combination of the monovalent picture and the covalency is interpreted as a confirmation of an inverted ligand field.