 The organofluorine compounds can serve as a "sigma-donor ligand," as illustrated by the titanium(III) derivative [(C5Me5)2Ti(FC6H5)]BPh4.Most often, however, fluorocarbon substituents are used to enhance the Lewis acidity of metal centers.A premier example is "Eufod," a coordination complex of europium(III) that features a perfluoroheptyl modified acetylacetonate ligand.