Attractive fluorine···fluorine interactions between perfluorinated alkyl chains: A case of perfluorinated Cu(II) diiminate Cu[C₂F₅-C(NH)-CF=C(NH)-CF₃]₂

A synthesis of the perfluorinated copper diiminate complex Cu[C2F5-C(NH)-CF=C(NH)-CF3]2 (3) and its self-assembly into infinite 1D chains in the crystal via Type II C(sp3)-F···F-C(sp3) contacts between perfluoroethyl substituents is reported. Rare Type II F···F interactions were studied by DFT calculations and topological analysis of the electron density distribution within the formalism of Bader's theory (QTAIM method). This is the first report which discusses Type II contacts between perfuoroalkyl chains.