Polyfluoroalkylated tripyrazolylmethane ligands: Synthesis and complexes

Tripyrazolylmethanes represent a novel class of uncharged ligands analogous to charged tripyrazolylborates (scorpionates), which are isoelectronic and isolobal with cyclopentadienides. We report here a straightforward synthesis of the first polyfluoroalkylated tripyrazolylmethane ligands bearing C4F9–C12F25 ponytails, based on allylation/perfluoroalkylation/reduction sequence of transformations of 2,2,2-tripyrazol-1-ylethanol. Model complexation reactions of these ligands gave sandwich complexes of copper(II), nickel(II), cobalt(II) and iron(II), the structure of which was confirmed by detailed MS analysis, as well as by NMR spectroscopy for the fourth diamagnetic complex. Fluorophilicity of the ligands and their complexes peaks for C10F21 ponytail but lies below zero.