Synthesis and in Solution and Solid State Structural Study of Intramolecular Pt···H Interactions in Pentafluorophenyl Platinum(II) Complexes Containing the Ligands Triazene, Formamidine, and 2-Aminopyridine

The preparation of the [NBu4][Pt(C6F5)3L] complexes (L = triazene, 1; formamidine, 2; 2-aminopyridine, 3) have
been carried out. These ligands contain a hydrogen atom, with more or less acidic character, in a position suitable
for establishing an intramolecular hydrogen bonding interaction with the metal center. This interaction has been
detected in solution for 1; its 1H NMR spectrum shows that the resonance assignable to this hydrogen has platinum
satellites. For 2, this coupling is not observed, and the interaction, if it exists, has to be weaker because of the less
acidic character of the hydrogen atom. The 2-aminopyridine ligand is more flexible than the triazene or formamidine,
and also in this case, no evidence of the interaction in solution is obtained. Nevertheless, if another potential
proton acceptor is present, such as ClO4- in [NBu4]2[Pt(C6F5)3(C5H6N2)](ClO4) (4), a conventional N−H···O−Cl
hydrogen bond is formed. The crystal structures of complexes 1−4 have been determined by X-ray diffraction.