Intermolecular stabilization in new 2-iminopyridine derivatives complexes of Pd(II) and their reactivity towards alkenes

Two new iminopyriridine ligands (1–2) and two new neutral Pd(II) complexes (4–5) were designed, synthesized and characterized by spectroscopic and spectrometric techniques. Molecular structures of compounds 1, 3 and 5 were obtained by X-Ray Diffraction. Addition of AgPF6 to compounds 4–5 produced two new cationic Pd(II) complexes stabilized by an exocyclic nitrile intermolecular interaction (6–7). The spectrometric characterization of these compounds confirms a dimeric nature of the complexes and an enhanced air/thermal/light resistance. The reactivity towards ethylene oligomerization/polymerization of all complexes (4–7) at 1 bar was evaluated, either as single component or with 1 equivalent of B(C6F5)3. The change of the counterion from PF6− to OTf− allowed to obtain the compound 8, where an improvement of the reactivity was observed. ESI-MS experiments of 8 showed the insertion of up to 16 units of ethylene in the chain.