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

• Published in: Journal of organometallic chemistry Vol. 863; pp. 21 - 29
• Main Authors: Escobar, Manuel A., Moreno da Costa, David, Trofymchuk, Oleksandra S., Daniliuc, Constantin G., Gracia, Francisco, Nachtigall, Fabiane M., Santos, Leonardo S., Rojas, Rene S., Cabrera, Alan R.
• Format: Journal Article
• Language: English
• Published: LAUSANNE Elsevier B.V 15.05.2018; Elsevier
• Subjects: Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Intermolecular stabilization; Nitrile group; Oligomerization; Palladium (II); Physical Sciences; Science & Technology; α−diimine; Nitrile group; α−diimine; Oligomerization; Intermolecular stabilization; Palladium (II); ALPHA-OLEFINS; DESIGN; BEHAVIOR; NICKEL-CATALYST; LIVING POLYMERIZATION; COORDINATION; ETHYLENE POLYMERIZATION; LIGAND; alpha-diimine; COPOLYMERIZATION
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2018.03.032

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. [Display omitted] •Design and synthesis of two neutral N,N-ciano-iminopyriridine ligands.•Synthesis and characterization of air, thermal and light stable [(NN)Pd(CH3)]+X− complexes.•Exocyclic nitrile stabilizes intermolecularly Pd(II) complexes, avoiding the use of extra auxiliary ligands.•Complexes activate ethylene and 1-hexene, as single component catalyst and co-activated with B(C6F5)3.