Ruthenium(η⁶,η¹-arene-CH₂-NHC) Catalysts for Direct Arylation of 2-Phenylpyridine with (Hetero)Aryl Chlorides in Water

• Published in: Molecules (Basel, Switzerland) Switzerland), 2018-03, Vol.23 (3), p.647
• Main Authors: Kaloğlu, Nazan, Özdemir, İsmail, Gürbüz, Nevin, Arslan, Hakan, Dixneuf, Pierre H
• Format: Article
• Language: English
• Subjects: 2-phenylpyridine; Aromatic compounds; Benzimidazoles; Catalysts; Catalytic activity; Chemical Sciences; Chlorides; Crystal structure; direct arylation; Fourier transforms; Halides; homogeneous catalysis; Infrared analysis; Infrared spectroscopy; N-heterocyclic carbene; NMR; Nuclear magnetic resonance; Ruthenium; Ruthenium compounds; single crystal structure; Single crystals
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules23030647

A series of new benzimidazolium halides were synthesized in good yields as unsymmetrical -heterocyclic carbene (NHC) precursors containing the N-CH₂-arene group. The benzimidazolium halides were readily converted into ruthenium(II)-NHC complexes with the general formula [RuCl₂(η⁶,η¹-arene-CH₂-NHC)]. The structures of all new compounds were characterized by ¹H NMR (Nuclear Magnetic Resonance), C NMR, FT-IR (Fourier Transform Infrared) spectroscopy and elemental analysis techniques. The single crystal structure of one benzimidazole ruthenium complex, , was determined. The complex is best thought of as containing an octahedrally coordinated Ru center with the arene residue occupying three sites, the remaining sites being occupied by a (carbene)C-Ru bond and two Ru-Cl bonds. The catalytic activity of [RuCl₂(η⁶,η -arene-CH₂-NHC)] complexes was evaluated in the direct (hetero)arylation of 2-phenylpyridine with (hetero)aryl chlorides in water as the nontoxic reaction medium. These results show that catalysts and were the best for monoarylation with simple phenyl and tolyl chlorides. For functional aryl chlorides, , , and appeared to be the most efficient.