Synthesis and catalytic activities of bimetallic Ru (II) arene complexes bearing bis-benzimidazoles

Abstract

In this study, bis-benzimidazole ligands (1a-d) were synthesized using linker groups and they were evaluated as catalyst generated in situ from [RuCl₂(p-cymene)]₂ for transfer hydrogenation (TH) of acetophenone. The bimetallic Ru (II) arene complex (2b) synthesized from ligand 1b which showed the best activity among the ligands in the catalytic TH reaction. The obtained ligands and 2b complex were characterized by ¹H- and ¹³C-NMR, elemental analysis and IR spectroscopy. The catalytic activities of complexes having different chain lengths and Y (CH₃ or H) groups were compared. The highest conversion (99%) was obtained with 2b.

0000-0002-7422-6593

Keywords

• Bis-benzimidazole,ruthenium,transfer hydrogenation

References

1. Referans1. Günnaz, S, Özdemir, N, Dayan, S, Dayan, O, Çetinkaya, B, 2011. Synthesis of Ruthenium(II) Complexes Containing Tridentate Triamine (′N ͡N ͡N′) and Bidentate Diamine Ligands (N ͡N′): as Catalysts for Transfer Hydrogenation of Ketones, Organometallics, 30(15): 4165-4173.
2. Referans2. Haneda, S, Adachi, Y, Hayashi, M. 2009. Copper(I)-2-(2′-pyridyl)benzimidazole catalyzed N-arylation of indoles, Tetrahedron, 65(50): 10459-10462.
3. Referans3. Haneda, S, Gan, Z, Eda, K, Hayashi, M. 2007. Ligand Effects of 2-(2-Pyridyl)benzazole−Pd Complexes on the X-ray Crystallographic Structures, 1H NMR Spectra, and Catalytic Activities in Mizoroki−Heck Reactions, Organometallics, 26(26): 6551-6555.
4. Referans4. Done, M, C, Ruther, T, Cavell, K, J, Kilner, M, Peacock, E. J, Braussaud, N, Skelton, B, W, White, A, J. 2000. Novel cationic and neutral Pd(II) complexes bearing imidazole based chelate ligands: synthesis, structural characterisation and catalytic behaviour, J. Organomet. Chem., 607(1): 78-92.
5. Referans5. Zhao, X, Liu, D, Li, Y, Cui, G. 2018. Two 3D cadmium (II) coordination polymers modulated by flexible bis(benzimidazole) ligands displaying high photocatalytic activities for degradation of methylene blue and methyl orange, Polyhedron, 156(1): 200-207.
6. Referans6. Aksenov, A, V, Smirnov, A, N, Aksenov N, A, Bijieva, A, S, Aksenova, I, V, Rubin, M. 2015. Benzimidazoles and benzoxazoles via the nucleophilic addition of anilines to nitroalkanes, Org. Biomol. Chem., 13(14): 4289-4295.
7. Referans7. Zhang, D, Jiang, X, Yang, H, Martinez, A, Feng, M, Donga, Z, Gao, G. 2013. Acridine-based macrocyclic fluorescent sensors: self-assembly behavior characterized by crystal structures and a tunable bathochromic-shift in emission induced by H2PO4− via adjusting the ring size and rigidity, Org. Biomol. Chem., 11(20): 3375-3381.
8. Referans8. Liu, Q, X, Wei, Q, Zhao, X, J, Wang, H, Li, S, J, Wang, X, G. 2013. Cobalt(II), copper(II), zinc(II) and cadmium(II) complexes based on dibenzimidazolyl bidentate ligands with alkanyl linkers: crystal structure, weak interactions and conformations, Dalton Trans., 42(16): 5902-5915.

9. Referans9. Iaroshenko, V, O, Ostrovskyi, D, Miliutina, M, Maalik, A, Villinger, A, Tolmachev, A, Volochnyuk, D, M, Langer, P. 2012. Design and Synthesis of Polycyclic Imidazole‐Containing N‐ Heterocycles based on C-H Activation/Cyclization Reactions, Adv. Synth. Catal., 354(13): 2495-2503.
10. Referans10. Kucukbay, H, Yilmaz, U, Sireci, N, Onganer, A, N. 2011. Synthesis and antimicrobial activities of some bridged bis-benzimidazole derivatives, Turk. J. Chem., 35(4): 561-571.
11. Referans11. Wang, D, E, Deng, K, J, Lv, K, L, Wang, C, G, Wen, L, L, Li, D, F. 2009. Structures, photoluminescence and photocatalytic properties of three new metal–organic frameworks based on non-rigid long bridges, CrystEngComm, 11(7): 1442-1450.
12. Referans12. Wong, W, W, H, Vickers, M, S, Cowley, A, R, Paul, R, L, Beer, P, D. 2005. Tetrakis(imidazolium) macrocyclic receptors for anion binding, Org. Biomol. Chem., 3(23): 4201-4208.
13. Referans13. Ma, J, F, Liu, J, F, Liu, Y, C, Xing, Y, Jia, H, Q, Lin, Y, H. 2000. Two new coordination polymers of Co(II) with 1,1′-(1,4-butanediyl)bis(benzimidazole), New J. Chem., 24(10): 759-763.
14. Referans14. Shi, Z, Thummel, R, P. 1995. N,N'-Bridged Derivatives of 2,2'-Bibenzimidazole, J. Org. Chem., 60(18): 5935-5945.
15. Referans15. Shi, Z, Thummel, R, P. 1995. Bridged dibenzimidazolinylidenes as new derivatives of tetraaminoethylene, Tetrahedron Lett., 36(16): 2741-2744.
16. Referans16. Dayan, O, Özdemir, N, Şerbetci, Z, Dinçer, M, Çetinkaya, B, Büyükgüngör, O. 2012. Synthesis and catalytic activity of ruthenium(II) complexes containing pyridine-based tridentate triamines (NNN) and pyridine carboxylate ligands (NO), Inorg. Chim. Acta, 392(1): 246-253.
17. Referans17. Noyori, R, Hashiguchi, S. 1997. Asymmetric Transfer Hydrogenation Catalyzed by Chiral Ruthenium Complexes, Acc. Chem. Res., 30(2): 97-102.
18. Referans18. Gao, J, X, Ikariya, T, Noyori, R. 1996. A Ruthenium(II) Complex with a C2-Symmetric Diphosphine/Diamine Tetradentate Ligand for Asymmetric Transfer Hydrogenation of Aromatic Ketones, Organometallics, 15(4): 1087-1089.