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Öğe Synthesis of N-heterocyclic carbene-palladium-PEPPSI complexes and their catalytic activity in the direct C-H bond activation(Elsevier Science Sa, 2018) Kaloglu, Nazan; Kaloglu, Murat; Tahir, Muhammad Nawaz; Arici, Cengiz; Bruneau, Christian; Doucet, Henri; Dixneuf, Pierre H.; Cetinkaya, Bekir; Ozdemir, IsmailA series of benzimidazolium salts having their two nitrogen atoms substituted by bulky groups have been synthesized. The benzimidazolium salts were readily converted into the corresponding palladium-NHC-PEPPSI complexes with general formula [PdBr2(NHC) (Py)], (NHC = N-heterocyclic carbene; PEPPSI = pyridine-enhanced precatalyst preparation, stabilisation, and initiation). The structures of all new compounds were characterized by NMR, IR spectroscopy and microanalysis techniques, which support the proposed structures. The molecular structure of complex 2g was determined by singlecrystal X-ray diffraction study. Next, the palladium-NHC-PEPPSI complexes were used as catalysts in the direct C5-arylation of 1-methylpyrrole-2-carboxaldehyde by aryl halides. These complexes exhibited moderate to high catalytic activities and gave C-H activation selectively at the C5-position of 1methylpyrrole- 2-carboxaldehyde. Both electron-donating and electron-withdrawing substituents were well tolerated with catalytic systems based on these complexes, even non-activated aryl chlorides such as chlorobenzene or 4-chlorotoluene were coupled with pyrrole in moderate yields. (C) 2017 Elsevier B.V. All rights reserved.Öğe Synthesis, Characterization and Catalytic Activity of New N-Heterocyclic Bis(carbene)ruthenium Complexes(Wiley-V C H Verlag Gmbh, 2009) Ozdemir, Ismail; Demir, Serpil; Gurbuz, Nevin; Cetinkaya, Bekir; Toupet, Loic; Bruneau, Christian; Dixneuf, Pierre H.The reaction of RuCl2(PPh3)(3) with tBuOK-deprotonated ortho-xylyl-bis(N-imidazolinium) salts 1a-d yields RuCl2(PPh3)[bis(imidazolidin-2-ylidene)] complexes (2a-d). Under similar conditions, [RuCl2(p-cymene)](2) leads to the ruthenium complex 3 containing a tridentate eta(6)-arene-dicarbene ligand. All synthesized compounds were characterized by elemental analysis and NMR spectroscopy, and the molecular structures of 2a, 2b and 3 were determined by X-ray crystallography. The catalytic activity of RuCl2(PPh3)[bis(imidazolidin-2-ylidene)] complexes 2a-b was evaluated in the direct arylation of 2-phenylpyridine with chlorobenzene derivatives. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)