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Öğe 1, 1',3,3'-tetraalkyl-2,2'-biperimidinylidenes: Unexpected substituent effects on the reactivity of carbon-carbon double bond(2003) Alici B.; Hökelek T.; Çetinkaya E.; Çetinkaya B.C2 deprotonation of 1, 3-dibutylperimidinium bromide (1a) with sodium hydride and a catalytic amount of potassium tert-butoxide in dry THF led to the formation of the exceptionally inert tetraaminoalkene 2a. In contrast, isostructural tetrakis(2-methoxyethyl)-tetraaminoalkene (2b) instantaneously reacted with O2 to yield urea 3b, and silver nitrate was readily reduced with 2b to form a silver mirror. Compound 2a has been characterized by X-ray diffraction studies; the naphtho-pyrimidine skeleton imposes structural constraints and some rigidity to the C=C bonding. © 2003 Wiley Periodicals, Inc.Öğe [1,3-Bis(2,3,4,5,6-pentafluorobenzyl)-benzimodazol-2-ylidene] bromido(?4-cyclo-octa-1,5-diene)rhodium(I)(International Union of Crystallography, 2007) Dinçer M.; Özdemir N.; Gülcemal G.; Çetinkaya B.The title complex, [RhBr(C8H12)(C21H8N2F10)], has a slightly distorted pseudo-square-planar geometry. The whole molecule has an approximate mirror symmetry, with the mirror plane passing through the mid-points of the two alkene bonds of the cycloocta-1,5-diene (COD) ligand. The average Rh - C(COD) distance is inversely related to the magnitude of the Rh - C(benzimidazole) distance in this type of compound. The mol-ecules are stacked in columns running along the a axis. The crystal structure contains two types of inter-molecular C - H?F inter-actions, as well as two weak ?-? stacking inter-actions. © International Union of Crystallography 2007.Öğe [1,3-Bis(2-ethoxyphenyl)imidazolidin-2-ylidene]bromo(cycloocta-1,5-diene) rhodium(I)(2005) Dinçer M.; Özdemir N.; Günay M.E.; Çetinkaya B.; Büyükgüngör O.The title complex, [RhBr(C8H12)(C19H 22N2O2)], has a distorted square-planar geometry. There are two molecules, A and B, in the asymmetric unit. The Rh-C bond distance between the N-heterocyclic ligand and the metal atom is 2.039 (2) Å in molecule A and 2.042 (2) Å in molecule B. The angle between the carbene heterocycle and the coordination plane is 87.56 (12)° in molecule A and 87.03 (11)° in molecule B. It is shown that the average Rh-C(COD) (COD is cyclooctadiene) distance is linearly dependent on the Rh-C(imidazolidine) distance in this type of compound. This can be ascribed to the steric hindrance produced by the packing. The crystal structure contains intramolecular C-H?O and intermolecular C-H?Br interactions. © 2005 International Union of Crystallography.Öğe {1,3-Bis(3,4,5-trimethoxy-benz-yl)-3,4,5,6-tetra-hydro-pyrimidin-2-yl- idene}chloro(n4-cyclo-octa-1,5-diene)rhodium(I)(2007) Arslan H.; VanDerveer D.; Özdemir I.; Demir S.; Çetinkaya B.In the title complex, [RhCl(C8H12)(C24H32N2O6)], the Rh atom is coordinated by a Cl atom, one C atom of the tetrahydropyrimidine ring and the two double bonds of cyclo-octa-diene. Each of the tetra-hydro-pyrimidine and cyclo-octa-diene rings is puckered. © International Union of Crystallography 2007.Öğe 1,3-Bis(thio-phen-2-ylmeth-yl)-3,4,5,6-tetrahydropyrimidinium trichlorido(µ6-pcymene)ruthenate(II)(2008) Arslan H.; Vanderveer D.; Özdemir S.; Gürbüz N.; Gök Y.; Çetinkaya B.The asymmetric unit of the title compound, (C14H17N2S2)[Ru(C10H14)Cl3], contains a 1,3-bis-(thio-phen-2-ylmeth-yl)-3,4,5,6-tetra-hydro-pyrimidinium cation and a trichlorido(µ6-p-cymene)ruthenate(II) anion. The Ru atom exhibits a distorted octa-hedral coordination with the benzene ring of the p-cymene ligand formally occupying three sites and three chloride atoms occupying the other three sites. The N - C bond lengths of the N - C - N unit of the pyrimidinium cation are shorter than the average single C - N bond length of 1.48 Å, thus showing double-bond character, indicating a partial electron delocalization within the N - C - N fragment. The pyrimidine ring has an envelope conformation. Four inter-molecular C - H?Cl hydrogen bonds generate a three-dimensional hydrogen-bonded framework.Öğe 1,3-Bis[4-(dimethyl-amino)benz-yl]-4,5,6,7-tetra-hydro-1H-1, 3-diazepan-2-ium chloride(2008) Arslan H.; Vanderveer D.; Gök Y.; Özdemir S.; Çetinkaya B.The title N-heterocyclic carbene derivative, C23H33N4 +· Cl-, has been synthesized and characterized by elemental analysis, 1H and 13C NMR, IR spectroscopy and a single-crystal X-ray diffraction study. Ions of the title compound are linked by three C - H?Cl inter-actions. The seven-membered 1,3-diazepane ring has a form inter-mediate between twist-chair and twist-boat.Öğe 1,4,5,6-tetrahydropyrimidinium halides ligands for Suzuki-Miyaura cross-coupling of unactivated aryl chlorides(2005) Alici B.; Özdemir I.; Gürbüz N.; Çetinkaya E.; Çetinkaya B.Four functionalized bis(1,4,5,6-tetrahyropyrimidinium) salts (2a-d) have been prepared and characterized by conventional spectroscopic methods and elemental analyses. A highly effective, easy to handle and environmentally benign process for palladium mediated Suzuki cross-coupling was developed. The in situ prepared three component system Pd(OAc)2 / bis(1,4,5,6-tetrahyropyrimidinium) bromides (2a-d) and Cs2CO 3 catalyses quantitatively the Suzuki cross-coupling of deactivated aryl chloride.Öğe 1-Ferrocenylmethyl-3-(2,4,6-tri-methyl-benzyl)-1H-imidazolidin-3-ium iodide and trans-bis-(3-benzyl-1-ferrocenylmethyl-1H-imidazolidin-2-yl-idene) diiodidopalladium(II)(2012) Daran J.-C.; Demirhan F.; Yldrm O.; Çetinkaya B.Owing to increasing inter-est in the use of N-heterocyclic carbenes (NHCs) based on imidazolidinium ions as ligands in the design of highly efficient transition-metal-based homogeneous catalysts, the characterizations of the 1-ferrocenylmethyl-3-(2,4,6-trimethyl-benzyl)imidazolidin-3-ium iodide salt, [Fe(C 5H 5)(C 19H 24N 2)]I, (I), and the palladium complex trans-bis-(3-benzyl-1-ferrocenylmethyl-1H- imidazolidin-2-yl-idene)diiodidopalladium(II), [Fe 2Pd(C 5H 5) 2(C 16H 17N 2) 2I 2], (II), are re-ported. Compound (I) has two iodide anions and two imidazolidinium cations within the asymmetric unit (Z' = 2). The two cations have distinctly different con-formations, with the ferrocene groups orientated exo and endo with respect to the N-heterocyclic carbene. Weak C-H donor hydrogen bonds to both the iodide anions and the ? system of the mesitylene group combine to form two-dimensional layers perpendicular to the crystallographic c direction. Only one of the formally charged imidazolidinium rings forms a near-linear hydrogen bond with an iodide anion. Complex (II) shows square-planar coordination around the Pd II metal, which is located on an inversion centre (Z' = 0.5). The ferrocene and benzyl substituents are in a trans-anti arrangement. The Pd-C bond distance between the N-heterocyclic carbene ligands and the metal atom is 2.036 (7) Å. A survey of related structures shows that the lengthening of the N-C bonds and the closure of the N-C-N angle seen here on metal complexation is typical of similar NHCs and their complexes. © 2012 International Union of Crystallography.Öğe 1-Pentamethylbenzyl-3-nbuthylbenzimidazolesilver(I)bromide complex: Synthesis, characterization and DFT calculations(Elsevier, 2014) Kunduracioglu A.; Tamer Ö.; Avci D.; Kani I.; Atalay Y.; Çetinkaya B.A novel NHC complex of silver(I) ion, 1-pentamethylbenzyl-3- nbuthylbenzimidazolesilver(I)bromide, was prepared and fully characterized by single crystal X-ray structure determination. FT-IR, NMR and UV-vis spectroscopies were employed to investigate the electronic transition behaviors of the complex. Additionally, the molecular geometry, vibrational frequencies, gauge including atomic orbital (GIAO) 1H and 13C chemical shift and electronic transition values of silver(I) complex were calculated by using density functional theory levels (B3LYP and PBE1PBE) with LANL2DZ basis set. Also, the vibrational frequencies were supported on the basis of the potential energy distribution (PED) analysis calculated for PBE1PBE level. We were also investigated total static dipole moment (µ), the mean polarizability (aa), the anisotropy of the polarizability (??), the mean first-order hyperpolarizability (aa) of the title complex. Natural bond orbital (NBO) analysis was performed to determine the presence of hyperconjugative interactions, and charge distributions.Öğe The 1:1 co-crystallization of enantiomers of an arene-tethered and ortho-metallated N-heterocyclic carbene ruthenium(II) half-sandwich complex: Synthesis, structural characterization and theoretical study(2008) Karabiyik H.; Kilinçarslan R.; Aygün M.; Çetinkaya B.; García-Granda S.The reaction of [RuCl2(p-cymene)]2 with in situ deprotonated NHC precursor 1,3-bis(biphenyl-2-yl)imidazolinium chloride was carried out in p-xylene at 140 °C to produce {A figure is presented}2, in which the NHC moiety acts as a tridentate C,C',C''-ligand. The complex 2 was characterized by NMR spectroscopy and X-ray crystallographic study. Crystallographic analysis combined with computational study regarding the compound, 1-[?6-(2'-biphenyl)]-3-[2-phenyl-1,2-phenylene]imidazolidin-2-ylidenechlororuthenium(II), 2, reveals that its metal-centered enantiomers are co-crystallized in 1:1 ratio and NHC frame possessing a tridentate coordination mode consists of ?-donation of the carbene carbon, ?6-arene tethering of terminal biaryl and ?1-coordination of the biphenyl ring at 2-position. Enantiomers of the complex are packed as asymmetric dimers in solid state formed by C-H?Cl type weak H-bonds and C-H?? type interactions giving rise to asymmetric chains. Both interactions serve to stabilization of the extended structure. © 2007 Elsevier Masson SAS. All rights reserved.Öğe (2,6-Bis{1-[4-(dimethyl-amino)phenyl-imino]eth-yl}-pyridine) -dichlorido-(tri-phenyl-phosphine-P)ruthenium(II): a zigzag chain of fused centrosymmetric R2 2(12) rings(2007) Özdemir N.; Dinçer M.; Dayan O.; Çetinkaya B.The title compound, [RuCl2(C25H29N5)(C18H15P)], a transfer hydrogenation catalyst, is supported by an N,N',N''-tridentate pyridine-bridged ligand and triphenyl-phosphine. The RuII centre is six-coordinated in a distorted octa-hedral arrangement, with the two Cl atoms located in the axial positions, and the pyridine (py) N atom, the two imino N atoms and the triphenyl-phosphine P atom located in the equatorial plane. The two equatorial Ru - Nimino distances (mean 2.093 Å) are substantially longer than the equatorial Ru - Npy bond [1.954 (4) Å]. It is observed that the Nimino - M - Npy bond angle for the five-membered chelate rings of 2,6-bis(imino)pyridine-based complexes is inversely related to the magnitude of the M - Npy bond. The title structure is stabilized by intra- and inter-molecular C - H?Cl hydrogen bonds, as well as by intra-molecular ?-? stacking inter-actions between the aromatic rings belonging to the triphenyl-phosphine ligand and the dimethyl-amino-phenyl fragment. The inter-molecular hydrogen bonds form an R 2 2(12) ring and a zigzag chain of fused centrosymmetric rings running parallel to the [100] direction. © International Union of Crystallography 2007.Öğe 2-(4-Pyridyl)-1,3-di(4-picolyl)imidazolidine(2010) Yigit B.; Yigit M.; Özdemir I.; Çetinkaya B.; Çetinkaya E.The title compound was prepared by treatment of N,N'-di(4-picolylamino)ethane with N,N-dimethylformamide dimethylacetal in toluene and it was characterized by elemental analysis, 1H NMR and 13C NMR. © 2010 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.Öğe (2Z,6Z)-N 2,N 2'-Bis(2,6-diisopropylphenyl)-N 1,N 1'-bis-(2-methoxyethyl)pyridine-2,6- dicarboxamidine(2008) Dinçer M.; Özdemir N.; Dayan O.; Çetinkaya B.In the title compound, C37H53N5O2, the benzene rings make dihedral angles of 84.61 (8) and 67.10 (9)° with the pyridine ring. The crystal structure is stabilized by strong intra-molecular inter-actions. The two (2-methoxyethyl)amine groups are disordered over two positions; the site occupancies are ca 0.6 and 0.4. © International Union of Crystallography 2008.Öğe ?6-mesityl,?1-imidazolinylidene-carbene- ruthenium(II) complexes: Catalytic activity of their allenylidene derivatives in alkene metathesis and cycloisomerisation reactions(2003) Çetinkaya B.; Demir S.; Özdemir I.; Toupet L.; Sémeril D.; Bruneau C.; Dixneuf P.H.The reaction of electron-rich carbene-precursor olefins containing two imidazolinylidene moieties [(2,4,6- Me3C6H2CH2)NCH2 CH2N(R)C=]2 (2a: R = CH2CH2OMe, 2b R = CH2Mes), bearing at least one 2,4,6-trimethylbenzyl (R = CH2Mes) group on the nitrogen atom, with [RuCl2(arene)]2 (arene = p-cymene, hexamethylbenzene) selectively leads to two types of complexes. The cleavage of the chloride bridges occurs first to yield the expected (carbene) (arene)ruthenium(II) complex 3. Then a further arene displacement reaction takes place to give the chelated ?6-mesityl,?1-carbene - ruthenium complexes 4 and 5. An analogous ?6-a- rene,?1-carbene complex with a benzimidazole frame 6 was isolated from an in situ reaction between [RuCl2(p-cymene)]2, the corresponding benzimidazolium salt and cesium carbonate. On heating, the RuCl2(imidazolinylidene) (p-cymene) complex 8, with p-methoxybenzyl pendent groups attached to the N atoms, leads to intramolecular p-cymene displacement and to the chelated ?6-arene,?1-carbene complex 9. On reaction with AgOTf and the propargylic alcohol HC?CCPh2OH, compounds 4-6 were transformed into the corresponding ruthenium allenylidene intermediates (4 › 10, 5 › 11, 6 › 12). The in situ generated intermediates 10-12 were found to be active and selective catalysts for ring-closing metathesis (RCM) or cycloisomerisation reactions depending on the nature of the 1,6-dienes. Two complexes [RuCl2- [?1CN(CH2C6H2 Me3-2,4,6)CH2CH2N- (CH2CH2OMe)}(C6Me6)] 3 with a monodentate carbene ligand and [RuCl2{?1- CN[CH2(?6-C6H2 Me3-2,4,6)]CH2CH2N- (CH2C6H2Me3-2,4,6)}] 5 with a chelating carbene-arene ligand were characterised by X-ray crystallography.Öğe Access to 3-Methyl-4-methylene-N-tosylpyrrolidine and 3,4-Dimethyl-N-tosylpyrroline by Ruthenium-Catalyzed Cascade Cycloisomerization/Isomerization Reactions(Wiley-VCH Verlag, 2004) Özdemir I.; Çetinkaya E.; Çetinkaya B.; Çiçek M.; Sémeril D.; Bruneau C.; Dixneuf P.H.New RuCl2(benzimidazole)(arene) complexes have been prepared. Upon reaction with 1,1-diphenylprop-2-ynol they generate catalyst precursors which perform the cycloisomerization of diallyltosylamide into 3-methyl-4-methylene-N-tosylpyrrolidine. The presence of N-(2,4,6-trimethylbenzyl)benzimidazole as ligand leads to a subsequent isomerization and gives the 3,4-dimethyl-N-tosylpyrroline. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.Öğe (Acetonitrile){2,6-bis-[1-(2,4,6-tri-methyl-phenyl-imino)-ethyl]-pyridine} -dichlorido-ruthenium(II) dichloro-methane solvate(2007) Özdemir N.; Dinçer M.; Dayan O.; Çetinkaya B.In the title compound, [RuCl2(C2H3N)(C27H31N3)]·CH2Cl2, the Ru II ion is six-coordinated in a distorted octa-hedral arrangement, with the two Cl atoms located in the apical positions, and the pyridine (py) N atom, the two imino N atoms and the acetonitrile N atom located in the basal plane. The two equatorial Ru - Nimino distances are almost equal (mean 2.087 Å) and are substanti-ally longer than the equatorial Ru - Npy bond [1.921 (4) Å]. It is observed that the Nimino - M - Npy angle for the five-membered chelate rings of pyridine-2,6-diimine complexes is inversely related to the magnitude of the M - Npy bond. The title structure is stabilized by intra- and inter-molecular C - H?Cl hydrogen bonds, as well as by van der Waals inter-actions. © International Union of Crystallography 2007.Öğe Annulated N-heterocyclic carbene ligands derived from 2- methylaminopiperidine: Their complexes and catalytic applications(2008) Turkmen H.; Pape T.; Hahn F.E.; Çetinkaya B.A new type of carbene precursor, 1,5,6,7,8,8a-hexahydroimidazo[1,5-a] pyridine (1), has been prepared from 2-(aminomethyl)piperidine and N,N-dimethylformamide dimethylacetal. The reactions of three imidazolidinium salts with [Rh(acac)(COD)] and [Ir(µ-OMe)(COD)]2 were found to afford rhodium and iridium complexes of N-heterocyclic carbenes, respectively. These complexes have been tested as catalysts in the transfer hydrogenation of cyclohexanone and acetophenone using 2-propanol as hydrogen source. © 2008 American Chemical Society.Öğe Aqueous-phase Suzuki–Miyaura cross-coupling reactions catalyzed by Pd-NHC complexes(2009) Türkmen H.; Can R.; Çetinkaya B.Cleavage reactions of [PdBr2(NHC)]2 with two equiv. of pyridine derivatives (L), having one or two carboxylic acid groups [L = NC5H4-2-COOH, NC5H4-3-COOH, NC5H4-4-COOH, or NC5H3-2,6-(COOH)2 in chloroform or DMSO, respectively, afforded the monomeric mixed ligand complexes trans-[PdBr2(NHC)L] (1–4) which, due to deprotonation of the carboxylic acid functionality, are water soluble in KOH. The catalytic activity of complexes 1–4 in aqueous Suzuki–Miyaura cross-coupling reactions were evaluated and compared. The dicarboxylic functionality enhances the catalyst reactivity and stability and the carboxylate derived from 4 could be easily recovered and reused for several cycles under the mild reaction conditions. © 2009 The Royal Society of Chemistry.Öğe Biosorption of Ce(III) onto modified Pinus brutia leaf powder using central composite design(2012) Kütahyali C.; Sert S.; Çetinkaya B.; Yalçintaş E.; Acar M.B.The biosorption of Ce(III) from aqueous solution by citric acid-modified Pinus brutia leaf powder was studied in a batch system as a function of initial pH, temperature, initial concentration of adsorbate, and contact time. Central composite design method was used in the experiments. Thermodynamic parameters such as standard enthalpy (?H 0), entropy (?S 0), and free energy (?G 0) were calculated, and the results indicated that biosorption was exothermic. The biosorption of Ce(III) on modified Pinus brutia leaf powder was investigated by Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) isotherms. The results show that Ce(III) adsorption can be explained by Langmuir isotherm model, and monolayer capacity was found as 62.1 mg/g. The results suggested that the modification process enhances the biosorption capacity of the adsorbent, and modified Pinus brutia leaf powder may find promising applications for the recovery of Ce(III) from aqueous effluents. © Springer-Verlag 2011.Öğe Bis{2,6-bis-[1-(4-fluoro-phenyl-imino)-eth-yl]pyridine}- 1?3 N,N',N'';3?3 N,N',N''-di-µ-chlorido-1:2?2 Cl:Cl;2?:3?2 Cl:Cl-trichlorido-1?Cl,2?Cl, 3?Cl-2-copper(I)-1,3-dicopper(II)(2008) Özdemir N.; Dinçer M.; Dayan O.; Çetinkaya B.The title complex, [Cu3Cl5(C21H 17N3F2)2], is the first reported copper trimer including both CuI and CuII ions. The two CuII ions are five-coordinate in a significantly distorted square-pyramidal arrangement, with the bridging Cl atom located in the apical position, and the pyridine (py) N atom, the two imine N atoms and the other Cl atom located in the basal plane. The CuI ion is in a trigonal planar configuration surrounded by three Cl atoms. The structure is stabilized by intra- and inter-molecular C - H?Cl and C - H??(py) hydrogen bonds. © 2008 International Union of Crystallography.