- N, N′-Olefin functionalized Bis-Imidazolium Pd(II) chloride N-Heterocyclic carbene complex builds a supramolecular framework and shows catalytic efficacy for 'C-C' coupling reactions
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The ligand 3,3′-(p-phenylenedimethylene)bis{1-(2-methylallyl)} imidazolium bromide (1) and its Palladium(II) N-heterocyclic carbene (NHC) complex (3) has been synthesized and characterized by several spectroscopic techniques and the solid-state structure of 3 has been determined by single crystal X-ray diffraction studies. The Pd(II) complex possesses ring head to tail π- π stacking interactions (3.767 A ) through imidazole rings. Complex 3 catalyzes Suzuki-Miyaura 'C-C' coupling reaction. DFT calculations have been used to understand the HOMO/LUMO energy and hence the stability and reactivity of Pd(II) complex in syn and anti-configuration.
- Roymahapatra, Gourisankar,Samanta, Tapastaru,Seth, Saikat Kumar,Mahapatra, Ambikesh,Chattopadhyay, Shyamal Kumar,Dinda, Joydev
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- Palladium(II) chloro complexes with (RS)-1-(4-chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)pentan-3-ol
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Palladium(II) chloro complexes with (RS)-1-(4-chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-tria-zol-1-ylmethyl)pentan-3-ol (L), such as trans-[PdCl2L2], cis-[PdCl2L2], and trans-[Pd2(μ-Cl)2Cl2L2], were synthesized. The structures of their coordination cores and the coordination modes of the reagent to the metal ion via the N(4) atom of the triazole ring were established by electronic, IR, and 1H and 13C NMR spectroscopy. The ratio of RS- and RR(SS)-diastereomers in the complexes was determined from the complete assignment of signals in their 1H and 13C NMR spectra.
- Khisamutdinov,Shitikova,Anpilogova,Golubyatnikova,Mulagaleev,Murinov
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- Structure of Cu(II) and Pd(II) complexes with 2-(2,2-dimethylhydrazone)pentanone-4
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Palladium(II) and copper(II) complexes with 2-(2,2-dimethylhydrazone) pentanone-4 are synthesized for the first time. The compounds are characterized by IR and NMR spectroscopy, elemental and single crystal X-ray diffraction analyses. The palladium complex crystallizes in the space group I41/a; the copper complex crystallizes in the space group P1?. Both compounds are molecular; the palladium chelate core has a distorted square geometry and that of copper has a distorted tetrahedral geometry. The average M–O and M–N bond lengths are respectively 1.9808(15) ? and 2.0427(17) ? for M = Pd, 1.915(8) ? and 1.97(1) ? for M = Cu. The chelate O–M–N angles are 88.32(7)-91.67(7)° for M = Pd, 93.37(4)-99.02(5)° for M = Cu.
- Kuratieva,Vikulova,Shushanyan,Nikolaeva,Dorovskikh,Mikhaleva,Morozova
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- Classical and non-classical redox reactions of Pd(ii) complexes containing redox-active ligands
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Reactivity studies of a Pd(ii)-verdazyl complex reveal novel ligand-centred reduction processes which trigger pseudo-reductive elimination at Pd. Reaction of the complex with water induces a ligand-centred redox disproportionation. The reduced verdazyl ligands can also be reversibly protonated. This journal is
- Sanz, Corey A.,Ferguson, Michael J.,McDonald, Robert,Patrick, Brian O.,Hicks, Robin G.
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- Photolysis of tetraphenylcyclobutadiene palladium chloride induced by LMCT excitation
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The complex tetraphenylcyclobutadiene palladium(IV) chloride shows a longest-wavelength absorption at λmax = 530 nm which is assigned to a LMCT transition from the C4Ph4 dianion to Pd(IV). LMCT excitation leads to the release of Pd(CH3CN) 2Cl2 and neutral C4Ph4 which dimerizes to octaphenylcyclooctatetraene.
- Kunkely, Horst,Vogler, Arnd
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- STUDY ON THE MECHANISM OF ETHYLENE OXIDATION BY A NITRITE COMPLEX OF PALLADIUM IN CHLOROFORM MEDIUM.
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A detailed mechanism of ethylene oxidation by a palladium nitrite complex Pd(NO//2)Cl(CH//3CN)//2 in chloroform solution is studied using IR and **1H NMR spectroscopy. Kinetic and spectral data obtained indicate the formation of a number of intermediates. The structure and routes of decomposition of the intermediates to end products are suggested.
- Gusevskaya,Beck,Stepanov,Likholobov,Nekipelov,Yermakov,Zamaraev
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- Flexible cofacial binuclear metal complexes derived from α,α-bis(salicylimino)-m-xylene
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The tetradentate Schiff-base ligand SIXH2 (α,α-bis(salicylimino)-m-xylene), prepared from salicylaldehyde and m-xylylenediamine, forms cofacial binuclear complexes with Pd and Cu. Of the two isomers possible (trans-syn and trans-anti) for M2(SIX) 2, these complexes crystallize exclusively as the trans-anti isomer. In ansolvous Pd2(SIX)2, the metal-containing planes are approximately parallel, with Pd ... Pd 4.416(1) A. Pd 2(SIX)2 also forms a crystalline solvate, in which the molecules adopt a more open conformation with longer metal-metal distances (5.109(1) and 5.112(1) A). The M ... M distance is significantly longer in Cu2(SIX)2 (6.653(1) A), because of conformational changes in the m-xylylene moieties and substantial tetrahedral distortion about Cu.
- Maverick, Andrew W.,Laxman, Ravi K.,Hawkins, Mark A.,Martone, Daniel P.,Fronczek, Frank R.
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- N-donor complexes of palladium as catalysts for Suzuki cross-coupling reactions in ionic liquids
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Palladium imidazole complexes have been used as catalyst precursors for the Suzuki cross-coupling reaction in 1-butyl-3-methylimidazolium-based ambient temperature ionic liquids. The system provides a stable, recyclable method for iodo- and bromoarenes. The preferred reaction conditions are explored and the effect of changing the ionic liquid components is investigated.
- Mathews, Christopher J.,Smith, Paul J.,Welton, Tom
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- Trimeric cage complexes of platinum group and coin metals
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The treatment of cis,cis-1,3,5-tris(diphenylphosphinomethyl)cyclohexane (tdppmcy) with Rh(CO)Cl(PPh3)2, MCl2L 2 (M = Pd, Pt; L = PhCN, MeCN), Pt(CN)2, AgBF4, or Au(Cl)PPh3 in a stoichiometric ratio of 2:3 affords the trimeric macrocyclic cage compounds [M]3(tdppmcy)2 {[M] = trans-Rh(CO)Cl (2), trans-PdCl2 (3), trans-Pt(CN)2 (4b), Ag+ (5), and AuCl (6)} in good yields. Only when PtCl 2(PhCN)2 was used as complex precursor, the formation of coordination polymers was observed. NMR spectroscopy in solution as well as single-crystal X-ray diffraction analyses demonstrate that in all cases two tdppmcy ligands coordinate three metal fragments exclusively in trans fashion. Copyright
- Stickel, Marc,Maichle-Moessmer, Caecilia,Mayer, Hermann A.
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- A Titanium(III)-Catalyzed Reductive Umpolung Reaction for the Synthesis of 1,1-Disubstituted Tetrahydroisoquinolines
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A catalytic reductive C1-acylation of 3,4-dihydroisoquinolines is presented that gives direct access to 1,1-disubstituted tetrahydroisoquinolines. The reaction is a titanium(III)-catalyzed reductive umpolung process in which nitriles act as effective acylation agents. The method is highly chemo- and regioselective and is demonstrated in 20 examples. It is well-suited for the large-scale synthesis of functionalized tetrahydroisoquinoline products, which is exemplified in the form of a six-step synthesis of (±)-3-demethoxyerythratidinone. (Figure Presented).
- Luu, Hieu-Trinh,Wiesler, Stefan,Frey, Georg,Streuff, Jan
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- A supramolecular recyclable catalyst for aqueous Suzuki-Miyaura coupling
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A water-soluble, supramolecular catalytic system has been designed based on inclusion complexation between a hydrophobic palladium(ii)-dipyrazole complex bearing an adamantyl (Ad) molecular recognition moiety and a complementary, hydrophilic β-cyclodextrin (β-CD) derivative. The single-crystal molecular structure of the Pd(ii) complex was determined and its host-guest inclusion complexation with heptakis(2,6-di-O-methyl)-β-CD (dmβ-CD) in an aqueous medium was confirmed by 2D NOESY 1H NMR spectroscopy. The catalyst showed high activity for Suzuki-Miyaura coupling of hydrophilic aryl bromides with aryl boronic acids in aqueous organic solvents. In the presence of n-Bu4NBr as a stabilizer, the catalyst-containing reaction solution can be recycled and reused multiple times to catalyze the coupling reaction of fresh substrates once the product has been removed by centrifugation. This work demonstrates a supramolecular complex approach, non-covalently modifying a water insoluble metal complex to provide a water-soluble inclusion system to serve as a recyclable catalyst for potential application in green chemical synthesis. This journal is
- Qi, Miao,Tan, Pei Zi,Xue, Fei,Malhi, Haripal Singh,Zhang, Zhong-Xing,Young, David J.,Hor, T. S. Andy
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- Synthesis, structural, vibrational and DFT investigation of new binuclear molecular Pd–Cu and Cu–Cu complexes formed by Schiff base and hexafluoroacetylacetonate building blocks
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In this work, the first binuclear molecular noble metal-contained complex from the Schiff base (SB) and β-diketonate building blocks, viz. [Pd(acacen)Cu(hfac)2], has been synthesized and investigated in comparison with the homometallic binuclear analog [Cu(acacen)Cu(hfac)2]. The detailed comparative characterization of the structure of these new compounds as well as their molecular SB components [M(acacen)] was performed using crystallography, vibrational spectroscopy and DFT calculations. Experimental IR bands have been assigned based on DFT calculations. The Hirshfeld surface analysis was used as a tool for the better insight into intermolecular contacts. It was shown that despite both bimetallic complexes had similar molecular structure and packing style, the nature of the closest intermolecular contacts in [M(acacen)Cu(hfac)2] differed considerably. A topological analysis of the electron density distribution in [M(acacen)] and [M(acacen)Cu(hfac)2] complexes was carried out and the most probable paths of bond cleavage during decomposition of the compounds were revealed. The binding energies of the molecular components in binuclear complexes were also calculated.
- Basova, Tamara V.,Kovaleva, Evgenia A.,Krasnov, Pavel O.,Morozova, Natalya B.,Nikolaeva, Nataliya S.,Smolentsev, Anton I.,Sukhikh, Alexander A.,Vikulova, Evgeniia S.
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- Remarkable catalytic activity of [PdCl2(CH3CN) 2] in Suzuki-Miyaura cross-coupling reaction in aqueous media under mild conditions
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[PdCl2(CH3CN)2] (2 mol%) was found to be an efficient catalyst for the Suzuki-Miyaura cross coupling reaction between aryl bromide and aryl boronic acid in water solvent at 45 °C. The scope of the protocol was extended to various aryl bromides and aryl boronic acids. In general, an effective method has been developed for the Suzuki-Miyaura cross coupling reaction by using a phosphine-free Pd catalyst.
- Ganesamoorthy,Shanmugasundaram,Karvembu
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- Thermal behavior of volatile palladium(II) complexes with tetradentate Schiff bases containing propylene-diimine bridge
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Palladium(II) complexes with tetradentate Schiff bases, Pd(acacpda)(I) and Pd(acacdmpda)(II) (acacpda2?—N,N′-(propylene)-bis(acetylacetoneiminato-), acacdmpda2?—N,N′-(2,2-dimethylpropylene)-bis(acetylacetoneiminato-)), have been synthesized, purified and characterized by elemental analysis, IR and NMR spectroscopy. Complex I was obtained for the first time, and its solid-state structure was investigated by single-crystal X-ray diffraction. It has a discrete molecular structure with the Pd2+ ion being in a distorted square-planar coordination environment formed by N and O atoms of the acacpda2? ligand. The thermal properties of complexes I and II in condensed phase were investigated by thermogravimetry. Compound II transfers into the gas phase almost completely, while compound I evaporates with a partial decomposition. The temperature dependences of saturated vapor pressure were measured by the flow method in the temperature intervals (423–457) and (422–478) K for I and II, respectively. Both complexes were shown to exhibit an excellent stability upon sublimation. The thermodynamic parameters of sublimation processes were calculated to be: ΔsubH440 = (133 ± 4) kJ mol?1, ΔsubS4400= (210 ± 9) J (mol K)?1 for I, ΔsubH450 = (135 ± 1) kJ mol?1, ΔsubS4500= (218 ± 3) J (mol K)?1 for II. It has been found that the complex II with a more bulky Schiff base ligand possesses slightly higher vapor pressure values as compared to I, which is probably due to the lower contribution of weak intermolecular interactions occurring in the crystal structure of II.
- Vikulova, Evgeniia S.,Cherkasov, Sergey A.,Nikolaeva, Nataliya S.,Smolentsev, Anton I.,Sysoev, Sergey V.,Morozova, Natalya B.
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- Palladium(II) complexes of 2-pyridylmethylamine and 8-aminoquinoline: A crystallographic and DFT study
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Two nominally square planar palladium(II) chelates: dichloro-(2-aminomethylpyridine-N,N′)-palladium(II) ([Pd(L1)Cl2]) and dichloro-(8-aminoquinoline)-palladium(II) ([Pd(L2)Cl2]) have been synthesised and studied by X-ray crystallography and DFT methods. [Pd(L1)Cl2] crystallised in the monoclinic space group C2/c. In the solid state this compound exists as a one-dimensional supramolecular structure supported by N-HCl hydrogen bonds and metallophilic PdPd interactions. The same hydrogen bonding motif leads to a two-dimensional supramolecular structure in the case of [Pd(L2)Cl2]; this structure is devoid of metallophilic interactions. DFT simulations show that the planar geometry of [Pd(L1)Cl2] in the solid state is not the lowest energy conformation. An out-of-plane distortion of the methylene group leads to a structure ca. 11 kJ mol-1 lower in energy. The NBO partial charges provide insight into the stability of the hydrogen bonding motif. TD-DFT calculations were used to delineate the experimental UV-visible spectra.
- Akerman, Kate J.,Venter, Chané,Hunter, Leigh A.,Akerman, Matthew P.
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- Synthesis, crystal analysis and DFT calculations of Ni(II) and Pd(II) complexes of 3,3'-((1,2-phenylenebis(azanediyl))bis(2-oxoethane-2,1-diyl))bis(1-allyl-1H-imidazole-3-ium)
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Ni(II) and Pd(II) Complexes of 3,3'-((1,2-phenylenebis(azanediyl))bis(2-oxoethane-2,1-diyl))bis(1-allyl-1H-imidazole-3-ium) were synthesised in good yield and characterized by spectroscopic and X-ray diffraction techniques. These novel complexes, which are neutral in charge, possess square planar geometry where the coordination of the tetradentate ligand is through C2 of the imidazole moiety. These complexes are identified to be single cis-isomers as confirmed by 1H NMR and single crystal X-ray diffraction data. DFT/B3LYP calculations were also conducted using the theoretical model of the precursor heterocyclic ligand and Ni(II) and Pd(II) metal complexes. The results of these theoretical data which are calculated to be the structural parameters of optimized structures exhibited good agreement with those obtained from X-ray crystal diffraction analysis. Both metal complexes are subjected to further theoretical studies such as determination of the HOMO-LUMO gap, molecular electrostatic potential (MEP) and calculation of reactivity descriptors and the obtained results attest the superiority of these compounds as novel heterocyclic functional materials.
- Al-Azmi, Amal
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- Synthesis and redox chemistry of Pd(ii) complexes of a pincer verdazyl ligand
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A series of palladium(ii) complexes containing a redox-active, tridentate verdazyl ligand of general formula (verdazyl)PdL (L = Cl, CH3CN) are synthesized. The tetrazine core of tridentate verdazyl ligand 5 is flanked by two pyridyl groups, creating a geometry in which the ancillary ligand L is bound trans to the verdazyl ring in the square planar metal complexes. Pd(ii) complexes were isolated with the verdazyl ligand in either its neutral radical charge state (6: L = CH3CN, 12: L = Cl) or its closed-shell monoanionic charge state (10: L = CH3CN, 9: L = Cl). The charge state of the ligand was determined using X-ray crystallography and NMR, EPR, and IR spectroscopy. The cyclic voltammograms of radical complexes 6 and 12 each contain a reversible one-electron reduction wave and an irreversible one-electron oxidation wave. The complexes can be chemically interconverted between radical ligand (6, 12) and reduced, closed-shell anion (9, 10) using decamethylferrocene as the reductant and a mixture of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and fluoroboric acid as the oxidant.
- Sanz, Corey A.,Patrick, Brian O.,Hicks, Robin G.
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- Electrocatalytic reduction of carbon dioxide by substituted pyridine and pyrazole complexes of palladium
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A series of [PdCl2L2] complexes (L = substituted pyridine and pyrazole) has been tried as an electrocatalyst for the reduction of CO2 in acetonitrile (AN) containing 0.1 M tetraethylammonium perchlorate (TEAP) at glassy carbon or Pt electrodes. The complexes working as the catalyst were [PdCl2L2] (L = Pyrazole (Pyra), 4-Methylpyridine (4-Mpy) and 3-methylpyrazole (3-Mpyra)) at an applied potential of -1.10V vs Ag/10mM Ag+ and the reduction products were formic acid and H2 with no CO. The current efficiency for the formation of formic acid were 10, 20 and 10.2% for Pd complexes of Pyra, 4-Mpy and 3-Mpyra, respectively. The current efficiency for the hydrogen evolution were 31-54%, and the source of the formate proton and hydrogen was from the added water (4% by volume). Copyright
- Hossain, A. G. M. Mostafa,Nagaoka,Ogura
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- Silver(i), gold(i) and palladium(II) complexes of a NHC-pincer ligand with an aminotriazine core: A comparison with pyridyl analogues
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Dinuclear silver, di- and tetra-nuclear gold, and mononuclear palladium complexes with chelating C,N,C diethylaminotriazinyl-bridged bis(NHC) pincer ligands were prepared and characterised. The silver and gold complexes exist in a twisted, helical conformation in both the solution- and the solid state. In contrast, an analogous dinuclear gold complex with pyridyl-bridged NHCs exists in a linear conformation. Computational studies have been performed to rationalise the formation of twisted/helical vs. linear forms.
- Vaughan, Jamila,Carter, Damien J.,Rohl, Andrew L.,Ogden, Mark I.,Skelton, Brian W.,Simpson, Peter V.,Brown, David H.
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- Catalytic C–C cross-coupling and hydrogen evolution by two Pd(II)-complexes of di-2-pyridyl ketone benzoyl hydrazones
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The reactions between [PdCl2(CH3CN)2] and dpk-h [dpk-h = di-2-pyridyl ketone benzoyl hydrazone (dpkbh) or di-2-pyridyl ketone 4-aminobenzoyl hydrazone (dpk-4-abh)] at room temperature in air produced [PdCl2(κ3-Npy,Nim,O-dpkbh)] (1) and PdCl2(κ3-Npy,Nim,O-dpk-4-abh)] (2). X-ray structural analysis on a single crystal of PdCl(κ3-N,N,O-dpk-4-abh-H)]·H2O·dmf (3) established its authenticity, points to keto-enol tautomerization due to solvent-compound interactions and revealed pseudo-coordination of the carbonyl group to the Pd ion. Solid-state infrared measurements confirmed the pseudo coordination of the carbonyl group of dpk-h as evident from the appearance of the ν(C=O) of coordinated dpk-h in close proximity to the ν(C=O) of uncoordinated dpk-h. 1H NMR measurements on protophilic solutions of 1 and 2 disclosed solvent dependence and keto-enol tautomerization while variable temperature studies established the predominance of the keto form. The electronic absorption spectra of 1 and 2 measured in protophilic solvents confirmed the coordination of the Pd ion to dpk-h as evident from the appearance of d-d and ligand based electronic transitions. The catalytic C–C cross-coupling reactions and electro-catalytic behavior of 1 and 2 toward a proton reduction were investigated and revealed good catalytic properties. Overall rate constants (kapp) for the electrocatalytic H2 evolution of (3.39 ± 0.3) × 103 and (4.04 ± 0.2) × 103 M?1 s?1 were estimated and overpotentials of 157 and 67 mV, and turnover numbers (TON) of 2.0 and 3.2 for 1 and 2, respectively, were determined.
- Bakir, Mohammed,Lawrence, Mark W.,Nelson, Peter,Yamin, M. Bohari
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- Nitrile-functionalized pyridinium ionic liquids: Synthesis, characterization, and their application in carbon-carbon coupling reactions
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A series of relatively low-cost ionic liquids, based on the N-butyronitrile pyridinium cation [C3CNpy]+, designed to improve catalyst retention, have been prepared and evaluated in Suzuki and Stille coupling reactions. Depending on the nature of the anion, these salts react with palladium chloride to form [C3CNPy]2[PdCl4] when the anion is Cl- and complexes of the formula [PdCl 2(C3CNpy)2][anion]2 when the anion is PF6-, BF4-, or N(SO 2CF3)2-. The solid-state structures of [C3CNpy]Cl and [C3CNpy]2[PdCl4] have been established by single-crystal X-ray diffraction. The catalytic activity of these palladium complexes following immobilization in both N-butylpyridinium and nitrile-functionalized ionic liquids has been evaluated in Suzuki and Stille coupling reactions. All of the palladium complexes show good catalytic activity, but recycling and reuse is considerably superior in the nitrile-functionalized ionic liquid. Inductive coupled plasma spectroscopy reveals that the presence of the coordinating nitrile moiety in the ionic liquid leads to a significant decrease in palladium leaching relative to simple N-alkylpyridinium ionic liquids. Palladium nanoparticles have been identified as the active catalyst in the Stille reaction and were characterized using transmission electron microscopy.
- Zhao, Dongbin,Fei, Zhaofu,Geldbach, Tilmann J.,Scopelliti, Rosario,Dyson, Paul J.
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- Novel palladium imidazole catalysts for Suzuki cross-coupling reactions
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Novel palladium infidazole catalytic systems for the Suzuki cross-coupling reaction have been developed from commercially available and inexpensive imidazoles and palladium sources, and exhibit high activity and no homo-coupling.
- Mathews, Christopher J.,Smith, Paul J.,Welton, Tom
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- Synthesis, characterization and biological investigation of glycine-based sulfonamide derivative and its complex: Vibration assignment, HOMO – LUMO analysis, MEP and molecular docking
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A combined experimental and theoretical investigation has been reported on N-(glycine)-para styrene sulfonamide (abbreviated as GSS). The GSS and its complex were synthesized for first time in two steps. The GSS was synthesized from the reaction of para styrene sulfonyl chloride and glycine in the mild condition. The palladium complex was prepared from the reaction of PdCl2, CH3CN and GSS as a ligand. The GSS and its complex was confirmed using FT-IR and 1H-NMR spectra. The data obtained from wave number calculations are used to assign vibrational bands obtained in infrared and Raman spectra recorded. Potential energy distribution was done using GAR2PED program. HOMO-LUMO analysis, and Molecular Electrostatic Potential studies of the GSS and its complex have been investigated using DFT method. The GSS is investigated against Staphylococcus aureus and Escherichia coli. Molecular Docking study of GSS is also reported.
- Shafieyoon, Parvaneh,Mehdipour, Ebrahim,Mary, Y. Sheena
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- Preparation, characterization and evaluation of novel 1,3,5-triaza-7-phosphaadamantane (PTA)-based palladacycles as anti-cancer agents
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A series of novel mononuclear 1,3,5-triaza-7-phosphaadamantane (PTA)-based palladacycles were prepared by cleaving μ-Cl binuclear orthopalladated dimers of substituted benzylidene-2,6-diisopropylphenylamines. All complexes were fully characterized using IR and NMR spectroscopy, mass spectrometry as well as elemental analysis. In-vitro evaluation of the complexes as anti-cancer agents against the breast-cancer cell lines MCF7 and MDA-MB 231 as well the melanoma cell line ME1402 shows that four of the five complexes tested are active. These palladacycles exhibit their cytotoxicity by inducing DNA damage which subsequently triggers apoptosis. DNA binding studies using electrophoresis and spectroscopic techniques, such as UV-Vis and circular dichroism spectroscopy, confirms that the palladacycle, C2 definitely interacts with DNA. Results from these DNA binding experiments seem to rule out co-valent and intercalative binding, pointing rather to a non-covalent interaction, with electrostatic binding being the most likely possibility. It is envisioned that this would probably involve a hydrolysed or solvated derivative of C2.
- Blanckenberg,Aliwaini,Kimani,van Niekerk,Neumann-Mufweba,Prince,Mapolie
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- Carbazolyl-bis(triazole) and Carbazolyl-bis(tetrazole) Complexes of Palladium(II) and Platinum(II)
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The synthesis of several carbazole-bis(triazole) (CzTrR) and carbazole-bis(tetrazole) (CzTR) ligands (5a–d and 6a–d, respectively, where R=Me (a), i–Pr (b), Bz (c) and CH2-2,4,6-C6H2Me3 (d)) is reported. Reaction of these ligands with PdCl2 in refluxing acetonitrile affords the complete series of square planar complexes, Pd(CzTrR)Cl (7a–d) and Pd(CzTR)Cl (8a–d). The analogous platinum complexes are prepared by deprotonation of ligand carbazole nitrogen under nitrogen followed by reaction with Pt(COD)Cl2 to give Pt(CzTrR)Cl (9b, 9d) and Pt(CzTR)Cl (10b, 10d). The X-ray structure of several ligands (5b, 5c, 6c) and their metal complexes (8b, 8d, 9b) are reported. Complexes 7–10d were examined by cyclic voltammetry and DFT calculations to shed light on their electronic structures. The Pd and Pt complexes of the same ligand (CzTr: 7d, 9d; CzT: 8d, 10d) showed very similar oxidation potentials suggesting the lowest oxidation is ligand based. In contrast, oxidations of the tetrazole complexes 7d and 9d were notably more difficult than the triazole complexes 8d and 10d. Both of these observations are supported by DFT calculations that indicate the HOMO is essentially carbazole π-bonding in character.
- Samanta, Samya,Zheng, Cameron,Gajecki, Leah,Berg, David J.,Oliver, Allen G.,Crosby, Tristan,Godin, Logan,Sandhu, Jaylene
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- Electronic spectrum and photoreactivity of dichloro(1,5-cyclooctadiene)-palladium(II)
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The complex PdII(1,5-COD)Cl2 (1,5-COD = 1,5-cyclooctadiene) shows a long-wavelength ligand-to-metal charge transfer (LMCT) absorption at λmax = 342 nm. It is suggested that LMCT excitation generates a COD radical cation and PdICl2- in the primary photochemical step. In acetonitrile, a back-electron transfer takes place that leads to the transformation of 1,5-COD to its 1,3-isomer and a solvated Pd(II) complex. In ethanol, the COD radical cation and PdI are reduced by the solvent, which is oxidized to acetaldehyde. Metallic palladium is formed as a colloid.
- Kunkely, Horst,Vogler, Arnd
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- 7-azaindol-1-yl(organo)silanes and their PdCl2 complexes: Pd-capped tetrahedral silicon coordination spheres and paddlewheels with a Pd-Si axis
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Supported by excess triethylamine, 7-azaindole (HL) and dichlorodimethylsilane (Me2SiCl2), methyltrichlorosilane (MeSiCl3), and tetrachlorosilane (SiCl4) react, respectively, with formation of the 7-azaindol-1-yl-substituted silanes Me 2SiL2, MeSiL3, and SiL4. In these compounds the silicon atom adopts [4+2], [4+3], and [4+4] coordination, respectively, with the pyridine N atoms of the 7-azaindol-1-yl groups capping the tetrahedral Si coordination sphere from distances of >3 A. Two pyridine nitrogen atoms of these silanes replace the acetonitrile ligands of [PdCl2(NCMe)2], thus forming the complexes Me 2Si(μ-L)2PdCl2, MeSiL(μ-L) 2PdCl2, and SiL2(μ-L)2PdCl 2. In addition to capping of the silicon coordination sphere by the pyridine N atoms of the dangling 7-azaindol-1-yl groups (in MeSiL(μ-L) 2PdCl2 and SiL2(μ-L)2PdCl 2), these three palladium complexes exhibit capping of one tetrahedral face of the Si coordination sphere by the palladium atom (with Si···Pd separations of 3.34, 3.43, and 3.31 A, respectively). According to computational analyses, the paddlewheel complex ClSi(μ-L)4PdCl should be energetically favored over its isomer SiL2(μ-L)2PdCl2; however, isomerization into this paddlewheel compound requires higher temperatures (150 °C) or the addition of a Lewis acid (such as GaCl3).
- Wahlicht, Sven,Brendler, Erica,Heine, Thomas,Zhechkov, Lyuben,Wagler, Joerg
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- The synthesis and efficient one-pot catalytic "self-breeding" of asymmetrical NC(sp3)E-hybridised pincer complexes
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Cyclopalladation of the pyridyl-substituted chiral phosphine sulfide (N-P=S) and oxide (N-P=O) compounds afforded the asymmetric N-C(sp3)?-S and N-C(sp3)?-O pincer complexes. When applied as catalysts in asymmetric hydrophosphination, the newly developed aliphatic pincer catalyst could be recycled over three runs and obtained in large quantities via a one-pot "self-breeding" catalytic protocol.
- Yang, Xiang-Yuan,Tay, Wee Shan,Li, Yongxin,Pullarkat, Sumod A.,Leung, Pak-Hing
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- Development of an Efficient Synthesis of rac-3-Demethoxyerythratidinone via a Titanium(III) Catalyzed Imine-Nitrile Coupling
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We herein describe the evolution of a rapid, high-yielding synthesis of the erythrina alkaloid 3-demethoxyerythratidinone. The natural product is assembled in six steps from commercial precursors in 30–35 % overall yield and with only two chromatographical purification operations. The key step is a titanium(III) catalyzed umpolung reaction in form of a reductive imine–nitrile coupling that can be combined with a subsequent cyclization reaction on a 50 mmol scale. Furthermore, optimized Wacker oxidation conditions enable the selective alkene oxidation in the presence of a tertiary amine functionality, which has been a problem in previous syntheses of erythrina alkaloids. The racemic route can be used to prepare the natural product on gram scale and the results may be useful for the synthesis of related alkaloids.
- Luu, Hieu-Trinh,Streuff, Jan
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- Development of nitrile-functionalized ionic liquids for C-C coupling reactions: Implication of carbene and nanoparticle catalysts
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A series of nitrile-functionalized imidazolium salts (many of which are liquid at room temperature) have been prepared. The reactivity of these salts with PdCl2 has been studied, resulting in salts containing a tetrachloropalladate dianion or compounds in which the nitrile substituent coordinates to the palladium center. Further derivation of the latter compounds affords carbenes. All the new compounds have been characterized by spectroscopic methods and nine of them by single-crystal X-ray diffraction. The catalytic activity of the different palladium salts in Suzuki, Stille, and Heck reactions has been evaluated in some of the nitrile-functionalized ionic liquids (ILs) and compared with that of nonfunctionalized ILs, providing insights into the nature of the actual catalyst. In some instances, palladium nanoparticles have been identified, but the nature of the catalyst strongly depends on the IL employed.
- Fei, Zhaofu,Zhao, Dongbin,Pieraccini, Daniela,Ang, Wee Han,Geldbach, Tilmann J.,Scopelliti, Rosario,Chiappe, Cinzia,Dyson, Paul J.
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- Excited state properties of dimeric π-allylpalladium(II) chloride. Photoreduction of palladium induced by ligand-to-metal charge transfer excitation
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The longest-wavelength absorption of [(π-allyl)PdIICl]2 at λmax=318 nm is assigned to an allyl-→PdII ligand-to-metal charge transfer (LMCT) transition. In the primary photochemical step LMCT excitation leads to the formation of an allyl radical and PdICl, which in acetonitrile undergoes a disproportionation to metallic palladium and palladium(II). PdII(CH3CN)2Cl2 is formed with φ=0.008 at λirr=366 nm.
- Kunkely, Horst,Vogler, Arnd
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- Crystal structures, antibacterial, antioxidant and nucleic acid interactions of mononuclear, and tetranuclear palladium(II) complexes containing Schiff base ligands
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Two new palladium complexes, [Pd(dpbs)Cl] (1) and [Pd4(dbbs)4] (2) (where (dpbs)2?=?o,o′-(N,N′-dipicolinyldene)diazadiphenyl disulfide and (dbbs)2?=?N,N′-(1,1′-dithio-bis(phenylene))-bis(salicylideneimine)), have been synthesized and characterized by analytical and spectral (electronic, IR, 1H, 13C spectroscopy) techniques. The structures of 1 and 2 have been solved by single-crystal X-ray diffraction experiments, which indicate distorted square planar coordination geometries around palladium(II) by O, N, and S donors. The metal chelates have been screened for their antibacterial and antioxidant activities, and compared with their respective ligands. The binding properties of the complexes have been studied by electronic absorption, emission spectroscopy, and viscosity measurements. The competitive fluorescence study with ethidium bromide and the effect of iodide concentration on ?uorescence of the complex-DNA system have been investigated. All these experimental results suggest that palladium complexes strongly bind to DNA, presumably via groove binding. The thermodynamic parameters, enthalpy change (ΔH°), and entropy change (ΔS°) were calculated by the Van’t Hoff equation, suggesting hydrogen bonds play a predominant role in the binding of complexes to DNA.
- Moosun,Bhowon,Hosten,Jhaumeer-Laulloo
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- Synthesis of Indoles by Reductive Cyclization of Nitro Compounds Using Formate Esters as CO Surrogates
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Alkyl and aryl formate esters were evaluated as CO sources in the Pd- and Pd/Ru-catalyzed reductive cyclization of 2-nitrostyrenes to give indoles. Whereas the use of alkyl formates requires the presence of a ruthenium catalyst such as Ru3(CO)12, the reaction with phenyl formate can be performed by using a Pd/phenanthroline complex alone. Phenyl formate was found to be the most effective CO source and the desired products were obtained in excellent yields, often higher than those previously reported using pressurized CO. The reaction tolerates many functional groups, including sensitive ones like a free aldehydic group or a pendant pyrrole. Detailed experiments and kinetic studies allow to conclude that the activation of phenyl formate is base-catalyzed and that the metal doesn't play a role in the decarbonylation step. The reactions can be performed in a single thick-walled glass tube with as little as 0.2 mol-% palladium catalyst and even on a 2 g scale. The same protocol can be extended to other nitro compounds, affording different heterocycles.
- Ahmed Fouad, Manar,Ferretti, Francesco,Formenti, Dario,Milani, Fabio,Ragaini, Fabio
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supporting information
p. 4876 - 4894
(2021/09/20)
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- Synthesis of meso-tetraarylthienylporphyrins by Suzuki-Miyaura cross-coupling reaction and studying their UV-Vis absorption spectra
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meso-Tetra(5-arylthien-2-yl)porphyrins and their copper complexes were synthesized by two different approaches using Suzuki-Miyaura cross-coupling reactions. The first, involving the formation of 5-arylthien-2-yl carbaldehydes, followed by condensation with pyrrole. The second is a direct process that involves the coupling of meso-tetra (5-bromothien-2-yl) porphyrins with the arylboronic acids. The yield of the second approach (40-50 %) was higher than the first approach (28-35 %). The UV-Vis absorption spectra of the synthesized porphyrins revealed bathochromic shifts when compared with the parent porphyrin. Additionally, the products showed no aggregation behaviour in solution (DCM), giving a linear correlation between absorption intensity and the concentration.
- Elghamry, Ibrahim,Abdelsalam, Mamdouh,Al-Faiyz, Yasair,Al-Gadry, Meshail,Al-Taysan, Norah
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p. 322 - 337
(2021/02/12)
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- A ferrocene-templated Pd-bearing molecular reactor
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High-yield, chromatography-free syntheses of a ferrocene-templated molecular cage and its Pd-bearing derivative are presented. The formation of a symmetric cage-type structure was confirmed by single-crystal X-ray diffraction analysis. The Pd-bearing cage was used as an innovative catalyst for the efficient synthesis of 1,1'-biphenyls under mild conditions. The presented catalyst is reusable and 1,1'-biphenyls can be obtained efficiently in a gram scale process.
- Gunka, Piotr A.,Kasprzak, Artur
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supporting information
p. 6974 - 6979
(2020/06/04)
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- Transmetallation of Bis(6-diphenylphosphinoacenaphth-5-yl)-Mercury and -Tributyltin with Precious Metal Chlorides
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The reaction of bis(6-diphenylphosphinoacenapht-5yl)mercury, (6-Ph2P-Ace-5-)2Hg, with [(CO)2RhCl]2 and PtCl2 proceeded with extrusion of mercury / mercury(I) chloride and provided the octahedral rhodium and platinum complexes (6-Ph2P-Ace-5-)2Rh(CO)Cl and (6-Ph2P-Ace-5-)2PtCl2, respectively. The reaction of the (6-diphenylphosphinoacenapht-5yl)stannane 6-Ph2P-Ace-5-SnBu3 with PdCl2 gave rise to tributyltin chloride and a dimeric arylpalladium chloride [(6-Ph2P-Ace-5-)PdCl]2 with a planar Pd2Cl2 core. Together with the previously known gold(III) complex cis- and trans-[R2Au][Cl], the newly prepared compounds were investigated by DFT calculations. The fully optimized gas-phase structure of [(6-Ph2P-Ace-5-)PdCl]2 gives rise to a bend Pd2Cl2 core featuring a Pd···Pd palladophilic interaction. The bonding situation was studied using a set of real-space bonding indicators (RSBIs) derived from the methods Atoms-In-Molecules (AIM), Electron Localizability Indicator (ELI-D) and Non-Covalent Interaction (NCI) index.
- Furan, Sinas,Lork, Enno,Mebs, Stefan,Hupf, Emanuel,Beckmann, Jens
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p. 856 - 865
(2020/05/18)
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- Palladium(II)-Catalyzed Aminotrifluoromethoxylation of Alkenes: Mechanistic Insight into the Effect of N-Protecting Groups
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An efficient palladium-catalyzed regioselective 5-exo aminotrifluoromethoxylation of alkenes has been established herein, which provides a practical route towards the synthesis of OCF3-containing pyrrolidines. tert-Butyloxycarbonyl (Boc) as an amino protecting group plays a significant role in both the chemo- and regioselectivities. In addition, preliminary mechanistic studies reveal that the amino protecting group of substrates and the counter anion of palladium catalyst play critical roles in reaction efficiency presumably due to an isomerization of alkyl- Pd(II) intermediates. Moreover, the asymmetric 5-exo aminotrifluoromethoxylation reaction has also been achieved by introducing a sterically bulky pyridinyl-oxazoline ligand.
- Chen, Chaohuang,Chen, Pinhong,Hou, Chuanqi,Liu, Guosheng
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supporting information
p. 346 - 350
(2020/05/25)
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- Functional hexanuclear Y(III) cluster-based MOFs supported Pd(II) single site catalysts for aerobic selective oxidation of styrene
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Oxidation of styrene is one of the significant reactions in organic synthesis. In this work, a serious of PdCl2 moiety-decorated Y6-MOFs adopting post-synthetic strategy were fabricated as applicable single-site catalysts for oxidation of styrene. Specifically, the functional organic linker, H2bpydc (2,2′-bipyridine-5,5′-dicarboxylic acid), was first incorporated quantitatively into Y6 clusters-based MOF, [(CH3)2NH2]2[Y6(μ3-OH)8(bpdc)6] (bpdc = 4,4′-biphenyl dicarboxylic acid) via post-synthetic ligand exchange. Then post-synthetic Pd(II) metalation was performed to enhance the density of isolated single sites. The obtained Pd(II)-Y-bpydcx/bpdc1-x can be used as highly efficient heterogeneous single-site catalysts to promote selective oxidative cleavage of styrene to benzaldehyde using O2 as a oxidant under solvent-free and mild reaction conditions (1 atm and 80 °C). Importantly, when using Pd(II)-Y-bpydc0.8/bpdc0.2 (0.024 mmol Pd) as catalyst, the high conversion of styrene and the selectivity for benzaldehyde can reach 88.7 % and 82.2 %, respectively.
- Han, Zheng-Bo,Wei, Na,Xing, Zhiqiang,Zhang, Yue
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- Mono- and dinuclear palladium(II) complexes incorporating 1,2,3-triazole-derived mesoionic carbenes: syntheses, solid-state structures and catalytic applications
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Two 1,2,3-triazole-derived monocationic salts 3 and 4 bearing N-aryl wingtips were prepared using copper-catalyzed “click” reactions followed by alkylations with iodomethane. Employing a silver–carbene transfer method, two dinuclear palladium(II) complexes of triazolin-5-ylidenes (5/6) were obtained, the former of which has been reported previously. Bridge-cleavage reaction of 5 as a representative with PPh3 yielded cis-configured mesoionic carbene/phosphine hybrid complex cis-7 and homoleptic bis(phosphine) complex 8, suggesting the presence of a ligand exchange process. In contrast, bridge breakages of 5/6 with pyridine cleanly afforded PEPPSI-type complexes 9 and 10 in near quantitative yields. Finally, all complexes were exploited to catalyze Mizoroki–Heck coupling reactions with aryl bromides as the substrates, and PEPPSI-type complex 9 was found to be the best performer generally giving good to excellent yields.
- Zhang, Xin,Yan, Xuechao,Zhang, Bo,Wang, Ran,Guo, Shuai,Peng, Shiyong
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- Palladium(II) Complexes Based on N,S-Donor Ligands: Synthesis and Molecular Structures
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Phenyl(chloro)dithioformate is treated with pyrazole derivatives and phenyl(Pz-1-carbodithioate) ligands (Pz = pyrazole (1), 3-methylpyrazole (2), and 3,5-dimethylpyrazole (3)) are obtained. These ligands are treated with PdCl2 in acetonitrile and complexes of the general formula Pd(L)Cl2 form in an essentially quantitative yield. The ligands are found to be N,S-bidentate linkers, and 5-membered palladacycles are obtained. Precursors 1–3 are oily materials and characterized by 1H and 13C NMR spectroscopy. Due to a partial solubility of Pd complexes, the complete set of NMR data cannot be collected. The structural elucidation is also accompanied by elemental and mass spectrometric analyses. Solid-state structures of complexes 5 and 6 are determined by X-ray diffraction. The data obtained for complexes 5 and 6 are also calculated by DFT using the TURBOMOLE program package. Experimental and calculated data sets are found to be in close agreement with each other.
- Khan,Khan,Noor,Schwarz
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p. 159 - 167
(2019/04/30)
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- (Isocyano Group π-Hole)???[dz2 -MII] Interactions of (Isocyanide)[MII] Complexes, in which Positively Charged Metal Centers (d8-M=Pt, Pd) Act as Nucleophiles
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Inspection of the X-ray structures of the newly prepared trans-[MII(CNXyl)2(DAPT)2]Cl(BF4) (M=Pd, Pt; Xyl=2,6-Me2C6H3; DAPT=4,6-diaminopyrimidine-2(1H)-thione) complexes and the appropriate Hirshfeld molecular surface analysis allowed the recognition of the previously unknown π-hole???metal interactions between a ligated isocyano group (acting as a π-hole donor) and the positively charged d8-PtII and d8-PdII metal centers (acting as nucleophiles); this is the first identification of π-hole???metal interactions with triple-bond species. Results of DFT calculations followed by the topological analysis of the electron density distribution within the framework of Bader's theory (quantum theory of atoms in molecules, QTAIM) confirmed the presence of these contacts. The electrostatic surface potential calculations indicated that π-hole???metal contacts are formed upon interaction between the electrophilic isocyano C atom (π-hole donor) and the nucleophilic dz2 orbital of the metal centers, which act as π-hole acceptors. Available CCDC data were processed from the perspective of the π-hole???metal interactions with isocyanide ligands, and their analysis disclosed the role of metal nucleophilicity in the corresponding π-hole acceptor ability.
- A. Katkova, Svetlana,S. Mikherdov, Alexander,A. Kinzhalov, Mikhail,S. Novikov, Alexander,A. Zolotarev, Andrey,Boyarskiy, Vadim P.,Kukushkin, Vadim Yu.
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supporting information
p. 8590 - 8598
(2019/06/08)
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- Catalyst containing para-benzhydryl substituted alpha-diimine palladium (II), and preparation method thereof
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The invention discloses a catalyst containing para-benzhydryl substituted alpha-diimine palladium (II), and a preparation method thereof. The preparation method comprises three main steps: preparation of a para-benzhydryl substituted phenylamine derivative, preparation of a para-benzhydryl substituted alpha-diimine ligand, and preparation of a para-benzhydryl substituted alpha-diimine palladium (II) ligand. The catalyst containing para-benzhydryl substituted alpha-diimine palladium (II) can be used in catalysis of alpha-alkene oligomerization preparation of PAO base oil, the obtained PAO base oil is low in pour point and high in viscosity index, and the using effect of the PAO base oil is improved greatly.
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Paragraph 0030; 0038; 0044; 0048; 0052; 0056
(2019/10/08)
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- Halides Held by Bifurcated Chalcogen-Hydrogen Bonds. Effect of μ(S,N-H)Cl Contacts on Dimerization of Cl(carbene)PdII Species
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The reaction of cis-[PdCl2(CNCy)2] (1) with thiazol-2-amines (2-10) leads to the C,N-chelated diaminocarbene-like complexes [PdCl{C(N(H)4,5-R2-thiazol-2-yl)NHCy}(CNCy)] (11-14; 82-91%) in the case of 4,5-R2-thiazol-2-amines (R, R = H, H (2), Me, Me (3), -(CH2)4- (4)) and benzothiazol-2-amine (5) or gives the diaminocarbene species cis-[PdCl2{C(N(H)Cy)N(H)4-R-thiazol-2-yl}(CNCy)] (15-19; 73-93%) for the reaction with 4-aryl-substituted thiazol-2-amines (R = Ph (6), 4-MeC6H4 (7), 4-FC6H4 (8), 4-ClC6H4 (9), 3,4-F2C6H3 (10)). Inspection of the single-crystal X-ray diffraction data for 15-17 and 19 suggests that the structures of all these species exhibit previously unrecognized bifurcated chalcogen-hydrogen bonding μ(S,N-H)Cl and also PdII···PdII metallophilic interactions. These noncovalent interactions collectively connect two symmetrically located molecules of 15-17 and 19, resulting in their solid-state dimerization. The existence of the μ(S,N-H)Cl system and its strength (6-9 kcal/mol) were additionally verified/estimated by a Hirshfeld surface analysis and DFT calculations combined with a topological analysis of the electron density distribution within the formalism of Bader's theory (AIM method) and NBO analysis. The observed noncovalent interactions are jointly responsible for the dimerization of 15-19 not only in the solid phase but also in CHCl3 solutions, as predicted theoretically by DFT calculations and confirmed experimentally by FTIR, HRESI-MS, 1H NMR, and diffusion coefficient NMR measurements. Available CCDC data were processed under the new moiety angle, and the observed μ(S,E-H)Cl systems were classified accordingly to E (E = N, O, C) type atoms.
- Mikherdov, Alexander S.,Novikov, Alexander S.,Kinzhalov, Mikhail A.,Boyarskiy, Vadim P.,Starova, Galina L.,Ivanov, Alexander Yu.,Kukushkin, Vadim Yu.
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supporting information
p. 3420 - 3433
(2018/03/25)
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- Polystyrene bis[N-(2-pyridyl) sulfonamide] palladium(II): Synthesis, characterization as a catalyst for coupling reactions
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The [N-(2-pyridyl)] para-styrene sulfonamide (PSS) was prepared as a monomer, from the reaction of para-styrene sulfonyl chloride and 2-amino pyridine in the presence of potassium hydroxide solution 0.5?M as a base, and CH3Cl. Polystyrene [N-(2-pyridyl) sulfonamide] (PPSS) was synthesized from the polymerization of [N-(2-pyridyl)] para-styrene sulfonamide (PSS). The Polystyrene bis [N-(2-pyridyl) sulfonamide] palladium (II) as a polymer- supporting palladium complex was also prepared from the reaction of PdCl2 (CH3CN)2 with PPSS in the presence of KOH 0.5?M. Polystyrene bis [N-(2-pyridyl) sulfonamide] palladium (II) is produced as a novel heterogeneous catalyst for coupling reactions for C-C bond formation. This method includes higher yield and has an easier work-up procedure. The structures of the monomer, polymer and its Pd complex were confirmed by using FT-IR and 1H-NMR spectroscopy. Elemental analysis of Pd by inductively coupled plasma (ICP) technique and hot filtration test showed loading of the metal into solution from the catalyst The heterogeneous catalyst was recycled without any loss in its properties.
- Shafieyoon, Parvaneh,Mehdipour, Ebrahim,Tavakol, Hosein
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p. 324 - 328
(2018/01/04)
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- Comparative Study of Novel Phosphordiamidite and Phosphite Ligands Used in Alkene Hydroformylation; Synthesis, Characterization, Metalation, and Catalytic Evaluation
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Three novel ligands have been prepared by the reactions of 1,1′-(chlorophosphinediyl)bis(1H-pyrrole) with either 2-pyridinemethanol or 2,6-pyridinedimethanol or the reaction of 1,1′-biphenyl-2,2′-diyl phosphorochloridite with 2-pyridinemethanol. Measurement of |1JP–Se| values demonstrate that the phosphite donor is less basic than the phosphoramidite donors. Coordination preferences of the ligands in octahedral cis-tetracarbonylmolybdenum(0) and square planar cis-dichloropalladium(II) complexes have been evaluated using multinuclear NMR and X-ray crystallography. Rhodium(I) complexes of the bidentate ligands have been evaluated as catalysts for styrene hydroformylation, and their activities are nearly double those of catalysts containing traditional phosphites. The regioselectivities of the RhI complexes of the bidentate ligands are not significantly different at 80 °C and 20 atm and are not affected by the addition of a lithium salt. In contrast, changing reaction conditions causes the % n-aldehyde to vary from 15 to 50 %. The regioselectivity of the catalyst containing the bidentate phosphoramidite/pyridine ligand was more sensitive to pressure than temperature with both effects being significant.
- Hastings, Samantha D.,Cagle, Ethan C.,Totsch, Timothy R.,Tyus, Shakyra D.,Gray, Gary M.
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p. 4158 - 4174
(2018/10/15)
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- MULTICOMPONEMT PLASMONIC PHOTOCATALYSTS CONSISTING OF A PLASMONIC ANTENNA AND A REACTIVE CATALYTIC SURFACE: THE ANTENNA-REACTOR EFFECT
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A method of making a multicomponent photocatalyst, includes inducing precipitation from a pre-cursor solution comprising a pre-cursor of a plasmonic material and a pre-cursor of a reactive component to form co-precipitated particles; collecting the co-precipitated particles; and annealing the co-precipitated particles to form the multicomponent photocatalyst comprising a reactive component optically, thermally, or electronically coupled to a plasmonic material.
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Paragraph 0080
(2019/01/07)
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- Oxidative Mechanochemistry: Direct, Room-Temperature, Solvent-Free Conversion of Palladium and Gold Metals into Soluble Salts and Coordination Complexes
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Noble metals are valued, critical elements whose chemical activation or recycling is challenging, and traditionally requires high temperatures, strong acids or bases, or aggressive complexation agents. By using elementary palladium and gold, demonstrated here is the use of mechanochemistry for noble-metal activation and recycling by mild, clean, solvent-free, and room-temperature chemistry. The process leads to direct, efficient, one-pot conversion of the metals, including spent catalysts, into either simple water-soluble salts or metal–organic catalysts.
- Do, Jean-Louis,Tan, Davin,Fri??i?, Tomislav
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supporting information
p. 2667 - 2671
(2018/02/06)
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- Pt(II) and Pd(II)-assisted coupling of nitriles and 1,3-diiminoisoindoline: Synthesis and luminescence properties of (1,3,5,7,9-pentaazanona-1,3,6,8-tetraenato)Pt(II) and Pd(II) complexes
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Treatment of trans-[PtCl2(NCR)2] 1 (R?=?Me (1a), Et (1b), o-ClC6H4 (1c), p-ClC6H4 (1d), p-(HC[dbnd]O)C6H4 (1e), p-O2NC6H4CH2 (1f)) with 1,3-diiminoisoindoline HN[dbnd]CC6H4C(NH)[dbnd]NH 2 gives access to the corresponding (1,3,5,7,9-pentaazanona-1,3,6,8-tetraenato)Pt(II) complexes [PtCl{NH[dbnd]C(R)N[dbnd]C(C6H4)NC[dbnd]NC(R)[dbnd]NH}] 3a–f, in good yields (65–70%). The reaction of trans-[PdCl2(NCMe)2] 4a with 2 furnishes (1,3,5,7,9-pentaazanona-1,3,6,8-tetraenato)Pd(II) complex [PdCl{NH[dbnd]C(Me)N[dbnd]C(C6H4)NC[dbnd]NC(Me)[dbnd]NH}] 5a, in good yield (65%). However, the reaction of trans-[PdCl2(NCR)2] 4 (R?=?Ph (4b), p-MeC6H4CH2 (4c), p-(HC[dbnd]O)C6H4 (4d), p-O2NC6H4CH2 (4e)) with 2 gives a number of unidentified products. The compounds 3a–f and 5a were characterized by IR,1H,13C and DEPT-135 NMR spectroscopies, elemental analyses and, in the case of the Pt(II) complex [PtCl{NH[dbnd]C(Me)N[dbnd]C(C6H4)NC[dbnd]NC(Me)[dbnd]NH}] 3a, also by X-ray diffraction analysis. Compounds 3a and 3b were also characterized by UV–Vis absorption and luminescence emission spectroscopies. Emission quantum yields of ca. 3?×?10?3 were obtained in dichloromethane solution, and luminescence lifetimes are in the order of the tens of nanoseconds. Both compounds also exhibited luminescence in solid state (polystyrene matrix), with luminescence lifetimes in the order of hundreds of nanoseconds.
- Lasri, Jamal,Pedras, Bruno,Haukka, Matti,Berberan-Santos, Mário N.
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p. 195 - 202
(2017/06/13)
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- Novel phosphorus-coordinated palladium(II) complexes derived from 3,5-disubstituted-1H-1,2,4-diazaphospholes: Synthesis and catalytic application in Suzuki-Miyaura cross-coupling reactions
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Four novel phosphorus-coordinated palladium(II) complexes(I-IV) were easily prepared by the reaction of 3,5-disubstituted-1H-1,2,4-diazaphospholes with Pd(CH3CN)2Cl2at room temperature and characterized. The catalytic activity of palladium(II) complexes was further evaluated in Suzuki-Miyaura reaction of aryl halides with arylboronic acids, giving the biphenyl derivatives in good yields.
- Jia, Xuefeng,Zhao, Fang
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p. 145 - 149
(2017/03/09)
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- Spectroscopic, electrochemical and X-ray crystallographic properties of a novel palladium(II) complex of thioamide deprotonated di-2-pyridyl ketone thiosemicarbazone (dpktsc-H)?
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The reaction between di-2-pyridyl ketone thiosemicarbazone (dpktsc) and PdCl2(CH3CN)2, generated in situ from the reaction between PdCl2 and CH3CN, gave the unprecedented [Pd2Cl3(κ5-Npy,Nim,S,Npy,Nam-dpktsc-H)]·2CH3CN (1) complex (py = pyridine, im = imine and am = amide). The identity of 1 was confirmed via its elemental analysis and spectroscopic properties. Infrared and 1H-NMR spectra confirmed the coordination of (dpktsc-H)? to the palladium ions. The electronic absorption spectra measured in dmso and dmf and density functional theory (DFT) calculations revealed metal-to-ligand charge-transfer (MLCT), d–d and intra-ligand charge-transfer (ILCT) electronic transitions. X-ray structural analysis on a crystal of [Pd2Cl3(κ5-Npy,Nim,S,Npy,Nam-dpktsc-H)]·H2O (2) grown from dmf solution of 1 confirmed its formulation and showed the solid-state structure contains a web of molecules locked via a network of non-covalent interactions. Electrochemical measurements on 1 in dmf revealed metal- and ligand-based redox processes. In contrast to the electrochemical decomposition of uncoordinated dpktsc, coordinated (dpktsc-H)? in 1 does not undergo electrochemical decomposition. Electrochemical titrations of 1 with p-toluenesulfonic acid monohydrate (p-TSOH) revealed electro-catalytic proton reduction. Over-potential (η) of 180?mV for the H2 evolution was observed and is comparable to several molecular electro-catalysts for proton reduction. Controlled-potential electrolysis confirmed the electro-catalytic proton reduction by the Pd-complex. Electrochemical reactions of CO2 in the presence of 1 exhibited a proton dependence, and metal- and ligand-based electrochemical reaction.
- Bakir, Mohammed,Lawrence, Mark A. W.,Ferhat, Marhoun,Conry, Rebecca R.
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p. 3048 - 3064
(2017/10/13)
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- Tetrakis [N-(2-pyridyl) sulfonamide] di palladium: synthesize, X-ray diffraction, antibacterial properties and as a novel binuclear Pd-complex for coupling reactions
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The N-(2-pyridyl) 4-toluene sulfonamide as a free ligand (PTS) was prepared from the reaction of 2-amino pyridine and 4-toluenesulfonyl chloride in the presence of potassium hydroxide solution 1?M as a base and THF was used as a solvent. The complex tetrakis [N-(2-pyridyl) sulfonamide] di palladium (1) (Pd2L4) was also prepared from the reaction of PdCl2(CH3CN)2 using (PTS) in the presence of NaOH 0.5?M and its application in Heck and Suzuki reactions. This complex consists of a binuclear unit consisting of four ligands linked to two palladium atoms via the nitrogen of pyridines ring and the nitrogen of sulfonamides. These compounds were confirmed by FT-IR and 1H NMR spectroscopy. Moreover, the structure of the complex was studied by single-crystal X-ray diffraction method. The green crystal of Pd2L4 [L?=?N-(2-pyridyl) sulfonamide](1) was found to crystallize in the monoclinic space group C2/c with a?=?18.2013(19), b?=?19.7544(16), c?=?17.2898(19) ?, β?=?120.179(8) °; V?=?5374.0(9) ?3; Z =?4; the final R1?=?0.0894, wR2?=?0.1754 (or 5867 observed reflections and 318 variables). The Pd–Pd distance is 2.567(2) ?. In addition, PTS and Pd2L4 presented different antibacterial behaviors. The free ligand was active against Staphylococcus aureus and Escherichia coli, but the complex was inactive against them.
- Mehdipour, Ebrahim,Shafieyoon, Parvaneh,Salahvarzi, Maryam,Amani, Vahid
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p. 1575 - 1582
(2017/06/06)
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- Photocatalytic Transfer Hydrogenolysis of Allylic Alcohols on Pd/TiO2: A Shortcut to (S)-(+)-Lavandulol
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We report herein a regio- and stereoselective photocatalytic hydrogenolysis of allylic alcohols to form unsaturated hydrocarbons employing a palladium(II)-loaded titanium oxide; the reaction proceeds at room temperature under light irradiation without stoichiometric generation of salt wastes. Olefin and saturated alcohol moieties tolerated the reaction conditions. Hydrogen atoms were selectively incorporated into less sterically congested carbons of the allylic functionalities. This protocol allowed a short-step synthesis of (S)-(+)-lavandulol from (R)-(?)-carvone by avoiding otherwise necessary protection/deprotection steps.
- Takada, Yuki,Caner, Joaquim,Kaliyamoorthy, Selvam,Naka, Hiroshi,Saito, Susumu
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supporting information
p. 18025 - 18032
(2017/12/08)
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- Rich Coordination Chemistry of π-Acceptor Dibenzoarsole Ligands
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A series of dibenzoarsole (also known as 9-arsafluorene) derivatives have been prepared, and their coordination chemistry has been investigated. The different ligand topology and the arsenic substituents govern the reactivity of the ligands. We report various crystal structures of palladium and platinum complexes derived from this family of ligands. The biphenyl backbone of the bridged bidentate ligands allows very flexible coordination. We have also studied the application of an allylic Pd complex in nucleophilic substitution reactions, revealing that the benzoarsole substituent is susceptible to metal insertion.
- Gupta, Arvind Kumar,Akkarasamiyo, Sunisa,Orthaber, Andreas
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p. 4504 - 4511
(2017/04/26)
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- Palladium(II) and platinum(II) complexes of ((2-pyridyl)pyrazol-1-ylmethyl)benzoic acids: Synthesis, Solid state characterisation and biological cytotoxicity
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The new ligands 3-(3-(2-pyridyl)pyrazol-1-ylmethyl)benzoic acid (L2) and 5-(3-(2-pyridyl)pyrazol-1-ylmethyl)benzene 1,3-dicarboxylic acid (L3) are reported and the synthesis and characterisation of [PdCl2(L)] and [PtCl2(L)] complexes of these and the previously reported 4-(3-(2-pyridyl)pyrazol-1-ylmethyl)benzoic acid (L1) are described. In the solid state, the square planar complexes assemble via hydrogen bonding interactions involving COOH and M-Cl groups as well as by various π-stacking interactions involving the aromatic rings on the ligands and, notably, the chelate rings. Hirshfeld surface analysis has been used to gain insight into the assembly of the molecules. Preliminary studies of the biological cytotoxicity of the [PtCl2(L)] complexes against A549 and MDA-MB-231 cancer cell lines are reported.
- McKay, Aidan P.,Lo, Warrick K.C.,Preston, Dan,Giles, Gregory I.,Crowley, James D.,Barnsley, Jonathan E.,Gordon, Keith C.,McMorran, David A.
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- A Palladium(II)-Catalyzed C-H Activation Cascade Sequence for Polyheterocycle Formation
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Polyheterocycles are found in many natural products and are useful moieties in functional materials and drug design. As part of a program towards the synthesis of Stemona alkaloids, a novel palladium(II)-catalyzed C-H activation strategy for the construction of such systems has been developed. Starting from simple 1,3-dienyl-substituted heterocycles, a large range of polycyclic systems containing pyrrole, indole, furan and thiophene moieties can be synthesized in a single step. Don't overdo it: A palladium(II)-catalyzed C-H activation cascade sequence for the synthesis of polyheterocycles is reported. Aromatization of the initially formed dihydro species occurred with a quinone oxidant. In some cases the use of one equivalent of the oxidant enabled isolation of the dihydro species as a single isomer (see scheme; X=NMe, O, S).
- Cooper, Stephen P.,Booker-Milburn, Kevin I.
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supporting information
p. 6496 - 6500
(2015/06/02)
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- Efficient catalytic activation of Suzuki-Miyaura C-C coupling reactions with recyclable palladium nanoparticles tailored with sterically demanding di-n-alkyl sulfides
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n-Bromodocosane reacts with Na2S, generated in situ by the reduction of elemental sulfur with NaBH4, to give n-didocosyl sulfide (L1), which acts as a protector for palladium nanoparticles (2-7) that are prepared using different palladium precursors in the presence of L1 (Pd:L1 ratio 1:2 and 4:1). The NPs have been characterized with powder X-ray diffraction, SEM, EDX, UV-vis spectroscopy and HRTEM. The size (nm) ranges for the majority of spherical NPs 2-7 are ~18-19, 4-5, 5-7, 4-6, 7-9 and 4-6 respectively. The precursor of palladium affects the size, shape and dispersion of the NPs. When [Pd(CH3CN)2Cl2]/Na2PdCl4 was used as a precursor, uniformly dispersed NPs of narrow size range were obtained. L1 and its complex [Pd(L1)2Cl2] (1) have also been synthesized by the reaction of Na2PdCl4 with L1 and characterized with 1H and 13C{1H} NMR spectroscopy. The NPs show good catalytic activity for the Suzuki-Miyaura coupling (SMC) of various aryl chlorides/bromides with phenylboronic acid at low catalyst loading (0.1-0.5 mol% of Pd). The conversion is good for some aryl halides in a short reaction time of the order 1-2 h. Among 2-7, the highest activity is observed for Pd NPs obtained from Na2PdCl4, which is probably due to uniformity in their size and dispersion. The distinct advantage of NPs 2-7 is that they can be separated and reused at least up to five times. The complex 1, equivalent to 0.001 mol% Pd, is efficient for the SMC of some aryl halides, as good conversion into coupled products has been observed. Two phase tests, conducted for 1 and 3, suggest the contribution of both homogeneous and heterogeneous catalytic pathways in overall catalysis. This journal is
- Kumar, Satyendra,Rao,Kumar, Arun,Singh, Mahabir P.,Saleem, Fariha,Singh, Ajai K.
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p. 20081 - 20089
(2015/03/30)
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- Palladium-catalyzed cyclization of 2-alkynyl-N-ethanoyl anilines to indoles: Synthesis, structural, spectroscopic, and mechanistic study
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This study reports a facial regio-selective synthesis of 2-alkyl-N-ethanoyl indoles from substituted-N-ethanoyl anilines employing palladium (II) chloride, which acts as a cyclization catalyst. The mechanistic trait of palladium-based cyclization is also explored by employing density functional theory. In a two-step mechanism, the palladium, which attaches to the ethylene carbons, promotes the proton transfer and cyclization. The gas-phase barrier height of the first transition state is 37kcal/mol, indicating the rate-determining step of this reaction. Incorporating acetonitrile through the solvation model on density solvation model reduces the barrier height to 31kcal/mol. In the presence of solvent, the electron-releasing (-CH3) group has a greater influence on the reduction of the barrier height compared with the electron-withdrawing group (-Cl). These results further confirm that solvent plays an important role on palladium-catalyzed proton transfer and cyclization. For unveiling structural, spectroscopic, and photophysical properties, experimental and computational studies are also performed. Thermodynamic analysis discloses that these reactions are exothermic. The highest occupied molecular orbital-lowest unoccupied molecular orbital gap (4.9-5.0eV) confirms that these compounds are more chemically reactive than indole. The calculated UV-Vis spectra by time-dependent density functional theory exhibit strong peaks at 290, 246, and 232nm, in good agreement with the experimental results. Moreover, experimental and computed 1H and 13C NMR chemical shifts of the indole derivatives are well correlated.
- Hoque, Mohammad Mazharol,Halim, Mohammad A.,Sarwar, Mohammed G.,Khan, Md. Wahab
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p. 732 - 742
(2015/11/09)
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- An Alternative Approach to PEPPSI Catalysts: From Palladium Isonitriles to Highly Active Unsymmetrically Substituted PEPPSI Catalysts
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A series of new pyridine-enhanced precatalyst preparation, stabilization, and initiation (PEPPSI)-type complexes bearing different types of carbene ligands was prepared by the modular and convergent template synthesis strategy. Nitrogen acyclic carbenes, saturated and unsaturated five-membered NHC, saturated six-membered NHCs, and five-membered N-heterocyclic oxo-carbene (NHOC) ligands on palladium were prepared this way. These new organometallic compounds then were tested in Suzuki and Negishi cross-coupling reactions by using substrates with one or two substituents in ortho-position of the new C- C bond being formed. Both aryl chlorides and bromides were tested as coupling partners. In some cases, the new ligands gave results similar to Organ's successful IPr-based and IPent-based PEPPSI derivatives, with aryl bromides 0.05 mol % catalyst load still gave satisfactory results, with aryl chlorides 0.5 mol % were needed.
- Zeiler, Anna,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 11065 - 11071
(2015/11/10)
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- Palladium(II) complexes containing N,N′-bidentate N-(pyridin-2-ylmethyl)aniline and its derivatives: Synthesis, structural characterisation, and methyl methacrylate polymerisation
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The reaction of [Pd(CH3CN)2Cl2] with N-(pyridin-2-ylmethyl)aniline (L1) and its derivatives (L 2-L6) in ethanol yields [(NN′)PdCl2] complexes, namely [LnPdCl2] (Ln = L 1-L6). The X-ray crystal structure of Pd(II) complexes revealed that the palladium atom in [LnPdCl2] (L n = L1-L6) showed a square plane geometry involving two nitrogen atoms of NN′-bidentate and two chlorido ligands. Complex [L4PdCl2] containing 2,4,6-trimethyl-N-(pyridin-2- ylmethyl)aniline (L4) showed the highest catalytic activity for the polymerisation of methyl methacrylate (MMA) in the presence of modified methylaluminoxane (MMAO) with an activity of 1.41 × 105 g PMMA/mol Pd·h at 60 °C and poly(methyl methacrylate) (PMMA) syndiotacticity (characterised using 1H NMR spectroscopy) of ca. 0.70.
- Kim, Sunghoon,Kim, Dongil,Lee, Ha-Jin,Lee, Hyosun
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- Synthesis, spectroscopic characterization and density functional studies of a bis-benzimidazole derivative and of its complexes with palladium(II) halides
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The 2,6-bis(benzimidazol-2′-ylthiomethyl)pyridine (L) ligand and its palladium(II) complexes [Pd(L)X]X (X = Cl, Br, and I) have been synthesized and characterized by spectroscopic data acquisition. The ligand (L) was prepared by conventional heating as well as by microwave irradiation. Microwave irradiation shows additional features, including an easy workup, a much faster reaction and higher yields. The molar conductivity data reveal that the complexes form a 1:1 electrolyte in DMSO. The geometries, ground-state energetics and vibrational spectra of (L) and of its complexes have been elucidated, in terms of quantum chemical calculations. In the mononuclear complexes, the palladium atom is coordinated to three nitrogen atoms and one terminal halogen atom in a slightly distorted square planar arrangement. The present elemental analyses, FT-IR (mid, far), 1H and 13C NMR spectra are in good accordance with the square planar geometry around the Pd ion. The thermal behaviors of the complexes have been assessed by thermal gravimetric and differential thermal analyses.
- Aghatabay, Naz Mohammed,Altun, Ahmet,Gürbüz, Mustafa Ulvi,Türkyilmaz, Murat
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p. 905 - 912
(2014/08/18)
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- Palladium complex catalyst immobilized on epoxy support under supercritical conditions
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The aim of this research was to obtain a new-generation complex catalyst under supercritical carbon dioxide. A new complex catalyst based on epoxy resin cured with multifunctional polythiourethane was prepared. The use of polythiourethane as a hardener allowed us to introduce linking groups into the structure of the polymer without further functionalization of the resin. Additionally, the use of supercritical CO2 enabled a more accurate and better distribution of the metal complex in the polymer matrix. The presence of the functional groups allowed us to obtain a catalyst wherein the metal centers had a different electronic structure and various degrees of oxidation, so that such a system was characterized by its high selectivity. The catalytic properties of the prepared catalysts were tested in the hydrogenation reaction. Research methods like time-of-flight secondary-ion mass spectrometry (ToF-SIMS), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and nitrogen BET surface area measurements were used to characterize polymeric support and heterogenized catalysts.
- Ba?czek, Natalia,Strzelec, Krzysztof
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p. 1080 - 1087
(2015/02/18)
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