bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pincer‐Type Heck Catalysts and Mechanisms Based on PdIV Intermediates: A Computational Study
Authors: Blacque Olivier , Frech Christian M. 
Published: December 2009

AbstractPincer‐type palladium complexes are among the most active Heck catalysts. Due to their exceptionally high thermal stability and the fact that they contain PdII centers, controversial PdII/PdIV cycles have been often proposed as potential catalytic mechanisms. However, pincer‐type PdIV intermediates have never been experimentally observed, and computational studies to support the proposed PdII/PdIV mechanisms with pincer‐type catalysts have never been carried out. In this computational study the feasibility of potential catalytic cycles involving PdIV intermediates was explored. Density functional calculations were performed on experimentally applied aminophosphine‐, phosphine‐, and phosphite‐based pincer‐type Heck catalysts with styrene and phenyl bromide as substrates and (E)‐stilbene as coupling product. The potential‐energy surfaces were calculated in dimethylformamide (DMF) as solvent and demonstrate that PdII/PdIV mechanisms are thermally accessible and thus a true alternative to formation of palladium nanoparticles. Initial reaction steps of the lowest energy path of the catalytic cycle of the Heck reaction include dissociation of the chloride ligands from the neutral pincer complexes [{2,6‐C6H3(XPR2)2}Pd(Cl)] [X=NH, R=piperidinyl (1 a); X=O, R=piperidinyl (1 b); X=O, R=iPr (1 c); X=CH2, R=iPr (1 d)] to yield cationic, three‐coordinate, T‐shaped 14e− palladium intermediates of type [{2,6‐C6H3(XPR2)2}Pd]+ (2). An alternative reaction path to generate complexes of type 2 (relevant for electron‐poor pincer complexes) includes initial coordination of styrene to 1 to yield styrene adducts [{2,6‐C6H3(XPR2)2}Pd(Cl)(CH2CHPh)] (4) and consecutive dissociation of the chloride ligand to yield cationic square‐planar styrene complexes [{2,6‐C6H3(XPR2)2}Pd(CH2CHPh)]+ (6) and styrene. Cationic styrene adducts of type 6 were additionally found to be the resting states of the catalytic reaction. However, oxidative addition of phenyl bromide to 2 result in pentacoordinate PdIV complexes of type [{2,6‐C6H3(XPR2)2}Pd(Br)(C6H5)]+ (11), which subsequently coordinate styrene (in trans position relative to the phenyl unit of the pincer cores) to yield hexacoordinate phenyl styrene complexes [{2,6‐C6H3(XPR2)2}Pd(Br)(C6H5)(CH2CHPh)]+ (12). Migration of the phenyl ligand to the olefinic bond gives cationic, pentacoordinate phenylethenyl complexes [{2,6‐C6H3(XPR2)2}Pd(Br)(CHPhCH2Ph)]+ (13). Subsequent β‐hydride elimination induces direct HBr liberation to yield cationic, square‐planar (E)‐stilbene complexes with general formula [{2,6‐C6H3(XPR2)2}Pd(CHPhCHPh)]+ (14). Subsequent liberation of (E)‐stilbene closes the catalytic cycle.
Symmetrization of Cationic Hydrogen Bridges of Protonated Sponges Induced by Solvent and Counteranion Interactions as Revealed by NMR Spectroscopy
Authors: Pietrzak Mariusz , Wehling Jens P. , Kong Shushu , Tolstoy Peter M. , Shenderovich Ilya G. , López Concepción , Claramunt Rosa María , Elguero José , Denisov Gleb S. , Limbach Hans‐Heinrich 
Published: December 2009

AbstractThe properties of the intramolecular hydrogen bonds of doubly 15N‐labeled protonated sponges of the 1,8‐bis(dimethylamino)naphthalene (DMANH+) type have been studied as a function of the solvent, counteranion, and temperature using low‐temperature NMR spectroscopy. Information about the hydrogen‐bond symmetries was obtained by the analysis of the chemical shifts δH and δN and the scalar coupling constants J(N,N), J(N,H), J(H,N) of the 15NH15N hydrogen bonds. Whereas the individual couplings J(N,H) and J(H,N) were averaged by a fast intramolecular proton tautomerism between two forms, it is shown that the sum |J(N,H)+J(H,N)| generally represents a measure of the hydrogen‐bond strength in a similar way to δH and J(N,N). The NMR spectroscopic parameters of DMANH+ and of 4‐nitro‐DMANH+ are independent of the anion in the case of CD3CN, which indicates ion‐pair dissociation in this solvent. By contrast, studies using CD2Cl2, [D8]toluene as well as the freon mixture CDF3/CDF2Cl, which is liquid down to 100 K, revealed an influence of temperature and of the counteranions. Whereas a small counteranion such as trifluoroacetate perturbed the hydrogen bond, the large noncoordinating anion tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate B[{C6H3(CF3)2}4]− (BARF−), which exhibits a delocalized charge, made the hydrogen bond more symmetric. Lowering the temperature led to a similar symmetrization, an effect that is discussed in terms of solvent ordering at low temperature and differential solvent order/disorder at high temperatures. By contrast, toluene molecules that are ordered around the cation led to typical high‐field shifts of the hydrogen‐bonded proton as well as of those bound to carbon, an effect that is absent in the case of neutral NHN chelates.
Colourimetric Carboxylate Anion Sensors Derived from Viologen‐Based Receptors
Authors: Swinburne Adam N. , Paterson Martin J. , Fischer Kathrin H. , Dickson Sara Jane , Wallace Emma V. B. , Belcher Warwick J. , Beeby Andrew , Steed Jonathan W. 
Published: December 2009

AbstractA series of tri‐ and tetrapodal viologen‐based anion receptors showing a colourimetric response to carboxylates, such as acetate, have been synthesised. Alteration of the anion binding sites allows for binding site competition within a receptor. This results in a delayed colourimetric response for urea derivatives compared with pyridinium systems because the anions are initially bound to the periphery of the receptor, away from the viologen unit. DFT calculations and experimental measurements allow the colour change to be assigned to an anion–receptor charge‐transfer process, facilitated by the exceptionally low reduction potential of the cationic host compounds. Evidence for electron transfer to give the viologen radical cation is also seen in some cases.
Dynamic Supramolecular Polymers Based on Benzene‐1,3,5‐tricarboxamides: The Influence of Amide Connectivity on Aggregate Stability and Amplification of Chirality
Authors: Stals Patrick J. M. , Everts Jeffrey C. , de Bruijn Robin , Filot Ivo A. W. , Smulders Maarten M. J. , Martín‐Rapún Rafael , Pidko Evgeny A. , de Greef Tom F. A. , Palmans Anja R. A. , Meijer E. W. 
Published: December 2009

AbstractN‐Centred benzene‐1,3,5‐tricarboxamides (N‐BTAs) composed of chiral and achiral alkyl substituents were synthesised and their solid‐state behaviour and self‐assembly in dilute alkane solutions were investigated. A combination of differential scanning calorimetry (DSC), polarisation optical microscopy (POM) and X‐ray diffraction revealed that the chiral N‐BTA derivatives with branched 3,7‐dimethyloctanoyl chains were liquid crystalline and the mesophase was assigned as Colho. In contrast, N‐BTA derivatives with linear tetradecanoyl or octanoyl chains lacked a mesophase and were obtained as crystalline compounds. Variable‐temperature infrared spectroscopy showed the presence of threefold, intermolecular hydrogen bonding between neighbouring molecules in the mesophase of the chiral N‐BTAs. In the crystalline state at room temperature a more complicated packing between the molecules was observed. Ultraviolet and circular dichroism spectroscopy on dilute solutions of N‐BTAs revealed a cooperative self‐assembly behaviour of the N‐BTA molecules into supramolecular polymers with preferred helicity when chiral alkyl chains were present. Both the sergeants‐and‐soldiers as well as the majority‐rules principles were operative in stacks of N‐BTAs. In fact, the self‐assembly of N‐BTAs resembles closely that of their carbonyl (CO)‐centred counterparts, with the exception that aggregation is weaker and amplification of chirality is less pronounced. The differences in the self‐assembly of N‐ and CO‐BTAs were analysed by density functional theory (DFT) calculations. These reveal a substantially lower interaction energy between the monomeric units in the supramolecular polymers of N‐BTAs. The lower interaction energy is due to the higher energy penalty for rotation around the PhNH bond compared to the PhCO bond and the diminished magnitude of dipole–dipole interactions. Finally, we observed that mixed stacks are formed in dilute solution when mixing N‐BTAs and CO BTAs.
ChemInform Abstract: Thermodynamic and Structural Investigations of Ammonium Borohydride, a Solid with a Highest Content of Thermodynamically and Kinetically Accessible Hydrogen.
Authors: Karkamkar Abhijeet , Kathmann Shawn M. , Schenter Gregory K. , Heldebrant David J. , Hess Nancy , Gutowski Maciej , Autrey Tom 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Transport Properties of Undoped and Br‐Doped PbTe Sintered at High‐Temperature and Pressure ≥ 4.0 GPa.
Authors: Dong Yongkwan , McGuire Michael A. , Malik Abds‐Sami , DiSalvo Francis J. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: One‐Pot, High‐Yield Synthesis of Titanate Nanotube Bundles Decorated by Pd (Au) Clusters for Stable Electrooxidation of Methanol.
Authors: Xue Xiudong , Gu Li , Cao Xuebo , Song Yingying , Zhu Lianwen , Chen Peng 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Lanthanum Phosphite Microspheres: Hydrothermal Synthesis, ab initio Structure Determination, Morphology and Photoluminescence of La(HO)(HPO3).
Authors: Xiong Ding‐Bang , Zhao Yu‐Feng , Gulay Lubomir D. , Zhao Jing‐Tai 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis and Magnetic Properties of 12L‐Perovskites Ba4LnIr3O12 (Ln = Lanthanides).
Authors: Shimoda Yuki , Doi Yoshihiro , Wakeshima Makoto , Hinatsu Yukio 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Al Lewis Acid‐Catalyzed Regiodivergent 1,2‐Rearrangement of α‐Siloxy Aldehydes: Scope and Mechanism.
Authors: Ohmatsu Kohsuke , Tanaka Takayuki , Ooi Takashi , Maruoka Keiji 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Efficient and Convenient Oxidation of Thiols to Symmetrical Disulfide with Silica—PCl5/NaNO2 in Water.
Authors: Pathak Uma , Pandey Lokesh Kumar , Mathur Sweta 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Efficient and Facile Method for the Nitration of Aromatic Compounds by Nitric Acid in Micellar Media.
Authors: Sana S. , Tasneem Tasneem , Ali M. Moazzam , Rajanna K. C. , Saiprakash P. K. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Catalytic, Broensted Base Strategy for Intermolecular Allylic C—H Amination.
Authors: Reed Sean A. , Mazzotti Anthony R. , White M. Christina 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Thio FCMA Intermediates as Strong Acyl Donors: A General Solution to the Formation of Complex Amide Bonds.
Authors: Rao Yu , Li Xuechen , Danishefsky Samuel J. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Formation of Secondary or Tertiary Aliphatic Amines in Aqueous Media.
Authors: Simion Alina Marieta , Arimura Takashi , Miyazawa Akira , Simion Cristian , Prakash G. K. Surya , Olah George A. , Tashiro Masashi 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: B‐Alkylcatecholborane‐Mediated Tandem Radical Conjugated Addition—Aldol Cyclization.
Authors: Beauseigneur Alice , Ericsson Cecilia , Renaud Philippe , Schenk Kurt 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Hydrogen‐Bonding Asymmetric Metal Catalysis with α‐Amino Acids: A Simple and Tunable Approach to High Enantioinduction.
Authors: Lu Yingdong , Johnstone Tim C. , Arndtsen Bruce A. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Nickel‐Catalyzed Conjugate Addition of Simple Alkenes to Enones.
Authors: Ogoshi Sensuke , Haba Toshifumi , Ohashi Masato 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Asymmetric Aldol Reaction of Ketones with Alkenyl Trichloroacetates Catalyzed by Dibutyltin Dimethoxide and BINAP·Silver(I) Complex: Construction of a Chiral Tertiary Carbon Center.
Authors: Yanagisawa Akira , Terajima Yuuki , Sugita Kazuma , Yoshida Kazuhiro 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Novel Approach to the Practical Synthesis of Sulfides: An InBr3—Et3SiH Catalytic System Promoted the Direct Reductive Sulfidation of Acetals with Disulfides.
Authors: Sakai Norio , Moritaka Kohei , Konakahara Takeo 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Simple and Convenient Methods for Synthesis, Resolution and Application of Aminonaphthols.
Authors: Periasamy Mariappan , Anwar Shaik , Reddy Meda Narsi 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of 1‐Methyleneindenes via Palladium‐Catalyzed Tandem Reactions.
Authors: Ye Shengqing , Gao Ke , Zhou Haibo , Yang Xiaodi , Wu Jie 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Asymmetric Total Synthesis of (‐)‐Plicatic Acid via a Highly Enantioselective and Diastereoselective Nucleophilic Epoxidation of Acyclic Trisubstituted Olefins.
Authors: Sun Bing‐Feng , Hong Ran , Kang Yan‐Biao , Deng Li 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Tetrasubstituted Furans by PdII‐Catalyzed Three‐Component Domino Reactions of 2‐(1‐Alkynyl)‐2‐alken‐1‐ones with Nucleophiles and Vinyl Ketones or Acrolein.
Authors: Liu Renrong , Zhang Junliang 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Regio‐ and Stereoselective Synthesis of Multisubstituted 3‐Pyrrolines.
Authors: Xu Jian Feng , Li Peng Bin , Wu Lu Ling , Huang Xian 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Poly(ethylene glycol): An Alternative Solvent for the Synthesis of Cyclic Carbonate from Vicinal Halohydrin and Carbon Dioxide.
Authors: Wang Jing‐Lun , He Liang‐Nian , Dou Xiao‐Yong , Wu Fang 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Divergent Approach to the Synthesis of 3‐Substituted‐2‐pyrazolines: Suzuki Cross‐Coupling of 3‐Sulfonyloxy‐2‐pyrazolines.
Authors: Grimm Jonathan B. , Wilson Kevin J. , Witter David J. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: One‐Pot Electrochemical Synthesis of Fused Indole Derivatives Containing Active Hydroxyl Groups in Aqueous Medium.
Authors: Zeng Cheng‐Chu , Liu Fu‐Jian , Ping Da‐Wei , Hu Li‐Ming , Cai Yuan‐Li , Zhong Ru‐Gang 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Ligand‐Free‐Palladium‐Catalyzed Direct 4‐Arylation of Isoxazoles Using Aryl Bromides.
Authors: Fall Yacoub , Reynaud Celine , Doucet Henri , Santelli Maurice 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of 6‐Substituted Imidazo[2,1‐b]thiazoles via Pd/Cu‐Mediated Sonogashira Coupling in Water.
Authors: Kamali Taghi A. , Bakherad Mohammad , Nasrollahzadeh Mahmoud , Farhangi Shiva , Habibi Davood 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Base‐Promoted Tandem Reaction of 3‐(1‐Alkynyl)chromones with 1,3‐Dicarbonyl Compounds: An Efficient Approach to Functional Xanthones.
Authors: Zhao Lizhi , Xie Fuchun , Cheng Gang , Hu Youhong 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Microwave‐Assisted Silver(I)‐Mediated Selective O‐Alkylation of Aromatic Imidate Systems.
Authors: Singh Brajendra K. , Cavalluzzo Claudia , De Maeyer Marc , Debyser Zeger , Parmar Virinder S. , Van der Eycken Erik 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.