- Mapping the Intricate Reactivity of Nanojars toward Molecules of Varying Acidity and Their Conjugate Bases Leading to Exchange of Pyrazolate Ligands
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A comprehensive reactivity study of nanojars toward 18 different acidic compounds with varying pKa, including 12 different carboxylic acids (both aliphatic and aromatic mono- and dicarboxylic acids), p-toluenesulfonic acid, hydrogen sulfate, hydrogen carbonate, carbonic acid, 1-decanethiol, and methanol, as well as four different conjugate bases (formate, acetate, benzoate, 2-bromoethanesulfonate) is carried out with the aid of electrospray-ionization mass spectrometry. Thus, the effect on nanojar substitution and breakdown pattern of a number of variables, such as concentration of reagent (acid or conjugate base), acidity of reagent (pKa), effect of acid vs conjugate base, steric effects, aromaticity, incarcerated anion and size of the nanojar, is evaluated. Of the substitution and breakdown products identified by mass spectrometry, acetate-substituted nanojars (Bu4N)2[CO3?{Cu27(μ-OH)27(μ-pz)27-x(μ-CH3COO)x}] (x = 1 and 2), as well as dimeric complexes (Bu4N)2[Cu2(μ-pz)2A2] (A = CO32- and SO42-) have been isolated and characterized by single-crystal X-ray diffraction. This study offers a detailed understanding of the behavior of nanojars of various sizes and with different incarcerated anions in the presence of the above-mentioned compounds at varying concentrations and tests the limits of the pyrazolate/carboxylate structural analogy in multinuclear metal complexes. The results point to the possibility of obtaining functionalized nanojars via pyrazolate/carboxylate ligand exchange, an aid in the design of anion extraction processes using nanojars or similar complexes as extracting agents.
- Hartman, Christian K.,Mezei, Gellert
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- Mechanism of the formation of a Mn-based CO2 reduction catalyst revealed by pulse radiolysis with time-resolved infrared detection
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Using a new technique, which combines pulse radiolysis with nanosecond time-resolved infrared (TRIR) spectroscopy in the condensed phase, we have conducted a detailed kinetic and mechanistic investigation of the formation of a Mn-based CO2 reduction electrocatalyst, [Mn(tBu 2-bpy)(CO)3]2 (tBu2-bpy = 4,4′-tBu2-2,2′-bipyridine), in acetonitrile. The use of TRIR allowed, for the first time, direct observation of all the intermediates involved in this process. Addition of excess [nBu 4N][HCO2] to an acetonitrile solution of fac-MnBr( tBu2-bpy)(CO)3 results in its quantitative conversion to the Mn-formate complex, fac-Mn(OCHO)(tBu 2-bpy)(CO)3, which is a precatalyst for the electrocatalytic reduction of CO2. Formation of the catalyst is initiated by one-electron reduction of the Mn-formate precatalyst, which produces the bpy ligand-based radical. This radical undergoes extremely rapid (τ = 77 ns) formate dissociation accompanied by a free valence shift to yield the five-coordinate Mn-based radical, Mn?( tBu2-bpy)(CO)3. TRIR data also provide evidence that the Mn-centered radical does not bind acetonitrile prior to its dimerization. This reaction occurs with a characteristically high radical-radical recombination rate (2kdim = (1.3 ± 0.1) × 109 M-1 s-1), generating the catalytically active Mn-Mn bound dimer.
- Grills, David C.,Farrington, Jaime A.,Layne, Bobby H.,Lymar, Sergei V.,Mello, Barbara A.,Preses, Jack M.,Wishart, James F.
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- Synthesis of silyl formates, formamides, and aldehydesviasolvent-free organocatalytic hydrosilylation of CO2
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Carbon dioxide (CO2) was used as a C1 source to prepare silyl formates, formamides, and aldehydes. Tetrabutylammonium acetate (TBAA) catalyzed the solvent-freeN-formylation of amines with CO2and hydrosilane to give formamides including Weinreb formamide, Me(MeO)NCHO, which was successively converted into aldehydes by one-pot reactions with Grignard reagents.
- Ema, Tadashi,Hasegawa, Jun-Ya,Hiyoshi, Mahoko,Murata, Takumi,Ratanasak, Manussada
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supporting information
p. 5783 - 5786
(2020/06/03)
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- Exploring Selectivity of 22 Acyclic Urea-, Carbazole- and Indolocarbazole-Based Receptors towards 11 Monocarboxylates
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Carboxylates are attractive target analytes in supramolecular analytical chemistry. 22 acyclic synthetic receptors with different numbers and geometric arrangements of hydrogen-bond donors (HBD) and hydrophobic moieties have been applied to experimentally study selective binding of 11 carboxylate anions of widely differing basicity, hydrophobicity and steric demand, which resulted in 242 accurately determined binding constants. It was found that besides the basicity of the anions, structural and steric factors of anions and receptors influence the binding. Several interesting cases are pinpointed and analysed. The ability of selected receptors to discriminate between anions according to structural features (hydrophilicity, substitution at α-carbon, etc.) is demonstrated. The present results give insight into carboxylate anion binding and make an important step towards systematic development of receptors with useful selectivity patterns and thereby to the practical use of receptor series in sensor arrays for carboxylate fingerprinting in mixtures.
- Martin, Kerli,N?ges, Juuli,Haav, Kristjan,Kadam, Sandip A.,Pung, Astrid,Leito, Ivo
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p. 5231 - 5237
(2017/09/29)
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- Use of formate salts as a hydride and a Co2 source in PGeP -palladium complex-catalyzed hydrocarboxylation of allenes
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Use of formate salts as a hydride as well as a CO2 source was achieved in a PGeP-palladium complex-catalyzed hydrocarboxylation of allenes through a highly efficient decarboxylation-carboxylation process. This reaction proceeds under mild conditions and provides an alternative strategy for utilizing formate salts as a C1 source.
- Zhu, Chuan,Takaya, Jun,Iwasawa, Nobuharu
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supporting information
p. 1814 - 1817
(2015/04/14)
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- Oxalate Formation in Electrochemical CO2 Reduction Catalyzed by Rhodium-Sulfur Cluster
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Electrochemical reduction of CO2 catalyzed by a triangular rhodium complex *)3(μ3-S)2>2+ selectively produced formate and oxalate in the presence of Bu4NBF4 and LiBF4, respectively, under the controlled potential electrolysis at -1.50 V (vs.SCE) in CO2-saturated CH3CN.A solution IR spectrum evidenced the adduct formation between *)3(μ3-S)2>0 and CO2 as the possible precursor for the oxalate formation.
- Kushi, Yoshinori,Nagao, Hirotaka,Nishioka, Takanori,Isobe, Kiyoshi,Tanaka, Koji
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p. 2175 - 2178
(2007/10/02)
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- HYDRATES OF ORGANIC COMPOUNDS - VIII. THE EFFECT OF CARBOXYLATE ANIONS ON THE FORMATION OF CLATHRATE HYDRATES OF TETRABUTYLAMMONIUM CARBOXYLATES.
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In this study, from the solid-liquid phase diagrams for 19 binary mixtures of tetrabutylammonium carboxylate-water, the effect of the shape and/or length of the alkyl group of a carboxylate anion on the stability (i. e. , melting point) and the crystal structure (i. e. , hydration number) of their clathrate hydrates has been systematically examined. These fundamental data would also offer a guiding principle, for example, for highly selective separation of a specific carboxylate anion from an aqueous solution containing several kinds of carboxylate anions by means of the formation of a mixed clathrate hydrate of tetrabutylammonium carboxylates.
- Nakayama,Torigata
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p. 171 - 174
(2007/10/02)
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