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1.
Jochen Fesseler Dr. Jae‐Hun Jeoung Prof. Dr. Holger Dobbek 《Angewandte Chemie (International ed. in English)》2015,54(29):8560-8564
Ni,Fe‐containing CO dehydrogenases (CODHs) use a [NiFe4S4] cluster, termed cluster C, to reversibly reduce CO2 to CO with high turnover number. Binding to Ni and Fe activates CO2, but current crystal structures have insufficient resolution to analyze the geometry of bound CO2 and reveal the extent and nature of its activation. The crystal structures of CODH in complex with CO2 and the isoelectronic inhibitor NCO? are reported at true atomic resolution (dmin≤1.1 Å). Like CO2, NCO? is a μ2,η2 ligand of the cluster and acts as a mechanism‐based inhibitor. While bound CO2 has the geometry of a carboxylate group, NCO? is transformed into a carbamoyl group, thus indicating that both molecules undergo a formal two‐electron reduction after binding and are stabilized by substantial π backbonding. The structures reveal the combination of stable μ2,η2 coordination by Ni and Fe2 with reductive activation as the basis for both the turnover of CO2 and inhibition by NCO?. 相似文献
2.
Dr. Jifu Duan Dr. Anja Hemschemeier David J. Burr Dr. Sven T. Stripp Prof. Eckhard Hofmann Prof. Thomas Happe 《Angewandte Chemie (International ed. in English)》2023,62(7):e202216903
Hydrogenases are H2 converting enzymes that harbor catalytic cofactors in which iron (Fe) ions are coordinated by biologically unusual carbon monoxide (CO) and cyanide (CN−) ligands. Extrinsic CO and CN−, however, inhibit hydrogenases. The mechanism by which CN− binds to [FeFe]-hydrogenases is not known. Here, we obtained crystal structures of the CN−-treated [FeFe]-hydrogenase CpI from Clostridium pasteurianum. The high resolution of 1.39 Å allowed us to distinguish intrinsic CN− and CO ligands and to show that extrinsic CN− binds to the open coordination site of the cofactor where CO is known to bind. In contrast to other inhibitors, CN− treated crystals show conformational changes of conserved residues within the proton transfer pathway which could allow a direct proton transfer between E279 and S319. This configuration has been proposed to be vital for efficient proton transfer, but has never been observed structurally. 相似文献
3.
Chi Chung Lee Yilin Hu Markus W. Ribbe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(4):1235-1238
Nitrogenase cofactors can be extracted into an organic solvent to catalyze the reduction of cyanide (CN−), carbon monoxide (CO), and carbon dioxide (CO2) without using adenosine triphosphate (ATP), when samarium(II) iodide (SmI2) and 2,6‐lutidinium triflate (Lut‐H) are employed as a reductant and a proton source, respectively. Driven by SmI2, the cofactors catalytically reduce CN− or CO to C1–C4 hydrocarbons, and CO2 to CO and C1–C3 hydrocarbons. The C C coupling from CO2 indicates a unique Fischer–Tropsch‐like reaction with an atypical carbonaceous substrate, whereas the catalytic turnover of CN−, CO, and CO2 by isolated cofactors suggests the possibility to develop nitrogenase‐based electrocatalysts for the production of hydrocarbons from these carbon‐containing compounds. 相似文献
4.
《Polyhedron》2002,21(18):1775-1778
The complex [Rh(CN)(O2)(PPh3)2(XNC)](CH2Cl2) has been obtained under ambient conditions from solutions containing trans-[Rh(CN)(PPh3)2(XNC)] upon exposure to air. The compound is unusual in that analogues containing the more strongly electron-donating ligands Cl−, N3− and NCO− (among others) in place of CN− are not formed. 相似文献
5.
Jackson P Fisher KJ Attalla MI 《Journal of the American Society for Mass Spectrometry》2011,22(8):1420-1431
The reaction between CO2 and aqueous amines to produce a charged carbamate product plays a crucial role in post-combustion capture chemistry when
primary and secondary amines are used. In this paper, we report the low energy negative-ion CID results for several anionic
carbamates derived from primary and secondary amines commonly used as post-combustion capture solvents. The study was performed
using the modern equivalent of a triple quadrupole instrument equipped with a T-wave collision cell. Deuterium labeling of
2-aminoethanol (1,1,2,2,-d4-2-aminoethanol) and computations at the M06-2X/6-311++G(d,p) level were used to confirm the identity of the fragmentation
products for 2-hydroxyethylcarbamate (derived from 2-aminoethanol), in particular the ions CN−, NCO− and facile neutral losses of CO2 and water; there is precedent for the latter in condensed phase isocyanate chemistry. The fragmentations of 2-hydroxyethylcarbamate
were generalized for carbamate anions derived from other capture amines, including ethylenediamine, diethanolamine, and piperazine.
We also report unequivocal evidence for the existence of carbamate anions derived from sterically hindered amines (Tris(2-hydroxymethyl)aminomethane and 2-methyl-2-aminopropanol). For the suite of carbamates investigated, diagnostic losses include
the decarboxylation product (−CO2, 44 mass units), loss of 46 mass units and the fragments NCO− (m/z 42) and CN− (m/z 26). We also report low energy CID results for the dicarbamate dianion (−O2CNHC2H4NHCO2−) commonly encountered in CO2 capture solution utilizing ethylenediamine. Finally, we demonstrate a promising ion chromatography-MS based procedure for
the separation and quantitation of aqueous anionic carbamates, which is based on the reported CID findings. The availability
of accurate quantitation methods for ionic CO2 capture products could lead to dynamic operational tuning of CO2 capture-plants and, thus, cost-savings via real-time manipulation of solvent regeneration energies. 相似文献
6.
Tomáš Weidlich Libor Dušek Barbora Vystrčilová Aleš Eisner Petr Švec Aleš Růžička 《应用有机金属化学》2012,26(6):293-300
The potential catalytic activity of selected C,N‐chelated organotin(IV) compounds (e.g. halides and trifluoroacetates) for derivatization of both dimethyl carbonate (DMC) and diethyl carbonate (DEC) was investigated. Some tri‐, di‐ and monoorganotin(IV) species (LCN(n‐Bu)2SnCl (1), LCN(n‐Bu)2SnCl.HCl (1a), LCN(n‐Bu)2SnI (2), LCNPh2SnCl (3), LCNPh2SnI (4), LCN(n‐Bu)SnCl2 (5), LCNSnBr3 (6) and [LCNSn(OC(O)CF3)]2(μ‐O)(μ‐OC(O)CF3)2 (7)) bearing the LCN moiety (LCN = 2‐(N,N‐dimethylaminomethyl)phenyl‐) were assessed as catalysts for reactions of both DMC and DEC with various substituted anilines. The catalytic activities of 4 and 7 for derivatization of DMC with p‐substituted phenols were studied for comparison with the standard base K2CO3/Silcarbon K835 catalyst (catalyst 8). The composition of resulting reaction mixtures was monitored by multinuclear NMR spectroscopy, GC and GC‐MS techniques. In general, catalysts 1, 3 and 7 exhibited the highest catalytic activity for all reactions studied, while some of them yielded selectively carbonates, carbamates, lactam or substituted urea. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
7.
《Radiation Physics and Chemistry》2008,77(6):761-767
Cyanide (CN−), thiocyanate (SCN−), and copper(I) cyanide (Cu(CN)43−) are common constituents in the wastes of many industrial processes such as metal finishing and gold mining, and their treatment is required before the safe discharge of effluent. The oxidation of CN−, SCN−, and Cu(CN)43− by ferrate(VI) (FeVIO42−; Fe(VI)) and ferrate(V) (FeVO43−; Fe(V)) has been studied using stopped-flow and premix pulse radiolysis techniques. The rate laws for the oxidation of cyanides were found to be first-order with respect to each reactant. The second-order rate constants decreased with increasing pH because the deprotonated species, FeO42−, is less reactive than the protonated Fe(VI) species, HFeO4−. Cyanides react 103–105 times faster with Fe(V) than with Fe(VI). The Fe(V) reaction with CN− proceeds by sequential one-electron reductions from Fe(V) to Fe(IV) to Fe(III). However, a two-electron transfer process from Fe(V) to Fe(III) occurs in the reaction of Fe(V) with SCN− and Cu(CN)43−. The toxic CN− species of cyanide wastes is converted into relatively non-toxic cyanate (NCO−). Results indicate that Fe(VI) is highly efficient in removing cyanides from electroplating rinse water and gold mill effluent. 相似文献
8.
Various novel double metal cyanide (DMC) catalysts were successfully prepared by modifying the central metal (M) and one of cyanide ion (CN-) in Zna[M(CN)b]c complex. Such modifications have significant impact on the catalytic efficiency as well as the polymer selectivity for the reaction of PO/CO2. Zn–Ni(Ⅱ) DMC is a potential catalyst for alternating copolymerization of PO/CO2, and DMC catalysts based on Zn3[Co(CN)5X]2 (X = Br-and N3-) exhibit moderate efficiency for the production of polycarbonates. This research presents the preliminary exploration of novel DMC complex via chemical modification of its central metal and ligand. 相似文献
9.
Diorganotin(IV) dichlorides of formula LCNRSnCl2 (where R is nBu or Ph) containing one LCN chelating ligand were hydrolyzed with aqueous sodium hydroxide in benzene. The composition of the products is strongly dependent on the amount of hydroxide. The partially hydrolyzed compounds of composition (LCNRSnCl)2(µ‐O) were isolated as crystalline products. A hydrolysis where more than one molar equivalent of NaOH is employed gave only a mixture of unidentifiable products. The structure of (LCNPhSnCl)2(µ‐O) was determined by X‐ray diffraction techniques in the solid state. In solution there was a mixture of diastereoisomers found, where the tin atoms serve as a stereogenic centers. The catalytic activity of starting dichlorides as well as (LCNPhSnCl)2(µ‐O) in various transesterification processes was investigated. The activity is very low in the case of starting dichlorides. When two molar equivalents of NaH are added or (LCNPhSnCl)2(µ‐O) is employed in the catalytic experiments, the activity is comparable to the literature data. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
Mengmiao Sun Guanzheng Wu Jiadi Jiang Yidong Yang Aijun Du Lei Dai Xin Mao Qing Qin 《Angewandte Chemie (International ed. in English)》2023,62(19):e202301957
The electrochemical NO3− reduction and its coupling with CO2 can provide novel and clean routes to synthesize NH3 and urea, respectively. However, their practical application is still impeded by the lack of efficient catalysts with desirable Faradaic efficiency (FE) and yield rate. Herein, we report the synthesis of molybdenum oxide nanoclusters anchored on carbon black (MoOx/C) as electrocatalyst. It affords an outstanding FE of 98.14 % and NH3 yield rate of 91.63 mg h−1 mgcat.−1 in NO3− reduction. Besides, the highest FE of 27.7 % with a maximum urea yield rate of 1431.5 μg h−1 mgcat.−1 toward urea is also achieved. The formation of electron-rich MoOx nanoclusters with highly unsaturated metal sites in the MoOx/C heterostructure is beneficial for enhanced catalytic performance. Studies on the mechanism reveal that the stabilization of *NO and *CO2NOOH intermediates are critical for the NH3 and urea synthesis, respectively. 相似文献
11.
Through a combination of Raman spectroscopy, multi-element NMR spectroscopy and chemical analysis, the differences between the action of carbonate and carbamate as agents for dissolving Cs3PMo12O40⋅xH2O(s) (CPM) and ZrMO2O7(OH)2(H2O)2(s) (ZM) have been elucidated. Alkaline H2NCO−2/HCO3−/CO32− solutions, derived from the dissolution of ammonium carbamate (NH4H2NCO2; AC), dissolve CPM by base hydrolysis of the PMo12O403− Keggin anion, ultimately forming [MoO4]2− and PO43− when excess base is present. If the initial concentration of H2NCO2−/HCO3−/ CO32− is lowered, base hydrolysis is incomplete and the dissolved species include [Mo7O24]6− and [P2Mo5O23]6−, and undissolved solid Cs3PMo12O40, CsxNH7−xPMo11O39, and CsxNH6−xMo7O24 remain. Na2CO3 solutions dissolve Cs3PMo12O40 through a similar mechanism, but the dissolution rate is much lower. We attribute this difference to the different buffering effects of H2NCO2−/HCO3−/CO32− and CO32−/HCO3− solutions, and the instability of carbamic acid, the protonated form of H2NCO2− (which rapidly decomposes into NH3 and CO2). The ability of NH3 to produce NH4+ and OH−, together with the evolution of CO2 gas, drive the reaction forward. Low temperature measurements under conditions where pure H2NCO2− is kinetically stable, allowed the rates of dissolution of CPM by H2NCO2− and CO32− to be compared directly, confirming the faster dissolution by H2NCO2−. Compared to CPM, the dissolution of ZM by H2NCO2−/HCO3−/CO32− is a much slower process and is driven by the formation of soluble ZrIV-carbonate complexes and MoO42−. The driving force for the dissolution of ZM is the superior complexing ability of carbonate over carbamate; consequently solutions containing a higher carbonate concentration dissolve ZM faster. 相似文献
12.
Catalytic Reduction of CN−, CO,and CO2 by Nitrogenase Cofactors in Lanthanide‐Driven Reactions 下载免费PDF全文
Dr. Chi Chung Lee Prof. Dr. Yilin Hu Prof. Dr. Markus W. Ribbe 《Angewandte Chemie (International ed. in English)》2015,54(4):1219-1222
Nitrogenase cofactors can be extracted into an organic solvent to catalyze the reduction of cyanide (CN?), carbon monoxide (CO), and carbon dioxide (CO2) without using adenosine triphosphate (ATP), when samarium(II) iodide (SmI2) and 2,6‐lutidinium triflate (Lut‐H) are employed as a reductant and a proton source, respectively. Driven by SmI2, the cofactors catalytically reduce CN? or CO to C1–C4 hydrocarbons, and CO2 to CO and C1–C3 hydrocarbons. The C? C coupling from CO2 indicates a unique Fischer–Tropsch‐like reaction with an atypical carbonaceous substrate, whereas the catalytic turnover of CN?, CO, and CO2 by isolated cofactors suggests the possibility to develop nitrogenase‐based electrocatalysts for the production of hydrocarbons from these carbon‐containing compounds. 相似文献
13.
Dr. Yetsedaw A. Tsegaw Dr. Hongmin Li Prof. em. Dr. Dr. h. c. Lester Andrews Prof. Dr. Han-Gook Cho Patrick Voßnacker Dr. Helmut Beckers Prof. Dr. Sebastian Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(5):e202103142
An investigation of pulsed-laser-ablated Zn, Cd and Hg metal atom reactions with HCN under excess argon during co-deposition with laser-ablated Hg atoms from a dental amalgam target also provided Hg emissions capable of photoionization of the CN photo-dissociation product. A new band at 1933.4 cm−1 in the region of the CN and CN+ gas-phase fundamental absorptions that appeared upon annealing the matrix to 20 K after sample deposition, and disappeared upon UV photolysis is assigned to (Ar)nCN+, our key finding. It is not possible to determine the n coefficient exactly, but structure calculations suggest that one, two, three or four argon atoms can solvate the CN+ cation in an argon matrix with C−N absorptions calculated (B3LYP) to be between 2317.2 and 2319.8 cm−1. Similar bands were observed in solid krypton at 1920.5, in solid xenon at 1935.4 and in solid neon at 1947.8 cm−1. H13CN reagent gave an 1892.3 absorption with shift instead, and a 12/13 isotopic frequency ratio–nearly the same as found for 13CN+ itself in the gas phase and in the argon matrix. The CN+ molecular ion serves as a useful infrared probe to examine Ng clusters. The following ion reactions are believed to occur here: the first step upon sample deposition is assisted by a focused pulsed YAG laser, and the second step occurs on sample annealing: (Ar)2++CN→Ar+CN+→(Ar)nCN+. 相似文献
14.
Yongzhi Zhong Xiangdong Kong Dr. Zhigang Geng Prof. Jie Zeng Prof. Xuan Luo Prof. Lin Zhang 《Chemphyschem》2020,21(18):2051-2055
Electroreduction of CO2 into carbonaceous fuels or industrial chemicals using renewable energy sources is an ideal way to promote global carbon recycling. Thus, it is of great importance to develop highly selective, efficient, and stable catalysts. Herein, we prepared cobalt single atoms (Co SAs) coordinated with phthalocyanine (Co SAs-Pc). The anchoring of phthalocyanine with Co sites enabled electron transfer from Co sites to CO2 effectively via the π-conjugated system, resulting in high catalytic performance of CO2 electroreduction into CO. During the process of CO2 electroreduction, the Faradaic efficiency (FE) of Co SAs-Pc for CO was as high as 94.8 %. Meanwhile, the partial current density of Co SAs-Pc for CO was −11.3 mA cm−2 at −0.8 V versus the reversible hydrogen electrode (vs RHE), 18.83 and 2.86 times greater than those of Co SAs (−0.60 mA cm−2) and commercial Co phthalocyanine (−3.95 mA cm−2), respectively. In an H-cell system operating at −0.8 V vs RHE over 10 h, the current density and FE for CO of Co SAs-Pc dropped by 3.2 % and 2.5 %. A mechanistic study revealed that the promoted catalytic performance of Co SAs-Pc could be attributed to the accelerated reaction kinetics and facilitated CO2 activation. 相似文献
15.
Lilith Domnik Holger Dobbek Christophe Léger Sébastien Dementin Vincent Fourmond 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):18934-18938
Ni‐containing CO dehydrogenases (CODHs) are very efficient metalloenzymes that catalyze the conversion between CO2 and CO. They are a source of inspiration for designing CO2‐reduction catalysts and can also find direct use in biotechnology. They are deemed extremely sensitive to O2, but very little is known about this aspect of their reactivity. We investigated the reaction with O2 of Carboxydothermus hydrogenoformans (Ch) CODH II and the homologous, recently characterized CODH from Desulfovibrio vulgaris (Dv) through protein film voltammetry and solution assays (in the oxidative direction). We found that O2 reacts very quickly with the active site of CODHs, generating species that reactivate upon reduction—this was unexpected. We observed that distinct CODHs exhibit different behaviors: Dv CODH reacts half as fast with O2 than Ch CODH, and only the former fully recovers the activity upon reduction. The results raise hope that fast CO/CO2 biological conversion may be feasible under aerobic conditions. 相似文献
16.
《Angewandte Chemie (International ed. in English)》2017,56(10):2795-2799
The first deprotonation of a borohydride anion was achieved by treatment of [BH(CN)3]− with strong non‐nucleophilic bases, which resulted in the formation of alkali‐metal salts of the tricyanoborate dianion B(CN)32− in up to 97 % yield and 99.5 % purity. [BH(CN)3]− is less acidic than (Me3Si)2NH but a stronger acid than i Pr2NH. Less sterically hindered, more nucleophilic bases such as PhLi and MeLi mostly attack a CN group under formation of imine dianions [RC(N)B(CN)3]2−, which can be hydrolyzed to ketones of the [RC(O)B(CN)3]− type. The boron‐centered nucleophile B(CN)32− reacts with CO2 and CN+ reagents to give salts of the [B(CN)3CO2]2− dianion and the tetracyanoborate anion [B(CN)4]−, respectively, in excellent yields. 相似文献
17.
Dr. Peng Gao Dr. Zihao Cui Dr. Xiaolei Liu Dr. Yaqiang Wu Dr. Qianqian Zhang Prof. Zeyan Wang Prof. Zhaoke Zheng Prof. Hefeng Cheng Prof. Yuanyuan Liu Prof. Qing Li Prof. Baibiao Huang Prof. Peng Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(50):e202201095
Lead halide perovskite has triggered a lot of research due to its superior optical properties. However, halide perovskite materials have poor environmental stabilities and are easily affected by external factors such as water and heat, resulting in structural decomposition and performance failure. Contrary to this commonplace concept, it is found that CsPbBr3 (CPB) can convert to CsPb2Br5 (CP2B5) partially when meeting a small amount of water, and the CsPbBr3@CsPb2Br5 (CPB@CP2B5) composite is synthesized by an in situ method accordingly. The CPB@CP2B5 composite shows an enhanced catalytic performance compared with pure CPB, as well as a dramatically synergistic effect of photo and thermal for catalytic CO2 hydrogenation. The CO production rate of CPB@CP2B5 is determined as 69 μmol g−1 h−1 under light irradiation at 200 °C, which is 156.8 and 43.4 times higher than that under pure photo (0.44 μmol g−1 h −1) and pure thermal (1.59 μmol g−1 h −1) condition, respectively. Meanwhile, the CPB@CP2B5 sample is also stable, which shows no significant decline in the catalytic activity during 8 cycles of repeated experiments. The probable mechanism is explored by utilizing a series of in situ characterizations. 相似文献
18.
Bithiophene triarylborane dyad: An efficient material for the selective detection of CN− and F− ions
Sakthivel Perumal Sekar Karuppannan Sivaraman Gandhi Singaravadivel Subramanian Anbu Govindasamy Senthil Kumar Gopal 《应用有机金属化学》2020,34(1):e5257
A new fluorescent chemosensor based on bithiophene coupled dimesitylborane (BMB-1) was synthesized and characterized. BMB-1 was used for colorimetric and turn-on fluorescent sensing of cyanide (CN−) and fluoride (F−) ions, in the presence of other competitive anions in an aqueous (CH3CN–H2O) medium. BMB-1 showed a hypsochromic shift (blue shift) with addition of CN− and F− ions in absorption studies. The lower detection level of CN− and F− ions is 1.37 × 10−9 and 1.75 × 10−9 M, respectively. The BMB-1 binding mechanism is based on the nucleophilic addition of CN− and F− ions in the internal charge transfer transition of bithio moiety to the boranylmesitylene unit, and the color changes were observed under UV light. This result is further confirmed by Fourier transform infrared spectroscopy, mass spectrometry and density functional theory calculations. Also, the BMB-1 probe is found to be a good adsorbent for the removal of F− ions in real water samples using the adsorption technique. 相似文献
19.
Dr. Hemlata Agarwala Xiaoyu Chen Julien R. Lyonnet Dr. Ben A. Johnson Prof. Dr. Mårten Ahlquist Prof. Dr. Sascha Ott 《Angewandte Chemie (International ed. in English)》2023,62(17):e202218728
Molecular electrocatalysts for CO2-to-CO conversion often operate at large overpotentials, due to the large barrier for C−O bond cleavage. Illustrated with ruthenium polypyridyl catalysts, we herein propose a mechanistic route that involves one metal center that acts as both Lewis base and Lewis acid at different stages of the catalytic cycle, by density functional theory in corroboration with experimental FTIR. The nucleophilic character of the Ru center manifests itself in the initial attack on CO2 to form [ Ru -CO2]0, while its electrophilic character allows for the formation of a 5-membered metallacyclic intermediate, [ Ru -CO2CO2]0,c, by addition of a second CO2 molecule and intramolecular cyclization. The calculated activation barrier for C−O bond cleavage via the metallacycle is decreased by 34.9 kcal mol−1 as compared to the non-cyclic adduct in the two electron reduced state of complex 1 . Such metallacyclic intermediates in electrocatalytic CO2 reduction offer a new design feature that can be implemented consciously in future catalyst designs. 相似文献
20.
Dr. Shanti G. Patra Dr. Erzsébet Illés Dr. Amir Mizrahi Prof. Dr. Dan Meyerstein 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(3):711-720
CoII salts in the presence of HCO3−/CO32− in aqueous solutions act as electrocatalysts for water oxidation. It comprises of several key steps: (i) A relatively small wave at Epa≈0.71 V (vs. Ag/AgCl) owing to the CoIII/II redox couple. (ii) A second wave is observed at Epa≈1.10 V with a considerably larger current. In which the CoIII undergoes oxidation to form a CoIV species. The large current is attributed to catalytic oxidation of HCO3−/CO32− to HCO4−. (iii) A process with very large currents at >1.2 V owing to the formation of CoV(CO3)3−, which oxidizes both water and HCO3−/CO32−. These processes depend on [CoII], [NaHCO3], and pH. Chronoamperometry at 1.3 V gives a green deposit. It acts as a heterogeneous catalyst for water oxidation. DFT calculations point out that Con(CO3)3n−6, n=4, 5 are attainable at potentials similar to those experimentally observed. 相似文献