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Frontispiece: Heterolytic Cleavage of Hydrogen by an Iron Hydrogenase Model: An Fe‐H⋅⋅⋅H‐N Dihydrogen Bond Characterized by Neutron Diffraction
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Dr. Tianbiao Liu Dr. Xiaoping Wang Dr. Christina Hoffmann Dr. Daniel L. DuBois Dr. R. Morris Bullock 《Angewandte Chemie (International ed. in English)》2014,53(21)
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Heterolytic Cleavage of Hydrogen by an Iron Hydrogenase Model: An Fe‐H⋅⋅⋅H‐N Dihydrogen Bond Characterized by Neutron Diffraction
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Dr. Tianbiao Liu Dr. Xiaoping Wang Dr. Christina Hoffmann Dr. Daniel L. DuBois Dr. R. Morris Bullock 《Angewandte Chemie (International ed. in English)》2014,53(21):5300-5304
Hydrogenase enzymes in nature use hydrogen as a fuel, but the heterolytic cleavage of H? H bonds cannot be readily observed in enzymes. Here we show that an iron complex with pendant amines in the diphosphine ligand cleaves hydrogen heterolytically. The product has a strong Fe‐H???H‐N dihydrogen bond. The structure was determined by single‐crystal neutron diffraction, and has a remarkably short H???H distance of 1.489(10) Å between the protic N‐Hδ+ and hydridic Fe‐Hδ? part. The structural data for [CpFe H (PtBu2NtBu2 H )]+ provide a glimpse of how the H? H bond is oxidized or generated in hydrogenase enzymes. These results now provide a full picture for the first time, illustrating structures and reactivity of the dihydrogen complex and the product of the heterolytic cleavage of H2 in a functional model of the active site of the [FeFe] hydrogenase enzyme. 相似文献
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OH⋅⋅⋅N and CH⋅⋅⋅O Hydrogen Bonds Control Hydration of Pivotal Tropane Alkaloids: Tropinone⋅⋅⋅H2O Complex
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Dr. Patricia Écija Montserrat Vallejo‐López Dr. Luca Evangelisti Dr. José A. Fernández Prof. Dr. Alberto Lesarri Prof. Dr. Walther Caminati Dr. Emilio J. Cocinero 《Chemphyschem》2014,15(5):918-923
The effect of monohydration in equatorial/axial isomerism of the common motif of tropane alkaloids is investigated in a supersonic expansion by using Fourier‐transform microwave spectroscopy. The rotational spectrum reveals the equatorial isomer as the dominant species in the tropinone???H2O complex. The monohydrated complex is stabilized primarily by a moderate O?H???N hydrogen bond. In addition, two C?H???O weak hydrogen bonds also support this structure, blocking the water molecule and avoiding any molecular dynamics in the complex. The water molecule acts as proton donor and chooses the ternary amine group over the carbonyl group as a proton acceptor. The experimental work is supported by theoretical calculations; the accuracy of the B3LYP, M06‐2X, and MP2 methods is also discussed. 相似文献
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Karolis Norvaia Keith J. Flanagan Dire Gibbons Mathias O. Senge 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(46):16705-16709
Die Selektivität und funktionale Variabilität von Porphyrinkofaktoren basiert typischerweise auf der Substratbindung durch Metalloporphyrine, wobei die Pyrrolstickstoffatome nur zur Chelatisierung der Metallionen dienen. In einem ersten Schritt zu Porphyrinzentren mit “enzymähnlicher” Aktivität zeigt eine strukturelle und spektroskopische Untersuchung der Substratbindung im Kern jedoch, dass ein sattelverbogenes Porphyrin mit peripheren Aminorezeptorgruppen ( 1 , 2,3,7,8,12,13,17,18‐Oktaethyl‐5,10,15,20‐tetrakis(2‐aminophenyl)porphyrin), abhängig von der Azidität der Lösung, Analyte in einer schaltbaren Weise koordiniert. Das supramolekulare Ensemble weist eine hohe Affinität und Selektivität für das Pyrophosphatanion (2.26±0.021)×109 m ?1 auf. 1H‐NMR‐Spektroskopie liefert Einblicke in den wahrscheinlichen Bindungsmodus und erlaubt die Charakterisierung der Atropisomere, deren Struktur auch durch Röntgenstrukturanalysen aufgeklärt wurde. 相似文献
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Seenichamy Jeyaprakash Narayanan Bashyam Sridevi Tavarekere K. Chandrashekar Ashwani Vij Raja Roy 《Angewandte Chemie (International ed. in English)》1998,37(24):3394-3397
An unprecedented coupling reaction of heteroatom-containing tripyrranes leads to the formation of core-modified sapphyrins 1 and 2 , which self-assemble in the solid state to form supramolecular ladders. Weak C−H⋅⋅⋅S and C−H⋅⋅⋅Se hydrogen-bonding interactions in addition to C−H⋅⋅⋅N hydrogen bonds are responsible for the observed structures. 相似文献
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Dr. Russell W. Driver Prof. Timothy D. W. Claridge Prof. Steve Scheiner Prof. Martin D. Smith 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(46):16513-16521
The precise role of non‐conventional hydrogen bonds such as the C?H???O interaction in influencing the conformation of small molecules remains unresolved. Here we survey a series of β‐turn mimetics using X‐ray crystallography and NMR spectroscopy in conjunction with quantum calculation, and conclude that favourable torsional and electronic effects are important for the population of states with conformationally influential C?H???O interactions. Our results also highlight the challenge in attempting to deconvolute a myriad of interdependent noncovalent interactions in order to focus on the contribution of a single one. Within a small molecule that is designed to resemble the complexity of the environment within peptides and proteins, the interplay of different steric burdens, hydrogen‐acceptor/‐donor properties and rotational profiles illustrate why unambiguous conclusions based solely on NMR chemical shift data are extremely challenging to rationalize. 相似文献