scholarly journals Electronic and molecular structures of the active-site H-cluster in [FeFe]-hydrogenase determined by site-selective X-ray spectroscopy and quantum chemical calculations

2014 ◽  
Vol 5 (3) ◽  
pp. 1187-1203 ◽  
Author(s):  
Camilla Lambertz ◽  
Petko Chernev ◽  
Katharina Klingan ◽  
Nils Leidel ◽  
Kajsa G. V. Sigfridsson ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Active Site ◽  
Quantum Chemical ◽  
Molecular Structures ◽  
X Ray ◽  
Structural Configurations ◽  
Site Selective

Site-selective X-ray spectroscopy discriminated the cubane and diiron units in the H-cluster of [FeFe]-hydrogenase revealing its electronic and structural configurations.

scholarly journals Synthesis of Bis(Carboranyl)amides 1,1′-μ-(CH2NH(O)C(CH2)n-1,2-C2B10H11)2 (n = 0, 1) and Attempt of Synthesis of Gadolinium Bis(Dicarbollide)

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1321
Author(s):  
Yasunobu Asawa ◽  
Aleksandra V. Arsent’eva ◽  
Sergey A. Anufriev ◽  
Alexei A. Anisimov ◽  
Kyrill Yu. Suponitsky ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
X Ray Diffraction ◽  
Stable Conformation ◽  
Acyl Chlorides ◽  
X Ray ◽  
Cesium Fluoride ◽  
The Stability

Bis(carboranyl)amides 1,1′-μ-(CH2NH(O)C(CH2)n-1,2-C2B10H11)2 (n = 0, 1) were prepared by the reactions of the corresponding carboranyl acyl chlorides with ethylenediamine. Crystal molecular structure of 1,1′-μ-(CH2NH(O)C-1,2-C2B10H11)2 was determined by single crystal X-ray diffraction. Treatment of bis(carboranyl)amides 1,1′-μ-(CH2NH(O)C(CH2)n-1,2-C2B10H11)2 with ammonium or cesium fluoride results in partial deboronation of the ortho-carborane cages to the nido-carborane ones with formation of [7,7′(8′)-μ-(CH2NH(O)C(CH2)n-7,8-C2B9H11)2]2−. The attempted reaction of [7,7′(8′)-μ-(CH2NH(O)CCH2-7,8-C2B9H11)2]2− with GdCl3 in 1,2-dimethoxy- ethane did not give the expected metallacarborane. The stability of different conformations of Gd-containing metallacarboranes has been estimated by quantum-chemical calculations using [3,3-μ-DME-3,3′-Gd(1,2-C2B9H11)2]− as a model. It was found that in the most stable conformation the CH groups of the dicarbollide ligands are in anti,anti-orientation with respect to the DME ligand, while any rotation of the dicarbollide ligand reduces the stability of the system. This makes it possible to rationalize the design of carborane ligands for the synthesis of gadolinium metallacarboranes on their base.

Electrochemical aromatization of dihydroazines. Effect of chalcogenophosphoryl (CGP) substituents on anodic oxidation of 9-CGP-9,10-dihydroacridines

Synthesis ◽  
2021 ◽  
Author(s):  
Alexander Schepochkin ◽  
Oleg N. Chupakhin ◽  
Nadezhda Demina ◽  
Maxim Averkov ◽  
Tatyana Shimanovskaya ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Structural Analysis ◽  
Quantum Chemical Calculations ◽  
Anodic Oxidation ◽  
Quantum Chemical ◽  
X Ray

The effect of chalcogenophosphoryl fragments on the anodic oxidation of 9-chalcogenophosphoryl-9,10-dihydroacridines was studied in detail. The data of X-ray structural analysis, quantum chemical calculations and cyclic voltammetry obtained for these compounds provide an explanation of the observed features. The direct electrochemical phosphorylation of acridine was first carried out successfully.

Structure and Reactivity of [Mo3-μ3S-(μS2)3]4+Complexes. Quantum Chemical Calculations, X-ray Structural Characterization, and Raman Spectroscopic Measurements

1998 ◽  
Vol 37 (11) ◽  
pp. 2633-2644 ◽  
Author(s):  
María J. Mayor-López ◽  
Jacques Weber ◽  
Kaspar Hegetschweiler ◽  
Marc D. Meienberger ◽  
Felix Joho ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Structural Characterization ◽  
Quantum Chemical ◽  
Spectroscopic Measurements ◽  
X Ray ◽  
Raman Spectroscopic

Evaluation of Aspects Controlling Crystallization of Nitrofurantoin

2019 ◽  
Vol 800 ◽  
pp. 9-13
Author(s):  
Aija Trimdale ◽  
Agris Bērziņš
Keyword(s):  
Gibbs Energy ◽  
Quantum Chemical Calculations ◽  
Organic Solvents ◽  
Quantum Chemical ◽  
Polymer Additives ◽  
Factors Affecting ◽  
X Ray

Nitrofurantoin was crystallized from multiple mixtures of water and organic solvents with and without additives to try to find and identify factors affecting phase obtained in crystallization and provide possible information on crystallization control. Obtained crystals were identified with powder X-ray diffractometry. Crystallization control possibilities were evaluated by using polymer additives and crystallization additives, by also using quantum chemical calculations to investigate the association of nitrofurantoin and additive molecules and calculate Gibbs energy of association.

The synergy of different solid-state techniques to elucidate the supramolecular assembly of two 1H-benzotriazole polymorphs

2019 ◽  
Vol 21 (36) ◽  
pp. 19879-19889
Author(s):  
María Mar Quesada-Moreno ◽  
Juan Ramón Avilés-Moreno ◽  
Juan Jesús López-González ◽  
Fco. Javier Zúñiga ◽  
Dolores Santa María ◽  
...  
Keyword(s):  
Solid State ◽  
Quantum Chemical Calculations ◽  
Absolute Configuration ◽  
Quantum Chemical ◽  
Supramolecular Structure ◽  
Supramolecular Assembly ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Absolute

4aα (chiral) and 4aβ (achiral) polymorphs of 1H-benzotriazole are studied by X-ray crystallography, SSNMR, IR, Raman, VCD, and quantum chemical calculations. The absolute configuration of the supramolecular structure of 4aα polymorph is determined.

3(5),4-Dimethyl- and 3,4,5-trimethylpyrazole at 200 K. X-ray crystallography and quantum-chemical analysis

1999 ◽  
Vol 55 (3) ◽  
pp. 441-447 ◽  
Author(s):  
Lourdes Infantes ◽  
Concepción Foces-Foces ◽  
Jose Elguero
Keyword(s):  
Quantum Chemical ◽  
Molecular Structures ◽  
Asymmetric Unit ◽  
Quantum Chemical Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
Crystal And Molecular Structures ◽  
Unit Form ◽  
Proton Disorder ◽  
Independent Molecules

The crystal and molecular structures of 3(5),4-dimethylpyrazole, C5H8N2, (I), and of 3,4,5-trimethylpyrazole, C6H10N2, (II), have been determined at 200 K. In (I) the 4,5-dimethylpyrazole tautomer is present in the solid state and the six independent molecules in the asymmetric unit form trimers via NH...N hydrogen bonds related by a pseudo centre of symmetry. The asymmetric unit of (II) contains one and a half molecules: these exhibit NH proton disorder and are hydrogen bonded to each other via their respective NH groups to form chains. Ab initio calculations at HF and B3LYP/6-31G** levels indicate that the 3,4-dimethylpyrazole tautomer is more stable than the 4,5-dimethylpyrazole tautomer by only approximately 0.5  kcal  mol−1 (1 kcal mol−1 = 4.184 kJ mol−1).

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