Solid state simulation of tetramer form of 5-aminoorotic acid: The vibrational spectra and molecular structure study by using MP2 and DFT calculations

Author(s):  
S. Ortiz ◽  
M. Alcolea Palafox ◽  
V.K. Rastogi ◽  
Rashmi Tomer
2010 ◽  
Vol 52 (2) ◽  
pp. 108-121 ◽  
Author(s):  
M. Alcolea Palafox ◽  
V.K. Rastogi ◽  
A. Guerrero-Martínez ◽  
G. Tardajos ◽  
H. Joe ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kurt F. Hoffmann ◽  
Anja Wiesner ◽  
Carsten Müller ◽  
Simon Steinhauer ◽  
Helmut Beckers ◽  
...  

AbstractOrganic fluoronium ions can be described as positively charged molecules in which the most electronegative and least polarizable element fluorine engages in two partially covalent bonding interactions to two carbon centers. While recent solvolysis experiments and NMR spectroscopic studies on a metastable [C–F–C]+ fluoronium ion strongly support the divalent fluoronium structure over the alternative rapidly equilibrating classical carbocation, the model system has, to date, eluded crystallographic analysis to confirm this phenomenon in the solid state. Herein, we report the single crystal structure of a symmetrical [C–F–C]+ fluoronium cation. Besides its synthesis and crystallographic characterization as the [Sb2F11]− salt, vibrational spectra are discussed and a detailed analysis concerning the nature of the bonding situation in this fluoronium ion and its heavier halonium homologues is performed, which provides detailed insights on this molecular structure.


2010 ◽  
Vol 88 (4) ◽  
pp. 309-317 ◽  
Author(s):  
Wendy A. Sears ◽  
Craig D. MacKinnon ◽  
Robert C. Mawhinney ◽  
Lauren C. Sinnemaki ◽  
Matthew J. Johnson ◽  
...  

A new synthetic route to mononitrated oligothiophenes is described, as well as the preparation of halogenated derivatives (Br, I) thereof. An unusual deep red colour is observed and explained, with the aid of DFT calculations, as arising from a significant quinoidal contribution to the molecular structure. The crystal structures of two compounds, H(C4H2S)3NO2 and Br(C4H2S)3NO2, are presented. Both compounds have planar sheets held together by intermolecular short contacts (hydrogen bonds and, for the latter, NO2···Br interactions); the sheets do not directly superimpose, so the effect of the π-stacking is not maximized. Solid-state fluorescence and extended-Hückel band-structure calculations are also presented for these materials.


2020 ◽  
Vol 32 (1) ◽  
pp. 297-307
Author(s):  
Łukasz Szeleszczuk ◽  
Tomasz Gubica ◽  
Sebastian Szmeja ◽  
Arkadiusz Ciesielski ◽  
Michał K. Cyrański ◽  
...  

AbstractA reliable method for molecular structure determination, excluding single-crystal X-ray diffraction (SCXRD), has been applied to six methyl glycoside tetrabenzoates. The proposed method is based on a global conformational search using molecular mechanics and subsequent DFT calculations guided by a solid-state NMR experiment. The accuracy of the applied method has been verified on three methyl glycoside benzoates for which the SCXRD analysis has been completed. It appeared that the calculated conformations of unprivileged energy could be found in the solid state. Bulky substituents (benzoates) exerted less energetically favored interactions in crystals in contrast to isolated molecules. Therefore, solid-state NMR was revealed to be an indispensable approach for choosing credible conformations from the calculated conformations.


2004 ◽  
Vol 82 (2) ◽  
pp. 285-292 ◽  
Author(s):  
Trevor W Hayton ◽  
Brian O Patrick ◽  
Peter Legzdins ◽  
W Stephen McNeil

The monomeric trinitrosyl complex, W(NO)3Cl3, can be prepared by the treatment of WCl6 in CH2Cl2 with NO gas, and its identity has been unambiguously confirmed by a single-crystal X-ray diffraction analysis. The complex crystallizes in the space group Pmn21 as a three-component twin (a = 10.4280(4) Å, b = 6.3289(2) Å, c = 5.6854(2) Å, Z = 2, R1 = 0.065, wR2 = 0.176). Its solid-state molecular structure consists of a tungsten centre bound to three chloride ligands and three linear nitrosyl ligands in a fac-octahedral stereochemistry. In addition, the structure contains a crystallographically imposed mirror plane. The two independent W—N linkages are 1.88(2) and 1.92(1) Å long, while the two corresponding N—O bond lengths are 1.13(2) and 1.16(2) Å. DFT calculations on fac-W(NO)3Cl3 at the B3LYP/LANL2DZ level of theory afford optimized intramolecular metrical parameters that match the X-ray crystallographically determined bond lengths and bond angles quite well. In addition, they provide a rationale for the nearly linear W-N-O linkages extant in the complex. Solutions of fac-W(NO)3Cl3 in CH2Cl2 lose ClNO under ambient conditions and deposit the well-known [W(NO)2Cl2]n polymer, and this conversion is fully reversible.Key words: nitrosyl, tungsten, structure, bonding.


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