An experimental and theoretical approach to the study of the properties of parabanic acid and related compounds: synthesis and crystal structure of diethylimidazolidine-2-selone-4,5-dione

2000 ◽  
Vol 78 (9) ◽  
pp. 1147-1157
Author(s):  
Massimiliano Arca ◽  
Francesco Demartin ◽  
Francesco A Devillanova ◽  
Francesco Isaia ◽  
Francesco Lelj ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Frontier Orbitals ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Related Compounds ◽  
Donor Character ◽  
Ft Raman

The syntheses of the first examples of selenoparabanic acid derivatives (dialkylimidazolidine-2-selone-4,5-dione, 3eR R = Me, Et, Bu) are presented along with the X-ray crystal structure determination of 3eEt. To gain an insight in the properties of parabanic acid derivatives on the basis of their electronic structures, we report the results of comparative hybrid-DFT calculations performed on parabanic, thioparabanic, and selenoparabanic acids (3aH, 3bH, and 3eH) and on their N,N' -dimethyl derivatives (3aMe, 3bMe, and 3eMe). Calculations show that the different nature of the frontier orbitals of 3aR compared to those of 3bR and 3eR, might account for the different reactivities of these compounds. Moreover, the weak donor character of 3bR and 3eR towards molecular di-iodine, estimated by FT-Raman measurements is in agreement with the calculated NBO-charge distribution.Key words: selenation, selenoparabanic derivatives, crystal structure, DFT calculations.

scholarly journals The preparation and characterization of SeCl3SbF6, improved syntheses of MCl3(As/Sb)F6 (M = S, Se), and the X-ray crystal structure determination of SeCl3AsF6 and a new phase of SBr3SbF6

1996 ◽  
Vol 74 (9) ◽  
pp. 1671-1681 ◽  
Author(s):  
Jack Passmore ◽  
Paul D. Boyle ◽  
Gabriele Schatte ◽  
Todd Way ◽  
T. Stanley Cameron
Keyword(s):  
Crystal Structure ◽  
Raman Spectroscopy ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Ft Raman Spectroscopy ◽  
New Phase ◽  
Ft Raman

Alternative and, in some cases, improved syntheses of the salts MX3(As/Sb)F6 (M = S, Se) and SCl3(SbCl6/AlCl4) are described. In addition, the synthesis of SeCl3SbF6 is reported. The compounds were characterized by FT–Raman spectroscopy and the X-ray crystal structures of SeCl3AsF6 (also 77Se NMR) and a new phase of SBr3SbF6 were determined. Crystals of SeCl3AsF6 and SBr3SbF6 are monoclinic, space group P21/c with [values for SBr3SbF6 in brackets] a = 7.678(1) [8.137(1)] Å, b = 9.380(3) [9.583(2)] Å, c = 11.920(3) [12.447(2)] Å, β = 98.19(2)° [97.36(1)]°, V = 849.72(3) [962.6(3)] Å3,z = 4, Dx = 2.925 [3.502] Mg m−3, R = 0.0525 [0.055], and Rw = 0.0554 [0.060] for 1151 [1472] observed reflections. Key words: MX3+ salts, FT–Raman spectroscopy, X-ray crystal structures of SeCl3AsF6, SBr3SbF6, and preparation of SeCl3SbF6.

Synthesis and Crystal Structure Determination of Cyclosporin H

2000 ◽  
Vol 65 (8) ◽  
pp. 1317-1328 ◽  
Author(s):  
Alexandr Jegorov ◽  
Ladislav Cvak ◽  
Aleš Husek ◽  
Petr Šimek ◽  
Anna Heydová ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Amino Acids ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Acid Catalyzed ◽  
Products Of Reaction ◽  
Cyclosporin H

Acid-catalyzed degradation of cyclosporin A was studied in various solvents and products of reaction were monitored by HPLC. Identification of amino acids and their chirality were determined after hydrolysis and derivatization by GC-MS. Cyclosporin H was isolated as the principal product and its structure was determined by X-ray diffraction: Cyclosporin H- diethyl ether-water (1 : 0.5 : 1) crystallizes in the monoclinic space group I2 with a = 12.338(2) Å, b = 18.963(2) Å, c = 34.074(3) Å, β = 96.47(2)°, Z = 4, and V = 7 921.4(17) Å3.

Solvothermal Synthesis and Crystal Structure Determination of Tris- (ethyleneamine-ammonium) Tetraselenoantimonat: Non-Centrosymmetry Mediated by an Extended Unusual N-H···N Hydrogen Bonded Network?

1998 ◽  
Vol 53 (10) ◽  
pp. 1144-1148 ◽  
Author(s):  
Frank Wendland ◽  
Christian Näther ◽  
Michael Schur ◽  
Wolfgang Bensch
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Solvothermal Synthesis ◽  
Amino Nitrogen ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Ammonium Hydrogen ◽  
Solvothermal Conditions

AbstractThe title compound has been synthesized under solvothermal conditions by the reaction of elemental chromium, antimony and selenium in a solution of 40% 1,2-ethanediamine (en) in methanol. The crystal structure consists of tetrahedral SbSe43- anions which are connected by monoprotonated 1,2-ethanediamine (enH+) cations via N-H--Se hydrogen bonding. The enH+ cations are joined via strong N-H -N hydrogen bonds between the ammonium hydrogen and the amino nitrogen atom forming four distinct chains, each built up of three crystallographically independent enH+ cations. Two of these chains are running parallel to [100], the other two are parallel to [010]. Based on this arrangement different centrosymmetric or non-centrosymmetric hydrogen bonding patterns are possible, but only in one chain the sequence of NH2 and NH3+ groups was determined by X-ray diffraction

Synthesis and crystal-structure determination of fibrillar methylammonium trimolybdate hydrate

2007 ◽  
Vol 22 (3) ◽  
pp. 241-245 ◽  
Author(s):  
B. Włodarczyk-Gajda ◽  
A. Rafalska-Łasocha ◽  
W. Łasocha
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Synthesis Method ◽  
Diffraction Method ◽  
Orthorhombic Space Group ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Novel Synthesis

A novel synthesis method of fibrillar trimolybdates with the use of Ag2Mo3O10∙2H2O as a precursor has been used successfully to synthesize methylammonium trimolybdate, (CH3NH3)2Mo3O10∙H2O. The crystal structure of this compound was determined by X-ray powder diffraction method and refined by the Rietveld method. The compound is orthorhombic, space group Pnma (62), with a=11.241(3), b=7.585(1), and c=15.516(4) Å. The redetermined crystal structure of the precursor and the structure of the title compound are compared and discussed.

Darstellung und Kristallstrukturanalyse von K3BiO3 und Rb3BiO3 / Synthesis and Crystal Structure Determination of K3BiO3 and Rb3BiO3

1997 ◽  
Vol 52 (9) ◽  
pp. 1031-1036 ◽  
Author(s):  
Nicola Zoche ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Single Crystal ◽  
Structure Determination ◽  
Solid State Reactions ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Binary Compounds ◽  
First Time

K3BiO3 and Rb3BiO3 have been synthesized for the first time by solid state reactions of the respective binary compounds. K3BiO3 was obtained from Bi2O3 and K2O at 550 °C, Rb3BiO3 from Bi2O3 and Rb2O at 650 °C. The compounds were structurally examined by single-crystal X -ray investigations (K3BiO3: I 4̅ 3 m, a = 1070.15(2) pm, Z = 8; Rb3BiO3: P 21 3, a = 875.48(2) pm, Z = 4). The structures reveal “isolated” BiO33- groups. While K3BiO3 is isostructural to Na3BiO3, Rb3BiO3 has the same crystal structure as Cs3BiO3.

Heteronuclear Nucleobase Complexes as Tools for the Isolation of the Minor Rotamer of the Parent Compound: Synthesis and Crystal Structure Determination of Head-Head and Head-Tail Forms of trans-[(CH3NH2)2Pt(1-MeC-N3)2]2+ (1-MeC = 1-methylcytosine)

1995 ◽  
Vol 50 (11) ◽  
pp. 1767-1776 ◽  
Author(s):  
Dagmar Holthenrich ◽  
Imre Sóvágó ◽  
Gerd Fusch ◽  
Andrea Erxleben ◽  
Edda C. Fusch ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Parent Compound ◽  
Crystal Structure Analysis ◽  
Rapid Crystallization ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Compound Synthesis ◽  
The One ◽  
Solid State Structures

The two rotamers (head-tail, 1, and head-head, 2) of the bis(1-methylcytosine)complex of trans-(CH3NH2)2Pt(II), have been crystallized as ClO4- (1, 2a) and PF6- (2b) salts and characterized by X-ray crystal structure analysis and 1H and 195Pt NMR spectroscopy. In aqueous solution, 1 is preferred over 2 by 70:30. Upon slow crystallization from H2O, 1 is obtained as the only product. Isolation of 2a and 2b has now been accomplished via formation of the heteronuclear derivative trans-[(CH3NH2)2Pt(1-MeC--N3,N4)2Hg]2+, in which the deprotonated 1-methylcytosinato ligands (1-MeC-) are oriented head-head, precipitation of Hg(II) by thiourea, and rapid crystallization of the parent compound. The solid state structures of 1 and 2b differ markedly in a number of aspects. Isolation of pure 1 and 2 permits a detailed study of the kinetics and thermodynamics of the interconversion of the two rotamers. From comparison with the behavior of 1 and 2 in H2O on the one hand and DMSO and DMF on the other a clear solvent effect on the rotamer distribution is seen which most likely relates to differences in H bonding between solvent and solute.

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