scholarly journals The synthesis and X-ray structures of the geometric isomers of 1-amino-1,2-cyclopentanedicarboxylic acid

1993 ◽  
Vol 71 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Kenneth Curry ◽  
Hugh McLennan ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Elevated Temperatures ◽  
Geometric Isomers ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrolysis Products ◽  
Hydrolysis Of ◽  
Cis Isomer ◽  
C Nmr

The geometric isomers of 1-amino-1,2-cyclopentanedicarboxylic acid were isolated as the hydrolysis products of 2-cyclopentanecarboxylic acid-5,5′-hydantoin. The hydantoin ester was formed from ethyl -2-oxocyclopentanecarboxylate via a Bucherer–Bergs reaction. Hydrolysis of the hydantoin at elevated temperatures gave a mixture of trans- and cis-1 -amino-1,2-cyclopentanedicarboxylic acids indicating epimerization during hydrolysis. The trans product has not been described previously and the cis not extensively characterized. X-ray crystallography reveals that both isomers are zwitterionic in the solid state and the cis isomer molecules are linked by unusually strong hydrogen bonding. Structures were confirmed by 13C NMR, X-ray crystallography, and elemental analysis. Physical data are also presented.

scholarly journals Hydrolysis of Scandium Alkyl Derivatives Supported by a Pentadentate Diborate Ligand: Interconversion of Hydroxo and Oxo Complexes

2019 ◽  
Author(s):  
Daniel W. Beh ◽  
Warren Piers ◽  
Laurent Maron ◽  
Yan Yang ◽  
Benjamin S. Gelfand ◽  
...  
Keyword(s):  
Solid State ◽  
Hydroxo Complex ◽  
Ambient Atmosphere ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrolysis Products ◽  
Alkyl Derivatives ◽  
Rapid Formation ◽  
Hydrolysis Of ◽  
Pentadentate Ligand

Uncontrolled reaction of water with scandium alkyls (compounds <b>1-R</b>) supported by a dianionic, pentadentate ligand leads to rapid formation of an oxo-bridged dimer (<b>2</b>). Solid state samples can be exposed to ambient atmosphere to generate samples enriched in the bridging dihydroxo dimer <b>3</b>, which slowly converts to the m-oxo species with elimination of water. DFT computations show that <b>3</b> is actually more thermodynamically stable than <b>2</b>, but the reactivity of <b>3</b> with the water eliminated leads to its decomposition to <b>2</b> and several hydrolysis products. Some of these products were characterized by X-ray crystallography, specifically a hexameric scandium dihydroxo cluster (<b>4</b>) in which the pentadentate ligand has partially demetallated. Attempts to synthesize hydroxo complex <b>3</b> by protonation of <b>2</b> also lead to hydrolysis products.

scholarly journals Hydrolysis of Scandium Alkyl Derivatives Supported by a Pentadentate Diborate Ligand: Interconversion of Hydroxo and Oxo Complexes

2019 ◽  
Author(s):  
Daniel W. Beh ◽  
Warren Piers ◽  
Laurent Maron ◽  
Yan Yang ◽  
Benjamin S. Gelfand ◽  
...  
Keyword(s):  
Solid State ◽  
Hydroxo Complex ◽  
Ambient Atmosphere ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrolysis Products ◽  
Alkyl Derivatives ◽  
Rapid Formation ◽  
Hydrolysis Of ◽  
Pentadentate Ligand

Uncontrolled reaction of water with scandium alkyls (compounds <b>1-R</b>) supported by a dianionic, pentadentate ligand leads to rapid formation of an oxo-bridged dimer (<b>2</b>). Solid state samples can be exposed to ambient atmosphere to generate samples enriched in the bridging dihydroxo dimer <b>3</b>, which slowly converts to the m-oxo species with elimination of water. DFT computations show that <b>3</b> is actually more thermodynamically stable than <b>2</b>, but the reactivity of <b>3</b> with the water eliminated leads to its decomposition to <b>2</b> and several hydrolysis products. Some of these products were characterized by X-ray crystallography, specifically a hexameric scandium dihydroxo cluster (<b>4</b>) in which the pentadentate ligand has partially demetallated. Attempts to synthesize hydroxo complex <b>3</b> by protonation of <b>2</b> also lead to hydrolysis products.

47,49Ti NMR in Metals, Inorganics, and Gels

2000 ◽  
Vol 55 (1-2) ◽  
pp. 291-297 ◽  
Author(s):  
T. J. Bastow
Keyword(s):  
Solid State ◽  
Titanium Oxide ◽  
Recent Progress ◽  
Titanium Isopropoxide ◽  
Metallic State ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Of ◽  
C Nmr

Some recent progress in solid state 47,49Ti NMR is described and reviewed. The metallic-state work described covers metals such as hep titanium, TiB2 , a number of intermetallics such as TiAl2 and TiAl3· The inorganic work covers the various titanium oxide based materials including the TiO2 polymorphs, anatase, rutile and brookite. The gel work covers the evolution of crystalline titania from gels formed by hydrolysis of titanium isopropoxide. Some complementary data from 17O and 13C NMR and powder X-ray diffraction is also included.

scholarly journals Simple Methylcadmium Alkoxides

2007 ◽  
Vol 62 (10) ◽  
pp. 1339-1342 ◽  
Author(s):  
Surajit Jana ◽  
Tania Pape ◽  
Norbert W. Mitzel
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Molecular Formula ◽  
Equimolar Ratio ◽  
X Ray ◽  
X Ray Crystallography ◽  
Elemental Analyses ◽  
Solid State Structures ◽  
Structural Aspects ◽  
C Nmr

The reaction of dimethylcadmium with alcohols R-OH in equimolar ratio leads to the formation of tetrameric methylcadmium alkoxides with molecular formula [(MeCd)4 (OR)4] [R = Me (1), Et (2) and iPr (3)]. These compounds have been characterised by 1H, 13C NMR and IR spectroscopy, by mass spectrometry, elemental analyses and by X-ray crystallography (for 2 and 3). The solid state structures show distorted cubane-type aggregates with Cd4O4 cores. The structural aspects and the spectroscopic characterisations of these compounds are discussed.

The relative stabilities of PhE(NH-t-Bu)2 and PhE(μ-N-t-Bu)2EPh (E = As, Sb, and Bi): X-ray structures of {Li2[PhAs(N-t-Bu)2]}2 and PhE(μ-N-t-Bu)2EPh (E = Sb, Bi)

2003 ◽  
Vol 81 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Glen G Briand ◽  
Tristram Chivers ◽  
Masood Parvez
Keyword(s):  
Solid State ◽  
Nmr Spectra ◽  
Phenyl Group ◽  
Synthetic Approach ◽  
Relative Stabilities ◽  
X Ray ◽  
X Ray Crystallography ◽  
In Trans ◽  
C Nmr

The reaction of PhECl2 with 2 equiv of LiHN-t-Bu has been studied for the series E = As, Sb, and Bi to determine the effect of the phenyl group on subsequent amine condensation processes. For PhAsCl2, the metathesis product PhAs(NH-t-Bu)2 4 was obtained as a colourless oil. Similar reactions involving PhECl2, where E = Sb or Bi, yielded the cyclodipnict(III)azanes PhE(μ-N-t-Bu)2EPh 5 (E = Sb) and 6 (E = Bi), respectively. Treatment of 4 with 2 equiv of n-BuLi produced the dilithium salt Li2[PhAs(N-t-Bu)2] 7a. Products 4, 5, 6, and 7a were characterized by 1H, 7Li (7a), and 13C NMR spectra, while 5, 6, and 7a were also structurally characterized by X-ray crystallography. Compound 7a is dimeric in the solid state via intermolecular Li···N and η6-Li···Ph interactions. The cyclodipnict(III)azanes 5 and 6 have similar structures, with the exocyclic phenyl groups in trans positions relative to the E2N2 ring. This synthetic approach provides a new route to the four-membered rings RE(μ-N-t-Bu)2ER (E = Sb, Bi) and the first example of a bis(organyl)cyclodibism(III)azane.Key words: arsenic, antimony, bismuth, amides, imides.

scholarly journals Solid-state tautomeric structure and invariom refinement of a novel and potent HIV integrase inhibitor

2013 ◽  
Vol 69 (3) ◽  
pp. 285-288 ◽  
Author(s):  
John Bacsa ◽  
Maurice Okello ◽  
Pankaj Singh ◽  
Vasu Nair
Keyword(s):  
Solid State ◽  
Integrase Inhibitor ◽  
Correlation Spectroscopy ◽  
Hiv Integrase ◽  
Acta Cryst ◽  
X Ray ◽  
X Ray Crystallography ◽  
Molecular Charge ◽  
Intramolecular Hydrogen ◽  
C Nmr

The conformation and tautomeric structure of (Z)-4-[5-(2,6-difluorobenzyl)-1-(2-fluorobenzyl)-2-oxo-1,2-dihydropyridin-3-yl]-4-hydroxy-2-oxo-N-(2-oxopyrrolidin-1-yl)but-3-enamide, C27H22F3N3O5, in the solid state has been resolved by single-crystal X-ray crystallography. The electron distribution in the molecule was evaluated by refinements with invarioms, aspherical scattering factors by the method of Dittrichet al.[Acta Cryst.(2005), A61, 314–320] that are based on the Hansen–Coppens multipole model [Hansen & Coppens (1978).Acta Cryst.A34, 909–921]. The β-diketo portion of the molecule exists in the enol form. The enol –OH hydrogen forms a strong asymmetric hydrogen bond with the carbonyl O atom on the β-C atom of the chain. Weak intramolecular hydrogen bonds exist between the weakly acidic α-CH hydrogen of the keto–enol group and the pyridinone carbonyl O atom, and also between the hydrazine N—H group and the carbonyl group in the β-position from the hydrazine N—H group. The electrostatic properties of the molecule were derived from the molecular charge density. The molecule is in a lengthened conformation and the rings of the two benzyl groups are nearly orthogonal. Results from a high-field1H and13C NMR correlation spectroscopy study confirm that the same tautomer exists in solution as in the solid state.

Two-bond 13C–13C spin-coupling constants in saccharides: dependencies on exocyclic hydroxyl group conformation

2021 ◽  
Author(s):  
Jieye Lin ◽  
Reagan J. Meredith ◽  
Allen G. Oliver ◽  
Ian Carmichael ◽  
Anthony S. Serianni
Keyword(s):  
Solid State ◽  
Torsion Angle ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Spin Coupling Constants ◽  
C Nmr

13C-Labeled mono- and disaccharides were studied by X-ray crystallography and solid-state 13C NMR to determine the dependence of 2JC1,C3 in aldopyranosyl rings on the C1–C2–O2–H torsion angle, θ2, involving C2 of the C1–C2–C3 coupling pathway.

3-Aminotropane-3-carboxylic acids. Preparation and properties

1980 ◽  
Vol 58 (21) ◽  
pp. 2295-2299 ◽  
Author(s):  
Gregorio G. Trigo ◽  
Carmen Avendaño ◽  
Emilia Santos ◽  
Halvor N. Christensen ◽  
Mary E. Handlogten
Keyword(s):  
Amino Acids ◽  
Inhibitory Action ◽  
Equatorial Position ◽  
Amino Group ◽  
Biological Transport ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrolysis Rates ◽  
Hydrolysis Of ◽  
C Nmr

The two isomers of 3-aminotropane-3-carboxylic acid have been prepared by hydrolysis of the two α- and β-tropane-3-spiro-5′-hydantoins whose configurations were determined by X-ray crystallography and 13C nmr. The [Formula: see text] values of these amino acids and the hydrolysis rates of their N-formyl derivatives have been determined to study the influence of the amino group in an axial or equatorial position. The biological transport – inhibitory action of the two tropane amino acids has also been compared.

Structural diversity in thallium chemistry: structures of four chlorothallate(III) salts including a novel compound containing three geometrically different anions

1996 ◽  
Vol 74 (8) ◽  
pp. 1490-1502 ◽  
Author(s):  
Margaret Ann James ◽  
Jason A.C. Clyburne ◽  
Anthony Linden ◽  
Bruce D. James ◽  
John Liesegang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Structural Diversity ◽  
State Structure ◽  
X Ray ◽  
Coordination Numbers ◽  
X Ray Crystallography ◽  
Hydrogen Bonding Networks ◽  
Alkyl Ammonium ◽  
High Coordination

Four new thallium-containing salts with different alkyl ammonium cations have been prepared and characterized by X-ray crystallography: 1: bis(p-toluidinium) pentachlorothallate(III), [CH3C6H4NH3]2 [TlCl5], M = 597.9, monoclinic, P21/c, a = 7.515(2), b = 21.376(6), c = 12.769(2) Å, β = 92.13(2)°, V = 2050(1) Å3, Z = 4, Dcalc = 1.937 Mg m−3, µ = 8.512 mm−1, T = 293(1) K, R = 0.046; 2: 1,5-pentanediammonium pentachlorothallate(III), [NH3(CH2)5NH3] [TlCl5], M = 485.83, orthorhombic, P212121, a = 13.226(2), b = 13.595(2), c = 7.628(2) Å, V = 1371.6(3) Å3, Z = 4, Dcalc = 2.352 Mg m−3, µ = 12.84 mm−1, T = 173(1) K, R = 0.025; 3: pentakis(2-adamantaneammoniumn) bistetrachlorothallate(III) hexachlorothallate(III), [C10H18N]5 [TlCl4]2[TlCl6], M = 1870.75, monoclinic, P21a = 16.466(5), b = 25.985(2), c = 7.724(3) Å, β = 90.14(3)°, V = 3305(2) Å3, Z = 2, Dcalc = 1.880 Mg m−3, µ = 7.978 mm−1, T = 173(1) K, R = 0.056; 4: bis(piperazinium) decachlorodithallate(III) trihydrate, [NH2C4H8NH2]2 [Tl2Cl10]•3H2O, M = 993.62, monoclinic, C2/c, a = 14.154(3), b = 15.445(3), c = 13.228(3) Å, β = 114.44(1)°, V = 2632.7(9) Å3, Z = 4, Dcalc = 2.506 Mg m−3, µ = 13.39 mm−1, T = 173(1) K, R = 0.026. For most of the salts examined, formation of [TlCl5]2− is possible; however, no isolated [TlCl5]2− anions were observed. In most cases, high coordination numbers at thallium were observed (CN = 6), and these can be achieved via formation of anionic chains or through dimerization, giving [Tl2Cl10]4−. Of particular interest is the solid state structure of salt 3 in which there are three geometrically different chlorothallate ions. Extensive hydrogen-bonding networks are observed in each structure. Key words: thallium, thallium(III) chlorides, chlorothallate, hydrogen bonding, alkyl ammonium cations.

Synthesis, characterization, and reactivity of the first hafnium alkyl complex stabilized by amidate ligands

2005 ◽  
Vol 83 (6-7) ◽  
pp. 1037-1042 ◽  
Author(s):  
Robert K Thomson ◽  
Brian O Patrick ◽  
Laurel L Schafer
Keyword(s):  
Coordination Chemistry ◽  
Solid State ◽  
Key Words ◽  
Low Temperatures ◽  
Variable Temperature ◽  
X Ray ◽  
X Ray Crystallography ◽  
Exchange Processes ◽  
Hydrolysis Of

A photo and thermally stable bis(amidate)–dibenzyl complex of Hf ([DMP(NO)Ph]2Hf(CH2Ph)2(THF) (2a) was formed as a monosolvated THF adduct in near quantitative yield from Hf(CH2Ph)4 and N-2,6-dimethylphenyl(phenyl)amide (1). Isomerization between the THF-bound product and the THF-free product can be observed visually by the conversion from a red-orange product at low temperatures to a pale yellow product at high temperatures. Solid-state crystallographic characterization of the orange product confirmed its constitution as a monosolvated species. Kinetic parameters for the exchange of the THF moiety were determined from variable-temperature NMR experiments. The product of the hydrolysis of the Hf dibenzyl species by water was characterized by X-ray crystallography, and was found to be a rare tetrametallic Hf oxo cluster species (3).Key words: hafnium, protonolysis, amidate, coordination chemistry, organometallic chemistry, exchange processes.

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