scholarly journals Computational studies of the unusual water adduct [Cp2TiMe(OH2)]+: the roles of the solvent and the counterion

2014 ◽  
Vol 43 (29) ◽  
pp. 11195-11201 ◽  
Author(s):  
Jörg Saßmannshausen
Keyword(s):  
Dft Calculations ◽  
Computational Studies ◽  
Nmr Data ◽  
Good Comparison

Detailed DFT calculations revealed that two molecules of CH2Cl2 are required to obtain a good comparison with the experimental NMR data.

Computational studies on the interactions of glycine amino acid with graphene, h-BN and h-SiC monolayers

2017 ◽  
Vol 19 (3) ◽  
pp. 1896-1908 ◽  
Author(s):  
H. Tavassoli Larijani ◽  
M. Jahanshahi ◽  
M. Darvish Ganji ◽  
M. H. Kiani
Keyword(s):  
Density Functional Theory ◽  
Silicon Carbide ◽  
Amino Acid ◽  
Boron Nitride ◽  
Dft Calculations ◽  
Density Functional ◽  
Computational Studies ◽  
Functional Theory ◽  
Zwitterionic Form ◽  
Hexagonal Sheets

In the present work, the adsorption of glycine amino acid and its zwitterionic form onto three different hexagonal sheets, namely graphene, boron-nitride (h-BN) and silicon carbide (h-SiC), has been investigated within the framework of density functional theory (DFT) calculations.

Tropylium Salt Promoted Hydroboration Reactions: Mechanistic Insights via Experimental and Computational Studies

2021 ◽  
Author(s):  
Nhan Nu Hong Ton ◽  
Binh Khanh Mai ◽  
Thanh Vinh Nguyen
Keyword(s):  
Dft Calculations ◽  
Lewis Acids ◽  
Experimental Studies ◽  
Cross Coupling ◽  
Computational Studies ◽  
Metal Free ◽  
Hydride Abstraction ◽  
Novel Method ◽  
Tropylium Salts

Abstract: Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross coupling chemistry. This type of reaction has traditionally been mediated by transition metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to efficiently promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic paradigm, which is triggered by a hydride abstraction of pinacolborane with tropylium ion. This is followed by a series of <i>in situ</i> counterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.

scholarly journals Synthetic and Computational Studies on the ABC Trioxadispiroketal Subunit of the Marine Biotoxin Azaspiracid-1

2008 ◽  
Vol 3 (11) ◽  
pp. 1934578X0800301
Author(s):  
Jialiang Li ◽  
Xiaohua Li ◽  
David R. Mootoo
Keyword(s):  
Dft Calculations ◽  
Natural Product ◽  
Anomeric Effect ◽  
Computational Studies ◽  
Structural Factors ◽  
Substitution Pattern ◽  
Major Isomer ◽  
The Stability ◽  
Insight Into

The trioxadispiroketal residue in the marine biotoxin azaspiracid-1, which exists in a configuration capable of exhibiting a double anomeric effect, is believed to be the thermodynamically most stable bis-spiroketal diastereomer. In order to get insight into how structural factors affect this equilibrium, a simplified ABC trioxadispiroketal analog of azaspiracid-1 was synthesized and subjected to equilbration and computational studies. Compound 7, which represents a double anomeric effect was obtained as the major isomer, together with diastereomers 14 and 15, in a respective ratio of 62:22:16. DFT calculations for 7, 14 and 15 qualitatively matched this observation. These results suggest that while a double anomeric effect may play a major role in the stability of the trioxadispiroketal configuration in the more complex natural product, the substitution pattern of the C ring is also a contributing factor.

Structural, spectroscopic and computational studies on the monoclinic polymorph (form I) of potassium hydrogen disilicate (KHSi2O5)

2014 ◽  
Vol 78 (3) ◽  
pp. 609-622 ◽  
Author(s):  
D. Schmidmair ◽  
V. Kahlenberg ◽  
L. Perfler ◽  
D. M. Többens
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Dft Calculations ◽  
Phase I ◽  
Spectroscopic Data ◽  
Direct Methods ◽  
Computational Studies ◽  
Structural Investigations ◽  
Micro Raman Spectroscopy ◽  
Potassium Hydrogen

AbstractHydrothermal treatment of quartz with 2 M K2CO3solutions at 623 K and 1 kbar resulted in the formation of single crystals of the monoclinic polymorph of potassium hydrogen disilicate (KHSi2O5or KSi2O4(OH)). Basic crystallographic data of this so-called phase I at room conditions are as follows: space groupC2/m,a= 14.5895(10) Å,b= 8.2992(3) Å,c= 9.6866(7) Å, β = 122.756(10)°,V= 986.36(10) Å3,Z= 8. The structure was determined by direct methods and refined to a residual of R(|F|) = 0.0224 for 892 independent observed reflections withI> 2σ(I). The compound belongs to the group of chain silicates. It is based on crankshaft-likeviererdouble-chains running parallel to [010]. The H atoms are associated with silanol groups. Hydrogen bonding between neighbouring double-chains results in the formation of ∼5 Å wide slabs. The three crystallographically independent K cations with six to eight O ligands provide linkage (1) between the chains of a single slab or (2) between adjacent slabs. Structural investigations have been supplemented by micro-Raman spectroscopy. The interpretation of the spectroscopic data including the allocation of the bands to certain vibrational species has been aided by DFT calculations.

Bicyclo[3.2.0]hepta-1,3,6-triene — UV photoelectron spectroscopic and computational studies

2005 ◽  
Vol 83 (9) ◽  
pp. 1352-1359 ◽  
Author(s):  
T Bajorek ◽  
N H Werstiuk
Keyword(s):  
Carbon Atom ◽  
Dft Calculations ◽  
Photoelectron Spectroscopy ◽  
Amine Oxide ◽  
Authentic Sample ◽  
Ionization Potentials ◽  
Spectral Subtraction ◽  
Computational Studies ◽  
Simulated Spectrum ◽  
Uv Photoelectron Spectroscopy

Pyrolysis of N,N-dimethylbicyclo[3.2.0]hepta-3,6-dien-1-amine oxide (5) at 120 °C in the source chamber of the UV photoelectron (PE) spectrometer yielded bicyclo[3.2.0]hepta-1,3,6-triene (6). The triene dimerizes to yield a mixture of two dimers in equal amounts. A PE spectrum of an authentic mixture of dimers was also recorded for the purpose of spectral subtraction. Pyrolysis of 5 also generates dimethylhydroxylamine (7), a spectrum of which was also recorded from an authentic sample. Spectral subtraction allowed the first two ionization potentials of triene 6 at 7.2 and 9.8 eV to be identified. The resultant PE spectrum was compared very favorably with a simulated spectrum obtained from DFT calculations. A QTAIM analysis and calculation of delocalization indexes showed that while homoconjugation between C4 and C6 is negligible there is a weak through-space interaction between the bridgehead carbon atom C1 and C6 of the four-membered ring.Key words: bicyclo[3.2.0]hepta-1,3,6-triene, UV photoelectron spectroscopy, DFT calculations, QTAIM, delocalization indexes.

scholarly journals Radical-initiated P,P-metathesis reactions of diphosphanes: evidence from experimental and computational studies

2021 ◽  
Author(s):  
Paul G. Pringle ◽  
Callum Branfoot ◽  
Tom Young ◽  
Duncan F Wass
Keyword(s):  
Dft Calculations ◽  
Computational Studies ◽  
Ambient Conditions ◽  
Metathesis Reactions

By combining the diphosphanes Ar2P–PAr2, where Ar = C6H5, 4-C6H4Me, 4-C6H4OMe, 3,5-C6H3(CF3)2, it has been shown that P,P-metathesis generally occurs rapidly under ambient conditions. DFT calculations have shown that the...

scholarly journals DFT Calculations and ROESY NMR Data for the Diastereochemical Characterization of Cytotoxic Tetraterpenoids from the Oleoresin of Abies balsamea

2015 ◽  
Vol 78 (12) ◽  
pp. 2896-2907 ◽  
Author(s):  
Serge Lavoie ◽  
Charles Gauthier ◽  
Vakhtang Mshvildadze ◽  
Jean Legault ◽  
Benoit Roger ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Abies Balsamea ◽  
Nmr Data
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