1,4,5,8-Tetraazafulvalene – Darstellung schwefelhaltiger Derivate und Zuordnung des Chromophors / 1,4,5,8-Tetraazafulvalenes – Synthesis of Sulfur-Containing Derivatives and Classification of the Chromophor

2004 ◽  
Vol 59 (4) ◽  
pp. 406-413 ◽  
Author(s):  
Christiane Kühn ◽  
R. Beckert ◽  
U.-W. Grummt ◽  
C. Käpplinger ◽  
E. Birckner
Keyword(s):  
Lipoic Acid ◽  
Density Functional ◽  
Tautomeric Form ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Different Types ◽  
Palladium Catalyzed ◽  
Catalyzed Reactions ◽  
Sulfur Containing

Abstract In order to obtain sulfur-containing tetraazafulvalenes the derivatives 1 - 3 were cross-coupled with different types of acetylenes via palladium-catalyzed reactions. Starting from the tetrabromoaryl derivative 3a, four bromine atoms could be replaced by 2-ethynylthiophene. Under analogous conditions, the methylsulfanyl esters 7 -11 could be obtained by employing 4-ethynylbenzoic acid 4-(methylsulfanyl)butylester 6. Lipoic acid could be integrated into tetraazafulvalenes successfully in a two step reaction. First, the Sonogashira coupling method yielded the compound 12 possessing two (4-anilino)ethynyl residues which were then condensed with lipoic acid to give derivative 13. Whereas the NMR data suggest the predominance of prototropic form A, UV/vis spectra of the deeply colored tetraazafulvalenes are in favor with structure B rather than with structure A. DFT calculations at the B3LYP/6-31G(d) level showed that tautomeric form B is about 60 kJ/mol more stable than A. In addition, time-dependent density functional theory calculations support the substructure of two crossed diazaheptamethinemerocyanines.

scholarly journals CO2 activation through silylimido and silylamido zirconium hydrides supported on N-donor chelating SBA15 surface ligands

2016 ◽  
Vol 52 (12) ◽  
pp. 2577-2580 ◽  
Author(s):  
Farhan Ahmad Pasha ◽  
Anissa Bendjeriou-Sedjerari ◽  
Edy Abou-Hamad ◽  
Kuo-Wei Huang ◽  
Jean-Marie Basset
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Solid State Nmr ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Co2 Activation ◽  
Functional Theory ◽  
Surface Ligands ◽  
Different Types ◽  
Zirconium Hydrides

Density functional theory calculations and 2D 1H–13C HETCOR solid state NMR spectroscopy prove that CO2 can be used to probe, by its own reactivity, different types of N-donor surface ligands on SBA15-supported ZrIV hydrides: [(Si–O–)(Si–N)[Zr]H] and [(Si–NH–)(Si–X–)[Zr]H2] (XO or NH).

Understanding the role of frustrated Lewis pairs as ligands in transition metal-catalyzed reactions

2020 ◽  
Vol 49 (10) ◽  
pp. 3129-3137 ◽  
Author(s):  
Jorge Juan Cabrera-Trujillo ◽  
Israel Fernández
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
State Of The Art ◽  
Density Functional Theory Calculations ◽  
Frustrated Lewis Pairs ◽  
Functional Theory ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Lewis Pairs

The role of frustrated Lewis pairs (FLPs) as ligands in gold(i) catalyzed-reactions has been computationally investigated by using state-of-the-art density functional theory calculations.

Understanding the Reaction Mechanism of Gold-Catalyzed Reactions of 2,1-Benzisoxazoles with Propiolates and Ynamides

2021 ◽  
Author(s):  
Zhaoyuan Yu ◽  
Shu-Juan Lin ◽  
Zhenyang Lin
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Catalyzed Reactions

The detailed reaction mechanisms of gold-catalyzed reactions of 2,1-benzisoxazoles with propiolates and ynamides have been investigated with the aid of density functional theory calculations. Our investigation focused on the different...

scholarly journals Graphene Support Effects on Palladium Catalyzed Reactions

2019 ◽  
Vol 20 (2) ◽  
Author(s):  
Kathleen Dreyer
Keyword(s):  
Binding Energy ◽  
Palladium Catalysts ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Binding Energies ◽  
Catalytic Reactions ◽  
Graphene Interface ◽  
Palladium Catalyzed ◽  
Pd Clusters ◽  
Catalyzed Reactions

Palladium catalysts are often anchored to a support, such as graphitic carbon, to increase their overall surface area and facilitate catalytic reactions. There is a potential for interaction between the support and the catalyst, which can affect such reactions. At a certain palladium size threshold, it is hypothesized that the effects of the support on reactions on Pd are negligible. To determine this threshold, the Pd catalyst size and shape were varied (size was varied in the number of layers and number of Pd atoms, while shape ranged from hemispherical to spherical). The Pd clusters ranged from 2-5 layers and 38-293 atoms. Also, the graphene support was functionalized to different extents to test its effect on catalytic reactions on Pd. Initially, adsorption reactions of H*, O*, C*, OH*, and CH* onto supported Pd were tested to determine the effects of catalyst shape and size on the binding energy of such adsorbates. Periodic density functional theory calculations were used to determine these binding energies on bare Pd, Pd on a pure graphene support, and Pd on graphene functionalized with oxygen and hydroxide. These tests revealed that smaller Pd particles (about 100 atoms or fewer) are influenced by the support, showing large shifts in adsorbate binding energy from the pure graphene to the functionalized graphene. This shift in binding energy indicates that there are major changes in the catalytic behavior of sites upon which the adsorption reaction was tested, meaning that sites near the Pd-graphene interface might be affected by the support.

Phenanthro[9,10-a]corannulene by one-step annulative π-extension of corannulene

2017 ◽  
Vol 95 (3) ◽  
pp. 329-333 ◽  
Author(s):  
Kenta Kato ◽  
Yasutomo Segawa ◽  
Kenichiro Itami
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Photophysical Properties ◽  
Coupling Reaction ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
X Ray ◽  
Palladium Catalyzed ◽  
One Step ◽  
The One

The one-step π-extension of corannulene was achieved using a palladium-catalyzed C–H coupling reaction. The X-ray crystal structure and photophysical properties of the thus formed phenanthro[9,10-a]corannulene (1) were investigated, and the structural properties of 1 were examined by density functional theory calculations. In contrast to dibenzo[g,p]chrysene, the most stable structure of 1 was a butterfly-shaped structure, resulting from the bowl-shaped distortion of the corannulene moiety.

scholarly journals A comparative test of different density functionals for calculations of NH3-SCR over Cu-Chabazite

2019 ◽  
Vol 21 (21) ◽  
pp. 10923-10930 ◽  
Author(s):  
Lin Chen ◽  
Ton V. W. Janssens ◽  
Henrik Grönbeck
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Comparative Test ◽  
Density Functionals ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Nh3 Scr ◽  
Different Types

A general challenge in density functional theory calculations is to simultaneously account for different types of bonds. Here, different exchange–correlation functionals are explored for O2 dissociation over Cu(NH3)2+ complexes in Cu-Chabazite.

scholarly journals Sequentially Catalyzed Three-Component Masuda–Suzuki–Sonogashira Synthesis of Fluorescent 2-Alkynyl-4-(7-azaindol-3-yl)pyrimidines: Three Palladium-Catalyzed Processes in a One-Pot Fashion

Synlett ◽  
2020 ◽  
Author(s):  
Thomas J. J. Müller ◽  
Daniel Drießen ◽  
Lukas Biesen
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Time Dependent ◽  
Absorption Bands ◽  
One Pot ◽  
Functional Theory ◽  
Efficient Access ◽  
Three Component Reaction ◽  
Palladium Catalyzed ◽  
Wavelength Absorption

The Masuda–Suzuki–Sonogashira sequence efficiently unites, in a one-pot fashion, a borylation, an arylation, and an alkynylation in the sense of a sequentially Pd-catalyzed three-component reaction to give fluorescent 2-alkynyl-4-(7-azaindol-3-yl) pyrimidines in yields of 24–83% (14 examples). Time-dependent density-functional theory calculations supported the electronic structure of the longest wavelength absorption bands, revealing that this novel consecutive three-component synthesis opens an efficient access to alkynyl meriolins, a novel class of potential inducers of apoptosis.

Polymorphism in the nitrate salt of the [Mn(acetylacetonate)2(H2O)2]+ ion

2010 ◽  
Vol 66 (3) ◽  
pp. 373-379 ◽  
Author(s):  
A. R. Biju ◽  
M. V. Rajasekharan
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Lattice Energy ◽  
Chair Conformation ◽  
Water Molecules ◽  
Complex Ions ◽  
Functional Theory ◽  
One Dimensional ◽  
Dimensional Network ◽  
Different Types

The crystallization of [Mn(acac)2(H2O)2]+ from solutions containing excess nitrate leads to the formation of four polymorphs. All polymorphs contain two different types of complex ions, one containing essentially coplanar acac ligands and the other in which the two acac ligands together assume a chair conformation. Molecular modelling using DFT (density-functional theory) calculations shows that the coplanar conformation is the electronically stable one. The hydrogen bonding between the trans-water molecules and the nitrate ion produces a one-dimensional chain of 12-membered rings, which are further organized into a two-dimensional network via a lattice water molecule. Lattice-energy calculations have been carried out to compare the stabilities of the four polymorphs.

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