scholarly journals Ab initio study of mechanism of forming a Si-heterocyclic spiro-Sn-heterocyclic ring compound by cycloaddition reaction of Me2Si=Sn: and ethene

2019 ◽  
Vol 44 (2) ◽  
pp. 114-121
Author(s):  
Xiaojun Tan ◽  
Xiuhui Lu
Keyword(s):  
Singlet State ◽  
Cycloaddition Reaction ◽  
Chemical Species ◽  
Heterocyclic Ring ◽  
Basis Set ◽  
Cycloaddition Reactions ◽  
Unoccupied Orbital ◽  
Donor Acceptor ◽  
Moller Plesset ◽  
First Time

X2Si=Sn: (X = H, Me, F, Cl, Br, Ph, Ar, etc.) are a new chemical species. The cycloaddition reactions of X2Si=Sn: are a new field of stannylene chemistry. The mechanism of the cycloaddition reaction between singlet state Me2Si=Sn: and ethene has been investigated for the first time here using second-order Møller-Plesset perturbation theory together with the 6-311++G** basis set for C, H and Si atoms and the LanL2dz basis set for Sn atoms. From the potential energy profile, it could be predicted that the reaction has one dominant reaction channel. The reaction process presented is that the 5p unoccupied orbital of Sn in Me2Si=Sn: and the π orbital of ethene form a π → p donor–acceptor bond resulting in the formation of an intermediate. The instability of this intermediate makes it isomerize to a four-membered Si-heterocyclic ring stannylene. Because the 5p unoccupied orbital of the Sn atom in the four-membered Si-heterocyclic ring stannylene and the π orbital of ethene form a π → p donor–acceptor bond, the four-membered Si-heterocyclic ring stannylene further combines with ethene to form another intermediate. Because the Sn atom in this intermediate assumes sp3 hybridization after the transition state, the intermediate isomerizes to a Si-heterocyclic spiro-Sn-heterocyclic ring compound. This result indicates the modes of cycloaddition reactions between X2Si=Sn: and symmetric π-bonded compounds, i.e. this study opens up a new field for stannylene chemistry.

scholarly journals Ab initio study of the mechanism of formation of a spiro-Sn-heterocyclic ring compound by the cycloaddition reaction of H2C=Sn: and ethylene

2019 ◽  
Vol 84 (3) ◽  
pp. 293-301
Author(s):  
Xiaojun Tan ◽  
Xiuhui Lu
Keyword(s):  
Cycloaddition Reaction ◽  
Heterocyclic Ring ◽  
Membered Ring ◽  
Ab Initio Study ◽  
Mechanism Of Formation ◽  
Potential Energy Profile ◽  
Unoccupied Orbital ◽  
Reaction Rule ◽  
Donor Acceptor ◽  
First Time

X2C=Sn: (X = H, Me, F, Cl, Br, Ph, Ar?) are new species of chemistry. The cycloaddition reactions of X2C=Sn: is a new study field of stannylene chemistry. The mechanism of cycloaddition reaction of singlet H2C=Sn: with ethylene is studied for the first time using the MP2/GENECP (C, H in 6-311++G**; Sn in LanL2dz) method in this paper. From the potential energy profile, it could be predicted that the reaction has one dominant reaction channel. The reaction rule presented is that the 5p unoccupied orbital of tin in H2C=Sn: sidewise overlaps with the bonding ? orbital of ethylene resulting in the formation of an intermediate. The instability of the intermediate makes it isomerise to a four-membered ring stannylene. As the 5p unoccupied orbital of the Sn atom in the four-membered ring stannylene and the ? orbital of ethylene form a ??p donor?acceptor bond, the four-membered ring stannylene further combines with ethylene to form another intermediate, and this intermediate further isomerises to a spiro-Sn-heterocyclic ring compound. The Sn in the spiro-Sn-heterocyclic ring compound is combined with adjacent atoms by sp3 hybridization. The results of this study reveal the mechanism of cycloaddition reaction of X2C=Sn: with symmetric ?-bond compounds.

scholarly journals Theoretical study of the formation of a spiro-Sn-heterocyclic compound by cycloaddition reaction of Me2C=Sn: and ethene

2018 ◽  
Vol 24 (6) ◽  
pp. 311-315 ◽  
Author(s):  
Xiaojun Tan ◽  
Xiuhui Lu
Keyword(s):  
New Species ◽  
Intermediate Product ◽  
Theoretical Study ◽  
Cycloaddition Reaction ◽  
Heterocyclic Ring ◽  
Membered Ring ◽  
Energy Profile ◽  
Potential Energy Profile ◽  
Donor Acceptor ◽  
First Time

AbstractX2C=Sn: compounds (X=H, Me, F, Cl, Br, Ph, Ar) are new species. The cycloaddition reactions of X2C=Sn: are also a new study field of unsaturated stannylene chemistry. The mechanism of cycloaddition reaction between singlet Me2C=Sn: and ethene was investigated for the first time using the MP2/GENECP (C, H in 6-311++G**; Sn in LanL2dz) method. From the potential energy profile, it was predicted that the reaction has one dominant channel in which the 5p unoccupied orbital of Sn: in Me2C=Sn: and theπorbital of ethene form aπ→pdonor-acceptor bond in an intermediate product. Instability of the intermediate product results in its isomerization to a four-membered ring of stannylene. The four-membered stannylene further combines with ethene to form another intermediate product that further isomerizes to a spiro-Sn-heterocyclic ring compound.

Homolytic bond-dissociation enthalpies of tin bonds and tin–ligand bond strengths — A computational study

2009 ◽  
Vol 87 (7) ◽  
pp. 974-983 ◽  
Author(s):  
Sarah R. Whittleton ◽  
Russell J. Boyd ◽  
T. Bruce Grindley
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Basis Set ◽  
Functional Theory ◽  
Bond Dissociation ◽  
Donor Acceptor ◽  
Bond Strengths ◽  
Moller Plesset ◽  
Effective Core Potentials ◽  
Ligand Bond

Density functional theory and second-order Møller–Plesset perturbation theory with effective core potentials have been used to calculate homolytic bond-dissociation enthalpies, D(Sn–X), of organotin compounds, and their performance has been assessed by comparison with available experimental bond enthalpies. The SDB-aug-cc-pVTZ basis set with its effective core potential was used to calculate the D(Sn–X) of a series of trimethyltin(IV) species, Me3Sn–X, where X = H, CH3, CH2CH3, NH2, OH, Cl, and F. This is the most comprehensive report to date of homolytic Sn–X bond-dissociation enthalpies (BDEs). Effective core potentials are then used to calculate thermodynamic parameters including donor–acceptor bond enthalpies, [Formula: see text], for a series of tin-ligand complexes, L2SnX4 (X = Br or Cl, L = py, dmf, or dmtf), which are compared with previous experimental and nonrelativistic computational results. Based on computational efficiency and accuracy, it is concluded that effective core potentials are appropriate computational methods to examine bonding in organotin systems.

scholarly journals Synergistic Palladium-Phosphoric Acid Catalysis in (3 + 2) Cycloaddition Reactions between Vinylcyclopropanes and Imines

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 150 ◽  
Author(s):  
Vasco Corti ◽  
Enrico Marcantonio ◽  
Martina Mamone ◽  
Alessandro Giungi ◽  
Mariafrancesca Fochi ◽  
...  
Keyword(s):  
Phosphoric Acid ◽  
Palladium Catalyst ◽  
Palladium Catalysts ◽  
Acid Catalysis ◽  
Cycloaddition Reaction ◽  
Cross Coupling ◽  
Cycloaddition Reactions ◽  
Synergistic Catalysis ◽  
Palladium Catalyzed ◽  
First Time

The palladium-catalyzed (3 + 2) cycloaddition reaction between vinylcyclopropanes (VCPs) bearing geminal EWG’s and imines represents a straightforward and flexible entry to polysubstituted pyrrolidine derivatives. In this paper, we demonstrate that using a synergistic catalysis approach, based on the combination of phosphoric acid and palladium catalysts, it is possible to engage for the first time N-aryl and N-benzyl imines in this cycloaddition reaction. A range of polysubstituted pyrrolidines is obtained with moderate to good yields and diastereoselectivities, using a simple palladium species (Pd(PPh3)4) and an archetypical phosphoric acid as catalyst combination. A two-step scheme which exploits the same palladium catalyst for two consecutive and mechanistically distinct reactions (the cycloaddition and a Suzuki–Miyaura cross-coupling) is also presented. This synergistic catalysis approach is well posited for the development of the enantioselective version of this reaction. A screening of common BINOL-derived chiral phosphoric acids as catalyst component identified a species giving the product with moderate, yet promising, enantioselectivity (64% ee).

scholarly journals Novel synthesis of highly functionalized cyclopentane derivatives via [3 + 2] cycloaddition reactions of donor–acceptor cyclopropanes and (E)-3-aryl-2-cyanoacrylates

2019 ◽  
Vol 43 (1-2) ◽  
pp. 43-49 ◽  
Author(s):  
Chenlu Dai ◽  
Mingshuang Li ◽  
Mengjun Chen ◽  
Naili Luo ◽  
Cunde Wang
Keyword(s):  
Cycloaddition Reaction ◽  
Cycloaddition Reactions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Novel Synthesis ◽  
Donor Acceptor

An efficient [3 + 2] cycloaddition reaction of cyanocyclopropanecarbonates and ( E)-3-aryl-2-cyanoacrylates mediated by 1,8-diazabicyclo[5.4.0]undec-7-ene for the synthesis of highly functionalized cyclopentane derivatives in moderate to good yields (79%−87%) was developed. The structures of two typical products were confirmed by X-ray crystallography.

The preparation of 1,2,3,5-dithiadiazolium chlorides from the reaction of nitrile sulphides with thiazyl chloride

1994 ◽  
Vol 72 (4) ◽  
pp. 1143-1153 ◽  
Author(s):  
John N. Bridson ◽  
Steven B. Copp ◽  
Melbourne J. Schriver ◽  
Shuguang Zhu ◽  
Michael J. Zaworotko
Keyword(s):  
Crystal Structure ◽  
Cycloaddition Reaction ◽  
Heterocyclic Ring ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Space Group ◽  
X Ray ◽  
Alkyl Derivatives ◽  
First Time

Adamantyl-1,3,4-oxathiazol-2-one has been prepared for the first time and from it 1-adamantyl nitrile sulphide has been generated. Characterisation data are presented, including the X-Ray crystal structure of the oxathiazolone. (Crystal data for C12H15NO2S: monoclinic, space group P21/c, a = 11.334(2) Å,b = 7.344(1) Å, c = 14.373(2) Å,β = 107.74(1)°, V = 1139.5(3) Å3, Z = 4, R = 0.042). The planar heterocyclic ring is similar to structures observed in the gas phase for other oxathiazolone derivatives. The nitrile sulphide was reacted with dimethyl-acetylene dicarboxylate in situ to give an isothiazole derivative. The X-Ray crystal structure of 3-adamantyl-4,5-bis(methoxycarbonyl)-isothiazole has been obtained. (Crystal data for C17H21NO4S: monoclinic, space group P21/n, a = 7.305(4) Å, b = 7.339(4) Å, c = 31.552(4) Å, β = 92.75(3)°, V = 1690(1) Å3, Z = 4, R = 0.079). A general cycloaddition reaction was discovered between the nitrile sulphides and thiazyl chloride to give 1,2,3,5-dithiadiazolium chlorides. The structure of the new 4-adamantyl-1,2,3,5-dithiadiazolium chloride was confirmed by reduction to the 4-adamantyl-1,2,3,5-dithiadiazolyl for which the X-Ray crystal structure has been determined. (Crystal data for C11H15N2S2: monoclinic, space group C2, a = 10.284(4) Å, b = 8.651(2) Å, c = 13.669(2) Å, β = 112.83(1)°, V = 1120.9(4) Å3, Z = 4, R = 0.042). The radical adopts a twisted dimer structure in the solid state which is similar to the structures observed for other alkyl derivatives.

scholarly journals Ab initio study of the mechanism of forming a spiro-Si-heterocyclic ring compound involving Ge from H2Ge=Si: and acetaldehyde

2016 ◽  
Vol 81 (6) ◽  
pp. 633-643
Author(s):  
Xiuhui Lu ◽  
Jingjing Ming
Keyword(s):  
New Species ◽  
Reaction Pathway ◽  
Cycloaddition Reaction ◽  
Heterocyclic Ring ◽  
Energy Profile ◽  
Ab Initio Study ◽  
Potential Energy Profile ◽  
Reaction Rule ◽  
Donor Acceptor ◽  
A New Species

The H2Ge=Si: and its derivatives(X2Ge=Si:, X = H, Me, F, Cl, Br, Ph, Ar??) is a new species. Its cycloaddition reactions is a new area for the study of silylene chemistry. The mechanism of the cycloaddition reaction between singlet H2Ge=Si: and acetaldehyde has been investigated with MP2/6-311++G** method, From the potential energy profile, it can be predicted that the reaction has a dominant reaction pathway. The reaction rule presented is that the two reactants firstly form a four-membered Ge-heterocyclic ring silylene through the [2+2] cycloaddition reaction. Because of the 3p unoccupied orbital of Si: atom in the four-membered Ge-heterocyclic ring silylene and the ? orbital of acetaldehyde form a ??p donor-acceptor bond, the four-membered Ge-heterocyclic ring silylene further combines with acetaldehyde to form an intermediate. Then the intermediate isomerizes to a spiro-Si-heterocyclic ring compound involving Ge via a transition state.

scholarly journals The SN2 reaction and its relationship with the Walden inversion, the Finkelstein and Menshutkin reactions together with theoretical calculations for the Finkelstein reaction

2021 ◽  
Author(s):  
Ibon Alkorta ◽  
José Elguero
Keyword(s):  
Linear Models ◽  
Theoretical Calculations ◽  
Computational Method ◽  
Basis Set ◽  
Free Energies ◽  
Nitrogen And Phosphorus ◽  
Atom Pairs ◽  
Leaving Groups ◽  
First Time ◽  
Nitrogen Phosphorus

AbstractThis communication gives an overview of the relationships between four reactions that although related were not always perceived as such: SN2, Walden, Finkelstein, and Menshutkin. Binary interactions (SN2 & Walden, SN2 & Menshutkin, SN2 & Finkelstein, Walden & Menshutkin, Walden & Finkelstein, Menshutkin & Finkelstein) were reported. Carbon, silicon, nitrogen, and phosphorus as central atoms and fluorides, chlorides, bromides, and iodides as lateral atoms were considered. Theoretical calculations provide Gibbs free energies that were analyzed with linear models to obtain the halide contributions. The M06-2x DFT computational method and the 6-311++G(d,p) basis set have been used for all atoms except for iodine where the effective core potential def2-TZVP basis set was used. Concerning the central atom pairs, carbon/silicon vs. nitrogen/phosphorus, we reported here for the first time that the effect of valence expansion was known for Si but not for P. Concerning the lateral halogen atoms, some empirical models including the interaction between F and I as entering and leaving groups explain the Gibbs free energies.

scholarly journals Molecular Hydrogen as a Lewis Base in Hydrogen Bonds and Other Interactions

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3294 ◽  
Author(s):  
Sławomir J. Grabowski
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Hydrogen ◽  
Spectroscopic Properties ◽  
Lewis Base ◽  
Basis Set ◽  
Orbital Method ◽  
Topological Parameters ◽  
Theoretical Approaches ◽  
Strength Of Interaction ◽  
Moller Plesset

The second-order Møller–Plesset perturbation theory calculations with the aug-cc-pVTZ basis set were performed for complexes of molecular hydrogen. These complexes are connected by various types of interactions, the hydrogen bonds and halogen bonds are most often represented in the sample of species analysed; most interactions can be classified as σ-hole and π-hole bonds. Different theoretical approaches were applied to describe these interactions: Quantum Theory of ‘Atoms in Molecules’, Natural Bond Orbital method, or the decomposition of the energy of interaction. The energetic, geometrical, and topological parameters are analysed and spectroscopic properties are discussed. The stretching frequency of the H-H bond of molecular hydrogen involved in intermolecular interactions is considered as a parameter expressing the strength of interaction.

scholarly journals Pyran-Squaraine as Photosensitizers for Dye-Sensitized Solar Cells: DFT/TDDFT Study of the Electronic Structures and Absorption Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Reda M. El-Shishtawy ◽  
Shaaban A. Elroby ◽  
Abdullah M. Asiri ◽  
Rifaat H. Hilal
Keyword(s):  
Solar Cells ◽  
Dye Sensitized Solar Cells ◽  
Nbo Analysis ◽  
Basis Set ◽  
Absorption Properties ◽  
Charge Delocalization ◽  
Squaraine Dyes ◽  
Dye Sensitized ◽  
Donor Acceptor ◽  
Sensitized Solar Cells

In an effort to provide, assess, and evaluate a theoretical approach which enables designing efficient donor-acceptor dye systems, the electronic structure and optical properties of pyran-squaraine as donor-acceptor dyes used in dye-sensitized solar cells were investigated. Ground state properties have been computed at the B3LYP/6-31+G**level of theory. The long-range corrected density functionals CAM-B3LYP, PBEPBE, PBE1PBE (PBE0), and TPSSH with 6-311++G**were employed to examine absorption properties of the studied dyes. In an extensive comparison between experimental results and ab initio benchmark calculations, the TPSSH functional with 6-311++G**basis set was found to be the most appropriate in describing the electronic properties for the studied pyran and squaraine dyes. Natural transition orbitals (NTO), frontier molecular orbitals (FMO), LUMO, HOMO, and energy gaps, of these dyes, have been analyzed to show their effect on the process of electron injection and dye regeneration. Interaction between HOMO and LUMO of pyran and squaraine dyes was investigated to understand the recombination process and charge-transfer process involving these dyes. Additionally, we performed natural bond orbital (NBO) analysis to investigate the role of charge delocalization and hyperconjugative interactions in the stability of the molecule.

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