Zhenxia Lian

Ab initio study of mechanism of forming bis-heterocyclic compound with Si and Ge between dimethylsilylene germylidene (Me 2 Si=Ge:) and ethene

The mechanism of the cycloaddition reaction between singlet dimethylsilylene germylidene (Me2Si=Ge:) and ethene has been investigated with the CCSD(T)//MP2/6-31G* method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rules presented is that the two reactants firstly form a Si-heterocyclic four-membered ring germylene through the [2+2] cycloaddition reaction. Due to the sp3 hybridization of the Ge: atom in Si-heterocyclic four-membered ring germylene, the Si-heterocyclic four-membered ring germylene further combined with ethene to form a bis-heterocyclic product with Si and Ge (P2).

Ab initio Study on Mechanism of Forming a Silicic Bis-Heterocyclic Compound Between Dimethylmethylenesilylene and Ethene

The mechanism of the cycloaddition reaction of forming a silicic bis-heterocyclic compound between singlet dimethylmethylenesilylene (Me2C=Si:) and ethene has been investigated with the CCSD(T)//MP2/6-31G* method. From the potential energy profile, it can be predicted that, this reaction has one dominant channel. The presented rule of this dominant channel: the 3p unoccupied orbital of Si in dimethylmethylenesilylene and the π orbital of ethene forming the π→p donor-acceptor bond, resulting in the formation of three-membered ring intermediate (INT1); INT1 then isomerizes to a four-membered ring silylene (P2), which is driven by ring-enlargement effect; due to sp3 hybridization of Si atom in P2, P2 further combines with ethene to form a silicic bis-heterocyclic compound.

Ab initio study of the formation of bis-heterocyclic compound involving Si and Ge from dichlorosilylene germylidene (Cl2Si=Ge:) and ethene

The mechanism of the cycloaddition reaction between singlet state dichlorosilylene germylidene (Cl2Si=Ge:) and ethene has been investigated with CCSD(T)//MP2/6-31G* method, from the potential energy profile, we predict that the reaction has one dominant reaction pathway. The presented rule of the reaction is that the two reactants firstly form a Si-heterocyclic four-membered ring germylene through the [2+2] cycloaddition reaction. Due to the sp3 hybridization of the Ge: atom in Si-heterocyclic four-membered ring germylene, the Si-heterocyclic four-membered ring germylene further combined with the ethene to form a bis-heterocyclic compound with Si and Ge.

Ab initio study of mechanism of forming a spiro-heterocyclic ring compound with Si and Ge between dimethylsilylene germylidene (Me 2 Si = Ge:) and acetone

AbstractThe mechanism of the cycloaddition reaction between singlet state dimethylsilylene germylidene (Me2Si = Ge:) and acetone has been investigated with CCSD(T)//B3LYP/6-31G* method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rules presented are that the two reactants first form a Si-heterocyclic four-membered ring germylene through the [2 + 2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge atom in the Si-heterocyclic four-membered ring germylene and the π orbital of acetone forming a π→p donor-acceptor bond, the Si-heterocyclic four-membered ring germylene further combines with acetone to form an intermediate. Because the Ge atom in the intermediate happens sp3 hybridization after transition state, then, the intermediate isomerizes to a spiro-heterocyclic ring compound with Si and Ge via a transition state. FigureThe potential energy profile for the cycloaddition reactions between dimethylsilylene germylidene and acetone with CCSD(T)//B3LYP /6-31G*

Theoretical study of the mechanism of cycloaddition reaction between dichloro-germylidene and acetaldehyde

The mechanism of the cycloadditional reaction between singlet dichloro-germylidene(R1) and (acetaldehyde(R2) has been investigated with MP2/6-31G* method, including geometry optimization, vibrational analysis and energies for the involved stationary points on the potential energy surface. From the potential energy profile, we predict that the cycloaddition reaction between singlet dichloro-germylidene and acetaldehyde has two competitive dominant reaction pathways. Going with the formation of two side products (INT3 and INT4), simultaneously. The two competitive reactions both consist of two steps: (1) two reactants firstly form a three-membered ring intermediate (INT1) and a twisted four-membered ring intermediate (INT2), respectively, both of which are barrier-free exothermic reactions of 44.5 and 63.0 kJ/mol; (2) then INT1 and INT2 further isomerize to a four-membered ring product (P1) and a chlorine-transfer product (P2) via transitions (TS1 and TS2), respectively, with the barriers of 9.3 and 1.0 kJ/mol; simultaneously, P1 and INT2 react further with acetaldehyde(R2) to give two side products (INT3 and INT4), respectively, which are also barrier-free exothermic reaction of 65.4 and 102.7 kJ/mol.

Density Functional Theory Study of Mechanism of Cycloaddition Reaction Between Dimethyl-Silylene Carbene and Acetone

The mechanism of the cycloaddition reaction between singlet dimethyl-silylene carbene and acetone has been investigated with density functional theory, From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. The presented rule of this reaction: the [2+2] cycloaddition effect between the π orbital of dimethyl-silylene carbene and the π orbital of π-bonded compounds leads to the formation of a twisty four-membered ring intermediate and a planar four-membered ring product; The unsaturated property of C atom from carbene in the planar four-membered ring product, resulting in the generation of CH3-transfer product and silicic bis-heterocyclic compound.

Theoretical study of mechanism of cycloaddition reaction between singlet dichlorosilylene carbene (Cl2Si=C:) and formaldehyde

The mechanism of the cycloaddition reaction between singlet dichlorosilylene carbene (Cl2Si=C:) and formaldehyde has been investigated with MP2/6-31G* method, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated by Zero-point energy and CCSD (T)//MP2/6-31G* method. From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. The first dominant reaction pathway consists of two steps: (1) the two reactants (R1, R2) firstly form a four-membered ring intermediate (INT4) through a barrier-free exothermic reaction of 387.9 kJ/mol; (2) intermediate (INT4) then isomerizes to H-transfer product (P4.2) via a transition state (TS4.2) with energy barrier of 4.7 kJ/mol. The second dominant reaction pathway as follows: on the basis of intermediate (INT4) created between R1 and R2, intermediate (INT4) further reacts with formaldehyde (R2) to form the intermediate (INT5) through a barrier-free exothermic reaction of 158.3 kJ/mol. Then, intermediate (INT5) isomerizes to a silicic bis-heterocyclic product (P5) via a transition state (TS5), for which the barrier is 40.1 kJ/mol.

Theoretical study on the mechanism of extraction reaction between silylene carbene and its derivatives and thiirane

The mechanism of the sulfur extraction reaction between singlet silylene carbine and its derivatives and thiirane has been investigated with density functional theory (DFT), including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated by B3LYP/6-311G(d, p) method. From the potential energy profile, it can be predicted that the reaction pathway of this kind consists in two steps: (1) the two reactants firstly form an intermediate through a barrier-free exothermic reaction; (2) the intermediate then isomerizes to a product via a transition state. This kind of reactions has similar mechanism: when the silylene carbene and its derivatives [X2Si=C: (X = H, F, Cl, CH3)] and thiirane approach each other, the shift of 3p lone electron pair of S in thiirane to the 2p unoccupied orbital of C in X2Si=C: gives a p → p donor-acceptor bond, thereby leading to the formation of intermediate (INT). As the p → p donor-acceptor bond continues to strengthen (that is the C-S bond continues to shorten), the intermediate (INT) generates product (P + C2H4) via transition state (TS). It is the substituent electronegativity that mainly affect the extraction reactions. When the substituent electronegativity is greater, the energy barrier is lower, and the reaction rate is greater.

THEORETICAL STUDY OF THE MECHANISM OF CYCLOADDITION REACTION BETWEEN DICHLORO-SILYLENE CARBENE(CL2SI=C:) AND ACETONE

The mechanism of the cycloaddition reaction between singlet dichloro-silylene carbene and acetone has been investigated with DFT, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated by CCSD(T)//B3LYP/6-31G* method. From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. The channel (I) consists of two steps: (1) the two reactants firstly form a four-membered ring intermediate through a barrier-free exothermic reaction of 307.1 kJ/mol; (2) four-membered ring intermediate then isomerizes to a CH3-transfer product via a transition state with energy barrier of 11.3 kJ/mol. The process of channel (II) is as following: on the basis of four-membered ring intermediate created between the two reactants, four-membered ring intermediate further reacts with acetone to form the intermediate through a barrier-free exothermic reaction of 165.8 kJ/mol; Then, intermediate isomerizes to a silicic bis-heterocyclic product via a transition state, for which the barrier is 57.6 kJ/mol.

Ab initio Study of Mechanism of Forming Germanic Bis-Heterocyclic Compound Between Dichloro-Germylene Carbene (Cl2Ge = C:) and Formaldehyde

The mechanism of the cycloaddition reaction of forming germanic bis-heterocyclic compound between singlet dichloro-germylene carbene and formaldehyde has been investigated with CCSD(T)//MP2/6–31G* method, from the potential energy profile, we predict that the reaction has two competitive dominant reaction pathways. The presented rule of this reaction: the 2p unoccupied orbital of the C atom in dichloro-germylene carbene insert the π orbital of formaldehyde from oxygen side, resulting in the formation of intermediate. In the intermediate and between two reactants, because of the two bonding π orbital in dichloro-germylene carbene and formaldehyde have occurred [2+2] cycloaddition reaction, forming two four-membered ring compounds in which Ge and O are in the opposite orientation and in the syn-position, respectively. Because of the unsaturated property of C atom from carbene in the two four-membered ring compounds, they further reacts with formaldehyde, resulting in the generation of two germanic bis-heterocyclic compounds.