Xiuhui Lu

Theoretical study on the mechanism of cycloaddition reaction between dichlorogermylene silylene (Cl2Ge=Si:) and acetaldehyde

The mechanism of the cycloaddition reaction between singlet state dichlorogermylene silylene (Cl2Ge=Si:) and acetaldehyde has been investigated with the MP2/cc-pvtz//MP2/6-31G* method. According to the potential energy profile, it can be predicted that the reaction has four competitive dominant reaction pathways. The presented rule of this reaction is that the 3p unoccupied orbital of Si: atom in dimethylgermylene silylene(Cl2Ge=Si:) inserts the π orbital of acetaldehyde from the oxygen side, resulting in the formation of intermediate. In the intermediate and two reactants, two four-membered ring silylenes, with Si and O in the syn-position and opposite orientation, respectively, are generated, as the [2+2] cycloaddition reaction has occurred between the two bonding π orbital in dichlorogermylene silylene and acetaldehyde. Because of the unsaturated property of Si: atom in the two four-membered ring silylenes, they can further react with acetaldehyde to form two silicic bis-heterocyclic compounds. Simultaneity, the drive of ringlet tensility and unsaturated property of Si: atom in the four-membered ring silylene makes it isomerize into a distorted four-membered ring product and a Cl-transfer product and a H-transfer product, respectively.

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.

Theoretical study of mechanism of cycloaddition reaction between 2,2-dimethyl(2-germavinylidene) [(CH3)2Ge=C:] and formaldehyde

The mechanism of the cycloaddition reaction between singlet 2,2-dimethyl(2-germavinylidene) [(CH3)2Ge=C:] and formaldehyde has been investigated with CCSD(T)//MP2/6-311G** method. From the potential energy profile, it could be predicted that the reaction has two competitive dominant reaction pathways. The first pathway consist of the transfer of formaldehyde oxygen π-electrons to the 2p unoccupied orbital of the C: atom in 2,2-dimethyl(2-germavinylidene) with a formation of intermediate which then isomerizes to a four-membered heterocyclic ring carbene (Ge and O in the 1,3-position). The second pathway is a direct [2 + 2] cycloaddition reaction in which the interaction of two π-bonds in 2,2-dimethyl(2-germavinylidene) and formaldehyde generates another four-membered heterocyclic ring carbene (Ge and O in 1,2-position). Because of the unsaturated property of the C: atom in the two four-membered heterocyclic ring carbenes, the two four-membered heterocyclic ring carbenes could further react with formaldehyde, generating two spiro-heterocyclic ring compounds.

Density Functional Theory Study on Mechanism of Forming Spiro‐Ge‐heterocyclic Ring Compound from Me2Ge=Ge: and Acetaldehyde

The H2Ge=Ge:, as well as and its derivatives (X2Ge=Ge:, X=H, Me, F, Cl, Br, Ph, Ar, …) is a kind of new species. Its cycloaddition reactions is a new area for the study of germylene chemistry. The mechanism of the cycloaddition reaction between singlet Me2Ge=Ge: and acetaldehyde was investigated with the B3LYP/6‐31G* method in this work. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule is that the two reactants firstly form a four‐membered Ge‐heterocyclic ring germylene through the [2+2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge: atom in the four‐membered Ge‐heterocyclic ring germylene and the π orbital of acetaldehyde forming a π→p donor‐acceptor bond, the four‐membered Ge‐heterocyclic ring germylene further combines with acetaldehyde to form an intermediate. Because the Ge atom in intermediate happens sp3 hybridization after transition state, then, intermediate isomerizes to a spiro‐Ge‐heterocyclic ri...

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 on the mechanism of cycloaddition reaction between silylene silylene(H2Si=Si:) and acetaldehyde

AbstractThe mechanism of the cycloaddition reaction between singlet silylene silylene (H2Si=Si:) and acetaldehyde has been investigated with CCSD(T)//MP2/6-31G* and CCSD(T)//MP2/6-31G** method, from the potential energy profile, we could predict that the reaction has three competitive dominant reaction pathways. The present rule of this reaction is that the 3p unoccupied orbital of the Si: atom in silylene silylene (H2Si=Si:) inserts on the π orbital of acetaldehyde from oxygen side, resulting in the formation of an intermediate. Isomerization of the intermediate further leads to the generation of a four-membered ring silylene (the H2Si-O in the opposite position). In addition, the [2 + 2] cycloaddition reaction of the two π-bonds in silylene silylene and acetaldehyde generates another four-membered ring silylene (the H2Si-O in the syn-position). Because of the unsaturated property of Si: atom in the two four-membered ring silylenes, they could further react with acetaldehyde, resulting in the generation of two spiro-heterocyclic ring compounds with Si. Simultaneously, the ring strain of the four-membered ring silylene (the H2Si-O in the syn-position) makes it isomerize to a twisted four-membered ring product. FigureThe potential energy profile for the cycloaddition reactions between H2Si = Si: and acetaldehyde with CCSD (T)//MP2/6-31G*

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.