Features of Mechanism of Cycloaddition Reaction between H2Sn=Sn: and Ethylene

The mechanism of the cycloaddition reaction between singlet H2Ge = Ge: and acetone has been investigated with CCSD(T)//MP2/6-31G* method. From the potential energy profile, it could be predicted that the reaction has two competitive dominant reaction pathways. The reaction rule presented 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 acetone forming a π → p donor–acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with acetone to form an intermediate. Because the Ge atom in intermediate happens sp3 hybridization after transition state, then, intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. Simultaneously, the ring strain of the four-membered Ge-heterocyclic ring germylene makes it isomerize to a twisted four-membered ring product.

Ab initio study of mechanism of forming a spiro-Si-heterocyclic ring compound from Me2Si[dbnd]Si: and formaldehyde

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.

Ab initio study of mechanism of forming a spiro-Ge-heterocyclic ring compound from H2Ge[dbnd]Ge: and formaldehyde

Density functional theory study of mechanism of forming a spiro-Si-heterocyclic ring compound from Me2Si[dbnd]Si: and acetaldehyde

The mechanism of the cycloaddition reaction between singlet H2Ge=Ge: and ethene has been investigated by the B3LYP/6-311 ++G** method. From the potential energy profile and change of Gibbs free energy, it could be predict that the reaction has only one dominant reaction pathway at 298 K and 149.825 kPa. The reaction rule presented is that the two reactants first 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 ethene forming a π → p donor–acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with ethene to form an intermediate; and because the Ge: atom in intermediate happens sp3 hybridization after transition state, then the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state.

The mechanism of cycloaddition reaction between singlet state dichloromethylenegermene (Cl2C=Ge:) and ethene has been investigated with the CCSD(T)//B3LYP/6-31G* method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction channel. The reaction rule presented is that the 4p unoccupied orbital of Ge in dichloromethylenegermene and the π orbital of ethene forming a π → p donor–acceptor bond resulting in the formation of a three-membered ring intermediate. Ring-enlargement effect make the three-membered ring intermediate isomerizes to a four-membered ring germylidene. Because the 4p unoccupied orbital of Ge atom in the four-membered ring germylidene and the π orbital of ethene form a π → p donor–acceptor bond, the four-membered ring germylidene further combines with ethene to form another intermediate. Because the Ge atom in the intermediate happens sp3 hybridization after transition state, the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound.

The H2Ge=Ge: and its derivatives (X2Ge=Ge:, X = H, Me, F, Cl, Br, Ph, Ar……) is a 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 acetone has been investigated with the B3LYP/6-31G* method in this article. From the potential energy profile, it can be predicted that the reaction has only one dominant reaction pathway. The reaction rule presented 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 acetone forming a π → p donor–acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with acetone to form an intermediate. Because the Ge: atom in the intermediate produces sp3 hybridization after a transition state, then the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. The research result indicated the laws of cycloaddition reaction between Me2Ge=Ge: and acetone, and laid the theory foundation of the cycloaddition reaction between H2Ge=Ge: and its derivatives (X2Ge=Ge:, X = H, Me, F, Cl, Br, Ph, Ar……) and asymmetric π-bonded compounds, which is significant for the synthesis of small-ring and spiro-heterocyclic ring compounds involving Ge. The study extends the research area and enriches the research content of germylene chemistry.

The mechanism of the cycloaddition reaction between singlet state silylene germylene (H2Si=Ge:) and formaldehyde has been investigated with the CCSD(T)//MP2/cc-pvtz method, from the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rules presented is that [2 + 2] cycloaddition reaction between two reactants firstly generates a Si-heterocyclic four-membered ring germylene. Because of the 4p unoccupied orbital of the Ge atom in (the) Si-heterocyclic four-membered ring germylene and the π orbital of formaldehyde forming a π → p donor–acceptor bond, the Si-heterocyclic four-membered ring germylene further combines with formaldehyde to form an intermediate. Because the Ge atom in intermediate happens sp 3 hybridization after transition state, then, intermediate isomerizes to a bis-heterocyclic compound with Si and Ge via a transition state.

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 ring compound via a transition state. The research result indicates the laws of cycloaddition reaction between Me2Ge=Ge: and acetaldehyde, and lays the theory foundation of the cycloaddition reaction between H2Ge=Ge: and its derivatives (X2Ge=Ge:, X=H, Me, F, Cl, Br, Ph, Ar, …) and asymmetric π-bonded compounds, which are significant for the synthesis of small-ring and spiro-Ge-heterocyclic ring compounds.

H2Ge=Si: and its derivatives (X2Ge=Si:, X=H, Me, F, Cl, Br, Ph, Ar, …) are new species. Its cycloaddition reactions are new area for the study of silylene chemistry. The cycloaddition reaction mechanism of singlet H2Ge=Si: and formaldehyde has been investigated with the MP2/aug-cc-pVDZ method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule is that 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 π orbital of formaldehyde forming a π→p donor-acceptor bond, the four-membered Ge-heterocyclic ring silylene further combines with formaldehyde to form an intermediate. Because the Si: atom in the intermediate undergoes sp3 hybridization after transition state, then the intermediate isomerizes to a spiro-Si-heterocyclic ring compound involving Ge via a transition state. The result indicates the laws of cycloaddition reaction between H2Ge=Si: or its derivatives (X2Ge=Si:, X=H, Me, F, Cl, Br, Ph, Ar, …) and asymmetric π-bonded compounds are significant for the synthesis of small-ring involving Si and Ge and spiro-Si-heterocyclic ring compounds involving Ge.

The mechanism of the cycloaddition reaction between singlet state dimethylsilylene germylidene (Me(2)Si = 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 sp(3) hybridization after transition state, then, the intermediate isomerizes to a spiro-heterocyclic ring compound with Si and Ge via a transition state.

The and its derivatives (, X = H, Me, F, Cl, Br, Ph, Ar) is a new species. Its cycloaddition reactions is a new area for the study of germylene chemistry. The mechanism of the cycloaddition reaction between singlet state Cl2Ge=Ge: and formaldehyde has been investigated with CCSD(T)//MP2/ method. From the potential energy profile, it could be predicted that the reaction has only one dominant reaction pathway. The reaction rule presented is that the two reactants first form a fourmembered 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 orbital of formaldehyde forming a donor-acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge: atom in intermediate hybridizes to an hybrid orbital after transition state, then, intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. The research result indicates the laws of cycloaddition reaction between and formaldehyde, and laid the theory foundation of the cycloaddition reaction between and its derivatives (, X = H, Me, F, Cl, Br, Ph, Ar) and asymmetric -bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds. The study extends research area and enriches the research content of germylene chemistry.

The mechanism of the cycloaddition reaction between singlet dichlorosilylenesilylene (Cl2Si=Si:)→Cl2Si=Si: and aldehyde 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 four-membered ring silylene through the [2+2] cycloaddition reaction. Because of the 3p unoccupied orbital of Si: atom in the four-membered ring silylene and the π orbital of aldehyde forming a π → p donor–acceptor bond, the four-membered ring silylene further combines with aldehyde to form an intermediate. Because the Si: atom in the intermediate happens sp 3 hybridization after transition state, then the intermediate isomerizes to a spiro-heterocyclic ring compound involving Si via a transition state.

The mechanism of the cycloaddition reaction between singlet dichlorosilylene germylidene (Cl2SiGe:) and formaldehyde 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 rule presented is that the two reactants first form a four-membered Si-heterocyclic ring germylene through the [2 + 2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge atom in the four-membered Si-heterocyclic ring germylene and the π orbital of formaldehyde forming a π→p donor–acceptor bond, the four-membered Si-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge atom in intermediate undergoes sp3 hybridization after transition state, then, the intermediate isomerizes to a spiro-heterocyclic ring compound involving Si and Ge via a transition state. © 2012 Wiley Periodicals, Inc.