Ab initio Study on Formation Mechanism of Spiro-Si-Heterocyclic Ring Compound Involving Ge from H2Ge=Si: and Formaldehyde

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.     

Ab initio study of mechanism of cycloaddition reaction between H2Ge = Ge: and acetone

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.     

Density functional theory study of mechanism of forming a spiro-Ge-heterocyclic ring compound from H2Ge=Ge: and ethene

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.     

Ab initio study of mechanism of forming bis-heterocyclic compound with Si and Ge between dimethylsilylene germylidene (Me2Si=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 sp ³ 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 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 sp ³ 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.     

Theoretical study on the mechanism of cycloaddition reaction between dichlorogermylene silylene (Cl<Subscript>2</Subscript>Ge=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 a spiro-ge-heterocyclic ring compound

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 sp ³ hybridization after transition state, the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound.     

Ab initio study of mechanism of forming bis-heterocyclic compound with Si and Ge between silylene germylene (H2Si=Ge:) and formaldehyde

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 ?? orbital of formaldehyde forming a ??????p donor?Cacceptor 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.     

Ab initio study of the mechanism of forming a spiro‐heterocyclic ring compound involving Si and Ge from dichlorosilylene germylidene(Cl2SiGe:) and formaldehyde

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.     

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 of a mechanism of formation of a spiro heterocycle with the Ge spiroatom from dimethylgermylidene germylene (Me2Ge=Ge:) and ethylene

The B3LYP/6-311++G** study of the mechanism of the cycloaddition of singlet 2,2-dimethyl-1,2-digermavinylidene (Me₂Ge=Ge:) to ethylene was performed. [2+2] Cycloaddition of the reactants first produced four-membered cyclic germylene, then the interaction of unoccupied 4p orbital of the Ge atom with the π orbital of another ethylene molecule yielded intermediate with the π → p donor-acceptor bond. Isomerization of this intermediate via low-laying transition state resulted in spirocyclic compound with the sp³ hybridized Ge spiroatom.     

Ab initio Study of Mechanism of Cycloaddition Reaction between Germylene Silylene (H2GeSi:) and Acetone

The mechanism of the cycloaddition reaction between singlet germylene silylene (H₂GeSi:) and acetone has been investigated with CCSD(T)/6‐31G*//MP2/6‐31G* method. From the potential energy profile, we could predict that the reaction has two competitive dominant reaction channels. The present rule of this reaction is that the [2+2] cycloaddition reaction of the two (‐bonds in germylene silylene and acetone generates a four‐membered ring silylene with Ge. Because of the unsaturated property of Si atom in the four‐membered ring silylene with Ge, it could further react with acetone, resulting in the generation of a bis‐heterocyclic compound with Si and Ge. Simultaneously, the ring strain of the four‐membered ring silylene with Ge makes it isomerize to a twisted four‐membered ring product.     

Ab initio study of mechanism of forming a spiro-heterocyclic ring compound involving Si from dichlorosilylenesilylene (Cl2Si=Si:)→Cl2Si=Si: and aldehyde

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.     

Ab Initio Study of the Mechanism of Forming a Spiro-Si-heterocyclic Ring Compound Involving Ge from Cl_2Ge=Si:and Formaldehyde

The X2Ge=Si:(X = H, Me, F, Cl, Br, Ph, Ar···) is a new species. Its cycloaddition reaction is a new area for the study of silylene chemistry. The mechanism of cycloaddition reaction between singlet Cl2Ge=Si: and formaldehyde has been investigated with 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 reaction rule presented is that the two reactants firstly form a four-membered Ge-heterocyclic ring silylene through the [2+2] cycloaddition reaction. Owing to 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 intermediate shows sp3 hybridization after transition state, the intermediate isomerizes to a spiro-Si-heterocyclic ring compound involving Ge via a transition state. Simultaneously, the ring strain of the four-membered Ge-heterocyclic ring silylene makes it isomerize to a twisted four-membered ring product. The research result indicates the laws of cycloaddition reaction between X2Ge=Si:(X = H, Me, F, Cl, Br, Ph, Ar···) and the asymmetric π-bonded compounds, which are significant for the synthesis of small-ring and spiro-Si-heterocyclic ring compound involving Ge. The study extends the research area and enriches the research content of silylene chemistry.     

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 πorbital 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.     

Synthese und Strukturen von Bis(amino)germa- und -stanna-Chalkogeniden

Synthesis and Structures of Bis(amino)germa and -stanna Chalcogenides The cyclic bis(amino)germylene 1 and the -stannylene 2 react with elemental S, Se and Te to yield oxydation products of the general formula Me₂Si(NtBu)₂MEl₂M(NtBu)₂SiMe₂ (M = Ge, El = S ( 4 ), El = Se ( 5 ), El = Te ( 6 ); M = Sn, El = Se ( 9 ), El = Te ( 10 )). As may be deduced from X-ray structures ( 4, 5, 6, 9, 10 ) all compounds show similar central skeletons: the three spirocyclicly connected four-membered rings SiN₂M (2x) and MEl₂M are oriented in an orthogonal way to oneanother. The germanium and the tin atoms thus are in a distorted tetrahedral coordination while the chalcogen atoms only have two neighbours in acute angles. If 1 is allowed to react with trimethylamine-N-oxide, the oxygen is transferred to germanium and [Me₂Si(NtBu)₂GeO]₃ ( 3 ) is formed. Contrarily to the other compounds 3 can be described as a trimer. There is a central almost planar Ge₃O₃ six-membered ring, the germanium atoms serving as spiro-cyclic centres to three GeN₂Si four-membered rings (X-ray structure of 3 ). In the central four-membered rings of 4, 5, 6, 9 and 10 no transanular bonding between the chalcogen atoms have to be considered although these atoms have small distances to oneanother. The mean M-El distances have been found to be: Ge? O 1.762(5), Ge? S 2.226(3), Ge? Se 2.363(3), Ge? Te 2.592(5), Sn? Se 2.536(3), Sn? Te 2.741(3) Å.     

Über die Halogenaminierung von Diseleniden. Synthese und Struktur des achtgliedrigen Ring-Kations [Me2SN2SeMe]2++

On the Haloamination of Diselenides. Synthesis and Structure of the Eight-membered Ring Cation [Me₂SN₂SeMe]₂⁺⁺ N-halogen compounds of benzamidine and S,S-dimethylsulfone diimides react with diselenides by Se? Se-bond cleavage yielding different types of selenium-nitrogen compounds. With N-bromo-benzamidine the diazene derivatives RSeN(Ph)CN?NC(Ph)NSeR 2a, b (a : R = Me; b : R = Ph) are formed. In the reaction of N,N′-Dichloro-S,S-dimethylsulfone diimide, Me₂S(NCl)₂, with diselenides cyclic hetero-selenonium salts [(Me₂SN₂SeR)Cl]₂ ( 4a, b ) are obtained. The structure of the eight membered ring compound 4a was determined by x-ray crystallography (space group P1 , Z = 1) and compared with that of the isotypic sulfonium salt [(Me₂SN₂SMe)Br]₂ ( 3a ).     

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.     

Synthesis, structure, and reactivity of a pyridine-stabilized germanone

The first isolable pyridine‐stabilized germanone has been prepared and its reactivity toward trimethylaluminum has been investigated. The germanone adduct results from a stepwise conversion that starts from 4‐dimethylaminopyridine (DMAP) and the ylide‐like N‐heterocyclic germylene LGe: (L=CH{(C?CH₂)(CMe)[N(aryl)]₂}, aryl=2,6‐iPr₂C₆H₃) ( 1 ) at room temperature, and gives the corresponding germylene–pyridine adduct L(DMAP)Ge: ( 2 ) in 91 % yield. The latter reacts with N₂O at room temperature to form the desired germanone complex L(DMAP)Ge?O ( 3 ) in 73 % yield. The Ge? O distance of 1.646(2) Å in 3 is the shortest hitherto reported for a Ge?O species. The reaction of 3 with trimethylaluminum leads solely to the addition product LGe(Me)O[Al(DMAP)Me₂] ( 4 ). The latter results from insertion of the Ge?O subunit into an Al? Me bond of AlMe₃ and concomitant migration of the DMAP ligand from germanium to the aluminum atom. Compounds 2 – 4 have been fully characterized by analytical and spectroscopic methods. Their molecular structures have been established by single‐crystal X‐ray crystallographic analysis.     

Structures of the phosphinidene germylenoid HP=GeLiF and its cycloaddition reaction with ethylene

The structures of phosphinidene germylenoid HP=GeLiF were studied for the first time by using DFT (density functional theory) calculations. The geometries were optimized at the B3LYP/6-311+G (d, p) level at first and then the single-point energies were calculated at QCISD/6-311++G (d, p) level. Theoretical calculations predicted that HP=GeLiF has two equilibrium structures, the p-complex (1) and the three-membered-ring (2) structures, in which structure 1 has the lower energy and is more stable than 2. To exploit the reactivity of HP=GeLiF, the cycloaddition reaction of 1 and ethylene was investigated at the same level of theory. From the potential energy profile, we predicted that the cycloaddition reaction has one dominant reaction pathway. The calculated result shows that the dominant reaction pathway is a [2?+?2] cycloaddition reaction which is the interaction of two π bonds in HP=GeLiF and ethylene molecule, and a four-membered-ring P-heterocyclic germylene is formed. Since sp³ hybridization of Ge atom in this four-membered-ring germylene, it may further react with another ethylene and finally forming a spiro-Ge-heterocyclic compound involving phosphorus. This means that this reaction involves a [2?+?2] cycloaddition as the initial step, and then a [2?+?1] cycloaddition carried out.