Vinylidene and its heavier analogues are fundamentally important in synthetic chemistry,but their stabilization and structural characterization remains extremely challenging.Herein we describe that the reduction of an...Vinylidene and its heavier analogues are fundamentally important in synthetic chemistry,but their stabilization and structural characterization remains extremely challenging.Herein we describe that the reduction of an NHSi-stabilized stannyl-stannylene(2)with one molar equivalent of[(^(Mes)Nacnac)Mg]_(2)affords an NHSi-stabilized distannavinylidene(3).Single-crystal X-ray crystallography and density functional theory(DFT)calculations show that compound 3 features a pronounced Sn=Sn double bond and one lone pair of electrons at the two-coordinate Sn atom.Most strikingly,3 undergoes an interconversion with distannyne(4)upon the addition and removal of one molar equivalent of N-heterocyclic carbene.Compound 3 readily reacts with Ph_(2)C=C=O,Ad C≡P and(Al Cp^(*))_(4)to give the structurally interesting stannacycles(5,6)and an aluminyl distannyne(7),demonstrating its unique reactivity derived from the high substituent lability.展开更多
The mechanism of cycloaddition reaction between singlet silylene carbene and acetone has been investigated with CCSD（T）//MP2/6-31G method. From the potential energy profile, it can be predicted that the reaction has...The mechanism of cycloaddition reaction between singlet silylene carbene and acetone 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. One 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 585.9 kJ/mol; （2） Then intermediate （INT4） isomerizes to CH3-transfer product （P4.1） via a transition state （TS4.1） with energy barrier of 5.3 kJ/mol. The other is as follows： on the basis of intermediate （INT4） created between R1 and R2, intermediate （INT4） further reacts with acetone （R2） to form the intermediate （INT5） through a barrier-free exothermic reaction of 166.3 kJ/mol; Then, intermediate （INT5） isomerizes to a silicic bis-heterocyclic product （P5） via a transition state （TS5）, for which the barrier is 54.9 kJ/mol. The presented rule of this reaction： the [2＋2] cycloaddition effect between the π orbital of silylene carbene and the π orbital of π-bonded compounds leads to the formation of a four-membered ring intermediate （INT4）; The unsaturated property of C atom from carbene in the four-membered ring intermediate （INT4） results in the generation of CH3-transfer product （P4.1） and silicic bis-heterocyclic compound （P5）.展开更多
The X2Ge=Si： （X = H, Me, F, reaction is a new area for the study of silylene between singlet CI2Ge=Si： and formaldehyde CI, Br, Ph, At...） is a new species. Its cycloaddition chemistry. The mechanism of cycloaddit...The X2Ge=Si： （X = H, Me, F, reaction is a new area for the study of silylene between singlet CI2Ge=Si： and formaldehyde CI, Br, Ph, At...） is a new species. Its cycloaddition chemistry. The mechanism of cycloaddition reaction 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, C1, Br, Ph, Ar...） and the asymmetric g-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 silvlene chemistrv.展开更多
The metal-substituted silylenes are of high interest,as the theoretical studies indicated that the silylenes with electropositive substituents have a small ΔE_(S-T)(singlet-triplet energy gap)or even the ground-state...The metal-substituted silylenes are of high interest,as the theoretical studies indicated that the silylenes with electropositive substituents have a small ΔE_(S-T)(singlet-triplet energy gap)or even the ground-state triplets.However,such compounds are highly unstable,and only two transient alkali metal-substituted silylenes M(^(t)Bu_(3)Si)Si:(M=Li,K)were generated by photoextrusion of the alkali metal-substituted silacyclopropenes and merely studied by spectroscopic method(EPR)at low temperature(14 to 50 K).Herein,we report the generation of transient zinc-substituted silylenes from zinc silacyclopropanyl complexes under very mild and convenient conditions.The generated transient zinc-substituted silylenes are highly reactive and undergo intermolecular cycloaddition with alkenes for the synthesis of zinc-substituted Si-heterocyclic compounds.If there is no substrate,the zinc-substituted silylenes attack the C-C bonds of the β-diketiminato ligands and break the C-C bonds.DFT studies further highlight the silylene nature of the zinc-substituted silylene and a very small ΔE_(S-T)(4.4 kcal/mol).展开更多
The mechanism of the cycloaddition reaction between singlet silylene silylene （H2Si = Si：） and acetone has been investigated with the CCSD （T）//MP2/6-31 G＊ method, According to the potential energy profile, it c...The mechanism of the cycloaddition reaction between singlet silylene silylene （H2Si = Si：） and acetone has been investigated with the CCSD （T）//MP2/6-31 G＊ method, According to the potential energy profile, it can be predicted 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 silylene silylene （H2Si=Si：） and acetone leads to the formation of a four-membered ring silylene （E3）. Because of the unsaturated property of Si： atom in E3, it further reacts with ace- tone to form a silicic bis-heterocyclic compound （P7）. Simultaneously, the ring strain of the four-membered ring silylene （E3） makes it isomerize to a twisted four-membered ring product （P4）.展开更多
The mechanism of the cycloaddition reaction between singlet germylene silylene （H2Ge =Si：） and acetone has been investigated with CCSD（T）/6-31G＊//MP2/6-31 G＊ method. From the potential energy profile, we could ...The mechanism of the cycloaddition reaction between singlet germylene silylene （H2Ge =Si：） and acetone has been investigated with CCSD（T）/6-31G＊//MP2/6-31 G＊ 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 π-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. Simul- taneously, the ring strain of the four-membered ring silylene with Ge makes it isomerize to a twisted four-membered ring product.展开更多
We have discovered a route to access the longest low-valent molecular silaphospha-chain,a sevenmembered chain structure that incorporates three silicon and four phosphorus atoms by stepwise activation of white phospho...We have discovered a route to access the longest low-valent molecular silaphospha-chain,a sevenmembered chain structure that incorporates three silicon and four phosphorus atoms by stepwise activation of white phosphorus(P_(4))using two different silylene precursors.The chain species was formed via a highly reactive polyphosphide intermediate.The isolation of a stable analogue of this reaction intermediate was achieved by stepwise reaction with mono and bis(silylenes).Due to the rigidity of the ferrocenediyl framework of the bis(silylene),the isomerization process of the chain structure was hampered.Theoretical studies such as natural bond orbital and atoms in molecules analyses of the seven-membered chain species indicated some degree of delocalization of the double bond system.展开更多
Carboranes are a class of polyhedral boron-carbon molecular clusters,they can serve as versatile ligands in stabilizing low-valent main group element compounds,due to their exceptionally thermal and chemical stabiliti...Carboranes are a class of polyhedral boron-carbon molecular clusters,they can serve as versatile ligands in stabilizing low-valent main group element compounds,due to their exceptionally thermal and chemical stabilities,easy modifications at the cage carbon vertices,as well as large spherical steric effects.These carborane-based ligands provide interesting opportunities for the synthesis of low-valent main group element compounds with novel structure and reactivity,which indeed enrich the chemistry of low-valent element main group compounds.This review summarizes the recent advances in the chemistry of lowvalent group 13 and group 14 element compounds supported by carborane-based ligands.Achievements and perspectives in this new and flourishing field are discussed in this review.展开更多
基金supported by the National Natural Science Foundation of China(22071124,22371130,22221002)the Frontiers Science Center for New Organic Matter at Nankai University(C029215001)+1 种基金the Fundamental Research Funds for the Central Universities(63206007)the Nankai University and Young Elite Scientists Sponsorship Program by Tianjin。
文摘Vinylidene and its heavier analogues are fundamentally important in synthetic chemistry,but their stabilization and structural characterization remains extremely challenging.Herein we describe that the reduction of an NHSi-stabilized stannyl-stannylene(2)with one molar equivalent of[(^(Mes)Nacnac)Mg]_(2)affords an NHSi-stabilized distannavinylidene(3).Single-crystal X-ray crystallography and density functional theory(DFT)calculations show that compound 3 features a pronounced Sn=Sn double bond and one lone pair of electrons at the two-coordinate Sn atom.Most strikingly,3 undergoes an interconversion with distannyne(4)upon the addition and removal of one molar equivalent of N-heterocyclic carbene.Compound 3 readily reacts with Ph_(2)C=C=O,Ad C≡P and(Al Cp^(*))_(4)to give the structurally interesting stannacycles(5,6)and an aluminyl distannyne(7),demonstrating its unique reactivity derived from the high substituent lability.
文摘The mechanism of cycloaddition reaction between singlet silylene carbene and acetone 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. One 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 585.9 kJ/mol; （2） Then intermediate （INT4） isomerizes to CH3-transfer product （P4.1） via a transition state （TS4.1） with energy barrier of 5.3 kJ/mol. The other is as follows： on the basis of intermediate （INT4） created between R1 and R2, intermediate （INT4） further reacts with acetone （R2） to form the intermediate （INT5） through a barrier-free exothermic reaction of 166.3 kJ/mol; Then, intermediate （INT5） isomerizes to a silicic bis-heterocyclic product （P5） via a transition state （TS5）, for which the barrier is 54.9 kJ/mol. The presented rule of this reaction： the [2＋2] cycloaddition effect between the π orbital of silylene carbene and the π orbital of π-bonded compounds leads to the formation of a four-membered ring intermediate （INT4）; The unsaturated property of C atom from carbene in the four-membered ring intermediate （INT4） results in the generation of CH3-transfer product （P4.1） and silicic bis-heterocyclic compound （P5）.
基金supported by the National Natural Science Foundation of China(No.51102114)
文摘The X2Ge=Si： （X = H, Me, F, reaction is a new area for the study of silylene between singlet CI2Ge=Si： and formaldehyde CI, Br, Ph, At...） is a new species. Its cycloaddition chemistry. The mechanism of cycloaddition reaction 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, C1, Br, Ph, Ar...） and the asymmetric g-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 silvlene chemistrv.
基金supported by the National Natural Science Foundation of China(21890721,21732007)the Shanghai Municipal Committee of Science and Technologythe Chinese Academy of Sciences President’s International Fellowship Initiative。
文摘The metal-substituted silylenes are of high interest,as the theoretical studies indicated that the silylenes with electropositive substituents have a small ΔE_(S-T)(singlet-triplet energy gap)or even the ground-state triplets.However,such compounds are highly unstable,and only two transient alkali metal-substituted silylenes M(^(t)Bu_(3)Si)Si:(M=Li,K)were generated by photoextrusion of the alkali metal-substituted silacyclopropenes and merely studied by spectroscopic method(EPR)at low temperature(14 to 50 K).Herein,we report the generation of transient zinc-substituted silylenes from zinc silacyclopropanyl complexes under very mild and convenient conditions.The generated transient zinc-substituted silylenes are highly reactive and undergo intermolecular cycloaddition with alkenes for the synthesis of zinc-substituted Si-heterocyclic compounds.If there is no substrate,the zinc-substituted silylenes attack the C-C bonds of the β-diketiminato ligands and break the C-C bonds.DFT studies further highlight the silylene nature of the zinc-substituted silylene and a very small ΔE_(S-T)(4.4 kcal/mol).
文摘The mechanism of the cycloaddition reaction between singlet silylene silylene （H2Si = Si：） and acetone has been investigated with the CCSD （T）//MP2/6-31 G＊ method, According to the potential energy profile, it can be predicted 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 silylene silylene （H2Si=Si：） and acetone leads to the formation of a four-membered ring silylene （E3）. Because of the unsaturated property of Si： atom in E3, it further reacts with ace- tone to form a silicic bis-heterocyclic compound （P7）. Simultaneously, the ring strain of the four-membered ring silylene （E3） makes it isomerize to a twisted four-membered ring product （P4）.
文摘The mechanism of the cycloaddition reaction between singlet germylene silylene （H2Ge =Si：） and acetone has been investigated with CCSD（T）/6-31G＊//MP2/6-31 G＊ 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 π-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. Simul- taneously, the ring strain of the four-membered ring silylene with Ge makes it isomerize to a twisted four-membered ring product.
基金supported by the Deutsche Forschungsgemeinschaft(DFG)[project no.470309834(Ro2008/21-1 and HI 2063/1-1)]the support by the state of Baden-Württemberg through bwHPC and DFG[grant no.INST 40/467-1 FUGG(JUSTUS cluster)].
文摘We have discovered a route to access the longest low-valent molecular silaphospha-chain,a sevenmembered chain structure that incorporates three silicon and four phosphorus atoms by stepwise activation of white phosphorus(P_(4))using two different silylene precursors.The chain species was formed via a highly reactive polyphosphide intermediate.The isolation of a stable analogue of this reaction intermediate was achieved by stepwise reaction with mono and bis(silylenes).Due to the rigidity of the ferrocenediyl framework of the bis(silylene),the isomerization process of the chain structure was hampered.Theoretical studies such as natural bond orbital and atoms in molecules analyses of the seven-membered chain species indicated some degree of delocalization of the double bond system.
基金the National Natural Science Foundation of China(No.21901039)the Natural Science Foundation of Jiangsu Province(No.BK20190327)。
文摘Carboranes are a class of polyhedral boron-carbon molecular clusters,they can serve as versatile ligands in stabilizing low-valent main group element compounds,due to their exceptionally thermal and chemical stabilities,easy modifications at the cage carbon vertices,as well as large spherical steric effects.These carborane-based ligands provide interesting opportunities for the synthesis of low-valent main group element compounds with novel structure and reactivity,which indeed enrich the chemistry of low-valent element main group compounds.This review summarizes the recent advances in the chemistry of lowvalent group 13 and group 14 element compounds supported by carborane-based ligands.Achievements and perspectives in this new and flourishing field are discussed in this review.
基金Supported by the National Natural Science Foundation of China(20571033 & 20701016)by the Program for New Century Excellent Talents in University(NCET-06-0483)~~
