A New Disilene with π-Accepting Groups from the Reaction of Disilyne RSiSiR (R = Si^<i>i</i>Pr[CH(SiMe₃)₂]) with Isocyanides

The reaction of 1,1,4,4-tetrakis­[bis­(trimethylsilyl)­methyl]-1,4-diisopropyltetrasila-2-yne (<b>1</b>) with <i>tert</i>-butylisocyanide or <i>tert</i>-octylisocyanide produced the corresponding disilyne–isocyanide adducts [RSiSiR­(CNR′)₂] (R = Si^<i>i</i>Pr­[CH­(SiMe₃)₂]₂, R′ = ^<i>t</i>Bu (<b>2a</b>) or CMe₂CH₂^<i>t</i>Bu (<b>2b</b>)), which are stable below −30 °C and were characterized by spectroscopic data and, in the case of <b>2a</b>, X-ray crystallography. Upon warming to room temperature, <b>2</b> underwent thermal decomposition to produce 1,2-dicyanodisilene R­(NC)­SiSi­(CN)­R (<b>3</b>) and 1,2-dicyanodisilane R­(NC)­HSiSiH­(CN)­R (<b>4</b>) via C–N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative <b>3</b> was characterized by X-ray crystallography

A New Disilene with π-Accepting Groups from the Reaction of Disilyne RSiSiR (R = Si^<i>i</i>Pr[CH(SiMe₃)₂]) with Isocyanides

The reaction of 1,1,4,4-tetrakis­[bis­(trimethylsilyl)­methyl]-1,4-diisopropyltetrasila-2-yne (<b>1</b>) with <i>tert</i>-butylisocyanide or <i>tert</i>-octylisocyanide produced the corresponding disilyne–isocyanide adducts [RSiSiR­(CNR′)₂] (R = Si^<i>i</i>Pr­[CH­(SiMe₃)₂]₂, R′ = ^<i>t</i>Bu (<b>2a</b>) or CMe₂CH₂^<i>t</i>Bu (<b>2b</b>)), which are stable below −30 °C and were characterized by spectroscopic data and, in the case of <b>2a</b>, X-ray crystallography. Upon warming to room temperature, <b>2</b> underwent thermal decomposition to produce 1,2-dicyanodisilene R­(NC)­SiSi­(CN)­R (<b>3</b>) and 1,2-dicyanodisilane R­(NC)­HSiSiH­(CN)­R (<b>4</b>) via C–N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative <b>3</b> was characterized by X-ray crystallography

[[(Me₃Si)₂CH]₂^<i>i</i>PrSi(NHC)SiSi(Me)Si^<i>i</i>Pr[CH(SiMe₃)₂]₂]⁺: A Molecule with Disilenyl Cation Character

Reaction of the disilyne–NHC complex <b>1</b> [RLSiSiR: (R = Si^<i>i</i>Pr­[CH­(SiMe₃)₂]₂, L = NHC)] with MeOTf gave the cation <b>2</b> [RLSiSiRMe]⁺, which is the first example of a base-stabilized heavy group 14 element analogue with vinyl cation character. Cation <b>2</b> has been fully characterized by multinuclear NMR spectroscopy and X-ray diffraction analysis. The molecular structure indicates that there are significant contributions from the NHC-stabilized cationic resonance structure <b>2A</b>, the disilene-like structure <b>2B</b>, and even some contribution from the silylene-like structure <b>2C</b>

An Isolable NHC-Stabilized Silylene Radical Cation: Synthesis and Structural Characterization

The silyl-substituted silylene–NHC complex bis­(tri-<i>tert</i>-butylsilyl)­silylene–(1,3,4,5-tetramethylimidazol-2-ylidene) [(^<i>t</i>Bu₃Si)₂Si:←NHC^Me, <b>2</b>] was synthesized and isolated as air- and moisture-sensitive orange crystals by reductive debromination of the dibromosilane (^<i>t</i>Bu₃Si)₂SiBr₂ (<b>1</b>) with 2.0 equiv of KC₈ in the presence of NHC^Me. In addition, the silylene–NHC complex <b>2</b> cleanly underwent one-electron oxidation with 1.0 equiv of Ph₃C⁺·Ar₄B^– (Ar₄B^– = tetrakis­[4-(<i>tert</i>-butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl]­borate) in benzene to afford the NHC-stabilized silylene radical cation [(^<i>t</i>Bu₃Si)₂Si←NHC^Me]^•+·Ar₄B^– (<b>3</b>). The radical cation <b>3</b> was isolated as air- and moisture-sensitive yellow crystals and structurally characterized by X-ray crystallography and electron paramagnetic resonance spectroscopy, which showed that <b>3</b> has a planar structure with a π-radical nature

A New Disilene with π-Accepting Groups from the Reaction of Disilyne RSiSiR (R = Si^<i>i</i>Pr[CH(SiMe₃)₂]) with Isocyanides

The reaction of 1,1,4,4-tetrakis­[bis­(trimethylsilyl)­methyl]-1,4-diisopropyltetrasila-2-yne (<b>1</b>) with <i>tert</i>-butylisocyanide or <i>tert</i>-octylisocyanide produced the corresponding disilyne–isocyanide adducts [RSiSiR­(CNR′)₂] (R = Si^<i>i</i>Pr­[CH­(SiMe₃)₂]₂, R′ = ^<i>t</i>Bu (<b>2a</b>) or CMe₂CH₂^<i>t</i>Bu (<b>2b</b>)), which are stable below −30 °C and were characterized by spectroscopic data and, in the case of <b>2a</b>, X-ray crystallography. Upon warming to room temperature, <b>2</b> underwent thermal decomposition to produce 1,2-dicyanodisilene R­(NC)­SiSi­(CN)­R (<b>3</b>) and 1,2-dicyanodisilane R­(NC)­HSiSiH­(CN)­R (<b>4</b>) via C–N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative <b>3</b> was characterized by X-ray crystallography

[[(Me₃Si)₂CH]₂^<i>i</i>PrSi(NHC)SiSi(Me)Si^<i>i</i>Pr[CH(SiMe₃)₂]₂]⁺: A Molecule with Disilenyl Cation Character

Reaction of the disilyne–NHC complex <b>1</b> [RLSiSiR: (R = Si^<i>i</i>Pr­[CH­(SiMe₃)₂]₂, L = NHC)] with MeOTf gave the cation <b>2</b> [RLSiSiRMe]⁺, which is the first example of a base-stabilized heavy group 14 element analogue with vinyl cation character. Cation <b>2</b> has been fully characterized by multinuclear NMR spectroscopy and X-ray diffraction analysis. The molecular structure indicates that there are significant contributions from the NHC-stabilized cationic resonance structure <b>2A</b>, the disilene-like structure <b>2B</b>, and even some contribution from the silylene-like structure <b>2C</b>

An Isolable NHC-Stabilized Silylene Radical Cation: Synthesis and Structural Characterization

The silyl-substituted silylene–NHC complex bis­(tri-<i>tert</i>-butylsilyl)­silylene–(1,3,4,5-tetramethylimidazol-2-ylidene) [(^<i>t</i>Bu₃Si)₂Si:←NHC^Me, <b>2</b>] was synthesized and isolated as air- and moisture-sensitive orange crystals by reductive debromination of the dibromosilane (^<i>t</i>Bu₃Si)₂SiBr₂ (<b>1</b>) with 2.0 equiv of KC₈ in the presence of NHC^Me. In addition, the silylene–NHC complex <b>2</b> cleanly underwent one-electron oxidation with 1.0 equiv of Ph₃C⁺·Ar₄B^– (Ar₄B^– = tetrakis­[4-(<i>tert</i>-butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl]­borate) in benzene to afford the NHC-stabilized silylene radical cation [(^<i>t</i>Bu₃Si)₂Si←NHC^Me]^•+·Ar₄B^– (<b>3</b>). The radical cation <b>3</b> was isolated as air- and moisture-sensitive yellow crystals and structurally characterized by X-ray crystallography and electron paramagnetic resonance spectroscopy, which showed that <b>3</b> has a planar structure with a π-radical nature

A Schrock-Type Germylene Complex: (η⁵‑C₅H₄Et)₂(PMe₃)HfGe(SiMe^tBu₂)₂

The stable group 4 metal germylene complex (η⁵-C₅H₄Et)₂(PMe₃)­HfGe­(SiMe^<i>t</i>Bu₂)₂ (<b>2</b>) is readily available by the reaction of the 1,1-dilithiogermane (^<i>t</i>Bu₂MeSi)₂GeLi₂ with (η⁵-C₅H₄Et)₂HfCl₂ in toluene at −50 °C, followed by treatment with trimethylphosphine. The hafnium–germanium bond distance of 2.6705(5) Å in <b>2</b> is indicative of its double-bond character, being ca. 3–7% shorter than the usual Hf–Ge single bonds. The novel hafnium germylene derivative is classified as a Schrock-type complex, featuring a negatively polarized nucleophilic germanium center

Stibasilene SbSi and Its Lighter Homologues: A Comparative Study

The multiply bonded derivatives of the heavier main group elements are among the most challenging targets for synthetic pursuits. Those of them featuring a double bond between the silicon and group 15 element are represented mostly by the silaimines <i>N</i>Si< and phosphasilenes PSi< with a very few examples of arsasilenes AsSi<. In this contribution, we report on the synthesis and structural elucidation of the first stable stibasilene and novel phosphasilene and arsasilene derivatives, featuring an identical substitution pattern. A systematic comparison within the series phosphasilene–arsasilene–stibasilene is made on the basis of their experimental and computational studies

Stibasilene SbSi and Its Lighter Homologues: A Comparative Study

The multiply bonded derivatives of the heavier main group elements are among the most challenging targets for synthetic pursuits. Those of them featuring a double bond between the silicon and group 15 element are represented mostly by the silaimines <i>N</i>Si< and phosphasilenes PSi< with a very few examples of arsasilenes AsSi<. In this contribution, we report on the synthesis and structural elucidation of the first stable stibasilene and novel phosphasilene and arsasilene derivatives, featuring an identical substitution pattern. A systematic comparison within the series phosphasilene–arsasilene–stibasilene is made on the basis of their experimental and computational studies