Synthesis of Phosphine-Functionalized Silicon Cubane and Its Oxidative Addition, Giving a Bis(silyl)copper Complex

A new strategy for the introduction of a second type of Si atom to silicon cubanes has been developed starting from the tricyclic hexasilane dianion [Ar6Si6]2– (Ar = 2,4,6-Me3C6H2). Treatment of the dianion with Ar′SiCl3, followed by KC8, gave new types of octasilacubanes Ar6Ar′2Si8 [Ar′ = 2,4,6-iPr2C6H2 (3a), 2-Ph2PC6H4 (3b)] in high yields. Remarkably, treatment of cubane 3b bearing with two phosphine groups with 2 equiv of CuCl in CH2Cl2 yielded the bis(silyl)copper complex via the selective oxidative addition of the newly formed Si–Si bond to Cu ion. Single-crystal X-ray analysis indicated the unique square-planar, four-coordinate Cu cation paired with the [CuCl2]− counteranion

Synthesis of Calcium and Ytterbium Complexes Supported by a Tridentate Imino-Amidinate Ligand and Their Application in the Intermolecular Hydrophosphination of Alkenes and Alkynes

Well-defined calcium and ytterbium complexes [{2-NC­(Ph)­NArC₆H₄CHNAr}­M­{N­(SiMe₃)₂}­(THF)] (M = Ca, Yb; Ar = 2,6-<i>i</i>Pr₂C₆H₃) have been synthesized and characterized. They catalyze the intermolecular hydrophosphination of alkenes, dienes, and alkynes with high activity and selectivity under mild conditions. Highly selective 1,4-additions (94–100%) for the conjugated dienes examined have been observed with both catalysts. The calcium complex exclusively catalyzes anti addition to alkynes, including terminal alkynes, while the ytterbium, in most cases, catalyzes syn addition. The calcium catalyst could promote hydrophosphination of hindered alkenes such as stilbene under relatively mild conditions

Metal-Free, Stereospecific Bis-Silylation of Functionalized Alkynes with NHC-Supported Silylaminosilylene

The NHC-supported silylaminosilylene Ar­(SiMe₃)­N­(Cl)­Si­(I<i>i</i>Pr) (<b>1</b>; Ar = 2,6-<i>i</i>Pr₂C₆H₃, I<i>i</i>Pr = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) is an efficient and stereospecific bis-silylation reagent for a range of functionalized alkynes to yield cis-1,2-bis-silylated alkenes via a 1,4-silyl migration from the amino nitrogen atom to an alkyne carbon atom. The reaction is regio- and stereospecific for terminal alkynes with an electron-withdrawing substituent, thus providing a facile access to 1,2-bis-silylated alkenes with two different silyl groups

2‑Hydro-2-aminophosphasilene with N–Si–P π Conjugation

The first 2-aminophosphasilene, [Ar­(Me₃Si)­N]­HSiPAr′ (<b>4</b>, Ar = 2,6-<i>i</i>Pr₂C₆H₃, Ar′ = 2,6-Mes₂C₆H₃), bearing a hydride ligand on the three-coordinate silicon atom has been synthesized and structurally characterized. Both X-ray data of <b>4</b> and DFT calculations on the model compound (H₂N)­HSiPH (<b>4′</b>) disclosed that the amino group on the silicon atom results in significant N–Si–P π conjugation

Selective Silylation of Nitriles with an NHC-Stabilized Silylene to 1,2-Disilylimines and Subsequent Synthesis of Silaaziridines

The highly regioselective synthesis of <i>trans</i>-1,2-disilylimines have been achieved by the bis-silylation of nitriles with the NHC-stabilized silylene NHC-Si­(NArSiMe₃)Cl (<b>1</b>; Ar = 2,6-<i>i</i>Pr₂C₆H₃, NHC = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene). The bis-silylation involves the migration of the SiMe₃ group on the nitrogen atom in the silylene to the carbon atom of the nitrile functionality. The 1,2-disilylimine products feature an NHC-stabilized silaimine moiety and could undergo nucleophilic attack by phenyllithium reagents to yield novel silaaziridines with an NHC-stabilized exocyclic SiN double bond

Cyclopropanation and Isomerization Reactions of β-Diketiminato Boron Complexes

The reaction of HC­[(CBu^<i>t</i>)­(NAr)]₂Li with BCl₃ yielded the azaallyl boron dichloride [ArNC­(Bu^<i>t</i>)­C­(H)­C­(Bu^<i>t</i>)­N­(Ar)]­BCl₂ (<b>1</b>), which can be converted to the β-diketiminato boron dichloride HC­[(CBu^<i>t</i>)­(NAr)]₂BCl₂ (<b>2</b>) upon heating at 40 °C. Reaction of <b>1</b> with the bulky lithium salts LiN­(SiMe₃)₂ and MesLi (Mes = 2,4,6-Me₃C₆H₂) resulted in the cyclopropanation of the CBu^<i>t</i> group via the deprotonation of the methyl group, while reactions with PhLi and LiNEt₂ gave substitution products

Cyclopropanation and Isomerization Reactions of β-Diketiminato Boron Complexes

The reaction of HC­[(CBu^<i>t</i>)­(NAr)]₂Li with BCl₃ yielded the azaallyl boron dichloride [ArNC­(Bu^<i>t</i>)­C­(H)­C­(Bu^<i>t</i>)­N­(Ar)]­BCl₂ (<b>1</b>), which can be converted to the β-diketiminato boron dichloride HC­[(CBu^<i>t</i>)­(NAr)]₂BCl₂ (<b>2</b>) upon heating at 40 °C. Reaction of <b>1</b> with the bulky lithium salts LiN­(SiMe₃)₂ and MesLi (Mes = 2,4,6-Me₃C₆H₂) resulted in the cyclopropanation of the CBu^<i>t</i> group via the deprotonation of the methyl group, while reactions with PhLi and LiNEt₂ gave substitution products

Cyclopropanation and Isomerization Reactions of β-Diketiminato Boron Complexes

The reaction of HC­[(CBu^<i>t</i>)­(NAr)]₂Li with BCl₃ yielded the azaallyl boron dichloride [ArNC­(Bu^<i>t</i>)­C­(H)­C­(Bu^<i>t</i>)­N­(Ar)]­BCl₂ (<b>1</b>), which can be converted to the β-diketiminato boron dichloride HC­[(CBu^<i>t</i>)­(NAr)]₂BCl₂ (<b>2</b>) upon heating at 40 °C. Reaction of <b>1</b> with the bulky lithium salts LiN­(SiMe₃)₂ and MesLi (Mes = 2,4,6-Me₃C₆H₂) resulted in the cyclopropanation of the CBu^<i>t</i> group via the deprotonation of the methyl group, while reactions with PhLi and LiNEt₂ gave substitution products

Cesium Carbonate-Catalyzed Reduction of Amides with Hydrosilanes

Cesium carbonate has been found to be an effective catalyst for the reduction of tertiary carboxamides with the simple, commercially available PhSiH₃ under solvent-free conditions. The catalytic system can effectively reduce a range of amides under relatively mild conditions (from room temperature to 80 °C) to yield the corresponding amines in good to excellent yields (71–100%) and thus has the potential for practical applications

Cyclopropanation and Isomerization Reactions of β-Diketiminato Boron Complexes

The reaction of HC­[(CBu^<i>t</i>)­(NAr)]₂Li with BCl₃ yielded the azaallyl boron dichloride [ArNC­(Bu^<i>t</i>)­C­(H)­C­(Bu^<i>t</i>)­N­(Ar)]­BCl₂ (<b>1</b>), which can be converted to the β-diketiminato boron dichloride HC­[(CBu^<i>t</i>)­(NAr)]₂BCl₂ (<b>2</b>) upon heating at 40 °C. Reaction of <b>1</b> with the bulky lithium salts LiN­(SiMe₃)₂ and MesLi (Mes = 2,4,6-Me₃C₆H₂) resulted in the cyclopropanation of the CBu^<i>t</i> group via the deprotonation of the methyl group, while reactions with PhLi and LiNEt₂ gave substitution products