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

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

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

Synthesis and Reactions of π‑Conjugated Iminoboranes Stabilized by Intramolecular Imine Groups

Reduction of the boron difluorides HC­[(CBu^<i>t</i>)­(NAr)]₂BF₂ led to C–N bond cleavage to give the iminoborane [C­(Bu^<i>t</i>)­CHC­(Bu^<i>t</i>)­NAr]­BNAr (<b>2</b>, Ar = 2,6-Me₂C₆H₃; <b>2′</b>, Ar = 2,6-Pr^<i>i</i>₂C₆H₃) stabilized by an intramolecular imine group. Reaction of <b>2</b> with NHC resulted in nucleophilic attack on the α-carbon atom to give [C­(Bu^<i>t</i>)­(NHC)­CHC­(Bu^<i>t</i>)­NAr]­BNAr (<b>3</b>). <b>2</b> reacted with CO₂ to give [C­(Bu^<i>t</i>)­CHC­(Bu^<i>t</i>)­NAr]­B­(CO₂)­NAr (<b>4</b>)

One-Step Access to Luminescent Pentaaryldiazaboroles via C–C Double Bond Formation from Imidoylstannanes

A series of pentaaryl-substituted diaza­boroles have been prepared for the first time by a novel strategy based on the C–C double bond formation from imidoylstannane reagents in the presence of dibromo­phenyl­boranes. The aryl substituents on the 4,5-position of the planar C₂N₂B core have substantial effects on their electronic structures. All the new diazaboroles are luminescent both in solution and in the solid state. DFT calculations indicate the 4,5-<i>C</i>-aryl substituents have significant contributions to the LUMOs

Isolable 1,1-Disubstituted Silole Dianion: a Homogeneous Two-Electron-Transfer Reducing Reagent

The 1,1-disubstituted silole dianion <b>2</b> has been isolated and characterized by single-crystal X-ray analysis for the first time. <b>2</b> can be used as a two-electron-transfer reducing reagent for the reduction of organic compounds and inorganic salts with regeneration of the corresponding neutral silole in nearly quantitative yields, indicating that it is an excellent reducing reagent. Reduction of (Mes)₂SiCl₂ with <b>2</b> selectively yielded the cyclotrisilane (Mes₂Si)₃ in high yield, which has not been isolated in pure form with the existing methods

One-Step Access to Luminescent Pentaaryldiazaboroles via C–C Double Bond Formation from Imidoylstannanes

A series of pentaaryl-substituted diaza­boroles have been prepared for the first time by a novel strategy based on the C–C double bond formation from imidoylstannane reagents in the presence of dibromo­phenyl­boranes. The aryl substituents on the 4,5-position of the planar C₂N₂B core have substantial effects on their electronic structures. All the new diazaboroles are luminescent both in solution and in the solid state. DFT calculations indicate the 4,5-<i>C</i>-aryl substituents have significant contributions to the LUMOs

One-Step Access to Luminescent Pentaaryldiazaboroles via C–C Double Bond Formation from Imidoylstannanes

A series of pentaaryl-substituted diaza­boroles have been prepared for the first time by a novel strategy based on the C–C double bond formation from imidoylstannane reagents in the presence of dibromo­phenyl­boranes. The aryl substituents on the 4,5-position of the planar C₂N₂B core have substantial effects on their electronic structures. All the new diazaboroles are luminescent both in solution and in the solid state. DFT calculations indicate the 4,5-<i>C</i>-aryl substituents have significant contributions to the LUMOs