Although known for over 90 years, only in the past two decades has the chemistry of diboron(4) compounds been extensively explored. Many interesting structural features and reaction patterns have emerged, and more importantly, these compounds now feature prominently in both metal-catalyzed and metal-free methodologies for the formation of B–C bonds and other processes.

Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse

Asymmetric hydrogenation of acetophenone with trans-RuH(η1-BH4)[(S)-tolbinap][(S,S)-dpen] (TolBINAP = 2,2‘-bis(di-4-tolylphosphino)-1,1‘-binaphthyl; DPEN = 1,2-diphenylethylenediamine) in 2-propanol gives (R)-phenylethanol in 82% ee. The reaction proceeds smoothly even at an atmospheric pressure of H2 at room temperature and is further accelerated by addition of an alkaline base or a strong organic base. Most importantly, the hydrogenation rate is initially increased to a great extent with an increase in base molarity but subsequently decreases. Without a base, the rate is independent of H2 pressure in the range of 1−16 atm, while in the presence of a base, the reaction is accelerated with increasing H2 pressure. The extent of enantioselection is unaffected by hydrogen pressure, the presence or absence of base, the kind of base and coexisting metallic or organic cations, the nature of the solvent, or the substrate concentrations. The reaction with H2/(CH3)2CHOH proceeds 50 times faster than that with D2/(...

Mechanism of Asymmetric hydrogenation of ketones catalyzed by BINAP/1,2-diamine-ruthenium(II) complexes

Transition Metal−Boryl Compounds: Synthesis, Reactivity, and Structure

Supramolecular structural transformations involving coordination polymers in the solid state

Electron-precise coordination modes of boron-centered ligands.

Convenient synthesis of K[(C5H4MeMnH(CO)2] and reactions with Cl2B[N(SiMe3)2] and B2R2Cl2 (R = Me2N, Me3C)

Asymmetric hydrovinylation of styrene applying cationic allyl palladium complexes of a P-chiral ligand

A New Concept for Chelate Ligands with Planar Chirality

Reaction of Na[(Cp)Fe(CO)2] and Na[(Cp)W(CO)3] with B2(NMe2)2Cl2 yields the first transition metal-substituted diboranes [Cl(Me2N)B–B(NMe2)M(Cp)(CO)n] [M(Cp)(CO)n Fe(Cp)(CO)2, W(Cp)(CO)3] (1a, b). The compounds were characterized in solution by NMR methods and in the crystal by X-ray structural determination.

Diboran(4)yl Groups as Ligands to Transition Metals

Reactivity of Acetylenes toward the Titanocene Vinylidene Fragment [Cp*2TiCCH2]. Formation of Methylenetitanacyclobutenes and Vinyltitanium Acetylides. Crystal and Molecular Structures of Cp*2TiCR‘CR‘‘CCH2 (R‘ = R‘‘ = CH3; R‘ = SiMe3, R‘‘ = C6H5) and Cp*2Ti(CHCH2)(C⋮CPh)

Beate Ganter

Papers

Convenient synthesis of K[(C5H4MeMnH(CO)2] and reactions with Cl2B[N(SiMe3)2] and B2R2Cl2 (R = Me2N, Me3C)

Asymmetric hydrovinylation of styrene applying cationic allyl palladium complexes of a P-chiral ligand

A New Concept for Chelate Ligands with Planar Chirality

Diboran(4)yl Groups as Ligands to Transition Metals

Reactivity of Acetylenes toward the Titanocene Vinylidene Fragment [Cp2TiCCH2]. Formation of Methylenetitanacyclobutenes and Vinyltitanium Acetylides. Crystal and Molecular Structures of Cp2TiCR‘CR‘‘CCH2 (R‘ = R‘‘ = CH3; R‘ = SiMe3, R‘‘ = C6H5) and Cp*2Ti(CHCH2)(C⋮CPh)