Hydrogenolysis of haloboranes: from synthesis of hydroboranes to formal hydroboration reactions.

Hydroboranes are versatile reagents in synthetic chemistry, but their synthesis relies on energy-intensive processes. Herein, we report a new method for the preparation of hydroboranes from hydrogen and the corresponding haloboranes. Triethylamine (NEt3) form with dialkylchloroboranes a Frustrated Lewis Pair (FLP) able to split H2 and afford the desired hydroborane with ammonium salts. Unreactive haloboranes were unlocked using a catalytic amount of Cy2BCl, enabling the synthesis of commonly used hydroboranes such as pinacolborane or catecholborane. The mechanisms of these reactions have been examined by DFT studies, highlighting the importance of the base selection. Finally, the system's robustness has been evaluated in one-pot B-Cl hydrogenolysis/hydroboration reactions of C=C unsaturated bonds.

Tantallacyclopentadiene as a unique metal-containing diene ligand coordinated to nickel for preparing tantalum-nickel heterobimetallic complexes.

A mononuclear tantallacyclopentadiene complex, TaCl3(C4H2tBu2) (3), serves as a unique ligand to nickel: the addition of Ni(COD)2 to 3 selectively afforded heterobimetallic Ta-Ni complex 4. The cyclooctadiene ligand bound to the nickel center in complex 4 was readily substituted by monodentate and bidentate phosphine ligands, such as dimethylphenylphosphine, 1,2-bis(diphenylphosphino)ethane, and 1,2-bis(diethylphosphino)ethane, to give the corresponding phosphine complexes 5, 6a, and 6b. We also examined a ligand substitution reaction with 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) to produce the corresponding Ta-Ni complex 7. These newly prepared Ta-Ni heterobimetallic complexes were characterized spectroscopically together with the crystal structures of 4, 6a, and 7.

Nickel-catalysed hydroalkoxylation reaction of 1,3-butadiene: ligand controlled selectivity for the efficient and atom-economical synthesis of alkylbutenyl ethers.

The nickel-catalysed hydroalkoxylation of butadiene is promoted by a nickel(0)/dppb catalyst (dppb = 1,4-bis(diphenylphosphino)butane; see scheme). By following this new synthetic procedure, alkylbutenyl ethers are readily obtained from an alcohol and 1,3-butadiene with exclusion of dimerisation and telomerisation products.