The ß-Agostic Structure in (C5 Me5 )2 Sc(CH2 CH3 ): Solid-State NMR Studies of (C5 Me5 )2 Sc-R (R=Me, Ph, Et).

Multinuclear solid-state NMR studies of Cp*2 Sc-R (Cp*=pentamethylcyclopentadienyl; R=Me, Ph, Et) and DFT calculations show that the Sc-Et complex contains a ß-CH agostic interaction. The static central transition 45 Sc NMR spectra show that the quadrupolar coupling constants (Cq ) follow the trend of Ph≈Me>Et, indicating that the Sc-R bond is different in Cp*2 Sc-Et compared to the methyl and phenyl complexes. Analysis of the chemical shift tensor (CST) shows that the deshielding experienced by Cß in Sc-CH2 CH3 is related to coupling between the filled σC-C orbital and the vacant πSc⋯HC* orbital.

Cationic [(Iminophosphine)Nickel(Allyl)]+ Complexes as the First Example of Nickel Catalysts for Direct Hydroamination of Allenes.

The first example of nickel-catalyzed hydroamination of allenes is reported. The new cationic [(3-iminophosphine)nickel(allyl)]+ catalysts have been fully characterized and act regioselectively in the catalytic hydroamination of allenes with secondary amines at room temperature.

Solid-state 45Sc NMR studies of Cp*2Sc-X and Cp*2ScX(THF).

Cp*2Sc-X, where X is a halide, were synthesized and studied by solid-state 45Sc NMR to determine how the Sc-X bond affects quadrupolar NMR parameters. The experimental quadrupolar coupling constants (CQ) show that the fluoride has the largest coupling constant and that the iodide has the smallest coupling constant. DFT analysis of this data indicates that the CQ of these compounds is related to core scandium and halide orbitals, which is related to polarizability of the halide and the Sc-X distance. Cp*2ScX(THF) were also investigated by solid-state 45Sc NMR spectroscopy, and have much smaller CQ values than the base-free halides. This is related to the change in structure of the THF adduct and occupation of orbitals of π-symmetry that reduce CQ.

Selective hydrosilylation of alkynes and ketones: contrasting reactivity between cationic 3-iminophosphine palladium and nickel complexes.

The catalytic hydrosilylation of alkynes and ketones has been explored utilizing palladium- and nickel(allyl) complexes supported by 3-iminophosphine ligands. Palladium and nickel demonstrated distinctly different reactivity profiles, with palladium proving very effective for the hydrosilylation of electron-deficient alkynes, while nickel excelled with ketones and internal alkynes. Additionally, in many cases, regioselective hydrosilylation was observed.

High-Yield Production of Fatty Nitriles by One-Step Vapor-Phase Thermocatalysis of Triglycerides.

Fatty nitriles are widely used as intermediate molecules in the pharmaceutical and polymer industries. In addition, hydrogenation of fatty nitriles produces fatty amines that are common surfactants. In the conventional fatty nitrile process, triglycerides are first hydrolyzed and the resulting fatty acids are catalytically reacted with NH3 in a liquid-phase reaction. In this study, we report a simpler one-step fatty nitrile production method that involves a direct vapor-phase reaction of triglycerides with NH3 in the presence of heterogeneous solid acid catalysts. The reactions were performed in a tubular reactor maintained at 400 °C into which triglycerides were injected through an atomizer to allow rapid volatilization and reaction; NH3 was fed as a gas. Several metal oxide catalysts were tested, and reactions in the presence of V2O5 resulted in near-theoretical fatty nitrile yields (84 wt % relative to the feed mass). In general, catalysts with higher acidity such as V2O5, Fe2O3, and ZnO showed higher fatty nitrile yields compared to low acidity catalysts such as ZrO, Al2O3, and CuO. Energy balance calculations indicate that the one-step reaction described here would require significantly lower energy than the conventional process primarily because of the elimination of the energy-intense triglyceride hydrolysis.

Highly efficient regioselective hydrosilylation of allenes using a [(3IP)Pd(allyl)]OTf catalyst; first example of allene hydrosilylation with phenyl- and diphenylsilane.

A [(3IP)Pd(allyl)]OTf complex was shown to function efficiently and regioselectively in allene hydrosilylation with phenyl- and diphenylsilane. The catalyst also proved to be highly active for allene hydrosilylation employing a wide range of silanes, each of which produced a single regioisomer.