Huaifeng Li

Selective Hydrogen Generation from Formic Acid with Well-Defined Complexes of Ruthenium and Phosphorus–Nitrogen PN3-Pincer Ligand

An unsymmetrically protonated PN(3) -pincer complex in which ruthenium is coordinated by one nitrogen and two phosphorus atoms was employed for the selective generation of hydrogen from formic acid. Mechanistic studies suggest that the imine arm participates in the formic acid activation/deprotonation step. A long life time of 150 h with a turnover number over 1 million was achieved.

C–S Cross-Coupling Reactions Catalyzed by Recyclable Core-Shell Structured Copper/Cu2O Nanowires Under Ligand-Free Conditions

Core-shell structured Cu/Cu2O nanowires were demonstrated as efficient catalysts for C–S cross-coupling reactions. The excellent coupling activity over Cu/Cu2O nanowires on a diverse set of aryl iodides and thiols is attributed to the synergetic effect of the special core-shell structures and their advanced spatial configuration.

Conversion of CO2 from air into formate using amines and phosphorus-nitrogen PN3P-Ru(II) pincer complexes

Well-defined ruthenium(II) PN3P pincer complexes were developed for the hydrogenation of carbon dioxide. Excellent product selectivity and catalytic activity with TOF (turnover frequency) and TON (turnover number) up to 13 000 h−1 and 33 000, respectively, in a THF/H2O biphasic system were achieved. Notably, effective conversion of carbon dioxide from air into formate was conducted in the presence of an amine, allowing easy product separation and catalyst recycling.

Cobalt-Catalyzed Selective Hydrogenation of Nitriles to Secondary Imines

The first example of cobalt-catalyzed selective hydrogenation of nitriles to secondary imines is reported. The results demonstrate the significantly different selectivity compared with the previously reported cobalt catalytic system during the nitrile hydrogenation. A variety of aromatic and aliphatic nitriles are hydrogenated to the corresponding secondary imines.

A Pseudo-Dearomatized PN3P*Ni-H Complex as a Ligand and σ-Nucleophilic Catalyst

In contrast to the conventional strategy of modifying the reactivities and selectivities of the transition metal and organocatalysts by varying the steric and electronic properties of organic substituent groups, we hereby demonstrate a novel approach that the sigma (σ) nucleophilicity of the imine arm can be significantly enhanced in a pseudodearomatized PN3P* pincer ligand platform to reach unprecedented N-heterocyclic carbene-like reactivity. Accordingly, the imine arm of the PN3P*Ni-H pincer complex efficiently catalyzes the hydrosilylation of aldehydes, cycloaddition of carbon dioxide (CO2) to epoxides, and serves as a ligand in the Ru-catalyzed dehydrogenative acylation of amines with alcohols.