2 research outputs found
One-Pot Synthesis of Au<sub>11</sub>(PPh<sub>2</sub>Py)<sub>7</sub>Br<sub>3</sub> for the Highly Chemoselective Hydrogenation of Nitrobenzaldehyde
In this study, the gold clusters
Au<sub>11</sub>(PPh<sub>3</sub>)<sub>7</sub>Cl<sub>3</sub> and Au<sub>11</sub>(PPh<sub>2</sub>Py)<sub>7</sub>Br<sub>3</sub> (PPh<sub>2</sub>Py = diphenyl-2-pyridylphosphine)
are synthesized via a one-pot procedure based on the wet chemical
reduction method. The Au<sub>11</sub>(PPh<sub>3</sub>)<sub>7</sub>Cl<sub>3</sub> cluster is found to be active in the chemoselective
hydrogenation of 4-nitrobenzaldehyde in the presence of hydrogen (H<sub>2</sub>) and a base (e.g., pyridine). Interestingly, the cluster
with the functional ligand PPh<sub>2</sub>Py shows similar activity
without losing catalytic efficiency in the absence of the base. The
structure of the gold clusters and reaction pathway of the catalytic
hydrogenation are investigated at the atomic/molecular level via UV–vis
spectroscopy, electrospray ionization (ESI) mass spectrometry, and
density functional theory (DFT) calculations. It is found that one
ligand (PPh<sub>3</sub> or PPh<sub>2</sub>Py) removal is the first
step to expose the core of the gold clusters to reactants, providing
an active site for the catalytic reaction. Then, the H–H bond
of the H<sub>2</sub> molecule becomes activated with the aid of either
free amine (base) or ligand PPh<sub>2</sub>Py which is attached to
the gold clusters. This work demonstrates the promise of the functional
ligand PPh<sub>2</sub>Py in the catalytic hydrogenation to reduce
the amount of materials (free base: e.g., pyridine) that ultimately
enter the waste stream, thereby providing a more environmentally friendly
reaction medium
Nickel-Catalyzed Direct Thiolation of C(sp<sup>3</sup>)–H Bonds in Aliphatic Amides
Nickel-catalyzed thiolation of the
inactivated methyl CÂ(sp<sup>3</sup>)–H bonds of aliphatic amides
with disulfide is described.
It is a novel strategy for the synthesis of thioethers with the ultimate
goal of generating thioether carboxylic acids with various functional
groups