Platinum N‐Heterocyclic Carbene Nanoparticles as New and Effective Catalysts for the Selective Hydrogenation of Nitroaromatics

Abstract

Dedicated to Professor Ernesto Carmona on the occasion of his 65 th birthday.Abstract: In this communication, we report the first synthesis of Pt NPs stabilized with NHC ligands and their investigation as catalysts in the chemoselective hydrogenation of nitroarenes. The results in catalysis show that by a proper choice of the NHC stabilizer and the adjustment of the NHC/metal ratio, these NHC-capped Pt NPs exhibit high levels of activity and selectivity in the hydrogenation reactions. In particular, Pt NPs stabilized with 2 equiv. of IPr carbene (PtIPr 0.2 ) catalyze the chemoselective reduction of a series of functionalized nitroarenes under mild conditions (1 bar H 2 , 308C). This catalyst tolerates the presence of a range of functional groups including hydroxyl, benzyloxy, carbonyl and olefinic moeities as well as halogens.

Controlled metal nanostructures: Fertile ground for coordination chemists

“…Ti NPs [138], and the use of carbene ligands to control the size of Pt [139] or Ru NPs [87,[140]. Weakly coordinating alcohols [141], [142] or carbohydrates like cyclodextrines [143] can also serve as stabilizers, as well as some solvents such as organic carbonates [144], ionic liquids [145], [146], [147], [148], or polyols [149], [150].…”

Highly Stable Water‐Soluble Platinum Nanoparticles Stabilized by Hydrophilic N‐Heterocyclic Carbenes

“…The strategy presented herein uses sulfonated N-heterocyclic carbene (NHC) ligands to stabilize platinum nanoparticles (PtNPs) in water, under air, for an indefinite time period. [4][5][6][7][8][9][10][11][12][13] Some of us have characterized the coordination of such ligands to ruthenium nanoparticles by solid-state NMR spectroscopy. Solidstate NMR studies showed coordination of the carbene ligands to the nanoparticle surface and allowed the determination of a 13 C-195 Pt coupling constant for the first time in a nanosystem (940 Hz).…”

“…[1] The agglomeration of MNPs can be avoided by coordinating ligands to their surface. [4][5][6][7][8][9][10][11][12][13] Some of us have characterized the coordination of such ligands to ruthenium nanoparticles by solid-state NMR spectroscopy. [3] Surprisingly, the stabilization of MNPs with NHC ligands and, more specifically, the interaction between the metal surface and the NHC ligand, have rarely been studied.…”

“…[4][5][6][7][8][9][10][11][12][13] Some of us have characterized the coordination of such ligands to ruthenium nanoparticles by solid-state NMR spectroscopy. We recently described the behavior of RuNPs as catalysts for the hydrogenation of arenes [5] and the synthesis of PtNPs as chemoselective catalysts for the hydrogenation of aromatic nitro compounds, [12] both stabilized by bulky NHCs. Additionally, NHCs have been used to synthesize Au [9,10] and Ag [11] MNPs as model systems for the formation of either conglomerates or 3D networks.…”

The hydrogenation of nitroarenes mediated by platinum nanoparticles: an overview

“…55 Platinum nanoparticles were synthesized by decomposition of [Pt(dba) 2 ] in THF at room temperature under 3 bar of H 2 and in the presence of variable amounts (0.2 or 0.5 equiv.) 55 Platinum nanoparticles were synthesized by decomposition of [Pt(dba) 2 ] in THF at room temperature under 3 bar of H 2 and in the presence of variable amounts (0.2 or 0.5 equiv.)…”