Catalytic Reduction of Nitroarenes by Dipalladium Complexes: Synergistic Effect

Abstract

The direct reaction between 2,7-bis(2-pyridinyl)-1,8-naphthyridine (bpnp) and Pd(CH 3 COO) 2 in CF 3 COOH yields the new dinuclear palladium(II) complex [Pd 2 (bpnp)(μ-OH)(CF 3 CO 2 ) 2 ](CF 3 CO 2 ) (1). Similarly, substitution of Pd(CH 3 CN) 4 (BF 4 ) 2 with bpnp in DMF gives [Pd 2 (bpnp)(μ-OH)(DMF) 2 ](BF 4 ) 3 (2). Treatment of 1 or 2 with Cl − readily provide the chloro-substituted species [Pd(bpnp)(μ-OH)(Cl) 2 ] + . All complexes were characterized by spectroscopic methods, and the structure of 2 was further confirmed by X-ray crystallography. Complex 1 is an efficient catalyst for the reduction of aromatic nitro compounds leading to the corresponding aniline derivatives under atmospheric pressure of hydrogen at 50 °C. The mechanistic pathway of the catalysis is investigated. From the reaction pathway, it is suggested that a facile condensation of nitroso and hydroxylamine intermediates is enabled by the dipalladium system and the desired transformation proceeds smoothly under mild reaction conditions to yield the reduced product.

Magnetic nanoparticle‐tethered Schiff base–palladium(II): Highly active and reusable heterogeneous catalyst for Suzuki–Miyaura cross‐coupling and reduction of nitroarenes in aqueous medium at room temperature

“…Reaction solvent, temperature, time and yield are the important factors in view of efficiency. As is evident from Table , the reported catalysts require various organic solvents, high temperature, longer reaction time and low yield for nitroarene reduction …”

Synthesis, Characterization, and Catalytic Activities of Palladium Complexes with Phenylene-Bridged Bis(thione) Ligands

“…Apart from hydrogen, sodium borohydride (NaBH 4 ) reducing agent has been widely used, allowing efficient reduction of nitroarenes to anilines when used in combination with metal catalysts . Palladium-based catalysts, both coordination complexes and supported by polymer, metal–organic framework, nanohybrid, or nanoparticles, are all good candidates for the hydrogenation of nitroarenes due to their efficient catalytic performance. − However, there are few reports on palladium complexes bearing thione ligands for the reduction of nitro compounds. Continuing our research interests in organochalcogen metal complexes for their rich chemistry, we prepared palladium–thione complexes to study their versatile structural chemistry and catalytic activities.…”

Synthesis of water soluble Pd‐Piperidoimidazolin‐2‐ylidene complexes and their catalytic activities in neat water

“…The Pd complexes are effective catalysts for the reduction of nitroarenes . However, to the best of our knowledge, the catalytic properties of PEPPSI‐type Pd (II)NHC complexes on the reduction of nitro compounds is yet to be explored.…”

“…The reduction of nitroarenes is also an important process since the products of aromatic amines bearing groups, such as chloro‐, carbonyl, cyano are important intermediates in the synthesis of chemicals . They form the basis of multi‐component agricultural chemicals, medicines, natural products, polymers, liquid crystals and ligands . Studies to develop catalytic systems that perform in a short time at room temperatures using low catalyst loading is an ongoing effort.…”