Rational Design of Sterically Hindered and Unsymmetrical N py N im O ph Pincer‐Type Ligands and Their Palladium(II) Complexes: Catalytic Applications in Suzuki–Miyaura Reaction and Allylation of Aldehydes

Well Defined Phosphine Free Ni-Catalyzed Dehydrogenation of Secondary Alcohols for the Synthesis of Ketones and Ketazines

In this work, we unveil a novel synthesis of bench stable Ni (II) complexes supported by tetradentate Schiff-base ligands and the complexes were devoid of any phosphine or phosphine-based ligand. These Ni-complexes were successfully applied for the dehydrogenation of secondary alcohols for ketone and ketazine syntheses. Secondary alcohols with different functional groups were well tolerated during catalytic cycle. Moreover, we successfully extended this protocol for the synthesis of biologically significant ketones and ketazines. On the basis of various control experiments, probable reaction pathway was proposed, and an acceptorless alcohol dehydrogenation mechanism was suggested.

One-Pot Synthesis of 1, 2-Dihydro [1,2,4] Triazinium Salt by Copper-Assisted Unprecedented Cyclization Reaction: Applications in DNA and Protein Interaction Studies

Copper catalyzed intramolecular annulation of 2-((2-benzylidene-1-phenylhydrazineyl)methyl)pyridine derivatives was described. It was found that Cu(II) is reduced under the reaction condition to Cu(I). Synthesized 1,2-dihydro [1,2,4] triazinium salt showed fluorescence activity in the solid state. On treating with base, an instant increase in fluorescence was observed. A detailed physicochemical assessment underscored the robust DNA-binding capabilities of the [1,2,4]triazinium cationic species (C1-C3) via intercalative mechanisms. Notably, binding assays with BSA accentuated the heightened nucleic acid affinity of these cationic species.

Selective Formation of Mononuclear Palladium and Acetonitrile-Bridged Dinuclear Palladium Complexes Containing a Chiral Tridentate Ligand

From the chiral Schiff base tridentate ligand L_Ph, unusual acetonitrile-bridged dinuclear palladium complex 1 and organopalladium complex 1' were synthesized selectively by using acetonitrile and ethanol, respectively. The chiral tridentate Schiff base ligand was bound to the palladium metal center with different chelation modes ([ONO] for 1 and [CNO] for 1'). Complex 1 constitutes the first example of dinuclear metal complexes connected only by a bridging acetonitrile, in which an exceptionally short C≡N bond distance [0.945(12) Å] of bridged acetonitrile was observed. To study the influence of a phenyl group attached to an imine, the phenyl-free ligand L_H was prepared and used. In that case, an acetonitrile bridge was not observed. Theoretical calculation studies supporting the formation of 1 and 1' are favored.

Ferrocenyl palladacycles derived from unsymmetrical pincer-type ligands: evidence of Pd(0) nanoparticle generation during the Suzuki-Miyaura reaction and applications in the direct arylation of thiazoles and isoxazoles

A new family of ferrocenyl-palladacycle complexes Pd(L¹)Cl (Pd1) and Pd(L²)Cl (Pd2) were synthesized and characterized by UV-visible, IR, ESI-MS, and NMR spectral studies. The molecular structures of Pd1 and Pd2 were determined by X-ray crystallographic studies. Palladacycle catalyzed Suzuki-Miyaura cross-coupling reactions were investigated utilizing the derivatives of phenylboronic acids and substituted chlorobenzenes. Mechanistic investigation authenticated the generation of Pd(0) nanoparticles during the catalytic cycle and the nanoparticles were characterized by XPS, SEM and TEM analysis. Direct C-H arylation of thiazole and isoxazole derivatives employing these ferrocenyl-palladacycle complexes was examined. The reaction model for the arylation reaction implicating the in situ generation of Pd(0) nanoparticles was proposed.