Unusual coordination of a 1,2,3-triazolyl-pyridine ligand in a Pd() complex: application in the Suzuki-Miyaura coupling reaction

• Published in: New journal of chemistry 2023-04, Vol.47 (14), p.6871-6879
• Main Authors: Gahlaut, Puneet Singh, Gautam, Deepak, Lama, Prem, Jana, Barun
• Format: Article
• Language: English
• Subjects: Acetonitrile; Catalysts; Chelation; Chemical reactions; Coordination compounds; Coupling (molecular); Ethanol; Ligands; Molecular structure; Nitrogen; Palladium; Pyridines; Single crystals; Transition metal compounds
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d3nj00206c

A modified "click" reaction between 2-azidopyridine and di(prop-2-yn-1-yl)phthalate [dpp] ( 2 ) produces a novel bis(1,2,3-triazolyl-pyridine) ligand on an ortho -phthalic acid platform [bptmp] ( 3 ). The [bptmp] ligand is prepared to produce transition metal complexes through selective N-3 coordination of the inverse triazolyl-pyridine ligand. An equimolar reaction between [bptmp] ( 3 ) and PdCl 2 (CH 3 CN) 2 in acetonitrile leads to the isolation of a light-yellow solid ( 4 ). Several spectroscopic and spectrometry data established that the formed complex has a molecular formula of PdCl 2 [bptmp] ( 4 ). Molecular structure determination using a single crystal X-ray diffraction study further established the formation of a 1 : 1 metal-ligand complex, where PdCl 2 bridges the two side-arms of the phthalic acid platform. As per the design of [bptmp], in complex ( 4 ), the chelating bidentate triazolyl-pyridine units are not coordinated, whereas the N-3 nitrogen of the inverse triazolyl-pyridine selectively coordinated to Pd( ii ). Furthermore, complex ( 4 ) is proved to be a highly effective catalyst for the Suzuki-Miyaura coupling reaction in a water/ethanol solvent combination with very modest catalyst loading. The high reactivity of complex 4 in the catalytic Suzuki-Miyaura coupling reaction is attributed to the electronic and steric properties of the [bptmp] ligand. A modified "click" reaction between 2-azidopyridine and di(prop-2-yn-1-yl)phthalate [dpp] ( 2 ) produces a novel bis(1,2,3-triazolyl-pyridine) ligand on an ortho -phthalic acid platform [bptmp] ( 3 ).