Synthesis and characterization of cationic cyclopalladated complexes derived from p-tert-butyl-calix[4]arene bisphosphite with nitrogen donors

A series of new cationic cyclopalladated complexes 2–6 have been synthesized from neutral cyclopalladated complex 1 of p-tert-butyl-calix[4]arene bisphosphite with various nitrogen donor ligands (acetonitrile, pyridine, aniline, (R)-(+)-1-phenylethylamine and 4,4′-bipyridine) in presence of Ag(OSO2CF3) as a chloride scavenger. These cationic cyclopalladated complexes have been characterized by NMR spectroscopy. Single crystal X-ray diffraction studies performed on cationic cyclopalladated complexes 3 and 6 in solid state reveal nearly square planar geometry around the metal and distorted cone conformation of the calix[4]arene framework. These cationic cyclopalladated complexes based on hetero ligands having variable steric and electronic properties could be efficient catalysts for important organic transformation reactions.