Regiospecific cyclometallation: Synthesis, spectral properties and crystal structure of peri-palladate

At room temperature 1-(2′-hydroxy-5′-methylphenylazo)naphthalene (H2L) reacts with disodium tetrachloropalladate in ethanol and undergoes cyclopalladation leading to the formation of the pink monomeric compound [PdL(Pic)] (1) in the presence of 4-picoline (Pic). The structure of 1 has been determined by single crystal X-ray crystallography. The metal ion is in a distorted square planar CNON coordination sphere. The palladium(II)–carbon bond formation occurs exclusively at the C8 (peri-) position of the naphthyl ring of H2L. 1-(2′-hydroxy-5′-methylphenylazo)naphthalene behaves as a dianionic terdentate [C8(naphthyl), N(diazo), O(phenolato)] ligand towards palladium(II). The peri-palladate 1 has also been characterized by spectral (IR, electronic, 1H and 13C{1H} NMR) data.

Graphical abstractAt room temperature naphthylazophenol undergoes regiospecific palladation at the peri-position of the naphthyl ring and binds palladium(II) as a dianionic terdentate ligand. The spectral properties and crystal structure of the peri-palladate have been described.Figure optionsDownload full-size imageDownload as PowerPoint slide