Palladium(II) Complexes of the Thiosemicarbazone and N‐Ethylthiosemicarbazone of 3‐Hydroxypyridine‐2‐carbaldehyde: Synthesis,Properties, and X‐Ray Crystal Structure

Two novel, stable Pd^II complexes, compounds 3 and 4 , of two 3‐hydroxypyridine‐2‐carbaldehyde thiosemicarbazones, 1 and 2 , resp., were prepared from Li₂PdCl₄. The single‐crystal X‐ray structure of complex 3 (= [Pd( 2 )Cl]) shows that the ligand monoanion coordinates in a planar conformation to the metal via the pyridyl N‐, the imine N‐, and the thiolato S‐atoms. Intermolecular H‐bonds, π–π, and CH ? ? ? π interactions lead to a two‐dimensional supramolecular assembly. The electronic, IR, UV/VIS, and NMR spectroscopic data of the two complexes are reported, together with their electrochemical properties. A sophisticated experimental procedure was used to determine the multiple dissociation constants of the ligands 1 and 2 by UV/VIS titration.