Synthesis, characterization and X-ray structures of the model ligand for a coordination polymer: diethyl-2,6-pyridine dicarboxamide and its complex with PdCl2

The reaction of 2,6-dicarboxylic acid dichydrochloride in dry toluene with EtNH2 in KOH affords the title compound (I). It is a model ligand to mimic the polymer repeat unit to establish the site of metal coordination to polymer support. The central part of the molecule constitutes of a pyridine ring with two side chains forming an inner cavity with two hydrogen amide atoms pointing towards the cavity. The pyridine nitrogen atom completes the third potential binding site. The carbonyl groups are directed outside of the inner cavity. The reaction of I with a stoichiometric amount of dichlorobis (benzonitrile) palladium in CH2Cl2 affords the [bis(diethyl-2,6-pyridine dicarboxamide)Pd2Cl6]·2HCl (II). Compounds I and II were fully characterized by spectroscopic techniques and also by X-ray diffraction analysis.