Synthesis and spectroscopic structural investigations of the charge-transfer complexes formed in the reaction of 2,6-diaminopyridine with π-acceptors TCNE, chloranil, and DDQ

Molecular charge-transfer complexes of the donor 2,6-diaminopyridine (2,6-DAPY) with π-acceptors tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tetrachloro-p-benzoquinone(chloranil) were studied spectrophotometrically in chloroform at room temperature. All formed complexes exhibit well resolved charge-transfer bands in the regions where neither donor nor acceptors have any absorption. The stoichiometries of the reactions were determined from photometric titration methods. The results obtained show the formed CT complexes have the structures [(2,6-DAPY)(TCNE)3], [(2,6-DAPY)(DDQ)2], and [(2,6-DAPY)(chloranil)]. These three complexes were isolated as solids and further characterized by elemental analysis and infrared measurements.