Inclusion Compounds of Some Charge-Transfer Complexes

The charge-transfer complex of benzidine and tetracyano-p-quinodimethane has been shown to form an inclusion compound with certain molecules such as dichloromethane, dibromomethane and acetone. The molecular volumes of these guest substances are all smaller than 75 cm3/mol, while the substances which are not included have a molecular volume larger than 80 cm3/mol. Besides the size, the molecular shape is also considered to be a primary factor for the formation of the inclusion compound. The heat of formation of the inclusion compound with dichloromethane as a guest was determined to be 11.1±1 kcal per mole of the guest substance by the thermochemical measurements. Similar inclusion compounds were also obtained, when 3,3′-diaminobenzidine, 3,3′-dichlorobenzidine and o-tolidine were used in place of benzidine.