Pressure effect on the eda-complexes formed between mesitylene, hexamethylbenzene and tetracyanoethylene in carbon tetrachloride

The intermolecular charge transfer spectra of tetracyanoethylene with mesitylene and hexamethylbenzene have been measured in carbon tetrachloride under high pressures up to 1400kg/cm^2 at 25℃. Both the equilibrium constants for the formation of EDA-complexes and their molar absorption coefficients were increased with pressure. The values of the volume change for the formation of the complexes were -7.1 and -14.1 cm^3/mole for mesitylene-TCNE and HMB-TCNE complexes, respectively. For mesitylene-TCNE complex, the red shift of the absorption maximum was observed with increasing pressure. On the other hand, HMB-TCNE complex showed the red shift at first and turned to the blue shift with higher pressure