CORRELATION OF THERMODYNAMIC STABILITIES OF CHARGE-TRANSFER COMPLEXES OF ANTHRACENE AND CHLORANIL WITH THOSE OF TETRA-CYANOETHYLENE

The formation constants of charge-transfer complexes of a number of 9- and 9,10-substituted anthracenes with chloranil have been measured by a spectrophotometric method and the corresponding thermodynamic parameters ΔG°c, ΔH°c and ΔS°c evaluated in various solvents. vmax values of the chargetransfer band for chloranil were linearly related to those for tetracyanoethylene (TCNE). Good correlations were also obtained between vmax and the corresponding ionisation potentials Ip of the donor molecules. In addition ΔG°c varied linearly with Ip and from these correlations, values of ΔG°c, etc. for the corresponding TCNE complexes could be calculated. These values are otherwise very difficult to obtain due to the high reactivity of TCNE. © 1979.