ACIDITY OF DIBASIC CARBON ACIDS .5. THE 2ND ACIDITY CONSTANT OF 9,10-DIHYDRODIBENZ[ALPHA,H]ANTHRACENE IN TETRAHYDROFURAN-GEOMETRY, CHARGE-DISTRIBUTION OF DIANION, STRUCTURE OF DIMETALLIC SALTS

The second equilibrium ion pair acidity constant (pK(2)) of 9,10-dihyd rodibenz[a,h]anthracene (DBDHA, 1H(2)) with counter ions sodium (pK(2) 28.5) and potassium (pK(2) 30.4) has been determined in tetrahydrofur an (THF) at 298 K, This value is considerably lower than for other 9,1 0-dihydroanthracene derivatives. Disodium,dipotassium and dirubidium s alts of DBDHA, i.e, 1(2-), exist as contact ion triplets in THF at 298 K, although the dilithium salt behaves as a solvent-separated ion tri plet under the same conditions, In the dianion of DBDHA (1(2-)) the ne gative charge is displaced from the deprotonated carbon atoms towards the outer benzene rings.