SPECTROPHOTOMETRIC, POLAROGRAPHIC AND CONDUCTOMETRIC EVIDENCE FOR TRIPLE ION FORMATION FROM BENZENESULFONATE AND DIPHENYL PHOSPHATE SALTS IN PROTOPHOBIC APROTIC-SOLVENTS

The formation of triple cations (C6H5SO3-(Li+)2) in acetonitrile was shown by re-resolution of C6H5SO3Li precipitate with the addition of a large excess of LiClO4 to tetraethylammonium benzenesolfonate (Et4N C6H5SO3). The conductivities of tributylammonium benzenesulfonate in benzonitrile and nitrobenzene were explained by symmetrical triple ion formation (M2X+ and MX2-) in addition to ion pair formation (MX), while in acetonitrile by ion pair formation alone. Tributylammonium diphenyl phosphate (n-Bu3NH(PhO)2PO2) formed triple ions even in propylene carbonate with the high dielectric constant (epsilon(r) = 64.4 at 25-degrees-C). The present study and a recalculation of previous work have shown that the association of R3NH+ X- (R = Et or n-Bu) in benzonitrile increases in the following order: NO3- < C6H5SO3- < p-toluenesulfonate < CH3SO3-, while the K(a) values by the Shedlovsky analysis increase in the opposite order.