SPECTROPHOTOMETRIC, POLAROGRAPHIC AND CONDUCTOMETRIC EVIDENCE FOR TRIPLE ION FORMATION FROM BENZENESULFONATE AND DIPHENYL PHOSPHATE SALTS IN PROTOPHOBIC APROTIC-SOLVENTS
M. Hojo et al., SPECTROPHOTOMETRIC, POLAROGRAPHIC AND CONDUCTOMETRIC EVIDENCE FOR TRIPLE ION FORMATION FROM BENZENESULFONATE AND DIPHENYL PHOSPHATE SALTS IN PROTOPHOBIC APROTIC-SOLVENTS, Electrochimica acta, 39(5), 1994, pp. 629-638
The formation of triple cations (C6H5SO3-(Li+)2) in acetonitrile was s
hown by re-resolution of C6H5SO3Li precipitate with the addition of a
large excess of LiClO4 to tetraethylammonium benzenesolfonate (Et4N C6
H5SO3). The conductivities of tributylammonium benzenesulfonate in ben
zonitrile and nitrobenzene were explained by symmetrical triple ion fo
rmation (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 car
bonate with the high dielectric constant (epsilon(r) = 64.4 at 25-degr
ees-C). The present study and a recalculation of previous work have sh
own 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.