Kinetic studies of the reactions of O,O-diphenyl Z-S-aryl phosphorothioates with X-benzylamines have been carried out in dimethyl sulfoxide at 55.0 $^{circ}C$. The Hammett (log $k_2$ vs ${sigma}_X$) and Bronsted [log $k_2$ vs $pK_a(X)$] plots for substituent X variations in the nucleophiles are biphasic concave downwards with a maximum point at X = H, and the unusual positive ${ ho}_X$ and negative ${eta}_X$ values are obtained for the strongly basic benzylamines. The sign of the cross-interaction constant (${ ho}_{XZ}$) is negative for both the strongly and weakly basic nucleophiles. Greater magnitude of ${ ho}_{XZ}$ value is observed with the weakly basic nucleophiles (${ ho}_{XZ}$ = -2.35) compared to with the strongly basic nucleophiles (${ ho}_{XZ}$ = -0.03). The deuterium kinetic isotope effects ($k_H/k_D$) involving deuterated benzylamines [$XC_6H_4CH_2ND_2$] are primary normal ($k_H/k_D$ > 1). The proposed mechanism is a concerted $S_N2$ involving a frontside nucleophilic attack with a hydrogen bonded, four-center-type transition state for both the strongly and weakly basic nucleophiles. The unusual positive ${ ho}_X$ and negative ${eta}_X$ values with the strongly basic benzylamines are rationalized by through-space interaction between the ${pi}$-clouds of the electron-rich phenyl ring of benzylamine and the phenyl ring of the leaving group thiophenoxide.