1,8-Bis(N-benzyl-N-methylamino)naphthalene ( 2) and its hy-the free base 2 is 0.6 (± 0.07) kcal•mol -1 less stable than the dl form (∆H°= -0.64 (±0.03) kcal•mol -1 ; ∆S°= -0.18 (±0.13) drogen iodide salt [2H] + [I] -were synthesised from 1,8-diaminonaphthalene. The thermodynamic diastereomer ratios of (2) cal•K -1 mol -1 ) and the activation barriers for interconversion are ca. 14.2 (±0.4) and 14.8 (±0.4) kcal•mol -1 respectively. The and [2H] + in [D 7 ]DMF are 73.4:26.6 and 89.7:10.3 respectively at 293 K. The solid state structures of the major dl-(R N R N /S N S N ) effect of solvent polarity on the entropy and enthalpy change on approach to the transition state was studied. An diastereomers were determined by single crystal X-ray diffraction. The minor diastereomers were shown to be the approximate correlation with the solvent dielectric constant was found for both ∆H ‡ and ∆S ‡ and this may be ascribed to meso-(R N S N ) forms by performing 1 H-NMR NOE studies on isotopically desymmetrized 1-(N-benzyl-N-[ 13 C]-methylami-the development of a net dipole in the transition state due to substantially different hybridisation and geometry at the two no)-8-(NЈ-benzyl-NЈ-methylamino)naphthalene [ 13 C]-2 and the salt [ 13 C]-[2H] + . In [D 7 ]DMF at 298 K, the meso form of nitrogen centres.