H-1-Nmr Study Of Ternary Platinum(Ii) Complexes With N-(1-Naphtyl)Methyl-1,2-Ethanediamine Or N-(9-Anthrylmethyl)-1,2-Ethanediamine And Bipyridine Or Phenanthroline And Restricted Single Bond Rotation Due To Aromatic-Aromatic Ring Interaction

H-1-NMR spectra of square-planar complexes with the formula [Pt(L-1)(L-2)]X-2 where L-1 is 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) and L-2 is N-(1-naphthyl)methyl-1,2-ethanediamine (Npen) or N-(9-anth ryl)methyl-1,2-ethanediamine (Aten) indicate that the N-naphthylmethyl and N-anthrylmethyl groups are forced to adopt a pseudo axial disposition due to intramolecular repulsion of hydrogen atoms of the aromatic diimines. The aromatic-aromatic interactions in the N-arylmethyl-1,2-ethanediamine complexes and aromatic diimines caused them to undergo intramolecular stacking. H-1-NMR spectra of these complexes showed a significant concentration and temperature dependence. The monomer-dimer equilibrium was estimated, based on the concentration dependency. Restricted single bond rotation was estimated from temperature dependency data. The rotation of the anthracene ring of the [Pt(bpy)(Aten)](2+) complex showed an activation energy of ca. 38 kJ mol(-1), which is in good agreement with a mechanism involving successive rotations about single bonds with restriction by intramolecular aromatic-aromatic ring interactions.