AB-INITIO STUDIES OF PROTON SPONGES - 1,8-BIS(DIMETHYLAMINO)NAPHTHALENE

The structures of 1,8-bis(dimethylamino)naphthalene and Its protonated forms have been determined by ab initio geometry optimization. The ti tle compound is found to possess C-2 symmetry in the gas phase, and th e N(C10H6)N fragment is markedly nonplanar. Protonation causes the mol ecule to become more planar, as it approaches (without quite attaining ) C-2 upsilon symmetry. Asymmetric protonation at one nitrogen is ener getically preferred to the symmetric N...H...N bridged form. The predi cted proton affinity is within a few kilojoules per mole of an experim ental value. The changes in structure and the electron distribution ar e discussed in terms of the topology of the charge density rho and of del(2) rho, for this and related amines.