A H-1, C-13 and N-15 NMR investigation of three substituted DMAN derivatives and their monoprotonated salts

We report a H-1, C-13 and N-15 NMR investigation of one symmetrically subst ituted 2,7-dichloro and two unsymmetrically substituted 2-chloro and 4-brom o DMAN [1,8-bis(dimethylamino)naphthalene] proton sponges and their protona ted salts. From a consideration of the NMR data reported we conclude, that the most sensitive parameters for investigating compounds of this kind are (1)J(N-15-H-1) and N-15 and H-1 chemical shifts for the nuclei in the [N-8- H-N1](+) bridge. A further significant NMR parameter is (3)J(H-1-H-1) for t he bridging proton and the N(CH3)(2) protons. An analysis of the values of (1)J (N-15-H-1) for the studied compounds is consistent with the view that in the investigated system equilibrium between two tautomeric forms occurs. A study at temperatures between 27 and -40 degrees C, and a change of solv ent, show that the values of the N-15 chemical shifts and couplings (1)J (N -15-H-1) and (3)J (H-1-H-1) for the [N8-H-N1](+) bridge are essentially unc hanged. This shows that the bonding arrangements of the bridge atoms are st able under these experimental conditions. Copyright (C) 2000 John Wiley & S ons, Ltd.