Complexes of the “proton sponge” 1,8-bis(dimethylamino)naphthalene (DMAN): Part 5. The structure at 100 K of [DMANH] +·[dihydrogen hemimellitate] − hemihydrate

Abstract

Crystallisation of the “proton sponge” 1,8-bis(dimethylamino)naphthalene (DMAN) in the presence of hemimellitic acid (1,2,3-benzenetricarboxylic acid, BTA) resulted in the salt [DMANH] +·[BTA] −· 1 2 H 2O. The structure analysis was performed at liquid nitrogen temperature (100 K). The space group is C2/c with Z = 8. The cell dimensions are: a = 20.085(1), b = 8.557(1), c = 25.429(1) Å, β = 105.01(1)°, V = 4221.3(6) Å 3. The structure was solved by direct methods and refined to R = 0.0363 for 4131 unique reflections with I ⩾ 2.5σ( I). The proton sponge DMAN accepts a proton from one of the carboxyl groups of BTA with the formation of a strong intramolecular hydrogen bond. Electron-density difference maps in the plane of this [NH⋯N] + hydrogen bond reveal a disordering of the hydrogen atom in a 70:30 ratio over two positions at distances of approximately 0.9 Å from the pertaining nitrogen atoms. The water molecule is disordered over two positions at distances of 1.203(3) Å from the twofold axis.