The Tetrafluoroborate Salt of 4-Methoxybenzyl N-2-(dimethylamino)ethyl-N-nitrosocarbamate: Synthesis, Crystal Structure and DFT Calculations

The tetrafluoroborate salt of 4-methoxybenzyl N-2-(dimethylamino)ethyl-N-nitrosocarbamate was prepared in two steps, via the corresponding carbamate. Its crystal structure is monoclinic, space group P21/c. The unit cell dimensions are: a = 19.499(8) A ˚ , b = 5.877(3) A ˚ , c = 15.757(7) A ˚ , a = 90, b = 110.019(7), c = 90, V = 1696.5(12) A ˚ 3 , Z = 4. The structure exhibits an unexpected, pseudo-gauche conformation with respect to the C2-C3 bond, due to a stabilizing hydrogen bond between the car- bonyl oxygen (O1) and the hydrogen atom at the trialky- lammonium center (H3n), with a distance between them of 2.37 A ˚ . DFT calculations on the cation (B3LYP/6-31 ? G(d)) confirm that the hydrogen bond stabilized gauche conformation is the global minimum structure.