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-Nnitrosocarbamate 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) Å, b = 5.877(3) Å, c = 15.757(7) Å, α = 90°, β = 110.019(7)°, γ = 90°, V = 1696.5(12) Å, 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 carbonyl oxygen (O1) and the hydrogen atom at the trialkylammonium center (H3n), with a distance between them of 2.37 Å. DFT calculations on the cation (B3LYP/6-31+G(d)) confirm that the hydrogen bond stabilized gauche conformation is the global minimum structure.