Synthesis of [35]Adamanzane, 1,5,9,13-Tetraazabicyclo [7.7.3]nonadecane, by Oxidative C-N Cleavage of [36]Adamanzane, 1,5,9,13-Tetraazatricyclo[7.7.3.35,13]docosane and Crystal Structure of the Tetraprotonated Bromide Salt of [35]Adamanzane.

Reaction of the cage amine [36]adamanzane, 1,5,9,13-tetraazatricyclo-[7.7.3.35,13]docosane, with sodium iodide in 93% sulfuric acid affords the bicyclictetraamine [35]adamanzane, 1,5,9,13-tetraazabicyclo[7.7.3]nonadecane which was isolated as its tetraprotonated bromide salt, [H4[35]adz]Br4 (yield 70%). The structure of the [H4[35]adz]Br4 has been determined by X-ray diffraction techniques at T=120 K; Mr=529.09, monoclinic, P21/n, a=11.300(3), b=12.563(3), c=15.561(6) Å, beta=90.29(3)degrees, Z=4, Dx=1.78 g cm-3, MoKa=0.71073 Å, mu=72.9 cm-1, F(000)=1176, R(F)=0.0734 for 4028 reflections with I>2 sigma(I) and wR(F2)=0.2116 for all 6439 unique reflections. The conformation of the 16-membered ring is best described as a distorted 'rectangular' [3535] conformation. The distance between the bridging nitrogen atoms is 4.983(9) Å, and the distance between the non-bridging atoms is 7.568(10) Å. The four acidic hydrogen atoms are all oriented away from the cavity. The concentration acid dissociation constants of H4[35]adz4+ were determined by potentiometric glass-electrode measurements and 1H and 13C NMR spectroscopy: pKa1=1-2, pKa3=9.65(2) and pKa4=12.09(4) (1 M NaBr, 25 degrees C).