NUCLEOPHILIC CLEAVAGE PRODUCTS FROM BETA-DEPROTONATED SESQUIDIAZABICYCLOOCTANE DICATION

Nucleophilic cleavage of aminoaziridinium cation 2(+) by PhS(-), N=C-, CH3CO2-, and F- results in C-N+ bond cleavage with inversion at carbo n, producing essentially only the axially-substituted (X) (22/31) deri vatives for the latter two cases, but 40 and 15% exo-substituted 1(X) (22/22) are initially produced for thiophenoxide and cyanide, respecti vely. The increase in oxidation potential for 3(CN) vs 3 (0.22 V) is t he same as that for replacement of the corresponding ii by CN in an ac yclic system. X-ray structures show that larger changes in nitrogen py ramidality (Delta alpha(av) + 8.4 vs + 5.8 degrees) and NN distance (- 0.172 vs -0.160 Angstrom) occur upon electron loss from 3 than from 1. Despite more constricted bond angles at nitrogen, crystalline 3(+)TsO (-) is more planar than 1(+)TsO(-) (alpha(av) = 119.1 degrees vs 118.6 degrees), and the two double nitrogen inversion forms of 3(+) are est imated to differ in energy by under 0.02 kcal/mol in solution from END OR and ESR studies. 3(0/+) shows slower self-electron transfer than 1( 0/+) (k(ex) (25 degrees C, CH3CN) similar to 300 vs 700 M(-1) s(-1)). Neither more planar nitrogens for 3(+) than for 1(+) nor slower electr on transfer for 3(0/+) are predicted by AM1 calculations.