C-13-H-1 COUPLING-CONSTANTS IN CARBOCATIONS .7. APPLICATION OF THE DELTA-J EQUATION TO POLYCYCLIC SYSTEMS INCLUDING BICYCLO[2.2.1]HEPT-2-YLCATIONS

One-bond C-13-H-1 coupling constants have been measured for the polycy clic carbocations 2-methylbicyclo[2.2.2]octyl (10), 2-arylbicyclo[2.2. 2]octyl (11), 3-arylbicyclo[3.2.1]octyl (15), 8-methyltricyclo[5.2.1.0 (2,6)]decyl (23), 2-methyl-5,6-benzobicyclo[2.2.1]heptyl (25), 2-arylb icyclo[2.2.1]heptyl (27), 2-methyltricyclo[3.3.1.1(3,7)]decyl (17), an d 2-aryltricyclo[3.3.1.1(3,7)]decyl (18). Comparisons with the corresp onding ketones provided DELTAJ values consistent with classical cation s for 10, 11, 15, 23, and 25. In the case of 17 and 18 the low DELTAJ values suggest that 2-adamantyl cations are distorted significantly fr om sp2 toward sp3 hybridization. DELTAJ(C1H) values for 27 give an exc ellent linear correlation with sigma+, with no deviation at high elect ron demand. For the parent 2-norbornyl cation (28), exceptionally high values for DELTAJ are consistent with a nonclassical sigma-bridged st ructure in superacid.