13C-1H Coupling Constants in Carbocations. 5. Trishomocyclopropenium Cations Generated from Bicyclohex-3-yl, Tricyclo2,4>oct-8-yl, and Pentacyclo2,4.03,8.05,7>non-9-yl Precursors

Article abstract of DOI:10.1021/jo00246a019

One-bond 13C-H coupling constants have been measured for the trismonocyclopropenium cations derived from bicyclo<3.1.0>hex-3-yl (1), tricyclo<3.2.1.0^2,4>oct-8-yl, (12, 14) and pentacyclo<4.3.0.0^2,4.0^3,8.0^5,7>non-9-yl (26, 27) precursors under stable ion conditions and compared with those of the corresponding model ketones. the ΔJ values thus obtained for the bridging carbons (21-32Hz) and the ajacent methylene or methine carbons (18-27 Hz) are large and not consistent with static or equilibrating classical structures for these cations.The data provide additional confirmation of the ??-bridged, nonclassical nature of these