C-13 CHEMICAL-SHIFTS AND C-13-N-15-COUPLING CONSTANTS OF SOME N-15-LABELED BRIDGEHEAD NITRO-COMPOUNDS

Measurement of the C-13 NMR spectra of the bridgehead nitro compounds 1a-5a has been performed. It is found that one-bond C-13-N-15 coupling is not necessarily a reflection of the degree of s character of the b ridgehead carbon exocyclic bonding orbital. Although the magnitude of vicinal coupling to the bridgehead carbon increases, in accordance wit h the number of three-bond pathways available for transmission of spin information, coupling is actually reduced by opposing contributions f rom through-space intramolecular orbital interactions.