Carbon-13 chemical-shift tensors in polycyclic aromatic compounds. 9. Biphenylene

The principal values of the C-13 chemical-Shift tensors of natural abundance biphenylene were measured at room temperature with the FIREMAT experiment. Of 18 crystallographically distinct positions (three sets of six congruent carbons each), the three primary bands have been resolved into seven single peaks and four degenerate peaks (two double, one triple, and one quadruple). Hence, eleven different chemical-shift tensors are reported. An interpretation of the data is made by comparison to carbon chemical-shift tensors in other molecules with similar chemical environments. Experimental and theoretical values based on a model of the asymmetric unit of the crystal unit cell are in good agreement.