BICYCLO[2.2.1]HEPTA-2,5-DIENE-2,3-DICARBOXAMIDE, C9H10N2O2

Intramolecular hydrogen bonding between the amido groups [O(81)...H(111) = 1.89(4) angstrom and N(11)-H(111)...O(81) = 151(3)-degrees] maintains the molecule in a conformation that favours partial delocalization between the amido groups and the adjacent C(2)=C(7) double bond. This can be interred from a shortening of the C(1)-C(2) and C(7)-C(8) single bonds [1.479 (3) and 1.481 (3) angstrom, respectively] and a small lengthening of the C(2)=C(7) double bond [1.341 (3) angstrom]. Partial relief of the strain in the cycle then allows a shortening of the C(4)=C(5) double bond [1.285 (4) angstrom] 11.330(3) angstrom in unsubstituted norbornadiene; Morino, Kuchitsu & Yokoseki (1967). Bull. Chem. Soc. Jpn, 40, 1552]. The crystal also exhibits intermolecular N-H...O hydrogen bonding, with N...O distances in the range 2.960(3)-2.978(3) angstrom and N-H...O angles between 160 (3) and 174 (3)-degrees.