Extremely short non-bonded H ? H distance in two derivatives of exo, exo-tetracyclo[6.2.1.13,6.02,7]dodecane

Non-bonded H ⋯ H distances of 1.754(4) and 1.713(3)Å have been measured by low-temperature neutron diffraction experiments on the crystals of exo,exo-tetracyclo[6.2.1.13,6.02,7]dodecan-4-yl 3′,5′-dinitrobenzoate (2) and exo,exo-tetracyclo[6.2.1.13,6.02,7]dodecane-2,7-dicarboxylic anhydride (3); empirical force field calculations for parent gaseous hydrocarbons give larger values by about 0.14 Å.