Short H center dot center dot center dot H distances in norbornene derivatives

A short H ... H intramolecular interaction was reported previously for an a nhydride of syn-sesquinorbornene. The synthesis and structure of a such an anhydride with an additional five-membered dithiole ring has been investiga ted. While hydrogen atom positions are not accurately located, the 1.62 Ang strom separation indicates this molecule is a candidate for the shortest H ... H interaction. Two cycloadducts of norbornadiene, which literature sugg ests might exhibit additional short interactions, are reported also; howeve r, the isomers with minimal intramolecular interactions are the isolated pr oducts. C22H20O3S2, 3, crystallizes in <P(1)over bar> with a = 10.881(4), b = 13.712(8), C = 6.548(8) Angstrom, alpha = 101.32(6), beta = 107.49(5), g amma = 90.49(4)degrees, D-calc = 1.445 g cm(-3), and Z = 2, C21H20O4Cl8, 5, in P2(1)/n with a = 8.168(2), b = 13.488(4), c = 23.500(6) Angstrom, beta = 94.72(2)degrees, D-calc = 1.597 g cm(-3), and Z = 4, C21H28O4, 6, in <P(1 )over bar> with a = 12.667(2), b = 12.792(2), c = 12.540(2) Angstrom, alpha = 113.51(1), beta = 98.18(1), alpha = 74.39(1)degrees, D-calc = 1.276 g cm (-3), and Z = 4.