Short H· · ·H distances in norbornene derivatives

Abstract

A short H· · ·H intramolecular interaction was reported previously for an anhydride of syn-sesquinorbornene. The synthesis and structure of a such an anhydride with an additional five-membered dithiole ring has been investigated. While hydrogen atom positions are not accurately located, the 1.62 Å separation indicates this molecule is a candidate for the shortest H· · ·H interaction. Two cycloadducts of norbornadiene, which literature suggests might exhibit additional short interactions, are reported also; however, the isomers with minimal intramolecular interactions are the isolated products. C₂₂H₂₀O₃S₂, 3, crystallizes in P $\bar 1$ with a = 10.881(4), b = 13.712(8), C = 6.548(8) Å, α = 101.32(6), β = 107.49(5), γ = 90.49(4)°, D _calc = 1.445 g cm⁻³, and Z = 2, C₂₁H₂₀O₄Cl₈, 5, in P2₁/n with a = 8.168(2), b = 13.488(4), c = 23.500(6) Å, β = 94.72(2)°, D _calc = 1.597 g cm⁻³, and Z = 4, C₂₁H₂₈O₄, 6, in P> $\bar 1$ with a = 12.667(2), b = 12.792(2), c = 12.540(2) Å, α = 113.51(1), β = 98.18(1), α = 74.39(1)°, D _calc = 1.276 g cm⁻³, and Z = 4.