References

General ChemistryCatalysisOrganic Chemistry

Phase Transition of [2,2]‐Paracyclophane – An End to an Apparently Endless Story

Published in Chemistry – A European Journal
Authors Hilke Wolf, Dirk Leusser, Mads R. V. Jørgensen, Regine Herbst‐Irmer, Yu‐Sheng Chen, Ernst‐Wilhelm Scheidt, Wolfgang Scherer, Bo B. Iversen, Dietmar Stalke

AbstractIn this contribution, the solid‐state low‐temperature phase structure of [2,2]‐paracyclophane is unambiguously characterised by single‐crystal X‐ray analysis. Additionally, a heat capacity measurement was undertaken, which proves the existence of a λ‐type phase transition at 45 K, a transition that is connected with the formation of a secondary Cp/T feature at 60 K. The low‐temperature phase (<45 K) crystallises in the lower symmetry space group P$\bar 4$n2, whereas the high‐temperature phase (>60 K) crystallises in space group P42/mnm. This proves what has been postulated both by experimental and theoretical chemists but has repeatedly been dismissed as speculation many times.