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Incommensurate Phase in Λ-cobalt (III) Sepulchrate Trinitrate Governed by Highly Competitive N-H⋅⋅⋅O and C-H⋅⋅⋅O
Somnath Dey1,2, Andreas Schönleber1, Sander van Smaalen1
1Laboratory of Crystallography, University of Bayreuth, Universitätsstraße 30, 95447, Bayreuth, Germany.
Abstract:
Phase transitions in molecular crystals are often determined by intermolecular interactions. The cage complex of [Co(C12 H30 N8 )]3+ ⋅ 3 NO3 - is reported to undergo a disorder-order phase transition at Tc1 ≈133 K upon cooling. Temperature-dependent neutron and synchrotron diffraction experiments revealed satellite reflections in addition to main reflections in the diffraction patterns below Tc1 . The modulation wave vector varies as function of temperature and locks in at Tc3 ≈98 K. Here, we demonstrate that the crystal symmetry lowers from hexagonal to monoclinic in the incommensurately modulated phases in Tc1
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