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Polymorphism; Coordination compound; Crystal structure; Differential scanning calorimetry; Density functional theory
Abstract:
The crystal-to-crystal phase transition of the
previously reported dinuclear Ci-symmetric complex [{Cu(NO3)2(phen)}2(4,40-bipy)] (1) (phen = 1,10-phenanthroline; 4,40-bipy = 4,40-bipyridine) [Seidel et al. (2011) Z Anorg 637:1545–1554, 10] was studied in detail by differential scanning calorimetry (DSC), powder X-ray diffraction and variable temperature determinations of the
unit cell parameters on a single-crystal. A density functional theory (DFT) study was undertaken to elucidate effects of crystal packing on the molecular structure in the
solid-state. The DFT study confirmed that the molecular structures of 1 found in the solid-state do not represent the minimum energy conformation of the free molecule,
especially with respect to the twist of the 4,40-bipy bridging ligand. The DSC analysis revealed that the phase transition is a fully reversible process, and suggests that the relationship between the dimorphic forms of 1 is enantiotropic.
