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Polymorphism of 2-Adamantanone

2014; American Chemical Society; Volume: 14; Issue: 5 Linguagem: Inglês

10.1021/cg500313m

1528-7505

Ph. Négrier, Marı́a Barrio, Michela Romanini, J. Ll. Tamarit, Denise Mondieig, А. И. Кривчиков, Leszek Kępiński, A. Jeżowski, Daria Szewczyk,

Phase Equilibria and Thermodynamics

The polymorphism of 2-adamantanone (C10H14O) has been investigated by means of X-ray diffraction and high-pressure thermal analysis. The intricate behavior of the low-temperature crystalline phases has been disentangled. The stable phase has been found to be orthorhombic (Cmc21, Z = 4), fully ordered, with lattice parameters a = 6.8884(18) Å, b = 10.830(3) Å, c = 10.658(3) Å, and V/Z = 198.8(1) Å3. The metastable phase was determined to be monoclinic (P21/c, Z = 4) with lattice parameters a = 6.5920(17) Å, b = 11.118(3) Å, c = 12.589(3) Å, β= 118.869(11) o, and V/Z = 202.0(1) Å3. The pressure–temperature phase diagram irrefutably shows the stability relation between both phases and, accordingly, the long-time unknown polymorphic behavior is now revealed and gives coherent physical explanation of the literature published so far.