α-Tris(2,4-pentanedionato-k2O,O')aluminium(III) at 240, 210, 180, 150 and 110 K: a new δ phase at 110 K

The crystal structure of the title compound, [Al(C5H7O2)3], has been investigated by a multi-temperature measurement to provide information on thermal vibrations and disorder in the structure. At 110 K, the structure of a new δ polymorph could be determined. A disorder-order phase transition takes place between 150 and 110 K and is klassengleich. The unit-cell volume increases by a factor of three and the diffraction pattern shows weak supercell reflections