On the elasticity of Copper(II)acetylacetonate crystals

Structure-property correlations in a wide variety of elastic molecular crystals indicate that (a) corrugated structures that can interlock readily (prevent plastic deformation either through geometrical or energetic considerations) and (b) a multitude of weak and dispersive intermolecular interactions that would act as structural buffers through easy rupture and reformation during deformation, are structural features that impart a crystal the ability to accommodate large elastic strains.1-4 Based on their studies on copper(II)acetylacetonate crystals (1, hereafter), Worthy et al. claimed that these criteria are “incorrect”.5 In order to examine their claim critically, we conducted detailed experiments on crystals of 1. Our flexure experiments show that they indeed readily undergo plastic deformation when bent on the (101) face, which contradicts Worthy et al.‘s assertion that the (101) face is highly elastic. Therefore, the crystal 1 is not an ideal model system for rejecting the prevailing and widely accepted-molecular mechanisms for exceptional elastic flexibility of organic crystals.