A molecular ‘back-flip’: the structural consequences of the crystal-to-crystal phase transition between [(phen)2CuCO3]·11H2O and [(phen)2CuCO3]·7H2O

Abstract

Metastable [(phen)₂CuCO₃]·11H₂O, 1, crystallises in P-1 and undergoes a crystal-to-crystal phase transition, giving [(phen)₂CuCO₃]·7H₂O, 1a, in P2₁/c. Intermolecular π-π interactions between the complexes generate 2-D lattices with (6,3) topology, ‘brick-like’ in 1 and herringbone in 1a; a transition that requires a remarkable 180° rotation (a molecular back-flip) of adjacent [(phen)₂CuCO₃] units to have occurred during the phase change.