1,4-Bis[2-(4-ferrocenylphenyl)-ethynyl]anthraquinone from synchrotron X-ray powder diffraction

The title compound, [Fe₂(C₅H₅) ₂(C₄₀H₂₂O₂)] or 1,4-(FcPh) ₂Aq [where FcPh is 2-(4-ferrocenylphenyl)ethynyl and Aq is anthraquinone], was synthesized in an attempt to obtain a new solvent-incorporating porous material with a large void space. Thermodynamic data for 1,4-(FcPh)₂Aq show a phase transition at approximately 430 K. The crystal structure of solvent-free 1,4-(FcPh)₂Aq was determined at temperatures of 90, 300 and 500 K using synchrotron powder diffraction data. A direct-space method using a genetic algorithm was employed for structure solution. Charge densities calculated from observed structure factors by the maximum entropy method were employed for model improvement. The final models were obtained through multistage Rietveld refinements. In both phases, the structures of which differ only subtly, the planar Aq fragments are stacked alternately in opposite orientations, forming a one-dimensional column. The FcPh arms lie between the stacks and fill the remaining space, leaving no voids. C - H⋯π interactions between the Ph and Fc fragments mediate crystal packing and stabilization.