Single-crystal X-ray structural refinement of the `tetragonal' C60 polymer

The single crystals of the `tetragonal' C60 polymer were prepared by the polymerization of C60 single crystals under a pressure of 2.5 GPa at 500 °C. The X-ray structural analysis resulted in the orthorhombic space group Immm; a=9.026(2) Å, b=9.083(2) Å, c=15.077(3) Å, and Z=2; R1/wR2=0.0731/0.1719 for 654 observed reflections and 74 variables. The crystal structure represents a pseudo-tetragonal packing of translationally identical adjacent two-dimensional (2D) layers formed by the polymerization of C60 molecules via [2+2] cycloaddition.