Cyclopentadienylcaesium by high-resolution X-ray powder diffraction

The structure of solid (eta(5)-cyclopentadienyl)caesium, [Cs(C5H5)], has been refined by high-resolution powder X-ray diffraction. Atomic parameters based on the isostructural Rb analogue were used in the starting model. The compound crystallizes in space group Pnma, with Z = 4 and unit cell parameters a 11.3664(2), b = 8.8648(2) and c = 5.7200(1) Angstrom. [Cs(C5H5)] shows a polymeric zigzag chain, a so-called multidecker structure, with an average Cs-Cp-centroid distance of 3.140(5) Angstrom. [Cs(C5H5)] contains a single chain along the a axis. The chains are bent with a Cp-centroid-Cs-Cp-centroid angle of 129.7 (1)degrees.