(CuI)P4Se4: An Adduct of Polymeric P4Se4 with CuI

Pure yellow (CuI)P4Se4 was prepared by reaction of stoichiometric amounts of CuI, red P, and gray Se in evacuated silica ampoules. The crystal structure was determined from single crystals at room temperature. (CuI)P4Se4 crystallizes in the orthorhombic system, space group Cmca with a = 14.770 (1) AÊ , b = 12.029 (1) AÊ , c = 12.449 (1) AÊ , V = 2211.9(6) AÊ , and Z = 8. The structure refinement converged to R = 0.0190 (wR = 0.0272) for 1020 independent reflections and 51 parameters. A prominent feature of the crystal structure are neutral polymeric P4Se4 strands which are connected by copper iodide. These strands consist of norbornane analogous P4Se3 cages which are linked by selenium bridges. The polymers are achiral since a mirror plane exists perpendicular to the strands. The single polymers are connected by [Cu2I2] units to form layers. These layers are stacked along the b axis and are connected by van der Waals-interactions only. Raman spectra of (CuI)P4Se4 differ significantly from Raman spectra of (CuI)3P4Se4 and catena(P4Se4)x.