Abstract
The crystal and molecular structure of the compound ReaOCUÍCjHsCOaHPÍCeHsMj reported recently by Rouschias and Wilkinson has been determined by means of single-crystal X-ray diffractometry. The molecular structure is essentially, though not in all respects, that postulated by Rouschias and Wilkinson. There are two octahedrally coordinated rhenium atoms with the octahedra joined on a common edge; the bridging atoms on this common edge are Cl and O. The propionato group fills one apical coordination position in each octahedron and the remaining positions in each are filled by two Cl atoms and a phosphorus atom. The phosphorus atoms are trans to the bridging chlorine atom. Neglecting the orientations of the phenyl rings and the /3-carbon atom of C2H5CO2, the structure has a virtual mirror plane containing the bridging O and Cl atoms and the carboxyl carbon atom. The quadrilateral formed by the two bridging atoms and the two rhenium atoms is practically planar, with an Re-Re distance of 2.522 ± 0.001 Á. The crystals, which were black, with tetragonal prismatic morphology (p = 1.94 g cm-3 at ^23°) belong to the tetragonal system with a = 10.669 ± 0.003 A and c = 34.898 ± 0.007 Á. For Z = 4, pcaic:i = 1.945 g cm-3. The structure was solved by Patterson and Fourier methods and refined by least squares. Systematic absences indicated the space group to be P4i or P43. The use of 3156 hkl reflections and 446 hkl re- flections permitted an unambiguous choice (for this particular crystal) of P43, for which final weighted and unweighted resid- uals of 0.050 and 0.044, respectively, were obtained.