Three hexafluoridoiridates(IV), Ca[IrF6].2H2O, Sr[IrF6].2H2O and Ba[IrF6]

The structures of the hexafluoridoiridates(IV) of calcium, Ca[IrF(6)].2H(2)O [calcium hexafluoridoiridate(IV) dihydrate], strontium, Sr[IrF(6)].2H(2)O [strontium hexafluoridoiridate(IV) dihydrate], and barium, Ba[IrF(6)] [barium hexafluoridoiridate(IV)], have been determined by single-crystal X-ray analysis. The first two compounds are isomorphous. Their metal cations are eight-coordinated in a distorted square-antiprismatic coordination environment, and their anions are represented by an almost ideal octahedron. These two structures can be described as frameworks in which all atoms occupy general positions. Sr[RhF(6)] and Ba[RhF(6)] have a different space group (R\overline{3}m, from powder diffraction data) but similar cell dimensions. The structures are very close to that of Ba[IrF(6)]. The cation is in a cuboctahedral coordination. The metal atoms are located on special positions of \overline{3} symmetry, while the F atoms are in general positions.