The crystal structure and polarised Raman spectrum of Rb2AgI3

The crystal structure of Rb 2 AgI 3 , space group Pnma, a = 10.258(2), b = 4.886(4), c = 20.063(10) Å, has been refined. It is isostructural with K 2 AgI 3 with chains of corner linked AgI 4 tetrahedra (Ag—I(bridge) = 2.881 Å, Ag—I(terminal) = 2.834 Å) running along b. The average bonding distance around the two seven coordinate Rb atoms is 3.722 Å. The polarised Raman spectrum shows the expected 36 modes which are assigned to four different symmetry species. All modes occur with frequencies less than 112 cm −1 .