TRI-MU-AMIDO-BIS-[TRIAMMINECHROMIUM(III)] IODIDE, [CR2(NH2)3(NH3)6]I3, A NEW HEXAGONAL PEROWSKITE

The compound [Cr2(NH2)3(NH3)6]I3 was synthesized by the reaction of Cr I2 with supercritical ammonia in high pressure autoclaves at 773 K and P(NH3) = 600 MPa. Its crystal structure was determined on the basis o f X-ray single crystal data: space group P6(3)/mmc, a = 7.670(2) angst rom, c = 18.096(4) angstrom, Z = 3, R/R(w=1) = 0.01610.018 for 396 obs erved structure factors with I greater-than-or-equal-to 3sigma (I). Th e compound contains dinuclear [Cr2(NH2)3(NH3)6]3+-cations with a short d(Cr - Cr) = 2.65 angstrom. The entire structure is described by a mo tif of a common close-packing of iodine and nitrogen. Chromium occupie s face-sharing nitrogen octahedra desribed by the stacking sequence... \A(Cr)B(Cr)A C(Cr)B(Cr)C\....