STUDIES OF POLYHALIDES - XXXVII - HEPTAIODIDES(3-) OF AMINE COMPLEXESOF CHROMIUM AND COBALT - HEXAMINECHROMIUM(III) HEPTAIODIDE [CR(NH3)(6)](I-3)(I-4) AND THE TRI-MU-HYDROXO-BIS[METAL(III)-TRIAMMINE] HEPTAIODIDES [(NH3)(3)M(OH)(3)M(NH3)(3)](I-3)(2)I WITH M = CO, CR

The new compounds [Cr(NH3)(6)](I-3)(I-4) and [(NH3)(3)M(OH)(3)M(NH3)(3 )](I-3)(2)I with M = Cr, Co have been prepared by the reaction of [M(N H3)(6)]X-3 (M = Cr, Co; X = Cl, I, NO3), KI, and I-2 in water under co ntrolled stoichiometric and pH conditions. The first compound is isoty pic with the cobalt compound of the same composition. It crystallizes in the monoclinic space group I2/m with a = 984.7(3), b = 786.6(1), c = 1330.1(3) pm, beta = 95.34(2)degrees and Z = 2 and contains nearly o ctahedral cations [Cr(NH3)(6)](3+), a linear triiodide ion I-3(-) and a tetraiodide ion I-4(2-). The two other compounds are isotypic. They crystallize in the orthorhombic space group Pnma with a = 2629.6(14)/2 633.5(2), b = 798.3(11)/797.3(1), c = 1127.6(7)/1125.7(1) pm and Z = 3 for Co/Cr respectively. The heptaiodide(3-) ion is broken into two tr iiodide ions and one iodide ion.