THE CRYSTAL-STRUCTURES OF (NH4)(2)[RECL6] , [RECL2(CH3CN)(4)](2)[RECL6]CENTER-DOT-2CH(3)CN AND [RECL4(18-CROWN-6)]

Brown single crystals of (NH4)(2)[ReCl6] are formed by the reaction of NH4Cl with ReCl5 in a suspension of diethylether. [ReCl2(CH3CN)(4)](2 )[ReCl6] . 2CH(3)CN crystallizes as brown crystal plates from a soluti on of ReCl5 in acetonitrile. Lustrous green single crystals of [ReCl4( 18-crown-6)] are obtained by the reaction of 18-crown-6 with ReCl5 in a dichloromethane suspension. All rhenium compounds are characterized by IR spectroscopy and by crystal structure determinations. (NH4)(2)[R eCl6]: Space group Fm $($) over bar$$ 3m, Z = 4, 75 observed unique re flections, R = 0.01. Lattice constant at -70 degrees C: a = 989.0(1) p m. The compound crystallizes in the (NH4)(2)[PtCl6] type, the Re-Cl di stance is 235.5(1) pm. [ReCl2(CH3CN)(4)](2)[ReCl6] . 2CH(3)CN: Space g roup P $($) over bar$$ 1, Z = 1,2459 observed unique reflections, R = 0.12. Lattice dimensions at -60 degrees C: a = 859.0(1), b = 974.2(7), c = 1287.3(7) pm, alpha = 102.69(5)degrees, beta = 105.24(7)degrees, gamma = 102.25(8)degrees. The structure consists of two symmetry-indep endent [ReCl2(CH3CN)(4)](+) ions with trans chlorine atoms, [ReCl6](2- ) ions, and included acetonitrile molecules. In the cations the Re-Cl bond lengths are 233 pm in average, in the anion they are 235 pm in av erage. [ReCl4(18-crown-6)]: Space group P2(1)/n, Z = 4, 3633 observed unique reflections, R = 0.06. Lattice dimensions at -70 degrees C: a = 1040.2(4), b = 1794.7(5), c = 1090.0(5)pm, beta = 108.91(4)degrees. T he compound forms a molecular structure, in which the rhenium atom is octahedrally coordinated by the four chlorine atoms and by two oxygen atoms of the crown ether molecule.