(Ba6O)(ReN3)2: Synthesis, Crystal Structure and Physical Properties

The reaction of a mixture of barium and rhenium (3:1) at 850 degrees C under flowing nitrogen yielded the nitride-oxide (Ba6O)(ReN3)(2) (R (3) over bar (No. 148); a = 8.1178(2) angstrom, c = 17.5651(4) angstrom; V = 1002.43(5) angstrom(3); Z = 6). According to a structure refinement on X-ray powder diffraction data, this compound is isostructural to a recently described nitride-oxide of osmium of analogous composition. The structure consists of sheets of trigonal ReN3 units and trigonal antiprismatic Ba6O groups. The Ba-O distance of 2.73 angstrom is close to the sum of the respective ionic radii. The trigonal ReN35- nitride anion displays a Re-N bond length of 1.94 degrees, and is planar within the limits of experimental error. The constitution of the anion was confirmed by IR and Raman spectroscopy. The nitride-oxide is stable up to 1000 degrees C, semiconducting (sigma = 4.57 x 10(-3) Omega(-1).cm(-1) at RT), and paramagnetic down to 25 K. A Curie-Weiss analysis resulted in a magnetic moment of mu = 0.68 mu(B) per rhenium atom.