Rh3B2-x, new structure type of binary borides with triclinic symmetry

New binary compound Rh3B2-x, x=0.167 crystallizing with its own structure type has been observed from the as cast alloys. The compound has a limited thermal stability range: it was found to decompose after annealing at 800oC for 20 days. The crystal structure was investigated by X-ray diffraction from two single crystals using different techniques: CAD-4 automatic diffractometer, a=5.470(2), b=6.816(3), c=9.068(4), α=110.74(3), β=94.81(3), γ=90.44(2), 107 refined parameters, R1=0.0418, wR2=0.1087 for 1223 reflections with I>2σ(Io), and BRUKER SMART AXS, a=5.483(4), b=6.818(6), c=9.072 (7), a=110.78(1), b=94.73(1), g=90.46(1), 107 refined parameters, R1=0.0401, wR2=0.0959 for 943 reflections with I>2σ(Io). The Rh3B2-x, structure (space group P1-bar , Pearson symbol aP30-1) is the first representative of structures with triclinic symmetry among binary borides and contains three different types of boron-boron aggregation: isolated boron atoms, B-B pairs and B6 chain fragments