Synthesis and Crystal Structure of the Electron-Rich Cyano-Rhodate Ba3[Rh(CN)3].

Brownish gray microcrystalline powders of Ba₃[Rh(CN)₃] were synthesized from pellets of mixtures of Ba₂N, rhodium, NaCN, and graphite at 1070 K in an argon atmosphere. Synchrotron powder diffraction data at 293(1) K revealed the crystal structure of the compound [ P6₃/ m, a = 9.23266(7) Å, c = 5.81612(6) Å] is isostructural to Ba₃[Co(CN)₃] and Ba₃[Ir(CN)₃]. The trigonal-planar complex [Rh(CN)₃]^6- is surrounded by nine Ba²⁺ cations forming a tri-capped trigonal prism. Compared to typical cyano ligands, the C-N bond is long [1.21(5) Å] and the vibrational frequencies are low (IR 1674 cm^-1, Raman 1728 cm^-1). [ABSTRACT FROM AUTHOR]