Na ₄ Ba ₉ MnN ₃ : A New Subnitridometalate with Trigonal Planar Anions [Mn ^III N ₃ ] ⁶⁻

Abstract

The new subvalent nitridomanganate(III) Na 4 Ba 9 MnN 3 was obtained by reacting Ba 2 N with Ba, Na, and Mn. The structure crystallizes with a new structure type in hexagonal metric (space group P 6 3 / mmc (No. 194), lattice parameters a = 11.9583(5), and c = 11.7822(5) Å). The structure features isolated trigonal planar nitridomanganate(III) anions (MnN 3 ) 6− , coordinated by a triply capped trigonal prism of nine barium atoms. The isolated cluster units [Ba 9 (MnN 3 )] are separated by metallic sodium atoms, which are coordinated by mixed barium‐sodium icosahedra [Na@Na 6 Ba 6 ] and [Na@Na 4 Ba 8 ]. The trigonal planar nitridomanganate anion (MnN 3 ) 6− has already been described in the crystal structure of the valence compound Ba 3 (MnN 3 ). The MnN bond lengths are virtually identical in both compounds and indicate a formal oxidation state of +III for manganese. A formal electron counting according to (Na + ) 4 (Ba 2+ ) 9 (MnN 3 ) 6− . 16 e − emphasizes the metallic character of the new subvalent compound.