Synthesis and structure of Sr6Ge5N2 and Ba6Ge5N2

Abstract

Two isostructural new alkaline earth germanium nitrides, Sr6Ge5N2 and Ba6Ge5N2, were obtained as single crystals from constituent elements in molten Na. They both crystallize in space group P-mmn (No. 59) with a = 4.0007(8), b = 17.954(3), c = 9.089(2) angstrom, Z = 2, and a = 4.1620(2), b = 18.841 (1), c = 9.6116(5) angstrom, Z = 2, for Sr6Ge5N2 and Ba6Ge5N2, respectively. Their crystal structure contains features for both Zintl and nitride phases: zigzag anionic chain of Ge-infinity(2-), and dumbbell-shaped bent anion of GeN24-. Counter cations of Sr or Ba wrap these anionic units in a channel-like arrangement. Unlike in other germanium nitrides, bond lengths of both GeN arms of the GeN24-, are same in Sr6Ge5N2 and Ba6Ge5N2.