Structural Novelties in Anionic Cluster Halide Phases. Discrete Tetrahedral A(4)Br(+) Ions in Two New Zirconium Bromide Structures (A = Na-Cs).

Suitable reactions of ABr, Zr, ZrBr(4), and an interstitial Z element in Ta containers at 850 degrees C afford two series of quaternary cluster phases containing A(4)Br(3+) ions. Cubic (A(4)Br)(2)Zr(6)(Z)Br(18) phases occur for various combinations of A = Na-Cs, Z = Be, B, H, Mn. The combination with A = K, Z = B was structurally characterized (inverse fluorite, Fm&thremacr;m, Z = 4, a = 16.191(2) Å). The 15-e cluster exhibits the appropriate magnetic moment, and this decreases toward the diamagnetic 14-electron limit in products with potassium deficiencies, (K(4)(-)(x)())(2)Zr(6)Br(18)B, x </= approximately 0.5. The tetragonal Cs(4)Br[Zr(6)(B)Br(12)]Br(4) (P&fourmacr;2(1)m, Z = 2, a = 12.5482(7) Å, c = 11.5610(9) Å) contains a new type of puckered M(6)Br(16) layers with Cs(4)Br(3+) in tunnels normal to the layers. Both examples of A(4)Br(3+) ions have short central Br-A bonds plus three to nine more distant bromines in neighboring clusters about each A, respectively.