The Complex Amide K-2[Zr(NH2)(6)]

We present the low-temperature synthesis of potassium hexaamido zirconate(IV) from the transition metal tetrafluoride and the alkali metal dissolved in liquid ammonia at -40 degrees C. Potassium hexaamido zirconate(IV) K2Zr(NH2)(6)] is the first ternary amide reported for elements of group 4 of the periodic table It crystallizes with a novel structure type in the trigonal space group R (3) over barc with a = 6.5422(2) angstrom, c = 32.824(2) angstrom, V = 1216.66(9) angstrom(3), Z = 6 and c/a = 5.017. The structure can be derived from the K2PtCl6 type. The compound contains discrete D-3-symmetric [Zr(NH2)(6)](2) anions which differ significantly from octahedral shape. Quantum chemical calculations show the distortion to arise from a splitting of degenerate d-orbitals on the zirconium atom leading to a significant gain in energy.