PARTIAL SUBSTITUTION OF NICKEL BY SODIUM IN NICKEL(II)-AMIDE - ISOLATED NA4NI2(NH2)8.4NH3 GROUPINGS IN SODIUM-TETRAAMIDONICCOLATE(II)-DIAMMONIATE

Single crystals of Na2Ni(NH2)4.2NH3 are obtained in liquid ammonia at room temperature by the reaction of NaNH2 with Ni(NH2)2 or NiBr2 as well as [Ni(NH3)3](SCN)2 in a molar ratio of 2:1 or 4:1 respectively. The compound shows a considerable NH3 pressure just at -33-degrees-C. Therefore an apparatus was developed which allows to select crystals under a dry NH3 atmosphere at room temperature. X-ray investigations gave the following data: Na2Ni(NH2)4.2NH3: I4/m, N = 4, a = 8.932(2) angstrom, c = 10.984(2) angstrom, rho(X-ray) = 1.538 g cm-3, R/R(w) = 0.029/0.031 with w = 1, N((F(0)2) greater-than-or-equal-to 2-sigma(F(0)2)) = 277, N(Variables) = 40 The orange-red amido-ammoniate contains two planar [Ni(NH2)4]2-ions oriented parallel to [001] which form ground and top of a prism, that is side-capped by Na+ions and in greater distance by NH3 molecules. Na+ions are coordinated pyramidal by 4NH2- and 1NH3. 4Na+- and 2Ni2+ ions are arranged to a deformed octahedron that is surrounded by a compressed cuboctahedron of 8NH2- and 4NH3. This arrangement hints to an analogy in the structure of Ni(NH2)2, which contains Ni6(NH2)12 groups.