SYNTHESIS AND CRYSTAL-STRUCTURE OF NAZN(O H)(3)CENTER-DOT-3H(2)O AND NAZN(OH)(3)

The electrochemical corrosion of zinc in a zinc/iron-pair leads in an ammonia containing solution of sodium hydroxide at room temperature to colourless crystals of NaZn(OH)(3) . 3H(2)O. The X-ray structure dete rmination on these crystals was successful including all hydrogen posi tions. P (1) over bar, Z = 2, a = 3.344(1)Angstrom, b = 8.058(1)Angstr om, c = 11.138(2)Angstrom alpha = 93.13(2)degrees, beta = 98.31(2)degr ees, gamma = 93.40(2)degrees, N(F-0(2) greater than or equal to 2 sigm a F-0(2)) = 2340, N(Var.) = 101, R-1/wR(2) = 0.034/0.081. NaZn(OH)(3) . 3H(2)O contains Zn2+ in tetrahedral coordination by OH-and Naf in oc tahedral coordination by one OH-and five H2O. The tetrahedra around Zn 2+ form corner-sharing chains, the octahedra around Na+ form edge-shar ing chains. Raman spectroscopic measurements indicate weak hydrogen br idge bonds between H2O as donor and OH-. For NaZn(OH)(3) data determin ed by X-ray-structure analysis are given: P4(2)bc, 2 = 8, a = 10.831(2 )Angstrom, c = 5.330(1)Angstrom, N = (F-0(2) > 2 sigma F-0(2)) = 525, N(Var.) = 56, R-1/wR(2) = 0.030/0.062. The structure of NaZn(OH)3 is d iscussed with respect to previous investigations.