Abstract: | Formation of the “Superoctahedral” Heteropolyanion Ni(TaF6)6]4? through Oxidation of Tantalum with Ammonium Fluoride at the Monel-Container Wall A few single crystals of (NH4)4Ni(TaF6)6] are obtained besides (NH4)TaF6] as the main product of the reaction of (NH4)F with tantalum powder in an He-are-welded Monel metal container at 400°C. The crystal structure (trigonal, R-3c (Nr. 167), Z = 6, a = 1723,0(2); c = 2166,6(2) pm; R1 = 0,0303, WR2 = 0,0609) contains the superoctahedral heteropolyanion Ni(TaF6)6]4? and (NH4)+ ions; it may be recognized as a derivative structure of the K4CdCl6 type according to (NH4)4Ni(TaF6)6]?K4Cd(Cl)6]. |