Fluoride crystal structures. Part XX. Niobium pentafluoride–antimony pentafluoride

Abstract

Crystals of the title adduct are triclinic, space group P, a= 5·64, b= 9·58, c= 7·38 Å, α= 87·2, β= 99·9, γ= 106·5°. The structure was determined from photographic data by Patterson and Fourier methods and refined by three-dimensional least-squares methods to R 0·065 for 906 reflections. The structure consists of a zigzag endless chain arrangement with alternating antimony and niobium atoms linked by cis-bridging fluorine atoms. Both metal atoms have a distorted octahedral co-ordination by fluorine atoms, the distortion being greater for niobium, consistent with a substantial contribution to the structure from the ionic form [NbF₄]⁺[SbF₆]^–.