Fluoride crystal structures. Part IX. Seleninyl difluoride–niobium pentafluoride, SeOF2,NbF5

Abstract

Crystals of the adduct of seleninyl difluoride with niobium pentafluoride are orthorhombic, space group Pmcn, a= 8·02, b= 7·13, c= 11·09 Å. The structure was refined by three-dimensional least-squares methods, to R 0·103 for 445 independent reflections. In the adduct the seleninyl difluoride molecule forms an oxygen bridge to niobium and thus completes a distorted octahedral arrangement around the niobium atom. The Se–F distance is 1·68 and Se–O is 1·60 Å, close to the corresponding values of 1·727 and 1·580 Å in seleninyl difluoride vapour. Intermolecular contacts to fluorine of 2·69, 2·69, and 2·88 Å complete a much distorted octahedral co-ordination around the selenium atom.