In the gas phase, SbF5 adopts a trigonal bipyramidal structure of D3h point group symmetry (see picture). The material adopts a more complicated structure in the liquid and solid states. The liquid contains polymers wherein each Sb is octahedral, the structure being described with the formula ((μ-F) denotes the fact that fluoride centres bridge two Sb centres). The crystalline material is a tetramer, meaning that it has the formula [SbF4(μ-F)4. The Sb-F bonds are 2.02 Å within the eight-membered Sb4F4 ring; the remaining fluoride ligands radiating from the four Sb centers are shorter at 1.82 Å. The related species PF5 and AsF5 are monomeric in the solid and liquid states, probably due to the smaller sizes of the central atom, which limits their coordination number. BiF5 is a polymer.