Among the following the pair in which the two species are not isostructural is

SiF4 has symmetrical letrahedral shape which is due to sp3 hybridization of the central sulphur atom in its excited state configuration. SF4 has distorted tetrahedral or See-Saw geometry which arise due to sp3d hybridization of central sulphur atom and due to the presence of lone pair of electron in one of the equatorial hybrid orbital.