The static JT distortion itself is well known in the structures of MF 6 molecules with non-zero spin. However, the structure of the third-row transition metal hexafluorides may be stable in the presence of JT distortion. It is currently recognized that ReF 6 and OsF 6 show the dynamic JT effect , and the structures of ReF 6 , OsF 6 , IrF 6 , and PtF 6 are very close to O h based on electron-diffraction experiments in the gas phase , single-crystal X-ray diffractometry , and extended Xray absorption fine structure (EXAFS) . Even if it exists, the JT distortion may be smaller than experimental errors. In theory, the most sophisticated calculation for the third-row transition metal hexafluorides was carried out at the coupled cluster singles and doubles with perturbed triples (CCSD(T)) level with the SOC at the DFT level . Their calculated structures agree with the experiment well, but they compared the averaged bond lengths of the D 4h structures and experimental structures in O h symmetry. It was reported that the SO effect stabilizes the O h structures of PtF 6 and IrF 6