A Raman investigation of some metal (II) hexafluorosilicate (IV) and hexafluorotitanate (IV) salts

Abstract Raman data on M(II)(H 2 O) 6 SiF 6 (MNi, Fe, Mg, Zn) and M(II)(H 2 O) 6 TiF 6 (MNi, Zn) are presented. The results allow a positive identification of the symmetric MO stretch for the first time in these salts; other band assignments are also discussed. Low temperature (300⩽ T K⩽15) results are also presented and a discussion of the mechanism of the phase transition at 120 K in NiTiF 6 ·6H 2 O is given. It is shown that the phase transition in this salt has a different origin from that in the hexafluorosilicate salts.