Structural depolymerization of titanium(IV) fluoride: basis for the formation of titanium(IV) fluoride complexes

The applicability of the concept of structural depolymerization is demonstrated by the example of titanium(IV) fluoride and its complex salts obtained in the systems CsF/TiF4/aHF, (Gua)(2)CO3/TiF4/aHF, (Gua)Cl/TiF4/aHF, and Im/TiF4/aHF (aHF, anhydrous hydrogen fluoride; (Gua(+)), guanidinium cation, [C(NH2)(3)](+); Im, imidazole). The compositions of the fluoridotitanates(IV) formed in these systems and their crystal structures are considered in terms of the degree of polymerization (epsilon). The latter is defined as the ratio between the number of bridging fluorine atoms (M - F-b - M) and the number of terminal fluorine atoms (M - F-t) in the [MnF4n+x](x-) (M = Ti; n >= 1) structural fragments. With increasing initial amount of fluoride ion donors (AX = CsF or in situ formed (Gua)F and ImHF) in AF/TiF4 reactions, the degree of polymerization of the crystal structures of the obtained salts decreases.