X-ray crystal structures and solution dynamics of sodium organofluorotitanates [Na{Ti2(C5Me5)2F7}] and [NaTi6(C5Me5)5F20(H2O)]·(THF)

Na{Ti₂(C₅Me₅)₂F₇}] (1) was prepared from sodium fluoride and {Ti(C₅Me₅)F₃}₂] H.W. Roesky, et al., Angew. Chem. Int. Ed. Engl. 31 (1992) 864-866]. The solid-state 1 consists of a polymeric chain of two rows of dititanate anions Ti₂(C₅Me₅)₂F₇]⁻ connected by sodium ions in the middle of the chain. Each sodium ion is coordinated by five fluorine atoms from three Ti₂(C₅Me₅)₂F₇]⁻ anions. The variable-temperature ¹⁹F NMR of CD₃CN solution of 1 revealed interconversions of monomeric species Na(CD₃CN)_n{Ti₂(C₅Me₅)₂F₇}] (1solv) with different number of CD₃CN ligands on the sodium ion. The addition of HMPA to the CD₃CN solution of 1 allows ¹⁹F NMR observation of 1·HMPA (1a) and 1·HMPA·CD₃CN (1b) in the slow exchange. The solid-state structure of NaTi₆(C₅Me₅)₅F₂₀(H₂O)]·(THF) (2·THF) reveals the sodium ion coordinated by four fluorine atoms from the anion Ti₂(C₅Me₅)₂F₇]⁻ and by three fluorine atoms from the cluster Ti₄(C₅Me₅)₃F₁₃(H₂O)].