Lithium complexes with a [Cp*2Ti2F7]– ligand: 19F NMR probe for lithium solvation

Reaction of the in situ prepared lithium fluoride with [Cp*TiF3]2 afforded [{Li(Cp*2Ti2F7)}2(THF)2]·2THF, 3· 2THF. The addition of 12-crown-4 to a THF solution of 3·2THF results in [{Li(Cp*2Ti2F7)}2(µ2-1:1-12-crown-4)]· (12-crown-4), 4·(12-crown-4). In the solid state structures of 3·2THF and 4·(12-crown-4), which consist of dimeric [Li(Cp*2Ti2F7)]2 units, the lithium atom is coordinated by three fluorine atoms and an oxygen atom from the ether. Dimeric and monomeric (with respect to lithium) species were observed in solution of 3·2THF or 4·(12crown-4). The solvation of the lithium atom in monomeric species [Li(Cp*2Ti2F7)Sn] with S = CDCl3, 12-crown-4, THF-d8, was studied by variable temperature 19F NMR spectroscopy. Slow exchange of coordinated deuterated trichloromethane and 12-crown-4 on lithium ion was observed in a CDCl3/12-crown-4 solution of 4·(12-crown-4) by 19F NMR spectroscopy up to 302 K.