A Fluorine-19NMR Study of Some Bromofluorotitanate Complexes and Hydrolysis of Some Titanium Tetrafluoride Complexes.

摘要

Low temperature fluorine-19nuclear magnetic resonance (NMR) spectroscopy has been used to examine a number of fluorotitanate complexes of the type TiF(x) Br(4-x):2THF (THF =tetrahydrofuran) and TiF(x) Br(4-x):DME (DME = 1,2-dimethoxyethane) where x is 1to 4. Hydrolysis studies have also been carried out on the TiF4:2THF complex in excess THF and on TiF4:2EtOH in excess EtOH (EtOH =ethanol). Attempts were also made to study similar fluorotitanate complexes containing tetrahydrothiophene in place of THF and iodide in place of bromide. The complexes examined were found to contain octahedrally coordinated titanium and in some cases more than one geometric form was observed. DME acts as a bidentate chelating agent and coordinates through its oxygen atoms to titanium with a cis orientation. Fluorine-19chemical shift values and coupling constants were determined for each complex. The stereochemistry was also determined for each complex where possible. A hypothetical model which considers the extent of ligand to titanium pi-bonding is discussed in an attempt to relate the observed fluorine-19NMR spectra to the stereochemistry of the complexes present. (Author)