879657-27-9Relevant academic research and scientific papers
Non-redox-assisted oxygen-oxygen bond homolysis in titanocene alkylperoxide complexes: [Cp2TiIV(η1-OO tBu)L]+/0, L = Cl-, OTf-, Br -, OEt2, et3P
DiPasquale, Antonio G.,Hrovat, David A.,Mayer, James M.
, p. 915 - 924 (2006)
The titanium(IV) alkylperoxide complex Cp2Ti(OOtBu)Cl (1) is formed on treatment of Cp2TiCl2 with NaOO tBu in THF at -20 °C. Treatment of 1 with AgOTf at -20 °C gives the triflate complex Cp2Ti-(OOtBu)OTf (2), which is rapidly converted to the bromide Cp2Ti(OOtBu)Br (3) on addition of nBu4-NBr. The X-ray crystal structures of 1 and 3 both show η1-OOtBu ligands. Complex 2 is stable only below -20 °C; 1H, 13C, and 19F NMR spectra suggest that it also contains an η1-OOtBu ligand. Removal of the chloride from 1 with [Ag(Et2O) 2]BAr′4 (Ar′ = 3,5-(CF3) 2C6H3) yields the etherate complex [Cp 2-Ti(OOtBu)(OEt2)]BAr′4 (4). Again, coordination of a fourth ligand to the Ti center indicates an η1-OOt-Bu ligand in 4. These peroxide complexes do not directly oxidize olefins or phosphines. For instance, the cationic etherate complex 4 reacts with excess Et3P simply by displacement of the ether to form [Cp2Ti(η1-OOtBu)(Et 3P)]BAr′4 (5). Compounds 1-5 all decompose by O-O bond homolysis, based on trapping and computational studies. The lack of direct oxygen atom transfer reactivity is likely due to the η1 coordination of the peroxide and the inability to adopt more reactive η2 geometry. DFT calculations indicate that the steric bulk of the tBu group inhibits formation of the hypothetical [Cp 2Ti(η2-OOtBu)]+ species.
