Reactivity at the β-Diketiminate Ligand Nacnac- on Titanium(IV) (Nacnac- = [Ar]NC(CH3)CHC(CH 3)N[Ar], Ar = 2,6-[CH(CH3)2]2C 6H3). Diimine-alkoxo and Bis-anilido Ligands Stemming from the Nacnac-Skeleton

Article abstract of DOI:10.1021/ic034853e

The reaction of ketene OCCPh₂ with the four-coordinate titanium(IV) imide (L₁)Ti=NAr(OTf) (L₁^- = [Ar]NC(CH₃)-CHC(CH₃)N[Ar], Ar = 2,6-[CH(CH ₃)₂]₂C₆H₃) affords the tripodal dimine-alkoxo complex (L₂)Ti=NAr(OTf) (L₂ ^- = [Ar]NC(CH₃)CHC(O)=CPh₂C(CH ₃)N[Ar]). Complex (L₂)Ti=NAr(OTf) forms from electrophilic attack of the β-carbon of the ketene on the γ-carbon of the Nacnac^- NCCγCN ring. On the contrary, nucleophiles such as LiR (R^- = Me, CH₂^tBu, and CH ₂SiMe₃) deprotonate cleanly in OEt₂ the methyl group of the β-carbon on the former Nacnac^- backbone to yield the etherate complex (L₃)Ti=NAr(OEt₂), a complex that is now supported by a chelate bisanilido ligand (L₃^2- = [Ar]NC(CH₃)CHC(CH₂)N[Ar]). In the absence of electrophiles or nucleophiles, the robust (L₁)Ti=NAr(OTf) template was found to form simple adducts with Lewis bases such as CN^tBu or NCCH₂(2,4,6-Me₃C₆H₂). Complexes (L₂)Ti=NAr(OTf), (L₃)Ti=NAr(OEt₂), and the adducts (L₁)Ti=NAr(OTf)(XY) [XY = CN^tBu and NCCH ₂(2,4,6-Me₃C₆H₂)] were structurally characterized by single-crystal X-ray diffraction studies.