Ammonia-Borane Derived BN Fragments Trapped on Bi- and Trimetallic Titanium(III) Systems

Titanium(III) complexes containing unprecedented (NH₂ BH₂ NHBH₃ )^2- and {N(BH₃ )₃ }^3- ligands have been isolated, and their structures elucidated by a combination of experimental and theoretical methods. The treatment of the trimethyl derivative [TiCp*Me₃ ] (Cp*=η⁵ -C₅ Me₅ ) with NH₃ BH₃ (3 equiv) at room temperature gives the paramagnetic dinuclear complex [{TiCp*(NH₂ BH₃ )}₂ (μ-NH₂ BH₂ NHBH₃ )], which at 80 °C leads to the trinuclear hydride derivative [{TiCp*(μ-H)}₃ {μ₃ -N(BH₃ )₃ }]. The bonding modes of the anionic BN fragments in those complexes, as well as the dimethylaminoborane group trapped on the analogous trinuclear [{TiCp*(μ-H)}₃ (μ₃ -H)(μ₃ -NMe₂ BH₂ )], have been studied by X-ray crystallography and density functional theory (DFT) calculations.