We
report a combined synthetic, mechanistic, and computational
(DFT) study of the synthesis of new diamide-amine-supported
titanium borylimides and their reactions with TolCCH and Ar<sup>F</sup>CCH (Tol = 4-C<sub>6</sub>H<sub>4</sub>Me, Ar<sup>F</sup> = C<sub>6</sub>F<sub>5</sub>). Reaction of Ti{NB(NAr′CH)<sub>2</sub>}Cl<sub>2</sub>(py)<sub>3</sub> (Ar′ = 2,6-C<sub>6</sub>H<sub>3</sub><sup>i</sup>Pr<sub>2</sub>) with Li<sub>2</sub>N<sub>2</sub><sup>R</sup>N<sup>Me</sup> (N<sub>2</sub><sup>R</sup>N<sup>Me</sup> = MeN(CH<sub>2</sub>CH<sub>2</sub>NR)<sub>2</sub>) or Li<sub>2</sub>N<sub>2</sub>N<sup>py</sup> (N<sub>2</sub>N<sup>py</sup> = (2-C<sub>5</sub>H<sub>4</sub>N)CMe(CH<sub>2</sub>NSiMe<sub>3</sub>)<sub>2</sub>) afforded the borylimides Ti(N<sub>2</sub><sup>R</sup>N<sup>Me</sup>){NB(NAr′CH)<sub>2</sub>}(py) (R = SiMe<sub>3</sub> (<b>9</b>), Ar<sup>F</sup> (<b>10</b>), or <sup>i</sup>Pr (<b>11</b>)) and Ti(N<sub>2</sub>N<sup>py</sup>){NB(NAr′CH)<sub>2</sub>}(py) (<b>21</b>). Compounds <b>9</b> and <b>10</b> reacted with ArCCH (Ar = Tol or Ar<sup>F</sup>) via [2 +
2] cycloaddition to form the azatitanacyclobutenes Ti(N<sub>2</sub><sup>R</sup>N<sup>Me</sup>){N{B(NAr′CH)<sub>2</sub>}C(H)C(Ar)}.
In the case of R = Ar<sup>F</sup> these underwent subsequent intramolecular
C–F bond cleavage/C–C coupling processes. Reaction of <b>11</b> and <b>21</b> with TolCCH also formed azatitanacyclobutenes,
whereas Ar<sup>F</sup>CCH formed borylamide-acetylides via a C–H
bond activation process which is endergonic in the case of TolCCH. On
heating, these kinetic products rearranged via alkyne elimination
to form the corresponding azatitanacyclobutenes as the thermodynamic
outcomes
