Reactivity of an Unsaturated Iridium(III) Phosphoramidate Complex, [Cp*Ir{κ<sup>2</sup>‑<i>N</i>,<i>O</i>}][BAr<sup>F</sup><sub>4</sub>]

The three-legged piano stool complex [Cp*Ir­(κ<sup>2</sup>-<i>N</i>,<i>O</i>-Xyl­(<u>N</u>)­P­(<u>O</u>)­(OEt)<sub>2</sub>)­(Cl)], [<b>1</b>] (Cp* = η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>, Xyl = 2,6-dimethylphenyl), was prepared from reaction of 0.5 equiv of [Cp*IrCl<sub>2</sub>]<sub>2</sub> with the sodiated phosphoramidate ligand Na­[Xyl­(N)­P­(O)­(OEt)<sub>2</sub>]. Treatment of [<b>1</b>] with Na­[BAr<sup>F</sup><sub>4</sub>], [BAr<sup>F</sup><sub>4</sub>] = [B­(C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>)<sub>4</sub>], led to the formation of the 16-electron two-legged piano stool species [Cp*Ir­(κ<sup>2</sup>-<i>N</i>,<i>O</i>-Xyl­(<u>N</u>)­P­(<u>O</u>)­(OEt)<sub>2</sub>)]­[BAr<sup>F</sup><sub>4</sub>], [<b>2</b>]­[BAr<sup>F</sup><sub>4</sub>], which was characterized in both solution and solid state. Reactivity screening revealed that complex [<b>2</b>]­[BAr<sup>F</sup><sub>4</sub>] undergoes addition of a variety of Lewis bases to afford the corresponding 18-electron adducts with concomitant movement of the phosphoramidate ligand from κ<sup>2</sup>-<i>N</i>,<i>O</i> to κ<sup>1</sup>-<i>N</i>, [Cp*Ir­(κ<sup>1</sup>-<i>N</i>-Xyl­(<u>N</u>)­P­(O)­(OEt)<sub>2</sub>)­(L)<sub>2</sub>]­[BAr<sup>F</sup><sub>4</sub>]; L = CN<i>t</i>Bu, [<b>3</b>]­[BAr<sup>F</sup><sub>4</sub>], CNXyl, [<b>4</b>]­[BAr<sup>F</sup><sub>4</sub>], MeCN, [<b>7</b>]­[BAr<sup>F</sup><sub>4</sub>], bipy, [<b>8</b>]­[BAr<sup>F</sup><sub>4</sub>]; bipy = 2,2′-bipyridine. For complex [<b>7</b>]­[BAr<sup>F</sup><sub>4</sub>], variable-temperature <sup>31</sup>P­{<sup>1</sup>H} NMR spectroscopy revealed that MeCN coordination was reversible between 238 and 190 K. To probe E–H (E = Si, B) bond activation, complex [<b>2</b>]­[BAr<sup>F</sup><sub>4</sub>] was treated with H<sub>2</sub>SiPh<sub>2</sub>, providing the five-membered iridacycle [Cp*Ir­(κ<sup>2</sup>-<i>N,Si</i>-Xyl­(<u>N</u>)­P­(O<u>Si</u>Ph<sub>2</sub>)­(OEt)<sub>2</sub>)]­[BAr<sup>F</sup><sub>4</sub>], [<b>9</b>]­[BAr<sup>F</sup><sub>4</sub>], via geminal Si–H activation, while use of mesityl borane, H<sub>2</sub>BMes (Mes = 2,4,6-trimethylphenyl), afforded the six-membered phosphoramidate-stabilized borane complex [Cp*Ir­(κ<sup>3</sup>-<i>N,H,H</i>-Xyl­(<u>N</u>)­P­(OB<u>H</u><sub><u>2</u></sub>Mes)­(OEt)<sub>2</sub>)]­[BAr<sup>F</sup><sub>4</sub>], [<b>10</b>]­[BAr<sup>F</sup><sub>4</sub>]. Complexes [<b>3</b>]­[BAr<sup>F</sup><sub>4</sub>] and [<b>9</b>]­[BAr<sup>F</sup><sub>4</sub>] were additionally characterized by single-crystal X-ray diffraction.