Entrapment of THF‐Stabilized Iridacyclic Ir^III Silylenes from Double H−Si Bond Activation and H₂ Elimination.

Binh, Dang Ho; Hamdaoui, Mustapha; Fischer‐Krauser, Diane; Karmazin, Lydia; Bailly, Corinne; Djukic, Jean‐Pierre

The reaction of H3SiR (R=Ph, nBu) with cationic η5‐C5Me5‐ (Cp*) and benzo[h]quinolinyl‐based iridacycle [1 b] gives rise to new [(IrH)→SiRH2] adducts. In the presence of THF these adducts readily undergo elimination of H2 gas at subambient temperature to form THF‐stabilized metallacyclic IrIII silylene complexes, which were characterized in situ by NMR spectroscopy, trapped in minute amounts by reactive crystallization, and structurally characterized by XRD. Theoretical investigations (static DFT‐D reaction‐energy profiling, ETS‐NOCV) support the promoting role of THF in the H2 elimination step and the consolidation of the Ir‐to‐Si interaction in the spontaneous (ΔG<0) formation of Ir silylenes in the presence of THF. Mechanistic insights indicate that the Ir silylene species arising from the [1 b] /phenylsilane system are relevant catalytic species in the hydrodefluorination of fluoroalkanes. It′s a trap! Treatment of a Cp*‐bearing iridacycle with phenylsilane in the presence of THF yields a THF‐stabilized cationic IrIII silylene complex, which was characterized in situ by NMR spectroscopy, trapped by reactive crystallization, and structurally characterized (see figure). It exhibits catalytic activity in the hydrodefluorination of fluoroalkanes. Cp*: η5‐C5Me5.

SILYLENES; TRANSITION metal complexes; CATIONS; NUCLEAR magnetic resonance spectroscopy; X-ray diffraction; ELECTROPHILES

Chemistry - A European Journal, 2018, Vol 24, Issue 66, p17577

0947-6539

Academic Journal

10.1002/chem.201804048