Cationic (η⁵‑C₅Me₄R)Rh^III Complexes with Metalated Aryl Phosphines Featuring η⁴‑Phosphorus plus Pseudo-Allylic Coordination

In this contribution we study experimentally and computationally some electrophilic cationic (η⁵-C₅Me₄R)­Rh^III complexes containing a cyclometalated bis­(aryl) phosphine, PR′Ar₂. The phosphine Ar groups feature methyl substituents at the 2- and 6-positions of the aromatic rings, allowing the formation of the complexes [(η⁵-C₅Me₄R)­Rh­(C^∧P)]⁺ (<b>3</b>^<b>+</b>), where the metalated phosphine exhibits η⁴ coordination to rhodium through phosphorus and the carbon atoms of the adjoining pseudo-allylic functionality. The solution and solid-state structures of complexes <b>3</b>^<b>+</b> have been studied by NMR and X-ray methods and their electronic properties investigated with the aid of DFT calculations. The Lewis acid behavior of complexes <b>3</b>^<b>+</b> has also been addressed, concentrating on reactivity toward CO, H₂ ,and hydrosilanes. Some catalytic Si–H/Si–D exchange and hydrosilylation reactions are also reported

Synthesis and Characterization of [Ir(<i>Acac^BiMs</i>)(COD)] and [<i>cis</i>-Ir(<i>Acac^BiMs</i>)₂(COE-OH)]

The reaction of dinuclear complex [IrCl­(COD)]₂ (COD = 1,5-cyclooctadiene) with 1 equiv of 1,3-dimesitylpropane-1,3-dione (H-<i>Acac</i>^<i>BiMs</i>) and an excess of triethylamine in benzene or dichloromethane at room temperature results in the formation of β-diketonate complex [Ir­(<i>Acac</i>^<i>BiMs</i>)­(COD)], <b>1</b>. Further, compound <b>1</b> reacts with an equivalent of H-<i>Acac</i>^<i>BiMs</i> in dichloromethane under atmospheric conditions to give the new complex with the formula [<i>cis</i>-Ir­(<i>Acac</i>^<i>BiMs</i>)₂(COE-OH)], <b>2</b> (COE-OH = σ,π-hydroxyenediyl), through a formal insertion of a hydroxyl group into a COD ring. All compounds were characterized by melting point, analytical data, and IR and NMR spectroscopy. Additionally, an X-ray crystallographic study was undertaken to corroborate the structure of both complexes

Synthesis and Characterization of [Ir(<i>Acac^BiMs</i>)(COD)] and [<i>cis</i>-Ir(<i>Acac^BiMs</i>)₂(COE-OH)]

The reaction of dinuclear complex [IrCl­(COD)]₂ (COD = 1,5-cyclooctadiene) with 1 equiv of 1,3-dimesitylpropane-1,3-dione (H-<i>Acac</i>^<i>BiMs</i>) and an excess of triethylamine in benzene or dichloromethane at room temperature results in the formation of β-diketonate complex [Ir­(<i>Acac</i>^<i>BiMs</i>)­(COD)], <b>1</b>. Further, compound <b>1</b> reacts with an equivalent of H-<i>Acac</i>^<i>BiMs</i> in dichloromethane under atmospheric conditions to give the new complex with the formula [<i>cis</i>-Ir­(<i>Acac</i>^<i>BiMs</i>)₂(COE-OH)], <b>2</b> (COE-OH = σ,π-hydroxyenediyl), through a formal insertion of a hydroxyl group into a COD ring. All compounds were characterized by melting point, analytical data, and IR and NMR spectroscopy. Additionally, an X-ray crystallographic study was undertaken to corroborate the structure of both complexes