C-NH2 bond formation mediated by iridium complexes.

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry

Background:

• The amido-bridged trinuclear iridium complex [{Ir(μ-NH2 )(tfbb)}3 ] (tfbb=tetrafluorobenzobarrelene) is a key starting material.
• Understanding the reactivity of such complexes is crucial for developing new synthetic methodologies.

Purpose of the Study:

• To investigate the transformation of [{Ir(μ-NH2 )(tfbb)}3 ] in the presence of phosphanes (PR3).
• To explore an alternative synthetic route to the resulting mononuclear compounds.
• To elucidate the reaction mechanisms using Density Functional Theory (DFT) studies.

Main Methods:

• Reaction of [{Ir(μ-NH2 )(tfbb)}3 ] with phosphanes (PR3).
• Reaction of [Ir(Cl)(tfbb)(PMePh2 )2] with ammonia and phosphane.
• Density Functional Theory (DFT) calculations.

Main Results:

• The trinuclear complex transforms into mononuclear compounds [Ir(1,2-η(2) -4-κ-C12 H8 F4 N)(PR3 )3] through C-N coupling.
• An alternative synthesis of these mononuclear compounds was established.
• DFT studies confirmed that both synthetic pathways proceed via nucleophilic attack.

Conclusions:

• The amido moiety of the trinuclear complex undergoes nucleophilic attack on a coordinated diolefin, leading to C-N coupling.
• Ammonia can directly attack the coordinated tetrafluorobenzobarrelene (tfbb) ligand in an alternative synthetic route.
• Nucleophilic attack is the key mechanistic step in these iridium-mediated transformations.