Iridium(I)– and Rhodium(I)–Olefin Complexes\nContaining an α‑Diimine Supporting Ligand

Abstract

Iridium­(I) complexes\nof the type IrX­(olefin)­(α-diimine) (α-diimine\n= 1,4-bis­(2,6-xylyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene; X = Cl,\nI, Me, O₂CCF₃; olefin = ethylene, cyclooctene\n(COE)) were synthesized from the readily available precursor [IrCl­(COE)₂]₂. These complexes display unusual ¹H NMR spectra and have large UV–vis extinction coefficients.\nNOESY and HSQC NMR experiments were used to provide rigorous NMR spectral\nassignments, and IrCl­(C₂H₄)­(α-diimine), <b>1</b>, and IrCl­(COE)­(α-diimine), <b>4</b>, were structurally\ncharacterized by X-ray crystallography. The related rhodium complex\n[RhCl­(α-diimine)]₂, <b>6</b>, was also synthesized\nand characterized by NMR and X-ray crystallography. <b>6</b> was observed to be in equilibrium with RhCl­(C₂H₄)­(α-diimine), <b>7</b>, under an ethylene atmosphere.