Synthesis, Structures, and Catalytic Properties of Dinuclear Iridium(I) Complexes with a Hexadentate Macrocyclic Diamine‐Tetracarbene Ligand

摘要

> Two dinuclear macrocyclic Ir I NHC complexes, [Ir ₂ (L 1 )(COD) ₂ ](PF ₆ ) ₂ ( 1 , COD = 1,5‐cyclooctadiene) and [Ir ₂ Cl(L 1 )(COD)]Cl ( 2 ), were prepared by the reaction between [{IrCl(COD)} ₂ ] and macrocyclic N‐heterocyclic carbene (NHC) ligand precursor (H ₄ L 1 )(PF ₆ ) ₄ containing four benzimidazolium and two secondary amino groups. Furthermore, 1 and 2 were carbonylated to give [Ir ₂ (L 1 )(CO) ₄ ](PF ₆ ) ₂ ( 3 ) and [Ir ₂ Cl(L 1 )(CO) ₂ ]Cl ( 4 ), respectively. Notably, 1 can capture the chloride ion to turn itself into 2 with accompanying transformation from cis to trans configuration. Complexes 2 and 4 have unusual five‐coordinate Ir I centers, which are rarely reported for Ir I NHC complexes. The catalytic properties of 1 , 2 , and related mononuclear Ir I complex [Ir(L 2 )(COD)](PF ₆ ) ( 5 , L