Diastereoselective Photoreaction of Ir(III) Amine Complexes for Generation of New Multidentate Ligands in situ via a Postcoordinated Interligand‐Coupling Strategy

Abstract

Main observation and conclusionThe diastereoselective photoreactions of Ir(III)‐amine and Ir(III)‐diamine complexes are observed in the presence of O2. The Ʌ‐[Ir(pq)2(R‐mapy)](PF6) (pq is 2‐phenylquinoline and mapy is 2‐(1‐aminoethyl)pyridine) diastereomer is dehydrogenatively oxidized into imine complex Ʌ‐[Ir(pq)2(mapy‐2H)](PF6) at room temperature, while the Ʌ‐[Ir(pq)2(S‐mapy)](PF6) diastereomer occurs interligand C—N cross‐coupling reaction at 60 °C, affording a new tetradentate complex Ʌ‐[Ir(pq)(S‐pqpe)] (PF6) (pqpe is 2‐phenyl‐N‐(1‐pyridin‐2‐yl)ethyl‐quinolin‐8‐amine). The identical cases are also observed in diamine complexes Ʌ‐[Ir(pq)2(R,R‐chda)](PF6) (chda is 1,2‐diaminocyclohexane), Ʌ‐[Ir(pq)2(R,S‐chda)](PF6), and Ʌ‐[Ir(pq)2(S,S‐chda)](PF6), where the R configuration ligand is dehydrogenatively oxidized into imine, while the S configuration is retentive and the bound nitrogen atom is coupling to the C8 of pq ligand, affording Ʌ‐[Ir(pq)2(chdi)](PF6) (chdi is 1,2‐diiminocyclohexane), Ʌ‐[Ir(pq)(S‐pqchim)](PF6) (pqchim is N‐(2‐iminocyclohexyl)‐2‐phenyl‐ quinolin‐8‐amine), and Ʌ‐[Ir(S,S‐pqchda)](PF6) (pqchda is N',N”‐bis(2‐phenylquinolin‐8‐yl)cyclohexane‐1,2‐diamine), respectively. These provide a new and useful protocol for the synthesis of multidentate ligands in situ via the postcoordinated interligand‐coupling strategy under mild conditions.