1245928-36-2Relevant academic research and scientific papers
Carboxylate ligand-induced intramolecular C-H bond activation of iridium complexes with N -phenylperimidine-based carbene ligands
Tsurugi, Hayato,Fujita, Shingo,Choi, Gyeongshin,Yamagata, Tsuneaki,Ito, Syoji,Miyasaka, Hiroshi,Mashima, Kazushi
, p. 4120 - 4129 (2010)
We report the synthesis and structure of iridium(I) complexes with N,N′-disubstituted perimidine carbene ligands and halides or carboxylate ligands. Iodo-, chloro-, and acetate-Ir(carbene)(cod) complexes were selectively prepared by changing the bases and silver salts. Intramolecular C-H bond activation to prepare a cyclometalated Ir(III) complex, (C-C:) 2Ir(OAc) (6), where C-C: is a cyclometalated perimidine carbene ligand, was achieved using a carboxylate-ligated iridium complex; otherwise, C-H activation did not proceed. Acetate-Ir(carbene)(cod) (3c) reacted with benzoic anhydride at room temperature to afford benzoate-Ir(carbene)(cod) (3d). A perimidine-carbene- and phenylpyridine-ligated Ir(III) complex, (C -C:)(C-N)Ir(OCOR) (8), where C-N is a cyclometalated phenylpyridine ligand, was isolated in good yield by mixing 3c or 3d and phenylpyridine under reflux in toluene. On the basis of the formation of 1,3-cyclooctadiene from the reaction mixture, we propose the following reaction mechanism for the intramolecular C-H activation: carboxylate-induced C-H bond activation and subsequent pyridine- or carbene-directed C-H bond oxidative addition, followed by the isomerization of 1,5-cyclooctadiene and reaction with carboxylic acid produces (C-C:)(N-C:)Ir(OCOPh). The cyclometalated complex 6 reacts with sodium acetylacetonate to form (C -C:)2Ir(acac) (11), which exhibits phosphorescent emission at max = 555 nm (τ = 0.65 μs, φPL = 0.0018) in CH2Cl2 solution at room temperature.
