Department of Chemistry, Durham University, Durham DH1 3LE, UK.
Inorg Chem. 2012 Jan 2;51(1):290-7. doi: 10.1021/ic201655n. Epub 2011 Dec 19.
The new homoleptic tris-cyclometalated [Ir(C^N)(3)] complexes mer-8, fac-8, and fac-9 incorporating γ-carboline ligands are reported. Reaction of 3-(2,4-difluorophenyl)-5-(2-ethylhexyl)-pyrido[4,3-b]indole 6 with iridium(III) chloride under standard cyclometalating conditions gave the homoleptic complex mer-8 in 63% yield. The X-ray crystal structure of mer-8 is described. The Ir-C and Ir-N bonds show the expected bond length alternations for the differing trans influence of phenyl and pyridyl ligands. mer-8 quantitatively isomerized to fac-8 upon irradiation with UV light. However, heating mer-8 at 290 °C in glycerol led to an unusual regioselective loss of one fluorine atom from each of the ligands, yielding fac-9 in 58% yield. fac-8 is thermally very stable: no decomposition was observed when fac-8 was heated in glycerol at 290 °C for 48 h. The γ-carboline system of fac-8 enhances thermal stability compared to the pyridyl analogue fac-Ir(46dfppy)(3)10, which decomposes extensively upon being heated in glycerol at 290 °C for 2 h. Complexes mer-8, fac-8, and fac-9 are emitters of blue-green light (λ(max)(em) = 477, 476, and 494 nm, respectively). The triplet lifetimes for fac-8 and fac-9 are ~4.5 μs at room temperature; solution Φ(PL) values are 0.31 and 0.22, respectively.
报告了新型全同三-环金属化[Ir(C^N)(3)]配合物 mer-8、fac-8 和 fac-9，它们都含有 γ-咔啉配体。在标准环金属化条件下，将 3-(2,4-二氟苯基)-5-(2-乙基己基)吡啶并[4,3-b]吲哚 6 与三氯化铱反应，以 63%的产率得到全同配合物 mer-8。描述了 mer-8 的 X 射线晶体结构。Ir-C 和 Ir-N 键表现出预期的键长交替，这是由于苯基和吡啶基配体的不同反式影响。mer-8 在紫外光照射下定量异构化为 fac-8。然而，将 mer-8 在 290°C 的甘油中加热导致每个配体从一个氟原子发生不寻常的区域选择性缺失，以 58%的产率得到 fac-9。fac-8 在热上非常稳定：当 fac-8 在甘油中于 290°C 加热 48 小时时，没有观察到分解。与吡啶类似物 fac-Ir(46dfppy)(3)10 相比，fac-8 的 γ-咔啉系统增强了热稳定性，后者在甘油中于 290°C 加热 2 小时时会发生广泛分解。配合物 mer-8、fac-8 和 fac-9 是蓝绿光的发射器（λ(max)(em) = 477、476 和 494nm）。在室温下，fac-8 和 fac-9 的三重态寿命约为 4.5μs；溶液Φ(PL)值分别为 0.31 和 0.22。
