Thermally Induced Defluorination during a mer to fac Transformation of a Blue-Green Phosphorescent Cyclometalated Iridium(III) Complex

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• 作者：Yonghao Zheng ; Andrei S. Batsanov ; Robert M. Edkins ; Andrew Beeby ; Martin R. Bryce
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：January 2, 2012
• 年：2012
• 卷：51
• 期：1
• 页码：290-297
• 全文大小：464K
• 年卷期：v.51,no.1(January 2, 2012)
• ISSN：1520-510X

文摘

The new homoleptic tris-cyclometalated [Ir(CN)₃] complexes mer-8, fac-8, and fac-9 incorporating 纬-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鈥揅 and Ir鈥揘 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 掳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 掳C for 48 h. The 纬-carboline system of fac-8 enhances thermal stability compared to the pyridyl analogue fac-Ir(46dfppy)₃10, which decomposes extensively upon being heated in glycerol at 290 掳C for 2 h. Complexes mer-8, fac-8, and fac-9 are emitters of blue-green light (位_max^em = 477, 476, and 494 nm, respectively). The triplet lifetimes for fac-8 and fac-9 are 4.5 渭s at room temperature; solution 桅_PL values are 0.31 and 0.22, respectively.