Triphos Iridium(III) Halide Complex Photochemistry: Triphos Arm Dissociation

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• 作者：Andreas Ross ; Paul R. Sharp
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：November 4, 2013
• 年：2013
• 卷：52
• 期：21
• 页码：12645-12654
• 全文大小：472K
• 年卷期：v.52,no.21(November 4, 2013)
• ISSN：1520-510X

文摘

Photolysis of Ir(triphos)X₃ (triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane; X = Cl, Br) yields an insoluble product believed to be oligomeric [Ir(triphos)X₃]_n with bridging triphos and halide ligands. Refluxing pyridine (py) dissolves the insoluble photoproducts ultimately yielding the dangling triphos complexes mer-Ir(魏²-triphos)(py)X₃. Oxidation of the P center of the dangling arm of Ir(魏²-triphos)(py)Cl₃ yields mer-Ir(魏²-P,P-triphosO)(py)Cl₃ (triphosO = MeC(CH₂P(O)Ph₂)(CH₂PPh₂)₂), which was characterized by single-crystal X-ray diffraction. mer-Ir(魏²-triphos)(py)Cl₃ is also formed when Ir(triphos)Cl₃ is photolyzed in the presence of py ( = 26%). Both mer-Ir(魏²-triphos)(py)Cl₃ and mer-Ir(魏²-P,P-triphosO)(py)Cl₃ photoisomerize in pyridine to their thermally unstable fac-isomers. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations suggest triphos ligand arm dissociation occurs along a triplet pathway from an initial Franck鈥揅ondon ligand-field excited state that relaxes to a Jahn鈥揟eller axially distorted octahedral triplet with a long Ir鈥揚 bond. Subsequent triphos arm dissociation yields a distorted trigonal-bipyramidal triplet that undergoes intersystem crossing to a square pyramidal singlet.