Photoreduction of Pt(IV) Chloro Complexes: Substrate Chlorination by a Triplet Excited State
详细信息 查看全文
- 作者：Tharushi A. Perera ; Mehdi Masjedi ; Paul R. Sharp
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：July 21, 2014
- 年：2014
- 卷：53
- 期：14
- 页码：7608-7621
- 全文大小：702K
- ISSN：1520-510X
文摘
The Pt(IV) complexes trans-Pt(PEt3)2(Cl)3(R) 2 (R = Cl, Ph, 9-phenanthryl, 2-trifluoromethylphenyl, 4-trifluoromethylphenyl, 3-perylenyl) were prepared by chlorination of the Pt(II) complexes trans-Pt(PEt3)2(R)(Cl) 1 with Cl2(g) or PhICl2. Mixed bromo鈥揷hloro complexes trans,trans-Pt(PEt3)2(Cl)2(Br)(R) (R = 9-phenanthryl, 4-trifluoromethylphenyl), trans,cis-Pt(PEt3)2(Cl)2(Br)(4-trifluoromethylphenyl), trans,trans-Pt(PEt3)2(Br)2(Cl)(R) (R = 9-phenanthryl), and trans,cis-Pt(PEt3)2(Br)2(Cl)(4-trifluoromethylphenyl) were obtained by halide exchange or by oxidative addition of Br2 to 1 or Cl2 to trans-Pt(PEt3)2(R)(Br). Except for 2 (R = Ph, 4-trifluoromethylphenyl), all of the Pt(IV) complexes are photosensitive to UV light and undergo net halogen reductive elimination to give Pt(II) products, trans-Pt(PEt3)2(R)(X) (X = Cl, Br). Chlorine trapping experiments with alkenes indicate a reductive-elimination mechanism that does not involve molecular chlorine and is sensitive to steric effects at the Pt center. DFT calculations suggest a radical pathway involving 3LMCT excited states. Emission from a triplet is observed in glassy 2-methyltetrahydrofuran at 77 K where photoreductive elimination is markedly slowed.