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Bavi M, Nabavizadeh SM, Hosseini FN, Niknam F, Hamidizadeh P, Hoseini SJ, Raoof F, Abu-Omar MM. Ligand-Mediated C-Br Oxidative Addition to Cycloplatinated(II) Complexes and Benzyl-Me C-C Bond Reductive Elimination from a Cycloplatinated(IV) Complex. ACS OMEGA 2020; 5:28621-28631. [PMID: 33195914 PMCID: PMC7658948 DOI: 10.1021/acsomega.0c03573] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 09/01/2020] [Indexed: 06/11/2023]
Abstract
Reaction of the Pt(II) complexes [PtMe2(pbt)], 1a, (pbt = 2-(2-pyridyl)benzothiazole) and [PtMe(C^N)(PPh2Me)] [C^N = deprotonated 2-phenylpyridine (ppy), 1b, or deprotonated benzo[h]quinoline (bhq), 1c] with benzyl bromide, PhCH2Br, is studied. The reaction of 1a with PhCH2Br gave the Pt(IV) product complex [PtBr(CH2Ph)Me2(pbt)]. The major trans isomer is formed in a trans oxidative addition (2a), while the minor cis products (2a' and 2a″) resulted from an isomerization process. A solution of Pt(II) complex 1a in the presence of benzyl bromide in toluene at 70 °C after 7 days gradually gave the dibromo Pt(IV) complex [Pt(Br)2Me2(pbt)], 4a, as determined by NMR spectroscopy and single-crystal XRD. The reaction of complexes 1b and 1c with PhCH2Br gave the Pt(IV) complexes [PtMeBr(CH2Ph)(C^N)(PPh2Me)] (C^N = ppy; 2b; C^N = bhq, 2c), in which the phosphine and benzyl ligands are trans. Multinuclear NMR spectroscopy ruled out other isomers. Attempts to grow crystals of the cycloplatinated(IV) complex 2b yielded a previously reported Pt(II) complex [PtBr(ppy)(PPh2Me)], 3b, presumably from reductive elimination of ethylbenzene. UV-vis spectroscopy was used to study the kinetics of reaction of Pt(II) complexes 1a-1c with benzyl bromide. The data are consistent with a second-order SN2 mechanism and the first order in both the Pt complex and PhCH2Br. The rate of reaction decreases along the series 1a ≫ 1c > 1b. Density functional theory calculations were carried out to support experimental findings and understand the formation of isomers.
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Affiliation(s)
- Marzieh Bavi
- Professor Rashidi
Laboratory of Organometallic Chemistry, Department of Chemistry, College
of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - S. Masoud Nabavizadeh
- Professor Rashidi
Laboratory of Organometallic Chemistry, Department of Chemistry, College
of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | | | - Fatemeh Niknam
- Professor Rashidi
Laboratory of Organometallic Chemistry, Department of Chemistry, College
of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - Peyman Hamidizadeh
- Professor Rashidi
Laboratory of Organometallic Chemistry, Department of Chemistry, College
of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - S. Jafar Hoseini
- Professor Rashidi
Laboratory of Organometallic Chemistry, Department of Chemistry, College
of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - Fatemeh Raoof
- Professor Rashidi
Laboratory of Organometallic Chemistry, Department of Chemistry, College
of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - Mahdi M. Abu-Omar
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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The history of organoplatinum chemistry in Iran: 40-year research. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2020. [DOI: 10.1007/s13738-020-01892-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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