Diverse C鈥揅 Bond-Forming Reactions of Bis(carbene)platinum(II) Complexes

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• 作者：Rachel C. Klet ; Jay A. Labinger ; John E. Bercaw
• 刊名：Organometallics
• 出版年：2012
• 出版时间：September 24, 2012
• 年：2012
• 卷：31
• 期：18
• 页码：6652-6657
• 全文大小：330K
• 年卷期：v.31,no.18(September 24, 2012)
• ISSN：1520-6041

文摘

The platinum(0) complex Pt(PPh₃)₄ catalyzes coupling of the carbene ligands of (CO)₅Cr{C(OMe)(p-MeOC₆H₄)} (1). The stable bis(carbene)platinum(II) complexes Cl₂Pt{C(OMe)(Me)}₂ (3), Br₂Pt{C(OMe)(Me)}₂ (4), and Cl₂Pt{C(OⁱPr)(Me)}₂ (5) can be induced to undergo C鈥揅 coupling reactions by several means. Reduction of 3鈥?b>5 to platinum(0) with cobaltocene results in formation of internal olefins, (E/Z)-2,3-dimethoxybut-2-ene (6) or (E/Z)-2,3-diisopropoxybut-2-ene (7). Reaction of 3鈥?b>5 with PPh₃ yields terminal olefins, 2,3-dimethoxybut-1-ene (13) or 2,3-diisopropoxybut-1-ene (15), along with Cl₂Pt(PPh₃)₂ (12) or Br₂Pt(PPh₃)₂ (14). In contrast, addition of pyridine to 3鈥?b>5 does not effect C鈥揅 coupling; instead, the acyl complexes cis-Cl(py)Pt(COMe){C(OMe)(Me)} (8), cis-Br(py)Pt(COMe){C(OMe)(Me)} (9), and cis-Cl(py)Pt(COMe){C(OⁱPr)(Me)} (10) are obtained, with concomitant formation of alkyl halide. Possible mechanistic pathways for C鈥揅 bond formation are discussed, as well as explanations for the different reactivities observed for pyridine and PPh₃.