Design of Sterically Demanding, Electron-Rich Carbene Ligands with the Perimidine Scaffold

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• 作者：Patrick Bazinet ; Tiow-Gan Ong ; Julie S. O'Brien ; Nathalie Lavoie ; Eleanor Bell ; Glenn P. A. Yap ; Ilia Korobkov ; Darrin S. Richeson
• 刊名：Organometallics
• 出版年：2007
• 出版时间：May 21, 2007
• 年：2007
• 卷：26
• 期：11
• 页码：2885 - 2895
• 全文大小：267K
• 年卷期：v.26,no.11(May 21, 2007)
• ISSN：1520-6041

文摘

A family of N,N'-disubstituted perimidinium cation salts were employed as precursors to persistentmonomeric carbenes with novel molecular architectures and electronic structures. Depending on thesubstituents, reaction of these 1,3-disubstituted perimidinium cations with LiN(SiMe₃)₂ led either todeprotonation and generation of new carbenes or to enetetramines. In addition to spectroscopiccharacterization, crystallographic analysis of C₁₀H₆(ⁱPrN)₂C (10), C₁₀H₆(ⁱPrN)(Me₃CCH₂N)C (11), {C₁₀H₆[N(3,5-Me₂C₆H₃)]₂C}₂ (13), and C₁₀H₆(ⁱPrN)(3,5-Me₂C₆H₃N)C (14) definitively confirmed the nature ofthese species. The mixed benzyl/cycloheptyl-substituted carbene C₁₀H₆(cyclo-C₇H₁₃N)(p-MeC₆H₄CH₂N)C(17) was observed to undergo dimerization upon heating to yield both cis and trans isomers of theenetetramine {C₁₀H₆(cyclo-C₇H₁₃N)(p-MeC₆H₄CH₂N)C}₂, (17)₂. Rhodium complexes of these perimidine-based carbenes were accessed via reactions with either monomeric carbene or enetetramine. Spectroscopicand crystallographic analysis of these rhodium-carbene complexes revealed the sterically demandingnature of the carbene ligands, which is manifested in the observation of hindered Rh-C_carbene bond rotationand through %V_bur measurements, and their exceptional electron-donating ability.