1,2-Azaborolyls, Isoelectronic Analogues of the Ubiquitous Cyclopentadienyl Ligand: Synthesis of B-Heteroatom-Substituted 1,2-Azaborolyl Complexes and an Assessment of Their Electronic Features


  • We thank Prof. Timothy M. Swager, Dr. Takeshi Shioya, and J. D. Tovar for assistance with the electrochemistry. Support has been provided by Bristol-Myers Squibb, Merck, Novartis, and Pfizer.

  • X-ray crystal structure analysis.


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The substituent on boron allows the electronic nature of the heterocycle of B-heteroatom-substituted (R=H, O, S, N, P, and F) 1,2-azaborolyl complexes to be modulated. Given that 1,2-azaborolyl is isoelectronic with cyclopentadienyl (see scheme), one of the most widely used ligands in organometallic chemistry, it seems likely that the diverse array of compounds synthesized in this study will stimulate the development of applications of η5-(1,2-azaborolyl) ligands in metal-catalyzed processes.