Indacyclopentadienes and Aromatic Indacyclopentadienyl Dianions: Synthesis and Characterization

• Published in: Chemistry : a European journal 2019-03, Vol.25 (16), p.4218-4224
• Main Authors: Zhang, Yongliang, Yang, Zhenqiang, Zhang, Wen‐Xiong, Xi, Zhenfeng
• Format: Article
• Language: English
• Subjects: Anions; aromatic indacyclopentadienyl dianions; butadienes; Chemical synthesis; Chemistry; Crystal structure; indacyclopentadienes; Indium; Lithium; metalloaromatics; Organometallic compounds; Structural analysis; Theoretical analysis
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201806356

A series of unprecedented metallacycles of indium, including indacyclopentadienes (2), spiro indacyclopentadienes (3), aromatic indacyclopentadienyl dianions with an In−Li bond (4), and aromatic indacyclopentadienyl dianions with an In−In bond (5), were synthesized and structurally characterized by single‐crystal X‐ray structural analysis for the first time. Both indacyclopentadienes 2 and 3 were synthesized by reaction of 1,4‐dilithio‐1,3‐butadienes with InCl3. Structural transformations between 2 and 3 were observed. Reduction of indacyclopentadienes 2 with an excess amount of lithium afforded aromatic indacyclopentadienyl dianions 4 with an In−Li bond or 5 with an In−In bond, respectively, depending on the substituents on the ring. The aromatic character of 4 and 5 was confirmed by both experimental measurements and theoretical analysis. In da cycle: The first synthesis and structural analysis of a series of metallacycles of indium, including indacyclopentadienes, spiro indacyclopentadienes, aromatic indacyclopentadienyl dianions with an In−Li bond, and aromatic indacyclopentadienyl dianions with an In−In bond have been realized (see scheme).