In the past few years, a series of progress (Nat. Chem., 2013, 5, 698; Nat. Commun., 2014, 5, 3265; ACIE, 2014, 53, 6232; ACIE, 2015, 54, 3102; ACIE, 2015, 54, 6181) on the project of metallapentalyne have been published. Recently, we found that the metallapentalynes can be easily synthesized. This research has been published on Angew. Chem. Int. Ed. (2015, 54, 7189-7192) entitled “Five-Membered Cyclic Metal Carbyne: Synthesis of Osmapentalynes by the Reactions of Osmapentalene with Allene, Alkyne, and Alkene”.

Synthesis of small cyclic metal carbynes are challenging due to the large angle strain associated with the highly distorted nonlinear triple bonds. Recently, we reported a general and effective route for the synthesis of five-membered cyclic metal carbyne complexes, osmapentalynes, via osmapentalene with a metallcycloproene unit. Such a metallacyclopropene unit can react with allene, alkyne, and alkene to form osmapentalynes. We also found that these novel metalla-aromatics show broad absorption in the ultraviolet-visible-near-infrared region (~700 nm).

On the other hand, calculations done by the group of Jun Zhu revealed that the the sp3-hybridized carbon atom is nucleophilic. In addition, isomerization stabilization energy, nucleus-independent chemical shift, and the anisotropy of the induced current density analysis confirm the aromaticity in the synthesized osmapentalynes. The realization of transforming osmapentalene to osmapentalyne via this general route would not only allow further exploration of metallapentalyne chemistry but also show promising applications of this novel aromatic system with broad absorption band and high molar absorption coefficient.

This research was supported by the National Basic Research Program of China, the National Science Foundation of China and the program for New Century Excellent Talents in University.

URL link for article: http://onlinelibrary.wiley.com/doi/10.1002/anie.201502412/full

Prof. Haiping Xia’s group website: http://chem.xmu.edu.cn/group/hpxia/index.htm