title: Synthesis of Cyclic Vinylidene Complexes and Azavinylidene Complexes by Formal [4+2] Cyclization Reactions.
abstract: Reactions of the hydrido-butenylcarbyne complex [OsHCl2(≡CC(PPh3)=CHEt)(PPh3)2]BF4 (1) with nitriles RC≡N (R=2-cyclopropyl-2-oxopropyl, 3-amino-2-oxobutyl) lead to six-membered cyclic vinylidene complexes 3 and azavinylidene complexes 4, that is, iso-osmapyridiniums. Treatment of 1 with excess 2-formylbenzonitrile at reflux temperature in CHCl3 in the presence of air produces a fused osmapyridinium 8, which is first oxidized to the tricyclic iso-osmapyridinium derivative 7, then to iso-osmapyridinium 9, which contains a fused naphthalenone fragment. The conversion of iso-osmapyridinium 9 (with a vinylidene segment) to the iso-osmapyridinium compounds 10 and 11 (with azavinylidene segments) was achieved in the presence of a hydrogen halide, such as HCl or HI. The molecular structures of the complexes synthesized were confirmed by X-ray studies. Moreover, the aromatic stabilization energy and nucleus-independent chemical-shift values of the osmapyridiniums and the strain in the iso-osmapyridinium rings were investigated by DFT calculations.
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials and, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
authors.forename: Jinxiang
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials and, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
authors.forename: Zi-Ao
authors.initials: ZA
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials and, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials and, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China. zh@xmu.edu.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials and, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China. hpxia@xmu.edu.cn.
authors.forename: Haiping
authors.initials: H
authors.lastname: Xia
keywords: azavinylidenes; cycloaddition; iso-metallapyridiniums; metallacycles; vinylidenes