Ruthenium Trispyrazolylborate Complexes. 18. Aminocarbene Ruthenium Complexes Derived from Terminal Alkynes and 2-Aminopyridines

The reactions of RuTp(COD)Cl with the bidentate ligands 2-aminopyridine (apy), 2-amino-4-picoline (apic), and 2-(methylamino)pyridine (mapy) in the presence of terminal alkynes HC⋮CR (R = Ph, n-Bu, C6H9) afford the cyclic aminocarbene complexes RuTp(CCH2R-apy)Cl, RuTp(CCH2R-apic)Cl, and RuTp(CCH2R-mapy)Cl. This reaction proceeds most likely via the intermediacy of both a reactive RuTp complex containing a strained, and thus labile, κ2-N,N-coordinated aminopyridine ligand and a vinylidene intermediate. As side products, except for mapy, the dimeric complexes [RuTp(μ-apy)Cl]2 and [RuTp(μ-apic)Cl]2, featuring bridging aminopyridine ligands, were isolated. Representative complexes were characterized by X-ray crystallography.RuTp(COD)Cl与双齿配体2-氨基吡啶（2-aminopyridine, apy）、2-氨基-4-甲基吡啶（2-amino-4-picoline, apic）以及2-(甲氨基)吡啶（2-(methylamino)pyridine, mapy）在末端炔烃HC≡CR（R = 苯基Ph、正丁基n-Bu、环己烯基C6H9）存在下发生反应，得到环型氨基卡宾配合物RuTp(CCH2R-apy)Cl、RuTp(CCH2R-apic)Cl与RuTp(CCH2R-mapy)Cl。该反应的反应路径极有可能经由两种中间体完成：一种是含有张力型（因此具有不稳定性）κ2-N,N配位氨基吡啶配体的活性RuTp配合物，另一种为亚乙烯基中间体。除使用mapy的反应体系外，其余反应均分离得到以桥联氨基吡啶配体为特征的二聚配合物[RuTp(μ-apy)Cl]2与[RuTp(μ-apic)Cl]2作为副产物。选取代表性配合物通过X射线晶体衍射完成了结构表征。