Conventional and unconventional alkyne activations by Ru and Os for unprecedented dimetalated quinolizinium complexes.

Two types of unexpected quinolizinium complexes were obtained from the reactions between pyridine-functionalized propargylic alcohol HCCC(OH)(Ph)(CH2(2-py)) (L1) and cis-[M(L^L)2Cl2] (M = Ru, Os; L^L = 1,1-bis(diphenylphosphino)methane (dppm), 2,2′-bipyridine (bpy)). Their molecular structures revealed that L1 can be activated by Ru and Os via the conventional “vinylidene-involving” or unconventional “non-vinylidene-involving” pathways.