Synthesis and Reactivity Study of Metallaindole Complexes (M = Ru and Os) with a Fused Metallacyclopropene Unit

Novel metallaindole complexes with a fused metallacyclopropene unit have been obtained from the reactions of MCl2(PPh3)3 (M = Ru, Os) with 2-(octyn-1-yl)aniline. A dinuclear amino- and alkyne-coordinated Ru complex has been isolated and characterized, which can be oxidized to ruthenaindole. The ruthenaindole can undergo electrophilic substitution with NCS on both benzo and alkenyl units, as well as dearomatization-aromatization through an acid–base reaction. While the osmaindole is also reactive toward electrophilic substitution, it is stable toward HBF4 or HPF6. This work demonstrates a comprehensive study of ruthenaindole and osmaindole complexes.