The reaction of closo-diazononahydrodecaborate [1-N2B10H9]− with bidentate diamino ligands L: A new route to dicage derivatives [B10H9LB10H9]2−

► NMe4[N2B10H9] reacts with diamino ligands L at 120 °C after 15 h under argon. ► When L is flexible, the reaction yielded the monocage NMe4[B10H9L]. ► When L′ is a good nucleophile and not flexible, formation of dicages is observed. ► Chelating atoms of L′ should not hinder each other upon binding to the boron cages. ► Some L′ hinders the formation of dicages due to steric and electronic effects.