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

The reaction of NMe4[N2B10H9] with a series of bidentate diamino ligands L was studied in order to prepare dicage derivatives (NMe4)2[B10H9LB10H9]. The ligands used are: NH2(CH2)nNH2 (n = 2, 3, 4, 6, 9, and 12), 1,2-diaminocyclohexane, 1,8-napthalenediamine, and 1,10-phenanthroline. The reaction was carried out for 15 h at 120 °C, under argon inert atmosphere. When the ligand L used is flexible such as NH2(CH2)nNH2, the reaction yielded the monocage derivatives NMe4[B10H9NH2(CH2)nNH2], while a mixture of the dicage (NMe4)2[B10H9LB10H9] and the monocage NMe4[B10H9L] was formed when the ligand L is rigid such as 1,2-diaminocyclohexane. On the other hand, the reaction of NMe4[N2B10H9] with the rigid ligands 1,10-phenanthroline and 1,8-naphthalenediamine yielded only the monocage derivative due to steric hindrance and electronic effect. All these new closo-[B10H10]2− derivatives were obtained in pure form with acceptable yields and were characterized by 11B NMR, 1H NMR, 13C NMR, negative ESI and TLC.