Synthesis,characterization and mechanism of formation of 6-substituted nido-B 10 H 13 decaboranes by the opening reaction of closo-decahydrodecaborate [B 10 H 10 ] 2− cage

The synthesis of new 6-LB₁₀H₁₃ (L = ligand) derivatives of decaborane B₁₀H₁₄ with different ligands was achieved by the opening cage reaction of closo-decahydrodecaborate (NH₄)₂B₁₀H₁₀ in the presence of a strong acid (HNO₃ or H₂SO₄) in organic solvents (hexane or benzene derivatives). This reaction was performed by varying different factors: the acid strength, the solvent polarity, the equivalent amounts of (NH₄)₂B₁₀H₁₀ with respect to the acid used (1/4 or 1/6) and the reaction time (30 minutes to 24 hours). Nitric acid forced hexane solvent to play the role of ligand whereas sulfuric acid did not. The reaction of (NH₄)₂B₁₀H₁₀ with HNO₃ in hexane produced 6-(C₆H₁₃)B₁₀H₁₃ and [B₉H₁₃NO₃]⁻. The reaction of (NH₄)₂B₁₀H₁₀ with H₂SO₄ in aromatic solvent L (benzene, toluene, o-xylene and m-xylene) produced 6-LB₁₀H₁₃ and 6-(HO₃SO)B₁₀H₁₃ as major products with B₆H₁₀ and [B₉H₁₄]⁻ as minor products. All these derivatives were characterized by ¹¹B NMR, ¹H NMR, ¹³C NMR and negative ESI. This study elucidated some facts and ideas that were not clear concerning the mechanism of opening reaction of closo-[B₁₀H₁₀]²⁻.