Deprotonation of the carbaborane nido-7-NH2But-7-CB10 H12: crystal structures of nido-7-NH2But-7-CB10 H12 and [NEt3(CH2Ph)][ nido-7-NHBut-7-CB10H12 ]

Abstract

The crystal structure of nido-7-NH ₂ Bu ^t -7-CB ₁₀ H ₁₂ 1 has been determined by X-ray diffraction. The compound crystallises in the orthorhombic space group Pbca [a = 10.507(5), b = 13.805(6), c = 18.093(9) Å]. The nido-icosahedral structure was established with two endo-B–H–B and two NH ₂ hydrogen atoms located in Fourier-difference maps and refined. The structure determination is also supported by ¹¹ B-{ ¹ H}– ¹¹ B-{ ¹ H} correlation NMR spectroscopy. A molecular orbital calculation and frontier density analysis of 1 indicated that deprotonation should initially occur at the exo-nitrogen atom. Treatment of 1 with 1 equivalent of LiBu ⁿ , followed by addition of [NEt ₃ (CH ₂ Ph)]Cl, gave [NEt ₃ (CH ₂ Ph)][nido-7-NHBu ^t -7-CB ₁₀ H ₁₂ ] 2 as the only product and single crystals were grown for an X-ray diffraction study. The salt crystallises in the monoclinic space group P2 ₁ /n [a = 10.651(2), b = 11.652(2), c = 20.926(3) Å, β = 101.77(2)°]. The ¹ H, ¹³ C-{ ¹ H} and ¹¹ B-{ ¹ H} NMR spectra of 1 and 2 have also been recorded.