New Aspects of the Synthesis of closo-Dodecaborate Nitrilium Derivatives [B12H11NCR]− (R = n-C3H7, i-C3H7, 4-C6H4CH3, 1-C10H7): Experimental and Theoretical Studies

Abstract

The preparation of novel nitrilium derivatives of closo-dodecaborate anion [B12H11NCR]−, R = n-C3H7, i-C3H7, 4-C6H4CH3, 1-C10H7 is described. Target compounds were obtained in good yields (up to 73%). The synthesis of target borylated nitrilium derivatives was characterised by the simplicity of the chemical apparatus and the absence of the necessity for the purification of desired compounds. The crystal structures of previously obtained [B12H11NCCH3]− and novel [B12H11NCC3H7]− were established with the help of X-ray structure analysis. DFT-analysis of several nitrilium derivatives [B12H11NCR]−, R = CH3, C3H7, 4-CH3C6H4 was carried out. The main peculiarities of the C≡N bond of the exo-polyhedral substituent were revealed in terms of bond lengths, bond orders and atomic charges. The LUMO orbitals of the systems considered were examined for understanding of the electrophilic nature of the nitrilium derivatives of the closo-dodecaborate anion.

Reduction of Triple Bond in [B12H11NCR]− Anions by Lithium Aluminum Hydride: A Novel Approach to the Synthesis of N-Monoalkylammonio-Substituted closo-Dodecaborates

“…Two absorption bands in the ranges 3290-3230 and 3206-3195 cm −1 correspond to the valence vibrations of the N-H bonds of the ammonium group. Also, the absorption bands of the C≡N bond in the region 2330-2300 cm −1 are absent in the spectra of the reduction products [60].…”

“…For a long time, it was believed that these derivatives could not be isolated in their non-hydrolyzed form [58]. However, a new synthesis method involving the use of absolute organic solvents allows the preparation of these compounds in pure form and for further modifications [60].…”