Tetracarba-nido-hexa-, -octa, and -decaborane derivatives. NMR study and DFT calculations

•Calculations of indirect nuclear spin–spin coupling constants of carbon-rich carboranes work very well.•Calculations of indirect nuclear spin–spin coupling constants support experimental NMR studies for structural assignments.•Calculated 57Fe–57Fe indirect spin–spin coupling constants predict Fe–Fe interactions.•The synthesis of peralkylated 2,6,8,10-tetracarba-nido-decaboranes has been re-investigated.

6-Ethyl-1,2,3,4,5-pentamethyl-2,3,4,5-tetracarba-nido-hexaborane(6), 1,2,3,4-tetraethyl-5,6,7,8-tetracarba-nido-octaborane(8), its bis-Fe(CO)3 complex, and decaalkyl-2,6,8,10-tetracarba-nido-decaboranes(10) were characterized by multinuclear magnetic resonance methods (11B, 13C NMR spectroscopy, and heteronuclear 13C{11B} decoupling experiments). Particular attention was given to measure spin–spin coupling constants J(13C,11B). These and other NMR parameters were compared with calculated data, based on optimized gas phase geometries on the B3LYP/6-311 + G(d,p) level of theory, and reasonable agreement was found.

Graphical abstractReduction of peralkylated 1,5-dicarba-closo-pentaborane(5) to its dianion, oxidative coupling leads to “classical” hexaboradamantane, which irreversibly rearranges into the 2,6,8,10-tetracarba-nido-decaborane(10).Figure optionsDownload full-size imageDownload as PowerPoint slide