N-arylammonio- and N-pyridinium-substituted derivatives of dodecahydro-closo-dodecaborate(2-)

We report two methods for preparing N-arylammonio, N-pyridyl and N-arylamino dodecaborates: heating of the tetrabutylammonium salt of dodecahydro-closo-dodecaborate(2-) with aryl and pyridyl amines, or nucleophilic attack of [closo-B12H11NH2]2− on a strongly deactivated aromatic system. With aryl amines we obtained [1-closo-B12H11N(R1)2C6H5]− (R1 = H, CH3). With 4-(dimethylamino)pyridine, [1-closo-(B12H11NC5H4)-4-N(CH3)2]−, with a bond between the boron and the pyridinium nitrogen, was obtained. A presumable mechanism for this kind of reactions is reported. By nucleophilic substitution, two products, [1-closo-(B12H11NHC6H3)-3,4-(CN)2]2− and [1-closo-(B12H11NHC6H2)-2-(NO2)-4,5-(CN)2]2−, were formed with 4-nitrophthalonitrile and 1-chloro-2,4-dinitrobenzene gave [1-closo-(B12H11NHC6H3)-2,4-(NO2)2]2−. For [1-closo-B12H11N(CH3)2C6H5]− and [1-closo-(B12H11NHC6H3)-2,4-(NO2)2]2− single crystal X-ray structures were obtained.

N-ammonio and arylamino dodecaborates were synthesized by heating of the tetrabutylammonium salt of dodecahydro-closo-dodecaborate(2-) with aryl amines, or nucleophilic attack of [closo-B12H11NH2]2− on a strongly deactivated aromatic system. With 4-(dimethylamino)pyridine, a pyridinium derivative, [closo-B12H11NC5H4N(CH3)2]−, with a bond between the boron and the pyridinium nitrogen, was obtained.Figure optionsDownload as PowerPoint slide