Carbaundecaborane

The preparation of a series of aminecarboranes of the type BioHi2CNH2R from decaborane and alkyl isocyanides has been reported. A more convenient preparation of this class of aminecarboranes, which gives the parent member B10H12CNH3, has also been reported. Procedures for preparation of the aminecarboranes, their methylation, and subsequent deamination of the C-(trialkylamine) carbaundecaborane(12) are described here. 

C-(Trimethylamine)carbaundecaborane(12) is a colorless crystalline solid. It is insoluble in water and moderately soluble in polar organic solvents. 

C -(Dimethylpropylamine)carbaundecaborane(12) is a white crystalline solid, m.p. 191-192°. It is very soluble in acetone and tetrahydrofuran, slightly soluble in chloroform and methanol, and insoluble in benzene and water. The infrared spectrum (Nujol and hexachlorobutadiene mulls) contains major absorption bands at 2988(m), 2561(vs), 1481(m), 1472(m), 1414(m), 1130(m), 1035(m), and 934(m) cm. h The proton nuclear magnetic resonance spectrum (acetone-de solution) exhibits... 

Deamination of C-(trialkylamine)carbaundecaborane(12) derivatives to the carborane anion BjoHiaCH" can be accomplished with sodium metal or sodium hydride in tetrahydrofuran solution. A procedure using sodium metal is described here to illustrate this general reaction. The properties of the cesium and tetramethylammonium salts of the BioHi2CH anion are given. 

The C-(trimethylamine)carbaundecaborane(12) (9.57 g., 0.05 mole) is placed in the reaction flask, and 250 ml. of dry tetrahydrofuran is added. Sodium metal (4.59 g., 0.2 mole) is added to the reaction flask, and after gas evolution has ceased, the oil bath is heated to 75-80° with vigorous stirring of the reaction mixture. A thick white precipitate will develop... 

The preparation and purification of C-(trimethj lamine)carbaundecaborane(J2) is described in Procedure B of this synthesis. 

---