Bertocco Philipp, Derendorf Janis, Jenne Carsten, Kirsch Christoph
Fakultät für Mathematik und Naturwissenschaften, Anorganische Chemie, Bergische Universität Wuppertal , Gaußstr. 20, 42119 Wuppertal, Germany.
Inorg Chem. 2017 Mar 20;56(6):3459-3466. doi: 10.1021/acs.inorgchem.6b03006. Epub 2017 Feb 27.
The partly halogenated and N-alkylated closo-dodecaborates [BClHN(propyl)] and [BBrHNR] (R = ethyl-pentyl) were prepared by alkylation of [BHNH] and subsequent halogenation with elemental chlorine or N-bromosuccinimide. Simple metathesis reactions yielded the [HNMe], [Cmim], [NBu], and Na salts, which were characterized by heteronuclear NMR and IR spectroscopy as well as electrospray ionization mass spectrometry. The crystal structures of the salts [HNMe][BBrHN(ethyl)]·CHCN, [HNMe][BBrHN(propyl)], Na[BBrHN(butyl)], and [HNMe][BClHN(propyl)]·CHCN were determined by single-crystal X-ray diffraction. The [Cmim] salts are thermally stable to temperatures higher than 300 °C. The melting points are between 57 and 80 °C, which classify the [Cmim] salts of [BClHN(propyl)] and [BBrHNR] (R = propyl-pentyl) as ionic liquids. The anions are oxidized only at potentials higher than 2 V versus Fc as determined by cyclic voltammetry. The solubility of the sodium salts in CHCl solution was determined by NMR spectroscopy. With the increasing length of the alkyl chain attached to the ammonio group the solubility is significantly enhanced. A solubility up to 125 mmol/L for Na[BBrHN(pentyl)] in dichloromethane was determined. In addition, the trialkylation of the perchlorinated anion [BClNH] was investigated in detail. A Hofmann elimination was observed to occur at higher temperatures, when alkyl groups with β-hydrogen atoms were introduced. Organic substituents without β-hydrogen atoms gave more stable compounds; however, trialkylation proved to be difficult presumably due to steric hindrance. The crystal structure of the byproduct [PPh][BClN(propargyl)] was determined.
部分卤代和N - 烷基化的闭式十二硼酸盐[BClHN(丙基)]和[BBrHNR]（R = 乙基 - 戊基）通过[BHNH]的烷基化以及随后用元素氯或N - 溴代琥珀酰亚胺进行卤化反应制备而成。简单的复分解反应生成了[HNMe]、[Cmim]、[NBu]和钠盐，通过异核核磁共振、红外光谱以及电喷雾电离质谱对其进行了表征。通过单晶X射线衍射确定了盐[HNMe][BBrHN(乙基)]·CHCN、[HNMe][BBrHN(丙基)]、Na[BBrHN(丁基)]和[HNMe][BClHN(丙基)]·CHCN的晶体结构。[Cmim]盐在高于300℃的温度下热稳定。熔点在57至80℃之间，这将[BClHN(丙基)]和[BBrHNR]（R = 丙基 - 戊基）的[Cmim]盐归类为离子液体。通过循环伏安法测定，阴离子仅在相对于Fc高于2 V的电位下被氧化。通过核磁共振光谱测定了钠盐在CHCl溶液中的溶解度。随着连接到铵基上的烷基链长度增加，溶解度显著提高。测定了Na[BBrHN(戊基)]在二氯甲烷中的溶解度高达125 mmol/L。此外，还详细研究了全氯阴离子[BClNH]的三烷基化反应。当引入具有β - 氢原子的烷基时，在较高温度下观察到霍夫曼消除反应发生。没有β - 氢原子的有机取代基生成了更稳定的化合物；然而，由于空间位阻，三烷基化反应被证明是困难的。确定了副产物[PPh][BClN(炔丙基)]的晶体结构。
