Fourier transform ion cyclotron resonance mass spectrometry has been used to examine the reactions of Si(CH3)3+ with nitrobenzene, TNT, and RDX. With nitrobenzene, the only reaction observed is adduct formation which generates the C6H5NO2Si(CH3)3+ ion. The bimolecular rate constant for the reaction of Si(CH3)3+ with nitrobenzene is measured to be 1.8 × 10-9 cm3 s-1 molecule-1. With TNT, fragmentation and adduct formation were observed. The bimolecular rate constant for the reaction of Si(CH3)3+ with TNT is measured to be 0.85 × 10-9 cm3 s-1 molecule-1. With RDX, the dominant reaction observed is adduct formation, but some fragmentation is seen as a minor reaction pathway. The bimolecular rate constant for the reaction of Si(CH3)3+ with RDX is estimated to be similar to that observed with TNT (∼0.7 × 10-9 cm3 s-1 molecule-1). Collision-induced dissociation experiments performed on both the TNT−Si(CH3)3+ and the RDX−Si(CH3)3+ adducts using off-resonance collisional activation show the same fragmentation pattern that is observed during adduct formation. This fragmentation pattern appears to be a “fingerprint” for both adducts. These reactions appear to be driven by the high affinity of Si for oxygen and the attraction of the Si(CH3)3+ ion to the formal negative charge of oxygen in a nitro group. A reaction coordinate diagram for reactions of RDX with Si(CH3)3+ is derived (from known thermochemistry and ab initio calculations on the reactive intermediates) and its implications are discussed. Reactions of this type could be useful as a detection scheme for common explosives.
傅里叶变换离子回旋共振质谱已被用于研究Si(
CH3)3+与
硝基苯、TNT(三
硝基甲苯)和RDX(
环三亚甲基三硝胺)的反应。与
硝基苯的反应观察到的唯一现象是加合物的形成,生成了C6H5NO2Si( )3+离子。Si( )3+与
硝基苯反应的双分子速率常数测得为1.8 × 10-9 cm3 s-1 molecule-1。与TNT反应时,观察到了碎裂和加合物的形成。Si( )3+与TNT反应的双分子速率常数测得为0.85 × 10-9 cm3 s-1 molecule-1。与RDX反应时,主要观察到的是加合物的形成,但也有一些碎裂作为次要反应途径。Si( )3+与RDX反应的双分子速率常数估计与TNT的观察值相似(约0.7 × 10-9 cm3 s-1 molecule-1)。在TNT−Si( )3+和RDX−Si( )3+加合物上进行的碰撞诱导解离实验(使用非共振碰撞活化)显示,在加合物形成过程中观察到的碎裂模式相同。这种碎裂模式似乎是这两种加合物的“指纹”。这些反应似乎是由
硅对氧的高亲和力以及Si( )3+离子对硝基中形式负电荷氧的吸引所驱动的。从已知的 热
化学和反应中间体的从头计算中得出了RDX与Si( )3+反应的反应坐标图,并讨论了其含义。这类反应可能有助于作为常见炸药的检测方案。