Departamento de Química, Módulo 13, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049, Madrid, Spain.
Org Biomol Chem. 2012 Oct 7;10(37):7552-61. doi: 10.1039/c2ob26166a.
The collision induced dissociation of formamide-Ca(2+) complexes produced in the gas phase through nanoelectrospray ionization yields as main products ions CaOH, HCNH, Ca(NH(2)), HCO(+) and Ca(NH(3)) and possibly Ca(H(2)O) and C,O,Ca, the latter being rather minor. The mechanisms behind these fragmentation processes have been established by analyzing the topology of the potential energy surface by means of B3LYP calculations carried out with a core-correlated cc-pWCVTZ basis set. The Ca(2+) complexes formed by formamide itself and formimidic acid play a fundamental role. The former undergoes a charge separation reaction yielding Ca(NH(2)) + HCO(+), and the latter undergoes the most favorable Coulomb explosion yielding Ca-OH + HCNH and is the origin of a multistep mechanism which accounts for the observed loss of water and HCN. Conversely, the other isomer of formamide, amino(hydroxyl)carbene, does not play any significant role in the unimolecular reactivity of the doubly charged molecular cation.
气相中通过纳喷雾电离产生的甲酰胺-Ca(2+)复合物的碰撞诱导解离主要产生离子CaOH、HCNH、Ca(NH(2))、HCO(+)和Ca(NH(3))，可能还有Ca(H(2)O)和C,O,Ca，后者则较少。通过使用核心相关的 cc-pWCVTZ 基组进行 B3LYP 计算来分析势能面的拓扑结构，确定了这些碎裂过程背后的机制。由甲酰胺本身和甲脒形成的 Ca(2+)复合物起着重要作用。前者经历电荷分离反应，生成Ca(NH(2)) + HCO(+)，而后者经历最有利的库仑爆炸，生成Ca-OH + HCNH，是解释观察到的水和 HCN 损失的多步机制的起源。相反，甲酰胺的另一种异构体氨基(羟基)卡宾在双电荷分子阳离子的单分子反应中没有任何重要作用。
