Maleknia S, Brodbelt J
Department of Chemistry and Biochemistry, University of Texas, Austin 78712-1167.
Rapid Commun Mass Spectrom. 1992 Jun;6(6):376-81. doi: 10.1002/rcm.1290060605.
High energy collision-induced dissociation (CID) techniques were applied for structural elucidation of alkali-metal ion adducts of crown ethers. The CID of alkali-metal adducts of tetraglyme and hexaethylene glycol were also evaluated to contrast the fragmentation pathways of the cyclic ethers with those of acyclic analogs. A common fragmentation channel for alkali-metal ion adducts of all the ethers, which results in distonic radical cations, is the homolytic cleavage of carbon-carbon bonds. Additionally, dissociation by carbon-oxygen bond cleavages occurs, and these processes are analogous to the fragmentation pathways observed for simple protonated ethers. The proposed fragmentation pathways for alkali-metal ion adducts of crown ethers result mostly in odd-electron, acyclic product ions. Dissociation of the alkali-metal ion adducts of the acyclic ethers is dominated by losses of various neutral species after an initial hydride or proton transfer. The CID processes for all ethers are independent of the alkali-metal ion sizes; however, the extent of dissociation of the complexes to bare alkali-metal ions increases with the size of the metal.
高能碰撞诱导解离（CID）技术被用于冠醚碱金属离子加合物的结构解析。还对四甘醇二甲醚和六甘醇的碱金属加合物进行了CID评估，以对比环状醚与非环状类似物的碎裂途径。所有醚的碱金属离子加合物的一个共同碎裂通道是碳-碳键的均裂，会产生双自由基阳离子。此外，还会发生碳-氧键断裂导致的解离，这些过程与简单质子化醚所观察到的碎裂途径类似。所提出的冠醚碱金属离子加合物的碎裂途径大多产生奇数电子的非环状产物离子。非环状醚的碱金属离子加合物的解离主要是在初始氢化物或质子转移后各种中性物种的损失。所有醚的CID过程与碱金属离子大小无关；然而，配合物解离为裸碱金属离子的程度随金属大小的增加而增大。
