Gong Yu, Tian Guoxin, Rao Linfeng, Gibson John K
Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
J Phys Chem A. 2014 Apr 17;118(15):2749-55. doi: 10.1021/jp501454v. Epub 2014 Apr 2.
The Pu(4+), Np(4+), and U(4+) ions, which have large electron affinities of ∼34.6, ∼33.6, and ∼32.6 eV, respectively, were stabilized from solution to the gas phase upon coordination by three neutral tetramethyl-3-oxa-glutaramide ligands (TMOGA). Both collision induced dissociation (CID) and electron transfer dissociation (ETD) of Pu(TMOGA)3(4+) reveal the propensity for reduction of Pu(IV) to Pu(III), by loss of TMOGA(+) in CID and by simple electron transfer in ETD. The reduction of Pu(IV) is in distinct contrast to retention of Th(IV) in both CID and ETD of Th(TMOGA)3(4+), where only the C-Oether bond cleavage product was observed. U(TMOGA)3(4+) behaves similarly to Th(TMOGA)3(4+) upon CID and ETD, while the fragmentation patterns of Np(TMOGA)3(4+) lie between those of Pu(TMOGA)3(4+) and U(TMOGA)3(4+). It is notable that the gas-phase fragmentation behaviors of these exceptional tetrapositive complexes parallel fundamental differences in condensed phase chemistry within the actinide series, specifically the tendency for reduction from the IV to III oxidation states.
钚（IV）、镎（IV）和铀（IV）离子的电子亲合能分别约为34.6、33.6和32.6电子伏特，通过与三个中性四甲基-3-氧杂-戊二酰胺配体（TMOGA）配位后，它们从溶液相稳定到气相。钚（TMOGA）3（4+）的碰撞诱导解离（CID）和电子转移解离（ETD）都表明，在CID中通过失去TMOGA（+）以及在ETD中通过简单的电子转移，钚（IV）有还原为钚（III）的倾向。钚（IV）的这种还原与钍（TMOGA）3（4+）在CID和ETD中钍（IV）的保留形成鲜明对比，在钍（TMOGA）3（4+）的CID和ETD中只观察到C-O醚键断裂产物。铀（TMOGA）3（4+）在CID和ETD中的行为与钍（TMOGA）3（4+）相似，而镎（TMOGA）3（4+）的碎裂模式则介于钚（TMOGA）3（4+）和铀（TMOGA）3（4+）之间。值得注意的是，这些特殊的四价配合物的气相碎裂行为与锕系元素系列中凝聚相化学的基本差异相似，特别是从IV氧化态还原到III氧化态的倾向。
