Bubas Amanda R, Tatosian Irena J, Iacovino Anna, Corcovilos Theodore A, van Stipdonk Michael J
Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, PA 15282, USA.
Department of Physics, Duquesne University, 600 Forbes Ave, Pittsburgh, PA 15282, USA.
Phys Chem Chem Phys. 2024 Apr 24;26(16):12753-12763. doi: 10.1039/d4cp00823e.
In a previous study, electrospray ionization, collision-induced dissociation (CID), and gas-phase ion-molecule reactions were used to create and characterize ions derived from homogeneous precursors composed of a uranyl cation (UO) coordinated by either formate or acetate ligands [E. Perez, C. Hanley, S. Koehler, J. Pestok, N. Polonsky and M. Van Stipdonk, Gas phase reactions of ions derived from anionic uranyl formate and uranyl acetate complexes, , 2016, , 1989-1998]. Here, we describe a follow-up study of anionic complexes that contain a mix of formate and acetate ligands, namely [UO(OC-CH)(OC-H)] and [UO(OC-CH)(OC-H)]. Initial CID of either anion causes decarboxylation of a formate ligand to create carboxylate-coordinated U-hydride product ions. Subsequent CID of the hydride species causes elimination of acetaldehyde or formaldehyde, consistent with reactions that include intra-complex hydride attack upon bound acetate or formate ligands, respectively. Density functional theory (DFT) calculations reproduce the experimental observations, including the favored elimination of formaldehyde over acetaldehyde by hydride attack during CID of [UO(H)(OC-CH)(OC-H)]. We also discovered that MS CID of the acetate-formate complexes leads to generation of the oxyl-methide species, [UO(O)(CH)], which reacts with HO to generate [UO(O)(OH)]. DFT calculations support the observation that formation of [UO(O)(OH)] by elimination of CH is favored over HO addition and rearrangement to create [UO(OH)(CH)].
在之前的一项研究中，电喷雾电离、碰撞诱导解离（CID）和气相离子-分子反应被用于生成和表征由甲酸根或乙酸根配体配位的铀酰阳离子（UO）组成的均相前体衍生的离子[E. 佩雷斯、C. 汉利、S. 克勒、J. 佩斯托克、N. 波隆斯基和M. 范·斯蒂普登克，甲酸铀酰和乙酸铀酰阴离子配合物衍生离子的气相反应，，2016，，1989 - 1998]。在此，我们描述了一项关于含有甲酸根和乙酸根配体混合物的阴离子配合物的后续研究，即[UO(OC-CH)(OC-H)]和[UO(OC-CH)(OC-H)]。任一阴离子的初始CID会导致甲酸根配体脱羧，生成羧基配位的铀酰氢产物离子。随后氢化物物种的CID会导致乙醛或甲醛的消除，这分别与包括配合物内氢化物对结合的乙酸根或甲酸根配体的攻击反应一致。密度泛函理论（DFT）计算重现了实验观察结果，包括在[UO(H)(OC-CH)(OC-H)]的CID过程中，氢化物攻击优先消除甲醛而非乙醛。我们还发现乙酸根-甲酸根配合物的质谱CID会导致生成甲氧负离子物种[UO(O)(CH)]，它与HO反应生成[UO(O)(OH)]。DFT计算支持这样的观察结果，即通过消除CH形成[UO(O)(OH)]比HO加成并重排生成[UO(OH)(CH)]更有利。
