Formation and hydrolysis of gas ‐phase [UO2(R)]+: R═CH3, CH2CH3, CH═CH2, and C6H5

AbstractThe goals of the present study were (a) to create positively charged organo ‐uranyl complexes with general formula [UO2(R)]+ (eg, R ═CH3 and CH2CH3) by decarboxylation of [UO2(O2C ─R)]+ precursors and (b) to identify the pathways by which the complexes, if formed, dissociate by collisional activation or otherwise react when exposed to gas ‐phase H2O. Collision ‐induced dissociation (CID) of both [UO2(O2C ─CH3)]+ and [UO2(O2C ─CH2CH3)]+ causes H+ transfer and elimination of a ketene to leave [UO2(OH)]+. However, CID of the alkoxides [UO2(OCH2CH3)]+ and [UO2(OCH2CH2CH3)]+ produced [UO2(CH3)]+ and [UO2(CH2CH3)]+, respectively. Isolation of [UO2(CH3)]+ and [UO2(CH2CH3)]+ for reaction with H2O caused formation of [UO2(H2O)]+ by elimination of ·CH3 and ·CH2CH3: Hydrolysis was not observed. CID of the acrylate and benzoate versions of the complexes, [UO2(O2C ─CH═CH2)]+ and [UO2(O2C ─C6H5)]+, caused decarboxylation to leave [UO2(CH ═CH2)]+ and [UO2(C6H5)]+, respectively. These organometallic species do react with H2O to produce [UO2(OH)]+, and loss of the respective radicals to leave [UO2(H2O)]+ was not detected. Density functional theory calculations suggest that formation of [UO2(OH)]+, rather than the hydrated UVO2+, cation is energetically favored regardless of the precursor ion. However, for the [UO2(CH3)]+ and [UO2(CH2CH3)]+ precursors, the transition state energy for proton transfer to generate [UO2(OH)]+ and the associated neutral alkanes is hi...

Source: Journal of Mass Spectrometry - September 4, 2019 Category: Chemistry Authors: Irena Tatosian, Amanda Bubas, Anna Iacovino, Susan Kline, Luke Metzler, Michael Van Stipdonk Tags: RESEARCH ARTICLE Source Type: research