Structure Determination of Zinc and Cadmium Dication Complexes with Intact and Deprotonated Histidyl Glycine and Glycyl Histidine Dipeptides.

Metalated intact and deprotonated histidyl glycine and glycyl histidine dipeptides were investigated in the gas phase by using infrared multiple photon dissociation (IRMPD) spectroscopy with light from a free-electron laser (FEL). The dipeptides M(GlyHis), M(HisGly), [M(GlyHis-H)], and [M(HisGly-H)], where M = Zn and Cd, were probed to elucidate how the His position along the peptide chain and ligand charge state might influence the structures observed in the gas phase. Simulated annealing calculations were performed to determine energetically low-lying conformers and isomers of these structures.

The Curious Case of Pu: Insight on 5f Orbital Activity from Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) Reactions.

A comprehensive understanding of when and how 5f orbitals participate in complex chemical bonding is important for a variety of applications. The actinides are unique in that they possess 5f orbitals and can access high oxidation states, which make them attractive for use in catalysis. Fundamental studies of actinide-ligand interactions offer a mechanism to examine the activation of the 5f orbitals so that the selectivity of 5f orbitals can be assessed.

The bond energy of UN+: Guided ion beam studies of the reactions of U+ with N2 and NO.

A guided ion beam tandem mass spectrometer was used to study the reactions of U+ with N2 and NO. Reaction cross sections were measured over a wide range of energy for both systems. In each reaction, UN+ is formed by an endothermic process, thereby enabling the direct measurement of the threshold energy and determination of the UN+ bond dissociation energy.

Reactions of gas-phase uranyl formate/acetate anions: reduction of carboxylate ligands to aldehydes by intra-complex hydride attack.

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.

A guided ion beam investigation of UO2+ thermodynamics and f orbital participation: Reactions of U+ + CO2, UO+ + O2, and UO+ + CO.

A guided ion beam tandem mass spectrometer was employed to study the reactions of U+ + CO2, UO+ + O2, and the reverse of the former, UO+ + CO. Reaction cross sections as a function of kinetic energy over about a three order of magnitude range were studied for all systems. The reaction of U+ + CO2 proceeds to form UO+ + CO with an efficiency of 118% ± 24% as well as generating UO2+ + C and UCO+ + O.

Reactions of Atomic Thorium and Uranium Cations with SF Studied by Guided Ion Beam Tandem Mass Spectrometry.

The fundamental chemistry of the thorium and uranium fluorides continues to be an area of interest because of the use of thorium and uranium fluoride compounds in nuclear fuel systems. Here, we study the reaction of thorium cations with sulfur hexafluoride for the first time and revisit the reaction of uranium cations with sulfur hexafluoride. By using guided ion beam tandem mass spectrometry, we explore the reaction pathways that become accessible well above thermal energies ( ∼ 0.

Characterization of Uranyl Coordinated by Equatorial Oxygen: Oxo in UO versus Oxyl in UO.

Uranium trioxide, UO, has a T-shaped structure with bent uranyl, UO, coordinated by an equatorial oxo, O. The structure of cation UO is similar but with an equatorial oxyl, O. Neutral and cationic uranium trioxide coordinated by nitrates were characterized by collision induced dissociation (CID), infrared multiple-photon dissociation (IRMPD) spectroscopy, and density functional theory.

Destruction and reconstruction of UO using gas-phase reactions.

While the strong axial U[double bond, length as m-dash]O bonds confer high stability and inertness to UO22+, it has been shown that the axial oxo ligands can be eliminated or replaced in the gas-phase using collision-induced dissociation (CID) reactions. We report here tandem mass spectrometry experiments initiated with a gas-phase complex that includes UO22+ coordinated by a 2,6-difluorobenzoate ligand. After decarboxylation to form a difluorophenide coordinated uranyl ion, [UO2(C6F2H3)]+, CID causes elimination of CO, and then CO and C2H2 in sequential dissociation steps, to leave a reactive uranium fluoride ion, [UF2(C2H)]+.

Collision-induced dissociation of [UO (NO )(O )] and reactions of product ions with H O and O.

We recently reported a detailed investigation of the collision-induced dissociation (CID) of [UO (NO ) ] and [UO (NO ) (O )] in a linear ion trap mass spectrometer (J. Mass Spectrom. DOI:10.

Collision-induced dissociation of [UO (NO ) ] and [UO (NO ) (O )] and reactions of product ions with H O and O.

Electrospray ionization (ESI) can produce a wide range of gas-phase uranyl (UO ) complexes for tandem mass spectrometry studies of intrinsic structure and reactivity. We describe here the formation and collision-induced dissociation (CID) of [UO (NO ) ] and [UO (NO ) (O )] . Multiple-stage CID experiments reveal that the complexes dissociate in reactions that involve elimination of O , NO , or NO , and subsequent reactions of interesting uranyl-oxo product ions with (neutral) H O and/or O were investigated.

Formation and hydrolysis of gas-phase [UO (R)] : R═CH , CH CH , CH═CH , and C H.

The goals of the present study were (a) to create positively charged organo-uranyl complexes with general formula [UO (R)] (eg, R═CH and CH CH ) by decarboxylation of [UO (O C─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 H O. Collision-induced dissociation (CID) of both [UO (O C─CH )] and [UO (O C─CH CH )] causes H transfer and elimination of a ketene to leave [UO (OH)] . However, CID of the alkoxides [UO (OCH CH )] and [UO (OCH CH CH )] produced [UO (CH )] and [UO (CH CH )] , respectively.

Gas-Phase Deconstruction of UO: Mass Spectrometry Evidence for Generation of [OUCH] by Collision-Induced Dissociation of [UO(C≡CH)].

Because of the high stability and inertness of the U=O bonds, activation and/or functionalization of UO and UO remain challenging tasks. We show here that collision-induced dissociation (CID) of the uranyl-propiolate cation, [UO(OC-C≡CH)], can be used to prepare [UO(C≡CH)] in the gas phase by decarboxylation. Remarkably, CID of [UO(C≡CH)] caused elimination of CO to create [OUCH], thus providing a new example of a well-defined substitution of an "yl" oxo ligand of UO in a unimolecular reaction.