Ionic fragmentation versus electron detachment in isolated transition metal complex dianions

Boxford, William E.; Pearce, Jon; Dessent, Caroline E. H.

doi:10.1016/j.cplett.2004.10.054

Cited by 32 publications

(45 citation statements)

References 15 publications

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“…This observation reflects the fact that RCB ed (inner) is substantially higher than RCB if (inner) for these dianions, mirroring results obtained in our group for transition metal complex dianions. 9 Although gas-phase molecular dianions are commonly thought to be primarily unstable with respect to electron detachment, our results illustrate that ionic fragmentation will generally represent the preferred lowest energy decay pathway for dianions that can dissociate to form stable anions. While larger multiply charged biomolecular ions such as peptides and oligonucleotides have also been observed to dissociate via ionic fragmentation, these situations are somewhat different from the systems studied here where the excess charges occupy adjacent molecular groups.…”

Section: Further Discussionmentioning

confidence: 87%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Much of this research effort is driven by the challenge of understanding the unique physical characteristics of these systems. For example, the ground-state potential energy surfaces of MCAs are generally dominated by novel repulsive Coulomb barriers (RCBs) that arise from the combination of the long-range Coulomb repulsion between the excess negative charges and the short-range attractive interaction.…”

Section: Introductionmentioning

confidence: 99%

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Stabilization of Excess Charge in Isolated Adenosine 5‘-Triphosphate and Adenosine 5‘-Diphosphate Multiply and Singly Charged Anions

et al. 2005

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Multiply charged anions (MCAs) represent highly energetic species in the gas phase but can be stabilized through formation of molecular clusters with solvent molecules or counterions. We explore the intramolecular stabilization of excess negative charge in gas-phase MCAs by probing the intrinsic stability of the [adenosine 5'-triphosphate-2H](2-) ([ATP-2H](2-)), [adenosine 5'-diphosphate-2H](2-) ([ADP-2H](2-)), and H(3)P(3)O(10)(2-) dianions and their protonated monoanionic analogues. The relative activation barriers for decay of the dianions via electron detachment or ionic fragmentation are investigated using resonance excitation of ions isolated within a quadrupole trap. All of the dianions decayed via ionic fragmentation demonstrating that the repulsive Coulomb barriers (RCB) for ionic fragmentation lie below the RCBs for electron detachment. Both the electrospray ionization mass spectra (ESI-MS) and total fragmentation energies for [ATP-2H](2-), [ADP-2H](2-), and H(3)P(3)O(10)(2-) indicate that the multiply charged H(3)P(3)O(10)(2-) phosphate moiety is stabilized by the presence of the adenosine group and the stability of the dianions increases in the order H(3)P(3)O(10)(2-) < [ADP-2H](2-) < [ATP-2H](2-). Fully optimized, B3LYP/6-31+G* minimum energy structures illustrate that the excess charges in all of the phosphate anions are stabilized by intramolecular hydrogen bonding either within the phosphate chain or between the phosphate and the adenosine. We develop a model to illustrate that the relative magnitudes of the RCBs and hence the stability of these ions is dominated by the extent of intramolecular hydrogen bonding.

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Section: Further Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Stabilization of Excess Charge in Isolated Adenosine 5‘-Triphosphate and Adenosine 5‘-Diphosphate Multiply and Singly Charged Anions

et al. 2005

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“…Our study of thermal heating and effects on fragmentation of MCAs can parallel to the previous low energy collisioninduced-dissociation studies of MCAs. 46,47 …”

Section: G Temperature Dependence Of Multiply Charged Clustersmentioning

confidence: 98%

Probing the early stages of salt nucleation—Experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

2015

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Due to the fast solvent evaporation in electrospray ionization (ESI), the concentration of initially dilute electrolyte solutions rapidly increases to afford the formation of supersaturated droplets and generation of various pristine anhydrous salt clusters in the gas phase. The size, composition, and charge distributions of these clusters, in principle, witness the nucleation evolution in solutions. Herein, we report a microscopic study on the initial stage of nucleation and crystallization of sodium/potassium thiocyanate salt solutions simulated in the ESI process. Singly charged Mx(SCN)x+1(-), doubly charged My(SCN)y+2(2-) (M = Na, K), and triply charged Kz(SCN)z+3(3-) anion clusters (x, y, and z stand for the number of alkali atoms in the singly, doubly, and triply charged clusters, respectively) were produced via electrospray of the corresponding salt solutions and were characterized by negative ion photoelectron spectroscopy (NIPES). The vertical detachment energies (VDEs) of these sodium/potassium thiocyanate cluster anions were obtained, and theoretical calculations were carried out for the sodium thiocyanate clusters in assisting spectral identification. The measured VDEs of singly charged anions Mx(SCN)x+1(-) (M = Na and K) demonstrate that they are superhalogen anions. The existence of doubly charged anions My(SCN)y+2(2-) (y = 2x, x ≥ 4 and 3 for M = Na and K, respectively) and triply charged anions Kz(SCN)z+3(3-) (z = 3x, x ≥ 6) was initially discovered from the photoelectron spectra for those singly charged anions of Mx(SCN)x+1(-) with the same mass-to-charge ratio (m/z), and later independently confirmed by the observation of their distinct mass spectral distributions and by taking their NIPE spectra for those pure multiply charged anions with their m/z different from the singly charged species. For large clusters, multiply charged clusters were found to become preferred, but at higher temperatures, those multiply charged clusters were suppressed. The series of anion clusters investigated here range from molecular-like M1(SCN)2(-) to nano-sized K22(SCN)25(3-), providing a vivid molecular-level growth pattern reflecting the initial salt nucleation process.

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“…The coordination numbers of ligand and solvent molecules required to make stable dianionic metal complexes (84)(85)(86) and hydrated clusters (63, 87) have been pursued using size-selected collision-induced dissociation techniques. The competition between ionic fragmentation versus electron detachment and the counter-ion perturbation of MCAs has been investigated by collision excitation and ab initio calculations (88)(89)(90)(91). Lifetimes for a number of metastable dianions have been directly measured (83,92).…”

Section: Introductionmentioning

confidence: 99%

Photoelectron Spectroscopy of Multiply Charged Anions

Wang

2009

Annu. Rev. Phys. Chem.

125

171

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Multiply charged anions (MCAs) are common in condensed phases but are challenging to study in the gas phase. An experimental technique, coupling photoelectron spectroscopy (PES) with electrospray ionization (ESI), has been developed to investigate the properties of free MCAs in the gas phase. This article reviews the principles of this technique and some initial findings about the intrinsic properties of MCAs. Examples include the observation of the repulsive Coulomb barrier that exists universally in MCAs and its effects on the dynamic stability and PES of MCAs. The solvation and solvent stabilization of MCAs have been studied in the gas phase and are also discussed. A second-generation low-temperature ESI-PES apparatus has been developed, which allows ion temperatures to be controlled from 10 to 350 K. New results from this low-temperature ESI-PES instrument are also reviewed, including doubly charged fullerene anions, inorganic metal complexes, and temperature-induced conformation changes of complex anions.

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Ionic fragmentation versus electron detachment in isolated transition metal complex dianions

Cited by 32 publications

References 15 publications

Stabilization of Excess Charge in Isolated Adenosine 5‘-Triphosphate and Adenosine 5‘-Diphosphate Multiply and Singly Charged Anions

Stabilization of Excess Charge in Isolated Adenosine 5‘-Triphosphate and Adenosine 5‘-Diphosphate Multiply and Singly Charged Anions

Probing the early stages of salt nucleation—Experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

Photoelectron Spectroscopy of Multiply Charged Anions

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