[Cu·(H2O)n]2+ Clusters:  The First Evidence of Aqueous Cu(II) in the Gas Phase

Stace, A. J.; Walker, Nicholas R.; Firth, Steve

doi:10.1021/ja9722436

Cited by 106 publications

(94 citation statements)

References 15 publications

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“…In particular, the metalligand and hydrogen bond strengths are not balanced correctly, especially in complexes exhibiting a high (Ն2) charge, and current popular functionals appear to favor lower coordination number. Thus, contrary to the DFT results referred to above, MP2 calculations found the [Mn(H 2 O) 6 ] 2ϩ structure to be energetically more favorable than the [Mn(H 2 O) 4 …”

Section: Computationalcontrasting

confidence: 73%

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A Gas-phase study of the preferential solvation of Mn²⁺ in mixed water/methanol clusters

Duncombe

Rydén

Puškar

et al. 2008

J. Am. Soc. Mass Spectrom.

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The kinetic shift that exists between two competing unimolecular fragmentation processes has been used to establish whether or not gas-phase Mn 2ϩ exhibits preferential solvation when forming mixed clusters with water and methanol. Supported by molecular orbital calculations, these first results for a metal dication demonstrate that Mn 2ϩ prefers to be solvated by methanol in the primary solvation shell. (J Am Soc Mass Spectrom 2008, 19, 520 -530 [4 -9], but equally important is behavior in many-component solvents, where competing interactions may be dominated by differences in molecular properties [10 -12]. In general, a condensed phase solution containing solvents with very similar pure-state properties might be expected to behave in a manner that reflects the composition of the solvent mixture [13]. There have been several attempts to simulate the behavior of metal dications in mixed solvent systems, [14 -18], and of particular significance to the work discussed here are the molecular dynamics studies of Day and Patey [14,15]. From simulations of an ion in the presence of water and methanol they concluded that a positively charged solute exhibits a pronounced preference for water. If there are large differences in the solvating abilities of the components, selective or preferential solvation may occur [11,12]; however, the degree of averaging present in a typical condensed phase system means that subtle effects due to small differences in free energy are unlikely to make their presence felt [13]. In contrast, the consequences of small, individual differences in molecular properties can be amplified in the gas phase because of the influence they may have on establishing equilibria or determining fragmentation pathways [10, 19 -21]. Presented here are the results of a study designed to see if an established technique for generating multiply charged metal/solvent complexes in the gas phase can yield useful information on behavior in mixed solvent systems. From this first study, the experimental results demonstrate that for water and methanol as solvents, gas-phase Mn 2ϩ does exhibit preferential solvation. This conclusion is supported by detailed molecular orbital calculations on a wide range of mixed [Mn(MeOH) 2ϩ complexes, which show that small differences in the binding energies of methanol and water are sufficient to account for the experimental results. ExperimentalThe experimental apparatus used for the generation and detection of gas-phase multiply charged metalligand complexes has been described extensively in previous publications [22]. Briefly, mixed neutral argon/ligand clusters are produced by the adiabatic expansion of solvent vapor mixed with argon through a pulsed supersonic nozzle. Previous work on the preferential solvation of hydrogen ions in clusters composed of methanol and water showed that the composition of ionized clusters depended quite significantly on the composition of the coexpansion mixture [19]. In this study, several mixtures were evaluated, but it was found that a ratio of 5:1,...

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Section: Computationalcontrasting

confidence: 73%

“…2ϩ is more stable than the "6 ϩ 0"-[Mn(H 2 O) 6 ] 2ϩ by 17.6 kJ mol Ϫ1 . However, the gain in energy due to replacement of second shell water molecules in the "4 ϩ 2" structure is slightly greater (at 20.9 kJ mol Ϫ1 ) than that of replacing first shell waters in the "6 ϩ 0" structure.…”

Section: Calculated Mixed-ligand Structuresmentioning

confidence: 97%

A Gas-phase study of the preferential solvation of Mn²⁺ in mixed water/methanol clusters

Duncombe

Rydén

Puškar

et al. 2008

J. Am. Soc. Mass Spectrom.

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“…These gas-phase proton-transfer reactions (reaction 2) may have counterparts in aqueous solution. In a simplified picture of diluted solutions of aluminum salts, hexacoordinated aluminum(III) goes from Al 3+ (H 2 O) 6 in strongly acidic environment to Al(OH) 6 3− in strongly basic environment via AlOH 2+ (H 2 O) 5 5 2− (H 2 O) at intermediate pH. 27 Although the corresponding solution chemistry is much more complicated than the chemistry of these gas-phase clusters, and competing reactions involving several aluminum atoms are possible, the underlying chemical principles may be the same for certain reaction steps.…”

Section: Discussionmentioning

confidence: 99%

Unimolecular Reactions of Dihydrated Alkaline Earth Metal Dications M²⁺(H₂O)₂, M = Be, Mg, Ca, Sr, and Ba: Salt-Bridge Mechanism in the Proton-Transfer Reaction M²⁺(H₂O)₂ → MOH⁺ + H₃O⁺

Beyer

Williams²,

Bondybey³

1999

J. Am. Chem. Soc.

150

198

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The unimolecular reactivity of M 2+ (H 2 O) 2 , M = Be, Mg, Ca, Sr, and Ba, is investigated by density functional theory. Dissociation of the complex occurs either by proton transfer to form singly charged metal hydroxide, MOH + , and protonated water, H 3 O + , or by loss of water to form M 2+ (H 2 O) and H 2 O. Charge transfer from water to the metal forming H 2 O + and M + (H 2 O) is not favorable for any of the metal complexes. The relative energetics of these processes are dominated by the metal dication size. Formation of MOH + proceeds first by one water ligand moving to the second solvation shell followed by proton transfer to this second-shell water molecule and subsequent Coulomb explosion. These hydroxide formation reactions are exothermic with activation energies that are comparable to the water binding energy for the larger metals. This results in a competition between proton transfer and loss of a water molecule. The arrangement with one water ligand in the second solvation shell is a local minimum on the potential energy surface for all metals except Be. The two transition states separating this intermediate from the reactant and the products are identified. The second transition state determines the height of the activation barrier and corresponds to a M 2+ -OH − -H 3 O + "saltbridge" structure. The computed B3LYP energy of this structure can be quantitatively reproduced by a simple ionic model in which Lewis charges are localized on individual atoms. This salt-bridge arrangement lowers the activation energy of the proton-transfer reaction by providing a loophole on the potential energy surface for the escape of H 3 O + . Similar salt-bridge mechanisms may be involved in a number of proton-transfer reactions in small solvated metal ion complexes, as well as in other ionic reactions.

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“…An interesting paper by Stace et al reported mass spectrometry of the cupric complexes coordinated by water molecules in gas phase [7]. The correlation between the ion intensity and the number of coordinated solvent molecules gives insight into the structures of metal-solvent complexes.…”

Section: Introductionmentioning

confidence: 99%

Calculations of hyperfine coupling constant of copper(II) in aqueous environment. Finite temperature molecular dynamics and relativistic effects

et al. 2015

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The presented paper is focused on the calculation of hyperfine coupling constants (HFCC) of Cu (2+) ion in water environment. To simulate the conditions of the electron paramagnetic resonance (EPR) experiment in aqueous phase, molecular dynamics using the density functional theory (DFT) was employed. In total three different functionals (BLYP, B3LYP, M06) were employed for studying their suitability in describing coordination of Cu (2+) by water molecules. The system of our interest was composed of one Cu (2+) cation surrounded by a selected number (between thirty and fifty) of water molecules. Besides the non-relativistic HFCCs (Fermi contact terms) of Cu (2+) also the four-component relativistic HFCC calculations are presented. The importance of the proper evaluation of HFCCs, the inclusion of spin-orbit term, for Cu (2+) containing systems (Neese, J. Chem. Phys. 118, 3939 2003; Almeida et al., Chem. Phys. 332, 176 2007) is confirmed at the relativistic four-component level of theory.

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[Cu·(H₂O)_n]²⁺ Clusters: The First Evidence of Aqueous Cu(II) in the Gas Phase

Cited by 106 publications

References 15 publications

A Gas-phase study of the preferential solvation of Mn²⁺ in mixed water/methanol clusters

A Gas-phase study of the preferential solvation of Mn²⁺ in mixed water/methanol clusters

Unimolecular Reactions of Dihydrated Alkaline Earth Metal Dications M²⁺(H₂O)₂, M = Be, Mg, Ca, Sr, and Ba: Salt-Bridge Mechanism in the Proton-Transfer Reaction M²⁺(H₂O)₂ → MOH⁺ + H₃O⁺

Calculations of hyperfine coupling constant of copper(II) in aqueous environment. Finite temperature molecular dynamics and relativistic effects

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[Cu·(H2O)n]2+ Clusters: The First Evidence of Aqueous Cu(II) in the Gas Phase

Cited by 106 publications

References 15 publications

A Gas-phase study of the preferential solvation of Mn2+ in mixed water/methanol clusters

A Gas-phase study of the preferential solvation of Mn2+ in mixed water/methanol clusters

Unimolecular Reactions of Dihydrated Alkaline Earth Metal Dications M2+(H2O)2, M = Be, Mg, Ca, Sr, and Ba: Salt-Bridge Mechanism in the Proton-Transfer Reaction M2+(H2O)2 → MOH+ + H3O+

Calculations of hyperfine coupling constant of copper(II) in aqueous environment. Finite temperature molecular dynamics and relativistic effects

Contact Info

Product

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[Cu·(H₂O)_n]²⁺ Clusters: The First Evidence of Aqueous Cu(II) in the Gas Phase

A Gas-phase study of the preferential solvation of Mn²⁺ in mixed water/methanol clusters

A Gas-phase study of the preferential solvation of Mn²⁺ in mixed water/methanol clusters

Unimolecular Reactions of Dihydrated Alkaline Earth Metal Dications M²⁺(H₂O)₂, M = Be, Mg, Ca, Sr, and Ba: Salt-Bridge Mechanism in the Proton-Transfer Reaction M²⁺(H₂O)₂ → MOH⁺ + H₃O⁺