Treatment of Substitution and Rearrangement Mechanisms of Transition Metal Complexes with Quantum Chemical Methods

Rotzinger, François P.

doi:10.1021/cr030715v

Cited by 168 publications

(155 citation statements)

References 160 publications

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“…69 Not surprisingly, both associative and dissociative exchanges were seen in the simulations. However, it was found that the pathway followed for the observed associative exchanges was considerably more complex than that found for dissociative exchanges.…”

Section: E Hydration Shell Particle Exchangementioning

confidence: 81%

Structure and dynamics of the hydration shells of the Zn2+ ion from ab initio molecular dynamics and combined ab initio and classical molecular dynamics simulations

Cauët

Bogatko

Weare

et al. 2010

The Journal of Chemical Physics

101

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Results of ab initio molecular dynamics ͑AIMD͒ simulations ͑density functional theory+ PBE96͒ of the dynamics of waters in the hydration shells surrounding the Zn 2+ ion ͑T Ϸ 300 K, Ϸ 1 gm/ cm 3 ͒ are compared to simulations using a combined quantum and classical molecular dynamics ͓AIMD/molecular mechanical ͑MM͔͒ approach. Both classes of simulations were performed with 64 solvating water molecules ͑ϳ15 ps͒ and used the same methods in the electronic structure calculation ͑plane-wave basis set, time steps, effective mass, etc.͒. In the AIMD/MM calculation, only six waters of hydration were included in the quantum mechanical ͑QM͒ region. The remaining 58 waters were treated with a published flexible water-water interaction potential. No reparametrization of the water-water potential was attempted. Additional AIMD/MM simulations were performed with 256 water molecules. The hydration structures predicted from the AIMD and AIMD/MM simulations are found to agree in detail with each other and with the structural results from x-ray data despite the very limited QM region in the AIMD/MM simulation. To further evaluate the agreement of these parameter-free simulations, predicted extended x-ray absorption fine structure ͑EXAFS͒ spectra were compared directly to the recently obtained EXAFS data and they agree in remarkable detail with the experimental observations. The first hydration shell contains six water molecules in a highly symmetric octahedral structure is ͑maximally located at 2.13-2.15 Å versus 2.072 Å EXAFS experiment͒. The widths of the peak of the simulated EXAFS spectra agree well with the data ͑8.4 Å 2 versus 8.9 Å 2 in experiment͒. Analysis of the H-bond structure of the hydration region shows that the second hydration shell is trigonally bound to the first shell water with a high degree of agreement between the AIMD and AIMD/MM calculations. Beyond the second shell, the bonding pattern returns to the tetrahedral structure of bulk water. The AIMD/MM results emphasize the importance of a quantum description of the first hydration shell to correctly describe the hydration region. In these calculations the full d 10 electronic structure of the valence shell of the Zn 2+ ion is retained. The simulations show substantial and complex charge relocation on both the Zn 2+ ion and the first hydration shell. The dipole moment of the waters in the first hydration shell is 3.4 D ͑3.3 D AIMD/MM͒ versus 2.73 D bulk. Little polarization is found for the waters in the second hydration shell ͑2.8 D͒. No exchanges were seen between the first and the second hydrations shells; however, many water transfers between the second hydration shell and the bulk were observed. For 64 waters, the AIMD and AIMD/MM simulations give nearly identical results for exchange dynamics. However, in the larger particle simulations ͑256 waters͒ there is a significant reduction in the second shell to bulk exchanges.

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Section: E Hydration Shell Particle Exchangementioning

confidence: 81%

Structure and dynamics of the hydration shells of the Zn2+ ion from ab initio molecular dynamics and combined ab initio and classical molecular dynamics simulations

Cauët

Bogatko

Weare

et al. 2010

The Journal of Chemical Physics

101

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“…[105][106][107] Although in some cases there is good agreement between ab initio and experimental energy barriers for water exchanges from octahedral metal ions, [55,106,[108][109][110] this agreement is found only after extraordinary care. [106][107][108]111] Furthermore, reactions with seemingly simple mechanisms, such as the exchange of a single bound water molecule, do not lend themselves to expression in terms of simple reaction coordinates. For example, using the metalwater distance of the outgoing water molecule as the reaction coordinate can lead to exceedingly low transmission probabilities.…”

Section: Lifetimes Of Bound Water Moleculesmentioning

confidence: 99%

Minerals as Molecules—Use of Aqueous Oxide and Hydroxide Clusters to Understand Geochemical Reactions

Casey

Rustad

Spiccia

2009

Chemistry A European J

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Large aqueous oxide ions as minerals! Minerals dissolve by repeated ligand exchange reactions and geochemists use polyoxometalate ions to establish structure-reactivity relations for environmentally important functional groups. Here, for example, are plotted the dissolution rates of two classes of minerals against rates of solvent exchanges around the corresponding aquo ions.Geochemists and environmental chemists make predictions about the fate of chemicals in the shallow earth over enormously long times. Key to these predictions is an understanding of the hydrolytic and complexation reactions at oxide mineral surfaces that are difficult to probe spectroscopically. These minerals are usually oxides with repeated structural motifs, like silicate or aluminosilicate polymers, and they expose a relatively simple set of functional groups to solution. The geochemical community is at the forefront of efforts to describe the surface reactivities of these interfacial functional groups and some insights are being acquired by using small oligomeric oxide molecules as experimental models. These small nanometer-size clusters are not minerals, but their solution structures and properties are better resolved than for minerals and calculations are relatively well constrained. The primary experimental data are simple rates of steady oxygen-isotope exchanges into the structures as a function of solution composition that can be related to theoretical results. There are only a few classes of large oxide ions for which data have been acquired and here we review examples and illustrate the general approach, which also derives directly from the use of model clusters to understand for the active core of metalloenzymes in biochemistry.

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“…This is the root of the open controversy concerning this point, as very recently emphasized by Rotzinger. 13,58 XANES can go further, but it does not yield a unique answer: the simple idea of a stable well-defined coordination geometry in solution does not work in this case. On the basis of this hypothesis, the question on which is the structure adopted by Cu͑II͒ aquaions in solution is meaningless.…”

Section: Figmentioning

confidence: 99%

“…12 The departure from the generally accepted picture reported by Pasquarello et al 12 causes the appearance of subsequent theoretical and experimental works trying to verify these findings, as reported by Rotzinger in a very recent review. 13 On the theoretical side, contradictory results have been recently provided by molecular-dynamics ͑MD͒ simulations. While in one case, Blumberger et al 14 show that the Cu͑II͒ hydrate fluctuates between tetragonally distorted octahedral, square pyramidal, and trigonal bipyramidal coordination, in another case, Schwenk and Rode 15 support a single distorted octahedral structure.…”

Section: Introductionmentioning

confidence: 99%

The hydration of Cu2+: Can the Jahn-Teller effect be detected in liquid solution?

Chaboy

Muñoz‐Páez

Merkling

et al. 2006

The Journal of Chemical Physics

114

125

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The long elusive structure of Cu͑II͒ hydrate in aqueous solutions, classically described as a Jahn-Teller distorted octahedron and recently proposed to be a fivefold coordination structure ͓Pasquarello et al., Science 291, 856 ͑2001͔͒, has been probed with x-ray-absorption spectroscopy by performing a combined theoretical and experimental analysis. Two absorption channels were needed to obtain a proper reproduction of the x-ray-absorption near-edge structure ͑XANES͒ region spectrum, as already observed in other Cu͑II͒ complexes ͓Chaboy et al., Phys. Rev. B 71, 134208 ͑2005͔͒. The extended x-ray-absorption fine-structure ͑EXAFS͒ spectrum was analyzed as well within this approach. Quite good reproductions of both XANES and EXAFS spectra were attained for several distorted and undistorted structures previously proposed. Nevertheless, there is not a clearly preferred structure among those including four-, five-, and sixfold coordinated Cu͑II͒ ions. Taking into account our results, as well as many more from several other authors using different techniques, the picture of a distorted octahedron for the Cu͑II͒ hexahydrate in aqueous solution, paradigm of the Jahn-Teller effect, is no longer supported. In solution a dynamical view where the different structures exchange among themselves is the picture that better suits the results presented here.

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Treatment of Substitution and Rearrangement Mechanisms of Transition Metal Complexes with Quantum Chemical Methods

Cited by 168 publications

References 160 publications

Structure and dynamics of the hydration shells of the Zn2+ ion from ab initio molecular dynamics and combined ab initio and classical molecular dynamics simulations

Structure and dynamics of the hydration shells of the Zn2+ ion from ab initio molecular dynamics and combined ab initio and classical molecular dynamics simulations

Minerals as Molecules—Use of Aqueous Oxide and Hydroxide Clusters to Understand Geochemical Reactions

The hydration of Cu2+: Can the Jahn-Teller effect be detected in liquid solution?

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