Coordination and ligand exchange dynamics of solvated metal ions

Rode, Bernd M.; Schwenk, Christian F.; Hofer, Thomas S.; Randolf, Bernhard R.

doi:10.1016/j.ccr.2005.03.032

Cited by 176 publications

(202 citation statements)

References 77 publications

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“…The B3LYP method proved inferior in this case, but it was also employed in this work in order to test its adequacy for the description of hydrated anions, as several cases have shown that the DFT methods can give poor results for hydrated cations. 5,24,25 It should be realized that while the HF scheme could produce an error due to the neglect of electron correlation effects, the DFT methods, although including such effects to a certain (uncontrollable) extent, are often found to overestimate the correlation energy. [23][24][25][26] On the other hand, a comparison of the HF calculations with the DFT results could be helpful to give a qualitative estimate of a possible influence of correlation effects.…”

Section: Methodsmentioning

confidence: 99%

A Combined QM/MM Molecular Dynamics Simulations Study of Nitrate Anion (NO₃^-) in Aqueous Solution

2006

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The structural and dynamical properties of NO 3 -in dilute aqueous solution have been investigated by means of two combined quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations, namely HF/MM and B3LYP/MM, in which the ion and its surrounding water molecules were treated at HF and B3LYP levels of accuracy, respectively, using the DZV+ basis set. On the basis of both HF and B3LYP methods, a well-defined first hydration shell of NO 3 -is obtainable, but the shell is quite flexible and the hydrogen-bond interactions between NO 3 -and water are rather weak. With respect to the detailed analysis of the geometrical arrangement and vibrations of NO 3 -, the experimentally observed solvent-induced symmetry breaking of the ion is well reflected. In addition, the dynamical information, i.e., the bond distortions and shifts in the corresponding bending and stretching frequencies as well as the mean residence time of water molecules surrounding the NO 3 -ion, clearly indicates the "structure-breaking" ability of this ion in aqueous solution. From a methodical point of view it seems that both the HF and B3LYP methods are not too different in describing this hydrated ion by means of a QM/MM simulation. However, the detailed analysis of the dynamics properties indicates a better suitability of the HF method compared to the B3LYP-DFT approach.

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Section: Methodsmentioning

confidence: 99%

A Combined QM/MM Molecular Dynamics Simulations Study of Nitrate Anion (NO₃^-) in Aqueous Solution

2006

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“…9,11−13 Substitution processes in nonaqueous media are of interest because of synthetic applications. Ligand substitution kinetics of transition metals, e.g., manganese, 14 chromium, 11 nickel, 12 cadmium, 15 and others, 16 attract a great deal of attention and have been actively studied. Moreover, photoinduced structural rearrangements of metal complexes also raise a lot of interest.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Formation of Copper(II) Chloro Complexes Revealed by Transient Absorption Spectroscopy and DFT/TDDFT Calculations

et al. 2015

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Copper(II) complexes are extremely labile with typical ligand exchange rate constants on the order of 10 6 −10 9 M −1 s −1 . As a result, it is often difficult to identify the actual formation mechanism of these complexes. In this work, using UV−vis transient absorption when probing in a broad time range (20 ps to 8 μs) in conjunction with DFT/TDDFT calculations, we studied the dynamics and underlying reaction mechanisms of the formation of extremely labile copper(II) CuCl 4 2− chloro complexes from copper(II) CuCl 3 − trichloro complexes and chloride ions. These two species, produced via photochemical dissociation of CuCl 4 2− upon 420 nm excitation into the ligand-to-metal-charge-transfer electronic state, are found to recombine into parent complexes with bimolecular rate constants of (9.0 ± 0.1) × 10 7 and (5.3 ± 0.4) × 10 8 M −1 s −1 in acetonitrile and dichloromethane, respectively. In dichloromethane, recombination occurs via a simple one-step addition. In acetonitrile, where [CuCl 3 ]− reacts with the solvent to form a [CuCl 3 CH 3 CN] − complex in less than 20 ps, recombination takes place via ligand exchange described by the associative interchange mechanism that involves a [CuCl 4 CH 3 CN] 2− intermediate. In both solvents, the recombination reaction is potential energy controlled.

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“…[43][44][45] Carboxylic groups are the most important interaction sites for metal binding to these molecules, as they are for many other organic and bioorganic molecules. Experimental and theoretical studies of the hydration of metal ions [48][49][50][51][52][53] and carboxylic functional groups [54][55][56][57] show that carboxylic groups are sites of strong association of divalent ions with NOM 24,[58][59][60] and that increasing the cation charge density increases the tendency to form a contact ion pair. 44,47 Here we present a computational molecular dynamics (MD) study of the interaction of Na + , Ca 2+ , and Mg 2+ with the carboxylic groups of a TNB NOM fragment and with acetate anion that provides an improved quantitative understanding of the structure and energetics of these interactions.…”

Section: Introductionmentioning

confidence: 99%

Metal Cation Complexation with Natural Organic Matter in Aqueous Solutions: Molecular Dynamics Simulations and Potentials of Mean Force

Iskrenova-Tchoukova¹,

Kalinichev²,

2010

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Natural organic matter (NOM, or humic substance) has a known tendency to form colloidal aggregates in aqueous environments, with the composition and concentration of cationic species in solution, pH, temperature, and the composition of the NOM itself playing important roles. Strong interaction of carboxylic groups of NOM with dissolved metal cations is thought to be the leading chemical interaction in NOM supramolecular aggregation.Computational molecular dynamics (MD) study of the interactions of Na + , Mg 2+ , and Ca 2+ with the carboxylic groups of a model NOM fragment and acetate anions in aqueous solutions provides new quantitative insight into the structure, energetics, and dynamics of the interactions of carboxylic groups with metal cations, their association and the effects of cations on the colloidal aggregation of NOM molecules. Potentials of mean force and the equilibrium constants describing overall ion association and the distribution of metal cations between contact ion pairs and solvent separated ions pairs were computed from free MD simulations and restrained umbrella sampling calculations. The results provide insight into the local structural environments of metal-carboxylate association and the dynamics of exchange among these sites. All three cations prefer contact ion pair to solvent separated ion pair coordination, and Na + and Ca 2+ show a strong preference for bidentate contact ion pair formation. The average residence time of a Ca 2+ ion in a contact ion pair with the carboxylic groups is of the order of 0.5 ns, whereas the corresponding residence time of a Na + ion is only between 0.02 and 0.05 ns. The average residence times of a Ca 2+ ion in a bidentate coordinated contact ion pair vs. a monodentate coordinated contact ion pair are about 0.5 ns and about 0.08 ns, respectively. On the 10-ns time scale of our simulations, aggregation of the NOM molecules occurs in the presence of Ca 2+ but not Na + or Mg 2+ . These results agree with previous experimental observations and are explained 3 by both Ca 2+ ion-bridging between NOM molecules and decreased repulsion between the NOM molecules due to the reduced net charge of the NOM-metal complexes. Simulations on a larger scale are needed to further explore the relative importance of the different aggregation mechanisms and the stability of NOM aggregates.4

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Coordination and ligand exchange dynamics of solvated metal ions

Cited by 176 publications

References 77 publications

A Combined QM/MM Molecular Dynamics Simulations Study of Nitrate Anion (NO₃^-) in Aqueous Solution

A Combined QM/MM Molecular Dynamics Simulations Study of Nitrate Anion (NO₃^-) in Aqueous Solution

Mechanism of Formation of Copper(II) Chloro Complexes Revealed by Transient Absorption Spectroscopy and DFT/TDDFT Calculations

Metal Cation Complexation with Natural Organic Matter in Aqueous Solutions: Molecular Dynamics Simulations and Potentials of Mean Force

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Coordination and ligand exchange dynamics of solvated metal ions

Cited by 176 publications

References 77 publications

A Combined QM/MM Molecular Dynamics Simulations Study of Nitrate Anion (NO3-) in Aqueous Solution

A Combined QM/MM Molecular Dynamics Simulations Study of Nitrate Anion (NO3-) in Aqueous Solution

Mechanism of Formation of Copper(II) Chloro Complexes Revealed by Transient Absorption Spectroscopy and DFT/TDDFT Calculations

Metal Cation Complexation with Natural Organic Matter in Aqueous Solutions: Molecular Dynamics Simulations and Potentials of Mean Force

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A Combined QM/MM Molecular Dynamics Simulations Study of Nitrate Anion (NO₃^-) in Aqueous Solution

A Combined QM/MM Molecular Dynamics Simulations Study of Nitrate Anion (NO₃^-) in Aqueous Solution