Zur Existenz der Kationen VO2+, TiO2+ und ZrO2+

Dehnicke, Kurt; Weidlein, Johann

doi:10.1002/ange.19660782317

Cited by 5 publications

(2 citation statements)

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“…In contrast to the monovalent oxo-ions, no studies have been reported for the divalent transition-metal oxo-cations except for those published by Dehnicke et al, 20 Ellis et al, 21 and Davies et al 22 5 ]Cl 2 have also been reported in literature discussing the structure of these complexes in great detail.…”

Section: −5 ]mentioning

confidence: 84%

Quantum mechanical charge field molecular dynamics simulation of the TiO²⁺ ion in aqueous solution

et al. 2007

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Structural and dynamical properties of the TiO(2+) ion in aqueous solution have been investigated by using the new ab initio quantum mechanical charge field (QMCF) molecular dynamics (MD) formalism, which does not require any other potential functions except those for solvent-solvent interactions. Both first and second hydration shell have been treated at Hartree-Fock (HF) quantum mechanical level. A Ti-O bond distance of 1.5 A was observed for the [Ti=O](2+) ion. The first hydration shell of the ion shows a varying coordination number ranging from 5 to 7, five being the dominant one and representing one axial and four equatorial water molecules directly coordinated to Ti, which are located at 2.3 A and 2.1 A, respectively. The flexibility in the coordination number reflects the fast exchange processes, which occur only at the oxo atom, where water ligands are weakly bound through hydrogen bonds. Considering the first shell hydration, the composition of the TiO(2+) hydrate can be characterized as [(H(2)O)(0.7)(H(2)O)(4) (eq)(H(2)O)(ax)](2+). The second shell consists in average of 12 water molecules located at a mean distance of 4.4 A. Several other structural parameters such as radial and angular distribution functions and coordination number distributions were analyzed to fully characterize the hydration structure of the TiO(2+) ion in aqueous solution. For the dynamics of the TiO(2+) ion, different sets of dynamical parameters such as Ti=O, Ti-O(eq), and Ti-O(ax) stretching frequencies and ligands' mean residence times were evaluated. During the simulation time of 15 ps, 3 water exchange processes in the first shell were observed at the oxo atom, corresponding to a mean residence time of 3.6 ps. The ligands' mean residence time for the second shell was determined as 3.5 ps.

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Section: −5 ]mentioning

confidence: 84%

Quantum mechanical charge field molecular dynamics simulation of the TiO²⁺ ion in aqueous solution

et al. 2007

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“…Considering the available experimental data ,,− for tetravalent cations and although the high charge on the ion gives rise to the formation of [M(OH) m ] 4− m species, two types of behavior according to hydrolysis phenomena can be identified. On one hand, heavy metal ions such as Th(IV), U(IV), Np(IV), or Pu(IV) can form stable aquaions under very acid conditions (pH < 1).…”

Section: Resultsmentioning

confidence: 99%

General Quantum-Mechanical Study on the Hydrolysis Equilibria for a Tetravalent Aquaion: The Extreme Case of the Po(IV) in Water

et al. 2008

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A systematic study of the different hydrolyzed species derived from the hydrated Po(IV) in water, [Po(H(2)O)(n)(OH)(m)]((4-m)) for 1 m 4, and 4 m + n 9, has been carried out by means of quantum mechanical computations. The effects of outer solvation shells have been included using a polarizable continuum dielectric model. For a fixed number of hydroxyl groups, the preferred hydration number for the Po(IV) can be determined in terms of Gibbs energy. It is shown that the hydration number (n) systematically decreases with the increase in the number of hydroxyl groups (m) in such a way the total coordination number (n + m) becomes smaller, being 9 in the aquocomplex and 4 in the neutral hydroxo-complex. Free energies for the hydrolysis processes involving Po(IV) complexes and a different number of hydroxyl groups have been computed, revealing the strong tendency toward hydrolysis exhibited by these complexes. The predominant species of Po(IV) in aqueous solutions are ruled by a dynamical equilibrium involving aggregates containing in the first coordination shell OH(-) groups and water molecules. Although there is not experimental information to check the theoretical predictions, theoretical computations in solution seem to suggest that the most likely clusters are [Po(H(2)O)(5)(OH)(2)](2+) and [Po(H(2)O)(4)(OH)(2)](2+). The geometry of the different clusters is ruled by the trend of hydroxyl groups to be mutually orthogonal and to promote a strong perturbation of the water molecule in trans-position by lengthening the Po-H(2)O distances and tilting the corresponding bond angle. A general thermodynamic cycle is defined to compute the Gibbs free energy associated to the formation of the different hydrolyzed forms in solution. From it, the estimates of pK(a) values associated to the different protolytic equilibria are provided and discussed. Comparison of the relative values of pK(a) along a hydrolysis series with the experimental values for other tetravalent cations supports its consistency.

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Darstellung und Eigenschaften der Dioxalato‐monovanadate(V)

1969

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Zur Existenz der Kationen VO₂⁺, TiO²⁺ und ZrO²⁺

Cited by 5 publications

References 6 publications

Quantum mechanical charge field molecular dynamics simulation of the TiO²⁺ ion in aqueous solution

Quantum mechanical charge field molecular dynamics simulation of the TiO²⁺ ion in aqueous solution

General Quantum-Mechanical Study on the Hydrolysis Equilibria for a Tetravalent Aquaion: The Extreme Case of the Po(IV) in Water

Darstellung und Eigenschaften der Dioxalato‐monovanadate(V)

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Zur Existenz der Kationen VO2+, TiO2+ und ZrO2+

Cited by 5 publications

References 6 publications

Quantum mechanical charge field molecular dynamics simulation of the TiO2+ ion in aqueous solution

Quantum mechanical charge field molecular dynamics simulation of the TiO2+ ion in aqueous solution

General Quantum-Mechanical Study on the Hydrolysis Equilibria for a Tetravalent Aquaion: The Extreme Case of the Po(IV) in Water

Darstellung und Eigenschaften der Dioxalato‐monovanadate(V)

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Zur Existenz der Kationen VO₂⁺, TiO²⁺ und ZrO²⁺

Quantum mechanical charge field molecular dynamics simulation of the TiO²⁺ ion in aqueous solution

Quantum mechanical charge field molecular dynamics simulation of the TiO²⁺ ion in aqueous solution