The dipole moment of water in the first hydration shell of a monovalent ion

1968 ◽  
Vol 46 (21) ◽  
pp. 2407-2411 ◽  
Author(s):  
Dieter K. Ross
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
Continuous Medium ◽  
Hydration Shell ◽  
Bulk Water ◽  
Water Molecules ◽  
The Mean ◽  
Monovalent Ion ◽  
Coordinated Water ◽  
First Hydration Shell

The mean dipole moment of the water molecules in contact with a monovalent ion is estimated. The first hydration shell of a spherical ion is assumed to contain either four or six coordinated water molecules, while the water molecules outside this shell are replaced by a continuous medium whose dielectric constant is that corresponding to bulk water at 25 °C. It is found that the dipole moment induced in the attached water molecules is comparable with its permanent dipole moment.

scholarly journals The Interaction Energy of an Isolated Monovalent Ion

1968 ◽  
Vol 21 (5) ◽  
pp. 597 ◽  
Author(s):  
DK Ross
Keyword(s):  
Dipole Moment ◽  
Aqueous Medium ◽  
Interaction Energy ◽  
Dipole Moments ◽  
Hydration Shell ◽  
Water Molecules ◽  
Li Ion ◽  
Monovalent Ion ◽  
First Hydration Shell

The interaction energy of a monovalent ion in an aqueous medium at 25�C is determined. It is also found that the water molecules in the first hydration shell of the ion have a mean dipole moment far in excess of their permanent dipole moments. Thus, for example, the increase in the dipole moment of the attached water molecules. due to the presence of an ion is about 60% for the small four-coordinated Li+ ion and about 30% for the larger four-coordinated 1- ion. Calculations are also carried out on the assumption that the ions are six coordinated.

The Second Hydration Shell of Li+ in Aqueous LiI from X-Ray and MD Studies

1981 ◽  
Vol 36 (10) ◽  
pp. 1076-1082 ◽  
Author(s):  
T. Radnai ◽  
G. Pálinkás ◽  
Gy I. Szász ◽  
K. Heinzinger
Keyword(s):  
Hydration Shell ◽  
Distribution Functions ◽  
Dynamics Simulation ◽  
Scattering Data ◽  
Water Molecules ◽  
Radial Distribution Functions ◽  
Partial Structure ◽  
X Ray ◽  
Total Structure ◽  
First Hydration Shell

Indications from a molecular dynamics simulation of a 2.2 molal LiI solution of the existence of a second hydration shell of Li+ have been checked by an x-ray investigation of the same solution. The scattering data are analysed via partial structure functions and radial distribution functions which have been obtained from a model fitted to the total structure function. Experiment and simulation agree on first neighbor ion-water distances. An octahedral arrangement of six water molecules in the first hydration shell of Li+ and additional twelve water molecules in the second shell have been verified by the experiment.

A Molecular Dynamics Study of the Structure of an Aqueous CsF Solution

1983 ◽  
Vol 38 (2) ◽  
pp. 214-224 ◽  
Author(s):  
Gy. I. Szász ◽  
K. Heinzinger
Keyword(s):  
Molecular Dynamics ◽  
Hydration Shell ◽  
Distribution Functions ◽  
Dynamics Simulation ◽  
Water Model ◽  
Water Molecules ◽  
Heat Of Solution ◽  
Average Temperature ◽  
Experimental Density ◽  
First Hydration Shell

Abstract A molecular dynamics simulation of a 2.2 molal aqueous CsF solution has been performed employing the ST2 water model. The basic periodic cube with a sidelength of 18.50 Å contained 200 water molecules, and 8 ions of each kind, corresponding to an experimental density of 1.26 g/cm3. The simulation extended over 6.5 ps with an average temperature of 307 K. The structure of the solution is discussed by means of radial distribution functions and the orientation of the water molecules. The computed hydration numbers in the first shell of Cs+ and F- are 7.9 and 6.8, respectively; the corresponding first hydration shell radii are 3.22 A and 2.64 A, respectively. Values for the hydration shell energies and the heat of solution have been calculated.

scholarly journals Crystal structure of magnesium selenate heptahydrate, MgSeO4·7H2O, from neutron time-of-flight data

2014 ◽  
Vol 70 (9) ◽  
pp. 134-137 ◽  
Author(s):  
A. Dominic Fortes ◽  
Matthias J. Gutmann
Keyword(s):  
Crystal Structure ◽  
Unit Cell Volume ◽  
Lattice Water Molecule ◽  
Water Molecules ◽  
Tetrahedral Coordination ◽  
Flight Data ◽  
Lattice Water ◽  
Neutron Time ◽  
The Mean ◽  
Coordinated Water

MgSeO4·7H2O is isostructural with the analogous sulfate, MgSO4·7H2O, consisting of isolated [Mg(H2O)6]2+octahedra and [SeO4]2−tetrahedra, linked by O—H...O hydrogen bonds, with a single interstitial lattice water molecule. As in the sulfate, the [Mg(H2O)6]2+coordination octahedron is elongated along one axis due to the tetrahedral coordination of the two apical water molecules; these have Mg—O distances of ∼2.10 Å, whereas the remaining four trigonally coordinated water molecules have Mg—O distances of ∼2.05 Å. The mean Se—O bond length is 1.641 Å and is in excellent agreement with other selenates. The unit-cell volume of MgSeO4·7H2O at 10 K is 4.1% larger than that of the sulfate at 2 K, although this is not uniform; the greater part of the expansion is along theaaxis of the crystal.

Dielectric dispersion and dipole moment of myoglobin in water

1972 ◽  
Vol 328 (1574) ◽  
pp. 371-387 ◽  
Keyword(s):  
Crystal Structure ◽  
Dipole Moment ◽  
Protein Concentration ◽  
Hydration Shell ◽  
Sperm Whale ◽  
Dielectric Dispersion ◽  
Water Molecules ◽  
Solution Conductivity ◽  
Sperm Whale Myoglobin ◽  
Good Agreement

The parameters of dielectric dispersion at radio frequencies in aqueous solutions of horse and sperm whale myoglobin have been measured as functions of protein concentration, solution conductivity and temperature. From these dependences it is shown that, of the likely interpretations, the mechanism of molecular rotation is best able to account for the observed dispersion. The results are consistent with a dipole moment of around 150D for the myoglobin molecule and a hydration shell of about two water molecules thickness. This value of dipole moment is shown to be in good agreement with that obtained from calculations based on the known crystal structure.

Water and Metal Cations in Solution

2019 ◽  
Author(s):  
Jean-Pierre Jolivet
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
High Dielectric Constant ◽  
Reaction Medium ◽  
Fixed Number ◽  
Water Molecules ◽  
Dipolar Interactions ◽  
Solvated Ions ◽  
High Dielectric ◽  
High Polarity

Water has an exceptional ability to dissolve minerals. It is safe and chemically stable, and it remains liquid over a wide temperature range. Thus, it is the best solvent and reaction medium for both laboratory and industrial purposes. Water is able to dissolve ionic and ionocovalent solids because of the high polarity of the molecule (dipole moment μ = 1.84 Debye) as well as the high dielectric constant of the liquid (ε = 78.5 at 25°C). This high polarity allows water to exhibit a strong solvating power: that is, the ability to fix onto ions as a result of electrical dipolar interactions. Water is also an ionizing liquid able to polarize an ionocovalent molecule. For example, the solvolysis phenomenon increases the polarization of the HCl molecule in aqueous solution. Finally, owing to the high dielectric constant of the liquid, water is a dissociating solvent that can decrease the electrostatic forces between solvated cations and anions, allowing their dispersion as H+solvated and Cl−solvated through the liquid. (The attractive force F between charges q and q′ separated by the distance r is given by Coulomb’s law, F = qq′/εr2.) These characteristics are rarely found together in common liquids. The dipole moment of the ethanol molecule (μ = 1.69 Debye) is close to that of water, but the dielectric constant of ethanol is much lower (ε = 24.3). Ethanol is a good solvating liquid, but a poor dissociating one; consequently, it is considered a bad solvent of ionic compounds. Dissolution in water of an ionic solid such as sodium chloride is limited to dipolar interactions with Na+ and Cl− ions and their dispersion in the liquid as solvated ions, regardless of the pH of the solution. Cations with higher charge, especially cations of transition metals, retain a fixed number of water molecules, thereby forming a true coordination complex [M(OH2)N]z+ with a well-defined geometry. In addition to the dipolar interactions, water molecules behave as true ligands because they are Lewis bases exerting an electron σ-donor effect on the empty orbitals of the cation.

Spin-state dependence of the structural and vibrational properties of solvated iron(ii) polypyridyl complexes from AIMD simulations: II. aqueous [Fe(tpy)2]Cl2

2019 ◽  
Vol 21 (2) ◽  
pp. 650-661 ◽  
Author(s):  
Latévi M. Lawson Daku
Keyword(s):  
Hydration Shell ◽  
State Dependence ◽  
Distribution Functions ◽  
Water Molecules ◽  
Radial Distribution Functions ◽  
Spin States ◽  
Polypyridyl Complexes ◽  
Coordination Numbers ◽  
A Chain ◽  
First Hydration Shell

LS and HS Fe–O radial distribution functions and running coordination numbers for aqueous [Fe(tpy)2]Cl2: in both spin states, the first hydration shell of [Fe(tpy)2]2+ consists in a chain of ∼15 hydrogen-bonded water molecules wrapped around the ligands.

The Structural and Dynamic Properties of some Transition Metal Aqua Cations: Results from Neutron Scattering

1995 ◽  
Vol 50 (2-3) ◽  
pp. 247-256 ◽  
Author(s):  
G. W. Neilson ◽  
S. Ansell ◽  
J. Wilson
Keyword(s):  
Transition Metal ◽  
Neutron Scattering ◽  
Dynamic Properties ◽  
Hydration Shell ◽  
Electrolyte Solutions ◽  
Bulk Water ◽  
Water Molecules ◽  
Quasielastic Neutron ◽  
Quasielastic Neutron Scattering ◽  
Insight Into

Abstract The following paper comprises a survey of the role neutron scattering methods have played to help understand the origins of the diverse properties of electrolyte solutions which contain transition metal cations. It is seen how neutron diffraction and isotopic substitution is able to resolve the local structure around contrasting ions, such as Cr3+ , Ni2+, Fe3+ , Fe2+, Cu2+, without recourse to sophisticated modelling procedures. Quasielastic neutron scattering (QNS) provides insight into the dynamics of the protons in solution. The results enable one to distinguish between cations whose water molecules are coordinated on time scales larger than 5 x 10-9 s, shorter than 10-10s, or intermediate between those two limits. QNS also provides information on the existence of a second relatively short-lived hydration shell distinct from the bulk water.

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