TY - JOUR

T1 - Quantum chemical studies of the hydration of Sr2+ in vacuum and aqueous solution

AU - Kerridge, Andrew

AU - Kaltsoyannis, Nikolas

PY - 2011/4/26

Y1 - 2011/4/26

N2 - The geometric structures of gas-phase Sr2+ hydrates are calculated quantum chemically by using hybrid (B3LYP) and meta-GGA (TPSS) density functional theory, and a range of thermodynamic data (including sequential bond enthalpies, entropies and free energies for the reactions Sr2+ (H2O)(n-1)+ H2O 'Sr2+(H2O)(n)) are shown to be in excellent agreement with experiment. When the number of coordinating water molecules exceeds six, such that water begins to occupy the second solvation shell, it is found that detailed analysis based on both geometrical and conformational entropy is required in order to confidently identify the experimentally observed structures. The significant increase in coordination number observed experimentally between the gas-and aqueous-phase species is successfully reproduced, as is the first solvation shell geometry. Inaccurate second shell geometries imply that larger model systems may be required to achieve agreement with experiment. Candidate species for on-going computational studies of the interaction of hydrated Sr2+ with brucite surfaces have been identified.

AB - The geometric structures of gas-phase Sr2+ hydrates are calculated quantum chemically by using hybrid (B3LYP) and meta-GGA (TPSS) density functional theory, and a range of thermodynamic data (including sequential bond enthalpies, entropies and free energies for the reactions Sr2+ (H2O)(n-1)+ H2O 'Sr2+(H2O)(n)) are shown to be in excellent agreement with experiment. When the number of coordinating water molecules exceeds six, such that water begins to occupy the second solvation shell, it is found that detailed analysis based on both geometrical and conformational entropy is required in order to confidently identify the experimentally observed structures. The significant increase in coordination number observed experimentally between the gas-and aqueous-phase species is successfully reproduced, as is the first solvation shell geometry. Inaccurate second shell geometries imply that larger model systems may be required to achieve agreement with experiment. Candidate species for on-going computational studies of the interaction of hydrated Sr2+ with brucite surfaces have been identified.

KW - computational chemistry

KW - density functional calculations

KW - hydrates

KW - strontium

KW - thermodynamics

KW - DENSITY-FUNCTIONAL THEORY

KW - X-RAY-DIFFRACTION

KW - GAS-PHASE

KW - ALKALINE-EARTH

KW - METAL-IONS

KW - BASIS-SETS

KW - ENERGIES

KW - WATER

KW - MOLECULES

KW - ENTROPIES

U2 - 10.1002/chem.201003226

DO - 10.1002/chem.201003226

M3 - Journal article

VL - 17

SP - 5060

EP - 5067

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

SN - 0947-6539

IS - 18

ER -