Molecular Dynamics Analysis of Stabilities of Transitional Hydrogen Bonds in Sulfate Aqueous Solution

Different mechanisms of H-bond formation between sulfate anion and water are presented using molecular dynamics simulations. Multi-centered hydrogen bonds were observed. Always the hydrogen bridge making/breaking goes according to the large angular jump mechanism. Moreover, classical, bifurcated and trifurcated hydrogen bonds between water and sulfate have transitional character. This is supported by free energies of binding of water to sulfate ion determined for particular types of hydrogen bridges. This phenomenon is similar to the one observed in the hydration shell of perchlorate anion. Nevertheless the amplitudes of angular jump as well as hydrogen bond lifetimes are different in both cases.