Hydration mechanisms of Cu(2+): tetra-, penta- or hexa-coordinated?
To shed light on the hydration mechanisms of Cu(2+), we carried out simulations in both gas and aqueous phases by using the ab initio molecular dynamics technique equipped with the method of constraint. The simulations provide relatively complete free-energy information, from which the coexisting coordination pictures are clearly revealed. In both phases, the 5-fold complex is the most thermodynamically favorable state whereas the classically-accepted 6-fold occurs as a very weak stable state. In the gas phase, the 4-fold complex is a more reachable state than the 6-fold, but it cannot hold stably in the aqueous phase. The extracted thermodynamic values illustrate that in the gas phase the entropy term dominates the evolution processes to the 5-fold whereas in the aqueous case the energy term is dominant.
Liu
Xiandong
X
State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, PR China.
Lu
Xiancai
X
Jan Meijer
Evert
E
Wang
Rucheng
R
D003300:Copper / Q000737:chemistry*; D019277:Entropy; D007536:Isomerism; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D012997:Solvents / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
D012997:Solvents; D014867:Water; D003300:Copper