Hydrates of Cu2+ and CuCl+ in Dilute Aqueous Solution: A Density Functional Theory and Polarized Continuum Model Investigation

作者：Xia, Fei-Fei; Yi, Hai-Bo^*; Zeng, Dewen

来源：Journal of Physical Chemistry A, 2010, 114(32): 8406-8416.

DOI：10.1021/jp1000804

• CHLORO COMPLEX-FORMATION
• AB-INITIO
• EXCITED-STATES
• WATER
• COPPER(II)
• SOLVATION
• STABILITY
• SPECTRA
• TEMPERATURES
• ENERGIES

In this work, structures, and properties of Cu2+ and CuCl+ hydrates in the gas and aqueous phases have been investigated using the B3LYP method. Contact ion pair (CIP) and solvent-shared ion pair (SSIP) were both taken into account for CuCl+ hydrates. Our calculations show that [Cu(H2O)(n)](2+) clusters favor a very open four-coordinated structure for n = 5-12 in the gas phase, while a five-coordinated conformer is favored for n >= 8 in the aqueous phase. An approximate complete solvation shell of Cu2+ in the aqueous phase needs more than 12 water molecules, while that of CuCl+ in the aqueous phase needs only about eight water molecules. For [CuCl(H2O)(n)](+) clusters, the most stable structure is a four-coordinated GIP conformer for n = 4-7 in the gas phase and a five-coordinated CIP conformer for n = 8-10 in the aqueous phase. However, the five-coordinated CIP/h conformer (CIP conformer that the axial chloride atom tends to dissociate) of [CuCl(H2O)(n)](+) clusters becomes more favorable as n increases to 11. As the hydration process proceeds, the charges on the copper atom of [Cu(H2O)(n)](2+) clusters decrease, while those of [CuCl(H2O)(n)](+) clusters increase (probably due to the dissociation of Cl-). The d-d electron transition and partial charge transition band around 160 nm of the five-coordinated conformer of [Cu(H2O)(n)](2+) clusters and those bands (similar to 170 and similar to 160 nm) of SSIP or five-coordinated CIP/h conformers of [CuCl(H2O)(n)](+) clusters are coincident with the absorption of [Cu](2+)(aq) species (similar to 180 nm) resolved from the spectra obtained in trace CuCl2 (ca. 10(-5) mol.kg(-1)) + LiCl (0-18 mol.kg(-1)) aqueous solution, while those of five-coordinated CIP conformers of [CuCl(H2O)(n)](+) clusters (n = 8 and 9) around 261 and 247 nm correspond to the absorption of [CuCl](+) (aq) species (similar to 250 nm). Our calculated electronic spectra indicate that the typical peak of copper(II)-chloride complexes changes from 180 to 250 nm, and 275 nm, as the process of Cl- coordination. For [Cu](2+)(aq), [CuCl](+)(aq), and [CuCl2](0)(aq) species, the central Cu(II) atom prefers five-coordination.

• 出版日期2010-8-19
• 单位湖南大学