Solvation Structures of Manganese(II), Iron(II), Cobalt(II), Nickel(II), Copper(II), Zinc(II), and Gallium(III) Ions in Methanol, Ethanol, Dimethyl Sulfoxide, and Trimethyl Phosphate As Studied by EXAFS and Electronic Spectroscopies

Abstract

Solvation structures of the Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Ga(III) ions in methanol (MeOH), ethanol (EtOH), dimethyl sulfoxide (DMSO), and trimethyl phosphate (TMP) have been determined using extended X-ray absorption fine structure (EXAFS) spectroscopy. In MeOH, EtOH, and DMSO, the solvation structures of all metal(II,III) ions are 6-coordinate octahedral as in water, and the M−O bond lengths are similar to those in water. In the bulky solvent TMP, the 5-coordinate solvation structure is observed for the Zn(II) ion without ligand-field stabilization. The Ga(III) ion has the 6-coordinate solvation structure in TMP despite its smaller ionic radius than the Zn(II) ion because of the higher charge density on the Ga(III) ion. In the cases of the Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) ions, the electronic absorption spectra have been measured in MeOH, EtOH, and DMSO. All solutions for each metal(II) ion show a spectral pattern similar to that in water, which is consistent with the results of the EXAFS measurements.