EXAFS and <i>ab Initio</i> Molecular Orbital Studies on the Structure of Solvated Silver(I) Ions

Abstract

Structure parameters of solvated silver(I) ions in eight neat solvents were determined by extended X-ray absorption fine structure spectroscopy. The coordination geometry of the solvated silver(I) ion is four-coordinate tetrahedral at the Ag−O bond distances of 239 pm in trimethylphosphate, 239 pm in N,N-dimethylformamide, 238 pm in 1,1,3,3-tetramethylurea, and 238 pm in dimethyl sulfoxide as oxygen-donating solvents, and at the Ag−N bond distances of 229 pm in acetonitrile, 230 pm in 2-methylpyridine, 229 pm in n-propylamine, and 231 pm in ethylenediamine as nitrogen-donating solvents. According to our present ab initio molecular orbital calculations concerning the structure of the silver(I) ion bound by n molecules of hydrogen cyanide (n = 1−6) and acetonitrile (n = 1−5) in the gas phase, the maximal stabilization for the solvation is observed at n = 4. The results of the theoretical calculations in the gas phase are consistent with the experimental observations in solution.