EXAFS AND AB-INITIO MOLECULAR-ORBITAL STUDIES ON THE STRUCTURE OF SOLVATED SILVER(I) IONS

Structure parameters of solvated silver(I) ions in eight neat solvents were determined by extended X-ray absorption fine structure spectrosc opy. The coordination geometry of the solvated silver(I) ion is four-c oordinate tetrahedral at the Ag-O bond distances of 239 pm in trimethy lphosphate, 239 pm in N,N-dimethylformamide, 238 pm in 1,1,3,3-tetrame thylurea, 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 ethylenediami ne as nitrogen-donating solvents. According to our present ab initio m olecular orbital calculations concerning the structure of the silver(I ) ion bound by n molecules of hydrogen cyanide (n = 1-6) and acetonitr ile (n = 1-5) in the gas phase, the maximal stabilization for the solv ation is observed at n = 4. The results of the theoretical calculation s in the gas phase are consistent with the experimental observations i n solution.