Structure of Methanol Solvated Iodozinc(II) Complexes in Solution

The structures of the solvated zinc ion and the solvated zinc-iodide complexes in methanol solution have been determined by EXAFS. The zinc ion is six-coordinated in an octahedral fashion with a mean Zn-O bond distance of 2.071(4) Å. According to the stability constants of the zinc-iodide system in methanol solution the first complex, ZnI+, is suppressed, which may indicate that a coordination change takes place at this step. On the other hand, the second complex, ZnI2, predominates at excess of iodide. The methanol solvated ZnI2 complex has a tetrahedral structure with mean Zn-I and Zn-O bond distances of 2.55(1) and 1.99(1) Å, respectively. The mean Zn-I bond distance in a solution containing a maximal content of ZnI+, ca. 12%, strongly indicates that the first complex also has a tetrahedral structure.