Abstract
A method is described which allows precise isotopic analysis of the less labile oxygen atoms in the first coordination sphere of Mo(V) in aqueous media. Rapid conversion of Mo/sup v/(aq), as generated by Hg/sup 0/ reduction of Mo(VI) in ca. 3 M HCl solution, to Mo/sub 2/O/sub 4/EDTA/sup 2 -/ in labeled water shows no appreciable transfer of solvent oxygens to the product ion. Aquated Mo(V), commonly referred to as Mo/sub 2/O/sub 4//sup 2 +/, is shown to contain 1.98 +- 0.03 slowly and 2.04 +- 0.06 rapidly exchanging oxygens (on the minute time scale) in agreement with the formula Mo/sub 2/O/sub 4//sup 2 +/(aq). The slowly exchanging oxygens are shown by Raman and IR /sup 18/O shifts to be the bridging type having a t/sub 1/2/ of about 100 h at 40/sup 0/C while the yl-oxygens have a t/sub 1/2/ of about 4 min at 0/sup 0/C. Solvent in the coordination sphere exchanges much more rapidly. Some of the kinetic parameters and medium effects are evaluated and discussed.
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