COORDINATION CHEMISTRY OF NEPTUNYL(V) COMPOUNDS BY MEANS OF MOSSBAUER-SPECTROSCOPY

Five neptunyl(V) compounds were synthesized and studied by Np-237 Moss bauer Spectroscopy The isomer shifts (delta) of the Mossbauer spectra ranged from -18.6 to -19.0 mm s(-1) for the compounds with Np atoms su rrounded by seven oxygen atoms. Interlaced two sets of hyperfine split ting were observed in the spectra for the acetate and the benzoate, de lta's of one set with larger magnetic splitting were -19.4 and -19.5 m m s(-1), respectively, but those of the other set with smaller magneti c splitting were -13.2 and -10.8 mm s(-1), respectively. From the comp arison of the present results with those reported on neptunyl(V) and ( VI) compounds, it is concluded that there are two neptunium sites in t he acetate and the benzoate in their structure, one is the site with t he coordination number (CN) of 7 and the other is that with CN of 8. ( C) 1998 Elsevier Science S.A.