Neptunium magnetic properties

A lot of new coordination Np(V) complexes are still synthesized and several types of a novel CCB network have been found in their crystal structure [58-61]. Magnetic study is also performed about some neptunyl(+l) complexes [62], but there is no application of Np Mossbauer spectroscopy to them. Np Mossbauer spectroscopy is a very powerful and indispensable tool to study the electronic and the magnetic properties of neptunium complexes and will give several important information that cannot be provided with the magnetization measurement. Now Np Mossbauer spectroscopy is hardly performed due to the severe restrictions in handling transuranic materials and the output in this field is markedly reduced [63] however, many unsolved problems in this field that one should work on are left uncompleted. 

That magnetic measurements often raise more problems than they solve, is demonstrated for the indicated compound. We prepared a series of [ (C2H5N] i,An(NSC) e compounds (An = Th, U, Np, Pu) with cubic coordination of the actinide ion. We derived a consistent interpretation of the magnetic and optical properties of the uranium and the neptunium compounds (6 ). In the case of Pu we expect an isolated T1 ground state and a first excited state at about 728 cm-1. To our surprise we found a magnetic ground state much more pronounced than in the case of the hexachloro-complex, Fig. 4. 

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