symmetry, optical properties and thermodynamics of neptunium(v) complexes对称的光学性质和热力学镎(v)复合物.pdf

Symmetry 2010, 2, 1-14; doi:10.3390/sym2010001 OPEN ACCESS symmetry ISSN 2073-8994 /journal/symmetry Review Symmetry, Optical Properties and Thermodynamics of Neptunium(V) Complexes Linfeng Rao * and Guoxin Tian Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; E-Mail: gtian@ * Author to whom correspondence should be addressed; E-Mail: lrao@. Received: 25 November 2009; in revised form: 19 December 2009 / Accepted: 21 December 2009 / Published: 28 December 2009 Abstract: Recent results on the optical absorption and symmetry of the Np(V) complexes with dicarboxylate and diamide ligands are reviewed. The importance of recognizing the “silent” feature of centrosymmetric Np(V) species in analyzing the absorption spectra and calculating the thermodynamic constants of Np(V) complexes is emphasized. Keywords: symmetry; optical absorption; thermodynamics; neptunium; complexation 1. Introduction Neptunium, an element in the actinide series of the periodic table, has an electronic configuration of [Rn]5f5 2 4 1 2 7s (or [Rn]5f 6d 7s ). The most stable oxidation state of neptunium in aqueous solutions is 2 Np(V) with an electronic configuration of [Rn]5f . Np(V) exists in aqueous solutions as the hydrated NpO2+ cation and exhibits characteristic absorption bands in the near IR region. In particular, the hydrated NpO2+ cation has an intensive absorption band at 980 nm (ε = 395 M-1cm-1) that