Lanthanides aquo ions

Carnall, W. T. Fields, P. R. Rajnak, K. Electronic energy levels of the trivalent lanthanide aquo ions. I-IV. J. Chem. Phys. 1968, 49(10), 4424-4455. 

Electronic Energy Levels of the Trivalent Lanthanide Aquo Ions. II. Gd3+, W.T. Camall, P.R. Fields, andK. Rajnak. J. Chem. Phys. 49, 4443-4446 (1968). 

Since the energy levels of free lanthanide ions are not known, the relative nephelauxetic effect, /J1 is usually determined from the experimental data using the spectra of the lanthanide aquo ions as reference or standards. In such a case... 

The first known work on the intensities of the intra 4f—4f transitions is that of Van Vleck [53]. This was followed by the work of Jurbner and coworkers [54,55]. In 1962 Judd [56] and Ofelt [57] independently proposed the theory of forced electric-dipole transition which enabled the compilation of oscillator strengths for lanthanide aquo ions. 

Progress was made in the theoretical interpretation of the spectra of rare earth compounds and solutions in terms of energy level structure, in particular those of Pr3+ and Tm3+ with 4f2 and 4f12 configurations, respectively [123,124]. Differences in interpretation of the bands existed which were resolved in favour of f-f transitions [125]. Then the complex spectrum of Nd3+(4f3) was analyzed [126]. Jorgensen was one of the first to identify systematically the energy levels of lanthanide aquo ions [127]. 

Figure 4.14 Full packing diagram shows a 3D hydrogen-bonded network with channels containing either bpy and water guests or water guest only [27], (Reprinted with permission from L. Cunha-Silva, A. Westcott, N. Whitford, and M.J. Hardie, Flydrogen-bonded 3-D network structures of lanthanide aquo ions and 4,4 -bipyridine with carbaborane anions, Crystal Growth and Design, 6, no. 3, 726-735, 2006. 2006 American Chemical Society.)...

Sinha, S.P., 1983, Fluorescence spectra and lifetimes of the lanthanide aquo ions and their complexes, in Systematics and the Properties of the Lanthanides, ed. S.P. Sinha (Reidel, Dordrecht) ch. 10. 

P(M) was defined by Nugent etal. (1973b) to explain the apparent irregularities in lanthanide-metal enthalpies of sublimation and lanthanide aquo-ion enthalpies of formation. P(M) is shown in fig. 2 on an energy-level scale values are tabulated in... 

Ahmad, R. Dix, I. Hardie, M. J. 2003. Hydrogen-honded snperstrnctures of a small host molecule and lanthanide aquo ions. Inorg. Chem., 42 2182-4. 

Diketonates are insoluble in water. Diglycolates have been proposed as substitutes for studies in aqueous solutions. Another possibility deals with the use of lanthanide aquo-ions, and perchlorates and nitrates have been used in several cases they are soluble at pH < 6 and provide good shifts for a number of anionic functions. Eventually, good results in aqueous solutions have been obtained by using EDTA chelates which work at pH values as high as 10. 

Standard oxidation potentials referred to the normal hydrogen electrode (E°) for the divalent and trivalent lanthanide aquo ions are given in table 24.8 based primarily on the selected experimental results compiled by Chariot et al. (1971) and the systematic correlations summarized by Nugent (1975). Only Eu and Yb can persist for times of the order of minutes to hours in dilute acid solution, and can be readily produced by reduction of the trivalent ionic species (Laitinen and Taebel, 1941 Laitinen, 1942 Christensen et al., 1973). The value of E° = -0.43 V for the Eu(II-III) couple quoted in many previous compilations was obtained using both potentiometric and polarographic techniques. However, in a reevaluation of the solution thermodynamic properties of europium, Morss and Haug (1973) recommended the value E° = —0.35 V. 

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