Actinides ionization energy

For vanadium and chromium the first ionization energies are much lower than the first ionization energies of phosphorus and sulphur, respectively. This explains the high heats of formation of VC13 and CrCl3. In uranium, the tetravalent state is more stable than that in tungsten because uranium as an actinide has a different electron configuration. 

Experimental Ionization Energies (eV) and Assignments for Bis(cyclooctatetrene) actinides 7... 

Cumulative ionization energies across the lanthanide Series (reproduced by permission of Macmillan from S.A. Cotton, Lanthanides and Actinides, Macmillan, 1991). 

Although a full range of ionization energies is not available throughout the actinide series and thus cannot be used predictively, as for the lanthanides (Table 2.2), electrode potentials are more generally available (Table 9.5) and thus can be so used, as follows ... 

Table 7. Ionization energies (eV) of some cyclopentadienyl and cyclooctatetraenyl lanthanide and actinide compounds...

Sugar, J., "Revised ionization energies of the neutral actinides," Chem. Phys., 1974, 60, 4103. 

For the actinide molecules ThO, UO, UO2, and PUO2, contemporary methods [89,91,92] yield ionization energies as much as 2.4 eV smaller than those from the electron impact method [93]. Although one could arbitrarily correct the ionization energies of Chandrasekharaiah and Gingerich [3] by this amount, it is preferable to treat the electron-impact results with suspicion until the LnO ionization energies can be re-measured. 

By analogy with actinide compounds and on the basis of the Xa calculations, bands a and b are undoubtedly associated with ionizations from the e2u and e2g MO s, respectively. The fine structure associated with these bands is probably due to a vibronic Jahn-Teller effect in the ion states. Band c is taken to represent the ionization from both the ejg and e2 MO s. This band shows a shoulder on the higher ionization energy side, the separation of which from the main peak compares well with the computed Xa splitting. Moreover, the total rela-... 

Electronic configurations (free atom or ion) and ionization energies (kJ mol of rare earths and actinides a ... 

In fig. 4 the first to fourth ionization energies of the lanthanides and actinides are plotted for comparison. It is evident that the half-filled shell effect is much less significant for the actinides than for the lanthanides. This diminished effect is caused by the greater radial extension of the 5f orbitals compared to the 4f orbitals and manifests itself in the easier accessibility of 4-1- oxidation states of many actinides. 

Hydration properties are also discussed by Rizkalla and Choppin (1992) and in the chapter by Rizkalla and Choppin (ch. 127) of this volume. For internal consistency, especially when used to calculate ionization enthalpies of the heavy actinides, hydration enthalpies of David (table 3, this chapter) on the absolute scale of yd(H= — 1114kJmol were used to calculate ionization energies in table 2. 

In contrast to the now relatively extensive metal-metal bonded chemistry of sub valent Mg, Al, and Zn, homomet2Jlic bonds involving the 6s and 7s orbitals of the lanthanide and actinides elements are rare (diatomic overlap between the 5f orbitals in Uj and other cases is discussed later). Their absence is largely a consequence of the rdatively low second and third ionization energies (compared to Al), which reduce the stability of the -i-l and +2 oxidation states. Examples... 

A key fundamental property of small molecules is the IE, which allows thermodynamic properties of neutral species to be derived from those of cations, and vice versa. Only a few actinide molecular ionization energies have been accurately measured by spectroscopic techniques, specifically by Heaven and coworkers lE(UO) = 6.03107 0.00003 eV (Goncharov et al., 2006), 1E(U02)=6.127 0.001 eV (Merritt et al., 2008), lE(ThO)=6.60263 0.00003 eV (Goncharov and Heaven, 2006), and lE(ThF)=6.3952 0.0037 eV (Barker et al., 2012). Mar alo and coworkers have employed electron transfer of actinide cations with neutral species to... 

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