5f hybridization

Naegele JR, Ghijsen J (1985) Localization and Hybridization of 5f States in the Metallic and Ionic Bond as Investigated by Photoelectron Spectroscopy. 59160 197-262 Nag K, Bose SN (1985) Chemistry of Tetra-and Pentavalent Chromium. 63 153-197 Naletvajski RE (1993) The Hardness Based Molecular Charge Sensitivities and Their Use in the Theory of Chemical Reactivity. 80 115-186 Natan MJ, see Hoffman BM (1991) 75 85-108 Neilands JB, see Liu A (1984) 58 97-106 Neilands JB, see Chimiak A (1984) 58 89-96... 

Naegele, J. R., Ghijsen, J. Localization and Hybridization of 5f States in the Metallic and Ionic Bond as Investigated by Photoelectron Spectroscopy. Vol. 59/60, pp. 197-262. 

The increase of the total magnetic moment from USe to UTe is the result of the decrease of spin moment from 5f electrons due to the stronger hybridization effects between U atom and Te atom. 

Already in the thorium dimer, Th2, we see another pattern. The 7s population is reduced to close to one. The electron is moved to 6d, and a strong quadruple bond is formed, involving three two-electron bonds and two 6d one-electron bonds. We also start to see some population of the 5f orbitals that hybridizes with 6d. 

We have particularly emphasized the metallic bond, because the peculiar properties of the 5f wavefunctions are better seen in its context. Also, in compounds, however, f-f overlapping as well as hybridization play a conspicuous role. Only, the presence of a nonactinide element introduces other factors that have to be taken into account ... 

This leads to a second remark, which concerns hybridization, of which we have also shortly spoken. In choosing the o()i s in (23), we may mix to the 5f wave functions the 6d, 7 s, wave functions by taking hybridized orbitals wave functions as a starting point. 

A pioneering work for their qualitative understanding was the covalent treatment of the 5f-6d hybridization due to FriedeP Like p orbitals, f orbital are antisymmetric (il)(— R) = — tl)(R)) thus by linear combination with symmetric d orbitals, they give rise to highly directive hybrid orbitals (like s-p hybrids). Thus in Pa, U, Np and Pu metals each atom has four nearest neighbours more or less coplanar and at 90°. Let s take the example of a-U and put the nearest neighbours along the x and z axes. Necessary hybrid orbitals for such positions are ... 

The 5f electrons are itinerant and bonding, and from narrow 5f-bands (eventually hybridized). As discussed however in chapter A, they are bound to be spin-polarized, so that ... 

By varying the excitation energy in direct and inverse photoemission, further important information is collected on hybridized states. Thus, it can be said that by photoelectron methods, the itineracy of open shells (in actinides 5f) is well characterized. 

This emission is considerably enhanced as compared with the spectrum of Th metal (see Fig. 9). The comparison of XPS valence band for U and Th (with a 5 f° configuration) provides a straightforward and direct identification of the 5f emission. Consequently, the strong emission for U at Ep can be attributed to itinerant 5 f states, hybrid-... 

Within the actinide series Pu is the most intriguing element. On the basis of the Hubbard model, and taking into account an unhybridized bandwidth Wf (due only to f-f overlapping), the Un/Wf ratio is 0.7 for U and 3 for Pu in fact, one would have expected already for Pu a 5 f electron localization, since Uh > Wf. However, a hybridization of 5 f with (6d7s) states broadens the 5f bandwidth and delays the Mott-like transition (see Chap. A) from Pu to Am This influences many properties of Pu metaf . ... 

Applying this model, the 4f doublet of Th metal would appear to be a typical 5f-transition metal spectrum (i.e., with a split doublet where the 5 fs play the screening role of the d electrons in a d-transition metal). This is consistent with strong hybridization of 5f and (d, s) states as predicted by theory ... 

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