Rare-Earth Metal Compounds

A semi-quantitative description of the core level spectrum and the charge-transfer process can be obtained from a simple two-level MOLCAO-model based on the sudden approximation 155 157,160). Here, we follow the formulation of Larsson157) and consider the influence of a core hole on a single electron in an MO formed by linear combination of AO s Ul and uM centred on the ligands (L) and the central metal ion (M). In the ground state, before ionization, the electron is in a bonding orbital 

Quasi-Particle Properties of Hole Levels in Solids and Adsorbate Systems 

In this model the intensity ratio depends on the angle of rotation - rj due to the perturbing core hole and not on the absolute angles (mixing coefficients) and rj. 

As an example, let us apply this model to 3 d-ionization of La-halides (M = 4f, L 2p(F), 3p(Cl), 4p(Br)). A reasonable approximation consists in taking the metal and ligand atomic orbitals to be localized and the 4f-metal orbital to be empty in the ground state. This is achieved by choosing 17 = 0, and means that instantly after ionization the screening charge is localized on the ligands, 

In terms of the true core level spectrum, the intensity ratio now becomes 

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The main oxidation state for promethium is +3. At least 30 compounds of promethium have been identified, but none are commercially available. Three examples of typical rare-earth metal compounds are as follows ... 

Cathodic inhibition by rare earth metal compounds... 

Rare earth metal compounds Inhibiting pigments in paints. Silica, alumina, iron oxide or tin oxide with adsorbed rare earth metal cation in alkyd resin-based paints [15]... 

Rare earths. 2. Rare earth metal compounds. 3. Coordination compounds. I. Huang, Chunhui, 1933-QD172.R2R235 2010... 

This book contains four chapters in which part of the recent development of the use of molecular rare-earth metal compounds in catalysis is covered. To keep the book within the given page limit, not all aspects could be reviewed in detail. For example, the use of molecular rare-earth metal complexes as Lewis acidic catalysts is not discussed in this book. The first two chapters review different catalytic conversions, namely the catalytic o-bond metathesis (Chapter by Reznichenko and Hultzsch) and the polymerization of 1,3-conjugated dienes (Chapter by Zhang et al.). Within these chapters, different catalytic systems and applications are discussed. The final two chapters are more concentrated on recent developments of... 

In summary, the present volume of Structure and Bonding shows the substantial activity carried out in recent years in the held of synthesis of inorganic and organometallic rare-earth metal compounds and their use as catalysts for a number of different transformations. The future holds great promise for the rapid growth of this held of chemistry and for new spectacular results. 

Atoji, M., 1969, J. Chem. Phys. 51, 3J77. Ausloss, H., J.B. Sousa, M.M. Amado, R.F. Pinto, J.M. Moreira, M.E. Bragal and M.F. Pinheiro, 1980, On Various Anomalies in the Temperature Derivative of Transport Properties in Rare Earth Metallic Compounds, in (Gregory, J., J. McCarthy, J. James. J. Rhyne and H. Silber, eds.. The Rare Earths in Modern Science and Technology (Plenum, New York) p. 273. 

The RNigC2 (R = the heavy rare earth metals) compounds are orthorhombic and their lattice parameters have been determined for R = Gd-Lu (Putyatin and Sevastyanova 1987). 

Crystallographic data for rare earth metal compounds with discrete clusters. 

In contrast to all other rare earth metal compounds discussed so far, the hydride halides contain mobile interstitial atoms that can be added or (partly) removed at will in a topochemical reaction. These compounds therefore offer a unique possibility to study the delocalization of electrons in extended metal-metal bonds versus the localization at interstitial atoms. The known compounds are summarized in table 7. 

Yttrium is found together with other rare earth oxides inmonazite sands (Ce, La, etc.) PO4] and in bastnasite [(Ce, La, etc.)(C03)F] (see Section 1.7.1). Yttrium is extracted together with other rare earth elements in a concentrated solution of sodium hydroxide at 140-150 °C after cooling, the hydroxides of the rare earth elements are separated by filtration. Alternatively, bastnasite may be calcined to drive off CO2 and fluorine, and then leached with hydrochloric acid to dissolve the trivalent rare earth elements. The rare earth hydroxides and chlorides obtained in this way are further processed to produce individual rare earth metal compounds... 

Nasibov, I.O., P.G. Rustamov, Z.Sh. Karaev, T.U. Sultanov and M.I. Mourgusov, 1975b, in Preparations and studies of properties of rare earth metals compounds. Edit. Akad. 

Kustov, E.F., Bandurskii, G.A., Murav ev, E.N., Orlovskii, V.P., 1981. Electronic Spectra of Rare-Earth Metal Compounds. Nauka, Moscow (in Russian). 

Polybutadiene obtained by rare earth metal compounds has very high cis-1,4 content, and the polymerization is quasi-living. Therefore, we investigated in detail the modification of polybutadiene by neodymium catalyst with tin compound. 

The chemistry of rare earth metals, compounds, and corrosion inhibitors... 

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