Lanthanide compounds crystal chemistry

Notes on the crystal chemistry of selected alloys and compounds of the 15th group elements. Among the pnictides, several series of numerous isostructural compounds are found. The 1 1 compounds with Sc, Y, lanthanides and actinides, having the NaCl-type structure, generally correspond to very stable phases, strongly... 

The electronic spectra of lanthanide compounds resemble those of the free ions, in contrast to the norm in transition metal chemistry the crystal-field splittings can be treated as a perturbation on the unsplit levels. Complexes thus have much the same colour as the... 

In Chapters I and 2, an introduction is made to the synchrotron Mossbauer spectroscopy with examples. Examples include the/ns/tu Mossbauer spectroscopy with synchrotron radiation on thin films and the study of deep-earth minerals. Investigations of in-beam Mossbauer spectroscopy using a Mn beam at the RIKEN RIBF is presented in Chapter 3. This chapter demonstrates innovative experimental setup for online Mossbauer spectroscopy using the thermal neutron capture reaction, Fe (n, y) Fe. The Mossbauer spectroscopy of radionuclides is described in Chapters 4-7. Chapter 4 gives full description of the latest analysis results of lanthanides Eu and Gd) Mossbauer structure and powder X-ray diffraction (XRD) lattice parameter (oq) data of defect fluorite (DF) oxides with the new defect crystal chemistry (DCC) Oq model. Chapter 5 reviews the Np Mossbauer and magnetic study of neptunyl(+l) complexes, while Chapter 6 describes the Mossbauer spectroscopy of organic complexes of europium and dysprosium. Mossbauer spectroscopy is presented in Chapter 7. There are three chapters on spin-state switching/spin-crossover phenomena (Chapter 8-10). Examples in these chapters are mainly on iron compounds, such as iron(lll) porphyrins. The use of Mossbauer spectroscopy of physical properties of Sn(ll) is discussed in Chapter I I. 

Abstract Amino acids are the basic building blocks in the chemistry of life. This chapter describes the controllable assembly, structures and properties of lathanide(III)-transition metal-amino acid clusters developed recently by our group. The effects on the assembly of several factors of influence, such as presence of a secondary ligand, lanthanides, crystallization conditions, the ratio of metal ions to amino acids, and transition metal ions have been expounded. The dynamic balance of metalloligands and the substitution of weak coordination bonds account for the occurrence of diverse structures in this series of compounds. 

The study of coordination compounds of the lanthanides dates in any practical sense from around 1950, the period when ion-exchange methods were successfully applied to the problem of the separation of the individual lanthanides,131-133 a problem which had existed since 1794 when J. Gadolin prepared mixed rare earths from gadolinite, a lanthanide iron beryllium silicate. Until 1950, separation of the pure lanthanides had depended on tedious and inefficient multiple crystallizations or precipitations, which effectively prevented research on the chemical properties of the individual elements through lack of availability. However, well before 1950, many principal features of lanthanide chemistry were clearly recognized, such as the predominant trivalent state with some examples of divalency and tetravalency, ready formation of hydrated ions and their oxy salts, formation of complex halides,134 and the line-like nature of lanthanide spectra.135... 

This essay on the lanthanides has repeatedly drawn attention to a problem of immense importance in both chemistry and biochemistry. The role of water in controlling the stability, the structure, and the lability of coordination compounds. In fact the emphasis extends from coordination compounds to the surfaces of solids47. The role of water is then bound to be extremely important not only in complex chemistry and catalysis but in the growth and properties of crystals and amorphous materials. We can illustrate the problems outside Ln(III) chemistry48,49. ... 

Figure 4.34 (a) Perspective view and (b) side view of compound [Yb(III)(TMPP)(H20)3]Cl [51]. (Reproduced from W. Wong et al, Synthesis and crystal structures of cationic lanthanide (fi) mono-porphyrinate complexes, Journal of the Chemical Society, Dalton Transactions, 615, 1999 (doi 10.1039/a809696a), by permission of The Royal Society of Chemistry.)... 

Zinc tetraphenylporphyrinate forms a weak complex with Of in non-aqueous solutions. The bonding in this complex appears to be essentially ionic . We have already mentioned crystal structure determinations of lanthanide and actinide compounds. There is every reason to suppose that these elements have a rich dioxygen complex chemistry and this is confirmed by two recent papers For reasons of space, however, we shall not discuss the dioxygen complex chemistry of these elements. 

The ionic radii of the lower-valence states (An, An ) of the early actinides are similar to those of the trivalent states of the lanthanides [15]. As might be expected on the basis of the similarities in size and charge, the early actinides in their lower valence states play similar roles to the trivalent lanthanides and Zr in the stmctures of phosphates and arsenates. The chemistry of both trivalent- and tetravalent-actinide phosphates has recently been re-examined in detail [16-18]. This chapter takes a stmctural approach to the same material, and of necessity restricts its coverage to those compounds whose crystal stmctures have either been determined or whose stmctural affiliation may reasonably be inferred. It... 

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