Actinide survey

Although useful, even on a simple system, this approach can only trim an RCI basis size by a factor of 2-3 at most. For the lanthanide and actinide survey we are discussing here, we needed an order of magnitude or more for the mid-row anions to make the calculations feasible. 

Literature Survey of Published Actinide Single-Molecule Magnets... 

The review is divided into three sections, (i) the chemistry of scandium and yttrium, (ii) the chemistry of the lanthanide elements, further subdivided into a survey of lanthanide n.m.r. shift reagents and the general chemistry of the elements, and (iii) the chemistry of the actinide elements and uranyl and related compounds. 

Octacoordination is now recognized to be common for many lanthanide and actinide complexes. Among the < -transition metal ions, however octacoordination is less frequent. The d, d, d and d configurations are known to produce eight coordinated complexes (97). In an excellent review Lvppard (92) surveyed the chemistry of the octa coordinated complexes, especially stereochemical and bonding aspects, and included most of the published material upto 1967. 

In Part IV, a rapid survey is given of experimental evidence collected on actinide solids. The application of the concepts i. to iiii. helps in ordering this evidence in a unified description. 

This requires that the result of the simple treatments described be sustained by a critical survey of many other physical properties Unfortunately, and especially for heavier actinides, one is hampered many times by the lack of suitable experimental information. One of the merits, on the other hand, of these approaches is that they have often led to suggestions for particular decisive measurements. 

This treatment aiming to evaluate thermodynamically the orbital character of the bond in actinide metals, follows closely the general features illustrated above and has a particular value inasmuch as it is accompanied by a fairly comprehensive survey of the chemical and physical properties of actinide metals known at that time. In it, the metallic radius and the crystal structures are taken as valence indicators AH nd Tm as the bonding indicators . The metallic valence, however, is not taken as constant throughout the actinide series, but rather allowed to vary. The particular choices are justified by physical and chemical arguments, which are taken in support of the hypothesis chosen. 

After a survey of the basic theory and some experimental aspects of photoelectron spectroscopy which are relevant to actinide solids, two systems are illustrated elemental actinide metals, in which the Mott transition between plutonium and americium is evidenced in a photographic way by photoemission, and strongly ionic oxides, in which the 5f localized behaviour is clearly seen, and indications of f-p or d-p covalent mixing are investigated. 

The preceding discussion of the relationships between excited state electronic structure and photochemical reactivity focused primarily upon coordination compounds containing cP or low-spin cP transition metals. These relationships are generally applicable, however, to complexes of other d transition elements, the lanthanides and the actinides. A brief survey of the photochemical reactions of these latter systems is presented below. 

Fuels - [ALCOHOL FUELS] (Vol 1) - [COALCONVERSIONPROCESSES - LIQUEFACTION] (Vol 6) - [ALCOHOLS,HIGHERALIPHATIC - SURVEY AND NATURALALCOHOLSMANUFACTURE] (Voll) -H202 as oxidant [HYDPOGEN PEROXIDE] (Vol 13) -hydrazine as [HYDRAZINE AND ITS DERIVATIVES] (Vol 13) -hydrothermal oxidation of [SUPERCRITICAL FLUIDS] (Vol 23) -ignition m hot air streams [ACETALDEHYDE] (Voll) -for ironmaking [IRON] (Vol 14) -m pyrotechnics [PYROTECHNICS] (Vol 20) -thorium, uranium, and plutonium as [ACTINIDES AND TRANSACTINIDES] (Vol 1)... 

Olofsson, U. Allard, B. "Complexes of Actinides with Naturally Occurring Organic Substances - Literature Survey, KBS Technical Report 8309, Stockholm, Sweden, 1983. 

The second class consists of molecular compounds containing one or more silicon-transition-metal bonds. The first example, Me3SiFe(CO)2-(tjs-CbHb), was prepared in 1956 (359), but nearly 10 years then elapsed before other compounds were described (26, 94). These heralded many more, and now examples are known in which silicon is bonded to almost every transition metal (Fig. 1). Curiously, no Si-Ag compounds have been described there are also no reports of derivatives of lanthanides or actinides. Most work has involved Fe, Co, Pt, Mn, Re, Mo, Ru, and Ni, in roughly decreasing order of frequency. Almost all well-characterized molecular silicon-transition-metal compounds known at present are diamagnetic some possible exceptions are noted in Section II,F. The most recent comprehensive reviews of the area were published in 1973 (134) and 1974 (235), covering the literature until 1971 and 1972, respectively these contain details of earlier reviews. Other surveys of certain aspects have also appeared, two of them very recently (24, 25, 201). 

One of the most common topics asked of those who work with the actinides relates to handling procedures. The radioactive nature of these elements does require the use of special facilities, processes, and precautions. However, working with radioactive elements in subcritical quantities is as safe, if not safer, than handling many of the toxic chemicals found in a typical synthetic laboratory. The primary advantage in handling radioactive material is the ease with which these elements can be detected. Unlike other toxic chemicals, for example, lead, thallium, arsenic, and so on, a simple survey (seconds) with a radiation detector will show if containment of the material has been lost, where it is, and approximately how much is present. With appropriate monitoring, virtually no uptake of radioactive material occurs, and if any personnel contamination does occur, it is quickly detected and treated. 

Oxidative addition of organic halides to low-valent metal complexes generates reactive metal alkyls that can then be used in insertion, coupling, carbonylation-decar-bonylation and cyclization reactions for organic synthesis. These transformations can be made catalytic after development of the stoichiometric chemistry using the more stable metal alkyls. This section surveys the reactions of alkyl, aryl and acyl halides with transition metal complexes of the groups IIIA (lanthanides and actinides), IVA-VIII and IB. 

Olofsson U. and Allard B. (1983) Complexes of actinides with naturally occurring organic substances. Literature Survey Technical. KBS Report 83-09. 

The purpose of this chapter is to address the role of heavy oxoanions containing a chemically inert, but stereochemically active, lone-pair of electrons on the structures of purely inorganic actinide compounds. This work is not intended to be a comprehensive survey of all compounds that fall into this class, but rather its goal is to highlight key compounds with atypical structures where the influence of the lone-pair of electrons can be ascertained, if only in part. 

The central question that needs answering as this chapter comes to a close is whether or not general statements can be made concerning the role that the inert pair of electrons on heavy oxoanions can play in determining the structures of crystalline actinide compounds As we survey the known materials with anions of this type, it is apparent that there are many roles for these electrons, including the formation of channels and cavities, alignment to create polarity and chirality, and especially dimensional reduction. Dimensional reduction to one-... 

It should however be noted that for the lanthanide and actinide series numerous different definitions of the crystal field parameters have on occasion been adopted and care should therefore be taken in comparing quantities from different literature sources. In this review the crystal field parameters are throughout used in the sense defined above, but see for example Hutchings (36) for a survey of some other conventions. 

The intrinsic properties of the rare earth cations as revealed by their oxophilici-ty, hardness , and large size govern the reactivity of organolanthanide complexes. Hence, parallels to the chemistry of aluminum, the group 2 and group 4 elements, and the actinides are often detected. In this section the most important reaction pathways of these highly reactive complexes are surveyed with representative examples. The stoichiometric reactions outlined also represent the elementary steps in catalytic reaction sequences. 

An early survey of the possible sources for the hypersensitivity concluded that the most likely candidate was a mechanism based on the inhomogeneities of the dielectric surrounding the rare-earth or actinide ion (4). It runs as follows. The radiation field induces sinusoidally fluctuating dipole moments in the ligands surrounding the ion. These induced dipoles necessarily radiate, and the emitted fields impinge on the rare-earth or actinide ion. Because of the proximity of source and receiver, the plane-wave condition no longer applies the wave fronts are sufficiently distorted to produce substantial quadrupole components. 

---