Halide complexes thorium

Actinide halides and oxyhalides are known to form numerous complexes with oxygen and nitrogen donor ligands and the preparation and properties of such compounds have recently been reviewed (12, 13). Relatively few protactinium halide complexes are known, but this situation reflects the lack of research rather than a tendency not to form complexes. However, there is sufficient information available for certain ligands to permit a comparison with the behavior of other actinide halides, and to illustrate the similarities and differences observed with the tetrahalides of thorium to plutonium inclusive and, to a lesser extent, with the protactinium and uranium pentahalides. 

Ketones, aldehydes, esters. Complexes of ketones, aldehydes, and esters have been made with uranium and thorium halide complexes by isolating the product from a ligand-containing solution. Ethyl- and -propyl acetates also react with uranium tetrachloride to yield mixed halide-acetate salts with ester as an additional coordinating base. 

Isomorphism among compounds of the actinides is common and only a few examples need be given. The dioxides, MO2, of thorium, uranium, neptunium, plutonium and americium all have a fluorite lattice. The trihalides of the transuranic elements are isomorphous not only with the corresponding trihalides of actinium and uranium but also with those of the lanthanides. Isomorphism is also exhibited in many complex halides thus thorium, ura-... 

Hydrolysis of complexes of the type MFe is catalysed not only by acid but also by a series of metal ions. Kinetic data have been obtained for catalysis of hydrolysis of PFe, AsFg", AsFgCOH)- and also of BF4-, by beryllium(ii), aluminium(iii), zirconium(iv), and thorium(rv). Again this may be seen as an extension of studies on cation catalysis of hydrolysis of transition-metal complexes, e.g. the numerous studies of mercury(ii)-catalysed aquations of cobalt(iii)-ammine-halide complexes, or the recent study of metal ion catalysis of chloro(ethylenediaminetriacetato)-cobaltate(m). ... 

Very many complex halides of thorium and uranium have been prepared for crystallographic, magnetic, and spectroscopic studies. Preparative conditions suggested that these compounds are more stable than the parent (binary) halides. For example, UFs is difficult to prepare but complex halides such as CsUF are relatively stable. Among the transuranium elements, fewer high-valent binary... 

Rubidium metal alloys with the other alkali metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double halide salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and zinc. These complexes are generally water insoluble and not hygroscopic. The soluble rubidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide,... 

Thorium forms one series of halides, another one of oxyhalides, and also a series of double or complex halides. In general, stability of these compounds toward heat decreases as die atomic weight of die halogen increases. These compounds are often isostructural with the corresponding compounds of other actinide elements in the (IV) oxidation state. 

The chemistry of Th(IV) has expanded greatly since the mid-1980s (14,28,29). Being a hard metal ion, Th(IV) has the greatest affinity for hard donors such as N, O, and light halides such as F" and CT. Coordination complexes that are common for the /-block elements have been studied for thorium. These complexes exhibit coordination numbers ranging from 4 to 11. 

Allyl Complexes. Allyl complexes of thorium have been known since the 1960s and are usually stabilized by cyclopentadienyl ligands. Allyl complexes can be accessed via the interaction of a thorium halide and an allyl grignard. This synthetic method was utilized to obtain a rare example of a naked allyl complex, Th(r 3-C3H5)4 [144564-74-9], which decomposes at 0°C. This complex, when supported on dehydroxylated y-alumina, is an outstanding heterogeneous catalyst for arene hydrogenation and rivals the most active platinum metal catalysts in activity (17,18). 

Thorium halides form many complexes with neutral donors, discussed in chapter 11. Here it may be noted that there are a number of anionic complexes, including Cs2ThCl6, (pyH)2ThBr6, and (Bu4N)2ThIg, which generally seem to contain isolated [ThXs] ... 

Table 11.2 gives some stability constants for complexes of Th + and U02 +. Thorium forms stronger complexes with fluoride, the hardest halide ion, than with chloride and bromide this is the behaviour expected of a hard Lewis acid. Thorium also forms quite... 

Complexes of the Actinide(iv) Nitrates and Halides 11.6.1 Thorium Nitrate Complexes... 

Tn reviewing the chemistry of the actinides as a group, the simplest approach is to consider each valence state separately. In the tervalent state, and such examples of the divalent state as are known, the actinides show similar chemical behavior to the lanthanides. Experimental diflB-culties with the terpositive actinides up to plutonium are considerable because of the ready oxidation of this state. Some correlation exists with the actinides in studies of the lanthanide tetrafluorides and fluoro complexes. For other compounds of the 4-valent actinides, protactinium shows almost as many similarities as dijSerences between thorium and the uranium-americium set thus investigating the complex forming properties of their halides has attracted attention. In the 5- and 6-valent states, the elements from uranium to americium show a considerable degree of chemical similarity. Protactinium (V) behaves in much the same way as these elements in the 5-valent state except for water, where its hydrolytic behavior is more reminiscent of niobium and tantalum. 

Tetrachloride and tetrabromide complexes are known for thorium, protactinium, uranium, neptunium, and plutonium. These are similarly produced by halide-based oxidation of metals or hydrides, or by halogenation of oxides. A common structural type is reported for most compounds. The reported structure of thorium tetrachloride reveals that the coordination geometry about the metal is dodecahedral.The compounds are generally volatile and can be sublimed. The gas-phase electron diffraction structure of suggests that the molecule is... 

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