Lanthanide hydride halides

RXH. The hydride halides RXH of the divalent rare earth metals have been known for a long time. All of them, EuXH, YbXH with X = Cl, Br, 1, and SmBrH (Beck and Limmer 1982) crystallize in the PbFCl-type structure, which is also adopted by the hydride halides of the alkaline earth metals MXH (Ehrlich et al. 1956), by the mixed halides RXX of divalent lanthanides, and many oxyhalides ROX of the trivalent metals. The colorless compounds RXH of R = Sm, Eu, Yb therefore have to be addressed as normal salts. The hydrogen content of these compounds is strictly stoichiometric. 

The formation and disruption of M-M bonds through chemical reactions can be performed reversibly with the hydride halides of the trivalent lanthanides whose structures are closely related to that of Gd2Q2C2. 

Additional areas of lanthanide halide chemistry that have been reviewed include the synthesis, phase studies, and structures of complex lanthanide halides - compounds formed between one or more group 1 cation and lanthanide element halides (Meyer 1982). Halides in combination with lanthanide elements in the II, III, and IV oxidation states were considered with the chemistry of the heavier halides being emphasized. More recently the reduced ternary lanthanide halides (Meyer 1983) and the reduced halides of the lanthanide elements were reviewed (Meyer 1988). The latter review considered lanthanides in which the formal oxidation state of the cation was 2 and included hydride halides, oxide halides, mixed-valence ternary halides, and reduced halide clusters. Corbett et al. (1987) discussed the structures and some bonding aspects of highly reduced lanthanide halides and compounds stabilized by a second-period element bound within each cluster, e.g., SC7CIJ2B, SC5CI5B, YjCljC. 

Applications of relativistic quantum mechanical techniques to chemical problems have been numerous in the last several years. These techniques have been applied to both diatomics and polyatomics containing very heavy atoms. The author has written several reviews " which have dealt with the applications of these techniques to main group hydrides, halides and chalconides, main group dimers and trimers, and actinide and lanthanide containing molecules. In this section we shall give very selected applications to some very heavy molecules to demonstrate the power of these techniques. The readers are referred to these extensive reviews on the topic for further details. 

Metathetical routes using bulky lithium guanidinates as starting materials have also been employed to synthesize bis(guanidinato) lanthanide halides as well as reactive alkyls and hydrides. Scheme 63 shows as a typical example the formation of the lutetium chloro precursor, which was isolated in 76% yield. ... 

Acetyl ligands, in niobium complexes, C-H BDEs, 1, 298 Achiral phosphines, on polymer-supported peptides, 12, 698 Acid halides, indium compound reactions, 9, 683 Acidity, one-electron oxidized metal hydrides, 1, 294 Acid leaching, in organometallic stability studies, 12, 612 Acid-platinum rf-monoalkynes, interactions, 8, 641 Acrylate, polymerization with aluminum catalysts, 3, 280 Acrylic monomers, lanthanide-catalyzed polymerization,... 

Of great importance as precatalysts in organolanthanide-catalyzed processes are lanthanide hydrocarbyls containing the bulky bis(trimethylsilyl)methyl ligand. They are also the most suitable precursors for the preparation of the dimeric hydrides [(C5Me5)2Ln(/t-H)]2. Such compounds can be isolated completely free of coordinating solvents and alkali metal halides Eq. (2) [19-25. ... 

Lanthanide alkoxide complexes can be prepared using a number of methods. The key difference lies in the nature of lanthanide starting materials. These include elemental metals, halides, alkoxides, amides, carboxylates, hydrides, and organometallic species [1, 11], The organic ligands come from aliphatic alcohols, phenols, or their metal salts. 

The product of reaction of BH4 with element halides depends on the electropositivity of the element. Halides of the electropositive elements tend to form the corresponding M(BH4) c, e.g. M = Be, Mg, Ca, Sr, Ba Zn, Cd Al, Ga, Tl lanthanides Ti, Zr, Hf and Halides of the less electropositive elements tend to give the hydride or a hydrido-complex since the BH4 derivative is either unstable or non-existent thus SiCU gives SiH4 ... 

Comparative studies of other metal halides as dopant precursors for treating NaAlIij have shown that similar levels of kinetic enhancement of the reversible dehydrogenation can be achieved upon doping with chlorides of zirconium, vanadium, and several lanthanides. Lower levels of catalytic activity have been reported to occur in hydride that was charged with FeCl2 and... 

The second review is due to Pepper and Bursten (1991). This review focussed on the electronic structure of actinide-containing molecules. Note that the present chapter complements this in that our chapter is mostly on lanthanide-containing species. Consequently, the reader is referred to the excellent review by Pepper and Bursten (1991) for a comprehensive summary of the electronic structure of actinide-containing species. The review by Pepper and Bursten (1991) contains the details of calculations on actinide hydrides, actinide halides, actinide oxides, cyclopentadienyl-actinide complexes, aetinocenes, metal-metal bonding in actinide systems and miscellaneous other actinide systems. This review also consists of descriptions of theoretical techniques employed to study the actinide-containing molecules. The reader is directed to this review for further details on such calculations on actinide-containing molecules. 

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