Lanthanide organometallics hydrides

Other Andllaries. - A review of lanthanide hydrides with a focus on the hydride function, uncoordinated and metallic hydrides and their use as catalysts in diene polymerization has appeared. Steric and electronic effects on the stability of early lanthanide, neodymium and samarium, organometallic hydrides are discussed. ... 

Hunt s group (50, 51) have pioneered the application of the Cl source to organometallics such as the iron tricarbonyl complex of heptafulvene, whose electron impact spectrum shows (M—CO)+ as the heaviest ion, in contrast to the methane Cl spectrum with the ion as base peak. Boron hydrides (52) and borazine (53) have also been studied. The methane Cl spectrum of arenechromium and -molybdenum (54) show protonation at the metal giving a protonated parent or molecular ion. Risby et al. have studied the isobutane Cl mass spectra of lanthanide 2,2,6,6-tetramethylheptane-3,5-dionates[Ln(thd)3] (55) and 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-oetanedione [H(fod)] lanthanide complexes (56). These latter complexes have been suggested as a means of analysis for the lanthanide elements. 

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,... 

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. 

Voskoboynikov, A.Z., Parshina, I.N., Shestakova, A.K. et al. (1997) Reactivity of lanthanide and yttrium hydrides and hydrocarbyls toward organosilicon hydrides and related compounds. Organometallics, 16, 4041. 

Any modification of a complex, in order to increase or decrease its reactivity towards a substrate for catalytic purposes, can be easily accomplished by modulating the steric effects, even though modification of the electronic properties of the reactive site may also be necessary to render the catalyst more efficient. The evaluation of such electronic influence requires a comparison of complexes bearing ligands of the same size (isosteric ligands) but different in their chemical nature. The organometallic chemistry of the hard lanthanide elements is dominated by the soft cyclopentadienyl type ligands, while the number of non cyclopentadienyl hydrides is really modest. Due to the paucity of the published syntheses of... 

The polymerisation of dienes occurs when the lanthanide catalyst contains an organometallic component (usually, trialkylaluminum or dialkylaluminum hydride). Systems LnHal3 nL-AlR2lTal do not reveal catalytic activity. Moreover, dialkylaluminum... 

Professor Norbert W. Mitzel is professor of inorganic and structural chemistry at the University of Bielefeld. After preparative work on phosphorus ylides and then volatile silicon hydrides and Si-N compounds for CVD purposes, he studied weak intramolecular Si- -N interactions, poly-Lewis acids of B, Al, Ga and In, and later also organometallic lithium and lanthanide chemistry. He was particularly involved in multinuclear NMR spectroscopy. X-ray crystallography, including in-situ crystal growth of low-melting substances, and gas electron diffraction. 

Studies on OCH(CF3)2, OCMe(CF3)2, OCMc2(CF3), and 0C(CF3)3 derivatives of the alkali metds, alkaline earth metals, transition metals, and the lanthanide elements are reviewed, with emphasis on work reported since 1988. Alkali and alkaline earth fluoroalkoxides are generally made from reaction between the alcohol and the metal, its hydride, or organometallics. Most syntheses of transition metal derivatives involve reaction between metal halides and alkali or alkaline earth salts, or the alcoholysis of metal alkyls, alkoxides and amides. Coordination between organic fluorine and electropositive metals (ie. Na, Ba, Tl, Pr) is often observed in the crystal structures of these fluoroalkoxides and may be related to their use as chemical vapor dqx)sition precursors for metal fluorides. 

This review covers all organometallic complexes of Sc, Y and the lanthanides reported in the year 2000 and their reactions. Endohedral fullerene complexes of the lanthanides have, as usual, been excluded. Highlights this year include striking reports of lanthanides in non-classical oxidation states (Sections 3.2 and 5), a remarkable reversible dinitrogen activation described in Section 3.9.2 and evidence for the existence of the divalent hydrides LnH2(THF)2 (Ln = Sm, Yb) (Section 3.10). In addition Evans has assessed the utility of electrospray mass spectrometry for the characterization of organolathanides. The results are promising and the spectra and dissociation patterns show sensitivity to the metal and its oxidation state. ... 

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