Cyclopentadienyl trivalent chemistry

Lanthanide Complexes with Multidentate Ligands Lanthanide Oxide/Hydroxide Complexes Lanthanides Coordination Chemistry Solvento Complexes of the Lanthanide Ions Trivalent Chemistry Cyclopentadienyl. 

Aryls Alkyl Homogeneous Catalysis The Electronic Stmcture of the Lanthanides Variable Valency Solvento Complexes of the Lanthanide Ions Lanthanides Coordination Chemistry The Divalent State in Solid Rare Earth Metal Halides Lanthanides Comparison to 3d Metals Trivalent Chemistry Cyclopentadienyl Tetravalent Chemistry Organometallic Organic Synthesis. 

The first compounds with lanthanide chalcogen bonds were prepared with ancillary Cp or Cp Ugands (see Trivalent Chemistry Cyclopentadienyl), because at the time it was believed that Cp steric demands were necessary to control chemical reactivity, and because the solubility of products in hydrocarbon solvents limited potential side reactions. Metathesis reactions governed by the insolubility of alkali halides were initially investigated (Reaction 1), but eventually a host of synthetic approaches were successfully employed. Compounds have been prepared by reduction of RE-ER with divalent Ln (Reaction 2), where the driving force of the reaction is increased stability associated... 

Trivalent Chemistry Cyclopentadienyl Rare Earth Metal Cluster Complexes Lanthanide Oxide/Hydroxide Complexes Oxide and Sulfide Nanomaterials Near-Infrared Materials. 

NLO properties, 12, 128 organometallic complexes, 3, 318 as reaction materials, 3, 368 and selenium nucleophiles, 9, 471 surface chemistry on oxides, 12, 502 in triruthenium cyclopentadienyl clusters, 6, 799 trivalent halides, with metal carbonyl monoanions, 3, 347 Group 14 elements... 

Roesky introduced bis(iminophosphorano)methanides to rare earth chemistry with a comprehensive study of trivalent rare earth bis(imino-phosphorano)methanide dichlorides by the synthesis of samarium (51), dysprosium (52), erbium (53), ytterbium (54), lutetium (55), and yttrium (56) derivatives.37 Complexes 51-56 were prepared from the corresponding anhydrous rare earth trichlorides and 7 in THF and 51 and 56 were further derivatised with two equivalents of potassium diphenylamide to produce 57 and 58, respectively.37 Additionally, treatment of 51, 53, and 56 with two equivalents of sodium cyclopentadienyl resulted in the formation of the bis(cyclopentadienly) derivatives 59-61.38 In 51-61 a metal-methanide bond was observed in the solid state, and for 56 this was shown to persist in solution by 13C NMR spectroscopy (8Ch 17.6 ppm, JYc = 3.6 2/py = 89.1 Hz). However, for 61 the NMR data suggested the yttrium-carbon bond was lost in solution. DFT calculations supported the presence of an yttrium-methanide contact in 56 with a calculated shared electron number (SEN) of 0.40 for the yttrium-carbon bond in a monomeric gas phase model of 56 for comparison, the yttrium-nitrogen bond SEN was calculated to be 0.41. 

In this chapter we will review the synthesis, structural aspects, and basic chemical properties of formally divalent and trivalent titanium and zirconium metallocene complexes. We have restricted our coverage to the low-valent bis(rj-cyclopentadienyl) and related metallocenes metal halide complexes and organometallic mixed metal systems will not be discussed here. We have not attempted to present an exhaustive coverage of the field. Rather, our aim has been to describe critically and to evaluate the often confusing chemistry that has been reported for the reactive low-valent titanium and zirconium metallocenes. More general reviews (7) and a book (2) on the organometallic chemistry of titanium, zirconium, and hafnium have been published. 

This chemistry is dominated by the trivalent cyclopentadienyl and alkyl derivatives with various structures that are prepared from the trichloride LnCls. These compounds are very air- and moisture sensitive because of their ionic character. They are mild Lewis acids that coordinate the solvent used for their synthesis (most often THF). In the case of scandium (III), the Lewis acidity is much stronger (even larger than that of AlMes), because of the small ion size. 

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