Tetravalent chemistry organometallics

Coordination Complexes. The coordination and organometallic chemistry of thorium is dominated by the extremely stable tetravalent ion. Except in a few cases where large and sterically demanding ligands are used, lower thorium oxidation states are generally unstable. An example is the isolation of a molecular Th(III) complex [107040-62-0], Th[t -C5H3(Si(CH3)3)2]3 (25). Reports (26) on the synthesis of soluble Th(II) complexes, such as... 

A number of reviews dealing with organoplumbanes have been published,however, and the purpose of this contribution is to overview the advances in organometallic chemistry of lead in the last decade for both divalent lead, R2Pb, and tetravalent lead, R4 PbX . 

The diagram shows, in a simple and elementary way the reference position of La, Gd and Lu and accounts for a gradual variation inside each subgroup, i.e., from Ce to Eu and, although less clearly, from Tb to Yb. Ce and Tb, which follow respectively. La and Gd, can easily become tetravalent, whereas Eu and Yb, preceding Gd and Lu, can become bivalent. Such a behaviour is important and sometimes useful in explaining the organometallic and catalytic chemistry of 4f elements. ... 

Homogeneous Catalysis Lanthanide Halides Organometallic Chemistry Fundamental Properties Tetravalent Chemisiry Inoiganic Tetravalent Chemistry Organometallic The Divalent State in Solid Rare Earth Metal Halides The Electronic Structure of the Lanthanides. 

Even flien well-characterized coordination compoimds are limited to only a few classes of compounds. Notable are, e.g., halogeno complexes and complexes of oxo acids, p-diketonates and related SchifF-base complexes, as well as porphyrinates and related complexes. Two other important classes of cerium(lV) compounds, the alkoxides and amides of Ce" +, can be regarded as pjewfifo-organometallics and are discnssed together with the organocerium(IV) complexes in Tetravalent Chemistry OrganometalUc. 

Sulfur may be divalent, tetravalent, and even hexavalent (e.g., in alkyl- or arylsulfur pentafluorides). As a consequence, the organometallic chemistry of sulfur compounds exhibits a variety of facets. The next subsection deals with substitution reactions, whereas the other subsections summarize addition and addition/elimination processes. 

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