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Lanthanides: Alkyl Compounds

  1. Simon A. Cotton

Published Online: 17 DEC 2012

DOI: 10.1002/9781119951438.eibc2030

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Cotton, S. A. 2012. Lanthanides: Alkyl Compounds. Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. University of Birmingham, Birmingham, UK

Publication History

  1. Published Online: 17 DEC 2012

Abstract

Lanthanide alkyls are still an area where major discoveries remain to be made. These metals do not form simple molecular methyls; only two such compounds, LnMe3 (Ln = Lu, Y), are known. These are believed to be oligomers and have to be made by an indirect route. Benzyls exist as octahedral solvates fac-[Ln(CH2Ph)3(THF)3] (Ln = Sc, Y, La–Sm, Gd, Dy, Er, and Lu); their structure depends upon the size of the lanthanide concerned, as the compounds of the smaller metals (Sc, Y, Gd, Dy, Er, Lu) all feature three σ-(h1)-benzyl groups, and those of the largest metals all have three h2-benzyls, with [Sm(CH2Ph)3(THF)3] having one h2-benzyl and two h1-benzyl groups. Five-coordinate [Ln(CH2Ph)3(THF)2] (Ln = Sc, Lu) also exist. Trialkyls with the (trimethylsilyl)methyl group only exist for the smaller lanthanides, with five-coordinate [Ln(CH2SiMe3)3(THF)2] (Ln = Sc, Tb, Er-Lu) and six-coordinate [Sm(CH2SiMe3)3(THF)3] known; yttrium forms both types. Using the very bulky bis(trimethylsilyl)methyl group leads to unsolvated three-coordinate [Ln{CH(SiMe3)2}3] (Ln = Y, La, Ce, Sm, Lu); their trigonal pyramidal coordination geometries feature short Ln⋯CH3 contacts. Lanthanide alkyls are intensely air- and moisture-sensitive compounds which are employed as starting materials in various syntheses, including catalytic precursors.

Keywords:

  • scandium;
  • yttrium;
  • lanthanide;
  • alkyl;
  • hydrocarbyl;
  • methyl;
  • benzyl;
  • trimethylsilylmethyl;
  • neopentyl;
  • bis(trimethylsilylmethyl)