Pincer ligand

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A pincer ligand is a tridentate ligand system , which is usually bound to a transition metal .

history

The first pincer complexes were published by BL Shaw and CJ Moulton in the 1970s. Since then, many different ligand systems have been synthesized and published.

properties

Pincer ligands are structured in such a way that they can bond to the (transition) metal with two donor atoms (for example phosphorus , nitrogen or sulfur ) and a σ bond . Phosphines are often used as donors because they can be easily changed. For example, the sterics can be changed very easily. If the pincer ligand is bound to the metal via two phosphorus donors and a carbon-metal σ bond, it is called a PCP pincer ligand. Bonding by means of a nitrogen-metal σ bond is also possible (PNP). Furthermore, NCN (nitrogen-carbon-nitrogen) and SCS (sulfur-carbon-sulfur) ligand systems are common. Phenyl systems usually serve as the ligand backbone. However, aliphatic systems are also known. If the ligands are bound to a metal, coplanar systems result, which are very rigid. This leads to an increased thermal stability of the system.

  • Iridium PCP Pincer Complex

  • Ruthenium PNN Pincer Complex

  • Aliphatic palladium PCP pincer complex

Applications

Pincer ligands can be used in many catalytic processes: activation of carbon dioxide (CO 2 ), nitrogen (N 2 ), polymerization of alkenes and alkynes , alkane dehydrogenation and transfer hydrogenation .

Individual evidence

  1. ^ CJ Moulton, BL Shaw: J. Chem. Soc., Dalton Trans. 1976, p. 1020.
  2. ↑ R. Gerber, O. Blacque, CM Frech: ChemCatChem. 1, 2009, p. 393.
  3. ^ CJ Moulton, BL Shaw: J. Chem. Soc., Dalton Trans. 1976, p. 1020.
  4. ↑ R. Gerber, O. Blacque, CM Frech: ChemCatChem. 1, 2009, p. 393.
  5. ^ DW Lee, CM Jensen, D. Morales-Morales: Organometallics . 22, 2003, pp. 4744-4749.
  6. ↑ A. Vigalok, Y. Ben-David, D. Milstein: Organometallics . 15, 1996, pp. 1839-1844.
  7. ^ DS McGuiness, VC Gibson, JW Steed: Organometallics . 23, 2004, pp. 6288-6292.
  8. ^ DS McGuiness, VC Gibson, DDF Wass, JW Steed: J. Am. Chem. Soc. 125, 2003, pp. 12716-12717.
  9. ↑ J. Yao, WT Wong, G. Jia: J. Organomet. Chem. 598, 2000, pp. 228-234.
  10. ^ F. Liu, EB Pak, B. Singh, CM Jensen, AS Goldman. J. Am. Chem. Soc. 121, 1999, pp. 4086-4087.
  11. ↑ C. Jensen. Chem. Commun. 1999, pp. 2443-2449.
  12. ^ P. Dani, T. Karlen, RA Gossage, S. Gladiali, G. van Koten: Angew. Chem., Int. Ed. 39, 2000, pp. 743-745.