Diphosphines are a class of compounds used as ligands in inorganic and organometallic chemistry. In Chemistry, a ligand is either an Atom, Ion, or Molecule (see also Functional group) that bonds to a central metal generally Inorganic chemistry is the branch of Chemistry concerned with the properties and behavior of Inorganic compounds This field covers all Chemical compounds Organometallic chemistry is the study of Chemical compounds containing bonds between Carbon and a Metal. They are identified by the presence of two phosphine ligands joined by a backbone, and are usually chelating. Phosphine is the common name for phosphorus hydride (PH3 also known by the IUPAC name phosphane and occasionally phosphamine. Chelation is the binding or complexation of a bi- or multidentate Ligand.
The most widely used diphosphine ligands are the bis(diphenylphosphino)alkanes, Ph2P(CH2)nPPh2. These can be prepared from X(CH2)nX (X=halogen) and YPPh2 (Y=alkali metal) in THF [1]. Bidentate phosphines with only one bridging group such as dppm tend to promote metal-metal interaction or bond formation because the two donor P atoms are so close together. The use of chelate phosphines with many bridging groups giving long flexible chains has quite a different effect. For example, the chelate phosphine Bu2tP(CH2)10PBu2t can give complexes that have as many as 72 atoms in a ring [2].
Common ligands
Many diphosphine ligands are possible, but some are particularly commonly used and are commercially available. Representative or important diphosphines include:
- 1,1-Bis(diphenylphosphino)methane ("dppm")
- 1,2-Bis(diphenylphosphino)ethane ("dppe")
- 1,3-Bis(diphenylphosphino)propane ("dppp")
- 1,1'-Bis(diphenylphosphino)ferrocene ("dppf")
- 2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl ("BINAP")
- 4,5-Bis(diphenylphosphino)-9,9-dimethylxanthene ("Xantphos")
References
- ^ Wilkinson, G. BINAP is an Acronym for the Organophosphorus compound 22'-bis(diphenylphosphino-11'-binaphthyl Xantphos is an Organophosphorus compound derived from the Heterocycle Xanthene. ; Gillard, R. ; McCleverty, J. Comprehensive Coordination Chemistry: The synthesis, reactions, properties & applications of coordination compounds, vol. 2. ; Pergamon Press: Oxford, UK, 1987; p. 993. ISBN 0-08-035945-0
- ^ Cotton, F. A. ; Wilkinson, G. Advanced Inorganic Chemistry: A Comprehensive Text, 4th ed. ; Wiley-Interscience Publications: New York, NY, 1980; p. 246. ISBN 0-471-02775-8
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