Organobismuth chemistry

Organobismuth chemistry is the chemistry of organometallic compounds containing a carbon to bismuth chemical bond. According to one reviewer, applications are rare even though bismuth and bismuth compounds are the least toxic among the heavy metals and are relatively cheap.[1] The main bismuth oxidation states are Bi(III) and Bi(V) as in all higher group 15 elements. The energy of a bond to carbon in this group decreases in the order P > As > Sb > Bi.[2] The first reported use of bismuth in organic chemistry was in oxidation of alcohols by Challenger in 1934 (using Ph3Bi(OH)2).[3] Knowledge about methylated species of bismuth in environmental and biological media is very limited.[4] Organobismuth heterocycles are bismole and bismabenzene.

Organobismuth(V) chemistry

Bi(V) compounds are strongly oxidizing due to the inert pair effect and relativistic effects. Oxidizing agents are Ph3Bi(OOtBu)2, Ph3BiCO3 and (Ph3BiCl)2O. Substrates for oxidation are oximes, thiols, phenols and phosphines.[5] Compounds such as Ph5Bi and Ph3BiCl2 have been used in the arylation of arene compounds and 1,3-dicarbonyl compounds:[6]

Bi(V) compounds can be accessed through Bi(III) compounds for example:

Me3Bi + SOCl2 → Me3BiCl2
Me3BiCl2 + 2 MeLi → Me5Bi

Bi(V) easily forms an onium ion for example:

Ph5Bi + BPh3 → Ph4Bi+[BPh4]−

or an ate complex for example:

Ph5Bi + PhLi → Li+[Ph6Bi−]

The thermal stability of R5M compounds decrease in the order As > Sb > Bi and aryl compounds are more stable than alkyl compounds. Me5Bi decomposes explosively at 20 °C.

Structure and properties

Pentaphenylbismuth, Ph5Bi is square pyramidal like pentaphenylantimony, whereas pentamethybismuth is, as expected from VSEPR theory, trigonal bipyramidal.[7] Both compounds have a violet colour.[8]

Organobismuth(III) chemistry

Compounds of the type R3Bi can be accessed by reaction of bismuth chloride with organolithium compounds or Grignards:

BiCl3 + 3 RLi (or RMgCl) → R3Bi + 3 MgCl2 (or LiCl)

Triphenylbismuth, unlike the related phosphorus, arsenic, and antimony compounds, undergoes mild redistribution with its trihalide to give the mixed derivatives such as diphenylbismuth chloride (Ph2BiCl).[9]

Bismuth(III) iodide is a catalyst in the Mukaiyama aldol reaction. Bi(III) is also used in a Barbier type allylation of carbonyl compounds in combination with a reducing agent such as zinc or magnesium, possibly forming the active Bi(0) catalyst in situ.

The cyclic compound bismole, a structural analog of pyrrole, has not been isolated, but substituted bismoles are known.[10]

Salicylates

Bismuth subsalicylate, commonly known as Pepto-Bismol or pink bismuth is used to treat a variety of ailments. However, while it involves an organic functional group (see salicylic acid), the bismuth is not bonded directly to any carbon atoms.

See also

CH He
CLi CBe CB CC CN CO CF Ne
CNa CMg CAl CSi CP CS CCl CAr
CK CCa CSc CTi CV CCr CMn CFe CCo CNi CCu CZn CGa CGe CAs CSe CBr CKr
CRb CSr CY CZr CNb CMo CTc CRu CRh CPd CAg CCd CIn CSn CSb CTe CI CXe
CCs CBa CHf CTa CW CRe COs CIr CPt CAu CHg CTl CPb CBi CPo CAt Rn
Fr CRa Rf Db CSg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
↓
CLa CCe CPr CNd CPm CSm CEu CGd CTb CDy CHo CEr CTm CYb CLu
Ac CTh CPa CU CNp CPu CAm CCm CBk CCf CEs Fm Md No Lr
Chemical bonds to carbon
Core organic chemistry Many uses in chemistry
Academic research, but no widespread use Bond unknown

References

  1. ↑ "Bismuth-Mediated Organic Reactions", Ollevier, T. Ed., Topics in Current Chemistry, 2012, Springer Verlag, Berlin, vol. 311, 277 p. http://www.springer.com/chemistry/organic+chemistry/book/978-3-642-27238-7, Bismuth Reagents and Catalysts in Organic Synthesis Axel Jacobi von Wangelin in Transition Metals for Organic Synthesis Building Blocks and Fine Chemicals Beller, Matthias / Bolm, Carsten (eds.)
  2. ↑ C. Elschenbroich, A. Salzer Organometallics : A Concise Introduction (2nd Ed) (1992) from Wiley-VCH: Weinheim. ISBN 3-527-28165-7
  3. ↑ Organo-derivatives of bismuth and thallium Frederick Challenger and Oswald V. Richards, J. Chem. Soc., 1934, 405 doi:10.1039/JR9340000405
  4. ↑ Filella, M. "Alkyl derivatives of bismuth in the environmental and biological media". Metal ions in life sciences. Cambridge: RSC publishing. 7: 303–317. doi:10.1039/9781849730822-00303. ISBN 978-1-84755-177-1.
  5. ↑ Organobismuth Chemistry Hitomi Suzuki, Yoshihiro Matano Elsevier, 2001
  6. ↑ Bismuth(V) reagents in organic synthesis Derek H.R. Barton and Jean-Pierre Finet Pure & Appl. Chem., Vol. 59, No. 8, pp. 937—946, 1987.
  7. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 599. ISBN 0-08-037941-9.
  8. ↑ Arnold F. Holleman, Nils Wiberg: Lehrbuch der Anorganischen Chemie, 102nd Edition, de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1, p. 857.
  9. ↑ Derek H.R. Barton, Neerja Yadav Bhatnagar, Jean-Pierre Finet, William B. Motherwell "Pentavalent organobismuth reagents. Part vi. Comparative migratory aptitudes of aryl groups in the arylation of phenols and enols by pentavalent bismuth reagents" Tetrahedron 1986, Volume 42, , Pages 3111-3122 doi:10.1016/S0040-4020(01)87378-6
  10. ↑ Caster, Kenneth C. "Arsoles, stiboles, and bismoles" Clive W. Bird, ed. Comprehensive Heterocyclic Chemistry II (1996), 2, 857-902.
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