Organoantimony chemistry

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Organoantimony chemistry is the chemistry of compounds containing a carbon to antimony (Sb) chemical bond. Relevant oxidation states are Sb(V) and Sb(III). The toxicity of antimony[1] limits practical application in organic chemistry.[2]

Organoantimony(V) chemistry[edit]

Antimony compounds of the type R5Sb (stiboranes) can be synthesised from trivalent Sb precursors:

Ph3Sb + Cl2 → Ph3SbCl2
Ph3SbCl2 + 2 PhLi → Ph5Sb

Asymmetric compounds can also be obtained through the stibonium ion:

R5Sb + X2 → [R4Sb]+[X]
[R4Sb]+[X] + R'MgX → R4R'Sb

Just as in the related organobismuth compounds (same group 15), organoantimony(V) compounds form onium compounds and ate complexes.

Pentaphenylantimony decomposes at 200 °C to triphenylstibine and biphenyl. It forms a trigonal bipyramidal molecular geometry. In the related Me5Sb all methyl protons are equivalent at -100 °C in proton NMR. Compounds of the type R4SbX tend to form dimers.

Organoantimony(III) chemistry[edit]

Compounds of the type R3Sb (stibines) can be accessed by reaction of antimony trichloride with organolithium compounds or Grignards.

SbCl3 + 3 RLi (or RMgCl) → R3Sb

Typical reactions are:

R3Sb + Br2 → R3SbBr2
R3Sb + O2 → R3SbO
R3Sb + Na + NH3 → R2SbNa
R3Sb + B2H6 → R3Sb·BH3

Stibanes are weak Lewis acids and therefore ate complexes are not encountered. On the other hand they have good donor properties and are therefore widely used in coordination chemistry. R3Sb compounds are more air-sensitive than the R5Sb counterparts.

Antimony Metallocenes are known as well:

14SbI3 + 3 (Cp*Al)4 → [2Cp*Sb]+[AlI4]- + 8Sb + 6 AlI3

The Cp*-Sb-Cp* angle is 154°.

The cyclic compound stibole, a structural analog of pyrrole, has not been isolated, but substituted derivatives known as stiboles are known.

Organoantimony(II) chemistry[edit]

Distibines have a Sb-Sb single bond and are of some interest as thermochromic materials. For example tetramethyldistibine is a colorless as a gas, yellow as a liquid, red as solid just below the melting point of 18.5 °C and again yellow well below the melting point.[3]

See also[edit]

  • Chemical bonds of carbon with other elements in the periodic table:
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 Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo
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[edit]

  1. ^ Filella, M. "Alkyl derivatives of antimony in the environment". Metal ions in life sciences (Cambridge: RSC publishing) 7: 267–301. doi:10.1039/9781849730822-00267. ISBN 978-1-84755-177-1. 
  2. ^ C. Elschenbroich, A. Salzer Organometallics : A Concise Introduction (2nd Ed) (1992) from Wiley-VCH: Weinheim. ISBN 3-527-28165-7
  3. ^ Organoantimony compounds with element-element bonds H.J. Breunig, R. Rosler Coordination Chemistry Reviews 163 (1997) 33-53