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]
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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:
Bi(V) easily forms an onium ion for example:
or an ate complex for example:
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.
Compounds of the type R3Bi can be accessed by reaction of bismuth chloride with organolithium compounds or Grignards:
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).[7]
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 are known.[8]
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 does not bond directly to a carbon atom.
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 | Ra | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Uut | Uuq | Uup | Uuh | Uus | Uuo | |
↓ | |||||||||||||||||
CLa | CCe | CPr | CNd | CPm | CSm | CEu | CGd | CTb | CDy | CHo | CEr | CTm | CYb | CLu | |||
Ac | Th | Pa | CU | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |
Core organic chemistry | Many uses in chemistry |
Academic research, but no widespread use | Bond unknown / not assessed |