An organocadmium compound is an organometallic compound containing a carbon to cadmium chemical bond. Organocadmium chemistry describes physical properties, synthesis, reactions and use of these compounds. Cadmium shares group 12 with zinc and

mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

and their corresponding chemistries have much in common. The synthetic utility of organocadmium compounds is limited. The simplest organocadmium compound is dimethylcadmium. It is a linear molecule with a C-Cd bond length of 213 pm. Organocadmium compounds are typically sensitive to air, light, and moisture.

Synthesis

Dimethylcadmium and diethylcadmium were reported in 1917 by Erich Krause. In general, they are prepared by

transmetalation Transmetalation (alt. spelling: transmetallation) is a type of organometallic reaction that involves the transfer of ligands from one metal to another. It has the general form: :M1–R + M2–R′ → M1–R′ + M2–R where R and R′ can be, but ...

or by an exchange reaction between an alkylating agent and a cadmium salt. According to one procedure, diethylcadmium is produced the reaction of

cadmium bromide Cadmium bromide is the inorganic compound with the formula CdBr2. It is a white hygroscopic solid. It also can be obtained as a mono- and tetrahydrate. It has few applications. Preparation Cadmium bromide is prepared by heating cadmium with bro ...

with two equivalents of the

Grignard reagent A Grignard reagent or Grignard compound is a chemical compound with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide ...

ethylmagnesium bromide in diethyl ether. Diethylcadmium is a colorless oil with melting point −21

°C The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The ...

. Diphenylcadmium can be prepared by the reaction of phenyllithium with cadmium bromide. Diphenylcadmium is a solid with a melting point of 174 °C.

Fluoroalkyl and alkenyl derivatives

Following established trends, perfluorinated alkyl and alkenyl derivatives of cadmium exhibit improved thermal stability. The alkenyl derivatives are generated by the addition of iodotrifluoroethylene to cadmium metal.

Reactions

Organocadmium compounds are less nucleophilic than the

organozinc Organozinc compounds in organic chemistry contain carbon (C) to zinc (Zn) chemical bonds. Organozinc chemistry is the science of organozinc compounds describing their physical properties, synthesis and reactions.The Chemistry of Organozinc Compoun ...

s. This reduced reactivity is demonstrated in the conversion of

acyl chloride In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group . Their formula is usually written , where R is a side chain. They are reactive derivatives of carboxylic acids (). A specific example o ...

s to

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

s with these reagents. This reaction was reported by

Henry Gilman Henry Gilman (May 9, 1893 – November 7, 1986) was an American organic chemist known as the father of organometallic chemistry, the field within which his most notable work was done. He discovered the Gilman reagent, which bears his name. Earl ...

in 1936 and was used until less toxic cuprates were available. The related Grignard reagent would react further, giving to the tertiary

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

. Methyl cadmium was used in one of the steps leading to

cholesterol total synthesis Cholesterol total synthesis in chemistry describes the total synthesis of the complex biomolecule cholesterol and is considered a great scientific achievement. The research group of Robert Robinson (organic chemist), Robert Robinson with John Cor ...

: :

Organocadmium chemistry cholesterol synthesis Woodward

Another synthetic use of an organocadmium is the reaction of diisoamylcadmium with β-carbomethoxypropionyl chloride to methyl 4-keto-7-methyloctanoate without reacting further with the

group or the ester group. This selectivity is observed provided that the reaction is carried out salt free. When the cadmium reagent is generated in situ from a cadmium salt, the halide generates a more nucleophilic organocadmium reagent, an ate complex. The same salt effect can be observed with organozinc compounds. Dimethylcadmium has been used to synthesize colloidal nanocrystals of II-VI materials such as cadmium selenide. Its toxic and volatile nature has led researchers to look elsewhere for cadmium precursors such as cadmium oxide.

Toxicity

Cadmium compounds are toxic. Dimethylcadmium is toxic to the kidney, the liver, the central nervous system, and the respiratory organs when inhaled. Cadmium compounds in general are considered to be carcinogen to humans by the

IARC IARC may refer to: * International Aerial Robotics Competition * International Age Rating Coalition * International Agency for Research on Cancer * International Arctic Research Center * Israel Amateur Radio Club * iArc IARC may refer to: * Internat ...

References

{{ChemicalBondsToCarbon Organometallic compounds Cadmium compounds