Decamethylcobaltocene
Encyclopedia
Decamethylcobaltocene is an organocobalt compound with the formula Co(C5(CH3)5)2, abbreviated CoCp*2. It is dark brown solid. This compound is used as a strong reducing agent in organometallic chemistry
.
The permethylated form is more air-sensitive than the parent cobaltocene
, owing to the inductive effects of methyl groups. It is a thermally stable compound and easily undergoes vacuum sublimation
.
, having idealized D5d symmetry. Like cobaltocene, decamethylcobaltocene has a 19 electron count in its valence shell and is paramagnetic.
It is used as a one-electron reducing agent
. Relative to the ferrocene
/ferrocenium couple, the redox potential for the [CoCp*2]+/0 couple is -1.94 V compared to the [CoCp2]+/0 couple of -1.33 V. For comparison, the difference between the redox ferrocene and its permethylated derivative FeCp*2
]+/0 couple is -0.59 V.
have very similar structures. The additional electron occupies an orbital that is anti-bonding with respect to the Co-C bonds. Co-C distances of 2.118 Å at room temperature are slightly longer than seen in other metallocenes such as the Fe-C bonds in ferrocene, and fairly longer than its parent cobaltocene at 2.096 Å at room temperature (in the gas-phase, the Co-C distances in Cp2Co is 2.119 Å, closely resembling the Co-C bond lengths of decamethylcobaltocene.
An illustrative redox reaction of decamethylcobaltocene is:
Organometallic chemistry
Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character...
.
Synthesis
Decamethylcobaltocene is prepared by treatment of LiCp* with CoCl2:- 2 LiCp* + CoCl2 → 2 LiCl + CoCp*2
The permethylated form is more air-sensitive than the parent cobaltocene
Cobaltocene
Cobaltocene, known also as biscobalt or even "bis Cp cobalt", is an organocobalt compound with the formula Co2. It is a dark purple solid that sublimes readily slightly above room temperature. Cobaltocene was discovered shortly after ferrocene, the first metallocene...
, owing to the inductive effects of methyl groups. It is a thermally stable compound and easily undergoes vacuum sublimation
Sublimation
Sublimation may refer to:* Sublimation , the change from solid to gas without entering liquid phase* Sublimation , the transformation of emotions* Sublimation , a music album by Canvas Solaris-See also:...
.
Bonding
Co(C5Me5)2 is a metalloceneMetallocene
A metallocene is a compound typically consisting of two cyclopentadienyl anions bound to a metal center in the oxidation state II, with the resulting general formula 2M. Closely related to the metallocenes are the metallocene derivatives, e.g. titanocene dichloride, vanadocene dichloride...
, having idealized D5d symmetry. Like cobaltocene, decamethylcobaltocene has a 19 electron count in its valence shell and is paramagnetic.
It is used as a one-electron reducing agent
Reducing agent
A reducing agent is the element or compound in a reduction-oxidation reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized"...
. Relative to the ferrocene
Ferrocene
Ferrocene is an organometallic compound with the formula Fe2. It is the prototypical metallocene, a type of organometallic chemical compound consisting of two cyclopentadienyl rings bound on opposite sides of a central metal atom. Such organometallic compounds are also known as sandwich compounds...
/ferrocenium couple, the redox potential for the [CoCp*2]+/0 couple is -1.94 V compared to the [CoCp2]+/0 couple of -1.33 V. For comparison, the difference between the redox ferrocene and its permethylated derivative FeCp*2
Decamethylcobaltocene
Decamethylcobaltocene is an organocobalt compound with the formula Co2, abbreviated CoCp*2. It is dark brown solid. This compound is used as a strong reducing agent in organometallic chemistry.-Synthesis:...
]+/0 couple is -0.59 V.
Structure
Decamethylcobaltocene and decamethylferroceneDecamethylferrocene
Decamethylferrocene is a sandwich compound. In terms of structure and bonding it resembles ferrocene, but with a methyl group on each of the carbons of the Cp rings. It is a yellow crystalline solid that is a weak reductant.-Preparation:...
have very similar structures. The additional electron occupies an orbital that is anti-bonding with respect to the Co-C bonds. Co-C distances of 2.118 Å at room temperature are slightly longer than seen in other metallocenes such as the Fe-C bonds in ferrocene, and fairly longer than its parent cobaltocene at 2.096 Å at room temperature (in the gas-phase, the Co-C distances in Cp2Co is 2.119 Å, closely resembling the Co-C bond lengths of decamethylcobaltocene.
An illustrative redox reaction of decamethylcobaltocene is:
- 2 CoCp*2 + C60 → [CoCp*2]+ + [C60]2-