Cobaltocene
- Di (cyclopentadienyl ) cobalt
- Bis (cyclopentadienyl ) cobalt
Black solid
Fixed
176-180 ° C
Insoluble in water
Attention
Template: Infobox chemical / molecular formula search available
Cobaltocene ( Di (cyclopentadienyl ) cobalt or bis (cyclopentadienyl ) cobalt ) is a metallocene, i.e., a metal organic compound containing aromatic ring systems. Cobaltocene is structurally related to the very stable ferrocene. The sum formula is C10H10Co.
Properties
Cobaltocene crystal forms black needles with a melting point of 176-180 ° C. In nonpolar solvents such as hexane or toluene, it is readily soluble. It is very sensitive to air, as it is easy ( = cyclopentadienyl Cp) is oxidized to the yellow-green cation Cp2Co .
Bonding
Cobaltocene is formally composed of a cobalt ( II) cation and two cyclopentadienyl anions ( C5H5 ). Generally speaking, therefore an uncharged complex. The binding ratios are similar to those of ferrocene: The cyclopentadienyl anions have as aromatics via a delocalized π -electron system. Each of these two ligands may provide the Co ( II) cation 6 π - electrons available. The cobalt ( II) cation itself has seven electrons in the valence shell, so it still gets 12 electrons from the ligand, so that it has = 19 valence electrons in complex 7 12. Thus, it has one more electron than would be favorable according to the 18- electron rule, so this electron must occupy an antibonding molecular orbital. This fact also explains the ease of oxidation of cobaltocene to the cation with 18 valence electrons. The Cp -Cp distance is 340 pm. He is slightly longer than in ferrocene (332 pm ), which can be explained by the occupation of anti-bonding orbital with an electron.
Representation
Displaying cobaltocene can be made by the reaction of anhydrous cobalt (II ) chloride or Hexamincobalt (II ) chloride with cyclopentadienylsodium in tetrahydrofuran ( THF). The reaction must be performed under inert gas, because the starting materials and the reaction product are sensitive to air. The product can then be isolated and purified by sublimation in vacuo.