Dimanganese decacarbonyl


Dimanganese decacarbonyl is the chemical compound with the formula Mn210. This metal carbonyl is an important reagent in the organometallic chemistry of manganese.

Synthesis

The compound was first prepared in low yield by the reduction of manganese iodide with magnesium under CO. A more efficient preparation entails reduction of anhydrous MnCl2 with sodium benzophenone ketyl under 200 atmospheres of CO. The availability of inexpensive methylcyclopentadienyl manganese tricarbonyl has led to a low pressure route to Mn210.

Structure

Mn210 has no bridging CO ligands: it can be described 5Mn-Mn5. There are two kinds of CO ligands; one CO on each Mn is coaxial with the Mn-Mn bond, and four on each manganese that are perpendicular to it. In the stable rotamer, the two Mn5 subunits are staggered. The overall molecule thus belongs to the point group D4d, which is an uncommon symmetry shared with S2F10.

Reactions

Mn210 is air stable as a crystalline solid, but solutions require Schlenk techniques. It finds limited use in organic synthesis.
Characteristic reactions:
The anion is a versatile nucleophile. Protonation gives the hydride , and methylation gives .
Mn210 is a volatile source of a metal and a source of CO.