Organomanganese chemistry

Organomanganese chemistry is the chemistry of organometallic compounds containing a carbon to manganese chemical bond. In a recent review Cahiez et al. argue that as manganese is cheap and benign (only iron performs better in these aspects), organomanganese compounds have potential as chemical reagents, although currently they are not widely used as such despite extensive research. Organomanganese chemistry is the chemistry of organometallic compounds containing a carbon to manganese chemical bond. In a recent review Cahiez et al. argue that as manganese is cheap and benign (only iron performs better in these aspects), organomanganese compounds have potential as chemical reagents, although currently they are not widely used as such despite extensive research. The first organomanganese compounds were synthesised in 1937 by Gilman and Bailee who reacted phenyllithium with manganese(II) iodide to form phenylmanganese iodide (PhMnI) and diphenylmanganese (Ph2Mn). The reactivity of organomanganese compounds can be compared to that of organomagnesium compounds and organozinc compounds. The electronegativity of Mn (1.55) is comparable to that of Mg (1.31) and Zn (1.65) making the carbon atom (EN = 2,55) nucleophilic. The reduction potential of Mn is also intermediate between Mg and Zn. Key disadvantage of organomanganese compounds is that they can be obtained directly from the metal only with difficulty. General methods for the synthesis of organomanganese compounds exist.Organomanganese halides can be obtained by reaction of manganese halides (manganese(II) bromide, manganese(II) bromide) with organolithium or organomagnesium compounds in transmetallation: Manganese iodide can be prepared in situ from manganese and iodine in ether. Further reaction gives the symmetrical diorganomanganese compound. Organomanganates (the ate complex) are the most stable compounds: The organomanganese compounds are usually prepared in THF where they are the most stable (via complexation) even though many of them must be handled at low temperatures. Simple dialkylmanganese decompose by beta-hydride elimination to a mixture of alkanes and alkenes. Many organomanganese complexes are derived from dimanganese decacarbonyl, Mn2(CO)10. Bromination and reduction with lithium affords BrMn(CO)5 and LiMn(CO)5, respectfully. These species are precursors to alkyl, aryl, and acyl derivatives: The general pattern of reactivity is analogous to that for the more popular cyclopentadienyliron dicarbonyl dimer.