BuMnCl can be prepared in THF, at 0 °C, by reaction of n-Butyllithium or BuMgX with Manganese(II) Chloride or, better, with the soluble ate complex MnCl4Li2.
Butylmanganese halide solutions must be handled under an inert atmosphere in the absence of moisture. In THF, BuMnX are stable at rt. In ether, BuMnI is stable at -10 °C and BuMnBr at 10 °C. These reagents are best generated in situ and used rapidly.
