1,2-Bis(dimethylphosphino)ethane

1,2-Bis(dimethylphosphino)ethane (dmpe) is a diphosphine ligand in coordination chemistry. It is a colorless, air-sensitive liquid that is soluble in organic solvents. With the formula (CH$2$PMe$2$)$2$, dmpe is used as a compact strongly basic spectator ligand (Me = methyl), Representative complexes include V(dmpe)$2$(BH$4$)$2$, Mn(dmpe)$2$(AlH$4$)$2$, Tc(dmpe)$2$(CO)$2$Cl, and Ni(dmpe)Cl$2$.



Synthesis
It is synthesised by the reaction of methylmagnesium iodide with 1,2-bis(dichlorophosphino)ethane:
 * Cl$2$PCH$2$CH$2$PCl$2$ + 4 MeMgI → Me$2$PCH$2$CH$2$PMe$2$ + 4 MgICl

Alternatively it can be generated by alkylation of sodium dimethylphosphide.

The synthesis of dmpe from thiophosphoryl chloride has led to serious accidents and has been abandoned.

Related ligands

 * Bis(dicyclohexylphosphino)ethane, a bulkier analogue, which is also a solid.
 * 1,2-Bis(diphenylphosphino)ethane, more air-stable than dmpe, but less basic.
 * 1,2-Bis(dimethylphosphino)benzene, a more rigid analogue of dmpe.
 * Tetramethylethylenediamine, the diamine analogue of dmpe.