1,2-Bis(dimethylphosphino)ethane explained

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 (CHPMe), dmpe is used as a compact strongly basic spectator ligand (Me = methyl), Representative complexes include V(dmpe)(BH), Mn(dmpe)(AlH), Tc(dmpe)(CO)Cl, and Ni(dmpe)Cl.

Synthesis

It is synthesised by the reaction of methylmagnesium iodide with 1,2-bis(dichlorophosphino)ethane:^[1]

ClPCHCHPCl + 4 MeMgI → MePCHCHPMe + 4 MgIClAlternatively 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.^[2]

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.

Notes and References

1. R. J. Burt . J. Chatt . W. Hussain. G. J. Leigh . A convenient synthesis of 1,2-bis(dichlorophosphino)ethane, 1,2-bis(dimethylphosphino)ethane and 1,2-bis(diethylphosphino)ethane . . 182 . 2 . 1979 . 203–6 . 10.1016/S0022-328X(00)94383-3.
2. Book: 10.1002/9780470132548.ch42. Preparation of Tetramethyldiphosphine Disulfide and Ethylenebis(Dimethylphosphine) (Dmpe). 199–200. 1985. 23. Bercaw. J. E.. Inorganic Syntheses. Parshall. G. W.. 9780470132548. }