Trimethylphosphine

It is a pyramidal molecule with approximate C3v symmetry. The C–P–C bond angles are approximately 98.6°. PMe3 can be prepared by the treatment of triphenyl phosphite with methylmagnesium chloride: : 3 CH3MgCl + P(OC6H5)3 → P(CH3)3 + 3 C6H5OMgCl The synthesis is conducted in dibutyl ether, from which the more volatile PMe3 can be distilled. ==Reactions==

With a pKa of 8.65, PMe3 reacts with strong acids to give salts [HPMe3]X. This reaction is reversible. With strong bases, such as alkyl lithium compounds, a methyl group undergoes deprotonation to give PMe2CH2Li. PMe3 is easily oxidised to the phosphine oxide with oxygen. It reacts with methyl bromide to give tetramethylphosphonium bromide. Coordination chemistry Trimethylphosphine is a highly basic ligand that forms complexes with most metals. As a ligand, trimethylphosphine's Tolman cone angle is 118°. This angle is an indication of the amount of steric protection that this ligand provides to the metal that to which it is bound. Since trimethylphosphine is a compact ligand, several can bind to a single transition metal, as illustrated by the tungsten complex shown in the figure. Its complex with silver iodide, AgI(PMe3) is an air-stable solid that releases PMe3 upon heating. ==Safety==

PMe3 is toxic and pyrophoric. It converts to a much safer phosphine oxide upon treatment with sodium hypochlorite or hydrogen peroxide. ==References==