A role for free phosphinidenes in the reaction of magnesium and sterically encumbered ArPCl2 in solution at room temperature

The reduction of ArPCl2 (Ar=2,6-Trip2C6H3, 2,6-Mes2C6H3, 2,6-(2,6-Me2C6H3)2C6H3, or 2,4,6-tBu3C6H3) by various forms of activated magnesium have been examined and compared with previously reported reductions using unactivated magnesium. The current reactions are more rapid and give rise to products that are reminiscent of products obtained by irradiation of phosphanylidene-σ4-phosphoranes ArPPMe3 bearing the same Ar groups. The correlation in product distributions suggests the involvement of phosphinidenes in the reduction of aryldichlorophosphines by activated magnesium.