The first structurally authenticated alkali metal 1,3-diphosphaallyl complex [{Bu^tC(PMes)2}Li(thf)3] (Mes = 2,4,6-Me3C6H2): an alternative synthetic approach to substituted 1,3-diphosphaallyl complexes

Reaction of the phosphavinyl Grignard reagent [Z-MesP=C(But)MgBr.OEt2]2 (Mes = 2,4,6-Me3C6H2) with MesPCl2 affords the corresponding 1,3-diphosphapropene compound [Z-MesP=C(But)P(X)Mes] (X = Cl, Br); subsequent reaction with two equivalents of elemental lithium in thf affords the title compound [{ButC(PMes)2}Li(thf)3], which contains an asymmetric (eta)1-1,3-diphosphaallyl ligand.