Organomagnesium phosphanide Grignard analogues -: Synthesis, structural characterisation and solution behaviour of [BuMg{P(CH[SiMe3]2)(C6H3-2-OMe-3R)}]2 [R = H, Me]

The reaction between either one or two equivalents of the secondary phosphane {(Me3Si)(2)CH}PH(C6H3-2-OMe-3-R') [R' = H (1a), Me (1b) I and Bu2Mg yields the heteroleptic complexes [BuMg{P[CH(SiMe3)(2)](C6H3-2-OMe-3-R')}](2) [R' = H (2a), Me (2b)], irrespective of the ratio of 1 to Bu2Mg, X-ray crystallography shows that 2a and 2b crystallise as dimers containing a central Mg2P2 core. Dissolution of either 2a or 2b in THF results in complex degradation and formation of the tertiary phosphanes {(Me3Si)(2)CH}P(Me)(C6H3-2-OMe-3-R') and unidentified magnesium-containing products.