Ph2PCH PPh2 Research Articles

A Soft Grip: Magnesium Complexes with a Phosphine-Modified Phosphonium Diylidic Lewis Base.

Simple strategies to obtain magnesium complexes with the soft chelating diylidic ligand [Ph2 PCHPPh2 (fluorenylidene)]- (dppmflu- ) were developed to evaluate the influence of the hard acid (cation) and soft base (anion) mismatch on the stability and reactivity of the formed derivatives. Deprotonation of the precursor Ph2 PCH2 PPh2 (flu) (dppmfluH) by an alkylmagnesium derivative or magnesium amide provided access to [{Mg(dppmflu)(μ-nBu)}2 ], [Mg(dppmflu){N(SiMe3 )2 }], and [{Mg(dppmflu)(μ-Me)}2 ], which were used as starting materials for further investigations. The reaction of [{Mg(dppmflu)(μ-nBu)}2 ] with PhSiH3 in the presence of THF allowed isolation of the magnesium hydride complex [{Mg(dppmflu)(μ-H)(thf)}2 ] without a stabilizing nitrogen donor ligand. Prolonged heating enforced ligand redistribution and [{Mg(dppmflu)(μ-H)(thf)}2 ] was converted to [Mg(dppmflu)2 ] and MgH2 . The homoleptic derivative [Mg(dppmflu)2 ], in which the magnesium center is in a very soft ligand environment, can open a THF molecule by frustrated Lewis pair reactivity to give [{Mg(dppmflu)(μ-OC4 H8 dppmflu)}2 ].

Synthesis of trinuclear gold(I) and gold(III) complexes containing the tridentate bis(diphenylphosphino)methanide ligand. Crystal structure of [Cl(C6F5)2Au{Ph2PCH(AuNC5H5)PPh2}AuCl

The reaction of [Au(C6F5)2(Ph2PCHPPh2)] with [AuX(L)][X = Cl or Br, L = tetrahydrothiophen (tht) or AsPh3] leads to trinuclear complexes [X(C6F5)2Au{Ph2PCH (AuL) PPh2}AuX] containing the tridentate [Ph2PCH PPh2]– ligand. Displacement of tht with L = PPh3, pyridine, or 4-methylpyridine leads to the corresponding derivatives. The structure of [Cl(C6F5)2Au{Ph2PCH (AuNC5H5) PPh2}AuCl] has been determined by X-ray diffraction: space group P, a=11.664(5), b=14.790(6), c= 18.344(6)Å, α=111.30(4), β= 94.1 8(4), γ=107.64(4)°, and Z= 2; R= 0.075 for 4 627 reflections.