PHOSPHANE COMPLEXES OF ALKALINE-EARTH METALS

The reaction of [bis(dimethylphosphanyl)(trimethylsilyl)methanide] Li[ (PMe2)(2)C(SiMe3)] with BeCl2 gave the homoleptic compound Be[(PMe2)(2 )C(SiMe3)](2) (5) with four beryllium-phosphorus bonds constituting a distorted tetrahedron around the beryllium center. The reaction of MgC l2 with Li[(PMe2)(2)C(SiMe3)] resulted in the formation of the bis-che late complex Mg[(PMe2)(2)C(SiMe3)](2) 2 THF (7), where the distorted c is-octahedral magnesium center is additionally coordinated by two THF ligands. In the reaction of 7 with an additional equivalent of Li[C(PM e2)(2)(SiMe3)], THF is released and the magnesate anion (Mg[(PMe2)(2)C (SiMe3)](3))(-) (8) was obtained. This compound is not only the first reported hexacoordinated magnesate, but also the first magnesium compo und with six magnesium-phosphorus bonds. With CaCl2 and Li[C(PMe2)(2)( SiMe3)], a heptacoordinated complex Ca[(PMe2)(2)C(SiMe3)](2) . 3 THF ( 10) with three coordinating THF ligands was isolated. The complexes we re characterized using Be-9{H-1}-, P-31{H-1}-, H-1-, C-13{H-1}-NMR NMR spectroscopy, and elemental analysis and by X-ray diffraction. The ne utral compounds are highly soluble in nonpolar solvents.