Synthesis and structures of Sr6P8 polyhedra in mixed phosphanides/phosphandiides of strontium

The strontiation of (H2PSiPr3)-Pr-i (1) with (THF)(2)Sr[N(SiMe3)(2)](2) in THF yields colorless tetrakis(tetra-hydrofuran-O)strontium bis(triisopropyl silylphosphanide) (3). The central alkaline earth metal atom has an octahed ral environment with the phosphanide ligands in trans position. The homomet alation in toluene leads to the elimination of 1 and THE Cooling of this so lution gives crystals of colorless tetrakis(tetrahydrofuran-O)hexastrontium -tetrakis(triisopropylsilylphosphanide) -tetrakis(triisopropylsilylphosphan diide) (4). The equimolar reaction of (H2PSiBu3)-Bu-t (2) with (THF)(2)Sr[N (SiMe3)(2)](2) in toluene yields in the first step heteroleptic dimeric {(M e3Si)(2)NSr(THF)(2)[P(H)(SiBu3)-Bu-t]}(2) (5)(2). This compounds monomerize s in THF to (Me3Si)(2)N-Sr-(THF)(4)[P(H)(SiBu3)-Bu-t] (6), which forms an e quilibrium with the homoleptic dismutation products (THF)(2)Sr[N(SiMe3)(2)] (2) and (THF)(4)Sr[P(H)(SiBu3)-Bu-t](2) (7). Compound (5)(2) undergoes a in tramolecular strontiation and bis(tetrahydrofuran-O)hexastrontium-tetrakis[ tri(tert-butyl)silylphosphanide]-kis[tri(tert-butyl)silylphosphandiide] (8) is isolated. The central Sr6P8-polyhedra of 4 and 8 are very similar.