Phosphaniminate von Alkalimetallen: Die Kristallstrukturen von [KNPCy₃]₄, [KNPCy₃]₄·2OPCy₃, [CsNPCy₃]₄·4OPCy₃ und [Li₄(NPPh₃)(OSiMe₂NPPh₃)₃(DME)]

The alkalimetal phosphoraneiminates [KNPCy₃]₄, (1) [KNPCy₃]₄·2OPCy₃ (2) and [CsNPCy₃]₄·4OPCy₃ (3) (Cy = cyclohexyl) which are obtainable by the reaction of pottassium amide or cesium amide with Cy₃PI₂ or Cy₃PBr₂ in liquid ammonia, as well as the lithium derivative [Li₄(NPPh₃)(OSiMe₂NPPh₃)₃(DME)] (4) have been characterized by crystal structure determinations. 4 has been formed by the insertion reaction of silicon greaze (-OSiMe₂)n into the LiN bonds of [LiNPPh₃]₆ in DME solution (DME = 1, 2-dimethoxyethane). 1: Space group P&1macr;, Z = 2, lattice dimensions at 193 K: a = 1389.8(1); b = 1408.1(1); c = 2205.2(2) pm; α = 78.952(10)?; β = 81.215(10)?; γ = 66.232(8)?; R1 = 0.0418. 2: Space group Pbcn, Z = 4, lattice constants at 193 K: a = 2943.6(2); b = 2048.2(1); c = 1893.8(1) pm; R1 = 0.0428. 3: Space group Cmc2₁, Z = 4, lattice dimensions at 193 K: a = 2881.6(2); b = 2990.2(2); c = 1883.7(2) pm; R1 = 0.0586. 4·1/2DME: Space group R&3macr;c, Z = 12, lattice dimensions at 193 K: a = b = 1583.5(1); c = 11755.3(5) pm; R1 = 0.0495. All complexes have heterocubane structures. In 1-3 they are formed by four alkali metal atoms and by the nitrogen atoms of the (μ₃-NPCy₃^-) groups, whereas 4 forms a "heteroleptic" Li₄NO₃ heterocubane.