Chemical Bond in the Cyclic Anions P_6~(4-) and As_6~(4-): Synthesis,Crystal Structure,and Electron Localization Function of {Rb[18]crown-6)}_2-Rb_2As_6centre dot6NH_3

摘要

The cyclohexaphosphide anion P_6~(4-) is only encountered in the very air and moisture sensitive binary compounds M_4P_6 (M = K,Rb,Cs) in the solid state or as a ligand in organometallic complexes.In both cases the P_6~(4-) ion has a molecular shape close to D_(6h) symmetry.Solvation of the binary compounds M_4P_6 in ethylenediammine or liquid ammonia,does not yield stable solutions of P_6~(4-) ions (according to NMR spectroscopy) because these react to form a variety of compounds such as the lone pair aromatic cyclotetraphosphide anion P_4~(2-) and the cyclopentaphosphide anion P_5~-,the heptaphosphanor-ticyclane anion P_7~(3-) and also the undecaphosphatrishomocu-bane anion P_(11)~(3-).