Chemical Bond in the Cyclic Anions P64- and As64-: Synthesis, Crystal Structure, and Electron Localization Function of {Rb[18]crown-6)}2Rb2As66 NH3

摘要

The cyclohexaphosphide anion P64- is only encountered in the very air and moisture sensitive binary compounds M4P6 (M=K, Rb, Cs)[1]-[3] in the solid state or as a ligand in organometallic complexes. In both cases the P64- ion has a molecular shape close to D6h symmetry.[4]-[8] Solvation of the binary compounds M4P6 in ethylenediammine or liquid ammonia, does not yield stable solutions of P64- ions (according to NMR spectroscopy) because these react to form a variety of compounds such as the lone pair aromatic cyclotetraphosphide anion P42- [9] and the cyclopentaphosphide anion P5-,[10] the heptaphosphanorticyclane anion P73- and also the undecaphosphatrishomocubane anion P113-.[11] Thus, the isolation of the P64- ion in solvate crystals, in crystals containing it as an isolated anion without metal contacts, or as an ion complex has not been possible, and to date, attempts to detect it in liquid ammonia solution have also failed. A previous report on the existence of P64- in an ethylenediammine solution has been shown to be in error, in this case a singlet in the 31P NMR spectra was falsely assigned to P64- instead to P42-.[2], [9]