Acceptor properties of tetrachloro(phenyl)phosphorane and of the trichloro(phenyl)phosphonium ion

Abstract

The acceptor properties of PPhCl₄ and of the [PPhC₃]⁺ ion towards some Lewis bases have been investigated. Chloride ion adds to PPhCl₄ in the presence of a large cation to produce [PPhCl₅]^–, which exchanges rapidly with PPhCl₄ on the n.m.r. time scale. Unhindered pyridines L of sufficiently high basicity give molecular complexes PPhCl₄·L, similar to those of PCL₅. Bidentate pyridines L′ yield ionic six-co-ordinate derivatives [PPhCl₃L′] Cl; the cation has two isomeric forms which co-exist in solution. Pyridine reacts rapidly with [PPhCl₃,][SbCl₆] and [PPhCl₃][PCl₆], apparently to give adducts of the molecular species, PPhCl₄·py and MCl₅·py (M = P or Sb). Bidentate pyridines L′ yield 1 : 1 complexes [PPhC₃L′][MCl₆], which are stable in solution if soluble and again show the presence of cationic isomers. Several new solid compounds have been isolated and further characterised by means of elemental analysis, i.r. spectroscopy, and in some instances ³¹P n.m.r. and ³⁵Cl n.q.r. spectroscopy.