No abstract

Syntheses of stable and metastable isomersfor each of the chlorophenylphosphoranes, PhPCI, , Ph,PCI, and Ph,PCI, , together with some Lewis acid salts are described. Comparison of Raman spectra of the salts with one set of isomers suggests an ionic formulation [PhmPCl~-,] 1Cl-l (1 < n < 3); correlation with spectra of Sb and As analogues of known structure suggest pseudo-trigonal bipyramidal (\lrtbp) structures for the other isomers. Thermodynamically stable isomers are ionic Ph,PCI+CI-, Jltbp Ph,PCI, and Jlthp PhPCI, . Vibrational Raman assignments for the skeletal modes are given for each of the isomers and some of their Lewis acid salts. Frequency shifts arising from non-bonded interactions in the ionic species are compared with those in the methyl-substituted analogues.

A synthetic and Raman investigation of isomerism in the bromophenylphosphoranes has shown no evidence for ionic-covalent isomerism analogous to that in the chlorophenylphosphoranes. Two ionic modifications of PhPBr, have been identified by Raman spectroscopy, whereas Ph,PBr, was found to exist in only one ionic form, Ph,PBr,+Br-. A recent proposal that Ph,PBr, is a molecular fourco-ordinate species is disputed and evidence supporting an ionic formulation Ph,PBr+Br--is presented. Vibrational Raman assignments for the bromophenylphosphoranes and some of their tetrabromoborate Receitred 18th January 1994; Paper 4/003 16K

No abstract