Synthesis and vibrational spectra of some tri- and di-phenylhaloplumbates

Abstract

Phenylhaloplumbate salts of the type [Et 4N][Ph 3PbXY] (X or Y = Cl, Br, I), [Et 4N][Ph 6Pb 2X 2Y] (X or Y=Cl, Br), [Et 4N][Ph 2PbX 3] (X = Cl, Br, I), and [Me 4N] 2[Ph 2PbX 4] (X = Cl, Br) have been prepared and characterised in the solid state by infrared and Raman spectroscopy over the range 250–80 cm −1. Similar vibrational data are reported for [Me 4N][Ph 3PbX 2] (X = Cl, Br) and [Me 4N][Ph 2PbCl 3] as well as new data for Ph 3PbX and Ph 2PbX 2 (X = Cl, Br, I). These infrared and Raman data are consistent with 5-coordinate, approximately trigonal-bipyramidal structures for triphenyllead systems (except Ph 3PbI) and 6-coordinate, approximately octahedral structures for diphenyllead systems (except Ph 2PbI 2), the required degree of coordination being achieved by halogen bridges where necessary. Stretching modes associated with halogen bridges are observed as strong, broad infrared bands only weakly Raman active, characteristics which suggest that these bonds have high ionic character.