Electron capture phosphoranyl radicals in x-irradiated diphosphine disulfides. A single crystal ESR and a b i n i t i o quantum chemical study

Publisher Website
Google Scholar
Abstract
An electron spin resonance (ESR) study of phosphorus centered electron capture radicals trapped in single crystals of substituted diphosphine disulfides [R2P(S)P(S)R2, R=Me, Et, Ph] irradiated with x rays at 77 K is reported. The principal values and direction cosines of the hyperfine and g tensors were determined. It is shown that in all three compounds a three‐electron P–P bond radical is formed. The unpaired electron is found to be symmetrically distributed over the two phosphorus atoms. The direction of the phosphorus hyperfine coupling makes an angle of 20°–30° with the P–P bond. The alkyl substituted diphosphine disulfides reveal furthermore a radical in which the unpaired electron is asymmetrically distributed over the two phosphorus atoms. The electronic configuration of these radicals is best described as trigonal bipyramidal (TBP) with a central phosphorus atom and the unpaired electron in an equatorial position (TBP‐e). The second phosphorus atom and a sulfur substituent are located on the apical sites of the TBP. Irradiation yields for R=Et, Ph also a three‐electron P–S bond radical and a number of dissociation products. Ab initio quantum chemical calculations of the isotropic and anisotropic hyperfine couplings for the three‐electron P–P bond radicals are in good agreement with the experimental values and support the assignment.

This publication has 42 references indexed in Scilit: