INFRARED SPECTRA OF DICHLORO- AND DIBROMOPHOSPHINYL RADICALS IN SOLID ARGON

Simultaneous condensation of phosphorus trichloride and tribromide at high dilution in argon on a cesium iodide window at 15°K with a lithium vapor stream produces new infrared absorptions which can be assigned to the lithium halides and the dihalophosphinyl radicals. Identification of the dihalophosphinyl radicals is supported by chlorine isotopic splittings and comparison of spectra from the reaction of PCI3 and PBr3 with both lithium and sodium. Chlorine isotopic splittings suggest the vibrational assignments v1 452.0 and v3 524.8 cm-1 for PCl2, and by analogy the assignments v1 369.0 and v3 410.0 cm-1 for PBr2. Force constants are calculated for the dihalophosphinyl radicals and are compared to those for the phosphorus trihalides.