GAS-PHASE, LIQUID AND SOLID COMPLEXES IN THE POCL3-FECL3 SYSTEM

Raman and UV/VIS spectra were obtained at temperatures up to 625 K for the gas-phase complex formed over POCl3-FeCl3 molten mixtures under s tatic equilibrium conditions. Raman spectra were also measured for mol ten POCl3-FeCl3 salt mixtures. A comparison of the spectral features o f the POCl3-FeCl3 vapours with those of the POCl3-FeCl3 molten mixture s at 525 K indicates that the gas-phase complex has a 1:1 stoichiometr y (POCl3 . FeCl3) with characteristic vibrational bands at 95, 362, 53 0, 1218 and 1268 cm(-1). The data indicate a C-3v symmetry for the POC l3 . FeCl3 complex. The energies of the M<--t charge-transfer transiti ons in the electronic absorption spectra of the POCl3 . FeCl3 gas-phas e complex suggest, in agreement with the Raman data, that complexing o ccurs through oxygen bridging. The 1:1 POCl3 . FeCl3 molecular liquid complex is the predominant species in equilibrium with POCl3 and iron chloride at temperatures around 500 K. At temperatures below 450 K and in POCl3-rich mixtures the '3:2' ionic liquid compound [Fe(POCl3)(6)] [FeCl4](3) was formed at the expense of POCl3 . FeCl3 (I). Two solids were identified at room temperature,yellow POCl3 . FeCl3 and red [Fe(P OCl3)(6)][FeCl4](3), and their Raman spectra have been recorded.