THE USE OF PRESSURE-TUNING SPECTROSCOPY TO DISTINGUISH BETWEEN ONE-ELECTRON AND 2-ELECTRON TRANSFER PROCESSES

The first use of pressure-tuning spectroscopy as a diagnostic tool in the evaluation of an intervalence transition band to determine the num ber of electrons transferred is described. The trinuclear complex [(CN )(5)FeCNPt(NH3)(4)NCFe(CN)(5)](4-) was subjected in solution to hydros tatic pressures from ambient to 1.5 kbar giving a Delta V = -5.7+/-0. 2 cm(3) mol(-1). Calculated values from various models ranged from -5. 6 to -6.7 cm(3) mol(-1) assuming a one-electron transfer event and a n egligible inner-sphere reorganizational energy compared with the appar ently very large outer-sphere rearrangements that must occur.