INTERSYSTEM CROSSING DYNAMICS IN THE SPIN-CROSSOVER SYSTEMS [M-FE(PIC)(3)]CL-2-CENTER-DOT-SOL (M=MN OR ZN, SOL=MEOH OR ETOH)

The intersystem crossing rates from the high-spin (5T 2) to the low-spin (1A1) state in the spin-crossover systems [M:Fe(pic)3]Cl2·Sol, M=Zn or Mn, Sol=MeOH or EtOH have been measured in the temperature range between 5 and 170 K. Within the series of investigated compounds, the low-temperature rates are strongly correlated to the transition temperatures T1/2 of the thermal transition. The temperature dependence of the relaxation rates can only be understood in terms of a nonadiabatic multimode multiphonon process involving lattice vibrations. The relaxation rates are controlled by the zero point energy difference ΔE0, the Huang-Rhys parameters S opi and Sak for intramolecular and lattice vibrations, respectively, and the frequencies ωi the intramolecular vibrations. © 1994 American Institute of Physics.