Table 2. Fit Parameters of the Magnetic Relaxation Times (from AC Magnetic Susceptibility Measurements) for 1-Xa.
| compound | Hdc (Oe) | τtunnel (s) | C (K–n s–1) | n | τ0 (s) | Ueff (cm–1) |
|---|---|---|---|---|---|---|
| 1-Cl | 0 (slow process) | 111(9) | 10–8.94(3) | 45.1(1) | ||
| 0 (fast process) | 10–8.15(2) | 30.49(9) | ||||
| 1-Br | 0 | 0.0027(1) | 10–8.56(2) | 20.1(1) | ||
| 500 | 10–8.50(4) | 20.7(1) | ||||
| 1-I | 500 (slow process) | 0.0071(2) | 1.01(3) | 6.59(2) |
a
The quantum tunneling contribution to the magnetic relaxation of 1-Cl was determined from dc relaxation measurements (Figures S121 and S122), while values of τ0 and Ueff were obtained from fits of only the ac data. Two relaxation processes were characterized for 1-I on the ac time scale, but only the temperature dependence of the slower process (i.e., process 1, see Figure S119) could be determined.