mT values for 2 and 20.1(10% of 2 diluted in 90 % of 0) remained constant at 8.168 cm 3 mol -1 K and 7.872 cm 3 mol -1 K, respectively, which are consistent with the expected value for an uncoupled Gd ion (7.875 cm 3 mol -1 K) (Figure and S6). Moreover, 2 and 20.1 did not exhibit a magnetic ordering down to 2 K. The magnetization vs. field plots for 2 and 20.1 are shown in Figure . S7. There is butterfly-type hysteresis for 2 and 20.1 at 1.8 K, indicating a rapid quantum tunnelling effect. The hysteresis temperature is higher than those reported for Gd complexes (cf. 0.7 K). 10g