but show an enhanced easy-axis anisotropy with D = −0.433(2) cm−1, E = 0.014(2) cm−1 and B 4 0 = + 1.5 ( 1 ) × 10 - 5 cm - 1 (from high frequency and X-band EPR). The thermal-activation parameters for magnetic moment reversal are Ueff/kB = 15.7(2) K and τ0 = 3.5(5) × 10−8 s (from AC susceptometry). Micro-SQUID measurements on single crystals show that below about 0.2 K the spin dynamics is dominated