The fitting of the χ′ and χ″ data (Figures and) with the extended Debye model 63 (see ESI) yielded magnetization relaxation times (τ) and their distribution (α) at each temperature for [Co(1-3)](ClO4)2 (see Tables for values obtained from the fits). Reliable fits of the AC magnetic data were obtained for the temperature range between 1.8 and 4.8 K. The α values range between 0.16-0.30, 0.07-0.25 and 0.07-0.25 for [Co(1-3)](ClO4)2, respectively, showing a narrow distribution of the relaxation times. The curvature of the plot of ln(τ) vs T -1 (Figure ) points to the presence of several relaxation pathways that cannot be fitted with an Orbach process alone. Contributions from additional relaxation pathways were therefore considered and the relaxation times fitted using to Equation 1 (see Table for parameters):