Heat capacity calorimetry of a molecule-based magnetic material N(n-C4H9)4[CoIIFeIII(ox)3]

Calorimetric studies were carried out for the ferrimagnetic molecule-based material N(n-C4H9)(4)[(CoFeIII)-Fe-II (ox)(3)]. The magnetic transition was detected at 29.7 K, along with a small heat capacity hump around 12 K. A broad phase transition centred at 210 K was observed due to an order-disorder mechanism owing to increasing conformational change of the N(n-C4H9)(4)(+) cation. The enthalpy and 4 entropy gains corresponding to the heat capacity anomalies were estimated. The sum of the entropy gains at the 29.7 and 12 K anomalies was close to the expected magnetic entropy R In (6X4). This indicated that the heat capacity anomaly around 12 K has magnetic origin. (C) 2001 Elsevier Science BV All rights reserved.