Magnetocaloric effect and slow magnetic relaxation in two only azido bridged ferromagnetic tetranuclear metal clusters

Two M-II tetranuclear complexes bridged only by azido, Mn-4(N-3)(7.3)Cl0.7L4 (1) and Co-4(N-3)(8)L-4 (2) in which the four M-II ions are precisely coplanar bridged only by six azido anions, were obtained by using 4,5-diazafluoren-9-one (L) as a corner ligand. Magnetic studies indicate that ferromagnetic coupling was conducted by the azido anions between M-II ions. At low temperature, 1 exhibits a large magnetocaloric effect and 2 shows field-induced multiple magnetic relaxations.