A family of 3d metal clusters based on N-N single bonds bridged quasi-linear trinuclear cores: the Mn analogue displaying single-molecule magnet behavior.

The reactions of the diacylhydrazine ligands N , N '-bisalicyl-2,6-pyridine dicarbohydrazide (H 6 sphz) and N , N '-bis(3-methoxysalicyl)-2,6-pyridine dicarbohydrazide (H 6 msphz) with various 3d metal salts, afforded a series of coordination clusters, namely, [Mn III 2 Mn II (sphz)(acac) 2 (CH 3 OH) 4 ] (1, acac - = acetylacetone anions), [Ni II 3 (msphz)(Py) 4 ] (2, Py = pyridine), [Cu II 6 (sphz) 2 (Py) 4 ] (3) and [Cu II 6 (msphz) 2 (Py) 4 ]·2DMF·2H 2 O (4). Cluster 1 and 2 are single ligand assembled quasi-linear trinuclear structures. Both 3 and 4 consist a pair of quasi-linear {Cu 3 } cores, which are linked together by two crossed ligands. The adjacent 3d metal ions in all trinuclear cores of 1-4 are bridged by N-N single bonds of ligands, which convey ferromagnetic (FM) interactions between 3d metal centers of 1, and antiferromagnetic (AFM) interactions between those of 2-4. In particular, the FM interactions and linear arrangement of mixed-valence Mn centers in 1 result in a large spin ground states value ( S T ) of 13/2, as well as single-molecule magnet (SMM) behavior of slow relaxation and hysteresis of magnetization.