Ferromagnetism in [Mn(Cp*) 2 ] + ‐Derived Complexes: the “Miraculous” Stacking in [Mn(Cp*) 2 ][Ni(dmit) 2 ]

The synthesis and characterisation (X‐ray structure and magnetism) of metal complexes (Ni, Au) with the [Mn(Cp*) 2 ] + cation and the dmit 2− and dmid 2− ligands are reported. [Mn(Cp*) 2 ][Ni(dmit) 2 ] ( 1 ) and [Mn(Cp*) 2 ][Au(dmit) 2 ] ( 2 ) exhibit the same structural arrangement, built on stacks of [Ni(dmit) 2 ] − pairs separated by two [Mn(Cp*) 2 ] + cations, showing a ··· D + D + A − A − D + D + A − A − ··· motif. On the contrary, the dmid 2− derivative [Mn(Cp*) 2 ][Ni(dmid) 2 ]·CH 3 CN ( 3 ) exhibits a totally different structure, built on mixed layers composed of one [Ni(dmid) 2 ] − unit separated by two [Mn(Cp*) 2 ] + cations, showing a ··· D + D + A − D + D + A − ··· motif. The layers are separated from each other by perpendicular [Ni(dmid) 2 ] − units and solvent molecules. Compound 2 exhibits antiferromagnetic interactions, whereas 1 and 3 exhibit ferromagnetic interactions at low temperature. Moreover, as confirmed by AC and DC magnetic susceptibility measurements, 1 is a ferrimagnet, the first ever derived from a 1,2‐bis‐dithiolene ligand. The ferromagnetic interactions in 1 and 3 are explained using the McConnell I mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)