Magnetic Exchange In Mn-Ii[Tcne] (Tcne = Tetracyanoethylene) Molecule-Based Magnets With Two- And Three-Dimensional Magnetic Networks

The chemical bond and its role as a mediator of magnetic exchange interaction remains a crucial aspect in the study of molecular magnetism. Within the M[TCNE] (M = 3d metal; TCNE = tetracyanoethylene) class of organic-based magnets, only V[TCNE](x) (x similar to 2) orders magnetically above room temperature (T-c similar to 400 K), while structural factors underlying this exceptional behavior remain elusive. Conversely, Mn-[TONE] complexes of diverse crystal structure have recently become available, e.g., 2D-layer [Mn(TCNE)(NCMe)(2)] [SbF6] (T-c similar to 75 K), and 3D-network [Mn(TCNE)(1.5)](I-3)(0.5) (T-c similar to 170 K). Using this experimental structural data, DFT simulations have been performed and the spin-polarized electronic structures resolved. The nature of orbital interactions crucial for understanding magnetic behavior was revealed. Magnetic coupling, spin-orbital hybridization, as well as formation of exchange/superexchange pathways have been identified and interpreted in terms of the dimensionality of magnetic interaction. These results illustrate the complex nature of the electron exchange landscape in M[TCNE] molecule-based magnets.