Preorganized bi- and trimetallic complexes as building blocks for the controlled assembly of extended coordination compounds with magnetic ordering

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The project contributes to answer the basic question: how can long-range magnetic ordering be achieved in azide bridged coordination frameworks in a predictable manner? Two intertwined lines of research are followed: (i) A set of dinucleating pyrazolate ligands is used for the controlled assembly of novel azide-bridged 1D J-alternating chain compounds. Within the preorganized bimetallic building blocks, the binding mode of the azide co-ligand is predetermined by the characteristics of the ligand scaffold. Such modular approach also enables the unambiguous assignment of the two different coupling constants, since oligonuclear species that represent fragments of the extended alternating chain can be selectively prepared from unsymmetrical dinucleating ligands. (ii) The magnetic properties of novel oligonuclear complexes with unusual azide bridges are studied, in which each azide ion links three or four metal ions, respectively. Knowledge of the magnetic superexchange mediated by such multiply bridging ligands will extent the magnetostructural correlations already developed for the simpler and more common azide binding modes. Finally, these azide linkages are probed for the assembly of 2D and 3D extended coordination networks with long-range magnetic ordering.