Self-Assembled Dinuclear, Trinuclear, Tetranuclear, Pentanuclear, and Octanuclear Ni(ll) Complexes of a Series of Polytopic Diazine Based Ligands: Structural and Magnetic Properties

The nickel coordination chemistry of a series of polytopic diazine (N-N) based ligands has been examined. Selfassembly reactions lead to examples of dinuclear, trinuclear, tetranuclear, pentanuclear, and octanuclear complexes, all of which exhibit magnetic exchange coupling, with antiferromagnetic and ferromagnetic examples. Structural details are presented for [(L1)2Ni2(H20)2](N03)4-3H20 (1), .... The linear trinuclear Ni(ll) complex (2) has a c/s-N-N single bond bridge, and a water bridge linking the central Ni(ll) to each external Ni(ll) center in each of two similar trinuclear subunits, and exhibits intramolecular ferromagnetic exchange (J = 5.0 cm). A novel octanuclear metallacyclic ring structure exists in 5, with trans-N-N single bond bridges linking adjacent Ni(ll) centers, leading to quite strong intramolecular antiferromagnetic exchange (J = -30.4 cm).