Published online by Cambridge University Press: 25 February 2011
A chemical modification exploiting functional groups such as ether and methylene as bridges between high-spin assemblies has been carried out as a usable method to increase dimensionality of spin structure. Exchange interaction via an ether or a methylene bridge between two high-spin assemblies has been studied by single-crystal ESR spectroscopy. Whether it is ferromagnetic or antiferromagnetic depends upon the substituted position of the bridge, demonstrating the important role of the topological nature in spin alignment. It turns out that superexchange interaction or hyperconjugation mechanism can dominate spin alignment between high-spin assemblies. Using the criteria obtained, model compounds for units of organic ferrimagnets have been synthesized. They possess antiferromagnetically-exchange coupled heterospins and the salient features of their spin structures are characterized in terms of the spin density distribution as determined by single-crystal 1H-ENDOR (Electron-Nuclear-DOuble Resonance) spectroscopy.