Linkage isomerism and spin frustration in heterometallic rings: synthesis, structural characterization, and magnetic and EPR spectroscopic studies of Cr(7)Ni, Cr(6)Ni(2), and Cr(7)Ni(2) rings templated about imidazolium cations.

The synthesis and structural characterization of three heterometallic rings templated about imidazolium cations is reported. The compounds are [2,4-DiMe-ImidH][Cr(7)Ni(II)F(8)(O(2)CtBu)(16)] 1 (2,4-DiMe-ImidH=the cation of 2,4-dimethylimidazole), [ImidH](2)[Cr(6)Ni(II) (2)F(8)(O(2)CCtBu)(16)] 2 (ImidH=the cation of imidazole), and [1-Bz-ImidH](2) [Cr(7)Ni(II) (2)F(9)(O(2)CtBu)(18)] 3 (1-Bz-ImidH=the cation of 1-benzylimidazole). The structures show the formation of octagonal arrays of metals for 1 and 2 and a nonagon of metal centers for 3.