Synthesis, X-ray structure and characterization of a novel [fc(IMH)2H]+[Co(hfac)3]− salt with hydrogen bonded ferrocenyl bis(imino hydroxylamino) building blocks

The reaction of ferrocenylene bis(α-nitronyl nitroxide) diradical (1; [fc(NIT)2]) with Co(hfac)2 produces the reduction of the radical character of 1 with the formation of the diamagnetic ferrocenyl bis(α-imino nitroxide) cation, [fc(IMH)2H]+, which forms with the [Co(II)hfac3]−, as the counterion, the complex salt 4. This salt crystallizes in the P spatial group exhibiting an exotic supramolecular architecture in which the molecular ions are bonded through hydrogen bonds forming single chains with a zipper-like arrangement. Remarkable is the presence in complex salt 4 of two proton tautomeric forms in the [fc(IMH)2H]+ units.