2p–4f one-dimensional chains and two-dimensional networks assembled by a multicoordinating nitronyl nitroxide radical ligand

Abstract

Two new lanthanide (Ln)-radical one-dimensional (1D) chains {[Ln(hfac)₃(Nit-Ph-3,5-bIm)(H₂O)]·C₄H₁₀O}_n (Ln^III = Tb 1 and Dy 2) and two two-dimensional (2D) networks [Ln(hfac)₃(Nit-Ph-3,5-bIm)]_n (Ln^III = Pr 3 and Nd 4) were obtained using the multicoordinating nitronyl nitroxide radical ligand Nit-Ph-3,5-bIm (Nit-Ph-3,5-bIm = 2-[3,5-bis(1-imidazole)-phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonate). For compounds 1 and 2, each Nit-Ph-3,5-bIm radical links two Ln(hfac)₃ units via its two imidazolyl-N atoms, thus forming a 1D chain structure. A coordinated water molecule behaving as a hydrogen donor joins one of the uncoordinated NO groups of the Nit-Ph-3,5-bIm radical to generate a 2D layer structure. For compounds 3 and 4, the Nit-Ph-3,5-bIm radical ligand is coordinated to three Ln ions via its one NO group and two imidazolyl-N atoms, generating a unique 2D network. Magnetic studies reveal ferromagnetic coupling between the Ln(III) ion and the NO group mediated by hydrogen bonding in compounds 1 and 2. Furthermore, ac magnetic susceptibilities of compound 2 indicate the slow relaxation of magnetization.