Two mononuclear Ru
III complexes of formula
trans-[RuCl
4(Hgua)(dmso)]·2H
2O (
1) and
trans-[RuCl
4(Hgua)(gua)]·3H
2O (
2) [Hgua = protonated guanine (gua), dmso = dimethyl sulfoxide] have been synthesized and characterized magnetostructurally.
1 and
2 crystallize in the monoclinic system with space groups
P2
1/
n and
Pc, respectively. Each Ru
III ion in
1 and
2 is bonded to four chloride ions and one (
1) or two (
2) nitrogen atoms from guanine molecules and one sulfur atom (
1) of a dmso solvent molecule, generating axially compressed octahedral geometries in both cases. In their crystal packing, the Ru
III complexes are connected through an extended network of N-H⋯Cl hydrogen bonds and π⋯Cl intermolecular interactions, forming novel supramolecular structures of this paramagnetic 4d ion. Variable-temperature dc magnetic susceptibility data were obtained from polycrystalline samples of
1 and
2 and their plots show a different magnetic behavior. While
1 is a ferromagnetic compound at low temperature,
2 exhibits a behavior of magnetically isolated mononuclear Ru
III complexes with S = 1/2. The study on ac magnetic susceptibility data reveal slow relaxation of the magnetization, when external dc fields are applied, only for
2. These results highlight the presence of field-induced single-ion magnet (SIM) behavior for this mononuclear guanine-based Ru
III complex.
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