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. 2023 Oct 22;28(20):7213.
doi: 10.3390/molecules28207213.

Enantiomeric Complexes Based on Ruthenium(III) and 2,2'-Biimidazole: X-ray Structure and Magnetic Properties

Marta Orts-Arroyo  1 , Joel Monfort  1 , Nicolás Moliner  1 , José Martínez-Lillo  1
Affiliations

Enantiomeric Complexes Based on Ruthenium(III) and 2,2'-Biimidazole: X-ray Structure and Magnetic Properties

Marta Orts-Arroyo et al. Molecules. .

Abstract

We have prepared and characterized two Ru(III) compounds based on the 2,2'-biimidazole (H2biim) ligand, namely, a single complex of formula cis-[RuCl2(H2biim)2]Cl·4H2O (1) and a racemic mixture of formula {cis-[RuCl2(H2biim)2]Cl}2·4H2O (2), which contains 50% of Ru(III) complex 1. Both compounds crystallize in the monoclinic system with space groups C2 and P21 for 1 and 2, respectively. These complexes exhibit the metal ion bonded to four nitrogen atoms from two H2biim molecules and two chloride ions, which balance part of the positive charges in a distorted octahedral geometry. Significant differences are observed in their crystal packing, which leads to the observation of differences in their respective magnetic behaviors. Despite having imidazole rings in both compounds, π-π stacking interactions occur only in the crystal structure of 2, and the shortest intermolecular Ru···Ru separation in 2 is consequently shorter than that in 1. Variable-temperature dc magnetic susceptibility measurements performed on polycrystalline samples of 1 and 2 reveal different magnetic behaviors at low temperatures: while 1 behaves pretty much as a magnetically isolated mononuclear Ru(III) complex with S = 1/2, 2 exhibits the behavior of an antiferromagnetically coupled system with S = 0 and a maximum in the magnetic susceptibility curve at approximately 3.0 K.

Keywords: 2,2′-biimidazole; crystal explorer; crystal structures; enantiomers; magnetic properties; ruthenium.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) View of the cationic Ru(III) complex in compound 1; (b) view of one of the two enantiomeric units in compound 2. H atoms, chloride counter-anions and H2O molecules have been omitted for clarity. Thermal ellipsoids are depicted at the 50% probability level.
Figure 2
Figure 2
Detail of the one-dimensional motif generated by H-bonds (dashed red lines) connecting [RuCl2(H2biim)2]+ cations and chloride anions in 1.
Figure 3
Figure 3
View along the crystallographic [011] direction of the one-dimensional motif generated by offset π–π stacking interactions in 2.
Figure 4
Figure 4
(a) View along the crystallographic [110] direction of the two-dimensional motif generated by H-bonds involving N–H groups and chloride ions (dashed red lines) and H2O molecules (only selected ones) and chloride ions (dashed blue lines) in 1. (b) View along the crystallographic c axis of the two-dimensional arrangement of Ru(III) complexes connected through π–π stacking interactions (dashed red lines) and C-H···Cl interactions (dashed green lines) in 2.
Figure 5
Figure 5
Hirshfeld surfaces mapped through dnorm function for the two enantiomeric units of compound 2.
Figure 6
Figure 6
(a) The χMT versus T curve for compound 1. The inset displaying the χM versus T curve for 1. (b) The χMT versus T curve for compound 2. The inset displaying the χM versus T curve for 2. The solid red line is the best fit, whereas the solid black line is a guide for the eye.
Figure 7
Figure 7
Plot of M versus H measured at several temperatures (2–10 K) for compound 1. The solid red lines represent the best fit.
See this image and copyright information in PMC

References

    1. Higgins S. Regarding ruthenium. Nat. Chem. 2010;2:1100. doi: 10.1038/nchem.917. - DOI - PubMed
    1. Mulcahy S.P., Gründler K., Frias C., Wagner L., Prokop A., Meggers E. Discovery of a strongly apoptotic ruthenium complex through combinatorial coordination chemistry. Dalton Trans. 2010;39:8177–8182. doi: 10.1039/c0dt00034e. - DOI - PubMed
    1. Yamamoto Y., Tamaki Y., Yui T., Koike K., Ishitani O. New Light-Harvesting Molecular Systems Constructed with a Ru(II) Complex and a Linear-Shaped Re(I) Oligomer. J. Am. Chem. Soc. 2010;132:11743–11752. doi: 10.1021/ja104601b. - DOI - PubMed
    1. Duan L., Bozoglian F., Mandal S., Stewart B., Privalov T., Llobet A., Sun L. A molecular ruthenium catalyst with water-oxidation activity comparable to that of photosystem II. Nat. Chem. 2012;4:418–423. doi: 10.1038/nchem.1301. - DOI - PubMed
    1. Bruneau C., Achard M. Allylic ruthenium(IV) complexes in catalysis. Coord. Chem. Rev. 2012;256:525–536. doi: 10.1016/j.ccr.2011.10.018. - DOI