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. 2022 Jun 30;27(13):4211.
doi: 10.3390/molecules27134211.

Mixed-Valent Trinuclear CoIII-CoII-CoIII Complex with 1,3-Bis(5-chlorosalicylideneamino)-2-propanol

Masahiro Mikuriya  1 , Yuko Naka  1 , Ayumi Inaoka  1 , Mika Okayama  1 , Daisuke Yoshioka  1 , Hiroshi Sakiyama  2 , Makoto Handa  3 , Motohiro Tsuboi  1
Affiliations

Mixed-Valent Trinuclear CoIII-CoII-CoIII Complex with 1,3-Bis(5-chlorosalicylideneamino)-2-propanol

Masahiro Mikuriya et al. Molecules. .

Abstract

A mixed-valent trinuclear complex with 1,3-bis(5-chlorosalicylideneamino)-2-propanol (H3clsalpr) was synthesized, and the crystal structure was determined by the single-crystal X-ray diffraction method at 90 K. The molecule is a trinuclear CoIII-CoII-CoIII complex with octahedral geometries, having a tetradentate chelate of the Schiff-base ligand, bridging acetate, monodentate acetate coordination to each terminal Co3+ ion and four bridging phenoxido-oxygen of two Schiff-base ligands, and two bridging acetate-oxygen atoms for the central Co2+ ion. The electronic spectral feature is consistent with the mixed valent CoIII-CoII-CoIII. Variable-temperature magnetic susceptibility data could be analyzed by consideration of the axial distortion of the central Co2+ ion with the parameters Δ = -254 cm-1, λ = -58 cm-1, κ = 0.93, tip = 0.00436 cm3 mol-1, θ = -0.469 K, gz = 6.90, and gx = 2.64, in accordance with a large anisotropy. The cyclic voltammogram showed an irreversible reduction wave at approximately -1.2 V·vs. Fc/Fc+, assignable to the reduction of the terminal Co3+ ions.

Keywords: Schiff-base ligand; cobalt complex; mixed-valent complex; trinuclear complex.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schiff-base ligand 1,3-bis(5-chlorosalicylideneamino)-2-propanol as (a) pentadentate dinucleating ligand and (b) tetradentate mononucleating ligand.
Figure 2
Figure 2
(a–e) Trinuclear cobalt complexes with a linear array of CoIII-CoII-CoIII or CoII-CoII-CoII.
Figure 3
Figure 3
Synthetic scheme of the trinuclear cobalt complex [Co3(Hclsalpr)2(CH3COO)4].
Figure 4
Figure 4
Diffuse reflectance spectra of [Co3(Hclsalpr)2(CH3COO)4] (green line).
Figure 5
Figure 5
The ORTEP view of the molecular structure of [Co3(Hclsalpr)2(CH3COO)4] with thermal ellipsoids (50% probability level). The hydrogen atoms have been omitted for clarity.
Figure 6
Figure 6
Packing diagram of [Co3(Hclsalpr)2(CH3COO)4]·8THF. The hydrogen atoms have been omitted for clarity.
Figure 7
Figure 7
Variable temperature of χMT for [Co3(Hclsalpr)2(CH3COO)4] (blue circle). The solid lines were calculated and drawn with the parameter values described in the text.
Figure 8
Figure 8
Variable temperature of χMT for [Co3(Hsalpr)2(CH3COO)4] (blue circle) from the data in [40]. The solid lines were calculated and drawn with the parameter values described in the text.
Figure 9
Figure 9
Cyclic voltammograms of [Co3(Hclsalpr)2(CH3COO)4] in THF ([complex] = 1 × 10–3 M; [TBAP] = 0.2 M; scan rate = 100 mV s−1).
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