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Article

[MnIII6MnIINaI2], [MnIII3MnIINaI], and [MnIII3] Clusters Derived from Schiff Bases: Syntheses, Structures, and Magnetic Properties †

1
Departament de Química Inorgànica i Orgànica, Secció de Química Inorgànica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona, Spain
2
Institute for Solar Energy Research Hamelin, 31860 Emmerthal, Germany
3
Departament de Mineralogia, Cristal·lografia i Dipòsits Minerals and Unitat de Difracció de R-X, Centre Científic i Tecnològic de la Universitat de Barcelona (CCiTUB), 08028 Barcelona, Spain
4
Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, 08028 Barcelona, Spain
*
Authors to whom correspondence should be addressed.
Miquel and Paco, enormous scientists, incredible people and above all, extraordinary friends.
Magnetochemistry 2024, 10(10), 76; https://doi.org/10.3390/magnetochemistry10100076
Submission received: 6 September 2024 / Revised: 1 October 2024 / Accepted: 3 October 2024 / Published: 10 October 2024

Abstract

:
The reaction of manganese halides with polydentate Schiff bases obtained by the condensation of 3-ethoxysalicylaldehyde and different amino alcohols, resulting in a NO3 set of donors, yielded a series of manganese clusters with {MnIII6MnIINa2}, {MnIII3MnIINa}, and {MnIII3} metallic cores. The influence of the ligand substituents and the halide on the final nuclearity has been studied. Analysis of their static magnetic behaviour confirms the ground states of 19/2 for the {MnIII6MnIINa2} complexes, 7/2 for the {MnIII3MnIINa} clusters, and 12/2 for the triangular {MnIII3} systems, and a weak field induced a slow relaxation of the magnetization for the trinuclear complexes.

1. Introduction

The condensation of a primary amine with aldehydes or ketones yields Schiff bases, which are a class of highly tunable ligands as a function of the R–NH2 and the R–C=O precursors. The design, taking into account shape, chirality, and the number and kind of donors, can induce the selective coordination of only one cation or to generate polynuclear systems with the desired properties after coordination to the adequate cations. The enormous variety of available amines and aldehydes that can be employed as precursors can generate ligands with specific topologies or donor atoms that can link either 3d or 4f cations that demonstrated to be of application in many fields like syntheses, [1] catalysis [2], luminescence [3], or pharmaceuticals [4]. Salicyl and o-vanillin are the most employed aldehyde precursors to reach tetradentate two-pocket ligands with a NO3 set of donors.
The condensation of 3-ethoxysalicylaldehyde with substituted 2-aminoethanol, such 2-phenylglycinol or 2-Amino-1-phenylethanol, gives the polytopic ligands H2L1 and H2L2, respectively, see Scheme 1—top. Each ligand has a NO3 set of donors able to link up to three cations, generating medium and large clusters.
Manganese chemistry with these ligands is dominated by the {MnIII3M’M″} metallic cores that consist of a triangular bipyramid formed by one triangular arrangement of MnIII cations, linked through a μ3-O donor, and two apical M’ and M″ cations, see Scheme 1—bottom. The most common structure consists of pentanuclear {MnIII3MnIINaI} units [5,6,7,8,9,10,11,12] but some {MnIII3MnIICaII} [5,7,10], {MnIII3MnIIMnII} [7,10], or {MnIII3LnIIINaI} [13] cores have also been reported. This pentanuclear unit is very versatile and larger nuclearities have been reported when one of the apical cations is shared by two units, resulting in a nonanuclear {MnIII6MnIINaI2} [8,10,12,14,15] or {MnIII6LnIIINaI2} [16,17] skeleton or decanuclear {MnIII6MnII2NaI2} systems when the MnII cations from two or more units are linked by halides, pseudohalides, or methoxides [9,11,12,18,19,20].
During the last years, we explored the reactivity of a family of related ligands derived from o-vanillin and 2-amino-1-ethanol in MnII,III, [8,9,10,12,17], NiII [21,22], and FeIII chemistry [23], trying to elucidate the effect of the substituents on the C-atoms of amino alcohol. From this previous work, we realized that the size and position of the substituents (Me, Ph, isopropyl) is hardly insignificant and largely induces different shapes and nuclearities in the resulting clusters.
Following our previous work in this field, we have explored the influence of the ethoxo substituent on the salicylaldehyde ring and the position of the phenyl ring on the alcoxo arm of the Schiff base. The reaction of manganese(II) halides with ligands H2L1 and H2L2 yielded a series of clusters with different nuclearities ranging from tri- to nonanuclear with formulas [MnIII6MnIINa2(O)2(L1)6Cl6] (1R), [MnIII6MnIINa2(O)2(L1)6I6] (2Ra, 2Rb), [MnIII3(L2)3(O)(H2O)2(EtOH)]Cl (3), [MnIII3(L2)3(O)(H2O)(MeOH)2]Br (4), and [MnIII3MnIINa(O)(L2)3Cl3(CH3CN)]2[MnIIBr4] (5). Structural characterization shows a variety of metallic cores as function of minor changes on the Schiff bases, such as the rare trinuclear topology found in complexes 34 and the unusual MnIII-I-MnIII linkage found in complexes 2Ra and 2Rb. The study of their magnetic properties shows MnIII–MnIII ferromagnetic interactions and MnII–MnIII antiferromagnetic coupling yielding S ground states between 7/2 and 19/2.

2. Materials and Methods

2.1. Physical Measurements

Magnetic susceptibility measurements were carried out on pressed polycrystalline samples at the Mesures Magnètiques Unit from Scientific and Technological Centers (CCiTUB), Universitat de Barcelona, using a MPMS5 Quantum Design susceptometer (Quantum Design, Pfungstadt, Germany), working in the range 30–300 K under magnetic fields of 0.3 T and under a field of 0.03 T in the 30–2 K range to avoid saturation effects at low temperature. Diamagnetic corrections were estimated from Pascal tables. The fit of the magnetic experimental data were performed with the PHI programme [24]. CHN analyses were performed on vacuum dried samples. Infrared spectra (4000–400 cm–1) were recorded from KBr pellets on a Bruker IFS-125 FT-IR spectrophotometer (Bruker-Spain, Madrid, Spain).

2.2. X-ray Crystallography

Red prism-like specimens of 1R, 2Ra, 2Rb, 3, 4, and 5 were employed for the single crystal X-ray crystallographic analysis. The X-ray intensity data were measured on a D8 Venture system equipped with a multilayer monochromator and a Mo microfocus. The frames were integrated with the Bruker SAINT software package using a narrow-frame algorithm. The structures were solved and refined using the Bruker SHELXTL-2014/7 Software [25]. Crystal data and refinement details for complexes 1 to 5 are summarized in Table S1. Complete crystallographic information can be found in the corresponding CIF files with the following CCDC numbers: 2382107 (for 1R), 2382108 (for 2Ra), 2382109 (for 2Rb), 2382110 (for 3), 2382111 (for 4), and 2382112 (for 5), which contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures accessed on 9 May 2024.

2.3. Synthesis

H2L1 and H2L2 Schiff bases. The ligands were synthesized by the reaction of 3-ethoxysalicylaldehyde with R-2-phenylglycinol or the rac-2-Amino-1-phenylethanol, respectively, following previously reported methods [12]. Methanolic or ethanolic solutions (20 mL) obtained mixing 0.605 g (3.65 mmol) of 3-ethoxysalicylaldehyde and 0.5 g (3.65 mmol) of 2-phenylglycinol or 2-amino-1-phenylethanol were heated at 80° for 30 min in a microwave Anton Parr Monowave-300 furnace and diluted to 100 mL of volume. Fractions of 10 mL (0.0365 mmol) were employed in the syntheses of the corresponding complexes.
[MnIII6MnIINa2(O)2(L1)6Cl6] (1R) was synthesized. A solution of MnCl2·4H2O (0.072 g, 0.365 mmol) and 0.024 g (0.365 mmol) of sodium azide in 15 mL of acetonitrile was mixed with 10 mL of the previously prepared methanolic solution of (R)-H2L1 (0.365 mmol). The resulting yellow mixture was maintained at open air with vigorous stirring and after 10 min, the colour changed to dark brown. After 30 more minutes, the clear solution was layered with diethyl ether and well-formed dark crystals, adequate for X-ray diffraction, and these were collected after three days with a 50% yield (~0.12 g). Because the azide anion was not coordinated, the same product was obtained employing Na(OH) (0.015 g, 0.364 mmol) as the base. CHN for C102H102Cl6Mn7N6Na2O20: calcd. (%): C, 51.58; H, 4.33; N, 3.54. Found: C, 51.0; H, 4.5; N, 3.4.
[MnIII6MnIINa2(O)2(L1)6I6] (2Ra) and [MnIII6MnIINa2(O)2(L1)6I6]·11 CH3CN (2Rb) were synthesized. The synthesis was performed following the same procedure employed in 1R but using 0.112 g (0.364 mmol) of manganese iodide instead the chloride salt. Crystallization of the complex, either from the layers with diethyl ether or slow evaporation, yielded a mixture of well-formed prismatic crystals and bars in a similar amount, and these were manually separated. Structural determination proved the identity of the prismatic crystals (2Ra) and the bars (2b). Yield: 25% for both complexes (~0.10 g). CHN for C102H102I6Mn7N6Na2O20: calcd. (%): C, 41.90; H, 3.52; N, 2.87. Found 2Ra: C, 42.1; H, 3.4; N, 2.9. Found 2Rb: C, 42.3; H, 3.6; N, 2.8.
[MnIII3(L2)3(O)(H2O)2(EtOH)]Cl·0.5 CH3CN·0.25EtOH (3) was synthesized. To a solution of MnCl2·4H2O (0.072 g, 0.365 mmol) in acetonitrile (10 mL) was added Cs(OH) (0.109 g, 0.728 mmol). To the resulting brown suspension, 10 mL of the previously prepared ethanolic solution of rac-H2L (0.364 mmol) was added. The solid was redissolved after some minutes of stirring, resulting a dark brown solution. Crystals adequate for X-ray diffraction were obtained after one week from the slow diffusion of diethyl ether. Yield: 50% (~0.08 g). CHN for C53H61ClMn3N3O13: calcd. (%): C, 55.43; H, 5.35; N, 3.66. Found C, 55.8; H, 5.2; N, 3.5.
[MnIII3(L2)3(O)(H2O)(MeOH)2]Br·CH3CN·MeOH (4) was synthesized. The complex was obtained following the same procedure employed for the synthesis of complex 4, but starting from MnBr2·H2O (0.104 g, 0.364 mmol), Et3N (0.036 g, 0.364 mmol), and a methanolic solution of rac-H2L2 (0.364 mmol). The slow diffusion of diethyl ether yields crystalline complex 4 in a 60% yield (~0.09 g). CHN for C53H61BrMn3N3O13: calcd. (%): C, 53.37; H, 5.15; N, 3.52. Found C, 53.0; H, 5.3; N, 3.7.
[MnIII3MnIINa(O)(L2)3Cl3(CH3CN)]2[MnIIBr4]·0.5 H2O (5) was synthesized. The synthesis of this complex was performed following the same procedure employed for compound 1 starting from MnBr2·4H2O (0.104 g, (0.364 mmol) and 10 mL of the previously prepared ethanolic solution of rac-H2L2. Layering the resulting dark solution with diethyl ether, hexagonal crystals of 5 were collected in a 70% yield (~0.09 g). CHN for C106H108Br10Mn9N8Na2O20: calcd. (%): C, 40.37; H, 3.45; N, 3.55. Found C, 39.9; H, 3.6; N, 3.4.
Representative IR spectra (complexes 1R, 3, and 5) are shown in Figure S1.

3. Results and Discussion

3.1. Description of the Structures

The oxidation states of the manganese cations have been assigned with respect to the shape of the coordination sphere, charge valence of the resulting formulas, and BSV calculations, as shown in Table S2.

3.1.1. Crystal Structure of [MnIII6MnIINa2(O)2(L1)6Cl6] (1R), [MnIII6MnIINa2(O)2(L1)6I6] (2Ra), and [MnIII6MnIINa2(O)2(L1)6I6] (2Rb)

The three structures have a common core consisting in two {Mn3IIIMnIINa} pentanuclear units sharing the MnII cation. Selected bond parameters are reported in Table 1. To avoid repetitive plots, the structure of one of them (2Ra) is shown in Figure 1 as a representative core. The pentanuclear units show a trigonal bipyramid arrangement with the MnIII cations in the equatorial plane with the sodium and the divalent manganese in the apical positions. One μ3-O donor is placed in the centre of the triangular arrangement of MnIII cations. Each pentanuclear fragment is assembled by three L12− ligands linking the MnIII cations with the MnII by means of alcoxo bridges and with the sodium cation by means of phenoxo bridges. The coordination sphere of the MnIII cations is formed by one tridentate L12− ligand linking the alcoxo, phenoxo, and N-iminic donors, as well as the central oxo ligand and two bridging halide atoms. In all cases, the sodium cations are hexacoordinated and placed in the cavity formed by the three bidentate fragments composed by the phenoxo and the ethoxo O donors of the three L12− ligands, resulting in an intermediate polyhedron between the octahedral and trigonal prism.
Complexes 1R and 2Ra possesses a C3 axis that relates the MnIII and the L12− ligands, but the lack of an inversion centre imposed by the chiral ligand (R3 space group) determines that the two pentanuclear subunits are not equivalent and there are small differences in the bond parameters around Mn(1) and Mn(2), as shown in Table 1. Complex 2Rb shows the same core as 1R and 2Ra, but the loss of symmetry (from R3 to P21 space group) has the consequence that despite the bond parameters being very similar to those of 2Ra, all the cations are not equivalent, see Table S3.

3.1.2. Crystal Structure of [MnIII3(L2)3(O)(H2O)2(EtOH)]Cl (3) and [MnIII3(L2)3(O)(H2O)(MeOH)2]Br (4)

The two compounds have a common structure that consist of a triangular arrangement of MnIII cations linked by one μ3-O bridge and three L22− ligands, three solvent molecules, and one halide counterion. The representative molecular structure of complex 3 is shown in Figure 2 and the main bond parameters for the two complexes are listed in Table 2. The μ3-O donor is placed 0.85 Å over the plane defined by the manganese cations and the Mn-O-Mn bond angles lie in the short interval of 101.69(6)°–102.36(6)°. Each L22− ligand acts as tridentate by means of the deprotonated O-donors and the iminic nitrogen, whereas the O-ethoxy atoms remain uncoordinated. The coordination sphere of the MnIII cations is formed by the three donors from one L22− ligand, two O-alcoxo donors, and one solvent molecule (water or alcohol). The L22− ligand contains a chiral C-atom and the main plane of the (R) and (S) isomers are disordered and tilted around 50° with respect to the plane defined by the three cations, resulting a helical arrangement.

3.1.3. Crystal Structure of [MnIII3MnIINa(O)(L2)3Cl3(CH3CN)]2[MnIIBr4] (5)

The structure of 5 consists in two non-equivalent {MnIIIMnIINa} cationic pentanuclear units and one [MnIIBr4]2− counteranion. Bond parameters are similar in both molecules forming the global system (Table 3), which is shown in Figure 3.
The position of the cations and the linkage provided by the L22− ligands in the pentanuclear units are similar to those described for complexes 1R and 2Ra/2Rb. However, in this case, the divalent manganese is tetracoordinated with a coordination sphere composed of three O-alcoxo donors from the corresponding Schiff bases and one acetonitrile ligand, resulting in a NO3 environment. The tetrahedral arrangement around the MnII imposes larger MnII-O-MnIII bond angles than the octahedral environment that takes values in the 109.3(1)°–113.8(1)° range.

3.2. Structural and Synthetic Comments

The chemistry of the manganese halides and the reported ligands is sensitive to the specific halide and the topology of the ligand. The substituents in the vicinity of the O-alkoxo donor induce steric hindrance that becomes the determinant for the final nuclearities of the clusters. In fact, the {Mn6IIIMnII} core becomes not possible for the L22− ligand and the products tend to lower nuclearities such as {Mn3III} or {Mn3IIIMnIINa} found in complexes 35. It is remarkable that the characterization of clusters 3 and 4 had a triangular topology, which was unprecedented for the analogous ligand with a methoxy substituent. Ligand H2L2 is able to give the usual {Mn3IIIMnIINa} core, but probably due to small differences in solubility with respect to the methoxy-related ligand, can generate different cores.
Complexes 2Ra and 2Rb exhibit the unusual MnIII-I linkage that a priori is poorly compatible due to the oxidant character of the trivalent manganese. Most of the reported complexes exhibiting this bond are mononuclear phthalocyanine derivatives [26,27,28,29], in which the MnIII cation is placed in a square pyramidal environment with the iodide donor in the apical elongated site. Also, some iodide–phosphine complexes [30,31] and some other mononuclear complexes with the Schiff base 2,2′-bis(3,5-di-t-butylsalicylaldimino)-6,6′-dimethylbiphenyl [32] show a square pyramidal environment or the macrocyclic cyclam [33] derivative with an elongated octahedral environment, which have been reported.
Due to the apparent instability of the MnIII/I system, this ligand has not been usually employed in manganese cluster chemistry. The only structurally characterized clusters combining MnIII and iodide are those reported by Brechin et al. in some {MnII4MnIII6I4} derivatives of 2-Amino-2-methyl-1,3-propanediol and 2-Amino-2-ethyl-1,3-propanediol [34], as well as one hexanuclear complex derived from ethyl-salicyaldoxime that were the only clusters with MnIII-I bonds, including one μ3-I bridge [35]. It is remarkable that complexes 2Ra and 2Rb become the second clusters characterized with this kind of bond.
The configuration of the complexes built from chiral ligands is determined by the ligand chirality, which can be transferred to the coordination sphere of the cations to the complex or to the crystal. This “predetermined chirality” is usually propagated in an opposite sense by the corresponding enantiomeric ligands, resulting in mirror image clusters or networks for each enantiomer [36,37]. Thus, starting from the racemic H2L2 ligand, it could be expected that complexes 3, 4, or 5, containing three ligands in their structures, must show the RRR and SSS arrangements related by inversion centres in the network. However, as was summarized in a previous work, this family of clusters often exhibits an unexpected mixing of enantiomers in the same molecule [12].
Complex 3 shows a complete disorder for the three ligands and complex 4 shows a helical arrangement of the three Schiff bases with respect to the plane defined by the manganese cations and a mixture of enantiomers, with one R enantiomer and two disordered R/S enantiomers, or one S enantiomer and two disordered R/S ligands, see Figure 4. Complex 5 exhibits an unusual mixture of enantiomers in the same molecule, with one of the molecules containing two R enantiomers and one R/S disordered ligand, and the molecule related by the inversion centre in the network contains two S enantiomers and one disordered R/S ligand, as shown in Figure 4.

3.3. Magnetic Properties

Susceptibility measurements were performed in the 2–300 K temperature range on powdered pressed samples for complexes 1R, 2Ra, 4, and 5. Complexes 1R and 2Ra show χMT values of 17.49 and 18.48 cm3·mol−1·K at room temperature, lower than the expected values for six MnIII and one MnII isolated cations (22.375 cm3·mol−1·K) that decrease slightly down to a minimum of 16.86 cm3·mol−1·K at 150 K and 17.68 cm3·mol−1·K at 110 K for 1R and 2Ra, respectively. Below this minimum, the χMT values increase up to a maximum of 38.42 cm3·mol−1·K placed at 13 K for complex 1 and 37.24 cm3·mol−1·K at 10 K for complex 2Ra with a moderate decrease at lower temperatures, see Figure 5. The shape of the plot with a well-defined minimum is the signature of ferrimagnetic response for these two complexes.
Complex 4 shows the χMT value of 8.24 cm3·mol−1·K at room temperature, slightly lower than the expected value for three isolated MnIII cations of 9.00 cm3·mol−1·K. On cooling, the χMT value increases slightly up to a maximum value of 10.37 cm3·mol−1·K at 5.5 K, followed by a weak decrease at low temperature, suggesting a very weak ferromagnetic interaction. Finally, the room temperature χMT value for complex 5 is 29.97 cm3·mol−1·K, very close to the expected value for six MnIII and three MnII isolated cations of 31.125 cm3·mol−1·K. The χMT value increases up to 31.62 cm3·mol−1·K at 13 K and a further decrease below this temperature appears to be indicative of the presence of ferrimagnetic interactions, as shown in Figure 5.
The susceptibility plots for complexes 1R and 2Ra were fitted according the two-J Hamiltonian derived from Scheme 2.
H = −2J1(S1·S2 + S1·S3 + S2·S3 + S4·S5 + S4·S6 + S5·S6) − 2J2(S1·S7 + S2·S7 + S3·S7 + S4·S7 + S5·S7 + S6·S7)
This results in the best fit parameters J1 = 1.73(8) cm−1, J2 = −3.81(6) cm−1, and g = 1.859 (2) for complex 1 and J1 = 1.47(6) cm−1, J2 = −2.30(2) cm−1, and g = 1.867(3) for complex 2Ra. Magnetization measurements give unsaturated values of 14.70 and 16.50 Nμβ for complexes 1R and 2Ra, respectively, slightly lower than the expected spin-only value of 17.7 Nμβ, assuming a g value of 1.86 obtained in the susceptibility fit. The deviation should be attributed to weak zero-field splitting of the MnIII cations that has not been included in the fits due to the large size of the matrix, out of the scope of usual fits.
The fit of the experimental data for complex 4 according the spin-only Hamiltonian derived from Scheme 2 can be determined as follows:
H = −2J1(S1·S2 + S1·S3 + S2·S3)
This does not reproduce adequately the weak susceptibility increase and thus, a Dion term was added. The best fit values were J1 = 0.19(1) cm−1, Dion = 2.04(8), and g = 1.974(6). The magnetization measurement performed at 2 K reaches an unsaturated value of 11.45 Nμβ, close to the expected value of 12 Nμβ.
The susceptibility data for complex 5 were fitted, assuming the same set of interactions for the two non-equivalent units with the two-J Hamiltonian derived from Scheme 2.
H = 2 × (−2J1(S1·S2 + S1·S3 + S2·S3) − 2J2(S1·S4 + S2·S4 + S3·S4))
This includes the interactions inside the MnIII triangles (J1) and the interaction between the MnII···MnIII inside the two tetranuclear units. The contribution of one isolated S = 5/2 from the [MnBr4]2− isolated counteranion, assumed as fully isotropic according to its high S = 5/2 spin (6A1 term), has been taken into account for the total χMT value. The best fit parameters were J1 = 2.38(2) cm−1, J2 = −1.32(1) cm−1, and g = 1.939(1), implying a S = 7/2 spin ground state for each {NaMnIIMnIII3} cluster. Isothermal magnetization measurement at 2 K reaches a value of 18.54 Nμβ under the maximum applied field, close to the expected 19 Nμβ value, confirming the S = 7/2 ground state for the two {MnIII3MnIINaI} units, see Figure 5—right.
The ac response of complexes 1R, 2Ra, 4, and 5 was tested under different external fields (0–0.5 T) and a constant frequency of 1000 Hz and no out-of-phase signals were observed with the exception of weak tails in the χ″M(H) plots for triangular complex 3, Figure S2, which was shown to be too weak for a further analysis. The lack of ac response despite the relatively high S ground states of 19/2 (1R, 2Ra, 2Rb), 12/2 (3, 4), and 7/2 (5) should be attributed to the unfavourable arrangement of the easy axis of the MnIII cations, which show a triangular arrangement that results in a low or negligible total anisotropy for the whole molecules, see Figure 6.

4. Conclusions

Depending on the position of the substituents on the amino alcohol fragment of the Schiff bases obtained by condensation with 3-ethoxysalicylaldehyde with the 1 or 2-phenyl derivatives of 2-amino-1-ethanol, a series of clusters with {MnIII6MnIINa2}, {MnIII3MnIINa}, and {MnIII3} nuclearity have been characterized. The magnetic response of these systems yields large S ground states comprised between 7/2 and 19/2 as a consequence of the MnIII–MnIII ferromagnetic and MnII–MnIII antiferromagnetic coupling. The reported systems confirm that the mix of ligands with different (R)/(S) configurations in the same molecule instead of the expected separation of enantiomers is a common feature in this kind of cage with an odd number of chiral ligands.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/magnetochemistry10100076/s1, Table S1: Crystallographic data for compounds 15; Table S2: BVS calculation for the manganese cations; Table S3: Selected bond distances (Å) and angles (deg.) for compound 2Rb; Figure S1: Infrared spectra for complexes 1R, 3 and 5; Figure S2: AC susceptibility measurements vs. field (1000 Hz) for 4.

Author Contributions

The manuscript was prepared with the contributions of all authors. They specifically contributed as follows: J.L.; synthesis, characterization, performance of the magnetic measurements, and the analysis of the results of magnetic studies. M.F.-B.; single-crystal X-ray diffraction collection and refinement of the crystal structures. J.M. and A.E.; conceptualization and methodology, writing—original draft preparation, and writing—review and editing. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Spanish Ministry of Science and Innovation (MICINN) Project PID2023-146166NB-I00.

Data Availability Statement

The data presented in this study are available in this article or the Supplementary Materials.

Conflicts of Interest

The authors declare no conflicts of interest.

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Scheme 1. (Top) Molecular structure of H2L1 and H2L2 ligands employed in this work. (Bottom) coordination modes found in complexes 1R, 2Ra,b, and 5 (left) or 3 and 4 (right) and the topologies of the corresponding clusters. Asterisks denote chiral C-atoms.
Scheme 1. (Top) Molecular structure of H2L1 and H2L2 ligands employed in this work. (Bottom) coordination modes found in complexes 1R, 2Ra,b, and 5 (left) or 3 and 4 (right) and the topologies of the corresponding clusters. Asterisks denote chiral C-atoms.
Magnetochemistry 10 00076 sch001
Figure 1. Left: view of the molecular structure of the nonanuclear {MnIII6MnIINa2} complex 2Ra. Right: labelled plot of the core of complex 2Ra. Atom numbering is the same for the isostructural chloro complex 1R.
Figure 1. Left: view of the molecular structure of the nonanuclear {MnIII6MnIINa2} complex 2Ra. Right: labelled plot of the core of complex 2Ra. Atom numbering is the same for the isostructural chloro complex 1R.
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Figure 2. Partially labelled plot of the molecular structure of complex 3. The C-atom in the vicinity of the O-alcoxo donors is disordered and corresponds to the (R) or (S) enantiomer of the ligand. Structure and atom numbering is the same for complex 4.
Figure 2. Partially labelled plot of the molecular structure of complex 3. The C-atom in the vicinity of the O-alcoxo donors is disordered and corresponds to the (R) or (S) enantiomer of the ligand. Structure and atom numbering is the same for complex 4.
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Figure 3. Left: view of the molecular structure of one pentanuclear {MnIIIMnIINa} unit of complex 5. Right: labelled plot of the core of the pentanuclear complex.
Figure 3. Left: view of the molecular structure of one pentanuclear {MnIIIMnIINa} unit of complex 5. Right: labelled plot of the core of the pentanuclear complex.
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Figure 4. Arrangement of the enantiomers of the Schiff base for complexes 3 (top, left) and 5 (right). Colour key, Firebrick. Disordered R/S enantiomers: S-ligand, green; R-ligand, bronze. Left–bottom, space-fill plot of the two helicities of complex 4 (all ligands are disordered).
Figure 4. Arrangement of the enantiomers of the Schiff base for complexes 3 (top, left) and 5 (right). Colour key, Firebrick. Disordered R/S enantiomers: S-ligand, green; R-ligand, bronze. Left–bottom, space-fill plot of the two helicities of complex 4 (all ligands are disordered).
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Figure 5. Left: χMT plots in terms of temperature for complexes 1R, 2Ra, 4, and 5 (solid lines show the best fit of the data). Right: isothermal magnetization at 2 K for each compound.
Figure 5. Left: χMT plots in terms of temperature for complexes 1R, 2Ra, 4, and 5 (solid lines show the best fit of the data). Right: isothermal magnetization at 2 K for each compound.
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Scheme 2. Coupling scheme for the different topologies of complexes 1R, 2Ra (left), 4 (centre), and 5 (right). Red lines indicate the interactions involving the MnII cation.
Scheme 2. Coupling scheme for the different topologies of complexes 1R, 2Ra (left), 4 (centre), and 5 (right). Red lines indicate the interactions involving the MnII cation.
Magnetochemistry 10 00076 sch002
Figure 6. Core of the three topologies for complexes 15, emphasizing the triangular arrangement of the elongated axis of the MnIII cations (bold bonds).
Figure 6. Core of the three topologies for complexes 15, emphasizing the triangular arrangement of the elongated axis of the MnIII cations (bold bonds).
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Table 1. Main bond distances (Å) and angles (deg.) for complexes 1R and 2Ra.
Table 1. Main bond distances (Å) and angles (deg.) for complexes 1R and 2Ra.
1R2Ra
Mn1–O21.900(3)1.880(4)
Mn1–O31.899(3)1.903(3)
Mn1–O71.8810(8)1.8780(9)
Mn1–X12.595(1)2.942(1)
Mn1′–X12.701(1)3.021(1)
Mn2–O51.914(3)1.891(5)
Mn2–O61.886(3)1.900(4)
Mn2–O81.8761(9)1.872(1)
Mn2–X22.637(1)3.023(1)
Mn2′–X22.735(1)3.105(1)
Mn3–O32.201(3)2.202(3)
Mn3–O62.196(3)2.193(4)
Mn1–O7–Mn1′119.2(5)119.17(5)
Mn2–O8–Mn2′118.82(6)119.04(7)
Mn1–O3–Mn3122.9(2)123.8(2)
Mn2–O6–Mn3125.4(2)126.5(2)
Mn1–X1–Mn1′75.54(4)65.79(3)
Mn2–X2–Mn2′73.89(4)63.51(3)
Table 2. Main bond distances (Å) and angles (deg.) for the triangular complexes 3 and 4.
Table 2. Main bond distances (Å) and angles (deg.) for the triangular complexes 3 and 4.
34
Mn1–O32.255(2)2.227(1)
Mn1–O51.902(2)1.911(1)
Mn1–O61.882(1)1.877(1)
Mn1–O101.926(1)1.929(1)
Mn1–O112.293(3)2.278(2)
Mn1–N11.987(2)1.979(2)
Mn2–O21.910(2)1.908(1)
Mn2–O2w2.270(2)2.316(1)
Mn2–O31.889(1)1.868(1)
Mn2–O92.234(2)2.240(1)
Mn2–O101.921(1)1.915(1)
Mn2–N21.969(2)1.978(1)
Mn3–O3w2.266(2)2.279(2)
Mn3–O62.253(2)2.231(1)
Mn3–O81.902(2)1.890(1)
Mn3–O91.864(2)1.878(1)
Mn3–O101.929(1)1.921(1)
Mn3–N31.993(2)1.978(2)
Mn1–O3–Mn292.22(6)93.38(5)
Mn1-O6-Mn392.62(6)92.83(5)
Mn2–O9–Mn393.14(6)92.29(5)
Mn1–O10–Mn2102.36(6)102.13(6)
Mn1–O10–Mn3102.24(6)101.69(6)
Mn2–O10–Mn3101.74(6)101.96(5)
Table 3. Main bond distances (Å) and angles (deg.) for the two non-equivalent clusters present in the unit cell of compound 5.
Table 3. Main bond distances (Å) and angles (deg.) for the two non-equivalent clusters present in the unit cell of compound 5.
5A5B
Mn1–O11.914(2)1.931(3)
Mn1–O21.867(3)1.883(3)
Mn1–O101.920(2)1.903(2)
Mn1–Br12.7608(7)2.7261(7)
Mn1–Br32.7725(7)2.7938(7)
Mn3–O71.921(2)1.920(3)
Mn3–O81.887(2)1.889(3)
Mn3–O101.895(2)1.890(2)
Mn3–Br12.8260(6)2.8403(7)
Mn3–Br22.7777(7)2.7730(7)
Mn4–O41.903(2)1.906(3)
Mn4–O51.890(2)1.889(3)
Mn4–O101.897(2)1.887(3)
Mn4–Br22.9163(6)2.7651(7)
Mn4–Br32.7785(6)2.8431(7)
Mn2–O12.061(2)2.036(3)
Mn2–O42.052(2)2.050(3)
Mn2–O72.054(2)2.064(3)
Mn2–N42.135(4)2.113(5)
Mn1–O10–Mn3120.0(1)119.8(1)
Mn1–O10–Mn4119.9(1)120.0(1)
Mn3–O10–Mn4120.1(1)119.9(1)
Mn2–O1–Mn1109.3(1)113.8(1)
Mn2–O7–Mn3110.3(1)112.7(1)
Mn2–O4–Mn4111.8(1)113.4(2)
Mn1–Br1–Mn372.50(2)72.22(3)
Mn1–Br3–Mn473.09(2)71.21(3)
Mn3–Br2–Mn470.41(2)72.36(3)
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Löhr, J.; Font-Bardia, M.; Mayans, J.; Escuer, A. [MnIII6MnIINaI2], [MnIII3MnIINaI], and [MnIII3] Clusters Derived from Schiff Bases: Syntheses, Structures, and Magnetic Properties. Magnetochemistry 2024, 10, 76. https://doi.org/10.3390/magnetochemistry10100076

AMA Style

Löhr J, Font-Bardia M, Mayans J, Escuer A. [MnIII6MnIINaI2], [MnIII3MnIINaI], and [MnIII3] Clusters Derived from Schiff Bases: Syntheses, Structures, and Magnetic Properties. Magnetochemistry. 2024; 10(10):76. https://doi.org/10.3390/magnetochemistry10100076

Chicago/Turabian Style

Löhr, Johannes, Mercè Font-Bardia, Júlia Mayans, and Albert Escuer. 2024. "[MnIII6MnIINaI2], [MnIII3MnIINaI], and [MnIII3] Clusters Derived from Schiff Bases: Syntheses, Structures, and Magnetic Properties" Magnetochemistry 10, no. 10: 76. https://doi.org/10.3390/magnetochemistry10100076

APA Style

Löhr, J., Font-Bardia, M., Mayans, J., & Escuer, A. (2024). [MnIII6MnIINaI2], [MnIII3MnIINaI], and [MnIII3] Clusters Derived from Schiff Bases: Syntheses, Structures, and Magnetic Properties. Magnetochemistry, 10(10), 76. https://doi.org/10.3390/magnetochemistry10100076

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