Crystal structure and cryomagnetic study of a mononuclear erbium(III) ox­am­ate inclusion com­plex

Araujo Junior, C.R.; Oliveira, W.X.C.; Pinheiro, C.B.; Pedroso, E.F.; Nunes, W.C.; Almeida, A.A. de; Knobel, M.; Julve, M.; Pereira, C.L.M.

doi:10.1107/S2053229624005977

crystallography in latin america

STRUCTURAL
CHEMISTRY

ISSN: 2053-2296

Volume 80| Part 8| August 2024| Pages 349-356

https://doi.org/10.1107/S2053229624005977

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Crystal structure and cryomagnetic study of a mononuclear erbium(III) oxamate inclusion complex

Cleber R. Araujo Junior,^a Willian X. C. Oliveira,^a Carlos B. Pinheiro,^b Emerson F. Pedroso,^c Wallace C. Nunes,^c Adriele A. de Almeida,^d Marcelo Knobel,^d Miguel Julve ^e and Cynthia L. M. Pereira ^a ^*

^aDepartamento de Química, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, MG, 31270-901, Brazil, ^bDepartamento de Física, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, MG, 31270-901, Brazil, ^cInstituto de Física, Universidade Federal Fluminense, Niterói, RJ, 24210-346, Brazil, ^dInstituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP, 13083-859, Brazil, and ^eDepartament de Química Inorgànica, Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain
^*Correspondence e-mail: cynthialopes@ufmg.br

Edited by R. Diniz, Universidade Federal de Minas Gerais, Brazil (Received 30 May 2024; accepted 19 June 2024; online 10 July 2024)

This article is part of the collection Crystallography in Latin America: a vibrant community.

The synthesis, crystal structure and magnetic properties of an oxamate-containing erbium(III) complex, namely, tetrabutylammonium aqua[N-(2,4,6-trimethylphenyl)oxamato]erbium(III)–dimethyl sulfoxide–water (1/3/1.5), (C₁₆H₃₆N)[Er(C₁₁H₁₂NO₃)₄(H₂O)]·3C₂H₆OS·1.5H₂O or n-Bu₄N[Er(Htmpa)₄(H₂O)]·3DMSO·1.5H₂O (1), are reported. The crystal structure of 1 reveals the occurrence of an erbium(III) ion, which is surrounded by four N-phenyl-substituted oxamate ligands and one water molecule in a nine-coordinated environment, together with one tetrabutylammonium cation acting as a counter-ion, and one water and three dimethyl sulfoxide (DMSO) molecules of crystallization. Variable-temperature static (dc) and dynamic (ac) magnetic measurements were carried out for this mononuclear complex, revealing that it behaves as a field-induced single-ion magnet (SIM) below 5.0 K.

Keywords: erbium(III); oxamate; crystal structure; magnetic properties; single-ion magnet; spin qubit candidate; cryomagnetic; SIM.

CCDC reference: 2358484

1. Introduction

The search for derivatives with paramagnetic centres envisaging technologies based on quantum effects has attracted the attention of several research teams worldwide (Marin et al., 2021 ). These compounds, known as Single-Molecule Magnets (SMMs) or Single-Ion Magnets (SIMs), which are polynuclear or mononuclear compounds that exhibit relaxation of the magnetization phenomena (a requirement to build spin qubit entities), are produced using various potential organic spacers, like cyanide, carboxylate, oxalate and functionalized oxamate ligands (Ferrando-Soria et al., 2017 ). The assembling of these ligands, together with the type of metal ions, d- or f-block metals of the periodic table, plays a crucial role in producing interesting SMMs or SIMs because these polyatomic ligands are able to mediate important magnetic interactions between the paramagnetic ions linked by them.

Spin qubits are the basic units of quantum information that use the spin of subatomic particles, such as electrons or nuclei, to represent and process quantum data. Therefore, SMMs and SIMs, as magnetic entities, can be employed to build spin qubits to be integrated into potential technologies, such as quantum computing (Escalera-Moreno et al., 2018 ).

Increasing efforts have been devoted to investigating SMMs and SIMs containing rare-earth elements, because these ions typically have practical functional applications with high values of spin-orbit coupling compared to first-row transition elements (Chen et al., 2023 ; Dey et al., 2018 ). Therefore, lanthanide ions may produce performant magnetic ions and magnetic molecules, with higher blocking temperatures, compatible with technological applications (Guo et al., 2018 ). Since the discovery that oxamate complexes are good candidates for building spin qubits (Wang et al., 2023 ), our knowledge of the coordination chemistry of functionalized oxamates (da Cunha et al., 2019 , 2020 ; Vaz et al., 2020 , 2022 ; Dul et al., 2010 ; Fortea-Pérez et al., 2013 ) moved us to focus on the preparation and magneto-structural characterization of oxamate-containing lanthanide complexes, considering their potential use in spintronics.

In this article, we present the synthesis, crystal structure and magnetic properties of a field-induced SIM of formula n-Bu₄N[Er(Htmpa)₄(H₂O)]·3DMSO·1.5H₂O (1), where H₂tmpa is N-(2,4,6-trimethylphenyl)oxamic acid, n-Bu₄N⁺ is tetra-n-butylammonium and DMSO is dimethyl sulfoxide. This organic ligand was described previously in the synthesis of oxamate-bridged heterobimetallic cobalt(II)–copper(II) chains (Pardo et al., 2004 ). It is important to outline that the Htmpa⁻ ligand presents three methyl groups acting as donors of electronic density at the aromatic ring, in contrast to a previous report on the mononuclear dysprosium(III) oxamate complex Me₄N[Dy(HL)₄]·2CH₃CN, [H₂L is N-(2,6-dimethylphenyl)oxamic acid and Me₄N⁺ is tetramethylammonium], where the oxamate ligand has two methyl groups on the arene ring, the dysprosium ion being eight-coordinate. Also, a series of mononuclear lanthanide(III) oxamate complexes (Ln³⁺ = Eu³⁺, Gd³⁺, Dy³⁺, Tb³⁺, Nd³⁺ and Ho³⁺), incorporating withdrawing halogen and hydroxo substituents, were reported by our group (Vaz et al., 2020, 2022; da Cunha et al., 2019) and displayed nine-coordinated lanthanide ions. The molecular structure of the proligand EtHtmpa, namely, ethyl N-(2,4,6-trimethylphenyl)oxamate, used in this study is shown in Scheme 1.

2. Experimental

2.1. Materials and methods

All chemicals and solvents were of analytical grade and were used without further purification. The ethyl ester EtHtmpa proligand used in this work was synthesized as described previously (Pardo et al., 2004). Elemental analyses were carried out with a PerkinElmer 2400 analyzer. IR spectra were recorded on KBr pellets in the 4000–400 cm⁻¹ range on a PerkinElmer 882 spectrophotometer. The thermal study (TG/DTA, thermogravimetric/differential thermal analysis) was done with a DTG-60H Shimadzu instrument using 3.196 mg (0.0021 mmol) of the complex placed in an alumina crucible. The solid sample was heated at 10 K min⁻¹ from room temperature to 873 K under a dinitrogen atmosphere (flow rate = 50 ml min⁻¹). Samples of 1 suitable for single-crystal X-ray diffraction (SCXRD) data collection were investigated in a Rigaku Synergy diffractometer using Cu Kα radiation (λ = 1.54184 Å) at 220 K. The powder X-ray diffraction pattern (PXRD) of 1 was taken on an Empyrean (Panalytical) using Cu Kα₁ radiation (λ = 1.54056 Å). The simulated PXRD patterns was generated with Mercury software (Macrae et al., 2020 ) using the crystal data obtained from the SCXRD CIF file. Variable-temperature static (dc) magnetic susceptibility and variable-field magnetization measurements were carried out using a Quantum Design SQUID magnetometer model MPMS-XL-5. Variable-temperature dynamic (ac) magnetic susceptibility measurements were performed using a Model Quantum Design PPMS-9 operating with a small amplitude ac field (5 Oe) and scanning within the frequency range 0.1–10 kHz at different applied dc magnetic fields. The dc and ac magnetic measurements were performed on powdered polycrystalline samples, previously placed in gelatine capsules with mineral oil to prevent crystal movement. Corrections for the diamagnetism of the sample and for the sample holder were also applied.

2.2. Synthesis of 1

To an aqueous mixture (30 ml) containing the EtHtmpa proligand (480 mg, 2.04 mmol) was added dropwise tetrabutylammonium hydroxide (40 wt%, 1.33 ml, 2.05 mmol) under continuous stirring and the resulting mixture was heated at 60 °C for 30 min. The system was cooled to room temperature and DMSO (42 ml) was added dropwise. An aqueous solution (6 ml) of ErCl₃·6H₂O (193 mg, 0.50 mmol) was added slowly to the mixture under continuous stirring. The resulting solution was stirred, heated at 60 °C for 15 min and placed in an open Petri dish. Light-pink rectangular crystals of 1 suitable for X-ray structure analysis were obtained after 24 h in an open air atmosphere at room temperature after slow evaporation (yield: 486 mg, 65%). Elemental analysis for C₆₆H₁₀₆ErN₅O_17.5S₃ expected/calculated (%): C 50.67/52.67, 7.07/7.10, N 4.52/4.65. Selected IR peaks (KBr/cm⁻¹): 3418 [ν(O—H)], 3222 [ν(N—H)], 3968, 2918, 2875 [ν(C—H)], 1669, 1641 [ν(C=O)], 1535, 1487 [ν(C=C)], 1026 [ν(S=O)] 852, 767 [γ(C—H)].

2.3. Single-crystal X-ray data collection and refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. Data integration and scaling of the reflections for the SCXRD experiments were done through the CrysAlis PRO suite (Rigaku OD, 2022 $[Rigaku OD (2022). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ). The final unit-cell parameters were based on the fitting of all reflection positions. Analytical absorption correction and space group identification were performed using the CrysAlis PRO suite. The structure of 1 was solved by direct methods using the SUPERFLIP program (Palatinus & Chapuis, 2007 ). The positions of all atoms could be unambiguously assigned on consecutive difference Fourier maps. All but the H atoms and crystallization solvent molecules trapped in voids were refined with anisotropic atomic displacement parameters. The DMSO solvent molecule inside the void presented two possible positions and was thus treated as disordered with double positions for all atoms with refined occupancies combined into one DMSO molecule. Also, the water molecule can be found in the void with partial occupancy. Its occupancy was refined and converged to 0.54, then fixed at 0.5 for chemical purposes, meaning two DMSO and one water molecule form each void content (formed by two erbium complexes). The H atoms of this water molecule could not be located in difference maps and due to proximity to DMSO molecules inside the voids they were not added. The SQUEEZE routine (Spek, 2015 ) in PLATON (Spek, 2020 ) was applied to remove the contents of the void finding, per unit cell, i.e. 757 Å³ of accessible volume containing 187 electrons or ca 47 electrons distributed in approximately 190 Å³ per complex. This is compatible with one DMSO molecule (42 electrons and 117.98 Å³) and a half water molecule (5 electrons and 14.95 Å³). The H atoms were located in difference maps and included as fixed contributions according to the riding model (Johnson, 1970 ), with C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C) for the aromatic C atoms, C—H = 0.97 Å and U_iso(H) = 1.5U_eq(C) for methyl groups, C—H = 0.97 Å and U_iso(H) = 1.2U_eq(C) for methylene C atoms, and N—H = 0.86 Å and U_iso(H) = 1.2U_eq(C,N) for the amide groups.

Table 1
Experimental details

Crystal data
Chemical formula	(C₁₆H₃₆N)[Er(C₁₁H₁₂NO₃)₄(H₂O)]·3C₂H₆OS·1.5H₂O
M_r	1512.99
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	220
a, b, c (Å)	15.3967 (1), 30.6741 (2), 16.0612 (1)
β (°)	90.172 (1)
V (Å³)	7585.35 (8)
Z	4
Radiation type	Cu Kα
μ (mm⁻¹)	3.36
Crystal size (mm)	0.44 × 0.24 × 0.04

Data collection
Diffractometer	Rigaku XtaLAB Synergy Dualflex diffractometer with a HyPix detector
Absorption correction	Gaussian (CrysAlis PRO; Rigaku OD, 2022 $[Rigaku OD (2022). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ )
T_min, T_max	0.135, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	103272, 13894, 12290
R_int	0.061
(sin θ/λ)_max (Å⁻¹)	0.602

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.101, 1.04
No. of reflections	13894
No. of parameters	843
No. of restraints	7
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	1.32, −1.04
Computer programs: CrysAlis PRO (Rigaku OD, 2022 $[Rigaku OD (2022). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ), SUPERFLIP (Palatinus & Chapuis, 2007), SHELXL2018 (Sheldrick, 2015 ), Mercury software (Macrae et al., 2020) and Vesta (Momma & Izumi, 2011 ).

3. Results and discussion

The synthetic procedure used to produce 1 was slightly different from previous reports. Herein, we used the Et(Htmpa) proligand and n-Bu₄NOH in a diluted DMSO solution to obtain compound 1 in a one-pot synthesis, in contrast to other reports, in which the corresponding tetrabutylammonium salt of the ligand was isolated, characterized and then added to the solution of the corresponding lanthanide(III) ion. Complex 1 was obtained both as a single crystal and polycrystalline bulk. Elemental analysis and IR spectrometry (Fig. S1 in the supporting information), as well as the thermogravimetric analysis (TG curve; Fig. S2), support the composition of 1, whose stoichiometry was determined by single-crystal X-ray diffraction. The TG profile of 1 in Fig. S2 shows a gradual stepwise mass loss of ca 17% from room temperature to around 147 °C, corresponding to the complete release of the solvent molecules of crystallization [i.e. 1.5 H₂O (1.8%) and 3 DMSO (15.5%)], to render the unsolvated derivative of formula n-Bu₄N[Er(Htmpa)₄(H₂O)] (2). Compound 2 exhibits an unusually high thermal stability up to around 257 °C, just before decomposition occurs. Otherwise, the TDA profile of 1 in Fig. S2 evidences three distinct endothermic peaks centred around 40, 60 and 150 °C, which could be attributed to the loss of 1.5 H₂O, 2 DMSO and 1 DMSO solvent molecule of crystallization, respectively, evidencing the larger affinity of the included DMSO guest molecule. Moreover, the PXRD pattern of the polycrystalline sample (Fig. S3) is almost identical to that calculated from the crystal structure, supporting the purity of 1. The differences in intensity can be related to the preferential orientation of the powder sample and the optical elements used in the PXRD experiment.

The crystal structure of 1 consists of a discrete mononuclear erbium(III) complex anion, [Er(Htmpa)₄(H₂O)]⁻, an n-Bu₄N⁺ cation and crystallization solvent molecules, three DMSO and one and a half water molecules per metal complex. The complex crystallizes in the monoclinic space group P2₁/n with four erbium(III) complexes per unit cell. Fig. 1(a) shows the lanthanide atom surrounded by four bidentate monodeprotonated oxamate ligands from N-(2,4,6-trimethylphenyl)oxamic acid, and two water molecules. One tetrabutylammonium cation acts as a counter-ion, and two water molecules and three DMSO molecules of crystallization occur also in the asymmetric unit of each complex. In this case, the Er^III ion is nine-coordinated and the four aromatic rings are arranged in a cis orientation pointing in the same direction, opposite to the coordinated water molecule. The resulting structure is reminiscent of a calixarene-like motif for the anionic unit, as described for [Ln^III(HL)₄(DMSO)] units, in which HL is N-(4-X-phenyl)oxamic acid (X = Cl or F) (Vaz et al., 2020, 2022). However, in the case of 1, there are two remarkable differences: (i) one of the three DMSO crystallization molecules is practically inside the calixarene-type structure, almost in the middle of the packing of the four aromatic rings, and (ii) one water molecule is coordinated to the lanthanide(III) ion of 1, in contrast to the earlier reported example (Vaz et al., 2020, 2022). These structural features are probably a consequence of the differences in the synthetic procedure followed.

Figure 1
(a) The crystal structure of n-Bu₄N[Er(Htmpa)₄(H₂O)]·3DMSO·1.5H₂O (1). C atoms (in gray) are not labelled for clarity. Displacement ellipsoids are drawn at the 50% probability level.

Each monodeprotonated oxamate fragment of the four Htmpa⁻ ligands coordinates to the metal atom through its amide and carboxylate O atoms in a bidentate manner, subtending five-membered chelate rings [Fig. 2(a)]. The ninth coordination site is filled by a water molecule. All metal–oxamate bonds are very similar and cover the narrow range from 2.3541 (17) (Er1—O1) to 2.4592 (17) Å (Er1—O9). The coordination polyhedron of the Er^III ion is very close to a capped antiprismatic square [Fig. 2(b) and Table S1]. The water molecule, although being the capping ligand, exhibits a bond length shorter than those of the oxamate [Er1—O13 = 2.449 (2) Å]. One of the squares is built by all the amide O atoms (O3, O6, O9 and O12), while the other is defined by the carboxylate O atoms (O1, O4, O7 and O10); the water molecule is found as the capping ligand of this last square. The four Htmpa⁻ substituents are on the same side, interacting via CH₃⋯π in a square-like pattern [Fig. 2(a)], the distances from the methyl C atom to the centre of the aromatic ring cover the range 3.58–4.31 Å (see Table S2). The calixarene-like conformation of this complex is like a goblet, forming a small hydrophobic void.

Figure 2
(a) The crystal structure of the [Er(Htmpa)₄(H₂O)]⁻ anion of 1, with the relevant atoms labelled. Light-gray dotted lines indicate the CH₃⋯π interactions. Displacement ellipsoids are drawn at the 50% probability level. (b) The coordination sphere around the Er atom, showing its capped antiprismatic coordination geometry. H atoms have been omitted for clarity. C, O and N atoms are coloured in gray, red and blue, respectively.

The symmetry around the metal ion was compared to the ideal spherical capped square antiprism (CSAPR-9) through the continuous shape measures methodology (Llunell et al., 2013 ). The value found is 0.263 (Table S3), demonstrating that supramolecular chemistry plays a significant role in the crystal structure and the symmetry around the metal centre. Other nine-coordinated lanthanide(III)–oxamate complexes present a monocapped square antiprismatic, tricapped trigonal prismatic J51 (JTCTPR-9) and spherical tricapped trigonal prismatic symmetry (TCTPR-9) (Vaz et al., 2020, 2022).

In the crystal packing of 1, one can see two anionic complexes interacting with each other via van der Waals interactions of the 2,4,6-trimethylphenyl moiety. The combined void has an accessible volume of 378.5 Å³, hosting two DMSO molecules and one water molecule of crystallization, the last being divided over two positions to interact with both DMSO molecules simultaneously. One DMSO molecule has a CH₃ group inserted into the void (see Table S4) and the rest points out where it can interact with a water molecule via hydrogen bonds, which is also bound to the other DMSO molecule inserted into the second hydrophobic void [see Fig. 3(a)]. Along this interaction, the Er atoms are separated by 16.3474 (9) Å [Er1⋯Er1^vi; symmetry code: (vi) −x + 1, −y + 2, −z]. All other crystallization molecules, i.e. two DMSO and one water molecule, interact with the coordinated water molecule via hydrogen bonds, as can be seen in Fig. 3(b) and Table S2. These molecules bind to the coordinated water molecule, transitioning between the polar part of the complex to the apolar n-Bu₄N⁺, where the methyl groups of the DMSO molecules can interact with the aliphatic chains in the cation.

Figure 3
(a) Water and DMSO molecules fitting the voids formed by the packing of two [Er(Htmpa)₄(H₂O)]⁻ complexes. [Symmetry code: (vi) −x + 1, −y + 2, −z.] Displacement ellipsoids are drawn at the 50% probability level and molecules inside the voids as a ball-and-stick model. Orange dotted lines represent hydrogen bonds. H atoms have been omitted for clarity. (b) Interaction of the [Er(tmpa)₄(H₂O)]⁻ complex with the molecules of crystallization. Er, C, O, N and S atoms are coloured in green, gray, red, blue and yellow, respectively. Displacement ellipsoids are drawn at the 50% probability level. (c) Perspective drawing of two anionic entities of inclusion complex 1 (omitting the H atoms), in which the space-filling model represents the DMSO and H₂O solvent molecules.

The crystal packing of 1 is strongly based on hydrogen bonds via molecular recognition (see Table S4). Each oxamate has a protonated N atom which recognizes the neighbouring non-coordinated carboxylate O atom. This interaction occurs in a dimeric way, meaning the recognized molecule also has a protonated N atom, which interacts with the original oxamate non-coordinated O atom. Since the erbium complex has four oxamate ligands almost equally separated, the autorecognition of the complexes leads to a two-dimensional (2D) supramolecular system along the crystallographic ac plane [Fig. 4(a)]. Within this plane, the closest metal–metal separation along the (101) direction is 11.1287 (5) Å, while it is 11.1620 (5) Å in the ( $[\overline{1}]$ 0 $[\overline{1}]$ ) direction. The crystal packing along the crystallographic b axis is governed by van der Waals interactions. The 2,4,6-trimethylphenyl substituents along this direction form the voids with the captured DMSO and water molecules, the aliphatic arms of n-Bu₄N⁺ mediate the contacts with the aromatic part and the DMSO methyl groups cap the coordinated water molecule [see Fig. 4(b)].

Figure 4
(a) Molecular recognition of monodeprotonated oxamate fragments via hydrogen bonds (orange dotted lines) leading to a 2D supramolecular network running parallel to the crystallographic ac plane. C, O and N atoms are coloured in gray, red and blue, respectively. (b) Crystal packing along the crystallographic b axis, showing the n-Bu₄N⁺ ions mediating the van der Waals interactions between the metal complexes and solvent molecules. Colour code: [Er(H₂O)(Htmpa)₄]⁻ complex anions in gray, n-Bu₄N⁺ cations in pink, voids containing the trapped DMSO and water molecules in orange, and the remaining crystallization molecules in green.

The variable-temperature magnetic properties of 1 were investigated on a collection of crushed single crystals in direct-current (dc) and alternating-current (ac) modes. Dc data are shown as the χ_MT versus T plot in Fig. 5 [χ_M being the magnetic susceptibility per mol of the erbium(III) ion]. At room temperature, χ_MT is equal to 11.36 cm³ Oe mol⁻¹, a value which is close to that expected for a magnetically isolated Er^III ion [ground term ⁴I_15/2 with an equally populated J = 15/2 state, g_J = 6/5, L = 6 and S = 3/2] (Sorace & Gatteschi, 2015 ). Upon cooling, a monotonic decrease of χ_MT is observed until approximately 100 K, where the downturn becomes more pronounced, reaching 6.48 cm³ K mol⁻¹ at 2.0 K. The thermal depopulation of the excited Stark sublevels split by the crystal field and the spin-orbit coupling effects would account for the reduction of the χ_MT value when the temperature is decreased.

Figure 5
Temperature dependence of the c_MT product for 1 (H = 200 Oe). Inset: M versus HT⁻¹ curves for 1 at 2.0, 4.0 and 8.0 K.

The reduced magnetization curves for 1 do not collapse (M against H/T plots; see inset of Fig. 5), indicating the occurrence of a considerable magnetic anisotropy. M attains 4.9 Nβ at 2.0 K under 70 kOe, a value which is well below the theoretical value for saturation (ca 9.0 Nβ), a typical feature for Ln³⁺ compounds (Bazhenova et al., 2020 ). Hysteresis measurements at 2.0 K show no coercive field or remnant magnetization.

The dynamic magnetic behaviour of 1 was investigated through ac susceptibility measurements in the frequency range 0.1–10 kHz under applied dc fields ranging from 0 to 1000 Oe. Non-zero values of the out-of-phase signal (χ′′) were observed under H_dc = 0 Oe, but well-defined maximum peaks of this signal occurred by the application of dc magnetic fields of 600 and 1000 Oe below 5.0 K, suggesting field-induced SIM behaviour for 1. Fig. 6(a) shows both the in-phase (χ′) and out-of-phase (χ′′) frequency dependence under H_dc = 1000 Oe (optimum field) in the temperature range 2.0–5.0 K. The corresponding Cole–Cole plots of these data are depicted in Fig. 6(b). The Cole–Cole plots show a nearly semicircular and symmetrical shape, indicating a single relaxation process. The frequency dependence of both in-phase (χ′) and out-of-phase (χ′′) components of the ac susceptibility was fitted through the generalized Debye model using CCFIT2 software (Reta & Chilton, 2019 ; Blackmore et al., 2023 ). The parameters provided by these fittings are listed in Table S5. The temperature dependence of relaxation time (t) is shown in Fig. 7. These data were fitted by considering a combination of the Orbach process and quantum tunnelling of magnetization (QTM) by means of the following expression [Equation (1)]:

$[\tau ^{-1} (T) = \tau_0^{-1}{\rm exp}(-U_{\rm eff}/T) + \tau_{\rm QTM}^{-1}]$

where τ₀ is a pre-exponential factor, U_eff accounts for the energy barrier to the relaxation of the magnetization, and τ_QTM⁻¹ stands for the characteristic QTM rate. The best-fit results are: U_eff = 32 (2) K, τ₀ = 1.25 (2) × 10⁻⁹ s and τ_QTM = 1.4 (8) × 10⁻³ s. The effective energy barrier found for 1 is slightly greater than that reported for an erbium(III) β-diketonate complex (ca 26.8 K) and much greater than the values of the [Er(hd)₃(bipy)] complex (8 K) (hd is hexane-2,4-dione and bipy is 2,2′-bipyridine) (Martín-Ramos et al., 2015 ; Silva et al., 2014 ). This analysis of the data obtained under a dc field of 600 Oe for 1 shows values very close to those obtained with a field of 1000 Oe (see Fig. S5). A greater energy barrier was determined for one of the two processes observed in the Er^III complex [Er(dbm)₃(bipy)] (dbm is dibenzoylmethanate) with important intermolecular interaction effects, the values of U_eff being of 9.0 and 40 K (Silva et al., 2015 ).

Figure 6
(a) In-phase (χ′) and out-of-phase (χ′′) components of the magnetic susceptibility of 1 in the temperature range 2.0–5.0 K under H_dc = 1.0 kOe. (b) Cole–Cole plots of 1. The solid lines in parts (a) and (b) represent the best-fit curves using generalized Debye model parameters.

Figure 7
Arrhenius plot of ln t versus T⁻¹ of 1 under H_dc = 1.0 kOe. The solid line represents the best-fit curve to the experimental data, as described in the text, taking into consideration the uncertainties.

4. Conclusion

In this article, we describe the synthesis, characterization, crystal structure and magnetic properties of a mononuclear erbium(III) oxamate complex with the monodeprotonated form of N-(2,4,6-trimethylphenyl)oxamic acid as a ligand. The Er^III ion is nine-coordinated by four bidentate monodeprotonated oxamate groups and one water molecule, building a spherical capped square antiprism (CSAPR-9) polyhedron. Cryomagnetic measurements show that 1 exhibits field-induced magnetization relaxation, thus being a new example of a field-induced SIM of erbium(III) and a potential spin qubit candidate for future quantum technologies. We show that electronic donor groups at the aromatic rings of functionalized oxamate complexes can also favour the presence of the relaxation of the magnetization phenomena in lanthanide(III)–oxamate compounds.

Supporting information

CCDC reference: 2358484

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2053229624005977/dg3058sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2053229624005977/dg3058Isup2.hkl

Additional figures. DOI: https://doi.org/10.1107/S2053229624005977/dg3058sup3.pdf

Computing details top

Tetrabutylammonium aqua[N-(2,4,6-trimethylphenyl)oxamato]erbium(III)–dimethylsulfoxide–water (1/3/1.5) top

Crystal data top

(C₁₆H₃₆N)[Er(C₁₁H₁₂NO₃)₄(H₂O)]·3C₂H₆OS·1.5H₂O	F(000) = 3172
M_r = 1512.99	D_x = 1.325 Mg m⁻³
Monoclinic, P2₁/n	Cu Kα radiation, λ = 1.54184 Å
a = 15.3967 (1) Å	Cell parameters from 55180 reflections
b = 30.6741 (2) Å	θ = 2.9–78.8°
c = 16.0612 (1) Å	µ = 3.36 mm⁻¹
β = 90.172 (1)°	T = 220 K
V = 7585.35 (8) Å³	Plate, colorless
Z = 4	0.44 × 0.24 × 0.04 mm

Data collection top

Rigaku XtaLAB Synergy Dualflex diffractometer with a HyPix detector	13894 independent reflections
Radiation source: micro-focus sealed X-ray tube	12290 reflections with I > 2σ(I)
Detector resolution: 10.0000 pixels mm^-1	R_int = 0.061
ω scans	θ_max = 68.3°, θ_min = 2.9°
Absorption correction: gaussian (CrysAlis PRO; Rigaku OD, 2022)	h = −18→18
T_min = 0.135, T_max = 1.000	k = −36→36
103272 measured reflections	l = −15→19

Refinement top

Refinement on F²	7 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.037	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.101	w = 1/[σ²(F_o²) + (0.0501P)² + 7.8003P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max = 0.002
13894 reflections	Δρ_max = 1.32 e Å⁻³
843 parameters	Δρ_min = −1.04 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
C1	0.73925 (16)	0.72931 (8)	−0.05786 (15)	0.0241 (5)
C2	0.69087 (16)	0.77092 (9)	−0.08635 (15)	0.0254 (5)
C3	0.68188 (17)	0.82805 (9)	−0.18970 (17)	0.0310 (6)
C4	0.6992 (2)	0.86814 (10)	−0.15435 (19)	0.0394 (7)
C5	0.6593 (2)	0.90479 (11)	−0.1891 (2)	0.0449 (7)
H5	0.668586	0.931946	−0.164860	0.054*
C6	0.6063 (2)	0.90173 (11)	−0.2585 (2)	0.0469 (8)
C7	0.5928 (2)	0.86102 (11)	−0.2934 (2)	0.0436 (7)
H7	0.558664	0.858746	−0.341086	0.052*
C8	0.62851 (18)	0.82366 (10)	−0.25945 (18)	0.0368 (6)
C9	0.7619 (3)	0.87200 (13)	−0.0825 (2)	0.0563 (9)
H9A	0.766214	0.901963	−0.065765	0.084*
H9B	0.741376	0.854818	−0.036632	0.084*
H9C	0.818007	0.861660	−0.099338	0.084*
C10	0.5638 (3)	0.94183 (14)	−0.2961 (3)	0.0717 (12)
H10A	0.529658	0.933442	−0.343534	0.108*
H10B	0.527016	0.955328	−0.255375	0.108*
H10C	0.607861	0.962082	−0.313059	0.108*
C11	0.6098 (2)	0.77930 (12)	−0.2959 (2)	0.0514 (8)
H11A	0.640014	0.757436	−0.264391	0.077*
H11B	0.548487	0.773754	−0.293935	0.077*
H11C	0.629026	0.778496	−0.352730	0.077*
C12	0.69649 (17)	0.73844 (8)	0.23247 (16)	0.0273 (5)
C13	0.73154 (16)	0.77694 (9)	0.18058 (15)	0.0254 (5)
C14	0.83646 (18)	0.83606 (9)	0.17568 (17)	0.0333 (6)
C15	0.88708 (19)	0.83223 (10)	0.10452 (18)	0.0360 (6)
C16	0.9206 (2)	0.87032 (12)	0.0699 (2)	0.0445 (7)
H16	0.953853	0.868276	0.021742	0.053*
C17	0.9066 (2)	0.91077 (12)	0.1040 (2)	0.0548 (9)
C18	0.8605 (3)	0.91281 (12)	0.1783 (3)	0.0652 (11)
H18	0.854067	0.939598	0.204642	0.078*
C19	0.8239 (3)	0.87596 (12)	0.2141 (2)	0.0526 (8)
C20	0.7714 (4)	0.87882 (16)	0.2937 (3)	0.0861 (16)
H20A	0.769026	0.908586	0.311951	0.129*
H20B	0.713524	0.868404	0.283388	0.129*
H20C	0.798289	0.861265	0.335960	0.129*
C21	0.9422 (4)	0.95174 (15)	0.0631 (4)	0.0871 (15)
H21A	0.926082	0.976781	0.095384	0.131*
H21B	1.004326	0.949887	0.060074	0.131*
H21C	0.918578	0.954401	0.007907	0.131*
C22	0.9056 (3)	0.78925 (13)	0.0647 (3)	0.0610 (10)
H22A	0.941438	0.793582	0.016595	0.091*
H22B	0.935196	0.770732	0.103679	0.091*
H22C	0.851923	0.775797	0.048114	0.091*
C23	0.41139 (18)	0.73768 (9)	0.18704 (17)	0.0297 (6)
C24	0.46169 (16)	0.77922 (9)	0.21336 (15)	0.0252 (5)
C25	0.46375 (17)	0.84078 (9)	0.30876 (16)	0.0287 (5)
C26	0.44717 (19)	0.87965 (10)	0.26667 (18)	0.0366 (6)
C27	0.4806 (2)	0.91789 (10)	0.3010 (2)	0.0433 (7)
H27	0.470071	0.944194	0.274028	0.052*
C28	0.5292 (2)	0.91811 (10)	0.3740 (2)	0.0450 (7)
C29	0.5442 (2)	0.87859 (11)	0.41362 (19)	0.0408 (7)
H29	0.576438	0.878280	0.462654	0.049*
C30	0.51238 (18)	0.83942 (9)	0.38219 (17)	0.0327 (6)
C31	0.3957 (2)	0.88020 (13)	0.1865 (2)	0.0519 (8)
H31A	0.390927	0.909621	0.166700	0.078*
H31B	0.424812	0.862720	0.145614	0.078*
H31C	0.338779	0.868592	0.196349	0.078*
C32	0.5661 (3)	0.95986 (13)	0.4094 (3)	0.0754 (13)
H32A	0.549561	0.983903	0.374514	0.113*
H32B	0.543815	0.964346	0.464506	0.113*
H32C	0.628246	0.957845	0.411627	0.113*
C33	0.5301 (2)	0.79673 (11)	0.4251 (2)	0.0501 (8)
H33A	0.503085	0.773509	0.394417	0.075*
H33B	0.591625	0.791865	0.427748	0.075*
H33C	0.506852	0.797578	0.480457	0.075*
C34	0.44552 (17)	0.72748 (9)	−0.08388 (16)	0.0293 (5)
C35	0.42104 (16)	0.77140 (9)	−0.04378 (16)	0.0261 (5)
C36	0.32022 (18)	0.83213 (9)	−0.04394 (16)	0.0305 (6)
C37	0.3658 (2)	0.87037 (10)	−0.05813 (18)	0.0380 (6)
C38	0.3314 (2)	0.90893 (11)	−0.0271 (2)	0.0485 (8)
H38	0.361258	0.934873	−0.035994	0.058*
C39	0.2541 (2)	0.90989 (12)	0.0166 (2)	0.0524 (9)
C40	0.2107 (2)	0.87115 (13)	0.0295 (2)	0.0498 (8)
H40	0.158474	0.871532	0.058495	0.060*
C41	0.2424 (2)	0.83166 (11)	0.00060 (18)	0.0380 (6)
C42	0.4496 (2)	0.87045 (13)	−0.1057 (3)	0.0575 (9)
H42A	0.471436	0.899694	−0.109174	0.086*
H42B	0.491217	0.852366	−0.077533	0.086*
H42C	0.439609	0.859325	−0.160765	0.086*
C43	0.2173 (4)	0.95256 (17)	0.0488 (4)	0.0937 (17)
H43A	0.255717	0.976014	0.034308	0.141*
H43B	0.161324	0.957573	0.024104	0.141*
H43C	0.211646	0.951099	0.108195	0.141*
C44	0.1952 (3)	0.78959 (14)	0.0178 (3)	0.0604 (10)
H44A	0.226434	0.765794	−0.006850	0.091*
H44B	0.191195	0.785190	0.076795	0.091*
H44C	0.137852	0.790982	−0.005757	0.091*
C51	0.3698 (3)	0.52552 (13)	0.2897 (2)	0.0603 (10)
H51A	0.346285	0.543315	0.333282	0.090*
H51B	0.400994	0.501475	0.313662	0.090*
H51C	0.408622	0.542638	0.256297	0.090*
C52	0.2963 (2)	0.50830 (12)	0.2354 (2)	0.0493 (8)
H52A	0.256664	0.491588	0.269743	0.059*
H52B	0.264291	0.532748	0.212383	0.059*
C53	0.3281 (2)	0.47984 (11)	0.1649 (2)	0.0481 (8)
H53A	0.363912	0.456592	0.187265	0.058*
H53B	0.363474	0.497094	0.127510	0.058*
C55	0.2523 (2)	0.46033 (11)	0.1170 (2)	0.0445 (7)
H55A	0.222142	0.483607	0.088030	0.053*
H55B	0.211998	0.447632	0.156428	0.053*
C57	0.4335 (4)	0.5056 (2)	−0.1239 (4)	0.0985 (17)
H57A	0.461065	0.511839	−0.176098	0.148*
H57B	0.434448	0.531194	−0.089517	0.148*
H57C	0.464003	0.482421	−0.096325	0.148*
C58	0.3437 (4)	0.49247 (16)	−0.1388 (3)	0.0787 (13)
H58A	0.343425	0.467060	−0.174755	0.094*
H58B	0.313895	0.515793	−0.167953	0.094*
C59	0.2949 (3)	0.48201 (12)	−0.0613 (3)	0.0615 (10)
H59A	0.235574	0.474516	−0.075734	0.074*
H59B	0.293325	0.507651	−0.025952	0.074*
C60	0.3354 (2)	0.44448 (10)	−0.0130 (2)	0.0436 (7)
H60A	0.350361	0.421475	−0.051906	0.052*
H60B	0.388916	0.454569	0.012567	0.052*
C61	0.1327 (2)	0.32995 (13)	−0.1611 (3)	0.0583 (9)
H61A	0.079863	0.314383	−0.172458	0.087*
H61B	0.144520	0.349659	−0.206131	0.087*
H61C	0.179760	0.309629	−0.155621	0.087*
C62	0.1231 (2)	0.35527 (13)	−0.0817 (2)	0.0542 (9)
H62A	0.110157	0.335350	−0.036515	0.065*
H62B	0.074883	0.375418	−0.087072	0.065*
C63	0.2053 (2)	0.38059 (10)	−0.06094 (19)	0.0383 (6)
H63A	0.253054	0.360365	−0.052896	0.046*
H63B	0.219852	0.399564	−0.107156	0.046*
C64	0.19368 (19)	0.40760 (11)	0.0169 (2)	0.0416 (7)
H64A	0.165194	0.389814	0.058616	0.050*
H64B	0.155401	0.431819	0.004089	0.050*
C65	0.4290 (3)	0.35589 (18)	0.2539 (3)	0.0764 (13)
H65A	0.463793	0.332890	0.277013	0.115*
H65B	0.462132	0.371429	0.212921	0.115*
H65C	0.411936	0.375547	0.297332	0.115*
C67	0.3489 (3)	0.33666 (13)	0.2134 (2)	0.0544 (9)
H67A	0.316802	0.320390	0.254897	0.065*
H67B	0.366945	0.316277	0.170575	0.065*
C68	0.2887 (2)	0.37044 (11)	0.1743 (2)	0.0435 (7)
H68A	0.233111	0.357071	0.161477	0.052*
H68B	0.278696	0.393944	0.213521	0.052*
C69	0.32827 (18)	0.38856 (9)	0.09550 (19)	0.0352 (6)
H69A	0.334109	0.364958	0.055713	0.042*
H69B	0.386236	0.398989	0.108412	0.042*
C48	0.3326 (3)	0.62236 (13)	0.1497 (2)	0.0575 (9)
H48A	0.304909	0.639948	0.191341	0.086*
H48B	0.347715	0.594577	0.173163	0.086*
H48C	0.384237	0.636753	0.130686	0.086*
C47	0.2639 (3)	0.66895 (14)	0.0278 (3)	0.0679 (11)
H47A	0.234557	0.687653	0.066541	0.102*
H47B	0.323299	0.678015	0.022623	0.102*
H47C	0.235786	0.670678	−0.025513	0.102*
C49	0.5306 (3)	0.66064 (18)	0.3359 (3)	0.0845 (15)
H49A	0.546663	0.663853	0.393344	0.127*
H49B	0.558620	0.682830	0.303478	0.127*
H49C	0.468740	0.663449	0.330299	0.127*
C50	0.6760 (3)	0.61887 (14)	0.2984 (3)	0.0693 (11)
H50A	0.697161	0.621180	0.354536	0.104*
H50B	0.705218	0.595408	0.270626	0.104*
H50C	0.686800	0.645669	0.269413	0.104*
N1	0.72079 (15)	0.78967 (8)	−0.15436 (14)	0.0322 (5)
H1	0.765322	0.778493	−0.178499	0.039*
N2	0.79917 (15)	0.79818 (8)	0.21306 (14)	0.0336 (5)
H2	0.821429	0.788628	0.258717	0.040*
N3	0.42783 (15)	0.80114 (8)	0.27696 (14)	0.0318 (5)
H3	0.381876	0.790916	0.300179	0.038*
N4	0.35222 (15)	0.79167 (8)	−0.07575 (14)	0.0332 (5)
H4	0.325830	0.779936	−0.117361	0.040*
N5	0.27760 (15)	0.42563 (8)	0.05397 (16)	0.0357 (5)
O1	0.70372 (11)	0.71103 (6)	0.00333 (11)	0.0274 (4)
O2	0.80539 (12)	0.71799 (7)	−0.09525 (12)	0.0363 (4)
O3	0.62786 (11)	0.78413 (6)	−0.04631 (10)	0.0276 (4)
O5	0.72379 (14)	0.73294 (7)	0.30370 (12)	0.0418 (5)
O4	0.64103 (12)	0.71593 (6)	0.19397 (11)	0.0290 (4)
O6	0.69717 (11)	0.78582 (6)	0.11330 (10)	0.0271 (4)
O8	0.34141 (15)	0.72992 (8)	0.22112 (15)	0.0529 (7)
O7	0.44839 (11)	0.71624 (6)	0.13133 (11)	0.0296 (4)
O9	0.52813 (11)	0.78977 (6)	0.17621 (10)	0.0268 (4)
O11	0.40124 (16)	0.71293 (8)	−0.14068 (15)	0.0556 (7)
O10	0.51009 (12)	0.70936 (6)	−0.05009 (11)	0.0303 (4)
O12	0.46377 (11)	0.78538 (6)	0.01576 (10)	0.0273 (4)
O13	0.57495 (12)	0.65920 (6)	0.07631 (11)	0.0317 (4)
O16	0.30665 (19)	0.58712 (9)	0.00186 (19)	0.0681 (8)
O17	0.5368 (2)	0.60546 (10)	0.21066 (18)	0.0752 (9)
S2	0.26023 (6)	0.61457 (3)	0.06434 (6)	0.0525 (2)
S3	0.56337 (8)	0.60848 (4)	0.29982 (6)	0.0703 (3)
Er1	0.57866 (2)	0.73890 (2)	0.06838 (2)	0.02088 (6)
O18	0.53061 (17)	0.38295 (9)	0.04584 (17)	0.0571 (6)
O15	0.5639 (7)	1.0056 (3)	−0.1200 (6)	0.130 (5)*	0.524 (14)
S1	0.6524 (3)	0.94435 (13)	0.0684 (3)	0.1375 (16)*	0.632 (7)
C45	0.6143 (10)	0.8857 (5)	0.0815 (9)	0.117 (5)*	0.632 (7)
H45A	0.652036	0.870851	0.119778	0.175*	0.632 (7)
H45B	0.556087	0.885520	0.102710	0.175*	0.632 (7)
H45C	0.615574	0.871192	0.028543	0.175*	0.632 (7)
C46	0.6498 (7)	0.9674 (3)	0.1570 (6)	0.104 (3)*	0.632 (7)
H46A	0.694871	0.955606	0.191708	0.156*	0.632 (7)
H46B	0.658501	0.998156	0.150279	0.156*	0.632 (7)
H46C	0.594356	0.962247	0.182385	0.156*	0.632 (7)
O14	0.5858 (10)	0.9596 (5)	0.0085 (9)	0.198 (5)*	0.632 (7)
S1B	0.5841 (6)	0.9397 (3)	0.0680 (4)	0.140 (3)*	0.368 (7)
C46B	0.6555 (11)	0.9626 (5)	−0.0028 (10)	0.090 (4)*	0.368 (7)
H46D	0.692259	0.940200	−0.025178	0.136*	0.368 (7)
H46E	0.623282	0.976032	−0.047095	0.136*	0.368 (7)
H46F	0.690529	0.984106	0.024747	0.136*	0.368 (7)
O14A	0.533 (3)	0.9755 (12)	0.097 (2)	0.311 (17)*	0.368 (7)
C45A	0.6223 (12)	0.8931 (6)	0.1035 (12)	0.076 (5)*	0.368 (7)
H45D	0.654922	0.878828	0.060516	0.115*	0.368 (7)
H45E	0.659443	0.898473	0.150532	0.115*	0.368 (7)
H45F	0.574927	0.874735	0.120163	0.115*	0.368 (7)
H13B	0.565 (3)	0.6473 (13)	0.1266 (10)	0.115*
H13A	0.5338 (19)	0.6466 (13)	0.0445 (17)	0.115*
H18E	0.536 (2)	0.3554 (5)	0.064 (3)	0.115*
H18F	0.5849 (10)	0.3893 (13)	0.029 (3)	0.115*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0188 (12)	0.0324 (13)	0.0211 (12)	0.0023 (10)	0.0009 (9)	0.0011 (10)
C2	0.0214 (12)	0.0339 (13)	0.0208 (12)	0.0013 (10)	−0.0003 (9)	0.0027 (10)
C3	0.0256 (13)	0.0383 (15)	0.0292 (13)	0.0065 (11)	0.0075 (10)	0.0126 (11)
C4	0.0354 (15)	0.0455 (17)	0.0372 (15)	0.0012 (13)	0.0049 (12)	0.0124 (13)
C5	0.0426 (17)	0.0386 (16)	0.0536 (19)	0.0010 (13)	0.0084 (15)	0.0124 (14)
C6	0.0340 (16)	0.0486 (19)	0.058 (2)	0.0054 (14)	0.0034 (14)	0.0250 (16)
C7	0.0312 (15)	0.0562 (19)	0.0433 (17)	0.0019 (13)	−0.0029 (13)	0.0196 (15)
C8	0.0279 (14)	0.0491 (17)	0.0333 (14)	0.0040 (12)	0.0052 (11)	0.0103 (13)
C9	0.063 (2)	0.054 (2)	0.052 (2)	−0.0020 (17)	−0.0119 (17)	0.0044 (17)
C10	0.057 (2)	0.059 (2)	0.099 (3)	0.0096 (19)	−0.011 (2)	0.036 (2)
C11	0.052 (2)	0.055 (2)	0.0469 (19)	0.0011 (16)	−0.0084 (15)	0.0029 (16)
C12	0.0243 (13)	0.0337 (14)	0.0237 (13)	−0.0014 (10)	−0.0027 (10)	0.0056 (10)
C13	0.0223 (12)	0.0335 (13)	0.0204 (12)	−0.0027 (10)	−0.0023 (9)	0.0007 (10)
C14	0.0306 (14)	0.0378 (15)	0.0313 (14)	−0.0103 (11)	−0.0077 (11)	0.0026 (11)
C15	0.0300 (14)	0.0430 (16)	0.0350 (15)	−0.0066 (12)	−0.0046 (11)	0.0010 (12)
C16	0.0346 (16)	0.061 (2)	0.0384 (16)	−0.0140 (14)	−0.0006 (13)	0.0095 (15)
C17	0.052 (2)	0.050 (2)	0.061 (2)	−0.0172 (16)	−0.0036 (17)	0.0147 (17)
C18	0.082 (3)	0.0400 (19)	0.074 (3)	−0.0139 (19)	0.007 (2)	−0.0068 (18)
C19	0.063 (2)	0.0468 (19)	0.0474 (19)	−0.0094 (16)	0.0083 (16)	−0.0037 (15)
C20	0.126 (5)	0.066 (3)	0.067 (3)	−0.014 (3)	0.035 (3)	−0.017 (2)
C21	0.094 (4)	0.061 (3)	0.106 (4)	−0.030 (3)	0.009 (3)	0.028 (3)
C22	0.054 (2)	0.060 (2)	0.069 (2)	−0.0072 (18)	0.0196 (19)	−0.0079 (19)
C23	0.0246 (13)	0.0365 (15)	0.0279 (13)	−0.0075 (10)	0.0050 (11)	−0.0058 (11)
C24	0.0208 (12)	0.0342 (13)	0.0205 (11)	−0.0020 (10)	0.0010 (9)	−0.0033 (10)
C25	0.0236 (12)	0.0336 (14)	0.0289 (13)	−0.0033 (10)	0.0082 (10)	−0.0090 (11)
C26	0.0344 (15)	0.0437 (16)	0.0317 (14)	0.0004 (12)	0.0064 (12)	−0.0013 (12)
C27	0.0503 (18)	0.0319 (15)	0.0480 (18)	−0.0007 (13)	0.0061 (14)	−0.0011 (13)
C28	0.0437 (17)	0.0385 (16)	0.0527 (19)	−0.0078 (13)	0.0052 (14)	−0.0139 (14)
C29	0.0372 (16)	0.0475 (18)	0.0375 (16)	−0.0050 (13)	−0.0049 (12)	−0.0091 (13)
C30	0.0271 (13)	0.0372 (15)	0.0338 (14)	−0.0005 (11)	0.0036 (11)	−0.0041 (12)
C31	0.053 (2)	0.064 (2)	0.0383 (17)	0.0029 (17)	−0.0058 (15)	0.0039 (16)
C32	0.089 (3)	0.048 (2)	0.089 (3)	−0.021 (2)	−0.006 (3)	−0.020 (2)
C33	0.051 (2)	0.0485 (19)	0.0504 (19)	0.0020 (15)	−0.0101 (16)	0.0028 (15)
C34	0.0267 (13)	0.0374 (14)	0.0236 (12)	0.0049 (11)	−0.0058 (10)	−0.0042 (11)
C35	0.0211 (12)	0.0353 (13)	0.0219 (12)	0.0041 (10)	−0.0010 (9)	−0.0003 (10)
C36	0.0297 (13)	0.0389 (15)	0.0229 (12)	0.0100 (11)	−0.0080 (10)	−0.0033 (11)
C37	0.0361 (16)	0.0441 (16)	0.0338 (15)	0.0058 (13)	−0.0063 (12)	−0.0017 (12)
C38	0.056 (2)	0.0380 (16)	0.0519 (19)	0.0038 (15)	−0.0136 (16)	−0.0047 (15)
C39	0.055 (2)	0.050 (2)	0.052 (2)	0.0221 (16)	−0.0103 (16)	−0.0140 (16)
C40	0.0441 (18)	0.067 (2)	0.0387 (17)	0.0210 (16)	0.0055 (14)	−0.0073 (16)
C41	0.0359 (15)	0.0486 (17)	0.0295 (14)	0.0101 (13)	−0.0013 (11)	0.0002 (12)
C42	0.045 (2)	0.061 (2)	0.067 (2)	−0.0043 (17)	0.0085 (17)	0.0004 (19)
C43	0.107 (4)	0.071 (3)	0.103 (4)	0.041 (3)	−0.006 (3)	−0.036 (3)
C44	0.052 (2)	0.066 (2)	0.063 (2)	−0.0019 (18)	0.0141 (18)	0.0059 (19)
C51	0.070 (3)	0.058 (2)	0.053 (2)	−0.0087 (19)	−0.0062 (18)	−0.0083 (17)
C52	0.053 (2)	0.0480 (18)	0.0472 (18)	−0.0035 (15)	0.0026 (15)	−0.0073 (15)
C53	0.0418 (18)	0.0428 (17)	0.060 (2)	0.0013 (14)	0.0027 (15)	−0.0144 (15)
C55	0.0379 (16)	0.0402 (16)	0.0555 (19)	0.0101 (13)	0.0009 (14)	−0.0143 (15)
C57	0.084 (4)	0.093 (4)	0.119 (5)	−0.014 (3)	0.023 (3)	0.006 (3)
C58	0.098 (4)	0.059 (2)	0.079 (3)	0.005 (2)	0.004 (3)	0.017 (2)
C59	0.074 (3)	0.0363 (18)	0.074 (3)	−0.0017 (17)	−0.001 (2)	0.0071 (17)
C60	0.0447 (18)	0.0355 (15)	0.0505 (18)	−0.0027 (13)	0.0057 (14)	−0.0024 (14)
C61	0.046 (2)	0.062 (2)	0.066 (2)	−0.0010 (17)	−0.0048 (17)	−0.0183 (19)
C62	0.0361 (17)	0.063 (2)	0.063 (2)	−0.0015 (16)	−0.0072 (15)	−0.0135 (18)
C63	0.0375 (16)	0.0363 (15)	0.0412 (16)	0.0032 (12)	−0.0041 (12)	0.0036 (13)
C64	0.0286 (15)	0.0448 (17)	0.0515 (18)	0.0069 (12)	−0.0048 (13)	−0.0063 (14)
C65	0.064 (3)	0.117 (4)	0.048 (2)	0.005 (3)	−0.0185 (19)	−0.003 (2)
C67	0.057 (2)	0.061 (2)	0.0452 (19)	0.0065 (17)	−0.0082 (16)	0.0035 (16)
C68	0.0363 (16)	0.0471 (18)	0.0470 (18)	−0.0009 (13)	0.0032 (13)	0.0001 (14)
C69	0.0274 (14)	0.0352 (15)	0.0429 (16)	0.0051 (11)	0.0002 (12)	−0.0049 (12)
C48	0.066 (2)	0.052 (2)	0.055 (2)	−0.0077 (18)	−0.0034 (18)	0.0010 (17)
C47	0.075 (3)	0.061 (2)	0.067 (3)	0.017 (2)	0.002 (2)	0.005 (2)
C49	0.080 (3)	0.107 (4)	0.066 (3)	−0.015 (3)	0.027 (2)	0.013 (3)
C50	0.085 (3)	0.062 (2)	0.061 (2)	−0.007 (2)	−0.020 (2)	0.001 (2)
N1	0.0268 (11)	0.0410 (13)	0.0287 (11)	0.0099 (10)	0.0076 (9)	0.0128 (10)
N2	0.0323 (12)	0.0416 (13)	0.0269 (11)	−0.0108 (10)	−0.0097 (9)	0.0072 (10)
N3	0.0273 (11)	0.0385 (13)	0.0297 (11)	−0.0088 (9)	0.0093 (9)	−0.0108 (10)
N4	0.0301 (12)	0.0407 (13)	0.0288 (11)	0.0108 (10)	−0.0108 (9)	−0.0082 (10)
N5	0.0307 (12)	0.0338 (12)	0.0425 (13)	0.0047 (10)	0.0000 (10)	−0.0055 (10)
O1	0.0228 (9)	0.0344 (9)	0.0251 (9)	0.0060 (7)	0.0052 (7)	0.0072 (7)
O2	0.0296 (10)	0.0467 (11)	0.0328 (10)	0.0118 (9)	0.0100 (8)	0.0094 (9)
O3	0.0256 (9)	0.0358 (10)	0.0215 (8)	0.0080 (7)	0.0040 (7)	0.0043 (7)
O5	0.0391 (12)	0.0584 (13)	0.0279 (10)	−0.0159 (10)	−0.0146 (9)	0.0131 (9)
O4	0.0296 (9)	0.0343 (10)	0.0230 (8)	−0.0072 (8)	−0.0069 (7)	0.0064 (7)
O6	0.0221 (8)	0.0371 (10)	0.0222 (8)	−0.0057 (7)	−0.0031 (7)	0.0046 (7)
O8	0.0421 (13)	0.0640 (15)	0.0527 (14)	−0.0257 (11)	0.0282 (11)	−0.0291 (11)
O7	0.0245 (9)	0.0344 (10)	0.0299 (9)	−0.0053 (7)	0.0079 (7)	−0.0090 (8)
O9	0.0219 (9)	0.0346 (9)	0.0238 (8)	−0.0044 (7)	0.0037 (7)	−0.0053 (7)
O11	0.0540 (14)	0.0587 (14)	0.0538 (14)	0.0234 (12)	−0.0325 (12)	−0.0277 (12)
O10	0.0310 (10)	0.0364 (10)	0.0235 (9)	0.0088 (8)	−0.0080 (7)	−0.0072 (7)
O12	0.0226 (9)	0.0356 (10)	0.0237 (9)	0.0062 (7)	−0.0052 (7)	−0.0056 (7)
O13	0.0291 (10)	0.0357 (10)	0.0305 (9)	0.0002 (7)	−0.0002 (8)	−0.0022 (8)
O16	0.0684 (18)	0.0595 (16)	0.0765 (18)	−0.0102 (14)	0.0146 (14)	−0.0257 (14)
O17	0.092 (2)	0.0729 (18)	0.0606 (17)	−0.0337 (16)	−0.0356 (16)	0.0209 (14)
S2	0.0440 (4)	0.0553 (5)	0.0582 (5)	−0.0103 (4)	0.0106 (4)	−0.0109 (4)
S3	0.0845 (7)	0.0744 (7)	0.0520 (5)	−0.0373 (6)	−0.0177 (5)	0.0264 (5)
Er1	0.01724 (9)	0.02918 (9)	0.01621 (9)	0.00079 (5)	0.00011 (5)	−0.00017 (5)
O18	0.0501 (14)	0.0545 (14)	0.0665 (16)	−0.0022 (11)	0.0044 (12)	−0.0091 (12)

Geometric parameters (Å, º) top

C1—O2	1.234 (3)	C35—N4	1.330 (3)
C1—O1	1.258 (3)	C36—C37	1.386 (4)
C1—C2	1.547 (3)	C36—C41	1.398 (4)
C2—O3	1.234 (3)	C36—N4	1.430 (4)
C2—N1	1.319 (3)	C37—C38	1.389 (5)
C3—C4	1.380 (4)	C37—C42	1.501 (5)
C3—C8	1.394 (4)	C38—C39	1.384 (5)
C3—N1	1.437 (3)	C39—C40	1.380 (6)
C4—C5	1.396 (4)	C39—C43	1.517 (5)
C4—C9	1.507 (5)	C40—C41	1.387 (5)
C5—C6	1.383 (5)	C41—C44	1.507 (5)
C6—C7	1.384 (5)	C51—C52	1.522 (5)
C6—C10	1.518 (5)	C52—C53	1.512 (5)
C7—C8	1.383 (4)	C53—C55	1.518 (5)
C8—C11	1.509 (5)	C55—N5	1.520 (4)
C12—O5	1.229 (3)	C57—C58	1.458 (8)
C12—O4	1.259 (3)	C58—C59	1.491 (6)
C12—C13	1.544 (4)	C59—C60	1.520 (5)
C13—O6	1.232 (3)	C60—N5	1.514 (4)
C13—N2	1.333 (3)	C61—C62	1.501 (5)
C14—C19	1.385 (5)	C62—C63	1.521 (4)
C14—C15	1.390 (4)	C63—C64	1.511 (4)
C14—N2	1.429 (4)	C64—N5	1.525 (4)
C15—C16	1.394 (4)	C65—C67	1.512 (6)
C15—C22	1.493 (5)	C67—C68	1.525 (5)
C16—C17	1.374 (5)	C68—C69	1.512 (4)
C17—C18	1.391 (6)	C69—N5	1.531 (4)
C17—C21	1.521 (5)	C48—S2	1.781 (4)
C18—C19	1.389 (5)	C47—S2	1.769 (4)
C19—C20	1.517 (5)	C49—S3	1.775 (6)
C23—O8	1.233 (3)	C50—S3	1.763 (5)
C23—O7	1.249 (3)	O1—Er1	2.3541 (17)
C23—C24	1.549 (4)	O3—Er1	2.4289 (17)
C24—O9	1.229 (3)	O4—Er1	2.3400 (17)
C24—N3	1.331 (3)	O6—Er1	2.4316 (17)
C25—C26	1.394 (4)	O7—Er1	2.3540 (17)
C25—C30	1.396 (4)	O9—Er1	2.4592 (17)
C25—N3	1.429 (3)	O10—Er1	2.3547 (17)
C26—C27	1.394 (4)	O12—Er1	2.4222 (17)
C26—C31	1.509 (4)	O13—Er1	2.449 (2)
C27—C28	1.389 (5)	O16—S2	1.494 (3)
C28—C29	1.388 (5)	O17—S3	1.491 (3)
C28—C32	1.511 (5)	O15—O14Aⁱ	1.64 (4)
C29—C30	1.392 (4)	S1—O14	1.481 (15)
C30—C33	1.504 (4)	S1—C46	1.589 (10)
C34—O11	1.222 (3)	S1—C45	1.904 (15)
C34—O10	1.260 (3)	S1B—O14A	1.43 (4)
C34—C35	1.541 (4)	S1B—C45A	1.648 (19)
C35—O12	1.236 (3)	S1B—C46B	1.73 (2)

O2—C1—O1	128.1 (2)	C36—C41—C44	121.1 (3)
O2—C1—C2	119.1 (2)	C53—C52—C51	112.8 (3)
O1—C1—C2	112.9 (2)	C52—C53—C55	111.0 (3)
O3—C2—N1	124.4 (2)	C53—C55—N5	114.6 (3)
O3—C2—C1	119.7 (2)	C57—C58—C59	113.7 (5)
N1—C2—C1	115.8 (2)	C58—C59—C60	112.4 (4)
C4—C3—C8	122.0 (3)	N5—C60—C59	114.2 (3)
C4—C3—N1	119.2 (3)	C61—C62—C63	111.5 (3)
C8—C3—N1	118.8 (3)	C64—C63—C62	111.1 (3)
C3—C4—C5	117.9 (3)	C63—C64—N5	114.8 (2)
C3—C4—C9	120.5 (3)	C65—C67—C68	114.0 (4)
C5—C4—C9	121.5 (3)	C69—C68—C67	110.3 (3)
C6—C5—C4	121.7 (3)	C68—C69—N5	115.6 (2)
C5—C6—C7	118.4 (3)	C2—N1—C3	122.6 (2)
C5—C6—C10	121.2 (4)	C13—N2—C14	123.2 (2)
C7—C6—C10	120.4 (3)	C24—N3—C25	123.5 (2)
C8—C7—C6	121.9 (3)	C35—N4—C36	122.9 (2)
C7—C8—C3	118.0 (3)	C60—N5—C55	111.0 (2)
C7—C8—C11	121.3 (3)	C60—N5—C64	111.1 (2)
C3—C8—C11	120.7 (3)	C55—N5—C64	107.2 (2)
O5—C12—O4	127.7 (2)	C60—N5—C69	107.1 (2)
O5—C12—C13	119.2 (2)	C55—N5—C69	111.2 (2)
O4—C12—C13	113.1 (2)	C64—N5—C69	109.3 (2)
O6—C13—N2	124.6 (2)	C1—O1—Er1	122.88 (15)
O6—C13—C12	119.5 (2)	C2—O3—Er1	117.08 (16)
N2—C13—C12	115.9 (2)	C12—O4—Er1	122.30 (16)
C19—C14—C15	121.4 (3)	C13—O6—Er1	116.69 (16)
C19—C14—N2	118.3 (3)	C23—O7—Er1	122.90 (16)
C15—C14—N2	120.2 (3)	C24—O9—Er1	116.13 (16)
C14—C15—C16	117.8 (3)	C34—O10—Er1	121.96 (16)
C14—C15—C22	122.4 (3)	C35—O12—Er1	116.89 (16)
C16—C15—C22	119.8 (3)	O16—S2—C47	107.0 (2)
C17—C16—C15	122.6 (3)	O16—S2—C48	107.06 (19)
C16—C17—C18	117.7 (3)	C47—S2—C48	96.2 (2)
C16—C17—C21	121.1 (4)	O17—S3—C50	105.5 (2)
C18—C17—C21	121.3 (4)	O17—S3—C49	107.0 (2)
C19—C18—C17	121.9 (4)	C50—S3—C49	97.0 (2)
C14—C19—C18	118.5 (3)	O4—Er1—O1	86.51 (6)
C14—C19—C20	120.1 (3)	O4—Er1—O7	83.62 (6)
C18—C19—C20	121.4 (4)	O1—Er1—O7	141.49 (7)
O8—C23—O7	128.1 (2)	O4—Er1—O10	139.69 (7)
O8—C23—C24	118.3 (2)	O1—Er1—O10	82.35 (6)
O7—C23—C24	113.6 (2)	O7—Er1—O10	81.54 (6)
O9—C24—N3	124.6 (2)	O4—Er1—O12	140.84 (6)
O9—C24—C23	120.0 (2)	O1—Er1—O12	131.03 (6)
N3—C24—C23	115.4 (2)	O7—Er1—O12	72.62 (6)
C26—C25—C30	122.2 (3)	O10—Er1—O12	67.63 (6)
C26—C25—N3	119.0 (3)	O4—Er1—O3	134.24 (6)
C30—C25—N3	118.9 (3)	O1—Er1—O3	67.27 (6)
C25—C26—C27	117.5 (3)	O7—Er1—O3	139.68 (6)
C25—C26—C31	121.2 (3)	O10—Er1—O3	75.35 (7)
C27—C26—C31	121.4 (3)	O12—Er1—O3	68.18 (6)
C28—C27—C26	122.4 (3)	O4—Er1—O6	67.47 (6)
C29—C28—C27	118.1 (3)	O1—Er1—O6	74.49 (6)
C29—C28—C32	120.4 (3)	O7—Er1—O6	133.39 (6)
C27—C28—C32	121.5 (3)	O10—Er1—O6	143.30 (6)
C28—C29—C30	122.0 (3)	O12—Er1—O6	107.56 (6)
C29—C30—C25	117.9 (3)	O3—Er1—O6	69.61 (6)
C29—C30—C33	121.5 (3)	O4—Er1—O13	70.37 (6)
C25—C30—C33	120.6 (3)	O1—Er1—O13	71.32 (6)
O11—C34—O10	126.7 (3)	O7—Er1—O13	70.29 (6)
O11—C34—C35	119.7 (2)	O10—Er1—O13	69.35 (6)
O10—C34—C35	113.5 (2)	O12—Er1—O13	126.06 (6)
O12—C35—N4	123.9 (2)	O3—Er1—O13	128.10 (6)
O12—C35—C34	119.8 (2)	O6—Er1—O13	126.37 (6)
N4—C35—C34	116.3 (2)	O4—Er1—O9	73.37 (6)
C37—C36—C41	121.9 (3)	O1—Er1—O9	143.51 (6)
C37—C36—N4	120.0 (3)	O7—Er1—O9	67.23 (6)
C41—C36—N4	118.1 (3)	O10—Er1—O9	132.17 (6)
C36—C37—C38	117.9 (3)	O12—Er1—O9	68.90 (6)
C36—C37—C42	121.4 (3)	O3—Er1—O9	105.77 (6)
C38—C37—C42	120.7 (3)	O6—Er1—O9	69.77 (6)
C39—C38—C37	121.9 (3)	O13—Er1—O9	126.10 (6)
C40—C39—C38	118.4 (3)	O14—S1—C46	115.0 (7)
C40—C39—C43	120.7 (4)	O14—S1—C45	99.1 (8)
C38—C39—C43	120.9 (4)	C46—S1—C45	108.2 (6)
C39—C40—C41	122.1 (3)	O14A—S1B—C45A	138.4 (17)
C40—C41—C36	117.8 (3)	O14A—S1B—C46B	105.0 (17)
C40—C41—C44	121.1 (3)	C45A—S1B—C46B	110.5 (10)

Symmetry code: (i) −x+1, −y+2, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O8ⁱⁱ	0.86	2.01	2.799 (3)	152
N2—H2···O11ⁱⁱⁱ	0.86	2.03	2.843 (3)	158
N3—H3···O2^iv	0.86	2.07	2.852 (3)	150
N4—H4···O5^v	0.86	2.05	2.865 (3)	157
O13—H13B···O17	0.90 (1)	1.91 (1)	2.780 (3)	161 (4)
O13—H13A···O18^vi	0.90 (1)	1.98 (1)	2.854 (3)	165 (3)
O18—H18E···O10^vi	0.90 (1)	2.12 (2)	2.901 (3)	144 (4)
O18—H18F···O16^vi	0.90 (1)	1.89 (1)	2.778 (4)	170 (4)

Symmetry codes: (ii) x+1/2, −y+3/2, z−1/2; (iii) x+1/2, −y+3/2, z+1/2; (iv) x−1/2, −y+3/2, z+1/2; (v) x−1/2, −y+3/2, z−1/2; (vi) −x+1, −y+1, −z.

Acknowledgements

The authors thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), the Bioanalytical Facility NEPS-DQ/UFMG (https://ne.qui.ufmg.br), the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), the Fundo de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), the Spanish MINECO and Unidad de Excelencia Maria de Maeztu for financial support.

Funding information

Funding for this research was provided by: Conselho Nacional de Desenvolvimento Científico e Tecnológico; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; Bioanalytical Facility NEPS-DQ; Fundação de Amparo à Pesquisa do Estado de São Paulo; Fundo de Amparo à Pesquisa do Estado do Rio de Janeiro (award Nos. E-26/010.000978/2019 and E-26/010.1553/2019); Ministerio de Economía y Competitividad (award No. PID201935-GB-I00); Unidad de Excelencia Maria de Maeztu (award No. CEX2019-000919).

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