Cu(II) 3,5-diiodosalicylate complexes: precursor-dependent formation of mono-, di-, tri- and tetranuclear compounds and 1D coordination polymers

Abstract

Reactions of CuCl₂·2H₂O or Cu(NO₃)₂·6H₂O with 3,5-diiodosalicylic acid (DISA) in the presence of different amines result in structurally diverse products. Overall, we isolated 14 complexes of various nuclearity (1, 2, 3 and 4, as well as 1D coordination polymers), all characterized by X-ray diffraction. Magnetic properties were studied for several representatives of this class.

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Introduction

It will not be an exaggeration to state that carboxylate complexes constitute one of the most studied classes of coordination compounds.^1–5 Currently, the number of corresponding structures deposited to the Cambridge Structural Database (CSD) exceeds 14 000, and these are extremely diverse, representing dozens of different structural motifs.^6–12

Within our recent research, we focused on halogen-substituted arenecarboxylates as ligands. On the one hand, these are not uncommon – there are dozens of corresponding complexes. As a single random example, there are 60 (!) compounds with 4-iodobenzoic acid (M = Sn,^13,14 U,^15–17 Cu,^18–20 Ru,²¹ Mo,²² Mn,^23,24 lanthanides,^25,26etc.). However, despite 1) the growing interest on halogen bonding (XB), a specific kind of non-covalent interaction involving halogen atoms,^27–29 and 2) the fact that it can be assumed that such coordination units can be involved in XB formation, these are however rather rarely considered from this point of view. This idea was successfully exploited, e.g., by Brammer et al.,^30–32 but the number of such studies is however rather low.^16,22

Observing the range of potential ligands attractive within the abovementioned context, we noticed that the commercially available 3,5-diiodosalicylic acid (DISA), despite it being a rather widespread and affordable reagent, was rarely used for the design of carboxylate complexes. Filling this gap, we recently prepared a series of corresponding heteroleptic derivatives of Zn(II)³³ – all belonging to the same type (mononuclear) but featuring different patterns of XB in the solid state. Turning to Cu(II) and using trialkylamines as deprotonating agents, we successfully isolated four mono- and dinuclear complexes, all featuring chelate coordination of fully deprotonated DISA.³⁴ However, once we decided to involve different substituted pyridines which can play a dualistic role (both deprotonation of DISA and coordination to a metal center giving a heteroleptic complex), we found that the diversity of products increases dramatically. Depending on the Cu source (nitrate vs. chloride), reagent ratio and other conditions, mono-, bi-, tri- and tetranuclear discrete complexes as well as 1D coordination polymers can be formed. In this work, we summarize our research in this field, discussing the structural features and (where relevant) magnetic behavior of the complexes.

Experimental section

All reagents were obtained from commercial sources and used as purchased. Solvents were purified according to the standard procedures.

Synthesis of 1

44 mg (0.18 mmol) of Cu(NO₃)₂·3H₂O were dissolved in 6 ml of CH₃CN, followed by the addition of a solution of H₂DISA (140 mg, 0.36 mmol) and Py (58 μl, 0.72 mmol) in 5 ml of CH₃CN. Slow evaporation results in the formation of violet crystals of 1. Yield 87%. For C₂₄H₁₆CuI₄N₂O₆ calcd, %: C, 28.84; H, 1.61; N, 2.80; found, %: C, 28.95; H, 1.71; N, 2.89.

Synthesis of 2

19.7 mg (0.12 mmol) of CuCl₂·2H₂O were dissolved in 4 ml of CH₃CN, followed by the addition of a solution of H₂DISA (90 mg, 0.23 mmol) and 2-MePy (45.5 μl, 0.46 mmol) in 5 ml of CH₃CN. Violet crystals of 2 formed within 1 day after slow evaporation of the solvent. Yield 85%. For C₂₆H₂₀CuI₄N₂O₆ calcd, %: C, 30.39; H, 1.96; N, 2.72; found, %: C, 30.51; H, 2.07; N, 2.78.

Synthesis of 3

The procedure was the same as that for 1, using 3-MePy (35 μl, 0.36 mmol) instead of pyridine. Slow evaporation led to the formation of purple plate-like crystals of 3.

Synthesis of 4

27.8 mg (0.12 mmol) of Cu(NO₃)₂·3H₂O were dissolved in 4 ml of CH₃CN, followed by the addition of a solution of H₂DISA (90 mg, 0.23 mmol) and 2-MePy (22.8 μl, 0.23 mmol) in 4 ml of CH₃CN. The next day, upon evaporation, green crystals of 4 suitable for XRD were formed, but the samples were always contaminated by an unidentified brown fine crystalline product.

Synthesis of 5

15.3 mg (0.09 mmol) of CuCl₂·2H₂O were dissolved in 5 ml of CH₃CN, followed by the addition of a solution of H₂DISA (70 mg, 0.18 mmol) and 3-MePy (35.0 μl, 0.36 mmol) in 5 ml of CH₃CN. Upon slow evaporation, blue crystals of 5 formed the next day. Yield 79%. For C₃₈H₃₄Cl₂Cu₂I₄N₄O₆ calcd, %: C, 33.88; H, 2.55; N, 4.16; found, %: C, 33.97; H, 2.65; N, 4.29.

Synthesis of 6

The procedure was the same as that for 5, using 3,4-MePy (40.4 μl, 0.36 mmol) instead of 3-MePy. Slow evaporation (approx. 3 days) led to the formation of blue crystals of 6. Yield 82%. For C₄₂H₄₂Cl₂Cu₂I₄N₄O₆ calcd, %: C, 35.96; H, 3.02; N, 4.00; found, %: C, 36.08; H, 3.10; N, 4.11.

Synthesis of 7

The procedure was the same as that for 5, using 4-MePy (17.5 μl, 0.18 mmol) instead of 3-MePy. Immediately after mixing, a blue precipitate appeared, from which blue crystals of 7 formed after 9 days. Yield 73%. For C₅₀H₄₈Cl₄Cu₃I₄N₆O₆ calcd, %: C, 36.04; H, 2.91; N, 5.05; found, %: C, 35.91; H, 3.00, N, 5.15.

Synthesis of 8

The procedure was the same as that for 5, using 4-EtPy (40.8 μl, 0.36 mmol) instead of 3-MePy. Upon slow evaporation, blue crystals of 8 formed within 1 day. Yield 81%. For Cu₃Cl₄C₅₆I₄O₆H₆₀N₆ calcd, %: C, 38.42; H, 3.46; N, 4.80; found, %: 3, 38.30; H, 3.45; N, 4.87.

Synthesis of 9

7.7 mg (0.03 mmol) of Cu(NO₃)₂·3H₂O were dissolved in 5 ml of CH₃CN, followed by the addition of a solution of H₂DISA (25 mg, 0.05 mmol) and Py (5.4 μl, 0.13 mmol) in 5 ml of CH₃CN. Slow evaporation for several days led to the formation of dark green crystals of 9 with small grains of a lighter color of 4 (as follows from PXRD data).

Synthesis of 10

6.2 mg (0.03 mmol) of Cu(NO₃)₂·3H₂O were dissolved in 5 ml of CH₃CN, followed by the addition of a solution of H₂DISA (20 mg, 0.05 mmol) and 3-MePy (5.0 μl, 0.13 mmol) in 5 ml of CH₃CN. Small green crystals of 10 formed overnight in a closed vial. For C₅₂H₃₆Cu₄I₈N₄O₁₂ calcd, %: C, 28.69; H, 1.67; N, 2.58; found, %: C, 28.74; H, 1.76; N, 2.50.

Synthesis of 11

15.5 mg (0.06 mmol) of Cu(NO₃)₂·3H₂O were dissolved in 5 ml of EtOH, followed by the addition of a solution of H₂DISA (50 mg, 0.13 mmol) and 4-MePy (12.5 μl, 0.13 mmol) in 5 ml of EtOH. Small dark green crystals of 11 formed overnight in a closed vial. For C₅₂H₃₆Cu₄I₈N₄O₁₂ calcd, %: C, 28.69; H, 1.67; N, 2.58; found, %: C, 28.77; H, 1.79; N, 2.64.

Synthesis of 12

15.5 mg (0.06 mmol) of Cu(NO₃)₂·3H₂O were dissolved in 5 ml of CH₃CN, followed by the addition of a solution of H₂DISA (50 mg, 0.13 mmol) and 4-EtPy (14.6 μl, 0.13 mmol) in 5 ml of CH₃CN. Immediately after mixing, a green precipitate appeared, from which green crystals of 12 formed after 2 days. For C₅₆H₄₄Cu₄I₈N₄O₁₂ calcd, %: C, 30.11; H, 1.99; N, 2.51; found, %: C, 30.02; H, 2.06; N, 2.57.

Synthesis of 13

9.3 mg (0.04 mmol) of Cu(NO₃)₂·3H₂O were dissolved in 4 ml of EtOH, followed by the addition of a solution of H₂DISA (30 mg, 0.08 mmol) and 2-MePy (15.2 μl, 0.15 mmol) in 4 ml of EtOH. The next day, dark green crystals of 13 formed in a closed vial.

Synthesis of 14

9.3 mg (0.04 mmol) of Cu(NO₃)₂·3H₂O were dissolved in 5 ml of CH₃CN, followed by the addition of a solution of H₂DISA (30 mg, 0.08 mmol) and 4-MePy (15 μl, 0.15 mmol) in 5 ml of CH₃CN. Slow evaporation over a week led to the formation of small green crystals of 14.

X-ray diffraction

Crystallographic data and refinement details for 1–14 are given in Table S1 (ESI†). For 1–6, 8, and 10, the data were collected on a New Xcalibur (Agilent Technologies) diffractometer with MoK_α radiation (λ = 0.71073) by doing φ scans of narrow (0.5°) frames at 150 K. Absorption correction was done empirically using SCALE3 ABSPACK (CrysAlisPro, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171.NET) (compiled Aug 13 2014, 18:06:01)). For 7, 9, and 11–14, the data were collected on a Bruker D8 Venture diffractometer with a CMOS PHOTON III detector and IμS 3.0 source (Mo Kα radiation, λ = 0.71073 Å) at 150 K. The φ- and ω-scan techniques were employed. Absorption correction was applied using SADABS (Bruker Apex3 software suite: Apex3, SADABS-2016/2 and SAINT, version 2018.7-2; Bruker AXS Inc.: Madison, WI, 2017.). Structures were solved using SHELXT³⁵ and refined by full-matrix least-squares treatment against |F|² in anisotropic approximation with SHELX 2014/7 (ref. 36) in the ShelXle program.³⁷ H-atoms were refined in geometrically calculated positions. Disordering of the coordinated Me-Py molecule over two closed positions in the crystal structure of 1 is a cause for refinement of all participating atoms in isotropic approximation. In the case of 2, 8, 10, 11 and 13, there is some residual electronic density around the I atoms without any chemical sense, reflecting A- and B-type alerts during PLATON check. In all cases, the residual electronic density does not exceed 10% over the total electronic count. The crystallographic data have been deposed in the Cambridge Crystallographic Data Centre under the deposition codes CCDC 2194777–2194790.

Powder X-ray diffraction (PXRD)

XRD analysis of polycrystals was performed on a Shimadzu XRD-7000 diffractometer (CuK-alpha radiation, Ni – filter, linear One Sight detector, 0.0143° 2θ step, 2 s per step). Plotting of the PXRD patterns and data treatment were performed using X'Pert Plus software (see the ESI†).

Magnetic measurements and TGA data

Details are given in the ESI.†

Results and discussion

The list of synthetic procedures given above represents only the optimized procedures for each compound. Behind them, there was an extended set of experiments which we summarized in Table 1. We performed them by varying several parameters: 1) the ratio of reagents, 2) the source of copper (nitrate vs. chloride) and 3) the pyridine ligand (in some cases, we also varied the solvent, as mentioned in Table 1). Interestingly, in the case of 2-MePy, no Cl-containing complex was isolated, regardless of the conditions. It remains unclear what is the driving force favoring the formation of bi- vs. trinuclear complexes (5 and 6vs.7 and 8) – it can be seen that complexes of only one of these types are formed with a certain Py ligand.

Table 1 Products of reactions between Cu(II) salts, H₂DISA and different pyridines

	L	Cu salt	Cu : H2DISA : L	Products	Comments
1	Py	Chloride	1 : 2 : 2	1	Initially forms [Cu2PyCl2]. After filtering off, it crystallizes to pure 1
2	Py	Chloride	1 : 2 : 4	1	See above
3	Py	Nitrate	1 : 2 : 2	9	With minor amounts of 4
4	Py	Nitrate	1 : 2 : 4	1	—
5	2-MePy	Chloride	1 : 2 : 2	2	—
6	2-MePy	Chloride	1 : 2 : 4	2	—
7	2-MePy	Nitrate	1 : 2 : 2	4	Contaminated by unidentified by-products
8	2-MePy	Nitrate	1 : 2 : 4	13
9	2-MePy	Nitrate	1 : 2 : 2	13	EtOH as solvent
10	2-MePy	Nitrate	1 : 2 : 4	13	EtOH as solvent
11	3-MePy	Chloride	1 : 2 : 2	5	—
12	3-MePy	Chloride	1 : 2 : 4	5	—
13	3-MePy	Nitrate	1 : 2 : 2	10	—
14	3-MePy	Nitrate	1 : 2 : 4	3	See 7
15	4-MePy	Chloride	1 : 2 : 2	7	—
16	4-MePy	Chloride	1 : 2 : 4	7	—
17	4-MePy	Nitrate	1 : 2 : 2	11	—
18	4-MePy	Nitrate	1 : 2 : 4	14	See 7
19	4-MePy	Nitrate	1 : 2 : 2	11	EtOH as solvent
20	4-MePy	Nitrate	1 : 2 : 4	11	EtOH as solvent
21	4-EtPy	Chloride	1 : 2 : 2	8	—
22	4-EtPy	Chloride	1 : 2 : 4	8	—
23	4-EtPy	Nitrate	1 : 2 : 2	12	—
24	4-EtPy	Nitrate	1 : 2 : 4	12	—
25	3,4-MePy	Chloride	1 : 2 : 2	6	—
26	3,4-MePy	Chloride	1 : 2 : 4	6	—

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[Cu(HDISA)₂L₂]

There are three complexes of the [Cu(HDISA)₂L₂] type – with L = Py (1), 2-MePy (2) and 3-MePy (3), respectively. The Cu has a square planar coordination environment consisting of two DISA units with a protonated OH group and two pyridines, respectively, in trans-mode (Fig. 1). This structural type was observed earlier in Cu(II) non-substituted^38–41 and substituted^42–45 salicylates. One O atom of each COO⁻ is involved in coordination, while the Cu⋯O(2) distances can rather indicate semi-coordination (Table 2). In 3, the 3-MePy ligands are disordered.

Fig. 1 Structure of 1. Here and below: Cu cyan; N deep blue; I purple; O red; C grey; H atoms are omitted.

Table 2 Cu⋯O and Cu–N distances (Å) in 1–3

Compound	Cu–O(1)	Cu–O(2)	Cu–N
1	1.949	2.632	2.017
2	1.921–1.931	2.851–2.934	1.980–1.981
3	1.987	2.535	1.974–2.015

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In 1, there are both I⋯O and I⋯I interactions (3.417 and 3.761 Å, respectively; Fig. 2) involving 5-I and 3-I substituents, respectively. Such contacts are absent in 2.

Fig. 2 System of I⋯O and I⋯I contacts (dashed lines) in 1.

4 belongs to a very widespread family of paddlewheel-type complexes: the [Cu₂(carboxylate)₄L₂] family.^46–49 Four HDISA units (Cu–O = 1.966 Å) connect two Cu atoms into a binuclear core (Cu⋯Cu = 2.668 Å). The –OH groups of HDISA are disordered over two positions with equal occupancies. The terminal positions at Cu sites are occupied by CH₃CN (Cu–N = 2.168 Å); also, there are solvate acetonitrile molecules in this structure.

[Cu₂L₄(HDISA)₂Cl₂]

These binuclear complexes form in two cases (L = 3-MePy (5) and 3,4-MePy (6)) where CuCl₂ was used as the precursor (see above). The Cu atoms are connected by two μ₂-bridging chlorides (see Table 3 for all bond lengths). The coordination sphere of each Cu is completed by two pyridine ligands and one HDISA coordinated by carboxylate groups (Fig. 3). This structural type is rare for copper(II) carboxylates; there are only two relevant examples⁵⁰ (including those found by us in Cu 2-iodobenzoates⁵¹) with monodentate N-donor ligands and slightly more with bidentate ones.^52–54 There are neither I⋯I nor I⋯O non-covalent interactions in these structures.

Table 3 Cu–O, Cu–N and Cu–Cl bond lengths (Å) in 5–8

Compound	Cu–O	Cu–N	Cu–Cl
5	2.324–2.637	1.998–2.010	2.025
6	2.337–2.641	1.994–2.006	2.026
7	2.292–2.829	1.998–2.031	2.019
8	2.297–2.957	1.985–2.011	2.026

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Fig. 3 Structure of 5. Here and below: Cl light green.

[Cu₃L₆(HDISA)₂Cl₄]

Trinuclear complexes of this family (Fig. 4) can be represented as a derivative of the [Cu₂L₄(HDISA)₂Cl₂] type with a {CuL₂Cl₂} unit “inserted” into the middle of the molecule. This is, to the best of our knowledge, an unprecedented type in Cu carboxylates. We isolated two examples – with L = 4-MePy (7) and 4-EtPy (8). Interestingly, two of the Cu–μ₂–Cl bonds are strongly elongated (2.879 and 2.957 Å in 7 and 8, respectively). In 8, there are weak (3.895 Å) I⋯I contacts between the neighboring molecules.

Fig. 4 Structure of 8.

[Cu₄L₄(DISA)₄]

These neutral complexes were isolated, with L = Py (9), 3-MePy (10), 4-MePy (11) and 4-EtPy (12). These consist of four copper atoms which build a tetrahedron. The DISA molecules are fully deprotonated; both carboxylate and hydroxo O-atoms are involved in coordination so that each DISA acts as a linker for two neighboring Cu centers. The coordination environment of the latter is therefore distorted square planar. Selection of a representative view of these structures is rather challenging so only the essential units are shown in Fig. 5. A summary of bond lengths and distances in 9–12 is given in Table 4. This motif is rare in Cu carboxylates – similar patterns were earlier encountered only in heteroleptic lactate complexes.⁵⁵

Fig. 5 Structure of 9. Only N atoms of the Py ligands and only O and some C atoms of the DISA ligand are shown.

Table 4 Cu–O and Cu–N distances in 9–14

Compound	Cu–O (2-O)	Cu–O (carboxylate)	Cu–N
9	1.889	1.908–1.959	2.000
10	1.884	1.909–1.968	2.007
11	1.890	1.907–1.954	1.986
12	1.890	1.911–1.954	1.985
13	1.863	1.936–1.958	2.008
14	1.885	1.906–2.003	1.988

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{[CuL(DISA)]}_n

In the 1D coordination polymers of this type, the DISA units feature the same coordination mode as those in [Cu₄L₄(DISA)₄] (all O atoms are involved, Fig. 6). Actually, this structure can be considered as a polymeric isomer of the previously considered tetranuclear type. The bond lengths in 13 and 14 (L = 2-MePy or 4-MePy, respectively) are listed in Table 4.

Fig. 6 Structure of 14. Only N atoms of L are shown.

Magnetic properties

We selected several complexes – 1, 2, 5, 8, 11 and 13 – for further in-depth investigation of magnetic properties. For complexes 1 and 2, the μ_eff values at 300 K are 1.89 and 1.82μ_B, respectively, and change slightly with decreasing temperature. The 1/χ(T) dependencies obey the Curie–Weiss law in the temperature range 50–300 K with the best fit values of C and Θ equal to 0.444 ± 0.001 K cm³ mol⁻¹ and 1.2 ± 0.1 K for 1 and 0.413 ± 0.001 K cm³ mol⁻¹ and −0.65 ± 0.07 K for 2. The μ_eff values at 300 K and Curie constants are in good agreement with the theoretical spin-only values of 1.86μ_B and 0.433 K cm³ mol⁻¹ for one Cu(II) ion (S = 1/2, g = 2.15). The Cu(II) ions in complexes 1 and 2 are magnetically isolated in full accordance with X-ray data (Fig. 7). Exchange interactions between spins of Cu(II) ions are negligibly small, and weakly ferromagnetic in the case of 1 (Weiss constant is 1.2 K) and weakly antiferromagnetic in case of complex 2 (Weiss constant is −0.65 K). Temperature dependencies of the effective magnetic moment (μ_eff) and inverse magnetic susceptibility 1/χ for complexes 1 and 2 are shown in the ESI.†

Fig. 7 Temperature dependencies of μ_eff for the complexes 5 (top) and 8 (bottom). Solid lines are theoretical curves.

The μ_eff values at 300 K for complexes 5 and 8 are 2.61 and 3.11μ_B, respectively, and change slightly with decreasing temperature down to 100 K. Below 100 K, the μ_eff decreases and reaches 0.78μ_B and 1.87μ_B at 5 K for 5 and 8, respectively. The μ_eff values at 300 K are in good agreement with the theoretical spin-only values of 2.63μ_B and 3.23μ_B for two and three Cu(II) ions in the case of 5 and 8 respectively. Temperature dependencies of μ_eff are indicative of antiferromagnetic coupling between the spins of Cu(II) ions in 5 and 8. The dimer model (Spin Hamiltonian H = −2JS₁S₂) was used to analyze the experimental μ_eff(T) dependence of 5, because two Cu(II) ions are connected by two μ₂-bridging chlorides. In complex 8, three Cu(II) ions are connected by four μ²-bridging chlorides, so the trimer model (Spin Hamiltonian H = −2J(S₁S₂+ S₂S₃)) was used. The best fit values of the g-factor and exchange coupling parameter J are 2.14 ± 0.01 and −6.9 ± 0.1 cm⁻¹ for complex 5 and 2.10 ± 0.01 and −5.8 ± 0.1 cm⁻¹ for complex 8.

The μ_eff value for 11 at 300 K is 3.81μ_B and is in good agreement with the theoretical one of 3.72μ_B for four Cu(II) ions. The μ_eff increases with decreasing temperature and reaches 4.94μ_B at 6 K. A tetramer model (Spin Hamiltonian H = −2J(S₁S₂ + S₂S₃ + S₃S₄ + S₁S₄)) describes well the experimental μ_eff(T) dependence with the best fit values of g-factor and exchange coupling parameter J equal to 2.15 ± 0.01 and 7.6 ± 0.1 cm⁻¹. Intermolecular exchange interactions are very weak, zJ′’ = −0.05 ± 0.01 cm⁻¹, but should be taken into account to describe the μ_eff(T) dependence properly at low temperatures.

For the 1D coordination polymer complex 13, the μ_eff value at 300 K is 1.81μ_B and changes slightly with decreasing temperature down to 100 K. Below 100 K, the μ_eff increases and reaches 2.47μ_B at 5 K, which indicates the predomination of ferromagnetic exchange interactions between spins of Cu(II) ions in 13. Analysis of the experimental μ_eff(T) dependence was performed using the uniform chain model (Spin Hamiltonian H = −2J ∑S_iS_i+1) in the finite chain approximations. The best fit values of g-factor and exchange coupling parameter J are 2.05 ± 0.01 and 5.1 ± 0.2 cm⁻¹.

Overall, the magnetic structures of all investigated complexes are correlated with the structural motifs. Weak ferromagnetic exchange interactions dominate in 11 and 13, whereas in complexes 5 and 8, with μ₂-bridging chlorides between Cu(II) ions, exchange interactions are antiferromagnetic in character.

Additionally, we performed TGA for the complexes isolated as pure phases. These data are summarized in the ESI.†

Conclusions

We demonstrated that 3,5-diiodosalicylate and Cu(II) in the presence of auxiliary ligands can undergo self-assembly into complexes of different nuclearity and geometries, including also 1D coordination polymers. Additionally, there often appear systems of halogen bonds in the solid state which, however, do not have a direct influence on the magnetic properties (these are governed by the molecular structures).

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

This research was funded by the Russian Foundation for Basic Research, Grant No. 20-33-70010, and partially supported by the Ministry of Science and Higher Education of the Russian Federation (structural characterization of the samples, 121031700313-8).

Notes and references

1. B.-H. Ye, M.-L. Tong and X.-M. Chen, Coord. Chem. Rev., 2005, 249, 545–565.
2. T. Loiseau, I. Mihalcea, N. Henry and C. Volkringer, Coord. Chem. Rev., 2014, 266–267, 69–109.
3. Y.-Z. Zheng, Z. Zheng and X.-M. Chen, Coord. Chem. Rev., 2014, 258–259, 1–15.
4. Y. A. Belousov, A. A. Drozdov, I. V. Taydakov, F. Marchetti, R. Pettinari and C. Pettinari, Coord. Chem. Rev., 2021, 445, 214084.
5. M. A. Kiskin and I. L. Eremenko, Russ. Chem. Rev., 2006, 75, 559–575.
6. I. A. Lutsenko, M. A. Kiskin, S. A. Nikolaevskii, A. A. Starikova, N. N. Efimov, A. V. Khoroshilov, A. S. Bogomyakov, I. V. Ananyev, J. K. Voronina, A. S. Goloveshkin, A. A. Sidorov and I. L. Eremenko, ChemistrySelect, 2019, 4, 14261–14270.
7. S. A. Nikolaevskii, D. S. Yambulatov, A. A. Starikova, A. A. Sidorov, M. A. Kiskin and I. L. Eremenko, Russ. J. Coord. Chem., 2020, 46, 260–267.
8. N. V. Gogoleva, M. A. Shmelev, I. S. Evstifeev, S. A. Nikolaevskii, G. G. Aleksandrov, M. A. Kiskin, Z. V. Dobrokhotova, A. A. Sidorov and I. L. Eremenko, Russ. Chem. Bull., 2016, 65, 181–190.
9. K. A. Yashkova, S. N. Mel'nikov, S. A. Nikolaevskii, M. A. Shmelev, A. A. Sidorov, M. A. Kiskin and I. L. Eremenko, J. Struct. Chem., 2021, 62, 1378–1384.
10. G. N. Kuznetsova, S. A. Nikolaevskii, D. S. Yambulatov, M. A. Shmelev, M. A. Kiskin, A. G. Starikov, A. A. Sidorov and I. L. Eremenko, J. Struct. Chem., 2021, 62, 184–195.
11. D. S. Yambulatov, S. A. Nikolaevskii, M. A. Shmelev, K. A. Babeshkin, D. V. Korchagin, N. N. Efimov, A. S. Goloveshkin, P. A. Petrov, M. A. Kiskin, M. N. Sokolov, M. N. Sokolov and I. L. Eremenko, Mendeleev Commun., 2021, 31, 624–627.
12. E. S. Bazhina, M. A. Shmelev, A. A. Korlyukov, M. A. Kiskin and I. L. Eremenko, Russ. J. Coord. Chem., 2021, 47, 105–116.
13. X.-M. Zhu, Y.-L. Feng, F.-X. Zhang, J.-X. Yu, W.-J. Jiang, Y.-X. Tan, Z.-J. Zhang and D.-Z. Kuang, Chin. J. Inorg. Chem., 2015, 31, 761–766.
14. J. Rani, G. Kaur, Diksha Sushila, R. Yadav, R. Kataria, P. Venugopalan, P. Natarajan, A. Chaudhary and R. Patra, CrystEngComm, 2019, 21, 1150–1158.
15. N. P. Deifel and C. L. Cahill, Chem. Commun., 2011, 47, 6114–6116.
16. J. A. Ridenour, M. H. Schofield and C. L. Cahill, Cryst. Growth Des., 2020, 20, 1311–1318.
17. M. Kalaj, K. P. Carter and C. L. Cahill, Eur. J. Inorg. Chem., 2017, 2017, 4702–4713.
18. K. Takahashi, N. Hoshino, T. Takeda, K. Satomi, Y. Suzuki, S.-I. Noro, T. Nakamura, J. Kawamata and T. Akutagawa, Dalton Trans., 2016, 45, 3398–3406.
19. M. I. Mohamadin, N. Abdullah, K. M. Lo and S. W. Ng, Acta Crystallogr., Sect. E: Struct. Rep. Online, 2010, 66, m1530.
20. A. D. Burrows, M. F. Mahon, P. R. Raithby, A. J. Warren, S. J. Teat and J. E. Warren, CrystEngComm, 2012, 14, 3658–3666.
21. Q. Guo, J. Dou, L. Wu, D. Li and D. Wang, J. Coord. Chem., 2007, 60, 785–794.
22. M. H. Chisholm, C. B. Durr, T. F. Spilker and P. J. Young, Inorg. Chim. Acta, 2015, 424, 300–307.
23. M. Hołyńska and S. Dehnen, Z. Anorg. Allg. Chem., 2012, 638, 763–769.
24. M. Hołyńska and S. Dehnen, Inorg. Chem. Commun., 2011, 14, 1290–1293.
25. J. H. S. K. Monteiro, A. De Bettencourt-Dias, I. O. Mazali and F. A. Sigoli, New J. Chem., 2015, 39, 1883–1891.
26. J. August Ridenour, K. P. Carter and C. L. Cahill, CrystEngComm, 2017, 19, 1190–1203.
27. G. R. Desiraju, P. S. Ho, L. Kloo, A. C. Legon, R. Marquardt, P. Metrangolo, P. Politzer, G. Resnati and K. Rissanen, Pure Appl. Chem., 2013, 85, 1711–1713.
28. P. Varadwaj, A. Varadwaj, H. Marques, P. R. Varadwaj, A. Varadwaj and H. M. Marques, Inorganics, 2019, 7, 40.
29. G. Cavallo, P. Metrangolo, R. Milani, T. Pilati, A. Priimagi, G. Resnati and G. Terraneo, Chem. Rev., 2016, 116, 2478–2601.
30. P. Smart, G. M. Espallargas and L. Brammer, CrystEngComm, 2008, 10, 1335–1344.
31. P. Smart, Á. Bejarano-Villafuerte, R. M. Hendry and L. Brammer, CrystEngComm, 2013, 15, 3160.
32. P. Smart, Á. Bejarano-Villafuerte and L. Brammer, CrystEngComm, 2013, 15, 3151–3159.
33. M. A. Bondarenko, M. I. Rakhmanova, P. E. Plyusnin, P. A. Abramov, A. S. Novikov, K. Rajakumar, M. N. Sokolov and S. A. Adonin, Polyhedron, 2021, 194, 114895.
34. M. A. Bondarenko, A. S. Novikov, T. S. Sukhikh, I. V. Korolkov, M. N. Sokolov and S. A. Adonin, J. Mol. Struct., 2021, 1244, 130942.
35. G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Adv., 2015, 71, 3–8.
36. G. M. Sheldrick, Acta Crystallogr., Sect. C: Struct. Chem., 2015, 71, 3–8.
37. C. B. Hübschle, G. M. Sheldrick and B. Dittrich, J. Appl. Crystallogr., 2011, 44, 1281–1284.
38. A. L. Abuhijleh and C. Woods, Inorg. Chem. Commun., 2001, 4, 119–123.
39. L.-G. Zhu and S. Kitagawa, Z. fur Krist. – New Cryst. Struct., 2002, 217, 579–580.
40. I. Leban, B. Kozlevčar, J. Sieler and P. Šegedin, Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1997, 53, 1420–1422.
41. M. Devereux, D. O'Shea, M. O'Connor, H. Grehan, G. Connor, M. McCann, G. Rosair, F. Lyng, A. Kellett, M. Walsh, D. Egan and B. Thati, Polyhedron, 2007, 26, 4073–4084.
42. F. T. Greenaway, A. Pezeshk, A. W. Cordes, M. C. Noble and J. R. J. Sorenson, Inorg. Chim. Acta, 1984, 93, 67–71.
43. Z. Ma and B. Moulton, Mol. Pharmaceutics, 2007, 4, 373–385.
44. Y. Wang, X.-M. Lin, F.-Y. Bai, R. Zhang and X.-X. Zhang, Chin. J. Inorg. Chem., 2017, 33, 1667–1677.
45. M. Puchoňová, J. Švorec, Ľ. Švorc, J. Pavlik, M. Mazúr, Ľ. Dlháň, Z. Růžičková, J. Moncoľ and D. Valigura, Inorg. Chim. Acta, 2017, 455, 298–306.
46. D. S. Yambulatov, S. A. Nikolaevskii, I. A. Lutsenko, M. A. Kiskin, M. A. Shmelev, O. B. Bekker, N. N. Efimov, E. A. Ugolkova, V. V. Minin, A. A. Sidorov, A. A. Sidorov and I. L. Eremenko, Russ. J. Coord. Chem., 2020, 46, 772–778.
47. L. D. Popov, S. A. Borodkin, M. A. Kiskin, A. A. Pavlov, N. N. Efimov, E. A. Ugolkova, V. V. Minin and I. N. Shcherbakov, Russ. J. Coord. Chem., 2022, 48, 75–83.
48. I. A. Lutsenko, M. E. Nikiforova, K. A. Koshenskova, M. A. Kiskin, Y. V. Nelyubina, P. V. Primakov, M. V. Fedin, O. B. Becker, V. O. Shender, I. K. Malyants, I. K. Malyants and I. L. Eremenko, Russ. J. Coord. Chem., 2021, 47, 881–890.
49. M. A. Uvarova and S. E. Nefedov, Russ. J. Coord. Chem., 2021, 47, 399–408.
50. E. Dilek, S. Caglar, S. Çardak, B. Karakoç, B. Caglar and O. Sahin, Arch. Pharm., 2019, 352(6), 1900007.
51. M. A. Bondarenko, A. S. Novikov, I. V. Korolkov, M. N. Sokolov and S. A. Adonin, Inorg. Chim. Acta, 2021, 524, 120436.
52. H. Jiang, J.-F. Ma and W.-L. Zhang, Acta Crystallogr., Sect. E: Struct. Rep. Online, 2007, 63, m1681.
53. C. J. Lin, Y. Q. Zheng, D. Y. Zhang and W. Xu, Russ. J. Coord. Chem., 2014, 40, 932–942.
54. G. H. Shahverdizadeh, S. W. Ng, E. R. T. Tiekink and B. Mirtamizdoust, Acta Crystallogr., Sect. E: Struct. Rep. Online, 2012, 68, m242–m243.
55. S. Balboa, J. Borrás, P. Brandi, R. Carballo, A. Castiñeiras, A. B. Lago, J. Niclós-Gutiérrez and J. A. Real, Cryst. Growth Des., 2011, 11, 4344–4352.

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Footnote

† Electronic supplementary information (ESI) available: XRD, PXRD and magnetic measurement details. CCDC 2194777–2194790. For ESI and crystallographic data in CIF or other electronic format see DOI: https://doi.org/10.1039/d2ce01393b

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