Crystal structure, Hirshfeld surface and energy framework analysis of bis­{3-(benzo­furan-6-yl)-5-[6-(1H-pyrazol-1-yl)pyridin-2-yl]-1H-1,2,4-triazol-1-ido}iron(II) methanol disolvate

Terpeliuk, I.; Znovjyak, K.; Shova, S.; Oksiuta, O.V.; Amirkhanov, V.M.; Fritsky, I.O.; Seredyuk, M.

doi:10.1107/S2056989025008655

research communications

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 81| Part 11| November 2025| Pages 991-995

https://doi.org/10.1107/S2056989025008655

Open

access

Crystal structure, Hirshfeld surface and energy framework analysis of bis{3-(benzofuran-6-yl)-5-[6-(1H-pyrazol-1-yl)pyridin-2-yl]-1H-1,2,4-triazol-1-ido}iron(II) methanol disolvate

Illia Terpeliuk,^a Kateryna Znovjyak,^a Sergiu Shova,^b Olexandr V. Oksiuta,^c Vladimir M. Amirkhanov,^a Igor O. Fritsky ^a and Maksym Seredyuk ^a ^*

^aDepartment of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska Street 64, Kyiv, 01601, Ukraine, ^bDepartment of Inorganic Polymers, "Petru Poni" Institute of Macromolecular, Chemistry, Romanian Academy of Science, Aleea Grigore Ghica Voda 41-A, Iasi, 700487, Romania, and ^cInstitute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Academik Kukhar Street, 02094, Kyiv, Ukraine
^*Correspondence e-mail: [email protected]

Edited by A. Briceno, Venezuelan Institute of Scientific Research, Venezuela (Received 20 August 2025; accepted 2 October 2025; online 7 October 2025)

The title compound, [Fe(C₁₈H₁₁N₆O)₂]·2CH₃OH, crystallizes in the orthorhombic space group Pbcn (No. 60) with half of the complex molecule and a methanol molecule in the asymmetric unit. In the complex, the two tridentate 3-(benzofuran-6-yl)-5-[6-(1H-pyrazol-1-yl)pyridin-2-yl]-4H-1,2,4-triazol ligands meridionally bind to the central Fe^II ion through the N atoms of the heterocyclic groups, forming a pseudo-octahedral coordination sphere. In the crystal, C—H(pz)⋯π(ph) and C—H⋯N/C/O interactions consolidate the structure. Energy framework analysis at the B3LYP/6–31 G(d,p) theory level was performed to quantify the interaction energies in the crystal.

Keywords: crystal structure; iron(II) complexes; neutral complexes; tridentate ligands.

CCDC reference: 2492851

1. Chemical context

3d-Metal complexes featuring tridentate bisazolepyridine ligands constitute a versatile class of coordination compounds with applications in biochemistry (Fares et al. 2020 ), catalysis (Wei et al., 2015 ) and molecular magnetism (Halcrow 2024 ). For ligands with asymmetric architectures, where one azole moiety bears a protonated nitrogen heteroatom, deprotonation can balance the charge of the central metal ion, yielding neutral complexes. In this case, the peripheral substituents on the neutral complexes influence intermolecular interactions, which in turn affect the connectivity, binding energy, crystal packing, and the coordination environment of the central ion.

Given the prominence of bisazolepyridines as ligands in the Fe^II spin-crossover domain, and motivated by our longstanding interest in complexes of 3d-metals with N-heterocyclic ligands (Seredyuk et al., 2007 ; Bonhommeau et al., 2012 ; Piñeiro-López et al., 2018 ), herein we report a new neutral low-spin complex based on the asymmetric ligand 3-(benzofuran-6-yl)-5-[6-(1H-pyrazol-1-yl)pyridin-2-yl]-4H-1,2,4-triazol. This study details the synthesis and crystal structure of the title compound, incorporating benzofuran groups to tune intermolecular interactions.

2. Structural commentary

The title compound, [Fe(C₁₈H₁₁N₆O)₂]·2CH₃OH, crystallizes in the orthorhombic space group Pbcn (No. 60) with half of the complex molecule and a methanol molecule in the asymmetric unit. In the complex, the two ligands meridionally bind to the central Fe^II ion, which lies on a twofold rotation axis through the N atoms of the heterocyclic groups, forming a pseudo-octahedral coordination sphere. The benzofuran group of the ligand is rotated by 16.2 (2)° relative to the almost planar pyrazole-pyridine-triazole (pz-py-trz) fragment (r.m.s. deviation = 0.055 Å). The methanol molecule forms hydrogen bonds with the trz rings (Fig. 1). The central Fe ion has a distorted octahedral N₆ coordination environment formed by the nitrogen donor atoms of the tridentate ligands. The average bond length iron–nitrogen (<Fe—N>) of 1.957 (2) Å and the volume of the [FeN₆] coordination polyhedron of 9.64 Å³ are small and afor the low-spin state of the central ion (Gütlich & Goodwin, 2004 ). The average trigonal distortion parameters Σ = Σ₁¹²(|90 − ϕ_i|), where ϕ_i is the angle N—Fe—N′, and Θ = Σ₁²⁴(|60 − θ_i|), where θ_i is the angle generated by superposition of two opposite faces of an octahedron, are 90.9 and 315.2°, respectively. The calculated continuous shape measure [CShM(O_h)] value relative to the ideal octahedral symmetry is 2.300 (Kershaw Cook et al., 2015 ). The values indicate a pseudo-octahedral coordination environment [for an ideal octahedron Σ = Θ = CShM(O_h) = 0].

Figure 1
The molecular structure in the asymmetric unit of the title compound and contact atoms with displacement ellipsoids drawn at the 40% probability level. The second ligand is shown in wireframe style for clarity. The strong O—H⋯N (red) and weak C—H⋯N/C/O/π (green) hydrogen bonds are shown with the nearest neighbours. Symmetry codes: (i) 1 − x, 1 + y, $[{1\over 2}]$ − z; (ii) $[{1\over 2}]$ + x, $[{1\over 2}]$ + y, $[{1\over 2}]$ − z; (iii) 1 − x, y, $[{1\over 2}]$ − z; (iv) $[{3\over 2}]$ − x, − $[{1\over 2}]$ + y, z; (v) $[{1\over 2}]$ + x, − $[{1\over 2}]$ + y, $[{1\over 2}]$ − z; (vi) $[{1\over 2}]$ + x, $[{1\over 2}]$ − y, 1 − z; (vii) 1 − x, 1 − y, 1 − z; (viii) 1 − x, y, $[{1\over 2}]$ − z.

3. Supramolecular features

In the crystal, the molecules interlock by inserting the narrower end of one into the wider end of another, and interact through weak C—H(pz)⋯π(ph) intermolecular contacts between the pyrazole and phenyl groups [the H2/C2⋯Cg(ph) distance is 2.550 (2)/3.489 (2) Å]. The formed supramolecular chains extend along the b-axis direction with a stacking periodicity of 10.5670 (1) Å (Fig. 2). Weak intermolecular C—H(pz, py)⋯N/C(pz, trz) interactions, ranging from 3.189 (2) to 3.695 (2) Å (Table 1), connect neighbouring chains into layers propagating in the ab plane. The voids between the layers are occupied by methanol molecules, which also participate in the bonding within separate layers. The methanol molecules form a strong O—H⋯N5 hydrogen bond with the deprotonated trz groups and weak C—H⋯O hydrogen bonds with the pz and py groups of the ligand. A complete list of selected intermolecular interactions is provided in Table 1.

Table 1
Hydrogen-bond and short contact geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2A⋯N5	0.85 (3)	1.89 (2)	2.750 (2)	178 (3)
C1—H1⋯N6ⁱ	0.95	2.27	3.189 (2)	163
C3—H3⋯O2ⁱⁱ	0.95	2.29	3.208 (2)	161
C5—H5⋯O2ⁱⁱ	0.95	2.46	3.386 (2)	164
C5—H5⋯N5ⁱⁱ	0.95	1.90	3.463 (2)	129
C7—H7⋯C1ⁱⁱⁱ	0.95	2.63	3.537 (2)	159
C19—H19A⋯N2^iv	0.97	2.74	3.491 (2)	133
C19—H19A⋯C3^iv	0.97	2.89	3.695 (2)	140
C6⋯C3^v	–	–	3.482 (2)	–
C7⋯C3^v	–	–	3.498 (2)	–
Symmetry codes: (i) $[x-{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) $[-x+1, y, -z+{\script{1\over 2}}]$ ; (v) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z]$ .

Figure 2
(a) A fragment of supramolecular column formed by stacking of molecules along the b axis; (b) Supramolecular layers formed by stacking of the supramolecular columns in the ab plane (for a better representation, each column has a different colour). Hydrogen atoms, except those in pz-groups participating in C–H⋯Cg(π) interactions, are omitted for clarity; (c) Stacking of the layers along the b axis direction with the methanol molecules in the voids. Hydrogen atoms are omitted for clarity.

Hirshfeld surface analysis was conducted for the complex to gain a deeper understanding of the interactions. These interactions are visualized as red (d_norm< vdW radii), white (d_norm= vdW radii), and blue (d_norm> vdW radii) spots on the d_norm surface for the compound along with fingerprint plots mapped with d_norm (where d_norm= d_i+ d_e) and decomposed to the separate contributions (Fig. 3a–c). At 39.9%, the largest contribution to the overall crystal packing is from H⋯H interactions, which are located in the middle region of the fingerprint plot. H⋯C contacts contribute 29.8%, and H⋯O 7.7%, resulting in pairs of characteristic wings. The H⋯N contacts, represented by a pair of sharp spikes in the fingerprint plot, make a 13.2% contribution to the surface.

Figure 3
(a) A projection of d_norm mapped on the Hirshfeld surface identifying contact points or areas for intermolecular interactions on the molecule; (b) decomposition of the projection d_norm into the specific intermolecular interactions; (c) decomposition of the two-dimensional fingerprint plot into specific interactions.

The energy framework (Spackman et al., 2021 ), was calculated based on the wave function at the B3LYP/6-31G(d,p) theory level. This framework includes components such as electrostatic (E_ele), polarization (E_pol), repulsion (E_rep), and dispersion (E_dis) interactions. The latter dominate the contributions, underscoring their primary role for neutral molecules in the crystal structure. The total energy diagram (E_tot) overlaid with a fragment of the crystal structure is built using cylindrical bonds between centroids of molecules, where the radii are proportional to the relative interaction strengths (Fig. 4a–c). The overall topology of the energy framework mirrors the interaction patterns both within and between layers, as outlined earlier. Quantitatively, the E_tot for intrachain interactions is −50.1 kJ mol⁻¹, while interchain interactions reach values as low as −81.8 kJ mol⁻¹. Interlayer interactions, in contrast, have an energy as low as −12.2 kJ mol⁻¹. The figure also shows colour-coding of the interactions around a central reference molecule, along with a table of the individual contributions to E_tot.

Figure 4
(a) The calculated energy frameworks, showing the total energy diagrams (E_tot); (b) decomposition of the energy framework into the part corresponding to the intralayer interactions and (c) interlayer interactions. In the table, the corresponding colour-coded energy values E_tot are provided, including their E_ele, E_pol, E_dis, and E_rep components. Tube size is set at 100 scale.

4. Database survey

A search of the Cambridge Structural Database (CSD, Version 5.42, last update April 2025; Groom et al., 2016 ) reveals several low-spin neutral Fe^II complexes based on asymmetric bisazolpyridines. The selected representative compound for different pairs of azol-azol substituents are ABUFOV (Rajnák et al., 2017 ), BEJQOA (Seredyuk et al., 2022 ), BOWRIR (Senthil Kumar et al., 2020 ) and XODCEB (Shiga et al., 2019 ). Table 2 collates some key structural parameters of the complexes. Compared to the title compound, the surveyed complexes generally do not bear voluminous substituents and exhibit lower coordination sphere distortion parameters, suggesting that the bulky benzofuran group, rigidly linked to the donor groups in the present ligand, likely induces greater deviation from an ideal octahedral geometry. This observation underscores the significant influence of peripheral substituents on the structural properties of such complexes.

Table 2
Computed distortion indices (Å, °) for the title compound and for similar complexes reported in the literature.

CSD Refcode	azol 1/azol 2	<Fe—N>	Σ	Θ	CShM(O_h)
Title compound	1,2,4-triazole/pyrazole	1.957	90.9	315.2	2.300
BEJQOA	1,2,4-triazole/pyrazole	1.946	87.5	308.9	2.163
ABUFOV	benzimidazole/benzimidazole	1.937	80.1	262.7	1.753
BOWRIR	tetrazole/pyrazole	1.934	89.7	287.4	2.043
XODCEB	benzimidazole/pyrazole	1.950	87.5	276.6	1.925

5. Synthesis and crystallization

The synthesis of the title compound followed the protocol reported for a similar complex (Seredyuk et al., 2022). It was produced by a layering technique in a standard test tube. The layering sequence was as follows: the bottom layer contained a solution of [Fe(L₂)](BF₄)₂ prepared by dissolving L = 3-(benzofuran-6-yl)-5-[6-(1H-pyrazol-1-yl)pyridin-2-yl]-4H-1,2,4-triazol (100 mg, 0.304 mmol) and Fe(BF₄)₂·6H₂O (51 mg, 0.152 mmol) in boiling acetone, to which chloroform (5 ml) was then added. The middle layer was a methanol–chloroform mixture (1:10; 10 ml), which was covered by a layer of methanol (10 ml), to which 100 µl of NEt₃ was added dropwise. The tube was sealed, and dark-red plate-like single crystals appeared after 3–4 weeks (yield ca. 80%). Elemental analysis calculated for C₃₈H₃₀FeN₁₂O₄: C, 58.92; H, 3.90; N, 21.70. Found: C, 59.14; H, 3.97; N, 22.05.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The hydrogen atom H2A was refined freely, other H atoms were refined as riding [C—H = 0.95–0.98 Å with U_iso(H) = 1.2–1.5U_eq(C)].

Table 3
Experimental details

Crystal data
Chemical formula	[Fe(C₁₈H₁₁N₆O)₂]·2CH₄O
M_r	774.59
Crystal system, space group	Orthorhombic, Pbcn
Temperature (K)	100
a, b, c (Å)	12.64747 (16), 10.56703 (12), 26.4991 (4)
V (Å³)	3541.51 (8)
Z	4
Radiation type	Cu Kα
μ (mm⁻¹)	3.92
Crystal size (mm)	0.2 × 0.10 × 0.02

Data collection
Diffractometer	Rigaku R-AXIS Spider
Absorption correction	Multi-scan (CrysAlis PRO; Rigaku OD, 2024 )
T_min, T_max	0.534, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	14149, 3464, 3112
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.632

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.097, 1.05
No. of reflections	3464
No. of parameters	267
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.38, −0.30
Computer programs: CrysAlis PRO (Rigaku OD, 2024), OLEX2.solve 1.5 (Bourhis et al., 2015 ), SHELXL2018/3 (Sheldrick, 2015 ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 2492851

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989025008655/zn2044sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989025008655/zn2044Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989025008655/zn2044Isup3.cdx

checkCIF report

Computing details top

Bis{3-(benzofuran-6-yl)-5-[6-(1H-pyrazol-1-yl)pyridin-2-yl]-1H-1,2,4-triazol-1-ido}iron(II) methanol disolvate top

Crystal data top

[Fe(C₁₈H₁₁N₆O)₂]·2CH₄O	D_x = 1.453 Mg m⁻³
M_r = 774.59	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, Pbcn	Cell parameters from 1992 reflections
a = 12.64747 (16) Å	θ = 2.6–21.9°
b = 10.56703 (12) Å	µ = 3.92 mm⁻¹
c = 26.4991 (4) Å	T = 100 K
V = 3541.51 (8) Å³	Plate, clear dark red
Z = 4	0.2 × 0.1 × 0.02 mm
F(000) = 1600

Data collection top

Rigaku R-AXIS Spider diffractometer	3464 independent reflections
Radiation source: sealed X-ray tube	3112 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.035
ω scans	θ_max = 77.0°, θ_min = 3.3°
Absorption correction: multi-scan (CrysAlisPro; Rigaku OD, 2024)	h = −14→15
T_min = 0.534, T_max = 1.000	k = −10→12
14149 measured reflections	l = −32→31

Refinement top

Refinement on F²	Primary atom site location: iterative
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) = 0.097	w = 1/[σ²(F_o²) + (0.0512P)² + 1.8481P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max = 0.001
3464 reflections	Δρ_max = 0.38 e Å⁻³
267 parameters	Δρ_min = −0.30 e Å⁻³
0 restraints

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
Fe1	0.500000	0.71753 (3)	0.250000	0.01699 (12)
N2	0.60321 (11)	0.88309 (13)	0.18316 (5)	0.0211 (3)
N5	0.51474 (11)	0.50739 (14)	0.33332 (6)	0.0212 (3)
N1	0.50229 (10)	0.84881 (14)	0.19681 (6)	0.0201 (3)
N6	0.69158 (11)	0.47812 (14)	0.32708 (6)	0.0248 (3)
O2	0.33165 (11)	0.58628 (13)	0.37969 (6)	0.0337 (3)
H2A	0.388 (2)	0.560 (3)	0.3652 (11)	0.051*
C10	0.60031 (14)	0.44450 (16)	0.34999 (7)	0.0234 (4)
N4	0.55298 (11)	0.58772 (13)	0.29740 (5)	0.0200 (3)
O1	0.76510 (15)	0.11184 (16)	0.45227 (8)	0.0592 (5)
N3	0.64849 (12)	0.72535 (13)	0.23605 (6)	0.0192 (3)
C3	0.60208 (15)	0.97836 (16)	0.14857 (7)	0.0252 (4)
H3	0.661738	1.018159	0.133646	0.028 (5)*
C1	0.43939 (14)	0.92266 (16)	0.16998 (7)	0.0231 (4)
H1	0.364343	0.920088	0.171141	0.018 (5)*
C9	0.65775 (14)	0.56733 (16)	0.29510 (7)	0.0219 (4)
C14	0.59610 (19)	0.17309 (18)	0.46954 (7)	0.0370 (5)
C15	0.50599 (18)	0.2460 (2)	0.46065 (8)	0.0368 (5)
H15	0.444813	0.236306	0.481086	0.034 (6)*
C11	0.59762 (15)	0.34926 (16)	0.39076 (7)	0.0255 (4)
C4	0.68561 (14)	0.81295 (16)	0.20461 (6)	0.0209 (3)
C8	0.71692 (14)	0.64890 (16)	0.26088 (7)	0.0216 (4)
C2	0.49829 (14)	1.00533 (19)	0.13958 (7)	0.0264 (4)
H2	0.471293	1.067668	0.117193	0.035 (6)*
C13	0.68376 (18)	0.19108 (19)	0.43879 (8)	0.0375 (5)
C5	0.79190 (14)	0.83074 (17)	0.19502 (7)	0.0249 (4)
H5	0.816012	0.894204	0.172386	0.035 (6)*
C6	0.86160 (14)	0.75147 (18)	0.22005 (8)	0.0279 (4)
H6	0.935455	0.759817	0.214414	0.028 (5)*
C12	0.68793 (17)	0.27699 (18)	0.39928 (9)	0.0349 (5)
H12	0.749420	0.286094	0.379018	0.035 (6)*
C19	0.3624 (2)	0.6729 (2)	0.41714 (9)	0.0448 (6)
H19A	0.408898	0.737042	0.402292	0.068 (9)*
H19B	0.400247	0.628001	0.443998	0.064 (9)*
H19C	0.299544	0.713942	0.431245	0.071 (10)*
C7	0.82468 (16)	0.65977 (19)	0.25333 (7)	0.0273 (4)
H7	0.872601	0.605658	0.270552	0.029 (5)*
C16	0.50739 (16)	0.33329 (19)	0.42130 (8)	0.0303 (4)
H16	0.446288	0.383066	0.414909	0.031 (6)*
C18	0.6261 (3)	0.0745 (2)	0.50447 (9)	0.0503 (7)
H18	0.583948	0.039318	0.530606	0.066 (9)*
C17	0.7255 (3)	0.0429 (2)	0.49248 (11)	0.0611 (8)
H17	0.764801	−0.020237	0.509770	0.073 (10)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Fe1	0.0157 (2)	0.0172 (2)	0.0181 (2)	0.000	−0.00027 (13)	0.000
N2	0.0203 (7)	0.0218 (7)	0.0213 (7)	0.0000 (6)	0.0010 (6)	0.0024 (6)
N5	0.0224 (7)	0.0200 (7)	0.0212 (7)	−0.0031 (6)	0.0002 (6)	0.0033 (6)
N1	0.0184 (7)	0.0204 (7)	0.0214 (7)	0.0004 (5)	0.0001 (5)	−0.0016 (6)
N6	0.0224 (7)	0.0235 (7)	0.0286 (8)	0.0000 (6)	−0.0013 (6)	0.0059 (6)
O2	0.0288 (7)	0.0369 (7)	0.0354 (8)	−0.0025 (6)	0.0023 (6)	−0.0099 (6)
C10	0.0232 (9)	0.0212 (8)	0.0258 (9)	−0.0024 (7)	−0.0018 (7)	0.0017 (7)
N4	0.0183 (7)	0.0194 (7)	0.0222 (7)	−0.0020 (5)	−0.0005 (5)	0.0014 (6)
O1	0.0574 (11)	0.0473 (9)	0.0729 (12)	0.0010 (8)	−0.0213 (9)	0.0316 (9)
N3	0.0193 (7)	0.0188 (7)	0.0195 (7)	−0.0009 (6)	−0.0001 (6)	0.0003 (5)
C3	0.0303 (9)	0.0224 (8)	0.0229 (9)	0.0005 (7)	0.0014 (7)	0.0047 (7)
C1	0.0230 (9)	0.0233 (8)	0.0230 (8)	0.0041 (7)	−0.0019 (7)	−0.0016 (7)
C9	0.0211 (8)	0.0211 (8)	0.0234 (8)	0.0002 (7)	−0.0014 (7)	0.0028 (7)
C14	0.0639 (15)	0.0252 (9)	0.0218 (9)	−0.0096 (10)	−0.0079 (9)	0.0020 (7)
C15	0.0570 (15)	0.0290 (10)	0.0243 (10)	−0.0052 (9)	0.0058 (9)	0.0013 (8)
C11	0.0314 (10)	0.0217 (8)	0.0234 (9)	−0.0050 (7)	−0.0053 (7)	0.0025 (7)
C4	0.0227 (9)	0.0207 (8)	0.0193 (8)	0.0009 (7)	−0.0007 (7)	0.0009 (6)
C8	0.0210 (8)	0.0209 (8)	0.0230 (8)	0.0014 (7)	−0.0014 (7)	0.0011 (7)
C2	0.0309 (10)	0.0257 (9)	0.0228 (9)	0.0052 (7)	−0.0017 (7)	0.0028 (7)
C13	0.0442 (12)	0.0278 (9)	0.0405 (12)	−0.0042 (9)	−0.0168 (10)	0.0085 (9)
C5	0.0234 (9)	0.0254 (9)	0.0261 (9)	−0.0028 (7)	0.0020 (7)	0.0049 (7)
C6	0.0177 (9)	0.0313 (9)	0.0347 (10)	−0.0005 (8)	0.0014 (7)	0.0048 (8)
C12	0.0333 (11)	0.0309 (10)	0.0405 (12)	−0.0056 (8)	−0.0070 (9)	0.0119 (9)
C19	0.0680 (16)	0.0340 (11)	0.0325 (11)	−0.0132 (11)	0.0105 (11)	−0.0067 (9)
C7	0.0219 (9)	0.0280 (9)	0.0320 (10)	0.0019 (8)	−0.0016 (7)	0.0064 (8)
C16	0.0409 (11)	0.0245 (9)	0.0254 (10)	−0.0021 (8)	0.0026 (8)	0.0021 (8)
C18	0.088 (2)	0.0333 (12)	0.0300 (11)	−0.0088 (13)	−0.0149 (12)	0.0091 (9)
C17	0.084 (2)	0.0421 (13)	0.0570 (16)	−0.0069 (14)	−0.0303 (15)	0.0262 (12)

Geometric parameters (Å, º) top

Fe1—N1ⁱ	1.9778 (15)	C9—C8	1.458 (2)
Fe1—N1	1.9778 (15)	C14—C15	1.396 (3)
Fe1—N4	1.9770 (14)	C14—C13	1.389 (3)
Fe1—N4ⁱ	1.9770 (14)	C14—C18	1.444 (3)
Fe1—N3ⁱ	1.9158 (15)	C15—H15	0.9500
Fe1—N3	1.9158 (15)	C15—C16	1.392 (3)
N2—N1	1.375 (2)	C11—C12	1.392 (3)
N2—C3	1.362 (2)	C11—C16	1.409 (3)
N2—C4	1.399 (2)	C4—C5	1.381 (2)
N5—C10	1.345 (2)	C8—C7	1.382 (3)
N5—N4	1.364 (2)	C2—H2	0.9500
N1—C1	1.322 (2)	C13—C12	1.387 (3)
N6—C10	1.352 (2)	C5—H5	0.9500
N6—C9	1.338 (2)	C5—C6	1.385 (3)
O2—H2A	0.85 (3)	C6—H6	0.9500
O2—C19	1.405 (3)	C6—C7	1.391 (3)
C10—C11	1.477 (2)	C12—H12	0.9500
N4—C9	1.344 (2)	C19—H19A	0.9800
O1—C13	1.374 (3)	C19—H19B	0.9800
O1—C17	1.384 (3)	C19—H19C	0.9800
N3—C4	1.331 (2)	C7—H7	0.9500
N3—C8	1.354 (2)	C16—H16	0.9500
C3—H3	0.9500	C18—H18	0.9500
C3—C2	1.364 (3)	C18—C17	1.339 (4)
C1—H1	0.9500	C17—H17	0.9500
C1—C2	1.403 (3)

N1ⁱ—Fe1—N1	90.92 (9)	C14—C15—H15	120.6
N4ⁱ—Fe1—N1	92.23 (6)	C16—C15—C14	118.8 (2)
N4—Fe1—N1ⁱ	92.23 (6)	C16—C15—H15	120.6
N4—Fe1—N1	159.14 (6)	C12—C11—C10	118.26 (17)
N4ⁱ—Fe1—N1ⁱ	159.14 (5)	C12—C11—C16	120.36 (18)
N4—Fe1—N4ⁱ	92.13 (8)	C16—C11—C10	121.36 (17)
N3ⁱ—Fe1—N1ⁱ	79.51 (6)	N3—C4—N2	111.09 (15)
N3—Fe1—N1	79.51 (6)	N3—C4—C5	123.59 (16)
N3—Fe1—N1ⁱ	96.99 (6)	C5—C4—N2	125.31 (16)
N3ⁱ—Fe1—N1	96.98 (6)	N3—C8—C9	109.07 (15)
N3ⁱ—Fe1—N4ⁱ	79.64 (6)	N3—C8—C7	120.68 (16)
N3ⁱ—Fe1—N4	103.86 (6)	C7—C8—C9	130.18 (17)
N3—Fe1—N4	79.64 (6)	C3—C2—C1	106.30 (16)
N3—Fe1—N4ⁱ	103.86 (6)	C3—C2—H2	126.8
N3—Fe1—N3ⁱ	175.06 (8)	C1—C2—H2	126.8
N1—N2—C4	116.41 (14)	O1—C13—C14	111.21 (19)
C3—N2—N1	111.23 (14)	O1—C13—C12	124.5 (2)
C3—N2—C4	132.29 (15)	C12—C13—C14	124.3 (2)
C10—N5—N4	104.56 (13)	C4—C5—H5	121.7
N2—N1—Fe1	112.69 (10)	C4—C5—C6	116.69 (16)
C1—N1—Fe1	142.05 (12)	C6—C5—H5	121.7
C1—N1—N2	105.17 (14)	C5—C6—H6	119.6
C9—N6—C10	101.33 (14)	C5—C6—C7	120.74 (17)
C19—O2—H2A	107.2 (19)	C7—C6—H6	119.6
N5—C10—N6	114.20 (15)	C11—C12—H12	121.6
N5—C10—C11	123.95 (16)	C13—C12—C11	116.8 (2)
N6—C10—C11	121.82 (16)	C13—C12—H12	121.6
N5—N4—Fe1	139.02 (11)	O2—C19—H19A	109.5
C9—N4—Fe1	114.63 (11)	O2—C19—H19B	109.5
C9—N4—N5	106.35 (13)	O2—C19—H19C	109.5
C13—O1—C17	104.5 (2)	H19A—C19—H19B	109.5
C4—N3—Fe1	119.77 (12)	H19A—C19—H19C	109.5
C4—N3—C8	119.57 (15)	H19B—C19—H19C	109.5
C8—N3—Fe1	120.46 (12)	C8—C7—C6	118.72 (17)
N2—C3—H3	126.8	C8—C7—H7	120.6
N2—C3—C2	106.38 (16)	C6—C7—H7	120.6
C2—C3—H3	126.8	C15—C16—C11	121.32 (19)
N1—C1—H1	124.5	C15—C16—H16	119.3
N1—C1—C2	110.91 (16)	C11—C16—H16	119.3
C2—C1—H1	124.5	C14—C18—H18	127.0
N6—C9—N4	113.56 (15)	C17—C18—C14	105.9 (2)
N6—C9—C8	130.27 (16)	C17—C18—H18	127.0
N4—C9—C8	116.07 (15)	O1—C17—H17	123.5
C15—C14—C18	136.1 (2)	C18—C17—O1	113.0 (2)
C13—C14—C15	118.49 (18)	C18—C17—H17	123.5
C13—C14—C18	105.4 (2)

Fe1—N1—C1—C2	175.25 (15)	N3—C8—C7—C6	0.5 (3)
Fe1—N4—C9—N6	−179.26 (12)	C3—N2—N1—Fe1	−176.63 (11)
Fe1—N4—C9—C8	3.9 (2)	C3—N2—N1—C1	0.66 (19)
Fe1—N3—C4—N2	−4.37 (19)	C3—N2—C4—N3	−177.97 (17)
Fe1—N3—C4—C5	175.56 (14)	C3—N2—C4—C5	2.1 (3)
Fe1—N3—C8—C9	1.54 (19)	C9—N6—C10—N5	0.5 (2)
Fe1—N3—C8—C7	−175.82 (14)	C9—N6—C10—C11	−177.82 (16)
N2—N1—C1—C2	−0.70 (19)	C9—C8—C7—C6	−176.21 (18)
N2—C3—C2—C1	−0.1 (2)	C14—C15—C16—C11	−0.3 (3)
N2—C4—C5—C6	179.99 (17)	C14—C13—C12—C11	0.3 (3)
N5—C10—C11—C12	170.28 (18)	C14—C18—C17—O1	−0.1 (3)
N5—C10—C11—C16	−11.3 (3)	C15—C14—C13—O1	−179.64 (19)
N5—N4—C9—N6	0.3 (2)	C15—C14—C13—C12	−0.3 (3)
N5—N4—C9—C8	−176.53 (14)	C15—C14—C18—C17	179.4 (3)
N1—N2—C3—C2	−0.4 (2)	C4—N2—N1—Fe1	6.09 (18)
N1—N2—C4—N3	−1.4 (2)	C4—N2—N1—C1	−176.61 (14)
N1—N2—C4—C5	178.66 (17)	C4—N2—C3—C2	176.33 (18)
N1—C1—C2—C3	0.5 (2)	C4—N3—C8—C9	176.42 (15)
N6—C10—C11—C12	−11.6 (3)	C4—N3—C8—C7	−0.9 (3)
N6—C10—C11—C16	166.86 (18)	C4—C5—C6—C7	−0.5 (3)
N6—C9—C8—N3	−179.67 (17)	C8—N3—C4—N2	−179.28 (14)
N6—C9—C8—C7	−2.6 (3)	C8—N3—C4—C5	0.6 (3)
C10—N5—N4—Fe1	179.40 (14)	C13—O1—C17—C18	−0.1 (3)
C10—N5—N4—C9	0.06 (18)	C13—C14—C15—C16	0.3 (3)
C10—N6—C9—N4	−0.5 (2)	C13—C14—C18—C17	0.2 (3)
C10—N6—C9—C8	175.77 (18)	C5—C6—C7—C8	0.2 (3)
C10—C11—C12—C13	178.16 (17)	C12—C11—C16—C15	0.3 (3)
C10—C11—C16—C15	−178.12 (18)	C16—C11—C12—C13	−0.3 (3)
N4—N5—C10—N6	−0.4 (2)	C18—C14—C15—C16	−178.8 (2)
N4—N5—C10—C11	177.92 (16)	C18—C14—C13—O1	−0.3 (2)
N4—C9—C8—N3	−3.5 (2)	C18—C14—C13—C12	179.1 (2)
N4—C9—C8—C7	173.51 (19)	C17—O1—C13—C14	0.2 (3)
O1—C13—C12—C11	179.6 (2)	C17—O1—C13—C12	−179.1 (2)
N3—C4—C5—C6	0.1 (3)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···N5	0.85 (3)	1.89 (2)	2.750 (2)	178 (3)
C1—H1···N6ⁱⁱ	0.95	2.27	3.189 (2)	163
C3—H3···O2ⁱⁱⁱ	0.95	2.29	3.208 (2)	161
C5—H5···O2ⁱⁱⁱ	0.95	2.46	3.386 (2)	164
C5—H5···N5ⁱⁱⁱ	0.95	1.90	3.463 (2)	129
C7—H7···C1^iv	0.95	2.63	3.537 (2)	159
C19—H19A···N2ⁱ	0.97	2.74	3.491 (2)	133
C19—H19A···C3ⁱ	0.97	2.89	3.695 (2)	140
C6···C3^v	–	–	3.482 (2)	–
C7···C3^v	–	–	3.498 (2)	–

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

Computed distortion indices (Å, °) for the title compound and for similar complexes reported in the literature. top

CSD Refcode	azol 1/azol 2	<Fe—N>	Σ	Θ	CShM(O_h)
Title compound	1,2,4-triazole/pyrazole	1.957	90.9	315.2	2.300
BEJQOA	1,2,4-triazole/pyrazole	1.946	87.5	308.9	2.163
ABUFOV	benzimidazole/benzimidazole	1.937	80.1	262.7	1.753
BOWRIR	tetrazole/pyrazole	1.934	89.7	287.4	2.043
XODCEB	benzimidazole/pyrazole	1.950	87.5	276.6	1.925

Acknowledgements

The authors are grateful to the FAIRE programme provided by the Cambridge Crystallographic Data Centre (CCDC) for the opportunity to use the Cambridge Structural Database (CSD) and associated software. Author contributions are as follows: conceptualization, MS; methodology, KZ; formal analysis, IOF; synthesis, IT; single-crystal measurements, SS; writing (original draft), IT and MS; writing (review and editing), KZ and VMA; visualization and calculations, OVO; funding acquisition, MS and KZ.

Funding information

Funding for this research was provided by: Ministry of Education and Science of Ukraine (grant for the perspective development of the scientific direction "Mathematical sciences and natural sciences" at the Taras Shevchenko National University of Kyiv).

References

Bonhommeau, S., Lacroix, P. G., Talaga, D., Bousseksou, A., Seredyuk, M., Fritsky, I. O. & Rodriguez, V. (2012). J. Phys. Chem. C 116, 11251–11255. Web of Science CrossRef CAS Google Scholar
Bourhis, L. J., Dolomanov, O. V., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2015). Acta Cryst. A71, 59–75. Web of Science CrossRef IUCr Journals Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Fares, M., Wu, X., Ramesh, D., Lewis, W., Keller, P. A., Howe, E. N. W., Pérez–Tomás, R. & Gale, P. A. (2020). Angew. Chem. Int. Ed. 59, 17614–17621. Web of Science CSD CrossRef CAS Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Gütlich, P. & Goodwin, H. A. (2004). Top. Curr. Chem. 233, 1–47. Google Scholar
Halcrow, M. A. (2024). Dalton Trans. 53, 13694–13708. Web of Science CrossRef CAS PubMed Google Scholar
Kershaw Cook, L. J., Mohammed, R., Sherborne, G., Roberts, T. D., Alvarez, S. & Halcrow, M. A. (2015). Coord. Chem. Rev. 289–290, 2–12. Web of Science CSD CrossRef CAS Google Scholar
Piñeiro-López, L., Valverde-Muñoz, F. J., Seredyuk, M., Bartual-Murgui, C., Muñoz, M. C. & Real, J. A. (2018). Eur. J. Inorg. Chem. pp. 289–296. Google Scholar
Rajnák, C., Titiš, J., Fuhr, O., Ruben, M. & Boča, R. (2017). Polyhedron 123, 122–131. Google Scholar
Rigaku OD (2024). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England. Google Scholar
Senthil Kumar, K., Vela, S., Heinrich, B., Suryadevara, N., Karmazin, L., Bailly, C. & Ruben, M. (2020). Dalton Trans. 49, 1022–1031. Web of Science CSD CrossRef CAS PubMed Google Scholar
Seredyuk, M., Gaspar, A. B., Kusz, J., Bednarek, G. & Gütlich, P. (2007). J. Appl. Cryst. 40, 1135–1145. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Seredyuk, M., Znovjyak, K., Valverde-Muñoz, F. J., da Silva, I., Muñoz, M. C., Moroz, Y. S. & Real, J. A. (2022). J. Am. Chem. Soc. 144, 14297–14309. Web of Science CSD CrossRef CAS PubMed Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Shiga, T., Saiki, R., Akiyama, L., Kumai, R., Natke, D., Renz, F., Cameron, J. M., Newton, G. N. & Oshio, H. (2019). Angew. Chem. Int. Ed. 58, 5658–5662. Web of Science CSD CrossRef CAS Google Scholar
Spackman, P. R., Turner, M. J., McKinnon, J. J., Wolff, S. K., Grimwood, D. J., Jayatilaka, D. & Spackman, M. A. (2021). J. Appl. Cryst. 54, 1006–1011. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wei, S. Y., Wang, J. L., Zhang, C. S., Xu, X.-T., Zhang, X. X., Wang, J. X. & Xing, Y.-H. (2015). ChemPlusChem 80, 549-558. Web of Science CSD CrossRef CAS PubMed Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.