English

• 1. INTRODUCTION

  In the last year, Okamura et al. reported a pentanuclear iron cluster which can be catalyst water oxidation^[1]. Polynuclear iron(III) clusters continue to attract the intense interest of many inorganic groups^[2-4]. In the molecular magnet system, high-spin Fe^III ions have a large number of unpaired electrons (3d⁵, S = 5/2) and usually display strong antiferromagnetic interactions among Fe^III ions^{[5, 6]}, but part of high nuclearity iron(III) clusters which possess appropriate topologies and large spin (S) values in their ground states can even occasionally function as single-molecule magnets (SMMs)^{[7, 8]}.

  Careful selection of appropriate organic ligand with certain characteristics, such as variable bonding modes and the ability to perform supramolecular interactions, is helpful for tailoring and constructing clusters with desirable properties^[9-13]. In recent years, many complexes constructed with 5-amino-1, 2, 3, 4-tetrazole (HATZ) have been reported^[14-19]. From the structural point of view, HATZ possesses two interesting characteristics: (1) the ATZ possesses four N atoms of tetrazole group and one amino group with two hydrogen atoms and might be utilized as versatile linker in constructing interesting coordination polymers with abundant hydrogen bonds^{[5, 14-19]}. (2) HATZ shows abundant coordination modes (Scheme 1), such as μ₂: 1η¹: 4η^1[14], μ₃: 1η¹: 2η¹: 4η^1[15], μ₁: 1η^1[16], μ₃: 1η¹: 2η¹: 3η¹: 4η^1[17], μ₂: 2η¹: 3η^1[18] and μ₃: 1η¹: 2η¹: 3η^1[19]. But the complexes of HATZ Schiff base are rarely reported^[5]. Herein, using a new Schiff base H₂timb synthesized by 5-bromo-2-hydroxybenzaldehyde and HATZ, a pentanuclear iron(III) cluster [HN(C₂H₅)₃]· [Fe₅(timb)₄(ATZ)₄(μ₃-O)₂]·(H₂O)₅ (1) was synthesized through micro-vial reactions.

  Scheme 1

  

  Scheme 1.  Coordination modes of HATZ

  DownLoad: Full-Size Img PowerPoint

  2. EXPERIMENTAL

  2.1 Synthesis of H₂timb

  A mixture of 5-bromo-2-hydroxybenzaldehyde (20 mmol, 4.021 g), HATZ (20 mmol, 1.701 g) and EtOH (30 mL) in a 100 mL flask was refluxed at 80 ℃ for 2 h, and then dried at 50 ℃ for 24 h after filtrated, yellow-greenish powder had been gained (yield: 3.706 g, ca. 98%, based on HATZ). Anal. Calcd. for H₂timb: C₈H₆N₅OBr (M_r = 268.09), Calcd.: C, 35.81; H, 2.34; N, 26.11%. Found: C, 35.78; H, 2.38; N, 26.14%. IR data (KBr, cm^–1, Fig. S1): 3379w, 1613s, 1555s, 1470s, 1274s, 1174s, 1063m, 728m.

  2.2 Synthesis of 1

  A mixture of FeCl₃·6H₂O (0.5 mmol, 0.135 g), H₂timb (0.5 mmol, 0.134 g) and anhydrous acetonitrile (10 mL) with a pH adjusted to 7 by addition of triethylamine was stirred for 15 min at room temperature. The mixture was poured into a micro-vial (20 mL) and then heated at 80 ℃ for 72 h. Bright black cuboid crystals of 1 were collected by filtration, washed with anhydrous acetonitrile (5 mL × 3) and dried in air (yield: 0.152 g, ca. 88.74% based on Fe^III). Anal. Calcd. for 1: C₄₂H₅₀Br₄Fe₅N₄₁O₁₁ (M_r = 1904.04): C, 26.49; H, 2.65; N, 30.15%. Found: C, 26.35; H, 2.74; N, 30.22. IR data for 1 (KBr, cm^–1, Fig. S1): 3357m, 1601s, 1574w, 1444s, 1299s, 1178s, 829w, 586m.

  2.3 Crystal structure determination

  The diffraction data were collected on an Agilent G8910A CCD diffractometer with graphite monochromatic Mo-Kα radiation (λ= 0.71073 Å) using an ω-θ scan mode in the range 3.74≤θ≤25.10°. Raw frame data were integrated with the SAINT program^[20]. The structure of 1 was solved by direct methods using SHELXS-97 and refined by full-matrix least-squares on F² using SHELXS-97^[20]. An empirical absorption correction was applied with the program SADABS^[20]. All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were positioned geometrically and refined as riding. Calculations and graphics were performed with SHELXTL^[20]. Disordered solvent molecules are removed by squeeze program. The solvent molecules and countervailing cations were determined by elemental and thermogravimetric analyses. Selected bond lengths and bond angles for 1 are listed in Table 1, and hydrogen bond lengths and bond angles in Table 2.

  Table 1

  

  Table 1.  Selected Bond Lengths (Å) and Bond Angles (°) for 1

  DownLoad: CSV

  Bond	Dist.		Bond	Dist.		Bond	Dist.
  Fe(1)–O(1)	1.919(3)		Fe(2)–O(1)i	1.880(6)		Fe(1)–N(6)	2.078(6)
  Fe(1)–O(2)	1.907(5)		Fe(2)–O(1)	1.880(6)		Fe(1)–N(7)iii	2.145(6)
  Fe(1)–N(1)	2.191(6)		Fe(2)–N(2)	2.113(6)		Fe(2)–N(2)ii	2.113(6)
  Fe(2)–N(2)iii	2.113(6)
  Angle	(°)		Angle	(°)		Angle	(°)
  O(1)–Fe(1)–N(1)	99.70(18)		O(1)–Fe(2)–N(2)ii	86.48(14)		N(7)iii–Fe(1)–N(1)	87.0(2)
  O(1)–Fe(1)–N(3)i	82.99(19)		O(1)–Fe(2)–N(2)	93.52(14)		N(7)iii–Fe(1)–N(3)i	165.6(2)
  O(1)–Fe(1)–N(6)	85.0(2)		O(1)–Fe(2)–N(2)i	93.52(14)		O(2)–Fe(1)–N(1)	172.9(2)
  O(1)–Fe(1)–N(7)iii	83.6(2)		O(1)–Fe(2)–N(2)iii	93.52(14)		O(2)–Fe(1)–N(3)i	96.4(2)
  O(2)–Fe(1)–O(1)	174.68(18)		N(2)i–Fe(2)–N(2)iii	90.216(18)		O(2)–Fe(1)–N(6)	89.8(2)
  N(6)–Fe(1)–N(1)	172.9(2)		O(1)i–Fe(2)–O(1)	180.0		O(2)–Fe(1)–N(7)iii	97.4(2)
  N(6)–Fe(1)–N(3)i	95.8(2)		O(1)–Fe(2)–N(2)i	86.48(14)		O(1)i–Fe(2)–N(2)	86.48(14)
  N(2)iii–Fe(2)–N(2)	173.0(3)		N(2)ii–Fe(2)–N(2)i	173.0(3)		O(1)i–Fe(2)–N(2)ii	93.52(14)
  N(2)i–Fe(2)–N(2)	90.217(18)		O(1)i–Fe(2)–N(2)iii	86.48(14)
  Symmetry transformation: (i) y, –x+1, –z; (ii) –y+1, x, –z; (iii) –x+1, –y+1, z

  Table 2

  

  Table 2.  Hydrogen Bond Lengths (Å) and Bond Angles (°) for 1

  DownLoad: CSV

  D–H···A	d(D–H)	d(H···A)	d(D···A)	∠DHA
  N(10)–H(10A)···N(5)iv	0.8600	2.4300	2.9126	116.00
  N(10)–H(10B)···O(2)	0.8600	2.3800	3.0351	133.00
  N(10)–H(10B···N(4)iv	0.8600	2.4200	2.9320	119.00
  C(2)–H(2)···N(5)	0.9300	2.3300	2.7485	107.00
  N(9)–H(9)···Br(1)v	0.86	2.80	3.516	141.6
  N(10)–H(10A)···Br(1)v	0.86	2.95	3.672	142.9
  Symmetry codes: (iv) –y+0.5, −x, z−1/4; (v) 0.5−y, x−0.5, 0.5–z

  2.4 Hirshfeld surface calculations of 1

  Molecular Hirshfeld surface calculations were performed by using the CrystalExplorer program^[21]. When the CIFs file of 1 are read into the CrystalExplorer program, all hydrogen bond lengths were automatically modified to typical standard neutron values (C–H = 1.083 Å, N–H = 1.009 Å and O–H = 0.983 Å)^[22]. In this study, all the Hirshfeld surfaces were generated using a high (standard) surface resolution. The 3D dnorm surfaces were mapped by using a fixed color scale of 0.76 (red) to 2.4 (blue). The 2D fingerprint plots were displayed by using the standard 0.4~3.0 Å view with the de and di distance scales displayed on the graph axes.

  3. RESULTS AND DISCUSSION

  3.1 Description of the crystal structure

  Single-crystal X-ray structure analysis reveals that 1 crystallizes in tetragonal system space group I$ \bar 4 $2d with 4₂ axes. As illustrated in Fig. 1, 1 consists of one pentanuclear anionic Fe^III cluster, [Fe₅(timb)₄(ATZ)₄(μ₃-O)₂]^–. It can also be seen that Fe(2) atom is located at the center of structure bridged by two μ₃-O^2‒ groups which are linked with the other four Fe atoms (Fe(1), its three centrosymmetric equivalent Fe atoms, Fe(1)a, Fe(1)b, and Fe(1)c, symmetry codes: (a) y, 1–x, –z; (b) 1–x, 1–y, z; (c) 1–y, x, –z). The five Fe^III atoms formed two isosceles triangles perpendicular to each other sharing one vertex (plane equation of Fe(1)– Fe(2)–Fe(1)b: 18.183x + 7.673y = 12.9276, Fe(1)a– Fe(2)–Fe(1)c: –7.673x + 18.183y = 5.2553). Dihedral angle between the two planes is 90.0º which is perpendicular to each other. The Fe···Fe distance of 1 falls in the range of 3.291~3.305 Å, obviously shorter than that of [Fe₅(μ₃-F)₂(XDK)₂(L)₄(O₂CPh)₄] (H₂XDK = m-xylylenediamine bis(Kemp's triacid)-imide, L = pyridine(py) or N-methylimidazole-(N–MeIm). The Fe···Fe distances are in range of 3.452~3.585 Å)^[23]. The magnetic exchange angles of Fe–O–Fe are in the range of 118.1~120.9°. The coordination geometry of the central iron Fe(2) ion can be described as a slightly distorted octahedron with the bond lengths of 1.880(4)~2.113(4) Å and the cis-angles in the range of 86.5(1)°~93.5(1)°, whereas the trans-angles vary from 173.0(2) to 180.0°. The other iron ions (Fe(1), Fe(1)a, Fe(1)b, and Fe(1)c) adopt a FeN₄O₂ configuration coordinated by two ATZ ligands, two timb ligands and one μ₃-O^2‒ group. The Fe(1) ion is found in more distorted octahedral geometry (cis-angles range from 83.0(1) to 99.7(1)°, and trans-angles from 165.6(2) to 174.7(1)°) with the axial bond elongated. The coordination bond lengths around the Fe(1) ion are in the range of 1.907(3)~2.191(5) Å. These bond lengths are consistent with those found in comparable structures (Fe–X (X = N, O) distances range from 1.869 to 2.225 Å)^[23-25]. It is very interesting that the timb ligand displays a μ₃: η¹: η¹: η¹: η¹ coordination mode while the ATZ ligand displays a μ₂: 1η¹: 2η¹ coordination mode (Scheme 1g). This coordination pattern is easy to form clusters which are different from the coordination mode of Scheme 1a, 1b, 1d~1f. Those coordination patterns of Scheme 1a, 1b, 1d~1f are easy to form polymers^{[14, 15, 17-19]}. At the same time, it must be noted that the ATZ ligand was synthesized though H₂timb Schiff base decomposition reaction.

  Figure 1

  

  Figure 1.  Anionic structure of 1. The hydrogen atoms, solvent molecules and countervailing cations are omitted for clearly

  DownLoad: Full-Size Img PowerPoint

  Complex 1 further constructed a 1D chain through double receptor N···H–N hydrogen bonds (N(4)a···H(10a)ⁱ–N(10)ⁱ, 2.931 Å, N(5a)···H(10b)ⁱ–N(10)ⁱ, 2.913 Å symmetry code: (i) x, 0.5–y, 0.25–z) and double donor N– H···N hydrogen bonds (N(10)– H(10a)ⁱⁱ···N(4)ⁱⁱ, 2.931 Å, N(10)–H(10b)ⁱⁱ···N(5)ⁱⁱ, 2.913 Å symmetry code: (ii) y, x–0.5, 0.25+z. Fig. S2) which further formed a 3D network through abundant hydrogen bonds: N–H···N, N–H···Br (N(9)–H(9)···Br(1)ⁱⁱⁱ, 3.516Å, N(10)– H(10a)···Br(1)ⁱⁱⁱ, 3.672 Å, symmetry code: (iii) 0.5–y, x–0.5, 0.5–z), π···π interactions (the distance between the plane of C(3)~C(8) and the plane of (C(3)~C(8))^iv is 3.457 Å, symmetry code: (iv) x, 0.5–y, 0.25–z), N–H···O and C–H···N (Table 2, Fig. S3)^{[26, 27]}.

  3.2 Magnetic properties

  The magnetic susceptibilities of 1 were measured by using crushed single crystal samples. The dc susceptibilities of 1 were measured under an applied field of 1 kOe at temperature ranging from 2 to 300 K.

  For complex 1, the five Fe(III) ions give rise to the χ_mT product of 6.53 cm³·K·mol^–1 at room temperature (Fig. 2). The χ_mT values at room temperature are all much less than the spin-only value of 22 cm³·K·mol^–1 for five non-interacting high-spin Fe^III ions assuming g = 2.2^[25]. The observed values of 1 are also lesser than those obtained for [Fe₅(μ₃-F)₂(XDK)₂(py)₄(O₂CPh)₄] (~10.98 cm³·K·mol^–1) and [Fe₅(μ₃-F)₂(XDK)₂(N-MeIm)₄(O₂CPh)₄] (~10.38 cm³·K·mol^–1)^[23]. Upon decreasing T, the χ_mT values of 1 gradually decrease to the minimum of 2.57 at 2 K. Similar magnetic behaviors were observed for [Fe₅(μ₃-F)₂(XDK)₂(py)₄(O₂CPh)₄] and [Fe₅(μ₃-F)₂(XDK)₂ (N-MeIm)₄(O₂CPh)₄]^[23]. The results indicated the presence of strong antiferromagnetic interactions.

  Figure 2

  

  Figure 2.  Plots of χ_m-T and χ_mT-T for 1. The red solid line represents a fit of data in the temperature range of 22~300 K. Inset: The exchange pathway is between the Fe(III) ions

  DownLoad: Full-Size Img PowerPoint

  Examination of the bond lengths and angles between Fe(III) ions in 1 for magneto-structural correlations reveal two obvious antiferromagnetic interactions. The quantitative approximation of the exchange interactions for the 3D oxo-bridged Fe(III) systems was obtained by fitting the appropriate theoretical equation to the experimental data separately in 22~300 K, through using the program Origin8.6. The Heisenberg spin-Hamiltonian (Eq. 1):

  $ \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\frown}$}}{H} = - 2J({\vec S_1}{\vec S_4} + {\vec S_2}{\vec S_3}) - 2J'({\vec S_1}{\vec S_5} + {\vec S_2}{\vec S_5} + {\vec S_3}{\vec S_5} + {\vec S_4}{\vec S_5})$

  (Eq.1)

  Where J and J' characterize the exchange of Fe(1)···Fe(1)c and Fe(1)···Fe(2) through µ₃-O bridge for 1 (inset Fig. 2). The best fitting gave: g = 2.026, J = –2.066 cm^–1, J' = –1.80 × 10^–4 cm^–1, and R = ∑ [(χ_obs – χ_calc) ²/∑(χ_obs) ² = 1.20 × 10^–5. These results further support intracluster antiferromagnetic coupling between the Fe(III) ions in 1 through μ₃-O bridges.

  The χ_m^–1-T curve follows the Curie-Weiss law [χ_m = C/(T–θ)] (Fig. S4) severally in 70~300 K with a Weiss constant of θ to be –70.59 K and Curie constant of C being 7.90 cm³⋅K⋅mol^–1. The negative Weiss constant suggests dominant intracluster antiferromagnetic coupling between adjacent Fe(III) ions through μ₃-O bridges.

  3.3 Hirshfeld surface analysis

  Hirshfeld surface analysis is a useful tool for describing the surface characteristics of the molecules^[28-31], which was performed to visualize the different intermolecular interactions in crystal structures by employing 3D molecular surface contours. The Hirshfeld surfaces in the crystal structure of a particular complex are constructed on the basis of the electron distribution calculated as the sum of spherical atom electron densities. Inside the Hirshfeld surface the electron distribution due to a sum of spherical atoms for the molecule (the pro-molecule) dominates the corresponding sum over the crystal (the pro-crystal), and the Hirshfeld surface is defined as the ratio of the pro-molecule to pro-crystal electron densities equal to 0.5.

  One of the useful supplements for Hirshfeld surface analysis is the 2D fingerprint plot. It quantitatively analyzes the nature and type of intermolecular interaction between the molecules inside the crystals. The fingerprint plots can be decomposed to highlight particularly close contacts between the elements (Fig. 3). The Br···H interaction is one of the most significant contacts for 1.

  Figure 3

  

  Figure 3.  (a) dnorm of 1, (b) Full 2D Hirshfeld surface are, (c) Br···H (d) H···H, (e) N···H, (f) C···C fingerprint plots showing the percentages of contacts contributed to the total Hirshfeld surface area of 1

  DownLoad: Full-Size Img PowerPoint

  For 1, the Br···H interactions are represented by four blades in the fingerprint plot. So we can infer that there are significant N–H···Br (N(9)–H(9)···Br(1)ⁱⁱⁱ, 3.516 Å, N(10)– H(10a)···Br(1)ⁱⁱⁱ, 3.672 Å, symmetry code: (iii) 0.5–y, x–0.5, 0.5–z) interactions observed in complex 1 (The percentage of Br^…H contact of 1 is 45.4%). H···H contacts are the second major intermolecular interaction. Another main intermolecular interaction of 1 is N···H contacts which reflected in the middle of the scattered point of the 2-D fingerprint plots (The percentage of N···H contacts of 1 is 18.6%). In the solid state structure, abundant N–H···N hydrogen bonds (N(10)–H(10a)ⁱⁱ···N(4)ⁱⁱ, 2.931 Å, N(10)–H(10b)ⁱⁱ···N(5)ⁱⁱ, 2.913 Å symmetry code: (ii) y, x–0.5, 0.25+z) were observed. Also, the C···C contacts play important roles for 1. The percentage of C···C contacts of 1 is 3.2%. π···π interactions were also observed (π_{(C(3)–C(8)···}π_(C(3)–C(8)^iv distance is 3.457 Å, symmetry code: (iv) x, 0.5–y, 0.25–z, Fig. S2).

  3.4 Thermogravimetric analysis

  Considering the fact that multinuclear clusters based on tetrazolium are well-known for their high thermal stability, we also investigated the thermal analysis of 1 in this work. The sample was heated in a platinum crucible at a rate of 10 ℃⋅min^–1 under a nitrogen atmosphere within the temperature range of 25 to 1030 ℃ (Fig. 4). At first, between 25 and 115 ℃, 1 loses 10.5% of the weight continuously, corresponding to the loss of five water molecules and a countercation [HN(C₂H₅)₃] in 1. The weightlessness rate (10.5%) is consistent with the theoretical weightlessness rate (10.09%). The anionic [Fe₅(timb)₄(ATZ)₄(μ₃-O)₂]^– of 1 reveals high thermal stability, which begins to break down at 217 ℃.

  Figure 4

  

  Figure 4.  Thermogravimetric analysis of 1

  DownLoad: Full-Size Img PowerPoint

  4. CONCLUSION

  In summary, a penta-nuclear Fe(III) cluster has been successfully synthesized with FeCl₃·6H₂O, together with H₂timb Schiff base ligand. The Hirshfeld surface analysis results indicate that Br···H interactions play a most considerable role in stabilizing the self-assembly process. Magnetic studies reveal that complex 1 displays dominant antiferromagnetic intracluster interactions between Fe^III ions through μ₃-O bridges. In addition, the pentanuclear Fe^III clusters manifest high stability.

  
  
• 1. [1]

     Okamura, M.; Kondo, M.; Kuga, R.; Kurashige, Y.; Yanai, T.; Hayami, S.; Praneeth, V. K. K.; Yoshida, M.; Yoneda, K.; Kawata, S.; Masaoka, S. A pentanuclear iron catalyst designed for water oxidation. Nature 2016, 530, 465-468. doi: 10.1038/nature16529

  2. [2]

     Kitos, A. A.; Papatriantafyllopoulou, C.; Tasiopoulos, A. J.; Perlepes, S. P.; Escuer, A.; Nastopoulos, V. Binding of ligands containing carbonyl and phenol groups to iron(III): new Fe₆, Fe₁₀ and Fe₁₂ coordination clusters. Dalton Trans. 2017, 46, 3240-3251. doi: 10.1039/C6DT04830G

  3. [3]

     Mokhtari, R.; Rezaeifard, A.; Jafarpour, M.; Farrokhi, A. Visible-light driven catalase-like activity of blackberry-shaped {Mo₇₂Fe₃₀} nanovesicles: combined kinetic and mechanistic studies. Sci. Technol. 2018, 8, 4645-4656.

  4. [4]

     Mayans, J.; Font-Bardia, M.; Escuer, A. Chiroptical and magnetic properties of star-shaped Fe₄^III complexes from chiral Schiff bases. Structural and magnetic correlations based on continuous shape measures. Dalton Trans. 2018, 47, 8392-8401. doi: 10.1039/C8DT01684D

  5. [5]

     Chen, Z.; Fan, Y.; Wang, J.; Yang, L.; Zhang, S. Pentanuclear Fe(III) cluster: synthesis, structure, magnetic properties and hirshfeld surface analysis. Chemi. Select. 2018, 3, 9841-9844.

  6. [6]

     Herold, S.; Lippard, S. J. Synthesis, characterization, and magnetic studies of two novel isostructural pentanuclear iron(II) complexes. Inorg. Chem. 1997, 36, 50-58. doi: 10.1021/ic960783i

  7. [7]

     Milios C. J.; Winpenny R. E. P. Cluster-based single-molecule magnets. Struct. Bond. 2015, 164, 1-110.

  8. [8]

     Barra, A. L.; Caneschi A.; Cornia, A.; Fabrizi de Biani, F.; Gatteschi, D.; Sangregorio, C.; Sessoli, R.; Sorace, L. Single-molecule magnet behavior of a tetranuclear iron(III) complex. The origin of slow magnetic relaxation in iron(III) clusters. J. Am. Chem. Soc. 1999, 121, 5302-5310. doi: 10.1021/ja9818755

  9. [9]

     Xiao, Y.; Liu, Y. Q.; Li, G.; Huang, P. Microwave-assisted synthesis, structure and properties of a co-crystal compound with 2-ethoxy-6-methyliminomethyl-phenol. Supramol. Chem. 2015, 27, 161-166. doi: 10.1080/10610278.2014.918268

  10. [10]

      Xiao, Y.; Qin, Y.; Yi, M.; Zhu, Y. A disc-like heptanuclear nickel cluster based on schiff base: Synthesis, structure, magnetic properties and hirshfeld surface analysis. J. Clust. Sci. 2016, 27, 2013-2023. doi: 10.1007/s10876-016-1059-y

  11. [11]

      Zhang, S. H.; Zhang, Y. D.; Zou, H. H.; Guo, J. J.; Li, H. P.; Song, Y.; Liang, H. A family of cubane cobalt and nickel clusters: syntheses, structures and magnetic properties. Inorg. Chim. Acta 2013, 396, 119-125. doi: 10.1016/j.ica.2012.10.032

  12. [12]

      Feng, C.; Zhu, Y. Q.; Huang, H. H.; Zhao, H. A triazolate-supported Fe₃(μ₃-O) core: crystal structure, fluorescence, and hirshfeld surface analysis. J. Clust. Sci. 2016, 27, 1181-1190. doi: 10.1007/s10876-016-0989-8

  13. [13]

      Schmitz, S.; Secker, T.; Batool, M.; Leusen, J.; Nadeem, M. A.; Kögerler, P. A planar decanuclear cobalt(II) coordination cluster. Inorg. Chim. Acta 2018, 482, 522-525. doi: 10.1016/j.ica.2018.06.005

  14. [14]

      Wang, X. W.; Chen, J. Z.; Liu, J. H. Photoluminescent Zn(II) metal-organic frameworks built from tetrazole ligand:  2D four-connected regular honeycomb (4³6³)-net. Cryst. Growth Des. 2007, 7, 1227-1229. doi: 10.1021/cg070330w

  15. [15]

      Yao, Y. L.; Xue, L.; Che, Y. X.; Zheng, J. M. Syntheses, structures, and characterizations of two pairs of Cd(II)-5-aminotetrazolate coordination polymers. Cryst. Growth Des. 2009, 9, 606-610. doi: 10.1021/cg8009157

  16. [16]

      Zhang, J. G.; Zhang, T. L.; Yu, K. B. Studies on synthesis, crystal structure and thermal decomposition mechanism of cadmium complex [Cd(ATZ)₄(H₂O)₂](PA)₂·2H₂O. Acta Chim. Sinica 2001, 59, 84-90.

  17. [17]

      Lin, J. D.; Wang, S. H.; Cai, L. Z.; Zheng, F. K.; Guo, G. C.; Huang, J. S. Tetraalkylammonium cations as templates in the construction of two cadmium(II) metal-organic frameworks. CrystEngComm. 2013, 15, 903-910. doi: 10.1039/C2CE26213D

  18. [18]

      Kobrsi, I.; Bassioni, G. Bis(μ-5-diiso­propyl­amino-1, 2, 3, 4-tetra­zolido-κ₂N₂: N₃)bis­­[(triiso­propyl­phosphane)copper(I)]. Acta Crystal. 2011, E67, m975-m975.

  19. [19]

      He, X.; Lu, C. Z.; Yuan, D. Q. Two 3D porous cadmium tetrazolate frameworks with hexagonal tunnels. Inorg. Chem. 2006, 45, 5760-5766. doi: 10.1021/ic0520162

  20. [20]

      Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta Cryst. 2015, C71, 3-8.

  21. [21]

      McKinnon, J. J.; Spackman, M. A.; Mitchell, A. S. Novel tools for visualizing and exploring intermolecular interactions in molecular crystals. Acta Cryst. 2004, B60, 627-668.

  22. [22]

      Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A. G.; Taylor, R. Tables of bond lengths determined by X-ray and neutron diffraction. Part I. Bond lengths in organic compounds. J. Chem. Soc. Perkin Trans. 1987, 2, S1-S19.

  23. [23]

      Herold, S.; Lippard, S. J. Synthesis, characterization, and magnetic studies of two novel isostructural pentanuclear iron(II) complexes. Inorg. Chem. 1997, 36, 50-58. doi: 10.1021/ic960783i

  24. [24]

      Sertphon, D.; Harding, D. J.; Harding, P.; Murray, K. S.; Moubaraki, B.; Cashion, J. D.; Adams H. Anionic tuning of spin crossover in Fe^III-quinolylsalicylaldiminate complexes. Eur. J. Inorg. Chem. 2013, 788-795.

  25. [25]

      Tabernor, J.; Jones, L. F.; Heath, S. L.; Muryn, C.; Aromi, G.; Ribas, J.; Brechin, E. K.; Collison, D. A centred, elongated 'ferric tetrahedron' with an S = 15/2 spin ground state. Dalton Trans. 2004, 33, 975-976.

  26. [26]

      Zhang, C.; Yang, L.; Chen, H.; Zhang, S. H. A novel dinuclear copper(II) complex: synthesis, crystal structure, properties and hirshfeld surface analysis. Chin. J. Struct. Chem. 2017, 36, 1904-1911.

  27. [27]

      Chen, G. H.; He, Y. P.; Zhang, S. H.; Zhang, L. A series of zirconium-oxo cluster complexes based on arsenate or phosphonate ligands. Inorg. Chem. Comm. 2018, 97, 125-128. doi: 10.1016/j.inoche.2018.09.013

  28. [28]

      Spackman, M. A.; Jayatilaka, D. Hirshfeld surface analysis. CrystEngComm . 2009, 11, 19-32. doi: 10.1039/B818330A

  29. [29]

      Feng, C.; Ma, Y. H.; Zhang, D.; Li, X. J.; Zhao, H. Highly efficient electrochemiluminescence based on pyrazolecarboxylic metal organic framework. Dalton Trans. 2016, 45, 5081-5091. doi: 10.1039/C5DT04740D

  30. [30]

      Zhao, H.; Zhu, Y. Q.; Feng, C. One novel Mn(II) complex with 1-substituted-1H-1, 2, 3-triazole-4-carboxylic acid: crystal structure, fluorescence and hirshfeld surface analysis. Chin. J. Struct. Chem. 2017, 36, 66-72.

  31. [31]

      Xiao, Y.; Qin, Y.; Yi, M.; Zhu, Y. A disc-like heptanuclear nickel cluster based on Schiff base: synthesis, structure, magnetic properties and hirshfeld surface analysis. J. Cluster Sci. 2016, 27, 2013-2023. doi: 10.1007/s10876-016-1059-y

• 

  Scheme 1  Coordination modes of HATZ

  下载: 全尺寸图片 幻灯片
  

  Figure 1  Anionic structure of 1. The hydrogen atoms, solvent molecules and countervailing cations are omitted for clearly

  下载: 全尺寸图片 幻灯片
  

  Figure 2  Plots of χ_m-T and χ_mT-T for 1. The red solid line represents a fit of data in the temperature range of 22~300 K. Inset: The exchange pathway is between the Fe(III) ions

  下载: 全尺寸图片 幻灯片
  

  Figure 3  (a) dnorm of 1, (b) Full 2D Hirshfeld surface are, (c) Br···H (d) H···H, (e) N···H, (f) C···C fingerprint plots showing the percentages of contacts contributed to the total Hirshfeld surface area of 1

  下载: 全尺寸图片 幻灯片
  

  Figure 4  Thermogravimetric analysis of 1

  下载: 全尺寸图片 幻灯片

  Table 1.  Selected Bond Lengths (Å) and Bond Angles (°) for 1

  Bond	Dist.		Bond	Dist.		Bond	Dist.
  Fe(1)–O(1)	1.919(3)		Fe(2)–O(1)i	1.880(6)		Fe(1)–N(6)	2.078(6)
  Fe(1)–O(2)	1.907(5)		Fe(2)–O(1)	1.880(6)		Fe(1)–N(7)iii	2.145(6)
  Fe(1)–N(1)	2.191(6)		Fe(2)–N(2)	2.113(6)		Fe(2)–N(2)ii	2.113(6)
  Fe(2)–N(2)iii	2.113(6)
  Angle	(°)		Angle	(°)		Angle	(°)
  O(1)–Fe(1)–N(1)	99.70(18)		O(1)–Fe(2)–N(2)ii	86.48(14)		N(7)iii–Fe(1)–N(1)	87.0(2)
  O(1)–Fe(1)–N(3)i	82.99(19)		O(1)–Fe(2)–N(2)	93.52(14)		N(7)iii–Fe(1)–N(3)i	165.6(2)
  O(1)–Fe(1)–N(6)	85.0(2)		O(1)–Fe(2)–N(2)i	93.52(14)		O(2)–Fe(1)–N(1)	172.9(2)
  O(1)–Fe(1)–N(7)iii	83.6(2)		O(1)–Fe(2)–N(2)iii	93.52(14)		O(2)–Fe(1)–N(3)i	96.4(2)
  O(2)–Fe(1)–O(1)	174.68(18)		N(2)i–Fe(2)–N(2)iii	90.216(18)		O(2)–Fe(1)–N(6)	89.8(2)
  N(6)–Fe(1)–N(1)	172.9(2)		O(1)i–Fe(2)–O(1)	180.0		O(2)–Fe(1)–N(7)iii	97.4(2)
  N(6)–Fe(1)–N(3)i	95.8(2)		O(1)–Fe(2)–N(2)i	86.48(14)		O(1)i–Fe(2)–N(2)	86.48(14)
  N(2)iii–Fe(2)–N(2)	173.0(3)		N(2)ii–Fe(2)–N(2)i	173.0(3)		O(1)i–Fe(2)–N(2)ii	93.52(14)
  N(2)i–Fe(2)–N(2)	90.217(18)		O(1)i–Fe(2)–N(2)iii	86.48(14)
  Symmetry transformation: (i) y, –x+1, –z; (ii) –y+1, x, –z; (iii) –x+1, –y+1, z

  下载: 导出CSV

  Table 2.  Hydrogen Bond Lengths (Å) and Bond Angles (°) for 1

  D–H···A	d(D–H)	d(H···A)	d(D···A)	∠DHA
  N(10)–H(10A)···N(5)iv	0.8600	2.4300	2.9126	116.00
  N(10)–H(10B)···O(2)	0.8600	2.3800	3.0351	133.00
  N(10)–H(10B···N(4)iv	0.8600	2.4200	2.9320	119.00
  C(2)–H(2)···N(5)	0.9300	2.3300	2.7485	107.00
  N(9)–H(9)···Br(1)v	0.86	2.80	3.516	141.6
  N(10)–H(10A)···Br(1)v	0.86	2.95	3.672	142.9
  Symmetry codes: (iv) –y+0.5, −x, z−1/4; (v) 0.5−y, x−0.5, 0.5–z

  下载: 导出CSV
•