English

• 0.   Introduction

  Coordination polymers (CPs) based on multiden-tate N-heterocyclic ligands have attracted an upsurge of research interest from past few years owing to their intriguing moleculer topologies and potential applica-tions in gas sorption and storage, catalysis and photo-active devices^[1-11]. In this context, the triazole functional groups is particularly prominent in medicinal chemistry and materials science due to metabolically stable surrogates for a carboxylic acid groups and high density energy materials, respectively^[12]. Especially, triazoles have attracted increasing attention in coor-dination chemistry due to the need for new multi-functional materials and the improvement of research equipment and levels^[13-20]. Based on the use of triazoles as a ligand, the researchers synthesized a series of functional complexes with properties of optics, magnetism, ferroelectric, dielectric and adsorption^[21].

  Herein, we report the syntheses, crystal structures, thermal and fluorescence properties of two new complexs, [Zn(Athy)Br]_n (1, HAthy=HAthy=5-amino-1H-1, 2, 4-triazol-3-ol) and [Mn(Atca)₂(H₂O)₂] (2, HAtca=5-amino-1H-1, 2, 4-triazole-3-carboxylic acid). The two complexes were synthesized in different ways. Complex 1 was discovered from hydrothermal synthesis, but 2 was synthesied by solution diffusion. One of the carboxyl groups in the ligands was reduced to hydroxyl in the synthesis of Complex 1 for synthesis environment with high temperature and high pressure, it is different to the classical reduction of carboxyl reaction^[22]. Complex 1 has a 2D mesh structure, and 2 has a 3D framework with rich hydrogen bonding interactions. To our surprise, Complexes 1 and 2 both have strong photoluminescence properties, and might be potential blue fluorescent materials.

  1.   Experimental

  1.1   Materials and physical techniques

  All reagents and solvents were obtained from commercial sources and used directly without further purification. PL emission spectra were measured at room temperature on a fluorophotometer (JASCO, FP-6500). The elemental analyses were measured on a Vario EL Ⅲ elemental analyzer. Powder X-ray diffraction (PXRD) data were recorded on a Rigaku D/MAX 2000 PC X-ray diffraction instrument(Cu Kα, λ_α1=0.015 405 98 nm, λ_α2=0.015 444 26 nm), under the generator voltage (40 kV) and tube current (40 mA), by using continuous scan type from 5.0° to 50.0° at room temperature.

  1.2   Syntheses of the complexes

  1.2.1   Synthesis of 1

  As shown in Scheme 1, hydrothermal reaction of HAtca (0.025 6 g, 0.2 mmol) and ZnBr₂ (0.045 g, 0.2 mmol) in a mixed solution of ethanol (1 mL) and water (6 mL) at 140 ℃ for 2 days gave the colorless block crystals for 1. Yield: 17.97mg, 70.2% based on HAtca. Anal. Calcd. for C₁₆H₁₈Br₈N₃₂O₂Zn₈(%): C, 10.37; H, 0.98; N, 24.19. Found(%): C, 10.35; H, 0.94; N, 24.09. IR (KBr, cm^-1): 3 608(m), 3 450(s), 2 331(m), 1 631(s), 1 487(s), 1 295(s), 1 148(w), 829(w), 712 (m), 463(w).

  1.2.2   Synthesis of 2

  As shown in Scheme 1, complex 2 has been synthezied by solution diffusion. Single crystals were obtained by a three-layer crystallization: the lower layer was MnCl₂ (0.063 g, 0.5 mmol) dissolved in a mixed solution of ethanol (3 mL) and water (1 mL); the middle layer was a mixed solution of ethanol (3 mL) and water (3 mL); and the top layer was a neutral HAtca aqueous (0.064 g, 0.5 mmol, 5 mL) with pH value adjusted by NaOH (0.10 mL, 1 mol·L^-1). Colorless block crystals appeared after 9~10 days. Yield: 13.50 mg, 21.1% based on HAtca. Anal. Calcd. for C₆H₁₀N₈O₆Mn(%): C, 20.88; H, 2.92; N, 32.46. Found(%): C, 20.94; H, 2.31; N, 32.52. IR (KBr, cm^-1): 3 422(m), 3 370(m), 1 633(s), 1 476(m), 1 411(w), 1 285(s), 1 103(s), 835(w), 719(w), 471(w).

  Scheme 1

  

  Scheme 1.  Preparation of complexes 1 and 2

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  1.3   Crystallography

  X-ray single crystal diffraction data for 1 and 2 was collected on a Bruker P4 diffractometer with Mo Kα radiation (λ=0.071 073 nm) at 293 K using φ-ω scan technique and corrected by Lorentz-polarization and absorption corrections^[23-24]. Both crystal structures were solved by direct method and refined by full-matrix method based on F² by means of SHELXTL software package^[25]. Non-H atoms were refined anisotropically using all reflections with I>2σ(I). The organic H atoms were generated geometrically; the water H atoms were generated geometrically and refined with isotropic temperature factors. Crystal data and structure refinement parameters for 1 and 2 are listed in Table 1.

  Table 1

  

  Table 1.  Crystal data and structure refinement parameters for 1 and 2

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  Complex	1	2
  Empirical formula	C16H18Br8N32O2Zn8	C6H10N8O6Mn
  Formula weight	1 852.86	345.16
  Crystal system	Orthorhombic	Monoclinic
  Space group	Pbca	P21/c
  a/nm	0.942 86(8)	0.945 38(9)
  b/nm	1.003 95(8)	0.931 54(9)
  c/nm	1.228 81(11)	0.679 09(7)
  β/(°)		98.005(2)
  V/nm3	1.163 17(17)	0.592 22(10)
  Dc/(g·cm-3)	2.645	1.936
  Z	1	2
  μ/mm-1	10.984	1.164
  F(000)	874.0	350
  Data, restraint, parameter	1 331, 1, 83	2 891, 2, 97
  GOF	1.161	1.072
  Final R indexes [I>2σ(I)]	0.054 1, 0.108 7	0.028 1, 0.071 3
  Final R indexes (all data)	0.063 5, 0.112 1	0.033 5, 0.074 3
  (Δρ)max, (Δρ)min/(e·nm-3)	1 490, -2 260	652, -327
  aR1=∑||Fo|-|Fc||/∑|Fo|; bwR2=[∑w(Fo2-Fc2)2/w(Fo2)2]1/2.

  CCDC: 1833088, 1; 1575499, 2.

  2.   Results and discussion

  2.1   Crystal structures of 1 and 2

  The complexes were synthesized in different ways: 1 was discovered from hydrothermal synthesis, but 2 was synthesized by solution diffusion. It is worth mentioning that HAthy ligand in 1 underwent a de-carbonyl reaction and changed into hydroxyl functional groups under hydrothermal conditions, in which the Zn²⁺ ions act as Lewis acid. The carboxyl groups are prone to de-acidification at high temperature in the presence of Lewis acid. This kind of organic synthesis reaction has been applied in chemical production^[26].

  Single crystal X-ray diffraction analyses reveal that 1 belongs to orthorhombic crystal system with Pbca space group. The asymmetric unit consists of one Zn(Ⅱ) cation, one deprotonated HAthy ligand, and one coordination Br anion. The coordination environment of 1 is depicted in Fig. 1a.

  Figure 1

  

  Figure 1.  Coordinated environment of 1 (a) and 2 (b)

  Symmetry codes: ^ⅰ-x, -y, -z; ⅱ -1/2+x, 1/2-y, -z for 1; ^ⅰ -x+1, -y+1, -z+1 for 2

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  Meanwhile, the O atom in the hydroxyl group is not involved in the coordination. Complementary, the N atoms in pyrrol group play a very important role because the deprotonated N atoms balance the charge of complex. As shown in Fig. 1a. The center Zn(Ⅱ) cation is coordinated with three N atoms (N2, N3, N4) from HApyo ligand and one Br anion. The selected bond lengths and angles for Complex 1 are summarized in Table 2. All the data indicate that the center Zn(Ⅱ) adopts slightly distorted tetra-coordinated tetrahedron geometry. The 2D structure of Complex 1 can be found that the layers are interlaced with each other through Zn coordinated with the N atoms in deprotonated HAthy ligand observed along a, b and c axis. (Fig.S1).

  Table 2

  

  Table 2.  Selected bond lengths (nm) and angles (°) of complex 1

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  Zn1(Ⅱ)Br1	0.234 77(12)	N2(Ⅱ)C1	0.133 4(8)	N3(Ⅱ)N2ⅰ	0.138 2(8)
  Zn1(Ⅱ)N2	0.199 8(6)	N4(Ⅱ)C1ⅱ	0.134 3(8)	N3(Ⅱ)C2ⅳ	0.132 3(9)
  Zn1(Ⅱ)N3	0.199 5(6)	N4(Ⅱ)C2	0.134 9(8)	C2(Ⅱ)N3ⅴ	0.132 3(9)
  Zn1(Ⅱ)N4	0.200 8(5)	C1(Ⅱ)N4ⅲ	0.134 3(8)	C2(Ⅱ)O1	0.127(3)
  N2(Ⅱ)N3ⅰ	0.138 2(8)	N1(Ⅱ)C1	0.133 8(11)
  N2(Ⅱ)Zn1(Ⅱ)Br1	111.99(17)	C1(Ⅱ)N2(Ⅱ)N3i	105.6(5)	N1(Ⅱ)C1(Ⅱ)N4ⅲ	123.5(7)
  N2(Ⅱ)Zn1(Ⅱ)N4	108.2(2)	N3ⅰ(Ⅱ)N2(Ⅱ)Zn1	126.1(4)	N2ⅰ(Ⅱ)N3(Ⅱ)Zn1	125.7(4)
  N4(Ⅱ)Zn1(Ⅱ)Br1	107.45(16)	C1ⅱ(Ⅱ)N4(Ⅱ)Zn1	130.8(5)	C2ⅳ(Ⅱ)N3(Ⅱ)Zn1	127.8(5)
  N3(Ⅱ)Zn1(Ⅱ)Br1	114.66(18)	C1ⅱ(Ⅱ)N4(Ⅱ)C2	103.8(6)	C2ⅳ(Ⅱ)N3(Ⅱ)N2ⅰ	106.5(5)
  N3(Ⅱ)Zn1(Ⅱ)N2	107.7(2)	C2(Ⅱ)N4(Ⅱ)Zn1	125.4(5)	N3ⅴ(Ⅱ)C2(Ⅱ)N4	111.9(6)
  N3(Ⅱ)Zn1(Ⅱ)N4	107.6(2)	N2(Ⅱ)C1(Ⅱ)N4ⅲ	112.1(6)	O1(Ⅱ)C2(Ⅱ)N4	125.7(13)
  C1(Ⅱ)N2(Ⅱ)Zn1	127.5(5)	N2(Ⅱ)C1(Ⅱ)N1	124.4(7)	O1(Ⅱ)C2(Ⅱ)N3v	122.2(13)
  Symmetry codes: ⅰ -x, -y, -z; ⅱ 1/2+x, 1/2-y, -z; ⅲ -1/2+x, 1/2-y, -z; ⅳ1/2-x, -1/2+y, z; ⅴ1/2-x, 1/2+y, z.

  Four metal ions and four deprotonated HAthy ligand ligands are arranged alternately into a 16-membered big ring (A) structure, and two deprotonated HAthy ligands also form a 6-membered little ring (B) structure with two metal ions, as shown in Fig. 2. Each little ring is surrounded by four big rings, meanwhile, each big ring is adjacent to four big rings and four small rings, forming a stable 2D network structure.

  Figure 2

  

  Figure 2.  Packing view of 2D sheets along c axis in 1

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  Complex 2 crystallizes in the monoclinic system, space group P2₁/c. The asymmetric unit of 2 is composed of half Mn(Ⅱ) cation, one Atca ligand and one coordinated water molecule. As shown in Fig. 1b, the coordination of metal Mn(Ⅱ) and Atca ligands is relatively simple, and the coordinated geometry around Mn(Ⅱ) center can be viewed as a slightly distorted octahedron. The angle between the line L (O1W-Mn-O1W^ⅰ) and plane S (N1-O2-N1^ⅰ-O2^ⅰ) is 86.822(31)°, which is surrounded by two N atoms and two O atoms from two chelating Atca ligands and two coordinated water molecules. Selected bond lengths and angles for 2 are listed in Table 3.

  Table 3

  

  Table 3.  Selected bond lengths (nm) and angles (°) of complex 2

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  Mn(1)-N(1)	0.220 52(7)	Mn(1)-O(1W)	0.220 86(7)	Mn(1)-O(2)	0.224 06(7)
  N(1)-Mn(1)-N(1)ⅰ	180.0	N(1)-Mn(1)-O(1W)ⅰ	90.77(3)	O(1W)-Mn(1)-O(2)	86.82(3)
  N(1)-Mn(1)-O(1W)	89.23(3)	O(1)-C(1)-O(2)	125.59(8)	O(1W)ⅰ-Mn(1)-O(1W)	180.0
  N(1)-Mn(1)-O(2)ⅰ	104.66(2)	N(1)ⅰ-Mn(1)-O(2)ⅰ	75.34(2)	O(2)ⅰ-Mn(1)-O(2)	180.00(4)
  O(1W)-Mn(1)-O(2)ⅰ	93.18(3)	N(1)-Mn(1)-O(2)	75.34(2)
  Symmetry codes: ⅰ -x+1, -y+1, -z+1.

  Metal cations are aligned in parallel lines, no matter which axis they are viewed from(Fig.S2). Meanwhile, the alternate arrangement of adjacent pairs of complex can be observed from a axis. It can be seen clearly from the structure of 2 that carboxyl group acts as a receptor, amino group as a donor, and the coordinated water as both a receptor and a donor in hydrogen bond. The molecules of each complex are connected to the surrounding molecules by hydrogen bonds (Fig. 3a). The bond lengths and bond angles of hydrogen bonds of the complex are 0.25~0.32 nm and 130°~180°(Table 4), respectively, so they can be judged as a moderate hydrogen bond interaction (Fig. 3b). Obviously, two strong hydrogen bonds, O1W…O1^ⅰ and O2^ⅲ…O1W connect two adjacent parts, and form a stable 12-membered ring (#-metal ion-coordination water…carboxyl-metal ion-coordination water…carboxyl-#), which is then connected into a two-dimensional mesh structure. At the same time, the relatively weak hydrogen bond (N4…O1W^ⅱ) also increases the stability of structure. The other two relatively weak hydrogen bonds, N4…N2^ⅰ and N3…O1^ⅰ connects the two adjacent complex at the upper right to form a 10-membered ring between the two ligands. The above two-dimensional mesh structure is connected to form a highly stable 3D grid structure (Fig.S3).

  Table 4

  

  Table 4.  Hydrogen bond parameters of complex 2

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  D-H…A	d(D-H)/nm	d(H…A)/nm	d(D…A)/nm	∠D-H…A/(°)
  N(4)-H(4B)…O(1W)ⅱ	0.085	0.214	0.293 54(12)	159.6
  N(4)-H(4A)…N(2)ⅰ	0.084	0.207	0.290 57(12)	168.3
  N(3)-H(3)…O(1)ⅰ	0.083	0.207	0.289 30(10)	175.4
  O(1W)-H(1WB)…O(1)ⅱ	0.082	0.196	0.275 41(10)	164.6
  O(1W)-H(1WA)…O(2)ⅲ	0.080	0.198	0.274 94(9)	164.0
  Symmetry codes: ⅰx, 1/2+y, 1/2-z; ⅱ 1-x, -1/2+y, 1/2-z; ⅲ x, 3/2-y, -1/2+z.

  Figure 3

  

  Figure 3.  Hydrogen bonds in complex 2

  Symmetry codes: ^ⅰx, 1/2+y, 1/2-z; ^ⅱ1-x, -1/2+y, 1/2-z; ^ⅲx, 3/2-y, -1/2+z

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  2.2   Fluorescence properties and powder X-ray diffraction analysis

  It is generally assumed that transition metal coordination complexes formed by Zn or Mn centers possess excellent luminescent properties, because core-liked d-orbitals and d-d transitions. At the same time, most of the functional complexes constructed by nitrogen heterocyclic organic ligands also have potential applications in the field of fluorescence emission materials. Organic materials can influence the emission of wavelength. So the reasonable selection of organic ligands and central metals (such as Zn(Ⅱ), Cd(Ⅱ), Mn(Ⅱ)) to synthesize functional complexes is an effective way to obtain luminescent materials.

  The photoluminescent properties of 1 and 2 were investigated in solid state at room temperature (Fig. 4), while the ligand had no photoluminescent properties. When excited at 281 nm (Fig.S4), Complex 1 showed two broad emissions at 400 and 490 nm, which is probably due to a mixture of intra-ligand and ligand-to-ligand charge transition (LLCT)^[27-28]. Complex 2 exhibited two broad emissions at 382 and 402 nm when excited at 349 nm, similarly. The emissions of 2 also may be a mixture of intra-ligand and ligand-to-ligand charge transition (LLCT). And complex 2 had a hypsochromic shift of 60 nm considered to mainly originate from the influence of the coordination of the ligand to Mn(Ⅱ) ion^[29-30].

  Figure 4

  

  Figure 4.  Fluorescence emission spectra and fluorescence lifetime of 1 (a) and 2 (b) in solid-sate at room temperature

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  In addition, the significant increase in fluore-scence lifetime of 1 compared with 2 (the fluorescence lifetime of Complex 1 is 400 times that of complex 2) is tentatively attributed to the relative proportion of central metal cations and the difference of coordina-tion Br anions in coordination polymers (Fig. 4). It means that the complexes 1 may have better application prospects in blue light materials.

  2.3   PXRD and thermogravimetric analysis

  As shown in Fig. 5, the PXRD patterns of complexes of 1 and 2 show that their products are very highly crystalline^[31-33].

  Figure 5

  

  Figure 5.  Powder XRD patterns of complexes 1 (a) and 2 (b)

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  Complexes 1 and 2 are two-dimensional structures and flexible mononuclear structures respectively, but all have been constructed three dimensions grid structure by hydrogen bonds. Moreover, the hydrogen bonds in the complex 2 also increase the thermal stability of the structure. The thermal stabilities of Complex 1 and 2 were tested in a range of 300~1 100 K under a nitrogen atmosphere at a heating of 10 K·min^-1, and TGA curves of complexes 1 and 2 are shown in Fig. 6.

  Figure 6

  

  Figure 6.  TG and DTA curves of complexes 1 (a) and 2 (b)

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  As shown in Fig. 6a, when the temperature was less than 750 K, Complex 1 had higher thermal stability. Complex 1 had a downward peak near 769 K in the DTA curve, which may be due to high nitrogen content and high energy content of Complex 1. As well, it was preliminarily determined that the decomposition rate of 1 near 769K was the fastest, and then the structure completely collapsed and decomposed. However, the DTA curve of complex 2 had an upward peak in vicinity of 536 K (Fig. 6b), which may be caused by coordination of complex 2 with more water and a relatively high proportion of water in 2.

  The results indicate that Complex 1 has better thermal stability than 2, and the changes of their structure with temperature are represented by DSC, respectively (Fig.S5).

  3.   Conclusions

  In summary, we have successfully synthesized two novel transition metal triazole carboxylic complexes [Zn(Athy)Br]_n (1) and [Mn(Atca)₂(H₂O)₂] (2) through hydrothermal method and diffusion method, respectively. In the process of hydrothermal synthesis, the carboxyl group on triazole of Complex 1 was reduced to the hydroxyl group. Complexes 1 and 2 have blue and violet fluorescence properties, respectively, indicating potential applications in photoluminescence materials.

  Acknowledgments: Dr. Tan is grateful for the support from the National Natural Science Foundation of China (Grants No.21471070, 21761013, 21671086, 21461010), the Academic leader Foundation of Jiangxi Province and Jiangxi Science and Technology Department (Grant No.20153BCB22006).

  Supporting information is available at http://www.wjhxxb.cn

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• 

  Scheme 1  Preparation of complexes 1 and 2

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  Figure 1  Coordinated environment of 1 (a) and 2 (b)

  Symmetry codes: ^ⅰ-x, -y, -z; ⅱ -1/2+x, 1/2-y, -z for 1; ^ⅰ -x+1, -y+1, -z+1 for 2

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  Figure 2  Packing view of 2D sheets along c axis in 1

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  Figure 3  Hydrogen bonds in complex 2

  Symmetry codes: ^ⅰx, 1/2+y, 1/2-z; ^ⅱ1-x, -1/2+y, 1/2-z; ^ⅲx, 3/2-y, -1/2+z

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  Figure 4  Fluorescence emission spectra and fluorescence lifetime of 1 (a) and 2 (b) in solid-sate at room temperature

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  Figure 5  Powder XRD patterns of complexes 1 (a) and 2 (b)

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  Figure 6  TG and DTA curves of complexes 1 (a) and 2 (b)

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  Table 1.  Crystal data and structure refinement parameters for 1 and 2

  Complex	1	2
  Empirical formula	C16H18Br8N32O2Zn8	C6H10N8O6Mn
  Formula weight	1 852.86	345.16
  Crystal system	Orthorhombic	Monoclinic
  Space group	Pbca	P21/c
  a/nm	0.942 86(8)	0.945 38(9)
  b/nm	1.003 95(8)	0.931 54(9)
  c/nm	1.228 81(11)	0.679 09(7)
  β/(°)		98.005(2)
  V/nm3	1.163 17(17)	0.592 22(10)
  Dc/(g·cm-3)	2.645	1.936
  Z	1	2
  μ/mm-1	10.984	1.164
  F(000)	874.0	350
  Data, restraint, parameter	1 331, 1, 83	2 891, 2, 97
  GOF	1.161	1.072
  Final R indexes [I>2σ(I)]	0.054 1, 0.108 7	0.028 1, 0.071 3
  Final R indexes (all data)	0.063 5, 0.112 1	0.033 5, 0.074 3
  (Δρ)max, (Δρ)min/(e·nm-3)	1 490, -2 260	652, -327
  aR1=∑||Fo|-|Fc||/∑|Fo|; bwR2=[∑w(Fo2-Fc2)2/w(Fo2)2]1/2.

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  Table 2.  Selected bond lengths (nm) and angles (°) of complex 1

  Zn1(Ⅱ)Br1	0.234 77(12)	N2(Ⅱ)C1	0.133 4(8)	N3(Ⅱ)N2ⅰ	0.138 2(8)
  Zn1(Ⅱ)N2	0.199 8(6)	N4(Ⅱ)C1ⅱ	0.134 3(8)	N3(Ⅱ)C2ⅳ	0.132 3(9)
  Zn1(Ⅱ)N3	0.199 5(6)	N4(Ⅱ)C2	0.134 9(8)	C2(Ⅱ)N3ⅴ	0.132 3(9)
  Zn1(Ⅱ)N4	0.200 8(5)	C1(Ⅱ)N4ⅲ	0.134 3(8)	C2(Ⅱ)O1	0.127(3)
  N2(Ⅱ)N3ⅰ	0.138 2(8)	N1(Ⅱ)C1	0.133 8(11)
  N2(Ⅱ)Zn1(Ⅱ)Br1	111.99(17)	C1(Ⅱ)N2(Ⅱ)N3i	105.6(5)	N1(Ⅱ)C1(Ⅱ)N4ⅲ	123.5(7)
  N2(Ⅱ)Zn1(Ⅱ)N4	108.2(2)	N3ⅰ(Ⅱ)N2(Ⅱ)Zn1	126.1(4)	N2ⅰ(Ⅱ)N3(Ⅱ)Zn1	125.7(4)
  N4(Ⅱ)Zn1(Ⅱ)Br1	107.45(16)	C1ⅱ(Ⅱ)N4(Ⅱ)Zn1	130.8(5)	C2ⅳ(Ⅱ)N3(Ⅱ)Zn1	127.8(5)
  N3(Ⅱ)Zn1(Ⅱ)Br1	114.66(18)	C1ⅱ(Ⅱ)N4(Ⅱ)C2	103.8(6)	C2ⅳ(Ⅱ)N3(Ⅱ)N2ⅰ	106.5(5)
  N3(Ⅱ)Zn1(Ⅱ)N2	107.7(2)	C2(Ⅱ)N4(Ⅱ)Zn1	125.4(5)	N3ⅴ(Ⅱ)C2(Ⅱ)N4	111.9(6)
  N3(Ⅱ)Zn1(Ⅱ)N4	107.6(2)	N2(Ⅱ)C1(Ⅱ)N4ⅲ	112.1(6)	O1(Ⅱ)C2(Ⅱ)N4	125.7(13)
  C1(Ⅱ)N2(Ⅱ)Zn1	127.5(5)	N2(Ⅱ)C1(Ⅱ)N1	124.4(7)	O1(Ⅱ)C2(Ⅱ)N3v	122.2(13)
  Symmetry codes: ⅰ -x, -y, -z; ⅱ 1/2+x, 1/2-y, -z; ⅲ -1/2+x, 1/2-y, -z; ⅳ1/2-x, -1/2+y, z; ⅴ1/2-x, 1/2+y, z.

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  Table 3.  Selected bond lengths (nm) and angles (°) of complex 2

  Mn(1)-N(1)	0.220 52(7)	Mn(1)-O(1W)	0.220 86(7)	Mn(1)-O(2)	0.224 06(7)
  N(1)-Mn(1)-N(1)ⅰ	180.0	N(1)-Mn(1)-O(1W)ⅰ	90.77(3)	O(1W)-Mn(1)-O(2)	86.82(3)
  N(1)-Mn(1)-O(1W)	89.23(3)	O(1)-C(1)-O(2)	125.59(8)	O(1W)ⅰ-Mn(1)-O(1W)	180.0
  N(1)-Mn(1)-O(2)ⅰ	104.66(2)	N(1)ⅰ-Mn(1)-O(2)ⅰ	75.34(2)	O(2)ⅰ-Mn(1)-O(2)	180.00(4)
  O(1W)-Mn(1)-O(2)ⅰ	93.18(3)	N(1)-Mn(1)-O(2)	75.34(2)
  Symmetry codes: ⅰ -x+1, -y+1, -z+1.

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  Table 4.  Hydrogen bond parameters of complex 2

  D-H…A	d(D-H)/nm	d(H…A)/nm	d(D…A)/nm	∠D-H…A/(°)
  N(4)-H(4B)…O(1W)ⅱ	0.085	0.214	0.293 54(12)	159.6
  N(4)-H(4A)…N(2)ⅰ	0.084	0.207	0.290 57(12)	168.3
  N(3)-H(3)…O(1)ⅰ	0.083	0.207	0.289 30(10)	175.4
  O(1W)-H(1WB)…O(1)ⅱ	0.082	0.196	0.275 41(10)	164.6
  O(1W)-H(1WA)…O(2)ⅲ	0.080	0.198	0.274 94(9)	164.0
  Symmetry codes: ⅰx, 1/2+y, 1/2-z; ⅱ 1-x, -1/2+y, 1/2-z; ⅲ x, 3/2-y, -1/2+z.

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