A novel three-dimensional hetero­metallic coordination polymer: poly[[hexa­aqua­bis[μ₃-3,5-dicarboxyl­ato­pyrazol­ato-κ⁵O³,N²:N¹,O⁵:O^5′](μ₂-oxalato-κ⁴O¹,O²:O^1′,O^2′)copper(II)dierbium(III)] trihydrate]

The title novel heterometallic 3d–4f coord­ination polymer, {[CuEr₂(C₅HN₂O₄)₂(C₂O₄)(H₂O)₆]·3H₂O}_n, has a three-dim­ensional metal–organic framework composed of two types of metal atoms (one Cu^II and two Er^III) and two types of bridging anionic ligands [3,5-dicarboxyl­ato­pyrazol­ate(3−) (ptc³⁻) and oxalate]. The Cu^II atom is four-coord­inated in a square geometry. The Er^III atoms are both eight-coordinated, but the geometries at the two atoms appear different, viz. triangular dodeca­hedral and bicapped trigonal prismatic. One of the oxalate anions is located on a twofold axis and the other lies about an inversion centre. Both oxalate anions act as bis-bidentate ligands bridging the latter type of Er atoms in parallel zigzag chains. The pdc³⁻ anions act as quin­quedentate ligands not only chelating the Cu^II and the triangular dodeca­hedral Er^III centres in a bis­-bidentate bridg­ing mode, but also connecting to Er^III centres of both types in a monodentate bridging mode. Thus, a three-dim­ensional metal–organic framework is generated, and hydrogen bonds link the metal–organic framework with the uncoordinated water mol­ecules. This study describes the first example of a three-dimensional 3d–4f coordination polymer based on pyrazole-3,5-dicarboxylate and oxalate, and therefore demonstrates further the usefulness of pyrazoledicarboxylate as a versatile multidentate ligand for constructing heterometallic 3d–4f coordination polymers with interesting architectures.

S1. Comment

Much attention has been focused on the construction of heterometallic 3d–4f complexes since 1985 (Bencini et al., 1985), not only because of their potential applications in magnetism (Mereacre et al., 2007), luminescence (Sun et al., 2006) and gas storage (Wang et al., 2007) but also owing to their fascinating structures (Andruh, 2007; Yabe et al., 2007; Ren et al., 2008). With the purpose of the design and synthesis of 3d–4f coordination polymers with interesting architectures and topologies, a variety of multifunctional bridging ligands have been extensively employed, such as 2,2':6',2"-terpyridine (Figuerola et al., 2006), pyridine-2,4,6-tricarboxylic acid (Gao et al., 2006), iminodiacetate (Manna et al., 2007) and amino acids (Zhang et al., 2004). In view of the potential coordination sites afforded by the carboxylate O and pyrazole N atoms of 3,5-pyrazoledicarboxylic acid (H₃pdc), the fully deprotonated pdc^3- ligand can act as a mono-, bi- or multidentate ligand to link metal centres, generating coordination polymers, as is reported in the literature (Xia et al., 2007; King et al., 2004). However, no three-dimensional heterometallic 3d–4f coordination polymers based on pyrazole-3,5-dicarboxylate have been reported before. In this paper, we describe the synthesis of a novel 3d–4f coordination polymer, namely, [Cu(pdc)₂Er₂(C₂O₄)(H₂O)₆.3H₂O]_n, (I), by the reaction of H₃pdc with Er₂O₃ and CuO via a hydrothermal method; the compound has been characterized by IR, elemental analysis and X-ray single-crystal analysis.

Since no oxalate was directly introduced into the starting reaction mixture, we suppose that the oxalate ligand was synthesized in situ through an oxidation–hydrolysis reaction from pyrazole-3,5-dicarboxylic acid (see scheme below). Similar situations also occurred in other systems (Cheng et al., 2007; Li et al., 2006).

X-ray crystal structure analysis reveals that the title complex crystallizes in the centrosymmetric space group C2/c with two crystallographically independent oxalate ligands on twofold axes. A perspective view of the molecular structure of the title complex is depicted in Fig. 1, and selected bond lengths and angles are listed in Table 1.

As illustrated in Fig. 1, the title complex consists of two types of metal atoms (one Cu^II and two Er^III atoms) and two types of bridged ligands (ptc^3- and oxalate anions). The Cu^II atom assumes a square geometry, coordinated to two ptc^3- anions through carboxyl O and pyrazole N atoms in a bis-chelating fashion (O1, N1 and O5, N3). The Cu–O(N) bond lengths [1.887 (8)–1.964 (6) Å] and the angles around Cu^II atom [82.6 (3)–97.3 (4)°] are in good agreement with those in some related Cu^IIcomplexes (King et al., 2004) and Cu–Ln complexes (Liang et al., 2001; Costes et al., 2004; Wu et al., 2005). It is interesting to find two crystallographically independent eight-coordinated Er^III atoms (Er1 and Er2) in the title complex, and the geometries at Er1 and Er2 appear different when analysed using the usual considerations of Haigh (1995). Atom Er1 assumes a triangular–dodecahedral geometry, coordinated by three aqua ligands and three pdc^3- anions, that is, by one carboxyl O atom from a ptc^3- anion in a monodentate fashion (O4ⁱ) and two pairs of carboxyl O and pyrazole N atoms from two different ptc^3- ligands in a bis-chelating fashion (O3, N2, O7 and N4). The Er1–O(N) bond lengths range from 2.295 (7) to 2.492 (8) Å, comparable to those observed in other Er^III complexes (Xia et al., 2007; Lu et al., 2002). In contrast, atom Er2 assumes a bicapped trigonal–prismatic geometry, coordinated to three aqua ligands, one carboxyl O atom from a pdc^3- ligand and four O atoms from two different oxalate ligands in a bis-chelating fashion. The oxalate anions are both located on twofold axes, acting as bis-bidentate ligands to bridge Er2 atoms in a zigzag chain, as is observed in other Er^III complexes (Li et al., 2006; Lu et al., 2002). It is noted that the oxalate–Er2 chains lie parallel to one another. The bond lengths around atom Er2 [2.222 (7)–2.438 (7) Å] are in the normal range for Er^III atoms (Feng & Mao, 2007; Song & Mao, 2005; Subhan et al., 2002). As quinquedentate ligands, the pdc^3- anions link three different metal atoms, on the one hand chelating the Cu^II and Er^III centres in a bis-bidentate bridging mode to form a nearly coplanar building block, [CuEr1(pdc)₂]^-, and on the other hand connecting to another different Er^III center (Er1 or Er2) in a monodentate bridging mode. In this way, the parallel oxalate–Er2 chains are connected by pairs of [CuEr1(pdc)₂]^- blocks. Thus, a three-dimensional metal–organic framework is generated through the bridging ligands (Fig. 2).

Furthermore, the solvent water molecules are located in cavities of the metal–organic framework, allowing them to participate in various O—H···O hydrogen bonds with the coordinated water molecules and carboxylate O atoms. Finally, the three-dimensional metal–organic framework is linked with the uncoordinated water molecules by hydrogen bonds, which are all in the normal range and are given in Table 2. It is noted that the potential free volume accessible for water molecules determined by PLATON calculations (Spek, 2003) is about 2.1%. According to Kitagawa et al. (2004), the pore size in the polymer is about 4.7 Å (<5 Å), falling into the ultramicropore range. Therefore, the polymeric structure is considered to be poor for gas storage.

Related literature

For related literature, see: Andruh (2007); Bencini et al. (1985); Cheng et al. (2007); Costes et al. (2004); Feng & Mao (2007); Figuerola et al. (2006); Gao et al. (2006); Haigh (1995); King et al. (2004); Kitagawa et al. (2004); Li et al. (2006); Liang et al. (2001); Lu et al. (2002); Manna et al. (2007); Mereacre et al. (2007); Ren et al. (2008); Song & Mao (2005); Spek (2003); Subhan et al. (2002); Sun et al. (2006); Wang et al. (2007); Wu et al. (2005); Xia et al. (2007); Yabe et al. (2007); Zhang et al. (2004).

S2. Experimental

All chemicals were of analytical grade and were used without further purification. The hydrothermal reaction was performed in a 25 ml Teflon-lined stainless steel autoclave under autogenous pressure. A mixture solution of H₃pdc (0.070 g,0.4 mmol), Er₂O₃ (0.038 g, 0.1 mmol), CuO (0.016 g, 0.2 mmol) and water (3 ml) was placed in a 25 ml Teflon-lined autoclave and heated at 413 K for 5 d. After the sample was cooled slowly at a rate of 10 K h^-1 to room temperature, purple–red crystals of the title complex were obtained and air-dried by filtration (ca 15% yield based on Er). Analysis calculated for C₁₂H₂₀CuEr₂N₄O₂₁: C 15.10, H 2.11, N 5.87%; found: C 15.14, H 2.02, N 5.85%. IR (KBr discs, ν_max, cm^-1): 3449 (vs), 1629 (vs), 1571 (s), 1525 (m),1511 (m), 1403 (m), 1339 (vs), 1283 (s), 1064 (m), 1018 (m), 858 (w), 806 (m), 776 (w), 613 (w), 493 (w), 436 (w).

S3. Refinement

All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms [C—H = 0.93 Å, O—H = 0.92–0.95 Å and U_iso(H) = 1.2U_eq(C,O)].

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The Cu^II and Er^III coordination environments. Displacement ellipsoids are drawn at the 30% probability. H atoms have been omitted for clarity. [Symmetry codes: (i) -x + 3/2, y - 1/2, -z + 1/2; (ii) -x + 3/2, y + 1/2, -z + 1/2; (iii) -x + 2, y, -z + 1/2; (iv) -x + 2, -y + 2, -z + 1.] Don't match table 2
	Fig. 2. The packing of the title complex, viewed along the b axis, showing a three-dimensional metal–organic framework. Dashed lines indicate hydrogen bonds.

poly[[hexaaquabis[µ₃-3,5-dicarboxylatopyrazolato- κ⁵O³,N²:N¹,O⁵:O^5'](µ₂-oxalato- κ⁴O¹,O²:O^1',O^2')copper(II)dierbium(III)] trihydrate]

Crystal data

[CuEr2(C5HN2O4)2(C2O4)(H2O)6]·3H2O	Z = 8
Mr = 954.38	F(000) = 3624
Monoclinic, C2/c	Dx = 2.606 Mg m^−3
Hall symbol: -C 2yc	Mo Kα radiation, λ = 0.71073 Å
a = 37.829 (9) Å	µ = 7.81 mm^−1
b = 6.9457 (16) Å	T = 295 K
c = 22.772 (5) Å	Block, purple-red
β = 125.607 (4)°	0.4 × 0.3 × 0.2 mm
V = 4864.6 (19) Å^3

Data collection

Bruker SMART APEX CCD area-detector diffractometer	4281 independent reflections
Radiation source: fine-focus sealed tube	3070 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.074
ϕ and ω scans	θmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −43→44
Tmin = 0.07, Tmax = 0.21	k = −7→8
11670 measured reflections	l = −26→19

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.080	H-atom parameters constrained
S = 0.86	w = 1/[σ^2(Fo^2) + (0.01P)^2] where P = (Fo^2 + 2Fc^2)/3
4281 reflections	(Δ/σ)max = 0.001
310 parameters	Δρmax = 1.54 e Å^−3
0 restraints	Δρmin = −0.89 e Å^−3

Special details

Experimental. The elemental analysis was carried out on a Perkin–Elmer 240?C. Infrared spectra were recorded from KBr discs in the range of 4000_{400?cm-1 on a VECTOR-22 spectrometer.}

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

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cu1	0.75392 (4)	0.99618 (19)	−0.00235 (7)	0.0223 (3)
Er1	0.807097 (16)	1.03018 (7)	0.23411 (3)	0.02228 (15)
Er2	1.003527 (15)	0.76470 (7)	0.38941 (3)	0.01919 (14)
C1	0.6683 (3)	1.1134 (14)	−0.0793 (6)	0.018 (2)
C2	0.6866 (3)	1.1376 (16)	−0.0026 (6)	0.0235 (13)
C3	0.6713 (3)	1.2018 (14)	0.0364 (6)	0.022 (3)
H3	0.6437	1.2464	0.0195	0.027*
C4	0.7078 (3)	1.1832 (15)	0.1070 (5)	0.021 (3)
C5	0.7157 (4)	1.2328 (17)	0.1785 (6)	0.027 (3)
N1	0.7288 (3)	1.0917 (12)	0.0431 (4)	0.0235 (13)
N2	0.7422 (3)	1.1173 (12)	0.1114 (4)	0.0235 (13)
O1	0.6961 (2)	1.0535 (10)	−0.0904 (3)	0.0224 (18)
O2	0.6304 (2)	1.1490 (11)	−0.1273 (4)	0.032 (2)
O3	0.7505 (2)	1.1632 (11)	0.2324 (4)	0.035 (2)
O4	0.6889 (2)	1.3355 (11)	0.1785 (4)	0.030 (2)
C6	0.8205 (3)	0.8548 (15)	−0.0056 (6)	0.0215 (18)
C7	0.8382 (3)	0.8709 (14)	0.0706 (6)	0.0215 (18)
C8	0.8769 (4)	0.8305 (15)	0.1366 (6)	0.032 (3)
H8	0.9022	0.7802	0.1449	0.039*
C9	0.8691 (3)	0.8802 (15)	0.1867 (6)	0.023 (3)
C10	0.8952 (3)	0.8658 (15)	0.2658 (6)	0.023 (3)
N3	0.8102 (3)	0.9429 (12)	0.0832 (4)	0.023 (2)
N4	0.8285 (3)	0.9498 (12)	0.1537 (5)	0.024 (2)
O5	0.7792 (2)	0.8912 (10)	−0.0494 (4)	0.0279 (19)
O6	0.8425 (2)	0.8092 (10)	−0.0271 (4)	0.0287 (19)
O7	0.8764 (2)	0.9096 (11)	0.2951 (4)	0.030 (2)
O8	0.9339 (2)	0.8076 (10)	0.2994 (4)	0.0276 (19)
C11	1.0000	0.892 (2)	0.2500	0.0266 (8)
C12	1.0000	0.668 (2)	0.2500	0.0266 (8)
C13	0.9952 (4)	1.0891 (14)	0.4771 (6)	0.0266 (8)
O9	0.7736 (2)	0.7417 (11)	0.1827 (4)	0.036 (2)
H9A	0.7632	0.6856	0.2066	0.043*
H9B	0.7495	0.7646	0.1356	0.043*
O10	0.8408 (2)	1.2042 (10)	0.3435 (4)	0.036 (2)
H10A	0.8368	1.1601	0.3781	0.043*
H10B	0.8695	1.2480	0.3657	0.043*
O11	0.8260 (2)	1.3370 (11)	0.2208 (4)	0.042 (2)
H11A	0.8064	1.3776	0.1734	0.050*
H11B	0.8550	1.3304	0.2364	0.050*
O12	1.0016 (2)	0.9713 (10)	0.3011 (4)	0.0266 (8)
O13	1.0062 (2)	0.5922 (9)	0.3046 (4)	0.0266 (8)
O14	0.9925 (2)	1.0680 (9)	0.4205 (4)	0.0266 (8)
O15	1.0096 (2)	0.7572 (10)	0.4989 (4)	0.0266 (8)
O16	0.9640 (2)	0.4938 (10)	0.3838 (4)	0.0316 (19)
H16A	0.9809	0.4309	0.4287	0.038*
H16B	0.9581	0.4113	0.3462	0.038*
O17	1.0567 (2)	0.5282 (11)	0.4596 (4)	0.037 (2)
H17A	1.0714	0.5586	0.5088	0.044*
H17B	1.0772	0.5266	0.4488	0.044*
O18	1.0706 (2)	0.9117 (10)	0.4474 (4)	0.040 (2)
H18A	1.0898	0.9023	0.4982	0.048*
H18B	1.0864	0.8743	0.4294	0.048*
O19	0.9306 (3)	0.2694 (12)	0.2718 (4)	0.065 (3)
H19A	0.9123	0.3255	0.2257	0.077*
H19B	0.9512	0.2034	0.2693	0.077*
O20	0.8911 (3)	0.5464 (13)	0.3839 (6)	0.081 (4)
H20A	0.9024	0.6515	0.3743	0.097*
H20B	0.8668	0.5847	0.3828	0.097*
O21	1.0688 (2)	1.2537 (10)	0.3914 (4)	0.0312 (19)
H21A	1.0866	1.3021	0.3790	0.037*
H21B	1.0400	1.2320	0.3505	0.037*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0202 (7)	0.0318 (8)	0.0155 (7)	0.0033 (7)	0.0108 (6)	0.0003 (7)
Er1	0.0190 (3)	0.0342 (3)	0.0140 (3)	0.0012 (3)	0.0098 (2)	0.0018 (2)
Er2	0.0205 (3)	0.0224 (3)	0.0154 (3)	0.0021 (2)	0.0109 (2)	0.0003 (2)
C1	0.023 (6)	0.018 (6)	0.020 (7)	0.006 (5)	0.017 (6)	0.009 (5)
C2	0.018 (3)	0.038 (4)	0.015 (3)	0.000 (3)	0.010 (3)	−0.003 (3)
C3	0.016 (6)	0.028 (7)	0.025 (7)	0.009 (5)	0.013 (6)	0.002 (5)
C4	0.013 (6)	0.037 (7)	0.014 (6)	0.000 (5)	0.007 (5)	−0.005 (5)
C5	0.030 (7)	0.038 (8)	0.022 (7)	−0.001 (6)	0.020 (6)	0.003 (6)
N1	0.018 (3)	0.038 (4)	0.015 (3)	0.000 (3)	0.010 (3)	−0.003 (3)
N2	0.018 (3)	0.038 (4)	0.015 (3)	0.000 (3)	0.010 (3)	−0.003 (3)
O1	0.020 (4)	0.031 (5)	0.016 (4)	0.009 (3)	0.011 (4)	0.007 (3)
O2	0.023 (5)	0.050 (5)	0.020 (5)	0.015 (4)	0.010 (4)	0.008 (4)
O3	0.029 (5)	0.062 (6)	0.015 (4)	0.013 (4)	0.012 (4)	0.003 (4)
O4	0.024 (4)	0.052 (6)	0.013 (4)	0.014 (4)	0.010 (4)	0.002 (4)
C6	0.024 (5)	0.019 (4)	0.018 (5)	−0.001 (4)	0.010 (4)	0.003 (4)
C7	0.024 (5)	0.019 (4)	0.018 (5)	−0.001 (4)	0.010 (4)	0.003 (4)
C8	0.035 (8)	0.034 (8)	0.030 (8)	−0.005 (6)	0.020 (7)	0.000 (6)
C9	0.017 (6)	0.024 (7)	0.030 (7)	−0.008 (5)	0.015 (6)	0.002 (5)
C10	0.024 (7)	0.028 (7)	0.021 (7)	−0.009 (5)	0.014 (6)	−0.003 (5)
N3	0.019 (5)	0.035 (6)	0.015 (5)	0.006 (4)	0.010 (5)	0.005 (4)
N4	0.025 (5)	0.027 (6)	0.023 (6)	0.009 (4)	0.015 (5)	0.012 (4)
O5	0.020 (4)	0.049 (5)	0.012 (4)	0.001 (4)	0.008 (4)	−0.006 (4)
O6	0.024 (4)	0.042 (5)	0.023 (5)	−0.001 (4)	0.016 (4)	−0.009 (4)
O7	0.021 (4)	0.050 (6)	0.021 (5)	0.005 (4)	0.014 (4)	0.010 (4)
O8	0.020 (4)	0.031 (5)	0.030 (5)	0.007 (4)	0.013 (4)	0.004 (4)
C11	0.0407 (19)	0.022 (2)	0.023 (2)	0.000	0.0221 (18)	0.000
C12	0.0407 (19)	0.022 (2)	0.023 (2)	0.000	0.0221 (18)	0.000
C13	0.0407 (19)	0.022 (2)	0.023 (2)	0.000	0.0221 (18)	0.000
O9	0.042 (5)	0.048 (5)	0.022 (5)	−0.011 (4)	0.021 (4)	−0.004 (4)
O10	0.033 (5)	0.055 (6)	0.024 (5)	−0.014 (4)	0.019 (4)	−0.002 (4)
O11	0.046 (5)	0.056 (6)	0.025 (5)	−0.008 (4)	0.022 (5)	0.002 (4)
O12	0.0407 (19)	0.022 (2)	0.023 (2)	0.000	0.0221 (18)	0.000
O13	0.0407 (19)	0.022 (2)	0.023 (2)	0.000	0.0221 (18)	0.000
O14	0.0407 (19)	0.022 (2)	0.023 (2)	0.000	0.0221 (18)	0.000
O15	0.0407 (19)	0.022 (2)	0.023 (2)	0.000	0.0221 (18)	0.000
O16	0.036 (5)	0.032 (5)	0.018 (4)	0.000 (4)	0.010 (4)	0.011 (4)
O17	0.037 (5)	0.050 (6)	0.021 (5)	0.014 (4)	0.016 (4)	0.005 (4)
O18	0.022 (4)	0.050 (6)	0.040 (6)	0.004 (4)	0.013 (5)	−0.001 (4)
O19	0.070 (7)	0.061 (7)	0.027 (5)	0.022 (6)	0.008 (5)	−0.001 (5)
O20	0.065 (7)	0.068 (7)	0.140 (11)	0.021 (6)	0.077 (8)	0.041 (7)
O21	0.023 (4)	0.035 (5)	0.040 (5)	−0.006 (4)	0.022 (4)	−0.010 (4)

Geometric parameters (Å, º)

Cu1—N1	1.887 (8)	C6—C7	1.456 (14)
Cu1—N3	1.907 (8)	C7—N3	1.343 (12)
Cu1—O5	1.945 (7)	C7—C8	1.385 (14)
Cu1—O1	1.964 (6)	C8—C9	1.379 (14)
Cu1—Er1	4.5260 (18)	C8—H8	0.9297
Cu1—Er2	8.558 (2)	C9—N4	1.347 (12)
Er1—O9	2.295 (7)	C9—C10	1.470 (14)
Er1—O7	2.295 (7)	C10—O8	1.260 (11)
Er1—O3	2.310 (7)	C10—O7	1.262 (11)
Er1—O11	2.323 (7)	N3—N4	1.330 (11)
Er1—O4^i	2.338 (7)	C11—O12	1.254 (9)
Er1—O10	2.366 (7)	C11—O12^iii	1.254 (9)
Er1—N4	2.459 (8)	C11—C12	1.557 (19)
Er1—N2	2.492 (8)	C12—O13	1.240 (8)
Er1—Er2	6.3657 (16)	C12—O13^iii	1.240 (8)
Er2—O8	2.222 (7)	C13—O14	1.242 (11)
Er2—O18	2.308 (7)	C13—O15^iv	1.258 (11)
Er2—O13	2.325 (7)	C13—C13^iv	1.518 (19)
Er2—O14	2.336 (7)	O9—H9A	0.9219
Er2—O17	2.356 (7)	O9—H9B	0.9328
Er2—O16	2.360 (7)	O10—H10A	0.9333
Er2—O15	2.368 (6)	O10—H10B	0.9413
Er2—O12	2.438 (7)	O11—H11A	0.9281
C1—O2	1.221 (11)	O11—H11B	0.9366
C1—O1	1.285 (10)	O15—C13^iv	1.258 (11)
C1—C2	1.465 (14)	O16—H16A	0.9400
C2—N1	1.342 (12)	O16—H16B	0.9425
C2—C3	1.385 (12)	O17—H17A	0.9406
C3—C4	1.387 (13)	O17—H17B	0.9430
C3—H3	0.9301	O18—H18A	0.9427
C4—N2	1.328 (11)	O18—H18B	0.9363
C4—C5	1.514 (13)	O19—H19A	0.9419
C5—O4	1.240 (11)	O19—H19B	0.9322
C5—O3	1.261 (12)	O20—H20A	0.9349
N1—N2	1.337 (11)	O20—H20B	0.9414
O4—Er1^ii	2.338 (7)	O21—H21A	0.9319
C6—O6	1.227 (11)	O21—H21B	0.9458
C6—O5	1.299 (12)
N1—Cu1—N3	97.3 (4)	N1—C2—C1	114.9 (9)
N1—Cu1—O5	178.5 (3)	C3—C2—C1	135.8 (10)
N3—Cu1—O5	82.8 (3)	C2—C3—C4	102.1 (8)
N1—Cu1—O1	82.6 (3)	C2—C3—H3	129.0
N3—Cu1—O1	179.5 (3)	C4—C3—H3	129.0
O5—Cu1—O1	97.2 (3)	N2—C4—C3	113.0 (9)
N1—Cu1—Er1	49.1 (3)	N2—C4—C5	115.1 (9)
N3—Cu1—Er1	48.4 (2)	C3—C4—C5	131.8 (9)
O5—Cu1—Er1	130.9 (2)	O4—C5—O3	127.8 (10)
O1—Cu1—Er1	131.58 (19)	O4—C5—C4	118.7 (10)
O9—Er1—O7	95.0 (3)	O3—C5—C4	113.6 (10)
O9—Er1—O3	96.3 (3)	N2—N1—C2	110.3 (8)
O7—Er1—O3	151.3 (2)	N2—N1—Cu1	135.5 (7)
O9—Er1—O11	148.8 (3)	C2—N1—Cu1	114.2 (7)
O7—Er1—O11	94.8 (3)	C4—N2—N1	105.4 (8)
O3—Er1—O11	89.0 (3)	C4—N2—Er1	116.8 (7)
O9—Er1—O4^i	70.8 (2)	N1—N2—Er1	137.0 (6)
O7—Er1—O4^i	77.8 (2)	C1—O1—Cu1	114.6 (6)
O3—Er1—O4^i	81.1 (3)	C5—O3—Er1	127.0 (7)
O11—Er1—O4^i	140.3 (3)	C5—O4—Er1^ii	133.2 (7)
O9—Er1—O10	141.4 (2)	O6—C6—O5	122.4 (10)
O7—Er1—O10	79.9 (3)	O6—C6—C7	123.3 (10)
O3—Er1—O10	74.9 (2)	O5—C6—C7	114.3 (10)
O11—Er1—O10	69.6 (2)	N3—C7—C8	108.1 (10)
O4^i—Er1—O10	70.8 (2)	N3—C7—C6	114.3 (9)
O9—Er1—N4	75.3 (3)	C8—C7—C6	137.6 (11)
O7—Er1—N4	67.2 (3)	C9—C8—C7	104.3 (10)
O3—Er1—N4	141.4 (3)	C9—C8—H8	128.1
O11—Er1—N4	81.4 (3)	C7—C8—H8	127.6
O4^i—Er1—N4	128.1 (3)	N4—C9—C8	110.6 (10)
O10—Er1—N4	133.7 (3)	N4—C9—C10	116.3 (10)
O9—Er1—N2	75.5 (3)	C8—C9—C10	133.1 (10)
O7—Er1—N2	143.1 (3)	O8—C10—O7	124.8 (10)
O3—Er1—N2	65.5 (3)	O8—C10—C9	118.7 (10)
O11—Er1—N2	78.9 (3)	O7—C10—C9	116.6 (10)
O4^i—Er1—N2	128.9 (3)	N4—N3—C7	110.5 (8)
O10—Er1—N2	129.2 (3)	N4—N3—Cu1	135.5 (7)
N4—Er1—N2	75.9 (3)	C7—N3—Cu1	113.9 (7)
O9—Er1—Cu1	67.49 (17)	N3—N4—C9	106.4 (8)
O7—Er1—Cu1	105.10 (18)	N3—N4—Er1	138.0 (6)
O3—Er1—Cu1	103.59 (18)	C9—N4—Er1	115.4 (7)
O11—Er1—Cu1	81.36 (18)	C6—O5—Cu1	114.1 (7)
O4^i—Er1—Cu1	138.30 (18)	C10—O7—Er1	124.4 (7)
O10—Er1—Cu1	150.87 (17)	C10—O8—Er2	159.5 (7)
N4—Er1—Cu1	38.1 (2)	O12—C11—O12^iii	128.1 (14)
N2—Er1—Cu1	38.12 (19)	O12—C11—C12	115.9 (7)
O8—Er2—O18	141.8 (3)	O12^iii—C11—C12	115.9 (7)
O8—Er2—O13	84.5 (2)	O13—C12—O13^iii	129.7 (14)
O18—Er2—O13	97.9 (3)	O13—C12—C11	115.2 (7)
O8—Er2—O14	80.4 (2)	O13^iii—C12—C11	115.2 (7)
O18—Er2—O14	76.0 (2)	O14—C13—O15^iv	127.2 (9)
O13—Er2—O14	144.9 (2)	O14—C13—C13^iv	117.2 (12)
O8—Er2—O17	143.5 (3)	O15^iv—C13—C13^iv	115.6 (11)
O18—Er2—O17	72.6 (3)	Er1—O9—H9A	111.5
O13—Er2—O17	76.8 (2)	Er1—O9—H9B	108.5
O14—Er2—O17	130.9 (3)	H9A—O9—H9B	106.5
O8—Er2—O16	71.6 (2)	Er1—O10—H10A	117.9
O18—Er2—O16	146.6 (2)	Er1—O10—H10B	118.5
O13—Er2—O16	82.9 (2)	H10A—O10—H10B	110.7
O14—Er2—O16	121.1 (2)	Er1—O11—H11A	109.4
O17—Er2—O16	75.2 (2)	Er1—O11—H11B	106.7
O8—Er2—O15	108.1 (2)	H11A—O11—H11B	115.0
O18—Er2—O15	90.4 (3)	C11—O12—Er2	118.0 (8)
O13—Er2—O15	147.1 (2)	C12—O13—Er2	122.6 (8)
O14—Er2—O15	68.0 (2)	C13—O14—Er2	120.0 (6)
O17—Er2—O15	75.5 (2)	C13^iv—O15—Er2	119.1 (6)
O16—Er2—O15	73.1 (2)	Er2—O16—H16A	107.6
O8—Er2—O12	73.2 (2)	Er2—O16—H16B	109.9
O18—Er2—O12	72.9 (3)	H16A—O16—H16B	110.9
O13—Er2—O12	67.2 (2)	Er2—O17—H17A	109.4
O14—Er2—O12	78.2 (2)	Er2—O17—H17B	109.8
O17—Er2—O12	125.0 (2)	H17A—O17—H17B	107.9
O16—Er2—O12	135.3 (2)	Er2—O18—H18A	118.4
O15—Er2—O12	145.1 (2)	Er2—O18—H18B	113.3
O2—C1—O1	124.0 (10)	H18A—O18—H18B	106.7
O2—C1—C2	122.4 (9)	H19A—O19—H19B	103.7
O1—C1—C2	113.5 (9)	H20A—O20—H20B	110.2
N1—C2—C3	109.3 (9)	H21A—O21—H21B	112.3

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O9—H9A···O3^i	0.92	1.75	2.630 (9)	159
O9—H9B···O5^v	0.93	1.93	2.646 (10)	132
O10—H10A···O6^vi	0.93	2.05	2.910 (9)	152
O10—H10B···O20^vii	0.94	2.18	2.842 (11)	127
O11—H11A···O1^viii	0.93	1.90	2.683 (9)	141
O11—H11B···O19^vii	0.94	2.52	3.447 (11)	173
O16—H16A···O15^ix	0.94	1.97	2.839 (9)	154
O16—H16B···O19	0.94	1.70	2.604 (11)	161
O17—H17A···O20^ix	0.94	2.12	2.945 (12)	146
O19—H19A···O2^v	0.94	1.86	2.762 (11)	161
O19—H19B···O12^x	0.93	2.27	3.141 (11)	155
O20—H20A···O7	0.93	2.32	3.075 (11)	138
O20—H20B···O4^i	0.94	2.45	3.194 (11)	136
O21—H21A···O2^xi	0.93	1.78	2.687 (9)	165
O21—H21B···O12	0.95	2.18	2.906 (9)	133

Symmetry codes: (i) −x+3/2, y−1/2, −z+1/2; (v) −x+3/2, −y+3/2, −z; (vi) x, −y+2, z+1/2; (vii) x, y+1, z; (viii) −x+3/2, −y+5/2, −z; (ix) −x+2, −y+1, −z+1; (x) x, y−1, z; (xi) x+1/2, −y+5/2, z+1/2.