Tetra-μ-2,5-difluoro­benzoato-bis­[(2,2′-bipyridine)(2,5-difluoro­benzoato)gadolinium(III)]

Li, S.; Zhang, F.-L.; Tang, K.; Ma, Y.-F.

doi:10.1107/S1600536808023507

metal-organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 64| Part 9| September 2008| Page m1142

doi:10.1107/S1600536808023507

Open

access

RETRACTED ARTICLE

This article has been retracted. To view the retraction notice, click here.

Retracted: Tetra-μ-2,5-difluorobenzoato-bis[(2,2′-bipyridine)(2,5-difluorobenzoato)gadolinium(III)]

Sheng Li,^a Fu-Li Zhang,^b Kun Tang ^b and Yuan-Fang Ma ^a ^*

^aThe Institute of Immunology, Key Laboratory of Natural Drugs and Immunological Engineering of Henan Province, College of Medicine, Henan University, Kaifeng 475003, People's Republic of China, and ^bCollege of Medicine, Henan University, Kaifeng 475003, People's Republic of China
^*Correspondence e-mail: mayf_hd@126.com

(Received 28 April 2008; accepted 25 July 2008; online 9 August 2008)

In the centrosymmetric title compound, [Gd₂(C₇H₃F₂O₂)₆(C₁₀H₈N₂)₂], the asymmetric unit comprises one cation chelated by two 2,5-difluorobenzoate and one 2,2′-bipyridine. Two cations are linked into dimers via three bridging carboxylate groups from three 2,5-difluorobenzoic acid units. The Gd^III ion is nine-coordinated by seven O atoms and two N atoms.

Related literature

For related literature, see: Church & Halvorson (1959 ); Chung et al. (1971 ); Okabe & Oya (2000 ); Okabe et al. (2002 ); Serre et al. (2005 ); Pocker & Fong (1980 ); Scapin et al. (1997 ).

Experimental

Crystal data

[Gd₂(C₇H₃F₂O₂)₆(C₁₀H₈N₂)₂]
M_r = 1569.43
Triclinic, $[P \overline 1]$
a = 11.4012 (10) Å
b = 12.1890 (10) Å
c = 12.588 (2) Å
α = 103.99 (2)°
β = 102.90 (2)°
γ = 113.58 (2)°
V = 1451.6 (3) Å³
Z = 1
Mo Kα radiation
μ = 2.37 mm⁻¹
T = 293 (2) K
0.44 × 0.26 × 0.20 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ) T_min = 0.422, T_max = 0.648
8233 measured reflections
5557 independent reflections
4813 reflections with I > 2σ(I)
R_int = 0.021

Refinement

R[F² > 2σ(F²)] = 0.041
wR(F²) = 0.110
S = 1.00
5557 reflections
416 parameters
H-atom parameters constrained
Δρ_max = 2.22 e Å⁻³
Δρ_min = −0.62 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808023507/er2055sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808023507/er2055Isup2.hkl

checkCIF report

Comment top

In recent years, carboxylic acids have been widely used as polydentate ligands, which can coordinate to transition or rare earth ions yielding complexes with interesting properties that are useful in materials science (Church & Halvorson, 1959; Chung et al., 1971) and in biological systems (Okabe & Oya, 2000; Serre et al., 2005; Pocker & Fong, 1980; Scapin et al., 1997). Herein, we report the synthesis and X-ray crystal structure analysis of the title compound, hexa(2,5-difluorobenzoato) bis(2,2'-bipyridine) bisgadolinium(III).

The molecular structure of the title compound is shown in Fig.1, Gd^III is chelated by two 2,5-difluorobenzoate and one 2,2'-bipyridine. Two cations are linked into a dimer via bridging carboxylate groups from four 2,5-difluorobenzoate ions. The Gd^III ion is nine-coordinated with seven O atoms and two N atoms. The Gd—N and Gd—O bond lengths are in the range of 2.567 (4)–2.585 (5) Å and 2.364 (4)–2.495 (4) Å, respectively.

Related literature top

For related literature, see: Church & Halvorson (1959); Chung et al. (1971); Okabe & Oya (2000); Okabe et al. (2002); Serre et al. (2005); Pocker & Fong (1980); Scapin et al. (1997).

Experimental top

A mixture of gadolinium chloride (0.5 mmol), 2,5-difluorobenzoic acid (1 mmol), Sodium hydroxide(1 mmol), 2,2'-bipyridine(0.5 mmol), H₂O (8 ml) and Ethanol (8 ml) in a 25 ml Teflon-lined stainless steel autoclave was kept at 433 K for three days. Colorless crystals were obtained after cooling to room temperature.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); 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 top

Fig. 1. A view of the structure of (I), showing 30% probability displacement ellipsoids. Atoms labeled with i at the symmetry positions (-x + 1,-y + 2,-z + 1).

Tetra-µ-2,5-difluorobenzoato-bis[(2,2'-bipyridine)(2,5- difluorobenzoato)gadolinium(III)] top

Crystal data top

[Gd₂(C₇H₃F₂O₂)₆(C₁₀H₈N₂)₂]	Z = 1
M_r = 1569.43	F(000) = 766
Triclinic, P1	D_x = 1.795 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 11.4012 (10) Å	Cell parameters from 5557 reflections
b = 12.189 (1) Å	θ = 1.8–26.0°
c = 12.588 (2) Å	µ = 2.37 mm⁻¹
α = 103.99 (2)°	T = 293 K
β = 102.90 (2)°	Block, colorless
γ = 113.58 (2)°	0.44 × 0.26 × 0.20 mm
V = 1451.6 (3) Å³

Data collection top

Bruker APEXII CCD area-detector diffractometer	5557 independent reflections
Radiation source: fine-focus sealed tube	4813 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.021
ϕ and ω scans	θ_max = 26.0°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −10→14
T_min = 0.422, T_max = 0.649	k = −15→12
8233 measured reflections	l = −15→14

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.110	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.071P)² + 0.5036P] where P = (F_o² + 2F_c²)/3
5557 reflections	(Δ/σ)_max = 0.030
416 parameters	Δρ_max = 2.22 e Å⁻³
0 restraints	Δρ_min = −0.62 e Å⁻³

Crystal data top

[Gd₂(C₇H₃F₂O₂)₆(C₁₀H₈N₂)₂]	γ = 113.58 (2)°
M_r = 1569.43	V = 1451.6 (3) Å³
Triclinic, P1	Z = 1
a = 11.4012 (10) Å	Mo Kα radiation
b = 12.189 (1) Å	µ = 2.37 mm⁻¹
c = 12.588 (2) Å	T = 293 K
α = 103.99 (2)°	0.44 × 0.26 × 0.20 mm
β = 102.90 (2)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	5557 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2001)	4813 reflections with I > 2σ(I)
T_min = 0.422, T_max = 0.649	R_int = 0.021
8233 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.041	0 restraints
wR(F²) = 0.110	H-atom parameters constrained
S = 1.00	Δρ_max = 2.22 e Å⁻³
5557 reflections	Δρ_min = −0.62 e Å⁻³
416 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
Gd1	0.39616 (2)	0.80450 (2)	0.43978 (2)	0.03327 (12)
C1	0.5204 (7)	0.6201 (6)	0.2986 (6)	0.0566 (16)
H1	0.5606	0.6949	0.2835	0.068*
C2	0.5504 (8)	0.5214 (7)	0.2568 (7)	0.071 (2)
H2	0.6112	0.5310	0.2168	0.086*
C3	0.4902 (9)	0.4138 (7)	0.2755 (7)	0.074 (2)
H3	0.5067	0.3456	0.2468	0.089*
C4	0.4041 (8)	0.4025 (6)	0.3367 (6)	0.067 (2)
H4	0.3630	0.3274	0.3511	0.080*
C5	0.3784 (6)	0.5033 (5)	0.3773 (5)	0.0470 (15)
C6	0.6740 (5)	0.9487 (5)	0.6191 (5)	0.0369 (11)
C7	0.8263 (6)	1.0068 (5)	0.6801 (5)	0.0424 (13)
C8	0.9145 (7)	1.0683 (6)	0.6300 (7)	0.0626 (18)
H8	0.8813	1.0778	0.5601	0.075*
C9	1.0543 (8)	1.1162 (7)	0.6852 (9)	0.079 (2)
C10	1.1059 (8)	1.1078 (8)	0.7849 (9)	0.088 (3)
H10	1.2004	1.1430	0.8197	0.105*
C11	1.0194 (8)	1.0459 (9)	0.8400 (8)	0.084 (3)
H11	1.0547	1.0395	0.9110	0.100*
C12	0.8802 (6)	0.9953 (7)	0.7841 (6)	0.0538 (15)
C13	0.1577 (6)	0.6867 (5)	0.2396 (5)	0.0403 (12)
C14	0.0390 (6)	0.6516 (5)	0.1350 (5)	0.0457 (13)
C15	−0.0965 (7)	0.5954 (7)	0.1250 (6)	0.0602 (17)
C16	−0.2024 (7)	0.5661 (9)	0.0290 (7)	0.079 (2)
H16	−0.2919	0.5269	0.0273	0.094*
C17	−0.1783 (8)	0.5937 (8)	−0.0639 (7)	0.077 (2)
H17	−0.2498	0.5751	−0.1299	0.092*
C18	−0.0444 (9)	0.6503 (8)	−0.0579 (6)	0.074 (2)
C19	0.0612 (7)	0.6787 (6)	0.0364 (6)	0.0595 (17)
H19	0.1501	0.7167	0.0365	0.071*
C20	0.6082 (5)	0.9901 (5)	0.3314 (5)	0.0379 (11)
C21	0.6108 (6)	0.9679 (5)	0.2087 (5)	0.0440 (13)
C22	0.7087 (7)	1.0531 (6)	0.1808 (6)	0.0552 (16)
C23	0.7022 (9)	1.0268 (7)	0.0655 (7)	0.068 (2)
H23	0.7709	1.0843	0.0480	0.082*
C24	0.5951 (9)	0.9165 (8)	−0.0237 (7)	0.0695 (19)
H24	0.5889	0.9002	−0.1014	0.083*
C25	0.5001 (8)	0.8335 (7)	0.0047 (6)	0.0660 (18)
C26	0.5039 (6)	0.8539 (6)	0.1199 (6)	0.0528 (15)
H26	0.4374	0.7935	0.1369	0.063*
C27	0.2142 (7)	0.6084 (7)	0.5643 (7)	0.0621 (18)
H27	0.2169	0.6855	0.6019	0.075*
C28	0.1338 (8)	0.5019 (8)	0.5805 (8)	0.078 (2)
H28	0.0841	0.5069	0.6292	0.094*
C29	0.1264 (9)	0.3904 (8)	0.5264 (9)	0.091 (3)
H29	0.0694	0.3160	0.5350	0.109*
C30	0.2040 (9)	0.3852 (7)	0.4569 (8)	0.084 (3)
H30	0.2005	0.3077	0.4192	0.101*
C31	0.2871 (6)	0.4973 (5)	0.4440 (5)	0.0527 (16)
F1	0.8152 (5)	1.1601 (4)	0.2644 (4)	0.0831 (13)
F2	0.3947 (6)	0.7242 (5)	−0.0810 (4)	0.1036 (18)
F3	0.7955 (5)	0.9343 (6)	0.8322 (4)	0.0982 (17)
F4	1.1395 (6)	1.1740 (7)	0.6349 (8)	0.139 (3)
F5	−0.1314 (7)	0.5674 (10)	0.2087 (7)	0.179 (4)
F6	−0.0098 (10)	0.6785 (11)	−0.1474 (8)	0.217 (5)
N1	0.2898 (5)	0.6091 (4)	0.4975 (5)	0.0485 (12)
N2	0.4380 (5)	0.6129 (4)	0.3585 (4)	0.0456 (11)
O1	0.1425 (4)	0.6937 (4)	0.3365 (3)	0.0488 (10)
O2	0.2724 (4)	0.7142 (4)	0.2302 (4)	0.0522 (10)
O3	0.6255 (4)	1.0193 (3)	0.5933 (3)	0.0384 (8)
O4	0.5990 (4)	0.8317 (3)	0.5899 (4)	0.0526 (11)
O5	0.5617 (4)	0.8922 (3)	0.3554 (3)	0.0421 (8)
O6	0.3488 (4)	0.8965 (3)	0.6021 (4)	0.0478 (9)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Gd1	0.03152 (16)	0.02485 (15)	0.04068 (18)	0.01156 (11)	0.00743 (11)	0.01632 (11)
C1	0.053 (4)	0.044 (3)	0.067 (4)	0.025 (3)	0.016 (3)	0.014 (3)
C2	0.080 (5)	0.068 (5)	0.063 (4)	0.051 (4)	0.012 (4)	0.006 (4)
C3	0.099 (6)	0.047 (4)	0.060 (4)	0.049 (4)	−0.006 (4)	0.000 (3)
C4	0.084 (5)	0.035 (3)	0.056 (4)	0.030 (3)	−0.009 (4)	0.006 (3)
C5	0.054 (3)	0.029 (3)	0.041 (3)	0.020 (2)	−0.010 (3)	0.009 (2)
C6	0.034 (3)	0.034 (3)	0.039 (3)	0.015 (2)	0.005 (2)	0.017 (2)
C7	0.038 (3)	0.036 (3)	0.052 (3)	0.023 (2)	0.007 (2)	0.013 (2)
C8	0.051 (4)	0.059 (4)	0.089 (5)	0.027 (3)	0.026 (4)	0.044 (4)
C9	0.050 (4)	0.068 (5)	0.130 (8)	0.026 (4)	0.037 (5)	0.054 (5)
C10	0.042 (4)	0.079 (5)	0.133 (8)	0.031 (4)	0.009 (5)	0.042 (5)
C11	0.050 (4)	0.103 (6)	0.088 (6)	0.040 (4)	−0.001 (4)	0.038 (5)
C12	0.044 (3)	0.070 (4)	0.049 (3)	0.032 (3)	0.008 (3)	0.024 (3)
C13	0.041 (3)	0.026 (2)	0.043 (3)	0.013 (2)	0.005 (2)	0.011 (2)
C14	0.048 (3)	0.043 (3)	0.037 (3)	0.019 (3)	0.005 (2)	0.017 (2)
C15	0.042 (3)	0.084 (5)	0.042 (3)	0.020 (3)	0.012 (3)	0.026 (3)
C16	0.035 (3)	0.109 (7)	0.066 (5)	0.025 (4)	−0.001 (3)	0.026 (4)
C17	0.064 (5)	0.079 (5)	0.056 (4)	0.030 (4)	−0.017 (4)	0.019 (4)
C18	0.083 (6)	0.080 (5)	0.046 (4)	0.029 (4)	0.011 (4)	0.031 (4)
C19	0.056 (4)	0.058 (4)	0.051 (4)	0.012 (3)	0.015 (3)	0.030 (3)
C20	0.035 (3)	0.035 (3)	0.048 (3)	0.018 (2)	0.017 (2)	0.020 (2)
C21	0.049 (3)	0.046 (3)	0.054 (3)	0.031 (3)	0.025 (3)	0.026 (3)
C22	0.066 (4)	0.045 (3)	0.069 (4)	0.027 (3)	0.040 (3)	0.029 (3)
C23	0.099 (6)	0.073 (5)	0.085 (5)	0.059 (5)	0.066 (5)	0.052 (4)
C24	0.092 (6)	0.079 (5)	0.057 (4)	0.051 (5)	0.038 (4)	0.027 (4)
C25	0.078 (5)	0.065 (4)	0.046 (4)	0.032 (4)	0.023 (3)	0.010 (3)
C26	0.050 (3)	0.056 (4)	0.060 (4)	0.023 (3)	0.031 (3)	0.027 (3)
C27	0.053 (4)	0.061 (4)	0.089 (5)	0.028 (3)	0.030 (4)	0.050 (4)
C28	0.065 (5)	0.075 (5)	0.107 (6)	0.025 (4)	0.032 (4)	0.068 (5)
C29	0.085 (6)	0.058 (5)	0.107 (7)	0.006 (4)	0.019 (5)	0.060 (5)
C30	0.092 (6)	0.037 (4)	0.083 (6)	0.007 (4)	−0.004 (5)	0.033 (4)
C31	0.056 (4)	0.028 (3)	0.052 (3)	0.011 (2)	−0.007 (3)	0.021 (2)
F1	0.078 (3)	0.061 (2)	0.087 (3)	0.004 (2)	0.048 (2)	0.025 (2)
F2	0.111 (4)	0.098 (4)	0.057 (3)	0.024 (3)	0.033 (3)	0.000 (3)
F3	0.070 (3)	0.169 (5)	0.069 (3)	0.055 (3)	0.025 (2)	0.071 (3)
F4	0.072 (3)	0.148 (5)	0.253 (8)	0.052 (3)	0.089 (4)	0.135 (6)
F5	0.092 (5)	0.272 (10)	0.123 (6)	0.029 (5)	0.033 (4)	0.099 (6)
F6	0.151 (7)	0.295 (12)	0.128 (7)	0.030 (7)	0.016 (5)	0.120 (8)
N1	0.038 (3)	0.038 (2)	0.065 (3)	0.013 (2)	0.009 (2)	0.031 (2)
N2	0.043 (3)	0.033 (2)	0.055 (3)	0.018 (2)	0.005 (2)	0.018 (2)
O1	0.042 (2)	0.055 (2)	0.044 (2)	0.0152 (18)	0.0094 (17)	0.0274 (19)
O2	0.040 (2)	0.058 (3)	0.047 (2)	0.0221 (19)	0.0079 (18)	0.013 (2)
O3	0.0357 (18)	0.0307 (17)	0.048 (2)	0.0166 (15)	0.0074 (16)	0.0200 (16)
O4	0.044 (2)	0.0254 (18)	0.068 (3)	0.0106 (16)	−0.0058 (19)	0.0200 (18)
O5	0.041 (2)	0.0355 (19)	0.053 (2)	0.0166 (16)	0.0211 (17)	0.0215 (17)
O6	0.057 (2)	0.034 (2)	0.052 (2)	0.0167 (18)	0.0257 (19)	0.0200 (18)

Geometric parameters (Å, º) top

Gd1—O6	2.364 (4)	C13—C14	1.489 (8)
Gd1—O3ⁱ	2.378 (3)	C14—C15	1.377 (9)
Gd1—O5	2.380 (4)	C14—C19	1.409 (8)
Gd1—O2	2.419 (4)	C15—F5	1.279 (9)
Gd1—O4	2.482 (4)	C15—C16	1.357 (9)
Gd1—O1	2.495 (4)	C16—C17	1.347 (12)
Gd1—N1	2.567 (4)	C16—H16	0.9300
Gd1—N2	2.585 (5)	C17—C18	1.375 (12)
Gd1—O3	2.692 (4)	C17—H17	0.9300
Gd1—C13	2.806 (5)	C18—C19	1.345 (10)
Gd1—C6	2.942 (5)	C18—F6	1.350 (11)
Gd1—Gd1ⁱ	4.0615 (12)	C19—H19	0.9300
C1—N2	1.319 (8)	C20—O5	1.239 (6)
C1—C2	1.395 (9)	C20—O6ⁱ	1.253 (6)
C1—H1	0.9300	C20—C21	1.511 (8)
C2—C3	1.322 (12)	C21—C22	1.369 (8)
C2—H2	0.9300	C21—C26	1.397 (9)
C3—C4	1.363 (12)	C22—F1	1.335 (8)
C3—H3	0.9300	C22—C23	1.386 (10)
C4—C5	1.382 (9)	C23—C24	1.380 (11)
C4—H4	0.9300	C23—H23	0.9300
C5—N2	1.342 (7)	C24—C25	1.339 (10)
C5—C31	1.467 (10)	C24—H24	0.9300
C6—O4	1.237 (6)	C25—F2	1.352 (8)
C6—O3	1.261 (6)	C25—C26	1.399 (9)
C6—C7	1.505 (7)	C26—H26	0.9300
C7—C8	1.371 (9)	C27—N1	1.330 (9)
C7—C12	1.383 (9)	C27—C28	1.352 (9)
C8—C9	1.389 (10)	C27—H27	0.9300
C8—H8	0.9300	C28—C29	1.324 (13)
C9—C10	1.309 (13)	C28—H28	0.9300
C9—F4	1.335 (9)	C29—C30	1.384 (14)
C10—C11	1.409 (13)	C29—H29	0.9300
C10—H10	0.9300	C30—C31	1.389 (9)
C11—C12	1.380 (9)	C30—H30	0.9300
C11—H11	0.9300	C31—N1	1.352 (8)
C12—F3	1.325 (8)	O3—Gd1ⁱ	2.378 (3)
C13—O1	1.258 (7)	O6—C20ⁱ	1.253 (6)
C13—O2	1.254 (7)

O6—Gd1—O3ⁱ	75.83 (13)	C9—C8—C7	118.9 (7)
O6—Gd1—O5	132.95 (13)	C9—C8—H8	120.5
O3ⁱ—Gd1—O5	74.27 (13)	C7—C8—H8	120.5
O6—Gd1—O2	132.75 (15)	C10—C9—F4	118.7 (8)
O3ⁱ—Gd1—O2	78.28 (14)	C10—C9—C8	122.7 (8)
O5—Gd1—O2	74.17 (14)	F4—C9—C8	118.6 (8)
O6—Gd1—O4	84.95 (15)	C9—C10—C11	120.5 (7)
O3ⁱ—Gd1—O4	123.14 (12)	C9—C10—H10	119.8
O5—Gd1—O4	81.99 (14)	C11—C10—H10	119.8
O2—Gd1—O4	142.06 (15)	C12—C11—C10	117.1 (8)
O6—Gd1—O1	84.39 (15)	C12—C11—H11	121.4
O3ⁱ—Gd1—O1	81.23 (13)	C10—C11—H11	121.4
O5—Gd1—O1	125.10 (13)	F3—C12—C7	119.0 (5)
O2—Gd1—O1	52.89 (14)	F3—C12—C11	118.8 (6)
O4—Gd1—O1	149.72 (13)	C7—C12—C11	122.2 (7)
O6—Gd1—N1	79.37 (15)	O1—C13—O2	121.3 (5)
O3ⁱ—Gd1—N1	144.99 (15)	O1—C13—C14	119.4 (5)
O5—Gd1—N1	140.06 (15)	O2—C13—C14	119.2 (5)
O2—Gd1—N1	101.82 (16)	O1—C13—Gd1	62.8 (3)
O4—Gd1—N1	78.17 (14)	O2—C13—Gd1	59.3 (3)
O1—Gd1—N1	72.04 (14)	C14—C13—Gd1	168.3 (4)
O6—Gd1—N2	138.74 (15)	C15—C14—C19	114.5 (6)
O3ⁱ—Gd1—N2	145.41 (15)	C15—C14—C13	125.5 (6)
O5—Gd1—N2	78.19 (14)	C19—C14—C13	120.0 (6)
O2—Gd1—N2	74.34 (15)	F5—C15—C16	114.6 (7)
O4—Gd1—N2	72.15 (14)	F5—C15—C14	121.2 (6)
O1—Gd1—N2	98.28 (15)	C16—C15—C14	124.2 (7)
N1—Gd1—N2	62.87 (17)	C17—C16—C15	120.1 (7)
O6—Gd1—O3	70.83 (13)	C17—C16—H16	119.9
O3ⁱ—Gd1—O3	73.72 (12)	C15—C16—H16	119.9
O5—Gd1—O3	66.40 (12)	C16—C17—C18	117.8 (6)
O2—Gd1—O3	136.31 (13)	C16—C17—H17	121.1
O4—Gd1—O3	49.42 (11)	C18—C17—H17	121.1
O1—Gd1—O3	148.18 (13)	C19—C18—F6	115.1 (8)
N1—Gd1—O3	120.33 (13)	C19—C18—C17	122.5 (7)
N2—Gd1—O3	113.49 (13)	F6—C18—C17	122.4 (8)
O6—Gd1—C13	108.05 (16)	C18—C19—C14	120.8 (7)
O3ⁱ—Gd1—C13	76.10 (14)	C18—C19—H19	119.6
O5—Gd1—C13	98.99 (15)	C14—C19—H19	119.6
O2—Gd1—C13	26.47 (16)	O5—C20—O6ⁱ	126.5 (5)
O4—Gd1—C13	159.67 (14)	O5—C20—C21	115.8 (5)
O1—Gd1—C13	26.63 (15)	O6ⁱ—C20—C21	117.8 (5)
N1—Gd1—C13	88.73 (16)	C22—C21—C26	119.4 (6)
N2—Gd1—C13	88.09 (15)	C22—C21—C20	124.0 (5)
O3—Gd1—C13	149.07 (13)	C26—C21—C20	116.6 (5)
O6—Gd1—C6	80.23 (15)	F1—C22—C23	118.8 (6)
O3ⁱ—Gd1—C6	98.81 (13)	F1—C22—C21	120.7 (6)
O5—Gd1—C6	69.55 (14)	C23—C22—C21	120.4 (7)
O2—Gd1—C6	142.89 (15)	C24—C23—C22	120.9 (7)
O4—Gd1—C6	24.53 (12)	C24—C23—H23	119.6
O1—Gd1—C6	164.08 (15)	C22—C23—H23	119.6
N1—Gd1—C6	100.90 (14)	C25—C24—C23	118.1 (7)
N2—Gd1—C6	90.66 (15)	C25—C24—H24	120.9
O3—Gd1—C6	25.36 (12)	C23—C24—H24	120.9
C13—Gd1—C6	168.47 (16)	F2—C25—C24	119.3 (6)
O6—Gd1—Gd1ⁱ	68.84 (9)	F2—C25—C26	117.5 (7)
O3ⁱ—Gd1—Gd1ⁱ	39.52 (8)	C24—C25—C26	123.2 (7)
O5—Gd1—Gd1ⁱ	64.90 (9)	C25—C26—C21	117.9 (6)
O2—Gd1—Gd1ⁱ	111.12 (11)	C25—C26—H26	121.0
O4—Gd1—Gd1ⁱ	83.62 (8)	C21—C26—H26	121.0
O1—Gd1—Gd1ⁱ	118.30 (10)	N1—C27—C28	123.7 (8)
N1—Gd1—Gd1ⁱ	144.52 (12)	N1—C27—H27	118.1
N2—Gd1—Gd1ⁱ	138.26 (11)	C28—C27—H27	118.1
O3—Gd1—Gd1ⁱ	34.20 (7)	C29—C28—C27	119.4 (9)
C13—Gd1—Gd1ⁱ	115.34 (11)	C29—C28—H28	120.3
C6—Gd1—Gd1ⁱ	59.38 (10)	C27—C28—H28	120.3
N2—C1—C2	123.4 (7)	C28—C29—C30	119.6 (7)
N2—C1—H1	118.3	C28—C29—H29	120.2
C2—C1—H1	118.3	C30—C29—H29	120.2
C3—C2—C1	118.2 (8)	C29—C30—C31	119.2 (8)
C3—C2—H2	120.9	C29—C30—H30	120.4
C1—C2—H2	120.9	C31—C30—H30	120.4
C2—C3—C4	120.1 (7)	N1—C31—C30	120.0 (8)
C2—C3—H3	119.9	N1—C31—C5	116.6 (5)
C4—C3—H3	119.9	C30—C31—C5	123.4 (7)
C3—C4—C5	119.6 (7)	C27—N1—C31	118.1 (5)
C3—C4—H4	120.2	C27—N1—Gd1	120.0 (4)
C5—C4—H4	120.2	C31—N1—Gd1	120.8 (4)
N2—C5—C4	121.1 (7)	C1—N2—C5	117.6 (5)
N2—C5—C31	116.7 (5)	C1—N2—Gd1	121.2 (4)
C4—C5—C31	122.2 (6)	C5—N2—Gd1	121.2 (4)
O4—C6—O3	120.8 (5)	C13—O1—Gd1	90.6 (3)
O4—C6—C7	119.9 (4)	C13—O2—Gd1	94.2 (3)
O3—C6—C7	119.2 (4)	C6—O3—Gd1ⁱ	163.0 (3)
O4—C6—Gd1	56.4 (3)	C6—O3—Gd1	88.5 (3)
O3—C6—Gd1	66.2 (3)	Gd1ⁱ—O3—Gd1	106.28 (12)
C7—C6—Gd1	162.8 (4)	C6—O4—Gd1	99.0 (3)
C8—C7—C12	118.6 (6)	C20—O5—Gd1	135.6 (3)
C8—C7—C6	119.9 (5)	C20ⁱ—O6—Gd1	133.6 (3)
C12—C7—C6	121.4 (5)

O6—Gd1—O1—C13	153.0 (3)	O5—Gd1—C6—O4	−117.5 (4)
O3ⁱ—Gd1—O1—C13	76.5 (3)	O2—Gd1—C6—O4	−104.8 (4)
O5—Gd1—O1—C13	12.9 (4)	O1—Gd1—C6—O4	84.1 (6)
O2—Gd1—O1—C13	−5.4 (3)	N1—Gd1—C6—O4	22.1 (4)
O4—Gd1—O1—C13	−137.2 (4)	N2—Gd1—C6—O4	−40.3 (4)
N1—Gd1—O1—C13	−126.4 (4)	O3—Gd1—C6—O4	164.6 (6)
N2—Gd1—O1—C13	−68.5 (3)	C13—Gd1—C6—O4	−123.9 (7)
O3—Gd1—O1—C13	114.6 (3)	Gd1ⁱ—Gd1—C6—O4	170.3 (4)
C6—Gd1—O1—C13	167.9 (4)	O6—Gd1—C6—O3	−65.4 (3)
Gd1ⁱ—Gd1—O1—C13	90.7 (3)	O3ⁱ—Gd1—C6—O3	8.5 (4)
O6—Gd1—O2—C13	−24.6 (4)	O5—Gd1—C6—O3	77.9 (3)
O3ⁱ—Gd1—O2—C13	−82.4 (3)	O2—Gd1—C6—O3	90.6 (4)
O5—Gd1—O2—C13	−159.2 (4)	O4—Gd1—C6—O3	−164.6 (6)
O4—Gd1—O2—C13	147.7 (3)	O1—Gd1—C6—O3	−80.5 (6)
O1—Gd1—O2—C13	5.4 (3)	N1—Gd1—C6—O3	−142.5 (3)
N1—Gd1—O2—C13	61.8 (4)	N2—Gd1—C6—O3	155.1 (3)
N2—Gd1—O2—C13	118.9 (4)	C13—Gd1—C6—O3	71.5 (8)
O3—Gd1—O2—C13	−133.2 (3)	Gd1ⁱ—Gd1—C6—O3	5.7 (3)
C6—Gd1—O2—C13	−171.5 (3)	O6—Gd1—C6—C7	−177.5 (12)
Gd1ⁱ—Gd1—O2—C13	−104.8 (3)	O3ⁱ—Gd1—C6—C7	−103.6 (12)
O6—Gd1—O3—C6	108.4 (3)	O5—Gd1—C6—C7	−34.2 (12)
O3ⁱ—Gd1—O3—C6	−171.3 (4)	O2—Gd1—C6—C7	−21.5 (13)
O5—Gd1—O3—C6	−91.7 (3)	O4—Gd1—C6—C7	83.3 (12)
O2—Gd1—O3—C6	−119.1 (3)	O1—Gd1—C6—C7	167.4 (10)
O4—Gd1—O3—C6	8.3 (3)	N1—Gd1—C6—C7	105.4 (12)
O1—Gd1—O3—C6	149.2 (3)	N2—Gd1—C6—C7	43.0 (12)
N1—Gd1—O3—C6	43.8 (4)	O3—Gd1—C6—C7	−112.1 (13)
N2—Gd1—O3—C6	−27.4 (3)	C13—Gd1—C6—C7	−40.6 (16)
C13—Gd1—O3—C6	−158.3 (4)	Gd1ⁱ—Gd1—C6—C7	−106.4 (12)
Gd1ⁱ—Gd1—O3—C6	−171.3 (4)	O4—C6—C7—C8	120.0 (7)
O6—Gd1—O3—Gd1ⁱ	−80.30 (16)	O3—C6—C7—C8	−56.7 (8)
O3ⁱ—Gd1—O3—Gd1ⁱ	0.0	Gd1—C6—C7—C8	47.2 (14)
O5—Gd1—O3—Gd1ⁱ	79.60 (15)	O4—C6—C7—C12	−57.5 (8)
O2—Gd1—O3—Gd1ⁱ	52.2 (2)	O3—C6—C7—C12	125.8 (6)
O4—Gd1—O3—Gd1ⁱ	179.6 (2)	Gd1—C6—C7—C12	−130.3 (11)
O1—Gd1—O3—Gd1ⁱ	−39.5 (3)	C12—C7—C8—C9	0.6 (10)
N1—Gd1—O3—Gd1ⁱ	−144.87 (17)	C6—C7—C8—C9	−177.0 (6)
N2—Gd1—O3—Gd1ⁱ	143.94 (16)	C7—C8—C9—C10	−2.1 (13)
C13—Gd1—O3—Gd1ⁱ	13.0 (4)	C7—C8—C9—F4	178.9 (7)
C6—Gd1—O3—Gd1ⁱ	171.3 (4)	F4—C9—C10—C11	−179.4 (8)
O6—Gd1—O4—C6	−77.6 (4)	C8—C9—C10—C11	1.6 (15)
O3ⁱ—Gd1—O4—C6	−8.2 (4)	C9—C10—C11—C12	0.3 (14)
O5—Gd1—O4—C6	57.1 (4)	C10—C11—C12—F3	178.5 (8)
O2—Gd1—O4—C6	108.1 (4)	C10—C11—C12—C7	−1.8 (13)
O1—Gd1—O4—C6	−147.3 (4)	C8—C7—C12—F3	−178.9 (6)
N1—Gd1—O4—C6	−157.8 (4)	C6—C7—C12—F3	−1.4 (10)
N2—Gd1—O4—C6	137.2 (4)	C8—C7—C12—C11	1.4 (11)
O3—Gd1—O4—C6	−8.6 (3)	C6—C7—C12—C11	178.9 (7)
C13—Gd1—O4—C6	151.4 (5)	Gd1—O2—C13—O1	−10.1 (6)
Gd1ⁱ—Gd1—O4—C6	−8.4 (4)	Gd1—O2—C13—C14	166.6 (4)
O6—Gd1—O5—C20	−43.1 (6)	Gd1—O1—C13—O2	9.7 (5)
O3ⁱ—Gd1—O5—C20	9.3 (5)	Gd1—O1—C13—C14	−166.9 (4)
O2—Gd1—O5—C20	91.3 (5)	O6—Gd1—C13—O2	161.3 (3)
O4—Gd1—O5—C20	−118.5 (5)	O3ⁱ—Gd1—C13—O2	91.5 (3)
O1—Gd1—O5—C20	76.2 (5)	O5—Gd1—C13—O2	20.3 (3)
N1—Gd1—O5—C20	−179.1 (5)	O4—Gd1—C13—O2	−71.0 (6)
N2—Gd1—O5—C20	168.1 (5)	O1—Gd1—C13—O2	−170.3 (5)
O3—Gd1—O5—C20	−69.5 (5)	N1—Gd1—C13—O2	−120.3 (3)
C13—Gd1—O5—C20	82.0 (5)	N2—Gd1—C13—O2	−57.5 (3)
C6—Gd1—O5—C20	−96.7 (5)	O3—Gd1—C13—O2	78.6 (4)
Gd1ⁱ—Gd1—O5—C20	−31.8 (5)	C6—Gd1—C13—O2	26.3 (9)
O3ⁱ—Gd1—O6—C20ⁱ	−43.7 (5)	Gd1ⁱ—Gd1—C13—O2	86.7 (3)
O5—Gd1—O6—C20ⁱ	8.2 (6)	O6—Gd1—C13—O1	−28.4 (3)
O2—Gd1—O6—C20ⁱ	−102.4 (5)	O3ⁱ—Gd1—C13—O1	−98.2 (3)
O4—Gd1—O6—C20ⁱ	82.3 (5)	O5—Gd1—C13—O1	−169.4 (3)
O1—Gd1—O6—C20ⁱ	−126.0 (5)	O2—Gd1—C13—O1	170.3 (5)
N1—Gd1—O6—C20ⁱ	161.2 (5)	O4—Gd1—C13—O1	99.4 (6)
N2—Gd1—O6—C20ⁱ	137.8 (5)	N1—Gd1—C13—O1	50.0 (3)
O3—Gd1—O6—C20ⁱ	33.7 (5)	N2—Gd1—C13—O1	112.8 (3)
C13—Gd1—O6—C20ⁱ	−113.7 (5)	O3—Gd1—C13—O1	−111.0 (4)
C6—Gd1—O6—C20ⁱ	58.1 (5)	C6—Gd1—C13—O1	−163.3 (6)
Gd1ⁱ—Gd1—O6—C20ⁱ	−2.8 (5)	Gd1ⁱ—Gd1—C13—O1	−103.0 (3)
O6—Gd1—N1—C27	18.7 (5)	O6—Gd1—C13—C14	75 (2)
O3ⁱ—Gd1—N1—C27	−26.7 (6)	O3ⁱ—Gd1—C13—C14	6 (2)
O5—Gd1—N1—C27	167.5 (5)	O5—Gd1—C13—C14	−66 (2)
O2—Gd1—N1—C27	−113.1 (5)	O2—Gd1—C13—C14	−86 (2)
O4—Gd1—N1—C27	105.7 (5)	O4—Gd1—C13—C14	−157 (2)
O1—Gd1—N1—C27	−68.8 (5)	O1—Gd1—C13—C14	104 (2)
N2—Gd1—N1—C27	−178.5 (5)	N1—Gd1—C13—C14	154 (2)
O3—Gd1—N1—C27	78.9 (5)	N2—Gd1—C13—C14	−143 (2)
C13—Gd1—N1—C27	−90.0 (5)	O3—Gd1—C13—C14	−7 (2)
C6—Gd1—N1—C27	96.5 (5)	C6—Gd1—C13—C14	−60 (3)
Gd1ⁱ—Gd1—N1—C27	45.0 (6)	Gd1ⁱ—Gd1—C13—C14	1 (2)
O6—Gd1—N1—C31	−174.0 (4)	O2—C13—C14—C15	166.7 (7)
O3ⁱ—Gd1—N1—C31	140.6 (4)	O1—C13—C14—C15	−16.6 (9)
O5—Gd1—N1—C31	−25.2 (5)	Gd1—C13—C14—C15	−114 (2)
O2—Gd1—N1—C31	54.2 (4)	O2—C13—C14—C19	−15.2 (8)
O4—Gd1—N1—C31	−87.0 (4)	O1—C13—C14—C19	161.6 (6)
O1—Gd1—N1—C31	98.5 (4)	Gd1—C13—C14—C19	64 (2)
N2—Gd1—N1—C31	−11.1 (4)	C19—C14—C15—F5	−178.7 (9)
O3—Gd1—N1—C31	−113.8 (4)	C13—C14—C15—F5	−0.4 (13)
C13—Gd1—N1—C31	77.4 (4)	C19—C14—C15—C16	0.9 (12)
C6—Gd1—N1—C31	−96.2 (4)	C13—C14—C15—C16	179.1 (8)
Gd1ⁱ—Gd1—N1—C31	−147.7 (3)	F5—C15—C16—C17	178.4 (10)
O6—Gd1—N2—C1	−148.1 (4)	C14—C15—C16—C17	−1.2 (15)
O3ⁱ—Gd1—N2—C1	34.4 (6)	C15—C16—C17—C18	0.8 (14)
O5—Gd1—N2—C1	−3.3 (4)	C16—C17—C18—C19	−0.3 (14)
O2—Gd1—N2—C1	73.4 (5)	C16—C17—C18—F6	178.4 (10)
O4—Gd1—N2—C1	−88.6 (5)	F6—C18—C19—C14	−178.7 (9)
O1—Gd1—N2—C1	121.0 (5)	C17—C18—C19—C14	0.1 (13)
N1—Gd1—N2—C1	−174.1 (5)	C15—C14—C19—C18	−0.3 (11)
O3—Gd1—N2—C1	−60.8 (5)	C13—C14—C19—C18	−178.7 (7)
C13—Gd1—N2—C1	96.3 (5)	Gd1—O5—C20—O6ⁱ	48.8 (8)
C6—Gd1—N2—C1	−72.2 (5)	Gd1—O5—C20—C21	−130.3 (5)
Gd1ⁱ—Gd1—N2—C1	−31.0 (5)	O5—C20—C21—C22	−147.5 (6)
O6—Gd1—N2—C5	30.7 (5)	O6ⁱ—C20—C21—C22	33.3 (8)
O3ⁱ—Gd1—N2—C5	−146.7 (4)	O5—C20—C21—C26	34.0 (7)
O5—Gd1—N2—C5	175.5 (4)	O6ⁱ—C20—C21—C26	−145.3 (5)
O2—Gd1—N2—C5	−107.8 (4)	C26—C21—C22—F1	−177.0 (6)
O4—Gd1—N2—C5	90.3 (4)	C20—C21—C22—F1	4.5 (9)
O1—Gd1—N2—C5	−60.1 (4)	C26—C21—C22—C23	−0.4 (10)
N1—Gd1—N2—C5	4.7 (4)	C20—C21—C22—C23	−178.9 (6)
O3—Gd1—N2—C5	118.0 (4)	F1—C22—C23—C24	179.0 (7)
C13—Gd1—N2—C5	−84.8 (4)	C21—C22—C23—C24	2.3 (11)
C6—Gd1—N2—C5	106.7 (4)	C22—C23—C24—C25	−2.3 (11)
Gd1ⁱ—Gd1—N2—C5	147.8 (3)	C23—C24—C25—F2	−179.5 (7)
C5—N2—C1—C2	−1.8 (9)	C23—C24—C25—C26	0.3 (12)
Gd1—N2—C1—C2	177.1 (5)	C22—C21—C26—C25	−1.5 (9)
N2—C1—C2—C3	2.5 (11)	C20—C21—C26—C25	177.1 (6)
C1—C2—C3—C4	−2.2 (11)	C24—C25—C26—C21	1.6 (11)
C2—C3—C4—C5	1.4 (11)	F2—C25—C26—C21	−178.6 (6)
C1—N2—C5—C4	0.9 (8)	C31—N1—C27—C28	−0.6 (10)
Gd1—N2—C5—C4	−178.0 (4)	Gd1—N1—C27—C28	167.0 (6)
C1—N2—C5—C31	−179.9 (5)	N1—C27—C28—C29	−1.3 (13)
Gd1—N2—C5—C31	1.2 (6)	C27—C28—C29—C30	2.2 (13)
C3—C4—C5—N2	−0.7 (9)	C28—C29—C30—C31	−1.2 (13)
C3—C4—C5—C31	−179.9 (6)	C27—N1—C31—C30	1.5 (9)
Gd1—O4—C6—O3	16.4 (6)	Gd1—N1—C31—C30	−166.0 (5)
Gd1—O4—C6—C7	−160.3 (5)	C27—N1—C31—C5	−176.1 (6)
Gd1ⁱ—O3—C6—O4	−165.2 (9)	Gd1—N1—C31—C5	16.4 (6)
Gd1—O3—C6—O4	−14.9 (6)	C29—C30—C31—N1	−0.6 (11)
Gd1ⁱ—O3—C6—C7	11.4 (16)	C29—C30—C31—C5	176.8 (7)
Gd1—O3—C6—C7	161.8 (5)	N2—C5—C31—N1	−11.4 (7)
Gd1ⁱ—O3—C6—Gd1	−150.3 (12)	C4—C5—C31—N1	167.8 (5)
O6—Gd1—C6—O4	99.2 (4)	N2—C5—C31—C30	171.1 (6)
O3ⁱ—Gd1—C6—O4	173.1 (4)	C4—C5—C31—C30	−9.7 (9)

Symmetry code: (i) −x+1, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	[Gd₂(C₇H₃F₂O₂)₆(C₁₀H₈N₂)₂]
M_r	1569.43
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	11.4012 (10), 12.189 (1), 12.588 (2)
α, β, γ (°)	103.99 (2), 102.90 (2), 113.58 (2)
V (Å³)	1451.6 (3)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	2.37
Crystal size (mm)	0.44 × 0.26 × 0.20

Data collection
Diffractometer	Bruker APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2001)
T_min, T_max	0.422, 0.649
No. of measured, independent and observed [I > 2σ(I)] reflections	8233, 5557, 4813
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.041, 0.110, 1.00
No. of reflections	5557
No. of parameters	416
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	2.22, −0.62

Computer programs: APEX2 (Bruker, 2004), SAINT-Plus (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Acknowledgements

The authors are grateful for financial support from Henan University (grant No. 05YBGG013)

References

Bruker (2001). SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Chung, L., Rajan, K. S., Merdinger, E. & Crecz, N. (1971). Biophys. J. 11, 469–475. CrossRef CAS Web of Science PubMed Google Scholar
Church, B. S. & Halvorson, H. (1959). Nature (London), 183, 124–125. CrossRef PubMed CAS Web of Science Google Scholar
Okabe, N., Kyoyama, H. & Fujimoto, A. (2002). Acta Cryst. E58, m354–m356. Web of Science CSD CrossRef IUCr Journals Google Scholar
Okabe, N. & Oya, N. (2000). Acta Cryst. C56, 1416–1417. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Pocker, Y. & Fong, C. T. O. (1980). Biochemistry, 19, 2045–2049. CrossRef CAS PubMed Web of Science Google Scholar
Scapin, G., Reddy, S. G., Zheng, R. & Blanchard, J. S. (1997). Biochemistry, 36, 15081–15088. CrossRef CAS PubMed Web of Science Google Scholar
Serre, C., Marrot, J. & Ferey, G. (2005). Inorg. Chem. 44, 654–658. Web of Science CSD CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals 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.