Tetra-μ-benzoato-κ4 O:O′;κ3 O:O,O′;κ3 O,O′:O′-bis­[(benzoato-κ2 O,O′)(1,10-phenanthroline-κ2 N,N′)europium(III)] benzoic acid disolvate

Ping Howe Ooi; Siang Guan Teoh; Chin Sing Yeap; Hoong-Kun Fun

doi:10.1107/S1600536810015229

. 2010 Apr 30;66(Pt 5):m597–m598. doi: 10.1107/S1600536810015229

Tetra-μ-benzoato-κ⁴ O:O′;κ³ O:O,O′;κ³ O,O′:O′-bis[(benzoato-κ² O,O′)(1,10-phenanthroline-κ² N,N′)europium(III)] benzoic acid disolvate

Ping Howe Ooi ^a,^‡, Siang Guan Teoh ^a, Chin Sing Yeap ^b,^§, Hoong-Kun Fun ^b,^*,^¶

PMCID: PMC2979066 PMID: 21579069

Abstract

The asymmetric unit of the title complex, [Eu₂(C₇H₅O₂)₆(C₁₂H₈N₂)₂]·2C₆H₅COOH, contains one-half of the complex molecule, the complete molecule being generated by inversion symmetry, and one benzoic acid solvent molecule. The two Eu^III ions are linked by four bridging benzoate ions, with an Eu⋯Eu distance of 3.96041 (12) Å. Each Eu^III ion is coordinated by one phenanthroline heterocycle and a bidentate benzoate ion. The irregular nine-coordinated geometry of the metal ion is composed of seven O and two N atoms. The molecular structure is stabilized by intramolecular C—H⋯O hydrogen bonds. In the crystal structure, molecules are linked into chains by intermolecular C—H⋯O hydrogen bonds along the a axis. The crystal structure is further stabilized by intermolecular C—H⋯O and C—H⋯π interactions. Weak π–π interactions are also observed [centroid–centroid distances = 3.6962 (10)–3.6963 (10) Å].

Related literature

For general background to and applications of europium(III) complexes, see: Yam & Lo (1999 ▶); Beeby et al. (2003 ▶); Tang et al. (2008 ▶); Faulkner et al. (2005 ▶). For related Ln–benzoato complexes (Ln = lanthanide), see: Niu et al. (1999 ▶, 2002 ▶); Shi et al. (2001 ▶); Ooi et al. (2010 ▶).

Experimental

Crystal data

[Eu₂(C₇H₅O₂)₆(C₁₂H₈N₂)₂]·2C₇H₆O₂
M _r = 1635.22
Triclinic,
a = 9.6688 (2) Å
b = 12.8260 (2) Å
c = 15.1460 (3) Å
α = 75.244 (1)°
β = 78.605 (1)°
γ = 76.072 (1)°
V = 1744.26 (6) Å³
Z = 1
Mo Kα radiation
μ = 1.86 mm⁻¹
T = 296 K
0.58 × 0.32 × 0.28 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.413, T _max = 0.628
51513 measured reflections
12557 independent reflections
11674 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.020
wR(F ²) = 0.050
S = 1.04
12557 reflections
464 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.62 e Å⁻³
Δρ_min = −0.44 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810015229/rz2435sup1.cif

e-66-0m597-sup1.cif^{(39KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810015229/rz2435Isup2.hkl

e-66-0m597-Isup2.hkl^{(613.9KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Eu1—O5	2.3667 (9)
Eu1—O3ⁱ	2.3669 (9)
Eu1—O6ⁱ	2.3818 (10)
Eu1—O4	2.4571 (11)
Eu1—O2	2.4933 (11)
Eu1—O1	2.4974 (11)
Eu1—N1	2.5636 (11)
Eu1—N2	2.6134 (11)
Eu1—O3	2.6394 (11)

Open in a new tab

Symmetry code: (i) Inline graphic .

Table 2. Hydrogen-bond geometry (Å, °).

Cg1 is the centroid of the C35–C40 benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O8—H1O8⋯O1	0.86 (3)	1.82 (3)	2.660 (2)	166 (3)
C2—H2A⋯O6ⁱ	0.93	2.43	3.017 (2)	121
C9—H9A⋯O2ⁱⁱ	0.93	2.51	3.258 (2)	138
C11—H11A⋯O5	0.93	2.44	3.079 (2)	126
C25—H25A⋯Cg1ⁱⁱⁱ	0.93	2.65	3.551 (3)	164

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

SGT and PHO thank Universiti Sains Malaysia (USM) for the University Grant (No. 1001/229/PKIMIA/815002) for this research. HKF and CSY thank USM for the Research University Golden Goose grant (No. 1001/PFIZIK/811012). CSY also thanks USM for the award of a USM fellowship.

supplementary crystallographic information

Comment

Lanthanide complexes were widely used in biomedical field (Yam & Lo, 1999), sensing areas (Beeby et al., 2003) and optical imaging (Faulkner et al., 2005) because they exhibit intense luminescence, especially europium (III) and terbium (III) ions. In order to create high luminescence complexes, ligands which chelate to the lanthanide atoms should be able to protect lanthanide ions from solvent molecules and absorb energy to transfer it efficiently to the center metal atom (Tang et al., 2008). The title compound, (I) was synthesized and its structure was determined. Similar crystal structures with different lanthanides have been reported in the past, such as lanthanum(III) (Shi et al., 2001), samarium(III) (Niu et al., 1999), gadolinium(III) (Niu et al., 2002) and neodymium(III) (Ooi et al., 2010).

The asymmetric unit of the title complex (I) (Fig. 1) consists of one-half of the complex molecule and one benzoic acid. The complex molecule lies on a crystallographic inversion center. The two europium(III) ions are linked by four benzoate ions, with an Eu—Eu distance of 3.96041 (12) Å. Among the four benzoate ions, two of them also behave as chelating ligands to the europium(III) ions. Each metal ion is coordinated by one phenanthroline heterocycle and a bidentate benzoate ion. The irregular nine-coordinated geometry of the europium(III) ion is completed by seven benzoate O atoms and two phenanthroline N atoms. Bond lengths of Eu—O and Eu—N are listed in Table 1. All other bond lengths and angles are comparable to a closely La-benzoato complex (Shi et al., 2001).

In the crystal structure, intermolecular C9—H9A···O2 hydrogen bonds (Table 2) link the molecules into chains along the a axis (Fig. 2). The crystal structure is further stabilized by intermolecular O8—H1O8···O1 and C25A—H25A···Cg1 interactions (Table 2). Intramolecular C2—H2A···O6 and C11—H11A···O5 hydrogen bonds (Table 2) stabilize the molecular structure. Weak π–π interactions of Cg2···Cg3 = 3.6963 (10) Å and Cg3···Cg3 = 3.6962 (10) Å [Cg2 and Cg3 are centroids of benzene rings C1/N1/C2–C5 and C1/C5–C8/C12; symmetry code: 1-x, 1-y, 1-z] are observed.

Experimental

0.5 mmol of EuCl₃.6H₂O was dissolved in methanol and then was added into a solution (methanol-H₂O, 1.5:1) of 1,10-phenanthroline (0.5 mmol) and benzoic acid (1.5 mmol). The mixture was sealed in a tube, and heated directly to 403 K. After keeping at 403 K for 2 days, it was cooled to room temperature. Colourless block crystals (I) were obtained by filtration, and was washed with water and ethanol.