Poly[[hexa­aqua­tris­[μ2-2,5-dihy­droxy-1,4-benzoquinona­to(2−)]diholmium(III)] octa­deca­hydrate]

Koji Nakabayashi; Shin-ichi Ohkoshi

doi:10.1107/S1600536810028989

. 2010 Sep 25;66(Pt 10):m1300. doi: 10.1107/S1600536810028989

Poly[[hexaaquatris[μ₂-2,5-dihydroxy-1,4-benzoquinonato(2−)]diholmium(III)] octadecahydrate]

Koji Nakabayashi ^a, Shin-ichi Ohkoshi ^a,^*

PMCID: PMC2983139 PMID: 21587439

Abstract

In the polymeric title compound, {[Ho₂(C₆H₂O₄)₃(H₂O)₆]·18H₂O}_n, the Ho^III ion is nine-coordinated by six O atoms derived from three bidentate 2,5-dihydroxy-1,4-benzoquinonate (DHBQ²⁻) ligands and three O atoms from three water molecules. The Ho^III ions are connected via three ligands, resulting in the formation of a two-dimensional honeycomb layer parallel to the ab plane. The layer is racemic in which Δ- and Λ-coordination geometries around Ho^III ions are alternately arranged. The asymmetric unit comprises a third of a Ho^III ion, located on a threefold axis, one-half of a DHBQ²⁻ ion, located on a centre of inversion, one coordinated water molecule and three uncoordinated water molecules.

Related literature

For general background, see: Kitagawa & Kawata (2002 ▶); Nakabayashi & Ohkoshi (2009 ▶); Ohkoshi et al. (2001 ▶). For details of the synthesis, see: Weider et al. (1985 ▶). For related structures, see: Robl & Sheldrick (1988 ▶); Weiss et al. (1986 ▶).

Experimental

Crystal data

[Ho₂(C₆H₂O₄)₃(H₂O)₆]·18H₂O
M _r = 1176.46
Trigonal,
a = 14.1407 (3) Å
c = 18.0629 (5) Å
V = 3127.93 (12) Å³
Z = 3
Mo Kα radiation
μ = 3.88 mm⁻¹
T = 90 K
0.10 × 0.10 × 0.04 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.704, T _max = 0.856
11262 measured reflections
1594 independent reflections
1525 reflections with I > 2σ(I)
R _int = 0.025

Refinement

R[F ² > 2σ(F ²)] = 0.023
wR(F ²) = 0.063
S = 1.23
1594 reflections
86 parameters
H-atom parameters constrained
Δρ_max = 0.65 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku, 1998 ▶); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku, 2007 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and pyMOL (DeLano, 2007 ▶); software used to prepare material for publication: CrystalStructure.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810028989/tk2691sup1.cif

e-66-m1300-sup1.cif^{(20.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810028989/tk2691Isup2.hkl

e-66-m1300-Isup2.hkl^{(78.9KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Ho1—O1	2.371 (2)
Ho1—O2	2.463 (2)
Ho1—O3	2.385 (3)

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Acknowledgments

We are thankful for a Grant-in-Aid for Young Scientists (S) from JSPS, the Global COE Program, "Chemistry Innovation through Cooperation of Science and Engineering" from MEXT Japan, the Photon Frontier Network Program from MEXT, the Izumi Science and Technology Foundation and Asahi Glass Foundation. We also thank the Cryogenic Research Center and the Center for Nano Lithography & Analysis, The University of Tokyo, supported by MEXT Japan. This work has been approved by the Photon Factory Program Advisory Committee (Proposal 2009 G678).

supplementary crystallographic information

Comment

Lanthanide complexes have attracted attention as magnetic and luminescent materials due to the properties of the 4f orbitals in lanthanide ions. Although the magnetism of mononuclear lanthanide complexes are well understood, studies on polynuclear lanthanide complexes are much less advanced (Ohkoshi et al., 2001). The dimensionality of complexes and coordination geometry around lanthanide ions are key factors to control their magnetic properties. From this viewpoint, constructing polynuclear lanthanide complexes with various topologies are interesting. In our previous work, we reported the 3-D monometallic lanthanide metal assembly, Na₅[{Ho(THB^4-)₂}.7H₂O]_n (THB = 1,2,4,5-tetrahydroxybenzene) (Nakabayashi et al., 2009). In this work, we synthesized a 2-D honeycomb network composed of holmium ions (Ho^III) and 2,5-dihydroxy-1,4-benzoquinonate, [{Ho₂ (DHBQ^2-)₃ (H₂O)₆}.18H₂O]_n (Kitagawa et al., 2002; Robl et al., 1988).

The asymmetric unit comprises a third of a Ho^III ion, being located on a three-fold axis, one-half of a DHBQ^2- ion, being disposed about a centre of inversion, one coordinated water molecule, and three zeolitic water molecules.

The C—O distances of 1.276 (4) Å (C1—O1) and 1.274 (3) Å (C2—O2) in this compound agree with those of the DHBQ^2- ligands which were previously reported, e.g. 1.276 (6) Å (Weiss et al. 1986). In the coordination geometry, a Ho^III ion is coordinated to six O atoms from three bidentate DHBQ^2- ligands and three O atoms from three water molecules (Fig. 1 and Table 1). The Ho^III ion is connected via three ligands, which results in a two-dimensional honeycomb layer with a diameter of 16.6 Å. The layer has a racemic structure in which Δ- and Λ-coordination geometries around Ho^III ions are alternately arranged (Fig. 2). The zeolitic water molecules occupy regions between the layers.

The product of the molar magnetic susceptibility (χ_M) and temperature (T), χ_MT, values at room temperature was 13.6 cm³ K mol^-1. This value nearly corresponds to the expected value of 13.9 cm³ K mol^-1 due to Ho^III ions (J = 8, L = 6, S = 2, and g = 5/4).

All known compounds of this type have two specific structures, honeycomb or racemic, and show paramagnetism. Mixing lanthanide ions, the chiral lanthanide assemblies with Δ- or Λ-coordination geometries are targeted for synthesis, which should show a magneto-chiral dichroism. A study to clarify this hypotheses, work is currently under way.

Experimental

Under air, aqueous solutions of 0.1 M Ho(NO₃)₃ and 0.4 M 1,2,4,5-tetrahydroxybenzene (THB) (Weider et al., 1985) mixed. THB was gradually oxidized to 2,5-dihydroxy-1,4-benzoquinone (DHBQ) in the mixed solution, and slow complexation of Ho(NO₃)₃ and DHBQ) produced red crystals of the title polymer in 24% yield within a week. The obtained polycrystalline compound was dried under air. Elemental analysis indicated the formula was [Ho₂(C₆H₂O₄)₃(H₂O)₆].17H₂O, C₁₈H₅₂O₃₅Ho₂, calcd. Ho, 28.18%; C, 18.47%; H, 4.49%, found. Ho, 28.29%; C, 18.23%; H, 4.64%. There is a slight difference of zeolitic water molecules between the elemental analysis and the crystallographic formulation because zeolitic water molecules are easy to be lost from the crystals and their number depends on the drying processes.