Poly[hexa­aqua­bis(μ3-naphthalene-2,6-dicarboxyl­ato)(μ2-naphthalene-2,6-dicarboxyl­ato)diholmium(III)]

Almeida Paz, F.A.; Klinowski, J.

doi:10.1107/S1600536807064483

metal-organic compounds

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ISSN: 2056-9890

Volume 64| Part 1| January 2008| Pages m140-m141

https://doi.org/10.1107/S1600536807064483

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Poly[hexaaquabis(μ₃-naphthalene-2,6-dicarboxylato)(μ₂-naphthalene-2,6-dicarboxylato)diholmium(III)]

Filipe A. Almeida Paz ^a ^* and Jacek Klinowski ^b

^aDepartment of Chemistry, University of Aveiro, CICECO, 3810-193 Aveiro, Portugal, and ^bDepartment of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, England
^*Correspondence e-mail: filipe.paz@ua.pt

(Received 23 November 2007; accepted 29 November 2007; online 12 December 2007)

The crystal structure of the title compound, [Ho₂(C₁₂H₆O₄)₃(H₂O)₆]_n, contains binuclear centrosymmetric {Ho₂O₂(CO₂)₄(H₂O)₆} cores interconnected via the naphthalene-2,6-dicarboxylate (NDC²⁻) bridging ligands into a two-dimensional neutral plane net, ∞²[Ho₂(NDC)₃(H₂O)₆], exhibiting a typical (4,4)-topology. Interactions between adjacent layers are assured by a series of C—H⋯π contacts and a number of strong and highly directional O—H⋯O hydrogen bonds involving the coordinated water molecules and neighbouring coordinated carboxylate groups. One NDC²⁻ bridging ligand has its centroid located at a crystallographic centre of inversion.

Related literature

For related structures see: Zheng, Sun et al. (2004 ); Zheng, Wang et al. (2004 ); Paz & Klinowski (2003 ); Min & Lee (2002 ); Wang et al. (2002 ). For related literature, see: Cunha-Silva, Mafra et al. (2007 ); Cunha-Silva, Shi et al. (2007 ); Shi et al. (2007 ); Mafra et al. (2006 ); Shi et al. (2006 ); Paz, Rocha, Klinowski et al. (2005 ); Almeida Paz, Shi, Mafra et al. (2005 ); Almeida Paz, Shi, Trindade et al. (2005 ); Shi et al. (2005 ); Paz & Klinowski (2004 ); Almeida Paz et al. (2002a ,b ,c ); Allen (2002 ); Allen & Motherwell (2002 ); Altomare et al. (1994 ); Deluzet et al. (2003 ).

Experimental

Crystal data

[Ho₂(C₁₂H₆O₄)₃(H₂O)₆]
M_r = 540.23
Triclinic, $[P \overline 1]$
a = 7.8856 (3) Å
b = 9.6537 (5) Å
c = 12.5438 (6) Å
α = 75.191 (2)°
β = 74.224 (2)°
γ = 75.352 (2)°
V = 870.98 (7) Å³
Z = 2
Mo Kα radiation
μ = 4.60 mm⁻¹
T = 180 (2) K
0.10 × 0.05 × 0.05 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SORTAV; Blessing, 1995 ) T_min = 0.730, T_max = 0.796
11608 measured reflections
3987 independent reflections
3135 reflections with I > 2σ(I)
R_int = 0.067

Refinement

R[F² > 2σ(F²)] = 0.043
wR(F²) = 0.079
S = 1.00
3987 reflections
271 parameters
9 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.51 e Å⁻³
Δρ_min = −1.50 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

Ho1—O1	2.267 (4)
Ho1—O3ⁱ	2.252 (3)
Ho1—O4ⁱⁱ	2.279 (4)
Ho1—O5	2.389 (3)
Ho1—O6	2.450 (4)
Ho1—O1W	2.370 (4)
Ho1—O2W	2.461 (4)
Ho1—O3W	2.366 (4)

O1—Ho1—O4ⁱⁱ	144.69 (15)
O1—Ho1—O5	98.23 (13)
O1—Ho1—O6	77.54 (13)
O1—Ho1—O1W	72.71 (14)
O1—Ho1—O2W	142.57 (14)
O1—Ho1—O3W	76.58 (14)
O3ⁱ—Ho1—O1	101.02 (13)
O3ⁱ—Ho1—O4ⁱⁱ	96.82 (14)
O3ⁱ—Ho1—O5	147.95 (14)
O3ⁱ—Ho1—O6	155.80 (14)
O3ⁱ—Ho1—O1W	83.38 (14)
O3ⁱ—Ho1—O2W	72.20 (13)
O3ⁱ—Ho1—O3W	76.60 (14)
O4ⁱⁱ—Ho1—O5	81.43 (13)
O4ⁱⁱ—Ho1—O6	73.82 (13)
O4ⁱⁱ—Ho1—O1W	140.01 (13)
O4ⁱⁱ—Ho1—O2W	72.11 (13)
O4ⁱⁱ—Ho1—O3W	78.31 (14)
O5—Ho1—O6	54.22 (13)
O5—Ho1—O2W	76.91 (13)
O6—Ho1—O2W	123.35 (12)
O1W—Ho1—O5	78.18 (13)
O1W—Ho1—O6	118.31 (14)
O1W—Ho1—O2W	69.97 (13)
O3W—Ho1—O5	133.18 (14)
O3W—Ho1—O6	79.62 (14)
O3W—Ho1—O2W	133.39 (14)
O3W—Ho1—O1W	139.08 (13)
Symmetry codes: (i) -x+2, -y, -z+1; (ii) x+1, y, z-1.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1A⋯O2ⁱⁱⁱ	0.95 (4)	1.82 (2)	2.725 (5)	157 (5)
O1W—H1B⋯O5ⁱⁱⁱ	0.95 (4)	1.95 (3)	2.818 (5)	150 (4)
O2W—H2A⋯O2^iv	0.95 (4)	1.98 (4)	2.782 (5)	140 (5)
O2W—H2B⋯O2ⁱⁱⁱ	0.95 (4)	2.14 (4)	2.901 (6)	136 (4)
O3W—H3A⋯O6^v	0.95 (4)	1.78 (4)	2.704 (5)	165 (5)
O3W—H3B⋯O2W^vi	0.95 (4)	2.26 (4)	3.181 (6)	165 (4)
O3W—H3B⋯O4ⁱ	0.95 (4)	2.53 (5)	3.145 (6)	123 (4)
Symmetry codes: (i) -x+2, -y, -z+1; (iii) -x+2, -y+1, -z; (iv) x+1, y, z; (v) -x+2, -y, -z; (vi) -x+3, -y, -z.

Data collection: COLLECT (Nonius, 1998 ); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXTL (Bruker, 2001 ); molecular graphics: DIAMOND (Brandenburg, 2006 ); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536807064483/hj2008sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807064483/hj2008Isup2.hkl

checkCIF report

Comment top

In less than twenty years, the field of Crystal Engineering involving the synthesis and characterization of multi-dimensional metal-organic frameworks (also known as coordination polymers) has grown immensely to become one of the most active research areas in inorganic chemistry. These worldwide efforts are motivated by the new and often striking structural features obtained by varying the metal centres and the bridging organic ligands, and by the prospect of making materials with direct industrial applications. Following our efforts in the hydrothermal synthesis and structural characterization of highly crystalline materials of this kind, (Cunha-Silva, Mafra et al., 2007; Cunha-Silva, Shi et al., 2007; Shi et al., 2007; Mafra et al., 2006; Shi et al., 2006; Paz, Rocha, Klinowski et al., 2005; Almeida Paz, Shi, Mafra et al., 2005; Almeida Paz, Shi, Trindade et al., 2005; Shi et al., 2005; Paz & Klinowski, 2004; Paz & Klinowski, 2003; Almeida Paz et al. 2002a, 2002b, 2002c), we report here the low temperature crystal structure at 180 (2) K of a two-dimensional lanthanide-organic framework containing residues of naphthalene-2,6-dicarboxylic acid (H₂NDC), [Ho₂(NDC)₃(H₂O)₆], which is analogous to that reported by Deluzet et al. (2003) but containing instead Er³⁺, [Er₂(NDC)₃(H₂O)₆]. A search in the literature and in the Cambridge Structural Database (CSD, Version 5.28 with three updates - August 2007; Allen, 2002; Allen & Motherwell, 2002) produced only a handful of reports in which lanthanide centres are coordinated to H_{2 -}_xNDC^-^x residues (Zheng, Sun et al., 2004; Zheng, Wang et al., 2004; Paz & Klinowski, 2003; Wang et al., 2002; Min & Lee, 2002).

The structure of the title compound, I, contains a single crystallographically independent metallic centre, Ho1, coordinated to three water molecules (O1W, O2W and O3W) and four NDC^2-bridging ligands (Figure 1a), with a {HoO₈} coordination geometry resembling a highly distorted dodecahedron (Figure 1 b). The Ho—O bond lengths were found in the 2.252 (3)–2.461 (4) Å range,in good agreement with those of related materials as revealed by a search in the CSD. The three crystallographically independent carboxylate groups coordinate to the Ho³⁺ centres in distinct coordination fashions as shown in Figure 1a. Notably, the C8 carboxylate group is coordinated via a typical syn,syn-µ₂-bridging coordination fashion leading to the formation of binuclear centrosymmetric anionic [Ho₂(NDC)₆(H₂O)₆]^6- unit (Figure 1) with the Ho(1)···Ho(1)^vi intermetallic distance being of 5.0172 (4) Å [symmetry code: (vi) 3 - x, -y, -z]. While the C1 carboxylate group is coordinated via a syn-unidentate coordination fashion, the C13 carboxylate is instead bound to Ho1 via a typical syn,syn-chelate bidentate mode with a bite angle of 54.22 (13)°.

{Ho₂O₂(CO₂)₄(H₂O)₆} cores are interconnected via the bridging NDC^2-ligands into an inclined two-dimensional plane net (Figure 2). By taking the centre of gravity of each binuclear centrosymmetric anionic [Ho₂(NDC)₆(H₂O)₆]^6- unit as a node of the network, the resulting ∞²[Ho₂(NDC)₃(H₂O)₆] plane net has a typical (4,4) topology with the inter-nodal distances being of 12.8742 (6) Å and 16.3127 (6) Å. As shown in Figures 3a and 3 b, individual ∞²[Ho₂(NDC)₃(H₂O)₆] plane nets close pack in a parallel fashion (not along a principal axis of the unit cell) to produce the crystal structure. Along the [010] crystallographic direction the packing occurs in an orderly ABAB··· fashion (Figure 3 b). Connections between adjacent layers are mainly assured by strong and highly directional O—H···.O hydrogen bonds involving the O2W and O3W coordinated water molecules from one layer and the coordinated carboxylate groups from the neighbouring layer (Figure 4 and Table in the main paper summarizing the geometrical parameters of the hydrogen bonding interactions). Moreover, these connections are reinforced by weak C—H···π interactions between coordinated NDC^2- residues belonging to adjacent layers (not shown). It is important to stress that, within each ∞²[Ho₂(NDC)₃(H₂O)₆] layer, O1W is also engaged in strong O—H···.O hydrogen bonds which reinforce the connections between neighbouring binuclear units (Figure 4).

Related literature top

For related structures see: Zheng, Sun et al. (2004); Zheng, Wang et al. (2004); Paz & Klinowski (2003); Min & Lee (2002); Wang et al. (2002). For related literature, see: Cunha-Silva, Mafra et al. (2007); Cunha-Silva, Shi et al. (2007); Shi et al. (2007); Mafra et al. (2006); Shi et al. (2006); Paz, Rocha, Klinowski et al. (2005); Almeida Paz, Shi, Mafra et al. (2005); Almeida Paz, Shi, Trindade et al. (2005); Shi et al. (2005); Paz & Klinowski (2004); Almeida Paz et al. (2002a, 2002b, 2002c).

For related literature, see: Allen (2002); Allen & Motherwell (2002); Altomare et al. (1994); Deluzet et al. (2003).

Experimental top

Starting materials were purchased from commercial sources and were used as received without further purification: holmium(III) chloride hexahydrate (HoCl₃.6H₂O, 99.9%, Aldrich), naphthalene-2,6-dicarboxylic acid (H₂NDC, 99%, Aldrich) and triethylamine (TEA, 99%, Avocado).

To a solution of HoCl₃.6H₂O (1.054 g, 2.778 mmol) in distilled water (6.88 g), naphthalene-2,6-dicarboxylic acid (0.100 g, 0.463 mmol) and triethylamine (0.097 g, 0.959 mmol) were added and the mixture was stirred thoroughly for 5 minutes at ambient temperature. The suspension, with a molar composition of 6.01 Ho³⁺: 1.00 H₂NDC: 2.07 TEA: 137 H₂O, was transferred to a Parr teflon-lined stainless steel vessel (ca 21 cm³) and placed for 8 h at 145 °C in a preheated oven. Before opening, the reaction vessel was allowed to cool slowly to ambient temperature at a rate of 10 ° per hour over a period of 14 h. The isolated crystalline material was mainly composed of crystals of the title compound which were preserved in a portion of the mother liquor before being manually selected under a polarized microscope for subsequent crystal mounting on a glass fibre.

A small amount of colourless plate-like crystals, which could not be physically separated from the title compound, were also investigated and revealed to be isostructural with the frameworks reported by Zheng, Sun et al. (2004). The crystal data for this material will be the subject of a separate communication.

Structure description top

For related structures see: Zheng, Sun et al. (2004); Zheng, Wang et al. (2004); Paz & Klinowski (2003); Min & Lee (2002); Wang et al. (2002). For related literature, see: Cunha-Silva, Mafra et al. (2007); Cunha-Silva, Shi et al. (2007); Shi et al. (2007); Mafra et al. (2006); Shi et al. (2006); Paz, Rocha, Klinowski et al. (2005); Almeida Paz, Shi, Mafra et al. (2005); Almeida Paz, Shi, Trindade et al. (2005); Shi et al. (2005); Paz & Klinowski (2004); Almeida Paz et al. (2002a, 2002b, 2002c).

For related literature, see: Allen (2002); Allen & Motherwell (2002); Altomare et al. (1994); Deluzet et al. (2003).

Computing details top

Data collection: COLLECT (Nonius 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXTL (Bruker, 2001); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL (Bruker, 2001).

Figures top

	Fig. 1. (a) Schematic representation of the binuclear centrosymmetric anionic [Ho₂(NDC)₆(H₂O)₆]^6- unit showing the labelling scheme for all non-H atoms composing the asymmetric unit. Displacement ellipsoids are drawn at the 80% probability level and H atoms are represented as small spheres with arbitrary radii. (b) Magnification of the {Ho₂O₂(CO₂)₄(H₂O)₆} core of the binuclear unit, emphasizing the highly distorted {HoO₈} dodecahedral coordination environment for the Ho³⁺ centres. For selected bond lengths and angles of the {HoO₈} coordination polyhedron see the Table summarizing the geometrical details. Symmetry codes used to generate equivalent atoms: (i) 2 - x, -y, 1 - z; (ii) 1 + x, y, -1 + z.
	Fig. 2. Mixed polyhedral and ball-and-stick schematic representation of the two-dimensional (4,4) plane net formed by the self-assembly of the binuclear centrosymmetric anionic [Ho₂(NDC)₆(H₂O)₆]^6- units depicted in Fig. 1. The centres of gravity of the binuclear units were taken as the nodes of the network (blue spheres). Inter-nodal distances: 12.8742 (6) Å and 16.3127 (6) Å. Hydrogen atoms have been omitted for clarity.
	Fig. 3. (a) Mixed polyhedral and ball-and-stick and (b) and (c) topological representations of the crystal packing of the title compound. Hydrogen atoms have been omitted for clarity and adjacent (4,4) plane nets are represented with alternating colours.
	Fig. 4. O—H···O hydrogen bonding interactions connecting adjacent binuclear units within the two-dimensional layer (via O1W) and between adjacent layers (via O2W and O3W). Hydrogen bonds are represented as dashed purple lines. For geometrical details on the represented hydrogen bonding interactions see dedicated Table in the main paper.

poly[hexaaquabis(µ₃-naphthalene-2,6-dicarboxylato)(µ₂-naphthalene-2,6- dicarboxylato)diholmium(III)] top

Crystal data top

[Ho₂(C₁₂H₆O₄)₃(H₂O)₆]	Z = 2
M_r = 540.23	F(000) = 524
Triclinic, P1	D_x = 2.060 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.8856 (3) Å	Cell parameters from 14333 reflections
b = 9.6537 (5) Å	θ = 1.0–27.5°
c = 12.5438 (6) Å	µ = 4.60 mm⁻¹
α = 75.191 (2)°	T = 180 K
β = 74.224 (2)°	Block, white
γ = 75.352 (2)°	0.10 × 0.05 × 0.05 mm
V = 870.98 (7) Å³

Data collection top

Nonius Kappa CCD diffractometer	3135 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.067
Thin slice ω and φ scans	θ_max = 27.6°, θ_min = 3.5°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −10→9
T_min = 0.730, T_max = 0.796	k = −9→12
11608 measured reflections	l = −15→16
3987 independent reflections

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)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.079	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ²(F_o²) + (0.0301P)²] where P = (F_o² + 2F_c²)/3
3987 reflections	(Δ/σ)_max = 0.001
271 parameters	Δρ_max = 1.51 e Å⁻³
9 restraints	Δρ_min = −1.50 e Å⁻³

Crystal data top

[Ho₂(C₁₂H₆O₄)₃(H₂O)₆]	γ = 75.352 (2)°
M_r = 540.23	V = 870.98 (7) Å³
Triclinic, P1	Z = 2
a = 7.8856 (3) Å	Mo Kα radiation
b = 9.6537 (5) Å	µ = 4.60 mm⁻¹
c = 12.5438 (6) Å	T = 180 K
α = 75.191 (2)°	0.10 × 0.05 × 0.05 mm
β = 74.224 (2)°

Data collection top

Nonius Kappa CCD diffractometer	3987 independent reflections
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	3135 reflections with I > 2σ(I)
T_min = 0.730, T_max = 0.796	R_int = 0.067
11608 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.043	9 restraints
wR(F²) = 0.079	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	Δρ_max = 1.51 e Å⁻³
3987 reflections	Δρ_min = −1.50 e Å⁻³
271 parameters

Special details top

Experimental. See dedicated section in the main paper

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
Ho1	1.23306 (3)	0.20677 (3)	−0.001555 (19)	0.01786 (10)
O1W	1.1573 (5)	0.4195 (4)	0.0764 (3)	0.0232 (9)
H1A	1.207 (6)	0.504 (3)	0.039 (4)	0.035*
H1B	1.039 (3)	0.450 (5)	0.118 (4)	0.035*
O2W	1.4902 (5)	0.3308 (4)	−0.0586 (3)	0.0259 (10)
H2A	1.506 (8)	0.340 (5)	0.011 (2)	0.039*
H2B	1.466 (8)	0.425 (2)	−0.105 (3)	0.039*
O3W	1.2069 (5)	−0.0416 (4)	0.0556 (3)	0.0301 (10)
H3A	1.104 (4)	−0.083 (5)	0.073 (5)	0.045*
H3B	1.311 (4)	−0.116 (4)	0.057 (5)	0.045*
O1	0.9506 (5)	0.2157 (4)	0.1072 (3)	0.0280 (10)
O2	0.6931 (5)	0.3656 (4)	0.0793 (3)	0.0241 (9)
O3	0.6021 (5)	−0.1174 (4)	0.8691 (3)	0.0269 (10)
O4	0.4373 (5)	0.1075 (4)	0.8570 (3)	0.0251 (9)
O5	1.1644 (5)	0.3945 (4)	−0.1584 (3)	0.0236 (9)
O6	1.0619 (5)	0.1934 (5)	−0.1337 (3)	0.0264 (10)
C1	0.7893 (8)	0.2736 (6)	0.1411 (4)	0.0199 (13)
C2	0.7080 (7)	0.2329 (7)	0.2662 (4)	0.0228 (14)
C3	0.5563 (10)	0.3242 (9)	0.3151 (5)	0.064 (3)
H3	0.4986	0.4070	0.2690	0.076*
C4	0.4889 (11)	0.2952 (10)	0.4304 (5)	0.087 (4)
H4	0.3852	0.3585	0.4629	0.105*
C5	0.5711 (8)	0.1739 (7)	0.5001 (4)	0.0257 (14)
C6	0.5125 (8)	0.1470 (7)	0.6203 (4)	0.0317 (16)
H6	0.4139	0.2127	0.6549	0.038*
C7	0.5957 (8)	0.0288 (6)	0.6862 (4)	0.0219 (13)
C8	0.5390 (7)	0.0055 (6)	0.8131 (4)	0.0183 (12)
C9	0.7352 (12)	−0.0676 (9)	0.6357 (5)	0.068 (3)
H9	0.7895	−0.1530	0.6811	0.081*
C10	0.7972 (13)	−0.0426 (9)	0.5211 (5)	0.084 (4)
H10	0.8956	−0.1102	0.4886	0.101*
C11	0.7190 (8)	0.0806 (6)	0.4501 (4)	0.0250 (14)
C12	0.7875 (9)	0.1138 (7)	0.3314 (4)	0.0318 (15)
H12	0.8908	0.0512	0.2975	0.038*
C13	1.0862 (7)	0.3182 (7)	−0.1918 (4)	0.0217 (13)
C14	1.0289 (8)	0.3725 (7)	−0.3018 (4)	0.0242 (14)
C15	0.9115 (8)	0.3065 (7)	−0.3296 (4)	0.0286 (15)
H15	0.8619	0.2299	−0.2759	0.034*
C16	0.8682 (9)	0.3509 (7)	−0.4318 (4)	0.0307 (15)
H16	0.7879	0.3056	−0.4492	0.037*
C17	0.9428 (8)	0.4657 (7)	−0.5143 (4)	0.0241 (13)
C18	1.0982 (8)	0.4868 (6)	−0.3770 (4)	0.0264 (14)
H18	1.1732	0.5338	−0.3562	0.032*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ho1	0.01942 (16)	0.02085 (16)	0.01278 (13)	−0.00448 (11)	−0.00501 (9)	−0.00036 (9)
O1W	0.024 (2)	0.023 (2)	0.0200 (19)	−0.0050 (18)	−0.0003 (16)	−0.0053 (16)
O2W	0.027 (2)	0.030 (3)	0.023 (2)	−0.012 (2)	−0.0058 (18)	−0.0037 (17)
O3W	0.022 (2)	0.024 (2)	0.042 (2)	−0.0073 (19)	−0.006 (2)	−0.0011 (19)
O1	0.026 (2)	0.034 (3)	0.0193 (19)	−0.008 (2)	0.0008 (17)	−0.0019 (17)
O2	0.024 (2)	0.029 (2)	0.0183 (18)	−0.0072 (19)	−0.0085 (17)	0.0027 (17)
O3	0.034 (2)	0.024 (2)	0.0217 (19)	−0.004 (2)	−0.0144 (18)	0.0037 (17)
O4	0.027 (2)	0.026 (2)	0.0197 (19)	−0.004 (2)	−0.0015 (17)	−0.0053 (17)
O5	0.032 (2)	0.023 (2)	0.0164 (18)	−0.0026 (19)	−0.0130 (17)	0.0011 (16)
O6	0.026 (2)	0.037 (3)	0.0165 (18)	−0.013 (2)	−0.0058 (16)	0.0015 (17)
C1	0.023 (3)	0.026 (3)	0.016 (3)	−0.015 (3)	−0.002 (2)	−0.004 (2)
C2	0.016 (3)	0.035 (4)	0.015 (3)	−0.007 (3)	−0.005 (2)	0.002 (2)
C3	0.044 (5)	0.080 (6)	0.022 (3)	0.029 (4)	0.001 (3)	0.019 (3)
C4	0.055 (5)	0.111 (8)	0.026 (4)	0.061 (5)	0.008 (3)	0.013 (4)
C5	0.021 (3)	0.034 (4)	0.015 (3)	−0.004 (3)	−0.002 (2)	0.004 (2)
C6	0.023 (3)	0.042 (4)	0.021 (3)	0.000 (3)	−0.002 (2)	0.000 (3)
C7	0.025 (3)	0.023 (3)	0.016 (3)	−0.004 (3)	−0.003 (2)	−0.003 (2)
C8	0.017 (3)	0.026 (4)	0.018 (3)	−0.011 (3)	−0.009 (2)	−0.003 (2)
C9	0.088 (6)	0.055 (5)	0.019 (3)	0.033 (5)	−0.001 (4)	0.006 (3)
C10	0.113 (8)	0.058 (6)	0.022 (3)	0.059 (5)	0.003 (4)	0.001 (3)
C11	0.035 (4)	0.023 (3)	0.015 (3)	−0.004 (3)	−0.007 (2)	−0.002 (2)
C12	0.039 (4)	0.027 (4)	0.024 (3)	0.003 (3)	−0.004 (3)	−0.008 (3)
C13	0.013 (3)	0.027 (4)	0.024 (3)	0.002 (3)	−0.009 (2)	−0.004 (3)
C14	0.026 (3)	0.027 (4)	0.018 (3)	0.000 (3)	−0.010 (2)	−0.001 (2)
C15	0.039 (4)	0.026 (4)	0.023 (3)	−0.003 (3)	−0.015 (3)	−0.003 (2)
C16	0.042 (4)	0.028 (4)	0.027 (3)	−0.007 (3)	−0.016 (3)	−0.004 (3)
C17	0.030 (4)	0.024 (4)	0.019 (3)	0.002 (3)	−0.010 (2)	−0.008 (2)
C18	0.032 (4)	0.024 (4)	0.026 (3)	0.000 (3)	−0.015 (3)	−0.006 (3)

Geometric parameters (Å, º) top

Ho1—O1	2.267 (4)	C3—H3	0.9500
Ho1—O3ⁱ	2.252 (3)	C4—C5	1.399 (8)
Ho1—O4ⁱⁱ	2.279 (4)	C4—H4	0.9500
Ho1—O5	2.389 (3)	C5—C11	1.387 (8)
Ho1—O6	2.450 (4)	C5—C6	1.428 (7)
Ho1—O1W	2.370 (4)	C6—C7	1.359 (7)
Ho1—O2W	2.461 (4)	C6—H6	0.9500
Ho1—O3W	2.366 (4)	C7—C9	1.372 (9)
Ho1—C13	2.784 (5)	C7—C8	1.504 (7)
O1W—H1A	0.95 (4)	C9—C10	1.365 (8)
O1W—H1B	0.95 (4)	C9—H9	0.9500
O2W—H2A	0.95 (4)	C10—C11	1.405 (8)
O2W—H2B	0.95 (4)	C10—H10	0.9500
O3W—H3A	0.95 (4)	C11—C12	1.420 (7)
O3W—H3B	0.95 (4)	C12—H12	0.9500
O1—C1	1.256 (6)	C13—C14	1.494 (7)
O2—C1	1.262 (6)	C14—C18	1.378 (8)
O3—C8	1.270 (6)	C14—C15	1.404 (8)
O3—Ho1ⁱ	2.252 (3)	C15—C16	1.352 (7)
O4—C8	1.247 (7)	C15—H15	0.9500
O4—Ho1ⁱⁱⁱ	2.279 (4)	C16—C17	1.434 (8)
O5—C13	1.275 (7)	C16—H16	0.9500
O6—C13	1.268 (7)	C17—C17^iv	1.407 (12)
C1—C2	1.514 (7)	C17—C18^iv	1.421 (7)
C2—C12	1.349 (7)	C18—C17^iv	1.421 (7)
C2—C3	1.389 (9)	C18—H18	0.9500
C3—C4	1.379 (8)

O1—Ho1—O4ⁱⁱ	144.69 (15)	C12—C2—C1	120.6 (5)
O1—Ho1—O5	98.23 (13)	C3—C2—C1	119.5 (5)
O1—Ho1—O6	77.54 (13)	C4—C3—C2	120.2 (6)
O1—Ho1—O1W	72.71 (14)	C4—C3—H3	119.9
O1—Ho1—O2W	142.57 (14)	C2—C3—H3	119.9
O1—Ho1—O3W	76.58 (14)	C3—C4—C5	121.0 (7)
O3ⁱ—Ho1—O1	101.02 (13)	C3—C4—H4	119.5
O3ⁱ—Ho1—O4ⁱⁱ	96.82 (14)	C5—C4—H4	119.5
O3ⁱ—Ho1—O5	147.95 (14)	C11—C5—C4	118.4 (5)
O3ⁱ—Ho1—O6	155.80 (14)	C11—C5—C6	119.3 (5)
O3ⁱ—Ho1—O1W	83.38 (14)	C4—C5—C6	122.2 (6)
O3ⁱ—Ho1—O2W	72.20 (13)	C7—C6—C5	121.0 (6)
O3ⁱ—Ho1—O3W	76.60 (14)	C7—C6—H6	119.5
O4ⁱⁱ—Ho1—O5	81.43 (13)	C5—C6—H6	119.5
O4ⁱⁱ—Ho1—O6	73.82 (13)	C6—C7—C9	119.2 (5)
O4ⁱⁱ—Ho1—O1W	140.01 (13)	C6—C7—C8	120.6 (5)
O4ⁱⁱ—Ho1—O2W	72.11 (13)	C9—C7—C8	120.2 (5)
O4ⁱⁱ—Ho1—O3W	78.31 (14)	O4—C8—O3	123.9 (5)
O5—Ho1—O6	54.22 (13)	O4—C8—C7	118.8 (5)
O5—Ho1—O2W	76.91 (13)	O3—C8—C7	117.3 (5)
O6—Ho1—O2W	123.35 (12)	C10—C9—C7	121.1 (6)
O1W—Ho1—O5	78.18 (13)	C10—C9—H9	119.5
O1W—Ho1—O6	118.31 (14)	C7—C9—H9	119.5
O1W—Ho1—O2W	69.97 (13)	C9—C10—C11	121.6 (7)
O3W—Ho1—O5	133.18 (14)	C9—C10—H10	119.2
O3W—Ho1—O6	79.62 (14)	C11—C10—H10	119.2
O3W—Ho1—O2W	133.39 (14)	C5—C11—C10	117.6 (5)
O3W—Ho1—O1W	139.08 (13)	C5—C11—C12	119.6 (5)
O3ⁱ—Ho1—C13	170.11 (14)	C10—C11—C12	122.7 (6)
O1—Ho1—C13	88.87 (14)	C2—C12—C11	120.9 (6)
O4ⁱⁱ—Ho1—C13	74.78 (15)	C2—C12—H12	119.6
O3W—Ho1—C13	106.20 (17)	C11—C12—H12	119.6
O1W—Ho1—C13	99.61 (15)	O6—C13—O5	120.3 (5)
O5—Ho1—C13	27.19 (15)	O6—C13—C14	119.5 (5)
O6—Ho1—C13	27.09 (15)	O5—C13—C14	120.2 (5)
O2W—Ho1—C13	99.84 (15)	O6—C13—Ho1	61.6 (3)
Ho1—O1W—H1A	122 (3)	O5—C13—Ho1	58.9 (2)
Ho1—O1W—H1B	121 (3)	C14—C13—Ho1	173.3 (4)
H1A—O1W—H1B	108 (4)	C18—C14—C15	120.6 (5)
Ho1—O2W—H2A	103 (3)	C18—C14—C13	118.3 (5)
Ho1—O2W—H2B	113 (4)	C15—C14—C13	121.1 (5)
H2A—O2W—H2B	110 (4)	C16—C15—C14	120.8 (6)
Ho1—O3W—H3A	129 (3)	C16—C15—H15	119.6
Ho1—O3W—H3B	120 (3)	C14—C15—H15	119.6
H3A—O3W—H3B	110 (4)	C15—C16—C17	120.4 (6)
C1—O1—Ho1	155.6 (4)	C15—C16—H16	119.8
C8—O3—Ho1ⁱ	138.9 (4)	C17—C16—H16	119.8
C8—O4—Ho1ⁱⁱⁱ	154.8 (3)	C17^iv—C17—C18^iv	119.4 (6)
C13—O5—Ho1	93.9 (3)	C17^iv—C17—C16	118.9 (6)
C13—O6—Ho1	91.3 (3)	C18^iv—C17—C16	121.7 (6)
O1—C1—O2	124.8 (5)	C14—C18—C17^iv	119.8 (6)
O1—C1—C2	117.0 (5)	C14—C18—H18	120.1
O2—C1—C2	118.2 (5)	C17^iv—C18—H18	120.1
C12—C2—C3	119.8 (5)

O3ⁱ—Ho1—O1—C1	131.2 (9)	C6—C7—C8—O3	169.4 (5)
O4ⁱⁱ—Ho1—O1—C1	−109.8 (9)	C9—C7—C8—O3	−12.2 (9)
O3W—Ho1—O1—C1	−155.6 (9)	C6—C7—C9—C10	3.3 (13)
O1W—Ho1—O1—C1	51.8 (9)	C8—C7—C9—C10	−175.1 (8)
O5—Ho1—O1—C1	−23.0 (9)	C7—C9—C10—C11	−1.3 (16)
O6—Ho1—O1—C1	−73.4 (9)	C4—C5—C11—C10	−178.5 (9)
O2W—Ho1—O1—C1	56.2 (9)	C6—C5—C11—C10	4.2 (10)
C13—Ho1—O1—C1	−48.6 (9)	C4—C5—C11—C12	2.8 (10)
O3ⁱ—Ho1—O5—C13	162.5 (3)	C6—C5—C11—C12	−174.5 (6)
O1—Ho1—O5—C13	−71.0 (3)	C9—C10—C11—C5	−2.5 (14)
O4ⁱⁱ—Ho1—O5—C13	73.3 (3)	C9—C10—C11—C12	176.2 (9)
O3W—Ho1—O5—C13	8.3 (4)	C3—C2—C12—C11	−0.5 (10)
O1W—Ho1—O5—C13	−141.3 (3)	C1—C2—C12—C11	175.6 (6)
O6—Ho1—O5—C13	−2.9 (3)	C5—C11—C12—C2	−1.6 (10)
O2W—Ho1—O5—C13	146.8 (3)	C10—C11—C12—C2	179.7 (7)
O3ⁱ—Ho1—O6—C13	−158.0 (3)	Ho1—O6—C13—O5	−5.1 (5)
O1—Ho1—O6—C13	112.8 (3)	Ho1—O6—C13—C14	172.4 (4)
O4ⁱⁱ—Ho1—O6—C13	−88.1 (3)	Ho1—O5—C13—O6	5.3 (5)
O3W—Ho1—O6—C13	−168.8 (3)	Ho1—O5—C13—C14	−172.3 (4)
O1W—Ho1—O6—C13	50.5 (3)	O1—Ho1—C13—O6	−64.2 (3)
O5—Ho1—O6—C13	2.9 (3)	O4ⁱⁱ—Ho1—C13—O6	84.1 (3)
O2W—Ho1—O6—C13	−33.1 (4)	O3W—Ho1—C13—O6	11.5 (3)
Ho1—O1—C1—O2	32.9 (12)	O1W—Ho1—C13—O6	−136.5 (3)
Ho1—O1—C1—C2	−144.8 (7)	O5—Ho1—C13—O6	−174.8 (5)
O1—C1—C2—C12	−16.9 (8)	O2W—Ho1—C13—O6	152.4 (3)
O2—C1—C2—C12	165.2 (5)	O1—Ho1—C13—O5	110.6 (3)
O1—C1—C2—C3	159.2 (6)	O4ⁱⁱ—Ho1—C13—O5	−101.0 (3)
O2—C1—C2—C3	−18.7 (9)	O3W—Ho1—C13—O5	−173.7 (3)
C12—C2—C3—C4	1.3 (13)	O1W—Ho1—C13—O5	38.4 (3)
C1—C2—C3—C4	−174.8 (8)	O6—Ho1—C13—O5	174.8 (5)
C2—C3—C4—C5	−0.1 (15)	O2W—Ho1—C13—O5	−32.8 (3)
C3—C4—C5—C11	−2.0 (14)	O6—C13—C14—C18	−162.7 (5)
C3—C4—C5—C6	175.3 (8)	O5—C13—C14—C18	14.9 (8)
C11—C5—C6—C7	−2.3 (10)	O6—C13—C14—C15	15.6 (8)
C4—C5—C6—C7	−179.5 (8)	O5—C13—C14—C15	−166.9 (5)
C5—C6—C7—C9	−1.6 (10)	C18—C14—C15—C16	2.0 (9)
C5—C6—C7—C8	176.9 (5)	C13—C14—C15—C16	−176.2 (5)
Ho1ⁱⁱⁱ—O4—C8—O3	−23.0 (12)	C14—C15—C16—C17	0.4 (9)
Ho1ⁱⁱⁱ—O4—C8—C7	158.7 (6)	C15—C16—C17—C17^iv	−1.9 (11)
Ho1ⁱ—O3—C8—O4	−57.1 (8)	C15—C16—C17—C18^iv	179.1 (6)
Ho1ⁱ—O3—C8—C7	121.2 (5)	C15—C14—C18—C17^iv	−2.9 (9)
C6—C7—C8—O4	−12.2 (8)	C13—C14—C18—C17^iv	175.4 (5)
C9—C7—C8—O4	166.2 (7)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1A···O2^v	0.95 (4)	1.82 (2)	2.725 (5)	157 (5)
O1W—H1B···O5^v	0.95 (4)	1.95 (3)	2.818 (5)	150 (4)
O2W—H2A···O2^vi	0.95 (4)	1.98 (4)	2.782 (5)	140 (5)
O2W—H2B···O2^v	0.95 (4)	2.14 (4)	2.901 (6)	136 (4)
O3W—H3A···O6^vii	0.95 (4)	1.78 (4)	2.704 (5)	165 (5)
O3W—H3B···O2W^viii	0.95 (4)	2.26 (4)	3.181 (6)	165 (4)
O3W—H3B···O4ⁱ	0.95 (4)	2.53 (5)	3.145 (6)	123 (4)

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

Experimental details

Crystal data
Chemical formula	[Ho₂(C₁₂H₆O₄)₃(H₂O)₆]
M_r	540.23
Crystal system, space group	Triclinic, P1
Temperature (K)	180
a, b, c (Å)	7.8856 (3), 9.6537 (5), 12.5438 (6)
α, β, γ (°)	75.191 (2), 74.224 (2), 75.352 (2)
V (Å³)	870.98 (7)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	4.60
Crystal size (mm)	0.10 × 0.05 × 0.05

Data collection
Diffractometer	Nonius Kappa CCD
Absorption correction	Multi-scan (SORTAV; Blessing, 1995)
T_min, T_max	0.730, 0.796
No. of measured, independent and observed [I > 2σ(I)] reflections	11608, 3987, 3135
R_int	0.067
(sin θ/λ)_max (Å⁻¹)	0.651

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.043, 0.079, 1.00
No. of reflections	3987
No. of parameters	271
No. of restraints	9
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	1.51, −1.50

Computer programs: COLLECT (Nonius 1998), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO and SCALEPACK (Otwinowski & Minor 1997), SIR92 (Altomare et al., 1994), SHELXTL (Bruker, 2001), DIAMOND (Brandenburg, 2006).

Selected geometric parameters (Å, º) top

Ho1—O1	2.267 (4)	Ho1—O6	2.450 (4)
Ho1—O3ⁱ	2.252 (3)	Ho1—O1W	2.370 (4)
Ho1—O4ⁱⁱ	2.279 (4)	Ho1—O2W	2.461 (4)
Ho1—O5	2.389 (3)	Ho1—O3W	2.366 (4)

O1—Ho1—O4ⁱⁱ	144.69 (15)	O4ⁱⁱ—Ho1—O6	73.82 (13)
O1—Ho1—O5	98.23 (13)	O4ⁱⁱ—Ho1—O1W	140.01 (13)
O1—Ho1—O6	77.54 (13)	O4ⁱⁱ—Ho1—O2W	72.11 (13)
O1—Ho1—O1W	72.71 (14)	O4ⁱⁱ—Ho1—O3W	78.31 (14)
O1—Ho1—O2W	142.57 (14)	O5—Ho1—O6	54.22 (13)
O1—Ho1—O3W	76.58 (14)	O5—Ho1—O2W	76.91 (13)
O3ⁱ—Ho1—O1	101.02 (13)	O6—Ho1—O2W	123.35 (12)
O3ⁱ—Ho1—O4ⁱⁱ	96.82 (14)	O1W—Ho1—O5	78.18 (13)
O3ⁱ—Ho1—O5	147.95 (14)	O1W—Ho1—O6	118.31 (14)
O3ⁱ—Ho1—O6	155.80 (14)	O1W—Ho1—O2W	69.97 (13)
O3ⁱ—Ho1—O1W	83.38 (14)	O3W—Ho1—O5	133.18 (14)
O3ⁱ—Ho1—O2W	72.20 (13)	O3W—Ho1—O6	79.62 (14)
O3ⁱ—Ho1—O3W	76.60 (14)	O3W—Ho1—O2W	133.39 (14)
O4ⁱⁱ—Ho1—O5	81.43 (13)	O3W—Ho1—O1W	139.08 (13)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1A···O2ⁱⁱⁱ	0.95 (4)	1.82 (2)	2.725 (5)	157 (5)
O1W—H1B···O5ⁱⁱⁱ	0.95 (4)	1.95 (3)	2.818 (5)	150 (4)
O2W—H2A···O2^iv	0.95 (4)	1.98 (4)	2.782 (5)	140 (5)
O2W—H2B···O2ⁱⁱⁱ	0.95 (4)	2.14 (4)	2.901 (6)	136 (4)
O3W—H3A···O6^v	0.95 (4)	1.78 (4)	2.704 (5)	165 (5)
O3W—H3B···O2W^vi	0.95 (4)	2.26 (4)	3.181 (6)	165 (4)
O3W—H3B···O4ⁱ	0.95 (4)	2.53 (5)	3.145 (6)	123 (4)

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

Acknowledgements

The authors are grateful to Fundação para a Ciência e a Tecnologia (FCT, Portugal) for financial support under the POCI-PPCDT/QUI/58377/2004 research project supported by FEDER.

References

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