Poly[[tetra­aquadi-μ₄-fumarato-μ₂-oxalato-dierbium(III)] tetra­hydrate]

Abstract

The title compound, {[Er₂(C₄H₂O₄)₂(C₂O₄)(H₂O)₄]·4H₂O}_n, was synthesized by the reaction of erbium nitrate hexa­hydrate with fumaric acid and oxalic acid under hydro­thermal conditions. The Er³⁺ cation (site symmetry ..2) is eight-coordinated by six O atoms from four fumarate anions (site symmetry ..2) and one bidentate oxalate anion (site symmetry 222), and by two water mol­ecules. The complex exhibits a three-dimensional structure consisting of oxalate pillared Er–fumarate layers with channels occupied by coordinating and lattice water mol­ecules. The three-dimensional structure features by O_water—H⋯O hydrogen bonds involving both the coordinating and lattice water mol­ecules.

Related literature  

For lanthanide–metal complexes containing fumarate ligands, see: Zhang et al. (2006 ▶). For lanthanide-containing structures with metal-organic frameworks and two different flexible carboxyl­ate ligands, see: Zhang et al. (2008 ▶); Zhu et al. (2007 ▶).

Experimental  

Crystal data  

• [Er₂(C₄H₂O₄)₂(C₂O₄)(H₂O)₄]·4H₂O

• M _r = 794.78

• Orthorhombic,

• a = 9.6016 (19) Å

• b = 15.701 (3) Å

• c = 26.722 (5) Å

• V = 4028.5 (14) ų

• Z = 8

• Mo Kα radiation

• μ = 8.38 mm⁻¹

• T = 293 K

• 0.19 × 0.16 × 0.13 mm

Data collection  

• Bruker SMART APEX CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.305, T _max = 0.402

• 9284 measured reflections

• 1162 independent reflections

• 1088 reflections with I > 2σ(I)

• R _int = 0.022

Refinement  

• R[F ² > 2σ(F ²)] = 0.018

• wR(F ²) = 0.045

• S = 1.11

• 1162 reflections

• 74 parameters

• H-atom parameters constrained

• Δρ_max = 0.51 e Å⁻³

• Δρ_min = −1.04 e Å⁻³

Data collection: SMART (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 1999 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Supplementary Material

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H4A⋯O5i	0.85	2.35	3.045 (5)	139
O4—H4B⋯O3ii	0.85	1.91	2.750 (3)	168
O5—H5A⋯O4	0.85	1.99	2.836	180
O5—H5B⋯O2iii	0.85	2.36	2.938 (4)	125

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

supplementary crystallographic information

Comment

In recent years, lanthanide metal-organic compounds have been of great interest due to their fascinating structures and potential applications in magnetism, luminescence, catalysis, gas storage and separation. Multitopic carboxylates have received considerable study due to their availability and potential for allowing for the tailored design of such frameworks. As we know, fumaric acid is a unique ligand with a relatively small, conjugated middle part and versatile coordination modes. A large number of lanthanide metal complexes containing fumarate ligands have been reported, see: Zhang et al. (2006). And lanthanide-containing MOFs with two different flexible carboxylate ligands are less developed, see: Zhang et al.(2008); Zhu et al.(2007). In this paper, we report the synthesis and structure of a new metal-organic compound constructed from fumarate ligands coordinated to Er atoms in the presence of oxalate ligands.

In the title compound I, Er1 is eight-coordinated with four O atoms from four fumarate ligands (O2ⁱⁱⁱ, O1^iv, O2, O1^v, (iii), 1.25 - x, 0.25 - y, z; (iv) 1.5 - x, 0.5 - y, 1 - z; (v) -0.25 + x, -0.25 + y, 1 - z), two O atoms from one oxalate ligand (O3 and O3ⁱⁱⁱ) and two water molecules (O4 and O4ⁱⁱⁱ) (Fig. 1). The Er—O bond lengths are between 2.273 (3)–2.428 (3) Å. The Er atoms are linked through bridging carboxyl groups of fumarate ligands to form two-dimensional Er–fum layers in the ab plane (Fig. 2). Along the c direction, the Er-fum layers are pillared by the oxalic acid resulting in a three-dimensional structure. The framework contains approximately 6.2 Å×11.1 Å rectangular channels along the [100] direction. These channels are occupied by coordinated and free water molecules (Fig. 3). The three-dimensional structure is stabilized by O_water—H···O hydrogen bonds involving both the coordinated and free water molecules.

Experimental

A mixture of fumaric acid (0.058 g, 0.50 mmol), oxalic acid (0.063 g, 0.50 mmol) and erbium nitrate hexahydrate (0.230 g, 0.50 mmol) in distilled water (15 ml) was stirred fully in air, and then sealed in 25 ml Teflon-lined stainless steel container, which was heated firstly at 403 K for 2 days and then at 443 K for 1 day. The pink block product, I, was crystallized upon cooling to 273 K.

Refinement

The H atoms attached to carbon were positioned geometrically and treated as riding on their parent atoms, with C—H 0.93. The hydrogen atoms of the water molecules were located in difference maps and refined by using the 'DFIX' command with O—H = 0.85 (2)Å with U_iso(H) = 1.5U_iso(O).

Figures

Fig. 1.

Coordination environment of Er1 in compound I with labelling and displacement ellipsoids drawn at the 30% probability level. Symmetry codes: (i) 2.25 - x, 0.25 - y, z; (ii) 1.25 - x, y, 1.25 - z; (iii) 1.25 - x, 0.25 - y, z; (iv) 1.5 - x, 0.5 - y, 1 - z; (v) -0.25 + x, -0.25 + y, 1 - z; (vi) 1 + x, y, z; (vii) 2 - x, -y, 1 - z; (viii) x, 0.25 - y, 1.25 - z; (ix) -1 + x, y, z; (x) -0.75 + x, 0.25 + y, 1 - z.

Fig. 2.

The two-dimensional Er-fum layer extends in the ab plane.

Fig. 3.

The three-dimensional network with rectangular channels along the [100] direction.

Crystal data

[Er2(C4H2O4)2(C2O4)(H2O)4]·4H2O	Dx = 2.621 Mg m−3
Mr = 794.78	Melting point: not measured K
Orthorhombic, Fddd	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -F 2uv 2vw	Cell parameters from 9875 reflections
a = 9.6016 (19) Å	θ = 3.0–27.5°
b = 15.701 (3) Å	µ = 8.38 mm−1
c = 26.722 (5) Å	T = 293 K
V = 4028.5 (14) Å3	Block, pink
Z = 8	0.19 × 0.16 × 0.13 mm
F(000) = 3008

Data collection

Bruker SMART APEX CCD diffractometer	1162 independent reflections
Radiation source: fine-focus sealed tube	1088 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
Detector resolution: 9.00cm pixels mm-1	θmax = 27.5°, θmin = 3.0°
ω scans	h = −12→12
Absorption correction: multi-scan (SADABS; Bruker, 2001)	k = −20→20
Tmin = 0.305, Tmax = 0.402	l = −34→31
9284 measured reflections

Refinement

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)] = 0.018	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.045	H-atom parameters constrained
S = 1.11	w = 1/[σ2(Fo2) + (0.0186P)2 + 60.2587P] where P = (Fo2 + 2Fc2)/3
1162 reflections	(Δ/σ)max = 0.003
74 parameters	Δρmax = 0.51 e Å−3
0 restraints	Δρmin = −1.04 e Å−3

Special details

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
C1	0.9358 (4)	0.1660 (2)	0.52974 (13)	0.0167 (6)
C2	1.0906 (4)	0.1604 (3)	0.53278 (16)	0.0268 (8)
H2	1.1407	0.2110	0.5348	0.032*
C3	0.6250	0.0756 (3)	0.6250	0.0150 (8)
Er1	0.6250	0.1250	0.508677 (7)	0.01528 (8)
O1	0.8868 (3)	0.23742 (16)	0.51740 (10)	0.0237 (5)
O2	0.8597 (3)	0.10210 (16)	0.53731 (11)	0.0239 (5)
O3	0.6164 (3)	0.04009 (15)	0.58332 (9)	0.0190 (5)
O4	0.4757 (3)	0.12267 (15)	0.43533 (9)	0.0256 (5)
H4A	0.3985	0.1447	0.4440	0.031*
H4B	0.4595	0.0706	0.4288	0.031*
O5	0.5533 (3)	0.20049 (15)	0.34370 (9)	0.0859 (16)
H5A	0.5298	0.1769	0.3711	0.103*
H5B	0.5661	0.2534	0.3485	0.129*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0141 (15)	0.0186 (16)	0.0173 (16)	0.0032 (13)	−0.0010 (13)	0.0001 (13)
C2	0.0159 (17)	0.0232 (18)	0.041 (2)	−0.0021 (14)	0.0015 (15)	−0.0025 (17)
C3	0.0133 (19)	0.013 (2)	0.019 (2)	0.000	−0.0012 (19)	0.000
Er1	0.01765 (12)	0.01422 (11)	0.01396 (11)	0.00560 (8)	0.000	0.000
O1	0.0239 (13)	0.0200 (12)	0.0270 (13)	0.0067 (10)	0.0003 (11)	0.0045 (10)
O2	0.0168 (12)	0.0205 (12)	0.0344 (14)	0.0009 (10)	0.0001 (11)	0.0027 (11)
O3	0.0269 (13)	0.0139 (11)	0.0161 (11)	−0.0003 (10)	−0.0015 (10)	−0.0010 (9)
O4	0.0296 (13)	0.0215 (12)	0.0256 (13)	−0.0017 (11)	−0.0040 (11)	0.0002 (11)
O5	0.099 (4)	0.076 (3)	0.082 (3)	−0.011 (3)	0.012 (3)	0.037 (3)

Geometric parameters (Å, º)

C1—O2	1.258 (4)	Er1—O3	2.401 (2)
C1—O1	1.260 (4)	Er1—O2	2.407 (3)
C1—C2	1.491 (5)	Er1—O2iii	2.407 (3)
C2—C2i	1.294 (8)	Er1—O4	2.428 (2)
C2—H2	0.9300	Er1—O4iii	2.428 (2)
C3—O3	1.249 (3)	O1—Er1iv	2.273 (3)
C3—O3ii	1.249 (3)	O4—H4A	0.8500
C3—C3iii	1.550 (9)	O4—H4B	0.8499
Er1—O1iv	2.273 (3)	O5—H5A	0.8500
Er1—O1v	2.273 (3)	O5—H5B	0.8500
Er1—O3iii	2.401 (2)
O2—C1—O1	122.4 (3)	O3—Er1—O2iii	77.67 (9)
O2—C1—C2	121.5 (3)	O2—Er1—O2iii	142.93 (13)
O1—C1—C2	116.0 (3)	O1iv—Er1—O4	74.78 (9)
C2i—C2—C1	124.0 (5)	O1v—Er1—O4	76.55 (9)
C2i—C2—H2	118.0	O3iii—Er1—O4	134.38 (9)
C1—C2—H2	118.0	O3—Er1—O4	129.93 (8)
O3—C3—O3ii	126.9 (4)	O2—Er1—O4	143.80 (9)
O3—C3—C3iii	116.6 (2)	O2iii—Er1—O4	72.91 (9)
O3ii—C3—C3iii	116.6 (2)	O1iv—Er1—O4iii	76.55 (9)
O1iv—Er1—O1v	144.28 (13)	O1v—Er1—O4iii	74.78 (9)
O1iv—Er1—O3iii	74.25 (9)	O3iii—Er1—O4iii	129.93 (8)
O1v—Er1—O3iii	141.35 (9)	O3—Er1—O4iii	134.38 (9)
O1iv—Er1—O3	141.35 (9)	O2—Er1—O4iii	72.91 (9)
O1v—Er1—O3	74.25 (9)	O2iii—Er1—O4iii	143.80 (9)
O3iii—Er1—O3	67.62 (11)	O4—Er1—O4iii	72.38 (12)
O1iv—Er1—O2	106.62 (9)	C1—O1—Er1iv	160.8 (3)
O1v—Er1—O2	84.78 (9)	C1—O2—Er1	111.9 (2)
O3iii—Er1—O2	77.67 (9)	C3—O3—Er1	119.4 (2)
O3—Er1—O2	71.66 (9)	Er1—O4—H4A	106.7
O1iv—Er1—O2iii	84.78 (9)	Er1—O4—H4B	106.7
O1v—Er1—O2iii	106.62 (9)	H4A—O4—H4B	106.7
O3iii—Er1—O2iii	71.66 (9)	H5A—O5—H5B	109.5

Symmetry codes: (i) −x+9/4, −y+1/4, z; (ii) −x+5/4, y, −z+5/4; (iii) −x+5/4, −y+1/4, z; (iv) −x+3/2, −y+1/2, −z+1; (v) x−1/4, y−1/4, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4A···O5vi	0.85	2.35	3.045 (5)	139
O4—H4B···O3vii	0.85	1.91	2.750 (3)	168
O5—H5A···O4	0.85	1.99	2.836	180
O5—H5B···O2viii	0.85	2.36	2.938 (4)	125

Symmetry codes: (vi) −x+3/4, y, −z+3/4; (vii) −x+1, −y, −z+1; (viii) −x+3/2, y+1/4, z−1/4.