The first three-dimensional FeIII–SrII heterometallic coordination polymer: poly[[di­aqua­tetra­kis­(μ3-pyridine-2,3-di­carboxyl­ato)diiron(III)strontium(II)] dihydrate]

Yang, Y.; Li, T.; Chen, Y.

doi:10.1107/S2053229615016617

The first three-dimensional Fe^III-Sr^II heterometallic coordination polymer: poly[[diaquatetrakis(₃-pyridine-2,3-dicarboxylato)diiron(III)strontium(II)] dihydrate]

Y. Yang, T. Li and Y. Chen

The title compound, poly[[diaqua-1 [kappa]

²O-tetrakis( [mu]

₃-pyridine-2,3-dicarboxylato)-2:1:2' [kappa]

¹⁰N,O²:O^2',O³:O^3';2:1:2' [kappa]

⁸O³:O^3':N,O²-diiron(III)strontium(II)] dihydrate], {[Fe₂Sr(C₇H₃O₄)₄(H₂O)₂]·2H₂O}_n, which has triclinic (P $\overline{1}$ ) symmetry, was prepared by the reaction of pyridine-2,3-dicarboxylic acid, SrCl₂·6H₂O and Fe(OAc)₂(OH) (OAc is acetate) in the presence of imidazole in water at 363 K. In the crystal structure, the pyridine-2,3-dicarboxylate (pydc^2-) ligand exhibits [mu]

₃-

¹,

¹:

¹:

¹ and

₃-

¹,

¹:

¹,

¹:

¹ coordination modes, bridging two Fe^III cations and one Sr^II cation. The Sr^II cation, which is located on an inversion centre, is eight-coordinated by six O atoms of four pydc^2- ligands and two water molecules. The coordination geometry of the Sr^II cation can be best described as distorted dodecahedral. The Fe^III cation is six-coordinated by O and N atoms of four pydc^2- ligands in a slightly distorted octahedral geometry. Each Fe^III cation bridges two neighbouring Fe^III cations to form a one-dimensional [Fe₂(pydc)₄]_n chain. The chains are connected by Sr^II cations to form a three-dimensional framework. The topology type of this framework is tfj. The structure displays O-H

O and C-H

O hydrogen bonding.

Keywords: heterometallic three-dimensional coordination polymer; iron(III); strontium(II); pyridine-2,3-dicarboxylate; crystal structure; tfj topology.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S2053229615016617/wq3100sup1.cif Contains datablocks 1, global
	Structure factor file (CIF format) https://doi.org/10.1107/S2053229615016617/wq3100Isup2.hkl Contains datablock I

CCDC reference: 773745

Introduction top

Heterometallic coordination polymers containing both transition metals and alkaline earth metals are currently being widely investigated, due to the aesthetically pleasing architectures that many such complexes possess and for their potential applications in the fields of catalysis, materials science and biochemistry (Cao et al., 2008; Fromm, 2008; Harder, 2003; Zhang et al., 2012; Lin et al., 2003). However, the construction of these heterometallic coordination polymers is a significant challenge (Chen et al., 2014). Firstly, the alkaline earth metals prefer O- to N-atom donors, while transition metals ions prefer N- to O-atom donors. Secondly, the broad span of coordination numbers of alkaline earth metals makes the topologies of the resulting coordination polymers difficult to control. Some rare examples of Fe–Sr heterometallic coordination complexes have been reported (Xu et al., 2015; Herbert et al., 2013; Samanta et al., 2006; Prodius et al., 2006), and most of them are trinuclear (Samanta et al., 2006; Prodius et al., 2006) or tetranuclear complexes (Herbert et al., 2013), or one-dimensional chain structures (Xu et al., 2015). Until now, no Fe–Sr heterometallic coordination polymers have been reported.

As an N-heterocyclic carboxylate ligand, pyridine-2,3-dicarboxylate (pydc^2-) provides one N atom and two carboxylate groups to coordinate to metal ions. It can therefore coordinate with either transition metals or alkaline earth metals to form coordination complexes, as exemplified by two heterometallic complexes (Co–Ca–2,3-pydc and Co–Ba–2,3-pydc) reported by the Lazarescu group (Lazarescu et al., 2011) and five heterometallic Sr^II–M^II–2,3-pydc (M = Co, Ni, Zn or Cu) three-dimensional coordination polymers reported by our group (Chen et al., 2014).

In our previous work, we have reported several series of Sr–transition metal (Chen et al., 2014, 2015) and Sr–Ln (Chen, et al., 2013) heterometallic coordination polymers based on N-heterocyclic carboxylate ligands. In this report, we present the synthesis and crystal structure analysis of the first three-dimensional Fe^III–Sr^II heterometallic coordination polymer, {[Fe₂Sr(pydc)₄(H₂O)₂]·2nH₂O}_n, (1) (see Scheme 1), in which the coordination modes of the pydc^2- ligand are different from that reported previously (Chen et al., 2014).

Experimental top

Synthesis and crystallization top

A mixture of pyridine-2,3-dicarboxylic acid (0.0331 g, 0.2 mmol), SrCl₂·6H₂O (0.0264 g, 0.1 mmol), Fe(OAc)₂(OH) (0.0167 g, 0.087 mmol), imidazole (0.0193 g, 0.284 mmol) and H₂O–C₂H₅OH (2 ml, 2:1 v/v) was sealed in a Pyrex bottle (8 ml) and heated at 363 K for 2 d. The bottle was then cooled to room temperature, generating light-brown block-shaped crystals of (1) (yield 0.0093 g, 23%, based on Fe). Elemental analysis, calculated for C₂₈H₂₀Fe₂N₄O₂₀Sr: C 36.09, H 2.16, N 6.01%; found: C 36.21, H 2.15, N 6.13%.

Refinement top

H atoms on pyridine C atoms were positioned geometrically and refined as riding atoms, with C—H = 0.97 Å and U_iso(H) = 1.2U_eq(C). Water H atoms were located in a difference Fourier map and refined with restraints of O—H = 0.86 (1) Å and U_iso(H) = 1.5U_eq(O).

Results and discussion top

The asymmetric unit of (1) consists of two pydc^2- ligands, one Fe^III cation, half an Sr^II cation, one coordinated water molecule and a solvent water molecule (Fig. 1). There are four doubly deprotonated pydc^2- ligands; two display a µ₃-η¹:η¹:η¹:η¹ coordination mode and two exhibit a µ₃-η¹:η¹:η¹:η¹:η¹ mode (see Scheme 2). Each pydc^2- ligand bridges two Fe^III cations and one Sr^II cation. The Fe^III cation is six-coordinated by one O atom (O5) and one N atom (N2) in coordination mode A (see Scheme 2), one O atom (O8B) in coordination mode B, one O atom (O2D) and one N atom (N1D) in coordination mode C, and one O atom (O4C) in coordination mode D, forming a slightly distorted octahedral structure. The Fe—O bond lengths range from 1.9448 (18) to 1.9810 (19) Å, and the Fe—N1 and Fe—N2 distances are 2.146 (2) and 2.171 (2) Å, respectively (Table 2). All the Fe—O and Fe—N distances are in good agreement with reference values (Xu et al., 2008; Wang et al., 2006; Goher et al., 1993; Allen et al., 1987). Each Fe^III cation is bridged to two neighbouring Fe^III cations; one side is bridged by two pydc^2- ligands in a µ₃-η¹:η¹:η¹:η¹ coordination mode and the other side is bridged by two pydc^2- ligands in a µ₃-η¹:η¹:η¹:η¹:η¹ coordination mode, forming a one-dimensional [Fe₂(pydc)₄]_n chain structure (Fig. 2). The average Fe···Fe distance is 6.566(s.u.?) Å. The Sr^II cation, which is located on an inversion centre, is eight-coordinated by two water molecules (O9 and O9A) and six O atoms from four pydc^2- ligands, in which two atoms (O7 and O7A) display a µ₃-η¹:η¹:η¹:η¹ coordination mode and four atoms (O1, O3, O1A and O3A) exhibit a µ₃-η¹:η¹:η¹:η¹:η¹ coordination mode. The Sr—O bond lengths range from 2.5617 (19) to 2.776 (2) Å, in good agreement with reported values (Chen et al., 2014). The one-dimensional [Fe₂(pydc)₄]_n chains are bridged by Sr^II cations to form a three-dimensional framework (Fig. 3).

In addition, the structure of (1) is stabilized by intramolecular hydrogen-bond interactions (Table 3) between the coordinated water molecules and the carboxylate groups of the pydc^2- ligands (O9—H9A···O4; see Table 3 for geometric parameters and symmetry codes), or between the pyridine ring and the coordinated water molecules (C3—H3···O9^viii) or the carboxylate groups (intermolecular hydrogen bonds C4—H4···O2^ix, C4—H4···O8^x, C5—H5···O6^x and C10—H10···O3ⁱ). The free water molecules are connected to the three-dimensional framework by three intermolecular hydrogen bonds (O10—H10A···O6^v, O9—H9B···O10^vi and O10—H10B···O7^vii) (Fig. 4).

To better understand the three-dimensional framework of (1), a topological approach has been applied. As shown in Fig. 5, each pydc^2- ligand bridges two Fe^III cations and one Sr^II cation, which can be simplified to a 3-connected node with point symbol (4.8²). The Fe^III cation can be simplified to a 4-connected node with point symbol (4².8⁴) and the Sr^II cation can be simplified to a 4-connected node with point symbol (8⁴.12²). The whole structure can be simplified to a 3-nodal 3,4,4-c net, with point symbol for the net (4.8²)₄(4².8⁴)₂(8⁴.12²). The topology type of the framework is tfj.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of (1), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) -x + 2,-y + 2,-z; (ii) -x + 3, -y + 2, -z + 1; (iii) -x + 2, -y + 2, -z + 1; (iv) x + 1, y + 1, z + 1.]
	Fig. 2. The one-dimensional chain structure of [Fe₂(pydc)₄]_n.
	Fig. 3. The three-dimensional framework of (1), including the hydrogen bonding (dashed lines), viewed along the b axis. H atoms which are not involved in hydrogen bonding have been omitted for clarity
	Fig. 4. A schematic representation of the 3-nodal topology net of (1) with the topological notation (4.8²)₄(4².8⁴)₂(8⁴.12²), viewed along the b axis. Light-orange balls represent the pyridine-2,3-dicarboxylate ligand.

Poly[[diaqua-1κ²O-tetrakis(µ₃-pyridine-2,3-dicarboxylato)-2:1:2'κ¹⁰N,O²:O^2',O³:O^3';2:1:2'κ⁸O³:O^3':N,O²-diiron(III)strontium(II)] dihydrate] top

Crystal data top

[Fe₂Sr(C₇H₃O₄)₄(H₂O)₂]·2H₂O	V = 793.4 (3) Å³
M_r = 931.80	Z = 1
Triclinic, P1	F(000) = 466
Hall symbol: -P 1	D_x = 1.950 Mg m⁻³
a = 8.1452 (16) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.6282 (19) Å	µ = 2.68 mm⁻¹
c = 11.736 (2) Å	T = 293 K
α = 105.69 (3)°	Block, light-brown
β = 98.02 (3)°	0.15 × 0.14 × 0.08 mm
γ = 111.68 (3)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	3105 independent reflections
Radiation source: fine-focus sealed tube	2607 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.024
φ and ω scans	θ_max = 26.0°, θ_min = 1.9°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −10→9
T_min = 0.690, T_max = 0.814	k = −10→11
11276 measured reflections	l = −13→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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.071	H-atom parameters constrained
S = 1.02	w = 1/[σ²(F_o²) + (0.0395P)² + 0.3626P] where P = (F_o² + 2F_c²)/3
3105 reflections	(Δ/σ)_max = 0.001
250 parameters	Δρ_max = 0.49 e Å⁻³
0 restraints	Δρ_min = −0.40 e Å⁻³

Crystal data top

[Fe₂Sr(C₇H₃O₄)₄(H₂O)₂]·2H₂O	γ = 111.68 (3)°
M_r = 931.80	V = 793.4 (3) Å³
Triclinic, P1	Z = 1
a = 8.1452 (16) Å	Mo Kα radiation
b = 9.6282 (19) Å	µ = 2.68 mm⁻¹
c = 11.736 (2) Å	T = 293 K
α = 105.69 (3)°	0.15 × 0.14 × 0.08 mm
β = 98.02 (3)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	3105 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2607 reflections with I > 2σ(I)
T_min = 0.690, T_max = 0.814	R_int = 0.024
11276 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.028	0 restraints
wR(F²) = 0.071	H-atom parameters constrained
S = 1.02	Δρ_max = 0.49 e Å⁻³
3105 reflections	Δρ_min = −0.40 e Å⁻³
250 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
Sr1	1.0000	1.0000	0.0000	0.02299 (11)
Fe1	1.53110 (4)	1.22869 (4)	0.76823 (3)	0.01849 (11)
O5	1.3100 (2)	1.04567 (19)	0.65193 (14)	0.0239 (4)
O2	0.7297 (2)	0.44673 (19)	−0.14731 (15)	0.0232 (4)
O4	0.5482 (2)	0.8478 (2)	0.10123 (15)	0.0279 (4)
O8	1.2881 (2)	0.8582 (2)	0.22875 (15)	0.0265 (4)
O7	1.1399 (2)	1.0079 (2)	0.21988 (16)	0.0282 (4)
O3	0.6225 (3)	0.8977 (2)	−0.06144 (16)	0.0330 (5)
O1	0.8093 (2)	0.70237 (19)	−0.04546 (17)	0.0301 (4)
N1	0.3830 (3)	0.3732 (2)	−0.20190 (17)	0.0209 (4)
O6	1.1454 (2)	0.9051 (2)	0.45821 (16)	0.0341 (5)
N2	1.5520 (3)	1.2580 (2)	0.59304 (17)	0.0211 (4)
C14	1.2676 (3)	0.9857 (3)	0.2677 (2)	0.0215 (5)
C8	1.4190 (3)	1.1348 (3)	0.4975 (2)	0.0194 (5)
C13	1.2782 (3)	1.0171 (3)	0.5355 (2)	0.0215 (5)
C9	1.4154 (3)	1.1213 (3)	0.3770 (2)	0.0212 (5)
O9	0.8715 (3)	1.1438 (2)	0.16180 (18)	0.0414 (5)
C6	0.6935 (3)	0.5666 (3)	−0.1051 (2)	0.0205 (5)
C2	0.4184 (3)	0.6334 (3)	−0.0895 (2)	0.0209 (5)
C1	0.4910 (3)	0.5274 (3)	−0.1329 (2)	0.0189 (5)
C3	0.2291 (4)	0.5775 (3)	−0.1174 (2)	0.0290 (6)
H3	0.1759	0.6453	−0.0872	0.035*
C7	0.5396 (3)	0.8057 (3)	−0.0129 (2)	0.0222 (5)
C4	0.1209 (4)	0.4211 (3)	−0.1901 (3)	0.0327 (6)
H4	−0.0061	0.3831	−0.2119	0.039*
C12	1.6822 (4)	1.3723 (3)	0.5706 (2)	0.0309 (6)
H12	1.7726	1.4577	0.6364	0.037*
C5	0.2012 (3)	0.3215 (3)	−0.2305 (2)	0.0282 (6)
H5	0.1273	0.2154	−0.2788	0.034*
C11	1.6864 (4)	1.3673 (3)	0.4528 (3)	0.0397 (8)
H11	1.7783	1.4484	0.4392	0.048*
C10	1.5528 (4)	1.2407 (3)	0.3554 (2)	0.0346 (7)
H10	1.5547	1.2352	0.2753	0.042*
O10	0.0825 (3)	0.2537 (3)	0.4079 (2)	0.0533 (6)
H9A	0.7666	1.0764	0.1578	0.080*
H10A	0.0096	0.2178	0.4490	0.080*
H9B	0.9189	1.1872	0.2397	0.080*
H10B	0.1150	0.1792	0.3818	0.080*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sr1	0.02621 (18)	0.01633 (17)	0.02160 (18)	0.00651 (13)	0.00160 (14)	0.00547 (13)
Fe1	0.02082 (19)	0.01568 (18)	0.01497 (18)	0.00613 (14)	0.00358 (14)	0.00233 (13)
O5	0.0257 (9)	0.0208 (9)	0.0169 (9)	0.0032 (7)	0.0047 (7)	0.0039 (7)
O2	0.0201 (8)	0.0190 (9)	0.0249 (9)	0.0076 (7)	0.0038 (7)	0.0016 (7)
O4	0.0405 (11)	0.0243 (9)	0.0177 (9)	0.0117 (8)	0.0112 (8)	0.0070 (7)
O8	0.0269 (9)	0.0234 (9)	0.0267 (9)	0.0137 (8)	0.0043 (8)	0.0020 (7)
O7	0.0286 (10)	0.0335 (10)	0.0244 (9)	0.0176 (8)	0.0025 (8)	0.0092 (8)
O3	0.0484 (12)	0.0229 (9)	0.0265 (10)	0.0112 (9)	0.0127 (9)	0.0111 (8)
O1	0.0240 (9)	0.0176 (9)	0.0370 (11)	0.0041 (7)	0.0019 (8)	0.0021 (8)
N1	0.0203 (10)	0.0203 (10)	0.0185 (10)	0.0072 (8)	0.0026 (8)	0.0049 (8)
O6	0.0265 (10)	0.0332 (10)	0.0220 (9)	−0.0026 (8)	0.0010 (8)	0.0035 (8)
N2	0.0237 (10)	0.0188 (10)	0.0175 (10)	0.0077 (8)	0.0038 (8)	0.0042 (8)
C14	0.0254 (13)	0.0252 (13)	0.0136 (11)	0.0098 (11)	0.0068 (10)	0.0070 (10)
C8	0.0221 (12)	0.0176 (12)	0.0185 (12)	0.0113 (10)	0.0034 (10)	0.0034 (9)
C13	0.0232 (12)	0.0212 (12)	0.0182 (12)	0.0106 (10)	0.0039 (10)	0.0032 (10)
C9	0.0249 (13)	0.0193 (12)	0.0192 (12)	0.0101 (10)	0.0050 (10)	0.0056 (10)
O9	0.0395 (11)	0.0377 (11)	0.0457 (12)	0.0164 (9)	0.0126 (10)	0.0122 (9)
C6	0.0251 (12)	0.0194 (12)	0.0160 (12)	0.0087 (10)	0.0052 (10)	0.0060 (10)
C2	0.0279 (13)	0.0228 (12)	0.0153 (12)	0.0120 (11)	0.0064 (10)	0.0099 (10)
C1	0.0241 (12)	0.0177 (12)	0.0149 (12)	0.0084 (10)	0.0050 (10)	0.0065 (9)
C3	0.0327 (15)	0.0299 (14)	0.0313 (15)	0.0194 (12)	0.0090 (12)	0.0124 (12)
C7	0.0285 (13)	0.0216 (12)	0.0232 (13)	0.0152 (11)	0.0076 (11)	0.0108 (10)
C4	0.0194 (13)	0.0345 (15)	0.0436 (17)	0.0117 (12)	0.0048 (12)	0.0143 (13)
C12	0.0317 (14)	0.0250 (14)	0.0232 (13)	0.0026 (11)	0.0035 (11)	0.0046 (11)
C5	0.0220 (13)	0.0269 (14)	0.0279 (14)	0.0067 (11)	0.0013 (11)	0.0059 (11)
C11	0.0442 (17)	0.0304 (15)	0.0303 (15)	−0.0012 (13)	0.0091 (13)	0.0142 (12)
C10	0.0471 (17)	0.0302 (15)	0.0195 (13)	0.0086 (13)	0.0083 (12)	0.0096 (11)
O10	0.0528 (14)	0.0375 (12)	0.0625 (15)	0.0125 (10)	0.0235 (12)	0.0123 (11)

Geometric parameters (Å, º) top

Sr1—O1ⁱ	2.5617 (19)	N1—Fe1^v	2.146 (2)
Sr1—O1	2.5617 (19)	O6—C13	1.221 (3)
Sr1—O9ⁱ	2.612 (2)	N2—C12	1.333 (3)
Sr1—O9	2.612 (2)	N2—C8	1.353 (3)
Sr1—O7ⁱ	2.6404 (19)	C14—C9	1.517 (3)
Sr1—O7	2.6405 (19)	C8—C9	1.380 (3)
Sr1—O3	2.776 (2)	C8—C13	1.501 (3)
Sr1—O3ⁱ	2.776 (2)	C9—C10	1.387 (4)
Fe1—O8ⁱⁱ	1.9448 (18)	O9—H9A	0.8469
Fe1—O4ⁱⁱⁱ	1.9602 (18)	O9—H9B	0.8577
Fe1—O5	1.970 (2)	C6—C1	1.514 (3)
Fe1—O2^iv	1.9810 (19)	C2—C1	1.378 (3)
Fe1—N1^iv	2.146 (2)	C2—C3	1.388 (4)
Fe1—N2	2.171 (2)	C2—C7	1.507 (3)
O5—C13	1.287 (3)	C3—C4	1.374 (4)
O2—C6	1.283 (3)	C3—H3	0.9300
O2—Fe1^v	1.9810 (19)	C4—C5	1.370 (4)
O4—C7	1.273 (3)	C4—H4	0.9300
O4—Fe1ⁱⁱⁱ	1.9602 (18)	C12—C11	1.376 (4)
O8—C14	1.270 (3)	C12—H12	0.9300
O8—Fe1ⁱⁱ	1.9449 (18)	C5—H5	0.9300
O7—C14	1.229 (3)	C11—C10	1.377 (4)
O3—C7	1.226 (3)	C11—H11	0.9300
O1—C6	1.224 (3)	C10—H10	0.9300
N1—C5	1.334 (3)	O10—H10A	0.8500
N1—C1	1.349 (3)	O10—H10B	0.8500

O1ⁱ—Sr1—O1	180.00 (4)	C5—N1—Fe1^v	126.54 (17)
O1ⁱ—Sr1—O9ⁱ	104.40 (7)	C1—N1—Fe1^v	113.32 (16)
O1—Sr1—O9ⁱ	75.60 (7)	C12—N2—C8	119.2 (2)
O1ⁱ—Sr1—O9	75.60 (7)	C12—N2—Fe1	128.33 (17)
O1—Sr1—O9	104.40 (7)	C8—N2—Fe1	112.33 (16)
O9ⁱ—Sr1—O9	180.00 (7)	O7—C14—O8	124.2 (2)
O1ⁱ—Sr1—O7ⁱ	85.42 (7)	O7—C14—C9	118.2 (2)
O1—Sr1—O7ⁱ	94.58 (7)	O8—C14—C9	117.5 (2)
O9ⁱ—Sr1—O7ⁱ	70.26 (6)	N2—C8—C9	122.2 (2)
O9—Sr1—O7ⁱ	109.74 (6)	N2—C8—C13	113.8 (2)
O1ⁱ—Sr1—O7	94.58 (7)	C9—C8—C13	124.0 (2)
O1—Sr1—O7	85.42 (7)	O6—C13—O5	124.9 (2)
O9ⁱ—Sr1—O7	109.74 (6)	O6—C13—C8	120.2 (2)
O9—Sr1—O7	70.26 (6)	O5—C13—C8	114.9 (2)
O7ⁱ—Sr1—O7	180.0	C8—C9—C10	117.8 (2)
O1ⁱ—Sr1—O3	115.66 (6)	C8—C9—C14	123.6 (2)
O1—Sr1—O3	64.34 (6)	C10—C9—C14	118.6 (2)
O9ⁱ—Sr1—O3	115.86 (7)	Sr1—O9—H9A	107.4
O9—Sr1—O3	64.14 (7)	Sr1—O9—H9B	127.1
O7ⁱ—Sr1—O3	65.72 (6)	H9A—O9—H9B	101.2
O7—Sr1—O3	114.28 (6)	O1—C6—O2	124.4 (2)
O1ⁱ—Sr1—O3ⁱ	64.34 (6)	O1—C6—C1	121.1 (2)
O1—Sr1—O3ⁱ	115.66 (6)	O2—C6—C1	114.44 (19)
O9ⁱ—Sr1—O3ⁱ	64.14 (7)	C1—C2—C3	118.3 (2)
O9—Sr1—O3ⁱ	115.86 (7)	C1—C2—C7	121.5 (2)
O7ⁱ—Sr1—O3ⁱ	114.28 (6)	C3—C2—C7	120.2 (2)
O7—Sr1—O3ⁱ	65.72 (6)	N1—C1—C2	121.7 (2)
O3—Sr1—O3ⁱ	180.0	N1—C1—C6	113.3 (2)
O8ⁱⁱ—Fe1—O4ⁱⁱⁱ	90.57 (8)	C2—C1—C6	124.9 (2)
O8ⁱⁱ—Fe1—O5	102.46 (8)	C4—C3—C2	119.3 (2)
O4ⁱⁱⁱ—Fe1—O5	87.33 (8)	C4—C3—H3	120.3
O8ⁱⁱ—Fe1—O2^iv	89.83 (8)	C2—C3—H3	120.3
O4ⁱⁱⁱ—Fe1—O2^iv	105.84 (8)	O3—C7—O4	123.4 (2)
O5—Fe1—O2^iv	162.02 (7)	O3—C7—C2	119.9 (2)
O8ⁱⁱ—Fe1—N1^iv	166.42 (7)	O4—C7—C2	116.7 (2)
O4ⁱⁱⁱ—Fe1—N1^iv	88.93 (8)	C5—C4—C3	119.6 (2)
O5—Fe1—N1^iv	91.07 (8)	C5—C4—H4	120.2
O2^iv—Fe1—N1^iv	77.28 (7)	C3—C4—H4	120.2
O8ⁱⁱ—Fe1—N2	92.77 (8)	N2—C12—C11	121.8 (2)
O4ⁱⁱⁱ—Fe1—N2	164.61 (8)	N2—C12—H12	119.1
O5—Fe1—N2	77.28 (8)	C11—C12—H12	119.1
O2^iv—Fe1—N2	89.19 (8)	N1—C5—C4	121.5 (2)
N1^iv—Fe1—N2	91.28 (8)	N1—C5—H5	119.3
C13—O5—Fe1	121.39 (15)	C4—C5—H5	119.3
C6—O2—Fe1^v	121.12 (15)	C12—C11—C10	119.1 (3)
C7—O4—Fe1ⁱⁱⁱ	144.33 (16)	C12—C11—H11	120.4
C14—O8—Fe1ⁱⁱ	143.19 (16)	C10—C11—H11	120.4
C14—O7—Sr1	136.49 (16)	C11—C10—C9	119.9 (3)
C7—O3—Sr1	115.05 (17)	C11—C10—H10	120.0
C6—O1—Sr1	156.83 (17)	C9—C10—H10	120.0
C5—N1—C1	119.5 (2)	H10A—O10—H10B	102.7

O8ⁱⁱ—Fe1—O5—C13	−86.54 (19)	C9—C8—C13—O6	−3.8 (4)
O4ⁱⁱⁱ—Fe1—O5—C13	−176.54 (19)	N2—C8—C13—O5	−3.6 (3)
O2^iv—Fe1—O5—C13	45.6 (3)	C9—C8—C13—O5	176.5 (2)
N1^iv—Fe1—O5—C13	94.58 (19)	N2—C8—C9—C10	−1.0 (4)
N2—Fe1—O5—C13	3.51 (18)	C13—C8—C9—C10	178.8 (2)
O1ⁱ—Sr1—O7—C14	−92.6 (2)	N2—C8—C9—C14	−179.5 (2)
O1—Sr1—O7—C14	87.4 (2)	C13—C8—C9—C14	0.3 (4)
O9ⁱ—Sr1—O7—C14	14.5 (2)	O7—C14—C9—C8	97.4 (3)
O9—Sr1—O7—C14	−165.5 (2)	O8—C14—C9—C8	−85.3 (3)
O7ⁱ—Sr1—O7—C14	36 (12)	O7—C14—C9—C10	−81.1 (3)
O3—Sr1—O7—C14	146.6 (2)	O8—C14—C9—C10	96.2 (3)
O3ⁱ—Sr1—O7—C14	−33.4 (2)	Sr1—O1—C6—O2	113.1 (4)
O1ⁱ—Sr1—O3—C7	−136.83 (16)	Sr1—O1—C6—C1	−68.1 (5)
O1—Sr1—O3—C7	43.17 (16)	Fe1^v—O2—C6—O1	175.19 (18)
O9ⁱ—Sr1—O3—C7	100.53 (17)	Fe1^v—O2—C6—C1	−3.7 (3)
O9—Sr1—O3—C7	−79.47 (17)	C5—N1—C1—C2	0.8 (3)
O7ⁱ—Sr1—O3—C7	151.45 (18)	Fe1^v—N1—C1—C2	−170.73 (18)
O7—Sr1—O3—C7	−28.55 (18)	C5—N1—C1—C6	178.3 (2)
O3ⁱ—Sr1—O3—C7	70 (100)	Fe1^v—N1—C1—C6	6.7 (2)
O1ⁱ—Sr1—O1—C6	124 (14)	C3—C2—C1—N1	0.6 (4)
O9ⁱ—Sr1—O1—C6	−72.6 (4)	C7—C2—C1—N1	−179.8 (2)
O9—Sr1—O1—C6	107.4 (4)	C3—C2—C1—C6	−176.5 (2)
O7ⁱ—Sr1—O1—C6	−4.3 (4)	C7—C2—C1—C6	3.1 (4)
O7—Sr1—O1—C6	175.7 (4)	O1—C6—C1—N1	178.6 (2)
O3—Sr1—O1—C6	56.0 (4)	O2—C6—C1—N1	−2.5 (3)
O3ⁱ—Sr1—O1—C6	−124.0 (4)	O1—C6—C1—C2	−4.1 (4)
O8ⁱⁱ—Fe1—N2—C12	−78.2 (2)	O2—C6—C1—C2	174.9 (2)
O4ⁱⁱⁱ—Fe1—N2—C12	179.5 (3)	C1—C2—C3—C4	−2.1 (4)
O5—Fe1—N2—C12	179.7 (2)	C7—C2—C3—C4	178.3 (2)
O2^iv—Fe1—N2—C12	11.6 (2)	Sr1—O3—C7—O4	70.3 (3)
N1^iv—Fe1—N2—C12	88.9 (2)	Sr1—O3—C7—C2	−110.4 (2)
O8ⁱⁱ—Fe1—N2—C8	96.90 (17)	Fe1ⁱⁱⁱ—O4—C7—O3	−176.5 (2)
O4ⁱⁱⁱ—Fe1—N2—C8	−5.4 (4)	Fe1ⁱⁱⁱ—O4—C7—C2	4.1 (4)
O5—Fe1—N2—C8	−5.25 (16)	C1—C2—C7—O3	73.9 (3)
O2^iv—Fe1—N2—C8	−173.32 (17)	C3—C2—C7—O3	−106.5 (3)
N1^iv—Fe1—N2—C8	−96.07 (17)	C1—C2—C7—O4	−106.7 (3)
Sr1—O7—C14—O8	−56.2 (4)	C3—C2—C7—O4	72.9 (3)
Sr1—O7—C14—C9	120.9 (2)	C2—C3—C4—C5	2.2 (4)
Fe1ⁱⁱ—O8—C14—O7	158.5 (2)	C8—N2—C12—C11	−0.9 (4)
Fe1ⁱⁱ—O8—C14—C9	−18.6 (4)	Fe1—N2—C12—C11	173.8 (2)
C12—N2—C8—C9	1.5 (4)	C1—N1—C5—C4	−0.7 (4)
Fe1—N2—C8—C9	−174.06 (19)	Fe1^v—N1—C5—C4	169.6 (2)
C12—N2—C8—C13	−178.3 (2)	C3—C4—C5—N1	−0.8 (4)
Fe1—N2—C8—C13	6.1 (2)	N2—C12—C11—C10	−0.1 (5)
Fe1—O5—C13—O6	179.1 (2)	C12—C11—C10—C9	0.7 (5)
Fe1—O5—C13—C8	−1.2 (3)	C8—C9—C10—C11	−0.1 (4)
N2—C8—C13—O6	176.0 (2)	C14—C9—C10—C11	178.5 (3)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O9—H9A···O4	0.85	2.11	2.898 (3)	156
O10—H10A···O6^vi	0.85	2.04	2.875 (3)	168
O9—H9B···O10^vii	0.86	2.01	2.835 (3)	161
O10—H10B···O7^viii	0.85	2.24	2.995 (3)	147
C3—H3···O9^ix	0.93	2.55	3.225 (3)	130
C4—H4···O2^x	0.93	2.60	3.380 (3)	142
C4—H4···O8^xi	0.93	2.53	3.292 (3)	140
C5—H5···O6^xi	0.93	2.49	3.172 (3)	131
C10—H10···O3ⁱ	0.93	2.43	3.233 (3)	145

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

Experimental details

Crystal data
Chemical formula	[Fe₂Sr(C₇H₃O₄)₄(H₂O)₂]·2H₂O
M_r	931.80
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	8.1452 (16), 9.6282 (19), 11.736 (2)
α, β, γ (°)	105.69 (3), 98.02 (3), 111.68 (3)
V (Å³)	793.4 (3)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	2.68
Crystal size (mm)	0.15 × 0.14 × 0.08

Data collection
Diffractometer	Bruker APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.690, 0.814
No. of measured, independent and observed [I > 2σ(I)] reflections	11276, 3105, 2607
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.071, 1.02
No. of reflections	3105
No. of parameters	250
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.49, −0.40

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999), SHELXTL (Sheldrick, 2008).

Selected geometric parameters (Å, º) top

Sr1—O1	2.5617 (19)	Fe1—O4ⁱⁱⁱ	1.9602 (18)
Sr1—O9	2.612 (2)	Fe1—O5	1.970 (2)
Sr1—O7ⁱ	2.6404 (19)	Fe1—O2^iv	1.9810 (19)
Sr1—O7	2.6405 (19)	Fe1—N1^iv	2.146 (2)
Sr1—O3	2.776 (2)	Fe1—N2	2.171 (2)
Fe1—O8ⁱⁱ	1.9448 (18)

O1ⁱ—Sr1—O1	180.00 (4)	O9—Sr1—O3ⁱ	115.86 (7)
O1ⁱ—Sr1—O9ⁱ	104.40 (7)	O7ⁱ—Sr1—O3ⁱ	114.28 (6)
O1—Sr1—O9ⁱ	75.60 (7)	O7—Sr1—O3ⁱ	65.72 (6)
O1—Sr1—O9	104.40 (7)	O3—Sr1—O3ⁱ	180.0
O9ⁱ—Sr1—O9	180.00 (7)	O8ⁱⁱ—Fe1—O4ⁱⁱⁱ	90.57 (8)
O1ⁱ—Sr1—O7ⁱ	85.42 (7)	O8ⁱⁱ—Fe1—O5	102.46 (8)
O1—Sr1—O7ⁱ	94.58 (7)	O4ⁱⁱⁱ—Fe1—O5	87.33 (8)
O9ⁱ—Sr1—O7ⁱ	70.26 (6)	O8ⁱⁱ—Fe1—O2^iv	89.83 (8)
O9—Sr1—O7ⁱ	109.74 (6)	O4ⁱⁱⁱ—Fe1—O2^iv	105.84 (8)
O1ⁱ—Sr1—O7	94.58 (7)	O5—Fe1—O2^iv	162.02 (7)
O1—Sr1—O7	85.42 (7)	O8ⁱⁱ—Fe1—N1^iv	166.42 (7)
O9ⁱ—Sr1—O7	109.74 (6)	O4ⁱⁱⁱ—Fe1—N1^iv	88.93 (8)
O9—Sr1—O7	70.26 (6)	O5—Fe1—N1^iv	91.07 (8)
O7ⁱ—Sr1—O7	180.0	O2^iv—Fe1—N1^iv	77.28 (7)
O1ⁱ—Sr1—O3	115.66 (6)	O8ⁱⁱ—Fe1—N2	92.77 (8)
O1—Sr1—O3	64.34 (6)	O4ⁱⁱⁱ—Fe1—N2	164.61 (8)
O9—Sr1—O3	64.14 (7)	O5—Fe1—N2	77.28 (8)
O7—Sr1—O3	114.28 (6)	O2^iv—Fe1—N2	89.19 (8)
O9ⁱ—Sr1—O3ⁱ	64.14 (7)	N1^iv—Fe1—N2	91.28 (8)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O9—H9A···O4	0.85	2.11	2.898 (3)	156
O10—H10A···O6^v	0.85	2.04	2.875 (3)	168
O9—H9B···O10^vi	0.86	2.01	2.835 (3)	161
O10—H10B···O7^vii	0.85	2.24	2.995 (3)	147
C3—H3···O9^viii	0.93	2.55	3.225 (3)	130
C4—H4···O2^ix	0.93	2.60	3.380 (3)	142
C4—H4···O8^x	0.93	2.53	3.292 (3)	140
C5—H5···O6^x	0.93	2.49	3.172 (3)	131
C10—H10···O3ⁱ	0.93	2.43	3.233 (3)	145

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

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The first three-dimensional FeIII-SrII heterometallic coordination polymer: poly[[di­aqua­tetra­kis­(3-pyridine-2,3-di­carboxyl­ato)diiron(III)strontium(II)] dihydrate]

Supporting information

The first three-dimensional Fe^III-Sr^II heterometallic coordination polymer: poly[[diaquatetrakis(₃-pyridine-2,3-dicarboxylato)diiron(III)strontium(II)] dihydrate]