Redetermination of poly[μ₂-aqua-diaquabis­(μ₃-pyridine-2,6-dicarboxyl­ato)manganese(II)]

The title compound, [Mn₂(C₇H₃NO₄)₂(H₂O)₃]_n, has been synthesized under hydro­thermal conditions. In the complex, the Mn atom is seven-coordinated by three symmetry-equivalent pyridine-2,6-dicarboxyl­ate ligands and a water mol­ecule in a penta­gonal–bipyramidal coordination environment. A crystallographic twofold rotation axis passes through the bridging water molecule and between adjacent pairs of Mn atoms.

Key indicators

• Single-crystal X-ray study
• T = 153 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.032
• wR factor = 0.075
• Data-to-parameter ratio = 11.5

checkCIF/PLATON results

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Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.25
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.16 Ratio

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Mn1         (2)       2.03

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
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S1. Comment

The chemistry of metal complexes containing paramagnetic metal ions and exhibiting extended structures is at the forefront of modern research, due to these compounds' potential applications in molecular magnetism (Field et al., 2006; Rueff et al., 2002; Zeng et al., 2005). The most useful strategy by which to construct such extended one dimensional systems is to employ appropriate bridging ligands, carboxylate for example, capable of binding metal centers through direct bond formation, promoting magnetic interactions. Pyridine-2,6-dicarboxylate (2,6-pdc^2-), which has been used as a ligand in homoleptic coordination polymers and coordination complexes, is a suitable building block for two-dimensional arrays (Zhao et al., 2003; Gao et al., 2006). There are a few examples of manganese complexes of 2,6-pdc (Ma, Chen, Chen et al., 2003; Ma, Chen, Liu et al., 2003; Okabe & Oya, 2000; Wei et al., 2005), although many crystal structures of complexes of 2,6-pdc with divalent ions such as Co^II, Ni^II and Cu^II (Ghosh et al., 2004; Ghosh et al., 2005) have been determined. The reactants we have used are different from those reported previously in the literature in an attempt to obtain a compound analogous to the title complex (I) (Wei et al., 2005). Its crystal structure is presented here. It should be noted that, compound (I) crystallizes in the monoclinic space group C2/c, while the P-1 space group was previously reported (Wei et al., 2005).

The hydrothermal reaction of Mn(NO₃)₂, 2,6-pdc and 5-bromo-2,4'-bipyridine (5-Br-2,4'-bpy) did not lead to the expected manganese system with coordinated bpy ligands, but to the unexpected formation of (I). Attempts were made to obtain compound (I) under the same conditions in the absence of bpy ligand. The collected crystals were in poor quality and not suitable for X-ray crystallography.

The crystallographically independent unit and atomic numbering of (I) are shown in Fig. 1, and selected bond distances and angles are given in Table 1. A half of (I) is crystallographically independent with a 2-fold axis through O1w. The asymmetric unit consists of one (O2w) and half water (half O1w), one Mn atom and one 2,6-pdc group. The coordination around the Mn atom is pentagonal-bipyramidal. All water molecules are coordinated with metal atoms: O1w atom as a bridge is connected to two neighbouring Mn atoms, while Ow2 atom is coordinated with Mn atom as terminal ligand. The equatorial belt is formed by one N atom (N1) and four O atoms (O2, O2ⁱⁱ, O3, O1w), and the axial positions are occupied by O3 atom and O2w atom [symmetry codes: (ii)-x,-y, -z + 2]. The Mn—O bond lengths fall in the ranges 2.122 (2)–2.4944 (16) Å, and Mn—N bond length is 2.292 (2) Å. These values are consistent with the corresponding distances in the literature (Wei et al., 2005).

In complex (I), the Mn atom is coordinated by four different O atoms of three trans 2,6-pdc ligands, so the complex is extended along c-axis, resulting in the formation of one-dimensional supramolecular chains (Fig.2). The water O1w is connected to the atom O1ⁱ by O1w—H1···O1ⁱ within one-dimensional chain[symmetrycodes: (i)-x,y,-z + 3/2]. The water O2w is hydrogen bonded to O4ⁱⁱⁱ and O^iv of two neighboring chains through O2w—H2b···O4ⁱⁱⁱ and O2w—H2a···O4^iv [symmetry codes: (iii)-x + 1/2,y - 1/2, -z + 3/2; (iv)x,-y,z + 1/2], forming cyclic hydrogen bonded net. Thus, the complex is further assembled into two-dimensional layer by hydrogen-bonding interaction along b-axis. Adjacent sheets cross each other to give a square hydrogen bonded network, in which are filled 2,6-pdc ligand from neighboring chains (Fig.3). The hydrogen bonding interaction plays an important role in stabilizing the crystal structure.

Related literature

For related literature, see: Field et al. (2006); Gao et al. (2006); Ghosh et al. (2004, 2005); Ma, Chen, Chen et al. (2003); Ma, Chen, Liu et al. (2003); Okabe & Oya (2000); Rueff et al. (2002); Wei et al. (2005); Zeng et al. (2005); Zhao et al. (2003).

S2. Experimental

In a typical experiment, H2pdc (0.042 g, 0.25 mmol) in an aqueous solution (6 ml) of NaOH (0.040 g, 1 mmol) was mixed with 5-Br-2,4'-bpy (0.0235 g, 0.1 mmol) in EtOH (2 ml); the mixture was then added to an aqueous solution (2 ml) of 50% Mn(NO₃)₂. The new mixture was placed in a 15-ml Teflon-lined autoclave and heated at 423 K for 4 d. The autoclave was then cooled to temperature at a rate of 4 K h^-1. Brown block crystals of (I) deposited on the wall of container were collected and air-dried.

S3. Refinement

Hydrogen atoms bound to carbon were placed in calculated positions and refined using a riding model with an isotropic displacement parameter fixed at 1.2 times U_eq for the atom to which they are attached. Hydrogen atoms on the water molecule were found in electron-density difference Fourier maps at the stages of the refinement procedure and were refined freely.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Bruker 1998); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. Complex (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small of arbitrary radii. [Symmetry codes: (i)-x, y,-z + 3/2; (ii)-x,-y,-z + 2; (iii)-x + 1/2,y - 1/2, -z + 3/2.]
	Fig. 2. A perspective view of the hydrogen bonded layer of polymer chains. Hydrogen bonds are drawn as dashed lines. [Symmetry codes: (i)-x, y,-z + 3/2; (iii)-x + 1/2,y - 1/2,-z + 3/2; (iv)x,-y,z + 1/2.]
	Fig. 3. A view along the c axis of the network structure of complex (I). Hydrogen bonds are drawn as dashed lines.

Poly[µ₂-aqua-diaquabis(µ₃-pyridine-2,6-dicarboxylato)manganese(II)]

Crystal data

[Mn2(C7H3NO4)2(H2O)3]	F(000) = 992
Mr = 494.14	Dx = 1.955 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 4593 reflections
a = 13.1763 (13) Å	θ = 2.6–26.0°
b = 9.7513 (10) Å	µ = 1.57 mm^−1
c = 13.1510 (13) Å	T = 153 K
β = 96.427 (2)°	Block, brown
V = 1679.1 (3) Å^3	0.39 × 0.10 × 0.06 mm
Z = 4

Data collection

Siemens SMART CCD area-detector diffractometer	1649 independent reflections
Radiation source: fine-focus sealed tube	1456 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.028
Detector resolution: 9 pixels mm^-1	θmax = 26.0°, θmin = 2.6°
ω scans	h = −16→16
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	k = −12→11
Tmin = 0.836, Tmax = 0.904	l = −10→16
4593 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.075	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0401P)^2 + 1.0348P] where P = (Fo^2 + 2Fc^2)/3
1649 reflections	(Δ/σ)max = 0.001
144 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.31 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Mn1	0.04668 (3)	0.01957 (4)	0.87334 (3)	0.01474 (14)
O3	0.09871 (12)	0.08881 (16)	0.70408 (12)	0.0177 (4)
O4	0.16289 (14)	0.25500 (19)	0.61332 (13)	0.0257 (4)
O2W	0.17185 (16)	−0.1023 (2)	0.93574 (16)	0.0283 (5)
O1	0.10025 (16)	0.29078 (19)	1.13305 (14)	0.0326 (5)
O2	0.04275 (13)	0.11744 (16)	1.02950 (13)	0.0179 (4)
O1W	0.0000	−0.1383 (2)	0.7500	0.0195 (5)
N1	0.11101 (14)	0.2377 (2)	0.87038 (14)	0.0163 (4)
C1	0.08209 (18)	0.2351 (3)	1.04755 (18)	0.0197 (5)
C7	0.13324 (17)	0.2082 (3)	0.69342 (18)	0.0174 (5)
C6	0.13422 (18)	0.3006 (2)	0.78526 (18)	0.0186 (5)
C5	0.1509 (2)	0.4409 (3)	0.7806 (2)	0.0253 (6)
H3	0.1671	0.4817	0.7205	0.030*
C2	0.10824 (19)	0.3133 (2)	0.95497 (19)	0.0201 (5)
C3	0.1234 (2)	0.4546 (3)	0.9564 (2)	0.0274 (6)
H5	0.1204	0.5047	1.0162	0.033*
C4	0.1429 (2)	0.5185 (3)	0.8670 (2)	0.0299 (6)
H4	0.1506	0.6132	0.8650	0.036*
H2A	0.217 (3)	−0.132 (3)	0.911 (3)	0.041 (10)*
H2B	0.166 (3)	−0.141 (3)	0.991 (3)	0.049 (11)*
H1	−0.039 (3)	−0.196 (3)	0.783 (3)	0.053 (11)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mn1	0.0185 (2)	0.0145 (2)	0.0116 (2)	0.00089 (14)	0.00353 (14)	−0.00022 (14)
O3	0.0200 (8)	0.0171 (9)	0.0167 (9)	−0.0033 (7)	0.0049 (7)	−0.0005 (7)
O4	0.0358 (11)	0.0287 (10)	0.0141 (9)	−0.0114 (8)	0.0102 (8)	−0.0016 (8)
O2W	0.0259 (10)	0.0392 (12)	0.0217 (11)	0.0160 (9)	0.0111 (9)	0.0099 (9)
O1	0.0577 (13)	0.0272 (10)	0.0150 (10)	−0.0202 (9)	0.0129 (9)	−0.0067 (8)
O2	0.0265 (9)	0.0149 (8)	0.0132 (8)	−0.0039 (7)	0.0070 (7)	−0.0017 (7)
O1W	0.0294 (14)	0.0135 (12)	0.0172 (13)	0.000	0.0091 (11)	0.000
N1	0.0177 (10)	0.0201 (11)	0.0117 (10)	−0.0021 (8)	0.0043 (8)	0.0002 (8)
C1	0.0236 (13)	0.0206 (13)	0.0155 (13)	−0.0027 (10)	0.0050 (10)	−0.0003 (10)
C7	0.0147 (11)	0.0223 (13)	0.0154 (13)	−0.0016 (9)	0.0030 (10)	−0.0002 (10)
C6	0.0197 (12)	0.0223 (13)	0.0145 (13)	−0.0026 (10)	0.0047 (10)	0.0017 (10)
C5	0.0360 (15)	0.0229 (14)	0.0180 (14)	−0.0095 (11)	0.0070 (11)	0.0012 (11)
C2	0.0263 (13)	0.0184 (13)	0.0164 (13)	−0.0039 (10)	0.0059 (11)	−0.0010 (10)
C3	0.0388 (16)	0.0230 (14)	0.0219 (14)	−0.0096 (12)	0.0095 (12)	−0.0057 (11)
C4	0.0473 (17)	0.0185 (13)	0.0250 (15)	−0.0119 (12)	0.0093 (13)	−0.0001 (11)

Geometric parameters (Å, º)

Mn1—O2W	2.122 (2)	O2—Mn1^ii	2.2679 (16)
Mn1—O3^i	2.1738 (16)	O1W—Mn1^i	2.2707 (17)
Mn1—O2^ii	2.2679 (16)	O1W—H1	0.91 (3)
Mn1—O2	2.2704 (17)	N1—C2	1.338 (3)
Mn1—O1W	2.2707 (17)	N1—C6	1.341 (3)
Mn1—N1	2.292 (2)	C1—C2	1.509 (3)
Mn1—O3	2.4944 (16)	C7—C6	1.506 (3)
O3—C7	1.263 (3)	C6—C5	1.388 (3)
O3—Mn1^i	2.1738 (16)	C5—C4	1.379 (4)
O4—C7	1.250 (3)	C5—H3	0.9300
O2W—H2A	0.76 (4)	C2—C3	1.391 (3)
O2W—H2B	0.83 (4)	C3—C4	1.380 (4)
O1—C1	1.247 (3)	C3—H5	0.9300
O2—C1	1.271 (3)	C4—H4	0.9300
O2W—Mn1—O3^i	163.97 (7)	Mn1^ii—O2—Mn1	109.15 (7)
O2W—Mn1—O2^ii	83.25 (8)	Mn1—O1W—Mn1^i	94.63 (9)
O3^i—Mn1—O2^ii	87.74 (6)	Mn1—O1W—H1	101 (2)
O2W—Mn1—O2	88.91 (7)	Mn1^i—O1W—H1	130 (2)
O3^i—Mn1—O2	100.66 (6)	C2—N1—C6	118.1 (2)
O2^ii—Mn1—O2	70.85 (7)	C2—N1—Mn1	116.91 (15)
O2W—Mn1—O1W	91.91 (7)	C6—N1—Mn1	123.91 (16)
O3^i—Mn1—O1W	73.86 (6)	O1—C1—O2	126.5 (2)
O2^ii—Mn1—O1W	83.50 (5)	O1—C1—C2	118.0 (2)
O2—Mn1—O1W	154.07 (5)	O2—C1—C2	115.5 (2)
O2W—Mn1—N1	104.68 (8)	O4—C7—O3	125.5 (2)
O3^i—Mn1—N1	90.69 (7)	O4—C7—C6	118.8 (2)
O2^ii—Mn1—N1	140.61 (6)	O3—C7—C6	115.7 (2)
O2—Mn1—N1	70.80 (6)	N1—C6—C5	122.7 (2)
O1W—Mn1—N1	133.50 (6)	N1—C6—C7	114.4 (2)
O2W—Mn1—O3	102.56 (7)	C5—C6—C7	122.8 (2)
O3^i—Mn1—O3	79.27 (6)	C4—C5—C6	118.5 (2)
O2^ii—Mn1—O3	150.96 (6)	C4—C5—H3	120.8
O2—Mn1—O3	136.87 (6)	C6—C5—H3	120.8
O1W—Mn1—O3	68.01 (5)	N1—C2—C3	122.6 (2)
N1—Mn1—O3	66.08 (6)	N1—C2—C1	115.0 (2)
C7—O3—Mn1^i	122.94 (15)	C3—C2—C1	122.3 (2)
C7—O3—Mn1	119.13 (14)	C4—C3—C2	118.4 (2)
Mn1^i—O3—Mn1	91.04 (6)	C4—C3—H5	120.8
Mn1—O2W—H2A	131 (3)	C2—C3—H5	120.8
Mn1—O2W—H2B	116 (2)	C5—C4—C3	119.5 (3)
H2A—O2W—H2B	111 (3)	C5—C4—H4	120.2
C1—O2—Mn1^ii	130.81 (15)	C3—C4—H4	120.2
C1—O2—Mn1	119.90 (15)
O2W—Mn1—O3—C7	−102.13 (17)	O2W—Mn1—N1—C6	104.24 (19)
O3^i—Mn1—O3—C7	94.14 (15)	O3^i—Mn1—N1—C6	−71.14 (19)
O2^ii—Mn1—O3—C7	159.06 (16)	O2^ii—Mn1—N1—C6	−158.42 (16)
O2—Mn1—O3—C7	0.0 (2)	O2—Mn1—N1—C6	−172.2 (2)
O1W—Mn1—O3—C7	170.92 (17)	O1W—Mn1—N1—C6	−3.0 (2)
N1—Mn1—O3—C7	−1.45 (15)	O3—Mn1—N1—C6	6.79 (17)
O2W—Mn1—O3—Mn1^i	128.63 (7)	Mn1^ii—O2—C1—O1	17.4 (4)
O3^i—Mn1—O3—Mn1^i	−35.10 (8)	Mn1—O2—C1—O1	−167.5 (2)
O2^ii—Mn1—O3—Mn1^i	29.82 (14)	Mn1^ii—O2—C1—C2	−162.32 (16)
O2—Mn1—O3—Mn1^i	−129.28 (7)	Mn1—O2—C1—C2	12.9 (3)
O1W—Mn1—O3—Mn1^i	41.68 (5)	Mn1^i—O3—C7—O4	−68.1 (3)
N1—Mn1—O3—Mn1^i	−130.69 (8)	Mn1—O3—C7—O4	179.19 (18)
O2W—Mn1—O2—C1	100.62 (18)	Mn1^i—O3—C7—C6	109.6 (2)
O3^i—Mn1—O2—C1	−92.33 (18)	Mn1—O3—C7—C6	−3.1 (3)
O2^ii—Mn1—O2—C1	−176.1 (2)	C2—N1—C6—C5	−2.9 (4)
O1W—Mn1—O2—C1	−167.26 (16)	Mn1—N1—C6—C5	165.08 (19)
N1—Mn1—O2—C1	−5.35 (17)	C2—N1—C6—C7	−178.7 (2)
O3—Mn1—O2—C1	−6.7 (2)	Mn1—N1—C6—C7	−10.7 (3)
O2W—Mn1—O2—Mn1^ii	−83.24 (9)	O4—C7—C6—N1	−173.6 (2)
O3^i—Mn1—O2—Mn1^ii	83.81 (8)	O3—C7—C6—N1	8.5 (3)
O2^ii—Mn1—O2—Mn1^ii	0.0	O4—C7—C6—C5	10.6 (4)
O1W—Mn1—O2—Mn1^ii	8.89 (17)	O3—C7—C6—C5	−167.3 (2)
N1—Mn1—O2—Mn1^ii	170.80 (9)	N1—C6—C5—C4	−0.2 (4)
O3—Mn1—O2—Mn1^ii	169.44 (6)	C7—C6—C5—C4	175.3 (2)
O2W—Mn1—O1W—Mn1^i	−142.47 (6)	C6—N1—C2—C3	3.3 (4)
O3^i—Mn1—O1W—Mn1^i	45.02 (5)	Mn1—N1—C2—C3	−165.5 (2)
O2^ii—Mn1—O1W—Mn1^i	134.55 (5)	C6—N1—C2—C1	−179.7 (2)
O2—Mn1—O1W—Mn1^i	126.10 (13)	Mn1—N1—C2—C1	11.5 (3)
N1—Mn1—O1W—Mn1^i	−30.06 (7)	O1—C1—C2—N1	164.3 (2)
O3—Mn1—O1W—Mn1^i	−39.69 (4)	O2—C1—C2—N1	−16.0 (3)
O2W—Mn1—N1—C2	−87.65 (18)	O1—C1—C2—C3	−18.7 (4)
O3^i—Mn1—N1—C2	96.97 (17)	O2—C1—C2—C3	161.0 (2)
O2^ii—Mn1—N1—C2	9.7 (2)	N1—C2—C3—C4	−0.6 (4)
O2—Mn1—N1—C2	−4.08 (17)	C1—C2—C3—C4	−177.4 (3)
O1W—Mn1—N1—C2	165.13 (15)	C6—C5—C4—C3	3.0 (4)
O3—Mn1—N1—C2	174.90 (19)	C2—C3—C4—C5	−2.6 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2W—H2A···O4^iii	0.76 (4)	1.99 (4)	2.722 (3)	162 (3)
O2W—H2B···O4^iv	0.83 (4)	1.96 (4)	2.783 (3)	171 (3)
O1W—H1···O1^ii	0.91 (3)	1.71 (3)	2.603 (2)	169 (3)

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