Poly[diaqua­[[mu]-1,4-bis­(imidazol-1-yl­meth­yl)benzene-[kappa]²N³:N^3']([mu]-trans-cyclo­hexane-1,4-carboxyl­ato-[kappa]²O¹:O⁴)manganese(II)]: a three-dimensional hydrogen-bonding [alpha]-polonium net

In the title coordination compound, [Mn(C₈H₁₀O₄)(C₁₄H₁₄N₄)(H₂O)₂]_n, each Mn^II centre occupies an inversion centre. The 1,4-bis­(imidazol-1-ylmethyl)benzene (1,4-bix) ligand and the trans-cyclo­hexane-1,4-dicarboxyl­ate dianion (chdc) both function in bridging modes, linking adjacent Mn^II centres into a two-dimensional four-connected (4,4) network. These two-dimensional layers are stacked in a parallel mode. Hydrogen bonds between water mol­ecules and carboxyl­ate O atoms link neighbouring (4,4) networks, yielding a three-dimensional [alpha]-polonium net.

S1. Comment

The design and synthesis of metal–organic coordination polymers are of great interest, not only because of their wide range of potential applications in nonlinear optics, catalysis, gas absorption, luminescence, magnetism and medicine, but also because of their intriguing variety of architectures and topologies (Eddaoudi et al., 2001; Noveron et al., 2002; Batten & Robson, 1998). Generally, the topology of a coordination polymer can often be controlled and modified by selecting the coordination geometry preferred by the metal ion and the chemical structure of the organic ligand chosen (Carlucci et al., 2003). The use of aromatic carboxylic acids in the syntheses of coordination polymers has aroused enormous interest due to their versatile coordination modes and variety of structural conformations (Wang et al., 2005). Aromatic multicarboxylate ligands, such as 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid and 1,4-benzenedicarboxylic acid, are widely used to construct coordination polymers with interesting properties (Tao et al., 2002). However, flexible dicarboxylate ligands are rarely used in the construction of coordination polymers. The cyclohexane-1,4-dicarboxylate dianion (chdc) is an example of a flexible dianion because of the presence of cis and trans configurations. On the other hand, 4,4'-bipyridine is a rigid rod-like spacer, well known in the construction of metal–organic polymers, and it has adopted numerous interesting supramolecular architectures (Batten, 2001). However, flexible N-donor ligands such as 1,4-bis(imidazol-1-ylmethyl)benzene (1,4-bix) have not been so well explored to date (Wang et al., 2006). In this work, 1,4-bix assembles with manganese cyclohexane-1,4-dicarboxylate to furnish the title complex, [Mn(1,4-bix)(chdc)(H₂O)₂], (I), which exists as an unusual six-connected α-polonium network.

Selected bond lengths and angles for (I) are given in Table 1. As shown in Fig. 1, the repeat unit of (I) contains one Mn^II atom, one 1,4-bix ligand, one chdc anion and two coordination water molecules. Each Mn^II atom lies on a centre of symmetry, and is six-coordinated in an octahedral environment by two carboxylate O atoms from two different chdc anions, two water O atoms and two N atoms from two distinct 1,4-bix ligands. Atoms O1, O1ⁱⁱⁱ, N1 and N1ⁱⁱⁱ comprise the basal plane, and atoms O1W and O1Wⁱⁱⁱ occupy the axial positions of the octahedron [symmetry code: (iii) Please complete]. The average Mn—O(carboxylate) and Mn—N distances in (I) (Table 1) are comparable with those observed for [Mn(bza)₂(ppz)₂] [bza is benzoic acid and ppz is 3-(2-pyridyl)pyrazole; Zou et al., 2005]. As depicted in Fig. 2, each Mn^II centre is bridged by the chdc dianions and 1,4-bix ligands to give a two-dimensional four-connected (4,4) network. Along the [101] direction, adjacent Mn^II centres are linked via the two monodentate carboxylate groups of the chdc ligands to form one-dimensional chains. The 1,4-bix ligands further extend these chains along the [111] direction, resulting in the final two-dimensional (4,4) network, with dimensions of 13.96 (2) × 11.65 (2) Å for the repeat unit. Analysis of the crystal packing of (I) reveals that these two-dimensional layers adopt a parallel stacking mode in the (101) plane.

The driving force for the formation of this unusual topology becomes apparent when the structure of (I) is examined in detail. Along the [100] direction, there are hydrogen-bonding interactions between the water molecules and carboxylate O atoms (Table 2) of neighbouring (4,4) networks. The hydrogen bonds link neighbouring (4,4) networks, yielding a three-dimensional supramolecular architecture (Fig. 3). If each double hydrogen-bonded bridge is considered as one linker, each Mn^II atom can be regarded as a six-connected node, and the overall network topology is that of α-polonium (Batten & Robson, 1998). Recently, several six-connected nets, such as 4⁴.6¹¹, LB-1 (4⁴.6¹⁰.8), pcu (4¹².6³), roa (4⁴.6¹⁰.8), and rob (4⁸.6⁶.8), have been observed in coordination polymers (Zhang et al., 2007). It is noteworthy that the α-polonium net presented here is clearly different from the six-connected three-dimensional nets mentioned above. To the best of our knowledge, the structure of (I) is the first α-polonium net constructed from hydrogen-bonding interactions in a coordination polymer.

S2. Experimental

Manganese chloride hexahydrate (0.119 g, 0.5 mmol), H₂chdc (0.135 g, 0.5 mmol) and 1,4-bix (0.093 g, 0.5 mmol) were placed in water (13 ml), and triethylamine was added until the pH value of the solution was 5.5. The solution was heated in a 23 ml Teflon-lined stainless steel autoclave at 445 K for 3 d. The autoclave was allowed to cool to room temperature over several hours. Block crystals of (I) were isolated in about 47% yield.

S3. Refinement

Carbon-bound H atoms were positioned geometrically, with C—H = 0.93 Å, and refined as riding, with U_iso(H) = 1.2U_eq(C). The water H atoms were located in a difference Fourier map, and were refined freely.

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SMART (Bruker, 1997); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL-Plus (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. A view of the local coordination of the Mn^ii atom in (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii. [Symmetry codes: (i) 1 - x, -y, 1 - z; (ii) 1 - x, 1 - y, 1 - z; (iii) -x, -y, -z.]
	Fig. 2. A view of the (4,4) network of (I), in the (101) plane.
	Fig. 3. A view of the three-dimensional hydrogen-bonding framework structure of (I), along the [010] direction

Poly[diaqua[µ-1,4-bis(imidazol-1-ylmethyl)benzene- κ²N³:N^3'](µ-cyclohexane-1,4-carboxylato- κ²O¹:O⁴)manganese(II)]

Crystal data

[Mn(C8H10O4)(C14H14N4)(H2O)2]	Z = 1
Mr = 499.42	F(000) = 261
Triclinic, P1	Dx = 1.489 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.6645 (2) Å	Cell parameters from 2255 reflections
b = 9.4282 (6) Å	θ = 3.0–26.4°
c = 10.7437 (5) Å	µ = 0.64 mm^−1
α = 91.907 (4)°	T = 293 K
β = 95.553 (3)°	Block, colourless
γ = 102.426 (4)°	0.23 × 0.19 × 0.16 mm
V = 556.84 (5) Å^3

Data collection

Bruker APEX diffractometer	2255 independent reflections
Radiation source: sealed tube	1887 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
ϕ and ω scans	θmax = 26.4°, θmin = 4.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −7→6
Tmin = 0.861, Tmax = 0.906	k = −11→10
5312 measured reflections	l = −12→13

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)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.076	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0413P)^2 + 0.015P] where P = (Fo^2 + 2Fc^2)/3
2255 reflections	(Δ/σ)max < 0.001
159 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.22 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	−0.1747 (3)	0.3008 (2)	0.0759 (2)	0.0436 (5)
H1	−0.3309	0.2675	0.0358	0.052*
C2	−0.0904 (4)	0.4328 (2)	0.1351 (2)	0.0473 (6)
H2	−0.1756	0.5061	0.1430	0.057*
C3	0.1913 (3)	0.3101 (2)	0.14803 (18)	0.0340 (4)
H3	0.3402	0.2855	0.1683	0.041*
C4	0.3124 (4)	0.5616 (2)	0.25080 (18)	0.0387 (5)
H4A	0.2294	0.6406	0.2597	0.046*
H4B	0.4480	0.5950	0.2026	0.046*
C5	0.4095 (3)	0.52626 (18)	0.37907 (16)	0.0287 (4)
C6	0.2643 (3)	0.4373 (2)	0.45444 (17)	0.0338 (4)
H6	0.1047	0.3943	0.4240	0.041*
C7	0.6480 (3)	0.5886 (2)	0.42597 (17)	0.0331 (4)
H7	0.7491	0.6482	0.3766	0.040*
C8	0.1839 (3)	−0.07995 (19)	0.26423 (15)	0.0243 (4)
C9	0.3820 (3)	−0.06034 (19)	0.37445 (15)	0.0254 (4)
H9	0.5024	−0.1144	0.3515	0.031*
C10	0.2878 (3)	−0.1211 (2)	0.49425 (15)	0.0295 (4)
H10A	0.2174	−0.2243	0.4795	0.035*
H10B	0.1605	−0.0737	0.5164	0.035*
C11	0.5119 (3)	0.0987 (2)	0.39691 (16)	0.0332 (4)
H11A	0.3948	0.1562	0.4145	0.040*
H11B	0.5820	0.1329	0.3216	0.040*
N1	0.0038 (2)	0.22288 (17)	0.08334 (13)	0.0312 (4)
N2	0.1440 (3)	0.43786 (16)	0.18122 (14)	0.0314 (4)
O1	0.24544 (19)	−0.02973 (14)	0.16165 (10)	0.0290 (3)
O2	−0.0256 (2)	−0.14543 (18)	0.27946 (13)	0.0508 (4)
O1W	0.3255 (2)	0.09931 (16)	−0.09218 (12)	0.0326 (3)
Mn1	0.0000	0.0000	0.0000	0.02103 (13)
HW12	0.256 (4)	0.124 (3)	−0.157 (2)	0.058 (7)*
HW11	0.437 (4)	0.063 (3)	−0.113 (2)	0.054 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0320 (9)	0.0443 (12)	0.0521 (13)	0.0114 (9)	−0.0082 (9)	−0.0149 (10)
C2	0.0418 (10)	0.0457 (13)	0.0570 (14)	0.0235 (10)	−0.0067 (10)	−0.0149 (11)
C3	0.0313 (9)	0.0317 (10)	0.0376 (10)	0.0102 (8)	−0.0071 (8)	−0.0073 (8)
C4	0.0507 (11)	0.0247 (10)	0.0353 (11)	0.0020 (8)	−0.0071 (9)	−0.0036 (8)
C5	0.0344 (9)	0.0202 (9)	0.0299 (9)	0.0044 (7)	0.0008 (8)	−0.0063 (7)
C6	0.0268 (8)	0.0324 (10)	0.0374 (11)	−0.0013 (7)	−0.0004 (8)	−0.0060 (9)
C7	0.0337 (9)	0.0308 (10)	0.0310 (10)	−0.0017 (8)	0.0056 (8)	−0.0022 (8)
C8	0.0245 (8)	0.0259 (9)	0.0224 (9)	0.0077 (7)	−0.0020 (7)	0.0008 (7)
C9	0.0274 (8)	0.0289 (9)	0.0185 (8)	0.0052 (7)	−0.0031 (7)	0.0017 (7)
C10	0.0328 (9)	0.0294 (10)	0.0215 (9)	−0.0011 (7)	−0.0036 (7)	0.0041 (7)
C11	0.0413 (10)	0.0324 (11)	0.0218 (9)	0.0019 (8)	−0.0040 (8)	0.0053 (8)
N1	0.0307 (7)	0.0323 (9)	0.0289 (8)	0.0077 (6)	−0.0040 (6)	−0.0075 (7)
N2	0.0368 (8)	0.0263 (8)	0.0287 (8)	0.0071 (6)	−0.0056 (6)	−0.0067 (7)
O1	0.0257 (6)	0.0440 (8)	0.0168 (6)	0.0082 (5)	−0.0022 (5)	0.0033 (5)
O2	0.0279 (7)	0.0782 (11)	0.0379 (8)	−0.0060 (7)	−0.0068 (6)	0.0275 (8)
O1W	0.0230 (6)	0.0491 (9)	0.0252 (7)	0.0073 (6)	0.0009 (6)	0.0033 (6)
Mn1	0.02051 (19)	0.0250 (2)	0.01583 (19)	0.00341 (14)	−0.00244 (13)	−0.00136 (14)

Geometric parameters (Å, º)

C1—C2	1.347 (3)	C8—O1	1.264 (2)
C1—N1	1.370 (2)	C8—C9	1.528 (2)
C1—H1	0.9300	C9—C11	1.522 (2)
C2—N2	1.362 (2)	C9—C10	1.523 (2)
C2—H2	0.9300	C9—H9	0.9800
C3—N1	1.316 (2)	C10—C11^ii	1.524 (2)
C3—N2	1.333 (2)	C10—H10A	0.9700
C3—H3	0.9300	C10—H10B	0.9700
C4—N2	1.468 (2)	C11—C10^ii	1.524 (2)
C4—C5	1.508 (2)	C11—H11A	0.9700
C4—H4A	0.9700	C11—H11B	0.9700
C4—H4B	0.9700	O1W—HW12	0.83 (3)
C5—C6	1.383 (3)	O1W—HW11	0.83 (2)
C5—C7	1.390 (2)	Mn1—N1	2.2515 (15)
C6—C7^i	1.381 (3)	Mn1—O1	2.1819 (10)
C6—H6	0.9300	Mn1—O1W	2.2203 (12)
C7—C6^i	1.381 (3)	Mn1—O1^iii	2.1819 (10)
C7—H7	0.9300	Mn1—O1W^iii	2.2203 (12)
C8—O2	1.243 (2)	Mn1—N1^iii	2.2515 (15)
C2—C1—N1	109.96 (16)	C11^ii—C10—H10A	109.2
C2—C1—H1	125.0	C9—C10—H10B	109.2
N1—C1—H1	125.0	C11^ii—C10—H10B	109.2
C1—C2—N2	106.53 (17)	H10A—C10—H10B	107.9
C1—C2—H2	126.7	C9—C11—C10^ii	111.87 (15)
N2—C2—H2	126.7	C9—C11—H11A	109.2
N1—C3—N2	112.47 (15)	C10^ii—C11—H11A	109.2
N1—C3—H3	123.8	C9—C11—H11B	109.2
N2—C3—H3	123.8	C10^ii—C11—H11B	109.2
N2—C4—C5	113.55 (15)	H11A—C11—H11B	107.9
N2—C4—H4A	108.9	C3—N1—C1	104.54 (16)
C5—C4—H4A	108.9	C3—N1—Mn1	125.58 (12)
N2—C4—H4B	108.9	C1—N1—Mn1	129.83 (12)
C5—C4—H4B	108.9	C3—N2—C2	106.50 (15)
H4A—C4—H4B	107.7	C3—N2—C4	127.03 (15)
C6—C5—C7	118.46 (17)	C2—N2—C4	126.44 (16)
C6—C5—C4	121.74 (16)	C8—O1—Mn1	126.24 (10)
C7—C5—C4	119.75 (17)	Mn1—O1W—HW12	98.7 (16)
C7^i—C6—C5	121.19 (16)	Mn1—O1W—HW11	129.9 (17)
C7^i—C6—H6	119.4	HW12—O1W—HW11	107 (2)
C5—C6—H6	119.4	O1—Mn1—O1^iii	180.00 (7)
C6^i—C7—C5	120.35 (17)	O1—Mn1—O1W^iii	92.04 (5)
C6^i—C7—H7	119.8	O1^iii—Mn1—O1W^iii	87.96 (5)
C5—C7—H7	119.8	O1—Mn1—O1W	87.96 (5)
O2—C8—O1	123.89 (14)	O1^iii—Mn1—O1W	92.04 (5)
O2—C8—C9	118.78 (15)	O1W^iii—Mn1—O1W	180.00 (9)
O1—C8—C9	117.32 (14)	O1—Mn1—N1^iii	91.53 (5)
C11—C9—C10	110.64 (14)	O1^iii—Mn1—N1^iii	88.47 (5)
C11—C9—C8	110.81 (14)	O1W^iii—Mn1—N1^iii	88.10 (5)
C10—C9—C8	113.15 (13)	O1W—Mn1—N1^iii	91.90 (5)
C11—C9—H9	107.3	O1—Mn1—N1	88.47 (5)
C10—C9—H9	107.3	O1^iii—Mn1—N1	91.53 (5)
C8—C9—H9	107.3	O1W^iii—Mn1—N1	91.90 (5)
C9—C10—C11^ii	112.14 (14)	O1W—Mn1—N1	88.10 (5)
C9—C10—H10A	109.2	N1^iii—Mn1—N1	180.00 (10)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—HW11···O1^iv	0.83 (2)	2.00 (2)	2.8103 (18)	165 (2)
O1W—HW12···O2^iii	0.83 (3)	1.81 (3)	2.6150 (18)	163 (2)

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