A one-dimensional Co^II coordination polymer exhibiting an unusual conformation for 1,2-bis(4-pyridyl)­ethane

The title compound, catena-poly­[[[tetra­aqua­cobalt(II)]-μ-1,2-bis(4-pyridyl)­ethane-κ²N:N] 2,6-naphthalene­di­carboxyl­ate], {[Co(C₁₂H₁₂N₂)(H₂O)₄](C₁₂H₆O₄)}_n or {[Co(BPE)(H₂O)₄](NDC)}_n [BPE is 1,2-bis(4-pyridyl)­ethane and NDC is 2,6-naphthalene­di­carboxyl­ate], denoted CUmof-4, was synthesized under mild hydro­thermal conditions. The crystal structure contains one-dimensional [Co(BPE)(H₂O)₄]_n²ⁿ⁺ coordination polymers, which stack along the b direction, alternating with uncoordinated NDC anions. The Co atom is located on a centre of symmetry. Hydro­gen bonds between the cationic polymer and the anions give rise to a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 180 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.042
• wR factor = 0.109
• Data-to-parameter ratio = 7.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level A:



THETM_01  Alert A The value of sine(theta_max)/wavelength is less than 0.550
          Calculated sin(theta_max)/wavelength =    0.5348


 Alert Level B:



REFNR_01  Alert B Ratio of reflections to parameters is < 8 for a
          centrosymmetric structure
          sine(theta)/lambda                0.5348
          Proportion of unique data used    1.0000
          Ratio reflections to parameters   7.9422


 1 Alert Level A = Potentially serious problem

 1 Alert Level B = Potential problem

 0 Alert Level C = Please check

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S1. Comment

We are interested in the synthesis of novel coordination compounds which contain both carboxylate and 4-pyridyl groups coordinated to metal centres (Almeida Paz et al., 2002). In particular, the use of 1,2-bis(4-pyridyl)ethane (BPE), which has increased flexibility compared to 4,4'-bipyridine (BPY), due to the two methylene (–CH₂–) groups between the 4-pyridyl rings, may lead to supramolecular isomerism (Hennigar et al., 1997).

The title compound, CUmof-4, (I), contains one crystallographically unique cobalt(II) centre, which occupies a centre of symmetry in P1 and exhibits an almost ideal octahedral environment composed of four water molecules in the equatorial plane and two trans-coordinated 4-pyridyl nitrogen atoms in axial positions (Fig. 1 and Table 1). A one-dimensional cationic [Co(BPE)(H₂O)₄]_n²ⁿ⁺ coordination polymer runs along the c direction (Fig. 2, top), with BPE ligands establishing bridges between metal centres [Co1···Co1ⁱ = 13.529 (2) Å; symmetry code: (i) x, y, z − 1]. These one-dimensional polymers alternate with NDC ions along the b direction (Fig. 1), with the anions being brought into close face-to-face contact to the BPE ligands (the average separation between adjacent aromatic rings being ca 3.5 Å) (Fig. 2). These interactions may account for the unusual conformation of the BPE ligand, within which both 4-pyridyl groups lie in the same plane. O—H···O⁻ hydrogen bonds connect the NDC anions to the coordinated water molecules, giving rise to a three-dimensional network (Fig. 3 and Table 2).

S2. Experimental

All chemicals were obtained from commercial sources and were used without further purification. To a solution of Co(NO₃)₂·6H₂O (0.476 g, Aldrich) in distilled water (12.4 g), 1,2-bis(4-pyridyl)ethane (BPE, 0.378 g, Aldrich), 2,6-naphthalenedicarboxylic acid (H₂NDC, 0.437 g, Aldrich) and triethylamine (TEA, 0.388 g, Avocado) were added, and the mixture was stirred thoroughly for 1 h at ambient temperature. The suspension, with an H₂NDC:Co²⁺:BPE:TEA:H₂O ratio of 1.01:1.00:1.02:1.91:343, was placed in a Parr stainless steel teflon-lined vessel (21 ml, filling rate 50%). The reaction was performed under autogeneous pressure and static conditions in a pre-heated oven at 418 K for 3 h. The vessel was then cooled slowly inside the oven to 298 K at a rate of 5 K h⁻¹ before opening. The crystalline product was collected by vacuum filtration and crystals of the title compound were manually separated and preserved in a portion of the autoclave solution.

S3. Refinement

H atoms bound to carbon were placed in calculated positions and allowed to ride during subsequent refinement, with U_iso(H) = 1.2U_eq(C). Aqua H atoms were located in difference Fourier maps and refined with a single isotropic displacement parameter common to all H atoms, and O—H and H···H distances restrained to ensure a reasonable geometry for the water molecules.

Computing details

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 at al., 1994); program(s) used to refine structure: SHELXTL (Bruker, 2001); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. View approximately along the a direction, showing alternation along b between one-dimensional cationic [Co(BPE)(H2O)4]n^2n+ coordination polymers and NDC anions. Hydrogen bonds are drawn as dashed lines. The asymmetric unit of CUmof-4 is represented with ellipsoids drawn at the 50% probability level. H atoms have been omitted for clarity. Colour scheme: C gray, N green, O blue and Co brown.
	Fig. 2. Perspective view of CUmof-4 along the b direction. Co^II centres are represented as octahedra, BPE ligands with black and NDC ions with white bonds.
	Fig. 3. Perspective view of CUmof-4 along the c direction, showing the O—H···O^− hydrogen-bonding network (dotted lines). H atoms have been omitted for clarity.

catena-poly[[[tetraaquacobalt(II)]-µ-1,2-bis(4-pyridyl)ethane-κ²N:N] 2,6-naphthalenedicarboxylate]

Crystal data

[Co(C12H12N2)(H2O)4](C12H6O4)	Z = 1
Mr = 529.40	F(000) = 275
Triclinic, P1	Dx = 1.616 Mg m^−3
a = 6.3586 (12) Å	Mo Kα radiation, λ = 0.7107 Å
b = 7.0047 (10) Å	Cell parameters from 6957 reflections
c = 13.529 (2) Å	θ = 1.0–22.5°
α = 88.463 (11)°	µ = 0.85 mm^−1
β = 77.165 (8)°	T = 180 K
γ = 68.056 (9)°	Plate, colourless
V = 543.91 (15) Å^3	0.18 × 0.12 × 0.01 mm

Data collection

Nonius KappaCCD diffractometer	1374 independent reflections
Radiation source: fine-focus sealed tube	1189 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.063
Thin–slice ω and ϕ scans	θmax = 22.3°, θmin = 3.5°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −6→6
Tmin = 0.943, Tmax = 0.992	k = −7→7
3625 measured reflections	l = −14→14

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)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.109	H atoms treated by a mixture of independent and constrained refinement
S = 1.20	w = 1/[σ^2(Fo^2) + (0.052P)^2 + 0.0618P] where P = (Fo^2 + 2Fc^2)/3
1374 reflections	(Δ/σ)max = 0.007
173 parameters	Δρmax = 0.37 e Å^−3
6 restraints	Δρmin = −0.42 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
Co1	0.0000	0.0000	0.0000	0.0222 (3)
O11	−0.2032 (5)	−0.1818 (4)	0.0287 (2)	0.0266 (7)
H11A	−0.171 (8)	−0.264 (5)	0.073 (2)	0.049 (8)*
H11B	−0.207 (9)	−0.241 (6)	−0.022 (2)	0.049 (8)*
O12	−0.2844 (5)	0.2830 (4)	0.0577 (2)	0.0296 (7)
H12A	−0.240 (7)	0.359 (6)	0.086 (3)	0.049 (8)*
H12B	−0.420 (5)	0.303 (6)	0.087 (3)	0.049 (8)*
O311	−0.2476 (5)	−0.3552 (4)	−0.1335 (2)	0.0298 (7)
O312	0.1401 (5)	−0.5207 (4)	−0.1781 (2)	0.0284 (7)
N21	−0.0504 (5)	0.0475 (5)	−0.1492 (2)	0.0235 (8)
C21	0.1358 (7)	0.0030 (6)	−0.2266 (3)	0.0230 (9)
H21A	0.2834	−0.0280	−0.2113	0.028*
C22	0.1263 (7)	−0.0006 (5)	−0.3267 (3)	0.0228 (9)
H22A	0.2648	−0.0349	−0.3786	0.027*
C23	−0.0877 (7)	0.0463 (5)	−0.3518 (3)	0.0214 (9)
C24	−0.2827 (7)	0.1028 (6)	−0.2721 (3)	0.0258 (10)
H24A	−0.4332	0.1430	−0.2856	0.031*
C25	−0.2590 (7)	0.1009 (6)	−0.1733 (3)	0.0273 (10)
H25A	−0.3952	0.1387	−0.1199	0.033*
C26	−0.1130 (7)	0.0341 (6)	−0.4595 (3)	0.0238 (9)
H26A	−0.2166	0.1715	−0.4748	0.029*
H26B	−0.1909	−0.0632	−0.4640	0.029*
C31	−0.0592 (7)	−0.4456 (6)	−0.1980 (3)	0.0238 (10)
C32	−0.0749 (7)	−0.4597 (5)	−0.3076 (3)	0.0223 (9)
C33	0.1213 (7)	−0.5191 (5)	−0.3845 (3)	0.0222 (9)
H33A	0.2687	−0.5556	−0.3682	0.027*
C34	−0.2949 (7)	−0.4070 (5)	−0.3320 (3)	0.0233 (9)
H34A	−0.4323	−0.3670	−0.2792	0.028*
C35	−0.3108 (7)	−0.4131 (5)	−0.4308 (3)	0.0234 (10)
H35A	−0.4598	−0.3767	−0.4454	0.028*
C36	−0.1113 (6)	−0.4722 (5)	−0.5118 (3)	0.0206 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0172 (5)	0.0300 (5)	0.0187 (5)	−0.0079 (3)	−0.0051 (3)	0.0032 (3)
O11	0.0246 (17)	0.0350 (16)	0.0217 (17)	−0.0117 (13)	−0.0076 (14)	0.0037 (13)
O12	0.0196 (17)	0.0344 (16)	0.0327 (18)	−0.0079 (13)	−0.0051 (14)	−0.0023 (14)
O311	0.0236 (18)	0.0413 (16)	0.0220 (16)	−0.0111 (14)	−0.0016 (14)	−0.0053 (14)
O312	0.0214 (17)	0.0364 (15)	0.0264 (16)	−0.0080 (13)	−0.0084 (13)	0.0020 (13)
N21	0.018 (2)	0.0281 (17)	0.024 (2)	−0.0086 (14)	−0.0053 (16)	0.0019 (15)
C21	0.019 (2)	0.027 (2)	0.020 (2)	−0.0059 (17)	−0.0036 (19)	0.0034 (18)
C22	0.020 (2)	0.023 (2)	0.022 (2)	−0.0055 (17)	−0.0015 (18)	0.0012 (18)
C23	0.025 (2)	0.0188 (19)	0.021 (2)	−0.0083 (17)	−0.007 (2)	0.0051 (17)
C24	0.020 (2)	0.031 (2)	0.026 (2)	−0.0077 (18)	−0.008 (2)	0.0037 (19)
C25	0.018 (2)	0.035 (2)	0.025 (2)	−0.0082 (18)	−0.0014 (19)	0.0042 (19)
C26	0.024 (2)	0.026 (2)	0.022 (2)	−0.0094 (17)	−0.0084 (17)	0.0042 (17)
C31	0.027 (3)	0.024 (2)	0.023 (2)	−0.0125 (19)	−0.007 (2)	0.0034 (19)
C32	0.022 (2)	0.0172 (19)	0.025 (2)	−0.0052 (16)	−0.0045 (19)	0.0015 (17)
C33	0.020 (2)	0.022 (2)	0.025 (2)	−0.0071 (17)	−0.009 (2)	0.0050 (18)
C34	0.021 (2)	0.025 (2)	0.021 (2)	−0.0074 (17)	−0.0026 (18)	−0.0002 (17)
C35	0.014 (2)	0.025 (2)	0.029 (3)	−0.0045 (17)	−0.006 (2)	0.0009 (19)
C36	0.018 (2)	0.0149 (19)	0.025 (2)	−0.0031 (16)	−0.0032 (18)	0.0028 (17)

Geometric parameters (Å, º)

Co1—O11	2.103 (3)	C23—C26	1.509 (5)
Co1—O11^i	2.103 (3)	C24—C25	1.378 (6)
Co1—N21	2.111 (3)	C24—H24A	0.950
Co1—N21^i	2.111 (3)	C25—H25A	0.950
Co1—O12	2.141 (3)	C26—C26^ii	1.520 (8)
Co1—O12^i	2.141 (3)	C26—H26A	0.990
O11—H11A	0.82 (2)	C26—H26B	0.990
O11—H11B	0.82 (2)	C31—C32	1.515 (6)
O12—H12A	0.83 (2)	C32—C33	1.368 (5)
O12—H12B	0.83 (2)	C32—C34	1.420 (5)
O311—C31	1.264 (5)	C33—C36^iii	1.422 (5)
O312—C31	1.265 (5)	C33—H33A	0.950
N21—C21	1.337 (5)	C34—C35	1.366 (5)
N21—C25	1.349 (5)	C34—H34A	0.950
C21—C22	1.370 (5)	C35—C36	1.413 (5)
C21—H21A	0.950	C35—H35A	0.950
C22—C23	1.393 (5)	C36—C33^iii	1.422 (5)
C22—H22A	0.950	C36—C36^iii	1.429 (7)
C23—C24	1.385 (6)
O11—Co1—O11^i	180.00 (9)	C22—C23—C26	123.2 (4)
O11—Co1—N21	92.29 (11)	C25—C24—C23	120.2 (4)
O11^i—Co1—N21	87.71 (11)	C25—C24—H24A	119.9
O11—Co1—N21^i	87.71 (11)	C23—C24—H24A	119.9
O11^i—Co1—N21^i	92.29 (11)	N21—C25—C24	122.7 (4)
N21—Co1—N21^i	180.00 (17)	N21—C25—H25A	118.7
O11—Co1—O12	94.68 (10)	C24—C25—H25A	118.7
O11^i—Co1—O12	85.32 (11)	C23—C26—C26^ii	115.4 (4)
N21—Co1—O12	91.82 (11)	C23—C26—H26A	108.4
N21^i—Co1—O12	88.18 (11)	C26^ii—C26—H26A	108.4
O11—Co1—O12^i	85.32 (11)	C23—C26—H26B	108.4
O11^i—Co1—O12^i	94.68 (11)	C26^ii—C26—H26B	108.4
N21—Co1—O12^i	88.18 (11)	H26A—C26—H26B	107.5
N21^i—Co1—O12^i	91.82 (11)	O311—C31—O312	124.9 (4)
O12—Co1—O12^i	180.0	O311—C31—C32	117.0 (3)
Co1—O11—H11A	114 (3)	O312—C31—C32	118.1 (4)
Co1—O11—H11B	114 (3)	C33—C32—C34	119.0 (4)
H11A—O11—H11B	110 (3)	C33—C32—C31	120.7 (3)
Co1—O12—H12A	111 (3)	C34—C32—C31	120.3 (4)
Co1—O12—H12B	130 (3)	C32—C33—C36^iii	122.0 (3)
H12A—O12—H12B	108 (3)	C32—C33—H33A	119.0
C21—N21—C25	116.7 (3)	C36^iii—C33—H33A	119.0
C21—N21—Co1	119.0 (2)	C35—C34—C32	120.5 (4)
C25—N21—Co1	124.0 (3)	C35—C34—H34A	119.7
N21—C21—C22	123.9 (4)	C32—C34—H34A	119.7
N21—C21—H21A	118.1	C34—C35—C36	121.7 (4)
C22—C21—H21A	118.1	C34—C35—H35A	119.1
C21—C22—C23	119.6 (4)	C36—C35—H35A	119.1
C21—C22—H22A	120.2	C35—C36—C33^iii	123.2 (3)
C23—C22—H22A	120.2	C35—C36—C36^iii	118.3 (5)
C24—C23—C22	116.8 (4)	C33^iii—C36—C36^iii	118.5 (4)
C24—C23—C26	120.0 (3)
O11—Co1—N21—C21	−126.5 (3)	Co1—N21—C25—C24	−170.7 (3)
O11^i—Co1—N21—C21	53.5 (3)	C23—C24—C25—N21	0.7 (6)
O12—Co1—N21—C21	138.7 (3)	C24—C23—C26—C26^ii	−178.7 (4)
O12^i—Co1—N21—C21	−41.3 (3)	C22—C23—C26—C26^ii	0.1 (6)
O11—Co1—N21—C25	46.5 (3)	O311—C31—C32—C33	167.6 (3)
O11^i—Co1—N21—C25	−133.5 (3)	O312—C31—C32—C33	−11.0 (5)
O12—Co1—N21—C25	−48.3 (3)	O311—C31—C32—C34	−11.0 (5)
O12^i—Co1—N21—C25	131.7 (3)	O312—C31—C32—C34	170.4 (3)
C25—N21—C21—C22	−3.2 (5)	C34—C32—C33—C36^iii	0.5 (5)
Co1—N21—C21—C22	170.3 (3)	C31—C32—C33—C36^iii	−178.1 (3)
N21—C21—C22—C23	0.7 (6)	C33—C32—C34—C35	−0.7 (5)
C21—C22—C23—C24	2.5 (5)	C31—C32—C34—C35	177.9 (3)
C21—C22—C23—C26	−176.3 (3)	C32—C34—C35—C36	0.2 (5)
C22—C23—C24—C25	−3.2 (5)	C34—C35—C36—C33^iii	179.8 (3)
C26—C23—C24—C25	175.6 (3)	C34—C35—C36—C36^iii	0.5 (6)
C21—N21—C25—C24	2.5 (5)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O11—H11A···O312^iv	0.82 (2)	2.03 (3)	2.846 (4)	170 (4)
O11—H11B···O311	0.82 (2)	1.83 (3)	2.654 (4)	174 (5)
O12—H12A···O312^i	0.83 (2)	2.05 (3)	2.867 (4)	170 (4)
O12—H12B···O311^v	0.83 (2)	1.96 (3)	2.777 (4)	170 (4)

Symmetry codes: (i) −x, −y, −z; (iv) −x, −y−1, −z; (v) −x−1, −y, −z.