A one-dimensional zigzag coordination polymer of di­aqua­(pyridine-2,3-di­carboxyl­ato)­cobalt(II)

The asymmetric unit of the title one-dimensional coordination polymer, catena-poly­[[μ-pyridine-2,3-di­carb­oxyl­ato-1κO:2κ²N,O′-bis­[di­aqua­cobalt(II)]]-μ-pyridine-2,3-di­carboxyl­ato-1κ²N,O:2κO′:1′κO′], [Co(C₇H₃NO₄)(H₂O)₂]_n, is composed of a cobalt(II) ion, a pyridine-2,3-di­carboxyl­ate dianion and two water mol­ecules. The polymer has a zigzag structure consisting of a chain of edge-fused rings, and the polymer chains are linked by O—H...O hydrogen bonds into a three-dimensional framework.

S1. Comment

The design and synthesis of coordination polymers is one of the most stimulating research frontiers in contemporary chemistry, owing to the intriguing crystallographic structure and the functional properties of these compounds as potential applications in materials (Eddaoudi et al., 2001; Seo et al., 2000; Perles et al., 2003). Based on the nature of the metal and the coordination behaviour of the ligand, the "node and spacer" approach has been remarkably successful at producing predicatable coordination-polymer architectures (Batten & Robson, 1998). Many coordination polymers can be generated by using metal ions as the "node" and linking them with linear "spacer" ligands such as 1,4-benzenedicarboxylate, 4-pyridinecarboxylate and 4,4'-bipyridine (Li et al., 1999; Hagrman et al., 1999; Lu & Babb, 2001). We present here the structure of a one-dimensional zigzag-type coordination polymer, namely catena-poly [diaqua(pyridine-2,3-dicarboxylato-κ⁴N:O,O',O')cobalt(II)], (I).

The coordination motif of the Co^II atom is a distorted octahedron (Table 1, Fig. 1) in which pyridyl atom N1, three carboxylate O atoms [O4, O1ⁱ and O1ⁱⁱ; symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) x, y, z − 1] and two water oxygen atoms (O1W and O2W) occupy the vertices. Thus, one cobalt(II) ion is bound to three pyridine-2,3-dicarboxylate ligands. One of these ligands chelates to the Co^II atom via the pyridine N atom and one of the O atoms of the carboxylate group in the 2-position, thus generating a five-membered chelating ring (–C1—N1—Co—O4—C7-). The other carboxylate group (in the 3-position) lies almost perpendicular to the pyridine plane because of steric interaction between the two carboxylate groups. The O1—C6—O2 dihedral angle between the pyridine ring and the carboxyl is 88.40 (13)°. One of the O atoms of this ligand acts as a bridge to connect two Co^II atoms in µ₂-O mode, thus forming a rhomboidal Co₂O₂ ring. The Co···Coⁱ [symmetry code: (i) 1 − x, 1 − y, 1 − z] distance is 3.4052 (8) Å, and the dihedral angle between the rhomboid ring and the five-membered chelating ring is 86.46 (7)°.

Along the c axis, two antiparallel ligands connect a pair of neighbouring Co^II atoms in a head-to-tail fashion, thus generating a chain of edge-fused rings; alternatively, the structure may be regarded as a pair of zigzag chains that are joined together via the common Co₂O₂ rhomboid unit. The two parallel zigzag chains are related by inversion centres.

There are two intrachain hydrogen bonds, viz. O1W—H1WA···O2ⁱⁱ and O2W—H2WA···O3ⁱⁱ [symmetry code: (ii) x, y, z − 1], which may exert some influence on the overall conformation of the chain. The chains are arranged in a parallel fashion along the a axis and in a zigzag fasion along the b direction. As a result, along the a axis, the chains are connected by interchain O2W—H2WB···O4^v hydrogen bonds [symmetry code: (v) −x, 1 − y, −z] to form a (010) sheet. Meanwhile, along the b axis, an interchain O1W—H1WB···O2^iv hydrogen bond [symmetry code: (iv) x, 1.5 − y, −0.5 + z], links the chains into puckered (100) sheets. The combination of the (100) and (010) sheets links all of the polymer chains into a three-dimensional hydrogen-bonded framework.

S2. Experimental

Co(ClO₄)₂·6H₂O (36.6 mg, 0.10 mmol), pyridine-2,3-dicarboxylic acid (16.7 mg, 0.10 mmol) and pyridine (0.4 cm³) were dissolved in a mixture of water (3 cm³) and ethanol (3 cm³), and the mixture was placed in a Teflon-lined stainless-steel vessel (25 cm³). The vessel was sealed and heated at 403 K for 3 d and then cooled to room temperature. Large red prismatic crystals were collected by filtration, followed by washing with water and ethanol.

S3. Refinement

H atoms bonded to C atoms were treated as riding, with U_iso(H) values equal to 1.2U_eq(C) and C—H distances of 0.93 Å. Water H atoms were located from difference maps and were refined subject to an O—H DFIX restraint of 0.82 (3) Å (eight restraints), and the U_iso(H) values were constrained to be 1.2U_eq(O).

Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2000); software used to prepare material for publication: SHELXTL (Sheldrick, 2000).

Figures

	Fig. 1. The molecular structure of (I), with displacement ellipsoids shown at the 30% probability level. H atoms unrelated to the asymmetric unit (open lines portion) have been omitted for clarity. [Symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) x, y, z − 1; (iii) 1 − x, 1 − y, −z.]
	Fig. 2. Stereoview of the structure, viewed approximately along the c axis. For clarity, H atoms have been omitted. Dashed lines indicate the location of the O—H···O hydrogen bonds.

catena- [diaqua(pyridine-2,3-dicarboxylato-κ⁴N:O,O',O')cobalt(II)]

Crystal data

[Co(C7H3NO4)(H2O)2]	F(000) = 524
Mr = 260.07	Dx = 2.007 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 7.7200 (15) Å	θ = 2.2–13.9°
b = 15.620 (3) Å	µ = 2.00 mm^−1
c = 7.8100 (16) Å	T = 298 K
β = 113.95 (3)°	Prism, red
V = 860.7 (4) Å^3	0.37 × 0.24 × 0.20 mm
Z = 4

Data collection

Enraf–Nonius CAD-4 diffractometer	1254 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.017
Graphite monochromator	θmax = 25.0°, θmin = 3.1°
ω scans	h = 0→9
Absorption correction: psi scan XCAD4 (Harms & Wocadlo, 1995)	k = 0→18
Tmin = 0.470, Tmax = 0.670	l = −9→8
1625 measured reflections	3 standard reflections every 200 reflections
1509 independent reflections	intensity decay: 1.1%

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)] = 0.023	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.062	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0319P)^2 + 0.385P] where P = (Fo^2 + 2Fc^2)/3
1509 reflections	(Δ/σ)max = 0.001
152 parameters	Δρmax = 0.28 e Å^−3
4 restraints	Δρmin = −0.36 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
Co	0.35351 (4)	0.55715 (2)	0.07142 (4)	0.01702 (12)
N1	0.5480 (3)	0.60168 (12)	0.3338 (3)	0.0172 (4)
O1	0.5170 (2)	0.56919 (10)	0.8996 (2)	0.0179 (4)
O2	0.4216 (3)	0.70161 (11)	0.8014 (3)	0.0340 (5)
O3	0.1955 (3)	0.57115 (13)	0.5084 (3)	0.0291 (4)
O4	0.1997 (2)	0.54100 (11)	0.2318 (2)	0.0228 (4)
O1W	0.2409 (3)	0.68383 (12)	0.0173 (3)	0.0295 (4)
O2W	0.1461 (3)	0.51688 (13)	−0.1719 (3)	0.0261 (4)
C1	0.4757 (3)	0.60161 (14)	0.4647 (3)	0.0164 (5)
C2	0.5794 (3)	0.62869 (15)	0.6463 (3)	0.0188 (5)
C3	0.7636 (4)	0.65845 (16)	0.6929 (3)	0.0234 (6)
H3	0.8374	0.6766	0.8143	0.028*
C4	0.8349 (4)	0.66065 (17)	0.5579 (4)	0.0259 (6)
H4	0.9565	0.6811	0.5856	0.031*
C5	0.7216 (4)	0.63170 (16)	0.3793 (4)	0.0225 (5)
H5	0.7695	0.6334	0.2876	0.027*
C6	0.4965 (3)	0.63277 (15)	0.7909 (3)	0.0193 (5)
C7	0.2737 (3)	0.56924 (15)	0.3987 (3)	0.0186 (5)
H2WA	0.144 (5)	0.531 (2)	−0.273 (4)	0.042 (10)*
H1WA	0.280 (5)	0.699 (2)	−0.060 (4)	0.050 (11)*
H2WB	0.039 (4)	0.501 (3)	−0.178 (5)	0.071 (13)*
H1WB	0.296 (5)	0.713 (2)	0.114 (4)	0.062 (12)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co	0.01784 (18)	0.02070 (18)	0.01339 (18)	−0.00146 (14)	0.00724 (13)	−0.00179 (13)
N1	0.0185 (10)	0.0175 (10)	0.0171 (10)	0.0000 (8)	0.0088 (8)	−0.0020 (8)
O1	0.0200 (8)	0.0195 (8)	0.0151 (8)	0.0005 (7)	0.0082 (7)	0.0023 (7)
O2	0.0591 (13)	0.0215 (10)	0.0323 (11)	0.0098 (9)	0.0299 (10)	0.0048 (8)
O3	0.0225 (9)	0.0497 (12)	0.0196 (9)	−0.0034 (8)	0.0132 (8)	−0.0016 (8)
O4	0.0206 (9)	0.0322 (10)	0.0168 (8)	−0.0065 (7)	0.0089 (7)	−0.0049 (7)
O1W	0.0369 (11)	0.0270 (10)	0.0268 (11)	0.0007 (9)	0.0153 (10)	−0.0011 (9)
O2W	0.0189 (9)	0.0427 (11)	0.0157 (9)	−0.0089 (8)	0.0059 (8)	−0.0039 (8)
C1	0.0198 (12)	0.0149 (11)	0.0162 (12)	0.0010 (10)	0.0089 (10)	0.0016 (9)
C2	0.0219 (12)	0.0163 (11)	0.0181 (12)	−0.0002 (10)	0.0081 (10)	0.0027 (9)
C3	0.0230 (13)	0.0260 (13)	0.0186 (12)	−0.0039 (10)	0.0057 (11)	−0.0017 (10)
C4	0.0208 (13)	0.0270 (13)	0.0293 (14)	−0.0040 (11)	0.0097 (11)	−0.0015 (11)
C5	0.0249 (13)	0.0235 (13)	0.0242 (13)	−0.0018 (11)	0.0152 (11)	−0.0012 (10)
C6	0.0208 (12)	0.0217 (12)	0.0138 (12)	−0.0049 (10)	0.0055 (10)	−0.0030 (10)
C7	0.0193 (12)	0.0192 (12)	0.0172 (12)	0.0015 (10)	0.0074 (10)	0.0024 (9)

Geometric parameters (Å, º)

Co—O2W	2.025 (2)	O1W—H1WB	0.84 (3)
Co—O4	2.0613 (17)	O2W—H2WA	0.81 (2)
Co—N1	2.107 (2)	O2W—H2WB	0.85 (3)
Co—O1W	2.133 (2)	C1—C2	1.382 (3)
Co—O1^i	2.1821 (16)	C1—C7	1.517 (3)
Co—O1^ii	2.1920 (17)	C2—C3	1.396 (3)
N1—C5	1.325 (3)	C2—C6	1.508 (3)
N1—C1	1.348 (3)	C3—C4	1.374 (4)
O1—C6	1.274 (3)	C3—H3	0.9300
O2—C6	1.239 (3)	C4—C5	1.387 (4)
O3—C7	1.232 (3)	C4—H4	0.9300
O4—C7	1.271 (3)	C5—H5	0.9300
O1W—H1WA	0.81 (2)
O2W—Co—O4	95.81 (7)	Co—O2W—H2WA	122 (2)
O2W—Co—N1	174.31 (8)	Co—O2W—H2WB	122 (3)
O4—Co—N1	78.94 (7)	H2WA—O2W—H2WB	113 (3)
O2W—Co—O1W	89.93 (8)	N1—C1—C2	122.2 (2)
O4—Co—O1W	86.84 (8)	N1—C1—C7	115.3 (2)
N1—Co—O1W	87.63 (8)	C2—C1—C7	122.5 (2)
O2W—Co—O1^i	88.34 (7)	C1—C2—C3	118.3 (2)
O4—Co—O1^i	100.30 (6)	C1—C2—C6	122.4 (2)
N1—Co—O1^i	94.70 (7)	C3—C2—C6	119.2 (2)
O1W—Co—O1^i	172.79 (7)	C4—C3—C2	119.4 (2)
O2W—Co—O1^ii	83.37 (7)	C4—C3—H3	120.3
O4—Co—O1^ii	177.89 (6)	C2—C3—H3	120.3
N1—Co—O1^ii	101.96 (7)	C3—C4—C5	118.5 (2)
O1W—Co—O1^ii	95.09 (7)	C3—C4—H4	120.7
O1^i—Co—O1^ii	77.75 (6)	C5—C4—H4	120.7
C5—N1—C1	118.8 (2)	N1—C5—C4	122.8 (2)
C5—N1—Co	128.41 (16)	N1—C5—H5	118.6
C1—N1—Co	112.72 (15)	C4—C5—H5	118.6
C6—O1—Co^i	134.59 (15)	O2—C6—O1	124.6 (2)
C6—O1—Co^iii	121.89 (15)	O2—C6—C2	115.9 (2)
Co^i—O1—Co^iii	102.25 (6)	O1—C6—C2	119.3 (2)
C7—O4—Co	116.81 (15)	O3—C7—O4	125.3 (2)
Co—O1W—H1WA	100 (3)	O3—C7—C1	118.8 (2)
Co—O1W—H1WB	108 (3)	O4—C7—C1	115.8 (2)
H1WA—O1W—H1WB	108 (4)
O4—Co—N1—C5	−180.0 (2)	C1—C2—C3—C4	0.6 (4)
O1W—Co—N1—C5	−92.7 (2)	C6—C2—C3—C4	−175.3 (2)
O1^i—Co—N1—C5	80.5 (2)	C2—C3—C4—C5	−1.0 (4)
O1^ii—Co—N1—C5	2.0 (2)	C1—N1—C5—C4	2.1 (4)
O4—Co—N1—C1	−3.09 (15)	Co—N1—C5—C4	178.81 (19)
O1W—Co—N1—C1	84.15 (16)	C3—C4—C5—N1	−0.3 (4)
O1^i—Co—N1—C1	−102.69 (16)	Co^i—O1—C6—O2	−177.61 (18)
O1^ii—Co—N1—C1	178.86 (15)	Co^iii—O1—C6—O2	17.8 (3)
O2W—Co—O4—C7	−172.09 (17)	Co^i—O1—C6—C2	−2.2 (3)
N1—Co—O4—C7	5.72 (17)	Co^iii—O1—C6—C2	−166.81 (16)
O1W—Co—O4—C7	−82.48 (17)	C1—C2—C6—O2	−90.6 (3)
O1^i—Co—O4—C7	98.55 (17)	C3—C2—C6—O2	85.1 (3)
C5—N1—C1—C2	−2.6 (3)	C1—C2—C6—O1	93.6 (3)
Co—N1—C1—C2	−179.76 (18)	C3—C2—C6—O1	−90.7 (3)
C5—N1—C1—C7	177.8 (2)	Co—O4—C7—O3	173.87 (19)
Co—N1—C1—C7	0.6 (2)	Co—O4—C7—C1	−7.0 (3)
N1—C1—C2—C3	1.2 (3)	N1—C1—C7—O3	−176.6 (2)
C7—C1—C2—C3	−179.2 (2)	C2—C1—C7—O3	3.8 (3)
N1—C1—C2—C6	177.0 (2)	N1—C1—C7—O4	4.2 (3)
C7—C1—C2—C6	−3.4 (4)	C2—C1—C7—O4	−175.4 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WB···O2^iv	0.84 (3)	1.92 (3)	2.749 (3)	168 (4)
O1W—H1WA···O2^ii	0.81 (2)	1.83 (3)	2.604 (3)	160 (4)
O2W—H2WA···O3^ii	0.81 (2)	2.01 (2)	2.806 (3)	168 (3)
O2W—H2WB···O4^v	0.85 (3)	1.84 (3)	2.674 (3)	170 (4)

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