Poly[trans-diaqua­bis(μ₂-3-pyridylacetato)copper(II)]

The title copper^II coordination polymer, trans-[Cu(C₇H₆NO₂)₂(H₂O)₂]_n, was obtained from a solvothermal reaction of 3-pyridylacetic acid hydro­chloride with Cu(ClO₄)₂·6H₂O. The mol­ecule is centrosymmetric, so pairs of equivalent ligands lie trans to each other in a slightly distorted octa­hedral geometry. The Cu^II center is coordinated by two water mol­ecules [Cu—O = 2.424 (4) Å], two pyridyl N atoms [Cu—N = 2.031 (4) Å], and two carboxyl­ate O atoms [Cu—O1 = 1.968 (4) Å]. All O_{carboxyl­ate}—Cu—O_{carboxyl­ate}, O_water—Cu—O_water and N—Cu—N bond angles are 180° due to the inversion symmetry of the complexes. Each 3-pyridylacetate anion uses its pyridine N atom and one carboxyl­ate O atom to connect two Cu^II ions, generating two-dimensional sheets parallel to (212). Each complex exhibits two intra­molecular O—H...O hydrogen bonds with angles at hydrogen of 156°. Adjacent two-dimensional layers are connected via inter­molecular O—H...O and weak C—H...O hydrogen-bonding contacts, resulting in a three-dimensional framework structure with oxygen as a trifurcated acceptor atom.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.008 Å
• R factor = 0.047
• wR factor = 0.117
• Data-to-parameter ratio = 12.1

checkCIF/PLATON results

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Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.70 mm
PLAT341_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          8

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

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

Pyridinecarboxylic acids have been extensively used in the preparation of metal complexes because of their versatile coordination modes. These ligands can connect different metal ions to form robust networks or some porous coordination polymers. Though various metal-pyridinepolycarboxylate complexes have been reported (Evans et al., 2002; Aakeröy et al., 1999; Tong et al., 2003; Li et al., 2004; Du et al., 2006), complexes of 3-pyridylacetate are very limited. Only complexes of nickel and cobalt have been published recently up to now (Martin et al., 2007). In this paper, we report a new two-dimensional coordination polymer, [Cu(3-pyridylacetato)₂(H₂O)₂]_n, (I).

The molecule of the title complex, which is similar to that previously described for [M(Hpya)₂(H₂O)₂]_n (M = Cu, Co, Mn, Ni, Zn, Cd; Hpya = 4-pyridylacetic acid) (Li et al., 2004; Du et al., 2006) and [M(3-pyridylacetato)₂(H₂O)₂]_n (M = Ni, Co) (Martin et al., 2007), is centrosymmetric, so pairs of equivalent ligands lie trans to each other in a slightly distorted octahedral geometry. The Cu^II center is six-coordinated by two water molecules in the axial positions, two pyridyl nitrogen atoms and two carboxylate oxygen atoms from four 3-pyridylacetate ligands in the equatorial plane. Each 3-pyridylacetate anion uses its pyridine nitrogen atom and one carboxylate oxygen atom to connect two Cu^II ions. Four 3-pyridylacetate anionic ligands and four Cu^II ions form a tetragon with a side length of 8.405 Å and a diagonal measurement of 14.443 * 8.602 Å based on the Cu—Cu distances. The tetragon is further extended into a two-dimensional framework parallel to (212) with a rhombic grid through sharing Cu^II ions, 3-pyridylacetate anionic ligands and intramolecular O3—H1···O2 hydrogen bonds (Fig. 1).

Adjacent two-dimensional layers are connected via intermolecular O—H···O and weak C—H···O hydrogen-bonding contacts, resulting in a three-dimensional framework structure with oxygen as a trifurcated acceptor atom (Fig. 2).

Related literature

The six-coordinate complex of 4-pyridylacetate ligands has similar octahedral geometry (Li et al., 2004; Du et al., 2006).

For related literature, see: Aakeröy et al. (1999); Evans & Lin (2002); Tong et al. (2003).

S2. Experimental

A mixture of 3-pyridylacetic acid hydrochloride (0.0434 g, 0.25 mmol), Cu(ClO₄)₂.6H₂O(0.0555 g, 0.15 mmol), NaClO₄.6H₂O (0.0300 g, 0.13 mmol), NaOH (0.0200 g, 0.5 mmol), THF (10 ml) and water (5 ml) was sealed in a 25 ml Teflon-lined stainless-steel reactor and heated to 333 K for 96 h, yielding blue crystals of (I) suitable for X-ray analysis. Elemental analysis for C₁₄H₁₆CuN₂O₆, calculated: C 45.22, H 4.34, N 7.53%; found: C 44.61, H 5.44, N 7.13%.

S3. Refinement

H atoms of the water molecules were located in a difference map. H atoms bonded to C atoms were placed at calulated positions and treated using a riding-model approximation [C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C)].

Computing details

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

Figures

	Fig. 1. Principal connectivity of the coordination polymer two-dimensional structure (I) on (2 1 2), showing 50% probability displacement ellipsoids. All H atoms except H1 have been omitted for clarity. Symmetry codes: (i) -x + 1,-y + 1,-z + 1.
	Fig. 2. Intermolecular hydrogen bonding contacts between the two-dimensional polymer layers in ac plane. For clarity, only H1, H2, and H5 were used. Symmetry codes: (ii) x - 1/2,-y + 3/2,z - 1/2; (iii) 1 - x,2 - y,1 - z; (iv) -x,2 - y,1 - z..

Poly[trans-diaquabis(µ₂-3-pyridylacetato)copper(II)]

Crystal data

[Cu(C7H6NO2)2(H2O)2]n	F(000) = 382
Mr = 371.83	Dx = 1.682 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 748 reflections
a = 9.0672 (18) Å	θ = 2.8–25.1°
b = 8.6022 (17) Å	µ = 1.52 mm^−1
c = 9.601 (2) Å	T = 298 K
β = 101.335 (3)°	Block, blue
V = 734.2 (3) Å^3	0.70 × 0.38 × 0.09 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	1284 independent reflections
Radiation source: fine-focus sealed tube	821 reflections with I > σ(I)
Graphite monochromator	Rint = 0.071
φ and ω scans	θmax = 25.0°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Bruker, 1998)	h = −10→9
Tmin = 0.416, Tmax = 0.875	k = −10→10
3558 measured reflections	l = −9→11

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.117	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0387P)^2 + 0.9264P] where P = (Fo^2 + 2Fc^2)/3
1284 reflections	(Δ/σ)max < 0.001
106 parameters	Δρmax = 0.79 e Å^−3
0 restraints	Δρmin = −0.72 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
Cu1	0.5000	0.5000	0.5000	0.0263 (3)
N1	0.3098 (5)	0.5766 (6)	0.5596 (5)	0.0278 (11)
O1	0.5329 (4)	0.7068 (4)	0.4238 (4)	0.0316 (10)
O2	0.6976 (4)	0.8160 (5)	0.5997 (4)	0.0444 (11)
O3	0.6312 (4)	0.5530 (5)	0.7405 (4)	0.0418 (12)
H1	0.6716	0.6365	0.7190	0.063*
H2	0.6890	0.4905	0.7941	0.063*
C1	0.6225 (6)	0.8136 (7)	0.4763 (6)	0.0280 (14)
C2	0.6336 (7)	0.9518 (7)	0.3801 (6)	0.0384 (17)
H2A	0.5428	1.0136	0.3719	0.046*
H2B	0.7176	1.0163	0.4244	0.046*
C3	0.2837 (6)	0.5449 (7)	0.6883 (5)	0.0293 (15)
H3	0.3553	0.4885	0.7509	0.035*
C4	0.1545 (6)	0.5920 (6)	0.7331 (6)	0.0263 (13)
C5	0.0475 (6)	0.6698 (7)	0.6372 (6)	0.0353 (15)
H5	−0.0428	0.6987	0.6620	0.042*
C6	0.0737 (6)	0.7049 (8)	0.5056 (6)	0.0402 (16)
H6	0.0037	0.7614	0.4415	0.048*
C7	0.2058 (6)	0.6550 (7)	0.4693 (6)	0.0338 (15)
H7	0.2228	0.6767	0.3789	0.041*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0300 (5)	0.0278 (6)	0.0254 (5)	−0.0014 (6)	0.0157 (4)	−0.0012 (5)
N1	0.029 (3)	0.029 (3)	0.027 (3)	−0.002 (2)	0.011 (2)	−0.002 (2)
O1	0.041 (2)	0.027 (3)	0.029 (2)	−0.009 (2)	0.0141 (18)	−0.0047 (18)
O2	0.048 (2)	0.044 (3)	0.039 (3)	−0.005 (2)	0.003 (2)	0.003 (2)
O3	0.043 (2)	0.045 (3)	0.035 (2)	−0.003 (2)	0.0032 (19)	−0.0014 (18)
C1	0.029 (3)	0.035 (4)	0.026 (3)	0.008 (3)	0.019 (3)	0.002 (3)
C2	0.044 (3)	0.044 (5)	0.034 (3)	−0.004 (3)	0.022 (3)	−0.002 (3)
C3	0.030 (3)	0.036 (4)	0.023 (3)	0.004 (3)	0.008 (2)	0.003 (2)
C4	0.031 (3)	0.021 (3)	0.032 (3)	−0.003 (3)	0.017 (3)	−0.002 (3)
C5	0.027 (3)	0.043 (4)	0.038 (4)	0.002 (3)	0.013 (3)	−0.004 (3)
C6	0.034 (3)	0.049 (5)	0.038 (4)	0.010 (3)	0.008 (3)	0.005 (3)
C7	0.041 (3)	0.038 (4)	0.024 (3)	−0.001 (3)	0.010 (3)	0.001 (3)

Geometric parameters (Å, º)

Cu1—O1^i	1.968 (4)	C2—C4^ii	1.508 (7)
Cu1—O1	1.968 (4)	C2—H2A	0.9700
Cu1—N1^i	2.031 (4)	C2—H2B	0.9700
Cu1—N1	2.031 (4)	C3—C4	1.385 (7)
Cu1—O3^i	2.424 (4)	C3—H3	0.9300
Cu1—O3	2.424 (4)	C4—C5	1.373 (7)
N1—C3	1.331 (6)	C4—C2^iii	1.508 (7)
N1—C7	1.332 (7)	C5—C6	1.364 (7)
O1—C1	1.263 (7)	C5—H5	0.9300
O2—C1	1.245 (6)	C6—C7	1.380 (7)
O3—H1	0.8500	C6—H6	0.9300
O3—H2	0.8500	C7—H7	0.9300
C1—C2	1.521 (8)
O1^i—Cu1—O1	180.00 (10)	O2—C1—C2	118.4 (5)
O1^i—Cu1—N1^i	90.59 (17)	O1—C1—C2	116.1 (5)
O1—Cu1—N1^i	89.41 (17)	C4^ii—C2—C1	114.1 (5)
O1^i—Cu1—N1	89.41 (17)	C4^ii—C2—H2A	108.7
O1—Cu1—N1	90.59 (17)	C1—C2—H2A	108.7
N1^i—Cu1—N1	180.000 (1)	C4^ii—C2—H2B	108.7
O1^i—Cu1—O3^i	95.85 (14)	C1—C2—H2B	108.7
O1—Cu1—O3^i	84.15 (14)	H2A—C2—H2B	107.6
N1^i—Cu1—O3^i	87.45 (15)	N1—C3—C4	122.9 (5)
N1—Cu1—O3^i	92.55 (15)	N1—C3—H3	118.5
O1^i—Cu1—O3	84.15 (14)	C4—C3—H3	118.5
O1—Cu1—O3	95.85 (14)	C5—C4—C3	117.6 (5)
N1^i—Cu1—O3	92.55 (15)	C5—C4—C2^iii	123.2 (5)
N1—Cu1—O3	87.45 (15)	C3—C4—C2^iii	119.1 (5)
O3^i—Cu1—O3	180.000 (1)	C6—C5—C4	120.0 (5)
C3—N1—C7	118.4 (5)	C6—C5—H5	120.0
C3—N1—Cu1	120.7 (4)	C4—C5—H5	120.0
C7—N1—Cu1	120.8 (4)	C5—C6—C7	118.8 (6)
C1—O1—Cu1	129.9 (4)	C5—C6—H6	120.6
Cu1—O3—H1	94.7	C7—C6—H6	120.6
Cu1—O3—H2	125.9	N1—C7—C6	122.1 (5)
H1—O3—H2	116.0	N1—C7—H7	118.9
O2—C1—O1	125.5 (5)	C6—C7—H7	118.9
O1^i—Cu1—N1—C3	46.4 (4)	Cu1—O1—C1—C2	172.3 (3)
O1—Cu1—N1—C3	−133.6 (4)	O2—C1—C2—C4^ii	133.6 (5)
O3^i—Cu1—N1—C3	142.2 (4)	O1—C1—C2—C4^ii	−48.2 (7)
O3—Cu1—N1—C3	−37.8 (4)	C7—N1—C3—C4	−1.2 (8)
O1^i—Cu1—N1—C7	−131.1 (4)	Cu1—N1—C3—C4	−178.8 (4)
O1—Cu1—N1—C7	48.9 (4)	N1—C3—C4—C5	2.5 (8)
O3^i—Cu1—N1—C7	−35.3 (4)	N1—C3—C4—C2^iii	179.0 (5)
O3—Cu1—N1—C7	144.7 (4)	C3—C4—C5—C6	−3.2 (9)
N1^i—Cu1—O1—C1	−78.0 (4)	C2^iii—C4—C5—C6	−179.6 (6)
N1—Cu1—O1—C1	102.0 (4)	C4—C5—C6—C7	2.8 (9)
O3^i—Cu1—O1—C1	−165.5 (4)	C3—N1—C7—C6	0.6 (9)
O3—Cu1—O1—C1	14.5 (4)	Cu1—N1—C7—C6	178.2 (4)
Cu1—O1—C1—O2	−9.7 (8)	C5—C6—C7—N1	−1.4 (9)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1···O2	0.85	1.96	2.762 (6)	156
O3—H2···O2^iv	0.85	1.98	2.826 (6)	170
C5—H5···O2^v	0.93	2.52	3.366 (7)	151

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