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The asymmetric unit of the title compound, {[Cu(C4O4)(C6H6N2O)2(H2O)2]·2H2O}n, consists of one pyridine-4-carbox­amide (isonicotinamide or ina) ligand, one-half of a squarate dianion, a coordinated aqua ligand and a solvent water mol­ecule. Both the CuII and the squarate ions are located on inversion centers. The CuII ions are octa­hedrally surrounded by four O atoms of two water mol­ecules and two squarate anions, and by two N atoms of the isonicotinamide ligands. The crystal structure contains chains of squarate-1,3-bridged CuII ions. These chains are held together by N-H...O and O-H...O inter­molecular hydrogen-bond inter­actions, forming an extensive three-dimensional network.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270105008164/sk1824sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270105008164/sk1824Isup2.hkl
Contains datablock I

CCDC reference: 273022

Comment top

The coordination chemistry of the squarate anion has attracted increasing attention because it gives rise to a wide variety of complexes and adopts mono- or polydentate coordination modes when acting as a ligand towards first row transition metal ions. The squarate anion does not behave like a chelating ligand but rather like a bridge between two or more metal atoms, ??as a singly or multiply monodentate ligand (Bernardinelli et al., 1989; Castro et al., 1999; Crispini et al., 2000). In all the cases described so far, each coordination site of squaric acid is coordinated to a different metal atom and either a one-dimensional chain or three-dimensional polymers are obtained (Hilberts et al., 1996; Greve & Nather, 2002; Greve et al., 2003). The exchange interactions in such polymer complexes, between transition-metal ions through extended bridging squarate groups, have been studied by both inorganic and bioinorganic chemists in recent years (Van Ooijen et al., 1978; Reinprecht et al., 1980; Yufit et al., 1999; Trombe et al., 2002). We have also used isonicotinamide as a second ligand; this pyridine derivate with an amide group (–CONH2) in the γ-position possesses strong antitubercular, antipyretic, fibrinolytic and antibacterial properties. Because of their strong pharmacological effects, mixed salts of isonicotinamide find extensive use as drugs in various biological and medicinal processes (Ahuja & Prasad, 1976). Isonicotinamide is also of interest in inorganic chemistry, since the ligand has three donor sites, viz. (i) the pyridine ring N atom, as in the title complex, (ii) the amine N atom and (iii) the carbonyl O atom, acting as a monodentate ligand. To our knowledge, there are only a few reports of the complexes of this ligand with transition metals(II) (Baum et al., 2002). Despite of the structural and magnetic interest, only a few crystal structures containing copper(II) squarate and geometrically demanding N-atom donor ligands have been investigated (Solans et al., 1990; Graf et al., 1997; Bernardinelli et al., 1989). In our ongoing research on squaric acid, we have synthesized some mixed ligand-copper(II) complexes of squaric acid and their structures have been reported. In these compounds, squaric acid behaves as a counter-anion or monodendate ligand (Uçar et al., 2004; Bulut et al., 2004), while in the title compound, (I), it acts as a bridging ligand between the copper(II) ions.

The coordination polyhedron of copper in (I) is best described as a distorted octahedron (Fig. 1). Each Cu atom is trans-connected to two molecules of ina [Cu1—N1 = 2.0029 (14) Å], two aqua ligands [Cu1—O4 = 2.4698 (18) Å] and two squarate O atoms [Cu1—O1 = 1.9921 (11) Å]. In the title complex there are also two solvent water molecules. The metal atoms are connected by the squarate dianions via µ-O,O coordination, forming `zigzag' chains in the direction of the crystallographic b axis (Fig 2). Only one O atom of each squarate dianion is involved in metal coordination, and the mode of? direct coordination in which two neighboring O atoms are involved is not found. The Cu atoms are located nearly in the molecular plane of the squarate dianions and are oriented in the direction of the oxygen lone pair.

In the title complex, the Cu1—O1 bond is considerably shorter than the Cu1—O4 bond because of the electronegative character of the C4O42− ligand. The Cu1—O1 bond distance is nearly identical to that observed in [Cu2(C4O4)(phen)4](CF3SO3)2·3H2O (1.995 (7) Å; Castro et al., 1999), whereas this distance is longer that in [Cu(C4O4)(phen)(H2O)2]·2H2O [1.967 (2) Å; phen is 1,10-phenanthroline; Solans et al., 1990]. This difference is clearly due to the fact that the squarate ligand is coordinated to the Cu atom in a monodentate fashion (Solans et al., 1990; Bulut et al., 2004) and therefore most of the negative charge is located on the coordinated O atom.

The squarate dianion is planar, with an r.m.s. deviation of 0.0048 Å, and the largest deviation from the mean plane is 0.0079 (14) Å for atom O??. The dihedral angle between the copper equatorial plane and the squarate plane is 36.86 (8)°. The pyridine ring of the isonicotinamide ligand is essentially planar (the r.m.s. deviation is 0.0087 Å) and the largest deviation from the mean plane is −0.0125 Å for atom C1. The dihedral angle between the pyridine ring and the squarate mean plane is 59.45 (5)°, while that between the pyridine and copper equatorial plane is 85.12 (5)°.

In the extended structure, the NH2 and CO groups of the ina ligand, the aqua ligand and the solvent water molecule, and the uncoordinated squarate O atoms are involved in interchain hydrogen bonding; the polymer chains are connected by interchain N2—H2A···O5(3/2 − x, 1/2 + y, 1/2 − z), N2—H2B···O4(1/2 + x, 3/2 − y, −1/2 + z), O5—H5A···O3(1 − x, 1 − y, −z), and O5—H5B···O2(x, y, z) interactions (Fig. 2). These interactions are also effective in forming a layered structure, and the geometry of the interactions is given in Table 2. The shortest interchain Cu1···Cu1(−x + 1/2,+y − 1/2,-z + 1/2) distance is 7.4251 (6) Å, whereas the the intrachain Cu1···Cu1(x, −1 + y, z) distance is 7.7824 (7) Å.

Experimental top

Squaric acid (0.57 g, 5 mmol) dissolved in water (25 ml) was neutralized with NaOH (0.40 g, 10 mmol) and was added to a hot solution of CuCl2·H2O (0.77 g, 5 mmol) dissolved in water (50 ml). The mixture was stirred at 333 K for 12 h and then cooled to room temperature. The yellow crystals which formed were filtered and washed with water and alcohol and dried in a vacuum. A solution of isonicotinamide (0.24 g, 2 mmol) in methanol (50 ml) was added dropwise with stirring to a suspension of the CuSq·2H2O (0.21 g, 1 mmol) in water (50 ml). The green solution was refluxed for about 2 h and then cooled to room temperature. A few days later, well formed dark-green crystals were selected for X-ray studies.

Refinement top

H atoms attached to C atoms were placed at calculated positions (C—H = 0.93 Å) and were allowed to ride on the parent atom [Uiso(H) = 1.2Ueq(C)]. The remaining H atoms were located in a difference map and their parameters were refined.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. : The molecular structure of (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 code: (vi) 1 − x, 1 − y, 1 − z; (vii) 1 − x, −y, 1 − z; (viii) x, −1 + y, z.]
[Figure 2] Fig. 2. : The zigzag chain structure of the copper(II) complex, with intra- and interchain interactions shown as dashed lines.
catena-Poly[[[diaquabis(pyridine-4-carboxamide-κN)copper(II)]-µ2-squarato- κO1:O3] dihydrate] top
Crystal data top
[Cu(C4O4)(C6H6N2O)2(H2O)2]·2H2OF(000) = 506
Mr = 491.91Dx = 1.641 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 5487 reflections
a = 11.3221 (9) Åθ = 1.8–27.9°
b = 7.7824 (4) ŵ = 1.16 mm1
c = 12.6314 (11) ÅT = 297 K
β = 116.535 (6)°Prism, dark green
V = 995.75 (13) Å30.23 × 0.21 × 0.16 mm
Z = 2
Data collection top
Stoe IPDS-II
diffractometer
2363 independent reflections
Radiation source: fine-focus sealed tube1755 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.058
Detector resolution: 6.67 pixels mm-1θmax = 27.8°, θmin = 2.0°
ω scansh = 1414
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)
k = 1010
Tmin = 0.768, Tmax = 0.843l = 1616
11948 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.027H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.061 w = 1/[σ2(Fo2) + (0.0355P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.89(Δ/σ)max < 0.001
2363 reflectionsΔρmax = 0.44 e Å3
167 parametersΔρmin = 0.47 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.089 (3)
Crystal data top
[Cu(C4O4)(C6H6N2O)2(H2O)2]·2H2OV = 995.75 (13) Å3
Mr = 491.91Z = 2
Monoclinic, P21/nMo Kα radiation
a = 11.3221 (9) ŵ = 1.16 mm1
b = 7.7824 (4) ÅT = 297 K
c = 12.6314 (11) Å0.23 × 0.21 × 0.16 mm
β = 116.535 (6)°
Data collection top
Stoe IPDS-II
diffractometer
2363 independent reflections
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)
1755 reflections with I > 2σ(I)
Tmin = 0.768, Tmax = 0.843Rint = 0.058
11948 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0270 restraints
wR(F2) = 0.061H atoms treated by a mixture of independent and constrained refinement
S = 0.89Δρmax = 0.44 e Å3
2363 reflectionsΔρmin = 0.47 e Å3
167 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
C10.4564 (2)0.5245 (2)0.25617 (16)0.0272 (4)
H10.38310.45790.24390.033*
C20.4706 (2)0.5804 (2)0.15966 (17)0.0309 (4)
H20.40670.55460.08360.037*
C30.5804 (2)0.6752 (2)0.17621 (17)0.0279 (4)
C40.6728 (2)0.7101 (2)0.29081 (17)0.0303 (4)
H40.74890.77160.30510.036*
C50.6507 (2)0.6525 (2)0.38355 (17)0.0263 (4)
H50.71260.67770.46040.032*
C60.5888 (2)0.7436 (3)0.06805 (19)0.0360 (5)
C70.47616 (18)0.1230 (2)0.46798 (14)0.0192 (4)
C80.4363 (2)0.0480 (2)0.41775 (16)0.0217 (4)
N10.54326 (16)0.56161 (18)0.36733 (13)0.0217 (3)
N20.7076 (2)0.7584 (3)0.0742 (2)0.0445 (5)
O10.44275 (14)0.27051 (14)0.42443 (11)0.0251 (3)
O20.35895 (16)0.10482 (15)0.31830 (11)0.0349 (4)
O30.48704 (19)0.7781 (3)0.01906 (14)0.0564 (5)
O40.27134 (16)0.60109 (19)0.38144 (13)0.0313 (3)
O50.5605 (2)0.1112 (3)0.23878 (18)0.0593 (6)
Cu10.50000.50000.50000.01912 (11)
H2A0.774 (3)0.719 (3)0.131 (3)0.041 (7)*
H2B0.720 (3)0.792 (3)0.019 (3)0.053 (8)*
H4A0.286 (3)0.691 (4)0.347 (3)0.059 (8)*
H4B0.235 (3)0.545 (3)0.332 (2)0.041 (8)*
H5A0.540 (4)0.141 (5)0.176 (4)0.094 (14)*
H5B0.511 (5)0.046 (6)0.243 (4)0.13 (2)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0293 (10)0.0270 (10)0.0267 (9)0.0071 (7)0.0138 (8)0.0035 (7)
C20.0334 (12)0.0356 (10)0.0220 (9)0.0056 (9)0.0107 (9)0.0035 (8)
C30.0319 (12)0.0308 (9)0.0239 (9)0.0008 (8)0.0151 (9)0.0032 (7)
C40.0278 (12)0.0356 (10)0.0282 (10)0.0074 (8)0.0132 (9)0.0011 (8)
C50.0254 (11)0.0295 (9)0.0229 (9)0.0031 (7)0.0098 (9)0.0000 (7)
C60.0452 (14)0.0392 (10)0.0269 (10)0.0059 (10)0.0192 (11)0.0032 (8)
C70.0239 (10)0.0146 (6)0.0181 (8)0.0006 (6)0.0084 (8)0.0004 (6)
C80.0278 (11)0.0134 (7)0.0225 (8)0.0011 (6)0.0099 (8)0.0009 (6)
N10.0257 (9)0.0192 (6)0.0217 (7)0.0009 (6)0.0119 (7)0.0002 (5)
N20.0454 (14)0.0639 (13)0.0304 (10)0.0112 (11)0.0224 (11)0.0077 (10)
O10.0363 (8)0.0130 (5)0.0216 (6)0.0007 (5)0.0089 (6)0.0017 (4)
O20.0451 (10)0.0201 (6)0.0220 (7)0.0007 (6)0.0007 (7)0.0019 (5)
O30.0479 (12)0.0880 (13)0.0295 (10)0.0005 (10)0.0138 (10)0.0216 (8)
O40.0364 (9)0.0303 (8)0.0253 (7)0.0024 (6)0.0121 (7)0.0047 (6)
O50.0511 (13)0.0868 (15)0.0392 (11)0.0052 (11)0.0192 (10)0.0172 (10)
Cu10.02873 (19)0.01169 (13)0.01919 (15)0.00055 (14)0.01272 (13)0.00038 (13)
Geometric parameters (Å, º) top
C1—N11.337 (2)C7—O11.256 (2)
C1—C21.370 (2)C7—C81.456 (2)
C1—H10.9300C8—O21.248 (2)
C2—C31.379 (3)N1—Cu12.0029 (14)
C2—H20.9300N2—H2A0.83 (3)
C3—C41.382 (3)N2—H2B0.81 (3)
C3—C61.508 (3)O1—Cu11.9921 (11)
C4—C51.378 (3)O4—H4A0.88 (3)
C4—H40.9300O4—H4B0.72 (3)
C5—N11.341 (2)O4—Cu12.4698 (18)
C5—H50.9300O5—H5A0.76 (4)
C6—O31.216 (3)O5—H5B0.78 (5)
C6—N21.317 (3)
N1—C1—C2122.80 (17)O3—C6—C3118.7 (2)
N1—C1—H1118.6N2—C6—C3117.0 (2)
C2—C1—H1118.6O1—C7—C8132.07 (17)
C1—C2—C3119.44 (18)O2—C8—C7134.75 (17)
C1—C2—H2120.3C1—N1—C5117.78 (15)
C3—C2—H2120.3C1—N1—Cu1119.11 (13)
C2—C3—C4118.23 (17)C5—N1—Cu1122.85 (12)
C2—C3—C6117.97 (18)C6—N2—H2A121.8 (17)
C4—C3—C6123.70 (18)C6—N2—H2B123 (2)
C5—C4—C3119.12 (18)H2A—N2—H2B115 (3)
C5—C4—H4120.4C7—O1—Cu1129.77 (12)
C3—C4—H4120.4H4A—O4—H4B102 (3)
N1—C5—C4122.58 (18)H5A—O5—H5B113 (5)
N1—C5—H5118.7O1—Cu1—N187.85 (5)
C4—C5—H5118.7O1—Cu1—O488.08 (6)
O3—C6—N2124.4 (2)O4—Cu1—N189.90 (6)
N1—C1—C2—C31.8 (3)O1—C7—C8—O20.4 (4)
C1—C2—C3—C40.1 (3)C2—C1—N1—C52.4 (3)
C1—C2—C3—C6176.40 (18)C2—C1—N1—Cu1171.84 (15)
C2—C3—C4—C51.4 (3)C4—C5—N1—C11.0 (3)
C6—C3—C4—C5174.92 (19)C4—C5—N1—Cu1172.96 (14)
C3—C4—C5—N10.8 (3)C8—C7—O1—Cu1178.91 (14)
C2—C3—C6—O330.2 (3)C7—O1—Cu1—N1127.80 (16)
C4—C3—C6—O3146.1 (2)C1—N1—Cu1—O145.88 (14)
C2—C3—C6—N2148.5 (2)C5—N1—Cu1—O1140.23 (15)
C4—C3—C6—N235.2 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···O5i0.83 (3)2.04 (3)2.871 (3)176 (2)
N2—H2B···O4ii0.81 (3)2.23 (3)3.036 (2)174 (3)
O4—H4A···O2iii0.88 (3)1.90 (3)2.750 (2)163 (3)
O4—H4B···O2iv0.72 (3)2.07 (3)2.790 (2)175 (3)
O5—H5A···O3v0.76 (4)1.97 (4)2.720 (3)172 (4)
O5—H5B···O20.78 (5)2.59 (5)3.330 (3)160 (5)
Symmetry codes: (i) x+3/2, y+1/2, z+1/2; (ii) x+1/2, y+3/2, z1/2; (iii) x, y+1, z; (iv) x+1/2, y+1/2, z+1/2; (v) x+1, y+1, z.

Experimental details

Crystal data
Chemical formula[Cu(C4O4)(C6H6N2O)2(H2O)2]·2H2O
Mr491.91
Crystal system, space groupMonoclinic, P21/n
Temperature (K)297
a, b, c (Å)11.3221 (9), 7.7824 (4), 12.6314 (11)
β (°) 116.535 (6)
V3)995.75 (13)
Z2
Radiation typeMo Kα
µ (mm1)1.16
Crystal size (mm)0.23 × 0.21 × 0.16
Data collection
DiffractometerStoe IPDS-II
diffractometer
Absorption correctionIntegration
(X-RED32; Stoe & Cie, 2002)
Tmin, Tmax0.768, 0.843
No. of measured, independent and
observed [I > 2σ(I)] reflections
11948, 2363, 1755
Rint0.058
(sin θ/λ)max1)0.657
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.027, 0.061, 0.89
No. of reflections2363
No. of parameters167
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.44, 0.47

Computer programs: X-AREA (Stoe & Cie, 2002), X-AREA, X-RED32 (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top
N1—Cu12.0029 (14)O4—Cu12.4698 (18)
O1—Cu11.9921 (11)
O1—Cu1—N187.85 (5)O4—Cu1—N189.90 (6)
O1—Cu1—O488.08 (6)
C1—C2—C3—C40.1 (3)O1—C7—C8—O20.4 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···O5i0.83 (3)2.04 (3)2.871 (3)176 (2)
N2—H2B···O4ii0.81 (3)2.23 (3)3.036 (2)174 (3)
O4—H4A···O2iii0.88 (3)1.90 (3)2.750 (2)163 (3)
O4—H4B···O2iv0.72 (3)2.07 (3)2.790 (2)175 (3)
O5—H5A···O3v0.76 (4)1.97 (4)2.720 (3)172 (4)
O5—H5B···O20.78 (5)2.59 (5)3.330 (3)160 (5)
Symmetry codes: (i) x+3/2, y+1/2, z+1/2; (ii) x+1/2, y+3/2, z1/2; (iii) x, y+1, z; (iv) x+1/2, y+1/2, z+1/2; (v) x+1, y+1, z.
 

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