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The title nickel coordination polymer, [Ni(C4H2O4)(C5H5N)(H2O)]n, has been obtained from the reaction of NiCl2·6H2O with disodium maleate and pyridine in an alcohol–water solution. Single-crystal X-ray analysis revealed that each Ni atom contains an approximately octahedral coordination environment in the compound with the maleate ligand in a novel coordination mode. The molecule has mirror symmetry. O—H...O hydrogen bonds exist in the corrugated two-dimensional structure; this is further extended into a three-dimensional framework via strong non-classical C—H...O interactions between adjacent layers.

Supporting information


Crystallographic Information File (CIF)
Contains datablocks I, global


Structure factor file (CIF format)
Contains datablock I

CCDC reference: 214800

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.012 Å
  • R factor = 0.056
  • wR factor = 0.138
  • Data-to-parameter ratio = 10.7

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ADDSYM reports no extra symmetry

Comment top

In the past decade, polycarboxylate ligands are widely used in the preparation of coordination polymers with open framework structure because they are capable of forming one-, two-, or three-dimensional networks by bridging between metal centers in a number of different manners (Shi et al., 2000; Kepert et al., 2000; Burrows et al., 2000). Maleate is a versatile ligand, which exhibit the ability to coordinate to metal atoms in several ways (Zhang et al., 1999). Nevertheless, NiII or CoII maleato complexes are rare. In order to further investigate the coordination fashion of maleate, a much larger data of this type of compound needs to be obtained. We have recently prepared some new maleate bridged NiII and CoII complexes with pyridine (py) and 2,2'-bipyridine (bipy) as a second ligand. This paper reports the structure of one of them, in which maleic dianion coordinated to metal center in a quite rare coordination mode (Prout et al., 1971; Lis, 1983; Li et al., 1996), namely, [Ni(µ-maleato)(py)(H2O)]n, (I).

As shown in Fig. 1, each six-coordinate central Ni2+ ion is in an approximate octahedral coordination environment, with the two axial coordination positions occupied by O atom of the water molecule and N atom of the pyridine molecule. The Ni—O distances are in the range of 2.060 (4)–2.100 (6) Å and the Ni—N distance is 2.083 (7) Å, with the O—Ni—O(N) angles between 86.8 (2) and 90.8 (2)°. The Ni2+ ion is deviated from the equatorial plane about only 0.074 Å toward the axially coordinated water molecule. O atoms of the maleate dianion coordinated to Ni2+ in two different modes: each carboxyl group of a maleic ligand offers one O atom to chelated a Ni atom to form a seven-membered ring in a boat conformation with the CC distance of 1.33 (1) Å; while the two remaining O atoms of the same maleate ligand bridged to the other two Ni atoms. As a result, the Ni2+ ions are bridged by maleic anions in a rarely tetra-dentate coordination fashion with a syn-anti coplanar conformation of the carboxyl group, forming a two- dimensional corrugated structure. Every four adjacent Ni2+ ions in the layer produce a bended square hole under the linkage of the maleate ligands, with the distance of 5.5 Å between every two adjacent Ni atoms. In addition, there exist two kinds of hydrogen bond interactions in the crystal: (i) intralayer hydrogen bond OW—WA···O1B; (ii) interlayer hydrogen bond C4C(pyridine)–H4AC···OW. Those weak interactions are benefit to the extra stabilization of the crystal structure.

Experimental top

An aqueous solution (10 ml) of NiCl2·6H2O (0.238 g, 1.0 mmol) was added to an alcohol–watter (1:1) solution (10 ml) containing maleic acid (0.116 g, 1.0 mmol) and sodium hydrate (0.080 g, 2.0 mmol) with stirring. After 80 min, pyridine (0.1 ml, 1.2 mmol) was added dropwise into the above reaction mixture and stirred for 30 min, then filtered. The filtrate was finally left at room temperature and single crystals adequate for X-ray diffraction studies were obtained after two weeks.

Data collection: SMART (Siemens, 1996); cell refinement: SMART; data reduction: SMART; Program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; software used to prepare material for publication: SHELXTL97.

Refinement top

H atoms were all located theoretically and refined as riding, except for atom HWA which was refined isotropically.

Computing details top

Data collection: SMART (Siemens, 1996); cell refinement: SMART; data reduction: XPREP/SAINT (Siemens, 1994); program(s) used to solve structure: SHELXTL (Siemens, 1994); program(s) used to refine structure: SHELXTL (Siemens, 1994); molecular graphics: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. A view of (I) with the atomic numbering scheme. Displacement ellipsoids at the 30% probability level. H atoms have been omitted for clarity.
[Figure 2] Fig. 2. Cell packing of (I), viewed down the c axis, showing the hydrogen bonds.
aqua(µ4-maleato-κ4O)pyridylnickel(II) top
Crystal data top
Ni(C4H2O4)(C5H5N)(H2O)]F(000) = 552
Mr = 269.88Dx = 1.780 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 29 reflections
a = 17.9522 (13) Åθ = 2.3–25.0°
b = 7.5712 (5) ŵ = 1.93 mm1
c = 7.4092 (6) ÅT = 293 K
V = 1007.06 (13) Å3Block, green
Z = 40.22 × 0.14 × 0.10 mm
Data collection top
950 independent reflections
Radiation source: fine-focus sealed tube701 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.075
ϕ and ω scansθmax = 25.0°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 2112
Tmin = 0.695, Tmax = 0.824k = 69
3021 measured reflectionsl = 87
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.056Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.138H atoms treated by a mixture of independent and constrained refinement
S = 1.04 w = 1/[σ2(Fo2) + (0.0554P)2 + 5.62P]
where P = (Fo2 + 2Fc2)/3
950 reflections(Δ/σ)max < 0.001
89 parametersΔρmax = 0.49 e Å3
0 restraintsΔρmin = 0.67 e Å3
Crystal data top
Ni(C4H2O4)(C5H5N)(H2O)]V = 1007.06 (13) Å3
Mr = 269.88Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 17.9522 (13) ŵ = 1.93 mm1
b = 7.5712 (5) ÅT = 293 K
c = 7.4092 (6) Å0.22 × 0.14 × 0.10 mm
Data collection top
950 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
701 reflections with I > 2σ(I)
Tmin = 0.695, Tmax = 0.824Rint = 0.075
3021 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0560 restraints
wR(F2) = 0.138H atoms treated by a mixture of independent and constrained refinement
S = 1.04Δρmax = 0.49 e Å3
950 reflectionsΔρmin = 0.67 e Å3
89 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
Ni0.21377 (6)0.25000.76154 (14)0.0199 (4)
OW0.2997 (3)0.25000.5693 (8)0.0251 (15)
N0.1227 (4)0.25000.9358 (9)0.0241 (17)
C10.1293 (5)0.25001.1162 (12)0.030 (2)
C50.0530 (5)0.25000.8700 (13)0.033 (2)
C30.0014 (6)0.25001.1621 (14)0.043 (3)
C20.0691 (5)0.25001.2323 (13)0.034 (2)
C40.0099 (6)0.25000.9770 (14)0.044 (3)
HWA0.289 (4)0.332 (9)0.503 (9)0.06 (3)*
O20.3425 (2)0.5621 (6)1.1137 (6)0.0285 (10)
C60.3246 (3)0.4544 (8)0.9931 (8)0.0192 (13)
C70.3873 (3)0.3375 (8)0.9326 (7)0.0229 (13)
O10.2609 (2)0.4447 (6)0.9216 (6)0.0274 (10)
Atomic displacement parameters (Å2) top
Ni0.0159 (6)0.0217 (5)0.0220 (6)0.0000.0001 (5)0.000
OW0.020 (3)0.031 (4)0.024 (3)0.0000.001 (3)0.000
N0.026 (4)0.022 (4)0.024 (4)0.0000.005 (3)0.000
C10.025 (5)0.043 (6)0.022 (5)0.0000.007 (4)0.000
C50.022 (5)0.053 (6)0.022 (5)0.0000.004 (4)0.000
C30.035 (6)0.056 (7)0.038 (6)0.0000.014 (5)0.000
C20.043 (5)0.039 (5)0.021 (5)0.0000.006 (5)0.000
C40.024 (5)0.073 (8)0.035 (6)0.0000.001 (5)0.000
O20.024 (2)0.028 (2)0.034 (2)0.003 (2)0.0040 (19)0.011 (2)
C60.019 (3)0.017 (3)0.021 (3)0.006 (2)0.001 (3)0.001 (3)
C70.017 (3)0.028 (3)0.024 (3)0.006 (3)0.006 (2)0.001 (3)
O10.019 (2)0.024 (2)0.039 (3)0.0002 (19)0.0032 (19)0.012 (2)
Geometric parameters (Å, º) top
Ni—O2i2.060 (4)C5—H5A0.9300
Ni—O2ii2.060 (4)C3—C21.369 (14)
Ni—O12.072 (4)C3—C41.380 (14)
Ni—O1iii2.072 (4)C3—H3A0.9300
Ni—N2.083 (7)C2—H2A0.9300
Ni—OW2.100 (6)C4—H4A0.9300
OW—HWA0.82 (7)O2—C61.252 (7)
N—C11.342 (11)O2—Niiv2.060 (4)
N—C51.344 (11)C6—O11.263 (6)
C1—C21.381 (13)C6—C71.500 (8)
C1—H1A0.9300C7—C7iii1.325 (12)
C5—C41.379 (13)C7—H7A0.9300
O2i—Ni—O2ii87.3 (2)C2—C1—H1A118.2
O2i—Ni—O1174.60 (16)N—C5—C4123.7 (9)
O2ii—Ni—O190.78 (17)N—C5—H5A118.2
O2i—Ni—O1iii90.78 (17)C4—C5—H5A118.2
O2ii—Ni—O1iii174.60 (16)C2—C3—C4118.6 (10)
O1—Ni—O1iii90.7 (2)C2—C3—H3A120.7
O2i—Ni—N86.83 (19)C4—C3—H3A120.7
O2ii—Ni—N86.83 (19)C3—C2—C1119.1 (9)
O1—Ni—N88.02 (18)C3—C2—H2A120.4
O1iii—Ni—N88.02 (18)C1—C2—H2A120.4
O2i—Ni—OW89.99 (17)C5—C4—C3118.8 (10)
O2ii—Ni—OW89.99 (17)C5—C4—H4A120.6
O1—Ni—OW95.06 (17)C3—C4—H4A120.6
O1iii—Ni—OW95.06 (17)C6—O2—Niiv134.7 (4)
N—Ni—OW175.6 (3)O2—C6—O1124.7 (5)
Ni—OW—HWA103 (5)O2—C6—C7113.9 (5)
C1—N—C5116.3 (8)O1—C6—C7121.3 (5)
C1—N—Ni123.3 (6)C7iii—C7—C6126.1 (3)
C5—N—Ni120.4 (6)C7iii—C7—H7A116.9
N—C1—C2123.5 (9)C6—C7—H7A116.9
N—C1—H1A118.2C6—O1—Ni130.6 (4)
Symmetry codes: (i) x+1/2, y1/2, z1/2; (ii) x+1/2, y+1, z1/2; (iii) x, y+1/2, z; (iv) x+1/2, y+1, z+1/2.
Hydrogen-bond geometry (Å, º) top
OW—HWA···O1ii0.82 (7)2.01 (7)2.780 (5)159 (?)
C4—H4A···OWv0.932.573.435 (12)155
Symmetry codes: (ii) x+1/2, y+1, z1/2; (v) x1/2, y, z+3/2.

Experimental details

Crystal data
Chemical formulaNi(C4H2O4)(C5H5N)(H2O)]
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)293
a, b, c (Å)17.9522 (13), 7.5712 (5), 7.4092 (6)
V3)1007.06 (13)
Radiation typeMo Kα
µ (mm1)1.93
Crystal size (mm)0.22 × 0.14 × 0.10
Data collection
DiffractometerSiemens SMART CCD
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.695, 0.824
No. of measured, independent and
observed [I > 2σ(I)] reflections
3021, 950, 701
(sin θ/λ)max1)0.595
R[F2 > 2σ(F2)], wR(F2), S 0.056, 0.138, 1.04
No. of reflections950
No. of parameters89
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.49, 0.67

Computer programs: SMART (Siemens, 1996), SMART, XPREP/SAINT (Siemens, 1994), SHELXTL (Siemens, 1994), SHELXL97 (Sheldrick, 1997), SHELXL97.

Selected geometric parameters (Å, º) top
Ni—O2i2.060 (4)Ni—O1iii2.072 (4)
Ni—O2ii2.060 (4)Ni—N2.083 (7)
Ni—O12.072 (4)Ni—OW2.100 (6)
O2i—Ni—O2ii87.3 (2)O1—Ni—N88.02 (18)
O2i—Ni—O1174.60 (16)O2i—Ni—OW89.99 (17)
O2ii—Ni—O190.78 (17)O1—Ni—OW95.06 (17)
O1—Ni—O1iii90.7 (2)N—Ni—OW175.6 (3)
O2i—Ni—N86.83 (19)
Symmetry codes: (i) x+1/2, y1/2, z1/2; (ii) x+1/2, y+1, z1/2; (iii) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
OW—HWA···O1ii0.82 (7)2.01 (7)2.780 (5)159(?)
C4—H4A···OWiv0.932.573.435 (12)155
Symmetry codes: (ii) x+1/2, y+1, z1/2; (iv) x1/2, y, z+3/2.

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