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In the title compound, {[K2Ni(C5O5)2(H2O)2]·4H2O}n, the Ni atom lies on an inversion centre. Two inversion-related croconate [4,5-dihydroxy-4-cyclo­pentene-1,2,3-trionate(2−)] ligands and an NiII ion form a near-planar symmetrical [Ni(C5O5)2]2− moiety. The near-square coordination centre of the moiety is then extended to an octa­hedral core by vertically bonding two water mol­ecules in the [Ni(C5O5)2(H2O)2]2− coordination anion. The crystal structure is characterized by a three-dimensional network, involving strong K...O...K binding, K...O—Ni binding and hydrogen bonding.

Supporting information


Crystallographic Information File (CIF)
Contains datablocks global, I


Structure factor file (CIF format)
Contains datablock I

CCDC reference: 294318

Comment top

The dianion of 4,5-dihydroxy-4-cyclopentene-1,2,3-trione, C5O52−, commonly refered to as the croconate anion, belongs to the family of cyclic oxocarbons of the formula CnOn2− [n = 3–6 for deltate, squarate, croconate and rhodizonate anions, respectively] (Seitz & Imming, 1992). Previous reports (Brouca-Cabarrecq & Trombe, 1992a or b?) reveal that croconate is a polydentate ligand. The strong and versatile coordination properties of the croconate ligand enable it to bond to metal ions via various modes. The reported structures of croconate transition metal complexes with no other co-ligands apart from water and ammonia show that their coordination modes can be classified into three types, namely a terminal mono-ligand coordination mode (type A in Fig. 1) (Brouca-Cabarrecq & Trombe, 1992a or b?), a symmetric bi-ligand coordination mode (type B in Fig. 1) (Wang et al., 2002) and various bridging coordination modes (types C, D, E and F in Fig. 1) (Cornia et al., 1993; Glick & Dahl, 1966; Brouca-Cabarrecq & Trombe, 1992a or b?; Maji et al., 2003). In this study, the title compound, (I), shows a symmetric coordination mode. To the best of our knowledge, this is the third example of this kind, in addition to [Na2Ni(C5O5)2(H2O)2]·4H2O and [Cu2Ni(C5O5)2(H2O)2]·4H2O (Wang et al., 2002), in the family of croconate complexes.

The [Ni(C5O5)2(H2O)2]2− anion of (I) (Fig. 2) consists of a planar [Ni(C5O5)2]2− moiety with two croconate ligands having a symmetrical bidentate coordination mode, with two water molecules occupying the axial sites of the centrosymmtric octahedral array (Table 1).

There are two K+ ions in (I), one on either side of the planar [Ni(C5O5)2]2− moiety, tightly bound to atoms O4 and O5. The formal molecule in the crystal can then be identified as [K2Ni(C5O5)2(H2O)2]. With four further water molecules of crystallization, the title crystal is thus formulated as [K2Ni(C5O5)2(H2O)2]·4H2O.

The inner five-membered chelate ring is perfectly planar. The two five-membered chelate rings sharing a common central Ni atom are also perfectly co-planar. The least-squares plane derived from these nine co-planar atoms is defined as the molecular plane. On the other hand, the croconate ligand is not planar, with the terminal atom O1 being 0.519 (2) Å and atom C1 being 0.282 (3) Å above the molecular plane. As a result, the [Ni(C5O5)2]2− moiety has a raised-head near-planar conformation. Other nearly co-planar atoms are K and O8 (water), with deviations from the molecular plane of 0.346 (1) and 0.353 (2) Å, respectively.

As a good π-conjugation system, the croconate dianion (`free' ligand) in its simple salt has a planar D5 h conformation with five almost identical C O bonds and five almost identical CC bonds, such as in Rb2C5O5 and Cs2C5O5 crystals (Braga et al., 2002). However, the coordinated ligand in its metal complexes commonly deviates from D5h symmetry. The CO bond involving coordinated O atoms is longer than that for the uncoordinated. In the title complex, the CO bond lengths are in the ranges 1.262 (3)–1.266 (3) Å for the coordinated O atoms, and 1.235 (3)–1.244 (3) Å for the uncoordinated.

Perhaps the major determinant of the packing of the coordination anion is the K···O interactions, and the second is the hydrogen bonding. The [Ni(C5O5)2(H2O)2]2− anions are stacked face-to-face along the b axis. As shown in Figs. 3 and 4, every K+ ion is connected to eight O atoms, with K···O distances varying in the range 2.6737 (19)–3.042 (2) Å; five are croconate O atoms and three are water O atoms. The two shortest K···O contacts are 2.6737 (19) Å (for K···O5) and 2.7410 (19) Å (for K···O4), which are between a K+ ion and the two O atoms from the two ligands of the same coordination anion, indicating very strong binding between the K+ ion and the coordination anion. These two K···O distances can therefore be singled out as being of the intra-molecular type. Based on various short contacts between [Ni(C5O5)2(H2O)2]2− units, one coordination anion (at the centre of Fig. 3) has mainly ten neighbouring anions, interconnected by potassium bridging and hydrogen bonding. Because of centrosymmetry, only five pairs of such inter-anionic interactions need to be considered. The strongest interactions are between the central anion and its neighbour at (−x, 2 − y, 1 − z) along the a axis, with two strong hydrogen bonds [O6—H···O2(−x, 2 − y, 1 − z) and O2···H—O6(−x, 2 − y, 1 − z) of 2.714 (3) Å] and an interaction between three O atoms and one K atom [O4/O5(1 − x, 2 − y, 1 − z)···K1(1 − x, 2 − y, 1 − z)···O1(−x, 2 − y, 1 − z)]. The interactions in this direction are further strengthened by a strong O6—H···O7 hydrogen bond of 2.791 (3) Å. Thus, a one-dimensional chain can be recognized along the [100] direction. There are two other neighbouring anions, each of which is connected to the central anion via an interaction between four O atoms and one K atom. The remaining two inter-anionic interactions are relatively weak, with one interaction between three O atoms and one K atom.

It is noteworthy (Figs. 3 and 4) that the non-coordinated O atoms (O1 and O3) have been effectively involved in O···K binding. This is simply the manifestation of the multi-chelate nature of the croconate ligand. The deviation of the terminal O1 atom from the molecular plane is the effect of a very short K1···O1(1/2 − x, 1/2 + y, 3/2 − z) distance of 2.771 (2) Å. By comparison, the five-membered croconate ring in [Na2Ni(C5O5)2(H2O)2]·4H2O (Wang et al., 2002), which also belongs to coordination mode D, is truly co-planar. This may be because the O···Na interactions in that compound are not as strong as the O···K interactions in (I).

As shown in Fig. 4, there is a two-dimensional network in the (101) plane, which consists of rectangular grids. Along the [010] direction, the zigzag but isometric series of K+ ions is connected by a kind of multi-oxygen-bridging, forming a uniform chain. In the [101] direction (vertical direction in Fig. 4), there is another kind of zigzag chain which is characterized by heteronuclear two-oxygen-bridging between K and Ni. Retrieving the third chain mentioned above along the [100] direction, the crystal structure of (I) definitely has a three-dimensional network.

Hydrogen bonding in the crystal structure of (I) is strong (Table 2), and mainly occurs between water and the O atoms of the croconate ligands. It plays an important role in the formation and stabilization of the three-dimensional structure. For example, the O6—H···O2(−x, 2 − y, 1 − z) and O6—H···O7 hydrogen bonds help to set up intermolecular interactions along the a axis (Fig. 3), while O7(3/2 − x, −1/2 + y, 3/2 − z)—H···O1(1/2 − x, 1/2 + y, 3/2 − z) makes a contribution to hold the chain along the b axis (Fig. 4).

Experimental top

NiCl2·6H2O (0.09 g) dissolved in water (5 ml) was added to a stirred aqueous solution (10 ml) of K2(C5O5)2·3H2O (0.1 g), and the resulting green transparent solution was filtered into a vial at room temperature. Slow evaporation of the filtrate at room temperature gave parallelepiped crystals of (I) after several weeks. Spectroscopic analysis: IR (KBr, ν, cm−1): 1510 (vs), 1589 (s), 1639 (s) [C C and CO hybrid vibration mode in (C5O5)2− plane].

Refinement top

All H atoms were initially located in difference Fourier maps and then allowed to ride on their parent O atoms in the refinement, with O—H distances restrained to 0.85 Å and Uiso(H) = 1.5 Ueq(O).

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The various coordination modes for metal–croconate complexes.
[Figure 2] Fig. 2. The formal [K2Ni(C5O5)2(H2O)2] molecule in the crystal structure of (I), with displacement ellipsoids at the 30% probability level.
[Figure 3] Fig. 3. A view, along the b axis, of the packing diagram of (I). Atoms O1–O5 are the O atoms of the croconate ligand (of which atoms O4 and O5 are coordinated), atom O6 is the coordinated water O atom, and atoms O7 and O8 are the solvent water O atoms. [Symmetry codes: (a) 1 − x, 2 − y, 1 − z; (b) −x, 2 − y, 1 − z; (c) 1 + x, y, z; (d) 1/2 − x, 1/2 + y, 3/2 − z.]
[Figure 4] Fig. 4. The grid formed by the two-dimensional network in the (101) plane. Isometric series of K+ ions in the [010] direction and hetero-metallic series of K+ and NiII ions in [101] direction are connected by two kinds of multi-oxygen-bridging. Note that some atoms have been omitted for clarity. The eight satellite O atoms of a K+ ion are also shown, of which O1, O3, O4 and O5 are from the croconate ligands, while O7 and O8 are from water molecules. [Symmetry codes: (a) 1 − x, 2 − y, 1 − z; (c) 1 + x, y, z; (d) 1/2 − x, 1/2 + y, 3/2 − z; (e) 3/2 − x, −1/2 + y, 3/2 − z.]
Poly[di-µ2-aqua-di-µ5-croconato(2-)-nickel(II)dipotassium(I)] tetrahydrate] top
Crystal data top
[K2Ni(C5O5)2(H2O)2]·4H2OF(000) = 532
Mr = 525.11Dx = 1.982 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 51 reflections
a = 8.0145 (14) Åθ = 4.7–14.3°
b = 6.660 (1) ŵ = 1.66 mm1
c = 16.489 (4) ÅT = 293 K
β = 90.200 (18)°Prism, green
V = 880.1 (3) Å30.40 × 0.38 × 0.20 mm
Z = 2
Data collection top
Siemens P4
1617 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.040
Graphite monochromatorθmax = 27.5°, θmin = 2.8°
ω scansh = 101
Absorption correction: ψ scan
(XSCANS; Siemens, 1996)
k = 81
Tmin = 0.549, Tmax = 0.715l = 2121
2853 measured reflections3 standard reflections every 97 reflections
2022 independent reflections intensity decay: 1%
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)] = 0.036H-atom parameters constrained
wR(F2) = 0.083 w = 1/[σ2(Fo2) + (0.0382P)2 + 0.2576P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
2022 reflectionsΔρmax = 0.31 e Å3
134 parametersΔρmin = 0.59 e Å3
9 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0125 (15)
Crystal data top
[K2Ni(C5O5)2(H2O)2]·4H2OV = 880.1 (3) Å3
Mr = 525.11Z = 2
Monoclinic, P21/nMo Kα radiation
a = 8.0145 (14) ŵ = 1.66 mm1
b = 6.660 (1) ÅT = 293 K
c = 16.489 (4) Å0.40 × 0.38 × 0.20 mm
β = 90.200 (18)°
Data collection top
Siemens P4
1617 reflections with I > 2σ(I)
Absorption correction: ψ scan
(XSCANS; Siemens, 1996)
Rint = 0.040
Tmin = 0.549, Tmax = 0.7153 standard reflections every 97 reflections
2853 measured reflections intensity decay: 1%
2022 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0369 restraints
wR(F2) = 0.083H-atom parameters constrained
S = 1.02Δρmax = 0.31 e Å3
2022 reflectionsΔρmin = 0.59 e Å3
134 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
C10.0110 (3)0.7295 (4)0.60907 (15)0.0210 (5)
K10.65657 (8)1.04861 (9)0.70443 (3)0.02814 (17)
Ni10.50001.00000.50000.02151 (15)
O10.1504 (2)0.6951 (3)0.63834 (11)0.0321 (5)
C20.0271 (3)0.7545 (4)0.52193 (14)0.0190 (5)
O20.0687 (2)0.7232 (3)0.46374 (10)0.0270 (4)
C30.1447 (3)0.7613 (4)0.65577 (15)0.0225 (5)
O30.1622 (2)0.7334 (3)0.72938 (11)0.0362 (5)
C40.1954 (3)0.8315 (4)0.51810 (14)0.0192 (5)
O40.2734 (2)0.8947 (3)0.45655 (10)0.0230 (4)
C50.2666 (3)0.8352 (4)0.59790 (15)0.0203 (5)
O50.4120 (2)0.8999 (3)0.61155 (11)0.0281 (4)
O60.4052 (2)1.2809 (3)0.51875 (12)0.0324 (5)
O70.5671 (3)1.4393 (3)0.65456 (13)0.0390 (5)
O80.9984 (2)1.2280 (3)0.70609 (12)0.0374 (5)
Atomic displacement parameters (Å2) top
C10.0149 (11)0.0248 (13)0.0232 (12)0.0032 (10)0.0018 (10)0.0049 (10)
K10.0311 (3)0.0328 (3)0.0205 (3)0.0035 (3)0.0001 (2)0.0023 (2)
Ni10.0138 (2)0.0331 (3)0.0177 (2)0.0078 (2)0.00246 (17)0.0005 (2)
O10.0164 (9)0.0499 (12)0.0300 (10)0.0078 (9)0.0045 (8)0.0089 (9)
C20.0160 (12)0.0193 (11)0.0216 (12)0.0018 (10)0.0008 (10)0.0014 (10)
O20.0191 (9)0.0403 (11)0.0214 (9)0.0059 (8)0.0020 (7)0.0001 (8)
C30.0183 (12)0.0275 (13)0.0218 (13)0.0025 (11)0.0010 (10)0.0027 (11)
O30.0282 (10)0.0612 (14)0.0193 (9)0.0086 (10)0.0009 (8)0.0092 (10)
C40.0165 (12)0.0215 (12)0.0197 (12)0.0001 (10)0.0041 (10)0.0004 (10)
O40.0176 (9)0.0344 (10)0.0171 (8)0.0066 (8)0.0035 (7)0.0011 (8)
C50.0145 (11)0.0251 (13)0.0214 (12)0.0039 (10)0.0019 (10)0.0003 (10)
O50.0180 (9)0.0451 (11)0.0213 (9)0.0108 (9)0.0011 (7)0.0008 (9)
O60.0174 (9)0.0401 (11)0.0396 (11)0.0039 (9)0.0012 (8)0.0064 (9)
O70.0414 (12)0.0360 (11)0.0399 (12)0.0087 (10)0.0114 (10)0.0041 (9)
O80.0335 (11)0.0506 (13)0.0281 (10)0.0045 (10)0.0028 (9)0.0001 (9)
Geometric parameters (Å, º) top
C1—O11.240 (3)Ni1—O5i2.0819 (18)
C1—C21.479 (3)Ni1—O52.0819 (18)
C1—C31.479 (3)C2—O21.244 (3)
K1—O52.6737 (19)C2—C41.445 (3)
K1—O4i2.7410 (19)C3—O31.235 (3)
K1—O1ii2.771 (2)C3—C51.454 (3)
K1—O72.821 (2)C4—O41.266 (3)
K1—O8iii2.880 (2)C4—C51.432 (3)
K1—O82.989 (2)C5—O51.262 (3)
K1—O1iv3.022 (2)O6—H10.8504
K1—O3ii3.042 (2)O6—H20.8492
Ni1—O6i2.043 (2)O7—H30.8490
Ni1—O62.043 (2)O7—H40.8485
Ni1—O4i2.0722 (17)O8—H50.8500
Ni1—O42.0722 (17)O8—H60.8481
O1—C1—C2126.1 (2)O8—K1—K1iii89.27 (5)
O1—C1—C3125.7 (2)O1iv—K1—K1iii44.44 (4)
C2—C1—C3108.2 (2)O3ii—K1—K1iii121.53 (5)
C2—C1—K1v163.94 (17)O7iii—K1—K1iii44.76 (4)
C3—C1—K1v82.84 (14)C1ii—K1—K1iii94.76 (5)
O5—K1—O4i69.42 (6)K1vi—K1—K1iii115.09 (3)
O5—K1—O1ii130.61 (6)O6i—Ni1—O6180.000 (1)
O4i—K1—O1ii149.54 (6)O6i—Ni1—O4i92.08 (7)
O5—K1—O789.41 (7)O6—Ni1—O4i87.92 (7)
O4i—K1—O769.10 (6)O6i—Ni1—O487.92 (7)
O1ii—K1—O786.70 (7)O6—Ni1—O492.08 (7)
O5—K1—O8iii72.66 (6)O4i—Ni1—O4180.0
O4i—K1—O8iii133.51 (6)O6i—Ni1—O5i91.85 (8)
O1ii—K1—O8iii76.85 (6)O6—Ni1—O5i88.15 (8)
O7—K1—O8iii136.36 (6)O4i—Ni1—O5i84.14 (7)
O5—K1—O8145.44 (6)O4—Ni1—O5i95.86 (7)
O4i—K1—O876.29 (6)O6i—Ni1—O588.15 (8)
O1ii—K1—O882.54 (6)O6—Ni1—O591.85 (8)
O7—K1—O882.30 (6)O4i—Ni1—O595.86 (7)
O8iii—K1—O8133.54 (5)O4—Ni1—O584.14 (7)
O5—K1—O1iv83.11 (6)O5i—Ni1—O5180.0
O4i—K1—O1iv69.59 (6)O6i—Ni1—K1i84.54 (6)
O1ii—K1—O1iv128.50 (5)O6—Ni1—K1i95.46 (6)
O7—K1—O1iv138.01 (6)O4i—Ni1—K1i130.92 (5)
O8iii—K1—O1iv80.18 (6)O4—Ni1—K1i49.08 (5)
O8—K1—O1iv81.04 (6)O5i—Ni1—K1i47.24 (5)
O5—K1—O3ii74.96 (6)O5—Ni1—K1i132.76 (5)
O4i—K1—O3ii117.82 (6)C1—O1—K1v116.65 (16)
O1ii—K1—O3ii60.26 (5)C1—O1—K1vii117.36 (17)
O7—K1—O3ii61.21 (6)K1v—O1—K1vii85.76 (5)
O8iii—K1—O3ii75.63 (6)O2—C2—C4126.8 (2)
O8—K1—O3ii127.30 (6)O2—C2—C1126.9 (2)
O1iv—K1—O3ii151.19 (6)C4—C2—C1106.2 (2)
O5—K1—O7iii144.48 (6)O3—C3—C5128.4 (2)
O4i—K1—O7iii125.16 (6)O3—C3—C1125.6 (2)
O1ii—K1—O7iii55.28 (6)C5—C3—C1105.9 (2)
O7—K1—O7iii125.48 (6)C3—O3—K1v108.71 (16)
O8iii—K1—O7iii76.36 (6)O4—C4—C5122.3 (2)
O8—K1—O7iii57.78 (6)O4—C4—C2128.1 (2)
O1iv—K1—O7iii74.82 (6)C5—C4—C2109.5 (2)
O3ii—K1—O7iii113.61 (5)C4—O4—Ni1105.65 (15)
O5—K1—C1ii112.59 (6)C4—O4—K1i157.76 (16)
O4i—K1—C1ii150.67 (6)Ni1—O4—K1i96.09 (6)
O1ii—K1—C1ii18.42 (5)O5—C5—C4122.3 (2)
O7—K1—C1ii81.59 (6)O5—C5—C3128.4 (2)
O8iii—K1—C1ii70.12 (6)C4—C5—C3109.3 (2)
O8—K1—C1ii99.35 (6)C5—O5—Ni1105.51 (16)
O1iv—K1—C1ii139.13 (6)C5—O5—K1154.61 (16)
O3ii—K1—C1ii42.60 (5)Ni1—O5—K197.90 (7)
O7iii—K1—C1ii71.40 (6)Ni1—O6—H1117.7
O5—K1—K1vi143.83 (5)Ni1—O6—H2110.9
O4i—K1—K1vi100.01 (4)H1—O6—H2109.3
O1ii—K1—K1vi49.80 (5)K1—O7—K1vi80.10 (6)
O7—K1—K1vi55.13 (5)K1—O7—H3104.7
O8iii—K1—K1vi126.47 (5)K1vi—O7—H372.0
O8—K1—K1vi46.58 (4)K1—O7—H4133.2
O1iv—K1—K1vi126.90 (5)K1vi—O7—H481.0
O3ii—K1—K1vi80.79 (5)H3—O7—H4109.4
O7iii—K1—K1vi70.35 (4)K1vi—O8—K184.49 (5)
C1ii—K1—K1vi60.20 (5)K1vi—O8—H5116.7
O5—K1—K1iii100.48 (5)K1—O8—H594.3
O4i—K1—K1iii113.97 (5)K1vi—O8—H697.6
O1ii—K1—K1iii87.07 (5)K1—O8—H6151.8
O7—K1—K1iii170.10 (5)H5—O8—H6109.4
O8iii—K1—K1iii48.93 (4)
Symmetry codes: (i) x+1, y+2, z+1; (ii) x+1/2, y+1/2, z+3/2; (iii) x+3/2, y1/2, z+3/2; (iv) x+1, y, z; (v) x+1/2, y1/2, z+3/2; (vi) x+3/2, y+1/2, z+3/2; (vii) x1, y, z.
Hydrogen-bond geometry (Å, º) top
O6—H1···O2viii0.851.892.714 (3)164
O7—H3···O8vi0.852.293.043 (3)149
O7—H4···O1ix0.852.152.847 (3)140
O8—H5···O2i0.852.042.877 (3)167
O8—H6···O3vi0.852.072.917 (3)173
O6—H2···O70.851.952.791 (3)169
Symmetry codes: (i) x+1, y+2, z+1; (vi) x+3/2, y+1/2, z+3/2; (viii) x, y+2, z+1; (ix) x+1, y+1, z.

Experimental details

Crystal data
Chemical formula[K2Ni(C5O5)2(H2O)2]·4H2O
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)8.0145 (14), 6.660 (1), 16.489 (4)
β (°) 90.200 (18)
V3)880.1 (3)
Radiation typeMo Kα
µ (mm1)1.66
Crystal size (mm)0.40 × 0.38 × 0.20
Data collection
DiffractometerSiemens P4
Absorption correctionψ scan
(XSCANS; Siemens, 1996)
Tmin, Tmax0.549, 0.715
No. of measured, independent and
observed [I > 2σ(I)] reflections
2853, 2022, 1617
(sin θ/λ)max1)0.650
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.083, 1.02
No. of reflections2022
No. of parameters134
No. of restraints9
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.31, 0.59

Computer programs: XSCANS (Siemens, 1996), XSCANS, SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), SHELXL97.

Selected bond lengths (Å) top
C1—O11.240 (3)Ni1—O62.043 (2)
C1—C21.479 (3)Ni1—O42.0722 (17)
C1—C31.479 (3)Ni1—O52.0819 (18)
K1—O52.6737 (19)C2—O21.244 (3)
K1—O4i2.7410 (19)C2—C41.445 (3)
K1—O1ii2.771 (2)C3—O31.235 (3)
K1—O72.821 (2)C3—C51.454 (3)
K1—O8iii2.880 (2)C4—O41.266 (3)
K1—O82.989 (2)C4—C51.432 (3)
K1—O1iv3.022 (2)C5—O51.262 (3)
K1—O3ii3.042 (2)
Symmetry codes: (i) x+1, y+2, z+1; (ii) x+1/2, y+1/2, z+3/2; (iii) x+3/2, y1/2, z+3/2; (iv) x+1, y, z.
Hydrogen-bond geometry (Å, º) top
O6—H1···O2v0.851.892.714 (3)164
O7—H3···O8vi0.852.293.043 (3)149
O7—H4···O1vii0.852.152.847 (3)140
O8—H5···O2i0.852.042.877 (3)167
O8—H6···O3vi0.852.072.917 (3)173
O6—H2···O70.851.952.791 (3)169
Symmetry codes: (i) x+1, y+2, z+1; (v) x, y+2, z+1; (vi) x+3/2, y+1/2, z+3/2; (vii) x+1, y+1, z.

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