Dipotassium tetra­aqua­bis­(μ-citrato-κ4O:O′,O′′,O′′′)nickelate(II) tetra­hydrate

Yao, H.-G.; Huang, J.-N.; Deng, R.-K.; Yao, Z.-B.

doi:10.1107/S1600536813022630

metal-organic compounds

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ISSN: 2056-9890

Volume 69| Part 9| September 2013| Pages m502-m503

doi:10.1107/S1600536813022630

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Dipotassium tetraaquabis(μ-citrato-κ⁴O:O′,O′′,O′′′)nickelate(II) tetrahydrate

Hua-Gang Yao,^a ^* Jia-Na Huang,^a Run-Kang Deng ^a and Zhi-Bang Yao ^a

^aSchool of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Guangdong 528458, People's Republic of China
^*Correspondence e-mail: yaohg518@126.com

(Received 3 July 2013; accepted 12 August 2013; online 17 August 2013)

The title complex, K₂[Ni₂(C₆H₅O₇)₂(H₂O)₄]·4H₂O, is a dinuclear centrosymmetric anionic octahedral complex, involving citrates as tridentate and bridging ligands, and coordinating water molecules. An extensive network of hydrogen bonds connects the complex anions through the two unique uncoordinating water molecules. The K⁺ counter cation is surrounded by seven O atoms in the form of an irregular polyhedron and further stabilizes the crystal packing.

Related literature

For applications of structures with metal-organic frameworks, see: Chui et al. (1999 ); Kahn & Martinez (1998 ); Kiang et al. (1999 ); Lin et al. (1999 ). For metal coordination polymers with a variety of topologies, see: Kondo et al. (2000 ); Shin et al. (2003 ); Wu et al. (2003 ); Yao et al. (2007 ). For the nickel–citrate complex K₂[Ni(C₆H₅O₇)(H₂O)₂]₂·4H₂O, which crystallized in the triclinic space group P $[\overline{1}]$ , see: Baker et al. (1983 ).

Experimental

Crystal data

K₂[Ni₂(C₆H₅O₇)₂(H₂O)₄]·4H₂O
M_r = 717.94
Monoclinic, P 2₁ /c
a = 10.616 (2) Å
b = 13.006 (3) Å
c = 9.0513 (18) Å
β = 93.09 (3)°
V = 1247.8 (4) Å³
Z = 2
Mo Kα radiation
μ = 1.94 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.15 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2001 ) T_min = 0.636, T_max = 0.741
9515 measured reflections
3128 independent reflections
2916 reflections with I > 2σ(I)
R_int = 0.017

Refinement

R[F² > 2σ(F²)] = 0.023
wR(F²) = 0.063
S = 1.02
3128 reflections
224 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.55 e Å⁻³

Table 1
Selected bond lengths (Å)

Ni1—O4	2.0322 (12)
Ni1—O2	2.0330 (11)
Ni1—O6	2.0345 (10)
Ni1—O2W	2.0677 (12)
Ni1—O1W	2.0709 (11)
Ni1—O3	2.0927 (10)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1WB⋯O2ⁱ	0.79 (3)	1.96 (3)	2.7322 (16)	167 (2)
O2W—H2WB⋯O1ⁱⁱ	0.84 (3)	1.93 (3)	2.7638 (16)	170 (2)
O4W—H4WB⋯O5ⁱⁱⁱ	0.85 (3)	1.91 (3)	2.7459 (17)	171 (2)
O2W—H2WA⋯O4W^iv	0.88 (3)	1.83 (3)	2.7064 (18)	174 (2)
O4W—H4WA⋯O5^v	0.72 (3)	2.20 (2)	2.8714 (19)	155 (2)
O3—H1⋯O6^vi	0.75 (2)	2.13 (2)	2.7152 (15)	135 (2)
O3W—H3WA⋯O2W^vii	0.85 (1)	2.25 (4)	2.912 (2)	135 (5)
Symmetry codes: (i) -x, -y+1, -z; (ii) $[x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (iii) $[-x, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) $[-x, y-{\script{1\over 2}}, -z-{\script{1\over 2}}]$ ; (v) $[x-1, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (vi) -x+1, -y+1, -z; (vii) $[-x, y+{\script{1\over 2}}, -z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536813022630/kp2456sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813022630/kp2456Isup2.hkl

checkCIF report

Comment top

The construction of metal–organic frameworks (MOFs) is an area of intense research activity due to their intriguing structural diversity and potential applications as zeolitic, optoelectronic, magnetic and conducting materials (Chui et al., 1999; Kiang et al., 1999; Kahn & Martinez, 1998; Lin et al., 1999). Depending on the conformation of carbon chains, the functional group of organic ligands and the type of metal ions, a variety of metal coordination polymers with different topological structures, such as one-dimensional chains (Shin et al., 2003), two-dimensional grids (Kondo et al., 2000), three-dimensional porous motifs (Yao et al., 2007) and helical strands (Wu et al., 2003) were observed. In this paper, we report the synthesis of a dimeric nickel(II) citrate complex by self-assembly under hydrothermal conditions.

In the crystal the centrosymmetric structural unit is a dinuclear Ni^II anion (Fig. 1) and the two potassium cations, and crystalline water molecules. The crystallographic unit is a half of the structural unit. The Ni^II ion adopts an octahedral coordination mode. One citrate ligand is bound with an hydroxyl and two carboxylate groups to the Ni^II ion, whereas one O atom (O6) from a carboxylate group of a symmetry-related citrate ligand occupies another apex, and two water molecules complete the octahedral environment. The Ni—O distances range from 2.0322 (12) Å to 2.0927 (10) Å (Table 1). Neighbouring dimeric complexes are consolidated into a three-dimensional structure by hydrogen bonds (Table 2, Fig. 2). The crystallographically independent potassium cation, K1, is seven-coordinated by O atoms, with an average contact distance of 2.852 Å.

The corresponding nickel–citrate complex with the triclinic space group P1, K₂[Ni(C₆H₅O₇)(H₂O)₂]₂.4H₂O, has been reported (Baker et al., 1983). The complex exists as centrosymmetric dimers, which has identical structure with the title complex, but a difference is that the potassium ions and water molecules of crystallization occupy the spaces between the nickel–citrate dimers in the two cases, resulting in the different formation of the geometry of potassium ion and hydrogen bonds.

Related literature top

For applications of structures with metal-organic frameworks, see: Chui et al. (1999); Kahn & Martinez (1998); Kiang et al. (1999); Lin et al. (1999). For metal coordination polymers with a variety of topologies, see: Kondo et al. (2000); Shin et al. (2003); Wu et al. (2003); Yao et al. (2007). For the nickel–citrate complex K₂[Ni(C₆H₅O₇)(H₂O)₂]₂.4H₂O, which crystallized in the triclinic space group P1, see: Baker et al. (1983).

Experimental top

Citric acid monohydrate (0.048 g), NiCl₂.6H₂O (0.042 g) and KOH (0.027 g) were dissolved in 6 ml mixed solvent of DMF–H₂0 (2:1 v/v), which were placed in a small vial. The mixture was heated at 351 K for 3 d and then cooled to room temperature. Green block crystals of the product were collected by filtration and washed with ethanol several times (88% based on Ni). This synthetic route allowed us to obtain a pure phase. Elemental analysis, calculated (%) for title compound: C 20.06, H 3.62; found C 20.35, H 3.44.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The structure of the dimeric complex anion, with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity.
	Fig. 2. Dimeric complexes are consolidated into three-dimensional structures by hydrogen bonds. Symmetry code: -x, 1/2 + y, 1/2 - z

Dipotassium tetraaquabis(µ-citrato-κ⁴O:O',O'',O''')nickelate(II) tetrahydrate top

Crystal data top

K₂[Ni₂(C₆H₅O₇)₂(H₂O)₄]·4H₂O	Z = 2
M_r = 717.94	F(000) = 736
Monoclinic, P2₁/c	D_x = 1.911 Mg m⁻³
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 10.616 (2) Å	µ = 1.94 mm⁻¹
b = 13.006 (3) Å	T = 293 K
c = 9.0513 (18) Å	Block, green
β = 93.09 (3)°	0.30 × 0.20 × 0.15 mm
V = 1247.8 (4) Å³

Data collection top

Bruker SMART APEXII CCD diffractometer	3128 independent reflections
Radiation source: fine-focus sealed tube	2916 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.017
ϕ and ω scans	θ_max = 28.4°, θ_min = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	h = −14→12
T_min = 0.636, T_max = 0.741	k = −17→17
9515 measured reflections	l = −12→12

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.023	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.063	H-atom parameters constrained
S = 1.02	w = 1/[σ²(F_o²) + (0.0378P)² + 0.4504P] where P = (F_o² + 2F_c²)/3
3128 reflections	(Δ/σ)_max = 0.001
224 parameters	Δρ_max = 0.43 e Å⁻³
2 restraints	Δρ_min = −0.55 e Å⁻³

Crystal data top

K₂[Ni₂(C₆H₅O₇)₂(H₂O)₄]·4H₂O	V = 1247.8 (4) Å³
M_r = 717.94	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 10.616 (2) Å	µ = 1.94 mm⁻¹
b = 13.006 (3) Å	T = 293 K
c = 9.0513 (18) Å	0.30 × 0.20 × 0.15 mm
β = 93.09 (3)°

Data collection top

Bruker SMART APEXII CCD diffractometer	3128 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	2916 reflections with I > 2σ(I)
T_min = 0.636, T_max = 0.741	R_int = 0.017
9515 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.023	2 restraints
wR(F²) = 0.063	H-atom parameters constrained
S = 1.02	Δρ_max = 0.43 e Å⁻³
3128 reflections	Δρ_min = −0.55 e Å⁻³
224 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

	x	y	z	U_iso*/U_eq
Ni1	0.243734 (14)	0.519202 (13)	−0.006123 (17)	0.01642 (7)
K1	−0.13777 (3)	0.90086 (3)	0.14726 (4)	0.03020 (9)
O1	0.07698 (9)	0.76820 (8)	0.19256 (13)	0.0290 (2)
O2	0.12630 (9)	0.63014 (8)	0.06472 (12)	0.0256 (2)
O3	0.38530 (9)	0.63022 (8)	−0.02002 (10)	0.01756 (18)
O4	0.32413 (10)	0.51024 (8)	0.20239 (12)	0.0247 (2)
O5	0.43183 (11)	0.60531 (8)	0.37004 (11)	0.0278 (2)
O6	0.37540 (9)	0.41901 (8)	−0.07541 (12)	0.0240 (2)
O7	0.25885 (11)	0.27918 (10)	−0.11481 (19)	0.0503 (4)
O1W	0.11765 (10)	0.40268 (8)	0.03601 (12)	0.0235 (2)
O2W	0.16893 (11)	0.54135 (9)	−0.21942 (12)	0.0238 (2)
O3W	−0.00587 (17)	0.89783 (14)	−0.11374 (17)	0.0549 (4)
O4W	−0.32069 (13)	0.97832 (11)	−0.06745 (14)	0.0336 (3)
C1	0.15547 (12)	0.71310 (10)	0.13242 (14)	0.0187 (2)
C2	0.29093 (12)	0.75171 (10)	0.13945 (16)	0.0202 (3)
C3	0.39866 (11)	0.67514 (10)	0.12633 (13)	0.0160 (2)
C4	0.38568 (12)	0.58926 (10)	0.24245 (14)	0.0181 (2)
C5	0.47751 (12)	0.26558 (11)	−0.14594 (16)	0.0197 (3)
C6	0.36067 (12)	0.32483 (11)	−0.11019 (15)	0.0212 (3)
H1	0.444 (2)	0.6015 (17)	−0.036 (2)	0.040 (6)*
H2A	0.2987 (17)	0.8014 (15)	0.067 (2)	0.030 (5)*
H2B	0.3039 (17)	0.7872 (16)	0.227 (2)	0.031 (5)*
H5A	0.4817 (18)	0.2059 (16)	−0.090 (2)	0.033 (5)*
H5B	0.4680 (17)	0.2407 (15)	−0.249 (2)	0.029 (5)*
H1WB	0.047 (2)	0.4026 (18)	0.003 (2)	0.048 (6)*
H1WA	0.152 (2)	0.354 (2)	−0.006 (3)	0.065 (8)*
H2WA	0.220 (2)	0.525 (2)	−0.290 (3)	0.057 (7)*
H2WB	0.140 (2)	0.601 (2)	−0.235 (3)	0.055 (7)*
H3WC	−0.003 (3)	0.8359 (11)	−0.141 (4)	0.096 (11)*
H3WA	−0.073 (3)	0.906 (4)	−0.168 (5)	0.18 (2)*
H4WA	−0.372 (2)	0.948 (2)	−0.100 (3)	0.041 (6)*
H4WB	−0.351 (2)	1.0134 (19)	0.001 (3)	0.053 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ni1	0.01296 (10)	0.01699 (11)	0.01930 (10)	−0.00081 (6)	0.00068 (6)	−0.00159 (6)
K1	0.02800 (17)	0.03044 (18)	0.03236 (17)	0.00154 (13)	0.00338 (13)	−0.00315 (13)
O4	0.0277 (5)	0.0229 (5)	0.0230 (5)	−0.0075 (4)	−0.0032 (4)	0.0043 (4)
O3	0.0162 (4)	0.0189 (4)	0.0176 (4)	0.0000 (4)	0.0014 (3)	−0.0016 (3)
O6	0.0158 (4)	0.0174 (5)	0.0390 (6)	0.0003 (4)	0.0041 (4)	−0.0049 (4)
O2	0.0151 (4)	0.0257 (5)	0.0358 (5)	0.0002 (4)	0.0014 (4)	−0.0107 (4)
O5	0.0335 (6)	0.0305 (6)	0.0188 (5)	−0.0038 (4)	−0.0047 (4)	−0.0002 (4)
O1	0.0182 (5)	0.0257 (5)	0.0438 (6)	0.0019 (4)	0.0077 (4)	−0.0090 (5)
C5	0.0148 (6)	0.0170 (6)	0.0273 (7)	−0.0008 (5)	0.0012 (5)	−0.0021 (5)
C6	0.0155 (6)	0.0201 (6)	0.0281 (6)	−0.0004 (5)	0.0018 (5)	−0.0029 (5)
C2	0.0152 (6)	0.0169 (6)	0.0286 (7)	0.0014 (5)	0.0011 (5)	−0.0030 (5)
O7	0.0178 (5)	0.0321 (7)	0.1024 (12)	−0.0080 (5)	0.0151 (6)	−0.0266 (7)
C1	0.0149 (6)	0.0201 (6)	0.0209 (6)	0.0015 (5)	0.0006 (4)	0.0004 (5)
C3	0.0136 (5)	0.0167 (6)	0.0175 (5)	0.0004 (4)	0.0004 (4)	−0.0021 (4)
C4	0.0147 (6)	0.0196 (6)	0.0201 (6)	0.0019 (5)	0.0009 (4)	0.0005 (5)
O1W	0.0150 (5)	0.0245 (5)	0.0308 (5)	−0.0034 (4)	0.0016 (4)	−0.0013 (4)
O2W	0.0265 (5)	0.0223 (5)	0.0224 (5)	−0.0007 (4)	−0.0003 (4)	0.0012 (4)
O3W	0.0621 (10)	0.0611 (10)	0.0421 (8)	0.0235 (8)	0.0082 (7)	−0.0023 (7)
O4W	0.0313 (6)	0.0412 (7)	0.0287 (6)	−0.0052 (5)	0.0048 (5)	−0.0084 (5)

Geometric parameters (Å, º) top

Ni1—O4	2.0322 (12)	O1—C1	1.2462 (16)
Ni1—O2	2.0330 (11)	C5—C6	1.5100 (18)
Ni1—O6	2.0345 (10)	C5—C3^v	1.5259 (18)
Ni1—O2W	2.0677 (12)	C5—H5B	0.984 (18)
Ni1—O1W	2.0709 (11)	C5—H5A	0.93 (2)
Ni1—O3	2.0927 (10)	C6—O7	1.2320 (17)
K1—O7ⁱ	2.6796 (13)	C2—C1	1.5213 (18)
K1—O3W	2.8108 (17)	C2—C3	1.5259 (17)
K1—O4ⁱⁱ	2.8425 (12)	C2—H2B	0.925 (19)
K1—O4W	2.8557 (16)	C2—H2A	0.926 (19)
K1—O1Wⁱⁱ	2.8633 (13)	O7—K1ⁱ	2.6796 (13)
K1—O1	2.8708 (12)	C3—C5^v	1.5259 (18)
K1—O3Wⁱⁱⁱ	3.053 (2)	C3—C4	1.5449 (18)
O4—C4	1.2606 (17)	O1W—K1^iv	2.8633 (13)
O4—K1^iv	2.8425 (12)	O1W—H1WB	0.79 (3)
O3—C3	1.4477 (15)	O1W—H1WA	0.83 (3)
O3—H1	0.75 (2)	O4W—H4WB	0.85 (3)
O6—C6	1.2723 (17)	O4W—H4WA	0.72 (3)
O2W—H2WB	0.84 (3)	O3W—K1ⁱⁱⁱ	3.053 (2)
O2W—H2WA	0.88 (3)	O3W—H3WC	0.842 (10)
O2—C1	1.2707 (17)	O3W—H3WA	0.845 (10)
O5—C4	1.2475 (17)

O4—Ni1—O2	88.95 (5)	C1—O2—Ni1	128.10 (9)
O4—Ni1—O6	89.34 (5)	C1—O1—K1	145.86 (10)
O2—Ni1—O6	174.20 (4)	C6—C5—C3^v	115.44 (11)
O4—Ni1—O2W	174.86 (4)	C6—C5—H5B	109.1 (11)
O2—Ni1—O2W	89.11 (5)	C3^v—C5—H5B	108.7 (11)
O6—Ni1—O2W	92.12 (5)	C6—C5—H5A	109.1 (12)
O4—Ni1—O1W	91.73 (5)	C3^v—C5—H5A	110.1 (12)
O2—Ni1—O1W	92.74 (5)	H5B—C5—H5A	103.7 (16)
O6—Ni1—O1W	92.85 (5)	O7—C6—O6	124.63 (13)
O2W—Ni1—O1W	93.12 (5)	O7—C6—C5	118.43 (13)
O4—Ni1—O3	80.12 (4)	O6—C6—C5	116.93 (12)
O2—Ni1—O3	89.07 (5)	C1—C2—C3	119.47 (11)
O6—Ni1—O3	85.17 (4)	C1—C2—H2B	107.3 (12)
O2W—Ni1—O3	95.08 (4)	C3—C2—H2B	108.4 (12)
O1W—Ni1—O3	171.62 (4)	C1—C2—H2A	108.7 (11)
O7ⁱ—K1—O3W	98.82 (5)	C3—C2—H2A	107.8 (11)
O7ⁱ—K1—O4ⁱⁱ	98.49 (4)	H2B—C2—H2A	104.2 (16)
O3W—K1—O4ⁱⁱ	143.18 (4)	C6—O7—K1ⁱ	147.10 (10)
O7ⁱ—K1—O4W	85.94 (5)	O1—C1—O2	123.20 (12)
O3W—K1—O4W	77.54 (5)	O1—C1—C2	116.40 (12)
O4ⁱⁱ—K1—O4W	71.58 (4)	O2—C1—C2	120.38 (11)
O7ⁱ—K1—O1Wⁱⁱ	97.26 (5)	O3—C3—C2	107.32 (10)
O3W—K1—O1Wⁱⁱ	145.89 (5)	O3—C3—C5^v	110.58 (10)
O4ⁱⁱ—K1—O1Wⁱⁱ	62.15 (4)	C2—C3—C5^v	107.80 (11)
O4W—K1—O1Wⁱⁱ	133.61 (4)	O3—C3—C4	108.84 (10)
O7ⁱ—K1—O1	82.13 (4)	C2—C3—C4	108.91 (10)
O3W—K1—O1	71.57 (5)	C5^v—C3—C4	113.21 (11)
O4ⁱⁱ—K1—O1	143.15 (3)	O5—C4—O4	125.05 (13)
O4W—K1—O1	144.57 (4)	O5—C4—C3	117.64 (12)
O1Wⁱⁱ—K1—O1	81.15 (4)	O4—C4—C3	117.23 (11)
O7ⁱ—K1—O3Wⁱⁱⁱ	167.85 (5)	Ni1—O1W—K1^iv	100.16 (5)
O3W—K1—O3Wⁱⁱⁱ	69.78 (6)	Ni1—O1W—H1WB	122.5 (17)
O4ⁱⁱ—K1—O3Wⁱⁱⁱ	89.00 (4)	K1^iv—O1W—H1WB	113.6 (16)
O4W—K1—O3Wⁱⁱⁱ	87.41 (5)	Ni1—O1W—H1WA	99.7 (18)
O1Wⁱⁱ—K1—O3Wⁱⁱⁱ	94.69 (4)	K1^iv—O1W—H1WA	116.3 (18)
O1—K1—O3Wⁱⁱⁱ	97.62 (4)	H1WB—O1W—H1WA	104 (2)
C4—O4—Ni1	113.92 (9)	K1—O4W—H4WB	87.9 (17)
C4—O4—K1^iv	129.32 (9)	K1—O4W—H4WA	123.4 (19)
Ni1—O4—K1^iv	101.83 (4)	H4WB—O4W—H4WA	107 (2)
C3—O3—Ni1	104.99 (7)	K1—O3W—K1ⁱⁱⁱ	110.22 (6)
C3—O3—H1	109.4 (17)	K1—O3W—H3WC	107 (2)
Ni1—O3—H1	106.2 (17)	K1ⁱⁱⁱ—O3W—H3WC	140 (2)
C6—O6—Ni1	128.00 (9)	K1—O3W—H3WA	92 (3)
Ni1—O2W—H2WB	114.0 (16)	K1ⁱⁱⁱ—O3W—H3WA	104 (4)
Ni1—O2W—H2WA	115.0 (16)	H3WC—O3W—H3WA	90 (4)
H2WB—O2W—H2WA	109 (2)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WB···O2ⁱ	0.79 (3)	1.96 (3)	2.7322 (16)	167 (2)
O2W—H2WB···O1^vi	0.84 (3)	1.93 (3)	2.7638 (16)	170 (2)
O4W—H4WB···O5ⁱⁱ	0.85 (3)	1.91 (3)	2.7459 (17)	171 (2)
O2W—H2WA···O4W^vii	0.88 (3)	1.83 (3)	2.7064 (18)	174 (2)
O4W—H4WA···O5^viii	0.72 (3)	2.20 (2)	2.8714 (19)	155 (2)
O3—H1···O6^v	0.75 (2)	2.13 (2)	2.7152 (15)	135 (2)
O3W—H3WA···O2W^ix	0.85 (1)	2.25 (4)	2.912 (2)	135 (5)

Symmetry codes: (i) −x, −y+1, −z; (ii) −x, y+1/2, −z+1/2; (v) −x+1, −y+1, −z; (vi) x, −y+3/2, z−1/2; (vii) −x, y−1/2, −z−1/2; (viii) x−1, −y+3/2, z−1/2; (ix) −x, y+1/2, −z−1/2.

Selected bond lengths (Å) top

Ni1—O4	2.0322 (12)	Ni1—O2W	2.0677 (12)
Ni1—O2	2.0330 (11)	Ni1—O1W	2.0709 (11)
Ni1—O6	2.0345 (10)	Ni1—O3	2.0927 (10)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WB···O2ⁱ	0.79 (3)	1.96 (3)	2.7322 (16)	167 (2)
O2W—H2WB···O1ⁱⁱ	0.84 (3)	1.93 (3)	2.7638 (16)	170 (2)
O4W—H4WB···O5ⁱⁱⁱ	0.85 (3)	1.91 (3)	2.7459 (17)	171 (2)
O2W—H2WA···O4W^iv	0.88 (3)	1.83 (3)	2.7064 (18)	174 (2)
O4W—H4WA···O5^v	0.72 (3)	2.20 (2)	2.8714 (19)	155 (2)
O3—H1···O6^vi	0.75 (2)	2.13 (2)	2.7152 (15)	135 (2)
O3W—H3WA···O2W^vii	0.845 (10)	2.25 (4)	2.912 (2)	135 (5)

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

References

Baker, E. N., Baker, H. N., Anderson, B. F. & Reevs, R. D. (1983). Inorg. Chim. Acta, 78, 281–285. CSD CrossRef CAS Web of Science Google Scholar
Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Chui, S. S. Y., Lo, S. M. F., Charmant, J. P. H., Orpen, A. G. & Williams, I. D. (1999). Science, 283, 1148–1150. Web of Science CSD CrossRef PubMed CAS Google Scholar
Kahn, O. & Martinez, C. J. (1998). Science, 279, 44–46. Web of Science CrossRef CAS Google Scholar
Kiang, Y.-H., Gardner, G. B., Lee, S., Xu, Z. & Lobkovsky, E. B. (1999). J. Am. Chem. Soc. 121, 8204–8206. Web of Science CSD CrossRef CAS Google Scholar
Kondo, M., Shimamura, M., Noro, S. I., Minakoshi, S., Asami, A., Seki, K. & Kitagawa, S. (2000). Chem. Mater. 12, 1288–1295. Web of Science CSD CrossRef CAS Google Scholar
Lin, W., Wang, Z. & Ma, L.-J. (1999). J. Am. Chem. Soc. 121, 11249–11251. Web of Science CSD CrossRef CAS Google Scholar
Sheldrick, G. M. (2001). SADABS. University of Gottingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Shin, D.-M., Lee, I.-S., Lee, Y.-A. & Chung, Y.-K. (2003). Inorg. Chem. 42, 2977–2981. Web of Science CSD CrossRef PubMed CAS Google Scholar
Wu, C.-D., Lu, C.-Z., Lin, X., Wu, D.-M., Lu, S.-F., Zhang, H.-H. & Huang, J.-S. (2003). Chem. Commun. pp. 1254–1255. Google Scholar
Yao, H.-G., Ji, M., Ji, S.-H., Jiang, Y.-S., Li, L. & An, Y.-L. (2007). Inorg. Chem. Commun. 10, 440–442. Web of Science CSD CrossRef CAS Google Scholar

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