Magnesium and nickel(II) furan-2,5-dicarboxyl­ate

The salts hexa­aqua­magnesium furan-2,5-dicarboxyl­ate, [Mg(H₂O)₆](C₆H₂O₅), (I), and hexa­aqua­nickel furan-2,5-di­carboxyl­ate, [Ni(H₂O)₆](C₆H₂O₅), (II), provide the first crystallographic characterization of the furan-2,5-dicarboxyl­ate dianion. Both structures exhibit extensive three-dimensional hydrogen-bonding networks between the octa­hedral coordinated hexa­aquametal(II) ions and the dicarboxyl­ate anions. Although the two structures are not isomorphous, they contain essentially identical two-dimensional slabs. The distinction between the structures is that these slabs are related by translation in (II), whereas adjacent slabs in (I) are reflected relative to each other by the action of a glide plane. The reflection occurs so that the local contacts between slabs are not changed, and thus the hydrogen-bond networks are identical except for the orientation of the water mol­ecules at the inter­face between slabs.

S1. Comment

2,5-Furandicarboxylic acid (FDA) has been identified by the US Department of Energy (DOE) biomass programme as one of the 12 chemicals that in the future can be used as a feedstock from biomass in biorefineries (Werpy & Petersen, 2004; Bozell & Petersen, 2010). Owing to the presence of the two carboxylic acid groups, FDA is considered to be a biorenewable building block in the formation of polymers from biomass and therefore may become an alternative to terephthalic, isophthalic and adipic acids, which are all produced from fossil fuel resources (Bozell & Petersen, 2010). In order to be able to use FDA as a building block for polymers, the compound must be of high purity. Herein we show that it is possible to crystallize 2,5-furandicarboxylate as magnesium and nickel salts starting from FDA and the metal carbonates in water.

The title compounds, magnesium(I) and nickel(II) salts of 2,5-furandicarboxylate, have the same molecular structure and the crystals are constitutionally identical. The asymmetric unit comprises one [M(OH₂)₆]²⁺ cation and one 2,5-furandicarboxylate anion. The two structures are illustrated in Figs. 1 and 2, respectively. The metal–water distances in the cations as well as the bond lengths in the dianions are unexceptional. With Mg—O(water) bond lengths of 2.0289 (7)–2.1077 (7) Å and Ni—O(water) bond lengths of 2.0219 (5)–2.0840 (6) Å, all distances are approximately equal to the average bond lengths of previously characterized [M(OH₂)₆]²⁺ complexes (Mg—O 2.0719 Å; Ni—O 2.0589 Å) in the Cambridge Structural Database (CSD; Allen, 2002; version 5.32, November 2010). All bond lengths in the dianions are approximately equal to the bond lengths of the parent 2,5-furandicarboxylic acid (Martuscelli & Pedone, 1968) and also the monoanion in potassium catena(2,5-dicarboxyfuran) (Jaulmes et al., 1982).

The intermolecular interactions are consequently the most interesting features of the structures. The packing in both (I) and (II) is governed by an elaborate three-dimensional hydrogen-bonding scheme. The presence of both an excellent hydrogen-bond donor (aqua ion) and acceptor (dicarboxylate) should lead to strong intermolecular interactions, and in both structures the packing allows short, almost linear O—H···O hydrogen bonds, consistent with strong interactions (Jeffrey, 1997). It is also in the packing that the only significant distinction between the two structures becomes apparent. In (II), all of the 2,5-furandicarboxylate anions are coplanar, whereas in (I) there exists two sets of anions where the molecular planes form an angle of 28.14 (2)° to each other.

Although the two compounds are not isomorphous, there is a very close relationship between them, which is expressed by the cell parameters: c in (I) [18.579 (3) Å] ≈ b in (II) [18.4255 (9) Å], a in (I) [6.6577 (17) Å] ≈ c in (II) [6.5942 (8) Å] and β in (I) = α in (II) = 90°. Consequently, the structures contain almost identical two-dimensional slabs parallel to these specified unit-cell faces. The structures appear essentially identical in projection along the a axis for (I) and along the c axis for (II) (see Figs. 3 and 4). The crystallographic repeat unit of the two-dimensional slabs corresponds to the unit-cell contents of (II) (Fig. 4). In (II), adjacent slabs are related by direct translation along the a axis. This gives rise to a monoclinic structure. In (I), the arrangement is such that the next slab is reflected compared to its neighbour (see Fig. 5), by virtue of the glide planes lying perpendicular to the a axis. The reflection occurs between every slab so that the crystallographic translation encompasses two slabs and is perpendicular to the plane of the slabs. Thus, (I) is orthorhombic. The resulting relationship between the cell parameters in the two structures is: b axis in (I) ≈ [2×a× cos(β - 90)] in (II).

The reflection of adjacent slabs in (I) occurs so that the local contacts between layers are not changed compared to those in (II), i.e. the positions of the atoms in contact between layers remain essentially unchanged. Thus, the hydrogen bonding between slabs is essentially identical in the two structures. The difference is the orientation of the water molecules at the interface between slabs.

This difference in structure for these two compounds with identical composition and comparable size of the metal ion is interesting but difficult to explain. The answer might be a subtle difference in the preferred geometry of the hexaaqua ions as a result of the different d-orbital configuration. The d⁰-configuration of Mg²⁺ does not impose any energetic penalty on the orientation of the coordinated water ligands compared to nickel (d⁸), thus accommodating a packing which leads to a structure with higher symmetry.

Related literature

For related literature, see: Allen (2002); Bozell & Petersen (2010); Gorbanev et al. (2009); Jaulmes et al. (1982); Jeffrey (1997); Martuscelli & Pedone (1968); Paluchowska et al. (1994); Werpy & Petersen (2004).

S2. Experimental

The two compounds were prepared by adaptation of the reported synthesis of the related compound pentaaqua(2-furancarboxylato)nickel(II)(2-furancarboxylate) (Paluchowska et al., 1994). 2,5-Furandicarboxylic acid was prepared as previously described (Gorbanev et al., 2009). The compound was recrystallized in warm water and precipitated with hydrochloric acid before use.

To a hot aqueous solution (10 ml) of 2,5-furandicarboxylic acid (1 mmol, 156 mg) was added the carbonate salt of magnesium or nickel (1 mmol). The solutions were cooled to room temperature. Water was slowly evaporated at room temperature for a few days and colourless (I) or green (II) crystals suitable for X-ray analysis were obtained. Elemental analysis found (calculated): (I) C 24.27% (25.16%), H 4.53% (4.93%); (II) C 22.69% (22.46%), H 4.30% (4.40%).

S3. Refinement

H atoms of the FDA anions were included in idealized positions and refined as riding, with C—H = 0.95 Å and U_iso(H) = 1.2U_eq(C). H atoms of the water molecules were located in a Fourier map and their positions were refined with the O—H distances restrained to 0.85 (2) Å, and with U_iso(H) = 1.2U_eq(O).

Computing details

For both compounds, data collection: COLLECT (Nonius, 1999); cell refinement: COLLECT (Nonius, 1999); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and OLEX2 (Dolomanov et al., 2009).

Figures

	Fig. 1. View of the molecular structure of (I) with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii.
	Fig. 2. View of the molecular structure of (II) with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii.
	Fig. 3. Packing diagram of (I) seen in projection along the a axis. For clarity, the extensive hydrogen-bonding network is not shown.
	Fig. 4. Packing diagram of (II) seen in projection along the c axis. For clarity, the extensive hydrogen-bonding network is not shown.
	Fig. 5. Packing diagram of (I) in projection along the c axis and (II) in projection along the b axis. In (I), the unit-cell repeat along the b axis encompasses two slabs, while in (I) the unit-cell repeat along the a axis encompasses only one slab.

(I) Hexaaquamagnesium(ii) (2,5-furandicarboxylate)

Crystal data

[Mg(OH2)6](C6H2O5)	F(000) = 1200
Mr = 286.48	Dx = 1.698 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 34835 reflections
a = 6.6577 (17) Å	θ = 2.2–37.8°
b = 18.1234 (3) Å	µ = 0.21 mm^−1
c = 18.579 (3) Å	T = 122 K
V = 2241.8 (6) Å^3	Plate, colourless
Z = 8	0.31 × 0.23 × 0.07 mm

Data collection

Nonius KappaCCD diffractometer	5972 independent reflections
Radiation source: fine-focus sealed tube	4551 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.082
ω and ϕ scans	θmax = 37.8°, θmin = 2.2°
Absorption correction: integration (Coppens, 1970)	h = −11→11
Tmin = 0.936, Tmax = 0.986	k = −30→30
107023 measured reflections	l = −31→31

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)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.092	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0373P)^2 + 0.7075P] where P = (Fo^2 + 2Fc^2)/3
5972 reflections	(Δ/σ)max = 0.001
199 parameters	Δρmax = 0.63 e Å^−3
12 restraints	Δρmin = −0.39 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
Mg1	0.08740 (4)	0.153863 (15)	0.415313 (14)	0.00840 (6)
O1	0.08761 (10)	0.06538 (3)	0.34841 (3)	0.01304 (11)
H1A	0.0633 (19)	0.0210 (6)	0.3572 (7)	0.016*
H1B	0.0823 (19)	0.0688 (7)	0.3029 (6)	0.016*
O2	0.10729 (10)	0.24404 (3)	0.48344 (3)	0.01243 (11)
H2A	0.097 (2)	0.2276 (7)	0.5264 (6)	0.015*
H2B	0.1884 (19)	0.2809 (7)	0.4858 (7)	0.015*
O3	−0.15370 (9)	0.12244 (3)	0.48213 (3)	0.01103 (10)
H3A	−0.2385 (18)	0.0946 (6)	0.4636 (6)	0.013*
H3B	−0.1111 (19)	0.1018 (7)	0.5204 (6)	0.013*
O4	0.32049 (9)	0.18971 (3)	0.35173 (3)	0.01233 (11)
H4A	0.3930 (18)	0.2269 (7)	0.3588 (7)	0.015*
H4B	0.3929 (19)	0.1561 (7)	0.3360 (7)	0.015*
O5	0.27399 (10)	0.09377 (4)	0.48307 (3)	0.01549 (12)
H5A	0.244 (2)	0.0751 (7)	0.5209 (6)	0.019*
H5B	0.3753 (19)	0.0711 (7)	0.4670 (7)	0.019*
O6	−0.13612 (9)	0.19410 (3)	0.34671 (3)	0.01196 (10)
H6A	−0.2088 (19)	0.1598 (6)	0.3345 (6)	0.014*
H6B	−0.2038 (19)	0.2319 (6)	0.3524 (7)	0.014*
O11	0.01048 (9)	−0.04770 (3)	0.25621 (3)	0.00899 (10)
O12	0.09522 (9)	0.08005 (3)	0.19312 (3)	0.01174 (10)
O13	0.09398 (9)	0.02701 (3)	0.08340 (3)	0.01187 (10)
O14	−0.01172 (9)	−0.07630 (3)	0.39458 (3)	0.01118 (10)
O15	−0.07711 (9)	−0.19615 (3)	0.37582 (3)	0.01119 (10)
C1	0.07362 (11)	0.02589 (4)	0.15085 (4)	0.00913 (12)
C2	0.01777 (11)	−0.04610 (4)	0.18321 (4)	0.00875 (12)
C3	−0.03056 (12)	−0.11393 (4)	0.15587 (4)	0.01021 (12)
H3	−0.0367	−0.1274	0.1065	0.012*
C4	−0.06995 (12)	−0.16039 (4)	0.21632 (4)	0.00970 (12)
H4	−0.1082	−0.2109	0.2153	0.012*
C5	−0.04146 (11)	−0.11743 (4)	0.27593 (4)	0.00836 (11)
C6	−0.04484 (11)	−0.13071 (4)	0.35420 (4)	0.00842 (12)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mg1	0.00863 (12)	0.00803 (11)	0.00854 (11)	−0.00015 (9)	0.00002 (9)	−0.00038 (8)
O1	0.0212 (3)	0.0080 (2)	0.0099 (2)	−0.0022 (2)	−0.0001 (2)	−0.00110 (17)
O2	0.0150 (3)	0.0110 (2)	0.0112 (2)	−0.0025 (2)	−0.0001 (2)	−0.00155 (19)
O3	0.0109 (2)	0.0124 (2)	0.0098 (2)	−0.00215 (19)	−0.00149 (19)	0.00067 (18)
O4	0.0111 (2)	0.0097 (2)	0.0162 (3)	−0.00146 (19)	0.0036 (2)	−0.00108 (19)
O5	0.0159 (3)	0.0206 (3)	0.0099 (2)	0.0067 (2)	0.0023 (2)	0.0040 (2)
O6	0.0112 (2)	0.0097 (2)	0.0149 (3)	0.00069 (19)	−0.0025 (2)	0.00009 (19)
O11	0.0124 (2)	0.0071 (2)	0.0075 (2)	−0.00150 (18)	0.00070 (18)	0.00015 (16)
O12	0.0143 (3)	0.0092 (2)	0.0117 (2)	−0.00103 (19)	0.0007 (2)	−0.00006 (18)
O13	0.0129 (3)	0.0140 (2)	0.0087 (2)	0.0003 (2)	0.00114 (19)	0.00223 (18)
O14	0.0161 (3)	0.0087 (2)	0.0088 (2)	−0.00145 (19)	0.00014 (19)	−0.00093 (17)
O15	0.0143 (3)	0.0075 (2)	0.0117 (2)	−0.00068 (19)	0.00128 (19)	0.00140 (17)
C1	0.0075 (3)	0.0099 (3)	0.0100 (3)	0.0004 (2)	0.0002 (2)	0.0014 (2)
C2	0.0097 (3)	0.0095 (3)	0.0071 (3)	−0.0001 (2)	0.0010 (2)	0.0001 (2)
C3	0.0113 (3)	0.0107 (3)	0.0087 (3)	−0.0009 (2)	0.0000 (2)	−0.0014 (2)
C4	0.0100 (3)	0.0087 (3)	0.0104 (3)	−0.0009 (2)	0.0003 (2)	−0.0015 (2)
C5	0.0097 (3)	0.0071 (2)	0.0083 (3)	−0.0005 (2)	0.0007 (2)	0.0001 (2)
C6	0.0077 (3)	0.0084 (3)	0.0091 (3)	0.0003 (2)	0.0006 (2)	0.0006 (2)

Geometric parameters (Å, º)

Mg1—O1	2.0289 (7)	O6—H6A	0.819 (11)
Mg1—O2	2.0715 (7)	O6—H6B	0.826 (11)
Mg1—O3	2.1077 (7)	C2—O11	1.3573 (9)
Mg1—O4	2.0556 (7)	C5—O11	1.3605 (9)
Mg1—O5	2.0770 (7)	C1—O12	1.2653 (9)
Mg1—O6	2.0907 (7)	C1—O13	1.2607 (9)
O1—H1A	0.836 (11)	C6—O14	1.2583 (9)
O1—H1B	0.849 (12)	C6—O15	1.2705 (9)
O2—H2A	0.855 (11)	C1—C2	1.4838 (10)
O2—H2B	0.860 (11)	C2—C3	1.3685 (10)
O3—H3A	0.832 (11)	C3—C4	1.4280 (11)
O3—H3B	0.852 (11)	C3—H3	0.9500
O4—H4A	0.839 (11)	C4—C5	1.3669 (10)
O4—H4B	0.831 (11)	C4—H4	0.9500
O5—H5A	0.806 (11)	C5—C6	1.4741 (10)
O5—H5B	0.845 (12)
O1—Mg1—O4	84.10 (3)	H4A—O4—H4B	108.1 (13)
O1—Mg1—O2	176.29 (3)	Mg1—O5—H5A	127.0 (10)
O4—Mg1—O2	93.07 (3)	Mg1—O5—H5B	121.3 (10)
O1—Mg1—O5	87.50 (3)	H5A—O5—H5B	107.5 (13)
O4—Mg1—O5	93.58 (3)	Mg1—O6—H6A	109.0 (9)
O2—Mg1—O5	90.29 (3)	Mg1—O6—H6B	126.8 (9)
O1—Mg1—O6	84.42 (3)	H6A—O6—H6B	110.0 (13)
O4—Mg1—O6	94.40 (3)	C2—O11—C5	107.35 (6)
O2—Mg1—O6	98.21 (3)	O13—C1—O12	126.32 (7)
O5—Mg1—O6	167.99 (3)	O13—C1—C2	116.35 (7)
O1—Mg1—O3	98.50 (3)	O12—C1—C2	117.33 (7)
O4—Mg1—O3	177.22 (3)	O11—C2—C3	110.07 (6)
O2—Mg1—O3	84.37 (3)	O11—C2—C1	115.63 (6)
O5—Mg1—O3	87.53 (3)	C3—C2—C1	134.30 (7)
O6—Mg1—O3	84.91 (3)	C2—C3—C4	106.32 (6)
Mg1—O1—H1A	129.8 (9)	C2—C3—H3	126.8
Mg1—O1—H1B	123.6 (9)	C4—C3—H3	126.8
H1A—O1—H1B	104.9 (13)	C5—C4—C3	106.01 (6)
Mg1—O2—H2A	106.9 (9)	C5—C4—H4	127.0
Mg1—O2—H2B	133.1 (9)	C3—C4—H4	127.0
H2A—O2—H2B	105.8 (12)	O11—C5—C4	110.25 (6)
Mg1—O3—H3A	115.9 (8)	O11—C5—C6	114.91 (6)
Mg1—O3—H3B	110.9 (9)	C4—C5—C6	134.76 (7)
H3A—O3—H3B	107.7 (12)	O14—C6—O15	124.93 (7)
Mg1—O4—H4A	126.7 (9)	O14—C6—C5	117.23 (6)
Mg1—O4—H4B	114.1 (9)	O15—C6—C5	117.83 (6)
Mg1—O1—H1A—H1B	165.0 (14)	Mg1—O4—H4A—H4B	141.2 (13)
Mg1—O2—H2A—H2B	146.0 (10)	Mg1—O5—H5A—H5B	156.8 (14)
Mg1—O3—H3A—H3B	124.9 (11)	Mg1—O6—H6A—H6B	143.1 (11)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O11	0.84 (1)	2.28 (1)	2.7201 (8)	113 (1)
O1—H1B···O12	0.85 (1)	2.05 (1)	2.8978 (9)	175 (1)
O1—H1A···O14	0.84 (1)	1.96 (1)	2.7869 (8)	170 (1)
O2—H2A···O15^i	0.86 (1)	1.91 (1)	2.7624 (9)	177 (1)
O2—H2B···O3^ii	0.86 (1)	2.13 (1)	2.9658 (9)	165 (1)
O3—H3A···O13^iii	0.83 (1)	1.87 (1)	2.7011 (9)	174 (1)
O3—H3B···O14^i	0.85 (1)	1.84 (1)	2.6756 (9)	167 (1)
O4—H4A···O15^iv	0.84 (1)	1.88 (1)	2.7200 (9)	174 (1)
O4—H4B···O12^v	0.83 (1)	2.00 (1)	2.8267 (9)	172 (1)
O5—H5A···O14^i	0.81 (1)	2.21 (1)	2.8839 (9)	142 (1)
O5—H5B···O13^v	0.85 (1)	1.91 (1)	2.7437 (10)	171 (1)
O6—H6A···O12^iii	0.82 (1)	2.01 (1)	2.8318 (9)	176 (1)
O6—H6B···O15^vi	0.83 (1)	2.01 (1)	2.8096 (9)	165 (1)

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

(II) Hexaaquanickel(ii) (2,5-furandicarboxylate)

Crystal data

[Ni(OH2)6](C6H2O5)	F(000) = 664
Mr = 320.88	Dx = 1.945 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 29998 reflections
a = 9.2242 (5) Å	θ = 2.2–45.1°
b = 18.4255 (9) Å	µ = 1.83 mm^−1
c = 6.5942 (8) Å	T = 122 K
β = 102.066 (6)°	Plate, green
V = 1095.99 (15) Å^3	0.46 × 0.24 × 0.03 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	9072 independent reflections
Radiation source: fine-focus sealed tube	7619 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.053
ω and ϕ scans	θmax = 45.1°, θmin = 2.2°
Absorption correction: integration (Gaussian integration; Coppens, 1970)	h = −18→18
Tmin = 0.505, Tmax = 0.950	k = −36→36
68883 measured reflections	l = −13→13

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.060	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ^2(Fo^2) + (0.008P)^2 + 0.4828P] where P = (Fo^2 + 2Fc^2)/3
9072 reflections	(Δ/σ)max = 0.001
199 parameters	Δρmax = 0.73 e Å^−3
12 restraints	Δρmin = −0.87 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
Ni1	0.191537 (9)	0.413277 (5)	0.326955 (13)	0.00661 (2)
O1	0.37555 (6)	0.35091 (3)	0.36385 (9)	0.01125 (8)
H1A	0.4573 (13)	0.3617 (7)	0.431 (2)	0.014*
H1B	0.3730 (15)	0.3058 (6)	0.376 (2)	0.014*
O2	0.00435 (6)	0.47761 (3)	0.25108 (9)	0.01238 (8)
H2A	−0.0667 (14)	0.4820 (7)	0.313 (2)	0.015*
H2B	0.0357 (15)	0.5196 (6)	0.238 (2)	0.015*
O3	0.11800 (6)	0.34921 (3)	0.06949 (8)	0.01087 (8)
H3A	0.0436 (13)	0.3583 (7)	−0.0180 (19)	0.013*
H3B	0.1823 (14)	0.3339 (7)	0.012 (2)	0.013*
O4	0.25782 (6)	0.47912 (3)	0.58678 (8)	0.01039 (8)
H4A	0.3195 (13)	0.4592 (7)	0.6829 (18)	0.012*
H4B	0.2975 (14)	0.5169 (6)	0.554 (2)	0.012*
O5	0.11680 (6)	0.34019 (3)	0.51743 (8)	0.01028 (8)
H5A	0.1859 (14)	0.3268 (7)	0.6121 (19)	0.012*
H5B	0.0464 (13)	0.3511 (7)	0.570 (2)	0.012*
O6	0.28678 (6)	0.48435 (3)	0.15164 (8)	0.01110 (8)
H6A	0.3294 (14)	0.5212 (7)	0.207 (2)	0.013*
H6B	0.3426 (14)	0.4663 (7)	0.0791 (19)	0.013*
C1	0.76421 (7)	0.35682 (3)	0.63886 (9)	0.00744 (8)
O12	0.65495 (6)	0.39796 (3)	0.57216 (8)	0.00984 (8)
O13	0.89499 (6)	0.37838 (3)	0.71385 (8)	0.01033 (8)
C2	0.73699 (7)	0.27795 (3)	0.62444 (9)	0.00751 (8)
O11	0.59692 (5)	0.25824 (3)	0.52969 (8)	0.00808 (7)
C3	0.82335 (7)	0.21777 (4)	0.67803 (10)	0.00872 (9)
H3	0.9247	0.2167	0.7467	0.010*
C4	0.73011 (7)	0.15694 (4)	0.60977 (10)	0.00905 (9)
H4	0.7571	0.1072	0.6236	0.011*
C5	0.59396 (7)	0.18460 (3)	0.52043 (10)	0.00788 (8)
C6	0.45003 (7)	0.15202 (4)	0.41850 (10)	0.00843 (9)
O14	0.34214 (6)	0.19477 (3)	0.35846 (8)	0.01080 (8)
O15	0.44705 (6)	0.08383 (3)	0.40061 (8)	0.01104 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.00602 (3)	0.00660 (3)	0.00720 (3)	0.00026 (2)	0.00134 (2)	0.00007 (2)
O1	0.00727 (17)	0.00887 (19)	0.0165 (2)	0.00114 (15)	0.00004 (15)	0.00093 (16)
O2	0.00967 (19)	0.0123 (2)	0.0156 (2)	0.00321 (16)	0.00355 (16)	0.00186 (17)
O3	0.00848 (18)	0.0139 (2)	0.00975 (17)	0.00052 (16)	0.00089 (14)	−0.00252 (15)
O4	0.01192 (19)	0.00886 (19)	0.00985 (17)	−0.00099 (15)	0.00103 (14)	0.00060 (14)
O5	0.00885 (18)	0.0119 (2)	0.01034 (17)	−0.00048 (15)	0.00270 (14)	0.00179 (15)
O6	0.0138 (2)	0.00850 (18)	0.01233 (19)	−0.00079 (16)	0.00579 (16)	−0.00090 (15)
C1	0.0071 (2)	0.0074 (2)	0.00805 (19)	−0.00042 (17)	0.00212 (16)	−0.00048 (16)
O12	0.00793 (17)	0.00723 (17)	0.01374 (19)	0.00103 (14)	0.00089 (14)	0.00015 (14)
O13	0.00691 (17)	0.01013 (19)	0.01344 (19)	−0.00163 (14)	0.00098 (14)	−0.00146 (15)
C2	0.00641 (19)	0.0075 (2)	0.00836 (19)	−0.00002 (16)	0.00103 (16)	−0.00059 (16)
O11	0.00648 (16)	0.00608 (16)	0.01098 (17)	−0.00015 (13)	0.00025 (13)	−0.00040 (13)
C3	0.0076 (2)	0.0088 (2)	0.0093 (2)	0.00140 (17)	0.00066 (16)	0.00017 (17)
C4	0.0096 (2)	0.0072 (2)	0.0101 (2)	0.00152 (18)	0.00128 (17)	0.00063 (17)
C5	0.0085 (2)	0.0060 (2)	0.0091 (2)	−0.00034 (17)	0.00177 (16)	−0.00020 (16)
C6	0.0087 (2)	0.0085 (2)	0.0083 (2)	−0.00140 (17)	0.00235 (16)	−0.00044 (16)
O14	0.00792 (17)	0.0107 (2)	0.01312 (19)	0.00001 (15)	0.00074 (14)	−0.00033 (15)
O15	0.01271 (19)	0.00747 (18)	0.01318 (19)	−0.00246 (15)	0.00326 (15)	−0.00133 (15)

Geometric parameters (Å, º)

Ni1—O1	2.0219 (5)	O6—H6A	0.831 (11)
Ni1—O2	2.0678 (6)	O6—H6B	0.841 (11)
Ni1—O3	2.0626 (6)	C2—O11	1.3617 (8)
Ni1—O4	2.0840 (6)	C5—O11	1.3583 (8)
Ni1—O5	2.0563 (5)	C1—O12	1.2644 (8)
Ni1—O6	2.0610 (6)	C1—O13	1.2682 (8)
O1—H1A	0.815 (11)	C6—O14	1.2661 (9)
O1—H1B	0.836 (11)	C6—O15	1.2618 (8)
O2—H2A	0.847 (12)	C1—C2	1.4744 (9)
O2—H2B	0.836 (11)	C2—C3	1.3680 (9)
O3—H3A	0.816 (11)	C3—C4	1.4270 (9)
O3—H3B	0.820 (11)	C3—H3	0.9500
O4—H4A	0.842 (11)	C4—C5	1.3692 (9)
O4—H4B	0.835 (11)	C4—H4	0.9500
O5—H5A	0.831 (11)	C5—C6	1.4838 (9)
O5—H5B	0.824 (11)
O1—Ni1—O5	86.24 (2)	H4A—O4—H4B	107.0 (13)
O1—Ni1—O6	89.03 (2)	Ni1—O5—H5A	110.5 (9)
O5—Ni1—O6	174.48 (2)	Ni1—O5—H5B	119.5 (9)
O1—Ni1—O3	84.10 (2)	H5A—O5—H5B	107.7 (13)
O5—Ni1—O3	91.92 (2)	Ni1—O6—H6A	119.2 (9)
O6—Ni1—O3	90.42 (2)	Ni1—O6—H6B	116.8 (9)
O1—Ni1—O2	172.96 (2)	H6A—O6—H6B	106.6 (12)
O5—Ni1—O2	98.84 (2)	O12—C1—O13	124.89 (6)
O6—Ni1—O2	86.12 (2)	O12—C1—C2	117.13 (6)
O3—Ni1—O2	90.84 (2)	O13—C1—C2	117.98 (6)
O1—Ni1—O4	97.89 (2)	O11—C2—C3	110.35 (6)
O5—Ni1—O4	87.55 (2)	O11—C2—C1	115.15 (5)
O6—Ni1—O4	90.29 (2)	C3—C2—C1	134.44 (6)
O3—Ni1—O4	177.90 (2)	C5—O11—C2	107.17 (5)
O2—Ni1—O4	87.24 (2)	C2—C3—C4	105.97 (6)
Ni1—O1—H1A	125.8 (10)	C2—C3—H3	127.0
Ni1—O1—H1B	122.5 (9)	C4—C3—H3	127.0
H1A—O1—H1B	103.4 (13)	C5—C4—C3	106.35 (6)
Ni1—O2—H2A	129.0 (9)	C5—C4—H4	126.8
Ni1—O2—H2B	105.4 (9)	C3—C4—H4	126.8
H2A—O2—H2B	106.5 (13)	O11—C5—C4	110.15 (6)
Ni1—O3—H3A	123.2 (9)	O11—C5—C6	115.61 (5)
Ni1—O3—H3B	115.7 (9)	C4—C5—C6	134.24 (6)
H3A—O3—H3B	109.0 (13)	O15—C6—O14	126.16 (6)
Ni1—O4—H4A	113.6 (9)	O15—C6—C5	116.44 (6)
Ni1—O4—H4B	110.1 (9)	O14—C6—C5	117.41 (6)
Ni1—O1—H1A—H1B	148.4 (13)	Ni1—O4—H4A—H4B	121.7 (11)
Ni1—O2—H2A—H2B	126.6 (13)	Ni1—O5—H5A—H5B	132.2 (11)
Ni1—O3—H3A—H3B	140.7 (13)	Ni1—O6—H6A—H6B	134.9 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1B···O11	0.84 (1)	2.28 (1)	2.7107 (7)	113 (1)
O1—H1A···O12	0.82 (1)	1.98 (1)	2.7929 (8)	173 (1)
O1—H1B···O14	0.84 (1)	2.07 (1)	2.8929 (8)	170 (1)
O2—H2A···O4^i	0.85 (1)	2.13 (1)	2.9510 (8)	163 (1)
O2—H2B···O13^ii	0.84 (1)	1.99 (1)	2.8048 (8)	164 (1)
O3—H3A···O13^iii	0.82 (1)	2.03 (1)	2.8290 (8)	165 (1)
O3—H3B···O14^iv	0.82 (1)	2.02 (1)	2.8409 (8)	175 (1)
O4—H4A···O15^v	0.84 (1)	1.84 (1)	2.6766 (8)	177 (1)
O4—H4B···O12^ii	0.84 (1)	1.87 (1)	2.6885 (8)	166 (1)
O5—H5B···O13^vi	0.82 (1)	1.91 (1)	2.7325 (8)	175 (1)
O5—H5A···O14^v	0.83 (1)	1.97 (1)	2.7997 (8)	173 (1)
O6—H6A···O12^ii	0.83 (1)	2.07 (1)	2.8105 (8)	149 (1)
O6—H6B···O15^iv	0.84 (1)	1.91 (1)	2.7435 (8)	172 (1)

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