Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807049045/hb2530sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807049045/hb2530Isup2.hkl |
CCDC reference: 667153
An aqueous mixture of Ni(OH)2Ni(CO3)24H2O and chelidonic acid in a 1:1 molar ratio yielded dark green blocks of (I) after 15 days, which were washed with ice cold water and dried in air (yield 55%). Elemental analysis found (calc)%: C 23.1 (22.9) H 4.38 (4.40). The % metal content was determined experimentally by complexometric edta titration as 15.88 (16.00).
H atoms bonded to O and C atoms were located in a difference map and refined with distance restraints of O—H = 0.82 (2)–0.92 (2) Å and with Uiso(H) = 1.2Ueq(O) and C—H = 0.92 (2)–0.97 (2) Å and with Uiso(H) = 1.2Ueq(C).
Recently, we reported (Yasodha et al., 2007) a copper complex of the chelidonate (2,6-dicarboxypyranone) dianion arisng from doubly deprotonated 4-pyrone-2,6-dicarboxylic acid in which all the carboxylate oxygen atoms are involved in metal coordination to form a one dimensional polymeric chain. Conversely, in pentaaqua chelidonate copper (II) monohydrate (Manojlovic-Muir et al., 1999), only the carbonyl oxygen atom coordinates to the metal.
As an extension of these studies, we now describe the title compound, (I), which is a hydrated molecular salt (Fig. 1), in which the chelidonate is present as an isolated dianion. The carboxylate groups O5/C6/O6 and O3/C7/O4 form dihedral angles of 7.5 (5)° and 8.51 (8)° with the pyrone ring. The [Ni(H2O)6]2+ complex cation in (I) adopts a distorted octahedral cooordination, with the axial bonds to O9 and O12 slightly longer than the other four Ni—O vertices (Table 1). The Ni—O distances in (I) are shorter than the distances observed in hexaaquanickel (II) bis(p-nitrobenzoate) dihydrate [Ni—O mean distance 2.117 (3) Å] (Qu et al., 2004).
In the crystal a network of O—H···O and possible C—H···O interactions (Table 2, Fig. 2) help to establish the packing in which chains of chelidonate moieties form chains mediated by the complex cations.
For background, see: Manojlovic-Muir et al.(1999); Qu et al. (2004); Yasodha et al. (2007).
Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA (Stoe & Cie, 2002); data reduction: X-RED (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
[Ni(H2O)6](C7H2O6)·H2O | F(000) = 760 |
Mr = 366.91 | Dx = 1.797 Mg m−3 Dm = 1.80 Mg m−3 Dm measured by not measured |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 24142 reflections |
a = 6.9471 (4) Å | θ = 1.8–29.6° |
b = 17.3603 (8) Å | µ = 1.50 mm−1 |
c = 11.6372 (6) Å | T = 150 K |
β = 104.884 (4)° | Block, green |
V = 1356.40 (12) Å3 | 0.53 × 0.46 × 0.37 mm |
Z = 4 |
Stoe IPDSII diffractometer | 3772 independent reflections |
Radiation source: fine-focus sealed tube | 3508 reflections with I > 2σ(I) |
Plane graphite monochromator | Rint = 0.026 |
Detector resolution: 6.67 pixels mm-1 | θmax = 29.5°, θmin = 2.2° |
rotation method scans | h = −9→9 |
Absorption correction: integration (X-RED; Stoe & Cie, 2002) | k = −24→21 |
Tmin = 0.504, Tmax = 0.607 | l = −16→16 |
24142 measured reflections |
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) = 0.057 | All H-atom parameters refined |
S = 1.06 | w = 1/[σ2(Fo2) + (0.028P)2 + 0.7192P] where P = (Fo2 + 2Fc2)/3 |
3772 reflections | (Δ/σ)max < 0.001 |
254 parameters | Δρmax = 0.37 e Å−3 |
0 restraints | Δρmin = −0.52 e Å−3 |
[Ni(H2O)6](C7H2O6)·H2O | V = 1356.40 (12) Å3 |
Mr = 366.91 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.9471 (4) Å | µ = 1.50 mm−1 |
b = 17.3603 (8) Å | T = 150 K |
c = 11.6372 (6) Å | 0.53 × 0.46 × 0.37 mm |
β = 104.884 (4)° |
Stoe IPDSII diffractometer | 3772 independent reflections |
Absorption correction: integration (X-RED; Stoe & Cie, 2002) | 3508 reflections with I > 2σ(I) |
Tmin = 0.504, Tmax = 0.607 | Rint = 0.026 |
24142 measured reflections |
R[F2 > 2σ(F2)] = 0.023 | 0 restraints |
wR(F2) = 0.057 | All H-atom parameters refined |
S = 1.06 | Δρmax = 0.37 e Å−3 |
3772 reflections | Δρmin = −0.52 e Å−3 |
254 parameters |
x | y | z | Uiso*/Ueq | ||
Ni1 | 0.83531 (2) | 0.156381 (8) | 0.903233 (13) | 0.01138 (5) | |
O7 | 0.73282 (13) | 0.08375 (5) | 0.76483 (8) | 0.01506 (16) | |
O8 | 0.55224 (13) | 0.19962 (5) | 0.87631 (8) | 0.01541 (16) | |
O1 | 1.28294 (12) | 0.50673 (5) | 1.06212 (7) | 0.01258 (15) | |
O4 | 1.51202 (15) | 0.66431 (5) | 1.23257 (8) | 0.01940 (18) | |
O12 | 0.76261 (13) | 0.07105 (5) | 1.01155 (8) | 0.01493 (16) | |
O10 | 0.92919 (15) | 0.22779 (6) | 1.04475 (8) | 0.01868 (18) | |
O11 | 1.10798 (13) | 0.10517 (6) | 0.92698 (9) | 0.01829 (18) | |
O5 | 1.13809 (14) | 0.36466 (5) | 1.03685 (8) | 0.01914 (18) | |
O9 | 0.90234 (14) | 0.23487 (5) | 0.78630 (8) | 0.01687 (17) | |
O6 | 1.01691 (14) | 0.38086 (5) | 0.84128 (8) | 0.01823 (17) | |
O3 | 1.45597 (14) | 0.54427 (5) | 1.28379 (8) | 0.01867 (18) | |
O2 | 1.29913 (13) | 0.64282 (5) | 0.78142 (8) | 0.01634 (17) | |
C6 | 1.11182 (17) | 0.40194 (7) | 0.94290 (10) | 0.0133 (2) | |
C7 | 1.45038 (17) | 0.59708 (7) | 1.21020 (10) | 0.0132 (2) | |
C3 | 1.29363 (16) | 0.60099 (7) | 0.86831 (10) | 0.0128 (2) | |
C2 | 1.20278 (17) | 0.52589 (7) | 0.85394 (10) | 0.0132 (2) | |
C1 | 1.20133 (16) | 0.48242 (6) | 0.94934 (10) | 0.0121 (2) | |
C5 | 1.36657 (16) | 0.57785 (6) | 1.07966 (10) | 0.0118 (2) | |
C4 | 1.37612 (17) | 0.62476 (7) | 0.98924 (10) | 0.0132 (2) | |
O13W | 0.92491 (14) | 0.42877 (6) | 0.60517 (9) | 0.02049 (19) | |
H2 | 1.147 (3) | 0.5086 (10) | 0.7770 (16) | 0.021 (4)* | |
H4 | 1.438 (3) | 0.6743 (10) | 1.0046 (16) | 0.022 (4)* | |
H8A | 0.459 (3) | 0.1746 (13) | 0.832 (2) | 0.038 (5)* | |
H8B | 0.542 (3) | 0.2423 (14) | 0.848 (2) | 0.041 (6)* | |
H12A | 0.717 (3) | 0.0277 (14) | 0.972 (2) | 0.046 (6)* | |
H7A | 0.800 (3) | 0.0434 (13) | 0.765 (2) | 0.040 (6)* | |
H10A | 0.956 (3) | 0.2080 (14) | 1.116 (2) | 0.047 (6)* | |
H11A | 1.151 (3) | 0.1121 (12) | 0.869 (2) | 0.038 (5)* | |
H12B | 0.859 (3) | 0.0595 (12) | 1.070 (2) | 0.037 (5)* | |
H11B | 1.201 (3) | 0.1070 (12) | 0.987 (2) | 0.039 (6)* | |
H9A | 0.985 (3) | 0.2188 (12) | 0.7533 (19) | 0.033 (5)* | |
H10B | 1.004 (3) | 0.2645 (14) | 1.044 (2) | 0.043 (6)* | |
H7B | 0.711 (3) | 0.1000 (12) | 0.696 (2) | 0.037 (5)* | |
H9B | 0.944 (3) | 0.2819 (14) | 0.809 (2) | 0.043 (6)* | |
H13A | 1.034 (4) | 0.4180 (16) | 0.585 (2) | 0.068 (8)* | |
H13B | 0.947 (4) | 0.4145 (15) | 0.676 (3) | 0.060 (7)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ni1 | 0.01381 (8) | 0.01007 (8) | 0.00988 (8) | −0.00031 (5) | 0.00237 (5) | 0.00005 (5) |
O7 | 0.0202 (4) | 0.0127 (4) | 0.0112 (4) | 0.0016 (3) | 0.0020 (3) | −0.0015 (3) |
O8 | 0.0159 (4) | 0.0124 (4) | 0.0167 (4) | 0.0008 (3) | 0.0021 (3) | −0.0002 (3) |
O1 | 0.0161 (4) | 0.0107 (4) | 0.0104 (4) | −0.0015 (3) | 0.0024 (3) | −0.0007 (3) |
O4 | 0.0297 (5) | 0.0121 (4) | 0.0137 (4) | −0.0031 (3) | 0.0006 (3) | −0.0009 (3) |
O12 | 0.0180 (4) | 0.0133 (4) | 0.0129 (4) | −0.0010 (3) | 0.0028 (3) | 0.0023 (3) |
O10 | 0.0277 (5) | 0.0151 (4) | 0.0120 (4) | −0.0066 (3) | 0.0029 (3) | −0.0013 (3) |
O11 | 0.0154 (4) | 0.0246 (5) | 0.0141 (4) | 0.0032 (3) | 0.0025 (3) | 0.0021 (4) |
O5 | 0.0280 (5) | 0.0143 (4) | 0.0139 (4) | −0.0056 (3) | 0.0032 (3) | 0.0010 (3) |
O9 | 0.0237 (4) | 0.0119 (4) | 0.0170 (4) | −0.0013 (3) | 0.0088 (3) | 0.0003 (3) |
O6 | 0.0249 (4) | 0.0150 (4) | 0.0131 (4) | −0.0046 (3) | 0.0018 (3) | −0.0019 (3) |
O3 | 0.0264 (4) | 0.0148 (4) | 0.0122 (4) | −0.0043 (3) | 0.0004 (3) | 0.0019 (3) |
O2 | 0.0205 (4) | 0.0156 (4) | 0.0130 (4) | −0.0009 (3) | 0.0045 (3) | 0.0036 (3) |
C6 | 0.0147 (5) | 0.0115 (5) | 0.0138 (5) | −0.0004 (4) | 0.0040 (4) | −0.0013 (4) |
C7 | 0.0152 (5) | 0.0127 (5) | 0.0111 (5) | 0.0005 (4) | 0.0021 (4) | −0.0005 (4) |
C3 | 0.0132 (4) | 0.0127 (5) | 0.0127 (5) | 0.0015 (4) | 0.0037 (4) | 0.0010 (4) |
C2 | 0.0146 (5) | 0.0131 (5) | 0.0116 (5) | 0.0002 (4) | 0.0024 (4) | −0.0012 (4) |
C1 | 0.0122 (4) | 0.0118 (5) | 0.0118 (5) | 0.0007 (4) | 0.0024 (4) | −0.0016 (4) |
C5 | 0.0123 (4) | 0.0099 (5) | 0.0127 (5) | 0.0005 (4) | 0.0023 (4) | −0.0008 (4) |
C4 | 0.0146 (5) | 0.0116 (5) | 0.0132 (5) | −0.0004 (4) | 0.0031 (4) | −0.0007 (4) |
O13W | 0.0180 (4) | 0.0287 (5) | 0.0143 (4) | −0.0006 (4) | 0.0034 (3) | 0.0000 (4) |
Ni1—O7 | 2.0253 (9) | O11—H11B | 0.82 (2) |
Ni1—O10 | 2.0304 (9) | O5—C6 | 1.2431 (15) |
Ni1—O11 | 2.0460 (9) | O9—H9A | 0.82 (2) |
Ni1—O8 | 2.0524 (9) | O9—H9B | 0.88 (2) |
Ni1—O9 | 2.0617 (9) | O6—C6 | 1.2516 (14) |
Ni1—O12 | 2.0894 (9) | O3—C7 | 1.2482 (14) |
O7—H7A | 0.84 (2) | O2—C3 | 1.2536 (14) |
O7—H7B | 0.82 (2) | C6—C1 | 1.5233 (16) |
O8—H8A | 0.84 (2) | C7—C5 | 1.5178 (15) |
O8—H8B | 0.81 (2) | C3—C4 | 1.4370 (16) |
O1—C1 | 1.3563 (13) | C3—C2 | 1.4393 (16) |
O1—C5 | 1.3574 (13) | C2—C1 | 1.3446 (16) |
O4—C7 | 1.2474 (14) | C2—H2 | 0.928 (18) |
O12—H12A | 0.90 (2) | C5—C4 | 1.3457 (16) |
O12—H12B | 0.84 (2) | C4—H4 | 0.957 (18) |
O10—H10A | 0.87 (2) | O13W—H13A | 0.87 (3) |
O10—H10B | 0.82 (2) | O13W—H13B | 0.84 (3) |
O11—H11A | 0.82 (2) | ||
O7—Ni1—O10 | 177.73 (4) | Ni1—O11—H11A | 110.5 (15) |
O7—Ni1—O11 | 87.77 (4) | Ni1—O11—H11B | 126.7 (15) |
O10—Ni1—O11 | 93.58 (4) | H11A—O11—H11B | 109 (2) |
O7—Ni1—O8 | 88.79 (4) | Ni1—O9—H9A | 113.0 (14) |
O10—Ni1—O8 | 89.78 (4) | Ni1—O9—H9B | 122.0 (15) |
O11—Ni1—O8 | 175.64 (4) | H9A—O9—H9B | 104 (2) |
O7—Ni1—O9 | 88.82 (4) | O5—C6—O6 | 126.97 (11) |
O10—Ni1—O9 | 92.97 (4) | O5—C6—C1 | 117.93 (10) |
O11—Ni1—O9 | 91.03 (4) | O6—C6—C1 | 115.09 (10) |
O8—Ni1—O9 | 91.58 (4) | O4—C7—O3 | 126.55 (11) |
O7—Ni1—O12 | 87.03 (4) | O4—C7—C5 | 115.94 (10) |
O10—Ni1—O12 | 91.18 (4) | O3—C7—C5 | 117.48 (10) |
O11—Ni1—O12 | 88.24 (4) | O2—C3—C4 | 122.44 (11) |
O8—Ni1—O12 | 88.90 (4) | O2—C3—C2 | 122.30 (11) |
O9—Ni1—O12 | 175.82 (4) | C4—C3—C2 | 115.25 (10) |
Ni1—O7—H7A | 115.9 (15) | C1—C2—C3 | 120.56 (11) |
Ni1—O7—H7B | 119.8 (15) | C1—C2—H2 | 121.7 (11) |
H7A—O7—H7B | 104 (2) | C3—C2—H2 | 117.7 (11) |
Ni1—O8—H8A | 117.5 (15) | C2—C1—O1 | 122.31 (10) |
Ni1—O8—H8B | 112.3 (15) | C2—C1—C6 | 124.31 (10) |
H8A—O8—H8B | 104 (2) | O1—C1—C6 | 113.38 (9) |
C1—O1—C5 | 119.00 (9) | C4—C5—O1 | 122.55 (10) |
Ni1—O12—H12A | 113.2 (15) | C4—C5—C7 | 124.49 (10) |
Ni1—O12—H12B | 112.9 (15) | O1—C5—C7 | 112.95 (9) |
H12A—O12—H12B | 108 (2) | C5—C4—C3 | 120.31 (11) |
Ni1—O10—H10A | 118.4 (16) | C5—C4—H4 | 120.5 (11) |
Ni1—O10—H10B | 122.3 (16) | C3—C4—H4 | 119.2 (11) |
H10A—O10—H10B | 110 (2) | H13A—O13W—H13B | 105 (2) |
O2—C3—C2—C1 | 179.43 (11) | C1—O1—C5—C4 | −1.62 (16) |
C4—C3—C2—C1 | −1.02 (16) | C1—O1—C5—C7 | 179.67 (9) |
C3—C2—C1—O1 | 0.35 (17) | O4—C7—C5—C4 | 7.95 (17) |
C3—C2—C1—C6 | −179.01 (10) | O3—C7—C5—C4 | −170.19 (11) |
C5—O1—C1—C2 | 0.98 (16) | O4—C7—C5—O1 | −173.37 (10) |
C5—O1—C1—C6 | −179.60 (9) | O3—C7—C5—O1 | 8.49 (15) |
O5—C6—C1—C2 | 172.73 (11) | O1—C5—C4—C3 | 0.91 (17) |
O6—C6—C1—C2 | −7.79 (16) | C7—C5—C4—C3 | 179.46 (10) |
O5—C6—C1—O1 | −6.67 (15) | O2—C3—C4—C5 | 179.96 (11) |
O6—C6—C1—O1 | 172.80 (10) | C2—C3—C4—C5 | 0.41 (16) |
D—H···A | D—H | H···A | D···A | D—H···A |
O7—H7A···O1i | 0.84 (2) | 2.49 (2) | 2.9284 (12) | 113.4 (18) |
O7—H7A···O3i | 0.84 (2) | 1.85 (2) | 2.6862 (13) | 174 (2) |
O7—H7B···O1i | 0.83 (2) | 2.55 (2) | 2.9284 (12) | 109.2 (17) |
O7—H7B···O5i | 0.83 (2) | 1.89 (2) | 2.7161 (13) | 175 (2) |
O8—H8A···O2ii | 0.84 (2) | 2.01 (2) | 2.8281 (13) | 165 (2) |
O8—H8B···O4iii | 0.81 (2) | 1.86 (2) | 2.6635 (12) | 172 (2) |
O9—H9A···O2iv | 0.82 (2) | 2.11 (2) | 2.8837 (13) | 157 (2) |
O9—H9B···O6 | 0.88 (2) | 1.80 (2) | 2.6841 (13) | 175 (2) |
O10—H10A···O4v | 0.87 (2) | 1.88 (2) | 2.7482 (13) | 175 (2) |
O10—H10B···O5 | 0.82 (2) | 1.98 (2) | 2.7980 (14) | 169 (2) |
O11—H11A···O2iv | 0.81 (2) | 1.94 (2) | 2.7439 (14) | 167 (2) |
O11—H11B···O13Wvi | 0.82 (2) | 1.90 (2) | 2.6738 (14) | 157 (2) |
O12—H12A···O13Wii | 0.90 (2) | 2.07 (2) | 2.9553 (14) | 171 (2) |
O12—H12B···O3v | 0.85 (2) | 1.87 (2) | 2.7053 (13) | 169 (2) |
O13W—H13A···O12vii | 0.87 (3) | 2.00 (3) | 2.8291 (14) | 160 (3) |
O13W—H13B···O6 | 0.84 (3) | 1.95 (3) | 2.7835 (14) | 176 (3) |
C2—H2···O13W | 0.929 (18) | 2.591 (19) | 3.4755 (16) | 159.1 (16) |
C4—H4···O8iii | 0.958 (18) | 2.582 (18) | 3.4046 (15) | 144.1 (16) |
Symmetry codes: (i) x−1/2, −y+1/2, z−1/2; (ii) −x+3/2, y−1/2, −z+3/2; (iii) −x+2, −y+1, −z+2; (iv) −x+5/2, y−1/2, −z+3/2; (v) −x+5/2, y−1/2, −z+5/2; (vi) x+1/2, −y+1/2, z+1/2; (vii) x+1/2, −y+1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | [Ni(H2O)6](C7H2O6)·H2O |
Mr | 366.91 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 150 |
a, b, c (Å) | 6.9471 (4), 17.3603 (8), 11.6372 (6) |
β (°) | 104.884 (4) |
V (Å3) | 1356.40 (12) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.50 |
Crystal size (mm) | 0.53 × 0.46 × 0.37 |
Data collection | |
Diffractometer | Stoe IPDSII |
Absorption correction | Integration (X-RED; Stoe & Cie, 2002) |
Tmin, Tmax | 0.504, 0.607 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 24142, 3772, 3508 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.693 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.023, 0.057, 1.06 |
No. of reflections | 3772 |
No. of parameters | 254 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.37, −0.52 |
Computer programs: X-AREA (Stoe & Cie, 2002), X-RED (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003).
Ni1—O7 | 2.0253 (9) | Ni1—O8 | 2.0524 (9) |
Ni1—O10 | 2.0304 (9) | Ni1—O9 | 2.0617 (9) |
Ni1—O11 | 2.0460 (9) | Ni1—O12 | 2.0894 (9) |
D—H···A | D—H | H···A | D···A | D—H···A |
O7—H7A···O1i | 0.84 (2) | 2.49 (2) | 2.9284 (12) | 113.4 (18) |
O7—H7A···O3i | 0.84 (2) | 1.85 (2) | 2.6862 (13) | 174 (2) |
O7—H7B···O1i | 0.83 (2) | 2.55 (2) | 2.9284 (12) | 109.2 (17) |
O7—H7B···O5i | 0.83 (2) | 1.89 (2) | 2.7161 (13) | 175 (2) |
O8—H8A···O2ii | 0.84 (2) | 2.01 (2) | 2.8281 (13) | 165 (2) |
O8—H8B···O4iii | 0.81 (2) | 1.86 (2) | 2.6635 (12) | 172 (2) |
O9—H9A···O2iv | 0.82 (2) | 2.11 (2) | 2.8837 (13) | 157 (2) |
O9—H9B···O6 | 0.88 (2) | 1.80 (2) | 2.6841 (13) | 175 (2) |
O10—H10A···O4v | 0.87 (2) | 1.88 (2) | 2.7482 (13) | 175 (2) |
O10—H10B···O5 | 0.82 (2) | 1.98 (2) | 2.7980 (14) | 169 (2) |
O11—H11A···O2iv | 0.81 (2) | 1.94 (2) | 2.7439 (14) | 167 (2) |
O11—H11B···O13Wvi | 0.82 (2) | 1.90 (2) | 2.6738 (14) | 157 (2) |
O12—H12A···O13Wii | 0.90 (2) | 2.07 (2) | 2.9553 (14) | 171 (2) |
O12—H12B···O3v | 0.85 (2) | 1.87 (2) | 2.7053 (13) | 169 (2) |
O13W—H13A···O12vii | 0.87 (3) | 2.00 (3) | 2.8291 (14) | 160 (3) |
O13W—H13B···O6 | 0.84 (3) | 1.95 (3) | 2.7835 (14) | 176 (3) |
C2—H2···O13W | 0.929 (18) | 2.591 (19) | 3.4755 (16) | 159.1 (16) |
C4—H4···O8iii | 0.958 (18) | 2.582 (18) | 3.4046 (15) | 144.1 (16) |
Symmetry codes: (i) x−1/2, −y+1/2, z−1/2; (ii) −x+3/2, y−1/2, −z+3/2; (iii) −x+2, −y+1, −z+2; (iv) −x+5/2, y−1/2, −z+3/2; (v) −x+5/2, y−1/2, −z+5/2; (vi) x+1/2, −y+1/2, z+1/2; (vii) x+1/2, −y+1/2, z−1/2. |
Recently, we reported (Yasodha et al., 2007) a copper complex of the chelidonate (2,6-dicarboxypyranone) dianion arisng from doubly deprotonated 4-pyrone-2,6-dicarboxylic acid in which all the carboxylate oxygen atoms are involved in metal coordination to form a one dimensional polymeric chain. Conversely, in pentaaqua chelidonate copper (II) monohydrate (Manojlovic-Muir et al., 1999), only the carbonyl oxygen atom coordinates to the metal.
As an extension of these studies, we now describe the title compound, (I), which is a hydrated molecular salt (Fig. 1), in which the chelidonate is present as an isolated dianion. The carboxylate groups O5/C6/O6 and O3/C7/O4 form dihedral angles of 7.5 (5)° and 8.51 (8)° with the pyrone ring. The [Ni(H2O)6]2+ complex cation in (I) adopts a distorted octahedral cooordination, with the axial bonds to O9 and O12 slightly longer than the other four Ni—O vertices (Table 1). The Ni—O distances in (I) are shorter than the distances observed in hexaaquanickel (II) bis(p-nitrobenzoate) dihydrate [Ni—O mean distance 2.117 (3) Å] (Qu et al., 2004).
In the crystal a network of O—H···O and possible C—H···O interactions (Table 2, Fig. 2) help to establish the packing in which chains of chelidonate moieties form chains mediated by the complex cations.