Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270113002230/fn3122sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270113002230/fn3122Isup2.hkl |
CCDC reference: 934549
To an aqueous solution (60 ml) containing citric acid ( 1 mmol, 0.192g) and sodium hydroxide ( 4 mmol, 0.160g) was added a mixture of 2,6-diaminopurine (2 mmol, 0.300 g) and cobalt acetate tetrahydrate (2 mmol, 0.498g). The resulting mixture was heated under reflux for 4h and then filtered. The filtrate was allowed to stand at room temperature for three weeks to give crystals of (I) suitable for X-ray analysis.
Some solvent water molecules presented problems in refinement: one of them (O6W) appeared split over two positions with depleted occupancy [0.405 (14) and 0.270 (14)], and its H atoms, as well as those for O5W, could not be found in the difference map and were not included in the final model.
The remaining H atoms were originally found in the difference Fourier map but were treated differently in refinement. C-bound H atoms were repositioned in their expected positions and thereafter allowed to ride, with C—Haromatic = 0.93 and C—Hmethylene = 0.97 Å, while N- and O-bound H atoms were refined with restrained distances of N—H = O—H = 0.85 (1) Å and H···H = 1.35 (2) Å. One of the water H atoms (H1WB) required an anti-bumping restraint to prevent an unrealistic approach to atom Co1. In all cases, Uiso(H) = 1.2Ueq(host).
In the final difference map, the maximum and minimum Δρ peaks are 1.05 and -1.43 e Å-3, respectively, at 0.49 and 1.02 Å from atom Co1. The rather complex character of the structure prevented some of the N-bound H atoms (H51B, H61B, H52A and H62B) from being involved in hydrogen bonding. In addition, it is worth noting that the space group should be considered centrosymmetric only on average; data reduction in space group C2/c showed many small violations to the c-glide condition, while refinement in space group C2 did not improve the results yet doubled the number of parameters needed in the description of the structure. This may be partially responsible for the rather unusual weighting scheme needed to optimize refinement.
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); 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) and PLATON (Spek, 2009).
[Co4(C6H4O7)2(C5H6N6)4(H2O)4]·6.35H2O | F(000) = 2862 |
Mr = 1398.78 | Dx = 1.905 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 10568 reflections |
a = 10.548 (2) Å | θ = 1.9–26.1° |
b = 18.669 (4) Å | µ = 1.45 mm−1 |
c = 24.795 (6) Å | T = 150 K |
β = 92.687 (5)° | Block, pink |
V = 4877.5 (19) Å3 | 0.18 × 0.15 × 0.14 mm |
Z = 4 |
Bruker SMART CCD area-detector diffractometer | 5466 independent reflections |
Radiation source: fine-focus sealed tube | 4889 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.076 |
CCD rotation images, thin slices scans | θmax = 27.9°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS in SAINT-NT; Bruker, 2002) | h = −13→13 |
Tmin = 0.77, Tmax = 0.82 | k = −24→24 |
20231 measured reflections | l = −32→32 |
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)] = 0.059 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.122 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.27 | w = 1/[σ2(Fo2) + (0.P)2 + 43.9582P] where P = (Fo2 + 2Fc2)/3 |
5466 reflections | (Δ/σ)max = 0.001 |
448 parameters | Δρmax = 1.05 e Å−3 |
26 restraints | Δρmin = −1.43 e Å−3 |
[Co4(C6H4O7)2(C5H6N6)4(H2O)4]·6.35H2O | V = 4877.5 (19) Å3 |
Mr = 1398.78 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 10.548 (2) Å | µ = 1.45 mm−1 |
b = 18.669 (4) Å | T = 150 K |
c = 24.795 (6) Å | 0.18 × 0.15 × 0.14 mm |
β = 92.687 (5)° |
Bruker SMART CCD area-detector diffractometer | 5466 independent reflections |
Absorption correction: multi-scan (SADABS in SAINT-NT; Bruker, 2002) | 4889 reflections with I > 2σ(I) |
Tmin = 0.77, Tmax = 0.82 | Rint = 0.076 |
20231 measured reflections |
R[F2 > 2σ(F2)] = 0.059 | 26 restraints |
wR(F2) = 0.122 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.27 | w = 1/[σ2(Fo2) + (0.P)2 + 43.9582P] where P = (Fo2 + 2Fc2)/3 |
5466 reflections | Δρmax = 1.05 e Å−3 |
448 parameters | Δρmin = −1.43 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Co1 | 0.5000 | 0.5000 | 0.5000 | 0.0618 (4) | |
Co2 | 1.0000 | 0.56680 (4) | 0.7500 | 0.01690 (16) | |
Co3 | 0.99629 (6) | 0.49587 (3) | 0.86241 (2) | 0.02559 (15) | |
O1W | 0.4093 (4) | 0.5383 (2) | 0.56859 (17) | 0.0539 (11) | |
H1WA | 0.441 (5) | 0.5763 (16) | 0.583 (2) | 0.065* | |
H1WB | 0.340 (2) | 0.552 (3) | 0.5533 (7) | 0.065* | |
O2W | 0.8698 (3) | 0.43158 (18) | 0.90284 (14) | 0.0359 (8) | |
H2WA | 0.795 (2) | 0.434 (2) | 0.889 (2) | 0.043* | |
H2WB | 0.878 (4) | 0.3887 (11) | 0.914 (2) | 0.043* | |
O3W | 0.1704 (4) | 0.31752 (19) | 0.36005 (15) | 0.0444 (9) | |
H3WA | 0.163 (4) | 0.3570 (16) | 0.343 (2) | 0.053* | |
H3WB | 0.245 (2) | 0.304 (3) | 0.355 (2) | 0.053* | |
O4W | 1.0000 | 0.3144 (4) | 0.7500 | 0.119 (4) | |
H4W | 0.946 (6) | 0.3420 (12) | 0.734 (4) | 0.143* | |
N11 | 0.9013 (3) | 0.64413 (18) | 0.79407 (13) | 0.0195 (7) | |
N21 | 0.8065 (4) | 0.74782 (19) | 0.81202 (15) | 0.0288 (8) | |
H21 | 0.782 (5) | 0.7913 (10) | 0.809 (2) | 0.035* | |
N31 | 0.8137 (4) | 0.6751 (2) | 0.95065 (15) | 0.0331 (9) | |
N41 | 0.9017 (3) | 0.59333 (19) | 0.88509 (13) | 0.0239 (7) | |
N51 | 0.7374 (5) | 0.7874 (2) | 0.92845 (17) | 0.0393 (10) | |
H51A | 0.717 (5) | 0.801 (2) | 0.9594 (9) | 0.047* | |
H51B | 0.724 (5) | 0.8216 (18) | 0.9067 (14) | 0.047* | |
N61 | 0.8874 (6) | 0.5628 (3) | 0.97387 (18) | 0.0532 (13) | |
H61A | 0.861 (6) | 0.569 (3) | 1.0050 (11) | 0.064* | |
H61B | 0.903 (6) | 0.5193 (11) | 0.968 (2) | 0.064* | |
C11 | 0.8600 (4) | 0.7070 (2) | 0.77525 (17) | 0.0247 (9) | |
H11 | 0.8678 | 0.7212 | 0.7396 | 0.030* | |
C21 | 0.8165 (4) | 0.7097 (2) | 0.85977 (17) | 0.0257 (9) | |
C31 | 0.7877 (4) | 0.7251 (3) | 0.91368 (18) | 0.0300 (10) | |
C41 | 0.8670 (4) | 0.6126 (3) | 0.93572 (18) | 0.0308 (10) | |
C51 | 0.8738 (4) | 0.6458 (2) | 0.84816 (15) | 0.0192 (8) | |
N12 | 0.5194 (5) | 0.6087 (2) | 0.4740 (2) | 0.0521 (14) | |
N22 | 0.5759 (5) | 0.7002 (2) | 0.42269 (19) | 0.0435 (11) | |
H22 | 0.599 (5) | 0.732 (2) | 0.4003 (19) | 0.052* | |
N32 | 0.5949 (4) | 0.7931 (2) | 0.55542 (17) | 0.0397 (10) | |
N42 | 0.5265 (5) | 0.6701 (2) | 0.5605 (2) | 0.0487 (12) | |
N52 | 0.6494 (5) | 0.8469 (2) | 0.47551 (18) | 0.0425 (11) | |
H52A | 0.671 (5) | 0.8876 (14) | 0.4878 (18) | 0.051* | |
H52B | 0.657 (6) | 0.848 (3) | 0.4416 (5) | 0.051* | |
N62 | 0.5595 (6) | 0.7381 (3) | 0.6365 (2) | 0.0653 (16) | |
H62A | 0.521 (6) | 0.708 (2) | 0.656 (2) | 0.078* | |
H62B | 0.547 (7) | 0.7789 (14) | 0.650 (2) | 0.078* | |
C12 | 0.5426 (6) | 0.6313 (3) | 0.4254 (3) | 0.0510 (16) | |
H12 | 0.5364 | 0.6017 | 0.3952 | 0.061* | |
C22 | 0.5737 (5) | 0.7256 (2) | 0.4757 (2) | 0.0371 (12) | |
C32 | 0.6071 (5) | 0.7902 (3) | 0.5015 (2) | 0.0369 (11) | |
C42 | 0.5587 (6) | 0.7339 (3) | 0.5812 (2) | 0.0462 (13) | |
C52 | 0.5393 (5) | 0.6683 (3) | 0.5057 (2) | 0.0428 (13) | |
C13 | 0.7456 (5) | 0.5094 (2) | 0.58061 (18) | 0.0352 (11) | |
C23 | 0.6864 (4) | 0.5216 (2) | 0.63414 (17) | 0.0297 (10) | |
H23A | 0.6117 | 0.4914 | 0.6353 | 0.036* | |
H23B | 0.6577 | 0.5709 | 0.6351 | 0.036* | |
C33 | 0.7696 (4) | 0.5074 (2) | 0.68605 (17) | 0.0261 (9) | |
C43 | 0.6950 (4) | 0.5242 (2) | 0.73587 (18) | 0.0278 (9) | |
H43A | 0.6105 | 0.5039 | 0.7309 | 0.033* | |
H43B | 0.6860 | 0.5757 | 0.7390 | 0.033* | |
C53 | 0.7567 (4) | 0.4952 (2) | 0.78852 (18) | 0.0304 (10) | |
C63 | 0.8005 (4) | 0.4270 (2) | 0.68523 (19) | 0.0321 (10) | |
O13 | 0.6761 (4) | 0.51159 (19) | 0.53803 (14) | 0.0444 (9) | |
O23 | 0.8635 (3) | 0.4991 (2) | 0.57762 (13) | 0.0404 (8) | |
O33 | 0.8779 (3) | 0.49242 (15) | 0.79150 (11) | 0.0253 (6) | |
O43 | 0.6882 (3) | 0.4760 (2) | 0.82554 (14) | 0.0440 (9) | |
O53 | 0.9030 (3) | 0.40625 (16) | 0.66689 (13) | 0.0318 (7) | |
O63 | 0.7175 (4) | 0.38575 (19) | 0.70148 (18) | 0.0514 (10) | |
O73 | 0.8818 (3) | 0.54856 (14) | 0.68448 (11) | 0.0215 (6) | |
O5W | 0.5574 (7) | 0.6585 (3) | 0.3006 (3) | 0.117 (3) | |
O6W' | 0.475 (2) | 0.6761 (7) | 0.7328 (5) | 0.099 (7) | 0.392 (13) |
O6W" | 0.4363 (18) | 0.6138 (9) | 0.6758 (8) | 0.074 (8) | 0.273 (14) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Co1 | 0.0851 (9) | 0.0234 (5) | 0.0711 (8) | −0.0084 (5) | −0.0602 (7) | 0.0102 (5) |
Co2 | 0.0183 (4) | 0.0169 (4) | 0.0153 (3) | 0.000 | −0.0017 (3) | 0.000 |
Co3 | 0.0336 (3) | 0.0215 (3) | 0.0213 (3) | 0.0006 (2) | −0.0026 (2) | 0.0052 (2) |
O1W | 0.056 (2) | 0.044 (2) | 0.058 (3) | −0.0180 (19) | −0.034 (2) | 0.020 (2) |
O2W | 0.0419 (19) | 0.0290 (17) | 0.0370 (19) | −0.0009 (15) | 0.0049 (15) | 0.0110 (15) |
O3W | 0.056 (2) | 0.0322 (19) | 0.044 (2) | 0.0078 (17) | −0.0126 (18) | 0.0105 (16) |
O4W | 0.188 (10) | 0.036 (4) | 0.123 (7) | 0.000 | −0.102 (7) | 0.000 |
N11 | 0.0233 (17) | 0.0205 (16) | 0.0147 (15) | 0.0030 (13) | 0.0015 (13) | 0.0046 (13) |
N21 | 0.040 (2) | 0.0196 (17) | 0.0269 (19) | 0.0061 (16) | 0.0037 (16) | −0.0010 (15) |
N31 | 0.044 (2) | 0.036 (2) | 0.0201 (18) | −0.0056 (18) | 0.0113 (16) | −0.0015 (16) |
N41 | 0.0291 (19) | 0.0260 (18) | 0.0169 (16) | −0.0031 (15) | 0.0050 (14) | 0.0042 (14) |
N51 | 0.056 (3) | 0.033 (2) | 0.030 (2) | 0.001 (2) | 0.016 (2) | −0.0013 (18) |
N61 | 0.095 (4) | 0.036 (2) | 0.030 (2) | 0.014 (3) | 0.025 (2) | 0.014 (2) |
C11 | 0.031 (2) | 0.022 (2) | 0.022 (2) | −0.0031 (17) | 0.0035 (17) | 0.0010 (16) |
C21 | 0.028 (2) | 0.026 (2) | 0.024 (2) | −0.0042 (17) | 0.0034 (16) | 0.0043 (17) |
C31 | 0.031 (2) | 0.033 (2) | 0.027 (2) | −0.0044 (19) | 0.0085 (18) | −0.0025 (19) |
C41 | 0.034 (2) | 0.035 (2) | 0.023 (2) | −0.005 (2) | 0.0054 (18) | 0.0028 (18) |
C51 | 0.0181 (18) | 0.0232 (19) | 0.0166 (18) | −0.0039 (15) | 0.0046 (14) | −0.0004 (15) |
N12 | 0.068 (3) | 0.025 (2) | 0.060 (3) | −0.001 (2) | −0.043 (3) | 0.006 (2) |
N22 | 0.059 (3) | 0.026 (2) | 0.043 (3) | 0.009 (2) | −0.023 (2) | 0.0014 (18) |
N32 | 0.054 (3) | 0.028 (2) | 0.036 (2) | 0.0063 (19) | −0.013 (2) | −0.0022 (17) |
N42 | 0.058 (3) | 0.033 (2) | 0.054 (3) | −0.010 (2) | −0.021 (2) | 0.011 (2) |
N52 | 0.064 (3) | 0.022 (2) | 0.040 (2) | 0.001 (2) | −0.014 (2) | −0.0008 (18) |
N62 | 0.090 (5) | 0.061 (4) | 0.045 (3) | −0.009 (3) | −0.004 (3) | 0.009 (3) |
C12 | 0.059 (4) | 0.026 (2) | 0.065 (4) | 0.008 (2) | −0.041 (3) | −0.008 (3) |
C22 | 0.049 (3) | 0.024 (2) | 0.037 (3) | 0.008 (2) | −0.019 (2) | 0.001 (2) |
C32 | 0.043 (3) | 0.026 (2) | 0.041 (3) | 0.004 (2) | −0.011 (2) | −0.002 (2) |
C42 | 0.050 (3) | 0.044 (3) | 0.043 (3) | 0.003 (3) | −0.012 (2) | 0.004 (2) |
C52 | 0.049 (3) | 0.027 (2) | 0.050 (3) | 0.004 (2) | −0.028 (3) | 0.005 (2) |
C13 | 0.053 (3) | 0.022 (2) | 0.028 (2) | −0.001 (2) | −0.019 (2) | −0.0030 (18) |
C23 | 0.031 (2) | 0.030 (2) | 0.026 (2) | −0.0001 (18) | −0.0120 (18) | −0.0021 (18) |
C33 | 0.024 (2) | 0.026 (2) | 0.027 (2) | −0.0045 (18) | −0.0075 (16) | 0.0020 (17) |
C43 | 0.020 (2) | 0.030 (2) | 0.033 (2) | −0.0017 (17) | −0.0047 (17) | 0.0029 (18) |
C53 | 0.035 (2) | 0.021 (2) | 0.035 (2) | −0.0101 (19) | −0.0035 (19) | 0.0029 (18) |
C63 | 0.032 (2) | 0.026 (2) | 0.037 (3) | −0.0039 (19) | −0.0123 (19) | −0.0032 (19) |
O13 | 0.056 (2) | 0.040 (2) | 0.0338 (18) | 0.0032 (17) | −0.0271 (17) | −0.0051 (16) |
O23 | 0.047 (2) | 0.048 (2) | 0.0255 (17) | 0.0049 (18) | −0.0103 (14) | −0.0087 (16) |
O33 | 0.0283 (15) | 0.0224 (15) | 0.0247 (15) | −0.0038 (12) | −0.0055 (12) | 0.0052 (12) |
O43 | 0.0328 (19) | 0.058 (2) | 0.042 (2) | −0.0093 (17) | 0.0059 (15) | 0.0205 (18) |
O53 | 0.0367 (18) | 0.0199 (15) | 0.0382 (18) | −0.0034 (13) | −0.0029 (14) | 0.0013 (13) |
O63 | 0.050 (2) | 0.0250 (18) | 0.080 (3) | −0.0142 (17) | 0.004 (2) | 0.0009 (18) |
O73 | 0.0242 (14) | 0.0191 (14) | 0.0204 (14) | −0.0050 (11) | −0.0071 (11) | −0.0013 (11) |
O5W | 0.132 (6) | 0.083 (4) | 0.144 (6) | 0.038 (4) | 0.082 (5) | 0.041 (4) |
O6W' | 0.16 (2) | 0.076 (10) | 0.061 (11) | 0.019 (11) | 0.020 (12) | 0.020 (7) |
O6W" | 0.088 (15) | 0.046 (10) | 0.087 (15) | 0.012 (9) | −0.001 (11) | −0.005 (9) |
Co1—O13 | 2.055 (3) | C21—C51 | 1.374 (6) |
Co1—O13i | 2.055 (3) | C21—C31 | 1.414 (6) |
Co1—O1Wi | 2.115 (5) | N12—C12 | 1.310 (8) |
Co1—O1W | 2.115 (5) | N12—C52 | 1.374 (7) |
Co1—N12 | 2.143 (4) | N22—C12 | 1.336 (7) |
Co1—N12i | 2.143 (4) | N22—C22 | 1.399 (7) |
Co2—O73 | 2.030 (3) | N22—H22 | 0.850 (10) |
Co2—O73ii | 2.030 (3) | N32—C42 | 1.341 (7) |
Co2—N11ii | 2.114 (3) | N32—C32 | 1.349 (7) |
Co2—N11 | 2.114 (3) | N42—C42 | 1.335 (7) |
Co2—O33ii | 2.184 (3) | N42—C52 | 1.370 (7) |
Co2—O33 | 2.184 (3) | N52—C32 | 1.328 (7) |
Co3—O73ii | 2.028 (3) | N52—H52A | 0.846 (10) |
Co3—O23ii | 2.049 (3) | N52—H52B | 0.848 (10) |
Co3—O2W | 2.086 (3) | N62—C42 | 1.373 (7) |
Co3—O33 | 2.109 (3) | N62—H62A | 0.851 (10) |
Co3—O53ii | 2.128 (3) | N62—H62B | 0.849 (10) |
Co3—N41 | 2.162 (4) | C12—H12 | 0.9300 |
O1W—H1WA | 0.852 (10) | C22—C52 | 1.362 (7) |
O1W—H1WB | 0.848 (10) | C22—C32 | 1.402 (6) |
O2W—H2WA | 0.848 (10) | C13—O13 | 1.257 (5) |
O2W—H2WB | 0.849 (10) | C13—O23 | 1.264 (6) |
O3W—H3WA | 0.851 (10) | C13—C23 | 1.510 (7) |
O3W—H3WB | 0.847 (10) | C23—C33 | 1.546 (5) |
O4W—H4W | 0.850 (10) | C23—H23A | 0.9700 |
N11—C11 | 1.328 (5) | C23—H23B | 0.9700 |
N11—C51 | 1.386 (5) | C33—O73 | 1.413 (5) |
N21—C11 | 1.334 (5) | C33—C43 | 1.528 (6) |
N21—C21 | 1.382 (5) | C33—C63 | 1.536 (6) |
N21—H21 | 0.853 (10) | C43—C53 | 1.530 (6) |
N31—C31 | 1.327 (6) | C43—H43A | 0.9700 |
N31—C41 | 1.354 (6) | C43—H43B | 0.9700 |
N41—C51 | 1.363 (5) | C53—O43 | 1.248 (5) |
N41—C41 | 1.372 (5) | C53—O33 | 1.278 (5) |
N51—C31 | 1.338 (6) | C63—O63 | 1.247 (6) |
N51—H51A | 0.845 (10) | C63—O53 | 1.254 (6) |
N51—H51B | 0.844 (10) | O23—Co3ii | 2.049 (3) |
N61—C41 | 1.337 (6) | O53—Co3ii | 2.128 (3) |
N61—H61A | 0.839 (10) | O73—Co3ii | 2.028 (3) |
N61—H61B | 0.842 (10) | O6W'—O6W'iii | 0.98 (3) |
C11—H11 | 0.9300 | ||
O13—Co1—O13i | 180.0 | N31—C31—N51 | 119.6 (4) |
O13—Co1—O1Wi | 88.36 (14) | N31—C31—C21 | 117.6 (4) |
O13i—Co1—O1Wi | 91.64 (14) | N51—C31—C21 | 122.7 (4) |
O13—Co1—O1W | 91.64 (14) | N61—C41—N31 | 117.5 (4) |
O13i—Co1—O1W | 88.36 (14) | N61—C41—N41 | 115.1 (4) |
O1Wi—Co1—O1W | 180.000 (1) | N31—C41—N41 | 127.5 (4) |
O13—Co1—N12 | 86.64 (15) | N41—C51—C21 | 124.5 (4) |
O13i—Co1—N12 | 93.36 (15) | N41—C51—N11 | 125.9 (4) |
O1Wi—Co1—N12 | 91.42 (19) | C21—C51—N11 | 109.6 (3) |
O1W—Co1—N12 | 88.58 (18) | C12—N12—C52 | 103.7 (4) |
O13—Co1—N12i | 93.36 (15) | C12—N12—Co1 | 127.3 (4) |
O13i—Co1—N12i | 86.64 (15) | C52—N12—Co1 | 127.5 (4) |
O1Wi—Co1—N12i | 88.58 (18) | C12—N22—C22 | 105.3 (5) |
O1W—Co1—N12i | 91.42 (19) | C12—N22—H22 | 141 (4) |
N12—Co1—N12i | 180.000 (1) | C22—N22—H22 | 113 (4) |
O73—Co2—O73ii | 160.68 (16) | C42—N32—C32 | 118.8 (4) |
O73—Co2—N11ii | 89.99 (12) | C42—N42—C52 | 111.6 (5) |
O73ii—Co2—N11ii | 103.26 (12) | C32—N52—H52A | 129 (3) |
O73—Co2—N11 | 103.26 (12) | C32—N52—H52B | 123 (3) |
O73ii—Co2—N11 | 89.99 (12) | H52A—N52—H52B | 108 (2) |
N11ii—Co2—N11 | 93.86 (18) | C42—N62—H62A | 124 (5) |
O73—Co2—O33ii | 82.51 (11) | C42—N62—H62B | 118 (5) |
O73ii—Co2—O33ii | 85.23 (11) | H62A—N62—H62B | 105 (2) |
N11ii—Co2—O33ii | 82.82 (12) | N12—C12—N22 | 114.6 (5) |
N11—Co2—O33ii | 173.39 (12) | N12—C12—H12 | 122.7 |
O73—Co2—O33 | 85.23 (11) | N22—C12—H12 | 122.7 |
O73ii—Co2—O33 | 82.51 (11) | C52—C22—N22 | 105.3 (4) |
N11ii—Co2—O33 | 173.39 (12) | C52—C22—C32 | 119.5 (5) |
N11—Co2—O33 | 82.82 (12) | N22—C22—C32 | 134.9 (5) |
O33ii—Co2—O33 | 101.03 (16) | N52—C32—N32 | 119.9 (4) |
O73ii—Co3—O23ii | 86.92 (13) | N52—C32—C22 | 123.1 (5) |
O73ii—Co3—O2W | 172.59 (13) | N32—C32—C22 | 116.9 (5) |
O23ii—Co3—O2W | 97.14 (14) | N42—C42—N32 | 128.6 (5) |
O73ii—Co3—O33 | 84.46 (11) | N42—C42—N62 | 115.2 (5) |
O23ii—Co3—O33 | 170.09 (13) | N32—C42—N62 | 116.2 (5) |
O2W—Co3—O33 | 90.92 (13) | C22—C52—N42 | 124.3 (5) |
O73ii—Co3—O53ii | 81.12 (12) | C22—C52—N12 | 111.1 (5) |
O23ii—Co3—O53ii | 85.17 (14) | N42—C52—N12 | 124.6 (5) |
O2W—Co3—O53ii | 93.00 (14) | O13—C13—O23 | 119.5 (5) |
O33—Co3—O53ii | 88.67 (12) | O13—C13—C23 | 119.0 (5) |
O73ii—Co3—N41 | 93.08 (12) | O23—C13—C23 | 121.5 (4) |
O23ii—Co3—N41 | 96.49 (14) | C13—C23—C33 | 117.7 (4) |
O2W—Co3—N41 | 92.62 (14) | C13—C23—H23A | 107.9 |
O33—Co3—N41 | 88.86 (12) | C33—C23—H23A | 107.9 |
O53ii—Co3—N41 | 173.90 (13) | C13—C23—H23B | 107.9 |
Co1—O1W—H1WA | 115 (5) | C33—C23—H23B | 107.9 |
Co1—O1W—H1WB | 98.9 (10) | H23A—C23—H23B | 107.2 |
H1WA—O1W—H1WB | 104.9 (16) | O73—C33—C43 | 112.0 (3) |
Co3—O2W—H2WA | 112 (3) | O73—C33—C63 | 110.6 (4) |
Co3—O2W—H2WB | 130 (3) | C43—C33—C63 | 109.2 (4) |
H2WA—O2W—H2WB | 105.4 (17) | O73—C33—C23 | 109.1 (3) |
H3WA—O3W—H3WB | 105.1 (17) | C43—C33—C23 | 110.1 (4) |
C11—N11—C51 | 103.9 (3) | C63—C33—C23 | 105.6 (3) |
C11—N11—Co2 | 125.6 (3) | C33—C43—C53 | 113.7 (4) |
C51—N11—Co2 | 130.2 (3) | C33—C43—H43A | 108.8 |
C11—N21—C21 | 105.8 (4) | C53—C43—H43A | 108.8 |
C11—N21—H21 | 129 (4) | C33—C43—H43B | 108.8 |
C21—N21—H21 | 124 (3) | C53—C43—H43B | 108.8 |
C31—N31—C41 | 119.4 (4) | H43A—C43—H43B | 107.7 |
C51—N41—C41 | 111.6 (4) | O43—C53—O33 | 124.0 (4) |
C51—N41—Co3 | 121.1 (3) | O43—C53—C43 | 119.4 (4) |
C41—N41—Co3 | 127.2 (3) | O33—C53—C43 | 116.6 (4) |
C31—N51—H51A | 129 (3) | O63—C63—O53 | 123.8 (4) |
C31—N51—H51B | 123 (3) | O63—C63—C33 | 116.5 (4) |
H51A—N51—H51B | 108 (2) | O53—C63—C33 | 119.6 (4) |
C41—N61—H61A | 121 (4) | C13—O13—Co1 | 149.4 (4) |
C41—N61—H61B | 126 (4) | C13—O23—Co3ii | 129.9 (3) |
H61A—N61—H61B | 111 (3) | C53—O33—Co3 | 126.8 (3) |
N11—C11—N21 | 114.0 (4) | C53—O33—Co2 | 123.9 (3) |
N11—C11—H11 | 123.0 | Co3—O33—Co2 | 91.96 (11) |
N21—C11—H11 | 123.0 | C63—O53—Co3ii | 109.5 (3) |
C51—C21—N21 | 106.5 (4) | C33—O73—Co3ii | 107.9 (2) |
C51—C21—C31 | 119.4 (4) | C33—O73—Co2 | 123.6 (2) |
N21—C21—C31 | 134.0 (4) | Co3ii—O73—Co2 | 99.10 (12) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+2, y, −z+3/2; (iii) −x+1, y, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1WA···N42 | 0.85 (1) | 2.06 (4) | 2.766 (6) | 140 (6) |
O2W—H2WA···O43 | 0.85 (1) | 2.04 (3) | 2.773 (5) | 144 (4) |
N61—H61B···O2W | 0.84 (1) | 2.32 (4) | 3.017 (6) | 140 (5) |
O4W—H4W···O53 | 0.85 (1) | 2.09 (6) | 2.835 (5) | 147 (10) |
O1W—H1WB···N61iii | 0.85 (1) | 2.47 (2) | 3.286 (7) | 163 (4) |
O2W—H2WB···N32iv | 0.85 (1) | 1.96 (1) | 2.804 (5) | 175 (5) |
O3W—H3WA···O73i | 0.85 (1) | 1.94 (1) | 2.778 (4) | 168 (5) |
O3W—H3WB···N62i | 0.85 (1) | 2.20 (2) | 3.030 (8) | 166 (5) |
N21—H21···O63v | 0.85 (1) | 1.78 (2) | 2.607 (5) | 162 (5) |
N51—H51A···N31vi | 0.85 (1) | 2.31 (1) | 3.149 (5) | 171 (5) |
N61—H61A···O23vii | 0.84 (1) | 2.20 (4) | 2.842 (5) | 133 (5) |
N22—H22···O3Wviii | 0.85 (1) | 2.05 (2) | 2.889 (6) | 168 (6) |
N52—H52B···O3Wviii | 0.85 (1) | 2.11 (2) | 2.934 (6) | 163 (5) |
N62—H62A···O6W′ | 0.85 (1) | 2.07 (4) | 2.834 (16) | 149 (6) |
N62—H62A···O6W" | 0.85 (1) | 2.05 (3) | 2.85 (2) | 157 (6) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (iii) −x+1, y, −z+3/2; (iv) −x+3/2, y−1/2, −z+3/2; (v) −x+3/2, y+1/2, −z+3/2; (vi) −x+3/2, −y+3/2, −z+2; (vii) x, −y+1, z+1/2; (viii) x+1/2, y+1/2, z. |
Experimental details
Crystal data | |
Chemical formula | [Co4(C6H4O7)2(C5H6N6)4(H2O)4]·6.35H2O |
Mr | 1398.78 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 150 |
a, b, c (Å) | 10.548 (2), 18.669 (4), 24.795 (6) |
β (°) | 92.687 (5) |
V (Å3) | 4877.5 (19) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.45 |
Crystal size (mm) | 0.18 × 0.15 × 0.14 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS in SAINT-NT; Bruker, 2002) |
Tmin, Tmax | 0.77, 0.82 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 20231, 5466, 4889 |
Rint | 0.076 |
(sin θ/λ)max (Å−1) | 0.658 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.059, 0.122, 1.27 |
No. of reflections | 5466 |
No. of parameters | 448 |
No. of restraints | 26 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
w = 1/[σ2(Fo2) + (0.P)2 + 43.9582P] where P = (Fo2 + 2Fc2)/3 | |
Δρmax, Δρmin (e Å−3) | 1.05, −1.43 |
Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1WA···N42 | 0.852 (10) | 2.06 (4) | 2.766 (6) | 140 (6) |
O2W—H2WA···O43 | 0.848 (10) | 2.04 (3) | 2.773 (5) | 144 (4) |
N61—H61B···O2W | 0.842 (10) | 2.32 (4) | 3.017 (6) | 140 (5) |
O4W—H4W···O53 | 0.850 (10) | 2.09 (6) | 2.835 (5) | 147 (10) |
O1W—H1WB···N61i | 0.848 (10) | 2.465 (17) | 3.286 (7) | 163 (4) |
O2W—H2WB···N32ii | 0.849 (10) | 1.956 (12) | 2.804 (5) | 175 (5) |
O3W—H3WA···O73iii | 0.851 (10) | 1.941 (14) | 2.778 (4) | 168 (5) |
O3W—H3WB···N62iii | 0.847 (10) | 2.201 (18) | 3.030 (8) | 166 (5) |
N21—H21···O63iv | 0.853 (10) | 1.784 (19) | 2.607 (5) | 162 (5) |
N51—H51A···N31v | 0.845 (10) | 2.312 (13) | 3.149 (5) | 171 (5) |
N61—H61A···O23vi | 0.839 (10) | 2.20 (4) | 2.842 (5) | 133 (5) |
N22—H22···O3Wvii | 0.850 (10) | 2.052 (17) | 2.889 (6) | 168 (6) |
N52—H52B···O3Wvii | 0.848 (10) | 2.112 (17) | 2.934 (6) | 163 (5) |
N62—H62A···O6W' | 0.851 (10) | 2.07 (4) | 2.834 (16) | 149 (6) |
N62—H62A···O6W" | 0.851 (10) | 2.05 (3) | 2.85 (2) | 157 (6) |
Symmetry codes: (i) −x+1, y, −z+3/2; (ii) −x+3/2, y−1/2, −z+3/2; (iii) −x+1, −y+1, −z+1; (iv) −x+3/2, y+1/2, −z+3/2; (v) −x+3/2, −y+3/2, −z+2; (vi) x, −y+1, z+1/2; (vii) x+1/2, y+1/2, z. |
For some time our group has focused attention on the study of the coordination chemistry of transition metal and lanthanide ions with (poly)carboxylic acids as ligands. An interesting candidate within this group is citric acid (H4cit, C6H8O7), not only due to its physiological importance [it is widely distributed in human plasma (Martin, 1986; Gautier-Luneau et al., 2007) and it participates in the catabolism of carbohydrates of aerobic organisms as a substrate in the tricarboxylic acid (or Krebs) cycle (Lippard & Berg, 1994)] but also for its intrinsic chemical interest. This molecule can give rise to mono- or multinuclear compounds of quite different natures through its binding to metal ions via an α-hydroxy, an α-carboxylate and/or one or both of its β-carboxylate groups (Matzapetaks et al., 2001; Kefalas et al., 2005; Zhou et al., 2005). In addition, it can show various degrees of deprotonation, ranging from a neutral ligand to a tetra-anion. A large number of complexes [about 360 in the Cambridge Structural Database (CSD), Version 5.33; Allen, 2002] have been reported, displaying coordination numbers covering the range from µ1 to µ9.
In parallel, in some of our previous research we found 2,6-diaminopurine (dap, C5H6N6) to be an extremely versatile coligand but one that has not been adequately explored. Only ten complexes could be found in the CSD, in seven different binding modes (Fig. 1), with coordination numbers from µ1 to µ3. Among the many interesting features of this ligand are its impressive ability to participate in hydrogen bonding, acting both as a (multiple) donor and a (multiple) acceptor and thus giving rise to complex hydrogen-bonding networks (see discussion below), and the fact that it can display a diversity of protonation states (1+, 1- or neutral). In any of these the dap molecule may present prototropy, a special form of tautomerism consisting of a rearrangement of the charge distribution. This is illustrated in Fig. 1, where the electron-density redistribution is evidenced by the different positions of the single and double bonds around the rings.
Given all this, the possibility of having both ligands together in one compound seemed an extremely promising venture. Therefore, we synthesized the title CoII complex, (I), and present its structure here.
Compound (I) crystallizes in space group C2/c with three independent types of CoII cations in the asymmetric unit, two of them lying on symmetry elements (Co1 on an inversion centre and Co2 on a two-fold axis), while the third, Co3, is in a general position. The asymmetric unit content is completed by one fully deprotonated (4-) citrate anion (cit), two diaminopurine (dap) molecules and two ligand water molecules. The structure is completed by a mixture of fully occupied solvent water molecules (two in general positions and one on a two-fold axis) and a disordered one, split over two positions.
There are two well defined coordination groups in the structure, one of them (mononuclear) containing only Co1 as its metal centre, and a second, trinuclear, one with both Co2 and Co3. Fig 2(a) presents the group containing Co1. The cation lies on a centre of symmetry and it is bound by one N atom from a monocoordinated dap ligand, one O atom from one citrate tetra-anion and one water ligand, plus their inversion-related counterparts. The octahedron thus defined is rather regular, with Co1—N/O distances in the range 2.055 (3)–2.142 (4) Å and central angles in the range 90±3.35 (15)° (cis), trans angles being fixed by symmetry at 180°.
The Co2–Co3 group is more complex (Fig. 2b). Atom Co2 lays on a twofold axis, while atom Co3 occupies a general position. These three vicinal Co centres are multiply bridged by a cit tetra-anion and a neutral dap ligand and their symmetry-related counterparts. The result is that both Co2 and Co3 end up with distorted octahedral environments, with Co—N/O distances in the ranges 2.029 (3)–2.184 (3) and 2.028 (3)–2.163 (4) Å, respectively, and central angles in the ranges 90±13.26 (12) and 180±19.32 (16)° for Co2, and 90±7.14 (14) and 180±9.92 (13)° for Co3 (Table 1).
The two independent dap ligands are neutral and participate in both the Co1 coordination group (dap2, in µ1 mode, denoted a4 in Fig. 1) and the Co2–Co3 one (dap1, in N,N'-µ2 mode, denoted b1 in Fig 1). Both dap ligands present the same protonated N atom (N31 and N32 [Should these be N21 and N22?]) and thus the same prototropic state.
The cit tetra-anions provide for charge balance, compensating the 4+ cationic charge of the four Co2+ cations. This 4- charge comes from the unprotonated α-hydroxy, α-carboxylate and both β-carboxylate groups. The ligand bridges four different CoII cations through two bi-coordinated and three mono-coordinated O atoms. The resulting µ4-κ5-O:O,O':O',O'',O''':O'''' mode seems to be novel for this ligand, as revealed by a search of the CSD. This binding behaviour serves to give internal coherence to the Co2–Co3 group and at the same time provides a linkage between both groups to define chains running parallel to [201] (Fig 3).
Neighbouring chains are laterally interleaved and well connected via hydrogen bonding. Fig. 4 presents a view down [201], showing the hydrophilic parts of the structure (in bold) approaching each other normal to the b direction, while the hydrophobic parts (in lighter lines) form a kind of buffer, separating the former along b. The hydrogen-bonding contacts are almost impossible to represent in the projection shown, due to the heavy overlap, but are fully detailed in Table 2. The first four entries correspond to `intrachain' bonds, shown in Figs. 2(a) and 2(b), and they determine R11(6) rings (Bernstein et al., 1995). The remaining hydrogen bonds serve to interconnect the chains in all directions perpendicular to the chains, to form a strongly coupled three-dimensional network.
The individual involvement in the hydrogen bonding of each ligand type (taking into account only the well determined water molecules) is as follows, in a donor/acceptor sequence: dap 8/5, cit 0/5 and water 7/5. It is apparent from these figures that the neutral dap ligand plays a significant role in the stabilization of the structure.