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The anion of the title complex, (C12H14N2)[Co2(C6H4O7)2(H2O)2], is a centrosymmetric edge-shared biocta­hedral dimer, in which the two Co atoms are bridged by two alkoxide O atoms of the fully deprotonated citrate ligands. All of the carboxyl­ate groups coordinate in a monodentate fashion to terminal positions, and two water mol­ecules complete the slightly distorted octa­hedral coordination. The dinuclear cation complex and the dianion are organized around inversion centers. Supra­molecular O—H...O and N—H...O inter­actions stabilize the architecture.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807049124/dn2240sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807049124/dn2240Isup2.hkl
Contains datablock I

CCDC reference: 627044

Key indicators

  • Single-crystal X-ray study
  • T = 298 K
  • Mean [sigma](C-C) = 0.006 Å
  • R factor = 0.040
  • wR factor = 0.118
  • Data-to-parameter ratio = 11.9

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT154_ALERT_1_C The su's on the Cell Angles are Equal (x 10000) 100 Deg. PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 = 4 PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X) Co1 - O4 .. 5.50 su PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor .... 2.13
Alert level G PLAT794_ALERT_5_G Check Predicted Bond Valency for Co1 (2) 2.56 PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 3
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 4 ALERT level C = Check and explain 2 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 2 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check

Comment top

The prevalent citric acid has been widely known for its abundance in physiological fluids(Srere, 1972). Binuclear iron complexes were studied long ago by the pioneer Marray (Marray, 1974). The structures and properties of such systems depend on the coordination and geometric preferences of both the central metals ions and bridging building blocks as well as the influence of weaker non-covalent interactions, such as hydrogen bonds and π-π stacking interactions. In this paper, we report the synthesis and crystal structure of the title complex,(I).

The anionic complex I is an edge-shared bi-octahedral dimer with centro-symmetric structure, in which the two iron atoms are bridged by two alkoxide oxygen atoms of the fully deprotonated citrate ligands. All of the carboxylate groups coordinate in a mono-dentate fashion to terminal positions, and two water molecules complete the slightly distorted octahedral coordination spheres. This structure is very similar to those reported by Shweky and coworkers (Shweky et al., 1994). The chelating of the deprotonated hydroxyl and carboxylic groups of the citrate ion leads to two six-membered rings and one five-membered ring, perhaps stabilizing the overall dimeric moiety. Fe—O bond lengths range from 1.9682 (2) -2.0294 (19) Å. Supramolecular interactions (O—H···O and N—H···O) stabilize the architecture(Table 1).

Related literature top

For related literature, see: Shweky et al. (1994); Srere (1972); Marray (1974).

Experimental top

citric acid(0.032 g, 0.062 mmol), CoCl2 (0.18 g, 0.21 mmol) and bpa (0.026 g, 0.019 mmol) and NaOH(0.048 mmol,0.12 mmol), were added in a mixed solvent of ethanol and acetonitrile, the mixture was heated for five hours under reflux. during the process stirring and influx were required. The resultant was then filtered to give a pure solution which was infiltrated by diethyl ether freely in a closed vessel, a weeks later some single crystals of the size suitable for X-Ray diffraction analysis.

Refinement top

All H atoms attached to C atoms and N atom were fixed geometrically and treated as riding with C—H = 0.93 Å (aromatic) or 0.97 Å (methylene) and N—H = 0.86 Å with Uiso(H) = 1.2Ueq(C or N). H atoms of water molecule were located in difference Fourier maps and included in the subsequent refinement using restraints (O—H= 0.85 (1)Å and H···H= 1.39 (2) Å) with Uiso(H) = 1.5Ueq(O).

Structure description top

The prevalent citric acid has been widely known for its abundance in physiological fluids(Srere, 1972). Binuclear iron complexes were studied long ago by the pioneer Marray (Marray, 1974). The structures and properties of such systems depend on the coordination and geometric preferences of both the central metals ions and bridging building blocks as well as the influence of weaker non-covalent interactions, such as hydrogen bonds and π-π stacking interactions. In this paper, we report the synthesis and crystal structure of the title complex,(I).

The anionic complex I is an edge-shared bi-octahedral dimer with centro-symmetric structure, in which the two iron atoms are bridged by two alkoxide oxygen atoms of the fully deprotonated citrate ligands. All of the carboxylate groups coordinate in a mono-dentate fashion to terminal positions, and two water molecules complete the slightly distorted octahedral coordination spheres. This structure is very similar to those reported by Shweky and coworkers (Shweky et al., 1994). The chelating of the deprotonated hydroxyl and carboxylic groups of the citrate ion leads to two six-membered rings and one five-membered ring, perhaps stabilizing the overall dimeric moiety. Fe—O bond lengths range from 1.9682 (2) -2.0294 (19) Å. Supramolecular interactions (O—H···O and N—H···O) stabilize the architecture(Table 1).

For related literature, see: Shweky et al. (1994); Srere (1972); Marray (1974).

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, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Bruker, 2004).

Figures top
[Figure 1] Fig. 1. Molecular view of (I), showing the atom-labelling scheme.Displacement ellipsoids are shown at the 50% probability level. H atoms not involved in H bonding were omitted for clarity. H bond is represented as dashed line. [Symmetry codes: (i) -x, -y, -z; (ii) 1 - x, -y + 1, -z + 1]
4,4'-(Ethane-1,2-diyl)dipyridinium di-µ-citrato-bis[aquacobaltate(II)] top
Crystal data top
(C12H14N2)[Co2(C6H4O7)2(H2O)2]Z = 1
Mr = 716.33F(000) = 366
Triclinic, P1Dx = 1.798 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 8.2975 (6) ÅCell parameters from 2437 reflections
b = 9.2340 (6) Åθ = 2.4–25.5°
c = 9.9647 (7) ŵ = 1.34 mm1
α = 65.242 (1)°T = 298 K
β = 72.803 (1)°Block, purple
γ = 85.004 (1)°0.25 × 0.20 × 0.18 mm
V = 661.72 (8) Å3
Data collection top
Bruker APEXII area-detector
diffractometer
2437 independent reflections
Radiation source: fine-focus sealed tube1949 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.024
φ and ω scansθmax = 25.5°, θmin = 2.4°
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
h = 1010
Tmin = 0.730, Tmax = 0.794k = 1111
5003 measured reflectionsl = 1112
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.118H atoms treated by a mixture of independent and constrained refinement
S = 1.15 w = 1/[σ2(Fo2) + (0.0605P)2 + 0.3131P]
where P = (Fo2 + 2Fc2)/3
2437 reflections(Δ/σ)max = 0.001
205 parametersΔρmax = 0.41 e Å3
3 restraintsΔρmin = 0.42 e Å3
Crystal data top
(C12H14N2)[Co2(C6H4O7)2(H2O)2]γ = 85.004 (1)°
Mr = 716.33V = 661.72 (8) Å3
Triclinic, P1Z = 1
a = 8.2975 (6) ÅMo Kα radiation
b = 9.2340 (6) ŵ = 1.34 mm1
c = 9.9647 (7) ÅT = 298 K
α = 65.242 (1)°0.25 × 0.20 × 0.18 mm
β = 72.803 (1)°
Data collection top
Bruker APEXII area-detector
diffractometer
2437 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
1949 reflections with I > 2σ(I)
Tmin = 0.730, Tmax = 0.794Rint = 0.024
5003 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0403 restraints
wR(F2) = 0.118H atoms treated by a mixture of independent and constrained refinement
S = 1.15Δρmax = 0.41 e Å3
2437 reflectionsΔρmin = 0.42 e Å3
205 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
xyzUiso*/Ueq
C10.1731 (5)0.4450 (5)0.1202 (5)0.0362 (9)
H10.19840.53640.21210.043*
C20.0838 (5)0.3211 (5)0.1064 (5)0.0362 (9)
H20.04760.32800.18870.043*
C30.0457 (5)0.1833 (4)0.0304 (5)0.0301 (9)
C40.1005 (5)0.1797 (5)0.1488 (5)0.0387 (10)
H40.07560.09020.24230.046*
C50.1921 (6)0.3075 (5)0.1301 (5)0.0424 (10)
H50.23070.30370.21010.051*
C60.0508 (5)0.0426 (5)0.0481 (5)0.0408 (10)
H6A0.15320.07900.01810.049*
H6B0.08340.03210.15580.049*
C70.3768 (4)0.8568 (4)0.5276 (4)0.0250 (8)
C80.4315 (5)0.8961 (4)0.3551 (4)0.0249 (8)
H8A0.55010.92990.31190.030*
H8B0.36720.98350.30340.030*
C90.4036 (4)0.7508 (4)0.3268 (4)0.0223 (7)
C100.4320 (5)0.7938 (4)0.1559 (4)0.0266 (8)
H10A0.36290.88290.11610.032*
H10B0.54920.82900.10140.032*
C110.3911 (4)0.6584 (4)0.1209 (4)0.0270 (8)
C120.2187 (4)0.6843 (4)0.4158 (4)0.0263 (8)
Co10.59943 (6)0.58334 (5)0.56194 (6)0.02524 (19)
N10.2251 (4)0.4365 (4)0.0025 (4)0.0354 (8)
H1A0.28120.51640.01280.043*
O20.4294 (3)0.7270 (3)0.6167 (3)0.0266 (6)
O30.2835 (3)0.9445 (3)0.5786 (3)0.0369 (7)
O40.5154 (3)0.6288 (2)0.3798 (3)0.0197 (5)
O50.1040 (3)0.7783 (3)0.3903 (4)0.0434 (8)
O60.1985 (3)0.5377 (3)0.5056 (3)0.0258 (6)
O70.3682 (4)0.6921 (3)0.0064 (3)0.0396 (7)
O80.3806 (3)0.5148 (3)0.2227 (3)0.0310 (6)
O1W0.7770 (3)0.7550 (3)0.4890 (4)0.0345 (7)
H1W0.8825 (16)0.746 (5)0.474 (5)0.052*
H2W0.751 (5)0.842 (3)0.497 (5)0.052*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.036 (2)0.029 (2)0.036 (2)0.0009 (17)0.0031 (18)0.0102 (18)
C20.035 (2)0.041 (2)0.039 (2)0.0038 (18)0.0100 (19)0.021 (2)
C30.0242 (19)0.026 (2)0.040 (2)0.0006 (15)0.0032 (17)0.0178 (18)
C40.044 (2)0.028 (2)0.040 (2)0.0026 (18)0.013 (2)0.0076 (19)
C50.048 (3)0.038 (2)0.049 (3)0.001 (2)0.019 (2)0.023 (2)
C60.032 (2)0.037 (2)0.055 (3)0.0074 (18)0.005 (2)0.023 (2)
C70.0204 (18)0.0183 (18)0.039 (2)0.0032 (14)0.0100 (16)0.0130 (16)
C80.0284 (19)0.0135 (17)0.036 (2)0.0015 (14)0.0163 (16)0.0085 (16)
C90.0240 (18)0.0166 (17)0.0276 (19)0.0044 (14)0.0131 (15)0.0073 (15)
C100.0290 (19)0.0185 (18)0.031 (2)0.0011 (15)0.0143 (16)0.0046 (16)
C110.0259 (19)0.024 (2)0.033 (2)0.0018 (15)0.0118 (16)0.0113 (17)
C120.0257 (19)0.025 (2)0.032 (2)0.0001 (15)0.0097 (16)0.0141 (17)
Co10.0252 (3)0.0191 (3)0.0329 (3)0.00227 (19)0.0123 (2)0.0098 (2)
N10.0302 (18)0.0284 (18)0.052 (2)0.0042 (14)0.0089 (16)0.0214 (17)
O20.0298 (14)0.0190 (13)0.0310 (14)0.0063 (10)0.0096 (11)0.0109 (11)
O30.0383 (16)0.0238 (14)0.0491 (18)0.0085 (12)0.0081 (13)0.0199 (13)
O40.0202 (12)0.0143 (11)0.0268 (13)0.0037 (9)0.0114 (10)0.0080 (10)
O50.0209 (14)0.0209 (14)0.075 (2)0.0064 (11)0.0141 (14)0.0082 (14)
O60.0220 (13)0.0151 (12)0.0352 (15)0.0006 (10)0.0063 (11)0.0067 (11)
O70.063 (2)0.0270 (15)0.0338 (16)0.0007 (13)0.0263 (15)0.0089 (13)
O80.0460 (16)0.0192 (13)0.0326 (15)0.0016 (11)0.0199 (13)0.0094 (12)
O1W0.0210 (13)0.0172 (13)0.0636 (19)0.0006 (10)0.0119 (14)0.0152 (13)
Geometric parameters (Å, º) top
C1—N11.336 (5)C9—O41.421 (4)
C1—C21.354 (5)C9—C101.525 (5)
C1—H10.9300C9—C121.556 (5)
C2—C31.392 (5)C10—C111.519 (5)
C2—H20.9300C10—H10A0.9700
C3—C41.372 (6)C10—H10B0.9700
C3—C61.505 (5)C11—O71.243 (4)
C4—C51.376 (5)C11—O81.279 (4)
C4—H40.9300C12—O51.240 (4)
C5—N11.328 (5)C12—O61.264 (4)
C5—H50.9300Co1—O21.968 (2)
C6—C6i1.512 (8)Co1—O8ii2.002 (2)
C6—H6A0.9700Co1—O42.004 (2)
C6—H6B0.9700Co1—O1W2.005 (2)
C7—O31.231 (4)Co1—O4ii2.031 (2)
C7—O21.289 (4)Co1—O6ii2.037 (2)
C7—C81.529 (5)N1—H1A0.8600
C8—C91.530 (4)O1W—H1W0.84 (3)
C8—H8A0.9700O1W—H2W0.84 (3)
C8—H8B0.9700
N1—C1—C2120.3 (4)C9—C10—H10A108.6
N1—C1—H1119.9C11—C10—H10B108.6
C2—C1—H1119.9C9—C10—H10B108.6
C1—C2—C3120.4 (4)H10A—C10—H10B107.6
C1—C2—H2119.8O7—C11—O8122.4 (3)
C3—C2—H2119.8O7—C11—C10118.3 (3)
C4—C3—C2117.5 (3)O8—C11—C10119.4 (3)
C4—C3—C6120.9 (4)O5—C12—O6125.6 (3)
C2—C3—C6121.5 (4)O5—C12—C9117.5 (3)
C3—C4—C5120.4 (4)O6—C12—C9116.9 (3)
C3—C4—H4119.8O2—Co1—O8ii90.26 (10)
C5—C4—H4119.8O2—Co1—O487.83 (9)
N1—C5—C4119.8 (4)O8ii—Co1—O4161.06 (10)
N1—C5—H5120.1O2—Co1—O1W88.52 (10)
C4—C5—H5120.1O8ii—Co1—O1W93.52 (11)
C3—C6—C6i112.5 (4)O4—Co1—O1W105.27 (11)
C3—C6—H6A109.1O2—Co1—O4ii109.39 (10)
C6i—C6—H6A109.1O8ii—Co1—O4ii85.02 (9)
C3—C6—H6B109.1O4—Co1—O4ii77.87 (10)
C6i—C6—H6B109.1O1W—Co1—O4ii162.01 (10)
H6A—C6—H6B107.8O2—Co1—O6ii171.24 (9)
O3—C7—O2121.8 (3)O8ii—Co1—O6ii90.27 (10)
O3—C7—C8120.9 (3)O4—Co1—O6ii94.46 (9)
O2—C7—C8117.2 (3)O1W—Co1—O6ii82.72 (10)
C7—C8—C9110.9 (3)O4ii—Co1—O6ii79.36 (9)
C7—C8—H8A109.5C5—N1—C1121.5 (3)
C9—C8—H8A109.5C5—N1—H1A119.2
C7—C8—H8B109.5C1—N1—H1A119.2
C9—C8—H8B109.5C7—O2—Co1129.2 (2)
H8A—C8—H8B108.0C9—O4—Co1125.0 (2)
O4—C9—C10107.7 (3)C9—O4—Co1ii107.50 (18)
O4—C9—C8111.2 (3)Co1—O4—Co1ii102.13 (10)
C10—C9—C8111.7 (3)C12—O6—Co1ii110.2 (2)
O4—C9—C12108.8 (3)C11—O8—Co1ii133.7 (2)
C10—C9—C12108.7 (3)Co1—O1W—H1W128 (3)
C8—C9—C12108.7 (3)Co1—O1W—H2W121 (3)
C11—C10—C9114.5 (3)H1W—O1W—H2W109 (5)
C11—C10—H10A108.6
Symmetry codes: (i) x, y, z; (ii) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O70.861.862.714 (4)169
O1W—H1W···O5iii0.84 (3)1.77 (2)2.593 (3)163 (4)
O1W—H2W···O3iv0.84 (3)1.82 (2)2.608 (3)154 (4)
Symmetry codes: (iii) x+1, y, z; (iv) x+1, y+2, z+1.

Experimental details

Crystal data
Chemical formula(C12H14N2)[Co2(C6H4O7)2(H2O)2]
Mr716.33
Crystal system, space groupTriclinic, P1
Temperature (K)298
a, b, c (Å)8.2975 (6), 9.2340 (6), 9.9647 (7)
α, β, γ (°)65.242 (1), 72.803 (1), 85.004 (1)
V3)661.72 (8)
Z1
Radiation typeMo Kα
µ (mm1)1.34
Crystal size (mm)0.25 × 0.20 × 0.18
Data collection
DiffractometerBruker APEXII area-detector
Absorption correctionMulti-scan
(SADABS; Bruker, 2004)
Tmin, Tmax0.730, 0.794
No. of measured, independent and
observed [I > 2σ(I)] reflections
5003, 2437, 1949
Rint0.024
(sin θ/λ)max1)0.606
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.118, 1.15
No. of reflections2437
No. of parameters205
No. of restraints3
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.41, 0.42

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPIII (Burnett & Johnson, 1996) and ORTEP-3 for Windows (Farrugia, 1997), SHELXTL (Bruker, 2004).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O70.861.862.714 (4)169.3
O1W—H1W···O5i0.84 (3)1.773 (17)2.593 (3)163 (4)
O1W—H2W···O3ii0.84 (3)1.82 (2)2.608 (3)154 (4)
Symmetry codes: (i) x+1, y, z; (ii) x+1, y+2, z+1.
 

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