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Acta Crystallogr Sect E Struct Rep Online. 2009 October 1; 65(Pt 10): m1256–m1257.
Published online 2009 September 30. doi:  10.1107/S160053680903863X
PMCID: PMC2970253

Hexakis(1H-imidazole-κN 3)cobalt(III) tris­(hexa­fluoridophosphate) hexa­hydrate

Abstract

In the crystal structure of the title compound, [Co(C3H4N2)6](PF6)3·6H2O, the CoIII atom lies on a special position with site-symmetry An external file that holds a picture, illustration, etc.
Object name is e-65-m1256-efi4.jpg and the P atom is located on a special position with site symmetry An external file that holds a picture, illustration, etc.
Object name is e-65-m1256-efi5.jpg. The CoIII atom has an almost ideal octa­hedral coordination formed by the N atoms of six imidazole ligands. The water mol­ecules form hydrogen-bonded helical chains propagating in [001] by O—H(...)O inter­actions with a distance of 2.913 (2) Å. They simultaneously inter­act as hydrogen-bond acceptors and donors with the cations and anions, respectively, resulting in the formation of a three-dimensional assembly. Weak C—H(...)F inter­actions further stabilize the crystal structure.

Related literature

For CoIII complexes with heterocycles, see: Wojtczak et al. (1990 [triangle]); Pazderski et al. (2008 [triangle]). For the hexa­kis(imidazole)-cobalt(III) ion in solution, see: Navon & Panigel (1989 [triangle]); Wiśniewska & Kita (2006 [triangle]). For Co—N bond distances in hexa­kis(imidazole)-cobalt(II) complexes, see: Tong et al. (2002 [triangle]). For CoIII—N and CoII—N bond lengths in hexa­ammine–cobalt complexes, see: Kime & Ibers (1969 [triangle]). The water mol­ecules present in the crystal structure form helical chains similar to those observed in a trichloro­phloroglucinol structure, see: Saha & Nangia (2005 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-m1256-scheme1.jpg

Experimental

Crystal data

  • [Co(C3H4N2)6](PF6)3·6H2O
  • M r = 1010.43
  • Trigonal, An external file that holds a picture, illustration, etc.
Object name is e-65-m1256-efi6.jpg
  • a = 20.9911 (13) Å
  • c = 7.0156 (9) Å
  • V = 2677.1 (4) Å3
  • Z = 3
  • Mo Kα radiation
  • μ = 0.77 mm−1
  • T = 100 K
  • 0.25 × 0.25 × 0.21 mm

Data collection

  • Bruker SMART APEX CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1997 [triangle]) T min = 0.832, T max = 0.856
  • 4893 measured reflections
  • 1373 independent reflections
  • 1288 reflections with I > 2σ(I)
  • R int = 0.026

Refinement

  • R[F 2 > 2σ(F 2)] = 0.031
  • wR(F 2) = 0.083
  • S = 1.08
  • 1373 reflections
  • 98 parameters
  • 3 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.54 e Å−3
  • Δρmin = −0.31 e Å−3

Data collection: SMART (Bruker, 2001 [triangle]); cell refinement: SAINT (Bruker, 2002 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: X-SEED (Barbour 2001 [triangle]); software used to prepare material for publication: SHELXL97.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680903863X/hg2572sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680903863X/hg2572Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors wish to thank the Nicolaus Copernicus University and the National Research Foundation of South Africa for financial support.

supplementary crystallographic information

Comment

During the course of ongoing studies on CoIII complexes with heterocycles (Wojtczak et al., 1990; Pazderski et al., 2008) the title compound (I) was isolated. The crystal structure of (I) is built of mononuclear [Co(imidazole)6]3+ trications with the Co1 atom lying on Wyckoff position 3a (site symmetry 3), PF6- anions with P atom lying on Wyckoff position 9 d (site symmetry 1) and lattice water molecules (Fig.1). It is worth mentioning that this is the first structure consisting of a hexakis(imidazole)-cobalt(III) cationic complex, whereas more than 15 structures consisting of a hexakis(imidazole)-cobalt(II) complex ion were reported. Furthermore, there are only two papers on the hexakis(imidazole)-cobalt(III) ion in solution, describing spectroscopic (Navon & Panigel, 1989) and kinetic properties (Wiśniewska & Kita, 2006) respectively. The CoIII ion has an almost ideal octahedral environment formed by six imidazole N atoms, with cis-N—Co—N angles of 88.68 (7)° and 91.32 (7)°. The planes of neighbouring imidazole rings are twisted from their usual perpendicular positions. This is the result of the extensive net of hydrogen bonds in the structure in which imidazole rings are involved (dihedral angle = 72.4 (6)°). The Co—N bond distance is equal to 1.961 (1) Å and as expected is slightly shorter than those reported for hexakis(imidazole)-cobalt(II) complexes with distances of 2.140±2.188 Å (Tong et al., 2002). A similar relation of bond lengths was reported for CoIII—N and Co(II)—N in hexaamminecobalt complexes (Kime & Ibers, 1969) with differences between those distances of 0.18 Å. The water molecules present in the crystal structure form helical chains (helix pitch = 7.016 (2) Å, c axis) similar to those observed in a trichlorophloroglucinol structure (Saha & Nangia, 2005). They are propagated in [001] directions by O1—H6···O1i interactions (symmetry operation: -y + 2/3, x-y + 1/3, z + 1/3) with a distance of 2.913 (2) Å), which are stabilized by hydrogen bonding with the remaining molecular units (Table 1) giving in turn a three-dimensional assembly. The weak C—H···F interactions (Table 1) further stabilize the packing arrangement (Fig. 2).

Experimental

A mixture of 11.84 g (174 mmol) of imidazole and 2.02 g (5 mmol) of Co(pyridine)3Cl3 was grinded for several minutes until the color changed from green to red. The mixture was subsequently dissolved in 100 ml of distilled water and the pH was adjusted to 2–3 by adding 3 M HCl. Then the mixture was diluted with water to a final volume of 2 l and passed through a Sephadex SP C-25 column starting with an aqueous 0.05 M HCl solution as eluent. The fraction obtained by using 0.2 M HCl was evaporated in a stream of cold air and the product [Co(imidazole)6]Cl3 was filtrated and washed with ethanol. 10 mg of this compound was placed in a 50 ml beaker and 20 ml of a saturated aqueous solution of NH4PF6 was added. Red crystals suitable for single-crystal X-ray analysis were obtained by slow evaporation.

Refinement

Water H atoms were located in a difference map and refined with a restrained O—H distance of 0.96 (3) Å, whereas Uiso(H) values were allowed to refine independently. The remaining H atoms were positioned geometrically, with C—H = 0.95 Å and N—H = 0.88 Å, and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C,N).

Figures

Fig. 1.
The molecular structure of (I), with the atom-numbering scheme [symmetry codes:(i) y,-x + y,-z; (ii) -x + y, -x, z; (iii) -x, -y, -z; (iv) -y, x-y, z; (v) x-y, x, -z; (vi) -x + 2/3,-y + 1/3,-z + 1/3]. Displacement ellipsoids are drawn at the 50% probability ...
Fig. 2.
The crystal packing of (I) viewed down [001] with the extensive net of hydrogen bonds leading to a three-dimensional arrangement (the red dashed lines indicate strong hydrogen bonding and the blue weak ones).

Crystal data

[Co(C3H4N2)6](PF6)3·6H2ODx = 1.880 Mg m3
Mr = 1010.43Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3Cell parameters from 3782 reflections
Hall symbol: -R 3θ = 3.1–28.2°
a = 20.9911 (13) ŵ = 0.77 mm1
c = 7.0156 (9) ÅT = 100 K
V = 2677.1 (4) Å3Block, red
Z = 30.25 × 0.25 × 0.21 mm
F(000) = 1530

Data collection

Bruker SMART APEX CCD area-detector diffractometer1373 independent reflections
Radiation source: fine-focus sealed tube1288 reflections with I > 2σ(I)
graphiteRint = 0.026
ω scansθmax = 28.2°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)h = −22→27
Tmin = 0.832, Tmax = 0.856k = −26→26
4893 measured reflectionsl = −9→8

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.031Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.083H atoms treated by a mixture of independent and constrained refinement
S = 1.08w = 1/[σ2(Fo2) + (0.0444P)2 + 4.9022P] where P = (Fo2 + 2Fc2)/3
1373 reflections(Δ/σ)max < 0.001
98 parametersΔρmax = 0.54 e Å3
3 restraintsΔρmin = −0.31 e Å3

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 (Å2)

xyzUiso*/Ueq
Co10.00000.00000.00000.01001 (15)
F20.25776 (5)0.09189 (5)0.20301 (16)0.0242 (3)
N10.05651 (7)0.08788 (7)0.15758 (19)0.0126 (3)
N30.14686 (7)0.19255 (7)0.2646 (2)0.0161 (3)
H30.19140.23020.28120.019*
C50.02873 (8)0.11667 (8)0.2899 (2)0.0155 (3)
H5−0.02130.09450.32850.019*
C20.12841 (8)0.13594 (8)0.1462 (2)0.0150 (3)
H20.16180.13070.06530.018*
C40.08453 (9)0.18177 (8)0.3556 (2)0.0171 (3)
H40.08100.21340.44640.020*
P10.33330.16670.16670.01496 (16)
F10.34563 (7)0.13360 (7)−0.02524 (19)0.0421 (4)
F30.37650 (6)0.13458 (7)0.2841 (2)0.0402 (4)
O10.27980 (6)0.31811 (6)0.37976 (18)0.0203 (3)
H60.3046 (15)0.3048 (15)0.473 (4)0.052 (8)*
H70.2625 (15)0.3462 (14)0.447 (4)0.051 (8)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Co10.00877 (17)0.00877 (17)0.0125 (3)0.00438 (9)0.0000.000
F20.0135 (4)0.0191 (5)0.0324 (6)0.0026 (4)0.0030 (4)0.0038 (4)
N10.0126 (6)0.0113 (6)0.0144 (6)0.0063 (5)−0.0004 (5)0.0004 (5)
N30.0148 (6)0.0122 (6)0.0179 (7)0.0041 (5)−0.0023 (5)−0.0005 (5)
C50.0158 (7)0.0158 (7)0.0158 (8)0.0085 (6)−0.0001 (5)−0.0015 (6)
C20.0137 (7)0.0137 (7)0.0171 (7)0.0063 (6)−0.0016 (5)−0.0009 (5)
C40.0205 (8)0.0153 (7)0.0161 (8)0.0095 (6)−0.0020 (6)−0.0023 (6)
P10.0104 (3)0.0156 (3)0.0172 (3)0.0052 (2)0.00177 (19)0.0010 (2)
F10.0372 (7)0.0354 (7)0.0378 (7)0.0062 (5)0.0167 (5)−0.0130 (5)
F30.0160 (5)0.0422 (7)0.0588 (9)0.0118 (5)0.0027 (5)0.0283 (6)
O10.0192 (6)0.0197 (6)0.0207 (6)0.0086 (5)−0.0039 (5)−0.0035 (5)

Geometric parameters (Å, °)

Co1—N11.9605 (13)C5—C41.361 (2)
Co1—N1i1.9605 (13)C5—H50.9500
Co1—N1ii1.9605 (13)C2—H20.9500
Co1—N1iii1.9605 (13)C4—H40.9500
Co1—N1iv1.9605 (13)P1—F1vi1.5939 (12)
Co1—N1v1.9605 (13)P1—F11.5938 (12)
F2—P11.5985 (9)P1—F2vi1.5985 (9)
N1—C21.3340 (19)P1—F3vi1.6012 (11)
N1—C51.3854 (19)P1—F31.6012 (11)
N3—C21.339 (2)O1—H60.96 (3)
N3—C41.369 (2)O1—H70.96 (3)
N3—H30.8800
N1—Co1—N1i88.68 (5)N1—C5—H5125.5
N1—Co1—N1ii91.32 (5)N1—C2—N3110.48 (14)
N1—Co1—N1v88.68 (5)N1—C2—H2124.8
N1—Co1—N1iii180.00 (9)N3—C2—H2124.8
N1v—Co1—N1iii91.32 (5)C5—C4—N3106.26 (14)
N1v—Co1—N1i91.32 (5)C5—C4—H4126.9
N1iii—Co1—N1i91.32 (5)N3—C4—H4126.9
N1v—Co1—N1ii180.00 (9)F1vi—P1—F1180.0
N1iii—Co1—N1ii88.68 (5)F1vi—P1—F289.75 (6)
N1i—Co1—N1ii88.68 (5)F1—P1—F290.25 (6)
N1—Co1—N1iv91.32 (5)F1vi—P1—F2vi90.25 (6)
N1v—Co1—N1iv88.68 (5)F1—P1—F2vi89.75 (6)
N1iii—Co1—N1iv88.68 (5)F2—P1—F2vi179.997 (1)
N1i—Co1—N1iv180.00 (5)F1vi—P1—F3vi90.13 (8)
N1ii—Co1—N1iv91.32 (5)F1—P1—F3vi89.86 (8)
C2—N1—C5105.91 (12)F2—P1—F3vi90.15 (6)
C2—N1—Co1126.96 (11)F2vi—P1—F3vi89.85 (6)
C5—N1—Co1126.84 (10)F1vi—P1—F389.86 (8)
C2—N3—C4108.30 (13)F1—P1—F390.14 (8)
C2—N3—H3125.8F2—P1—F389.85 (6)
C4—N3—H3125.8F2vi—P1—F390.15 (6)
C4—C5—N1109.04 (14)F3vi—P1—F3180.0
C4—C5—H5125.5H6—O1—H7105.7 (19)
N1v—Co1—N1—C2−98.46 (15)C2—N1—C5—C40.10 (17)
N1i—Co1—N1—C2−7.11 (13)Co1—N1—C5—C4−174.02 (11)
N1ii—Co1—N1—C281.54 (15)C5—N1—C2—N30.45 (17)
N1iv—Co1—N1—C2172.89 (13)Co1—N1—C2—N3174.56 (10)
N1v—Co1—N1—C574.46 (10)C4—N3—C2—N1−0.82 (18)
N1i—Co1—N1—C5165.81 (14)N1—C5—C4—N3−0.58 (18)
N1ii—Co1—N1—C5−105.54 (10)C2—N3—C4—C50.85 (18)
N1iv—Co1—N1—C5−14.19 (14)

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

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1—H6···O1vii0.96 (3)1.98 (3)2.913 (2)163 (3)
N3—H3···O10.881.982.834 (2)165
O1—H7···F3viii0.96 (3)2.10 (3)2.945 (2)146 (2)
C2—H2···F3ix0.952.343.042 (2)131
C4—H4···F1x0.952.403.303 (2)158

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG2572).

References

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