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Acta Crystallogr Sect E Struct Rep Online. 2009 October 1; 65(Pt 10): i71.
Published online 2009 September 12. doi:  10.1107/S1600536809036198
PMCID: PMC2970480

Hexaaqua­iron(II) bis­[fac-tribromido­tricarbonyl­ferrate(II)]

Abstract

In the title compound, [Fe(H2O)6][FeBr3(CO)3]2, both Fe atoms have an octa­hedral coordination and the bromide carbonyl complex has a fac-stereochemistry. The [Fe(H2O)6]2+ octa­hedron has point symmetry An external file that holds a picture, illustration, etc.
Object name is e-65-00i71-efi1.jpg and is slightly compressed along one O—Fe—O axis. The [FeBr3(CO)3] anion has point symmetry 1 and mean bond lengths of Fe—Br = 2.455 (5) Å and Fe—C = 1.809 (2) Å. The cation and anion complexes are mutually linked via O—H(...)Br hydrogen bonds with O(...)Br distances of 3.340 (3) to 3.388 (3) Å.

Related literature

For the chemistry of FeBr2(CO)4, see: Hieber & Bader (1928 [triangle]); Robertson et al. (2000 [triangle]). For the syntheses and crystal structures of anologous compounds with [(Fe/Co/Ru)(H2O)6]2+ cations and [(Ru/Os)(Cl/I)3(CO)3] complexes, see: Allen (2002 [triangle]); Taimisto et al. (2003 [triangle]); Haukka et al. (2006 [triangle]); Jakonen et al. (2007 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-00i71-scheme1.jpg

Experimental

Crystal data

  • [Fe(H2O)6][FeBr3(CO)3]2
  • M r = 923.17
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-65-00i71-efi2.jpg
  • a = 11.9334 (8) Å
  • b = 9.3394 (6) Å
  • c = 20.5775 (14) Å
  • V = 2293.4 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 12.37 mm−1
  • T = 100 K
  • 0.26 × 0.10 × 0.08 mm

Data collection

  • Bruker SMART APEX CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2003 [triangle]) T min = 0.15, T max = 0.37
  • 24075 measured reflections
  • 3316 independent reflections
  • 2674 reflections with I > 2σ(I)
  • R int = 0.061

Refinement

  • R[F 2 > 2σ(F 2)] = 0.034
  • wR(F 2) = 0.070
  • S = 1.04
  • 3316 reflections
  • 145 parameters
  • 18 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.98 e Å−3
  • Δρmin = −0.68 e Å−3

Data collection: SMART (Bruker, 2003 [triangle]); cell refinement: SAINT (Bruker, 2003 [triangle]); data reduction: SAINT and XPREP (Bruker, 2003 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Selected bond lengths (Å)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809036198/om2275sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809036198/om2275Isup2.hkl

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

Acknowledgments

Financial support by the FWF Austrian Science Fund (project No. P16600-N11) is gratefully acknowledged.

supplementary crystallographic information

Comment

FeBr2(CO)4, easily accessible by reaction of Fe(CO)5 with bromine (Hieber & Bader, 1928; Robertson et al., 2000), is stable under dry conditions but reacts readily with various protic or coordinating solvents and thus turned out to be an interesting precursor for iron complexes which are otherwise difficult to obtain. By treatment of FeBr2(CO)4 with wet benzene the title compound was obtained according to the equation: 3 FeBr2(CO)4 + 6H2O → Fe(H2O)6 + 2 FeBr3(CO)3 + 6 CO. The structure (Fig. 1) contains a [Fe(H2O)6]2+ octahedron with point symmetry 1 and a [FeBr3(CO)3]- octahedron with iron with point symmetry 1 (Fig. 1). The Fe—O bond lengths in [Fe(H2O)6]2+ (Table 1) correspond well with high-spin iron(II) in an axially weakly compressed octahedron. The [FeBr3(CO)3]- anion has a facial disposition of the bromide and carbonyl ligands and shows each three very uniform Fe—Br and Fe—C bond distances with mean values of Fe—Br = 2.455 (5) Å and Fe—C = 1.809 (2) Å (Table 1) consistent with a low-spin state. The bond angles about this iron deviate up to 5.6° from 90 and 180°. C—O bond lengths average to 1.128 (1) Å, and Fe—C—O angles 177.9 (10)°. Each of the three independent water molecules is coordinated by Fe1 and by pair of bromine atoms as hydrogen bond acceptors. Their coordination environments are pyramidal to flat pyramidal (O2w). The six independent O—H···Br bonds (Table 2) are quite uniform in distances and angles, all being essentially linear. The structure has various architectural aspects, but is best regarded as consisting of double layers of [FeBr3(CO)3] octahedra held together by interactions between the mainly inward-oriented CO groups whereas the bromine atoms define their outer surfaces (Fig. 2). These double layers are oriented parallel to (100) and centered at y = 1/4 and 3/4. Intercalated between these double layers are single layers of [Fe(H2O)6]2+ octahedra at z = 0, 1/2 and 1, which bridge the double layers via the O—H···Br hydrogen bonds. The title compound has no precedents in iron structural chemistry, but a few analogous [MX3(CO)3]- complexes are known for M = Ru, Os, Re, and X = Cl, Br, I (Cambridge Structural Database - CSD; Version 5.30 of November 2008; Allen, 2002). Most related to the title compound is [Ru(H2O)6]2+[RuCl3(CO)3]-2.2H2O (Taimisto et al., 2003), obtained from [RuCl2(CO)3]2 in wet CH2Cl2. It has, despite being triclinic (title compound is orthorhombic), an additional uncoordinated H2O, a structural architecture analogous to the title compound. More recently, this formerly unique compound was expanded into three isomorphous series of type 1, [(Fe/Co)(H2O)6]2+[(Ru/Os)Cl3(CO)3]-2, triclinic, space group P1, of type 2, [(Ru/Fe/Co)(H2O)6]2+[(Ru/Os)Cl3(CO)3]-2.2H2O, triclinic, space group P1, and of type 3, [(Fe/Co)(H2O)6]2+[RuI3(CO)3]-2.2H2O, monoclinic, space group P21/c (Haukka et al., 2006; Jakonen et al., 2007). All these compounds share the [MX3(CO)3]- (X = Cl, Br, I) double layer plus [M(H2O)6]2+ single layer architecture of the title compound with additional non-coordinated water molecules (structure types 2 and 3) being involved in the [M(H2O)6]2+ layers.

Experimental

The title compound was synthesized as follows: FeBr2(CO)4 (200 mg, 0.610 mmol; Hieber & Bader, 1928) was dissolved in wet benzene (20 ml, containing 1.67 mmol water) resulting in significant CO gas evolution. The solution was allowed to stand for 15 minutes until no further gas evolution was observed. The solution was set aside for about 1 h to give orange crystals of the title copound. Yield: 75 mg (40%).

Refinement

All H atoms belong to H2O molecules. They were refined in x,y,z using hard SADI restraints of program SHELXL97 (Sheldrick, 2008) to make all O—H bond lengths and all intramolecular H—H distances equal. Moreover, pairs of identical Uiso(H) values were refined for each water molecule.

Figures

Fig. 1.
Perspective view of the title compound with the atom numbering scheme. Atoms with primed labels are generated by inversion (-x,-y,-z). Displacement ellipsoids are at the 50% probability level.
Fig. 2.
Packing diagram of the title compound viewed down the a axis. [Fe(H2O)6] octahedra in green and stick bond representation, [FeBr3(CO)3] in ball-and-stick representation, hydrogen bonds shown as red broken lines.

Crystal data

[Fe(H2O)6][FeBr3(CO)3]2F(000) = 1728
Mr = 923.17Dx = 2.674 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 4102 reflections
a = 11.9334 (8) Åθ = 2.6–29.5°
b = 9.3394 (6) ŵ = 12.37 mm1
c = 20.5775 (14) ÅT = 100 K
V = 2293.4 (3) Å3Prism, brown
Z = 40.26 × 0.10 × 0.08 mm

Data collection

Bruker SMART APEX CCD diffractometer3316 independent reflections
Radiation source: fine-focus sealed tube2674 reflections with I > 2σ(I)
graphiteRint = 0.061
ω and [var phi] scansθmax = 30.0°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2003)h = −16→16
Tmin = 0.15, Tmax = 0.37k = −12→12
24075 measured reflectionsl = −28→28

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)] = 0.034Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.070H atoms treated by a mixture of independent and constrained refinement
S = 1.04w = 1/[σ2(Fo2) + (0.0343P)2] where P = (Fo2 + 2Fc2)/3
3316 reflections(Δ/σ)max = 0.001
145 parametersΔρmax = 0.98 e Å3
18 restraintsΔρmin = −0.67 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
Fe10.00000.00000.00000.01291 (15)
O1W−0.0694 (2)0.2102 (3)0.00795 (12)0.0182 (5)
O2W0.1316 (2)0.0750 (3)−0.06090 (15)0.0232 (6)
O3W0.0994 (2)0.0389 (3)0.08220 (14)0.0215 (6)
H1A−0.077 (4)0.227 (5)0.0468 (10)0.054 (12)*
H1B−0.037 (4)0.277 (4)−0.010 (2)0.054 (12)*
H2A0.194 (2)0.039 (4)−0.067 (2)0.052 (12)*
H2B0.132 (4)0.157 (3)−0.075 (2)0.052 (12)*
H3A0.104 (4)0.124 (2)0.091 (2)0.043 (11)*
H3B0.161 (2)0.001 (4)0.086 (2)0.043 (11)*
Fe2−0.00342 (4)0.48304 (5)0.17284 (2)0.01109 (11)
Br1−0.09906 (3)0.25138 (4)0.168259 (17)0.01518 (9)
Br2−0.11162 (3)0.57039 (4)0.079096 (17)0.01582 (9)
Br30.14630 (3)0.39406 (4)0.101623 (18)0.01610 (9)
C10.0671 (3)0.6547 (4)0.17014 (16)0.0147 (7)
O10.1100 (2)0.7616 (3)0.16509 (13)0.0217 (6)
C20.0777 (3)0.4172 (4)0.24072 (18)0.0146 (7)
O20.1272 (2)0.3740 (3)0.28314 (13)0.0205 (6)
C3−0.1149 (3)0.5406 (3)0.22633 (18)0.0147 (7)
O3−0.1840 (2)0.5739 (3)0.26062 (13)0.0194 (5)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Fe10.0130 (4)0.0108 (3)0.0149 (3)0.0008 (3)−0.0008 (3)−0.0007 (3)
O1W0.0231 (15)0.0132 (12)0.0182 (14)0.0015 (11)−0.0009 (11)−0.0008 (10)
O2W0.0206 (15)0.0173 (13)0.0317 (16)0.0026 (12)0.0083 (13)0.0042 (12)
O3W0.0220 (15)0.0165 (13)0.0260 (15)0.0059 (11)−0.0072 (12)−0.0062 (11)
Fe20.0113 (2)0.0102 (2)0.0117 (2)−0.00088 (19)0.00038 (19)−0.00026 (17)
Br10.01807 (18)0.01203 (17)0.01544 (17)−0.00387 (13)0.00183 (14)−0.00048 (12)
Br20.01585 (18)0.01523 (17)0.01639 (17)−0.00118 (13)−0.00296 (14)0.00300 (13)
Br30.01316 (18)0.01727 (17)0.01787 (18)−0.00097 (14)0.00263 (14)−0.00377 (13)
C10.0114 (17)0.0197 (18)0.0131 (17)0.0020 (14)−0.0001 (13)0.0008 (13)
O10.0247 (15)0.0175 (14)0.0229 (14)−0.0057 (11)0.0047 (11)0.0014 (10)
C20.0141 (18)0.0108 (15)0.0188 (18)−0.0040 (13)0.0031 (14)−0.0023 (13)
O20.0209 (14)0.0191 (13)0.0216 (14)0.0000 (11)−0.0051 (12)0.0006 (10)
C30.0187 (19)0.0087 (15)0.0167 (18)−0.0036 (13)−0.0032 (14)0.0016 (12)
O30.0188 (14)0.0184 (13)0.0209 (13)0.0018 (11)0.0031 (11)−0.0011 (10)

Geometric parameters (Å, °)

Fe1—O1W2.137 (3)O3W—H3B0.821 (19)
Fe1—O2W2.128 (3)Fe2—C11.812 (4)
Fe1—O3W2.098 (3)Fe2—C21.807 (4)
Fe1—O1Wi2.137 (3)Fe2—C31.808 (4)
Fe1—O2Wi2.128 (3)Fe2—Br12.4479 (6)
Fe1—O3Wi2.098 (3)Fe2—Br22.4605 (6)
O1W—H1A0.821 (19)Fe2—Br32.4558 (6)
O1W—H1B0.821 (19)C1—O11.126 (4)
O2W—H2A0.821 (19)C2—O21.128 (4)
O2W—H2B0.821 (19)C3—O31.129 (4)
O3W—H3A0.821 (19)
O3W—Fe1—O3Wi180.00 (18)Fe1—O3W—H3A113 (3)
O3W—Fe1—O2Wi89.97 (12)Fe1—O3W—H3B121 (3)
O3Wi—Fe1—O2Wi90.03 (12)H3A—O3W—H3B109 (3)
O3W—Fe1—O2W90.03 (12)C2—Fe2—C391.43 (16)
O3Wi—Fe1—O2W89.97 (12)C2—Fe2—C194.35 (15)
O2Wi—Fe1—O2W180.00 (16)C3—Fe2—C195.59 (15)
O3W—Fe1—O1W89.91 (10)C2—Fe2—Br188.80 (11)
O3Wi—Fe1—O1W90.09 (10)C3—Fe2—Br186.75 (11)
O2Wi—Fe1—O1W88.35 (10)C1—Fe2—Br1176.03 (11)
O2W—Fe1—O1W91.65 (10)C2—Fe2—Br387.49 (11)
O3W—Fe1—O1Wi90.09 (10)C3—Fe2—Br3177.51 (11)
O3Wi—Fe1—O1Wi89.91 (10)C1—Fe2—Br386.74 (11)
O2Wi—Fe1—O1Wi91.65 (10)Br1—Fe2—Br390.981 (19)
O2W—Fe1—O1Wi88.35 (10)C2—Fe2—Br2178.97 (12)
O1W—Fe1—O1Wi180.00 (14)C3—Fe2—Br289.57 (11)
Fe1—O1W—H1A107 (3)C1—Fe2—Br285.77 (11)
Fe1—O1W—H1B119 (4)Br1—Fe2—Br291.04 (2)
H1A—O1W—H1B109 (3)Br3—Fe2—Br291.50 (2)
Fe1—O2W—H2A128 (3)O1—C1—Fe2176.4 (3)
Fe1—O2W—H2B121 (3)O2—C2—Fe2178.8 (3)
H2A—O2W—H2B109 (3)O3—C3—Fe2178.4 (3)

Symmetry codes: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1W—H1A···Br10.82 (2)2.52 (2)3.340 (3)174 (4)
O1W—H1B···Br2ii0.82 (2)2.69 (2)3.475 (3)162 (5)
O2W—H2A···Br2iii0.82 (2)2.55 (2)3.373 (3)177 (5)
O2W—H2B···Br2ii0.82 (2)2.56 (2)3.341 (3)160 (5)
O3W—H3A···Br30.82 (2)2.58 (2)3.388 (3)169 (5)
O3W—H3B···Br3iv0.82 (2)2.53 (2)3.346 (3)177 (4)

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: OM2275).

References

  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Bruker (2003). SMART, SAINT, SADABS and XPREP Bruker AXS Inc., Madison, Wisconsin, USA.
  • Haukka, M., Jakonen, M., Nivajarvi, T. & Kallinen, M. (2006). Dalton Trans., pp. 3212–3220. [PubMed]
  • Hieber, W. & Bader, G. (1928). Chem. Ber.61, 1717–1722.
  • Jakonen, M., Hirva, P., Nivajarvi, T., Kallinen, M. & Haukka, M. (2007). Eur. J. Inorg. Chem.2007, 3497–3508.
  • Robertson, E. W., Wilkin, O. M. & Young, N. A. (2000). Polyhedron, 19, 1493–1502.
  • Sheldrick, G. M. (2008). Acta Cryst A64, 112–122. [PubMed]
  • Taimisto, M., Oilunkaniemi, R., Laitinen, R. S. & Ahlgren, M. (2003). Z. Naturforsch. Teil B, 58, 959–964.

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