A polymeric form of basic iron(III) acetate with an acetic acid ligand

A new crystalline com­pound, catena-poly[hexa-μ-acetato-(acetic acid)-μ₃-oxido-triangulo-triiron(III)]-μ-acetato], [Fe₃(C₂H₃O₂)₇O(C₂H₄O₂)]_n, incorporating the basic ferric acetate unit, has been obtained from an acetic anhydride solution of hydrated iron(III) nitrate. The crystals have the com­position Fe₃O(OAc)₇(HOAc) (HOAc is acetic acid) and include the well-known [Fe₃O(OAc)₆]⁺ unit, in which the Fe^III centres are linked to a central coplanar μ₃-oxido ligand. Acetate ions provide bridges between pairs of Fe^III centres. These individual [Fe₃O(OAc)₆]⁺ units are linked by additional bridging acetate anions to form zigzag chains. The bridging acetate ions coordinate to a position trans to the oxido group on two of the Fe^III centres. Remarkably, the trans site on the third Fe^III centre is occupied by the carbonyl group of an acetic acid mol­ecule. This is the first reported case of an acetic acid mol­ecule coordinating to an Fe^III centre. Not surprisingly, the acetic acid mol­ecule is only weakly coordinating, resulting in a short Fe—O(oxido) bond trans to the carbonyl group. The trans influence apparent in this structure provides an inter­esting contrast with the structurally similar Mn^III analogue, in which the corresponding pair of trans bonds are both elongated because of the Jahn–Teller effect.

1. Introduction

In the field of coordination chemistry, carboxyl­ate ions feature prominently in the formation of a wide variety of metal com­plexes. Although the carboxyl­ate group is capable of chelation, it is not a strongly favoured coordination mode because of the strain associated with the four-membered ring. It is far more common for the carboxyl­ate ion to span a pair of metal centres, as it does in com­plexes such as copper acetate, where four bridging acetate anions bridge a pair of Cu^II centres (van Niekerk & Schoening, 1953). A similar structure is adopted by molybdenum acetate, which features a re­mark­able quadruple bond between the Mo^II centres (Lawton & Mason, 1965; Cotton et al., 2005). In the case of basic zinc acetate, four Zn^II centres, at the vertices of a tetra­hedron, are bound to a central oxido anion (μ₄), while six acetate anions bridge pairs of Zn^II centres along the six edges of the tetra­hedron (Wyart, 1926). The six methyl groups are oriented outwards towards the vertices of an octa­hedron. Basic beryllium acetate adopts a similar structure (Pauling & Sherman, 1934).

The basic ferric acetate cation contains the [Fe₃O(OAc)₆]⁺ unit and consists of a planar μ₃-oxido group bound to a trio of Fe^III centres at the vertices of what is essentially an equilateral triangle (e.g. Anson et al., 1987; Balić et al., 2021; Abánades Lázaro et al., 2023). Each pair of Fe^III centres is bridged by a pair of acetate anions, one above and one below the plane of the Fe₃O entity, to give a unit which has approximate D_3h symmetry. The site trans to the oxido group on each metal is typically occupied by a monodentate ligand such as water. The methyl groups in this com­plex are directed towards the ver­tices of a trigonal prism. This type of unit may also be gen­er­at­ed with trivalent Cr (Figgis & Robertson, 1965), Mn (Hessel & Romers, 1969) and Ru (Nikolaou et al., 2023) centres, and can also exist for metals in mixed +2 and +3 oxidation states (Sato et al., 1996; Wei et al., 2020). Within the Cambridge Structural Database (CSD; Version 5.45, March 2024 release; Groom et al., 2016), 83 structures have been reported which contain the [Fe₃O(OAc)₆L₃] unit, where L may be a neutral or charged ligand. The net charge on the [Fe₃O(OAc)₆L₃] com­plex is typically balanced by a non-co­or­din­ating ion, such as chloride or perchlorate.

In the current work, we report the serendipitous isolation of basic ferric acetate crystals which display a significant distortion from the symmetric oxido bridge that is commonly ob­ser­ved with basic ferric carboxyl­ate structures and rationalize this reduced symmetry in terms of a significant trans influence.

2. Experimental

2.1. Synthesis and crystallization

In an attempt to prepare Fe-based coordination polymers incorporating the dianion of hy­droxy­benzoic acid (H₂hba), three acetic anhydride (Ac₂O) solutions were prepared. Fe(NO₃)₃·9H₂O (202 mg) was dissolved in Ac₂O (3 ml), H₂hba (110 mg) was dissolved in Ac₂O (2 ml) and LiOAc (255 mg) was dissolved in Ac₂O (3 ml). The solutions were mixed and heated to boiling on a hotplate. Small red–brown crystals were obtained from the cooled solution.

2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The H atoms were placed in calculated positions and refined as riding atoms, with U_iso(H) = 1.5U_eq(C) and C—H = 0.99 Å for methyl groups, and U_iso(H) = 1.5U_eq(O) and O—H = 0.85 Å for the hydroxy H atom.

Table 1
Experimental details

Crystal data
Chemical formula	[Fe3(C2H3O2)7O(C2H4O2)]
Mr	656.91
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	100
a, b, c (Å)	15.8661 (3), 15.8640 (3), 19.5003 (5)
V (Å^3)	4908.22 (18)
Z	8
Radiation type	Cu Kα
μ (mm^−1)	14.77
Crystal size (mm)	0.17 × 0.06 × 0.03
Data collection
Diffractometer	Rigaku XtaLAB Synergy Dualflex diffractometer with a HyPix detector
Absorption correction	Multi-scan (CrysAlis PRO; Rigaku OD, 2023)
Tmin, Tmax	0.408, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	38581, 5150, 3889
Rint	0.097
(sin θ/λ)max (Å^−1)	0.634
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.056, 0.156, 1.06
No. of reflections	5150
No. of parameters	365
No. of restraints	33
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å^−3)	0.88, −0.78
Computer programs: CrysAlis PRO (Rigaku OD, 2023), SHELXT2018 (Sheldrick, 2015a), SHELXL2018 (Sheldrick, 2015b), CrystalMaker (Palmer, 2020) and OLEX2 (Dolomanov et al., 2009).

Whilst the coordinated acetic acid mol­ecule was clearly defined in the solution and subsequent refinement, peaks of residual electron density in the Fourier difference map were consistent with a second overlapping location for the acetic acid mol­ecule. The peaks were assigned as acetic acid atoms and refined with com­plementary site occupancies. The result of the refinement showed two chemically similar positions for the coordinated acetic acid mol­ecule (Fig. 1), with the occupancies for the major and minor positions refining to 86 and 14%, respectively. The carbonyl O atom was common to both orientations. For each of the positions of the acetic acid molecule, the hydroxyl group forms a hydrogen-bonding interaction with a neighbouring O atom of a coordinated acetate group [O15⋯O1 = 2.598 (6) Å and O15A⋯O12 = 2.62 (3) Å]. A peak of electron density (0.35 e Å⁻³) was apparent between O15 and O1 (corresponding to the major orientation), and was consistent with the hydroxyl H atom. Hydroxyl H atoms were assigned, riding on O15 and O15A, with appropriate site occupancies. Details of the refinements can be found in the embedded instruction files in the CIF file.

Figure 1 The structure of 1, showing the disordered acetic acid group (top) with the atom-labelling scheme. The acetate group coordinated to Fe2 is also shown. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented by spheres of arbitrary size. The red dotted lines represent hy­dro­gen-bonding inter­actions.

3. Results and discussion

The combination of Fe(NO₃)₃, H₂hba and LiOAc in acetic an­hy­dride yielded crystals of com­position Fe₃O(OAc)₇(HOAc) (1). The structure consists of the common basic ferric acetate core in which three crystallographically distinct Fe^III centres bind to a central oxido dianion and six acetate ligands, each in a syn–syn conformation, spanning pairs of Fe^III centres, as indicated in Fig. 1. Whilst the [Fe₃O(O₂CR)₆]⁺ unit (R = alkyl or aryl group) is a common fragment, the structure reported here is unique because of the ligands that are trans to the oxido group on each Fe centre. The trans sites on two of the Fe centres are occupied by bridging acetate anions which adopt a syn–anti configuration. These two anions are symmetry related to each other and result in the formation of a zigzag chain which extends parallel to the a direction, as indicated in Fig. 2. With the [Fe₃O(OAc)₆]⁺ units bridged by a pair of ace­tate anions to symmetry-related counterparts, charge balance is achieved for this 1D coordination polymer.

Figure 2 The polymeric structure of 1, showing the zigzag chain extending in the a direction. C—O and C—C bonds are indicated by orange connections, Fe—O bonds by green connections and hy­dro­gen bonds between the acetic acid hydroxyl O atoms and neighbouring acetate O atoms by striped connections. H atoms have been omitted for clarity.

Only a neutral ligand is required to com­plete the octa­hedral geometry on the remaining Fe centre. Ligands such as water could normally fulfil this role, but under anhydrous conditions, obtained using a solvent such as acetic anhydride, this is not possible. Remarkably, an acetic acid mol­ecule coordinates to this Fe centre, as indicated in Figs. 1 and 2. The neutral mol­ecule coordinates through a carbonyl O atom, while the hy­droxyl group forms a geometrically favourable hy­dro­gen bond with a coordinated O atom of a neighbouring acetate anion. The carbonyl bond distance (C15—O16) of 1.207 (7) Å is significantly shorter than the C—OH bond [C15—O15 = 1.329 (8) Å]. Whilst the difference in C—O bond distances is expected for an acetic acid mol­ecule, it contrasts with the acetate anions, in which the C—O bonds have an inter­mediate bond length (∼1.25 Å).

The [Fe₃O(OAc)₆(H₂O)₃]⁺ fragment which is present in numerous crystal structures possesses a μ₃-oxido anion that forms Fe—O bonds of relatively similar length (see Table 2). In contrast, the three Fe—O(oxido) bond lengths in 1 show significant variation (Table 3), with the Fe—O bond (Fe3—O17) trans to the coordinated acetic acid being significantly shorter [1.872 (3) Å] than the other Fe—O bonds which are trans to a bridging acetate anion [1.921 (3) and 1.940 (3) Å for Fe1—O17 and Fe2—O17, respectively]. This would appear to indicate a trans influence associated with the relatively weak coordination of the carbonyl O atom from the acetic acid mol­ecule, which displays an Fe—O bond length of 2.144 (3) Å (Fe3—O16). In contrast, the bond lengths involving the acetate O atoms trans to O17 on Fe1 and Fe2 are 2.012 (3) and 2.014 (3) Å, respectively. Further distortion of the octa­hedral coordination geometry of Fe3 is apparent with the Fe centre lying 0.2585 (19) Å out of the plane of the ace­tate O atoms (O1, O10, O12 and O14) towards the μ₃-oxido atom (O17). In contrast, Fe1 and Fe2 lie only 0.1352 (17) and 0.1202 (19) Å, respectively, out of the plane of the cor­responding acetate O atoms.

Table 2
Fe—O bond lengths (Å) in typical com­pounds containing an [Fe₃O(OAc)₆(H₂O)₃]⁺ unit

Compound	Individual Fe—μ3-O(oxido) bond lengths	CSD refcode	Reference
[Fe3O(OAc)6(H2O)3]NO3·2C6H12N4·5H2O	1.9034 (8), 1.9034 (8), 1.9057 (16)	EMAVAS	Balić et al. (2021)
[Fe3O(OAc)6(H2O)3]NO3·C2H4O2	1.8961 (12), 1.8983 (11), 1.9120 (11)	GIZSEO03	Nieger (2016)
[Fe3O(OAc)6(H2O)3]Cl·6H2O	1.896 (4), 1.892 (4), 1.904 (4)	RIPLEH01	Shova et al. (1998)
[Fe3O(OAc)6(H2O)3]ClO4·3H2O	1.8969 (12), 1.8965 (11), 1.9043 (13)	LINHEZ	Abánades Lázaro et al. (2023)

Table 3
Fe—O(μ₃-oxido) bond lengths (Å) in 1

Bond	Bond length
Fe(bonded to acetic acid)—O(μ3-oxido)	Fe3—O17 1.872 (3)
Fe(bonded only to acetate)—O(μ3-oxido)	Fe1—O17 1.921 (3)
	Fe2—O17 1.940 (3)

To the best of our knowledge, this is the first recorded example of the coordination of an acetic acid mol­ecule to an Fe^III centre (CSD; Groom et al., 2016). This is perhaps not surprising given that in its acid form, the Lewis basicity of acetic acid is expected to be very low. Its coordination in this present case may be attributed to the absence of solvent mol­ecules that can serve as Lewis bases and the fact that the hydroxyl group of the acetic acid mol­ecule is in an ideal position to form a relatively strong hy­dro­gen bond with a neighbouring coordinated O atom [O15⋯O1 = 2.598 (6) Å and O15A⋯O12 = 2.62 (3) Å].

Although there are numerous potential O-atom acceptor sites for hy­dro­gen bonding, the only O—H donor group, belonging to the acetic acid mol­ecule, forms an intra­chain hy­dro­gen bond (O15⋯O1 or O15A⋯O12). As a result, there are only relatively weak inter­molecular contacts between chains.

The structure of 1 is similar to that of Mn₃O(OAc)₇(HOAc), which contains Mn^III centres, and adopts the same space group as Fe₃O(OAc)₇(HOAc) [Pbca, a = 15.8661 (3), b = 15.864 (3) and c = 19.5003 (5) Å] and Mn₃O(OAc)₇(HOAc) [Pbca, a = 16.07 (3), b = 19.84 (3) and c = 15.80 (2) Å] (Hessel & Romers, 1969). Despite the clear similarities in the general structure, there are some important differences associated with the high-spin d⁴ configuration of the Mn^III centre which result in Jahn–Teller tetra­gonally distorted octa­hedral coordination environments for the three Mn^III centres. For each Mn centre, there are four short bonds to O atoms that form an approximate square plane and two longer Mn—O bonds that are trans to each other. In the case of the Mn^III centre coordinated by the acetic acid mol­ecule, the two long bonds are the Mn—O(carbon­yl) bond of the acetic acid mol­ecule [2.33 (4) Å] and the Mn—μ₃-O bond [2.11 (4) Å]. For the remaining two Mn centres, the Mn—μ₃-O bonds are very short [1.85 (4) and 1.86 (4) Å], with the longer Mn—O bonds involving a pair of acetate O atoms that are trans to each other. The basicity of the oxido ligand would normally mean that it would form the shortest metal–oxygen bonds, but the poor basicity of the acetic acid ligand results in the Mn—O(carbon­yl) bond and its trans-O atom (the μ₃-oxido ligand) being the long bonds in the tetra­gonally distorted octa­hedral environment.

A remarkable contrast in the electronic effect of the poorly coordinating acetic acid mol­ecule is apparent in the schematic representation of the Fe and Mn structures presented in Fig. 3. Whereas the acetic acid mol­ecule exerts a trans influence in the Fe structure, leading to a shortening of the Fe—μ₃-O bond, the effect of the acetic acid in the Mn structure is to cause the trans Mn—μ₃-O bond to become elongated.

Figure 3 A schematic representation com­paring selected metal–oxygen bond lengths in Fe3O(OAc)7(HOAc) and Mn3O(OAc)7(HOAc).

4. Conclusion

Compound 1 provides another example of a classic basic metal carboxyl­ate structure, but unlike previous examples, the ab­sence of common coordinating solvent mol­ecules or neutral co-ligands results in the rare coordination of an acetic acid mol­ecule to an Fe^III centre. Acetate ions provide a bridge between symmetry-related units, leading to the formation of a zigzag chain. A trans influence results in a short Fe—O bond opposite the acetic acid carbonyl O atom, which contrasts with the behaviour of the structurally similar com­pound, Mn₃O(OAc)₇(HOAc), where a Jahn–Teller distortion results in the opposite effect, i.e. a lengthening of the Mn—O bond trans to the acetic acid.

Supporting information

Computing details

catena-Poly[hexa-µ-acetato-(acetic acid)-µ₃-oxido-triangulo-triiron(III)]-µ-acatato]

Crystal data

[Fe3(C2H3O2)7O(C2H4O2)]	Dx = 1.778 Mg m^−3
Mr = 656.91	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, Pbca	Cell parameters from 8086 reflections
a = 15.8661 (3) Å	θ = 4.5–71.3°
b = 15.8640 (3) Å	µ = 14.77 mm^−1
c = 19.5003 (5) Å	T = 100 K
V = 4908.22 (18) Å^3	Irregular, clear red
Z = 8	0.17 × 0.06 × 0.03 mm
F(000) = 2680

Data collection

Rigaku XtaLAB Synergy Dualflex diffractometer with a HyPix detector	5150 independent reflections
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Cu) X-ray Source	3889 reflections with I > 2σ(I)
Mirror monochromator	Rint = 0.097
Detector resolution: 10.0000 pixels mm^-1	θmax = 78.0°, θmin = 4.5°
ω scans	h = −19→19
Absorption correction: multi-scan (CrysAlis PRO; Rigaku OD, 2023)	k = −19→11
Tmin = 0.408, Tmax = 1.000	l = −24→24
38581 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.056	w = 1/[σ^2(Fo^2) + (0.0809P)^2 + 9.0225P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.156	(Δ/σ)max = 0.002
S = 1.06	Δρmax = 0.88 e Å^−3
5150 reflections	Δρmin = −0.77 e Å^−3
365 parameters	Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
33 restraints	Extinction coefficient: 0.00020 (4)
Primary atom site location: dual

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Fe2	0.87313 (4)	0.56380 (4)	0.24593 (4)	0.02289 (19)
Fe1	0.69003 (4)	0.58646 (4)	0.32908 (4)	0.02231 (19)
Fe3	0.86841 (4)	0.65690 (4)	0.39570 (4)	0.0246 (2)
O17	0.80980 (18)	0.60338 (18)	0.32468 (16)	0.0224 (6)
O7	0.6692 (2)	0.6388 (2)	0.23676 (18)	0.0292 (7)
O4	0.4361 (2)	0.5158 (2)	0.33477 (18)	0.0292 (7)
O3	0.5648 (2)	0.5676 (2)	0.33395 (18)	0.0288 (7)
O11	0.6673 (2)	0.70114 (19)	0.37278 (19)	0.0314 (8)
O13	0.9305 (2)	0.67555 (19)	0.23243 (18)	0.0298 (8)
O5	0.69210 (19)	0.47004 (19)	0.28768 (19)	0.0295 (7)
O9	0.9673 (2)	0.5171 (2)	0.30472 (18)	0.0307 (8)
O10	0.9534 (2)	0.5655 (2)	0.41216 (19)	0.0322 (8)
O8	0.7843 (2)	0.6014 (2)	0.17790 (19)	0.0352 (8)
O2	0.6976 (2)	0.5356 (2)	0.42557 (19)	0.0339 (8)
O16	0.9358 (2)	0.7203 (2)	0.47589 (18)	0.0348 (8)
O12	0.7907 (2)	0.7583 (2)	0.40255 (19)	0.0317 (8)
O1	0.8000 (2)	0.6079 (2)	0.47643 (19)	0.0344 (8)
O6	0.8212 (2)	0.4476 (2)	0.2477 (2)	0.0346 (8)
O14	0.9501 (2)	0.7225 (2)	0.33875 (18)	0.0323 (8)
C13	0.9627 (3)	0.7250 (3)	0.2750 (3)	0.0253 (9)
O15	0.8500 (3)	0.7198 (3)	0.5652 (3)	0.0495 (14)	0.850 (8)
H15	0.821447	0.688590	0.539268	0.074*	0.850 (8)
C5	0.7475 (3)	0.4246 (3)	0.2606 (3)	0.0250 (9)
C7	0.7123 (3)	0.6351 (3)	0.1831 (3)	0.0259 (10)
C9	0.9860 (3)	0.5190 (3)	0.3674 (3)	0.0293 (10)
C1	0.7361 (3)	0.5594 (3)	0.4776 (3)	0.0270 (10)
C3	0.5125 (3)	0.5120 (3)	0.3514 (3)	0.0253 (9)
C11	0.7128 (3)	0.7610 (3)	0.3938 (2)	0.0278 (10)
C6	0.7230 (3)	0.3367 (3)	0.2417 (3)	0.0320 (11)
H6A	0.682388	0.314990	0.275183	0.048*
H6B	0.773259	0.300695	0.241520	0.048*
H6C	0.697431	0.336593	0.195960	0.048*
C4	0.5384 (3)	0.4397 (3)	0.3960 (3)	0.0336 (12)
H4A	0.549084	0.460065	0.442612	0.050*
H4B	0.589895	0.414139	0.377524	0.050*
H4C	0.493312	0.397515	0.396934	0.050*
C14	1.0197 (3)	0.7930 (3)	0.2485 (3)	0.0352 (12)
H14A	1.053732	0.770803	0.210628	0.053*
H14B	1.056951	0.812081	0.285465	0.053*
H14C	0.985750	0.840483	0.232126	0.053*
C12	0.6682 (4)	0.8427 (3)	0.4106 (3)	0.0382 (12)
H12A	0.636010	0.861675	0.370641	0.057*
H12B	0.710021	0.885706	0.422859	0.057*
H12C	0.629890	0.833816	0.449360	0.057*
C8	0.6745 (4)	0.6726 (4)	0.1193 (3)	0.0397 (13)
H8A	0.657673	0.627291	0.088004	0.060*
H8B	0.716247	0.708712	0.096733	0.060*
H8C	0.624956	0.706268	0.131574	0.060*
C10	1.0550 (4)	0.4610 (3)	0.3906 (3)	0.0423 (14)
H10A	1.034602	0.402678	0.389846	0.063*
H10B	1.072022	0.475906	0.437376	0.063*
H10C	1.103467	0.466451	0.359779	0.063*
C15	0.9169 (5)	0.7483 (4)	0.5314 (4)	0.0362 (19)	0.850 (8)
C2	0.7063 (4)	0.5301 (5)	0.5458 (3)	0.0504 (16)
H2A	0.653924	0.559370	0.557694	0.076*
H2B	0.749346	0.542475	0.580460	0.076*
H2C	0.696120	0.469244	0.544262	0.076*
C16	0.9628 (6)	0.8159 (5)	0.5663 (5)	0.041 (2)	0.850 (8)
H16A	1.012794	0.831020	0.539496	0.062*	0.850 (8)
H16B	0.980186	0.796539	0.611914	0.062*	0.850 (8)
H16C	0.926183	0.865299	0.570982	0.062*	0.850 (8)
C15A	0.926 (3)	0.771 (2)	0.5208 (16)	0.038 (6)	0.150 (8)
O15A	0.8598 (19)	0.821 (2)	0.5135 (18)	0.065 (5)	0.150 (8)
H15A	0.843372	0.819542	0.472593	0.097*	0.150 (8)
C16A	0.990 (3)	0.794 (3)	0.570 (3)	0.043 (9)	0.150 (8)
H16D	0.996531	0.748040	0.603652	0.064*	0.150 (8)
H16E	0.972879	0.845437	0.594350	0.064*	0.150 (8)
H16F	1.043516	0.803482	0.546737	0.064*	0.150 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe2	0.0191 (3)	0.0204 (3)	0.0292 (4)	−0.0017 (3)	0.0015 (3)	−0.0018 (3)
Fe1	0.0189 (3)	0.0191 (3)	0.0290 (4)	0.0005 (3)	0.0002 (3)	−0.0002 (3)
Fe3	0.0220 (4)	0.0230 (4)	0.0288 (4)	−0.0008 (3)	−0.0007 (3)	−0.0013 (3)
O17	0.0196 (15)	0.0203 (14)	0.0272 (17)	0.0004 (12)	0.0008 (13)	−0.0011 (12)
O7	0.0255 (17)	0.0307 (17)	0.0315 (19)	−0.0002 (13)	−0.0009 (14)	0.0059 (14)
O4	0.0201 (16)	0.0346 (17)	0.0328 (19)	−0.0019 (13)	−0.0035 (14)	0.0079 (14)
O3	0.0226 (16)	0.0248 (15)	0.039 (2)	0.0024 (13)	−0.0004 (14)	0.0030 (14)
O11	0.0258 (17)	0.0249 (16)	0.043 (2)	−0.0016 (13)	0.0060 (15)	−0.0087 (15)
O13	0.0314 (18)	0.0217 (15)	0.036 (2)	−0.0021 (13)	0.0059 (15)	−0.0027 (13)
O5	0.0227 (16)	0.0236 (15)	0.042 (2)	−0.0023 (13)	0.0002 (15)	−0.0112 (14)
O9	0.0257 (17)	0.0348 (18)	0.0317 (19)	0.0055 (14)	0.0016 (14)	0.0003 (15)
O10	0.0289 (18)	0.0302 (17)	0.038 (2)	0.0060 (14)	−0.0074 (15)	−0.0021 (15)
O8	0.0291 (18)	0.041 (2)	0.035 (2)	0.0066 (15)	−0.0031 (15)	−0.0037 (16)
O2	0.0312 (19)	0.0387 (19)	0.0319 (19)	−0.0089 (15)	−0.0003 (15)	0.0091 (15)
O16	0.037 (2)	0.0362 (19)	0.0316 (19)	−0.0045 (15)	−0.0047 (16)	−0.0113 (16)
O12	0.0285 (18)	0.0244 (16)	0.042 (2)	0.0044 (13)	−0.0041 (15)	−0.0062 (14)
O1	0.0339 (19)	0.0403 (19)	0.0289 (18)	−0.0093 (15)	0.0007 (15)	0.0015 (15)
O6	0.0275 (18)	0.0236 (16)	0.053 (2)	−0.0048 (14)	0.0095 (16)	−0.0080 (15)
O14	0.0310 (18)	0.0332 (17)	0.0326 (19)	−0.0112 (14)	−0.0005 (15)	−0.0008 (15)
C13	0.022 (2)	0.022 (2)	0.032 (3)	0.0028 (17)	−0.0008 (19)	−0.0006 (18)
O15	0.046 (3)	0.055 (3)	0.047 (3)	−0.011 (2)	0.006 (2)	−0.009 (2)
C5	0.020 (2)	0.020 (2)	0.035 (3)	−0.0013 (17)	0.0028 (19)	0.0008 (18)
C7	0.029 (2)	0.017 (2)	0.031 (3)	0.0007 (17)	−0.004 (2)	−0.0014 (17)
C9	0.026 (2)	0.018 (2)	0.044 (3)	0.0015 (17)	0.000 (2)	0.000 (2)
C1	0.021 (2)	0.029 (2)	0.031 (3)	−0.0005 (18)	−0.003 (2)	0.0018 (19)
C3	0.020 (2)	0.025 (2)	0.031 (2)	−0.0039 (17)	−0.0010 (19)	−0.0004 (18)
C11	0.035 (3)	0.023 (2)	0.025 (2)	−0.0001 (19)	0.005 (2)	−0.0026 (18)
C6	0.028 (2)	0.021 (2)	0.047 (3)	−0.0010 (19)	−0.001 (2)	−0.004 (2)
C4	0.023 (2)	0.031 (2)	0.046 (3)	−0.0057 (19)	−0.004 (2)	0.010 (2)
C14	0.032 (3)	0.028 (2)	0.045 (3)	−0.005 (2)	−0.001 (2)	0.000 (2)
C12	0.043 (3)	0.027 (2)	0.045 (3)	0.009 (2)	0.000 (3)	−0.005 (2)
C8	0.042 (3)	0.040 (3)	0.036 (3)	0.003 (2)	−0.008 (2)	0.004 (2)
C10	0.036 (3)	0.036 (3)	0.055 (4)	0.009 (2)	−0.015 (3)	−0.004 (2)
C15	0.041 (4)	0.024 (4)	0.043 (4)	0.003 (3)	0.000 (3)	0.002 (3)
C2	0.040 (3)	0.075 (4)	0.035 (3)	−0.022 (3)	−0.005 (3)	0.019 (3)
C16	0.045 (5)	0.039 (5)	0.040 (4)	−0.008 (4)	−0.007 (4)	−0.008 (4)
C15A	0.049 (9)	0.017 (11)	0.047 (10)	−0.001 (9)	0.004 (9)	−0.001 (10)
O15A	0.057 (9)	0.069 (9)	0.068 (10)	0.003 (8)	−0.001 (9)	−0.015 (9)
C16A	0.058 (18)	0.026 (17)	0.046 (15)	0.003 (15)	−0.006 (15)	0.004 (14)

Geometric parameters (Å, º)

Fe2—O17	1.940 (3)	C5—C6	1.494 (6)
Fe2—O4^i	2.014 (3)	C7—C8	1.504 (7)
Fe2—O13	2.010 (3)	C9—C10	1.500 (7)
Fe2—O9	2.023 (3)	C1—C2	1.485 (7)
Fe2—O8	2.026 (4)	C3—C4	1.496 (7)
Fe2—O6	2.020 (3)	C11—C12	1.513 (7)
Fe1—O17	1.921 (3)	C6—H6A	0.9800
Fe1—O7	2.010 (3)	C6—H6B	0.9800
Fe1—O3	2.012 (3)	C6—H6C	0.9800
Fe1—O11	2.041 (3)	C4—H4A	0.9800
Fe1—O5	2.016 (3)	C4—H4B	0.9800
Fe1—O2	2.051 (4)	C4—H4C	0.9800
Fe3—O17	1.872 (3)	C14—H14A	0.9800
Fe3—O10	2.006 (3)	C14—H14B	0.9800
Fe3—O16	2.144 (3)	C14—H14C	0.9800
Fe3—O12	2.030 (3)	C12—H12A	0.9800
Fe3—O1	2.064 (4)	C12—H12B	0.9800
Fe3—O14	1.999 (3)	C12—H12C	0.9800
O7—C7	1.252 (6)	C8—H8A	0.9800
O4—C3	1.256 (6)	C8—H8B	0.9800
O3—C3	1.258 (5)	C8—H8C	0.9800
O11—C11	1.261 (6)	C10—H10A	0.9800
O13—C13	1.250 (6)	C10—H10B	0.9800
O5—C5	1.253 (5)	C10—H10C	0.9800
O9—C9	1.259 (6)	C15—C16	1.464 (9)
O10—C9	1.254 (6)	C2—H2A	0.9800
O8—C7	1.265 (6)	C2—H2B	0.9800
O2—C1	1.243 (6)	C2—H2C	0.9800
O16—C15	1.207 (7)	C16—H16A	0.9800
O16—C15A	1.201 (12)	C16—H16B	0.9800
O12—C11	1.250 (6)	C16—H16C	0.9800
O1—C1	1.272 (6)	C15A—O15A	1.320 (19)
O6—C5	1.252 (5)	C15A—C16A	1.45 (2)
O14—C13	1.261 (6)	O15A—H15A	0.8400
C13—C14	1.500 (7)	C16A—H16D	0.9800
O15—H15	0.8400	C16A—H16E	0.9800
O15—C15	1.329 (8)	C16A—H16F	0.9800
O17—Fe2—O4^i	176.57 (13)	O9—C9—C10	116.8 (5)
O17—Fe2—O13	93.02 (13)	O10—C9—O9	126.3 (4)
O17—Fe2—O9	93.01 (13)	O10—C9—C10	116.9 (5)
O17—Fe2—O8	93.58 (14)	O2—C1—O1	124.0 (5)
O17—Fe2—O6	94.07 (14)	O2—C1—C2	118.7 (4)
O4^i—Fe2—O9	86.44 (14)	O1—C1—C2	117.3 (5)
O4^i—Fe2—O8	86.85 (14)	O4—C3—O3	122.2 (4)
O4^i—Fe2—O6	82.53 (14)	O4—C3—C4	116.9 (4)
O13—Fe2—O4^i	90.39 (14)	O3—C3—C4	120.9 (4)
O13—Fe2—O9	93.62 (14)	O11—C11—C12	116.7 (5)
O13—Fe2—O8	88.24 (15)	O12—C11—O11	125.8 (4)
O13—Fe2—O6	172.74 (15)	O12—C11—C12	117.5 (4)
O9—Fe2—O8	173.05 (15)	C5—C6—H6A	109.5
O6—Fe2—O9	87.54 (15)	C5—C6—H6B	109.5
O6—Fe2—O8	89.79 (15)	C5—C6—H6C	109.5
O17—Fe1—O7	93.73 (14)	H6A—C6—H6B	109.5
O17—Fe1—O3	179.44 (13)	H6A—C6—H6C	109.5
O17—Fe1—O11	93.97 (13)	H6B—C6—H6C	109.5
O17—Fe1—O5	95.39 (13)	C3—C4—H4A	109.5
O17—Fe1—O2	92.17 (13)	C3—C4—H4B	109.5
O7—Fe1—O3	86.63 (14)	C3—C4—H4C	109.5
O7—Fe1—O11	88.66 (15)	H4A—C4—H4B	109.5
O7—Fe1—O5	91.29 (14)	H4A—C4—H4C	109.5
O7—Fe1—O2	173.71 (14)	H4B—C4—H4C	109.5
O3—Fe1—O11	86.47 (13)	C13—C14—H14A	109.5
O3—Fe1—O5	84.17 (13)	C13—C14—H14B	109.5
O3—Fe1—O2	87.49 (14)	C13—C14—H14C	109.5
O11—Fe1—O2	88.75 (15)	H14A—C14—H14B	109.5
O5—Fe1—O11	170.63 (13)	H14A—C14—H14C	109.5
O5—Fe1—O2	90.34 (15)	H14B—C14—H14C	109.5
O17—Fe3—O10	97.15 (14)	C11—C12—H12A	109.5
O17—Fe3—O16	178.92 (14)	C11—C12—H12B	109.5
O17—Fe3—O12	96.11 (14)	C11—C12—H12C	109.5
O17—Fe3—O1	97.59 (14)	H12A—C12—H12B	109.5
O17—Fe3—O14	98.45 (14)	H12A—C12—H12C	109.5
O10—Fe3—O16	83.53 (14)	H12B—C12—H12C	109.5
O10—Fe3—O12	165.93 (15)	C7—C8—H8A	109.5
O10—Fe3—O1	87.65 (15)	C7—C8—H8B	109.5
O12—Fe3—O16	83.28 (14)	C7—C8—H8C	109.5
O12—Fe3—O1	85.95 (15)	H8A—C8—H8B	109.5
O1—Fe3—O16	83.27 (14)	H8A—C8—H8C	109.5
O14—Fe3—O10	91.69 (15)	H8B—C8—H8C	109.5
O14—Fe3—O16	80.68 (14)	C9—C10—H10A	109.5
O14—Fe3—O12	91.01 (15)	C9—C10—H10B	109.5
O14—Fe3—O1	163.90 (14)	C9—C10—H10C	109.5
Fe1—O17—Fe2	120.18 (16)	H10A—C10—H10B	109.5
Fe3—O17—Fe2	118.37 (15)	H10A—C10—H10C	109.5
Fe3—O17—Fe1	121.44 (16)	H10B—C10—H10C	109.5
C7—O7—Fe1	129.8 (3)	O16—C15—O15	121.1 (6)
C3—O4—Fe2^ii	134.3 (3)	O16—C15—C16	124.3 (7)
C3—O3—Fe1	140.3 (3)	O15—C15—C16	114.6 (6)
C11—O11—Fe1	134.9 (3)	C1—C2—H2A	109.5
C13—O13—Fe2	130.6 (3)	C1—C2—H2B	109.5
C5—O5—Fe1	135.0 (3)	C1—C2—H2C	109.5
C9—O9—Fe2	135.7 (3)	H2A—C2—H2B	109.5
C9—O10—Fe3	126.2 (3)	H2A—C2—H2C	109.5
C7—O8—Fe2	134.5 (3)	H2B—C2—H2C	109.5
C1—O2—Fe1	131.2 (3)	C15—C16—H16A	109.5
C15—O16—Fe3	134.6 (4)	C15—C16—H16B	109.5
C15A—O16—Fe3	141.4 (18)	C15—C16—H16C	109.5
C11—O12—Fe3	128.3 (3)	H16A—C16—H16B	109.5
C1—O1—Fe3	131.3 (3)	H16A—C16—H16C	109.5
C5—O6—Fe2	130.6 (3)	H16B—C16—H16C	109.5
C13—O14—Fe3	131.9 (3)	O16—C15A—O15A	115 (3)
O13—C13—O14	124.8 (4)	O16—C15A—C16A	124 (3)
O13—C13—C14	118.0 (5)	O15A—C15A—C16A	119 (2)
O14—C13—C14	117.2 (4)	C15A—O15A—H15A	109.5
C15—O15—H15	109.5	C15A—C16A—H16D	109.5
O5—C5—C6	117.4 (4)	C15A—C16A—H16E	109.5
O6—C5—O5	125.0 (4)	C15A—C16A—H16F	109.5
O6—C5—C6	117.7 (4)	H16D—C16A—H16E	109.5
O7—C7—O8	125.5 (5)	H16D—C16A—H16F	109.5
O7—C7—C8	117.1 (4)	H16E—C16A—H16F	109.5
O8—C7—C8	117.4 (5)
Fe2^ii—O4—C3—O3	30.4 (7)	Fe3—O10—C9—O9	−5.2 (7)
Fe2^ii—O4—C3—C4	−152.1 (4)	Fe3—O10—C9—C10	173.7 (3)
Fe2—O13—C13—O14	−15.8 (7)	Fe3—O16—C15—O15	23.5 (11)
Fe2—O13—C13—C14	164.9 (3)	Fe3—O16—C15—C16	−155.5 (6)
Fe2—O9—C9—O10	−12.1 (8)	Fe3—O16—C15A—O15A	−21 (7)
Fe2—O9—C9—C10	168.9 (4)	Fe3—O16—C15A—C16A	175 (3)
Fe2—O8—C7—O7	−15.6 (7)	Fe3—O12—C11—O11	−6.6 (8)
Fe2—O8—C7—C8	165.4 (4)	Fe3—O12—C11—C12	172.5 (4)
Fe2—O6—C5—O5	−13.5 (8)	Fe3—O1—C1—O2	−5.0 (7)
Fe2—O6—C5—C6	165.7 (4)	Fe3—O1—C1—C2	175.0 (4)
Fe1—O7—C7—O8	−6.2 (7)	Fe3—O14—C13—O13	−9.6 (7)
Fe1—O7—C7—C8	172.7 (3)	Fe3—O14—C13—C14	169.7 (3)
Fe1—O3—C3—O4	−165.5 (4)	O10—Fe3—O17—Fe2	−53.88 (19)
Fe1—O3—C3—C4	17.1 (8)	O10—Fe3—O17—Fe1	125.52 (19)
Fe1—O11—C11—O12	−12.3 (8)	O12—Fe3—O17—Fe2	130.85 (18)
Fe1—O11—C11—C12	168.5 (4)	O12—Fe3—O17—Fe1	−49.8 (2)
Fe1—O5—C5—O6	−6.2 (8)	O1—Fe3—O17—Fe2	−142.44 (17)
Fe1—O5—C5—C6	174.6 (4)	O1—Fe3—O17—Fe1	37.0 (2)
Fe1—O2—C1—O1	−22.6 (7)	O14—Fe3—O17—Fe2	38.91 (19)
Fe1—O2—C1—C2	157.4 (4)	O14—Fe3—O17—Fe1	−141.69 (18)

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