Crystal structure of bis­[4-(1H-pyrrol-1-yl)phen­yl] ferrocene-1,1′-di­carboxyl­ate: a potential chemotherapeutic drug

Prez, W.I.; Rheingold, A.L.; Meléndez, E.

doi:10.1107/S2056989015007446

research communications

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ISSN: 2056-9890

Volume 71| Part 5| May 2015| Pages 536-539

https://doi.org/10.1107/S2056989015007446

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Crystal structure of bis[4-(1H-pyrrol-1-yl)phenyl] ferrocene-1,1′-dicarboxylate: a potential chemotherapeutic drug

Wanda I. Pérez,^a Arnold L. Rheingold ^b and Enrique Meléndez ^a ^*

^aUniversity of Puerto Rico, Department of Chemistry, PO Box 9019, Mayaguez, Puerto Rico 00681, USA, and ^bUniversity of California-San Diego, Department of Chemistry, Urey Hall 5128, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA
^*Correspondence e-mail: enrique.melendez@upr.edu

Edited by R. F. Baggio, Comisión Nacional de Energía Atómica, Argentina (Received 2 April 2015; accepted 15 April 2015; online 22 April 2015)

The title iron(II) complex, [Fe(C₁₆H₁₂NO₂)₂], crystallizes in the orthorhombic space group Pbca with the Fe²⁺ cation positioned on an inversion center. The cyclopentadienyl (Cp) rings adopt an anti conformation in contrast with other substituted ferrocenes in which the Cp rings appear in a nearly eclipsed conformation. The Cp and the aromatic rings are positioned out of the plane, with a twist angle of 70.20 (12)°, and the C(Cp)—C(CO) bond length is shorter than a typical C—C single bond, which suggests a partial double-bond character and delocalization with the Cp π system. The structure of the complex is compared to other functionalized ferrocenes synthesized in our laboratory.

Keywords: crystal structure; disubstituted ferrocene; antiproliferative; chemotherapeutic drug; MCF-7; pyrrole.

CCDC reference: 1054149

1. Chemical context

The gold standard of treatment for breast cancer has traditionally been cisplatin, a metal-based agent. Its administration, alone or in combination with other drugs, is also highly effective against various other types of cancers, including ovarian, head and neck, bladder, testicular and lung cancers (Galanski et al., 2005 ; Sandler et al., 2011 ). However, its clinical use suffers from major drawbacks, such as severe toxic side effects including neurotoxicity, hepatotoxicity, and nephrotoxicity (Pabla & Dong, 2008 ), as well as a drug-resistance phenomenon which leads to unsuccessful treatment (Dempke et al., 2000 ). Consequently, other metal-based drugs have been investigated, among them ferrocenes (Köpf-Maier et al., 1984 ). Ferrocene has the versatility of easy functionalization providing a fertile field for structural modification and to study structure–activity relationship (SAR).

Our group has been working in this field for many years, leading to exciting and biologically active ferrocenes. A wide variety of pendant (functional) groups have been attached or linked to the Cp ring to tailor the anti-proliferative properties of ferrocene, many of them with great success (Braga & Silva, 2013 ; Gasser et al., 2011 ; Jaouen & Metzler-Nolte, 2010 ; Fouda et al., 2007 ; Jaouen, 2006 ; van Staveren & Metzler-Nolte, 2004 ; Nguyen et al., 2009 ; Top et al., 2003 ; Vessières et al., 2005 , 2006 ; Meléndez, 2012 ; Vera et al., 2011 , 2014 ). Lately, a new range of organic chemotherapeutic compounds have been studied using pyrrole derivatives. These pyrrole derivatives have revealed good anti-proliferative activity and an increase in membrane permeability, allowing the compounds to reach the nucleus (Ghorab et al., 2014 ; Abou El Ella et al., 2008 ; Chatzopoulou et al., 2014 ; Mohamed et al., 2013 ; Hassan et al., 2009 ; Esteves et al., 2010 ; Clark et al., 2007 ; Merighi et al., 2003 ). Therefore, we functionalized ferrocene with a pyrrole, 4-(1H-pyrrol-1-yl)phenol, obtaining three new ferrocenes: 1,1′-4-(1H-pyrrol-1-yl)phenyl ferrocenedicarboxylate, 1,4-(1H-pyrrol-1-yl)phenyl, 1′-carboxyl ferrocenecarboxylate (Fc-(CO₂-Ph-4-Py)CO₂H) and 4-(1H-pyrrol-1-yl)phenyl ferroceneacetylate (Fc-CH₂CO₂-Ph-4-Py). We investigated their biological activities on breast cancer cell line (MCF-7) and among these ferrocenes, 1,1′-4-(1H-pyrrol-1-yl)phenyl ferrocenedicarboxylate (I) was shown to be most active in this series (Pérez et al., 2015 ). Nevertheless, the solid-state structure of (I) has been elusive (Pérez et al., 2015). The importance of this complex is the incorporation of pyrrole groups, which are derivatives of biologically active compounds, as well as pyrrole being an electrochemically active group precursor of polymeric material. In addition, ferrocene anticancer activity has been associated with its redox behavior and the capability to produce reactive oxygen species (ROS) (Acevedo et al., 2012 ; Kovjazin et al., 2003 ; Tabbi et al., 2002 ; Osella et al., 2005 ). Thus, the attachment of an electrochemically active group on ferrocene could potentiate the production of ROS and enhance its anticancer activity.

Given that the solid-state structure of this complex is not available, we determined the crystal structure of bis[4-(1H-pyrrol-1-yl)phenyl] ferrocene-1,1′-dicarboxylate, (I). Additionally, we compared the obtained crystal structure with other functionalized ferrocenes synthesized in our laboratory viz.: 4-bromophenyl (II) and 4-chlorophenyl ferrocenecarboxylate (III) (Vera et al., 2014), and 1,1′-methyl ferrocenedicarboxylate (IV) (Gao et al., 2009 ).

2. Structural commentary

The asymmetric unit contains one half-molecule since Fe²⁺ lies on an inversion center, Fig. 1. This symmetry is implied by the NMR data where only one set of signals were found for H2/H5 and H3/H4 of the Cp rings, as well as the H2/H6 and H3/H5 of the phenyl and H2/H5 and H3/H4 of the pyrrole groups. Consequently, the Cp rings adopt a perfect anti conformation. The average Fe—C(Cp) bond length is 2.044 (10) Å, which is very similar to that reported for ferrocene (Dunitz et al., 1956 ) and other structures previously reported by our lab (Vera et al., 2014; Gao et al., 2009). The Fe—C bond length of the substituted carbon [Fe—C1 2.032 (2) Å] is shorter that the remaining Fe—C bond lengths due to the inductive effect of the carboxylate on the Cp ring. The twist angles between the Cp ring and the carboxylate and the Cp ring and the aromatic ring are 14.4 (3)° (above the Cp plane) and 70.20 (12)°, respectively.

Figure 1
The molecular structure of (I)

, with displacement ellipsoids drawn at the 30% probability level. Unlabelled atoms are related to labelled ones by the symmetry operation −x, −y, −z.

To put it in perspective, we compare (I) with previously synthesized ferrocenes in our group containing only one Cp functionalized and a phenyl group attached to the carboxylate, but with Br and Cl instead of pyrrole in the 4-position, (II) and (III) (CCDC 949002 and 949003, Vera et al., 2014). First, in the 4-bromophenyl and 4-chlorophenyl derivatives, the Cp rings are positioned in a nearly eclipsed conformation and parallel with stagger angles < 3° and Cp tilt angles of 0.48–1.25°. In contrast, (I) has a perfect anti conformation. The carbonyl carbon of (I) has a distorted trigonal–planar geometry, analogous to the 4-chlorophenyl and 4-bromophenyl ferrocenecarboxylates. The twist angles between the Cp ring and the carboxylate for 4-bromo and 4-chlorophenyl ferrocenecarboxylates (6.75–10.15°) are smaller than that of the subject complex, 14.4 (3)°. Additionally, as mentioned previously, the carbonyl oxygen of (I) lies above the Cp plane whereas for the bromo and chloro derivatives, the carbonyl oxygens lie below the Cp plane. The twist angle between the Cp and the aromatic ring is 70.20 (12)° in (I), while in (II) and (III) the two rings are positioned at higher angles, approaching a perpendicular position.

The average Fe—C(Cp*) bond lengths of the substituted Cp rings in the 4-bromo and 4-chlorophenyl derivatives are identical, within experimental error, as in (I) [2.044 (13) Å]. As mentioned before, the Fe—C bond length where the pendant group is attached is substantially shorter than the remaining Fe—C(Cp) distances. The same bonding pattern is also observed for the 4-bromo and 4-chlorophenyl ferrocenecarboxylates. The C(Cp)—C(CO) bond length in (I), C1—C6, is shorter than a typical C—C single bond, [1.473 (3) versus 1.54 Å (single bond); Pauling, 1960 ]. This suggests partial double-bond character and delocalization with the Cp π system in analogous manner to that for the 4-bromo and 4-chloro derivatives.

In the structure of the disubstituted ferrocene Fe(C₅H₄CO₂CH₃)₂, (IV) (Gao et al., 2009), the average Fe—C(Cp) bond lengths are 2.048 (11)/2.049 (14) Å, similar to the title complex but the Cp rings adopt almost an eclipsed conformation with a stagger angle of 2.37° (Fig. 2). In addition, the functional groups are not positioned perfectly anti to each other. The Fe—C(Cp)—C(CO) bond in (IV) [1.477 (4) Å] is notably shorter than a typical C—C single bond (1.54 Å), in a similar manner to the title complex, suggesting delocalization with the Cp π system.

Figure 2
A Newman projection of Fe(C₅H₄CO₂CH₃)₂.

Finally, (I) contains two π ring systems, 4-(1H-pyrrol-1-yl)phenyl, which in principle could be involved in intramolecular π–π or C—H⋯π stacking similar to other 1,1′-disubstituted ferrocenes with an extended π ring system (Okabe et al., 2009 ; Togni et al., 1994 ; Gelin & Thummel, 1992 ). However, such π–π or C—H⋯π stacking is not observed in (I) since the Cp rings adopt an anti conformation.

3. Synthesis and crystallization

The synthesis of (I) was accomplished by treating 1,1′-ferrocenedicarboxylic acid with oxalyl chloride according to our recently published procedure (Pérez et al., 2015). ¹H NMR (500 MHz, CDCl₃) (δ p.p.m.): 7.37 (2H, d, ph; ³J = 8.8 Hz), 7.25 (2H, d, py; ³J = 2.8 Hz), 7.03 (2H, dd, ph; ³J = 1.3 Hz), 6.34 (2H, dd, py; ³J = 1.6 Hz), 5.08 (2H, overlapping doublets, AA′, Cp), 4.64 (2H, overlapping doublets, BB′, Cp). ¹³CNMR (125 MHz, CDCl₃) (δ p.p.m.): 169.0 (C=O), 148.3, 138.6, 122.9, 121.5, 119.5, 110.5, 73.4, 72.4, 72.0. Analysis calculated for C₃₂H₂₄O₄FeN₂: C, 69.05; H, 4.40; found: C, 68.62; H, 4.46.

Crystallization of (I) was performed inside an NMR tube containing CD₂Cl₂ for a period of two weeks, obtaining block-shaped orange crystals suitable for X-ray diffraction.

4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms were positioned in idealized locations (C₍₆₎—H = 0.95, C₍₅₎—H = 1.00 Å with U_iso(H) = 1.2U_eq(C).

Table 1
Experimental details

Crystal data
Chemical formula	[Fe(C₁₆H₁₂NO₂)₂]
M_r	556.38
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	100
a, b, c (Å)	10.6386 (15), 7.3948 (10), 30.554 (4)
V (Å³)	2403.7 (6)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.67
Crystal size (mm)	0.28 × 0.26 × 0.23

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2010 )
T_min, T_max	0.833, 0.877
No. of measured, independent and observed [I > 2σ(I)] reflections	12444, 2999, 2247
R_int	0.077
(sin θ/λ)_max (Å⁻¹)	0.669

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.117, 1.02
No. of reflections	2999
No. of parameters	178
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.34, −0.62
Computer programs: APEX2 and SAINT (Bruker, 2010), SHELXS97 and SHELXTL (Sheldrick, 2008 ) and SHELXL2013 (Sheldrick, 2015 ).

Supporting information

CCDC reference: 1054149

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989015007446/bg2552sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989015007446/bg2552Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2010); data reduction: SAINT (Bruker, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Bis[4-(1H-pyrrol-1-yl)phenyl] ferrocene-1,1'-dicarboxylate top

Crystal data top

[Fe(C₁₆H₁₂NO₂)₂]	D_x = 1.537 Mg m⁻³
M_r = 556.38	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 2807 reflections
a = 10.6386 (15) Å	θ = 2.7–28.1°
b = 7.3948 (10) Å	µ = 0.67 mm⁻¹
c = 30.554 (4) Å	T = 100 K
V = 2403.7 (6) Å³	Block, orange
Z = 4	0.28 × 0.26 × 0.23 mm
F(000) = 1152

Data collection top

Bruker APEXII CCD diffractometer	2247 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.077
Absorption correction: multi-scan (SADABS; Bruker, 2010)	θ_max = 28.4°, θ_min = 2.7°
T_min = 0.833, T_max = 0.877	h = −13→14
12444 measured reflections	k = −9→9
2999 independent reflections	l = −37→40

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.044	H-atom parameters constrained
wR(F²) = 0.117	w = 1/[σ²(F_o²) + (0.047P)² + 0.928P] where P = (F_o² + 2F_c²)/3
S = 1.02	(Δ/σ)_max < 0.001
2999 reflections	Δρ_max = 0.34 e Å⁻³
178 parameters	Δρ_min = −0.62 e Å⁻³

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Fe1	0.5000	0.5000	0.5000	0.01323 (14)
O1	0.23108 (15)	0.4748 (2)	0.41347 (5)	0.0213 (4)
O2	0.41465 (13)	0.3430 (2)	0.39352 (4)	0.0173 (3)
N1	0.37269 (16)	0.3889 (2)	0.21120 (5)	0.0133 (4)
C1	0.3680 (2)	0.3523 (3)	0.46783 (7)	0.0149 (4)
C2	0.3145 (2)	0.4294 (3)	0.50667 (6)	0.0169 (4)
H2A	0.2415	0.5142	0.5081	0.020*
C3	0.3857 (2)	0.3643 (3)	0.54286 (7)	0.0216 (5)
H3A	0.3716	0.3970	0.5742	0.026*
C4	0.4812 (2)	0.2469 (3)	0.52692 (7)	0.0191 (5)
H4A	0.5454	0.1827	0.5451	0.023*
C5	0.4712 (2)	0.2403 (3)	0.48035 (7)	0.0166 (4)
H5A	0.5262	0.1693	0.4601	0.020*
C6	0.3264 (2)	0.3975 (3)	0.42318 (6)	0.0144 (4)
C7	0.3923 (2)	0.3684 (3)	0.34853 (6)	0.0145 (4)
C8	0.48316 (19)	0.4601 (3)	0.32540 (7)	0.0155 (4)
H8A	0.5502	0.5182	0.3404	0.019*
C9	0.47630 (19)	0.4673 (3)	0.27993 (7)	0.0151 (4)
H9A	0.5398	0.5288	0.2639	0.018*
C10	0.37736 (19)	0.3853 (2)	0.25769 (6)	0.0121 (4)
C11	0.28353 (19)	0.2994 (3)	0.28206 (7)	0.0149 (4)
H11A	0.2137	0.2469	0.2674	0.018*
C12	0.29095 (19)	0.2899 (3)	0.32731 (6)	0.0154 (4)
H12A	0.2272	0.2302	0.3436	0.018*
C13	0.2795 (2)	0.3154 (3)	0.18518 (7)	0.0174 (4)
H13A	0.2077	0.2518	0.1954	0.021*
C14	0.3076 (2)	0.3494 (3)	0.14240 (7)	0.0195 (5)
H14A	0.2587	0.3153	0.1177	0.023*
C15	0.4232 (2)	0.4449 (3)	0.14143 (7)	0.0213 (5)
H15A	0.4661	0.4862	0.1161	0.026*
C16	0.4613 (2)	0.4663 (3)	0.18374 (7)	0.0184 (4)
H16A	0.5364	0.5248	0.1929	0.022*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Fe1	0.0159 (2)	0.0111 (2)	0.0127 (2)	−0.00228 (16)	−0.00142 (16)	0.00108 (15)
O1	0.0196 (9)	0.0274 (8)	0.0169 (8)	0.0076 (7)	−0.0004 (6)	−0.0006 (6)
O2	0.0162 (8)	0.0220 (8)	0.0137 (7)	0.0029 (6)	−0.0003 (6)	−0.0013 (6)
N1	0.0123 (8)	0.0123 (8)	0.0154 (8)	−0.0003 (7)	0.0015 (7)	−0.0003 (6)
C1	0.0164 (10)	0.0125 (9)	0.0160 (10)	−0.0039 (8)	0.0003 (8)	−0.0003 (7)
C2	0.0161 (10)	0.0168 (10)	0.0179 (10)	−0.0040 (9)	0.0031 (8)	0.0006 (8)
C3	0.0292 (12)	0.0190 (11)	0.0165 (11)	−0.0081 (10)	0.0015 (9)	0.0016 (8)
C4	0.0232 (12)	0.0139 (10)	0.0201 (11)	−0.0055 (9)	−0.0051 (9)	0.0046 (8)
C5	0.0197 (11)	0.0105 (9)	0.0197 (11)	−0.0009 (9)	−0.0040 (9)	0.0007 (8)
C6	0.0149 (10)	0.0121 (9)	0.0162 (10)	−0.0015 (8)	0.0004 (8)	−0.0014 (7)
C7	0.0157 (10)	0.0137 (9)	0.0142 (10)	0.0024 (8)	−0.0008 (8)	−0.0014 (7)
C8	0.0135 (10)	0.0150 (10)	0.0180 (10)	−0.0025 (8)	−0.0008 (8)	−0.0027 (8)
C9	0.0127 (10)	0.0135 (9)	0.0192 (10)	−0.0006 (8)	0.0023 (8)	0.0003 (8)
C10	0.0127 (10)	0.0085 (9)	0.0151 (10)	0.0031 (8)	0.0003 (8)	−0.0006 (7)
C11	0.0118 (10)	0.0136 (9)	0.0193 (10)	−0.0027 (8)	−0.0012 (8)	0.0004 (8)
C12	0.0150 (10)	0.0138 (9)	0.0173 (10)	−0.0010 (8)	0.0023 (8)	0.0018 (8)
C13	0.0139 (10)	0.0163 (10)	0.0219 (11)	−0.0002 (9)	−0.0005 (8)	−0.0016 (8)
C14	0.0211 (11)	0.0196 (11)	0.0177 (10)	0.0066 (9)	−0.0016 (9)	−0.0022 (8)
C15	0.0250 (13)	0.0211 (11)	0.0179 (11)	0.0031 (10)	0.0048 (9)	0.0015 (9)
C16	0.0161 (10)	0.0176 (10)	0.0217 (11)	−0.0032 (9)	0.0035 (9)	0.0024 (8)

Geometric parameters (Å, º) top

Fe1—C1	2.032 (2)	C3—H3A	1.0000
Fe1—C1ⁱ	2.033 (2)	C4—C5	1.428 (3)
Fe1—C5	2.035 (2)	C4—H4A	1.0000
Fe1—C5ⁱ	2.035 (2)	C5—H5A	1.0000
Fe1—C3ⁱ	2.050 (2)	C7—C8	1.376 (3)
Fe1—C3	2.050 (2)	C7—C12	1.386 (3)
Fe1—C2	2.051 (2)	C8—C9	1.392 (3)
Fe1—C2ⁱ	2.051 (2)	C8—H8A	0.9500
Fe1—C4ⁱ	2.055 (2)	C9—C10	1.392 (3)
Fe1—C4	2.055 (2)	C9—H9A	0.9500
O1—C6	1.201 (3)	C10—C11	1.398 (3)
O2—C6	1.366 (2)	C11—C12	1.387 (3)
O2—C7	1.407 (2)	C11—H11A	0.9500
N1—C13	1.382 (3)	C12—H12A	0.9500
N1—C16	1.386 (3)	C13—C14	1.364 (3)
N1—C10	1.422 (3)	C13—H13A	0.9500
C1—C5	1.427 (3)	C14—C15	1.418 (3)
C1—C2	1.434 (3)	C14—H14A	0.9500
C1—C6	1.473 (3)	C15—C16	1.364 (3)
C2—C3	1.424 (3)	C15—H15A	0.9500
C2—H2A	1.0000	C16—H16A	0.9500
C3—C4	1.423 (3)

C1—Fe1—C1ⁱ	180.0	C3—C2—Fe1	69.63 (13)
C1—Fe1—C5	41.09 (8)	C1—C2—Fe1	68.75 (12)
C1ⁱ—Fe1—C5	138.91 (8)	C3—C2—H2A	126.3
C1—Fe1—C5ⁱ	138.91 (8)	C1—C2—H2A	126.3
C1ⁱ—Fe1—C5ⁱ	41.09 (8)	Fe1—C2—H2A	126.3
C5—Fe1—C5ⁱ	180.0	C4—C3—C2	108.66 (19)
C1—Fe1—C3ⁱ	111.35 (8)	C4—C3—Fe1	69.90 (12)
C1ⁱ—Fe1—C3ⁱ	68.66 (8)	C2—C3—Fe1	69.74 (12)
C5—Fe1—C3ⁱ	111.27 (9)	C4—C3—H3A	125.7
C5ⁱ—Fe1—C3ⁱ	68.73 (9)	C2—C3—H3A	125.7
C1—Fe1—C3	68.65 (8)	Fe1—C3—H3A	125.7
C1ⁱ—Fe1—C3	111.34 (8)	C3—C4—C5	107.97 (18)
C5—Fe1—C3	68.73 (9)	C3—C4—Fe1	69.54 (12)
C5ⁱ—Fe1—C3	111.27 (9)	C5—C4—Fe1	68.84 (11)
C3ⁱ—Fe1—C3	180.0	C3—C4—H4A	126.0
C1—Fe1—C2	41.11 (8)	C5—C4—H4A	126.0
C1ⁱ—Fe1—C2	138.89 (8)	Fe1—C4—H4A	126.0
C5—Fe1—C2	69.15 (9)	C1—C5—C4	107.75 (18)
C5ⁱ—Fe1—C2	110.85 (9)	C1—C5—Fe1	69.36 (11)
C3ⁱ—Fe1—C2	139.37 (9)	C4—C5—Fe1	70.30 (11)
C3—Fe1—C2	40.63 (9)	C1—C5—H5A	126.1
C1—Fe1—C2ⁱ	138.89 (8)	C4—C5—H5A	126.1
C1ⁱ—Fe1—C2ⁱ	41.11 (8)	Fe1—C5—H5A	126.1
C5—Fe1—C2ⁱ	110.85 (9)	O1—C6—O2	123.84 (18)
C5ⁱ—Fe1—C2ⁱ	69.15 (9)	O1—C6—C1	126.17 (19)
C3ⁱ—Fe1—C2ⁱ	40.63 (9)	O2—C6—C1	109.97 (18)
C3—Fe1—C2ⁱ	139.37 (9)	C8—C7—C12	120.85 (19)
C2—Fe1—C2ⁱ	180.0	C8—C7—O2	116.66 (18)
C1—Fe1—C4ⁱ	111.29 (8)	C12—C7—O2	122.16 (18)
C1ⁱ—Fe1—C4ⁱ	68.71 (8)	C7—C8—C9	119.63 (19)
C5—Fe1—C4ⁱ	139.13 (9)	C7—C8—H8A	120.2
C5ⁱ—Fe1—C4ⁱ	40.87 (9)	C9—C8—H8A	120.2
C3ⁱ—Fe1—C4ⁱ	40.56 (9)	C10—C9—C8	120.67 (19)
C3—Fe1—C4ⁱ	139.44 (9)	C10—C9—H9A	119.7
C2—Fe1—C4ⁱ	111.44 (9)	C8—C9—H9A	119.7
C2ⁱ—Fe1—C4ⁱ	68.56 (9)	C9—C10—C11	118.55 (18)
C1—Fe1—C4	68.71 (8)	C9—C10—N1	120.40 (18)
C1ⁱ—Fe1—C4	111.29 (8)	C11—C10—N1	121.05 (17)
C5—Fe1—C4	40.87 (9)	C12—C11—C10	120.90 (19)
C5ⁱ—Fe1—C4	139.13 (9)	C12—C11—H11A	119.5
C3ⁱ—Fe1—C4	139.44 (9)	C10—C11—H11A	119.5
C3—Fe1—C4	40.56 (9)	C7—C12—C11	119.31 (19)
C2—Fe1—C4	68.56 (9)	C7—C12—H12A	120.3
C2ⁱ—Fe1—C4	111.44 (9)	C11—C12—H12A	120.3
C4ⁱ—Fe1—C4	180.00 (11)	C14—C13—N1	108.78 (19)
C6—O2—C7	119.52 (16)	C14—C13—H13A	125.6
C13—N1—C16	107.58 (17)	N1—C13—H13A	125.6
C13—N1—C10	126.34 (17)	C13—C14—C15	107.54 (19)
C16—N1—C10	126.08 (18)	C13—C14—H14A	126.2
C5—C1—C2	108.28 (18)	C15—C14—H14A	126.2
C5—C1—C6	127.65 (19)	C16—C15—C14	107.2 (2)
C2—C1—C6	123.89 (19)	C16—C15—H15A	126.4
C5—C1—Fe1	69.56 (12)	C14—C15—H15A	126.4
C2—C1—Fe1	70.14 (12)	C15—C16—N1	108.9 (2)
C6—C1—Fe1	122.25 (14)	C15—C16—H16A	125.6
C3—C2—C1	107.3 (2)	N1—C16—H16A	125.6

Symmetry code: (i) −x+1, −y+1, −z+1.

Acknowledgements

EM is thankful for the financial support of NIH-RISE 2 Best program (NIH-R25GM088023) for the research assistantship of WIP (graduate student).

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