Crystal structure of 1-ferrocenyl-2-(4-nitro­phen­yl)ethyne

Delgado Rivera, S.M.; González Espiet, J.C.; Dones, J.M.; Henríquez López, S.A.; Guadalupe, A.R.; Piñero Cruz, D.M.; Montes González, I.

doi:10.1107/S2056989020010336

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ISSN: 2056-9890

Volume 76| Part 8| August 2020| Pages 1403-1406

https://doi.org/10.1107/S2056989020010336

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Crystal structure of 1-ferrocenyl-2-(4-nitrophenyl)ethyne

Sara M. Delgado Rivera,^a Jean C. González Espiet,^b Jesús M. Dones,^a Sebastián A. Henríquez López,^a Ana R. Guadalupe,^a Dalice M. Piñero Cruz ^b and Ingrid Montes González ^a ^*

^aDepartment of Chemistry, University of Puerto Rico at Río Piedras, PO Box 23346, San Juan, PR 00931-3346, Puerto Rico, and ^bDepartment of Chemistry and the Molecular Sciences Research Center, University of Puerto Rico-Rio Piedras Campus, PO Box 23346, San Juan, 00931-3346, Puerto Rico
^*Correspondence e-mail: ingrid.montes2@upr.edu

Edited by G. Diaz de Delgado, Universidad de Los Andes, Venezuela (Received 23 March 2020; accepted 24 July 2020; online 31 July 2020)

The title ferrocene derivative, [Fe(C₅H₅)₂(C₈NO₂)], including an alkyne bonded to a para-nitrophenyl substituent, which was synthesized from a copper-free Sonogashira cross-coupling reaction between ethynylferrocene and 4-bromo-1-nitrobenzene, crystallizes in the P2₁/n space group. In the ferrocene unit, the pentadienyl (Cps) rings are in an eclipsed conformation. The angle of rotation between the substituted cyclopentadienyl ring and the p-nitrophenyl group is 6.19 (10)°, yielding a quasi-linear extension of the ferrocenyl substitution. Important intermolecular interactions arise from π–π stacking between the Cp rings and the p-nitrophenyl, from corners of the Cp rings that are perpendicularly aligned, and between the O atoms from the nitro substituent and carbons at the corners of the Cp rings, propagating along all three crystallographic axes.

Keywords: ferrocene; 4-nitrophenylethyne; Sonogashira coupling; green chemistry; crystal structure.

CCDC reference: 1991635

1. Chemical context

Recent efforts in the field of medicinal organometallic chemistry have been driven by a high interest in the synthesis of metal ethynyl complexes, particularly because of their biological activity (Görmen et al., 2012 ). In addition, phenylethyne-derived compounds display active electrochemical properties such as the generation of stable redox forms, regeneration at low potentials and good electrochemical reversibility (Gasser & Metzler-Nolte, 2012 ). 1-Ferrocenyl-2-(4-nitrophenyl)ethyne has previously been prepared in moderate-to-high yields (52–92%) by applying Sonogashira coupling reactions. However, all of them used 4-iodo-1-nitrobenzene or 4-triflate-1-nitrobenzene and a variety of solvents, catalysts and conditions, under an inert atmosphere. The reaction time varied from 25 min to 4 h (Torres et al., 2002 ; Shoji et al., 2014 ; Li et al., 2009 ; Fu et al., 2008 ; Coutouli-Argyropoulou et al., 2003 ). Other approaches involved the use of iodoferrocene and 4-ethynyl-1-nitrobenzene (Kulhánek et al., 2013 ). Our approach focuses on performing copper-free Sonogashira coupling between ethynylferrocene and 4-bromo-1-nitrobenzene without the need of inert atmosphere protocols and obtaining moderate-to-high yields, by following green chemistry protocols.

2. Structural commentary

Fig. 1 (Mercury; Macrae et al., 2020 ) shows the molecular structure of the title compound, which crystallizes in space group P2₁/n. The substituted ferrocene (Fc) system is linked to a p-nitrobenzene moiety by an acetylenic bridge between C11 and C12 with a bond distance of 1.202 (2) Å, which is comparable to those in similar complexes, e.g. 1.202 (2) Å (Misra et al. 2014 ), 1.197 (3) Å (Fu et al., 2008), and 1.193 (2) Å (Zora et al. 2006 ). The unit cell is comprised of four molecules with one molecule present per asymmetric unit. The substituted Cp and phenyl rings are almost parallel to each other, subtending a dihedral angle of 6.19 (10)°, in contrast to (phenyl-ethynyl)ferrocene (Zora et al., 2006), which has no substituent in the para position and exhibits a nearly perpendicular dihedral angle of 89.06 (3)°. The distances of the Fe1 atom from the centroids of the substituted and unsubstituted Cp rings are 1.6461 (8) and 1.6584 (8) Å, respectively. The Cg1—Fe1—Cg2 angle is 179.27°, where Cg1 and Cg2 are the centroids of substituted and unsubstituted Cp rings, respectively. The Cp rings in the ferrocene system are thus almost parallel, since the angle between the Cp ring planes is 1.03 (13)°. In addition, the Cp rings display a nearly eclipsed conformation with a slight deviation, as demonstrated by the average C—Cg1—Cg2—C torsion angle of 12.26°. The C—C bond distances in the Cp rings range from 1.417 (2) to 1.436 (2) Å, while the Fe—C bond lengths range between 2.038 (2) and 2.055 (2) Å.

Figure 1
Molecular structure of the title compound, including atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

3. Supramolecular features

The title compound exhibits π–π stacking interactions between one of the Cp rings from the Fc moiety and the p-nitrophenyl substituent, allowing the formation of a zigzag structure; atom pairs involved relate C6(Cp) and C7(Cp) to C17(p-nitrophenyl) and C18(p-nitrophenyl) of a neighboring molecule, with short contacts of 3.340 (2) and 3.397 (2) Å, respectively. This interaction can be described as pairs of molecules being interrupted by two C3(Cp)⋯H8—C8(Cp) interactions from a different interconnected pair of perpendicularly oriented Fc moieties with short contact distances of 2.83 Å each. Short contacts from neighboring molecules establishing a distinctive interconnected pair between a corner of the Cp ring and one of the oxygen atoms from the p-nitrophenyl substituent yield a closed arrangement of atoms. Short contacts involve H6—C6(Cp)⋯O1(p-nitrophenyl) at a distance of 3.461 (2) Å. Another interconnection is found between adjacent p-nitrophenyl groups, yielding a ring arrangement involving pairs from H17—C17(p-nitrophenyl)⋯O2(p-nitrophenyl) with a distance of 2.727 (2) Å and pairs from O1(p-nitrophenyl)⋯H15—C15(p-nitrophenyl) with a distance of 2.716 (2) Å. In addition, a chain is formed by short contacts from the C17—H17(p-nitrophenyl)⋯O1(p-nitrophenyl) interaction belonging to the p-nitrophenyl substituent with a distance of 3.203 (19) Å. Numerical details of the hydrogen-bonding interactions are given in Table 1 and the packing is shown in Fig. 2.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯O1ⁱ	0.93	2.55	3.461 (2)	168
C15—H15⋯O1ⁱⁱ	0.93	2.41	3.1909 (19)	141
C17—H17⋯O2ⁱⁱⁱ	0.93	2.49	3.2187 (19)	135
Symmetry codes: (i) -x, -y+1, -z+1; (ii) -x-1, -y+1, -z+1; (iii) -x, -y+1, -z.

Figure 2
Crystal packing of the title compound along the a axis with short-contact interactions shown as dashed lines.

4. Hirshfeld Surface Analysis

CrystalExplorer17 (Turner et al., 2017 ) was used to generate the Hirshfeld surface (Spackman & Jayatilaka, 2009 ) for the title compound mapped over d_norm and the associated two-dimensional fingerprint plots (McKinnon et al., 2007 ). Fig. 3 shows the molecules involved in the four closest contacts. Red spots on the Hirshfeld surface mapped over d_norm in the color range −0.2315 to 1.1417 arbitrary units confirm the previously mentioned main intermolecular contacts. The fingerprint plots are given for all contacts (Fig. 4a) and those decomposed into nine individual interactions: H⋯H (46.9%; Fig. 4b), C⋯H/ H⋯C (21.9%; Fig. 4c), O⋯H/ H⋯O (18.7%; Fig. 4d), C⋯C (7.5%; Fig. 4e), C⋯O/O⋯C (1.6%; Fig. 4f), C⋯N/N⋯C (1.2%; Fig. 4g), N⋯O/O⋯N (0.9%; Fig. 4h), O⋯O (0.9%; Fig. 4i) and N⋯H/H⋯N (0.5%; Fig. 4j). The Hirshfeld surface analysis for the title compound indicates that the most significant contributions arise from H⋯H and C⋯H contacts (González et al., 2020 ; McKinnon et al., 2004 , 2007; Spackman & McKinnon, 2002 ).

Figure 3
A view of the Hirshfeld surface of the title compound mapped over d_norm with the four main intermolecular contacts in the crystal lattice.

Figure 4
Full (a) and individual (b)–(j) two-dimensional fingerprint plots showing the nine intermolecular contacts present in the crystal structure.

5. Database survey

A search of the Cambridge Structural Database (Version 5.41, updated November 2019; Groom et al., 2016 ) revealed 142 related compounds with the 1-ferrocenyl-2-phenylethyne backbone. Of those structures, 41 contain substituents in the para position of the phenyl ring, as in the title compound. One of the reasons for such a high number of reported structures for methynylferrocene and its derived compounds is attributed to their substantial interest as chromophores, mainly because of their electronic communication capacity through the alkyne linkage to the Fe center. When comparing the effect of the substituent on the molecular structure, one of the main features is the dihedral angle that is formed between the substituted Cp ring of the ferrocene group and the phenyl moiety. The orientation can range from almost parallel (1.01°: YOHSIY; Bobula et al., 2008 ) to completely perpendicular (90.00°: YOHSUK01; Dai et al., 2013 ). Table 2 gives the dihedral angles for previously reported compounds; our compound having the second lowest dihedral angle and a nearly parallel conformation. Exchanging the hydrogen atoms in the methyl group for fluorine atoms shifts the dihedral angle from 1.01° to 90.00° in the case of methyl and trifluoromethyl substituents, respectively.

Table 2
The effect of the substituent on the dihedral angle (°) between the substituted Cp ring and the phenyl ring in compounds containing a 1-ferrocenyl-2-phenylethyne backbone and a para-substituted phenyl ring

Substituent	Dihedral angle	Refcode
Methyl (CH₃)	1.01 (9)	YOHSIY (Bobula et al., 2008)
Nitro (NO₂)	6.61 (9)	This work
Amino (NH₂)	8.05 (9)	YONFEN (Siemeling et al., 2008 )
Ethynyl (C≡CH)	8.61 (9)	RARNED (Lin et al., 1996 )
Iodo (I)	37.25 (9)	GIZTOA (Misra et al., 2014)
Cyano (C≡N)	69.58 (9)	MIJLAS01 (Bobula et al., 2008)
Hydrogen (H)	89.06 (9)	KELTIF (Zora et al., 2006)
Trifluoromethyl (CF₃)	90.00 (9)	YOKSUK01 (Dai et al., 2013)

6. Synthesis and crystallization

The title compound was prepared by adding ethynylferrocene (1.0 mmol), PdCl₂(PPh₃)₂ (0.01 mmol), Et₃N (2 mmol) and 4-bromo-1-nitrobenzene (1.0 mmol) to a 25 mL round-bottom flask, followed by the addition of DMF (1.0 mL) by syringe. The reaction was stirred for 1 h at 353 K. The reaction was stopped and crashed out with 20 mL of cold distilled water, then the solid was vacuum filtrated, and chromatographed [silica (heptane–ethyl acetate/7:3)] to afford the pure compound, 70% yield. Dark-red crystals suitable for X-ray diffraction were obtained by the slow evaporation of CDCl₃ solution of the title compound at room temperature. NMR analyses were performed on a Bruker AV-700 spectrometer by using CDCl₃ 99.9% pure as a solvent and Me₄Si as external standard.¹H NMR (δ in ppm, CDCl₃): 4.26 (s, 5H), 4.32 (s, 2H), 4.55 (s, 2H), 7.59 (d, J = 8.6Hz, 2H), 8.18 (d, J = 8.6Hz, 2H). ¹³C NMR (δ in ppm, CDCl₃): 63.6, 69.6, 70.1, 71.8, 84.5, 95.2, 123.6, 131.1, 131.8, 146.4. IR (ν_max, cm⁻¹): 2200 (C≡C). Electrochemistry: (CV_{200 mv}: E^o = 613 mV; ΔE = 90 mV).

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms were included in geometrically calculated positions, C—H = 0.93 Å, and refined as riding on their parent C atom with U_iso(H) = 1.2U_eq(C).

Table 3
Experimental details

Crystal data
Chemical formula	[Fe(C₅H₅)₂(C₈NO₂)]
M_r	331.14
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	5.9573 (1), 29.3810 (3), 8.0664 (1)
β (°)	100.202 (1)
V (Å³)	1389.55 (3)
Z	4
Radiation type	Cu Kα
μ (mm⁻¹)	8.75
Crystal size (mm)	0.20 × 0.07 × 0.04

Data collection
Diffractometer	Rigaku SuperNova, Single source at offset/far, HyPix3000
Absorption correction	Multi-scan (CrysAlis PRO; Rigaku OD, 2018 $[Rigaku OD (2018). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England.]$ )
T_min, T_max	0.642, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	21951, 2567, 2410
R_int	0.036
(sin θ/λ)_max (Å⁻¹)	0.605

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.024, 0.061, 1.07
No. of reflections	2567
No. of parameters	200
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.23, −0.37
Computer programs: CrysAlis PRO (Rigaku OD, 2018 $[Rigaku OD (2018). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England.]$ ), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 1991635

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989020010336/dj2003sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020010336/dj2003Isup2.hkl

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Rigaku OD, 2018); cell refinement: CrysAlis PRO (Rigaku OD, 2018); data reduction: CrysAlis PRO (Rigaku OD, 2018); program(s) used to solve structure: ShelXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

1-Ferrocenyl-2-(4-nitrophenyl)ethyne top

Crystal data top

[Fe(C₅H₅)₂(C₈NO₂)]	F(000) = 680
M_r = 331.14	D_x = 1.583 Mg m⁻³
Monoclinic, P2₁/n	Cu Kα radiation, λ = 1.54184 Å
a = 5.9573 (1) Å	Cell parameters from 12369 reflections
b = 29.3810 (3) Å	θ = 3.0–68.8°
c = 8.0664 (1) Å	µ = 8.75 mm⁻¹
β = 100.202 (1)°	T = 100 K
V = 1389.55 (3) Å³	Block, dark red
Z = 4	0.20 × 0.07 × 0.04 mm

Data collection top

Rigaku SuperNova, Single source at offset/far, HyPix3000 diffractometer	2567 independent reflections
Radiation source: micro-focus sealed X-ray tube, SuperNova (Cu) X-ray Source	2410 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.036
ω scans	θ_max = 68.9°, θ_min = 3.0°
Absorption correction: multi-scan (CrysAlisPro; Rigaku OD, 2018)	h = −7→7
T_min = 0.642, T_max = 1.000	k = −35→35
21951 measured reflections	l = −9→9

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.024	w = 1/[σ²(F_o²) + (0.0305P)² + 0.6401P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.061	(Δ/σ)_max = 0.003
S = 1.07	Δρ_max = 0.23 e Å⁻³
2567 reflections	Δρ_min = −0.37 e Å⁻³
200 parameters	Extinction correction: SHELXL-2018/3 (Sheldrick 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00060 (13)
Primary atom site location: dual

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
Fe1	0.76257 (4)	0.67811 (2)	0.90888 (3)	0.01397 (9)
O1	−0.49667 (19)	0.47779 (4)	0.27187 (15)	0.0226 (3)
O2	−0.2775 (2)	0.46760 (4)	0.08806 (15)	0.0271 (3)
N1	−0.3245 (2)	0.48668 (4)	0.21343 (17)	0.0167 (3)
C1	0.5321 (3)	0.68695 (5)	0.6915 (2)	0.0173 (3)
C2	0.7551 (3)	0.70112 (5)	0.6686 (2)	0.0192 (3)
H2	0.837507	0.689297	0.590834	0.023*
C3	0.8274 (3)	0.73649 (5)	0.7863 (2)	0.0208 (3)
H3	0.965574	0.751951	0.798205	0.025*
C4	0.6531 (3)	0.74426 (5)	0.8827 (2)	0.0205 (3)
H4	0.657556	0.765623	0.968280	0.025*
C5	0.4711 (3)	0.71379 (5)	0.8256 (2)	0.0198 (3)
H5	0.335922	0.711567	0.867718	0.024*
C6	0.7951 (3)	0.60950 (5)	0.9567 (2)	0.0221 (4)
H6	0.732434	0.586180	0.885223	0.026*
C7	1.0133 (3)	0.62957 (5)	0.9617 (2)	0.0193 (3)
H7	1.118391	0.621784	0.893815	0.023*
C8	1.0425 (3)	0.66366 (5)	1.0887 (2)	0.0192 (3)
H8	1.170282	0.682060	1.118684	0.023*
C9	0.8431 (3)	0.66474 (6)	1.1617 (2)	0.0212 (4)
H9	0.817060	0.683939	1.247992	0.025*
C10	0.6897 (3)	0.63126 (6)	1.0798 (2)	0.0233 (4)
H10	0.545564	0.624788	1.103002	0.028*
C11	0.3932 (3)	0.65207 (5)	0.6029 (2)	0.0189 (3)
C12	0.2680 (3)	0.62353 (6)	0.5308 (2)	0.0195 (3)
C13	0.1182 (3)	0.58890 (5)	0.4500 (2)	0.0170 (3)
C14	−0.0833 (3)	0.57845 (5)	0.5091 (2)	0.0182 (3)
H14	−0.119391	0.594223	0.600861	0.022*
C15	−0.2291 (3)	0.54491 (5)	0.43247 (19)	0.0167 (3)
H15	−0.363101	0.537993	0.471276	0.020*
C16	−0.1700 (3)	0.52188 (5)	0.2961 (2)	0.0153 (3)
C17	0.0281 (3)	0.53113 (5)	0.2348 (2)	0.0170 (3)
H17	0.063821	0.515003	0.143683	0.020*
C18	0.1713 (3)	0.56480 (5)	0.3118 (2)	0.0182 (3)
H18	0.304440	0.571598	0.271639	0.022*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Fe1	0.01496 (14)	0.01010 (14)	0.01622 (15)	−0.00021 (9)	0.00100 (10)	0.00119 (9)
O1	0.0200 (6)	0.0236 (6)	0.0264 (6)	−0.0064 (5)	0.0101 (5)	−0.0040 (5)
O2	0.0305 (7)	0.0265 (7)	0.0274 (7)	−0.0059 (5)	0.0137 (6)	−0.0127 (5)
N1	0.0188 (7)	0.0139 (6)	0.0179 (7)	0.0005 (5)	0.0049 (5)	0.0000 (5)
C1	0.0184 (8)	0.0138 (7)	0.0183 (8)	0.0005 (6)	−0.0004 (7)	0.0045 (6)
C2	0.0213 (8)	0.0158 (8)	0.0207 (8)	−0.0001 (6)	0.0039 (7)	0.0054 (6)
C3	0.0187 (8)	0.0142 (8)	0.0278 (9)	−0.0020 (6)	−0.0008 (7)	0.0071 (7)
C4	0.0233 (9)	0.0117 (7)	0.0243 (9)	0.0027 (6)	−0.0015 (7)	0.0004 (6)
C5	0.0180 (8)	0.0163 (8)	0.0244 (9)	0.0023 (6)	0.0020 (7)	0.0025 (6)
C6	0.0282 (9)	0.0111 (8)	0.0236 (9)	−0.0010 (6)	−0.0047 (7)	0.0037 (6)
C7	0.0216 (8)	0.0149 (8)	0.0205 (8)	0.0050 (6)	0.0011 (7)	0.0021 (6)
C8	0.0201 (8)	0.0151 (8)	0.0201 (8)	−0.0003 (6)	−0.0024 (7)	0.0021 (6)
C9	0.0274 (9)	0.0200 (8)	0.0161 (8)	0.0035 (7)	0.0030 (7)	0.0022 (6)
C10	0.0203 (8)	0.0229 (9)	0.0262 (9)	−0.0016 (7)	0.0026 (7)	0.0106 (7)
C11	0.0200 (8)	0.0165 (8)	0.0196 (8)	0.0012 (6)	0.0014 (7)	0.0032 (6)
C12	0.0203 (8)	0.0177 (8)	0.0200 (8)	0.0017 (7)	0.0026 (7)	0.0037 (7)
C13	0.0190 (8)	0.0131 (7)	0.0176 (8)	0.0007 (6)	−0.0005 (6)	0.0041 (6)
C14	0.0225 (8)	0.0166 (8)	0.0155 (8)	0.0018 (6)	0.0032 (6)	−0.0001 (6)
C15	0.0176 (8)	0.0164 (8)	0.0165 (8)	0.0010 (6)	0.0045 (6)	0.0022 (6)
C16	0.0175 (8)	0.0123 (7)	0.0159 (8)	−0.0002 (6)	0.0019 (6)	0.0011 (6)
C17	0.0183 (8)	0.0162 (8)	0.0169 (8)	0.0023 (6)	0.0048 (6)	0.0006 (6)
C18	0.0172 (8)	0.0177 (8)	0.0200 (8)	0.0007 (6)	0.0038 (6)	0.0045 (6)

Geometric parameters (Å, º) top

Fe1—C1	2.0431 (17)	C6—H6	0.9300
Fe1—C2	2.0454 (16)	C6—C7	1.422 (2)
Fe1—C3	2.0505 (16)	C6—C10	1.418 (3)
Fe1—C4	2.0491 (16)	C7—H7	0.9300
Fe1—C5	2.0375 (16)	C7—C8	1.421 (2)
Fe1—C6	2.0552 (16)	C8—H8	0.9300
Fe1—C7	2.0546 (16)	C8—C9	1.417 (2)
Fe1—C8	2.0515 (17)	C9—H9	0.9300
Fe1—C9	2.0489 (17)	C9—C10	1.423 (3)
Fe1—C10	2.0488 (16)	C10—H10	0.9300
O1—N1	1.2301 (17)	C11—C12	1.202 (2)
O2—N1	1.2312 (17)	C12—C13	1.432 (2)
N1—C16	1.464 (2)	C13—C14	1.402 (2)
C1—C2	1.435 (2)	C13—C18	1.403 (2)
C1—C5	1.437 (2)	C14—H14	0.9300
C1—C11	1.427 (2)	C14—C15	1.385 (2)
C2—H2	0.9300	C15—H15	0.9300
C2—C3	1.422 (2)	C15—C16	1.389 (2)
C3—H3	0.9300	C16—C17	1.385 (2)
C3—C4	1.422 (2)	C17—H17	0.9300
C4—H4	0.9300	C17—C18	1.380 (2)
C4—C5	1.418 (2)	C18—H18	0.9300
C5—H5	0.9300

C1—Fe1—C2	41.09 (6)	C4—C3—C2	108.54 (14)
C1—Fe1—C3	68.60 (6)	C4—C3—H3	125.7
C1—Fe1—C4	68.76 (6)	Fe1—C4—H4	126.6
C1—Fe1—C6	108.20 (7)	C3—C4—Fe1	69.76 (9)
C1—Fe1—C7	128.28 (7)	C3—C4—H4	125.9
C1—Fe1—C8	166.33 (7)	C5—C4—Fe1	69.25 (9)
C1—Fe1—C9	151.89 (7)	C5—C4—C3	108.16 (15)
C1—Fe1—C10	118.21 (7)	C5—C4—H4	125.9
C2—Fe1—C3	40.62 (7)	Fe1—C5—H5	125.9
C2—Fe1—C4	68.63 (7)	C1—C5—Fe1	69.60 (9)
C2—Fe1—C6	119.18 (7)	C1—C5—H5	126.0
C2—Fe1—C7	108.59 (7)	C4—C5—Fe1	70.13 (9)
C2—Fe1—C8	128.09 (7)	C4—C5—C1	108.06 (15)
C2—Fe1—C9	165.58 (7)	C4—C5—H5	126.0
C2—Fe1—C10	152.64 (7)	Fe1—C6—H6	126.3
C3—Fe1—C6	153.07 (7)	C7—C6—Fe1	69.74 (9)
C3—Fe1—C7	119.24 (7)	C7—C6—H6	126.0
C3—Fe1—C8	108.37 (7)	C10—C6—Fe1	69.55 (9)
C4—Fe1—C3	40.58 (7)	C10—C6—H6	126.0
C4—Fe1—C6	165.33 (7)	C10—C6—C7	108.03 (15)
C4—Fe1—C7	152.40 (7)	Fe1—C7—H7	126.1
C4—Fe1—C8	118.25 (7)	C6—C7—Fe1	69.78 (9)
C5—Fe1—C1	41.23 (7)	C6—C7—H7	126.1
C5—Fe1—C2	69.11 (7)	C8—C7—Fe1	69.63 (9)
C5—Fe1—C3	68.47 (7)	C8—C7—C6	107.88 (15)
C5—Fe1—C4	40.62 (7)	C8—C7—H7	126.1
C5—Fe1—C6	127.80 (7)	Fe1—C8—H8	126.1
C5—Fe1—C7	166.23 (7)	C7—C8—Fe1	69.87 (9)
C5—Fe1—C8	151.41 (7)	C7—C8—H8	125.9
C5—Fe1—C9	117.54 (7)	C9—C8—Fe1	69.69 (9)
C5—Fe1—C10	107.31 (7)	C9—C8—C7	108.12 (15)
C7—Fe1—C6	40.48 (7)	C9—C8—H8	125.9
C8—Fe1—C6	68.07 (7)	Fe1—C9—H9	126.0
C8—Fe1—C7	40.50 (6)	C8—C9—Fe1	69.89 (9)
C9—Fe1—C3	127.56 (7)	C8—C9—H9	126.0
C9—Fe1—C4	107.38 (7)	C8—C9—C10	107.97 (15)
C9—Fe1—C6	68.12 (7)	C10—C9—Fe1	69.67 (9)
C9—Fe1—C7	68.10 (7)	C10—C9—H9	126.0
C9—Fe1—C8	40.42 (7)	Fe1—C10—H10	125.9
C10—Fe1—C3	165.28 (7)	C6—C10—Fe1	70.03 (9)
C10—Fe1—C4	127.24 (7)	C6—C10—C9	108.00 (15)
C10—Fe1—C6	40.42 (7)	C6—C10—H10	126.0
C10—Fe1—C7	68.11 (7)	C9—C10—Fe1	69.68 (9)
C10—Fe1—C8	68.14 (7)	C9—C10—H10	126.0
C10—Fe1—C9	40.65 (7)	C12—C11—C1	177.07 (18)
O1—N1—O2	123.00 (13)	C11—C12—C13	178.15 (18)
O1—N1—C16	118.36 (13)	C14—C13—C12	120.19 (15)
O2—N1—C16	118.63 (13)	C14—C13—C18	119.13 (15)
C2—C1—Fe1	69.54 (9)	C18—C13—C12	120.67 (15)
C2—C1—C5	107.51 (14)	C13—C14—H14	119.6
C5—C1—Fe1	69.18 (9)	C15—C14—C13	120.74 (15)
C11—C1—Fe1	125.49 (11)	C15—C14—H14	119.6
C11—C1—C2	127.74 (15)	C14—C15—H15	120.9
C11—C1—C5	124.74 (15)	C14—C15—C16	118.24 (14)
Fe1—C2—H2	126.2	C16—C15—H15	120.9
C1—C2—Fe1	69.37 (9)	C15—C16—N1	118.51 (14)
C1—C2—H2	126.1	C17—C16—N1	118.86 (14)
C3—C2—Fe1	69.88 (9)	C17—C16—C15	122.62 (15)
C3—C2—C1	107.72 (14)	C16—C17—H17	120.7
C3—C2—H2	126.1	C18—C17—C16	118.53 (15)
Fe1—C3—H3	126.7	C18—C17—H17	120.7
C2—C3—Fe1	69.50 (9)	C13—C18—H18	119.6
C2—C3—H3	125.7	C17—C18—C13	120.73 (15)
C4—C3—Fe1	69.66 (9)	C17—C18—H18	119.6

Fe1—C1—C2—C3	−59.59 (11)	C5—C1—C2—C3	−0.63 (18)
Fe1—C1—C5—C4	59.82 (11)	C6—C7—C8—Fe1	−59.53 (11)
Fe1—C2—C3—C4	−58.88 (11)	C6—C7—C8—C9	−0.12 (18)
Fe1—C3—C4—C5	−58.78 (11)	C7—C6—C10—Fe1	59.33 (11)
Fe1—C4—C5—C1	−59.48 (11)	C7—C6—C10—C9	−0.24 (18)
Fe1—C6—C7—C8	59.43 (11)	C7—C8—C9—Fe1	−59.51 (11)
Fe1—C6—C10—C9	−59.57 (12)	C7—C8—C9—C10	−0.02 (18)
Fe1—C7—C8—C9	59.40 (11)	C8—C9—C10—Fe1	−59.63 (11)
Fe1—C8—C9—C10	59.49 (11)	C8—C9—C10—C6	0.16 (19)
Fe1—C9—C10—C6	59.79 (11)	C10—C6—C7—Fe1	−59.21 (11)
O1—N1—C16—C15	−2.5 (2)	C10—C6—C7—C8	0.22 (18)
O1—N1—C16—C17	177.91 (14)	C11—C1—C2—Fe1	−119.65 (17)
O2—N1—C16—C15	176.88 (14)	C11—C1—C2—C3	−179.24 (15)
O2—N1—C16—C17	−2.7 (2)	C11—C1—C5—Fe1	119.48 (16)
N1—C16—C17—C18	179.07 (14)	C11—C1—C5—C4	179.29 (15)
C1—C2—C3—Fe1	59.27 (11)	C12—C13—C14—C15	−179.76 (15)
C1—C2—C3—C4	0.39 (18)	C12—C13—C18—C17	179.41 (15)
C2—C1—C5—Fe1	−59.19 (11)	C13—C14—C15—C16	0.2 (2)
C2—C1—C5—C4	0.62 (18)	C14—C13—C18—C17	−0.2 (2)
C2—C3—C4—Fe1	58.78 (11)	C14—C15—C16—N1	−179.41 (14)
C2—C3—C4—C5	−0.01 (18)	C14—C15—C16—C17	0.1 (2)
C3—C4—C5—Fe1	59.10 (11)	C15—C16—C17—C18	−0.4 (2)
C3—C4—C5—C1	−0.38 (18)	C16—C17—C18—C13	0.5 (2)
C5—C1—C2—Fe1	58.96 (11)	C18—C13—C14—C15	−0.2 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O1ⁱ	0.93	2.55	3.461 (2)	168
C15—H15···O1ⁱⁱ	0.93	2.41	3.1909 (19)	141
C17—H17···O2ⁱⁱⁱ	0.93	2.49	3.2187 (19)	135

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

The effect of the substituent on the dihedral angle (°) between the substituted Cp ring and the phenyl ring in compounds containing a 1-ferrocenyl-2-phenylethyne backbone and a para-substituted phenyl ring top

Substituent	Dihedral angle	Refcode
Methyl (CH₃)	1.01 (9)	YOHSIY (Bobula et al., 2008)
Nitro (NO₂)	6.61 (9)	This work
Amino (NH₂)	8.05 (9)	YONFEN (Siemeling et al., 2008)
Ethynyl (C≡CH)	8.61 (9)	RARNED (Lin et al., 1996)
Iodo (I)	37.25 (9)	GIZTOA (Misra et al., 2014)
Cyano (C≡N)	69.58 (9)	MIJLAS01 (Bobula et al., 2008)
Hydrogen (H)	89.06 (9)	KELTIF (Zora et al., 2006)
Trifluoromethyl (CF₃)	90.00 (9)	YOKSUK01 (Dai et al., 2013)

Funding information

The authors acknowledge financial support under the NIH–RISE program, grant No. 2 R25 GM061151, and the NSF–CREST Center for Innovation, Research and Education in Environmental Nanotechnology, grant No. HRD-1736093. The single-crystal X-ray micro focus diffractometer was acquired through the support of the National Science Foundation under the Major Research Instrumentation Award No. CHE-1626103.

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