Toward a Tunable Synthetic [FeFe]-Hydrogenase H-Cluster Mimic Mediated by Perylene Monoimide Model Complexes: Insight into Molecular Structures and Electrochemical Characteristics

Article abstract of DOI:10.1021/acs.organomet.8b00450

The nature of the bridging dithiolate has an important role on tuning the physical and electrochemical properties of the synthetic H-cluster mimics of [FeFe]-hydrogenase and still of significant concern to scientists. In this report we describe the synthetic models of the active site of [FeFe]-hydrogenase containing perylene monoimide of peri-substituted disulfides as bridging linker. The resulting complexes were characterized by ¹H and ¹³C{¹H} NMR and IR spectroscopic techniques, mass spectrometry, and elemental analysis as well as X-ray analysis of complex 2a. The purpose of this work was to investigate the influence of the perylene-linker on the redox potentials of the complexes and their catalytic ability in the presence of acetic acid (AcOH) by applying cyclic voltammetry. Moreover, we compare these results with different diiron hexacarbonyl complexes previously reported in the literature. As a result, we have found that the presence of the rylene-linker provides further stability for the reduced species and shifted its reduction potentials to more positive values.

Full text of DOI:10.1021/acs.organomet.8b00450

Article
pubs.acs.org/Organometallics
Cite This: Organometallics XXXX, XXX, XXX−XXX
Toward a Tunable Synthetic [FeFe]-Hydrogenase H‑Cluster Mimic
Mediated by Perylene Monoimide Model Complexes: Insight into
Molecular Structures and Electrochemical Characteristics
†
‡
∥
Hassan Abul-Futouh,†,§,# Artem Skabeev,†,§ Davide Botteri, Yulian Zagranyarski, Helmar Gorls,
̈
Wolfgang Weigand,∥ and Kalina Peneva*,†,⊥
†Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, Lessingstrasse 8, 07743 Jena,
Germany
‡Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment Ohridski”, 1 James Bourchier Avenue, Sofia 1164, Bulgaria
∥Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldt Str. 8, 07743 Jena, Germany
⊥Friedrich Schiller University, CEEC Jena, Philosophenweg 7a, 07743 Jena, Germany
#Department of Pharmacy, Al-Zytoonah University of Jordan, P. O. Box 130, Amman 11733, Jordan
S
* Supporting Information
ABSTRACT: The nature of the bridging dithiolate has an important role on tuning the physical and electrochemical properties
of the synthetic H-cluster mimics of [FeFe]-hydrogenase and still of significant concern to scientists. In this report we describe
the synthetic models of the active site of [FeFe]-hydrogenase containing perylene monoimide of peri-substituted disulfides as
1
bridging linker. The resulting complexes were characterized by H and 13C{1H} NMR and IR spectroscopic techniques, mass
spectrometry, and elemental analysis as well as X-ray analysis of complex 2a. The purpose of this work was to investigate the
influence of the perylene-linker on the redox potentials of the complexes and their catalytic ability in the presence of acetic acid
(AcOH) by applying cyclic voltammetry. Moreover, we compare these results with different diiron hexacarbonyl complexes
previously reported in the literature. As a result, we have found that the presence of the rylene-linker provides further stability
for the reduced species and shifted its reduction potentials to more positive values.
an “H-cluster” (Figure 1, A) that is composed of canonical
[Fe4S4]-cluster coupled to a dinuclear iron complex called the
[Fe2S2] subsite.6 The [Fe2S2] subsite features a bridging
azadithiolato ligand as well as three CO and two CN− ligands
as shown in Figure 1, A. In the past few decades, many studies
have been devoted to the synthesis and characterization of the
H-cluster mimics and tested as electrocatalysts.7−9 The
modifications of the bridging dithiolate linker of the synthetic
H-cluster mimics play a crucial role in tuning its redox
potential and the number of electrons involved in the
reduction process.
INTRODUCTION
■
The tendency of finding clean and sustainable energy sources
has led to interest in molecular hydrogen production for fuel.1
In recent years, improving catalysts for producing molecular
hydrogen under mild conditions has inspired the design and
synthesis of different model complexes of hydrogenases. The
latter is a class of metalloenzymes found in bacteria and
selected archaea that catalyze both directions of the H+/H2
couple.2−4 These metalloenzymes can be classified into
[NiFe]-hydrogenases, [FeFe]-hydrogenases and [Fe]-hydro-
genases (Hmd) and among them, [FeFe]-hydrogenase has the
strongest catalytic ability for molecular hydrogen production at
pH = 7 and at mild reduction potentials (−0.4 V vs. NHE).4,5
The active site for all known [FeFe]-hydrogenases consists of
Received: July 1, 2018
© XXXX American Chemical Society
A
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Figure 2. Chemical structures of perylene monoimide (PMI)
derivatives used in this work.
employing a variety of analytical techniques (NMR spectros-
copy, elemental analysis, IR and mass spectrometry, and X-ray
structure determination of complex 2a). In addition, we
investigate the influence of the presence of PMI spacers of the
diiron complexes 1a−3a on the redox properties and the
catalytic behavior by applying cyclic voltammetry.
Figure 1. (A) Schematic representation of the H-cluster. (B−E)
Possible alterations of the bridging dithiolate linker of the synthetic
H-cluster mimics.
However, most of these reported models can electrocatalyze
the proton reduction with ∼1.0 V more negative than the
native enzyme.10 One of the most important factors that can
lead to productive electrocatalysis of the synthetic complexes is
the stability of its reduced species, which are considered as
intermediates in the catalytic cycle.8a For example, Pickett,
Heinekey and co-workers showed that the formation of the
monoanion species of [Fe2(CO)6{μ-pdt}] (pdt = 1,3-propane
dithiolate) (Figure 1, B) is not a reversible process indicating
that this species is not appreciably stable under reducing
conditions.11−13 On the other hand, the cyclic voltammogram
of [Fe2(CO)6{μ-bdt}] (bdt = 1,2-benzenedithiole) (Figure 1,
C) showed that it can be reduced by two electrons in a single
step unlike [Fe2(CO)6{μ-pdt}] complex.14−16 The presence of
a such thiolate-bridge enhanced the stability of the reduced
forms since the electrons are delocalized over the phenyl ring
and hence provide a more energetically favorable proton
reduction catalyst. Furthermore, it has been shown by Tilley
and others that the synthetic model [Fe2(CO)6{μ-naphth}]
(naphth = 1,8-naphthalenedithiole) (Figure 1, D) enhanced
the stability of the reduced species and hence reduced with the
normal ordering of potentials (i.e., E°1 is less negative than
E°2).8a−d This can be explained, if the rigidity of the
naphthalene ring is considered, as it decreases the probability
of such degradation pathways often observed for other
synthetic models having a saturated ligand in its linkers.
Moreover, the electronic properties of such model compounds
can be fine-tuned through chemical modifications of the
naphthalene backbone.8a−d For example, the introduction of an
imide group has provided additional stability to the
monoanionic species due to its strong electron-withdrawing
effect and thus has served as a suitable site for the attachment
of an additional chromophore (Figure 1, E).17−19 On the basis
of these findings, we have focused on synthetic architectures
that mimic the H-cluster and contain perylene monoimide
(PMI) dyes in its spacers. The perylene monoimide
chromophores are well-known for their excellent chemical,
thermal and photostability, and their low cost.20,21 Moreover,
these dyes can be substituted in the so-called bay-, ortho-, peri-
or imide-positions, (the nomenclature is explained in Figure 2)
demonstrating the ease and versatility with which the
electronic properties of the chromophores can be tailored for
a broad variety of applications.22 Herein we describe for the
first time the use of PMI derivatives (compounds 1−3, Figure
2) as proligands for the synthesis of [FeFe]-hydrogenase H-
cluster mimics. The resulting complexes are fully characterized
RESULTS AND DISCUSSION
■
The synthesis of compounds 1−3 were carried out following
procedures previously described in the literature.23,24 Com-
pounds 1, 2 and 3 were then reacted with [Fe2(CO)6{μ-S2}]
complex, that were synthesized following modified procedure
by Stanley et al. (Scheme 1, A).26 The reaction of in situ
generated [Fe2(CO)6{μ-(LiS)2}] with one equivalent of
compounds 1−3 afforded the diiron complexes 1a−3a and
the disulfide compounds 1b−3b as byproducts (Scheme 1, A).
Another synthetic strategy to obtain complexes 1a−3a is by
oxidative addition reaction of peri-perylene disulfide com-
pounds with Fe3(CO)12 (Scheme 1, B). In this alternative
synthetic pathway, the PMI-compounds 1−3 were reacted
with the elemental sulfur in NMP at 160 °C for 6 h to afford
compounds 1b−3b (Scheme 1, B).25 Next, the resulting
compounds consequently were reacted with equimolar
amounts of Fe3(CO)12 in boiling THF for 3 h followed by
column chromatography to afford the diiron complexes 1a−3a
in comparable yields to method A in Scheme 1. The resulting
complexes 1a−3a were characterized by spectroscopic
methods (1H NMR, 13C{1H} NMR and IR), mass
spectrometry, elemental analysis and X-ray crystallography
for 2a.
The IR spectra of complexes 1a−3a exhibit three absorption
bands for the terminal CO ligands of each complex in the
regions of 2079−2076, 2037−2033 and 1991−1986 cm−1,
which are in good agreement with the corresponding
naphthalene monoimide containing complexes reported in
the literature.17 Additionally, these wavenumbers indicate that
the substituent at the imide position does not strongly alter the
1
electron donating ability of compounds 1−3. The H NMR
spectra of complexes 1a−3a show two signals in the range of
8.65−8.56 and 8.41−8.35 ppm for the protons in ortho-
positions of the perylene backbone. Furthermore, the spectrum
of 1a also exhibits a triplet signal at 7.53 ppm and a doublet
signal at 7.36 ppm for the protons of the phenyl ring at the
imide position as well as the signals of the isopropyl protons
are shown as septet at 2.73 ppm and a doublet of doublet at
1.14 ppm, which are assigned to the (−CH) and (−CH3)
moieties, respectively.
On the other hand, the spectra of complexes 2a and 3a show
broad signals for the (−NCH2) and (−NCH) moieties at 4.19
and 5.15 ppm, respectively. The signals of the alkyl chain
protons appeared in the range of 2.22−0.83 ppm for 2a and 3a
B
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Scheme 1. Attempts to Prepare the Diiron Complexes 1a−3a
Figure 3. Molecular structure (50% probability) of complex 2a. Hydrogen atoms are omitted for clarity.
complexes. The 13C{1H} NMR spectra of complexes 1a−3a
show singlet at 207.6 for 1a and 206.9 ppm for 2a and 3a,
which are assigned to the terminal carbonyl carbon atoms of
the iron cores. The signals of the other carbon atoms in
complexes 1a−3a were also detected (see the Experimental
Section).
suitable single crystals for X-ray diffraction studies. Figure 3
depicts the molecular structure of complex 2a with ellipsoids
drawn at the 50% probability level. Two crystallographically
independent molecules in the unit cell of complex 2a were
determined, only one of them is shown in Figure 3.
The solid-state structure of complex 2a revealed the typical
butterfly architecture of [Fe2S2] cluster. The geometry around
each iron atom can be best described as a distorted
Molecular Structure. Fortunately, the diffusion of hexane
into a CH2Cl2 solution of complex 2a at 20 °C afforded
C
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octahedron, wherein the central atom is Fe surrounded by
three terminal CO ligands in a facial fashion as well as two
chalcogen atoms that bridge both iron centers. The Fe−Fe
bond length in 2a (2.4815 Å, average of the two independent
molecules) is slightly shorter than that in the analogous
naphthalene-containing complexes.8a−d,17−19 The average Fe-
CO bond length in 2a (1.7923 Å, average of the two
independent molecules) is comparable to those observed in
the corresponding naphthalene monoimide analogous.17−19 It
is notable that the average Fe−S (2.2410 Å, average of the two
independent molecules) bond lengths are comparable to those
of naphthalene containing complexes observed in the literatu-
re.8a−d,17−19 Additionally, the torsion angle τ formed from the
intersection between OCap−Fe1−Fe2 and OCap−Fe2−Fe1 of 2a
is 14.88°. The planarity of the perylene backbone was also
distorted by about 31.21° due to the steric hindrance of the
chlorine atoms.
Electrochemical Investigation. Cyclic voltammetry
(CV) was employed to understand the influence of the PMI-
linkers on the redox properties of complexes 1a−3a.
Furthermore, we made a comparison with the reduction
potentials of complexes 1a−3a and the reported reduction
potentials of its analogues, ([Fe2(CO)6{μ-pdt}],
[Fe2 (CO)6 {μ-bdt}], [Fe2 (CO)6 {μ-naphth}] and
[Fe2(CO)6{μ-NMI-R}] (NMI = naphthalene monoimide
dithiolate) (R is the substituent at the monoimide position,
where R = n-C8H17 group)), as shown in Table 1.8a,17 The CV
Furthermore, the cyclic voltammogram of 2a displays an
oxidation event (Epa = −0.55 V) in its return sweep scan in
contrast to complexes 1a and 2a. This oxidation event
vanished by reversing the forward scan of 2a after the first
reduction event and appears again when switching the scan
after the second reduction event as shown in Figure 4b. Such
behavior indicates that there is a chemical decomposition of
the product of the second reduced species of 2a and therefore,
the reduction event that appears at Epc = −1.58 V might
indicate the occurrence of a follow-up reaction.27 The number
of electrons transferred in the first reductions of complexes
1a−3a were determined from plots of the current function (Ip/
c·ν1/2 = (2.69 × 105)·A·D1/2·n3/2, where Ip = peak current, c =
complex concentration, ν = scan rate, A = electrode area, D =
diffusion coefficient and n = number of transferred electron) vs
the scan rates (ν) (Figure S1, Supporting Information), which
show the expected invariance for a process involving the
transfer of one electron.28−31 In general, when the reduction
process does not have any chemical route (simple E
mechanism (E = electron transfer), n = 1), the current
function of this reduction process should remain constant at all
scan rates since (2.69 × 105·A·D1/2·n3/2) has fixed value. These
reductions are being tentatively assigned to the FeI−FeI →
FeIFe0 couple, while the second reductions likely correspond
to the FeIFe0 → Fe0Fe0 couple similar to their analogues
reported in the literature.8a−d,17−19 Additionally, the stability of
complexes 1a−3a is slightly reduced under electrochemical
conditions when the scan was repeated up to 3 times at 0.2 V/s
(Figure. S2, Supporting Information). The first reduction
values of complexes 1a−3a are shifted to more positive value
by 330−900 mV compared to its analogues in Table 1. This
behavior reflects the strong electron-withdrawing character of
the PMI-linkers among these reported linkers. In addition, the
rigid nature of the perylene enhances the chemical stability of
the reduced species, which does not allow the formation of the
dianionic dimer species like the case in [Fe2(CO)6{μ-pdt}]
complex.8a This could be explained due to the delocalization of
the negative charge of the reduced species onto the PMI
backbone similar to the related [Fe2(CO)6{μ-bdt}] com-
plex.14,16,29a,32 Upon initiating the electrochemical scan in the
positive direction of complexes 1a−3a, (Figure S3, Supporting
Information) an irreversible oxidation peak is observed for
each complex (Table 1) which could be assigned to the one-
electron oxidation process of FeIFeI → FeIFeII as previously
reported for various diiron complexes.8c,17,33
Electrocatalysis. The catalytic behavior of complexes 1a−
3a was investigated by cyclic voltammetry in the presence of
various amounts of AcOH (0−10 mM), as illustrated in Figure
5. The presence of two equiv of AcOH in the solutions of
complexes 1a−3a revealed that none of the complexes showed
any response toward the acid at the first reduction events of
complexes 1a−3a, while the second reduction events of
complexes 1a−3a show small shifts (∼10−30 mV) to less
negative potentials which is a typical observation when
protonation of a dianionic species takes place.7d,34 However,
when the acid concentration was increased, the current of this
process remained constant. On the other hand, a new
reduction wave that did not have a counterpart in the
voltammetry of complexes 1a−3a come out near ∼ −1.97 V
when the negative-going scan was expanded to more negative
values. The current of this reduction waves increases in
response to the systematic increase in the acid concentration.
Indeed, the current of the direct reduction of AcOH in
Table 1. Summary of the Redox Potentials (vs. Fc+/Fc) of
Complexes 1a−3a Reduced in 0.1 M CH2Cl2-[n-Bu4N][BF4]
Solution at Scan Rate of 0.2 V/s and Its Analogues under
Identical Conditions
Ered1 (V) FeIFeI → Ered2 (V) FeIFe0 →
FeIFe0 Fe0Fe0
Eox
(V)
complex
[Fe2(CO)6{μ-pdt}]8a
[Fe2(CO)6{μ-bdt}]8a
−1.93
a
−1.58
(E1/2 = −1.47)
−1.76
[Fe2(CO)6{μ-
−2.00
naphth}]8a
(E1/2 = −1.67)
−1.34
[Fe2(CO)6{μ-NMI-
−1.68
C8H17}]17
(E1/2 = −1.31)
−0.99
(E1/2 = −0.96)
−1.01
(E1/2 = −0.99)
−1.04
(E1/2 = −1.65)
−1.23
(E1/2 = −1.19)
−1.24
(E1/2 = −1.21)
−1.25
1a
2a
3a
0.98
0.97
0.99
(E1/2 = −1.01)
(E1/2 = −1.22)
a
Two-electron reduction.
experiments of 1a−3a were performed in 0.1 M CH2Cl2-[n-
Bu4N][BF4] solution at scan rate of 0.2 V/s. Measurements
were recorded with ferrocene as an internal reference and all
potentials herein are quoted with respect to Fc+/Fc couple.
The cyclic voltammograms of complexes 1a−3a are shown in
Figure 4.
Complexes 1a and 3a show the occurrence of two quasi-
reversible reduction processes (E1/2 = −0.96, −1.19 V for 1a
and −1.01, −1.22 V for 3a, respectively), whereas complex 2a
shows two quasi-reversible reduction processes (E1/2 = −0.99
and −1.21 V, respectively) and additional reduction event at
more negative potential (Epc = −1.58 V) (Figure 4).
D
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Figure 4. Cyclic voltammetry of (a) 1.2 mM complex 1a, (b) 1.0 mM complex 2a and (c) 0.9 mM complex 3a in CH2Cl2-[n-Bu4N][BF4] (0.1 M)
solution at 0.2 V/s scan rate. The arrows indicate the scan direction. The potentials E are given in V and referenced to the Fc+/Fc couple.
Figure 5. Cyclic voltammetry of (a) 1.2 mM complex 1a, (b) 1.0 mM complex 2a and (c) 0.9 mM complex 3a in CH2Cl2-[n-Bu4N][BF4] (0.1 M)
solution at 0.2 V/s scan rate in the presence of various concentrations of AcOH. The arrows indicate the scan direction. The potentials E are given
in V and referenced to the Fc+/Fc couple.
1
CH2Cl2-[n-Bu4N][BF4] in the absence of complexes 1a−3a
makes a negligible influence on the response at potentials more
positive than ∼ −2.00 V and contributes less than 10% of the
current at ∼ −2.20 V.35 This indicates that the increase in the
current of the reduction wave at ∼ −1.97 V of complexes 1a−
3a with increasing AcOH concentration is due to an
electrocatalytic process for the proton reduction to H2. One
property of a catalyst that describes its performance is the
catalytic overpotential, which is defined in the current case as
the difference between the potential at half the catalytic peak
current (Ecat/2) and the standard reduction potential of the
acid.8e,36 A low overpotential points to an effective catalyst,
which means that the catalyst operates at a potential that is
close to the standard reduction potential of the acid. Because
the standard reduction potentials of acids in CH2Cl2 are
unknown, we use the values of Ecat/2 for comparison. As a
result, the catalytic potential of complexes 1a−3a accomplish
were fully characterized by use of H, 13C{1H} NMR and IR
spectroscopy, mass spectrometry, elemental analysis, and X-ray
structure determination of 2a. Moreover, we also report how
the physical, electrochemical, and electrocatalytic features are
influenced by the presence of the perylene-linker and compare
it with the previously reported analogues. Overall, the
reduction potentials of complexes 1a−3a are shifted to less
negative values compared to its analogues described in Table 1.
This shift reflects the strong electron-withdrawing character of
the perylene linkers among these reported complexes. In
addition, the rigid nature of the rylene core enhanced the
chemical stability of the reduced species. Future work in this
area will focus on optimization of the backbone of the
perylene-linker of complexes 1a−3a at the bay-positions and/
or incorporation of ligand substitutions at the iron center.
Indeed, push−pull substitution of rylenes can be used to
realize high visible and near-IR light absorption, leading to
spatial charge polarization in the excited state to enable
electron transfer and limit undesired recombination. In
addition, substitution of the dyes at peripheral positions
enables extensive tuning of their redox properties. In addition,
this also allows the incorporation of functional groups for
covalent linkage to soft matter matrices. We hope that these
modifications will enable their first application as photo-
sensitizers for hydrogen evolution reaction catalysts.
catalysis with comparable overpotentials reflected by Ecat/2
−1.89, −1.87, and −1.90 V, respectively.
=
CONCLUSION
■
This study elucidates the use of perylene monoimide of peri-
substituted dibromo or disulfides compounds as proligands to
react with either [Fe2(CO)6{μ-S2}] complex or Fe3(CO)12
under different conditions. In this work, we report the first
[FeFe]-hydrogenase synthetic mimics 1a−3a complexes that
contain the perylene monoimide chromophore. The complexes
E
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collected always from the third fraction and then the solvent was
removed in vacuo. The products were obtained as a red powder for
complexes 1a−3a.
EXPERIMENTAL SECTION
■
Materials and Techniques. The reactions of complexes 1a−3a
and compounds 1b−3b were performed using standard Schlenk and
vacuum-line techniques under an inert gas (nitrogen) atmosphere.
The 1H, 13C{1H}, NMR spectra were recorded with a Bruker Avance
400 or 300 MHz spectrometer. Chemical shifts are given in parts per
million with references to internal standard SiMe4. The mass spectra
were recorded with a Finnigan MAT SSQ 710 instrument. The IR
spectra were recorded with a Bruker Equinox 55 spectrometer
equipped with an ATR unit. Elemental analysis was performed with a
Leco CHNS-932 apparatus. TLC was performed by using Merck TLC
aluminum sheets (Silica gel 60 F254). Solvents from Fisher Scientific
and other chemicals from Acros and Aldrich were used without
further purification. All solvents were dried and distilled prior to use
according to standard methods. Compounds 1−3 were synthesized
(see the Supporting Information) according to the known literature
methods.23,24 The [Fe2(CO)6{μ-S2}] complex was synthesized
following the modified procedure by Stanley et al.26
Electrochemistry. Corrections for the iR drop were performed for
all experiments. Cyclic voltammetry measurements were conducted
using the three-electrode technique (glassy carbon disk (diameter d =
1.6 mm) as the working electrode, Ag/Ag+ in MeCN as the reference
electrode, and Pt wire as the counter electrode) with a Reference 600
potentiostat (Gamry Instruments). All of the experiments were
performed in CH2Cl2 solution containing 0.1 M [n-Bu4N][BF4] at
room temperature; the concentration of the complexes was 0.9−1.2
mM. Solutions were deaerated by purging with N2 for 5−10 min, and
a blanket of N2 was maintained over the solutions during the
measurements. The vitreous carbon disk was polished on a felt tissue
with alumina before each measurement. All of the potential values
reported in this paper are referenced to the potential of the
ferrocenium/ferrocene (Fc+/Fc) couple.
Method B. A solution of Fe3(CO)12 (0.20 mmol) and compounds
1b−3b, respectively, (0.20 mmol) in THF (30 mL) was heated at
reflux for 3 h under N2. The green solution turned to deep red and the
solvent was removed under reduced pressure. The residue was
purified by column chromatography using hexane/CH2Cl2 (1:2) for
1a and 3a while for 2a hexane/toluene (1:1) as the eluent. The
complexes were collected always from the third fraction and then the
solvent was removed in vacuo. The products were obtained as a red
powder for complexes 1a−3a.
Complex 1a. (14% yield, red powder); Anal. Calcd for
C40H21Cl4Fe2NO8S2: C, 49.98; H, 2.20; N, 1.46; S, 6.67. Found: C,
49.67; H, 2.09; N, 1.31; S, 6.42. FT-IR (solid state, ATR, cm−1) νCO
1
2079 (s), 2033 (s), 1986 (m); νCO 1703 (s), 1663 (s). H NMR
(400 MHz, CD2Cl2, ppm) δ = 8.65 (s, 2H), 8.41 (s, 2H), 7.53 (t, 1H,
3JHH = 7.8 Hz), 7.36 (d, 2H, 3JHH = 7.8 Hz), 2.73 (sep, 2H, 3JHH = 6.8
Hz), 1.14 (dd, 12H, JHH = 6.8, 4.9 Hz). 13C{1H} NMR (100 MHz,
CD2Cl2, ppm) δ = 207.6 (CO), 163.3 (CO), 146.6, 135.0, 134.7,
134.5, 134.1, 133.9, 131.1, 130.7, 130.3, 129.8, 126.6, 124.7, 124.5,
123.7, 122.8, 29.7, 24.3. DEI-MS m/z = 960 [M]+.
Complex 2a. (12% yield, red powder); Anal. Calcd for
C36H21Cl4Fe2NO8S2: C, 47.35; H, 2.32; N, 1.53; S, 7.02. Found: C,
47.03; H, 2.18; N, 1.37; S, 6.78. FT-IR (solid state, ATR, cm−1) νCO
1
2076 (s), 2035 (s), 1988 (m); νCO 1704 (s), 1661 (s). H NMR
(400 MHz, CD2Cl2, ppm) δ = 8.57 (s, 2H), 8.38 (s, 2H), 4.19 (bs,
2H), 1.73 (bs, 4H), 1.26 (bs, 8H), 0.87 (bs, 3H). 13C{1H} NMR (100
MHz, CD2Cl2, ppm) δ = 206.9 (CO), 162.5 (CO), 134.4, 134.1,
133.8, 133.5, 132.8, 129.9, 129.7, 129.2, 126.2, 123.4, 123.1, 122.6,
40.8, 31.9, 29.8, 29.4, 29.3, 28.1, 27.2, 22.8. DEI-MS m/z = 912 [M]+.
Complex 3a. (15% yield, red powder); Anal. Calcd for
C43H35Cl4Fe2NO8S2: C, 51.07; H, 3.49; N, 1.38; S, 6.34. Found: C,
50.92; H, 3.30; N, 1.25; S, 6.01. FT-IR (solid state, ATR, cm−1) νCO
Crystal Structure Determination. The intensity data were
collected on a Nonius KappaCCD diffractometer, using graphite-
monochromated Mo K radiation. Data were corrected for Lorentz and
polarization effects; absorption was taken into account on a
semiempirical basis using multiple-scans.37−39 The structure was
solved by direct methods (SHELXS)40 and refined by full-matrix
1
2076 (s), 2037 (s), 1991 (m); νCO 1700 (s), 1662 (s). H NMR
(400 MHz, CDCl3, ppm) δ = 8.56 (s, 2H), 8.35 (s, 2H), 5.15 (bs,
1H), 2.22 (bs, 2H), 1.85 (bs, 2H), 1.22 (s, 20H) 0.83 (s, 6H).
13C{1H} NMR (100 MHz, CD2Cl2, ppm) δ = 206.9 (CO), 134.5,
134.2, 133.9, 133.7, 129.8, 129.6, 129.1, 126.3, 123.5, 123.1, 55.3,
32.4, 31.9, 29.9, 29.6, 29.3, 27.1, 22.8, 14.2. DEI-MS m/z = 1010
[M]+.
least-squares techniques against Fo (SHELXL-97).40 All other
2
hydrogen atoms were located by difference Fourier synthesis and
refined isotropically. All non-hydrogen atoms were refined anisotropi-
cally.40 The crystal of 2a was a partial-merohedral twin. The twin law
was determined by PLATON41 to (1.001−0.004−0.003/0.000−1.000
0.000/0.500−0.001−1.001). The contribution of the main compo-
nent was refined to 0.800(3). MERCURY was used for structure
representations.42
General Procedure for the Preparation of Compounds 1b−
3b. A mixture of compounds 1−3, respectively, (0.3 mmol) and
elemental sulfur (1.5 mmol) in NMP (10 mL) was stirred at 160 °C
for 8−10 h. The mixture was allowed to cool to room temperature
and poured into 20 mL of 1.0 M hydrochloric acid solution. The
precipitate was filtered and then washed with methanol. The crude
products were purified by column chromatography using CH2Cl2 as
eluent on silica gel or by repetitive precipitation from CH2Cl2 solution
by methanol.
Crystal Data for 2a. C36H21Cl4Fe2NO8S2, Mr = 913.16 g mol−1,
red-brown prism, size 0.112 × 0.064 × 0.044 mm3, triclinic, space
̅
group P1, a = 10.1835(13), b = 15.4993(13), c = 22.6207(18) Å, α =
84.799(4), β = 83.333(5), γ = 89.828(8)°, V = 3531.5(6) Å3, T =
−140 °C, Z = 4, ρcalcd. = 1.717 gcm−3, μ (Mo Kα) = 12.98 cm−1,
multiscan, tmin = 0.4891, tmax = 0.7457, F(000) = 1840, 34962
reflections in h(−13/13), k(−20/20), l(−29/29), measured in the
range 1.53° ≤ Θ ≤ 25.68°, completeness Θmax = 96.3%, 12923
Compound 1b. (93% yield, dark-blue); Anal. Calcd for
C34H21Cl4NO2S2: C, 59.93; H, 3.11; N, 2.06; S, 9.41. Found: C,
59.63; H, 2.80; N, 1.93; S, 9.12. 1H NMR (300 MHz, CDCl3, ppm) δ
3
= 8.67 (s, 2H), 7.57 (s, 2H), 7.50 (m, 1H), 7.35 (d, 2H, JHH = 7.0
Hz), 2.73 (m, 2H), 1.18 (s, 12H). 13C{1H} NMR (75 MHz, CDCl3,
ppm) δ = 163.1 (CO), 148.1, 145.3, 137.5, 133,2, 132.0, 130.1,
129.9, 124.3, 120.6, 120.3, 119.6, 29.4, 24.2. DEI-MS m/z = 681
[M]+.
independent reflections, Rint = 0.0576, 9596 reflections with Fo
>
4σ(Fo), 958 parameters, 0 restraints, R1 = 0.0971, wR2 = 0.2459,
obs
obs
R1 = 0.1282, wR2 = 0.2670, GOF = 1.061, largest difference peak
all
all
and hole: 1.388/−1.461e Å−3.
Compound 2b. (94% yield, dark-blue); Anal. Calcd for
C30H21Cl4NO2S2: C, 56.89; H, 3.34; N, 2.21; S, 10.12. Found: C,
56.78; H, 3.30; N, 2.25; S,10.19. 1H NMR (300 MHz, CDCl3, ppm) δ
= 8.59 (s, 2H), 7.53 (s, 2H), 4.20 (m, 2H), 1.73 (m, 2H), 1.33 (m,
10H), 0.86 (m, 3H). 13C{1H} NMR (75 MHz, CDCl3, ppm) δ =
168.9 (CO), 147.7, 137.2, 134.3, 132,9, 132.6, 131.7, 131.1, 129.6,
123.7, 120.8, 120.5, 120.1, 119.4, 40.8, 31.8, 29.3 28.1, 27.1, 22.6,
14.1. DEI-MS m/z = 633 [M]+.
Compound 3b. (91% yield, dark-blue); Anal. Calcd for
C37H35Cl4NO2S2: C, 60.74; H, 4.82; N, 1.91; S, 8.76. Found: C,
60.49; H, 4.74; N, 1.89; S, 8.42. 1H NMR (300 MHz, CDCl3, ppm) δ
= 8.57 (m, 2H), 7.52 (s, 2H), 5.17 (dt, 1H, 3JHH = 15.2, 4.9 Hz), 2.23
General Procedure for the Preparation of Complexes 1a−
3a. Method A. A red solution of [Fe2(CO)6{μ-S2}] (0.14 mmol) in
THF (10 mL) was cooled to −78 °C and treated dropwise with
LiEt3BH (0.27 mL, 0.27 mmol, 1.0 M in THF) to give a dark-green
solution. After stirring the solution for 20 min at −78 °C, compounds
1−3 (0.14 mmol) in CH2Cl2 (15 mL) was added. The mixture was
stirred for 18 h while slowly warming up to room temperature, giving
rise to a dark-red solution. Solvent removal was performed under N2
by using a vacuum transfer line. The red residue was then purified by
column chromatography using hexane/CH2Cl2 (1:2) for 1a and 3a
while for 2a hexane/toluene (1:1) as the eluent. The complexes were
F
DOI: 10.1021/acs.organomet.8b00450
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(dd, 2H, 3JHH = 22.8, 9.7 Hz), 1.82 (m, 2H), 1.24 (m, 20H), 0.82 (t,
6H, 3JHH = 6.4 Hz). 13C{1H} NMR (75 MHz, CDCl3, ppm) δ = 160.4
(CO), 147.8, 137.2, 134.3, 133.3, 133.2, 133.1, 132.5, 131.9, 131.3,
129.5, 124.0, 120.3, 119.5, 55.0, 35.5, 32.4, 32.0, 29.7, 29.4, 27.1, 22.8,
14.2. DEI-MS m/z = 520 [M]+.
Evidence for a Nitrogen in the Dithiol Bridge. Phys. Chem. Chem.
Phys. 2009, 11, 6592−6599. (d) Berggren, G.; Adamska, A.;
Lambertz, C.; Simmons, T. R.; Esselborn, J.; Atta, M.; Gambarelli,
S.; Mouesca, J. M.; Reijerse, E.; Lubitz, W.; Happe, T.; Artero, V.;
Fontecave, M. Biomimetic Assembly and Activation of [FeFe]-
Hydrogenases. Nature 2013, 499, 66−69.
(7) (a) Li, Y.; Rauchfuss, T. B. Synthesis of Diiron(I) Dithiolato
Carbonyl Complexes. Chem. Rev. 2016, 116, 7043−7077 and
references cited therein . (b) Abul-Futouh, H.; Almazahreh, L. R.;
Sakamoto, T.; Stessman, N. Y. T.; Lichtenberger, D. L.; Glass, R. S.;
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.8b00450.
■
S
̈
Gorls, H.; El-khateeb, M.; Schollhammer, P.; Mloston, G.; Weigand,
W. [FeFe]-Hydrogenase H-Cluster Mimics with Unique Planar μ-
(SCH2)2ER2 Linkers (E = Ge and Sn). Chem. - Eur. J. 2017, 23, 346−
359. (c) Li, P.; Amirjalayer, S.; Hartl, F.; Lutz, M.; Bruin, B.; Becker,
R.; Woutersen, S.; Reek, J. N. H. Direct Probing of Photoinduced
Electron Transfer in a Self-Assembled Biomimetic [2Fe2S]-Hydro-
genase Complex Using Ultrafast Vibrational Spectroscopy. Inorg.
Chem. 2014, 53, 5373−5383. (d) Abul-Futouh, H.; El-khateeb, M.;
Supporting methods and figures (PDF)
Accession Codes
CCDC 1850264 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
̈
Gorls, H.; Asali, K. J.; Weigand, W. Selenium Makes the Difference:
Protonation of [FeFe]-Hydrogenase Mimics with Diselenolato
Ligands. Dalton Trans 2017, 46, 2937−2947.
(8) (a) Wright, R. J.; Lim, C.; Tilley, T. D. Diiron Proton Reduction
Catalysts Possessing Electron-Rich and Electron-Poor Naphthalene-
1,8-dithiolate Ligands. Chem. - Eur. J. 2009, 15, 8518−8525. (b) Qian,
G.; Zhong, W.; Wei, Z.; Wang, H.; Xiao, Z.; Long, L.; Liu, X. Diiron
Hexacarbonyl Complexes Bearing Naphthalene-1,8-dithiolate Bridge
Moiety as Mimics of the Sub-unit of [FeFe]-Hydrogenase: Synthesis,
Characterisation and Electrochemical Investigations. New J. Chem.
2015, 39, 9752−9760. (c) Figliola, C.; Male, L.; Horton, P. N.; Pitak,
M. B.; Coles, S. J.; Horswell, S. L.; Grainger, R. S. [FeFe]-
Hydrogenase Synthetic Mimics Based on Peri-Substituted Dichalco-
genides. Organometallics 2014, 33, 4449−4460. (d) Figliola, C.; Male,
L.; Horswell, S. L.; Grainger, R. S. N-Derivatives of peri-Substituted
Dichalcogenide [FeFe]-Hydrogenase Mimics: Towards Photocata-
lytic Dyads for Hydrogen Production. Eur. J. Inorg. Chem. 2015, 2015,
3146−3156. (e) Abul-Futouh, H.; Almazahreh, L. R.; Harb, M. K.;
AUTHOR INFORMATION
Corresponding Author
*E-mail: kalina.peneva@uni-jena.de.
ORCID
Hassan Abul-Futouh: 0000-0003-2419-9782
Artem Skabeev: 0000-0003-4014-1054
Kalina Peneva: 0000-0001-5578-3266
■
Author Contributions
§H.A.-F. and A.S. contributed equally
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
̈
Gorls, H.; El-khateeb, M.; Weigand, W. [FeFe]-Hydrogenase H-
■
Cluster Mimics with Various − S(CH2)nS− Linker Lengths (n = 2−
8): A Systematic Study. Inorg. Chem. 2017, 56, 10437−10451.
(9) (a) Zaffaroni, R.; Rauchfuss, T. B.; Gray, D. L.; De Goia, L.;
Zampelli, G. Terminal vs Bridging Hydrides of Diiron Dithiolates:
Protonation of Fe2(dithiolate)(CO)2(PMe3)4. J. Am. Chem. Soc. 2012,
134, 19260−19269. (b) Donovan, E. S.; McCormick, J. J.; Nichol, G.
S.; Felton, G. A. N. Cyclic Voltammetric Studies of Chlorine-
Substituted Diiron Benzenedithiolato Hexacarbonyl Electrocatalysts
Inspired by the [FeFe]-Hydrogenase Active Site. Organometallics
2012, 31, 8067−8070. (c) Harb, M. K.; Alshurafa, H.; El-khateeb, M.;
This work was supported by the DFG-funded Collaborative
Research Centre Catalight (SFB TRR234, Project A02 and
A03).
REFERENCES
■
(1) Cook, T. R.; Dogutan, D. K.; Reece, S. Y.; Surendranath, Y.;
Teets, T. S.; Nocera, D. G. Solar Energy Supply and Storage for the
Legacy and Nonlegacy Worlds. Chem. Rev. 2010, 110, 6474−6502.
(2) Frey, M. Hydrogenases: Hydrogen-Activating Enzymes.
ChemBioChem 2002, 3, 153−160.
̈
Al-Zuheiri, A.; Gorls, H.; Abul-Futouh, H.; Weigand, W. [FeFe]-
(3) Adams, M. W. The Structure and Mechanism of Iron-
hydrogenases. Biochim. Biophys. Acta, Bioenerg. 1990, 1020, 115−145.
(4) Vignais, P. M.; Billoud, B.; Meyer, J. Classification and
phylogeny of hydrogenases. FEMS Microbiol. Rev. 2001, 25, 455−501.
(5) (a) Cammack, R. Bioinorganic Chemistry: Hydrogenase
Sophistication. Nature 1999, 397, 214−215. (b) Hatchikian, E. C.;
Forget, N.; Fernandez, V. M.; Williams, R.; Cammack, R. Further
Characterization of the [Fe]-Hydrogenase from Desulfovibrio
Desulfuricans ATCC 7757. Eur. J. Biochem. 1992, 209, 357−365.
Hydrogenase Models Containig Long Diselenolato Linkers. Chemis-
trySelect 2018, 3, 8867−8873.
(10) (a) Yu, Z.; Wang, M.; Li, P.; Dong, W.; Wang, F.; Sun, L.
Diiron Dithiolate Complexes Containing Intra-Ligand NH ··· S
Hydrogen Bonds: [FeFe] Hydrogenase Active Site Models for the
Electrochemical Proton Reduction of HOAc with Low Overpotential.
Dalton Trans 2008, 2400−2406. (b) Tooley, C. A.; Pazicni, S.; Berda,
E. B. Toward a Tunable Snthetic [FeFe] Hydrogenase Mimic: Single-
Chain Nanoparticles Functionalized with a Single Diiron Cluster.
Polym. Chem. 2015, 6, 7646−7651.
(c) Lubitz, W.; Ogata, H.; Rudiger, O.; Reijerse, E. Hydrogenases.
̈
Chem. Rev. 2014, 114, 4081−4148.
(11) Borg, S. J.; Behrsing, T.; Best, S. P.; Razavet, M.; Liu, X.;
Pickett, C. J. Electron Transfer at a Dithiolate-Bridged Diiron
Assembly: Electrocatalytic Hydrogen Evolution. J. Am. Chem. Soc.
2004, 126, 16988−16999.
(12) Borg, S. J.; Bondin, M. I.; Razavet, M.; Liu, X.; Pickett, C. J.
Electrocatalytic Proton Reduction by Dithiolate-bridged Diiron
Carbonyl Complexes: A Connection to the H-Cluster? Biochem.
Soc. Trans. 2005, 33, 3−6.
(13) Aguirre de Carcer, I.; DiPasquale, A.; Rheingold, A. L.;
Heinekey, D. M. Active-Site Models for Iron Hydrogenases:
(6) (a) Peters, J. W.; Lanzilotta, W. N.; Lemon, B. J.; Seefeldt, L. C.
X-ray Crystal Structure of the Fe-only Hydrogenase (CpI) from
Clostridium Pasteurianum to 1.8 Angstrom Resolution. Science 1998,
282, 1853−1858. (b) Nicolet, Y.; de Lacey, A. L.; Vernede, X.;
Fernandez, V. M.; Hatchikian, E. C.; Fontecilla-Camps, J. C.
Crystallographic and FTIR Spectroscopic Evidence of Changes in
Fe Coordination Upon Reduction of the Active Site of the Fe-Only
Hydrogenase from Desulfovibrio desulfuricans. J. Am. Chem. Soc. 2001,
123, 1596−1601. (c) Silakov, A.; Wenk, B.; Reijerse, E.; Lubitz, W. 14
N HYSCORE Investigation of the H-Cluster of [FeFe] Hydrogenase:
G
DOI: 10.1021/acs.organomet.8b00450
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Reduction Chemistry of Dinuclear Iron Complexes. Inorg. Chem.
2006, 45, 8000−8002.
(29) (a) Gloaguen, F.; Morvan, D.; Capon, J.-F.; Schollhammer, P.;
Talarmin, J. Electrochemical Proton Reduction at Mild Potentials by
Monosubstituted Diiron Organometallic Complexes Bearing a
Benzenedithiolate Bridge. J. Electroanal. Chem. 2007, 603, 15−20.
(b) Schwartz, L.; Singh, P. S.; Eriksson, L.; Lomoth, R.; Ott, S.
Tuning the Electronic properties of Fe2(μ-arenedithiolate)-
(CO)6−n(PMe3)n (n = 0, 2) Complexes Related to the [Fe−Fe]-
Hydrogenase Active Site. C. R. Chim. 2008, 11, 875−889. (c) Abul-
(14) Capon, J.-F.; Gloaguen, F.; Schollhammer, P.; Talarmin, J.
Electrochemical Proton Reduction by Thiolate-Bridged Hexacarbo-
nyldiiron Clusters. J. Electro-anal. Chem. 2004, 566, 241−247.
(15) Capon, J.-F.; Gloaguen, F.; Schollhammer, P.; Talarmin, J.
Activation of Proton by The Two-Electron Reduction of a Diiron
Organometallic Complex. J. Electro-anal. Chem. 2006, 595, 47−52.
(16) Felton, G. A. N.; Vannucci, A. K.; Chen, J.; Lockett, L. T.;
Okumura, N.; Petro, B. J.; Zakai, U. I.; Evans, D. H.; Glass, R. S.;
Lichtenberger, D. L. Hydrogen Generation from Weak Acids:
Electrochemical and Computational Studies of a Diiron Hydrogenase
Mimic. J. Am. Chem. Soc. 2007, 129, 12521−12530.
̈
Futouh, H.; Gorls, H.; Weigand, W. Synthesis and Electrochemical
Investigation of Mono- and Di-phosphite Substituted [FeFe]-
Hydrogenase H-Cluster Mimics. Z. Anorg. Allg. Chem. 2017, 643,
1615−1620. (d) Chen, J.; Vannucci, A. K.; Mebi, C. A.; Okumura, N.;
Borowski, S. C.; Swenson, M.; Lockett, L. T.; Evans, D. H.; Glass, R.
S.; Lichtenberger, D. L. Synthesis of Diiron Hydrogenase Mimics
Bearing Hydroquinone and Related Ligands. Electrochemical and
Computational Studies of the Mechanism of Hydrogen Production
and the Role of O−H···S Hydrogen Bonding. Organometallics 2010,
29, 5330−5340.
(30) (a) Zhao, J.; Wei, Z.; Zeng, X.; Liu, X. Three Diiron Complexes
Bearing an Aromatic Ring as Mimics of the Diiron Subunit of [FeFe]-
Hydrogenase: Synthesis, Electron Transfer and Coupled Chemical
Reactions. Dalton Trans 2012, 41, 11125−11133. (b) Best, S. P.;
Borg, S. J.; White, J. M.; Razavet, M.; Pickett, C. J. On the Structure of
a Proposed Mixed-Valent Analogue of the Diiron Subsite of [FeFe]-
Hydrogenase. Chem. Commun. 2007, 4348−4350.
(31) Gloaguen, F.; Rauchfuss, T. B. Small Molecule Mimics of
Hydrogenases: Hydrides and Redox. Chem. Soc. Rev. 2009, 38, 100−
108.
(32) Capon, J.-F.; Gloaguen, F.; Schollhammer, P.; Talarmin, J.
Activation of Proton by the Two-Electron Reduction of a Di-iron
Organometallic Complex. J. Electro. anal. Chem. 2006, 595, 47−52.
(33) Gao, S.; Fan, J.; Sun, S.; Peng, X.; Zhao, X.; Hou, J. Selenium-
Bridged Diiron Hexacarbonyl Complexes as Biomimetic Models for
the Active Site of Fe−Fe Hydrogenases. Dalton Trans 2008, 2128−
2135.
(34) Surawatanawong, P.; Tye, J. W.; Darensbourg, M. Y.; Hall, M.
B. Mechanism of Electrocatalytic Hydrogen Production by a Di-iron
Model of Iron−Iron Hydrogenase: A Density Functional Theory
Study of Proton Dissociation Constants and Electrode Reduction
Potentials. Dalton Trans 2010, 39, 3093−3104.
(35) Borg, S. J.; Ibrahim, S. K.; Pickett, C. J.; Best, S. P.
Electrocatalysis of Hydrogen Evolution by Synthetic Diiron Units
Using Weak Acids as the Proton Source: Pathways of Doubtful
Relevance to Enzymic Catalysis by the Diiron Subsite of [FeFe]
Hydrogenase. C. R. Chim. 2008, 11, 852−860.
(17) Abul-Futouh, H.; Zagranyarski, Y.; Muller, C.; Schulz, M.;
̈
̈
̈
Kupfer, S.; Gorls, H.; Elkhateeb, M.; Grafe, S.; Dietzek, B.; Peneva, K.;
Weigand, W. [FeFe]-Hydrogenase H-cluster Mimics Mediated by
Naphthalene Monoimide Derivatives of Peri-Substituted Dichalcoge-
nides. Dalton Trans 2017, 46, 11180−11191.
(18) (a) Samuel, A. P. S.; Co, D. T.; Stern, C. L.; Wasielewski, M. R.
Ultrafast Photodriven Intramolecular Electron Transfer from a Zinc
Porphyrin to a Readily Reduced Diiron Hydrogenase Model
Complex. J. Am. Chem. Soc. 2010, 132, 8813−8815. (b) Poddutoori,
P.; Co, D. T.; Samuel, A. P. S.; Kim, C. H.; Vagnini, M. T.;
Wasielewski, M. R. Photoinitiated Multistep Charge Separation in
Ferrocene−Zinc Porphyrin−Diiron Hydrogenase Model Complex
Triads. Energy Environ. Sci. 2011, 4, 2441−2450.
(19) Li, P.; Amirjalayer, S.; Hartl, F.; Lutz, M.; Bruin, B.; Becker, R.;
Woutersen, S.; Reek, J. N. H. Direct Probing of Photoinduced
Electron Transfer in a Self-Assembled Biomimetic [2Fe2S]-Hydro-
genase Complex Using Ultrafast Vibrational Spectroscopy. Inorg.
Chem. 2014, 53, 5373−5383.
(20) Li, C.; Wonneberger, H. Perylene Imides for Organic
Photovoltaics: Yesterday, Today, and Tomorrow. Adv. Mater. 2012,
24, 613−636.
(21) Weil, T.; Vosch, T.; Hofkens, J.; Peneva, K.; Mullen, K. The
̈
Rylene Colorant FamilyTailored Nanoemitters for Photonics
Research and Applications. Angew. Chem., Int. Ed. 2010, 49, 9068−
9093.
(22) Wurthner, F.; Saha-Moller, C. R.; Fimmel, B.; Ogi, S.;
̈
̈
Leowanawat, P.; Schmidt, D. Perylene Bisimide Dye Assemblies as
Archetype Functional Supramolecular Materials. Chem. Rev. 2016,
116, 962−1052.
́
(23) Kaloyanova, S.; Zagranyarski, Y.; Ritz, S.; Hanulova, M.;
Koynov, K.; Vonderheit, A.; Mullen, K.; Peneva, K. Water-Soluble
̈
(36) Felton, G. A. N.; Mebi, C. A.; Petro, B. J.; Vannucci, A. K.;
Evans, D. H.; Glass, R. S.; Lichtenberger, D. L. Review of
Electrochemical Studies of Complexes Containing the Fe2S2 Core
Characteristic of [FeFe]-Hydrogenases Including Catalysis by These
Complexes of the Reduction of Acids to Form Dihydrogen. J.
Organomet. Chem. 2009, 694, 2681−2699.
NIR-Absorbing Rylene Chromophores for Selective Staining of
Cellular Organelles. J. Am. Chem. Soc. 2016, 138, 2881−2884.
(24) (a) Zagranyarski, Y.; Chen, L.; Zhao, Y.; Wonneberger, H.; Li,
C.; Mu
Acid Dianhydride into Strong Donor−Acceptor Chromophores. Org.
Lett. 2012, 14, 5444−5447. (b) Mahl, M.; Shoyama, K.; Ruhe, J.;
Grande, V.; Wurthner, F. Tetrachlorinated PolycyclicAromatic
̈
llen, K. Facile Transformation of Perylene Tetracarboxylic
̈
(37) COLLECT Data Collection Software; Nonius B.V.: Delft, The
Netherlands, 1998.
̈
Dicarboximides: New Electron-Poor p-Scaffolds and NIR Emitters
by Palladium-Catalyzed Annulation Reaction. Chem. - Eur. J. 2018, 24,
9409.
(38) Otwinowski, Z.; Minor, W. Processing of X-Ray Diffraction
Data Collected in Oscillation Mode. Methods Enzymol. 1997, 276,
307−326.
(39) SADABS, version 2.10; Bruker AXS: Madison, WI, 2002.
(40) Sheldrick, G. M. Crystal Structure Refinement with SHELXL.
Acta Crystallogr., Sect. C: Struct. Chem. 2015, C71, 3−8.
(41) Spek, A. L. A Tool for the Calculation of the Disordered
Solvent Contribution to the Calculated Structure Factors. Acta
Crystallogr., Sect. C: Struct. Chem. 2015, 71, 9−18.
(42) Macrae, C. F.; Edgington, P. R.; McCabe, P.; Pidcock, E.;
Shields, G. P.; Taylor, R.; Towler, M.; van de Streek, J. Mercury:
Visualization and Analysis of Crystal Structures. J. Appl. Crystallogr.
2006, 39, 453−457.
̈
(25) Zagranyarski, Y.; Chen, L.; Jansch, D.; Gessner, T.; Li, C.;
Mullen, K. Toward Perylene Dyes by the Hundsdiecker Reaction.
Org. Lett. 2014, 16, 2814−2817.
̈
(26) Stanley, J. L.; Rauchfuss, T. B.; Wilson, S. R. Studies on the
Condensation Pathway to and Properties of Diiron Azadithiolate
Carbonyls. Organometallics 2007, 26, 1907−1911.
́
(27) Capon, J.-F.; Ezzhaer, S.; Gloaguen, F.; Petillon, F. Y.;
Schollhammer, P.; Talarmin, J.; Davin, T. J.; McGrady, J. E.; Muir, K.
W. Electrochemical and Theoretical Investigations of the Reduction
of [Fe2(CO)5L{μ-SCH2XCH2S}] Complexes Related to [FeFe]
Hydrogenase. New J. Chem. 2007, 31, 2052−2064.
(28) Nicholson, R. S.; Shain, I. Theory of Stationary Electrode
Polarography for a Chemical Reaction Coupled between Two Charge
Transfers. Anal. Chem. 1965, 37, 178−190.
H
DOI: 10.1021/acs.organomet.8b00450
Organometallics XXXX, XXX, XXX−XXX