[FeFe]-hydrogenase H-cluster mimics mediated by mixed (S, Se) and (S, Te) bridging moieties: Insight into molecular structures and electrochemical characteristics

Article abstract of DOI:10.1002/hc.21446

Two synthetic models of the active site of [FeFe]-hydrogenase containing mixed (S, Se) and (S, Te) bridges have been synthesized and characterized. These complexes [Fe₂(CO)₆{μ-S(CH₂)₄E-μ)}] (E?=?Se (1), Te (2))

Full text of DOI:10.1002/hc.21446

Received: 14 August 2018
DOI: 10.1002/hc.21446
Revised: 6 October 2018
|
R E S E A R C H A R T I C L E
[
FeFe]-hydrogenase H-cluster mimics mediated by mixed (S, Se)
and (S, Te) bridging moieties: Insight into molecular structures
and electrochemical characteristics
1
Mohammad El-khateeb2
Helmar Görls3
Hassan Abul-Futouh
Wolfgang Weigand3
|
|
|
1Department of Pharmacy, Al-Zaytoonah
University of Jordan, Amman, Jordan
2Chemistry Department, Jordan University
Abstract
Two synthetic models of the active site of [FeFe]-hydrogenase containing mixed (S,
Se) and (S, Te) bridges have been synthesized and characterized. These complexes
[Fe (CO) {μ-S(CH ) E-μ)}] (E = Se (1), Te (2)) are obtained in moderate yields
of Science and Technology, Irbid, Jordan
3Institute for Inorganic and Analytical
Chemistry, Friedrich Schiller University
Jena, Jena, Germany
2
6
2 4
from the reaction of Fe (CO) with 1,2-thiaselenane or 1,2-thiatellurane. They have
3
12
1
13
1
77
1
been characterized by spectroscopic techniques (IR, H-, C{ H}-, Se{ H}-,
1
25
1
Correspondence
Wolfgang Weigand, Institute for Inorganic
Te{ H}-NMR, and MS) and elemental analysis. The structures of [Fe (CO) {μ-
2
6
S(CH ) Se-μ)}] and [Fe (CO) {μ-S(CH ) Te-μ)}] are determined by X-ray structure
2
4
2
6
2 4
and Analytical Chemistry, Friedrich Schiller
University Jena, Jena, Germany.
Email: wolfgang.weigand@uni-jena.de
and
Mohammad El-khateeb, Chemistry
Department, Jordan University of Science
and Technology, Irbid, Jordan.
Email: kateeb@just.edu.jo
determination and show the expected butterfly geometry. Moreover, the influence of
the mixed chalcogen atoms on the redox properties and the catalytic behavior of 1
and 2 are studied using cyclic voltammetry.
Contract grant sponsor: Office of Naval
Research Global for financial support.
1
|
INTRODUCTION
the past few decades, several diiron dithiolato complexes
that mimic the butterfly [Fe S ] sub-unit of the H-cluster
2
2
[10–28]
In recent years, the production of hydrogen catalyzed by first
row transition metals like iron represents promising substi-
tutes of the commonly used platinum, iridium, or rhenium
have been synthesized and tested as electrocatalysts.
Moreover, these complexes have been modified to contain
heavier chalcogen donor atoms such as selenium or tellurium
[
1]
[29–34]
catalysts. Green algae, such as Chlamydomonas reinhard-
tii, can produce hydrogen using [FeFe]-hydrogenase system
in a very efficient way with turnover frequencies over 10 000
instead of sulfur.
It has been reported that the incor-
poration of such heavier chalcogen atoms into the synthetic
H-cluster mimics of [FeFe]-hydrogenase results in lower
ionization and reorganization energies, which may lead to
[
2–4]
H /s.
The active site of this system contains an organome-
2
[32,35–37]
tallic Fe/S cluster, the so-called H-cluster (Figure 1A), that
faster electron transfers and more active catalysts.
is, responsible for the hydrogen evolution reaction.[
5–9]
Over
In a recent paper, we investigated the influence of the pres-
ence of mixed (S, Se) and (S, Te) ligands in [Fe (CO) {μ-
2
6
[38]
Dedicated to 82nd birthday of Professor Naomichi Furukawa.
Contract grant number: N62909-16-1-2054.
Contract grant sponsor:
S(CH ) E-μ)}] (E = Se, Te) complexes.
As a result, the
2
3
catalytic efficiency for the reduction of protons of these com-
plexes is found to be comparable to each other, with overall
similar overpotentials and catalytic peak currents. Moreover,
Deutscher Akademischer Austauschdienst.
Heteroatom Chemistry. 2018;e21446.
https://doi.org/10.1002/hc.21446
wileyonlinelibrary.com/journal/hc
© 2018 Wiley Periodicals, Inc.
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1 of 8

2
of 8
ABUL-FUTOUH eT AL.
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7
7
1
125
1
Darensbourg and co-workers have reported computational
studies to show the influence of increasing the dithiolato
spacer of [Fe (CO) {μ-(SCH ) (CH ) }] (n = 0-3) com-
Se{ H}- (for 1), Te{ H}-NMR (for 2), and IR spec-
troscopy), mass spectrometry, elemental analysis, and X-
ray crystallography.
2
6
2 2
2 n
plexes in the stabilization or destabilization of the “rotated
The IR spectra of complexes 1 and 2 are almost identical
in terms of the number of peaks and frequencies. Each com-
plex exhibits three absorption bands for the terminal CO li-
[
39]
structure”. The latter is an isomeric form in which one iron
unit is rotated with respect to other iron unit making one CO
ligand to be in a semi-bridging position and leaving a vacant
site at one of the iron atoms. These studies showed a decrease
in energy between the non-rotated and rotated forms of the
models as the linker length increases. This behavior was at-
tributed to a steric interaction between a methylene carbon
and the apical CO on one of the iron centers, and it facilitated
the formation of the rotated structure.
−
1
gands at 2056, 2029, and 1951 cm for complex 1 and at
−
1
2057, 2016, and 1950 cm for complex 2. These CO stretch-
ing vibrations are shifted to slightly lower frequencies (ca.
−
1
20 cm ) compared to those of complex 3 (2072, 2033, and
−
1 [22]
1997 cm ). This finding can be rationalized in terms of
increasing back-donation to CO due to the enhanced electron
donor ability of Se/Te atoms with respect to that of S atom.
Similar trends have been previously observed in comparing
the substitution of Se or Te in lieu of S in dichalcogenolato
[
38]
As a continuation of our previous studies in this area,
herein we report the synthesis and characterization of
[
13]
1
two mixed dichalcogenolato complexes [Fe (CO) {μ-
[FeFe] hydrogenase complexes.
The H NMR spectrum
2
6
S(CH ) E-μ)}] (E = Se (1), Te (2)) (Figure 1B) having
of complex 1 shows four broad signals at 2.61, 2.53, 1.75,
and 1.65 ppm for SeCH , SCH , SeCH CH and SCH CH
2
2
4
four carbon atoms in their bridging ligands. In addition,
2
2
2
2,
2
1
we also resynthesized the known complex [Fe (CO) {μ-
moieties, respectively. Similarly, the H NMR spectrum of
complex 2 exhibits four broad signals at 2.77 and 2.50 ppm
for TeCH and SCH moieties, respectively, and at 1.85 and
2
6
[
22]
S(CH ) S-μ}]
(3) for comparison purpose. The molecu-
2
4
lar structures of complexes 1 and 2 were determined using
single-crystal X-ray diffraction analysis. Complexes 1 and 2
allow direct comparison with the dithiolato analogue 3 which
is extensively studied for its ability to catalyze the formation
2
2
1.66 ppm for protons in TeCH CH and SCH CH moieties,
2
2
2
2
1
3
1
respectively. The C{ H} NMR spectra of complexes 1
and 2 display one signal for the carbonyl carbon atoms at
208.3 ppm for complex 1 and at 209.2 ppm for complex 2.
Moreover, the signals for the methylene carbons of the chain
linkers of both complexes were also detected at 32.8 ppm
(SCH ), 25.8 (SCH CH ), 25.1 (SeCH CH ), and 21.7
of H from weak acid.
2
2
RESULTS AND DISCUSSION
|
2
2
2
2
2
(
SeCH ) ppm for complex 1, while those for complex 2 are
2
The synthetic procedure of the precursors 1,2-thiaselenane
found at 33.6 (SCH ), 26.5 (SCH CH ), 24.6 (TeCH CH ),
2 2 2 2 2
and 1,2-thiatellurane required for the preparation of com-
and −3.67 (TeCH ) ppm. Indeed, carbon atoms directly
2
[
40]
plexes 1 and 2 is shown in Scheme 1.
Treatment of
bound to heavy nuclei, for example, Te, are known to expe-
riences a drastic high field shift. This effect is called heavy
Fe (CO) with 1,2-thiaselenane or 1,2-thiatellurane in
3
12
[
41]
77
1
boiling THF for 1 hour followed by subsequent column
chromatography afforded complexes 1 and 2, respectively,
as shown in Scheme 2. Complexes 1 and 2 have been
atom effect. In addition, the Se{ H} NMR spectrum of
complex 1 shows one signal at 273.2 ppm for the Se atom
1
25
1
while the Te{ H} NMR spectrum of complex 2 displays
1
13
1
characterized by spectroscopic methods ( H-, C{ H}-,
one signal at 421.6 ppm for the Te atom. The mass spectra
FIGURE 1 A, Structure of the H-cluster. B, Model complexes used in this study

ABUL-FUTOUH eT AL.
3 of 8
|
of complexes 1 and 2 show the molecular ion peaks and
the peaks resulted from dissociation of the six CO ligands,
sequentially.
2
.2
Electrochemical investigations
|
The electrochemical behavior of complexes 1 and 2 was
investigated by cyclic voltammetry as well as that of com-
plex 3 for comparison purposes. Figure 3 shows the cyclic
voltammograms of complexes 1-3 in CH Cl -[nBu N][BF ]
2
.1
Molecular structures
|
2
2
4
4
Single crystals suitable for X-ray diffraction studies were
solutions at a scan rate of 0.2 V/s. On initiating the electro-
chemical scan in the cathodic direction, one reduction event
(Epc = −1.63 and −1.64 V) was observed for complexes 1
and 2, respectively, within the CH2Cl2 solvent window as
shown in Figure 3.
obtained from a saturated solution of 1 and 2 in pentane at
−
24°C. The molecular structures of complexes 1 and 2 are
shown in Figure 2.
Indeed, the (S, Se) and (S, Te) positions in 1 and 2 are su-
perimposed, where the (S, Se) and (S, Te) are disordered be-
tween the locations of the chalcogen atoms, especially in the
case of the S and Se atoms of complex 1. Based on that, the
molecular structures of complexes 1 and 2 could give more
than one homologue; only one of them is shown in Figure 2.
As demonstrated in Figure 2, the solid-state structures of
complexes 1 and 2 espouse a pseudo-square-pyramidal ge-
ometry like those reported for the known diiron dithiolato
It can be noted that the reduction of complexes 1 and 2
occurs at less negative potential (ca. 20 mV) compared to
the corresponding sulfur analogue, complex 3. Generally,
the higher the electron density of the iron cores, the more
[
11–14]
complexes.
The central [Fe SE] (E = Se, Te) moieties
2
of 1 and 2 are in the butterfly conformation in which each Fe
atom is surrounded by three CO ligands in a facial fashion.
The Fe-Fe distances (1: 2.5485(4), 2: 2.5386(6) Å) are longer
[22]
than that reported for complex 3 (2.5179(3) Å). This can
be attributed to the increase in the size of E atom going from
S through Se to Te.
SCHEME 2 Synthetic pathway of the [FeFe]-hydrogenase
model complexes 1 and 2
SCHEME 1 The synthetic pathways
of the precursors 1,2-thiaselenane and
1
,2-thiatellurane

4
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ABUL-FUTOUH eT AL.
|
the negative reduction potential is observed. This fact con-
trasts with our results as such behavior can be explained
in terms of reorganization and stabilization of the reduced
2
.3
Catalytic experiments using a
|
weak acid
[
11,13,30,38,42]
species as previously reported.
Furthermore, in-
The catalytic behavior of complexes 1 and 2 was investigated
by cyclic voltammetry in the presence of various amounts
of acetic acid (AcOH) in CH2Cl2-[nBu4N][BF4] (0.1 mol/L)
solution at 0.2 V/s scan rate as illustrated in Figure 5.
creasing the scan rates of complexes 1 and 2 up to 15 V/s
enhances the reversibility of their reduction events as shown
in Figure 4. The reduction peaks of complexes 1 and 2 are
due to two-electron reduction in a single step based on the
The addition of one equivalent AcOH to solutions of
complexes 1 and 2 causes a shift in their reduction peaks to
less negative potentials by approximately 40 and 30 mV, re-
spectively (Figure 5). This anodic shift suggests that there
is an interaction between the acid and the reduced species
1
/2
study of the current function, (I /c·ν , I = peak current;
pc
c = concentration; ν = scan rate) of these complexes and
compare it to that of complex 3 which is known to undergo
[
22]
an overall two-electron reduction.
Upon initiating the
[
43–46]
electrochemical scan in the positive direction of complexes
and 2, an irreversible oxidation peak is observed for each
complex (E = 0.72 V for 1 and E = 0.71 V for 2), which
of these complexes in CH2Cl2.
However, the current is
1
not increasing with consecutive additions of AcOH indicat-
ing that catalysis is not occurred at this potential. At more
negative potentials (−1.80 to −2.30 V), two new reduction
peaks for complexes 1 and 2 are observed as illustrated in
Figure 5. The height of these peaks increases as the acid
pa
pa
could be assigned to the one-electron oxidation process of
I
I
I
II
Fe Fe → Fe Fe as previously reported for various diiron
[
13,30,31,42]
complexes.
FIGURE 2 Molecular structures
(
50% probability) of one isomer of complex
1
(left) and complex 2 (right). Hydrogen
atoms are omitted for clarity
FIGURE 3 Cyclic voltammetry of
1
.0 mmol/L complexes 1-3 in CH Cl -
2 2
[
nBu N][BF ] (0.1 m) solutions at 0.2 V/s
4 4
scan rate. The potentials E are given in V
+
and referenced to the Fc /Fc couple. The
arrows indicate the scan direction

ABUL-FUTOUH eT AL.
5 of 8
|
FIGURE 4 Cyclic voltammetry of 1.0 mmol/L complex 1 (left) and complex 2 (right) in CH Cl -[nBu N][BF ] (0.1 m) solutions at various
2
2
4
4
+
scan rates. The potentials E are given in V and referenced to the Fc /Fc couple. The arrows indicate the scan direction
FIGURE 5 Cyclic voltammetry of 1.0 mmol/L complex 1 (left) and complex 2 (right) in CH Cl -[nBu N][BF ] (0.1 mol/L) solution at
2
2
4
4
+
0
.2 V/s in the presence of different equivalents of AcOH. The potentials E are given in V and referenced to the Fc /Fc couple. The arrows indicate
the scan direction
concentration increases indicating that complexes 1 and 2
3
CONCLUSION
|
have the ability to catalyze the electrocatalytic reduction
of protons to H via two processes. Indeed, the current of
This study elucidates the use of 1,2-thiaselenane and 1,2-
2
the direct reduction of AcOH in CH Cl -[n-Bu N][BF ] in
thiatellurane compounds as proligands to form [Fe (CO) {μ-
2
2
4
4
2
6
the absence of complexes 1 and 2 makes a negligible in-
S(CH ) Se-μ}] (1) and [Fe (CO) {μ-S(CH ) Te-μ}] (2). The
2
4
2
6
2 4
1 13 1
fluence on the response at potentials more positive than
complexes were fully characterized by using H-, C{ H}-,
77
1
125
1
~
~
−2.00 V and contributes less than 10% of the current at
Se{ H}-,
Te{ H}-NMR, and IR spectroscopy, mass
[
43]
−2.20 V. This indicates that the increase in the current
spectrometry, elemental analysis, and X-ray structure deter-
mination. Furthermore, the influence of the bridging moieties
containing (S, Se) and (S, Te) on the redox behavior of 1 and 2
was studied using cyclic voltammetry. As a result, the reduc-
tion potential of both complexes is comparable to each other
and does not drastically differ from the corresponding sulfur
of these two new reduction peaks of complexes 1 and 2
with increasing AcOH concentration is due to an electro-
catalytic process for the proton reduction to H . However,
2
such catalytic behaviors are similar to those reported in the
literature for other hexacarbonyl complexes.[
43,47,48]

6
of 8
ABUL-FUTOUH eT AL.
|
analogues (complex 3). In addition, complexes 1 and 2 proved
to be good catalysts for proton reduction from AcOH to mo-
lecular hydrogen using cyclic voltammetry.
4
.3
Crystal structure determination
|
The intensity data were collected on a Nonius KappaCCD
diffractometer, using graphite-monochromated Mo-K radia-
α
tion. Data were corrected for Lorentz and polarization effects;
absorption was taken into account on a semi-empirical basis
4
4
EXPERIMENTAL PART
General comments
|
[
49–51]
using multiple-scans.
The structure was solved by direct
.1
|
[
52]
methods (SHELXS) and refined by full-matrix least squares
All reactions were performed using standard Schlenk
2
[52]
techniques against Fo (SHELXL-97). The hydrogen atoms
of 1 were located by difference Fourier synthesis and refined
isotropically. The hydrogen atoms of compounds 2 were in-
cluded at calculated positions with fixed thermal parameters.
and vacuum line techniques under an inert gas of di-
1
13
1
77
1
nitrogen. The H-,
C{ H}-, and
Se{ H}- and
1
25
1
Te{ H}-NMR spectra were recorded with a Bruker
Avance 400 and 500 MHz spectrometer. Chemical
[52]
All non-hydrogen atoms were refined anisotropically. Both
shifts are given in parts per million with references
complexes are present in the crystal as different derivatives
or isomers. This manifest itself is the disorder of the atoms S,
Se, or Te. The disorder could be resolved in both compounds.
1
13
to internal SiMe or CHCl ( H, C) and to Me Se
4
3
2
7
7
1
125
(
Se{ H}). The
Te chemical shift was measured vs
external PhTeTePh and converted to that of Me Te. The
[53]
2
MERCURY was used for structure representations.
mass spectra were measured with Finnigan MAT SSQ
7
10 instrument. The IR spectra were obtained using a
4
.3.1
Crystal data for 1
Bruker Equinox 55 spectrometer equipped with an ATR
unit. Elemental analyses were performed with a Leco
CHNS-932 apparatus. TLC was performed by using
Merck TLC aluminum sheets (Silica gel 60 F254). All
solvents were dried and distilled prior to use accord-
ing to standard methods. The following chemicals were
|
C H Fe O S Se , Mr = 465.53 g/mol, red-brown prism,
10
8
2 6 0.6 1.4
3
size 0.105 × 0.094 × 0.094 mm , monoclinic, space group
P
2 /n, a = 7.6046(2), b = 16.5405(4), c = 11.8942(2) Å,
1
3
β = 103.735(1)°, V = 1453.32(6) Å , T = −140°C, Z = 4,
3
−1
ρ
= 2.128 g/cm , μ (Mo-K ) = 56 cm , multi-scan, trans-
α
calcd.
used as received: Fe (CO) , 1,4-dibromobutane, potas-
3
12
min: 0.5869, transmax: 0.7456, F(000) = 900.6, 11 189 reflec-
sium thioacetate, sodium iodide, and potassium sele-
tions in h(−9/9), k(−21/21), l(−15/15), measured in the range
nocyanate. Silica gel of particle size 0.063-0.200 mm
2
.15° ≤ Θ ≤ 27.44°,completenessΘmax = 99.7%,3309independ-
(
70-230 mesh) was dried at 110°C and employed for
ent reflections, R = 0.0277, 3109 reflections with F > 4σ(F ),
int
o
o
column chromatography. The 1,2-thiaselenane and
2
2
29 parameters, 0 restraints, R1 = 0.0191, wR = 0.0446,
obs obs
1
,2-thiatellurane were prepared following the same pro-
2
R1 = 0.0213, wR = 0.0457, GOOF = 1.096, largest differ-
all
all
[
40]
cedure reported for similar compounds.
Both com-
−3
ence peak and hole: 0.431/−0.388 e Å .
pounds were not isolated and kept in solution to avoid
any polymerization processes.
4
.3.2
Crystal data for 2
|
C H Fe O S Te , Mr = 455.40 g/mol, red-brown prism,
10
8
2 6 1.42 0.58
4
.2
Electrochemistry
|
3
size0.042 × 0.040 × 0.020 mm , monoclinic, space group P 2 /n,
1
Corrections for the iR drop were performed for all experi-
ments. Cyclic voltammetric measurements were conducted
in three-electrode technique [glassy carbon disk (diameter
a = 9.7419(3), b = 9.8871(3), c = 14.9798(4) Å, β = 96.752(2)°,
3
3
V = 1432.83(7) Å , T = −140°C, Z = 4, ρ
= 2.111 g/cm ,
calcd.
−1
μ (Mo-K ) = 34.07 cm , multi-scan, transmin: 0.6652, trans-
α
+
d = 1.6 mm) as working electrode, Ag/Ag in MeCN as
max: 0.7456, F(000) = 883.5, 10 516 reflections in h(−11/12),
k(−12/12), l(−19/19), measured in the range 2.37° ≤ Θ ≤ 27.46°,
completeness Θmax = 99.6%, 3267 independent reflections,
R = 0.0366, 3018 reflections with F > 4σ(F ), 191 parameters,
reference electrode, Pt wire as counter electrode] using a
Reference 600 Potentiostat (Gamry Instruments). All experi-
ments were performed in CH Cl solutions (concentration of
2
2
int
o
o
2
the complexes 1.0 mmol/L) containing 0.1 mol/L [n-Bu N]
0 restraints, R1 = 0.0308, wR = 0.0595, R1 = 0.0353,
4
obs obs all
2
[
BF ] at room temperature. Solutions were deaerated by N
wR = 0.0611, GOOF = 1.163, largest difference peak and
all
4
2
−3
purge for 5-10 minutes, and a blanket of N was maintained
hole: 0.664/−0.513 e Å .
2
over the solutions during the measurements. The vitreous
carbon disk was polished on a felt tissue with alumina before
each measurement. All potential values reported in this paper
4
.4
General procedure for the synthesis of
|
[
Fe (CO) {μ-S(CH ) E-μ}] (E = Se (1), Te (2))
2
6
2 4
are referenced to the potential of the ferrocenium/ferrocene
+
(
Fc /Fc) couple.
A solution of Fe (CO)
(200 mg, 0.40 mmol) and
3
12
1
,2-thiaselenane or 1,2-thiatellurane (0.40 mmol) in THF

ABUL-FUTOUH eT AL.
7 of 8
|
(
30 mL) was heated at reflux for 1 hour under N . The
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2
King, D. Gust, A. L. Moore, T. A. Moore, J. Am. Chem. Soc.
green solution turned deep-red, and then the solvent was
removed under reduced pressure. The residue was purified
by column chromatography using hexane. A red-orange
fraction represents complexes 1 and 2 was collected and
the solvent removed in vacuo. The products were recrystal-
lized from saturated solution of n-pentane kept overnight
at −24°C.
2
012, 134, 1577.
[
5] A. Adamska-Venkatesh, S. Roy, J. F. Siebel, T. R. Simmons, M.
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015, 137, 12744.
[
6] A. Adamska, A. Silakov, C. Lambertz, O. Rüdiger, T. Happe, E.
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[
8] J. W. Peters, W. N. Lanzilotta, B. J. Lemon, L. Seefeldt, Science
853, 1998, 282.
1
4
.4.1
[Fe (CO) {μ-S(CH ) Se-μ}] (1)
|
2
6
2 4
[9] E. J. Reijerse, C. C. Pham, V. Pelmenschikov, R. Gilbert-Wilson,
A. Adamska-Venkatesh, J. F. Siebel, L. B. Gee, Y. Yoda, K.
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Yield: 40% (0.16 mmol). Anal. Calcd. for C H Fe O SSe:
1
0
8
2
6
C, 26.88; H, 1.80; S, 7.17. Found: C, 26.75; H, 1.71; S, 7.64.
1
H NMR (400 MHz, CDCl , ppm): δ 2.61 (bs, 2H, SeCH ),
3
2
[10] Y. Li, T. B. Rauchfuss, Chem. Rev. 2016, 116, 7043.
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khateeb, P. Schollhammer, G. Mloston, W. Weigand, Chem. Eur.
J. 2017, 23, 346.
2
2
.53 (bs, 2H, SCH ), 1.75 (bs, 2H, SeCH CH ), 1.65 (bs,
2 2 2
1
3
1
H, SCH CH ). C{ H} NMR (100 MHz, CDCl , ppm):
2
2
3
δ 208.3 (s, CO), 32.8 (s, SCH ), 25.8 (s, SCH CH ), 25.1
2
2
2
7
7
1
(
s, SeCH CH ), 21.7 (s, SeCH ). Se{ H} NMR (76 MHz,
2 2 2
−1
[12] a) R. J. Wright, C. Lim, T. D. Tilley, Chem. Eur. J. 2009, 15,
CDCl , ppm): δ 273.2. IR (ν , cm ): 2056(m), 2029(vs),
3
CO
8
518; b) G. Qian, W. Zhong, Z. Wei, H. Wang, Z. Xiao, L. Long,
+
1
951(s). DEI-MS (m/z): 448 [M] .
X. Liu, New J. Chem. 2015, 39, 9752.
[
[
[
[
13] C. Figliola, L. Male, P. N. Horton, M. B. Pitak, S. J. Coles, S. L.
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4
.4.2
[Fe (CO) {μ-S(CH ) Te-μ}] (2)
|
2
6
2 4
Yield: 46% (0.18 mmol). Anal. Calcd. for C H Fe O STe:
10
8
2 6
15] C. Topf, U. Monkowius, G. Knör, Inorg. Chem. Commun. 2012,
C, 24.24; H, 1.63; S, 6.47. Found: C, 24.02; H, 1.65; S, 6.30.
1
21, 147.
H NMR (400 MHz, CDCl , ppm): δ 2.77 (bs, 2H, TeCH ),
3
2
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2
.50 (bs, 2H, SCH ), 1.85 (bs, 2H, TeCH CH ), 1.66 (bs, 2H,
2 2 2
1
3
1
SCH CH ). C{ H} NMR (100 MHz, CDCl , ppm): δ 209.2 (s,
2
2
3
CO), 33.6 (s, SCH ), 26.5 (s, SCH CH ), 24.6 (s, TeCH CH ),
2
2
2
2
2
[
17] M. Razavet, S. C. Davies, D. L. Hughes, J. E. Barclay, D. J. Evans,
1
25
1
−
3.7 (s, TeCH ). Te{ H} NMR (157 MHz, CDCl , ppm):
2
3
S. A. Fairhurst, X. Liu, C. J. Pickett, Dalton Trans. 2003, 586.
−
1
δ 421.6. IR (ν , cm ): 2057(m), 2016(vs), 1950(s). DEI-MS
CO
[18] F. Gloaguen, J. D. Lawrence, M. Schmidt, S. R. Wilson, T. B.
+
(m/z): 498 [M] .
Rauchfuss, J. Am. Chem. Soc. 2001, 123, 12518.
[
[
[
[
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ACKNOWLEDGMENTS
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Organomet. Chem. 2007, 692, 5501.
M. El-khateeb thanks the Office of Naval Research Global for
financial support (Award Number: N62909-16-1-2054). H.
Abul-Futouh thanks the Deutscher Akademischer Austausch
Dienst (DAAD) for a scholarship.
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ORCID
Hassan Abul-Futouh
Wolfgang Weigand
http://orcid.org/0000-0003-2419-9782
http://orcid.org/0000-0001-5177-1006
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How to cite this article: Abul-Futouh H, El-khateeb
M, Görls H, Weigand W. [FeFe]-hydrogenase
H-cluster mimics mediated by mixed (S, Se) and (S,
Te) bridging moieties: Insight into molecular
structures and electrochemical characteristics.
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