Hydrogen evolution reaction mediated by an all-sulfur trinuclear nickel complex

Article abstract of DOI:10.1039/d0cc04174b

We report the synthesis and the characterization of a trinuclear nickel complex. Solid state and solution studies using X-ray diffraction, NMR and UV-vis spectroscopy highlight the square planar geometries around the metal centers and an all-sulfur coordi

Full text of DOI:10.1039/d0cc04174b

View Article Online
View Journal
ChemComm
Chemical Communications
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: C. Pieri, A.
Bhattacharjee, A. Hernandes Barrozo, M. Giorgi, B. Faure, J. Fize, M. Réglier, M. Field, M. Orio, V. Artero
and R. Hardré, Chem. Commun., 2020, DOI: 10.1039/D0CC04174B.
Volume 54
This is an Accepted Manuscript, which has been through the
Number
January 2018
Pages 1-112
1
4
Royal Society of Chemistry peer review process and has been
accepted for publication.
ChemComm
Chemical Communications
rsc.li/chemcomm
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 1359-7345
COMMUNICATION
S. J. Connon, M. O. Senge et al.
Conformational control of nonplanar free base porphyrins:
towards bifunctional catalysts of tunable basicity
rsc.li/chemcomm

Please do not adjust margins
Page 1 of 5
ChemComm
View Article Online
DOI: 10.1039/D0CC04174B
COMMUNICATION
Hydrogen evolution reaction mediated by an all-sulfur trinuclear
nickel complex
Cyril Pieri,a Anirban Bhattecharjee,b Alexandre Barrozo,a Bruno Faure,a Michel Giorgi,c Jennifer
Received 00th January 20xx,
Accepted 00th January 20xx
Fize,d Marius Réglier,a Martin Field,d* Maylis Orio,a* Vincent Arterod and Renaud Hardré a*
DOI: 10.1039/x0xx00000x
We report the synthesis and the characterization of a trinuclear Sellman et al. also explored a certain number of all-sulfur nickel
nickel complex. Solid state and solution studies using X-ray complexes.20 Once the structure of the [NiFe] hydrogenase was
diffraction, NMR and UV-vis spectroscopy highlight the square known, many heterobimetallic complexes were then
planar geometries around the metal centers and an all-sulfur developed.21 Unlike the enzyme, all of these complexes suffered
coordination sphere. It exhibits significant electrocatalytic activity from a lack of nickel centred reactivity22 and the situation only
23-28
for hydrogen evolution in DMF using Et3NHCl as the proton source. changed recently.12,
Moreover, the hydrogen producing
The theoretical reaction mechanism suggests that sulfur atoms act catalytic performances of these complexes with respect to
as proton relay, as proposed in [NiFe] hydrogenases.
overpotential requirement and turnover frequency (TOF)
towards hydrogen production were far below those of [NiFe]
hydrogenases, operating at the thermodynamic equilibrium
The limited sources of fossil fuels, together with their
environmental impact, render them unviable in the long run.
This is aggravated by an increasing energy demand worldwide,
resulting in higher prices, as well as with the lack of renewability
of fossil energy at the human time scale.1 To the contrary,
dihydrogen seems to be an ideal substitute, since it is based on
the most abundant atom in the universe, and its combustion
yields high energy, with water as the only waste.2,3 The main
issue remains with its production. While water electrolysis
appears as the most efficient way to produce hydrogen, the
flexible proton exchange membrane technology requires the
use of platinum, a rare and expensive metal with limited
stocks.4 In the search for an economically competitive way of
producing dihydrogen with non-noble metal-based catalysts,
Nature can guide us and inspiration can be found with the [NiFe]
hydrogenases. This family of enzymes is a very attractive
example as it is the most abundant hydrogenases among living
organisms. Their active sites are composed of two metal ions,
iron and nickel, the latter lying in a rare all-sulfur and distorted
tetrahedral coordination geometry.5-7 Many bio-inspired
complexes mimicking this active site can be found in literature8-
15 These models generally show some degree of variation from
the enzyme active site: metals, coordinating atoms, bridging
and exogenous ligands, e.g. CO and CN–.16-18 To reproduce the
features of the [NiFe] hydrogenase active site, an all-sulfur
nickel complex was obtained by Yamamura et al. in 1985, long
before the crystal structure of the enzyme was resolved.19
with a TOF around 1,000 s-1 29,30 The high activity of
.
hydrogenase depends on the presence of proton relays at the
vicinity of the active site. In [NiFe] hydrogenases, terminal
cysteinates have been assigned this role.22 While there are
several examples of FeFe hydrogenase models with terminal
thiolate ligands prone to protonation,31,32 there is only one
known example of a NiFe complex, and this was only observed
under strongly acidic conditions, not pertinent for catalysis.33 In
this context, we have developed a bio-inspired nickel complex
bearing an all-sulfur and constrained ligand that resembles the
Ni-center of the enzyme active site with its cysteine-thiolate
ligands implicated as bases in proton transfer reactions.
Inspired by the seminal work of Bosnich and Pickett,34-36 our
strategy to prepare the trithiol 3 was to start the synthesis from
the thiol
1 easily accessible according to the Bosnich
procedure.34, 37 Compound 2 was then obtained by S-alkylation
of 1 with 2-bromoethyl-trityl-sulfide. Removal of the trityl
substituent in dry acidic condition (CF3COOH) and the reduction
of the disulfide moiety by triethyltin hydride led to the trithiol
3. This overall process provided access to the trithiol 3 which
was used for the synthesis of Ni(II) complexes. Thus, the
reaction of the ligand 3 with 1 eq. of [Ni(CH3CN)6](BF4)2 in
acetonitrile with K2CO3 as base led to the formation of a soluble
complex that rapidly evolved by the formation of a brown
precipitate. Filtration followed by liquid chromatography with
CH2Cl2 as eluant allowed us to get the pure Ni(II) complex 4 in
45% yield (Scheme 1).
Suitable crystals were obtained from a saturated solution of the
complex in CH3CN. The complex crystallizes as a symmetric
trimer with the central Ni-atom lying on the crystallographic
two-fold axis (Figure 1).
a. Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Marseille, France.ꢀ
E-mail: renaud.hadre@univ-amu.fr, maylis.orio@univ-amu.fr
b. Socivolta Inc., 3 Place Ville Marie, suite 400 Montreal, QC H3B 2E3, Canada
c. Aix Marseille Univ, CNRS, Centrale Marseille, Spectropole FR1739, Marseille,
France
d. Univ. Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des
Métaux, 17 rue des Martyrs, 38000 Grenoble, France.
E-mail: martin.field@cea.fr
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 5
COMMUNICATION
Journal Name
Our computations support that its UV-vis spectrum is
View Article Online
DOI: 10.1039/D0CC04174B
dominated by three main absorption bands of different
intensity (Figure S10). The low-energy absorption is assigned to
a d-d transition while the two other spectral features are
attributed to charge transfers from the ligand to metal (Figure
S11 and Table S4). Both the shape and relative intensities of the
calculated spectrum are in pretty fair agreement with the
spectrum measured in solution.
The electrochemical study of 4 was performed by cyclic
voltammetry between +0.5 and –2.5 V vs. Fc+/0 (Figure 2). In the
cathodic region, two one-electron redox systems were
observed: one quasi-reversible at –1.65 V (½(Epc*+Epa*)) and
another irreversible at –2.09 V vs. Fc+/0 (Epc**). The plot of the
peak current versus the square root of the scan rates for the
reversible cathodic wave was found to be linear, indicating that
it is a diffusion-controlled process (Figure S7). In the anodic
direction, the CV revealed one oxidative process with an
Scheme 1 Synthetic route for the nickel complex 4. Conditions: a) NaH, THF, 0°C
to RT, overnight, 66%; b) CF3COOH (excess), Et3SiH (3 eq), CH2Cl2, RT overnight,
81%; c) [Ni(CH3CN)6](BF4)2, K2CO3 (3 eq), CH3CN, RT, 2h.
The asymmetric unit is thus composed of half the complex.
The coordination geometries of the metals are square planar
with small deviations from planar (defined by the Ni and the
four coordinated S atoms, Figure S6 and Table S1): the
maximum out-of-plane distances are close to 0.15 Å and 0.19 Å
(S1 in plane P1 including Ni2 and S1 in plane P2 including Ni1,
respectively). The dihedral angle between P1 and P2 is equal to
73.0697(4)°, while the dihedral angle between P1 and the
symmetric plane P1’ (symmetry code ’: 1-x, y, 3/2-z) is equal to
33.8471(8). The structure of compound 4 is therefore very
compact and folded with a bowl shape and a small accessible
cavity toward the central Ni-atom (mean width and depth equal
to 3.4 Å and 4.9 Å, respectively, Table S2).
To check that the structure of 4 corresponds to the one found
in solution, we performed the UV-vis titration of the ligand 3 by
nickel perchlorate in the presence of triethylamine in DMF.
Upon addition of [Ni(H2O)6](ClO4, the UV-vis spectrum displays
three absorption bands at 290 nm, 410 nm and 540 nm (Figure
S3).
irreversible wave observed at +0.22 V vs. Fc+/0
.
In an effort to gain insight into the nature of the species
observed during cyclic voltammetry experiments, we calculated
the structures of the putative species resulting from one and
two-electron reduction of 4 (Figures S12-14 and Tables S6-8),
and their electronic properties. Upon reduction, our results
indicate that most of the spin density is distributed at one nickel
center (Figure S15). The first reduction process of 4 occurs at
the central metal site leading to the formation of a Ni(II)-Ni(I)-
Ni(II) complex. The two-electron reduction of 4 results in a
triplet ground spin state S = 1 with a stabilization energy of 24
kJ.mol-1 over the singlet state S = 0. This result supports a metal-
based reduction occurring on another nickel center (Figure S16)
and leading to the formation of a Ni(I)-Ni(II)-Ni(I) complex. We
can notice a subsequent electronic rearrangement between the
first and second reduction, which explains the irreversibility
observed experimentally for the second redox system.
Redox potential calculations were conducted to fully assign
the electrochemical events (Tables S3). The computed values
for the one- and two-electron reduction processes are in good
agreement with experiment which indicates that the two
cathodic systems correspond to a monoelectronic processes.
and support the above assignments of the reduction loci in 4.
To examine the capability of complex 4 to mediate proton
reduction catalysis, its electrochemical behaviour was studied
by cyclic voltammetry in the presence of Et3NHCl (pKa = 9.2in
DMF)38,39 as proton source.
Figure 1 X-ray molecular structure of 4 with atom labelling scheme and ellipsoid
parameters at 50% probability level. Hydrogen atoms and carbon labels are
omitted for clarity.
Plotting the molecular extinction coefficient as a function of the
number of Ni(II) equivalents for each absorption band allowed
us to determine the stoichiometry of the complex (Figure S4).
Analysis of the titration curves for both the 410 and 540 nm
bands support the formation of a trinuclear species like 4 with
a 2:3 nickel to ligand ratio, e.g. 2 ligands for 3 metal ions.
To support the above assignment, we used time-dependent
DFT to calculate the theoretical UV-Vis spectrum of 4 (Figure S9
and Table S5) in the trimer form revealed by X-ray diffraction.
Figure 2 Cyclic voltammogram of 4, concentration 0.3 mM at a stationary glassy
carbon electrode (3 mm diameter) in DMF + 0.1M NEt4ClO4. Scan rate 100 mV.s–1
.
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 5
ChemComm
Please do not adjust margins
Journal Name
COMMUNICATION
-1
found. The most stable isomer (by 28 and 61 VkieJ/wmArotilcle Ownliitnhe
DOI: 10.1039/D0CC04174B
BP86/B3LYP, respectively) is protonated on a terminal thiolate ligand
coordinated on a peripheral Ni ion that remains in a square-planar
environment (Figure S17 and Table S9). This reaction is calculated to
be almost isergonic. Another isomer, with higher energy, is obtained
when protonation occurs at the Ni site thus yielding a hydride
derivative with a distorted square-based pyramidal geometry (Figure
S18 and Table S10). Reduction of the two isomers of [HNi3’S4’2]
yielding [HNi3’S4’2]– is calculated to occur at potentials close to the
one calculated for the first reduction of [Ni3’S4’2]. We note that the
stability order of the two isomers is inverted after this reduction step:
in that case the sulfur-protonated species (Figure S19 and Table S11)
is less stable (by 76 and 24 kJ.mol-1 with BP86/B3LY, respectively)
than the Ni-hydride square-planar isomer (Figure S20 and Table S12)
in which one thioether ligand has been eliminated from the Ni
coordination sphere and replaced by the hydride ligand.
Figure 3 Cyclic voltammograms of a 0.25 mM solution of 4 in DMF (0.1 M NEt4ClO4)
with increasing amounts of Et3NHCl (0-55 equiv.) recorded at a glassy carbon
electrode (3 mm diameter) and 100 mV.s–1
.
Cyclic voltammograms of 4 were recorded under argon in
DMF solutions with increased amounts of Et3NHCl (Figure 3) and
show a large irreversible catalytic wave with a mid-wave
퐸0
potential
푐푎푡 of –1.70 ± 0.03 V vs. Fc+/0, i.e. close to the
reduction potential of 4. The current response of this peak-
shaped wave is directly proportional to the concentration of
protons in the electrolyte solution (Figure S8). A value of 590
mV was calculated for the overpotential requirement of 4 for
proton reduction in the presence of Et3NHCl in DMF.39
To confirm that the observed catalytic waves correspond to the
electrocatalytic reduction of protons into hydrogen, we
performed a bulk electrolysis experiment of a DMF solution of
Et3NHCl in excess (200 mM) and 4 (1 mM). Gas products were
monitored by continuous in-line GC analysis. A potential of –
1.60 V versus Fc+/0 was applied to the mercury-pool working
electrode resulting in the immediate formation of hydrogen.
This experiment rules out the possibility that proton reduction
occurs as the result of deposition of nickel nanoparticles on the
electrode surface since they would amalgamate within the
mercury pool electrode. Consequently, under these conditions
catalysis mediated by 4 is expected to be homogeneous in
nature. During the 15 h experiment, a turnover number of 5 was
achieved with a moderate Faradaic yield of 30%; indicating
some degradation of the complex during turn-over.
Scheme 2 Proposed DFT computed reaction mechanism for hydrogen evolution
mediated by 4.
DFT calculations were finally conducted to decipher the reaction
mechanism of hydrogen evolution by 4 (Scheme 2). We propose the
catalytic cycle for H2 evolution presented in Scheme 2 and based on
Finally, protonation of the reduced hydride species [HNi3’S4’2]–
leads to formation of a dihydrogen complex [(H2)Ni3’S4’2]
(Figure S21 and Table S13). This reaction is calculated to be
the ECEC sequence, classically found for cobalt and nickel thermodynamically favorable. The structure is reminiscent of a
complexes.40-42 UV/Vis measurements performed in the absence and
presence of Et3NHCl (Figure S-5) display almost identical features,
indicating that the structure of 4 is unaffected by the addition of a
proton source of such strength. From the cyclic voltammetry
measurements in the presence of acid, it can be inferred that the
dihydrogen bond between nickel and sulfur that has been
proposed as a key intermediate in the route to H2 evolution at
the active site of [NiFe] hydrogenases (Ni-R in Scheme 3).44,45
From this dihydrogen complex, liberation of H2 is strongly and
entropically favored. Removal of H2 leads to the original
structure of [Ni3’S4’2] thus closing the catalytic cycle.
reaction proceeds from the one-electron reduced species with a In this work, we have reported the experimental and theoretical
study of an original trinuclear nickel complex that displays an
all-sulfur coordination sphere and exhibits a significant catalytic
midwave electrocatalytic potential equal to that of the first reduction
in 4 denoted [Ni3’S4’2]. The first reduction at the Ni site was
calculated at potentials of –1.84 and –2.02 V vs Fc+/0 when using the
B86 and B3LYP functionals, respectively (Table S3). We then
investigated the protonation of the reduced complex [Ni’3S4’2]– with
activity with
a moderate overpotential requirement for
hydrogen production in DMF using Et3NHCl as the proton
source. Detailed analysis of the electrocatalytic data combined
with DFT calculations allowed us to propose an ECEC catalytic
Et3NH+ yielding [HNi3’S4’2]. Two distinct protonation sites could be pathway involving Ni-bound terminal thiolate ligand as proton
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 4 of 5
COMMUNICATION
Journal Name
13 S. Canaguier, M. Field, Y. Oudart, J. Pécaut, M. VFioewntAertcicalevOen,liVne.
Artero, Chem. Comm., 2010, 46, 5876.DOI: 10.1039/D0CC04174B
14 D. Basu, T. Spencer Bailey, Noémie Lalaoui, Casseday P.
Richers, Toby J. Woods, Thomas B. Rauchfuss, Federica
Arrigoni, Giuseppe Zampella, Inorg. Chem. 2019, 58, 4, 2430.
15 N. Coutard, N. Kaeffer, V. Artero, Chem. Commun., 2016, 52,
13728.
relay mimicking the role of terminal cysteinate ligand in the
active site of [NiFe] hydrogenases.
16 A. C. Marr, D. J.E. Spencer, M. Schröder, Coord. Chem. Rev.
2001, 219–221, 1055.
17 T. R. Simmons, G. Berggrena, M. Bacchi, M. Fontecave, V.
Artero, Coord. Chem. Rev., 2014, 270-271, 127.
18 E. Bouwman, J. Reedijk, Coord. Chem. Rev., 2005, 15-16, 1555.
19 T. Yamamura, H. Miyamae, Y. Katayama, Y. Sasaki, Chem.
Lett., 1985, 269.
20 D. Sellmann, S. Fünfgelder, G. Pohlmann, F. Knoch, M. Moll,
Inorg. Chem., 1990, 29, 23, 4772.
21 S. Kaur-Ghumaan, M. Stein, Dalton Trans., 2014, 43, 9392
22 W. Lubitz, H. Ogata, O. Rüdiger, E. Reijerse, Chem. Rev., 2014
114, 4081.
23 H. Tang, M. B. Hall, J. Am. Chem. Soc., 2017, 139, 18065.
24 D. Brazzolotto, L. Wang, H. Tang, M. Gennari, N. Queyriaux, C.
Philouze, S. Demeshko, F. Meyer, M. Orio, V. Artero, M. B.
Hall, C. Duboc, ACS Catal., 2018, 8, 10658.
25 G. M. Chambers, M. T> Huynh, Y. Li, S. Hammes-Schiffer, T.B.
Rauchfuss, E. Reijerse, W. Lubitz, Inorg. Chem., 2016, 55, 419.
26 S. Ding, P. Ghosh, A. M. Lunsford, N. Wang, N. Bhuvanesh, M.
B. Hall, M. BY. Darensbourg, J. Am. Chem. Soc. 2016, 138,
12920.
Scheme 3 Catalytic cycle of the [NiFe] hydrogenases involving the Ni-SIa, Ni-R, and
Ni-C states.
Further work is currently in progress in our group to develop
new bio-inspired mimics of the [NiFe] hydrogenase and to
design original polynuclear metal complexes with thiolate
ligands capable of mediating efficient hydrogen evolution.
27 S. Ding, P. Ghosh, A. M Lunsford, N. Wang, N. Bhuvanesh, M.
B. Hall, M. Y. Darensbourg, J. Am. Chem. Soc. 2016, 138,
12920.
28 S. Ding, P. Ghosh, M. Y.Darensbourg, M. B.Hall, Proc. Natl.
Acad. Sci., 2017, 114, E9775.
Conflicts of interest
There are no conflicts to declare.
29 M. E. Ahmed, A. Dey, Curr. Opin. Electrochem., 2019, 15,155
30 D. Schilter, J. M. Camara, M. T. Huynh, S. Hammes-Schiffer, T.
B. Rauchfuss et al, Chem. Rev., 2016, 116, 8693.
31 U-P. Apfel, D. Troegel, Y. Halpin, S. Tschierlei, U. Uhlemann, H.
Görls, M. Schmitt, J. Popp, P. Dunne, M. Venkatesan, M. Coey,
M. Rudolph, J. G. Vos, R. Tacke, W. Weigand, Inorg. Chem
2010, 49, 21, 10117.
32 R. Zaffaroni, T. B. Rauchfuss, D. L. Gray, L. De Gioia, G.
Zampella, J. Am. Chem. Soc. 2012, 134, 46, 19260.
33 Lubitz (1) Weber, K.; Krämer, T.; Shafaat, H. S.;
Weyhermüller, T.; Bill, E.; van Gastel, M.; Neese, F.; Lubitz, W.
J. Am. Chem. Soc. 2012, 134, 20745.
34 C. Kolomyjec, J. Whelan, B. Bosnich, Inorg. Chem., 1983, 22,
2343.
35 M. Razavet, S. C. Davies, D. L. Hughes, C. J. Pickett, Chem.
Commun., 2001, 847.
36 M. Razavet, S. C Davies, D. L. Hughes, J. E. Barclay, D. J. Evans,
S. A Fairhurst, X. Liu, C. J. Pickett, Dalton Trans, 2003, 586.
37 R. A. Valiulin, A. G Kutateladze, J. Org. Chem., 2008, 73, 335.
38 K. Izutsu, Acid-Base Dissociation Constants in Dipolar Aprotic
Solvents; 1990, Blackwell Scientific: Oxford, U.K.
39 V. Fourmond, P.-. Jacques, M. Fontecave, V. Artero, Inorg.
Chem., 2010, 49, 10338.
40 V. Artero; J.-M. Saveant, Energy Environ. Sci., 2014, 7, 3808.
41 J. L. Dempsey, B. S. Brunschwig, J. R. Winkler, H. B. Gray, Acc.
Chem. Res., 2009, 42, 1995.
Acknowledgements
The authors gratefully acknowledge research support of this work by
the French National Research Agency (CODEC, ANR-19-
CE05_0030_01; CatH2, ANR-07-BLAN-0298; NiFe-Cat, ANR-2010-
BLAN-711-1; NiFemim, ANR-DFG-2016-NLE; Labex ARCANE;
Graduate school of Chemistry, Biology and Health of Univ. Grenoble
Alpes, CBH-EUR-GS, ANR-17-EURE-0003).
Notes and references
1
2
3
D. A. King, Science, 2004, 303, 176.
J. A. Turner, Science, 2004, 305, 972.
P. P. Edwards, V. L. Kuznetsov, W. I. F. David, N. P. Brandon,
Energy Policy, 2008, 36, 4356.
4
5
6
J. R. McKone, S. C. Marinescu, B. S. Brunschwig, J. R. Winkler,
H. B. Gray, Chem. Sci. 2014, 5, 865.
A. Volbeda, M-H. Charon, C. Piras, E.C. Hatchikian, M. Frey, J-
C. Fontecilla-Camps, Nature, 1995, 373, 580.
A. Volbeda A, E. Garcin, C. Piras, A. L. de Lacey, V.M.
Fernandez , E.C. Hatchikian, M. Frey, J-C. Fontecilla-Camps, J.
Am. Chem. Soc., 1996, 118, 12989.
7
8
R.P. Happe, W. Roseboom, A.J. Pierik, S.P.J Albracht, K.A.
Bagley, Nature 1997, 385, 126.
D. Sirbu, T. Straistari, A. C Benniston, Hydrogenases: From
Biomimetic to Bioinspired Models in Bioinspired Chemistry,
From Enzymes to Synthetic Models, 2019, 5, 89.
T. B. Rauchfuss, Acc. Chem. Res., 2015, 48, 2107.
42 N. Kaeffer, M. Chavarot-Kerlidou, V. Artero, Acc. Chem. Res.,
2015, 48, 1286.
9
43 N. Queyriaux, R.T. Jane, J. Massin, V. Artero, M. Chavarot-
Kerlidou, Coord. Chem. Rev., 2015, 304-305, 3.
44 P. E. M. Siegbahn, J. W. Tye, M. B. Hall, Chem. Rev., 2007, 107,
4414.
10 M. Y. Darensbourg, E.J. Lyon, J.J. Smee, Coord. Chem. Rev.,
2000, 206, 533.
11 Z. Li, Y. Ohki, K. Tatsumi, J. Am. Chem. Soc., 2005, 127, 8950.
12 D. Brazzolotto, M. Gennari, N. Queyriaux, T.R. Simmons, J.
Pecaut, S. Demeshko, F. Meyer, M. Orio, V.Artero, C. Duboc,
Nat. Chem., 2016, 8, 1054.
45 G. Dong, U. Ryde, JBIC, 2016, 21, 383.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 5
ChemComm
View Article Online
DOI: 10.1039/D0CC04174B
289x295mm (72 x 72 DPI)