Triphos-Fe dinitrogen and dinitrogen-hydride complexes: Relevance to catalytic N2 reduction

Article abstract of DOI:10.1039/c8cc07466f

The two electron reduction of iron complexes [(P^RP₂^Cy)Fe(Cl)₂] (R = Ph or tBu) 2a-b afforded complexes [(P^RP₂^Cy)Fe(N₂)₂] 4a-b. Protonation of 4a at the metal center and subsequent reduction to Fe(i)-H species lead to complex [(P^PhP₂^Cy)Fe(N₂)(H)₂] 6avia a spontaneous disproportionation reaction. Complex 4a behaves as one of the most efficient monometallic Fe-catalysts reported to date for N₂-to-N(SiMe₃)₃ functionalization under atmospheric pressure.

Full text of DOI:10.1039/c8cc07466f

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: A. Cavaillé, B.
Joyeux, N. Saffon, N. Nebra, M. Fustier-Boutignon and N. Mézailles, Chem. Commun., 2018, DOI:
10.1039/C8CC07466F.
This is an Accepted Manuscript, which has been through the
Volume 52 Number
1 4 January 2016 Pages 1–216
Royal Society of Chemistry peer review process and has been
accepted for publication.
ChemComm
Accepted Manuscripts are published online shortly after
Chemical Communications
www.rsc.org/chemcomm
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
author guidelines.
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, outlined
in our author and reviewer resource centre, 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
Marilyn M. Olmstead, Alan L. Balch, Josep M. Poblet, Luis Echegoyenet al.
Reactivity differences of Sc3N@C2n (2n 68 and 80). Synthesis of the
first methanofullerene derivatives of Sc N@D5h-C80
=
3
rsc.li/chemcomm

Please do not adjust margins
ChemComm
Page 1 of 5
View Article Online
DOI: 10.1039/C8CC07466F
Journal Name
COMMUNICATION
Triphos-Fe Dinitrogen and Dinitrogen-Hydride Complexes:
Relevance to Catalytic N2 Reductions.
Anthony Cavaillé,a Benjamin Joyeux,a Nathalie Saffon-Merceron,b Noel Nebra,a Marie Fustier-
Boutignon,a Nicolas Mézailles.*,a
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
The two electron reduction of the iron complexes [(PRP2Cy)Fe(Cl)2] isomer II.6 Since 2015, Peters spectroscopically identified the
(R = Ph or tBu) 2a-b afforded complexes [(PRP2Cy)Fe(N2)2] 4a-b. key intermediates III and IV, thus unequivocally providing a
Protonation of 4a at the metal center and subsequent reduction clear picture on the site of protonation at the distal N-atom for
to Fe(I)-H species leads to complex [(PPhP2Cy)Fe(N2)(H)2] 6a via the “EP3” ligated complexes.10 Interestingly, the same group
spontaneous disproportionation reaction. Complex 4a behaves as identified the hydride-borohydride [(BP3)(µ-H)Fe(N2)(H)]
one of the most efficient monometallic Fe-catalysts reported to complex
V under turnover conditions, pointing favorable
date for the N2-to-N(SiMe3)3 under atmospheric pressure.
protonation at the Fe center rather than at the N2.14 It is also
the case for Fe-N2 complexes which are not catalytically active
in N2-to-NH3 transformation.11 This selectivity can be switched
by adding strong Lewis acid, but stoichiometric formation of
NH3 from N2 has yet to be reported.12 To date, studies covering
protonation of low-valent Fe-N2 species at Fe within
catalytically active systems are very limited,7 yet the
evaluation of such (N2)Fe-H species in N2-functionalization
events is critical to understanding N2 reduction catalysis, and
what may limit its efficacy.
Nitrogen is an essential element for our biosphere and is
introduced in the living chain through ammonia. In nature, NH3
is synthesized by a family of bacteria possessing a nitrogenase
enzyme (Fe, FeV or FeMoco active center) via N2 reduction
involving electron and proton transfer sequences.1 On the
other hand, and only after decades of fundamental research, a
handful of synthetic models capable of performing catalytic
reduction of N2 into ammonia (or hydrazine) have been
developed.2 In overwhelming majority, they rely on Mo3-4 or
Fe5-7 complexes.8 A closer look at the structures of the known
catalysts for NH3 formation reveals that neutral tridentate
“PEP” ligands (E = N, P, C) occupy a prominent position for Mo
catalysts4,(best TON for NH3 formation :415)4e whereas the
tetradentate “EP3” ligands (E = B, C) are currently the most
efficient Fe systems5 (best TON: 89).5e Mechanistically, the
initial steps for the Mo-promoted N2-to-NH3 transformation
have been studied for Mo dinitrogen complexes featuring
bidentate, tridentate and tetradentate ligands, for which
protonation at the distal N to form the Mo(N=NH) and Mo=N-
NH2 intermediates is favored.9 In sharp contrast, there was not
much information about the site of protonation for
catalytically active Fe systems until very recently (Scheme 1).
Nishibayashi and co-workers isolated the thermodynamic,
dead-end complex
I by protonation at the pyrrole backbone
instead of the kinetically favored, catalytically-competent
Scheme 1 Protonation of low-valent Fe-N2 complexes that are
catalytically-competent in the N2-to-NH3 conversion.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 5
View Article Online
DOI: 10.1039/C8CC07466F
COMMUNICATION
Journal Name
In addition to these mechanistic studies, we have evaluated KC8, followed by slow warming up to room temperature over
the performances of our Fe complexes in the related N2 to 15 (Scheme 2). Complexes 4a 4b resp.), formed
N(SiMe3)3 reduction process and show them to be efficient quantitatively vs internal standard, are characterized by a
catalysts. These results are presented herein. triplet at 120.1 ppm (JP−P = 69.2 Hz) (150.5 ppm, JP−P = 48.0 Hz
h
(
Cy
Our group demonstrated that the PPhP2 ligand in resp.) and a doublet at 102.4 ppm (JP−P = 69.2 Hz) (97.0 ppm,
conjunction with Mo promotes the stepwise functionalization JP−P = 48.0 Hz resp.) in the 31P{1H} NMR spectrum (ESI), as well
of N2 in the [(PPhP2Cy)Mo(N2)2]2(µ-N2) complex by SiMe3Cl and as by two NN stretching bands in the IR spectrum at 2047 and
electrons.13 In the present work the PRP2Cy (R = Ph, tBu) ligands 1982 cm-1 (2048 and 1981 cm-1 resp.). Together, this data
are used for the synthesis of rare bis-N2 species of Fe(0) 14
,
suggested the formation of the expected [(PRP2Cy)Fe(N2)2]
[(PRP2Cy)Fe(N2)2] complexes 4a-b The [(PRP2Cy)Fe(N2)(H)2] complexes. Isolation of these complexes proved difficult as
.
complexes 6a-b were obtained upon a protonation/reduction loss of N2 appeared to be a facile process under vacuum and
sequence from complexes 4a-b through a facile dismutation complexes are thereby stored in THF solutions of known
process from a FeI hydride intermediate. These complexes concentration at –30 °C for further reactivity. Nonetheless,
showed activity in the reduction of N2 into NH3 and 4a slow evaporation of THF to dryness via N2 bubbling and
emerged as one of the most efficient monometallic Fe- extraction of the complexes into pentane allowed
catalysts reported to date for the N2 into N(SiMe3)3 crystallization of complex 4b (Fig. 1). The X-ray study
functionalization.
The bulky, strongly donating alkyl ligands PRP2 (PRP2
confirmed the formation of 4a-b as rare examples of Fe bis-N2
complexes.14 [(PtBuP2Cy)Fe(N2)2] features
square based
Cy
Cy
=
a
RP(CH2CH2PCy2)2, R = Ph, 1a; tBu, 1b) were reacted with pyramid geometry at Fe, with the three P-atoms located at
[FeCl2(THF)1.5] in THF to afford the expected Fe complexes equatorial positions. As a consequence, the two N2-ligands
[(PRP2Cy)Fe(Cl)2] 2a-b (light purple for 2a, and white powder for occupy the remaining equatorial position and one apical
2b) in excellent isolated yields (96%15 and 83% yield, position. In particular, the N−N bond lengths of 1.118(3) and
respectively, Scheme 2). Complexes 2a-b are paramagnetic 1.128(3) Å indicate weak back-donation from the Fe center to
and exhibit Mössbauer spectra with isomer shift of 0.767 the dinitrogen ligands, in accord to previous reports.14a
mm.s-1 and 0.730 mm.s-1 expected for FeII in a quintuplet state The catalytic performance of complexes 4a-b in the N2-to-NH3
(ESI). The magnetic moment of 5.2 μB for both 2a and 2b was transformation was then addressed. The reactions were
measured in solution using the Evans’ method, in agreement performed using 200 equiv. of KC8 and 200 equiv. of HBArF
4
with the Mössbauer (4.90 μB is expected for a spin-only S = 2 (HBArF
=
[H(Et2O)2][BArF ];
BArF
=
tetrakis(3,5-
4
4
4
magnetic moment).16 X-Ray diffraction analysis of complex 2b bis(trifluoromethyl)-phenyl)borate) at –80°C in Et2O for 1 h.14
confirmed the trigonal bipyramid geometry at the Fe (ESI).
Complexes 4a and 4b lead to 3.6±0.3 and 3.3±0.4 equiv. of
NH3, while negligible amounts of NH3 were achieved in
absence of reducing agent (less than 0.1 equiv.), in accord with
literature precedence.17 These observations indicate that,
although the performance is rather limited, the reaction
occurs via a catalytic process and not only via stoichiometric
protonation of the two N2 coordinated to the Fe center. It was
thus of importance to understand the initial stages of the
functionalization of coordinated N2 along with the factors
influencing catalytic turnover. In the more efficient catalytic
systems, the possible formation of an anionic Fe complex
(either formally Fe0 or Fe-I) has been shown.5a,6 Cyclic
voltammetry studies showed that no reduction wave
corresponding for the Fe0/Fe-I couple was observed down to –
Scheme 2 Synthesis of the (PRP2Cy)Fe complexes 3a-b and 4a-b
.
3.0
V . Confirmation was
vs Fc/Fc+ for complex 4a
Reduction of 2a-b to form Fe-N2 complexes was then studied.
Reduction by one electron using Na/Hg lead to the formation
of the corresponding [(PRP2Cy)Fe(Cl)] complexes 3a-b in
excellent isolated yield (92% and 85%, respectively).
experimentally obtained as no reaction occurred between
complexes 4a-b with excess KC8 at low temperature. The first
step under catalytic conditions has thus to imply protonation
of the Fe0 species. Reaction between complex 4a and one
Complexes 3a-b are paramagnetic, and 3a exhibits
a
equivalent of HBArF was therefore performed (–78°C or R.T.,
Mössbauer spectrum with isomer shift of 0.697 mm.s-1
expected for FeI in a quartet state (ESI).10a Identical magnetic
moment of 4.1 μB was measured in solution for 3a and 3b
using the Evans’ method (3.87 μB is expected for a spin-only S
= 3/2 magnetic moment).16 IR spectra of complexes 3a-b
showed that N2 does not coordinate at the FeI center, which
was confirmed by a X-ray diffraction study of complex 3a (ESI).
Reduction to Fe0 was thus studied. It can be achieved, either
from 2a-b or 3a-b at –80 °C with the stoichiometric amount of
4
THF). It resulted in the formation of a paramagnetic complex
characterized by a single νNN stretch at 2092 cm-1, only
consistent with protonation at Fe and not at the distal N, as
previously observed,17 leading to a FeII(H)(N2)+ complex 5a. DFT
calculations were carried out to probe the preferred site for
protonation of the Fe(N2)2 complex 4a (ESI). Solvent effects
were taken into account using the pcm method (solvent =
+
THF), and HBArF4 was modeled as H(OEt2)2 . The desirable
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 3 of 5
View Article Online
DOI: 10.1039/C8CC07466F
Journal Name
COMMUNICATION
protonation at a distal N to form [(PP2)Fe(N2)(N2H)]+ (triplet phosphine ligand.7 In the present case, formation of complex
state) is only marginally exergonic (–2.1 kcal/mol) because of 6a from 5a appears to involve reduction to the FeI(N2)(H)
the entropic gain generated by the liberation of two Et2O intermediate which is not stable toward dismutation. In order
+
molecules from H(OEt2)2 . Indeed, the reaction is calculated to to verify this assumption, the reaction between FeI complex 3a
be endothermic (∆H = +10.7 kcal/mol), and at best protonation
at terminal N would be in equilibrium with starting material.
On the other hand, protonation at Fe is both exothermic (∆H =
–1.6 kcal/mol) and strongly exergonic (–24.9 kcal/mol), leading
to the formation of the [(PP2)FeII(H)(N2)]+ complex (triplet
state), via spontaneous elimination of the N2 ligand trans to
the incoming H ligand. Accordingly, further experimental
evidence of the protonation at Fe was given by the subsequent
reduction by one equivalent of KC8 starting at low
Fig. 1 Molecular structure of 4b (left) and 6a (right). Hydrogen atoms
(except metallic hydrides) and solvent molecules are omitted for
clarity; thermal ellipsoids are drawn with 50% probability.
temperature.
Instead
of
forming
the
expected
[(PPhP2Cy)FeI(H)(N2)] complex (paramagnetic, doublet state), a
novel diamagnetic complex was formed in ca 50% (vs internal
standard). This species is characterized by a broad triplet at
120.2 ppm (JP−P = 6.7 Hz) and a doublet at 111.1 ppm (JP−P = 6.7
Hz) in the 31P{1H} NMR spectrum. Two highly coupled hydride
signals resonate at –9.8 ppm and –20.9 ppm in the 1H NMR
spectrum (ESI) and a νNN stretch at 2051 cm-1 was measured by
IR spectroscopy. Together, this data pointed to the formation
of the FeII complex [(PPhP2Cy)Fe(N2)(H)2] complex 6a (Scheme
3).
and one equivalent of LiBEt3H was conducted under N2 and
followed by 31P{1H} NMR spectroscopy. Within minutes of
mixing, a mixture of diamagnetic complexes was observed,
among which complex 6a. After 2 h at room temperature,
complex 6a is formed in ca 50% yield, confirming the favorable
dismutation reaction of the FeI intermediate. The
thermodynamic stability of the hydride-dinitrogen complexes
of FeI vs FeII in this series therefore depends to the highest
extent on the tridentate neutral phosphine ligand.
N2
Ph
N
2, THF
r.t., 1 h
H
P
PCy2
BArF
The [(PPhP2Cy)Fe(N2)(H)2] complex 6a was then subjected to the
model catalytic conditions (i.e. 200 equiv. of KC8 and 200
Ph
4
P
Fe N2
Fe
N
2, THF
P
N2
PCy2
-80°C to r.t.
over 3 h
Cy2
PCy2
5a
equiv. of HBArF at –80°C in Et2O for 1h), leading to the
4a
4
KC8
F
H
BAr
formation of 2.7±0.3 equiv. of NH3. One should note that this
result is almost identical to the one obtained by Peters and co-
workers with their [(P2P’Ph)Fe(N2)(H)2] complex (2.6±0.1 equiv.
NH3).
+
4
N2
Ph
P
PCy2
N
2, THF
r.t., 1 h
1/2
Fe
+ 1/2 Fe0
Cl
Ph
H
P
P
Fe
Cy2
H
H
LiEt3B
+
- Et3B
- LiCl
PCy2
45% vs
intern. std.
PCy2
6a
The aforementioned mechanistic aspects derived from the
protonation of the low-valent Fe-N2 complex 4a indicate that
addition of electrophiles at the distal N-atom is of utmost
importance to reach good turnover numbers when dealing
with Fe-catalyzed N2 functionalization. Given the high affinity
of Si moieties for N2 ligands bonded to transition metals, we
turned our attention toward the N2-silylation with ClSiMe3.2,19
To date, the most efficient catalytic systems are based on Mo
(best TON : 220)19a and Co (best TON: 195).19i Concerning Fe,
several Fe-hydride clusters have been shown to be very active
(TON: 160 for a Fe4 cluster, i.e. 40 per Fe center; 183 for Fe6
cluster, i.e. 31 per Fe center)19e while the most efficient
monometallic Fe complex was reported while our work was
under evaluation (TON: 121).19h Having in hands several Fe-N2
3a
N2
Ph
Cl
Ph
N
2, THF
r.t., 1 h
P
PCy2
Fe
P
Fe Cl
2 LiEt3BH
+
PCy2
H
P
- 2 Et3B
- 2 LiCl
PCy2
2a
Cy2
H
6a
(79%)
Scheme
(N2)Fe(H)2 6a
3
Multiple synthetic routes of access to the complex
.
Alternatively, this complex can be synthesized in a selective
manner from the reaction between complex 2a and two
equivalents of LiBEt3H. Unlike complexes 4a-b, 6a does not
release coordinated N2 under vacuum, and was crystallized in a
very good 79% yield. The solid state Mössbauer spectrum gives
rise to a quadrupole doublet for a FeII S = 0 species (δ = 0.063
mm.s-1 and ∆EQ = 0.673 mm.s-1; see ESI). The X-ray structure of
the complex corroborated the NMR data, and confirmed the
two different hydride environments, one being trans to the
central P atom and the second trans to N2.18 The N–N bond
distance of 1.085(2) Å in 6a is comparable to the one found for
4b despite a less electron rich Fe center (FeII vs Fe0), this
observation being attributed to the strong trans influence of
the hydride ligand. The reactivity we observed from either FeII
or FeI is in sharp contrast with the most recent report by
complexes, 4a, 4b and 6a, their efficiency in this process was
tested. Optimization of the model reaction conditions was
done with complex 4a. As often observed, THF appears critical,
as well as the use of 600 equiv. of K as reducing agent.13,19f
Under these conditions, complex 4a provides a TON of
32.0±0.8 in the range of the more efficient monometallic Fe
20
catalysts for the synthesis of silylamines from N2
.
It
corresponds to an efficiency in the formation of the N-Si bond
of 16% (17%, ref 19f, 15.5% and 20%, ref 19e; 24% ref 19h).
Complex 4b performs slightly less with a TON of 27.0±0.5,
Peters and co-workers who obtained the FeI complex
[P2P’PhFe(H)]2(μ-N2) (P2
= PhP(2-(iPr2P)C6H4)2) from the
P’Ph
hydride reduction of the FeIIX2 precursor featuring a tridentate
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
View Article Online
DOI: 10.1039/C8CC07466F
COMMUNICATION
Journal Name
Nakajima, K. Yoshizawa, Y. Nishibayashi, Bull. Chem. Soc.
Jpn., 2017, 90, 1111.
(a) J. S. Anderson, J. Rittle, J. C. Peters, Nature, 2013, 501, 84;
whereas the dihydride complex 6a is about half as efficient
(entry 7, TON 14.5).
5
Table 1. Catalytic investigations.
(b) S. E. Creutz, J. C. Peters, J. Am. Chem. Soc., 2014, 136
,
1105; (c) T. J. Del Castillo, N. B. Thompson, J. C. Peters, J. Am.
Chem. Soc., 2016, 138, 5341; (d) P. J. Hill, L. R. Doyle, A. D.
Crawford, W. K. Myers, A. E. Ashley J. Am. Chem. Soc., 2016,
138, 13521. (e) M. J. Chalkley, T. J. Del Castillo, B. D. Matson,
J. P Roddy, J. C. Peters, ACS Cent. Sci., 2017, 3, 217.
S. Kuriyama, K. Arashiba, K. Nakajima, Y. Matsuo, H. Tanaka,
Entrya
Cat.
4a
4a
4a
4a
4a
4b
6a
Solvent
THF
Red.
Na
K
Equiv. N(TMS)3
15.8
32.0±0.8b
1
2
3
4
5
6
7
6
THF
K. Ishii, K. Yoshizawa, Y. Nishibayashi, Nat. Commun., 2016,
7
1,4-dioxane
2-MeTHF
Et2O
K
7.7
, 12181.
T. M. Buscagan, P. H. Oyala, J. C. Peters, Angew. Chem. Int.
Ed., 2017, 56, 6921.
7
8
K
6.5
K
< 2.0
27.0±1.0b
Co complexes: (a) T. J. Del Castillo, N. B Thompson, D. L. M.
Suess, G. Ung, J. C. Peters, Inorg. Chem., 2015, 54, 9256; (b)
S. Kuriyama, K. Arashiba, H. Tanaka, Y. Matsuo, K. Nakajima,
K. Yoshizawa, Y. Nishibayashi, Angew. Chem. Int. Ed., 2016,
55, 14291.
(a) M. Hidai, Y. Mizobe, Chem. Rev., 1995, 95, 1115; (b) N.
Khoenkhoen, B. de Bruin, J. N. H. Reek, W. I. Dzik, Eur. J.
Inorg. Chem., 2015, 2015, 567.
THF
K
THF
K
14.5
aEquiv. N(TMS)3 = equiv. amine/Cat. b: done in duplicate
In conclusion, we show here that the tridentate ligand PRPCy2 is
able to stabilize rare Fe0 bis-N2 complexes 4a-b. These
complexes expand the small field of iron species able to
perform N2 reduction into NH3 under mild conditions in
homogeneous phase. Their weak activity can be explained by
kinetically favored protonation at the metallic center rather
than at a nitrogen atom as well as the in situ formation of the
FeII species [(PPhP2Cy)Fe(N2)(H)2] 6a from transient FeI(H)(N2)
species. The use of the bulkier, softer electrophile ClSiMe3
precluded such a reactivity at the Fe center and thereby
complex 4a rises up as one of the most competent catalysts for
N(TMS)3 production from N2. These results provide further
guidance toward the development of more efficient Fe
complexes in the N2 catalyzed reduction.
9
10 (a) J. S. Anderson, G. E. Cutsail, J. Rittle, B. A Connor, W. A.
Gunderson, L. Zhang, B. M. Hoffman, J. C. Peters, J. Am.
Chem. Soc., 2015, 137, 7803; (b) J. Rittle, J. C. Peters, J. Am.
Chem. Soc., 2016, 138, 4243.
11 L. D. Field, L. D.; N. Hazari, H. L. Li, Inorg. Chem., 2015, 54
4768.
,
12 J. B. Geri, J. P. Shanahan, N. K. Szymczak, J. Am. Chem. Soc.,
2017, 139, 5952.
13 Q. Liao, N. Saffon-Merceron, N. Mézailles, ACS Catal., 2015,
5
14 (a) J. L. Crossland, D. R. Tyler, Coord. Chem. Rev., 2010, 254
, 6902.
,
1883; (b) N. Hazari, Chem. Soc. Rev., 2010, 39, 4044.
15 A. Cavaillé, N. Saffon-Merceron, N. Nebra, M. Fustier-
CNRS and Université de Toulouse are acknowledged for
financial support. We are grateful to CalMip (CNRS, Toulouse,
France) for access to calculation facilities. We also thank Jean-
François Meunier for Mössbauer analyses, and Solvay for a
generous gift of phosphines.
Boutignon, N. Mézailles, Angew. Chem. Int. Ed., 2018, 57
1874.
16 (a) D. F. Evans, J. Chem. Soc., 1959, 2003; (b) G. A. Bain, J. F.
Berry, J. Chem. Educ., 2008, 85, 532.
17 L. D. Field, R. W. Guest, P. Turner, Inorg. Chem., 2010, 49
9086.
,
,
18 Z. Ouyang, J. Cheng, L. Li, X. Bao, L. Deng, Chem. Eur. J., 2016,
22, 14162.
19 Selected representative articles Mo: (a) H. Tanaka, A. Sasada,
T. Kouno, M. Yuki, Y. Miyake, H. Nakanishi, Y. Nishibayashi, K.
Yoshizawa, J. Am. Chem. Soc., 2011, 133, 3498; (b) Q. Liao, N.
Saffon-Merceron, N. Mézailles, Angew. Chem. Int. Ed., 2014,
53, 14206. Fe: (c) A. D. Piascik, P. J. Hill, A. D. Crawford, L. R.
Conflicts of interest
There are no conflicts to declare.
Doyle, J. C. Green, A. E. Ashley Chem. Commun., 2017, 53
,
Notes and references
7657; (d) G. Ung, J. C. Peters, Angew. Chem. Int. Ed., 2015,
54, 532; (e) R. Araake, K. Sakadani, M. Tada, Y. Sakai, Y. Ohki,
J. Am. Chem. Soc., 2017, 139, 5596; (f) M. Yuki, H. Tanaka, K.
Sasaki, Y. Miyake, K. Yoshizawa, Y. Nishibayashi, Nat.
1
(a) J. B. Howard, D. C. Rees, Chem. Rev., 1996, 96, 2965; (b)
B. K. Burgess, D. J. Lowe, Chem. Rev., 1996, 96, 2983; (c) B.
M. Hoffman, D. Lukoyanov, Z.-Y. Yang, D. R. Dean, L. C.
Seefeldt, Chem. Rev., 2014, 114, 4041.
Commun., 2012,
Knight, V. J. Catalano, R. García-Serres, L. J. Murray ACS
Catal., 2018, , 7208. (h) A. D. Piascik, R. Li, H. J. Wilkinson, J.
3, 1254. (g) R. B. Ferreira, B. J. Cook, B. J.
2
(a) M. D. Walter, in Adv. Organomet. Chem., Elsevier Inc.,
2016, pp. 261; (b) Y. Tanabe, Y. Nishibayashi, Chem. Rec.,
2016, 16, 1549.
8
C. Green, A. E. Ashley, J. Am. Chem. Soc., 2018, DOI:
10.1021/jacs.8b06999 Co: (i) R. B. Siedschlag, V. Bernales, K.
D. Vogiatzis, N. Planas, L. J. Clouston, E. Bill, L. Gagliardi, C. C.
Lu, J. Am. Chem. Soc., 2015, 137, 4638. (j) Y. Gao, G. Li, L.
Deng J. Am. Chem. Soc., 2018, 140, 2239.
3
4
D. V. Yandulov, R. R. Schrock, Science, 2003, 301, 76.
(a) K. Arashiba, Y. Miyake, Y. Nishibayashi, Nat. Chem., 2011,
3
, 120; (b) H. Tanaka, K. Arashiba, S. Kuriyama, A. Sasada, K.
Nakajima, K. Yoshizawa, Y. Nishibayashi, Nat. Commun.,
2014, , 3737; (c) K. Arashiba, E. Kinoshita, S. Kuriyama, A.
5
20 A (P2P2)Fe(N2) complex is reported to give 5.4 equiv. of
N(SiMe3)3 under 1 atm of N2, and 65 equiv. under 100 atm.:
D. E. Prokopchuk, E. S. Wiedner, E. D. Walter, C. V. Popescu,
N. A Piro, W. S. Kassel, R. M. Bullock, M. T. Mock J. Am.
Chem. Soc., 2017, 139, 9291.
Eizawa, K. Nakajima, H. Tanaka, K. Yoshizawa, Y.
Nishibayashi, J. Am. Chem. Soc., 2015, 137, 5666; (d) A.
Eizawa, K. Arashiba, H. Tanaka, S. Kuriyama, Y. Matsuo, K.
Nakajima, K. Yoshizawa, Y. Nishibayashi, Nat. Commun.,
2017,
8, 14874. (e) K. Arashiba, A. Eizawa, H. Tanaka, K.
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/C8CC07466F
Table of Contents entry
Mechanistic investigations of the catalyzed reduction of N2 with a rare (tridentate
phosphine)Fe(0) bis dinitrogen complex.
1