Side-on Coordination in Isostructural Nitrous Oxide and Carbon Dioxide Complexes of Nickel

Article abstract of DOI:10.1002/anie.202011301

A nickel complex incorporating an N₂O ligand with a rare η²-N,N′-coordination mode was isolated and characterized by X-ray crystallography, as well as by IR and solid-state NMR spectroscopy augmented by ¹⁵N-labeling experi

Full text of DOI:10.1002/anie.202011301

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Accepted Article
Title: Side-on Coordination in Isostructural Nitrous Oxide and Carbon
Dioxide Complexes of Nickel
Authors: Braulio Michele Puerta Lombardi, Chris Gendy, Benjamin S.
Gelfand, Guy M. Bernard, Roderick E. Wasylishen, Heikki M.
Tuononen, and Roland Roesler
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.202011301
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10.1002/anie.202011301
Angewandte Chemie International Edition
COMMUNICATION
Side-on Coordination in Isostructural Nitrous Oxide and Carbon
Dioxide Complexes of Nickel
Braulio M. Puerta Lombardi,[a] Chris Gendy,[a] Benjamin S. Gelfand,[a] Guy M. Bernard,[b] Roderick E.
Wasylishen,[b] Heikki M. Tuononen,*[c] and Roland Roesler*[a]
In memoriam: Professor Suning Wang
[a]
Braulio M. Puerta Lombardi, Dr. Chris Gendy, Dr. Benjamin S. Gelfand, Prof. Roland Roesler
Department of Chemistry
University of Calgary
2500 University Drive NW, Calgary, AB, T2N 1N4 Canada
E-mail: roesler@ucalgary.ca
[b]
[c]
Dr. Guy M. Bernard, Prof. Roderick E. Wasylishen
Gunning-Lemieux Chemistry Centre
University of Alberta
11227 Saskatchewan Drive NW, Edmonton, AB, T6G 2G2, Canada
Prof. Heikki M. Tuononen
Department of Chemistry, Nanoscience Centre
University of Jyvӓskylӓ
FI-40014 Jvӓskylӓ, Finland
E-mail: heikki.m.tuononen@jyu.fi
Supporting information for this article is given via a link at the end of the document.
Abstract: A nickel complex incorporating an N2O ligand with a rare
η2-N,N’-coordination mode was isolated and characterized by X-ray
crystallography, as well as by IR and solid-state NMR augmented by
15N-labeling experiments. The isoelectronic nickel CO2 complex
reported for comparison features a very similar solid-state structure.
Computational studies revealed that η2-N2O binds to nickel slightly
stronger than η2-CO2 in this case, and comparably to or slightly
stronger than η2-CO2 to transition metals in general. Comparable
transition state energies for the formation of isomeric η2-N,N’- and η2-
means that N2O persists in the atmosphere for an average of
117(8) years.9 Consequently, interest towards using N2O as a
synthon,10 as well as towards catalyzing its decomposition into
elements has increased in recent years, 11 in turn prompting
investigations meant to elucidate the interaction of this prominent
small molecule with metals.
O
N
N
O
N
N
O
N
N
V
N
2+
Mes
Mes
tBu2P
Rh
tBu2P
E
N
E
Mes
Me
N
Me
Ph
N
N,O-complexes, and
a
negligible activation barrier for the
H3N
H3N
NH3
Cl
O
N N
N
N
Ru
Ru
Cl
decomposition of the latter likely account for the limited stability of the
N2O complex.
NH3
P
PPh3
NH3
Ph
A
B
C
D
E = CH2, O
Taube 1969
James 2001
Chang 2011
Chaplin 2019
Among the numerous oxides of nitrogen, nitrous oxide (N2O) is
most intimately intertwined with modern human activities. It
figures on the WHO's List of Essential Medicines for use in pain
management,1 and it also has a long history as a recreational
drug dubbed “laughing gas”.2 It is used as an oxidant (“nitrous”) in
racing engines and is a suitable propellant in rockets,3 as well as
in whipped cream and cooking oil canisters. Industrially, N2O is
an important by-product in nitric acid and adipic acid
manufacturing. 4 Although industrial pollutants are not to be
neglected, natural, enzymatic denitrification processes5 are the
main source of N2O in the environment and for this reason the gas
was proposed to be part of the biosignature of life on exoplanets.6
The widespread use of nitrogen fertilizers led to an enhancement
of denitrification processes and N2O rose to prominence as a
greenhouse gas 300 times more potent than CO2, and “the
O
Dipp
N
N
Dipp
N
C(CF3)3
N
Co
Ni
Tipp
O
O
N
O
C(CF3)3
C
O
N N Cu
Al
N
N
N
N
O
O
C(CF3)3
Si
C(CF3)3
Tipp
Figueroa 2019
E
F
3
Malinowski 2018
This work
Figure 1. Transition metal complexes of N2O.
N2O reacts readily with numerous metal complexes and organic
substrates, mostly as an oxidant but also as a nitrogen atom
donor,4,10 and can be trapped by frustrated Lewis pairs12 and N-
heterocyclic carbenes (NHCs).13 Its reactivity involving insertion
into M-C and M-H bonds is well documented.10,14 In contrast to its
dominant ozone-depleting substance emitted in the 21st
isoelectronic counterpart CO2, however, which has
a rich
7
coordination chemistry,15 N2O has been generally described as a
poor, or exceedingly poor ligand due to its weak σ-donating and
π-accepting properties, low polarity, and oxidizing character.8b,16
Century”.
Although its decomposition into elements is
thermodynamically favorable (ΔfH°gas 82.1 kJ mol-1), the high
activation barrier (250 kJ mol-1)8 associated with this process
1
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10.1002/anie.202011301
Angewandte Chemie International Edition
COMMUNICATION
Extensive investigations of ruthenium derivative A (Figure 1),
which remained for more than three decades the only known
metal complex of nitrous oxide, revealed that N2O coordinated in
a linear fashion via the terminal nitrogen and was a poor ligand
susceptible to reduction and displacement.17 These conclusions
Prepared by deprotonation of its bis(imidazolium) precursor,
ligand 1 reacted with Ni(cod)2 to yield (1)Ni(η2-cod), 2. Solution 1H
NMR analysis of 2 revealed a broad, complex spectrum denoting
C1 symmetry, reflected in the 13C NMR spectrum by the presence
of two resonances for the coordinated carbene carbons (200.4
and 208.4 ppm). Reduced conformational fluxionality in
complexes containing bis(NHC)Ni fragments was shown to lead
to broad, poorly resolved resonances in the solution NMR spectra,
as well as lowering of the expected time-averaged symmetry.27
An X-ray diffraction experiment on 2 confirmed chelation of the
ligand to Ni in a bent geometry (C1-Ni1-C8 107.9(1)°) (Figure
S30) and the η2-coordination of 1,5-cyclooctadiene.
were supported by computational studies,17c,18 the spectroscopic
19
characterization of complex B,
as well as the NMR
characterization of surface-coordinated N2O.20 Confirmation of
these findings was provided over the last decade by the
comprehensive characterization of discrete, end-on bonded
complexes C, D and E. (Figure 1).21,22,23 The rich coordination
chemistry of CO2 suggests that the isoelectronic N2O molecule
should also be able to adopt a bent, N,N’-side-on coordination
mode, which had been probed computationally for surface
binding.24 Linear N2O bound at the [4Cu:2S] active site of nitrous
oxide reductase has been shown to display long, side-on CuꞏꞏꞏN
contacts.25 Ultimately, the first η2-N,N’-N2O complex F, which was
persistent below -25 °C, was recently characterized and the π-
basicity of the metal was shown to be key to its isolation.26
Table 1. Selected 15N NMR resonances for free and bound N2O.
Cpd.
N2O26
tol-d8
135
B19
D[a],22
DFB[d]
109
D[b],22
DFB[d]
103
F26
3
3[c]
Solv.
δNterm
δNcent
CD2Cl2
126
tol-d8
159
309
solid
312
365
gas
313
395
218
245
246
O
2-cod)
N
N
Dipp
N
Dipp
N
Dipp
N
Dipp
N
Dipp
N
Dipp
N
Ni
Ni
Ni(cod)2
N2O
[a] E = CH2. [b] E = O. [c] computed. [d] DFB = 1,2-F2C6H4.
o-xylene
- 1,5-COD
- 2,5-COD
N
N
N
N
N
N
Si
Si
In solution, complex 2 reacted with 1 atm of N2O at room
temperature to yield 3, which was isolated as a yellow crystalline
Si
2
43%
1
71%
61%
3
CO2
THF
- 1,5-COD
solid (Scheme 1). The low solubility of
3 precluded its
KHMDS
toluene
- 2 KBF4
Dipp
characterization in solution. As a solid, it can be stored for months
at -78 °C and handled at room temperature in vacuum or under
an inert atmosphere, but partial decomposition is apparent after
12 hours at room temperature (by IR). Heating to 70 °C in THF
leads to dissolution upon N2 development (Figure S3). The 13C
O
N
Dipp
N
Dipp
N
O
C
Dipp
N
Dipp
O
N
Dipp
N
N
H
N
N
Ni
Ni
H
N
N
N
N
N
2 BF4
Si
Si
Si
5
4
73%
CP-MAS NMR spectrum of
3 (Figure S19) features two
resonances corresponding to the coordinated carbene carbons at
183.7 and 192.5 ppm, similar to the values measured in solution
for 2.
Scheme 1. Synthesis of compounds 1 – 3 and 5, and the postulated, fleeting
η2-N,O-isomer 4. Dipp = 2,6-diisopropylphenyl.
We reported on a bis(NHC)2Ni0
–GeCl2 complex incorporating a
(NHC)2Ni0 fragment with a bent L2M geometry.27 Computational
studies indicated that this fragment featured the frontier orbitals
necessary for efficient η2-interactions with π-acidic ligands.28,18c
Thus, we hypothesized that a bis(NHC)2 supported Ni0 would be
an excellent candidate for stabilizing side-on, η2-N2O complexes,
especially taking into account the immunity of NHC ligands to
oxidation. Design of ligand 1, incorporating a shorter silane linker,
aimed to impose a narrow CNHC-Ni-CNHC angle and increase the
π-basicity of the metal. 29 This allowed us to characterize
analogous η2-bound Ni0 complexes of N2O and CO2 and to assess
the relative binding ability of the two ligands for the first time.
Figure 3. Overlaid FT-IR spectra for 3 and 3-(15N2) (99% isotopically enriched)
with spectral difference bellow.
The 15N CP-MAS NMR resonances for bound N2O in an
isotopically enriched sample of 3 were observed at 365 and 312
ppm (Figure 2), corresponding to the central and terminal nitrogen
atoms in N2O, respectively (vs. the gas phase computed values
of 395 and 313 ppm). These values are significantly deshielded
compared to those observed in the κ1-N- and the η2-N,N’-N2O
complexes, as well as those for free N2O (Table 1). Resonances
Figure 2. 15N CP-MAS NMR spectrum of 3 containing 33% 15N2O, the latter
prepared using an original method (see Supporting Information).
2
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10.1002/anie.202011301
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COMMUNICATION
corresponding to the naturally abundant nitrogen atoms in the
imidazole rings appear between 187.5-190.4 ppm, matching
literature data for NHC ligands.30 Infrared spectroscopy suggests
that N2O is side-on, η2-N,N’-coordinated in 3. The observed νNN
stretching and νNNO bending vibrations (Figure 3) at 1533 and
1138 cm-1, respectively (vs. the gas phase computed values of
1725 and 1243 cm-1, and the experimental values for F of 1624
and 1131 cm-1) shift to lower frequencies (1495 and 1121 cm-1) in
15N-enriched samples of 3. The νNN stretching vibration measured
in 3 is the lowest value observed in N2O metal complexes, both
κ1-N (2234-2303 cm-1 for νNN and 1150-1337 cm-1 for νNO in A –
E) and η2-N,N’-N2O (1624 cm-1 for νNN and 1131 cm-1 for νNNO in
F), in agreement with the high π-basicity of the (1)Ni0 fragment
and its strong interaction with the π* system of N2O.
X-ray crystallography revealed for 3 the expected, bent (1)Ni
fragment (C-N-C 104.47(13)°) with the side-on, η2-N,N’-
coordinated N2O ligand completing the coordination sphere of
nickel (Figure 4). The metric parameters characterizing the N2O
moiety (N5-N6 1.225(4) Å and N5-O1 1.276(4) Å) are consistent
with the calculated values and compare well with the N-N bond
length measured in F (1.212(8) Å). The nickel substituents are
coplanar, with the plane of the N2O ligand forming an angle of
8.4(3)° with the CNHCNiCNHC plane.
the energies are even greater, at 129 (74) kJ mol-1. Furthermore,
an energy decomposition analysis with ETS-NOCV revealed that
the instantaneous interaction energies of L in (1)Ni(L) follow a
similar trend, largely owing to the significantly stronger orbital
interactions (in parathesis): -401 (-643) and -415 (-709) kJ mol-1
for L = CO2 and N2O, respectively. The total orbital interaction
term can further be decomposed using NOCV, showing a
dominant contribution (83 % for 3 and 84 % for 5) involving
donation from the metal to the π* system of the ligand. Taken as
a whole, the results of the DFT calculations indicate that N2O
binds to (1)Ni0 slightly stronger than CO2 due to stronger orbital
interactions in 3. To probe whether the observed energetic trend
is more general, the equilibrium TM-CO2 + N2O ⇌ TM-N2O + CO2
(TM = transition metal fragment) was analyzed computationally
for 12 crystallographically characterized η2-C,O-CO2 complexes
and their hypothetical N2O analogues. The data (Table S2)
showed stronger binding for N2O in 9 systems (up to 26 kJ mol-1)
demonstrating that when bound in η2-fashion, N2O is
a
comparable or slightly better π-acceptor than CO2. However, it
needs to be stressed that N2O is oxidizing whereas CO2 is not, for
which reason the increased binding energy in the hypothetical
N2O systems considered above is unlikely to stabilize η2-N,N-N2O
complexes over metal or ligand oxidation.
Figure 5. Solid-state structure of 5 with 50% thermal ellipsoids, and hydrogen
atoms omitted. Selected bond lengths (Å) and angles (°) with [calculated
values]: O1-C35 1.283(4) [1.264], C35-O2 1.218(4) [1.206], Ni1-O1 1.949(2)
[1.937], Ni-C35 1.828(3) [1.839], Ni1-C1 1.973(3) [1.964], Ni1-C8 1.866(2)
[1.856], O1-C35-O2 134.6(3) [137.5], C1-Ni1-C8 106.95(10) [109.4].
Figure 4. Solid-state structure of one of the two independent molecules of 3
with 50% thermal ellipsoids, and hydrogen atoms omitted. Selected bond
lengths (Å) and angles (°) with [calculated values]: N5-N6 1.225(4) [1.210], N5-
O1 1.276(4) [1.239], Ni1-N5 1.803(3) [1.821], Ni-N6 1.926(3) [1.910], Ni1-C1
1.901(3) [1.934], Ni1-C8 1.893(3) [1.919], N5-N6-O1 134.7(3) [138.4], C1-Ni1-
C8 104.47(13) [107.7].
The energy landscape for the formation of 3 from (1)Ni0 and N2O
was also probed with computational methods (Figure S33). The
results revealed that the formation of 3 involves a modest barrier
(ΔG‡ = 38 kJ mol-1), with ΔG° = -56 kJ mol-1. The formation of the
η2-O,N-N2O isomer, 4, though not observed experimentally, was
found to involve a greater barrier (ΔG‡ = 70 kJ mol-1) and a minute
ΔG° of -2 kJ mol-1. However, 4 appears to be a metastable
species and readily converts to (1)NiO(N2) almost without a
barrier. Barrierless decomposition of η2-O,N-N2O bound to iron
has been investigated computationally and matched experimental
observations. 31 Thus, at a relative energy of -63 kJ mol-1,
(1)NiO(N2) represents the lowest energy point on the potential
energy surface and confirms that metal-oxo formation is
thermodynamically favored over η2-N,N-N2O complex formation,
albeit only by 7 kJ mol-1. As suggested by the calculated energy
landscape, 3, unlike 5, is a kinetic, not a thermodynamic, product,
in agreement with its limited stability. Similarly, decomposition of
F was reported to proceed via formation of a reactive metal−oxo
species and transfer of oxygen to the ancillary isocyanide ligand.26
Aiming to provide a comparison for 3, its CO2 analog 5 was
prepared by reaction of 2 with 1 atm of CO2 in THF. The product
was stable under an inert atmosphere and did not dissolve in
hydrocarbon and ethereal solvents. The solid-state 13C NMR
spectrum of 5 (Figure S21) is very similar to the spectrum of 3,
featuring two carbene resonances (188.2 and 192.2 ppm) and a
resonance corresponding to the CO2 ligand (167.3 ppm). A
characteristic νCO stretching vibration is observed in the IR
spectrum of 5 at 1695 cm-1 (vs. the gas phase computed value of
1855 cm-1). The solid-state structure of 5 is very similar to that of
3 (Figure 5). The bond angles in the coordinated CO2 and N2O
match closely (∠NNO 134.7(3) in 3 vs. ∠OCO 135.0(2)° in 5) but
differences are apparent in the bond distances to their terminal
atoms (N5-O1 1.275(3) Å in 3 vs. C35-O2 1.217(3) Å in 5).
A DFT computational comparison of the binding energies of L in
(1)Ni(L) (with ΔG° in parenthesis) yielded values of 87 (33) and
110 (56) kJ mol-1 for L = CO2 and N2O, respectively, while for a
hypothetical complex of (1)Ni with the classic π-acceptor ethylene,
3
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10.1002/anie.202011301
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COMMUNICATION
To summarize, employing the π-basic fragment (1)Ni, we isolated
3 by reaction of 2 with N2O. The rare η2-N,N’-coordination mode
of the N2O ligand in 3 was proved by single-crystal X-ray
crystallography, as well as 15N CP-MAS NMR and IR
spectroscopy aided by 15N isotopic enrichment. The isostructural,
η2-CO2 complex 5 was also synthesized, allowing a direct
comparison of the metal binding properties of the two
isoelectronic small molecules of environmental relevance.
Computational studies indicate that π-acceptance is the main
contributor to N2O binding in 3, and place the η2-N,N’-metal
binding ability of this ligand to the (1)Ni fragment in-between that
of CO2 and ethylene. In general, the η2-N,N’-binding ability of N2O
to transition metals is found to be comparable to, or slightly better
than that of CO2. This demonstrates that the need for a strongly
π-basic metal fragment comes not so much from the frequently
invoked “poor σ-donating and π-accepting properties” of N2O, but
from the need to stabilize η2-N,N’-coordination over the
thermodynamically more favorable metal-oxo formation. The well-
known oxidizing character of N2O may be mostly, if not entirely
responsible for the scarcity of η2-metal complexes employing this
ligand, and more of such complexes are expected to be in reach
in complex designs featuring the right balance of π-basicity and
resilience to oxidation at the metal center and associated ligands.
Acknowledgements
Financial support was provided by the Universities of Calgary,
Jyväskylä, and Alberta, as well as the NSERC of Canada in the
form of Discovery Grants #2019-07195 to R.R. and #2019-06816
to R.E.W. The project received funding from the European
Research Council under the EU's Horizon 2020 programme
(grant #772510 to H.M.T). R.E.W acknowledges the CFI and the
Government of Alberta for NMR Facilities support. Computational
resources were provided by the Finnish Grid and Cloud Infra-
structure
(persistent
identifier
urn:nbn:fi:research-infras-
2016072533) and the University of Calgary.
Conflict of interest
The authors declare no conflict of interest.
Keywords: nickel • nitrous oxide • carbon dioxide • N-
heterocyclic carbene • back bonding
[1]
World Health Organization. World Health Organization model list of
essential medicines: 21st list 2019. 2019 Geneva: World Health
Organization.
T. Kuschel, C. Näther, V. K. K. Praneeth, O. Sander, N. Lehnert, Inorg.
Chem. 2004, 43, 6979−6994.
[18] a) D. F.-T. Tuan, R. Hoffmann, Inorg. Chem. 1985, 24, 871−876; b) H.
Yu, G. Jia, Z. Lin, Organometallics 2008, 27, 3825–3833; c) J. G. Andino,
K. G. Caulton, J. Am. Chem. Soc. 2011, 133, 12576-12576.
[19] C. B. Pamplin, E. S. F. Ma, N. Safari, S. J. Rettig, B. R. James, J. Am.
Chem. Soc. 2001, 123, 8596–8597.
[2]
[3]
M. Laing, S. Afr. J. Sci. 2003, 99, 109-114.
V. Zakirov, M. Sweeting, T. Lawrence, J. Sellers, Acta Astronautica, 2001,
48, 353–362.
[4]
[5]
V. N. Parmon, G. I. Panov, A. Uriarte, A. S. Noskov, Catal. Today 2005,
100, 115–131.
[20] a) S. Hu, T. M. Apple, J. Catal. 1996, 158, 199-204; b) V. M. Mastikhin,
I. L. Mudrakovsky, S. V. Filimonova, Chem. Phys. Lett. 1988, 149, 175-
179; c) V. M. Mastikhin, I. L. Mudrakovsky, S. V. Filimonova, Zeolites
1990, 10, 593-597.
a) N. Lehnert, H. T. Dong, J. B. Harland, A. P. Hunt, C. J. White, Nat.
Rev. Chem. 2018, 2, 278–289.
[6]
[7]
a) J. L. Grenfell, Phys. Rep. 2017, 713, 1-17.
A. R. Ravishankara, J. S. Daniel, R. W. Portmann, Science 2009, 326,
123–125.
[21] N. A. Piro, M. F. Lichterman, W. H. Harman, C. J. Chang, J. Am. Chem.
Soc. 2011, 133, 2108–2111.
[8]
[9]
a) A. H. H. Chang, D. R. Yarkony, J. Chem. Phys. 1993, 99, 6824-6831;
b) W. C. Trogler, Coord. Chem. Rev. 1999, 187, 303-327.
M. J. Prather, J. Hsu, N. M. DeLuca, C. H. Jackman, L. D. Oman, A. R.
Douglass, E. L. Fleming, S. E. Strahan, S. D. Steenrod, O. A. Søvde, I.
S. A. Isaksen, L. Froidevaux, B. Funke, J. Geophys. Res. Atmos. 2015,
120, 5693–5705.
[22] M. R. Gyton, B. Leforestier, A. B. Chaplin, Angew. Chem. Int. Ed. 2019,
58, 15295-15298.
[23] V. Zhuravlev, P. J. Malinowski, Angew. Chem. Int. Ed. 2018, 57, 11697–
11700.
[24] b) A. Heyden, B. Peters, A. T. Bell, F. J. Keil, J. Phys. Chem. B 2005,
109, 1857−1873; a) C.-L. Hu, Y. Chen, J.-Q. Li, Y.-F. Zhang, Chem. Phys.
Lett. 2007, 438, 213–217.
[10] K. Severin, Chem. Soc. Rev. 2015, 44, 6375–6386.
[11] M. Konsolakis, ACS Catal. 2015, 5, 6397−6421.
[25] A. Pomowski, W. G. Zumft, P. M. H. Kroneck, O. Einsle, Nature 2011,
477, 234−237.
[12] a) E. Otten, R. C. Neu, D. W. Stephan, J. Am. Chem. Soc. 2009, 131,
9918–9919; b) R. C. Neu, E. Otten, A. Lough, D. W. Stephan, Chem. Sci.
2011, 2, 170–176; c) M. J. Kelly, J. Gilbert, R. Tirfoin, S. Aldridge, Angew.
Chem., Int. Ed. 2013, 52, 14094–14097.
[26] C. C. Mokhtarzadeh, C. Chan, C. E. Moore, A. L. Rheingold, J. S.
Figueroa, J. Am. Chem. Soc. 2019, 141, 15003−15007.
[27] C. Gendy, A. Mansikkamäki, J. Valjus, J. Heidebrecht, P. C.-Y. Hui, G.
M. Bernard, H. M. Tuononen, R. E. Wasylishen, V. K. Michaelis, R.
Roesler, Angew. Chem. Int. Ed. 2019, 58, 154–158.
[13] a) A. G. Tskhovrebov, E. Solari, M. D. Wodrich, R. Scopelliti, K. Severin,
Angew. Chem. Int. Ed. 2012, 51, 232–234; b) A. G. Tskhovrebov, B.
Vuichoud, E. Solari, R. Scopelliti, K. Severin, J. Am. Chem. Soc. 2013,
135, 9486–9492.
[28] a) T. Ziegler, Inorg. Chem. 1985, 24, 1547-1552; b) L. P. Wolters, F. M.
Bickelhaupt in Structure and Bonding (Eds.: O. Eisenstein, S.
Macgregor), Springer, Berlin, 2014.
[14] a) G. A. Vaughan, P. B. Rupert, G. L. Hillhouse, J. Am. Chem. Soc. 1987,
109, 5538−5539; b) G. A. Vaughan, C. D. Sofield, G. L. Hillhouse, A. L.
Rheingold, J. Am. Chem. Soc. 1989, 111, 5491−5493.
[29] a) C. Massera, G. Frenking, Organometallics 2003, 22, 2758-2765; b) F.
Hering, J. Nitsch, U. Paul, A. Steffen, F. M. Bickelhaupt, U. Radius, Chem.
Sci. 2015, 6, 1426–1432.
[15] a) A. Pastor, A. Montilla, F. Galindo, Adv. Organomet. Chem. 2017, 68,
1-91; b) A. Paparo, J. Okuda, Coord. Chem. Rev. 2017, 334, 136-149.
[16] W. B. Tolman, Angew. Chem. Int. Ed. 2010, 49, 1018-1024.
[17] a) J. N. Armor, H. Taube, J. Am. Chem. Soc. 1969, 91, 6874-6876; b) F.
Bottomley, W. V. F. Brooks, Inorg. Chem. 1977, 16, 501-502; c) F. Paulat,
[30] A. J. Arduengo, R. L. Harlow, M. Kline, J. Am. Chem. Soc. 1991, 113,
361–363.
[31] a) P. B. Armentrout, L. F. Halle, J. L. Beauchamp, J. Chem. Phys. 1982,
76, 2449–2457; b) L. Zhao, Y. Wang, W. Guo, H. Shan, X. Lu, T. Yang,
J. Phys. Chem. A 2008, 112, 5676–5683.
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10.1002/anie.202011301
Angewandte Chemie International Edition
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The characterization of η2-N,N’-N2O and CO2 complexes of nickel and the associated computational study reveal that the bonding
ability of N2O to nickel is intermediate between that of CO2 and that of H2C=CH2. It is shown that in general, N2O η2-binds to metals
comparably to, or stronger than CO2, indicating that the rarity of η2-N2O metal complexes is due mostly to its oxidizing character and
not to its weak σ-donating and π-accepting properties.
Institute and/or researcher Twitter usernames: @RolandRoesler, @ChrisGendy, @UC_Chem
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