Lewis acid promoted dehydration of amides to nitriles catalyzed by [PSiP]-pincer iron hydrides

Article abstract of DOI:10.1002/aoc.5466

The dehydration of primary amides to their corresponding nitriles using four [PSiP]-pincer hydrido iron complexes 1–4 [(2-Ph₂PC₆H₄)₂MeSiFe(H)(PMe₃)₂ (1), (2-Ph₂PC₆H₄)₂HSiFe(H)(PMe₃)₂ (2), (2-(iPr)₂PC₆H₄)₂HSiFe(H)(PMe₃)₂ (3) and (2-(iPr)₂PC₆H₄)₂MeSiFe(H)(PMe₃)₂ (4)] as catalysts in the presence of (EtO)₃SiH as dehydrating reagent was explored in the good to excellent yields. It was proved for the first time that Lewis acid could significantly promote this catalytic system under milder reaction conditions than other Lewis acid-promoted system, such as shorter reaction time or lower reaction temperature. This is also the first example that dehydration of primary amides to nitriles was catalyzed by silyl hydrido iron complexes bearing [PSiP]-pincer ligands with Lewis acid as additive. This catalytic system has good tolerance for many substituents. Among the four iron hydrides 1 is the best catalyst. The effects of substituents of the [PSiP]-pincer ligands on the catalytic activity of the iron hydrides were discussed. A catalytic reaction mechanism was proposed. Complex 4 is a new iron complex and was fully characterized. The molecular structure of 4 was determined by single crystal X-ray diffraction.

Full text of DOI:10.1002/aoc.5466

Received: 29 October 2019
DOI: 10.1002/aoc.5466
Revised: 19 December 2019
Accepted: 25 December 2019
F U L L P A P E R
Lewis acid promoted dehydration of amides to nitriles
catalyzed by [PSiP]-pincer iron hydrides
Guoliang Chang1 | Xiaoyan Li1
Yajie Wang1 | Hongjian Sun1
| Peng Zhang1 | Wenjing Yang1 | Kai Li1
| Olaf Fuhr2 | Dieter Fenske2
|
1School of Chemistry and Chemical
The dehydration of primary amides to their corresponding nitriles using four
[PSiP]-pincer hydrido iron complexes 1–4 [(2-Ph2PC6H4)2MeSiFe(H)(PMe3)2
(1), (2-Ph2PC6H4)2HSiFe(H)(PMe3)2 (2), (2-(iPr)2PC6H4)2HSiFe(H)(PMe3)2 (3)
and (2-(iPr)2PC6H4)2MeSiFe(H)(PMe3)2 (4)] as catalysts in the presence of
(EtO)3SiH as dehydrating reagent was explored in the good to excellent yields.
It was proved for the first time that Lewis acid could significantly promote this
catalytic system under milder reaction conditions than other Lewis acid-
promoted system, such as shorter reaction time or lower reaction temperature.
This is also the first example that dehydration of primary amides to nitriles
was catalyzed by silyl hydrido iron complexes bearing [PSiP]-pincer ligands
with Lewis acid as additive. This catalytic system has good tolerance for many
substituents. Among the four iron hydrides 1 is the best catalyst. The effects of
substituents of the [PSiP]-pincer ligands on the catalytic activity of the iron
hydrides were discussed. A catalytic reaction mechanism was proposed. Com-
plex 4 is a new iron complex and was fully characterized. The molecular struc-
ture of 4 was determined by single crystal X-ray diffraction.
Engineering, Key Laboratory of Special
Functional Aggregated Materials, Ministry
of Education, Shandong University,
Shanda Nanlu 27, Jinan, 250100, People's
Republic of China
2Institut für Nanotechnologie (INT) und
Karlsruher Nano-Micro-Facility (KNMF),
Karlsruher Institut für Technologie (KIT),
Hermann-von-Helmholtz-Platz 1, 76344,
Eggenstein-Leopoldshafen, Germany
Correspondence
Hongjian Sun, School of Chemistry and
Chemical Engineering, Key Laboratory of
Special Functional Aggregated Materials,
Ministry of Education, Shandong
University, Shanda Nanlu 27, Jinan
250100, China.
Email: hjsun@sdu.edu.cn
Funding information
National Natural Science Foundation of
China, Grant/Award Numbers: 21372143,
21572119
K E Y W O R D S
amide, dehydration, iron hydride, Lewis acid, nitrile
1 | INTRODUCTION
documented and promising strategies for synthesis of
nitriles. At the beginning, the precious metals as cata-
Nitrile group, as one of the key structural motifs, is an
important class of functionalities in organic and indus-
trial chemistry, advanced materials, pharmaceuticals,
pigments and agrichemicals.[1–5] Therefore, the develop-
ment of synthetic strategies toward nitriles is attracting
continuous interest of chemists. In traditional synthetic
methods, stoichiometric acidic dehydrating or basic
reagents.[2,6] azides,[6–8] or amine oxidation reagents[9]
were used. However, the drawbacks of these processes
are obvious, such as harsh reaction conditions, toxic
reagents and unfavorable formation of side products.
The dehydration of primary amides catalyzed by transi-
tion metal complexes represents one of the well-
lysts were used for this process.[10,11] Nevertheless, due
to the toxicity and high prices of the precious metals,
people have begun to look for cheap metal catalyst. Dur-
ing last decades, several cheaper and less-toxic catalysts
have been applied in the dehydration of primary amides
to nitriles.[12–14] Especially, iron complexes have becom-
ing more and more attractive for chemists because of
high abundance, low-cost and environmental friendli-
ness.[13] In 2011, Sortais and Darcel reported a well-
defined NHC iron complex catalyzed dehydration of
amides to nitriles and investigated the related mecha-
nism.[15] In the same year, Enthaler described the iron-
catalyzed dehydration of amides using M-methyl-N-
Appl Organometal Chem. 2020;e5466.
wileyonlinelibrary.com/journal/aoc
© 2020 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.5466

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CHANG ET AL.
(trimethylsilyl)trifluoroacetamide (MSTFA) as the dehy-
dration reagents.[16] Moreover, we have made some
achievements in the field of dehydration of amides to
nitriles with hydrido iron complexes as catalysts. In
2016, we disclosed that hydrido thiophenolato iron
(II) complexes could be used as efficient catalysts for
dehydration of primary amides to nitriles.[17] After two
years, we found that dehydration of amides to nitriles
could also be catalyzed by silyl hydrido iron
(II) complexes in good to excellent yields.[18] Meanwhile,
it was confirmed that MSTFA as dehydration reagent is
an excellent trimethylsilyl-transfer compound.[19,20] The
fluoride-catalyzed (metal-free) dehydration of primary
amides using silanes as dehydrating reagents was publi-
shed by Beller's group.[21] In 2011, Enthaler also
described a copper-catalyzed dehydration of primary
amides to form nitriles.[22] Last year, Buchwald pres-
ented a silylative dehydration of primary amides to
nitriles using copper-hydrides as catalyst.[23]
Over the years, it has been known that Lewis acids
can promote some metal catalyzed organic transforma-
tions.[24,25] Lewis acids were also used for dehydration of
amides to nitriles[14,20,26] but more stringent reaction con-
ditions, such as higher temperature or longer reaction
time, limit their application. It was also found that pri-
mary amides could transfer to the related nitriles by
ZnCl2 in CH3CN/H2O medium under microwave irradia-
tion.[27] After we have studied the dehydration of amides
to nitriles with hydrido iron or cobalt complexes as
catalysts,[7–18,28] now we want to know if Lewis acids can
promote these catalytic systems. Therefore, in order to
expand the scope of the application of these hydrido iron
complexes, four [PSiP]-pincer iron hydrides 1–4 were
synthesized (Figure 1) and their catalytic activities for
dehydration of amides to nitriles were explored. It was
also confirmed for the first time that Lewis acids could
promote this catalytic dehydration process. Among the
four iron hydrides, complex 4 is new. The influence of
the substituents at P and Si atom on the catalytic activity
of the iron hydrides were also discussed.
2 | RESULTS AND DISCUSSION
2.1 | Synthesis of [PSiP]-pincer iron
hydrides 1–4
Complexes 1–3 were prepared according to the literature
procedures.[29,30] Complex 4 was obtained from the com-
bination
of
bis(o-(diisopropylphosphino)phenyl)
ꢀ
methylsilane with Fe (PMe3)4 in THF at 0 C under Ar
atmosphere (Scheme 1). Complex 4 was fully character-
ized by 1H, 13C and 31P NMR, IR and X-ray diffraction as
SCHEME 1 Preparation of Complex 4
FIGURE 2 ORTEP plot of complex 4 at the 50% probability
level (most of hydrogen atoms are omitted for clarity). Selected
bond lengths (Å) and angles (deg): Fe1-P1 2.2362(1), Fe1-P2
2.2443(1), Fe1-P3 2.2713(1), Fe1-P4 2.2463(1), Fe1-Si1 2.3106(1),
Fe1-H1 1.53(2), P1-Fe1-P2 105.32(4), P1-Fe1-P3 99.92(4), P4-Fe1-P3
99.18(5), P4-Fe1-Si1 79.48(5), P1-Fe1-Si1 82.13(4), P1-Fe1-P3
99.92(4), P1-Fe1-P4 134.77(3), P1-Fe1-Si1 82.13(4), P3-Fe1-Si1
177.93(3), P2-Fe1-H1 177.50(9), Si1-Fe1-H1 92.40(9)
FIGURE 1 Selected silyl tridentate iron Complexes

HOMOGENEOUS CATALYSIS
3 of 8
well as elemental analysis. In the IR spectrum of 4, a typi-
cal ν (Fe-H) stretching band was found at 1839 cm−1. In
the H NMR spectrum of 4, a “td” signal at −14.56 ppm
for the hydrido H was formed by (PH)-coupling with four
P atoms (J (PH) = 18 and 75 Hz) while two doublets for
two PMe3 ligands were observed at 1.13 and 1.25 ppm,
respectively. This indicates that two PMe3 ligands are
chemically different. The spectroscopic characteristics are
comparable with those of complex 1.[30] In the 31P NMR
spectrum of 4 a “dt” peak at 1.7 and a multiplet peak at
6.3 ppm for the two PMe3 ligands and a doublet at
88.7 ppm for –PiPr2 groups were recorded in the integral
ratio of 1 (PMe3): 1 (PMe3): 2 (-PiPr2). The molecular
structure of 4 was determined by single crystal X-ray dif-
fraction (Figure 2).
Complex 4 has a distorted octahedral geometry with
an iron atom in the center. The axial bond angle
P2-Fe1-H1 is 177.50(9)o, deviated from 180o. The sum of
1
TABLE 1 Iron-catalyzed dehydration of p-chlorobenzamidea
Entry
1
Catalyst
Loading (mol%)
Silane
Solvent
THF
T(ꢀC)
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
40
60
60
25
40
Time(h)
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
6
Conv. (%)b
Yield (%)c
0
1
1
2
3
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
2
2
2
2
5
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
Et3SiH
0
79
74
71
69
92
65
55
59
57
51
60
60
51
50
70
37
72
53
43
61
32
57
66
11
30
2
THF
76
3
THF
70
4
THF
66
5
THF
65
6
THF
89
7
THF
59
8
THF
50
9
Ph2SiH
THF
54
10
11
12
13
14d
15e
16
17
18
19
20
21
22
23
24
25
26
Ph3SiH
THF
52
PhSiH3
THF
44
TMDS
THF
55
PMHS
THF
54
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
(EtO)3SiH
THF
47
THF
44
dioxane
benzene
DMSO
isopropanol
CH3Cl
CH2Cl2
THF
67
30
68
47
38
57
24
THF
51
THF
12
12
12
62
THF
<5
24
THF
aCatalytic reaction conditions: amide (1.0 mmol), (EtO)3SiH (3.0 mmol) and 1 (0.02 mmol) in 2 ml THF, T ꢀC, t h.
bDetermined by GC analysis. n-Dodecane as internal standard (1.0 mmol).
cIsolated yield.
d2 eq. Silane.
e4 eq. Silane.

4 of 8
CHANG ET AL.
equatorial coordination bond angles (P1-Fe1-P3 (99.92o),
P3-Fe1-P4 (99.18o), Si1-Fe1-P4 (79.48o) and Si1-Fe1-P1
(82.13o)) is 360.71o, slightly deviated from 360o. The
length of Fe1-H1 bond is 1.53(2) Å, almost same
(1.55(4) Å) with that of complex 1.[30] Among the four
Fe-P bonds Fe1-P3 (2.2713(1) Å) is the longest due to the
strongest trans-influence of the Si atom in comparison
with that of H and P atom.
No p-chlorobenzonitrile was detected in the absence of
catalyst (Entry 1, Table 1). 2 mol% of complex 1 could
afford 76% yield (Entry 2, Table 1). However, when com-
plex 1 was replaced by complexes 2–4, lower yields (65% -
70%) were obtained (Entries 3–5, Table 1) but the decline
from 2 to 3 is not significant. This result indicates that
the isopropyl groups at P atoms are not obviously benefi-
cial to reductive dehydration of primary amides to nitriles
in comparison to the phenyl groups (1 vs. 4; 2 vs 3) at P
atoms while the influence of the methyl group at Si atom
on the catalytic activity of the complexes is uncertain
(1 vs. 2; 4 vs. 3). When the catalyst loading was increased
to 5 mol%, the yield was increased to 89% (Entry
6, Table 1). With the decrease of the catalyst loading
(1 mol%) the yield (59%) declined significantly (Entry
7, Table 1). Surprisingly, the yields were greatly reduced
when (EtO)3SiH was replaced by other silanes, such as
Et3SiH, PhSiH3, Ph2SiH2, Ph3SiH, TMDS and PMHS as
the hydrogen sources (Entries 8–13, Table 1). Moreover,
no better yield could be obtained with 2 or 4 equiv. of
2.2 | Catalytic activities of complexes 1–4
The catalytic performance of complexes 1–4 was evalu-
ated for dehydration reduction of amides to nitriles. At
the beginning, p-chlorobenzamide as a model substrate
was treated with hydrosilane in the presence of catalytic
amount of the iron hydride in THF (Table 1). In order to
get optimized reaction conditions, a series of reaction
parameters, such as catalyst loading, solvent, reaction
temperature, silane and reaction time, were evaluated.
TABLE 2 Lewis acid-promoted dehydration of p-chlorobenzamidea
Entry
1
Catalyst
Loading (mol%)
Lewis Acid
ZnCl2
T(ꢀC)
25
60
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
Time (h)
8
Yield (%)b
38
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
-
2
2
2
2
2
2
2
2
2
2
2
2
2
1
2
2
2
0
2
ZnCl2
12
79
3
ZnCl2
12
77
4
ZnBr2
12
81
5
CuI
12
52
6
CuBr
12
<10
<10
<10
<10
<10
37
7
CuCl
12
8
Cu (acac)2
FeCl3
12
9
12
10
11
12
13
14
15
16
17
18
MgCl2
ZnBr2(8%)
ZnBr2(20%)
ZnBr2(50%)
ZnBr2
12
12
12
59
12
67
12
62
ZnBr2
24
85
ZnBr2
30
89
-
30
34
ZnBr2
30
0
aCatalytic reaction conditions: amide (1.0 mmol), (EtO)3SiH (3.0 mmol), Lewis acid (1.2 mmol) and 1 (0.02 mmol) in 2 ml THF, T ꢀC, t h.
bIsolated yield.

HOMOGENEOUS CATALYSIS
5 of 8
silane (Entries 14–15, Table 1). THF was proved to be the
best reaction medium in comparison with dioxane, ben-
zene, DMSO, isopropanol, CH3Cl and CH2Cl2 (Entries
16–21, Table 1). Lower reaction temperature brought
poorer yield (Entry 22, Table 1). When the reaction time
was shortened, the yield became worse (Entries 23 and
24, Table 1). When we compare the results of entries
25 and 26 in Table 1 with those of entries 1 and 3 in
Table 2, we can find that Lewis acids ZnCl2 promoted the
catalytic process obviously. When different Lewis acids
were added into this catalytic system, it was found that
ZnBr2 is the best Lewis acid for this catalytic system
(Entries 3–10, Table 2). When the mount of ZnBr2 was
decreased, the yields were decreased remarkably (Entries
11–13, Table 2). From entry 14 to entry 16 we can
conclude that the optimized catalytic conditions are:
complex 1 as catalyst, catalyst loading 2 mol%, ZnBr2 as
ꢀ
Lewis acid (1.2 equiv.), 40 C, 30 hr in THF. If we com-
pare entries 16 (Yield 89%) and 17 (Yield 34%) in Table 2,
we can know that Lewis acid ZnBr2 promoted this cata-
lytic reaction significantly. Without catalyst 1 the yield is
very poor in the presence of ZnBr2 (entry 18, Table 2).
Under the optimized reaction condition the scope of
the substrates for dehydration of amides to nitriles was
explored (Table 3). As shown in Table 3, aromatic, and
heteroaromatic as well as aliphatic nitriles could be pre-
pared in moderate to excellent yields from the
corresponding primary amides under the optimized con-
ditions. These results reveal that this catalytic system has
wide applicability for dehydration of amides to nitriles.
TABLE 3 The dehydration of amides to nitriles catalyzed by complex 1a,b
aCatalytic reaction conditions: amide (1.0 mmol), ZnBr2 (1.2 mmol) (EtO)3SiH (3.0 mmol) and complex 1 (0.02 mmol) in 2 ml THF, 40 ꢀC, 30 hr.
bIsolated yield.

6 of 8
CHANG ET AL.
SCHEME 2 A proposed catalytic
mechanism
Whether it is a substrate with electron-withdrawing
group (Cl- and F-) or with electron-donating group (Me-,
MeO- and -NH2), it has a good yield. p-Trifluoromethy-
lbenzamide has only 71% yield because –CF3 is a very
strong electron-withdrawing group. Cinnamonitrile was
synthesized from cinnamamide in 85% yield while C=C
bond remained unchanged. It must be noted that the
addition of Lewis acid played an important role for this
catalytic process. These results demonstrate that this cat-
alytic system has good tolerance for some substituents
and the catalytic conditions are milder than other Lewis
acid-promoted system, with shorter reaction time or
lower reaction temperature.[28–30]
H2. The interaction of A with (EtO)3SiH gives rise to
B and 1 through substitution. Intermediate C is formed
from the combination of B and 1. β-Elimination of
C delivers nitrile as the final product with the formation
of D. The ligand replacement of coordinated OSi (OEt)3
group by hydrido H produces ((EtO)3Si)2O with the
recovery of 1.
3 | CONCLUSIONS
[PSiP]-pincer hydrido iron complexes 1–4 were synthe-
sized and complex 4 is a new compound. The efficient
silane-based reductive dehydration of amides to nitriles
with complexes 1–4 as catalysts was explored in moder-
ate to excellent yields. It was proved for the first time
that Lewis acid could significantly promote this catalytic
system under milder reaction conditions than other
Lewis acid-promoted system, such as shorter reaction
time or lower reaction temperature. This is also the first
example that dehydration of primry amides to nitriles
was catalyzed by silyl hydrido iron complexes bearing
[PSiP]-pincer ligands with Lewis acid as additive. This
catalytic system has good tolerance for some substitu-
ents. The catalytic effect of [PSiP]-pincer ligand system
on the conversion of amide to nitrile is similar to that of
thiophenolato ligand system[17] and is better than that
2.3 | Catalytic mechanism
Based on the mechanism reported by Beller[31] and Buc-
hwald[23] we propose a mechanism in Scheme 2 for this
dehydration of amides to nitriles catalyzed by [PSiP]-
pincer iron hydrides. At the beginning of the catalytic
cycle, ZnBr2 as Lewis acid supports the tautomerization
of amide (F) to imine (E) form because the strong
electron-withdrawing ability of Lewis acid (ZnBr2)
makes the hydrogen atom on the hydroxyl group more
acidic. This is conducive to the first acid(H+)-base(H−)
reaction. E reacts with 1 to afford A with the release of

HOMOGENEOUS CATALYSIS
7 of 8
of selenophenolato ligand system.[32] A proposed mecha-
nism was discussed.
C6D6, 300 K, δ/ppm): 160.2 (Ar-C), 150.4 (Ar-C), 130.8
(Ar-C), 125.6 (Ar-C), 33.9–34.2 (m, PCHCH3), 32.4 (s, Si-
CH3), 27.6–29.9 (m, PCHCH3), 20.8 (d, J = 10.0 Hz,
PCH3), 20.1 (d, J = 24.0 Hz, PCH3).
4 | EXPERIMENTAL
4.1 | General procedures and materials
4.3 | X-ray crystal structure
determination
Standard vacuum techniques were used in the manipula-
tions of volatile and air-sensitive materials. Solvents were
dried by metal sodium and distilled under nitrogen
before use. Infrared spectra (4000–400 cm−1), as obtained
from Nujol mulls between KBr disks, were recorded on a
Bruker ALPHA FT-IR instrument. NMR spectra were
recorded using Bruker Avance 300 MHz spectrometers.
GC was recorded on a Fuli 9790 instrument. Melting
points were measured in capillaries sealed under N2 and
were uncorrected. Elemental analyses were carried out
on an Elementar Vario ELIII instrument. All the amides
were purchased and used without further purification.
Diffraction data were collected on a Bruker SMART
Apex II CCD diffractometer equipped with graphite-
monochromated Mo Kα radiation (λ = 0.71073 Å). The
crystal was kept at 298.15 K during data collection.
Using Olex2,[35] the structure was solved with the Sup-
erflip[36] structure solution program using Charge Flip-
ping and refined with the XL[37] refinement package
using Least Squares minimization. A summary of crystal
data, data collection parameters, and structure refine-
ment details is given in the Supporting Information.
CCDC-1571321 (4) contains the supplementary crystallo-
graphic data for this paper. Copies of the data can be
obtained free of charge on application to CCDC,
12 Union Road, Cambridge CB2 1EZ, UK (fax:
(+44)1223–336-033; e-mail: deposit@ccdc.cam.ac.uk).
The purity of the triethoxysilane used is 95%. Fe
[33]
(PMe3)4
and complexes 1–3[29,30] were prepared
according to literature procedures. The ligand of bis(o-
(diisopropylphosphino)phenyl)methylsilane was pre-
pared via a modified procedure according to the
literature.[34]
4.4 | Catalytic dehydration of primary
amides
4.2 | Synthesis of 4
The primary amide (1.0 mmol), Lewis acid (1.2 mmol)
and (EtO)3SiH (0.50 g, 3.0 mmol) were added into a
25 ml Schlenk tube containing a solution of catalyst in
2 ml of THF. The reaction mixture was stirred for
30 hr at 60 ꢀC or 40 ꢀC. The products were purified
according to literature procedures by Beller.[21] The
NMR of all products was listed in the Supporting
Information.
Under Ar, Fe (PMe3)4 (0.51 g, 1.41 mmol) in 30 ml tolu-
ene was added into
(diisopropylphosphino)phenyl)methylsilane
a
solution of ligand bis(o-
(0.60 g,
ꢀ
1.39 mmol) in 30 ml of toluene at 0 C. The mixture was
warmed slowly to room temperature and stirred at room
temperature for 24 hr. The toluene was discarded under
Ar. The residue was washed with n-pentane and diethyl
ether. Orange crystals (0.67 g, 82%) were obtained from
diethyl ether solution. Dec.: > 135 ꢀC. Anal. Calc. for
C31H58FeP4Si (638.62 g/mol): C, 58.30; H, 9.15. Found: C,
58.05; H, 9.40. IR (Nujol mull, cm−1): 3046 (ArH), 1839
ACKNOWLEDGMENTS
We gratefully acknowledge the support by NSF China
No. 21572119 and 21372143.
1
(Fe-H), 1508 (ArC=C), 943 (PMe3). H NMR (300 MHz,
C6D6, 300 K, δ/ppm): −14.86 (td, J = 18.0 Hz,
J = 72.0 Hz, 1H, Fe-H), 0.29 (s, SiCH3, 3H), 0.83 (q,
J = 3.0 Hz, PCHCH3, 6H), 0.98 (q, J = 3.0 Hz, PCHCH3,
12H), 1.08 (q, J = 3.0 Hz, PCHCH3, 6H), 1.12 (d,
J = 9.0 Hz, PCH3, 9H), 1.25 (d, J = 3.0 Hz, PCH3, 9H),
1.90–1.96 (m, PCHCH3, 2H), 2.47–2.49 (m, PCHCH3,
2H), 7.08 (d, J = 6.0 Hz, 2H, Ar-H), 7.19 (q, J = 9.0 Hz,
2H, Ar-H), 7.25 (d, J = 6.0 Hz, 2H, Ar-H), 7.94 (d,
J = 6.0 Hz, 2H, Ar-H). 31P NMR (121 MHz, C6D6, 300 K,
δ/ppm): 1.7 (dt, J = 46.3, 16.4 Hz, 1P, PMe3), 6.3 (m, 1P,
PMe3), 88.7 (d, J = 12.1 Hz, 2P, PiPr). 13C NMR (75 MHz,
CONFLICT OF INTEREST
There are no conflicts to declare.
FUNDING INFORMATION
National Natural Science Foundation of China,
Grant/Award Number: NSF China No. 21572119 and
21372143.
ORCID
Xiaoyan Li https://orcid.org/0000-0003-0997-0380
Hongjian Sun https://orcid.org/0000-0003-1237-3771

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How to cite this article: Chang G, Li X, Zhang P,
et al. Lewis acid promoted dehydration of amides
to nitriles catalyzed by [PSiP]-pincer iron hydrides.
Appl Organometal Chem. 2020;e5466. https://doi.
org/10.1002/aoc.5466