Iminophosphanes: Synthesis, Rhodium Complexes, and Ruthenium(II)-Catalyzed Hydration of Nitriles

Article abstract of DOI:10.1021/acs.organomet.7b00057

Highly stable iminophosphanes, obtained from alkylating nitriles and reaction of the resulting nitrilium ions with secondary phosphanes, were explored as tunable P-monodentate and 1,3-P,N bidentate ligands in rhodium complexes. X-ray crystal structures ar

Full text of DOI:10.1021/acs.organomet.7b00057

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pubs.acs.org/Organometallics
Iminophosphanes: Synthesis, Rhodium Complexes, and
Ruthenium(II)-Catalyzed Hydration of Nitriles
Mark K. Rong,† Koen van Duin,† Tom van Dijk,† Jeroen J. M. de Pater,‡ Berth-Jan Deelman,‡
Martin Nieger,§ A. W. Ehlers,†,∥,⊥ J. Chris Slootweg,*,†,⊥ and Koop Lammertsma*,†,∥
†Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam,
The Netherlands
‡Arkema B.V., location Vlissingen, P.O. Box 70, 4380 AB Vlissingen, The Netherlands
§Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, A. I. Virtasen aukio 1, P. O. Box 55, Helsinki,
Finland
∥Department of Chemistry, University of Johannesburg, Oakland Park 2006, South Africa
S
* Supporting Information
ABSTRACT: Highly stable iminophosphanes, obtained from
alkylating nitriles and reaction of the resulting nitrilium ions with
secondary phosphanes, were explored as tunable P-monodentate
and 1,3-P,N bidentate ligands in rhodium complexes. X-ray
crystal structures are reported for both κ1 and κ2 complexes with
the counterion in one of them being an unusual anionic
coordination polymer of silver triflate. The iminophosphane-
based ruthenium(II)-catalyzed hydration of benzonitrile in 1,2-
dimethoxyethane (180 °C, 3 h) and water (100 °C, 24 h) and
under solvent free conditions (180 °C, 3 h) results in all cases in
the selective formation of benzamide with yields of up to 96%,
thereby outperforming by far the reactions in which the common 2-pyridyldiphenylphosphane is used as the 1,3-P,N ligand.
carbonylation of alkynes,10c,11d,e Pd-catalyzed Buchwald−
INTRODUCTION
Hybrid ligands are important in catalysis, as they enable ligand-
■
Hartwig and Suzuki−Miyaura cross-coupling reactions,15
and metal-based reactivity in bifunctional systems.1,2 In
dinuclear Pd- and [Fe-Rh]-catalyzed carbonylation of alcohol-
s,12d,e,13c the Ru- and Au-catalyzed hydration of alkynes,10d,e the
particular, P,N ligands are of interest because of the presence
of both soft phosphorus and hard nitrogen donor sites.3 Of the
Ru-catalyzed transfer hydrogenation of ketones and aldehy-
des,11b,g the Ru-catalyzed isomerization of alkenes,10b the Ru-
catalyzed and dinuclear Rh-catalyzed hydrogenation of
alkenes,11f,12b the Rh-, Ir-, and [Ru−Rh]-catalyzed hydro-
formylation of alkenes,11c,13a,d and the Cr-catalyzed tri- and
tetramerization of ethylene,11i whereas CuI2 and [AuI3-AgI]
various topologies,4−7 1,3-P,N ligands have shown ample
applicability in transition-metal-based catalysis (Figure 1).
complexes have been used in photoluminescence.12a,c,13b
A
popular ligand in the complexes used for these reactions is 2-
pyridyldiphenylphosphane (PyPPh2),3,16 even though it has
limited flexibility for steric and electronic tuning of particularly
the N-donor site. Replacement of the pyridine group by an
imine or amine functionality provides 1,3-P,N ligands with
more opportunities to tune the properties of their derived
catalysts.
Recently, we reported a simple methodology, based on
nitrilium ions, to synthesize iminophosphanes (IUPAC: c-
phosphanylimines) and anionic phosphaamidinates that carry
different substituents at all three C, N, and P sites (Scheme
1).17 Shortly thereafter Hanton, Dyer, and co-workers reported
Figure 1. 1,3-P,N ligand systems.
The C1 spacer provides optimal separation8 for metal
coordination at nitrogen,9 phosphorus,10,11 or both atoms,11
as well as enabling the formation of homo-12 and hetero-
bimetallic13 complexes for metal activation, photoluminescence,
and cooperative metal−metal systems (Figure 2).13a,14
Exemplary reactions that make use of 1,3-P,N ligands are the
Ru-catalyzed hydration of nitriles,10a,11a,h the Pd-catalyzed
Received: January 25, 2017
Figure 2. 1,3-P,N coordination modes.
© XXXX American Chemical Society
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1 with MeOTf gave the corresponding N-methyl nitrilium
triflates 2 (R = Ph (a), 4-CH3-C6H4 (b), 4-CF3-C6H4 (c)). The
reaction with 1b was carried out in toluene at ambient
temperature to provide after 5 days white crystalline 2b (62%).
Methylations of the less nucleophilic 1a,c were performed
without solvent over an 18 h period; in the case of 1c a slightly
elevated reaction temperature of 45 °C was used to melt the
nitrile. Crystallization of the crude products provided nitrilium
salts 2a (DCM/Et2O) and 2c (DCM/pentane) as white solids
in 86% and 69% yields, respectively.
Scheme 1. Synthesis of Iminophosphanes and
Phosphaamidinates from Nitrilium Ions
Dropwise addition of diphenylphosphane and its 3-methyl, 3-
CF3, and 4-methyl derivatives to a DCM solution of nitrilium
triflates 2a−c at −78 °C, followed by deprotonation with
triethylamine at room temperature, resulted in the quantitative
formation of iminophosphanes 3a−f (Scheme 2). Et2O
extraction, filtration over alumina, and crystallization provided
the products in 46−91% as E/Z mixtures, as determined by
their 31P NMR chemical shifts (i.e., 3a 7.8 (E), −7.6 (Z); 3b 7.6
(E), −8.0 (Z); 3c 8.2 (E), −7.7 (Z); 3d 5.9 (E), −8.5 (Z); 3e
8.3 (E), −7.5 (Z); 3f 6.3 (E), −8.8 (Z)) with assignments
based on related ones reported earlier.17b The E/Z ratios were
found to be sensitive to the experimental setup (e.g.,
concentration), which is in agreement with the calculated
neutral ligands by condensing silylated phosphanes and imidoyl
chlorides, but this method is intrinsically more limited.11i These
1,3-P,N ligands coordinate to Au,17 Rh,17 Ir,17b and Cr11i
complexes. The iminophosphanes display dynamic κ1 and κ2
coordination behavior in the case of Rh(III), while 2-
pyridylphosphanes generally give exclusively κ1 Rh complex-
es.18a−c
In the present study we expand on the synthesis of
iminophosphanes to display the diversity of the nitrilium ion
methodology, report on the chelation to Rh(III) to further
exploit the intricacies of κ1 versus κ2 coordination, and examine
the performance of the iminophosphane versus the PyPPh2
ligand for the Ru(II)-catalyzed hydration of nitriles. The last
process, first reported in 198619 and used for the production of
polyacrylates and pharmaceuticals,19−21 was chosen because of
the role of the N-donor site in activating water in the catalytic
cycle.
very small energy differences (ωB97X-D/6-31+G(d,p); |ΔEE‑Z
|
= 0.19−0.78 kcal mol−1)23 as well as similar behavior reported
for related systems;17 3g was included for its different N
substituent (i-Pr versus Me).17b
Ligand Stability. Exploring the applicability of iminophos-
phanes in transition-metal-catalyzed reactions, such as the
hydration of nitriles (vide infra), requires these P,N ligands to
be stable toward water, whereas it is quite conceivable that they
are prone to hydrolysis to the corresponding diarylphosphanes
and amides. It is then comforting to see, using 31P NMR
monitoring, that the stability of E-/Z-3a in acetone toward
hydrolysis by degassed water over a period of 211 h showed
only slight degradation, which was attributed to oxidation to
[3a(O)] by air rather than hydrolysis (Figure 3). The oxidation
RESULTS AND DISCUSSION
■
The synthesis and stability of new iminophosphanes with
relatively small substituents is presented first. Next, the
coordination to Rh(III) is examined. This is followed by an
assessment of the performance of the ligands in the Ru(II)-
catalyzed hydration of nitriles.
Ligands. A set of iminophosphanes (3a−f) with different
electronic properties but similar steric features was prepared
from nitrilium triflates 2 (Scheme 2). The procedure is
Scheme 2. Synthesis of Iminophosphanes 3
Figure 3. Sensitivity of 3a (%) toward hydrolysis (reagent H2O
(degassed)) and oxidation (reagent O2 (in air)).
sensitivity of 3a was confirmed in a separate assessment (see
Supporting Information). Similar results were obtained for 3b,c
(see Supporting Information). The presence of 0.10 equiv of
triflic acid did not catalyze the hydrolysis of 3a. Exposure of 3a
to triflic acid at room temperature gave only N-protonated
iminophosphane without any degradation over a 46 h period.
This indicates that iminophosphanes are reasonably rugged
ligands.
analogous to the protocol we reported recently, the difference
being that here nitriles 1 are directly alkylated to provide the
ion, whereas previously we obtained the ions from imidoyl
chlorides.17 The choice of synthetic approach depends on the
N substituent: with i-Pr or larger alkyl groups, imidoyl chlorides
are the starting point, sometimes necessitating stabilization of
the resulting nitrilium ions with pyridine bases,17c but smaller
groups are only accessible by nitrile alkylation.22 Thus, treating
Rhodium Coordination. The chelation of the iminophos-
phanes toward rhodium was explored next. Recently, we found
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that ligands bulkier than 3a−f give P-monodentate complexes
with Au(I), bidentate complexes with Ir(III), and both κ1 and
κ2 complexes with Rh(III), of which only bidentate complexes
were isolable as the major products.17b We wondered whether
we could make monodentate Rh complexes the prevalent
product, which is of interest for cooperative Rh(III)
catalysis,10,11,13d,24 without relying on steric effects.25 We also
wondered how silver triflate, commonly added in excess in
Rh(III) catalysis,24b,c plays a role beyond the formation of
bidentate complexes by single Cl abstraction. To address these
issues, we focus on the chelation of 3a,c,e.
H-bonding interactions between Cp*−CH3 groups and the N
lone pair. The 2.3222(4) Å Rh1−P1 bond length of 4a is
similar to that of the 2-pyridylphosphanyl Rh(III) κ1 complex-
es.18a−c
1
P-monodentate complexes 4c (δ(31P) 35.4 ppm, JP,Rh
=
147.4 Hz) and 4e (δ(31P) 34.7 ppm, JP,Rh = 145.8 Hz) were
prepared likewise from 3c,e and isolated in 69% and 92% yields,
respectively (Scheme 3). The molecular structure of 4e,
obtained by a single-crystal X-ray structure determination,
reveals structural parameters with bond lengths Rh1−P1 =
2.3196(6) Å, N1−C1 = 1.269(3) Å, and P1−C1 = 1.870(2) Å
and a −53.92(19)° Rh1−P1−C1−N1 torsion angle that are
comparable to those of 4a (Figure 4). 31P NMR analysis of the
two reactions showed only in the case of 3e formation of a
byproduct (6%) that is assigned to P,N bidentate complex 5e
1
Treating E-/Z-3a in DCM with 1/2 equiv of [RhCp*Cl2]2 at
room temperature yielded two products in a 96:4 ratio
1
(Scheme 3). The major product (δ(31P) 34.5 ppm; JP,Rh
=
1
(δ(31P) −12.1 ppm, JP,Rh = 114.7 Hz).
Scheme 3. Synthesis of Mono- and Bidentate Rh(III)
Complexes 4 and 5
The reproducible 4:5 ratios indicate that the small extent or
absence of observed bidentate complexes depends to a degree
on the aromatic substituent. In comparison to the C- and P-
phenyl groups, the m-tolyl substituent at carbon (e) enhances
bidentate formation slightly (from 4 to 6%), while the p-CF3-
phenyl group at phosphorus (c) blocks it (Scheme 3). This
trend concurs with the N-donor strength calculated at ωB97X-
D/6-31+G(d,p) (Def2-TZVP for Rh) from the energy required
to transform cationic complex 5 from a κ1 to a κ2 arrangement
(Scheme 4);17b,23 a comparison between neutral 4 and ionic 5+
Scheme 4. DFT Analysis of the N-Donor Capacity of 3a,c,e
145.7 Hz), isolated as an orange solid (89%), is assigned to the
E isomer of monodentate Rh complex 4a, in analogy to
reported in situ Rh complexes.17c The minor product (δ(31P)
1
−5.1 ppm; JP,Rh = 113.4 Hz) is likely bidentate complex 5a
because of its similarity in 31P NMR data to related, bulkier Rh
complexes.17c Crystallization of 4a by slow diffusion of pentane
into a DCM/Et2O solution provided crystals suitable for an X-
ray structure determination. The molecular structure confirms
P-monodentate coordination and the E conformation for the
imine group (Figure 4), thereby illustrating the ease of Z to E
isomerization of the ligand.17c The N1−C1 bond length of
1.2738(17) Å is typical for a CN bond and the 1.8659(13) Å
long P1−C1 bond is normal for a P−alkyl single bond; the
Rh1−P1−C1−N1 torsion angle amounts to −56.15(11)°, with
is not feasible. The Rh−N bond strengths of 5a,c,e amount to
−14.7, −13.4, and −15.2 kcal mol−1, respectively, with
corresponding N lone pair orbital energies of −11.2, −11.4,
and −11.0 eV. These data support the notion that the selective
formation of only P-chelated complexes of 1,3-P,N ligands can
be controlled by changing the N-donor strength.
Of course, the 1,3-P,N ligands can also undergo clean
chelation with rhodium as shown before, but under more
forcing conditions. For example, treating 4 with 1 equiv of silver
triflate yielded bidentate complex 6 quantitatively (Scheme 5).
These ionic complexes, containing a triflate counteranion
instead of a chloride anion as in 5, were isolated as bright
orange solids and identified by their 31P NMR characteristics
1
1
Figure 4. Displacement ellipsoid plots of rhodium complexes 4a (left)
and 4e (right) at the 50% probability level. Hydrogen atoms and DCM
are omitted for clarity. Selected bond lengths (Å) and angles (deg): 4a,
Rh1−P1 = 2.3222(4), Rh1−Cl1 = 2.4056(3), Rh1−Cl2 = 2.4008(4),
P1−C1 = 1.8659(13), N1−C1= 1.2738(17), N1−C2 = 1.4634(17),
C1−C3 = 1.4946(17), N1−C1−P1 = 112.72(9), Rh1−P1−C1−N1 =
−56.15(11); 4e, Rh1−P1 = 2.3196(6), Rh1−Cl1 = 2.4013(6), Rh1−
Cl2 = 2.4011(6), P1−C1 = 1.870(2), N1−C1= 1.269(3), N1−C2 =
1.469(3), C1−C3 = 1.493(3), N1−C1−P1 = 113.62(18), Rh1−P1−
C1−N1 = −53.92(19).
(6a, −9.1 ppm, JP,Rh = 113.4 Hz; 6c, −5.0 ppm, JP,Rh = 115.0
1
Hz; 6e, −8.6 ppm, JP,Rh = 113.4 Hz). When 4a was treated
with an excess of 4 equiv of AgOTf,24b,c a yellow solid resulted
(7a, 80%) having a 31P NMR chemical shift (−9.9 ppm; 1JP,Rh
=
111.8 Hz) which differs from that of 6a (Scheme 5). Single-
crystal X-ray structure determinations confirm the bidentate
nature of both complexes (Figure 5) and reveal that the excess
of AgOTf caused the exchange of rhodium’s coordinated
chloride for an OTf group, without affecting the P,N ligand.
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Scheme 5. Bidentate Coordination of 3 to Rh(III)
Figure 6. Displacement ellipsoid plot of a dimeric unit of the
[Ag2OTf3(DCM)]n counterion of 7a at the 20% probability level (left)
and its simplified numbering scheme (right). Hydrogen atoms and
minor disordered part of the solvent DCM are omitted for clarity.
Selected bond lengths (Å) and angles (deg): Ag1−Ag2 = 3.0410(3),
Ag1- - -Ag2b = 4.0607(3), Ag1- - -Ag2a = 5.9371(3), Ag1−O =
2.345(2)-2.394(2); Ag2−O = 2.321(2)-2.509(2), Ag1- - -O33 =
2.621(2), Ag1−Cl1 = 2.9042(9), Ag1−Ag2−Ag1a = 113.71(1),
Ag2−Ag1−Ag2b = 102.17(1), Ag2−Ag1−Ag2b−Ag1b = 6.86(2).
PyPPh2 ligand for the role of the hard nitrogen donor site to
activate water, as is illustrated in Figure 7.10a,11a,h We opted for
Figure 5. Displacement ellipsoid plots of cationic rhodium complexes
6a (left) at the 30% probability level and 7a (right) at the 50%
probability level. Hydrogen atoms and counterions (triflate and
−
[Ag2OTf3(DCM)]n , respectively) are omitted for clarity. Selected
bond lengths (Å) and angles (deg): for 6a, Rh1−P1 = 2.3123(14),
Rh1−N1 = 2.106(4), Rh1−Cl1 = 2.3728(13), P1−C1 = 1.842(5),
N1−C1 = 1.274(7), N1−C2 = 1.466(7), C1−C3 = 1.461(7), N1−
Rh1−P1 = 66.27(12), N1−C1−P1 = 100.4(4); 7a, Rh1−P1 =
2.3328(7), Rh1−N1 = 2.126(2), Rh1−O11 = 2.1957(18), P1−C1 =
1.844(3), N1−C1 = 1.294(3), N1−C2 = 1.466(3), C1−C3 =
1.471(4), S1−O11 = 1.4711(19), S1−O12 = 1.433(2), S1−O13 =
1.429(2), N1−Rh1−P1 = 67.02(6), N1−C1−P1 = 102.29(18).
Figure 7. Ru-catalyzed, P,N-assisted hydration of benzonitrile.
ruthenium catalysts,29 which are extensively used in homoge-
neous catalysis30 and are more robust than those based on
rhodium (for comparison and completeness also included in
our tests), while their chemistry is comparable. This choice is
corroborated by the elevated temperatures needed.
The molecular structure of 6a shows Rh1−P1, Rh1−N1, and
Rh1−Cl1 bond lengths of respectively 2.3123(14), 2.106(4),
and 2.3728(13) Å and an acute N1−C1−P1 bond angle of
100.4(4)°. The structural features of 7a resemble those of 6a
and other bidentate 1,3-P,N Rh(III) complexes,17,18a,b,d except
for its triflate group with an Rh1−O11 bond length of
2.1957(18) Å that is similar to those reported for monodentate
Rh(III)−triflate bonds.26 Expectedly, the S1−O11 bond is
elongated with respect to the S1−O12 and S1−O13 bonds: i.e.,
1.4711(19), 1.433(2), and 1.429(2) Å, respectively.
The counterion of 7a is a coordination polymer of silver
triflate (Figure 6). Whereas aggregates of Ag(I) sulfonates are
known,27 the present structure is, to the best of our knowledge,
the first of its kind in an organometallic complex. The
molecular structure shows a linear chain with alternating Cs-
symmetric dinuclear Ag(I) units (Ag1−Ag2 = 3.0410(3) Å)
that are bridged by triflate anions. Each Ag atom has a
distorted-octahedral geometry with bi-, tri-, and tetradentate
coordinating triflate groups labeled as 2, 3, and 4 in Figure 6
(right); the Ag−O bond distances range from 2.321(2) to
2.509(2) Å.27 The weak coordination of DCM (Ag1−Cl1 =
2.9042(9) Å) completes the octahedral coordination sphere of
Ag1.28
To identify a suitable Ru source for benchmarking
iminophosphane 3a against PyPPh2 in the hydration of
benzonitrile, we conducted the catalytic reactions in 1,2-
dimethoxyethane, in water, and in the absence of a solvent.
Table 1 gives the precatalyst, ligand, solvent, and the yield of
benzamide. For the reactions in DME, the procedure of Takai,
Oshiki, and co-workers11h was followed by premixing 5 mol %
of the Ru precursor complex and 3a for 30 min, upon which the
catalyzed hydration of benzonitrile was executed in a closed
vessel at 180 °C for 3 h; 2 equiv of water was used to remain
consistent with the reported protocol. The results show that
precatalyst [Ru(p-cymene)Cl2]2 (entries 1 and 2) gives better
results than [Ru(C6Me6)Cl2]2 (entry 5) and [Ru(C6H5Me)-
Cl2]2 (entry 6), but even these give reasonable conversions.
The presence of 1 equiv of AgOTf hindered the reaction
(Table 1, entry 3), presumably through the formation of
inactive bidentate species. Remarkable is the observation that
the catalytic hydration using 3a gave an excellent yield of 87%
(entry 1), while the same process with the PyPPh2 ligand
performed very poorly with a product yield of a mere 3%11h
(entry 4). Using 2 equiv of 3a further enhanced the yield to
96% (entry 2). In addition, rhodium precatalyst [RhCp*Cl2]2
was examined under the same conditions. Even this in situ
generated catalyst, presumably 4a, yields benzamide, albeit in
only in 22% yield (entry 7), which is a remarkable observation,
Application in Catalytic Nitrile Hydration. Having
established simple synthetic protocols for highly stable
iminophosphanes and having demonstrated their ability to
function as P monodentate and P,N bidentate ligands, we set
out to explore their potential as hydration catalysts for nitriles.
This reaction was chosen to compare iminophosphanes to the
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Table 1. Ru(II)-Catalyzed Hydration of Benzonitrile
a
entry
precatalyst (M)
[Ru(p-cym)Cl2]2
ligand (L)
solvent
T (°C)
t (h)
yield (%)
b
1
3a
DME
DME
DME
DME
DME
DME
DME
H2O
180
180
180
180
180
180
180
100
100
180
180
180
3
3
87
96
b
c
2
[Ru(p-cym)Cl2]2
[Ru(p-cym)(Cl) (OTf)]2
[Ru(p-cym)Cl2]2
[Ru(C6Me6)Cl2]2
[Ru(C6H5Me)Cl2]2
[RhCp*Cl2]2
[Ru(p-cym)Cl2]2
[Ru(p-cym)Cl2]2
[Ru(p-cym)Cl2]2
[Ru(p-cym)Cl2]2
3a
b
d
d
3
3a
3
3
b
4
Ph2PPy
3a
3
311h
55
b
5
3
b
6
3a
3
84
b
7
3a
3
22
e
8
3a
24
24
3
94
e
9
Ph2PPy
3a
H2O
5711a
78
f
10
none
none
none
f
11
Ph2PPy
none
3
6
f
12
[Ru(p-cym)Cl2]2
3
6
a
b
c
d
Determined by GC. Conditions: Ph−CN (1 mmol), H2O (2 mmol), [M]L (5 mol %); DME (0.5 mL). 2 equiv. Prepared in situ from [Ru(p-
e
f
cym)Cl2]2 and AgOTf. Conditions: Ph−CN (1 mmol), [M]L (5 mol %); H2O (3.0 mL). Conditions: Ph−CN (3.6 mmol), H2O (7.2 mmol),
[M]L (1.4 mol %).
as no Rh(III) catalyst has so far been reported to hydrate
nitriles.
entry 1). Changing the N substituent from Me to the bulkier i-
Pr group (3g) decreased the yield by only 3% (entry 5). A
similar marginal effect (−2%) was observed on introducing a 4-
CF3 substituent on the C-phenyl group (3c, entry 2). Slightly
larger effects were found on introducing 3-CH3 and 3-CF3
substituents on the P-phenyl groups, causing modest changes in
yield of +4% (entry 3) and −8% (entry 4), respectively. These
may possibly be attributed to a difference in electron-donating
properties, which affect ruthenium’s Lewis acidity via the Ru−P
bond.14d All of this leads to the observation that the
iminophosphanes 3 are all effective ligands enabling the
solvent-free Ru(II)-catalyzed hydration of benzonitrile and
that these 1,3-P,N ligands can be modified at the P, C, and N
centers to effect the hydration to different degrees.
Next, we explored the protocol of Cadierno et al. by heating
benzonitrile and 5 mol % of precatalyst [Ru(p-cym)Cl2]2 and
the 1,3-P,N ligand in boiling water for 24 h using a closed
vessel.11a,31 Also in this case an outstanding yield of 94% was
obtained for the catalytic reaction with 3a (Table 1, entry 8),
which is far better than the 57% that resulted with the PyPPh2
ligand (entry 9).11a This performance is in line with that with
DME as solvent (entries 1 and 4) by also showing that the
catalytic reaction with ligand 3a outperforms that with Ph2PPy.
Finally, we compared the influence of these ligands in the
solvent-free hydration of benzonitrile by heating 1.4 mol % of
the catalyst in a 1:2 molar mixture of benzonitrile and water at
180 °C for 3 h in a closed vessel. Again, the reaction of [Ru(p-
cym)Cl2]2 and 3a (78%, entry 10) gave a far better
performance than that with the Ph2PPy ligand (6%, entry
11), which, in fact, seems to have no effect, as 6% was also
obtained when no P,N ligand was present (entry 12). It appears
that all three Ru-catalyzed approaches for the hydration of
benzonitrile underscore the potential of iminophosphanes as
ligands. The observed differences in the activity of 3a and
PyPPh2 were attributed to their difference in N-donor
strength.10a
CONCLUSION
■
This study shows iminophosphanes to be readily synthesized by
simple alkylation of nitriles and reaction of the resulting
nitrilium ions with a secondary phosphane. They are very stable
in water but do show some sensitivity to oxidation in air. The
1,3-P,N ligands are tunable by substitution at their P, C, and N
centers. Their coordination behavior was explored for
rhodium(III) complexes, using [RhCp*Cl2]2 as precursor.
Both P monodentate and 1,3-P,N bidentate ligands can be
obtained in high yield. Silver triflate is needed to enforce the
formation of the κ2 chelates, and when an excess is used, also
the second chloride is exchanged. Several X-ray crystal
structures of rhodium complexes are reported, including one
with a polymeric aggregate of Ag(I) sulfonate with embedded
DCM solvent molecules. The ligands were found to be effective
in the Ru(II)-catalyzed hydration of benzonitrile, be it in an
organic solvent, in water, or under solvent-free conditions. Its
performance appears to be better than that of 2-pyridyldiphe-
nylphosphane, with yields of up to 96% on using the
commercial [Ru(p-cym)Cl2]2 as precatalyst. Modifying the
substitution pattern of the iminophosphanes affects the yield of
the ruthenium-catalyzed hydration of benzonitrile as well as the
coordination to the rhodium complex. Clearly, more extensive
studies have to be performed for more catalytic processes, but
the easily synthesized iminophosphanes seem to have great
prospects as new 1,3-P,N ligands.
Finally, we address briefly the influence of the P,C,N
substituents of 3 on the yield of the Ru(II)-catalyzed hydration
using solvent-free conditions. The results are given in Table 2.
Whereas the iminophosphanes are only modestly different
from each other, some distinctly affected the benzamide yield.
As a reference we used 3a, which has Ph substituents on the P
and C centers and a Me group on the N atom. The catalyzed
hydration yield of benzonitrile amounted to 78% (Table 2,
Table 2. Solvent-Free [(3)Ru(p-cym)Cl2]-Catalyzed
a
Hydration of Benzonitrile
b
entry
ligand (L)
solvent
T (°C)
t (h)
yield (%)
1
2
3
4
5
3a
3c
3d
3e
3g
none
none
none
none
none
180
180
180
180
180
3
3
3
3
3
78
76
82
70
75
a
Conditions: Ph−CN (3.6 mmol), H2O (7.2 mmol), [Ru(p-
b
cym)Cl2]L (1.4 mol %). Determined by GC.
E
DOI: 10.1021/acs.organomet.7b00057
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
7.45 (d, 3JH,H = 8.0 Hz, 2H; m-ArH), 4.18 (s, 3H; NCH3), 2.51 (s, 3H;
C6H4CH3). 13C{1H} NMR (125.78 MHz, CDCl3): δ 151.3 (s; p-ArC),
EXPERIMENTAL SECTION
■
Preparation of Compounds. All experiments were performed
under an atmosphere of dry nitrogen using standard Schlenk-line and
glovebox techniques, unless stated otherwise. Solvents were distilled
under nitrogen over the appropriate drying agent; CaCl2 (DCM),
benzophenone/NaK (Et2O, THF, triethylamine), Na (toluene),
LiAlH4 (pentane), P2O5 (CD2Cl2, CDCl3). C6D6 was dried over Na
at room temperature. H2O was degassed ultrasonically in vacuo. Silver
salts were handled with minimum light exposure. Diphenylphosphane
was purchased from Sigma-Aldrich, and tris(3-methylphenyl)-
phosphane and bis(4-methylphenyl)chlorophosphane were obtained
from STREM Chemicals Inc. Bis(3-trifluoromethylphenyl)-
chlorophosphane was provided by Arkema B.V. The known
compounds 2a,22b bis(3-trifluoromethylphenyl)phosphane, bis(3-
methylphenyl)phosphane, and bis(4-methylphenyl)phosphane are
reported here, since their syntheses were revised and/or new analytical
data were obtained. All phosphanes and chlorophosphanes were
distilled under reduced pressure before use. Solids were predried in
vacuo for at least 30 min. All other reagents were used as received.
NMR spectra were recorded on a Bruker Avance 250 (1H, 250.13
MHz; 19F, 235.36 MHz; 31P, 101.25 MHz; room temperature), a
Bruker Avance 400 (1H, 400.13 MHz; 13C{1H}, 100.61 MHz; 31P,
161.98 MHz; room temperature) ,or a Bruker Avance 500 instrument
(1H, 500.23 MHz; 13C{1H}, 125.78 MHz; room temperature). 1H
spectra and 13C{1H} spectra were internally referenced to residual
solvent resonances (CDCl3, δ(1H) 7.26, δ(13C{1H}) 77.16; CD2Cl2,
δ(1H) 5.32, δ(13C{1H}) 53.84; C6D6, δ(1H) 7.16, δ(13C{1H}) 128.06),
and 31P spectra were referenced externally to H3PO4. Melting points
1
136.1 (s; o-ArC), 131.1 (s; m-ArC), 120.9 (q, JC,F = 319.5 Hz;
1
O3SCF3), 107.7 (tm, JC,14N = 50.9 Hz; CN), 99.4 (s; ipso-ArC), 32.5
(s; NCH3), 22.9 (s; C6H4CH3). 19F NMR (235.36 MHz, CDCl3): δ
−78.4 (s, O3SCF3). FT-IR (cm−1): ν 3051 (w), 2959 (w), 2473 (w),
2424 (w), 2368 (s), 2328 (w), 1670 (w), 1605 (s), 1506 (w), 1418
(m), 1389 (m), 1258 (s), 1225 (s), 1192 (s), 1148 (s), 1128 (s), 1028
(s), 974 (w), 943 (s), 824 (s), 791 (m), 756 (s), 739 (m), 702 (w),
635 (s), 573 (s), 540 (s), 517 (s), 488 (w), 447 (m), 438 (m), 409
(w). MS (ESI-Q-TOF): calcd for C9H10N 132.0808; found 132.0811.
1
Data for 2c are as follows. Mp: 106.9−108.0 °C. H NMR (500.23
MHz, CDCl3): δ 8.50 (d, 3JH,H = 8.3 Hz, 2H; o-ArH), 7.90 (d, 3JH,H
=
8.3 Hz, 2H; m-ArH), 4.26 (s, 3H; NCH3). 13C{1H} NMR (125.78
2
1
MHz, CDCl3): δ 162.5 (d, JC,F = 13.8 Hz; p-ArC), 139.4 (q, JC,F
=
34.0 Hz; C6H4CF3), 137.1 (s; o-ArC), 127.0 (s; m-ArC), 122.4 (q, 1JC,F
1
= 274.2 Hz; O3SCF3), 107.4 (s; ipso-ArC), 105.2 (tm, JC,14N = 50.0
Hz; CN), 32.9 (s; NCH3). 19F NMR (235.36 MHz, CDCl3): δ −64.5
(s; C6H4CF3), −78.7 (s; O3SCF3). FT-IR (cm−1): ν 3117 (w), 3067
(w), 3036 (w), 2957 (w), 2366 (s), 1688 (w), 1508 (w), 1412 (m),
1389 (w), 1319 (s), 1252 (s), 1225 (s), 1165 (s), 1130 (s), 1113 (s),
1067 (s), 1030 (s), 1018 (s), 928 (w), 847 (s), 756 (s), 733 (w), 706
(s), 683 (w), 636 (s), 596 (s), 573 (s), 536 (s), 517 (s), 469 (m), 449
(m), 432 (m). MS (ESI-Q-TOF): calcd for C9F3H7N 186.0525; found
186.0533.
Bis(3-trifluoromethylphenyl)phosphane.35 A solution of
freshly distilled bis(3-trifluoromethylphenyl)chlorophosphane (5.88
g, 16.50 mmol, 1.00 equiv) in 30 mL of Et2O was added dropwise at
−78 °C to a suspension of LiAlH4 (0.25 g, 6.59 mmol, 0.40 equiv) in
50 mL of Et2O, during which gas evolved from the mixture. After
addition, the gray suspension was warmed to room temperature. After
it was stirred for 1.5 h, the mixture was cooled to 0 °C and H2O (0.95
mL, 52.63 mmol, 3.19 equiv) was added dropwise. After the mixture
was stirred for 0.5 h at room temperature, volatiles were removed in
vacuo and the resulting gray-white suspension was extracted into 3 ×
10 mL of pentane. The combined extracts were evaporated to provide
bis(3-trifluoromethylphenyl)phosphane as a colorless liquid (4.94 g,
were measured using a Buchi M-565 melting point apparatus (sealed
̈
capillaries) and are uncorrected. High-resolution electrospray ioniza-
tion (ESI) mass spectrometry was carried out with a Bruker
micrOTOF-Q instrument in positive ion mode (capillary potential
of 4500 V). Infrared spectra were recorded on a Shimadzu FT-IR
8400S spectrophotometer.
Computational Procedure. Density functional calculations were
performed at the ωB97X-D32 level of theory using Gaussian09,
revision A.02.23 Geometry optimizations were performed using the 6-
31+G(d,p)33 basis set (Def2-TZVP for Rh),34 and the nature of each
stationary point was confirmed by frequency calculations.
(N-Methyl)(aryl)carbonitrilium Trifluoromethyl Sulfonates
2a−c.22b Protocol 1. MeOTf (1.0 equiv) was added dropwise to a
solution of arylnitrile (1.0 equiv) in toluene (0.27 mL/mmol of
arylnitrile). After the mixture was stirred for 18 h at room temperature,
a microcrystalline solid precipitated. Volatiles were removed in vacuo,
and after washing with pentane (2 × 0.4 mL/mmol), 2 was obtained as
an off-white solid (2a, 62%; 2b, 62%; 2c: 14%).
Protocol 2. MeOTf (1.0 equiv) was added dropwise to the
arylnitrile (1.2 equiv). The colorless solution was stirred for 18 h (2a,
room temperature; 2c, 45 °C). The resulting white-yellow crystalline
solid was washed with pentane (3 × 0.2 mL/mmol) and dried in vacuo
to provide 2 as a white solid (2a, 86%; 2c, 69%).
Crystallization was carried out by slow 1:1 diffusion of ether
(alternatively pentane) into a saturated DCM solution at 5 °C to
provide 2 as white crystals.
1
3
15.33 mmol, 93%). H NMR (500.23 MHz, C6D6): δ 7.61 (d, JH,P
=
6.9 Hz, 2H; PC−CH-CCF3), 7.17 (d, 3JH,H = 6.3 Hz, 2H; p-ArH), 7.05
3
3
(t, JH,H = 6.9 Hz, 2H; PC−CH-CH), 6.71 (t, JH,H = 7.7 Hz, 2H; m-
ArH), 4.81 (d, JH,P = 219.7 Hz, 1H; PH). 13C{1H} NMR (125.78
1
MHz, C6D6): δ 137.2 (d, 2JC,P = 17.3 Hz; PC−CH-CH), 135.9 (d, 1JC,P
2
3
= 13.6 Hz; ipso-ArC), 131.2 (qd, JC,F = 32.7 Hz, JC,P = 6.4 Hz; PC-
CH-CCF3), 130.5 (dq, 2JC,P = 18.2 Hz, 3JC,F = 4.5 Hz; PC-CH-CCF3),
3
3
129.3 (d, JC,P = 5.5 Hz; m-ArC), 125.7 (q, JC,F = 3.6 Hz; p-ArC),
124.6 (q, JC,F = 272.5 Hz; CF3). 19F NMR (235.36 MHz, C6D6): δ
1
−63.3 (s; C6H4CF3). 31P NMR (161.98 MHz, C6D6): δ −41.1 (dq,
1JP,H = 218.3 Hz, JP,H = 6.7 Hz).
3
Bis(3-methylphenyl)phosphane.36 A colorless solution of
tris(3-methylphenyl)phosphane (4.18 g, 13.73 mmol, 1.00 equiv) in
30 mL of THF was prepared in a separate vessel and added dropwise
at 0 °C to an excess of finely cut Li (0.21 g 30.23 mmol, 2.20 equiv)
suspended in 5 mL of THF. Afterward, the vessel was washed with 2 ×
10 mL of THF, which was also added to the reaction mixture. After
addition, the mixture was warmed to room temperature. After this
mixture was stirred for 26 h at room temperature, a deep red mixture
was obtained, which was decanted to remove excess Li. The resulting
solution was cooled to 0 °C, and H2O (1.0 mL, 55.40 mmol, 4.04
equiv) was added dropwise to give a white-gray mixture. After 1 h of
stirring at room temperature, volatiles were removed in vacuo to
provide a white oil, which was extracted sequentially into 50 mL of
Et2O for 24 h and 40 mL of Et2O for 20 h. The combined extracts
were evaporated to give a light yellow liquid, which was distilled (3.2 ×
10−2 mbar, heated with Bunsen burner) to provide bis(3-
methylphenyl)phosphane (1.71 g, 7.99 mmol, 58%) as a colorless
liquid. 1H NMR (500.23 MHz, C6D6): δ 7.30 (t, 3JH,H = 8.2 Hz, 4H; o-
ArH), 7.00 (t, 3JH,H = 7.4 Hz, 2H; m-ArH), 6.87 (d, 3JH,H = 6.6 Hz, 2H;
1
Data for 2a are as follows. Mp: 78.9−79.9 °C. H NMR (500.23
MHz, CDCl3): δ 8.31 (d, 3JH,H = 8.0 Hz, 2H; o-PhH), 7.92 (t, 3JH,H
=
7.8 Hz, 1H; p-PhH), 7.65 (t, 3JH,H = 8.0 Hz, 2H; m-PhH), 4.20 (s, 3H;
NCH3). 13C{1H} NMR (125.78 MHz, CDCl3): δ 138.6 (s; p-PhC),
1
136.2 (s; m-PhC), 130.1 (s; o-PhC), 120.9 (q, JC,F = 319.5 Hz;
O3SCF3), 106.8 (tm, 1JC,14N = 47.2 Hz; CN), 103.0 (s; ipso-PhC), 32.6
(s; NCH3). 19F{1H} NMR (235.36 MHz, CDCl3): δ −78.3 (s;
O3SCF3). FT-IR (cm−1): ν 3277 (w), 3248 (w), 3186 (w), 3026 (w),
2957 (w), 2457 (w), 2366 (s), 1680 (m), 1583 (m), 1528 (m), 1489
(w), 1448 (m), 1402 (m), 1371 (m), 1261 (s), 1223 (s), 1180 (s),
1148 (s), 1024 (s), 987 (s), 943 (m), 843 (w), 762 (s), 704 (s), 679
(s), 633 (s), 573 (s), 538 (s), 515 (s), 484 (w), 467 (m), 426 (w), 413
(w). MS (ESI-Q-TOF): calcd for C8H8N: 118.0651; found 118.0657.
1
p-ArH), 5.27 (d, JH,P = 215.0 Hz, 1H; PH), 1.99 (s, 6H; CH3).
2
13C{1H} NMR (125.78 MHz, C6D6): δ 138.3 (d, JC,P = 6.4 Hz; m-
1
Data for 2b are as follows. Mp: 117.0 °C dec; 135.1−135.8 °C. H
NMR (500.23 MHz, CDCl3): δ 8.18 (d, JH,H = 8.0 Hz, 2H; o-ArH),
3
2
ArC-CH3), 135.4 (d, 1JC,P = 10.9 Hz; ipso-ArC), 135.0 (d, JC,P = 18.2
F
DOI: 10.1021/acs.organomet.7b00057
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Hz; o-ArC), 131.5 (d, 2JC,P = 16.4 Hz; o-ArC), 129.5 (s; p-ArC), 128.8
609 (s), 573 (s), 548 (m), 507 (s), 474 (s), 449 (s), 426 (s). HR-MS
(ESI-Q-TOF): calcd for C20H19NP 304.1250; found 304.1245.
3
(d, JC,P = 6.4 Hz; m-ArC), 21.2 (s; CH3). 31P NMR (161.98 MHz,
1
3
1
C6D6): δ −40.3 (dq, JP,H = 215.4 Hz, JP,H = 7.9 Hz).
Data for 3b are as follows. Mp: 44.0−46.1 °C. Since not all H and
Bis(4-methylphenyl)phosphane.35 A solution of bis(4-
methylphenyl)chlorophosphane (1.81 mL, 8.01 mmol, 1.00 equiv)
in 15 mL of Et2O was added dropwise to a suspension of LiAlH4
(0.094 g 2.48 mmol, 0.31 equiv) at −78 °C. After addition, the gray
suspension was warmed to room temperature. After it was stirred for
1.5 h at room temperature, the mixture was cooled to 0 °C and H2O
(0.15 mL, 8.31 mmol, 1.04 equiv) was added dropwise. After it was
stirred for 1 h at room temperature, the gray-white suspension was
filtered onto anhydrous Na2SO4 (2.71 g), after which it was filtered
again. Volatiles were removed in vacuo to provide a white suspension,
which was extracted into 20 mL of pentane. After evaporation of the
extract, the obtained white suspension was distilled (2.3 × 10−2 mbar,
100 °C). Bis(4-methylphenyl)phosphane (0.81 g, 3.78 mmol, 47%)
13C NMR resonances of E-3b and Z-3b can be distinguished, one set of
1
signals is reported (integrals normalized separately for each isomer). H
NMR (500.23 MHz, CDCl3): δ 7.46−7.39 (m, 6H; P-ArH (E), P-ArH
(Z)), 7.32−7.23 (m, 14H; P-ArH (E), P-ArH (Z)), 7.02 (d, 3JH,H = 7.9
3
Hz, 2H; C-o-ArH (E)), 6.95 (d, JH,H = 8.2 Hz, 2H; C-o-ArH (Z)),
3
3
6.89 (d, JH,H = 7.9 Hz, 2H; C-m-ArH (E)), 6.84 (d, JH,H = 7.9 Hz,
2H; C-m-ArH (Z)), 3.56 (s, 3H; CN-CH3 (Z), 3.26 (d, 4JH,P = 1.9 Hz,
3H; CN-CH3 (E)), 2.26 (s, 3H; C-Ar-CH3 (E)), 2.20 (s, 3H; C-Ar-
1
CH3 (Z)). 13C{1H} NMR (125.78 MHz, CDCl3): δ 179.1 (d, JC,P
=
8.2 Hz; CN-CH3 (E)), 139.4 (s; C-ipso-ArC (Z)), 138.0 (s; C-ipso-ArC
(E)), 134.8 (d, JC,P = 20.0 Hz; P-ArC (E)), 134.8 (s; P-ipso-ArC (Z)),
134.6 (d, 1JC,P = 10.9 Hz; P-ipso-ArC (E)), 133.9 (d, JC,P = 19.1 Hz; P-
ArC (Z)), 129.0 (s; P-ArC (E)), 129.0 (s; P-ArC (Z)), 128.9 (s; P-
ArC), 128.8 (d, JC,P = 7.3 Hz; P-ArC), 128.3 (d, 4JC,P = 10.3 Hz; C-m-
1
was obtained as a colorless liquid. H NMR (500.23 MHz, C6D6): δ
3
3
4
7.38 (t, JH,H = 7.8 Hz, 4H; o-ArH), 6.89 (d, JH,H = 7.5 Hz, 4H; m-
ArH), 5.28 (d, 1JH,P = 214.1 Hz, 1H; PH), 2.02 (s, 6H; CH3). 13C{1H}
NMR (125.78 MHz, CDCl3): δ 138.4 (s; p-ArC), 134.5 (d, 2JC,P = 17.3
ArC (Z)), 127.8 (s; C-o-ArC (Z)), 127.1 (d, JC,P = 4.1 Hz; C-m-ArC
3
3
(E)), 43.6 (d, JC,P = 36.3 Hz; CN-CH3 (Z)), 43.2 (d, JC,P = 9.1 Hz;
CN-CH3 (E)), 21.4 (s; C-Ar-CH3 (E)), 21.3 (s; C-Ar-CH3 (Z)). 31P
NMR (161.98 MHz, CDCl3): δ 7.6 (s; E isomer, 83%), −8.0 (s; Z
isomer, 17%). FT-IR (cm−1): ν 3072 (m), 3001 (m), 2943 (m), 2907
(m), 2853 (m), 2756 (m), 1601 (s), 1570 (m), 1506 (s), 1481 (s),
1433 (s), 1404 (m), 1391 (s), 1375 (m), 1310 (m), 1261 (m), 1217
(m), 1182 (s), 1157 (m), 1111 (s), 1095 (s), 1065 (s), 1028 (s), 970
(s), 951 (s), 920 (s), 845 (m), 812 (s), 791 (s), 733 (s), 690 (s), 665
(s), 635 (s), 619 (s), 525 (s), 484 (s), 453 (s), 440 (s), 411 (s). HR-
MS (ESI-Q-TOF): calcd for C21H21NP 318.1406; found 318.1404.
2
3
Hz; o-ArC), 132.2 (d, JC,P = 9.1 Hz; ipso-ArC), 129.7 (d, JC,P = 6.4
Hz; m-ArC), 21.1 (s; CH3). 31P NMR (161.98 MHz, C6D6): δ −42.6
1
3
(dq, JP,H = 215.4 Hz, JP,H = 3.2 Hz).
((N-Methyl)arylimidoyl)diarylphosphanes 3a−f. Protocol 3a−
d. Diarylphosphane (1.0 equiv) was added dropwise to a solution of 2a
(1.1 equiv) in DCM (4.0 mL/mmol) at −78 °C to give a bright yellow
solution, which was warmed to room temperature and stirred for 15
min. Triethylamine (1.1 equiv) was added to give a yellow solution,
which was stirred for 1 h. Volatiles were removed in vacuo to give a
yellow oil, which was extracted into Et2O (3 × 4 mL/mmol). The
extract was concentrated to saturation and filtered over neutral
alumina. Evaporation provided 3 as an off-white solid (mixture of E
and Z isomers; 3a 91%, 3b 75%, 3c 85%, 3d 45%*) (*for
crystallization, a saturated Et2O solution was cooled to −80 °C).
Protocol 3e,f. Diarylphosphane (1.0 equiv) was added dropwise to
a solution of 2a (1.1 equiv) in DCM (4.0 mL/mmol) at −78 °C to
give a bright yellow solution, which was warmed to room temperature
and stirred for 15 min. Triethylamine (1.1 equiv) was added to give a
yellow solution, which was stirred for 1 h. Volatiles were removed in
vacuo to provide a yellow oil, which was extracted into Et2O overnight
(3 × 4 mL/mmol). The extract was concentrated to saturation and
filtered over neutral alumina. Evaporation provided an off-white solid,
which was extracted into pentane (5 mL/mmol). Evaporation of the
extract provided 3e−f (3e 77%*, 3f 53%) (*for crystallization, a
saturated pentane solution was cooled to −80 °C).
1
Data for 3c are as follows. Mp: 46.8−47.4 °C. Since not all H and
13C NMR resonances of E-3c and Z-3c can be distinguished, one set of
1
signals is reported (integrals normalized separately for each isomer). H
NMR (500.23 MHz, CDCl3): δ 7.47−7.38 (m, 6H; P-ArH (E), P-ArH
(Z), C-ArH (E)), 7.33−7.22 (m, 18H; P-ArH (E), P-ArH (Z), C-ArH
(Z)), 7.11 (d, 3JH,H = 8.2 Hz, 2H; C-ArH (Z)), 7.04 (d, 3JH,H = 7.9 Hz,
2H; C-ArH (E)), 3.60 (s; CN-CH3 (Z)), 3.24 (d, 4JH,P = 1.6 Hz; CN-
1
CH3 (E)). 13C{1H} NMR (125.78 MHz, CDCl3): δ 178.0 (d, JC,P
=
9.1 Hz; CN-CH3), 144.6 (d, 2JC,P = 6.4 Hz; C-ipso-ArC), 141.3 (d, 2JC,P
= 24.5 Hz; C-ipso-ArC), 134.7 (d, JC,P = 20.0 Hz, P-ArC), 133.8 (d, JC,P
1
= 19.1 Hz; P-ArC), 133.8 (d, JC,P = 9.1 Hz; P-ipso-ArC), 133.2 (d,
1JC,P = 9.1 Hz; P-ipso-ArC), 130.2 (q, JC,F = 31.8 Hz; CF3), 129.4 (d,
1
J
C,P = 8.2 Hz; P-ArC), 129.0 (d, JC,P = 7.3 Hz; P-ArC), 128.5 (d, JC,P =
7.3 Hz; P-ArC), 128.0 (s; C-ArC (Z)), 127.4 (d, JC,F = 3.6 Hz; C-ArC
(E)), 125.2 (q, JC,F = 3.6 Hz; C-ArC (E)), 125.1 (d, 2JC,F = 14.5 Hz; C-
p-ArC), 124.5 (q, JC,F = 7.7 Hz; C-ArC (Z)), 123.0 (d, 2JC,F = 14.5 Hz;
C-p-ArC), 44.1 (d, 3JC,P = 32.7 Hz; CN-CH3 (Z)), 43.4 (d, 3JC,P = 8.2
Hz; CN-CH3 (E)). 19F NMR (235.36 MHz, CDCl3): δ −62.7 (s; Z
isomer, 55%), −62.8 (s; E isomer, 45%). 31P NMR (161.98 MHz,
1
Data for 3a are as follows. Mp: 79.0−79.4 °C. Since not all H and
13C NMR resonances of E-3a and Z-3a can be distinguished, one set of
1
3
signals is reported (integrals normalized separately for each isomer). H
CDCl3): δ 8.2 (t, JP,H = 6.7 Hz; E isomer, 45%), −7.7 (s; Z isomer,
55%). FT-IR (cm−1): ν 3074 (w), 3065 (w), 3051 (w), 2962 (w),
2932 (w), 1664 (w), 1610 (w), 1582 (m), 1568 (m), 1483 (m), 1435
(m), 1406 (m), 1385 (m), 1321 (s), 1261 (m), 1236 (w), 1157 (s),
1109 (s), 1065 (s), 1009 (s), 999 (s), 970 (m), 918 (m), 843 (s), 818
(m), 802 (m), 771 (m), 743 (s), 696 (s), 681 (s), 650 (s), 615 (s), 598
(m), 579 (w), 546 (m), 507 (s), 482 (s), 447 (s), 430 (m), 419 (m).
HR-MS (ESI-Q-TOF): calcd for C21F3H18NP 372.1123; found
372.1123.
NMR (500.23 MHz, CDCl3): δ 7.45−7.38 (m, 4H; P-ArH (E)),
7.32−7.21 (m, 6H; P-ArH (E) and 10H; ArH (Z)), 7.21−7.13 (m,
3H; C-m,p-ArH (E)), 7.09−7.03 (m, 1H; ArH (Z)), 7.03−6.99 (m,
3
4H; C-ArH (Z)), 6.95 (d, JH,H = 6.6 Hz, 2H; C-o-ArH (E)), 3.57 (s,
4
3H; CN-CH3 (Z)), 3.25 (d, JH,P = 0.9 Hz, 3H; CN-CH3 (E)).
13C{1H} NMR (125.78 MHz, CDCl3): δ 179.2 (d, 1JC,P = 8.2 Hz; CN-
1
2
CH3 (E)), 176.7 (d, JC,P = 42.7 Hz; CN-CH3 (Z)), 141.4 (d, JC,P
=
2
7.3 Hz, C-ipso-ArC (Z)), 137.6 (d, JC,P = 24.5 Hz; C-ipso-ArC (E)),
134.7 (d, JC,P = 19.1 Hz, P-ArC (E)), 134.6 (d, 1JC,P = 10.0 Hz; P-ipso-
ArC (Z)), 133.9 (d, JC,P = 20.0 Hz; P-ArC (Z)), 133.9 (s; P-ipso-ArC
(E)), 129.1 (s; P-ArC (Z)), 129.0 (s; P-ArC (E)), 128.8 (s; P-ArC
(Z)), 128.7 (d, JC,P = 7.3 Hz; C-ArC (E)), 128.5 (d, JC,P = 20.9 Hz; P-
ArC (E)), 128.3 (d, 5JC,P = 7.3 Hz; C-ArC (Z), 128.2 (s; C-ArC (E)),
128.0 (d, 4JC,P = 20.0 Hz; C-ArC (Z)), 127.6 (d, 3JC,P = 5.4 Hz; C-ArC
(Z)), 127.0 (d, 3JC,P = 3.6 Hz; C-o-ArC (E)), 43.9 (d, 3JC,P = 33.6 Hz;
Data for 3d are as follows. Mp: 40.6 °C dec. Since not all 1H and 13
C
NMR resonances of E-3d and Z-3d can be distinguished, one set of signals
1
is reported (integrals normalized separately for each isomer). H NMR
(500.23 MHz, CDCl3): δ 7.71 (d, 3JH,H = 7.6 Hz, 2H; ArH (E)), 7.68−
7.54 (m, 9H; ArH (E), ArH (Z)), 7.49−7.41 (m, 6H; ArH (E), ArH
3
(Z)), 7.31−7.22 (m, 2H; ArH (Z)), 7.14 (t, JH,H = 7.9 Hz, 1H; ArH
3
3
(Z)), 7.08 (t, JH,H = 7.6 Hz, 2H; ArH (Z)), 7.00 (d, JH,H = 7.3 Hz,
3
CN-CH3 (Z)), 43.2 (d, JC,P = 8.2 Hz; CN-CH3 (E)). 31P NMR
3
2H; ArH (E)), 6.97 (d, JH,H = 7.3 Hz, 2H; ArH (Z)), 3.65 (s, 3H;
(161.98 MHz, CDCl3): δ 7.8 (t, 3JP,H = 7.9 Hz; E isomer, 71%); −7.6
CN-CH3 (Z)), 3.34 (s, 3H; CN-CH3 (E)). 13C{1H} NMR (125.78
3
1
(t, JP,H = 7.9 Hz; Z isomer, 29%). FT-IR (cm−1): ν 3069 (m), 2901
MHz, CDCl3): δ 177.5 (d, JC,P = 8.2 Hz; CN-CH3 (E)), 171.8 (s;
CN-CH3 (Z)), 140.3 (d, JC,P = 8.2 Hz; C-ipso-ArC), 137.8 (d, JC,P
2
(m), 2849 (w), 2746 (w), 1599 (s), 1572 (w), 1518 (w), 1479 (s),
1433 (s), 1383 (m), 1367 (w), 1277 (m), 1261 (m), 1242 (m), 1202
(m), 1155 (m), 1090 (m), 1067 (m), 1028 (s), 974 (m), 939 (m), 903
(m), 862 (m), 839 (m), 808 (m), 758 (s), 737 (s), 692 (s), 640 (s),
=
19.1 Hz; ArC), 137.2 (t, JC,P = 10.9 Hz; ArC), 136.8 (d, JC,P = 15.4 Hz;
ArC), 136.6 (d, 2JC,P = 25.4 Hz, C-ipso-ArC), 135.5 (d, 1JC,P = 12.3 Hz;
P-ipso-ArC), 134.9 (d, 1JC,P = 12.7 Hz; P-ipso-ArC), 131.5 (q, JC,F = 3.6
G
DOI: 10.1021/acs.organomet.7b00057
Organometallics XXXX, XXX, XXX−XXX

Organometallics
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Hz; P-ArC (E)), 131.3 (q, JC,F = 3.6 Hz; P-ArC (E)), 131.2−130.3 (m;
P-ArC-CF3, P-ArC), 129.4 (s; ArC), 129.4 (t, JC,P = 2.7 Hz; ArC),
128.9 (d, JC,P = 7.3 Hz; ArC), 128.7 (s; ArC), 128.6 (s; ArC (Z)),
127.9 (s; ArC), 127.3 (s; ArC), 126.9 (d, JC,P = 4.5 Hz; ArC (E)),
126.5 (q, JC,F = 3.6 Hz; P-ArC (Z)), 126.2 (q, JC,F = 3.6 Hz; P-ArC
acetone (10%) was added. The mixture was vigorously shaken and
subsequently kept at room temperature, during which the reaction
mixture was monitored using 31P NMR spectroscopy. Using this
methodology, systematically H2O was added to the mixture, which was
kept at room temperature during the described time span. 3a: (1) 0.50
equiv, 21 h; (2) 0.50 equiv, 68.5 h; (3) 1.00 equiv, 29 h; (4) 2.00
equiv, 26.5 h; (5) 4.00 equiv, 18.5 h; (6) 8.03 equiv, 24.5 h. (7) 481.7
equiv, 22.5 h. Observed hydrolysis (% 3a:% Ph2PH, time of
measurement): (1) 97:0, 21 h; (2) 95:0, 89 h; (3) 91:0, 118 h; (4)
89:0, 144 h; (5) 85:1, 163 h; (6) 85:1, 187 h; (7) 62:4, 210 h. 3b: (1)
0.50 equiv, 18 h; 92) 0.50 equiv, 49 h; (3) 3.00 equiv, 24 h; (4) 12.1
equiv, 25 h; (5) 461.67 equiv, 16 days. Observed hydrolysis (% 3b:%
Ph2PH, time of measurement): (1) 95:0, 18 h; 92) 91:0, 65 h; 93)
88:1, 91 h; (4) 84:2, 115 h; (5) 36:6, 524 h. 3c: (1) 0.46 equiv, 47.5 h;
92) 2.25 equiv, 24 h; (3) 16.9 equiv, 23.5 h; (4) 563.34 equiv, 72 h).
Observed hydrolysis (% 3c:% Ph2PH, time of measurement): (1) 95:0,
41 h; (2) 94:0, 69 h; (3) 92:1, 91 h; (4) 72:3, 165 h.
Acid Stability Study of 3a. 3a (0.0203 g, 0.066 mmol, 1.00 equiv)
was dissolved in 0.4 mL of DCM to give a yellowish solution. Addition
of a solution of TfOH in DCM (0.23 mL of a 0.28 M solution, 0.064
mmol, 0.98 equiv) provided a bright yellow solution, which was
vigorously shaken and kept at room temperature for 20 h, during
which the reaction was monitored using 31P NMR spectroscopy. Next,
again TfOH in DCM (0.23 mL of a 0.28 M solution, 0.064 mmol, 0.98
equiv) was added. The mixture was vigorously shaken and kept at
room temperature for 24 h, during which the reaction was monitored
using 31P NMR spectroscopy. Excess triethylamine (0.20 mL, 1.43
mmol, 21.74 equiv) was added to the mixture at 0 °C, resulting in a
light yellow solution of pure 3a.
Acid-Catalyzed Hydrolysis Study of 3a. 3a (0.0267 g, 0.088
mmol, 1.00 equiv) was dissolved in 0.6 mL of DCM to give a yellowish
solution. Addition of a solution of TfOH in DCM (31 μL of a 0.28 M
solution, 0.009 mmol, 0.10 equiv) provided a more intensely yellow
solution, which was vigorously shaken and kept at room temperature
for 1 h. Subsequently, H2O (0.8 μL, 0.044 mmol, 0.50 equiv) was
added to the mixture, which then was vigorously shaken and kept at
room temperature for 2 days, during which the reaction was monitored
using 31P NMR spectroscopy. Next, excess H2O (5.6 μL, 0.310 mmol,
3.52 equiv) was added to the mixture. After vigorous shaking, the
mixture was kept at room temperature for 24 days. Observed
hydrolysis (% 3a:% Ph2PH, time of measurement): (1) 86:1, 17 h; (2)
76:3, 60 h; (3) 74:3, 108 h; (4) 68:5, 248 h; (5) 58:9, 603 h; (6)
49:12, 1251 h.
Oxidation Study of 3a. Under an N2 atmosphere, 3a (0.012 g,
0.04 mmol, 1.00 equiv) was dissolved in 0.6 mL of acetone. Stepwise,
O2 (21% in air) was bubbled manually through the mixture with a rate
of approximately 6 bubbles per second using a needle with an inner
diameter of 1.194 mm. During additions, the mixture was kept in a
water bath at room temperature to inhibit acetone evaporation. After
each addition, the NMR tube was sealed using a screw cap and the
reaction mixture was monitored using 31P NMR spectroscopy. Using
this methodology, systematically O2 (21% in air) was added to the
mixture at room temperature over the described intervals: (1) O2
(21% in air, 1 mL, 8.73 μmol, 0.22 equiv), 30 s; (2) O2 (21% in air, 1
mL, 8.73 μmol, 0.22 equiv), 30 s; (3) O2 (21% in air, 2 mL, 17.47
μmol, 0.44 equiv), 60 s; (4) O2 (21% in air, 2 mL, 17.47 μmol, 0.44
equiv), 60 s; (5) O2 (21% in air, 4 mL, 34.94 μmol, 0.87 equiv), 2 min;
(6) O2 (21% in air, 4 mL, 34.94 μmol, 0.87 equiv), 2 min; (7) O2
(21% in air, 8 mL, 69.88 μmol, 1.75 equiv), 4 min; (8) O2 (21% in air,
8 mL, 69.88 μmol, 1.75 equiv), 4 min; (9) O2 (21% in air, 16 mL,
0.140 mmol, 3.49 equiv), 8 min; (10) O2 (21% in air, 16 mL, 0.140
mmol, 3.49 equiv), 8 min. From addition 7 onward, a white solid
started to precipitate. After the additions, the mixture was fully
oxidized by dissolving the mixture in 10 mL of acetone (technical
grade) and stirring the resulting solution under a closed air
atmosphere for 42 h at room temperature. Subsequently, the reaction
vessel was opened to the external air atmosphere and stirred for an
additional 173.5 h. The resulting solution was evaporated to provide a
white oil. Observed oxidation (% 3a, time of measurement): (1) 95, 17
min; (2) 86, 24 min; (3) 82, 30 min; (4) 74, 37 min; (5) 68, 46 min.;
1
1
(E)), 124.0 (q, JC,F = 272.5 Hz; CF3 (E)), 123.8 (qd, JC,F = 272.5,
3
4JC,P = 5.4 Hz; CF3 (Z)), 44.1 (d, JC,P = 34.5 Hz; CN-CH3(Z)), 43.2
(d, 3JC,P = 8.2 Hz; CN-CH3 (E)). 19F NMR (235.36 MHz, CDCl3): δ
−62.8 (s; E isomer, 62%), −62.9 (s; Z isomer, 38%). 31P NMR
(161.98 MHz, CDCl3): δ 5.9 (t, 3JP,H = 6.5 Hz; E isomer, 83%), −8.5
(s; Z isomer, 17%). FT-IR (cm−1): ν 3065 (w), 2962 (w), 1624 (m),
1603 (m), 1522 (m), 1479 (w), 1443 (m), 1416 (m), 1367 (w), 1321
(s), 1310 (s), 1259 (s), 1225 (m), 1161 (s), 1107 (s), 1088 (s), 1067
(s), 1028 (s), 999 (s), 935 (w), 905 (m), 891 (w), 866 (w), 795 (s),
762 (m), 743 (m), 692 (s), 683 (s), 636 (s), 611 (m), 575 (m), 542
(m), 517 (s), 482 (s), 467 (s), 453 (s). HR-MS (ESI-Q-TOF): calcd
for C22F6H17NP 440.0997; found 440.1002.
Data for 3e are as follows. Mp: n.a. (≤−20 °C). Since not all 1H and
13C NMR resonances of E-3e and Z-3e can be distinguished, one set of
1
signals is reported (integrals normalized separately for each isomer). H
NMR (500.23 MHz, CDCl3): δ 7.25−7.12 (m, 13H; ArH), 7.12−7.06
(m, 9H; ArH), 7.06−7.00 (m, 4H; ArH), 6.96 (d, 3JH,H = 7.6 Hz, 2H;
ArH (E)), 3.58 (s, 3H; CN-CH3 (Z)), 3.26 (s, 3H; CN-CH3 (E)), 2.26
(s, 6H; P-Ar-CH3 (E)), 2.24 (s, 6H; P-Ar-CH3 (Z)). 13C{1H} NMR
1
(125.78 MHz, CDCl3): δ 179.4 (d, JC,P = 7.3 Hz; CN-CH3 (E)),
1
2
177.0 (d, JC,P = 42.7 Hz; CN-CH3 (Z)), 141.5 (d, JC,P = 7.3 Hz; C-
ipso-ArC (Z)), 138.3 (d, 3JC,P = 7.3 Hz; P-ArC-CH3), 137.8 (d, 3JC,P
=
8.2 Hz; P-ArC-CH3), 137.8 (d, 2JC,P = 24.5 Hz; C-ipso-ArC (E)), 135.5
(d, JC,P = 20.9 Hz; ArC), 134.6 (d, JC,P = 21.8 Hz; ArC), 134.3 (d, 1JC,P
= 9.1 Hz; P-ipso-ArC), 133.7 (d, 1JC,P = 9.1 Hz; P-ipso-ArC), 131.7 (d,
JC,P = 17.3 Hz; ArC), 130.8 (d, JC,P = 17.3 Hz; ArC), 129.8 (d, JC.P
=
20.9 Hz; ArC), 129.0 (d, JC,P = 39.1 Hz; ArC), 128.5 (d, JC,P = 7.3 Hz;
ArC), 128.2 (d, JC,P = 7.3 Hz; ArC), 128.0 (d, JC,P = 19.1 Hz; ArC),
127.5 (d, JC,P = 22.7 Hz; ArC (Z)), 127.1 (s; ArC (E)), 127.0 (s; ArC
3
3
(E)), 43.9 (d, JC,P = 33.6 Hz; CN-CH3 (Z)), 43.3 (d, JC,P = 9.1 Hz;
CN-CH3 (E)), 21.6 (s; P-Ar-CH3 (E)), 21.5 (s; P-Ar-CH3 (Z)). 31P
NMR (161.98 MHz, CDCl3): δ 8.3 (s; E isomer, 68%), −7.5 (s; Z
isomer, 32%). FT-IR (cm−1): ν 3050 (w), 2924 (w), 2859 (w), 2359
(w), 2328 (w), 1738 (w), 1591 (m), 1520 (w), 1476 (w), 1443 (w),
1370 (w), 1265 (s), 1229 (w), 1200 (w), 1107 (w), 1074 (w), 1028
(w), 997 (w), 972 (w), 895 (w), 779 (m), 762 (w), 731 (s). HR-MS
(ESI-Q-TOF): calcd for C22H23NP 332.1563; found 332.1564.
1
Data for 3f are as follows. Mp: 64.3−65.6 °C. Since not all H and
13C NMR resonances of E-3f and Z-3f can be distinguished, one set of
1
signals is reported (integrals normalized separately for each isomer). H
3
NMR (500.23 MHz, CDCl3): δ 7.32 (t, JH,P = 7.7 Hz, 4H; P-ArH
(E)), 7.24−7.15 (m, 8H; C-m-ArH (E), ArH (Z)), 7.12−7.02 (m,
3
12H; P-ArH (E), C-p-ArH (E), ArH (Z)), 7.00 (dd, JH,H = 7.9 Hz,
4JH,P = 1.6 Hz, 2H; C-o-ArH (E)), 3.55 (s, 3H; CN-CH3 (Z)), 3.24 (d,
4JH,P = 1.9 Hz, 3H; CN-CH3 (E)), 2.30 (s, 6H; P-C6H4-CH3 (E,Z)).
13C{1H} NMR (125.78 MHz, CDCl3): δ 179.6 (s; CN-CH3), 139.1 (s;
P-ArC-CH3), 137.8 (d, JC,P = 25.4 Hz; ipso-ArC), 134.8 (d, JC,P = 20.0
Hz; P-ArC (E)), 134.0 (d, JC,P = 20.0 Hz; P-ArC (Z)), 131.0 (d, JC,P
=
7.3 Hz; ipso-ArC), 130.5 (d, JC,P = 7.3 Hz; ipso-ArC), 129.6 (s; ArC),
129.5 (s; ArC), 129.2 (s; ArC), 129.1 (s; ArC), 128.2 (s; ArC), 128.1
(s; ArC), 127.9 (d, JC,P = 2.7 Hz; ArC), 127.7 (s; ArC), 127.5 (s; ArC),
3
127.1 (d, JC,P = 4.5 Hz; C-o-ArC (E)), 43.4 (d, JC,P = 32.7 Hz; CN-
3
5
CH3 (Z)), 43.2 (d, JC,P = 8.2 Hz; CN-CH3 (E)), 21.5 (d, JC,P = 9.1
Hz; P-ArC-CH3 (E,Z)). 31P NMR (161.98 MHz, CDCl3): δ 6.3 (s; E
isomer, 76%), −8.8 (s; Z isomer, 24%). FT-IR (cm−1): ν 3063 (w),
3032 (w), 3015 (w), 2961 (m), 2910 (m), 2854 (w), 1653 (w), 1632
(w), 1591 (s), 1560 (w), 1524 (w), 1495 (s), 1439 (s), 1394 (m),
1306 (m), 1259 (s), 1202 (m), 1186 (m), 1099 (s), 1092 (s), 1070
(s), 1018 (s), 972 (m), 935 (m), 897 (m), 866 (w), 843 (m), 797 (s),
762 (s), 700 (s), 673 (m), 652 (s), 642 (s), 629 (s), 615 (s), 552 (w),
536 (s), 503 (s), 492 (s), 451 (s), 420 (m), 401 (s). HR-MS (ESI-Q-
TOF): calcd for C22H23NP 332.1563; found 332.1562.
Hydrolysis Study of 3a−c. 3 (0.02 g, 1.00 equiv) was dissolved in
0.6 mL of acetone in an NMR tube. Next, a solution of H2O in
H
DOI: 10.1021/acs.organomet.7b00057
Organometallics XXXX, XXX, XXX−XXX

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(6) 61, 55 min; (7) 56, 66 min; (8) 52, 77 min; (9) 49, 91 min; (10)
44, 107 min; (11) 4, 46 h; (12) 0, 220 h.
sulfonates 6a,c,e. Under an argon atmosphere, to a solution of 3
(0.31 mmol, 2.1 equiv) in 14 mL of DCM was added [RhCp*Cl2]2
(95 mg, 0.15 mmol, 1.0 equiv) to provide a red solution, which was
stirred for 30 min at room temperature. Next, AgOTf (79 mg, 0.30
mmol, 2.0 equiv) was added and the resulting suspension was stirred
for 60 min at room temperature in the absence of light, during which
the mixture turned bright orange. Filtration provided an orange-red
solution, which was evaporated to provide a yellow-orange solid. After
washing (6a,e: 3 × 5 mL of Et2O; 6c, 3 × 5 mL of pentane), 6 was
obtained as an orange powder (6a. quantitative; 6c, 97%; 6e, 97%).
( ( ( N - M e t h y l ) a r y l i m i d o y l ) d i a r y l p h o s p h a n y l ) -
(pentamethylcyclopentadienyl)rhodium(III) Dichlorides 4a,c,e.
Under an argon atmosphere, a solution of 3 (102 mg 0.34 mmol, 2.4
equiv) in 9 mL of DCM was added to a red-brown solution of
[RhCp*Cl2]2 (87 mg, 0.14 mmol, 1.0 equiv) in 5 mL of DCM. The
resulting red-brown solution was stirred for 30 min at room
temperature. Evaporation of the obtained red solution provided a
red-orange solid, which was washed with 3 × 5 mL of Et2O to provide
4 as an orange solid (4a, 90%; 4c, 68%; 4e, 92%). For crystallization,
subsequently Et2O and pentane were diffused into a DCM solution at
room temperature. Next, the solution was slowly cooled to provide red
needles.
1
Data for 6a are as follows. Mp: 138.8 °C. H NMR (500.23 MHz,
CDCl3): δ 7.66−7.59 (m, 8H; P-ArH), 7.47−7.42 (m, 3H; C-o-ArH,
3
3
P-ArH), 7.36 (t, JH,H = 6.9 Hz, 2H; C-m-ArH), 7.23 (d, JH,H = 7.6
Hz, 2H; C-o-ArH), 3.69 (d, 3JH,Rh = 3.8 Hz; N−CH3), 1.70 (d, 3JH,Rh
3.8 Hz; Cp*-CCH3). 13C{1H} NMR (125.78 MHz, CDCl3): δ 190.9
(dd, JC,P = 50.0 Hz, JC,Rh = 2.7 Hz; CN-CH3), 136.7 (d, JC,P = 11.8
=
1
Data for 4a are as follows. Mp: 164.6 °C. H NMR (500.23 MHz,
1
2
2
CDCl3): δ 7.71 (s, 5H; P-ArH), 7.18 (s, 5H; P-ArH), 6.99 (s, 3H; C-
o,p-ArH), 6.92 (s, 2H; C-m-ArH), 3.36 (s, 3H; NCH3), 1.44 (s, 15H;
4
3
Hz; P-m-ArC), 133.8 (d, JC,P = 2.7 Hz; P-p-ArC), 133.0 (d, JC,P
=
2
Cp*-CCH3). 13C{1H} NMR (125.78 MHz, CDCl3): δ 137.0 (d, JC,P
10.9 Hz; P-o-ArC), 132.9 (d, 4JC,P = 2.7 Hz; P-p-ArC), 132.3 (dd, 3JC,Rh
1
2
= 11.8 Hz, P-o-ArC), 135.4 (d, JC,P = 22.7 Hz; P-ipso-ArC), 130.2 (s;
= 7.3 Hz, JC,P = 1.8 Hz; C-ipso-ArC), 131.8 (s; C-p-ArC), 130.4 (d,
3JC,P = 10.9 Hz; P-m-ArC), 129.4 (d, JC,P = 11.8 Hz; P-o-ArC), 129.2
2
P-p-ArC), 127.8 (s; C-p-ArC), 127.7 (s; C-o-ArC), 127.4 (s; P-m-ArC),
1
(s; C-m-ArC), 127.5 (d, 2JC,P = 1.8 Hz; C-o-ArC), 123.7 (d, 1JC,P = 45.4
127.0 (s; C-m-ArC), 99.7 (d, JC,Rh = 5.5 Hz; Cp*-CCH3), 43.1 (d,
3JC,P = 21.8 Hz; CN-CH3), 9.0 (s; Cp*-CCH3), signals for C-ipso-ArC
and CN-CH3 are unresolved. 31P NMR (161.98 MHz, DCM): δ 37.3
Hz; P-ipso-ArC), 121.2 (q, 1JC,F = 320.6 Hz; O3SCF3), 120.7 (d, 1JC,P
=
1
2
36.3 Hz; P-ipso-ArC), 99.8 (dd, JC,Rh = 7.3 Hz, JC,P = 2.7 Hz; Cp*-
CCH3), 44.7 (d, 2JC,Rh = 18.2 Hz; NCH3), 9.6 (d, 2JC,Rh = 1.8 Hz; Cp*-
CCH3). 19F NMR (235.36 MHz, CDCl3): δ −78.2 (s). 31P NMR
(161.98 MHz, DCM): δ −9.1 (d, 1JP,Rh = 113.4 Hz). FT-IR (cm−1): ν
3065 (w), 2978 (w), 2908 (w), 1603 (w), 1479 (w), 1439 (m), 1381
(w), 1265 (s), 1240 (s), 1221 (s), 1188 (w), 1140 (s), 1097 (m), 1078
(m), 1030 (s), 997 (m), 951 (w), 854 (w), 847 (m), 814 (w), 752 (s),
719 (m), 692 (s), 635 (s), 565 (m), 517 (s), 482 (s), 463 (s), 440 (s).
HR-MS (ESI-Q-TOF): calcd for C30H33ClNPRh+ 576.1089; found
576.1112.
1
1
(d, JP,Rh = 146.6 Hz; 4a, 96%), −2.2 (d, JP,Rh = 113.0 Hz; 5a, 4%).
FT-IR (cm−1): ν 3055 (w), 2961 (w), 2914 (w), 1609 (m), 1609 (m),
1572 (w), 1489 (m), 1479 (m), 1433 (s), 1383 (m), 1369 (w), 1261
(m), 1209 (m), 1200 (m), 1188 (m), 1157 (m), 1092 (s), 1072 (s),
1022 (s), 970 (m), 951 (m), 860 (w), 800 (s), 764 (s), 743 (s), 690
(s), 648 (m), 611 (m), 550 (s), 511 (s), 494 (s), 469 (s), 451 (s), 430
(m), 401 (s). HR-MS (ESI-Q-TOF): calcd for C30H34Cl2NPRh+
612.0855; found 612.0873.
1
Data for 4c are as follows. Mp: 200.7 °C dec. H NMR (400.13
1
MHz, CDCl3): δ 7.71 (br. s, 4H; P-ArH), 7.42−7.09 (br. m, 8H; C-o-
Data for 6c are as follows. Mp: 120.9−128.5 °C. H NMR (500.23
ArH, P-ArH), 7.02 (d, 3JH,H = 7.1 Hz, 2H; C-m-ArH), 3.32 (d, 3JH,P
=
MHz, CDCl3): δ 7.74−7.66 (m, 6H; P-o,p-ArH), 7.66−7.58 (m, 4H;
3
3
2.8 Hz, 3H; CN-CH3), 1.43 (d, JH,Rh = 3.5 Hz, 15H; Cp*-CCH3).
P-m-ArH, C-o-ArH), 7.53−7.46 (m, 2H; P-m-ArH), 7.41 (d, JH,H
=
1
13C{1H} NMR (125.78 MHz, CDCl3): δ 175.1 (d, JC,P = 57.2 Hz;
3
7.9 Hz, 2H; C-m-ArH), 3.68 (d, JH,Rh = 4.1 Hz, 3H; CN-CH3), 1.71
CN-CH3), 139.1 (d, 1JC,P = 20.9 Hz; P-ipso-ArC), 135.4 (br. s; P-ArC),
(d, JH,Rh = 4.7 Hz, 15H; Cp*-CCH3). 13C{1H} NMR (125.78 MHz,
3
130.6 (s; P-ArC), 129.8 (q, 2JC,F = 32.7 Hz; C-p-ArC), 127.7 (s; C-m-
CDCl3): δ 189.6 (dd, 1JC,P = 50.0 Hz, 2JC,Rh = 4.5 Hz; CN-CH3), 136.8
4
1
2
3
ArC), 124.6 (q, JC,F = 3.6 Hz; C-o-ArC), 124.2 (q, JC,F = 272.5 Hz;
(d, JC,P = 11.8 Hz; P-m-ArC), 135.1 (d, JC,Rh = 7.3 Hz; C-ipso-ArC),
1
2
134.0 (d, 4JC,P = 2.7 Hz; P-p-ArC), 133.1 (t, 2JC,F = 33.6 Hz; C-p-ArC),
CF3), 99.8 (dd, JC,Rh = 6.4 Hz, JC,P = 2.7 Hz; Cp*-CCH3), 43.2 (d,
3JC,P = 20.9 Hz; CN-CH3), 9.0 (s; Cp*-CCH3), signals for C-ipso-ArC
and one P-ArC are unresolved. 19F NMR (235.36 MHz, CDCl3): δ
2
2
133.1 (d, JC,P = 10.9 Hz; P-o-ArC), 130.6 (d, JC,P = 10.9 Hz; P-o-
ArC), 129.5 (d, 3JC,P = 10.9 Hz; P-m-ArC), 128.4 (s; C-m-ArC), 126.2
(q, JC,F = 3.6 Hz; C-o-ArC), 123.4 (q, JC,F = 272.6 Hz; C-Ar-CF3),
3
1
−63.3 (s). 31P NMR (161.98 MHz, DCM): δ 35.1 (d, JP,Rh = 146.9
1
1
1
Hz). FT-IR (cm−1): ν 3057 (w), 2989 (w), 2953 (w), 2908 (w), 1624
(w), 1614 (w), 1572 (w), 1508 (m), 1479 (m), 1448 (m), 1433 (s),
1406 (m), 1369 (m), 1321 (s), 1263 (w), 1205 (w), 1188 (m), 1165
(s), 1122 (s), 1109 (s), 1090 (m), 1067 (s), 1020 (s), 997 (m), 972
(m), 933 (w), 924 (w), 837 (s), 800 (w), 743 (s), 696 (s), 689 (s),
663 (m), 619 (m), 606 (m), 550 (s), 509 (s), 498 (s), 465 (s), 449 (s),
432 (m). HR-MS (ESI-Q-TOF): calcd for C31H33Cl2F3NPRh+
680.0705; found 680.0705.
123.1 (d, JC,P = 44.5 Hz; P-ipso-ArC), 121.2 (q, JC,F = 320.6 Hz;
O3SCF3), 120.5 (d, 1JC,P = 34.5 Hz; P-ipso-ArC), 99.9 (dd, 1JC,Rh = 7.3
2
2
Hz, JC,P = 2.7 Hz; Cp*-CCH3), 45.1 (d, JC,Rh = 18.2 Hz; CN-CH3),
9.6 (s; Cp*-CCH3), signal for one P-p-ArC is unresolved. 19F NMR
(235.36 MHz, CDCl3): δ −63.2 (s; CF3), −78.2 (s; O3SCF3). 31P
1
NMR (161.98 MHz, DCM): δ −5.0 (d, JP,Rh = 114.7 Hz). FT-IR
(cm−1): ν 3072 (w), 2926 (w), 1616 (w), 1481 (w), 1456 (w), 1437
(w), 1406 (w), 1379 (w), 1323 (s), 1258 (s), 1223 (m), 1128 (m),
1113 (m), 1101 (m), 1067 (m), 1067 (m), 1030 (s), 993 (m), 993
(m), 839 (m), 839 (m), 746 (m), 746 (m), 719 (w), 690 (m), 636 (s),
571 (m), 527 (m), 517 (m), 492 (m), 474 (m), 444 (m). HR-MS
(ESI-Q-TOF): calcd for C31H32ClF3NPRh+ 644.0963; found
644.0967.
1
Data for 4e are as follows. Mp: 139.6 °C dec. H NMR (500.23
MHz, CDCl3): δ 7.66−7.35 (m, 5H; P-ArH), 7.22−6.95 (m, 6H; C-
ArH, P-ArH), 6.91 (s, 2H; C-ArH), 3.35 (s, 3H; CN-CH3), 2.19 (br. s,
3
6H; P-ArCH3), 1.43 (d, JH,Rh = 2.8 Hz, 15H; Cp*-CCH3). 13C{1H}
3
NMR (125.78 MHz, CDCl3): δ 176.6 (d, JC,P = 60.9 Hz; CN-CH3),
1
135.6 (d, 1JC,P = 20.9 Hz; P-ipso-ArC), 134.4 (d, JC,P = 2.7 Hz; P-ArC),
Data for 6e are as follows. Mp: 153.2 °C dec. H NMR (500.23
MHz, CDCl3): δ 7.59−7.53 (m, 1H; P-ArH), 7.48−7.30 (m, 10H; P-
ArH, C-m,p-ArH), 7.23 (d, 3JH,H = 7.6 Hz, 2H; C-o-ArH), 3.7 (d, 3JH,Rh
= 4.1 Hz, 3H; CN-CH3), 2.45 (s, 3H; P-Ar-CH3), 2.29 (s, 3H; P-Ar-
130.9 (s; P-ArC), 129.9 (d, JC,P = 12.7 Hz; P-ArC), 129.1 (d, JC,P
=
11.8 Hz; P-ArC), 127.7 (s; C-ArC), 127.5 (s; C-ArC), 126.9 (s; C-
1
2
ArC), 99.6 (dd, JC,Rh = 6.4 Hz, JC,P = 2.7 Hz; Cp*-CCH3), 43.1 (d,
3JC,P = 21.8 Hz; CN-CH3), 21.5 (s; P-ArCH3), 9.0 (d, 2JC,Rh = 1.8 Hz;
Cp*-CCH3), signals for C-ipso-ArC and P-Ar C-CH3 are unresolved.
3
CH3), 1.70 (d, JH,Rh = 4.4 Hz, 15H; Cp*-CCH3). 13C{1H} NMR
1
2
(125.78 MHz, CDCl33): δ 191.0 (dd, JC,P = 50.0 Hz, JC,Rh = 3.6 Hz;
3
1
31P NMR (161.98 MHz, DCM): δ 34.7 (d, JP,Rh = 144.6 Hz; 4e,
CN-CH3), 140.7 (d, JC,P = 10.9 Hz; P-ArC-CH3), 139.2 (d, JC,P
=
1
10.9 Hz; P-Ar C-CH3), 137.0 (d, JC,P = 10.9 Hz; P-ArC), 134.5 (d, JC,P
= 2.7 Hz; P-ArC), 133.8 (s; P-ArC), 132.9 (d, JC,P = 10.9 Hz; P-ArC),
132.4 (d, 3JC,Rh = 7.3 Hz; C-ipso-ArC), 131.7 (s; C-p-ArC), 130.3 (dd,
94%), −12.1 (d, JP,Rh = 114.7 Hz; 5e, 6%). FT-IR: ν = 2962 (m),
2907 (w), 1479 (w), 1443 (w), 1400 (w), 1258 (s), 1078 (s), 1011 (s),
864 (m), 789 (s), 690 (s), 662 (m), 611 (w), 557 (m), 542 (m), 480
(m), 465 (s), 465 (s). HR-MS (ESI-Q-TOF): calcd for
C32H38Cl2NPRh+ 640.1168; found 640.1163.
2JC,P = 11.4 Hz, JC,Rh = 3.2 Hz; P-o-ArC), 129.1 (s; C-m-ArC), 127.6
3
1
1
(s; C-o-ArC), 123.6 (d, JC,P = 43.6 Hz; P-ipso-ArC), 121.2 (q, JC,F
=
1
320.6 Hz; O3SCF3), 120.4 (d, JC,P = 36.3 Hz; P-ipso-ArC), 99.7 (dd,
Chloro(((N-methyl)arylimidoyl)diarylphosphanyl)-
(pentamethylcyclopentadienyl)rhodium(III) Trifluoromethyl-
1JC,Rh = 7.3 Hz, 2JC,P = 2.7 Hz; Cp*-CCH3), 44.6 (d, 2JC,Rh = 19.1 Hz;
I
DOI: 10.1021/acs.organomet.7b00057
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
4
CN-CH3), 21.5 (d, JC,P = 1.8 Hz; P-Ar-CH3), 9.6 (s; Cp*-CCH3),
signals for three P-p-ArC are unresolved. 19F NMR (235.36 MHz,
CDCl3): δ −78.6 (s). 31P NMR (161.98 MHz, DCM): δ −8.5 (d,
1JP,Rh = 112.4 Hz). FT-IR (cm−1): ν 3065 (w), 2962 (w), 2920 (w),
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.7b00057.
■
S
1655 (w), 1593 (w), 1541 (w), 1474 (m), 1447 (m), 1375 (m), 1319
(w), 1259 (s), 1223 (s), 1205 (s), 1146 (s), 1107 (s), 1080 (s), 1030
(s), 995 (s), 864 (w), 789 (s), 762 (s), 690 (s), 636 (s), 569 (s), 548
(s), 517 (s), 496 (w), 474 (m), 446 (s). HR-MS (ESI-Q-TOF): calcd
for C32H37ClNPRh+ 604.1402; found 604.1409.
Additional synthetic details, NMR spectra, and geo-
metries of computed structures (PDF)
X-ray crystallographic data for 4a (CCDC-1487761), 4e
(CCDC-1487762), 6a (CCDC-1487763), and 7a
(CCDC-1487764) (CIF)
[(((N-Methyl)phenylimidoyl)diphenylphosphanyl)-
( p e n t a m e t h y l c y c l o p e n t a d i e n y l ) r h o d i u m ( I I I )
( t r i flu o r o m e th y l s u l fo n at e ) ] [ p o l y( d is i l ve r ( I ) tr i s -
(trifluoromethanesulfonate)(methylene chloride))] (7a). Under
an argon atmosphere, to a solution of 3a (92 mg 0.30 mmol, 2.0
equiv) in 15 mL of DCM was added [RhCp*Cl2]2 (94 mg 0.15 mmol,
1.0 equiv) to provide a red solution, which was stirred for 30 min at
room temperature. Next, AgOTf (317 mg, 1.23 mmol, 8.2 equiv) was
added and the resulting suspension was stirred for 60 min at room
temperature in the absence of light, during which the mixture turned
yellow. Filtration provided an orange-red solution, which was
evaporated to provide an orange-red solid. After washing with 20
mL of pentane, 7a was obtained as a yellow solid (306 mg, 0.21 mmol,
71%). For crystallization, slow diffusion of pentane (55 mL/mmol of
compound) into a DCM solution (45 mL/mmol of compound) at
room temperature provided red blocks. Mp: 178.6 °C. 1H NMR
(500.23 MHz, CDCl3): δ 7.76−7.63 (m, 6H; P-o,p-ArH), 7.49−7.46
Cartesian coordinates for calculated structures (XYZ)
AUTHOR INFORMATION
Corresponding Authors
*E-mail for J.C.S.: j.c.slootweg@uva.nl.
*E-mail for K.L.: k.lammertsma@vu.nl.
ORCID
■
Koop Lammertsma: 0000-0001-9162-5783
Present Address
⊥HIMS, University of Amsterdam, Science Park 904, 1098 XH
Amsterdam, The Netherlands.
Notes
The authors declare no competing financial interest.
3
(m, 5H; P-m-ArH, C-p-ArH), 7.40 (t, JH,H = 7.7 Hz, 2H; C-m-ArH),
3
3
ACKNOWLEDGMENTS
7.33 (d, JH,H = 7.6 Hz, 2H; C-o-ArH), 4.01 (d, JH,Rh = 4.4 Hz, 3H;
■
CN-CH3), 1.72 (d, 3JH,Rh = 5.0 Hz, 15H; Cp*-CCH3). 13C{1H} NMR
This work was supported by the Council for Chemical Sciences
of The Netherlands Organization for Scientific Research
(NWO/CW) and by ARKEMA Vlissingen B.V.
1
2
(125.78 MHz, CDCl3): δ 193.9 (dd, JC,P = 48.1 Hz, JC,Rh = 3.6 Hz;
CN-CH3), 136.2 (dd, 3JC,P = 11.8 Hz, 4JC,Rh = 3.6 Hz; P-m-ArC), 134.4
(d, 4JC,P = 8.2 Hz; P-p-ArC), 133.6 (d, 4JC,P = 7.3 Hz; P-p-ArC), 133.3
(d, 2JC,P = 10.9 Hz; P-o-ArC), 132.3 (s; C-p-ArC), 132.1 (d, 2JC,P = 6.4
REFERENCES
■
2
3
Hz; C-ipso-ArC), 130.8 (d, JC,P = 8.2 Hz; P-o-ArC), 129.7 (d, JC,P
=
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