Improving intramolecular hydroamination Rh(i) and Ir(i) catalysts through targeted ligand modification

Article abstract of DOI:10.1039/b9nj00759h

A series of complexes containing the phosphino-pyrazolyl ligand 1-(2-(diphenylphosphino)phenyl)pyrazole (PyPhP) and 1-(2-(diphenylphosphino) ethyl)pyrazole (PyP) were synthesized: [Ir(PyPhP)(COD)]BPh₄, [Ir(PyPhP)(CO)₂]BPh₄, Rh(PyPhP)(CO)Cl and Ir(PyPhP)(CO)Cl. The complexes Rh(PyP)(CO)OSO₂CF₃ and Rh(PyPhP)(CO) OSO₂CF₃ were also synthesized, using the parent complexes Rh(PyP)(CO)Cl and Rh(PyPhP)(CO)Cl. The solid-state structures of the new complexes were determined by X-ray diffraction analysis. The cationic Ir(i) complex [Ir(PyPhP)(COD)]BPh₄ was found to be a highly efficient catalyst for the intramolecular hydroamination of 4-pentyn-1-amine, achieving a turnover rate of 1500 h^-1, with >98% conversion in 6 minutes. The efficiency of the catalyzed hydroamination of 4-pentyn-1-amine using the neutral Ir(i) and Rh(i) complexes as catalysts was significantly improved by generating active catalysts in situ through abstraction of a chloride ligand by reaction with AgOSO₂CF₃, TMSOSO₂CF₃ or NaBPh₄. The catalytic efficiency of the catalysts generated from Ir(PyP)(CO)Cl and a sodium salt were found to be inversely proportional to the coordinating strength of the counter-ion of the sodium salt. Rh(PyP)(CO)OSO ₂CF₃ is a more efficient catalyst for the cyclization of 4-pentyn-1-amine than the complex generated in situ from AgOSO ₂CF₃ and chloride complex Rh(PyP)(CO)Cl indicating that the higher lability of the triflate co-ligand of Rh(PyP)(CO)OSO ₂CF₃, compared to the chloride co-ligand of Rh(PyP)(CO)Cl, enhances the catalytic activity of the Rh(i) complexes.

Full text of DOI:10.1039/b9nj00759h

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Improving intramolecular hydroamination Rh(I) and Ir(I) catalysts
through targeted ligand modificationw
Sophie R. Beeren,a Serin L. Dabb,a Gavin Edwards,a Matthew K. Smith,b
Anthony C. Willisb and Barbara A. Messerle*a
Received (in Victoria, Australia) 15th December 2009, Accepted 27th January 2010
First published as an Advance Article on the web 25th February 2010
DOI: 10.1039/b9nj00759h
A series of complexes containing the phosphino-pyrazolyl ligand
1-(2-(diphenylphosphino)phenyl)pyrazole (PyPhP) and 1-(2-(diphenylphosphino)ethyl)pyrazole
(PyP) were synthesized: [Ir(PyPhP)(COD)]BPh4, [Ir(PyPhP)(CO)2]BPh4, Rh(PyPhP)(CO)Cl and
Ir(PyPhP)(CO)Cl. The complexes Rh(PyP)(CO)OSO2CF3 and Rh(PyPhP)(CO)OSO2CF3 were
also synthesized, using the parent complexes Rh(PyP)(CO)Cl and Rh(PyPhP)(CO)Cl.
The solid-state structures of the new complexes were determined by X-ray diffraction analysis.
The cationic Ir(I) complex [Ir(PyPhP)(COD)]BPh4 was found to be a highly efficient catalyst for
the intramolecular hydroamination of 4-pentyn-1-amine, achieving a turnover rate of 1500 hꢀ1
with 498% conversion in 6 minutes. The efficiency of the catalyzed hydroamination of
4-pentyn-1-amine using the neutral Ir(I) and Rh(I) complexes as catalysts was significantly
improved by generating active catalysts in situ through abstraction of a chloride ligand by
reaction with AgOSO2CF3, TMSOSO2CF3 or NaBPh4. The catalytic efficiency of the catalysts
,
generated from Ir(PyP)(CO)Cl and a sodium salt were found to be inversely proportional to the
coordinating strength of the counter-ion of the sodium salt. Rh(PyP)(CO)OSO2CF3 is a more
efficient catalyst for the cyclization of 4-pentyn-1-amine than the complex generated in situ from
AgOSO2CF3 and chloride complex Rh(PyP)(CO)Cl indicating that the higher lability of the
triflate co-ligand of Rh(PyP)(CO)OSO2CF3, compared to the chloride co-ligand of
Rh(PyP)(CO)Cl, enhances the catalytic activity of the Rh(I) complexes.
A number of rhodium and iridium complexes have been
Introduction
reported to catalyze intramolecular hydroamination very
effectively.15–26 We have developed Rh(I) and Ir(I) catalysts
which promote the formation of synthetically useful N-hetero-
cycles via the cyclization of alkynylamines.18–24,26 In particular
the alkynylamine 4-pentyn-1-amine (1) has been cyclized to
form 2-methylpyrroline (2) using a series of rhodium(I) and
iridium(I) catalysts with general formula [M(L-L)(C2)][BPh4]
where L-L is either a bidentate N-N-,18,21,22,24 P-C-,20
C-C-,23 or P-N-19 donor ligand and C2 is either two carbon
monoxide (CO) co-ligands or a chelating 1,5-cyclooctadiene
(COD) ligand. Of this group of complexes the most efficient
catalysts for the formation of 2 were found to be iridium(I)
complexes containing either a combination of P-N and COD
ligands,19 or N-N and CO ligands,18 with conversions of 98%
in less than 1.5 hours at 60 1C. Catalysts containing a mixed
P-N-donor ligand, such as 3, promoted turnover frequencies
ranging from 1200 to 3100 hꢀ1 for the cyclization of 1 to 2
(Fig. 1).19 These turnover frequencies are among the highest of
any rates reported to date for the catalyzed cyclization of 1 by
a late transition metal catalyst.10,12,14 Reported here are
investigations into the effect that replacing the PyP ligand
with a more rigid P,N-donor ligand in complexes of general
formula [M(P-N)(C2)][BPh4] has on catalyst efficiency.
Hydroamination is the addition of amine N–H bonds across
carbon–carbon multiple bonds and provides an atom efficient
route for the synthesis of amines, enamines and imines.1–3
The importance of these molecules as feedstocks for the
synthesis of bulk or fine chemicals and as intermediates in
organic chemistry is illustrated by the yearly production of
amines worldwide, which reaches several millions of tons.2
N-Heterocycles, which can be formed by catalyzed intra-
molecular hydroamination, are particularly important because
they are commonly key components of biologically significant
organic compounds and their synthesis is therefore important
to the pharmaceutical, agrochemical and dye industries.
Catalytic systems employed for the intramolecular hydro-
amination reaction include Group 2 metals,4 lanthanides,5
actinides,6 early7 and late8–14 transition metals. Late transition
metal complexes have an advantage over lanthanides and early
transition metal complexes due to their lower oxophilicity,
which means they are less sensitive to moisture and air and
have a greater functional group tolerance.
a School of Chemistry, University of New South Wales,
New South Wales 2052, Australia. E-mail: b.messerle@unsw.edu.au
b Research School of Chemistry, Australian National University,
Canberra, ACT, Australia
w CCDC reference numbers 291181 (6), 291475 (8), 291177 (9), 291474
(10), 729970 (11). For crystallographic data in CIF or other electronic
format see DOI: 10.1039/b9nj00759h
The first step of the majority of mechanisms previously
proposed for the late-transition metal catalyzed intramolecular
hydroamination reaction involves the binding of the substrate
ꢁc
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Scheme 1 COD = cyclooctadiene.
Fig. 1 Intramolecular hydroamination of 1 to form 2 using Rh(I) and
Ir(I) catalysts.
to a coordinatively unsaturated metal center. The unsaturated
metal center can be formed through either dissociation of a
labile ligand9,12,17 or the irreversible abstraction of a bound
ligand to create an activated metal catalyst in situ.11,16 For
example, when using Cu(II) based catalysts, dissociation of
one labile ligand from CuX2 (where [X]ꢀ = [OCOCF3]ꢀ,
[OSO2CF3]ꢀ or [OAc]ꢀ) was found to promote binding
of the alkynylamine substrate to the metal center and the
subsequent cyclization of the alkynylamine.9 Alternatively, an
active catalyst can be generated in situ by the abstraction of a
chloride ligand using a sodium or silver salt. A combination
of NaBArF (BArF = tetrakis[3,5-bis(trifluoromethyl)phenyl]-
borate) and a neutral iridium chloride complex (containing a
P,N,C-donor ligand) has been shown to catalyze the complete
cyclization of o-(2-phenylethynyl)aniline, whereas there was
no reaction observed when the complex was used with no
NaBArF present.16 Here we report alternative approaches for
promoting the formation of charged catalytic species by
abstracting the chloride co-ligand from the neutral complexes
Rh(PyP)(CO)Cl (4) and Ir(PyP)(CO)Cl (5)27 in situ or bꢀy
substitution of the Clꢀ ligand with the more labile OSO2CF3
ligand forming new reactive complexes.
Scheme 2 COE = cyclooctene.
carbon monoxide) in yields of 34% and 39%, respectively
(Scheme 2).
Rhodium triflate complexes were synthesized via the
abstraction of chloride from the complexes 4 or 8 (Scheme 3),
followed by the binding of a triflate anion. Dichloromethane
was chosen as the solvent, as coordinating solvents such as
tetrahydrofuran are known to compete with the triflate group
for binding to the metal center.28 Addition of silver triflate to a
solution of either 4 or 8 in dichloromethane, to remove Clꢀ in
the presence of OSO2CF3ꢀ, and subsequent removal of AgCl
through filtration, yielded the rhodium triflate complexes
Rh(PyP)(CO)(OSO2CF3) (10) and Rh(PyPhP)(CO)(OSO2CF3)
(11) in good yields (77% and 94%, respectively). Attempted
synthesis of the Ir(I) analogues of 10 and 11, Ir(PyP)(CO)-
(OSO2CF3) and Ir(PyPhP)(CO)(OSO2CF3), led to the formation
of mixtures of products, which could not be separated or
purified. The use of thallium triflate in place of silver triflate,
or performing the reactions at lower temperatures, did not
improve the outcome of these reactions.
Results and discussion
Synthesis of metal complexes
The iridium complexes 6, 7 and 9 all exhibit a singlet in the
31P{1H} NMR spectra in the range 11.5–15.6 ppm, which is a
similar range to the chemical shifts reported for the analogous
complexes containing PyP (Table 1).27 On substitution of the
chloride co-ligand of 4 and 8 with the triflate anion the
resonances due to the phosphorus atom in the 31P{1H} NMR
spectrum shifted significantly downfield. The 31P{1H} NMR
spectrum for 427 exhibited a doublet at 38.7 ppm compared to
the doublet observed at 46.8 ppm for the triflate analogue 10.
Likewise, the phosphorus resonances appeared at 41.7 and
A set of Ir(I) and Rh(I) complexes containing the ligand
1-(2-(diphenylphosphino)phenyl)pyrazole (PyPhP)13 were
synthesized following modifications of the methods developed
for the syntheses of the corresponding complexes that contain
the PyP ligand (Schemes 1 and 2).27 In PyPhP a planar
phenyl bridge has been introduced in place of the flexible
ethylene linkage of PyP. By thus expanding the range of
phosphino-pyrazole ligands incorporated into metal catalysts
we can consider the importance of the relative flexibility of the
ligand backbone in catalysis. The cationic Ir(I) complexes
[Ir(PyPhP)(COD)]BPh4 (6) and [Ir(PyPhP)(CO)2]BPh4 (7)
were synthesized from [IrCl(COD)]2 (COD = cyclooctadiene)
and isolated as air stable complexes in moderate yields, 47%
and 65%, respectively, (Scheme 1). The neutral complexes
Rh(PyPhP)(CO)Cl (8) and Ir(PyPhP)(CO)Cl (9) were synthesized
from [RhCl(CO)2]2 or [IrCl(CO)2]n (generated in situ from
stirring a solution of [IrCl(COE)]2 (COE = cyclooctene) under
Scheme 3
ꢁc
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Table 1 31P{1H} NMR spectroscopic data for complexes 6–11
complexes in dichloromethane. ORTEP plots of the structures
of the complexes are shown in Fig. 2 and 3. Selected bond
lengths and bond angles for the inner coordination sphere are
listed in Tables 2 and 3.
Complex
d
31P (ppm)
1JRh–P/Hz
[Ir(PyPhP)(COD)]BPh4 (6)
[Ir(PyPhP)(CO)2]BPh4 (7)
Ir(PyPhP)(CO)Cl (9)
11.5
15.6
12.0
38.7
41.7
46.8
50.1
—
—
—
165.5
161.7
182.7
176.0
The Rh and Ir coordination spheres of Rh(PyPhP)(CO)Cl
(8), Ir(PyPhP)(CO)Cl (9), [Ir(PyPhP)(COD)]BPh4 (6), Rh(PyP)-
(CO)(OSO2CF3) (10) and Rh(PyPhP)(CO)(OSO2CF3) (11) are
essentially all distorted square planar and the six-membered
metallocycle, formed from the chelate P,N-donor ligand,
adopts a pseudo-boat conformation that is similar to the
conformation of the metallocycles found in other Group 9
metal complexes with pyrazolyl-phosphine ligands.19,27
The P(1)–M(1)–N(11) bite angles for complexes containing
PyPhP (85.55(1)1, 83.65(8)1 and 83.94(9)1 and for 6, 8, and 9,
respectively) are each significantly smaller than 901, in
comparison to the complexes containing PyP, 3–5, which have
P(1)–M(1)–N(1) bite angles of 93.93(5)1, 92.21(5)1 and
Rh(PyP)(CO)Cl (4)27
Rh(PyPhP)(CO)Cl (8)
Rh(PyP)(CO)(OSO2CF3) (10)
Rh(PyPhP)(CO)(OSO2CF3) (11)
50.1 ppm in the 31P{1H} NMR spectra of 8 and 11, respec-
1
tively. The JRh–P coupling constants were larger for the
triflate complexes 10 and 11 (182.7 and 176.0 Hz, respectively)
compared to the equivalent coupling constants of their chloride
analogues 4 and 8 (165.5 and 161.7 Hz, respectively) (Table 1),
which suggests that the triflate co-ligand has a lower trans-
influence compared to that of the chloride co-ligand. The IR
spectra of the triflate complexes 10 and 11 exhibit higher
frequencies for the carbonyl bands than the analogous chloride
complexes, 4 and 8 (2015/2003 and 2010/2002 compared
to 1995/195127 and 1991 cmꢀ1, respectively, with the two
frequencies observed for the carbonyl complexes due to splitting
of the carbonyl peak caused by solid-state effects), which
reflects the weaker p-donor ability of triflate compared to
chloride.29
Solid state structures of the Rh(I) and Ir(I) complexes
Crystals suitable for X-ray crystallographic analysis were
obtained for [Ir(PyPhP)(COD)]BPh4 (6), Rh(PyPhP)(CO)Cl
(8), Ir(PyPhP)(CO)Cl (9), Rh(PyP)(CO)(OSO2CF3) (10) and
Rh(PyPhP)(CO)(OSO2CF3) (11) by the slow diffusion of
diethyl ether or n-hexane into concentrated solutions of the
Fig. 3 ORTEP depiction of the cation of 6 with thermal ellipsoids at
the 50% probability level. Hydrogen atoms have been omitted for
clarity.
Fig. 2 ORTEP depictions of 8–11 with thermal ellipsoids at the 50% probability level. Hydrogen atoms have been omitted for clarity.
ꢁc
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Table 2 Bond lengths (A) and angles (1) for the inner coordination
sphere of Ir(PyPhP)(CO)Cl (9), Rh(PyPhP)(CO)Cl (8), Rh(PyP)(CO)-
(OSO2CF3) (10) and Rh(PyPhP)(CO)(OSO2CF3) (11)
Rh(PyPhP)(CO)(OSO2CF3) (11) exhibits the greatest
distortion from the ideal square planar geometry, compared
to 4, 8 or 10, with the N(11)–Rh(1)–O(2), C(1)–Rh(1)–O(2),
N(11)–Rh(1)–C(1), and P(1)–Rh(1)–O(2) bond angles falling
further than 51 from the ideal 901 or 1801, (84.31(10)1,
98.00(13)1, 174.60(14)1 and 172.65(8)1, respectively).
9
8
10
11
Bond lengths/A
M(1)–P(1)
M(1)–N(11)
2.217(1)
2.098(3)
1.821(4)
2.368(1)
2.2064(9) 2.198(1)
2.1785(7)
2.088(3)
1.824(4)
2.109(3)
1.800(4)
2.3887(9)
2.108(3)
1.820(4)
M(1)–C(1)a
Catalysis
M(1)–Cl(1)
Rh(1)–O(2)b
2.174(2)
94.03(7)
84.65(9)
2.147(2)
88.52(7)
84.31(10)
4-Pentyn-1-amine (1) was chosen as the test substrate for the
investigations into the catalyzed cyclization of alkynylamines
for consistency with previously reported hydroamination
results.19,20 In all cases the reactions were performed in
THF-d8 at 60 1C, with 2 mol% catalyst loading.
Bond angles/1
P(1)–M(1)–N(11)
N(11)–M(1)–Cl(1)
N(11)–Rh(1)–O(2)a
Cl(1)–M(1)–C(1)
C(1)a–Rh(1)–O(2)b
83.94(9)
87.29(9)
83.65(8)
90.54(8)
92.49(13) 90.95(11)
94.43(12) 98.00(13)
a
b
C(31) for 11. O(41) for 11.
Catalysis using complexes containing PyPhP
The series of complexes containing PyPhP, [Ir(PyPhP)-
(COD)]BPh4 (6), [Ir(PyPhP)(CO)2]BPh4 (7), Rh(PyPhP)(CO)Cl
(8) and Ir(PyPhP)(CO)Cl (9) (Table 4, entries 1, 2, 3 and 5)
were all tested as catalysts for the hydroamination of 1. The
cationic complex 6 was found to be a highly efficient catalyst
for this reaction, promoting the complete conversion of the
substrate in 6.5 minutes with a turnover rate of 1500 hꢀ1. This
result is comparable to the best previously reported late-
transition metal hydroamination catalysts for the cyclization
of 1.10,12,14,19 The cationic dicarbonyl complex 7 was also an
effective catalyst (NT = 48 hꢀ1) but the neutral complexes 8
and 9 proved to be poor catalysts with neither reaching 70%
conversion after 90 hours. This trend in the catalyst efficiency
of 6–9 for the cyclization of 1 parallels that observed for
analogous Ir(I) and Rh(I) complexes containing pyrazolyl-
phosphine ligands based on the PyP ligand. Previous studies
have suggested that in analogous complexes, the loss of COD
is necessary for formation of the catalytically active species.19
Substitution of PyP with the more rigid PyPhP ligand of Ir(I)
complexes containing the COD co-ligand has significantly
improved the conversion of 1 to 2, with a conversion time of
6.5 minutes using 6 (Table 4), compared to a conversion time
of 90 minutes for [Ir(PyP)(COD)]BPh4 (3).19
Table 3 Bond lengths (A) and angles (1) of the inner coordination
sphere of [Ir(PyPhP)(COD)]BPh4 (6)
Bond lengths/A
Ir(1)–P(1)
Ir(1)–N(11)
Ir(1)–C(51)
2.280(1)
2.083(3)
2.222(4)
Ir(1)–C(52)
Ir(1)–C(55)
Ir(1)–C(56)
2.227(4)
2.124(4)
2.143(4)
Bond angles/1
P(1)–Ir(1)–N(11)
P(1)–Ir(1)–C(55)
P(1)–Ir(1)–C(56)
N(11)–Ir(1)–C(51)
N(11)–Ir(1)–C(52)
85.55(10)
93.97(12)
97.60(13)
90.11(16)
94.42(16)
C(51)–Ir(1)–C(56)
C(52)–Ir(1)–C(55)
C(51)–Ir(1)–C(55)
C(52)–Ir(1)–C(56)
80.87(19)
80.31(17)
96.46(18)
87.82(17)
89.47(6)1, respectively.27 It is clear that the rigid phenyl ring of
PyPhP induces significant ring strain in the metallocycles of
complexes 6, 8 and 9, in comparison to the more flexible
ethylene bridge of PyP. The Rh–O bond lengths for Rh–OSO2CF3
in 10 and 11 are at the lower end of the Rh–O bond distances
that are reported in the literature for rhodium triflate com-
plexes.30–36 The Rh–P bonds trans to the chloride anion in 4
and 8 (2.22(7) and 2.21(9) A, respectively) are similar, within
error, to the Rh–P bonds of 10 and 11 (2.20(1) and 2.18(7) A,
ꢀ
respectively) which are trans to OSO2CF3
.
Table 4 Hydroamination of 4-pentyn-1-amine (1) with Ir(I) and Rh(I) catalysts
Entry
Complexa
Chloride abstractorb
NT/hꢀ1c
Time/hd
1
2
3
4
5
6
7
8
[Ir(PyPhP)(COD)]BPh4 (6)
[Ir(PyPhP)(CO)2]BPh4 (7)
Rh(PyPhP)(CO)Cl (8)
—
—
None
NaBPh4
None
1500
48
—
68
—
25
—
24
13
5.7
5.1
3.0
2.6
62
2.7
36
3.5
0.1
1.9
106 (64%)
4.8
95 (41%)
6
91 (33%)
5.8
9.8
Ir(PyPhP)(CO)Cl (9)
Ir(PyP)(CO)Cl (5)
NaBPh4
None
NaBArF
NaBPh4
NaBF4
TMSOSO2CF3
NaOSO2CF3
AgOSO2CF3
—
None
NaBPh4
—
9
10
11
12
13
1413
15
16
17
15.8 (96%)
41
30.8 (92%)
34 (96%)
41(86%)
96 (88%)
7.5
AgOSO2CF3
Rh(PyP)(CO)Cl (4)
Rh(PyP)(CO)(OSO2CF3) (10)
15 (75%)
a
b
c
Reactions were carried out using 2 mol% of complex in THF-d8 at 60 1C. 2 mol%. NT is calculated as (moles of product at 50% conversion)/
(moles of catalyst)/(time to reach 50% conversion). Time at 98% conversion unless otherwise stated.
d
ꢁc
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Improving the efficiency of the neutral Ir and Rh catalysts by
The trimethylsilyl and silver salts, AgOSO2CF3 and TMSO-
SO2CF3, also have the potential to abstract chloride co-ligands
from metal complexes, and the efficiency of the neutral
Ir(PyP)(CO)Cl (5) as a catalyst in the presence of each of
these chloride abstractors (Table 4, entries 13 and 11) was
established. The addition of one equivalent of either TMSO-
SO2CF3 or AgOSO2CF3 to 5 enhanced the activity of 5,
decreasing the catalyzed reaction time for 496% conversion
to 41 and 34 hours, respectively, compared to 5 alone, which
only reached a conversion of 33% after 91 hours. The more
rapid initial reaction rate did not in all cases provide the best
final reaction outcome. The catalyst generated in situ from 5
in situ chloride abstraction
The abstraction of a chloride co-ligand from neutral Ir(I) and
Rh(I) carbonyl chloride complexes that contain pyrazolyl-
phosphine ligands, allows us to generate coordinatively
unsaturated complexes in situ, with weakly associated counter-
ions. Silver and sodium salts can be used to abstract a chloride
ligand from a metal complex to yield AgCl or NaCl, which can
in some cases be removed easily from the reaction mixture by
filtration. Here we have used AgOSO2CF3 and trimethylsilyl-
triflate (TMSOSO2CF3) in addition to a series of sodium salts
to exchange the chloride ligand of Rh(PyP)(CO)Cl (4),
Ir(PyP)(CO)Cl (5), Rh(PyPhP)(CO)Cl (8) and Ir(PyPhP)(CO)Cl
(9) with a series of less coordinating ligands and form more
active hydroamination catalysts.
and AgOSO2CF3 promoted
a significantly lower initial
conversion rate of 1 to 2 in comparison with the turnover rate
achieved using AgOSO2CF3 alone (NT = 62 hꢀ1) (Table 4,
entries 13 and 1413). However, where the reaction in the
presence of 5 and AgOSO2CF3 reached 96% conversion after
34 hours, the catalyzed reaction using AgOSO2CF3 alone
failed to reach 495% conversion even after 7 days. The
apparent decomposition of the catalytic Ag+ species when
AgOSO2CF3 is used alone has been noted previously, and in
this case the addition of P,N-donor ligands to the reaction
mixture was shown to stabilise the reactive catalytic species.13
It is worth noting that the catalytic system incorporating
NaOSO3CF3 is a potentially more useful catalyst than the
system incorporating AgOSO3CF3, as sodium salts are, in
general, easier to handle and less expensive than silver salts.
Synthesis of the triflate complex Rh(PyP)(CO)(OSO2CF3)
(10) allowed direct comparison between the efficiencies of
isolated catalysts as opposed to those generated in situ. The
efficiency of Rh(PyP)(CO)Cl (4) as a catalyst for the cyclization
of 1 was tested alone, as well as in the presence of chloride
abstractors AgOSO2CF3 and TMSOSO2CF3, and these results
were then compared to the efficiency of the isolated triflate
complex 10 (Fig. 4) as a catalyst for the same cyclization.
Rh(PyP)(CO)(OSO2CF3) (10), is a slightly more efficient
catalyst for the cyclization of 1, with a turnover number of
3.5 hꢀ1, compared to the chloride complex 4 (NT = 2.7 hꢀ1).
Rh(PyP)(CO)(OSO2CF3) (10) is also a more efficient catalyst
than the in situ generated catalysts formed from 4 together
with either AgOSO2CF3 or TMSOSO2CF3, as can be seen
The hydroamination of 4-pentyn-1-amine (1) was catalyzed
using Ir(PyP)(CO)Cl (5) (2 mol%) in the presence of a series
of sodium salts (2 mol%) with counter-ions of varying
coordinating ability (OSO2CF3ꢀ 4 BF4ꢀ 4 BPh4ꢀ 4 BArFꢀ)37
(Table 4, entries 12, 10, 9 and 8, respectively). In all cases an
improvement in the rate of hydroamination was observed in
comparison to catalysis using 5 alone, which reached only
33% conversion of 1 to 2 after 91 hours. Although there are
reported instances of acid catalysed hydroamination,38 any
acid contamination of the reaction mixture due to the sodium
salts would be at too low a concentration to have a notable
effect on the catalytic results presented here. A significant
improvement was observed for the in situ generated catalysts
formed from the addition of either NaBPh4 or NaBArF to 5,
with cyclization of (1) in 9.8 and 5.8 hours, respectively. The
efficiency of the catalysts generated from (5) and a sodium salt
was inversely proportional to the coordinating strength of the
counter-ion of the sodium salt, with catalytic efficiency in
the order of NaBArF 4 NaBPh4 4 NaBF4 4 NaOSO2CF3
(24, 13, 5.7, 3.0 hꢀ1, respectively). The counter-ions BPh4ꢀ and
BArFꢀ are the more weakly coordinating and allow the
formation of a coordinatively unsaturated active catalyst,
which enhances substrate binding.
The hydroamination of 4-pentyn-1-amine (1) was also
carried out in the presence of 2 mol% NaBPh4 and Rh(PyP)-
(CO)Cl (4), Rh(PyPhP)(CO)Cl (8) and Ir(PyPhP)(CO)Cl (9)
(Table 4 entries 16, 4 and 6). In all cases, the efficiency of
catalysis was significantly improved by exchange of chloride
for BPh4ꢀ. The catalysts generated in situ from the Rh
complexes 4 and 8 (NT = 36 hꢀ1 and NT = 68 hꢀ1
respectively) were more active than their Ir counterparts 5
and 9 with NaBPh4 (NT = 13 hꢀ1 and NT = 25 hꢀ1
,
,
respectively). The complexes 8 and 9 containing the ligand
PyPhP were more active catalysts in the presence of NaBPh4
than complexes 4 and 5, which contain the PyP ligand, further
confirming the potential of PyPhP for use in catalysis
compared to PyP. The two ligands differ both in backbone
flexibility and donor basicity. The PyPhP ligand has a
sterically more rigid structure. The IR stretches of the CO
substituents of the pairs of complexes with these two ligands
are also different, suggesting that the difference in catalytic
efficiency may result from both electronic and structural
effects.
Fig. 4 Reaction profile for the cyclization of 4-pentyn-1-amine (1)
catalyzed by 2 mol% of Rh(PyP)(CO)Cl (4) with 2 mol% NaBPh4 (m),
2 mol% of Rh(PyP)(CO)(OSO2CF3) (10) (&), 2 mol% of 4 (K),
2 mol% of 4 with 2 mol% AgOSO2CF3 (n), 2 mol% of 4 with 2 mol%
of TMSOSO2CF3 (’).
ꢁc
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1204 | New J. Chem., 2010, 34, 1200–1208

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from the reaction profiles in Fig. 4. These results indicate that
the higher lability of the triflate co-ligand of 10, compared to
that of the chloride co-ligand of 4, has the potential to enhance
the catalytic activity of Rh(I) complexes. The poor catalytic
activity of the catalyst generated in situ from 4 and AgOSO2CF3,
compared to the Ir(I) reaction, may be due to formation
90 minutes for [Ir(PyP)(COD)]BPh4 (3). This was attributed
to changes in the basicity of the ligand, and the ligand
flexibility.
The efficiency of the catalyzed hydroamination of 4-pentyn-
1-amine (1) by the neutral complexes Ir(PyP)(CO)Cl (5), 4, 8
and 9 was significantly improved by generating active catalysts
in situ through abstraction of a chloride ligand by reaction
with NaBPh4. In the case of complex 5, chloride abstraction by
addition of AgOSO2CF3 or TMSOSO2CF3 also generated an
effective in situ catalyst with a loosely bound triflate anion in
the place of Clꢀ. The catalytic efficiency of the catalysts
generated from 5 and a sodium salt was inversely proportional
to the coordinating strength of the counter-ion of the sodium
salt, with catalytic efficiency in the order of NaBArF 4
NaBPh4 4 NaBF4 4 NaOSO2CF3. The catalytic system
incorporating silver triflate was less efficient than those
incorporating TMSOSO3CF3 or NaOSO3CF3.
of inactive complexes containing
a Rh–Cl–Ag motif.
Complexes such as these have been observed previously upon
reaction of Ag salts with Rh(I) complexes containing Clꢀ
ligands.39
Conclusions
A series of complexes containing the phosphino-pyrazolyl
ligand 1-(2-(diphenylphosphino)phenyl)pyrazole (PyPhP) were
synthesized, [Ir(PyPhP)(COD)]BPh4 (6), [Ir(PyPhP)(CO)2]-
BPh4 (7), Rh(PyPhP)(CO)Cl (8) and Ir(PyPhP)(CO)Cl (9), in
addition to two complexes Rh(PyP)(CO)(OSO2CF3) (10) and
Rh(PyPhP)(CO)(OSO2CF3) (11) which were synthesized from
the parent complexes Rh(PyP)(CO)Cl (4) and 8 via chloride
abstraction with silver triflate. The solid-state structures of 6,
8–11 were determined using X-ray diffraction analysis
(Table 5).
The isolated complex formed from the reaction of 4 and
AgOSO2CF3, Rh(PyP)(CO)OSO2CF3 (10), is a more efficient
catalyst for the cyclization of 1 than the chloride complex 4
indicating that the higher lability of the triflate co-ligand of 10,
compared to the chloride co-ligand of 4 in fact enhances the
catalytic activity of the Rh(I) complexes. The poor catalytic
activity of the in situ generated, and isolated Rh(I) complexes
containing a triflate anion compared to the catalyst formed
from NaBPh4 and 4 is most likely due to the fact that the
triflate is a more strongly binding anion than the BPh4ꢀ anion.
The cationic Ir(I) complex 6 was found to be the best
catalyst for the intramolecular hydroamination cyclization of
4-pentyn-1-amine (1), promoting a turnover rate of 1500 hꢀ1
,
which is comparable to the best previously reported late-
transition metal hydroamination catalysts for the cyclization
of 1. 10,27 Substitution of PyP with the PhPyP ligand in the Ir(I)
complexes with the COD co-ligand significantly improved the
catalyzed cyclization of 4-pentyn-1-amine 1, with a conversion
time of 6 minutes for [Ir(PhPyP)(COD)]BPh4 6, compared to
Experimental section
The manipulations of metal complexes and air sensitive
reagents were carried out using standard Schlenk techniques
Table 5 Crystallographic data for 6, 8–11
6a
8b
9
10
11
Empirical formula C53H49BIrN2P
C22H17ClN2OPRh C22H17ClIrN2OP
584.00
C19H17F3N2O4PRhS C23H17F3N2O4PRhSꢂ0.5(CH2Cl2)
650.80
M/g molꢀ1
Crystal system
Space group
a/A
947.92
Triclinic
ꢀ
P1
494.71
560.29
Orthorhombic
P212121
9.6570(19)
10.144(2)
21.513(4)
90
Monoclinic
P21/n
Monoclinic
P21/c
Monoclinic
P21/c
10.780(2)
14.674(3)
14.848(3)
73.30(3)a
2176.0(8)
1.447
8.7900(18)
22.900(5)
10.496(2)
100.13(3)
2079.8(7)
1.865
12.002(2)
11.376(2)
15.535(3)
94.51(3)
2114.5(7)
1.760
10.5808(1)
20.0102(3)
12.2975(2)
100.3725(10)
2561.13(6)
1.688
b/A
c/A
b/1
V/A3
2107.4(7)
1.559
Dc/g cmꢀ3
Z
T/K
2
290(2)
4
290(2)
4
200(2)
4
200(2)
4
200
l (Mo-Ka)/A
m(Mo-Ka)/mmꢀ1
Crystal size/mm
2ymax
0.71073
3.143
0.71073
1.027
0.71073
6.640
0.71073
1.038
0.71073
0.97
0.31 ꢃ 0.17 ꢃ 0.11 0.50 ꢃ 0.24 ꢃ 0.16 0.68 ꢃ 0.15 ꢃ 0.13 0.24 ꢃ 0.19 ꢃ 0.14
0.27 ꢃ 0.06 ꢃ 0.04
54.96
54.94
55.22
55.06
55.00
Index ranges
ꢀ13 Z h Z 13
ꢀ19 Z k Z 17
ꢀ19 Z l Z 19
36 500
9936
0.0705
1.026
0.0368
0.0757
0.0611
0.0862
ꢀ12 Z h Z 12
ꢀ13 Z k Z 13
ꢀ27 Z l Z 27
30 380
4822
0.0554
0.987
0.0288
0.0588
0.0458
0.0660
ꢀ11 Z h Z 11
ꢀ29 Z k Z 29
ꢀ13 Z l Z 13
39 741
4799(0.1068)
0.1068
0.993
0.0256
0.0600
0.0359
0.0651
ꢀ15 Z h Z 15
ꢀ14 Z k Z 13
ꢀ20 Z l Z 20
46 655
4871
0.0810
1.005
0.0371
0.0862
0.0600
0.0985
ꢀ13 Z h Z 13
ꢀ25 Z k Z 25
ꢀ15 Z l Z 15
52 493
5855
0.086
0.977
0.028
0.0665
0.0495
0.0887
N
Nind (Rmerge
Rint
)
GoF (all data)
R1 (I 4 2s(I))
wR2 (I 4 2s(I))
R1 (all data)
wR2 (all data)
a
b
a (1) = 81.77(3), g (1) = 76.00(3). Flack parameter = ꢀ0.04(2).
ꢁc
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or in a nitrogen-filled dry box. For use in the synthesis of air
sensitive materials, solvents were dried and degassed prior
to use. Tetrahydrofuran (THF), diethyl ether, n-hexane,
n-pentane and benzene were pre-dried over sodium wire then
distilled from benzophenone over sodium shavings under
nitrogen. Dichloromethane and acetonitrile were distilled
from calcium hydride and methanol was dried over and
distilled from magnesium turnings. Most chemicals were
purchased from Aldrich Chemical Inc., with a few exceptions;
THF-d8, benzene-d6, and CD2Cl2, were purchased from Cam-
bridge Isotopes, AgOSO3CF3 was purchased from Lancaster,
IrCl3ꢂxH2O and RhCl3ꢂxH2O were obtained from Precious
Metals Online PMO P/L and were used without further
purification. All bulk compressed gases were obtained from
British Oxygen Company (BOC gases) and Linde Gas
Pty. Ltd.
dH(500 MHz; CD2Cl2; Me4Si) 7.71 (1H, d, 3JH3–H4 1.9, H3),
3
7.66 (1H, m, H50), 7.57 (1H, d, JH5–H4 2.5, H5), 7.55–7.51
(4H, m, p-CH of PPh2, H30 and H40), 7.44 (4H, m, m-CH of
PPh2), 7.35–7.28 (13H, m, o-CH of PPh2, o-CH of BPh4 and
H60), 6.99 (8H, dd apparent t, 3J 7.3, m-CH of BPh4), 6.84
(4H, dd apparent t, 3J 7.3, p-CH of BPh4), 6.39 (1H, dd
apparent t, 3J 2.7, H4), 5.14 (2H, br s, CHCH2 of COD), 3.40
(2H, br s, CHCH2 of COD), 2.33 (4H, d, CHCH2 of COD),
2.10 (4H, d, CHCH2 of COD) ppm.
d
d
P{H}(121 MHz; CD2Cl2) 11.5 ppm.
C{H}(75 MHz; CD2Cl2; Me4Si) 164.3 (q, JC–B 49.4, i-C of
1
1
2
BPh4), 144.9 (C3), 141.7 (d, JC1 –P 9.4, C10), 136.2 (q, JC–B
0
2
1.5, o-C of BPh4), 135.4 (C5), 135.4 (d, JC–P 11.6, o-C of
4
4
PPh2), 133.2 (d, JC5 –P 2.2, C50), 132.7 (d, JC–P 2.9, p-C of
PPh2), 132.4 (d, JC3 –P 2.9, C30), 130.1 (d, JC4 –P 6.5, C40),
129.5 (d, 3JC–P 10.9, m-C of PPh2), 125.9 (q, 3JC–B 2.9, m-C of
BPh4), 125.70 (d, JC6 –P 6.5, C60), 124.4 (d, JC–P 55.9, i-C of
PPh2), 122.0 (p-C of BPh4), 121.2 (d, JC2 –P 48.0, C20), 111.1
2
(C4), 96.0 (d, JC–P 14.5, CHCH2 of COD), 63.5 (CHCH2 of
0
2
3
0
0
37
3
1
[Ir(COD)(m-Cl)]2,40 [Rh(CO)2(m-Cl)]2,41 [Ir(COE)2(m-Cl)]2
0
and NaBArF42 were prepared according to literature methods.
We have previously reported the synthesis of ligand
PyPhP13 and the metal complexes Ir(PyP)(CO)Cl (5)27 and
Rh(PyP)(CO)Cl (4).27 4-Pentyn-1-amine (1) was synthesized
by the Organic Synthesis Center, School of Chemistry,
University of Sydney and dried over calcium hydride prior
to use. 1H, 13C{1H} and 31P{1H} NMR spectra were recorded
on a Bruker DPX300 or DMX500 spectrometer. All spectra
were obtained at 298 K unless otherwise reported and 1H and
13C spectra are referenced to internal solvent references.
31P NMR chemical shifts were externally referenced to
H3PO4 (85% in D2O) at 0 ppm. Infra-red spectroscopy was
performed using an ATI Mattson Genesis Series F.T.I.R.
spectrometer. Melting points were determined using a Reichert
melting point apparatus and are uncorrected. ESI-MS was
performed by Dr Russell Pickford at the Bioanalytical Mass
Spectroscopy Facility, University of New South Wales.
Microanalyses were carried out at the Campbell Analytical
Laboratory, University of Otago. The X-ray crystal structures
were determined by Dr Matthew Smith and Dr Anthony
Willis at the Research School of Chemistry, Australian
National University. X-Ray diffraction data were measured
on a Nonius KappaCCD diffractometer using Mo-Ka radiation.
Intensity data were collected with phi and omega scans and
corrected for absorption analytically. The structures were
solved with the use of SIR92 and refined using the
SHELXL-97 or CRYSTALS software packages.
1
0
COD), 33.0 (CHCH2 of COD), 29.5 (CHCH2 of COD) ppm.
ESI-MS (MeOH): m/z 630 ([M + H]+, 100%), 629
([M]+, 77).
Synthesis of [Ir(PyPhP)(CO)2][BPh4] (7)
An orange suspension of [Ir(PyPhP)(COD)][BPh4] (6) (176 mg,
0.185 mmol) in n-pentane (15 mL) and methanol (3 mL) was
degassed via three cycles of freeze/pump/thaw. Carbon
monoxide was introduced via a balloon and the suspension
turned yellow after 10 min. The mixture was stirred for a
further 1 h, and the atmosphere was replaced with nitrogen.
The yellow solid was collected by filtration, washed with
n-pentane (2 ꢃ 3 mL) and dried in vacuo to yield 7 (108 mg,
65%), mp 150–155 1C (decomp.).
Found C, 62.7; H, 4.25; N, 3.18%. C47H37BIrN2O2P
requires C, 63.0; H, 4.15; N, 3.15%.
dH(500 MHz; THF-d8; Me4Si) 8.11 (1H, d, 3JH3–H4 2.7, H3),
7.66 (1H, d, 3JH5–H4 2.4, H5), 7.65–7.60 (3H, m, p-CH of PPh2
and H50), 7.54–7.44 (9H, m, o-CH and m-CH of PPh2 and
3
H40), 7.27 (8H, m, o-CH of BPh4), 7.22 (1H, dd, JH6 –H5 8.2,
0
0
3
3
4
JH6 –P 4.8, H60), 7.08 (1H, ddd, JH3 –H4 7.7, JH3 –H5 1.3,
0
0
0
0
0
2
3
JH3 –P 11.9, H30), 6.80 (8H, dd apparent t, J = 7.4 Hz, m-CH
of BPh4), 6.67 (4H, t, 3J 7.0, p-CH of BPh4), 6.38 (1H, dd
0
3
apparent t, J 2.4, H4) ppm.
d
d
P{H}(121 MHz; CD2Cl2) 15.56 ppm.
1
C{H}(75 MHz; THF-d8; Me4Si) 165.2 (q, JC–B 49.4, i-C of
BPh4), 150.9 (C3), 141.2 (d, 1JC1 –P 8.0, C10), 137.7 (C5), 137.2
0
Synthesis of [Ir(PyPhP)(COD)]BPh4 (6)
2
2
(q, JC–B 1.5, o-BPh4), 135.3 (C50), 135.1 (d, JC–P 12.4,
o-PPh2), 134.7 (C40), 134.4 (d, JC–P 2.9, p-C of PPh2), 133.8
(d, 2JC3 –P 4.4, C30), 131.4 (d, JC2 –P 8.0, C20), 130.8 (d, JC–P
12.4 Hz, m-PPh2), 126.9 (d, JC6 –P 6.5 Hz, C60), 125.8
3
(q, JC–B 2.9, m-C of BPh4), 121.9 (p-C of BPh4), 112.38
A solution of PyPhP (209 mg, 0.621 mmol) in methanol
(10 mL) was added dropwise over 15 min to a red suspension
of [Ir(m-Cl)(COD)]2 (209 mg, 0.311 mmol) in methanol
(10 mL). The red solid dissolved to form an orange solution
which was stirred for 1 hour. NaBPh4 (213 mg, 0.622 mmol)
was added as a solid, resulting in the formation of an orange
precipitate. This mixture was stirred for 3 hours. The volatiles
were reduced to approximately 10 mL in vacuo, and diethyl
ether (5 mL) was added. The orange solid was collected by
filtration, washed with methanol (2 ꢃ 1 mL) and diethyl ether
(2 ꢃ 2 mL) and dried in vacuo to yield (6) (275 mg, 47%), mp
219–222 1C (decomp.).
4
2
3
0
0
3
0
(C4) ppm.
ES-ESI-MS (MeOH): m/z 549 ([M ꢀ CO]+, 40%).
n
max/cmꢀ1 2088 (CO), 2023 (CO).
Synthesis of Rh(PyPhP)(CO)Cl (8)
A solution of PyPhP (291 mg, 0.886 mmol) in methanol
(20 mL) was added dropwise to a red suspension of
ꢁc
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[Rh(m-Cl)(CO)2]2 (174 mg, 0.448 mmol) in methanol (10 mL).
The red solid dissolved to form a yellow solution and then a
yellow precipitate. After stirring for 30 min, 80% of the
solvent was removed in vacuo and diethyl ether (10 mL) was
added. The product was collected by filtration, washed with
methanol (2 ꢃ 1 mL) and diethyl ether (2 ꢃ 2 mL) to yield
complex 8 (172 mg, 39%), mp 285–290 1C (decomp.).
(30 mL). The solution was stirred for 3 h, during which time it
became cloudy. The reaction mixture was filtered through
Celitet and the filtrate concentrated in vacuo. n-Hexane was
added to give the product as a dark yellow precipitate which
was collected by filtration, washed with n-hexane (3 ꢃ 3 mL)
and dried in vacuo to yield 10 (206 mg, 77%).
Found C, 40.68; H, 3.18; N, 5.05%. C19H17F3N2O4PRhS
requires C, 40.73; H, 3.06; N, 5.00%.
dH(500 MHz; CD2Cl2; Me4Si) 8.31 (1H, d, 3JH3–H4 1.8, H3),
7.77 (1H, d, 3JH5–H4 2.2, H5), 7.61 (1H, dd apparent t, 3J 7.7,
H50), 7.55–7.46 (6H, m, o-CH and p-CH of PPh2), 7.42–7.38
(6H, m, m-CH of PPh2, H40 and H60), 6.96 (1H, dd apparent t,
dH(300 MHz; CDCl3; Me4Si) 8.02 (1H, s, H3), 7.84–7.77
(4H, m, o-CH of PPh2), 7.54–7.46 (7H, m, m-CH, p-CH of
3
PPh2 and H5), 6.30 (1H, apparent t, JH3–H4,H5–H4 2.3, H4),
3
3J 8.8, H30), 6.40 (1H, dd apparent t, J 2.4, H4) ppm.
4.51–4.40 (2H, m, NCH2), 2.65 (2H, m, PCH2) ppm.
1
P{H}(121 MHz, CD2Cl2) 46.8 (d, JRh–P 182.7) ppm.
1
P{H}(121 MHz; CDCl3) 41.7 (d, JRh–P 161.7 Hz) ppm.
d
d
d
1
2
C{H}(75 MHz; CDCl3; Me4Si) 189.6 (dd, JC–Rh 74.8, JC–P
d
C{H}(125 MHz, CD2Cl2) 186.2 (dd, 1JRh–C 72.7, 2JP–C 22.0,
2
16.0, CO), 146.7 (C3), 141.4 (d, 2JC1 –P 8.7, C10), 134.1 (d, JC–P
CO), 143.4 (s, C3), 133.7 (s, C5), 132.9 (dd, 2JP–C 11.6, 3JRh–C
0
2
2
13.1, o-C of PPh2), 132.3 (C5), 132.0 (d, JC3 –P 2.2, C30), 131.9
1.5, o-C of PPh2), 132.3 (br d, JRh–C 1.5, i-C of PPh2), 131.5
0
4
4
(d, JC5 –P 2.2, C50), 131.6 (d, JC–P 2.2 Hz, p-C of PPh2), 129.6
(d, 4JP–C 2.2, p-C of PPh2), 128.9 (d, 3JP–C 10.9, m-C of PPh2),
106.2 (s, C4), 47.5 (s, NCH2), 28.0 (d, 1JP–C 32.0, PCH2) ppm.
dF(282 MHz, CD2Cl2) ꢀ78.6 ppm.
0
1
3
(d, JC–P 55.2 Hz, C20 or i-C of PPh2), 128.9 (d, JC–P 11.6 Hz,
3
1
m-C of PPh2), 128.7 (d, JC–P 7.3, C40 or C60), 124.6 (d, JC2 –P
41.4, C20), 124.1 (d, 3JC–P 5.8, C40 or C60), 109.5 (C4) ppm.
ESI-MS (MeOH): m/z 459.0 ([M ꢀ Cl]+, 100%), 952
([[Rh(PyPhP)(CO)]2Cl]+, 78).
0
ESI-MS (DCM): m/z 383.7 ([Rh(PyP)]+, 60%), 411.8
([M ꢀ OSO2CF3]+, 55).
n
max/cmꢀ1 2015 (CO), 2003 (CO) cmꢀ1
.
n
max/cmꢀ1 1991 (CO).
Synthesis of Rh(PyPhP)(CO)(OSO2CF3) (11)
Synthesis of Ir(PyPhP)(CO)Cl (9)
AgOSO2CF3 (128 mg, 0.496 mmol) was added to a solution of
Rh(PyPhP)(CO)Cl (8) (202 mg, 0.406 mmol) in dichloro-
methane (25 mL). The solution was stirred for 3 h, during
which time it became cloudy. The reaction mixture was filtered
through Celitet and the filtrate concentrated in vacuo.
n-Hexane was added to give the product as a dark yellow
precipitate which was collected by filtration, washed with
n-hexane (3 ꢃ 3 mL) and dried in vacuo to yield 11 (223 mg,
94%).
An orange suspension of [Ir(m-Cl)(COE)2]2 (160 mg,
0.179 mmol) in acetonitrile (40 mL) was degassed via three cycles
of freeze/pump/thaw and carbon monoxide was introduced via a
balloon. The suspension was stirred under a carbon monoxide
atmosphere for 15 min, during which time the orange solid
dissolved to form a yellow solution. A solution of PyPhP
(117 mg, 0.356 mmol) in acetonitrile (9 mL) was added dropwise
to the reaction mixture. After stirring for 1 h, 75% of the solvent
was removed in vacuo and a yellow solid precipitated. The solid
was collected by filtration, washed with methanol (3 ꢃ 1 mL) and
diethyl ether (3 ꢃ 3 mL) and dried in vacuo to yield 9 (71 mg,
34%), mp 278–282 1C (decomp.).
dH(500 MHz; CD2Cl2; Me4Si) 7.97 (1H, s, H3), 7.86 (1H, s,
H5), 7.67 (1H, dd apparent t, 3J 7.6, H30), 7.54–7.43 (12H, m,
PPh2, H40 and H60), 7.00 (1H, dd apparent t, 3J 9.3, H50), 6.47
(1H, s, H4) ppm.
1
P{H}(121 MHz, CD2Cl2) 50.1 (d, JRh–P 176.0) ppm.
Found: C, 45.25; H, 2.95; N, 4.92%. C22H18ClIrN2OP
d
requires C, 45.25; H, 2.95; N, 4.8%.
dF(282 MHz, CD2Cl2) ꢀ78.5 ppm.
dH(500 MHz; CD2Cl2; Me4Si) 8.40 (1H, d, 3JH3–H4 1.8, H3),
7.84 (1H, d, 3JH5–H4 2.7, H5), 7.60 (1H, dd apparent t, 3J 7.7,
H50), 7.53 (4H, dd, 3Jo-H–P 12.3, 3Jo-H–m-H = 7.5 Hz, o-CH of
PPh2), 7.46 (2H, m, p-CH of PPh2), 7.42–7.38 (6H, m, m-CH
ESI-MS (DCM): m/z 459.02 ([M ꢀ OSO2CF3]+, 100%).
n
max/cmꢀ1 2010 (CO), 2002 (CO).
General procedures for catalytic reactions
3
of PPh2, H40 and H60), 6.99 (1H, dd apparent t, J 8.7, H30),
3
6.45 (1H, dd apparent t, J 2.8, H4) ppm.
All metal catalyzed hydroamination reactions were performed
on a small scale in an NMR tube fitted with a Young’s
concentric Teflon valve. All samples were prepared and reactions
carried out under a nitrogen atmosphere using freshly distilled,
dry degassed THF-d8. Either 4-pentyn-1-amine (1) was
injected into a solution of the catalyst, or a solution of 1 in
THF-d8 was reacted with the solid catalyst. The reactions were
performed at 60 1C by heating in an oil bath or within
the spectrometer. The temperature within the magnet was
calibrated using ethylene glycol.38,43
d
d
P{H}(121 MHz; CDCl3) 12.0 ppm.
3
C{H}(125 MHz; CD2Cl2; Me4Si) 176.3 (d, JC–P 13.0, CO),
2
146.4 (C3), 141.3 (C10), 134.3 (d, JC–P 12.0, o-C of PPh2),
133.5 (C5), 131.9 (d, 4JC–P 2.0, C50), 131.8 (m, C30 and p-C of
2
PPh2), 129.2 (C40 or C60), 129.1 (d, JC–P 7.0, C20), 128.8 (d,
3JC–P 12.0, m-C of PPh2), 124.5 (d, 3JC–P 6.0, C40 or C60), 109.4
(C4) ppm.
ESI-MS (MeOH): m/z 549 ([M ꢀ Cl]+, 100%).
n
max/cmꢀ1 1978 (CO).
The progress of the hydroamination reaction was monitored
by acquiring 1H NMR spectra at regular intervals. In the
preparation of each sample, when all reactants had been added
to the NMR tube, it was frozen in liquid nitrogen. The first
spectrum was measured as soon as the sample had been
Synthesis of Rh(PyP)(CO)(OSO2CF3) (10)
AgOSO2CF3 (124 mg, 0.482 mmol) was added to a solution of
Rh(PyP)(CO)Cl (4) (214 mg, 0.479 mmol) in dichloromethane
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010 New J. Chem., 2010, 34, 1200–1208 | 1207

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thawed to room temperature and inserted into the spectro-
meter. The moment of this first acquisition was taken to be
time zero. Conversion of starting material to product was
determined by integration of the product resonances relative
to the substrate resonances. The turnover rate (NT (hꢀ1)) was
calculated as the number of moles of product/moles of catalyst/
hour and was determined at the point of 50% conversion.
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Acknowledgements
Financial support from the Australian Research Council and
The University of New South Wales is gratefully acknowl-
edged. S.L.D. wishes to thank the Australian government for
an Australian Postgraduate Award scholarship.
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1208 | New J. Chem., 2010, 34, 1200–1208