Syntheses, structures, and reactions of cyrhetrenylphosphines; Applications in palladium catalyzed Suzuki cross-coupling reactions

Article abstract of DOI:10.1016/j.jorganchem.2013.10.029

Reaction of bromocyrhetrene (η⁵-C₅H ₄Br)Re(CO)₃ with lithium tetramethylpiperidide (LiTMP; 1.0 equiv, -78 C) and then ClPR₂ (R = a, Ph; b, Cy) gives (η⁵-1,2-C₅H₃BrPR₂)Re(CO) ₃ (5a, 48%; 5b, 80%). Analogous reactions with 2.0 equiv of LiTMP and ClPR₂ give the 1-bromo-2,5-diphosphidocyclopentadienyl complexes [η⁵-1,2,5-C₅H₂Br(PR₂) ₂]Re(CO)₃ (6a, 60%; 6b, 80%). These rhenium containing or cyrhetrenylphosphines are combined with Pd(OAc)₂ (2:1 mol ratio) to give catalysts for Suzuki couplings of phenylboronic acid and p-bromotoluene or p-bromoacetophenone (1 mol%; Cs₂CO₃, toluene, 100 C). The catalyst with 5b exhibits much higher activities than the others, with conversions of 92-64% after 20 min. The crystal structures of 5b and 6a,b are determined.

Full text of DOI:10.1016/j.jorganchem.2013.10.029

Journal of Organometallic Chemistry 749 (2014) 416e420
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Syntheses, structures, and reactions of cyrhetrenylphosphines;
applications in palladium catalyzed Suzuki cross-coupling reactions
,
,
Diego Sierra a b, Nattamai Bhuvanesh b, Joseph H. Reibenspies b, John A. Gladysz b
**
*
,
A. Hugo Klahn a
,
a Instituto de Química, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso, Chile
b Department of Chemistry, Texas A&M University, PO Box 30012, College Station, TX 77842-3012, USA
a r t i c l e i n f o
a b s t r a c t
(h
5-C5H4Br)Re(CO)3 with lithium tetramethylpiperidide (LiTMP;
Article history:
Reaction of bromocyrhetrene
1.0 equiv, ꢀ78 ꢁC) and then ClPR2 (R ¼ a, Ph; b, Cy) gives (
h
5-1,2-C5H3BrPR2)Re(CO)3 (5a, 48%; 5b, 80%).
Received 17 September 2013
Received in revised form
14 October 2013
Analogous reactions with 2.0 equiv of LiTMP and ClPR2 give the 1-bromo-2,5-
diphosphidocyclopentadienyl complexes [h
5-1,2,5-C5H2Br(PR2)2]Re(CO)3 (6a, 60%; 6b, 80%). These
Accepted 15 October 2013
rhenium containing or cyrhetrenylphosphines are combined with Pd(OAc)2 (2:1 mol ratio) to give
catalysts for Suzuki couplings of phenylboronic acid and p-bromotoluene or p-bromoacetophenone
(1 mol%; Cs2CO3, toluene, 100 ꢁC). The catalyst with 5b exhibits much higher activities than the others,
with conversions of 92e64% after 20 min. The crystal structures of 5b and 6a,b are determined.
Ó 2013 Elsevier B.V. All rights reserved.
Keywords:
Rhenium
Lithiation
Phosphines
Palladium
Suzuki coupling
Crystal structures
1. Introduction
In a relevant example involving ferrocenyl phosphines, the
addition of an ortho aryl substituent to (h h
5-C5H4PCy2)Fe( 5-C5H5),
The development of new phosphine ligands has had a huge
impact in transition metal catalyzed organic reactions [1e3] and
continues to attract great interest [4e7]. One growing subclass
would be organometallic or “transition metal containing” phos-
phines, in which the metal is a spectator that does not participate in
any of the bond breaking or bond making steps [8e10]. These are
being evaluated as ligands in increasing numbers of metal cata-
lyzed reactions.
as exemplified by I in Fig. 1 (Ar ¼ Ph, o-MeOC6H4, 1-naphthyl, 9-
phenanthrenyl), enhances the rates of palladium catalyzed Suzuki
cross-coupling reactions [13]. Similarly, the air stable 2-
trimethylsilyl ferrocenyl phosphine, (h -
5-C5H3SiMe3(PPh2))Fe(h5
C5Me5) (II), is a superb ligand for the Suzuki reaction [14]. It has
been proposed that an increase in steric bulk enhances the rate of
the product forming reductive elimination step in the catalytic
cycle [15].
The success of phosphine ligands in catalysis is a function of
both steric and electronic properties, and it is desirable to be able to
vary both independently. This allows fine tuning of the coordinated
species, thus enabling the various steps of the catalytic cycle to be
optimized [11]. One recurring theme in metal catalyzed carbone
carbon bond forming reactions has been the use of bulky phosphine
ligands, often with electron releasing substituents [12].
We have previously demonstrated that the rhenium containing
or cyrhetrenylphosphine (
the related chiral-at-rhenium
h
5-C5H4PPh2)Re(CO)3 (III) [10] as well as
phosphine
(h
5-C5H4PPh2)
Re(NO)(CH3)(PPh3) (IV) [9e] are effective ligands for palladium
catalyzed Suzuki cross coupling reactions. These provide coordi-
nation environments that are complementary to substituted fer-
rocenes. We wondered whether adding appropriate substituents to
the former at the ortho cyclopentadienyl positions could have a
beneficial effect. Accordingly, in this paper we describe syntheses,
crystal structures, and palladium catalyzed Suzuki reactions
involving cyrhetrenylphosphines that contain 1-bromo-2-
phosphidocyclopentadienyl and 1-bromo-2,5-diphosphidocyclo
pentadienyl units.
* Corresponding author. Tel.: þ1 979 845 1399.
** Corresponding author. Tel.: þ56 32 2274922.
E-mail addresses: gladysz@mail.chem.tamu.edu (J.A. Gladysz), hklahn@ucv.cl (A.
H. Klahn).
URL: http://www.chem.tamu.edu/rgroup/gladysz/index.html, http://www.
institutodequimica.ucv.cl/es/?page_id¼503
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.10.029

D. Sierra et al. / Journal of Organometallic Chemistry 749 (2014) 416e420
417
The new complexes 5a,b and 6a,b were obtained as air stable
white powders, and characterized by IR and NMR (1H, 13C, 31P)
spectroscopy, in most cases by mass spectrometry, and with 5b by
microanalysis, as summarized in the experimental section. NMR
spectra are reproduced in Supporting information. Product identi-
ties were evidenced by the strong IR nCO bands (2029e2025 and
1940e1933 cmꢀ1), 1H and 13C NMR signal patterns characteristic of
substituted cyclopentadienyl ligands (see Supporting information),
and intense molecular ions in the mass spectra. Also, the planar
chirality associated with the substituted cyclopentadienyl ligands
rendered the PR2 groups diastereotopic, resulting in two sets of 13
NMR signals.
C
2.2. Crystallography
Single crystals of 5b and 6a,b could be grown, and the X-ray
crystal structures were determined as summarized in Table 1 and
the experimental section. These confirmed the structural assign-
ments, and key bond lengths and angles are provided in supporting
information (Table 1s). Thermal ellipsoid plots of the molecular
structures are depicted in Fig. 2. In order to facilitate comparisons
between structures, the atom numbering schemes of some have
been altered from those in the CIF files (Supporting information).
Most of the metrical parameters (see Table 1s) are quite similar
and routine, conforming to those of many other formally octahedral,
three-legged piano stool cyclopentadienyl rhenium complexes. For
example, the OCeReeCO bond angles fall into the narrow range of
91.81(11)ꢁ to 87.5(2)ꢁ. Complex 6a adopts a conformation in which
two phenyl groups on opposite diphenylphosphido moieties are
nearly eclipsed (Fig. 2, middle), as evidenced by a C9eP1eP2eC21
torsion angle of 18.75ꢁ. Curiously, this motif has also been observed
in ferrocene V (Fig. 1), which features an identical cyclopentadienyl
ligand (analogous torsion angle 8.06ꢁ) [21].
Fig. 1. Relevant literature compounds.
2. Results and discussion
2.1. Syntheses of rhenium complexes
The new rhenium-containing or cyrhetrenylphosphines evalu-
ated in this study were synthesized by the four step pathway
depicted in Scheme 1, starting with the readily available cyclo-
pentadienyl tricarbonyl complex
(h
5-C5H5)Re(CO)3 (1) [16].
Following a previously reported protocol [17], the cyclopentadienyl
ligand was lithiated with n-BuLi, and subsequent addition of mer-
curic chloride afforded the chloromercuriocyclopentadienyl com-
plex (h
5-C5H4HgCl)Re(CO)3 (2). The reaction of 2 and Na2S2O3
The sums of the bond angles about the phosphorus atoms reflect
the degree of pyramidalization. Interestingly, all are significantly less
than that of an idealized tetrahedral atom, 328.4ꢁ (5b, 306.1ꢁ; 6a,
302.3ꢁ and 304.2ꢁ; 6b, 304.5ꢁ and 308.5ꢁ). To our knowledge,
no other cyrhetrenylphosphines have been crystallographically
characterized. However, for the di(t-butyl)phosphidocyclopenta-
afforded a bis(cyclopentadienyl)mercury species (3) [17], which
was treated with CuBr2 to give the bromocyclopentadienyl complex
(h
5-C5H4Br)Re(CO)3 (4) [18]. This constituted the starting point for
new chemistry, with the bromide group viewed as a possible means
of introducing additional functionality by metal catalyzed substi-
tution reactions.
dienyl complex (h
5-C5H4Pt-Bu)2Re(NO)(PPh3)(CH3), which has a
The dialkylamide base lithium tetramethylpiperidide (LiTMP)
has previously been used to deprotonate cyclopentadienyl ligands
[19]. Accordingly, reactions of 4 with LiTMP (1.0 equiv) and then the
chlorophosphines ClPR2 (R ¼ a, Ph; b, Cy) at ꢀ78 ꢁC afforded the 1-
bromo-2-phosphidocyclopentadienyl
complexes
(h
5-1,2-
C5H3BrPR2)Re(CO)3 (5a,b) in 48% and 80% yields, respectively, af-
ter chromatographic workups (Scheme 1). In some cases, the
samples contained small amounts of the corresponding phosphi-
docyclopentadienyl complexes
(h
5-C5H4PR2)Re(CO)3 [9d], pre-
sumably generated via initial bromide/lithium exchange. These
could be removed by repeating the chromatography, or
recrystallization.
Next, analogous reactions were conducted, but using 2.0 equiv
of LiTMP and the chlorophosphine. After comparable workups, the
1-bromo-2,5-diphosphidocyclopentadienyl complexes
[h
5-1,2,5-
C5H2Br(PR2)2]Re(CO)3 (6a,b) could be isolated in 60% and 80%
yields, respectively. This suggests the intermediacy of the dilithio
species (h
5-1,2,5-C5H2BrLi2)Re(CO)3. Indeed, at least one other
rhenium dilithiocyclopentadienyl complex has been previously
characterized [20]. Also, an analogous dilithiation/diphenylphos-
phination product, V in Fig. 1, has been isolated in low yield from
the reaction of 1,10-dibromoferrocene with the dialkylamide base
LiN(i-Pr)2 and ClPPh2 [21]. As with 5a,b, some samples of 6a,b
showed small amounts of impurities, and these could be removed
by repeating the chromatography or crystallization.
Scheme 1. Syntheses of new complexes.

418
D. Sierra et al. / Journal of Organometallic Chemistry 749 (2014) 416e420
Table 1
Crystallographic data for 5b, 6a, and 6b.
Complex
5b
6a
6b
Empirical formula C20H25BrO3PRe
C32H22BrO3P2Re
782.55
110(2)
C32H46BrO3P2Re
806.74
110(2)
Formula weight 610.48
Temperature [K] 110(2)
Diffractometer Bruker GADDS
Bruker Smart 1000 Bruker GADDS
ꢀ
Wavelength [A]
Crystal system
Space group
1.54178
Monoclinic
P2(1)/c
0.71073
Triclinic
P-1
1.54178
Orthorhombic
P2(1)2(1)2(1)
Unit cell dimensions
ꢀ
a [A]
12.0944(7)
10.162(2)
12.083(3)
13.648(3)
104.308(2)
97.445(3)
113.747(2)
1435.8(6)
2
10.6760(4)
12.0665(5)
24.9980(9)
90
90
90
3220.3(2)
4
1.664
10.009
1608
ꢀ
b [A]
15.0884(9)
12.4653(8)
90
115.301(3)
90
2056.5(2)
4
1.972
ꢀ
c [A]
a
b
g
[ꢁ]
[ꢁ]
[ꢁ]
3
ꢀ
Volume [A ]
Z
rcalcd [mg/m3]
1.810
5.767
756
m
[mmꢀ1
]
14.706
1176
F(000)
Crystal
0.25 ꢂ 0.08 ꢂ 0.04 0.30 ꢂ 0.20 ꢂ 0.20 0.09 ꢂ 0.08 ꢂ 0.02
size [mm3]
Range for data
4.04 to 60.80
1.95 to 25.00
4.07 to 60.00
collection
ꢁ
(
Q,
)
Index ranges
ꢀ13 ꢃ h ꢃ 13
ꢀ17 ꢃ k ꢃ 17
ꢀ13 ꢃ l ꢃ 14
15,171
ꢀ12 ꢃ h ꢃ 12
ꢀ14 ꢃ k ꢃ 14
ꢀ16 ꢃ l ꢃ 16
13,397
ꢀ11 ꢃ h ꢃ 11
ꢀ13 ꢃ k ꢃ 13
ꢀ28 ꢃ l ꢃ 28
25,217
Reflections
collected
Independent
reflections
Max. and
3038
5008
4688
[R(int) ¼ 0.0496]
[R(int) ¼ 0.0360]
[R(int) ¼ 0.4661]
0.5908
0.5963
0.8249
min.
and 0.1201
and 0.2766
and 0.466
transmission
Data/restraints/
parameters
Goodness-
of-fit on F2
Final R indices
3038/0/235
1.030
5008/0/352
1.002
4688/0/353
1.036
R1 ¼ 0.0282,
wR2 ¼ 0.0729
R1 ¼ 0.0349,
wR2 ¼ 0.0751
01.339
R1 ¼ 0.0193,
wR2 ¼ 0.0488
R1 ¼ 0.0203,
wR2 ¼ 0.0494
0.916
R1 ¼ 0.0181,
wR2 ¼ 0.0442
R1 ¼ 0.0190,
wR2 ¼ 0.0444
0.894
[I > 2
R indices
(all data)
s(I)]
Largest diff.
peak &
and ꢀ1.393
and ꢀ0.922
and ꢀ0.580
ꢀꢀ3
hole [eA
]
more
p basic rhenium fragment, the sum of the bond angles about
the t-Bu2P moiety is greater (315ꢁ) [9e]. In contrast, the values for the
trisubstituted cyclopentadienyl ligand in ferrocene V (305.1ꢁ and
299.1ꢁ) are comparable to those in 6a. Hence, in all of the
new complexes, the phosphorus-carbon bonds must have higher
degrees of phosphorus p character. This requires the phosphorus lone
pairs to have enhanced s character, and thereby decreased basicities.
2.3. Catalysis
The rhenium-containing monophosphines and diphosphines
5a,b and 6a,b were evaluated as ligands for palladium catalyzed
Suzuki cross coupling reactions of phenylboronic acid under the
standard conditions summarized in Scheme 2. In the interest of
identifying the most active system, conversions were assayed after
20 min. With both coupling partners assayed, p-bromotoluene and
p-bromoacetophenone, the monodicyclohexylphosphine ligand 5b
exhibited much higher activity than the others, with conversions of
64e92% (entries 2, 5).
However, this activity is lower than when the non-brominated
Fig. 2. Thermal ellipsoid plots (50% probability levels) of the molecular structures of
5b (top), 6a (middle), and 6b (bottom).
diphenylphosphido analog (h
5-C5H4PPh2)Re(CO)3 is used as a
ligand, as well as the 1,2-disubstituted ferrocenyl phosphines I and
II described in previous reports [10,13,14]. This may be due to the

D. Sierra et al. / Journal of Organometallic Chemistry 749 (2014) 416e420
419
(tetramethylpiperidene), n-BuLi (2.5 M in hexane), ClPPh2, ClPCy2,
Pd(OAc)2, Cs2CO3, p-bromotoluene, p-bromoacetophenone, and phe-
nylboronic acid, used as received from common commercial sources.
The complexes
Re(CO)3 (2) [17], the corresponding bis(cyclopentadienyl) mercurial
3 [17], and (
5-C5H4Br)Re(CO)3 (4) [18] were synthesized by liter-
(h (h
5-C5H5)Re(CO)3 (1) [16], 5-C5H4HgCl)
h
ature procedures. LiTMP was freshly prepared as follows [24]. A
Schlenk flask was charged with TMPH (0.14 mL, 0.84 mmol) and a
stir bar and cooled to 0 ꢁC. Then n-BuLi (2.5 M in hexane; 0.34 mL,
0.85 mmol) was slowly added with stirring. After 15 min, the faint
yellow LiTMP suspension was added to the reaction mixture via
cannula.
NMR spectra were recorded on Varian NMRS 500 and Bruker
AVANCE 400 spectrometers at ambient probe temperatures and
referenced as follows: 1H, residual internal CHCl3 (
internal CDCl3 (d d, 0.00 ppm).
d
, 7.24 ppm); 13C,
, 77.0 ppm); 31P, external 85% H3PO4 (
FT IR spectra were recorded on a PerkineElmer Spectrum One FT-IR
in a NaCl solution cell. MS and GCeMS analyses were conducted
using a Shimadzu QP5050 instrument with a direct injection
capability for non-volatile samples.
Scheme 2. Suzukicrosscouplingreactions usingrheniumcontainingphosphineligands.
electron withdrawing effect of the bromide substituent, which
renders all of these ligands less basic and capable of promoting the
oxidative addition step of the catalytic cycle [22,23]. The marked
decrease of activity with 5a (entries 1, 5) would in turn reflect
the lower basicity of the diphenylphosphido moiety. A parallel
reactivity trend with 6b and 6a is evident (entries 4 and 8 vs. 3 and
7). Nonetheless, with longer reaction times, both 5a and 6b should
give synthetically useful conversion levels.
3.2. (
h
5-1,2-C5H3BrPR2)Re(CO)3 (5; R ¼ a, Ph; b, Cy)
A Schlenk flask was charged with 4 (0.350 g, 0.840 mmol) and
THF (10 mL) and placed in a ꢀ78 ꢁC cold bath. A solution of freshly
prepared LiTMP (0.84 mmol) was slowly added via cannula with
stirring. After 0.5 h, the flask was transferred to a ꢀ40 ꢁC cold bath.
After 3.0 h, the flask was transferred to a ꢀ78 ꢁC cold bath, and
ClPR2 (0.84 mmol) was slowly added with stirring. The cold bath
was allowed to warm overnight. The solvent was removed by oil
pump vacuum. The yellow oil was chromatographed on a silica gel
column that was eluted first with hexane to give unreacted 4 and
The lower activities of 6a,b relative to 5a,b might be ascribed to
the electron withdrawing effect of the additional phosphido sub-
stituent. However, note the absence of any correlation to the sums
of the bonds angles about the phosphorus donor groups. Finally,
although the Suzuki conditions employed are not strictly identical,
the diphenylphosphidocyclopentadienyl complex (h
5-C5H4PPh2)
then with 9:1 v/v hexanes/dichloromethane to give (h
5-C5H4PR2)
Re(NO)(PPh3)(CH3) appears to give a catalyst with an activity
similar to that with 5b [9e].
Re(CO)3 [18] followed by 5. The solvent was removed from the
product containing fractions by rotary evaporation and oil pump
vacuum to give 5 as a white amorphous powder (5a: 0.243 g,
0.406 mmol, 48%; 5b: 0.410 g, 0.672 mmol, 80%) [25]. Crystalliza-
tion of 5b from hot hexanes afforded colorless needles suitable for
X-ray diffraction. Calcd for C20H25BrO3PRe (610.49): C, 39.35; H,
4.19; C, 39.44, H, 4.19.
2.4. Conclusions
This study has shown that bromocyrhetrene, 4, is easily con-
verted to brominated cyrhetrenylmonophosphines and cyrhetrenyl-
1,3-diphosphines by monodeprotonation/monophosphination and
dideprotonation/diphosphination sequences, respectively. All of
these complexes exhibit planar chirality, and therefore constitute
highly attractive phosphorus donor ligands for metal-catalyzed re-
actions, especially those inwhich chiral products are generated from
achiral reactants. However, initial screening results with palladium
catalyzed Suzuki coupling reactions, in which the basicities of the
phosphorus donor groups are often important, are disappointing. In
retrospect, the non-coordinating electronegative cyclopentadienyl
substituents appear to be a step in the wrong direction for this
particular application. Accordingly, future efforts will be directed at
replacing the bromine functionality, and the introduction of more
basic and/or bulkier phosphido moieties. Nonetheless, the new li-
gands may prove useful for other types of metal catalyzed trans-
formations, and additional exploratory chemistry, including efforts
to resolve the enantiomers, will be reported in due course.
Data for 5a. IR nCO (cmꢀ1, CH2Cl2): 2029 (vs), 1938 (vs). NMR (
d,
CDCl3 (ppm)): 1H (400 MHz) 7.48e7.29 (m, 10H, Ph), 5.80 (m, 1H,
C5H3), 5.24 (m, 1H, C5H3), 4.91 (m, 1H, C5H3); 13C{1H} (101 MHz)
192.5 (s, ReCO), 136.6 (d, JCP ¼ 12 Hz, i-Ph), 134.7 (d, JCP ¼ 10 Hz, i-
Ph0), 134.5 (d, JCP ¼ 21 Hz, o-Ph), 132.3 (d, JCP ¼ 19 Hz, o-Ph0), 129.8
(s, p-Ph), 129.0 (s, p-Ph0), 128.8 (d, JCP ¼ 7 Hz, m-Ph) [26], 128.7 (d,
JCP ¼ 7 Hz, m-Ph0) [26], 98.2 (d, JCP ¼ 21 Hz, C5H3), 92.9 (d,
JCP ¼ 30 Hz, C5H3), 91.1 (d, JCP ¼ 4 Hz, C5H3), 89.7 (s, C5H3), 82.8 (s,
C5H3); 31P{1H} (162 MHz) ꢀ18.7 (s, PPh2).
Data for 5b. IR nCO (cmꢀ1, CH2Cl2): 2027 (vs), 1933 (vs). NMR (
d,
CDCl3 (ppm)): 1H (500 MHz) 5.68 (dt, J ¼ 2.9, 1.6 Hz, 1H, C5H3), 5.44
(dd, J ¼ 3.1,1.8 Hz,1H, C5H3), 5.26 (ddd, J ¼ 3.2, 2.7, 0.7 Hz,1H, C5H3),
2.09 (m, 2H, C6H11), 1.91e1.58 (m, 10H, C6H11), 1.40e1.10 (m, 10H,
C6H11); 13C{1H} (101 MHz) 193.0 (s, ReCO), 95.6 (d, JCP ¼ 38 Hz,
C5H3), 93.8 (d, JCP ¼ 27 Hz, C5H3), 91.4 (s, C5H3), 88.8 (s, C5H3), 82.6
(s, C5H3), 35.1 (apparent t, JCP ¼ 14 Hz, C6H11), 31.7 (d, JCP ¼ 17 Hz,
C6H11), 30.8 (d, JCP ¼ 17 Hz, C6H11), 30.0 (d, JCP ¼ 8 Hz, C6H11), 29.6
(d, JCP ¼ 10 Hz, C6H11), 27.6e26.7 (apparent m, C6H11), 26.2 (d,
JCP ¼ 7 Hz, C6H11); 31P{1H} (202 MHz) ꢀ8.1 (s, PCy2). Mass spectrum
(EI, m/z): 610 [Mþ], 582 [Mþ ꢀ CO], 503 [Mþ ꢀ CO ꢀ Br].
3. Experimental section
3.1. General methods
All reactions were conducted under nitrogen atmospheres, and
workups were carried out in air. Chemicals were treated as follows:
THF, dried over an alumina column and degassed by aspirating with
argon; toluene, freshly distilled from Na/benzophenone; TMPH
3.3. [
h
5-1,2,5-C5H2Br(PR2)2]Re(CO)3 (6; R ¼ a, Ph; b, Cy)
These compounds were synthesized by procedures analogous to
those for 5a,b using 4 (0.175 g, 0.420 mmol), freshly prepared LiTMP

420
D. Sierra et al. / Journal of Organometallic Chemistry 749 (2014) 416e420
(0.84 mmol), and ClPR2 (0.84 mmol). An identical chromatographic
workup afforded (
5-C5H4PR2)Re(CO)3 and then 6a (0.197 g,
Appendix A. Supplementary material
h
0.252 mmol, 60%) or 6b (0.336 g, 0.335 mmol, 80%) as white
powders [25]. Recrystallizations of 6a,b from hot hexanes yielded
colorless needles suitable for X-ray diffraction.
CCDC-953402 (for 5b), 953403 (for 6a), and 953404 (for 6b)
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif. Also provided are 1H, 13C{1H}, and 31P{1H} NMR
spectra of 5a,b and 6a,b.
Data for 6a. IR nCO (cmꢀ1, CH2Cl2): 2029 (vs), 1940 (vs). NMR (
d,
CDCl3 (ppm)): 1H (400 MHz) 7.50e7.30 (m, 20H, Ph), 4.82 (s, 2H, C5H2);
13C{1H} (101 MHz) 192.4 (s, ReCO), 136.4 (d, JCP ¼ 12 Hz, i-Ph), 134.7
(d, JCP ¼ 23 Hz, o-Ph), 134.0 (d, JCP ¼ 10 Hz, i-Ph0), 132.5 (d, JCP ¼ 20
Hz, o-Ph0), 130.0 (s, p-Ph), 129.1 (s, p-Ph0), 128.9e128.74 (apparent m,
m-Ph) [26],128.72e128.6 (apparent m, m-Ph0) [26],102.5 (d, J ¼ 21 Hz,
Appendix B. Supplementary data
PC5H2), 99.9 (s, C5H2), 89.0 (t,
J
¼
3
Hz, BrC5H2); 31P{1H}
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2013.10.029.
(202 MHz) ꢀ19.0 (s, PPh2). Mass spectrum (EI, m/z): 782 [Mþ], 754
[Mþ ꢀ CO], 726 [Mþ ꢀ 2CO], 698 [Mþ ꢀ 3CO], 617 [Mþ ꢀ 3CO ꢀ Br].
Data for 6b. IR nCO (cmꢀ1, CH2Cl2): 2025 (vs), 1933 (vs). NMR (
d,
References
CDCl3 (ppm)): 1H (500 MHz) 5.42 (s, 2H, C5H2), 2.06 (m, 4H, C6H11),
1.91e1.63 (m, 20H, C6H11), 1.39e1.12 (m, 20H, C6H11); 13C{1H}
(126 MHz) 193.1 (s, ReCO), 101.4 (t, JCP ¼ 20 Hz, BrC5H2), 99.2 (d,
JCP ¼ 39 Hz, PC5H2), 90.0 (d, JCP ¼ 5 Hz, C5H2), 34.7 (d, JCP ¼ 13
Hz, C6H11), 31.7 (d, JCP ¼ 16 Hz, C6H11), 30.7 (d, JCP ¼ 18 Hz, C6H11),
30.4 (d, JCP ¼ 9 Hz, C6H11), 30.0 (d, JCP ¼ 10 Hz, C6H11), 27.5e26.9
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phosphine ligand (0.0090 M in toluene; 1.0 mL, 0.0090 mmol;
2 mol%) and dry toluene (12.0 mL) with stirring. The flask was
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Data were collected as outlined in Table 1. Cell parameters for 5b
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(h
5-C5H4PR2)Re(CO)3. This could be removed by repeating the chromatog-
raphy, or recrystallization.
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[27] APEX2, Program for Data Collection on Area Detectors, BRUKER AXS Inc, 5465
East Cheryl Parkway, Madison, WI 53711e5373 USA.
Acknowledgments
We thank the Welch Foundation (Grant A-1656) and FONDECYT
Chile (Grant 1060487) for financial support, and CONICYT Chile for
doctoral and short research stay scholarships (D. S.).
[28] G.M. Sheldrick, Program for Absorption Correction of Area Detector Frames,
BRUKER AXS Inc, 5465 East Cheryl Parkway, Madison, WI 53711e5373 USA.
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