Reductive elimination of the alkenyl fragment and a phosphine ligand from [Rh(acac){(E)-CH=CHR}(PCy3)2]BF4 (R=Cy, Ph, H): Preparation of [(E)-RHC=CHPCy3]BF4 from alkynes

Article abstract of DOI:10.1016/S0022-328X(98)01072-9

In dichloromethane under reflux, the five-coordinate alkenyl complexes [Rh(acac){(E)-CH=CHR}(PCy₃)₂]BF₄ [R=Cy (1), Ph (2), H (3)] evolve into the alkenylphosphonium derivatives [Rh(acac){η²-(E)-CH(PCy₃)=CHR}(PCy ₃)]BF₄ [R=Cy (4), Ph (5), H(6)], by reductive elimination reactions involving the one-electron alkenyl fragments and one of the two-electron phosphine ligands of 1-3. Complexes 4-6 react with carbon monoxide to afford Rh(acac)(CO)(PCy₃) and [(E)-RHC=CHPCy₃]BF₄ [R=Cy (8), Ph (9), H (10)]. In addition, we describe a new route for the preparation of alkenylphophonium salts starting from terminal alkynes, PCy₃ and HBF₄, and using the Rh(acac)(PCy₃) unit as a template.

Full text of DOI:10.1016/S0022-328X(98)01072-9

Journal of Organometallic Chemistry 577 (1999) 265–270
Reductive elimination of the alkenyl fragment and a phosphine ligand
from [Rh(acac){(E)-CHꢀCHR}(PCy3)2]BF4 (R=Cy, Ph, H):
preparation of [(E)-RHCꢀCHPCy3]BF4 from alkynes
Miguel A. Esteruelas a,*, Fernando J. Lahoz a, Marta Mart´ın a, Ana Mart´ınez a, Luis A. Oro a,
M. Carmen Puerta b, Pedro Valerga b
a Departamento de Qu´ımica Inorga´nica-ICMA, Uni6ersidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
b Departamento de Ciencia de Materiales e Ingenier´ıa Metalu´rgica y Qu´ımica Ino´rganica, Uni6ersidad de Ca´diz, Apartado 40 11510 Puerto Real,
Ca´diz, Spain
Received 14 September 1998
Abstract
In dichloromethane under reflux, the five-coordinate alkenyl complexes [Rh(acac){(E)-CHꢀCHR}(PCy3)2]BF4 [R=Cy (1), Ph
(2), H (3)] evolve into the alkenylphosphonium derivatives [Rh(acac){h2-(E)-CH(PCy3)ꢀCHR}(PCy3)]BF4 [R=Cy (4), Ph (5),
H(6)], by reductive elimination reactions involving the one-electron alkenyl fragments and one of the two-electron phosphine
ligands of 1–3. Complexes 4–6 react with carbon monoxide to afford Rh(acac)(CO)(PCy3) and [(E)-RHCꢀCHPCy3]BF4 [R=Cy
(8), Ph (9), H (10)]. In addition, we describe a new route for the preparation of alkenylphophonium salts starting from terminal
alkynes, PCy3 and HBF4, and using the Rh(acac)(PCy3) unit as a template. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Reductive elimination; Alkenyl fragment; Phosphine
1. Introduction
carbon monoxide to afford Rh(acac)(CO)(PR3) and
[Ph2CꢀCꢀCHPR3]BF4 (PR3=PCy3, PiPr3). The forma-
tion of the square-planar allenylphosphonium com-
plexes [Rh(acac){h2-CH(PR3)ꢀCꢀCPh2}(PR3)]BF4 from
the corresponding five-coordinate rhodium(III) allenyl
precursors is a result of intramolecular reductive elimi-
nations involving the one-electron allenyl fragment and
the two-electron phosphine ligands [18]. These type of
reductive elimination reactions are uncommon, and
previously they had been observed by Rubinskaya and
co-workers [19] and Guerchais and co-workers [20] in
neutral palladium and tungsten complexes, respectively.
Two years ago we reported the synthesis of the five-
coordinatealkenylcomplexes[Rh(acac){(E)-CHꢀCHR}-
(PCy3)2]BF4 (R=Cy, H) which, in contrast to the
allenyl species [Rh(acac){CHꢀCꢀCPh2}-(PR3)2]BF4, are
stable at r.t. [21]. In this paper we show that this type
of reductive elimination not only occurs in five-coor-
dinate allenyl rhodium(III) complexes but also in
Alkenylphosphonium salts play a main role in or-
ganic synthesis as intermediates reagents in processes
such as ring formation by Michael–Wittig, Michael-nu-
cleophilic displacement and Diels–Alder sequences;
phosphonioethylation; two-carbon chain-linking and
alkenation [1–17].
We have recently shown that the protonation of the
hydrido–alkynyl complexes Rh(acac){CꢁCC(OH)Ph2}-
H(PR3)2 with HBF4 leads to the allenyl derivatives
[Rh(acac){CHꢀCꢀCPh2}(PR3)2]BF4 (PR3=PCy3, PiP-
r3), which evolve at room temperature (r.t.) into the
square-planar rhodium(I) complexes [Rh(acac){h2-
CH(PR3)ꢀCꢀCPh2}(PR3)]BF4. The allenylphosphonium
ligand can be displaced from these compounds by
* Corresponding author. Fax: +34-976-76-11-87.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01072-9

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M.A. Esteruelas et al. / Journal of Organometallic Chemistry 577 (1999) 265–270
five-coordinate alkenyl rhodium(III) compounds. In ad-
dition, we describe a new route for the preparation of
alkenylphosphonium salts starting from terminal alky-
nes and using the Rh(acac)(PCy3) unit as a template.
2. Results and discussion
Although the alkenyl complexes [Rh(acac){(E)-
CHꢀCHR}(PCy3)2]BF4 [R=Cy (1), Ph (2), H (3)] are
stable in dichloromethane at r.t., under reflux they
undergo the intramolecular reductive elimination of the
corresponding alkenylphosphonium ligand to afford
the
rhodium(I)
derivatives
[Rh(acac){h2-(E)-
CH(PCy3)ꢀCHR}(PCy3)]BF4 [R=Cy (4), Ph (5), H
(6)], which were isolated as orange–yellow solids
(Scheme 1).
Complexes 4–6 were characterized by elemental anal-
ysis, IR and 1H-, 31P- and 13C-NMR spectroscopies.
Complex 4 was further characterized by an X-ray crys-
tallographic study. A view of the molecular geometry is
shown in Fig. 1.
The coordination geometry around the rhodium cen-
ter is square planar, with the b-diketonato ligand acting
with a bite angle of 87.6(1)° (Table 1). Although we
find the two olefinic carbons statically disordered, we
can confirm, without any doubt, that the alkenylphos-
phonium ligand has a trans stereochemistry at the CꢀC
double bond. Olefinic carbons, C(1) and C(2), of the
alkenylphosphonium ligand were modelled using two
geometrically restrained moieties.
Fig. 1. Molecular representation for the cationic complex
[Rh(acac){h2-(E)-CH(PCy3)ꢀCHCy}(PCy3)]BF4 (4). Only one group
of atoms has been drawn for the disordered olefinic carbon atoms.
constants between 55 and 58 Hz (Cy3P–Cꢀ) and about
3 Hz (Cy3P–Rh), and C–Rh coupling constants be-
tween 16 and 19 Hz. The 31P{1H}-NMR spectra of 4–6
show two doublets. Those corresponding to the tricy-
clohexylphosphine coordinated to the rhodium atom
appear between 37 and 47 ppm and show P–Rh cou-
pling constants of about 170 Hz, while the tricyclo-
hexylphosphine groups bonded to the ꢀCH carbon
atoms are observed between 33 and 36 ppm and show
P–Rh coupling constants of about 6 Hz.
The alkenylphosphonium ligands of 4–6 can be dis-
placed
by
carbon
monoxide
to
afford
The trans stereochemistry at the CꢀC double bond of
the alkenylphosphonium ligands is also supported by
the 1H-NMR spectra of 4–6, which shows a H–H
coupling constant of 13.5 Hz in the three cases. In the
13C{1H}-NMR spectra, the resonances due to the sp2-
carbon atoms of alkenylphosphonium ligands appear
between 76 and 62 ppm (ꢀCHR) and at about 17 ppm
(ꢀCHPCy3). The first as doublets with C–P coupling
constants between 15 and 18 Hz, and the second as
doublet of doublet of doublets with C–P coupling
Rh(acac)(CO)(PCy3) and the alkenylphosphonium salts
[(E)-RHCꢀCHPCy3]BF4 [R=Cy (8), Ph (9), H (10)],
which were isolated as white solids.
The spectroscopic data of 8–10 agree well with those
previously reported by Freeman, Schweizer and co-
workers [22,23] for related compounds. In the 1H-NMR
spectra the vinylic hydrogen resonances appear between
7 and 5 ppm, while in the 13C{1H}-NMR spectra the
sp2-carbon resonances are observed between 100 and
115 ppm (ꢀCHP) and between 166 and 143 ppm
(ꢀCHR). The 31P{1H}-NMR spectra shows singlets at
about 27 ppm.
Table 1
˚
Selected bond lengths (A) and angles (°) for the cationic complex
[Rh(acac){h2-(E)-CH(PCy3)ꢀCHCy}(PCy3)]BF4 (4)
˚
Bond lengths (A)
Rh(1)–O(1)
Rh(1)–O(2)
Rh(1)–C(mean)
2.078(3)
2.052(3)
2.093(4)
Rh(1)–P(2)
O(1)–C(45)
O(2)–C(47)
2.2974(11)
1.267(6)
1.277(6)
Bond angles (°)
P(2)–Rh(1)–O(1) 170.64(9)
P(2)–Rh(1)–O(2) 85.56(10)
O(1)–Rh(1)–O(2) 87.6(1)
Scheme 1.

M.A. Esteruelas et al. / Journal of Organometallic Chemistry 577 (1999) 265–270
267
We have previously reported that the addition of one
equivalent of terminal alkynes to solutions containing
equimolecular amounts of Rh(acac)(h2-C8H14)(PCy3)
and PCy3 leads to the hydrido–alkynyl complexes
Rh(acac)(C2R)H(PCy3)2, which react with HBF4 to af-
ford complexes 1–3. These reactions together with
those shown in Scheme 1 constitute a new synthetic
route to easily prepare alkenylphosphonium salts,
which involves the formal cis-addition of [HPCy3]BF4
to the carbon–carbon triple bond of terminal alkynes,
in the presence of the Rh(acac)(PCy3) unit. When the
intermediate rhodium complexes of the route are not
isolated, the alkenylphosphonium salts are obtained in
higher yields above 80%, and the rhodium used can
also be recovered in a higher yield above 80%.
In conclusion, in dichloromethane under reflux, the
five-coordinate alkenyl compounds [Rh(acac){(E)-
CHꢀCHR}(PCy3)2]BF4 are not stable and evolve by
reductive elimination into the alkenylphosphonium
derivatives [Rh(acac){h2-(E)-CH(PCy3)ꢀCHR}(PCy3)]-
BF4. This unusual reaction allows the preparation of
the alkenylphosphonium salts [(E)-RHCꢀCHPCy3]BF4
in high yields by formal addition of [HPCy3]BF4 to
terminal alkynes, using the unit Rh(acac)(PCy3) as a
template.
(72%). Anal. Calc. for C49H80BF4O2P2Rh: C, 61.76; H,
8.46%. Found: C, 61.41; H, 8.39. IR (KBr, cm−1):
w(CO)acac 1568 and 1524, w(BF4) 1056. H-NMR (300
1
MHz, CD2Cl2, 293 K): l 7.79 (dt, 1H, JHH=12.3,
JPH=9.9, RhCH), 7.3–7.1 (m, 5H, Ph), 5.99 (s, 1H,
CH of acac), 5.49 (dd, 1H, JHH=12.3, JPH=1.5,
RhCHꢀCH), 2.5–1.2 (m, 66H, C6H11), 2.19 (s, 6H,
1
CH3 of acac). H-NMR (300 MHz, CD2Cl2, 213 K): l
2.13 and 2.10 (both s, 6H, CH3 of acac). 31P{1H}-NMR
(121.4 MHz, CD2Cl2, 293 K): l 31.9 (d, JRhP=137.4).
31P{1H}-NMR (121.4 MHz, CD2Cl2, 213 K): l 34.3
(dd, JRhP=131.2, JPP=27.9), 22.6 (dd, JRhP=143.5,
J
PP=27.9). 13C{1H}-NMR (75.4 MHz, CD2Cl2, 213
K): l 186.0 and 185.5 (both s, CO of acac), 134.5 (s,
RhCHꢀCH), 129.2 (s, Cipso-Ph), 128.4 (s, Co-Ph), 126.3 (s,
Cp-Ph), 125.0 (s, Cm-Ph), 120.1 (dt, JRhC=32.9 JPC=7.9,
RhCHꢀCH), 100.2 (s, CH of acac), signals in the
region 37.2–25.6 ppm assigned to PCy3 and CH3 of
acac are very broad.
3.2. Preparation of [Rh(acac){p2-(E)-CH(PCy3)
ꢀCHCy}(PCy3)]BF4 (4)
A yellow solution of 1 (201.0 mg, 0.21 mmol) in 10
ml of dichloromethane was stirred under reflux for 10
h. The resulting orange solution was cooled and filtered
through Kieselguhr, and the filtrate was concentrated
to ca. 0.1 ml in vacuo; addition of diethyl ether caused
the precipitation of an orange–yellow solid. The solid
was decanted and washed with diethyl ether. Yield: 153
mg (76%). Anal. Calc. for C49H86BF4O2P2Rh: C, 61.38;
H, 9.04%. Found: C, 60.95; H, 9.12. IR (KBr, cm−1):
3. Experimental section
All reactions were carried out under an atmosphere
of argon by using Schlenk-tube techniques. Solvents
were dried by the usual procedures and distilled under
argon prior to use. The starting materials Rh(acac)-
1
w(CO)acac 1582 and 1520, w(BF4) 1056. H-NMR (300
(CꢁCPh)H(PCy3)2
and
[Rh(acac){(E)-CHꢀCHR}-
MHz, CD2Cl2, 293 K): l 5.50 (s, 1H, CH of acac), 3.70
(ddd, 1H, JHH=JPH=13.5, JHH’=6.7, ꢀCHCy), 2.7–
1.4 (m, 77H, C6H11), 2.01 and 1.94 (both s, 6H, CH3 of
(PCy3)2]BF4 [R=Cy (1), H (3)] were prepared by a
published method [21]. IR spectra were recorded on a
Perkin Elmer 883 spectrometer, and the NMR spectra
on Varian UNITY 300, Varian GEMINI 2000 (300
MHz) and Bruker ARX 300 instruments. Coupling
constants J are given in Hertz. Spectra assignment was
1
acac), signal of CH(PCy3) is localized in the H-COSY
spectrum at 1.36 ppm. 31P{1H}-NMR (121.4 MHz,
CD2Cl2, 293 K): l 37.8 (d, JRhP=170.3, Rh(PCy3)),
2
33.7 (d, JRhP=7.0, CH(PCy3)). 13C{1H}-NMR (75.4
achieved with the aid of H{31P}, H-COSY and 13C-
DEPT experiments. C and H analyses were carried out
with a Perkin Elmer 2400 CHNS/O microanalyser.
MHz, CD2Cl2, 293 K): l 186.8 and 185.7 (both s, CO
1
1
2
of acac), 100.3 (s, CH of acac), 75.1 (d, JPC=18.0,
ꢀCHCy), 45.8 (d, 3JPC=5.1, CH of Cy), 36.7, 33.2,
31.0 and 29.9 (all s, CH2 of Cy), 34.4 and 32.5 (both br,
CH of PCy3), 33.7 (d, JPC=40.0, CH of PCy3), 30.2,
30.1, 28.7, 28.6, 28.34, 28.25, 28.2, 28.1, 27.6, 27.4, 27.3,
27.1, 27.0, 26.9, 26.7, 26.3, 26.2 and 25.8 (all s, CH2 of
PCy3), 28.0 (d, JPC=5.9, CH3 of acac), 26.6 (s, CH3 of
acac), 16.6 (ddd, JPC=55.7, JRhC=16.1, 2JP’C=2.7,
CH(PCy3)).
3.1. Preparation of [Rh(acac){(E)-CHꢀCHPh}-
(PCy3)2]BF4 (2)
A suspension of Rh(acac)(CꢁCPh)H(PCy3)2 (259.5
mg, 0.30 mmol) in 7 ml of dichloromethane was cooled
at −78°C and then a stoichoimetric amount of
HBF4 · OEt2 (44 ml, 0.33 mmol) was added. A change
from white to yellow occurred almost instantaneously.
The resulting solution was stirring for 30 min at −
78°C, and then was carried out to r.t. The solvent was
removed in vacuo and the residue was washed with
diethyl ether to give a yellow solid. Yield: 206 mg
3.3. Preparation of [Rh(acac){p2-(E)-CH(PCy3)ꢀ
CHPh}(PCy3)]BF4 (5)
This compound was prepared as described for 4,
using 2 (238.2 mg, 0.25 mmol) as starting material:

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M.A. Esteruelas et al. / Journal of Organometallic Chemistry 577 (1999) 265–270
orange–yellow solid. Yield: 190 mg (80%). Anal. Calc.
for C49H80BF4O2P2Rh: C, 61.76; H, 8.46%. Found: C,
61.39; H, 8.33. IR (KBr, cm−1): w(CO)acac 1572 and
C26H46BF4P: C, 65.55; H, 9.73%. Found: C, 65.23; H,
9.32. IR (KBr, cm−1): w(BF4) 1053. 1H-NMR (300
MHz, CD2Cl2, 293 K): l 6.67 (ddd, 1H, JHH=JPH
17.6, JHH’=6.5, CH(PCy3)), 5.54 (dd, 1H, JHH
=
=
1
1529, w(BF4) 1054. H-NMR (300 MHz, CD2Cl2, 293
K): l 7.5–7.2 (m, 5H, Ph), 5.61 (s, 1H, CH of acac),
5.47 (dd, 1H, JHH=JPH=13.5, ꢀCHPh), 2.6–1.2 (m,
66H, C6H11), 2.12 and 2.03 (both s, 6H, CH3 of acac),
JPH=17.6, ꢀCHCy), 2.5–1.1 (m, 44H, C6H11).
31P{1H}-NMR (121.4 MHz, CD2Cl2, 293 K): l 25.7 (s).
13C{1H}-NMR (75.4 MHz, CD2Cl2, 293 K): l 166.0 (s,
ꢀCHCy), 101.5 (d, JPC=74.3, CH(PCy3)), 44.3 (d,
3JPC=13.7, CH of Cy), 30.4 (d, JPC=43.2, CH of
PCy3), 31.8, 27.0, 26.9, 26.7, 26.1, and 25.8 (all s, CH2
of Cy and PCy3).
1
signal of CH(PCy3) is localized in the H-COSY spec-
trum at 2.20 ppm. 31P{1H}-NMR (121.4 MHz, CD2Cl2,
293 K): l 40.1 (d, JRhP=169.3, Rh(PCy3)), 33.9 (d,
2JRhP=6.2, CH(PCy3)). 13C{1H}-NMR (75.4 MHz,
CD2Cl2, 293 K): l 187.4 and 185.6 (both s, CO of
3
acac), 141.8 (d, JPC=6.8, Cipso-Ph), 129.7 (s, Co,m-Ph),
3.6. Preparation of [(E)-HPhCꢀCHPCy3]BF4 (9)
2
127.7 (s, Cp-Ph), 100.3 (s, CH of acac), 62.2 (d, JPC
=
15.7, ꢀCHPh), 34.3 (d, JPC=40.3, CH of PCy3), 33.0
(d, JPC=21.6, CH of PCy3), 30.4, 29.9, 28.6, 28.1, 27.7,
27.5, 27.4, 27.3, 26.7, 26.4 and 25.9 (all s, CH2 of
PCy3), 28.0 (s, CH3 of acac), 26.8 (d, JPC=6.0, CH3 of
acac), 16.8 (ddd, JPC=58.0, JRhC=18.8, 2JP’C=3.8,
CH(PCy3)).
This compound was prepared as described for 8,
using compound 5 (95.2 mg, 0.10 mmol) as starting
material: white solid. Yield: 46 mg (98%). Anal. Calc.
for C26H40BF4P: C, 66.39; H, 8.57%. Found: C, 66.55;
1
H, 8.91. IR (KBr, cm−1): w(BF4) 1051. H-NMR (300
MHz, CD2Cl2, 293 K): l 7.7–7.5 (m, 5H, Ph), 7.42 (dd,
1H, JHH=JPH=17.4, ꢀCHPh), 6.27 (dd, 1H, JHH
=
3.4. Preparation of [Rh(acac){p2-(E)-CH(PCy3)ꢀ
CH2}(PCy3)]BF4 (6)
17.4, JPH=15.9, CH(PCy3)), 2.6–1.3 (m, 33H, C6H11).
31P{1H}-NMR (121.4 MHz, CD2Cl2, 293 K): l 28.0 (s).
13C{1H}-NMR (75.4 MHz, CD2Cl2, 293 K): l 154.2 (s,
ꢀCHPh), 134.3 (d, 3JPC=16.5, Cipso-Ph), 132.1, 129.4
A yellow solution of 3 (201.6 mg, 0.23 mmol) in 10
ml of dichloromethane was stirred under reflux for 10
h. The resulting dark brown solution was concentrated
to dryness, and the oil obtained was cromatographed
on Al2O3 (neutral, activity grade I, column length 15
cm). With acetone a yellow fraction was eluted from
which the solvent was removed in vacuo. The residue
was washed with diethyl ether to give compound 6 as a
yellow solid: yield: 30 mg (15%). Anal. Calc. for
C43H76BF4O2P2Rh: C, 58.91; H, 8.74%. Found: C,
58.36; H, 8.51. IR (KBr, cm−1): w(CO)acac 1570 and
and 128.7 (all s, Co,
p-Ph), 100.8 (d, JPC=77.8,
m,
CH(PCy3)), 30.7 (d, JPC=43.1, CH of PCy3), 27.0,
26.91, 26.97, 26.6 and 25.8 (all s, CH2 of PCy3).
3.7. Preparation of [(E)-H2CꢀCHPCy3]BF4 (10)
This compound was prepared as described for 8,
using compound 6 (30.0 mg, 0.036 mmol) as starting
material: white solid. Yield: 12 mg (86%). Anal. Calc.
for C20H36BF4P: C, 60.92; H, 9.20%. Found: C, 60.85;
1
1
1524, w(BF4) 1056. H-NMR (300 MHz, CD2Cl2, 293
H, 9.32. IR (KBr, cm−1): w(BF4) 1042. H-NMR (300
K): l 5.54 (s, 1H, CH of acac), 3.30 (dd, 1H, JHH
=
MHz, CD2Cl2, 293 K): l 6.82 (part A of a ABCX
system, 1H, JPH=41.7, ꢀCH2), 6.53 (part BC of a
ABCX system, 2H, JPH=19.5, ꢀCH2 and CH(PCy3)),
2.7–1.1 (m, 33H, C6H11). 31P{1H}-NMR (121.4 MHz,
CD2Cl2, 293 K): l 27.2 (s). 13C{1H}-NMR (75.4 MHz,
JPH=13.3, ꢀCH2), 3.05 (dd, 1H, JPH=20.4, JHH=7.5,
ꢀCH2), 2.5–1.2 (m, 66H, C6H11), 2.05 and 1.25 (both s,
6H, CH3 of acac), signal of CH(PCy3) is localized in
the 1H-COSY spectrum at 1.75 ppm. 31P{1H}-NMR
(121.4 MHz, CD2Cl2, 293 K): l 44.1 (d, JRhP=163.9,
CD2Cl2, 293 K): l 143.3 (s, ꢀCHPh), 115.0 (d, JPC
=
2
Rh(PCy3)), 35.6 (d, JRhP=5.2, CH(PCy3)).
69.6, CH(PCy3)), 30.2 (d, JPC=42.2, CH of PCy3),
27.1, 27.0, 26.9, 26.7 and 25.9 (all s, CH2 PCy3).
3.5. Preparation of [(E)-CyHCꢀCHPCy3]BF4 (8)
Compounds 8–10 were also obtained by the follow-
ing method: solutions of complex Rh(acac)(h2-
C8H14)(PCy3)5 (100.8 mg, 0.17 mmol) in toluene were
treated with one equivalent of HCꢁCR (R=Cy, Ph, or
SiMe3) in the presence of equimolecular amounts of
PCy3 (47.7 mg, 0.17 mmol). After stirring at 50°C until
white solids precipitated (about 30 min), the solvent
was removed and the residues were dissolved in
dichloromethane and treated with one equivalent of
HBF4 · OEt2 (26 ml, 0.19 mmol). The solvent was re-
moved and after addition of diethyl ether yellow solids
were precipitated, which were washed with diethyl
A stream of CO was passed through a solution of
compound 4 (200.0 mg, 0.21 mmol) in 10 ml of
dichloromethane for 2 min. A change from yellow to
light yellow occurred almost instantaneously. Then the
solvent was removed and the addition of diethyl ether
caused the precipitation of a white solid, which was
washed with diethyl ether. The ether solution was con-
centrated in vacuo to produce a residue, which was
identified as Rh(acac)(CO)(PCy3)5 (7). The white solid
was identified as 8. Yield: 92 mg (96%). Anal. Calc. for

M.A. Esteruelas et al. / Journal of Organometallic Chemistry 577 (1999) 265–270
269
Table 2
maximum transmission factors, 0.185 and 0.227, respec-
tively. The structure was solved by direct methods [24]
and refined by full-matrix least-squares on F2 [25].
After isotropic refinement, the presence of high electron
density residuals in the proximity of the olefinic carbons
[C(1) and C(2)] together with the impossibility of a
proper refinement of an anisotropic model for these
two atoms suggested the presence of a situation of
static disorder affecting fundamentally these two car-
bon atoms. The molecule disorder was carefully step-
wise modeled after anisotropic refinement of all
non-hydrogen non-disordered atoms. Two different po-
sitions were included for each olefinic carbon [C(1a)
and C(2a), and C(1b) and C(2b)], and were refined with
complementary occupancy factors, a common fixed dis-
placement parameter, and feeble geometric restrains
(DFIX commands applied to Rh–C(1)/C(2), P–C(1),
C(1)–C(2) and C(2)–C(3) bond distances). Geometric
data for these restrains were obtained from a detailed
search of related complexes in the CSD file; distances
Crystal data and data collection and refinement for [Rh(acac){h2-(E)-
CH(PCy3)ꢀCHCy}(PCy3)]BF4 (4)
Empirical formula
Molecular weight
Color and habit
Crystal size (mm)
Symmetry
C449H86BF4O2P2Rh · CH2Cl2
1043.76
Orange, prismatic block
0.37×0.29×0.26
Triclinic
Space group
P1
Unit cell dimensions
˚
a (A)
11.4093(14)
13.0571(17)
18.797(3)
96.989(11)
94.308(9)
109.110(9)
2606.5(6)
2
˚
b (A)
˚
c (A)
h (°)
i (°)
k (°)
−3
˚
V (A
)
Z
Dcalc. (g cm−3
)
1.330
Diffractometer
u(Mo–Kh) (A); technique
Siemens-STOE
0.71073; bisecting geometry
Graphite oriented
0.543
˚
Monochromator
v (mm−1
)
˚
Scan type
2q range (°)
ꢀ/2q
352q550°
173.0(2)
11730
9216
564
0.1526
0.0580
1.058
used were 2.11, 1.77, 1.39 and 1.48 A, respectively
(more details in supplementary material). All disor-
dered atoms were refined isotropically and hydrogen
atoms were included in calculated positions. A crystal-
lization solvent molecule (dichloromethane) was also
detected and included in the refinement. Final agree-
ment factors were R1 0.0580 [I=2|(I), 7908 reflections]
and wR2 0.1526 (all data).
Temperature (K)
No. of data collected
No. of unique data
No. of parameters refined
wRa (all data)
Rb [observed data, I\2|(I)]
Goodness-of-fitc
a wR(F2)={ꢀ[w(F2o−F2c)2]/ꢀ[w(F2o)2]}1/2
.
b R(F)=SꢁFoꢂ−ꢂFcꢁ/SꢂFo.
c S={S[ꢀ(Fo2−Fc2)2]/(n−p)}1/2, where n is the number of reflec-
tions and p the number of parameters.
5. Supporting information available
A listing of full experimental details of the structure
determination, crystal data, atomic coordinates, ther-
mal parameters, bond distances and angles for 4 (CIF
format, 15 pages). Ordering information is given on any
current masthead page.
ether. This solid was dissolved in dichoromethane and
stirred under reflux for 10 h. Then, a stream of CO was
passed through the solutions for 2 min and the solvent
was removed, the addition of diethyl ether caused the
precipitation of white solids, which were washed with
diethyl ether. From the ether solution was isolated the
complex Rh(acac)(CO)(PCy3) (7), [21] and the white
solids were identified as [(E)-RHCꢀCHPCy3]BF4 [R=
Cy (8), Ph (9) or H (10)] (yields about 85%).
Acknowledgements
We thank the DGICYT (Projects PB 94-1186 and PB
95-0806, Programa de Promocio´n General del
Conocimiento) for financial support. A. Mart´ınez is
grateful for the F.P.I. grant (M.E.C.).
4. Crystal data for 4
Crystals suitable for the X-ray diffraction study were
obtained by slow diffusion of pentane into a saturated
solution of 4 in dichloromethane. A summary of crystal
and refinement data is reported in Table 2. Data were
collected on a Siemens-Stoe diffractometer by using
oil-coated rapidly cooled crystal of approximate dimen-
sions 0.37×0.29×0.26 mm mounted directly from so-
lution. Of a total of 11730 reflections collected by ꢀ/2q
scans (352q550°), 9216 were unique. Data were cor-
rected for absorption (psi-scan method); minimum and
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