Thioethercarboxylates in palladium chemistry: First proof of hemilabile properties of S-O ligands1

Article abstract of DOI:10.1016/S0022-328X(97)00573-1

The reaction of trans-[PdCl(Ph)(PPh₃)₂] with the thallium salts 2-RS-C₆H₄-COOTl (R=Me, Et, i-Pr or t-Bu) yields the compounds trans-[Pd(OOC-C₆H₄-2-SR-κ¹-O)Ph(PPh ₃)₂] (1a-d). The solid state structure of the compound with R=Et has been confirmed by X-ray analysis. In solution, however, an equilibrium is established between certain complexes in which one PPh₃ ligand is replaced by the sulphur atom of the S-O ligand to afford chelates. The position of the equilibrium depends on both the electron density on the sulphur and the polarity of the solvent used. The standard free energy and activation energy of the mentioned equilibrium are ΔG⁰=22 kJ/mol and E_A=25-30 kJ/mol for the complex with R=i-Pr (1c).

Full text of DOI:10.1016/S0022-328X(97)00573-1

Ž
.
Journal of Organometallic Chemistry 553 1998 83–90
Thioethercarboxylates in palladium chemistry: First proof of hemilabile
1
properties of S–O ligands
)
Wolfgang H. Meyer, Robert Brull, Helgard G. Raubenheimer , Catharine Thompson,
¨
Gert J. Kruger
Department of Chemistry and Biochemistry, Rand Afrikaans UniÕersity, P.O. Box 524, Auckland Park, Johannesburg 2006, South Africa
Received 20 March 1997
Abstract
w
Ž
.Ž
.
. x
2
Ž
.
The reaction of trans- PdCl Ph PPh3 with the thallium salts 2-RS-C6H4-COOTl RsMe, Et, i-Pr or t-Bu yields the compounds
2. x Ž
.
1a–d . The solid state structure of the compound with RsEt has been confirmed by
1
w
Ž
Ž
trans- Pd OOC-C6H4-2-SR-k -O Ph PPh3
X-ray analysis. In solution, however, an equilibrium is established between certain complexes in which one PPh3 ligand is replaced by
the sulphur atom of the S–O ligand to afford chelates. The position of the equilibrium depends on both the electron density on the sulphur
and the polarity of the solvent used. The standard free energy and activation energy of the mentioned equilibrium are DG0s22 kJrmol
Ž
.
and EAs25–30 kJrmol for the complex with Rsi-Pr 1c . q 1998 Elsevier Science S.A.
Keywords: Palladium; Arylpalladium complexes; Hemilability; Sulphur–oxygen ligands
1. Introduction
thioethercarboxylate S–O ligands. The molecular struc-
ture of one such a complex showed that the potentially
bidentate ligand is only oxygen-bonded. In others, hemi-
labile behaviour of S–O ligands with respect to PPh3
substitution in solution, was observed.
Activity, selectivity and stability are the most impor-
tant features of an organometallic catalyst precursor.
The search for a balance between high activity on the
one hand and sufficient stability on the other leads to
the concept of ‘hemilability’. According to the gener-
ally accepted belief, a hemilabile bidentate chelating
ligand liberates one coordination site of the metal center
only ‘on demand’ of a competing substrate like an
olefin.
2. Results and discussion
(
2.1. Syntheses of trans-2-alkylthiobenzoatobis triphen-
( )
)
(
)
ylphosphine phenylpalladium II complexes 1a–d
w
x
P–O ligands 1–15 are well investigated and their
hemilabile behaviour has been proven by spectroscopic
Ž
The new phenylpalladium compounds 1a–d Scheme
.Ž 2 x
w
x
.
w
Ž
.
methods 1,14 . Under catalytic conditions a number of
P–O compounds function as monodentate ligands
1 were prepared by stirring trans- PdCl Ph PPh3
with 2-RS-C6 H4-COOTl in tetrahydrofuran for three
days at room temperature. The precipitation of TlCl,
which was filtered off, drove the reaction. The com-
plexes were finally obtained in moderate yields by
crystallisation from THFrpentane.
w
w
w
x
w
x
5,11,15 . Potentially hemilabile P–N 16–19 , P–S
x
w
x
w x
5,20–22 , N–O 23–25 , O–O 24 and S–O ligands
x
24 have been examined to a much lesser extent.
In this paper we describe the synthesis and character-
isation of phenylpalladium compounds bearing alkyl-
The crystal and molecular structures of 1a and 1b
were determined by X-ray diffraction, but only results
2
for the latter are reported here. The molecular struc-
)
Corresponding author. Tel.: q27-11-489-2365; fax: q27-11-
489-2363.
1 Dedicated to Professor Wolfgang Beck, on the occasion of his
65th birthday.
2 G.J. Kruger, C. Thompson, W.H. Meyer, R. Brull, H.G. Rauben-
¨
heimer, unpublished results.
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

(
)
84
W.H. Meyer et al.rJournal of Organometallic Chemistry 553 1998 83–90
Scheme 1. Preparation of phenylpalladium compounds 1a–d.
Ž
.
Ž
ture of 1b clearly shows that the sulphur atom is
established for compounds 1c chloroform and 1d ben-
.
non-coordinating in the solid state under the chosen
zene and chloroform and was clearly recognizable in
their P NMR spectra Table 1, Fig. 2 .
31
Ž
.
Ž
.
reaction conditions Fig. 1 .
Complexes 1a and 1b formed neither in benzene-d6
nor in chloroform-d1 complexes of type 2 containing
Pd–S bonds. In compound 1c, one PPh3 ligand was
substituted only in chloroform-d1 solution and this pro-
cess is indicated by the appearance of a new signal at d
26.6 and by the consequent presence of the signal for
free PPh3 at dy4.7 in the 31 P NMR spectrum. Even at
708C no trace of 2c was found in benzene-d6. For
complex 1d, with the highest expected electron density
on the sulphur, the chelate complex 2d was observed in
both deuterated benzene and chloroform. Thus, the posi-
tion of the equilibrium depends on both the electron
density on the sulphur and the polarity of the solvent
used: the higher the electron density and the more polar
the solvent the more the equilibrium is shifted to the
2.2. Infrared spectroscopic characterisation of com-
plexes 1a–d
Ž
.
The asymmetric and symmetric Õ CO stretching
vibrations for the carboxyl group of the S–O ligands in
complexes 1a–d are found between 1595–1608 cmy1
and 1328–1371 cmy1, respectively. The values for the
asymmetric stretching vibration correspond to that of a
dimeric allyl palladium compound containing two bridg-
y1
Ž
ing diphenylphosphino butyrate groups 1617 cm
,
.
Ž
nujol , the symmetric vibration of this compound 1289
cmy1, nujol being at lower energy than those of the
.
w
x
complexes 1a–d 26 . All the frequencies of 1a–d differ
considerably from those of arylnickel compounds with a
bidentake k 2-bonded pyridine carboxylate ligand
Ž
.
right side of the equation Scheme 2 . This behaviour
holds the promise of good catalytic activity of the
complexes 1c and 1d in C–C bond formation reactions
according to the concept of hemilability. An investiga-
tion utilizing the new complexes as catalyst precursors
in olefin oligomerisation and co-oligomerisation is
y1
Ž
. w x
23 .
1662–1668 cm
2.3. 31P NMR spectroscopic characterisation of com-
plexes 1a–d
Our original intention with the substitution of chlo-
presently underway.
31
w
Ž
.Ž .2 x
Ž
.
ride in trans- PdCl Ph PPh3 by the negatively
The P resonances of 1c and 1d Fig. 2 consist of
three and two peaks, respectively, and can be attributed
to the existence of additional geometric isomers. Indeed,
for complex 1a two such isomers were crystallised and
structurally identified by X-ray analysis hinting at a
sterically hindered rotation within the S–O ligand in
charged oxygen atom in potentially bidentate ligands,
was to establish whether the neutral sulphur atoms of
these ligands would also subsequently replace one PPh3
Ž
.
group in the reactant complex Scheme 2 . Such a
reaction should become thermodynamically more likely
with increasing basicity of the sulphur atom. Therefore,
a complete series of ligands was used in which an
increasing inductive effect of the substituents, R, on the
sulphur causes an increased electron density and thus an
increased basic strength in the order Me-Et-i-Pr-t-
Bu.
1
compounds 1a–d.
2.4. Determination of thermodynamic parameters for 1c
and 2c
By using 31 P NMR spectral data of 1c at different
temperatures, the values for the equilibrium constant,
K, and for the rate constant, k, applicable to the equa-
In the solid state Pd–S bond formation was absent.
In solution, however, the equilibrium in Scheme 2 was

(
)
W.H. Meyer et al.rJournal of Organometallic Chemistry 553 1998 83–90
85
Fig. 1. Schakal drawing of 1b showing the numbering scheme adopted.
Scheme 2. Possible equilibrium between Pd complexes with a non-chelating and a chelating ligand.

(
)
86
W.H. Meyer et al.rJournal of Organometallic Chemistry 553 1998 83–90
y3
Table 1
Ž
.
molrl for compound 1d under the
smaller 1=10
Equilibria between type 1 and type 2 complexes. 31 P NMR chemical
same conditions.
shifts in ppm
Solvent Complex type
a
b
c
d
2.5. Crystal and molecular structure of 1b
C6 D6
1
2
1
2
22.2 22.1 22.0
y
22.4 22.7
24.8
y
y
Selected bond lengths and angles are given in Table
3 and fractional atomic coordinates in Table 4. Fig. 1
shows the molecular structure and the adopted number-
ing scheme. Compound 1b crystallises in the mono-
clinic system with unit cell dimensions as given in
Table 5 which also contains other crystallographic data.
The complex shows a slightly distorted square planar
conformation around the central palladium. The devia-
tions of the Pd and the four surrounding ligand atoms
which are bonded to the Pd centre, from their least-
CDCl3
21.5 21.4 21.5 21.7 21.9 21.7 22.4
26.6 25.2
y
y
tion in Scheme 2 were determined in chloroform-d1
solution. The latter was calculated by determining the
half widths, h, of the signals for 1c, 2c and PPh3 and
Ž
.
applying the formula ksp hyh0 for slow exchange
w
x
reactions 27 . The value h0 defines the half width with
no exchange occurring and was estimated at 1.5 Hz
from the spectrum of 1b. The approximate equilibrium
constants, K, were calculated according to K s
˚
Ž
.
squares plane molecular plane are less than 0.1 A. The
phenyl ring and the carboxylate group of the oxygen-
donor ligand are aligned in a plane with deviations of
w
xw
x w x
2c PPh3 r 1c starting with a known amount of 1c and
˚
less than 0.07 A. The phenyl group attached to the
chloroform-d1. The equilibrium concentrations of the
various compounds participating in the reaction were
determined by integration, keeping in mind that the
signal of 1c integrates for two P atoms while that of 2c
refers to only one.
central atom is orientated rectangularly to the molecular
plane. The ligand plane, however, forms an angle of 638
with the latter.
˚
Ž .
Ž .
2.0024 2 A Pd–C bond lengths in 1b compare well
The 2.3441 2 and 2.3378 2 A Pd–P and the
˚
Ž .
with those in trans- PdBr o-tolyl PPh3
The standard free energy of reaction, DG0, was
calculated according to DG0 syRT ln K by plotting
ln K against 1rT. The activation energy, EA, followed
˚
Ž .
w
Ž
.Ž
.
x w
2.322 2 A,
2
˚
˚
Ž .
Ž . x w
x
2.319 2 A, 1.991 8 A 28 , a compound similar to the
starting material. Thus, no major change is introduced
by substituting the halide for a carboxylate ligand. Only
a few examples of Pd coordinated by one oxygen of a
carboxylate moiety are found in the literature. The
Ž
.
from an Arrhenius plot ln K against 1rT . Table 2
contains the results and Fig. 3 shows the linear Arrhe-
nius plots.
Due to the influence of the entropy term TDS0
Scheme 2 , the equilibrium is shifted to the right at
w
Ž
.Ž
.x w x Ž
Pd–O distances in PdMe mpyca PPh3 25 mpycaH
Ž
.
.
s6-methylpyridine-2-carboxylic acid with a chelating
higher temperatures increasing the equilibrium con-
stants. The value for DG0 was determined in the stan-
dard way to be 22 kJrmol. EA is of the order of 25–30
kJrmol.
N–O ligand where the oxygen is in trans position to
˚
x
w
Ž .
the methyl group 2.121 4 A , and in a dimeric palla-
dium allyl complex with two bridging aceta-
˚
˚
x
w
Ž . x w
x
todiphenylphosphine groups 2.124 6 A 26 , corre-
Substitution occurs to a larger extent for 1d than for
1c. The constants, K, at room temperature in chloro-
form-d1 solution were calculated as 20=10y3 and
4=10y3 molrl respectively. In benzene-d6, K is
w
Ž .
spond well to that of 1b 2.1315 2 A . Thus, the
complex 1b does not show unusual structural features.
w
x
w x
Pd compounds bearing two trans 29–31 or cis 32
coordinated carboxylate groups have Pd–O bond dis-
˚
tances between 2.00 and 2.08 A. An increased bond
Table 2
Determination of equilibrium and rate constants
y4
w x
T K
w
x
w
x
K 10 molrl k lrs
1c
2c
18.2
41.2
87.3
PPh3
243.15
258.15
273.15
288.15
303.15
6.7
10.9
18.0
34.3
54.3
9.7
23.9
35.5
27.0
52.5
98.7
92.7
196.3
153.0
293.1
181.3
309.2
Results
DG0 kJrmol
21.8"1.2
EA kJrmol EA kJrmol EA kJrmol
30.2"2.5 28.3"0.5 25.1"0.5
w
x
w
x
w
x
w
x
31
Ž
.
Ž
.
Ž
.
Fig. 2. P NMR spectra of 1c top and 1d bottom in C6 D6 left
Ž
.
and CDCl3 right .

(
)
W.H. Meyer et al.rJournal of Organometallic Chemistry 553 1998 83–90
87
Fig. 3. Arrhenius plots for 1c; signal basis: 1c: B, 2c: v, PPh3: '.
length for 1b is to be expected due to a larger trans
effect compared to the carboxylate ligand in the trans-
dicarboxylate Pd complexes.
It was found that compound 1a crystallises in two
modifications. They show different molecular structures
Ž
.
to be reported elsewhere in which the oxygen-donor
w
Ž
Ž
.
The geometry of 1b is similar to that of trans- Ni o-
ligand moiety is turned 1808 around the C carboxyl –
C phenyl bond. Compound 1b shows the same molecu-
1
.Ž .2 x Ž
.Ž
Ž
.
tolyl thpca-k -O PPh3 thpcaH s thiophene-2-
.
w x
carboxylic acid 33 but the bond distances from the Ni
lar structure as one of these two modifications.
˚
metal centre to the adjacent atoms are about 0.1 A
shorter.
3. Experimental
Table 3
3.1. General
˚
w x
w x
Selected bond lengths A and angles 8 for 1b
Ž
.
.
.
Ž .
2.1315 2
Pd–P1
Pd–P2
O41–C41
2.3441 2
Pd–O41
Pd–C31
O42–C41
All reactions and manipulations except the syntheses
of ligands and thallium salts were carried out under
nitrogen atmosphere using standard Schlenk techniques.
Solvents except methanol were dried and purified by
standard methods and freshly distilled before use. Other
reagents were used without further purification.
Ž
Ž .
2.0024 2
2.3378 2
Ž
Ž .
1.2280 1
1.2870 1
Ž .
Ž .
88.71 1
P1–Pd–C31
P2–Pd–O41
P2–Pd–P1
Pd–O41–C41
O41–C41–O42
Pd–P1–C111
Pd–P1–C121
Pd–P1–C131
90.36 0
93.81 1
P1–Pd–O41
P2–Pd–C31
O41–Pd–C31
Pd–C31–C32
Pd–C31–C36
Pd–P2–C211
Pd–P2–C221
Pd–P2–C231
Ž .
Ž .
87.14 0
Ž .
Ž .
171.47 0
177.48 0
Ž .
Ž .
123.43 0
116.28 1
124.45 1
124.02 0
Ž .
Ž .
118.21 0
w
Ž
.Ž
.
x w
x
The complex trans- PdCl Ph PPh3
34 and the
2
Ž .
Ž .
116.75 0
w
x
ligands 2-MeS-C6 H4-COOH 35 and 2-RS-C6 H4-
Ž .
Ž .
112.75 0
111.87 0
Ž .
Ž
.
w
x
COOH RsEt, i-Pr, t-Bu 36,37 were prepared ac-
Ž .
113.25 1
108.25 1
cording to literature methods.

(
)
88
W.H. Meyer et al.rJournal of Organometallic Chemistry 553 1998 83–90
Ž
.
Table 4
Table 4 continued
Fractional coordinates and equivalent isotropic displacement parame-
ters for atoms of 1b
2
˚
Ueq rA
Atom
x
y
z
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
H116 y0.0932 26
0.7251 30
0.2697 25
0.069 13
2
˚
Atom
x
y
z
Ueq rA
Ž
Ž
Ž
Ž
H122 y0.2622 32
0.4804 31
0.3056 31
0.082 15
Ž
.
Ž . Ž .
Ž
.
Ž
Ž
Ž
Ž
Pd
P1
P2
y0.003173 14 0.48080 2 0.267937 14 0.03823 14
H123 y0.3028 35
0.3756 38
0.3717 31
0.113 18
Ž . Ž . Ž . Ž .
Ž
Ž
Ž
Ž
y0.11351 5 0.53374 6 0.29400 5 0.0402 2
H124 y0.1998 30
0.2786 37
0.4675 29
0.092 15
Ž .
0.10911 5
Ž .
Ž .
Ž .
0.0393 2
Ž
Ž
Ž
Ž
0.43457 6 0.24269 5
0.3474 2
0.2950 2
0.24536 7 0.13754 7
0.6416 2
0.6437 3
0.7254 3
0.8062 3
0.8058 3
0.7247 3
0.4499 2
0.4419 3
0.3774 4
0.3243 3
0.3319 3
0.3954 3
0.5443 2
0.6018 3
0.6039 3
0.5489 3
0.4924 3
0.4906 3
0.5073 2
0.4883 3
H125 y0.0546 36
0.2982 39
0.4956 32
0.118 19
Ž
.
Ž .
Ž
.
Ž .
0.0474 6
Ž
Ž
Ž
Ž
O41 y0.05631 14
O42
S
0.24940 14
0.3511 2
H126 y0.0293 26
0.4001 29
0.4137 23
0.068 12
Ž .
Ž .
Ž .
Ž .
0.0685 7
Ž
Ž
Ž
Ž
0.0567 2
H132 y0.2698 24
0.6364 27
0.2276 24
0.063 11
Ž .
Ž .
Ž .
Ž .
0.0675 3
Ž
Ž
Ž
Ž
y0.17980 7
H133 y0.3793 25
0.6404 28
0.1052 22
0.056 11
Ž .
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
C111 y0.1123 2
0.3459 2
0.4182 2
0.4557 3
0.4210 3
0.3497 3
0.3127 3
0.3504 2
0.3410 3
0.3867 3
0.4408 3
0.4525 3
0.4070 2
0.1976 2
0.1856 2
0.1121 3
0.0499 3
0.0455 8
H134 y0.3867 26
0.5517 30
0.0017 26
0.069 12
Ž .
Ž .
Ž .
Ž
.
.
.
.
.
Ž
Ž
Ž
Ž
C112 y0.1201 3
0.0581 10
H135 y0.2854 27
0.4559 31
0.0153 28
0.072 13
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C113 y0.1222 3
0.0764 13
H136 y0.1707 25
0.4548 28
0.1380 22
0.052 11
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C114 y0.1164 3
0.0782 14
H212
H213
H214
H215
H216
0.0695 22
0.4374 26
0.0720 20
0.049 10
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C115 y0.1075 3
0.0778 14
0.0995 37
0.5231 35
y0.0156 38
0.111 20
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C116 y0.1049 3
0.0649 11
0.1749 31
0.6578 37
0.0354 30
0.092 16
Ž .
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
C121 y0.1445 2
0.0433 8
0.2285 23
0.6791 27
0.1695 21
0.043 11
Ž .
Ž .
Ž .
Ž
.
.
.
.
.
Ž
Ž
Ž
Ž
C122 y0.2244 3
0.0601 10
0.2078 23
0.5966 26
0.2561 23
0.055 11
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C123 y0.2446 3
0.0756 13
H222 y0.0219 23
0.3462 26
0.1212 21
0.049 10
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C124 y0.1854 3
0.0763 14
H223 y0.0481 26
0.2121 26
0.0519 24
0.057 11
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C125 y0.1050 3
0.0734 12
H224
H225
H226
H232
H233
H234
H235
H236
H32
H33
H34
H35
H36
0.0456 24
0.1036 31
0.0840 23
0.069 12
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C126 y0.0838 3
0.0590 10
0.1694 27
0.1303 30
0.1873 25
0.071 13
Ž .
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž .
C131 y0.2041 2
0.0439 8
0.2042 22
0.2659 22
0.2554 20
0.042 9
Ž .
C132 y0.2700 2
Ž .
Ž .
Ž
.
.
.
.
Ž
Ž
Ž
Ž
.
.
.
.
0.0582 10
0.2833 22
0.4236 26
0.2875 22
0.051 11
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C133 y0.3384 3
0.0694 12
0.3995 32
0.4087 34
0.3944 28
0.090 16
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C134 y0.3421 3
0.0659 11
0.4015 26
0.4260 29
0.5201 25
0.073 12
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C135 y0.2765 3
0.0609 3
0.1332 2
0.1741 2
0.0922 2
0.0625 11
0.2789 25
0.4435 31
0.5265 26
0.067 12
Ž .
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž .
C136 y0.2083 3
0.0526 9
0.1543 22
0.4418 24
0.4136 19
0.043 9
Ž .
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
.
C211
C212
C213
C214
C215
C216
C221
C222
0.1353 2
0.1037 3
0.1205 3
0.1689 3
0.2003 3
0.1843 3
0.0934 2
0.0166 2
0.0451 8
0.1139 25
0.6259 28
0.3900 25
0.069 12
Ž .
Ž .
Ž .
Ž
.
.
.
.
.
Ž
Ž
Ž
Ž
0.0548 10
0.1571 29
0.7689 32
0.3771 28
0.082 14
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
0.5449 4
Ž .
0.0404 3
Ž .
0.0711 12
0.0941 28
0.8496 35
0.2601 27
0.084 14
Ž .
Ž
Ž
Ž
Ž
Ž
0.6205 4
0.0694 3
0.0743 14
0.0037 31
0.7756 35
0.1400 30
0.092 16
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
0.6390 3
0.5843 3
0.1494 4
0.2032 3
0.0765 15
y0.0418 24
0.6302 26
0.1418 24
0.064 11
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
0.0590 10
H44
H45
H46
H47
y0.1715 28
0.0543 34
0.1362 27
0.071 14
Ž .
Ž .
Ž .
Ž .
Ž
Ž
.
.
Ž
Ž
0.3222 2
Ž .
0.1935 2
Ž .
0.0418 8
y0.0837 28
y0.0635 37
0.2032 28
0.090 14
Ž .
Ž .
Ž
Ž
Ž
Ž
0.3050 3
0.1318 2
0.0497 9
0.0284 42
y0.0133 41
0.3254 42
0.115 22
Ž .
Ž .
Ž .
Ž
.
.
.
.
Ž
Ž
.
.
.
.
.
.
Ž
Ž
C223 y0.0003 3
0.2231 3
0.1584 3
0.0897 3
0.1092 3
0.0613 10
0.0572 31
0.1225 37
0.3593 30
0.094 18
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
C224
C225
C226
C231
C232
C233
C234
C235
C236
C31
C32
C33
C34
C35
C36
C41
C42
C43
0.0591 3
0.1363 3
0.1534 3
0.2056 2
0.2821 2
0.3543 3
0.3512 3
0.2763 3
0.2044 2
0.0352 2
0.0919 3
0.1140 3
0.0816 3
0.0257 3
0.0027 3
0.0734 12
H511 y0.2983 46
0.1435 51
0.0901 41
0.164 28
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
Ž
0.1744 3
Ž .
0.1703 3
Ž .
0.0768 14
H512 y0.2216 34
0.1283 39
0.0412 32
0.119 18
Ž .
Ž
Ž
Ž
Ž
Ž
0.2556 3
0.2130 2
0.0580 10
H521 y0.3759 38
0.1930 39
y0.0415 35
0.125 19
Ž .
Ž .
Ž .
Ž .
Ž
Ž
Ž
Ž
0.4296 2
0.4223 3
0.3336 2
0.3308 3
0.0435 8
H522 y0.2951 54
0.2643 53
y0.0329 46
0.164 31
Ž .
Ž .
Ž .
Ž
.
.
.
.
Ž
Ž
Ž
Ž
0.0578 10
H523 y0.3578 78
0.2861 82
0.0329 72
0.312 62
Ž .
Ž .
Ž .
Ž
0.4202 3
Ž .
0.4006 3
Ž .
0.0704 12
Ž .
Ž
0.4261 3
0.4740 3
0.0709 12
Ž .
Ž .
Ž .
Ž .
Ž
0.0662 11
0.4332 3
0.4353 3
0.6096 2
0.6533 3
0.7436 3
0.7911 3
0.7488 3
0.6582 3
0.2828 3
0.1863 2
0.1625 3
0.0680 3
0.0021 4
0.0259 4
0.1164 3
0.1772 4
0.4782 3
0.4094 2
Ž .
0.2681 2
Ž .
0.3370 3
0.3313 4
0.2605 4
0.1926 4
0.1961 3
0.2928 2
0.2661 2
0.1980 2
0.1792 4
0.2239 5
Ž .
0.2898 6
0.3116 4
0.0636 4
Ž .
Ž .
Ž .
0.0507 9
Ž .
0.0457 8
13
Ž
Ä1
4
H NMR
NMR spectra 1H NMR at 300 MHz,
at 75 MHz with Me4Si as internal standard and 31
NMR at 121 MHz with 85% H3PO4 as external stan-
C
Ž .
Ž .
Ä1
4
H
Ž .
Ž .
Ž
.
.
P
0.0583 10
Ž .
Ž .
Ž .
Ž
0.0803 14
Ž .
0.081 2
Ž .
Ž .
Ž .
.
dard were recorded on a Varian Gemini 2000 NMR
Ž .
Ž .
Ž .
Ž
.
.
0.0724 13
spectrometer. For IR spectra 4000 to 600 cmy1, resolu-
Ž
Ž .
Ž .
Ž .
Ž
0.0575 10
tion 4 cmy1 a Perkin-Elmer 841 spectrophotometer
.
Ž .
Ž .
Ž .
Ž .
y0.0096 2
0.0508 9
Ž .
0.0543 9
Ž .
Ž .
Ž .
was used. Elemental analyses were carried out by the
Division of Energy Technology, CSIR, Pretoria.
y0.0385 3
Ž .
Ž .
Ž .
Ž
.
.
y0.1105 3
0.0576 10
Ž .
Ž .
Ž .
Ž
0.0804 14
C44
C45
C46
C47
C51
C52
y0.1245 4
Ž .
y0.0704 6
Ž .
Ž .
Ž .
0.100 2
Ž .
0.101 2
3.2. Crystal structure determinations
Ž .
Ž .
y0.0026 6
Ž .
Ž .
Ž .
Ž .
Ž
.
0.0140 4
0.0778 13
Ž .
Ž .
Ž .
Crystals of 1b suitable for X-ray crystallographic
analysis were obtained by crystallisation from
THFrpentane. The Siemens SMART CCD system was
used for X-ray diffraction data collection at room tem-
perature, using graphite monochromated MoKa radia-
tion. Empirical absorption corrections were applied by
y0.2606 4
0.097 2
Ž .
0.116 2
Ž .
y0.3235 5
Ž .
0.2408 6
0.5908 26 0.4356 20
0.7184 32 0.5097 30
0.8579 33 0.4437 26
Ž .
0.0020 5
Ž
.
.
.
.
Ž
.
Ž
.
.
.
.
Ž
.
.
.
.
H112 y0.1278 21
0.045 10
Ž
Ž
.
Ž
Ž
0.090 15
H113 y0.1212 29
Ž
Ž
Ž
.
Ž
Ž
Ž
0.077 14
H114 y0.1214 27
Ž
.
Ž
0.078 14
H115 y0.1089 27
0.8571 33 0.3250 26

(
)
W.H. Meyer et al.rJournal of Organometallic Chemistry 553 1998 83–90
89
Table 5
lection parameters. All data including anisotropic dis-
placement parameters are available from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB21EZ, UK.
Crystal and refinement data and data collection parameters for 1b
Crystal data
Formula
Formula weight g mol
Colour, habit
C51H44O2 P2 SPd
889.34
Light yellow, regular prism
0.18=0.18=0.25
0.592
y1
Ž
.
3
Ž
.
Crystal dimensions mm
[
(
3.3. Preparation of complexes trans- Pd OOC-C6 H4-2-
y1
Ž
.
m mm
1
)
(
)2 ]
SR-k -O Ph PPh3
Crystal system
Monoclinic
Space group
P21 ra
17.864 1
˚
Ž .
a A
Ž .
Ž
2-RS-C6 H4-COOH 0.63 mmol, RsMe, Et, i-Pr,
˚
Ž .
b A
Ž .
14.610 1
.
t-Bu was dissolved in 30 ml methanol. The stoichio-
metric amount of Tl2CO3 148 mg, 0.315 mmol was
added and the mixture refluxed for 30 min. When
necessary, water was added up to 10 ml during heat-
ing until a clear solution was obtained. The solvent was
removed in vacuo and the remaining thallium salt dried
for another 30 min and subsequently manipulated under
˚
Ž .
c A
Ž .
18.228 1
Ž .
Ž
.
Ž .
b 8
114.849 1
3
˚
Ž
.
Ž .
4317.0 5
V A
Ž
.
Z
4
y3
Ž
. Ž
.
D calc. g cm
1.368
Refinement data
Refinement method
Number of parameters
R F , observed reflections
Full-matrix least-squares on F2
w
Ž
.Ž .2 x Ž
nitrogen. A solution of trans- PdCl Ph PPh3 260
690
.
mg, 0.35 mmol in 15 ml tetrahydrofuran was added to
the 80% excess of 2-SR-C6 H4-COOTl and stirred for
three days at room temperature. Precipitated TlCl was
filtered off using Celite. The volume of the colourless to
orange solutions was reduced in vacuo to approximately
3 ml. The crystallisation of the product at room temper-
ature was initiated by the careful addition of a layer of
pentane. Yields were in the range of 40 to 50% without
attempting further crystallisation from the mother liq-
Ž
.
0.0331
0.1193
0.991
2
Ž
.
wR F , all reflections
Ž .
Goodness of fit S , all
Drs max
Drs mean
Ž
Ž
.
Ž
.
-0.2 for y of H523
.
0.009
y3
˚
Ž
.
Dr e A , min, max
y0.42, 0.23
Data collection parameters
Diffractometer
Siemens SMART CCD system
Univ. of the Witwatersrand,
Johannesburg
Ž
.
uid.
˚
Ž
.
Radiation
Monochromator
Temperature K
F 000
Theta range for
data collection
Index ranges
MoKa ls0.71073 A
1
w
Ž
Ž
.
.
Ž
.
x
trans- Pd OOC- C6 H 4 -2-SMe-k -O Ph PPh3
colourless crystals, H NMR d chloroform-d1, 293 K :
2.10 s, 3H, SCH3 , 6.3 m, 2H, Pd-C6 H5 , 6.5 m, 1H,
Pd-C6 H5 4-H , 6.6 m, 2H, Pd-C6 H5 , 6.65–7.6 m,
34H, OOC- C6 H4 , P C6 H5
form-d1, 293 K : 15.9, 121.9, 122.5, 127.1, 127.9,
:
2
Graphite
1
Ž
.
Ž .
Ž .
293 2
Ž
.
Ž
.
Ž
.
Ž
1832
1.868 to 23.278
.
Ž
.
Ž
13
Ž
.
Ž
. .
Ž
.
C NMR d chloro-
3
y19FhF15, y16FkF16,
y20FlF20
15998
.
128.5, 128.6, 129.6, 130.7, 131.1, 132.1, 132.2, 134.5,
Reflections collected
R internal
Independent reflections
Independent observed
137.3, 147.4, 171.1. 31 P H NMR d chloroform-d1,
Ä1
4
Ž
Ž
.
0.022
6126
5417
293 K : 21.5. 31 P H NMR d benzene-d6, 293 K :
.
Ä1
Ž
4
Ž
.
y1
Ž
.
.
Ž
.
22.2. IR KBr : yas CO : 1608 cm , ys CO : 1348
Ž .
reflections with I)4s I
cmy1
C50 H42O2 P2 SPd. Calc.:C, 68.6; H, 4.8; S, 3.7%.
. Anal. Found: C, 68.4; H, 4.7; S, 3.9.
1
w
Ž
Ž
.
.
Ž
.
x
trans- Pd OOC- C6 H 4 -2-SEt-k -O Ph PPh3
light-yellow crystals, H NMR d chloroform-d1, 293
:
2
1
Ž
using the Siemens utility program SADABS for CCD
detectors. The structure was solved using SHELXS-86
38 and refined with SHELXL-93 39 . All non-hydro-
3
.
Ž
.
Ž
K : 1.17 tr, 3H, Js7.1 Hz, SCH2CH3 , 2.6 br, 2H,
w
x
w x
.
Ž
.
Ž
SCH2CH3 , 6.2–6.4 m, 2H, Pd-C6 H5 , 6.4–6.6 m,
.
Ž
.
gen atoms were refined anisotropically. All hydrogen
atoms were found and refined with isotropic displace-
ment parameters. Final values for the residuals of Rs
1H, Pd-C6 H5 4-H , 6.6–6.7 m, 2H, Pd-C6 H5 , 6.8–7.7
m, 34H, OOC- C6 H4 , P C6 H5
roform-d1, 293 K : 13.2, 26.0, 121.9, 127.1, 127.9,
13
Ž
Ž
.
Ž
. .
Ž
.
C NMR d chlo-
3
.
Ž
0.0331, wRs0.1193 and Ss0.991 were obtained wR
128.5, 129.6, 130.7, 130.9, 131.2, 134.5, 137.3, 147.3,
171.1. 31 P H NMR d chloroform-d1, 293 K : 21.4.
2
2
c
2
2
2
1r2
2
Ä1
4
Ž
.
w
Ž
.
Ž
.
x
w
2Ž
.
, ws1r s F0 q
s Sw F0 yF rSw F0
31
2
2
2
Ä1
4 Ž . Ž .
H NMR d benzene-d6, 293 K : 22.1. IR KBr :
Ž
.
x
Ž
.
0.10 P
with Ps F0 q2F r3, SsGoodness of
P
Ž
c
2
2
c
2
1r2
yas CO : 1602 cm , ys CO : 1353 cmy1. Anal. Found:
y1
w
Ž
.
Ž
.
x
.
Ž
.
fits Sw F0 yF r nyp
with nsnumber of
.
reflections and psnumber of parameters . Important
bond lengths and angles of 1b, the fractional coordi-
nates and equivalent isotropic displacement parameters
of all atoms are given in Tables 3 and 4. Table 5
contains crystal data, refinement data and the data col-
C, 68.9; H, 5.1; S, 3.7. C51H44O2 P2 SPd. Calc.: C, 68.9;
H, 5.0; S, 3.6%.
1
w
Ž
Ž
.
.
Ž
.
x
trans- Pd OOC- C6 H 4 -2-Si-Pr-k -O Ph PPh3
colourless crystals, H NMR d benzene-d6, 293 K :
1.13 d, 6H, Js5.7 Hz, SCH CH3 , 3.16 m, 1H,
:
2
1
Ž
.
3
Ž
Ž
. .
Ž
2

(
)
90
W.H. Meyer et al.rJournal of Organometallic Chemistry 553 1998 83–90
w x
9
B. Demerseman, R. Le Lagadec, B. Guilbert, C. Renourd, P.
Ž
. .
Ž
.
Ž
SCH CH3 , 6.3–6.5 m, 2H, Pd-C6 H5 , 6.5–6.6 m,
2
Ž
.
Crochet, P.H. Dixneuf, Organometallics 13 1994 2269.
.
Ž
1H, Pd-C6 H5 6.6–8.2 m, 36H, Pd-C6 H5, OOC-
C6 H4 , P C6 H5
w
w
w
x
13
10 G.J.P. Britovsek, W. Keim, S. Mecking, D. Sainz, T. Wagner, J.
Ž
.
Ž
. .
Ž .
.
C NMR d benzene-d6, 293 K :
3
Ž
.
Chem. Soc. Chem. Commun. 1993 1632.
22.8, 33.8, 122.1, 129.8, 130.8, 130.6, 130.9, 131.2,
x
11 E. Lindner, Q. Wang, H.A. Mayer, R. Fanzi, M. Steimann,
131.5, 132.1, 132.3, 132.5, 135.1, 138.1, 141.4. 31 P
Ž
.
Organometallics 12 1993 1865.
31
Ä1
4
Ž
.
Ä1
4
Ž
x
12 H. Werner, A. Stark, M. Schulz, J. Wolf, Organometallics 11
H NMR d benzene-d6, 293 K : 22.0.
P H NMR
Ž
.
1992 1126.
Ž
Ž
.
.
d chloroform-d1, 293 K : 21.5, 21.7, 21.9. IR KBr :
w
w
w
x
Ž
.
13 A. Bader, E. Lindner, Coord. Chem. Rev. 108 1991 27.
yas CO : 1608 cm , ys CO : 1328 cmy1. Anal. Found:
y1
.
Ž
.
x
Ž
.
14 E. Lindner, B. Karle, Chem. Ber. 123 1990 1469.
C, 68.9; H, 5.0; S, 3.4. C52 H46O2 P2 SPd. Calc.: C, 69.1;
H, 5.1; S, 3.5%.
trans- Pd OOC- C6 H4 -2-St-Bu-k -O Ph PPh3
light orange crystals, H NMR d benzene-d6, 293 K :
1.1 s, 7.4H, SC CH3 3, S not coordinated , 1.2–1.3 m,
br, 1.6H, SC CH3 3, S coordinated , 6.2–7.9 m, 39H,
Pd-C6 H5, OOC- C6 H4 , P C6 H5
zene-d6, 293 K : 31.4, 45.0, 121.9, 126.5, 126.8, 127.1,
x
15 A.G. Abatjoglou, A.M. Harrison, R.W. Wegman, J. Chem. Soc.
Ž
.
Chem. Commun. 1987 1891.
1
w
x
16 R.E. Rulke, V.E. Kaasjager, P. Wehman, C.J. Elsevier,
w
Ž
Ž
.
.
Ž
.
x
¨
:
2
1
P.W.N.M. van Leeuwen, K. Vrieze, J. Fraanje, K. Goubitz, A.L.
Ž
.
Ž
.
Spek, Organometallics 15 1996 3022.
Ž
Ž
.
.
Ž
w
w
w
x
Ž
.
17 A. Pfaltz, P. von Mall, Angew. Chem. 105 1993 614.
Ž
.
.
.
Ž
x
Ž
.
18 C. Abu-Gnim, I. Amer, J. Mol. Catal. 85 1993 L275.
13
Ž
.
Ž
. .
Ž
C NMR d ben-
x
19 G.P.C.M. Dekker, A. Buijs, C.J. Elsevier, K. Vrieze, P.W.N.M.
3
van Leeuwen, W.J.J. Smeets, A.L. Spek, Y.F. Wang, C.H.
.
Ž
.
Stam, Organometallics 11 1992 1937.
129.9, 130.6, 130.7, 131.2, 131.5, 131.8, 132.3, 132.4,
w
x
31
20 M. Bressan, C. Bonuzzi, F. Morandini, A. Morvillo, Inorg.
Ä1
4 Ž
135.3, 136.2, 137.8.
P
H NMR d benzene-d6, 293
Ž
.
Chim. Acta 182 1991 153.
K : 22.4, 22.7. 31 P H NMR d chloroform-d1, 293
.
.
Ä1
4
Ž
w
w
x
Ž
.
21 H. Maas, Ph.D. thesis, Aachen 1996 .
y1
Ž
.
Ž
.
Ž
.
K : 21.7, 22.4. IR KBr : yas CO : 1595 cm , ys CO :
1371 cmy1. Anal. Found: C, 69.7; H, 5.1; S, 3.2.
C53 H48O2 P2 SPd. Calc.: C, 69.4; H, 5.3; S, 3.5%.
x
22 J.R. Dilworth, A.J. Hutson, J.S. Lewis, J.R. Miller, Y. Zheng,
Ž
.
Q. Chen, J. Zubieta, J. Chem. Soc. Dalton Trans. 1996 1093.
w
w
w
x
23 S.Y. Desjardins, K.J. Cavell, H. Jin, B.W. Skelton, A.H. White,
Ž
.
J. Organomet. Chem. 515 1996 233.
x
24 G.J.P. Britovsek, K.J. Cavell, W. Keim, J. Mol. Catal. A: Chem.
Ž
.
110 1996 77.
x
25 J.L. Hoare, K.J. Cavell, R. Hecker, B.W. Skelton, A.H. White,
Acknowledgements
Ž
.
J. Chem. Soc. Dalton Trans. 1996 2197.
w
w
x
Ž
.
26 S. Mecking, Ph. D. thesis, Aachen 1994 .
x
27 R.J. Abraham, J. Fischer, P. Loftus, Introduction to NMR
We thank the FRD for financial support. The mea-
surement of NMR spectra by Dr. Linda van der Merwe
and by Mr. Ian Vorster is gratefully acknowledged.
spectroscopy, Wiley, Chichester, 1988.
w
w
w
w
x
28 R.J. Cross, A.R. Kennedy, K.W. Muir, Acta Crystallogr. C 51
Ž
.
1995 208.
x
29 A. Behr, R. He, K.-D. Juszak, C. Kruger, Y.-H. Tsay, Chem.
Ž
.
Ber. 119 1986 991.
x
30 D.P. Bancroft, F.A. Cotton, M. Verbruggen, Acta Crystallogr. C
Ž
.
45 1989 1289.
References
x
31 N.N. Lyalina, S.V. Dargina, A.N. Sobolev, T.M. Buslaeva, I.P.
Ž
.
Romm, Koord. Khim. 19 1993 57.
w x
Ž
.
1
w x
2
S. Mecking, W. Keim, Organometallics 15 1996 2650.
E. Lindner, B. Keppler, R. Fawzi, M. Steimann, Chem. Ber. 129
1996 1103.
S.J. Chadwell, S.J. Coles, P.G. Edwards, M.B. Hursthouse, J.
Chem. Soc. Dalton Trans. 1996 1105.
S.J. Chadwell, S.J. Coles, P.G. Edwards, M.B. Hursthouse, J.
Chem. Soc. Dalton Trans. 1995 3551.
W. Keim, H. Maas, S. Mecking, Z. Naturforschung B: Chem.
Sci. 50 1995 430.
E. Lindner, M. Geprags, K. Gierling, R. Fawzi, M. Steimann,
Inorg. Chem. 34 1995 6106.
W. Keim, R.P. Schulz, J. Mol. Catal. 92 1994 21.
B. Demerseman, C. Renourd, R. Le Lagadec, M. Gonzalez, P.
Crochet, P.H. Dixneuf, J. Organomet. Chem. 471 1994 229.
w
w
w
x
Ž
.
32 D.J. Wink, Acta Crystallogr. C 46 1990 56.
x
Ž
.
33 R. Brull, Ph.D. thesis, Aachen 1995 .
¨
Ž
.
¨
x
34 W.A. Herrmann, C. Broßner, T. Priermeier, K. Ofele, J.
w x
3
Ž
.
Organomet. Chem. 481 1994 97.
Ž
.
w
x
Ž
.
35 Deutsche Chemische Gesellschaft Ed. , Beilsteins Handbuch
w x
4
der Organischen Chemie, Vol. 10, Springer, Berlin, Gottingen,
¨
Ž
.
Ž
.
Heidelberg, 4th edn. 1956 p. 125.
w x
5
w
w
x
36 P. Cogolli, F. Maiolo, L. Testaferri, M. Tingoli, M. Tiecco, J.
Ž
.
Ž
.
Org. Chem. 44 1979 2642.
w x
6
x
¨
37 L. Testaferri, M. Tiecco, M. Tingoli, D. Chianelli, M. Mon-
Ž
.
Ž
.
tanucci, Synthesis 1983 751.
w x
Ž
.
7
w
w
x
Ž
.
38 G.M. Sheldrick, Acta Crystallogr. A 46 1990 467.
w x
8
x
39 G.M. Sheldrick, Program for the Refinements of Structures,
Ž
.
Ž
.
University of Gottingen 1993 .
¨