Atropisomerism in palladacycles derived from the chloropalladation of heterosubstituted alkynes

Article abstract of DOI:10.1016/S0020-1693(03)00011-2

The chloropalladation of 2-substituted phenyl N,N-propargylamines, Y-2-C₆H₄C≡CCH₂NMe₂ (1a, Y=H; 2a, Y=CF₃; 3a, Y=OMe; 4a, Y=SMe and 5a, Y=NH₂) affords palladacycles in different ratios of isomers (geometric and atropisomers). In solution, the parent alkyne (Y=H) and the CF₃ substituted derivative generate a mixture of cisoid and transoid chloro-bridged dimer palladacycles of the type {Pd[κ¹-C, κ¹-N-C=(Y-2-C ₆H₄)C(Cl)CH₂NMe₂](μ-Cl)} ₂. Moreover, in the case of Y=CF₃ palladacyclic derivative each of the geometric isomers comprises a mixture of two diastereoisomers due to the restricted rotation of the C(vinyl)-C(aryl) sigma bond (atropisomers). Palladacycles 1a (Y=H) and 2a (Y=CF₃) crystallize as the single transoid and cisoid-anti isomer, respectively. The OMe substituted alkyne yields a similar dimeric compound that crystallizes as a single cisoid-anti isomer. In solution this dimeric compound is in fast equilibrium with a monomeric pincer compound of the type Pd[κ ¹-C, κ¹-N, κ¹-O-C=(MeO-2-C ₆H₄)C(Cl)CH₂NMe₂](Cl) assisted through the weak coordination of the OMe group. Pincer palladacycles Pd[κ¹-C, κ¹-N, κ¹-Y-C=(Y-2- C₆H₄)C(Cl)CH₂NMe₂](Cl) (Y=SMe and NH₂) were the sole products obtained in the chloropalladation of alkynes 4a and 5a. The bridge splitting reaction of the dimeric palladacycles 1b-3b with pyridine is highly selective, affording exclusively the corresponding monomeric compounds 1c-3c. The monomeric palladacycle 2d, which comprises a mixture of two atropisomers (2:1 ratio of anti/syn) was obtained from the reaction of 2b with 2-methylpyridine. Theoretical calculations indicated that the anti isomer of 2d is 5.42 kJmol^-1 more stable than its syn isomer.

Full text of DOI:10.1016/S0020-1693(03)00011-2

Inorganica Chimica Acta 350 (2003) 527Á536
/
www.elsevier.com/locate/ica
Atropisomerism in palladacycles derived from the chloropalladation
of heterosubstituted alkynes
Mara L. Zanini a, Mario R. Meneghetti a, Gunter Ebeling a, Paolo R. Livotto a,
¨
Frank Rominger b, Jairton Dupont a,*
a Laboratory of Molecular Catalysis, Instituto de Quimica, UFRGS, Av. Bento Goncalves 9500, Porto Alegre RS 91501-970, Brazil
¸
b Organisch-Chemisches Institut der Ruprecht-Karls-Universitat Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany
¨
Received 5 August 2002; accepted 27 November 2002
Dedicated to Dr Pierre Braunstein for his out standing contribution in Organometallic Chemistry.
Abstract
The chloropalladation of 2-substituted phenyl N,N-propargylamines, Y-2-C6H4CÅ
YꢀOMe; 4a, YꢀSMe and 5a, YꢀNH2) affords palladacycles in different ratios of isomers (geometric and atropisomers). In
solution, the parent alkyne (YꢀH) and the CF3 substituted derivative generate a mixture of cisoid and transoid chloro-bridged
dimer palladacycles of the type {Pd[k1-C, k1-N Á
CÄ(Y-2-C6H4)C(Cl)CH2NMe2](m-Cl)}2. Moreover, in the case of YꢀCF3
palladacyclic derivative each of the geometric isomers comprises a mixture of two diastereoisomers due to the restricted rotation of
the C(vinyl)ÃC(aryl) sigma bond (atropisomers). Palladacycles 1a (YꢀH) and 2a (YꢀCF3) crystallize as the single transoid and
/
CCH2NMe2 (1a, Yꢀ
/
H; 2a, YꢀCF3; 3a,
/
/
/
/
/
/
/
/
/
/
/
cisoid-anti isomer, respectively. The OMe substituted alkyne yields a similar dimeric compound that crystallizes as a single cisoid-
anti isomer. In solution this dimeric compound is in fast equilibrium with a monomeric pincer compound of the type Pd[k1-C, k1-N,
k1-O Ã
Pd[k1-C, k1-N, k1-Y Ã
chloropalladation of alkynes 4a and 5a. The bridge splitting reaction of the dimeric palladacycles 1bÁ
selective, affording exclusively the corresponding monomeric compounds 1cÁ3c. The monomeric palladacycle 2d, which comprises a
/
CÄ
/
(MeO-2-C6H4)C(Cl)CH2NMe2](Cl) assisted through the weak coordination of the OMe group. Pincer palladacycles
CÄ(Y-2-C6H4)C(Cl)CH2NMe2](Cl) (YꢀSMe and NH2) were the sole products obtained in the
3b with pyridine is highly
/
/
/
/
/
mixture of two atropisomers (2:1 ratio of anti/syn) was obtained from the reaction of 2b with 2-methylpyridine. Theoretical
calculations indicated that the anti isomer of 2d is 5.42 kJ molꢁ1 more stable than its syn isomer.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Palladacycles; Chloropalladation; Atropisomerism; Antisymbiotic effect
1. Introduction
various methods such as CÃ/H bond activation, trans-
metallation using aryllithium or magnesium organome-
tallic derivatives, oxidative addition of arylhalides,
transcyclometallation or chloropalladation of hetero-
substituted alkynes [2]. Structural geometric and stereo-
isomers are quite common in this class of organopalla-
dium compounds and these isomers can have distinct
Palladacycles possessing a PdÃ
/
C bond stabilized
two electron
intramolecularly by a PdÃY bond (Yꢀ
/
/
donor group, such as NR2, PR2, SR, etc.) have been
known since the 1960s [1] and have a large variety of
applications in areas ranging from new molecular
materials (liquid crystals, non-linear optics, molecular
electronics, etc.) to precursors for organometallic cata-
lysis [2]. These compounds are easily accessible through
physicalÁchemical properties and reactivities. The
/
presence of stereoisomers (enantio- and diastereo-iso-
mers) is usually related to the presence of a stereogenic
center in the palladated organic ligand. Cisoid
and transoid isomers are almost a general case in dimeric
halides palladacycles (Chart 1) and the transoid-geome-
try is usually the major compound of the mixture
* Corresponding author. Tel.: ꢂ
7304.
E-mail address: dupont@iq.ufrgs.br (J. Dupont).
/55-51-316 6321; fax: ꢂ55-51-3316
/
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00011-2

528
M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á536
/
Chart 1.
and the one most commonly observed in the solid state
[3].
While investigating the chloropalladation reaction [4]
of various 2-phenylsubstituted N,N-dimethylpropargy-
lamines we have isolated cisoid isomers of chloro
bridged dimeric palladacycles and we have established
that these compounds can also generate atropisomers. It
is interesting to note that atropisomers are classical in
organic molecules but rare in organometallic com-
pounds [5]. We wish to disclose herein some of our
experimental and theoretical results on the formation
and stabilization of atropisomers in cisoid palladacycles.
Scheme 2.
2.2. Solid-state structure of the palladacycles
The molecular structure of compounds 1bÁ
been also ascertained by means of X-ray diffraction
analysis. ORTEP diagrams are presented in Figs. 1Á3,
respectively, and selected bond distances and angles are
summarized in Tables 1 and 2, respectively. Crystal-
lographic data and details of the structure determination
are presented in Table 3. Tables of atomic coordinates
and anisotropic thermal parameters are supplied as
Supporting Information.
The coordination sphere around each Pd center can
be considered as essentially planar and this is also
evident for the centrosymmetric four-membered Pd2Cl2
rings (the Pd2Cl2-rings of 2b and 3b are bent (butterfly
shape) by 10 and 98, respectively). The conformation of
the five-membered rings formed by the ligands and the
Pd centers can be described as envelopes in which C(2) is
/
3b has
/
2. Results and discussion
2.1. Syntheses of the alkynes and palladacycles
The propargylalkynes 1a and 4a were prepared by
Mannich reaction of, respectively, phenylacetylene and
the easily available 2-methylthio-phenylacetylene with
HNMe2/CH2O. The alkynes 2a, 3a and 5a have been
obtained by Pd(PPh3)4/CuI promoted Sonogashira cou-
plings of the corresponding 2-aryl iodides or bromides
with 3-dimethylamino-1-propyne in diethylamine
(Scheme 1). These alkynes were characterized by means
of mass spectroscopy, IR, 1H and 13C NMR (Section 3).
˚
˚
˚
0.45 A in 1b, 0.43 A in 2b and 0.46 A in 3b, below the
planes containing Pd, C(1), C(3) and N(1).
However, it is noteworthy that there is a transoid
relationship through the chlorine bridges between the
NMe2 groups or the PdÃ
geometry is observed in palladacycles 2b and 3b.
Of note are the PdÃCl distances in compounds 1bÁ
those located trans to the PdÃC moiety are significantly
/C bonds in 1b whereas a cisoid
/
/3b;
The reaction of alkynes 1aÁ/5a with a methanolic
/
solution of Li2PdCl4 at 5 8C, using an identical proce-
dure to the one described earlier [4d], affords in almost
quantitative yields, the air and water stable pallada-
longer than those trans to NMe2 (Table 2) and this can
be attributed to the higher trans influence of the C
compared to the NMe2. This bond length difference is
similar to those usually observed in analogous halide-
bridged dimer palladacycles [3].
cycles 1bÁ
/
5b as orangeÁ
/
yellow crystalline solids
5b have been fully char-
(Scheme 2). Palladacycles 1bÁ
/
acterized by means of CHN combustion analysis, IR, 1H
and 13C NMR.
Unlike what was observed in compounds 1bÁ
/3b, the
palladacycles 4b and 5b are monomeric with the
Scheme 1.

M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á
/536
529
(Scheme 3). We observed that for each isomer the
methylene hydrogens and the dimethylamino groups
1
are equivalent (they appear as singlets in the H NMR
spectrum) and the proportion of the cisoid and transoid
isomers do not change with time or temperature, as
1
checked by H NMR spectroscopy at various tempera-
tures (from ꢁ30 to 30 8C). Note that above 40 8C the
/
dimer 1b decomposes.
Compound 2b in solution is composed of four isomers
in a 1:1:1:1 proportion since eight singlets are observed
for the NMe2 group and four AB spin systems for the
1
methylene hydrogens in its H NMR spectrum. As for
compound 1b, the proportion of these isomers does not
1
change with time or temperature (checked by H NMR
up to 40 8C). The most probable structure of these
isomers are anti and syn atropisomers (cisoid and
transoid chloro-bridged dimers) due to restricted rota-
tion of the 2-trifluoromethanearyl group through the
C(vinyl)Ã
/
C(aryl) bond (Scheme 4) within the NMR time
scale. It is of note that the 1H NMR spectrum of a
solution prepared at 0 8C in CDCl3 of isolated crystals
2b shows the presence of four isomers in a 1:1:1:1 ratio,
indicating that at this temperature the isomerization
process was already completed.
Fig. 1. ORTEP plot with atom-labeling scheme of the structure of 1b.
Displacement ellipsoids are at the 50% level; H atoms are omitted for
clarity.
formation of a pincer arrangement through the coordi-
nation of the SMe or NH2 groups. The structure 5b was
assigned by analogy with that of 4b (its X-ray molecular
structure has been recently reported [4e]) and on the
basis of its spectroscopic and chemical properties (see
below).
The 1H NMR spectrum of 3b shows the presence of a
single compound in which the OMe group is not
coordinated to the Pd center since its chemical shift
(3.68 ppm) is close to that of the free ligand 3a.
Moreover, the methylene hydrogens and the dimethyla-
mino groups are equivalent and they appear as singlets
at 3.59 and 2.83 ppm, at temperatures ranging from ꢁ
/
40 to 40 8C. This is a strong indication of a dynamic
process that renders the methylene hydrogens and NMe2
groups equivalent over this temperature range. How-
ever, also a fast rotation of the 2-methoxyaryl group
2.3. Solution structures of the palladacycles
1H NMR spectra of 1b in CDCl3 at room temperature
indicated the presence of two isomers in a 1:1 ratio, that
can be attributable to the cisoid and transoid geometries
through the C(vinyl)Ã
/
C(aryl) single bond could explain
Fig. 2. ORTEP plot with atom-labeling scheme of the structure of 2b. Displacement ellipsoids are at the 50% level; H atoms are omitted for clarity.

530
M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á536
/
Table 2
Selected bond angles (8) of palladacycles 1bÁ
/
3b and 2d
1b
2ba
C1Ã
C1Ã
N1Ã
C1ÃPd1Ã
N1ÃPd1Ã
Cl1ÃPd1Ã
Pd1ÃCl1Ã
/
Pd1Ã
Pd1Ã
Pd1Ã
/
N1 82.75(7)
C1Ã
C1Ã
N1Ã
C1ÃPd1Ã
N1ÃPd1Ã
Cl1ÃPd1Ã
Cl1ÃPd2Ã
Pd1ÃCl1Ã
Pd1ÃCl2Ã
/
Pd1Ã
Pd1Ã
Pd1Ã
/
N1 82.59(15)
/
/
Cl1 96.43(6)
/
/Cl1 93.45(12)
/
/
Cl1 179.07(5)
/
/
Cl1 175.23(10)
/
/
ClA 178.79(6)
/
/Cl2 177.10(13)
/
/
ClA 96.05
/
/
Cl2 98.44(9)
/
/
ClA 85.77(17)
Pd1A 95.22(17)
/
/
Cl2 85.64(4)
Cl2 85.25(4)
Pd2 97.91(4)
Pd2 90.25(4)
/
/
/
/
/
/
/
/
3ba
2d
C1Ã
C1Ã
N1Ã
C1ÃPd1Ã
N1ÃPd1Ã
Cl1ÃPd1Ã
Cl1ÃPd2Ã
Pd2ÃCl1Ã
Pd2ÃCl2Ã
/
Pd1Ã
Pd1Ã
Pd1Ã
/
N1 82.74(16)
C1Ã
C1Ã
N2Ã
C1ÃPd1Ã
N2ÃPd1Ã
N1ÃPd1Ã
C1ÃC2Ã
C3ÃC2Ã
N2ÃC26Ã
/
Pd1Ã
Pd1Ã
Pd1Ã
/
N2 93.02(10)
/
/
Cl1 95.60(12)
/
/N1 82.56 (10)
/
/
Cl1 178.24(12)
/
/
N1 175.02 (10)
/
/
Cl2 176.93(13)
/
/Cl1 177.84 (8)
Fig. 3. ORTEP plot with atom-labeling scheme of the structure of 3b.
Displacement ellipsoids are at the 50% level; H atoms are omitted for
clarity.
/
/
Cl2 95.99(11)
/
/
Cl1 88.98 (7)
/
/
Cl2 85.63(4)
Cl2 85.73(4)
Pd1 97.16(4)
Pd1 90.73(4)
/
/
Cl1 95.47 (7)
/
/
/
/
Cl2 123.5 (2)
Cl2 114.3 (2)
/
/
/
/
/
/
/
/
C27 118.2 (3)
Table 1
Selected bond distances (A) of palladacycles 1bÁ
˚
a
/
3b and 2d
Mean values of both parts of the dimers for 2b and 3b.
1b
2b
3b
2d
Pd1Ã
1.9974(18)
Pd1ÃN1
2.0641(16)
Pd1ÃCl1
2.3362(5)
Pd1ÃCl1A
2.4583(5)
C1ÃC2 1.328(3) C1Ã
1.309(5)
C1ÃCl1
1.479(6)
C16ÃC17
1.477(8)
C17ÃF1
1.340(6)
/
C1
Pd1Ã
1.983(4)
Pd1ÃN1
2.086(3)
Pd1ÃCl1
2.312(11)
Pd1ÃCl2
2.453(11)
C2
/
C1
Pd1Ã
1.987(4)
Pd1ÃN1
2.077(4)
Pd1ÃCl1
2.324(10)
Pd1ÃCl2
2.448(13)
C1ÃC2
1.321(6)
C1ÃCl1
1.469(6)
C16ÃO16
1.336(6)
/
C1
Pd1Ã
2.002(3)
Pd1ÃN2
2.042(2)
Pd1ÃN1
2.079(2)
Pd1ÃCl1
2.3876(7)
C1ÃC2
1.320(4)
C1ÃC11
1.488(4)
C16ÃC17
1.499(4)
C17ÃF1
1.331(4)
/
C1
6). These compounds were isolated as light-yellow air
and stable solids, and are soluble in polar organic
solvents such as dichloromethane and acetone.
/
/
/
/
1
The H NMR spectrum of 1cÁ/3c indicated that these
/
/
/
/
compounds were isolated as single isomers. As expected
the methylene hydrogens and NMe2 in 1c are equivalent
(they appear as singlets) whereas in 2c and 3c they are
inequivalent (AB spin pattern for the CH2 and two
singlets for the NMe2 group), indicating that there is
/
/
/
/
/
/
/
/
/
/
/
restricted rotation around the C(vinyl)Ã
compounds 2c and 3c. The location of the pyridine
ligand cis to the PdÃC bond in 1cÁ3c is based on their
1H NMR spectra, which shows the shielding of the
phenyl hydrogens to a lower frequency (B6.8 ppm) and
/C(aryl) bond in
/
/
/
/
/
/
/
/
Mean values of both parts of the dimers for 2b and 3b.
by analogy of the X-ray structure of analogous com-
pounds [6]. Theoretical calculations (Gaussian 98) [7]
this behavior if we assume the presence of a single
geometric isomer (cisoid or transoid) or their fast
interconversion. It is, however, more reasonable to
assume that this transformation occurs through the
formation of a ‘pincer’ intermediate (Scheme 5) where
the coordination of the OMe group assists the isomer-
ization (‘anchimerically-assisted isomerization process’).
clearly indicated that the cis CÃ
/
PdÃ
/
Py 1c isomer is 6.1
kcal molꢁ1 more stable than its trans CÃ
/
PdÃPy coun-
/
terpart. Moreover, this selectivity can be explained by
the antisymbiotic effect [8] of the soft Pd(II) center that
will place the incoming ligand cis to the PdÃ
/C bond.
This is an indication that the stereochemical out-come of
the bridge-splitting reaction is under thermodynamic
control.
1
The H NMR spectra of compounds 4b and 5b are
clearly consistent with the formation of a highly stable
‘pincer’ type structure, which does not undergo reaction
with donor ligands such as pyridine. In opposition, the
Interesting, atropo-diastereoisomers can be easily
prepared by reaction of dimeric compounds 2b and 3b
with substituted pyridines. Thus the reaction of 2b with
2-methylpyridine affords in almost quantitative yield the
monomeric palladacycle 2d (Scheme 7) as a mixture of
two atropisomers in 2:1 ratio, that do not change with
chloro-bridged dimers 1bÁ
dichloromethane at room temperature to afford the
adducts 1cÁ3c, respectively, in very good yields (Scheme
/3b do react with pyridine in
/

M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á
/536
531
Table 3
Summary of the crystal data and structure refinement for 1bÁ
/3b and 2d
1b
2b
3b
2d
Chemical formula
Temperature (K)
˚
Wavelength (A)
C22H26Cl4N2Pd2
200(2)
0.71073
C24H24Cl4F6N2Pd2
200(2)
C24H30Cl4N2O2Pd2
200(2)
0.71073
C18H19Cl2F3N2Pd
200(2)
0.71073
Monoclinic
C2/c
0.71073
Orthorhombic
Pna21
Crystal system
Space group
Z
Monoclinic
P21/c
Monoclinic
C2/c
2
8
8
4
˚
a (A)
13.0324(3)
8.2305(2)
11.9947(3)
108.702(1)
1218.66(5)
1.83
23.0218(5)
11.1004(3)
25.7210(4)
116.523(1)
5881.3(2)
1.83
20.2663(2)
13.0459(2)
23.5953(1)
113.980(1)
5699.96(11)
1.71
18.0239(2)
8.1098(2)
13.6206(3)
90
˚
b (A)
˚
c (A)
b (8)
Volume (A )
3
˚
1990.93(7)
1.66
1.23
rcalc (g cmꢁ3
)
m (mmꢁ1
)
1.93
Polyhedron
1.64
Polyhedron
1.66
Polyhedron
Crystal shape
Polyhedron
Crystal dimensions (mm3)
u range for data collected (8)
Index range
0.50ꢃ
3.0Á27.5
160h 0
100k 0
150l 015
12 064
2794 (Rint
2506 (I ꢀ
/
0.30ꢃ
/
0.04
0.22ꢃ
1.8Á27.5
290h 0
100k 0
330l 029
9172
5833 (Rint
3952 (I ꢀ
/
0.18ꢃ
/
0.05
0.36ꢃ
1.9Á27.5
260h 0
160k 0
250l 030
20 226
6477 (Rint
4558 (I ꢀ
/
0.20ꢃ
/
0.06
0.37ꢃ
2.3Á27.5
230h 0
80k 0
140l 0
5720
3617 (Rint
3337 (I ꢀ
/
0.33ꢃ
/
0.24
/
/
/
/
ꢁ
/
/
/16
ꢁ
/
/
/29
ꢁ
/
/
/23
ꢁ
/
/
/23
ꢁ
/
/
/10
ꢁ
/
/
/13
ꢁ
/
/
/
16
ꢁ
/
/
/
10
17
ꢁ/
/
/
ꢁ/
/
/
ꢁ/
/
/
ꢁ/
/
/
Reflections collected
Independent reflections
Observed reflections
ꢀ/
0.0285)
ꢀ/
0.0393)
ꢀ/0.0404)
ꢀ/0.0172)
/2s(I))
/2s(I))
/2s(I))
/2s(I))
Max./min. transmission
Data/restraints/parameters
0.94 and 0.73
2794/0/138
0.93 and 0.68
5833/0/347
0.92 and 0.69
6477/0/313
0.84 and 0.71
3617/1/236
R indices (I ꢀ
/
2s(I))
Largest difference peak/hole (e A
R1ꢀ
0.47 and ꢁ
/
0.019, wR2ꢀ
/
0.048 R1ꢀ
/
0.036, wR2ꢀ
/
0.066 R1ꢀ
/
0.039, wR2ꢀ
/
0.088 R1ꢀ
/
0.019, wR2ꢀ
/
0.047
ꢁ3
˚
)
/
0.34
0.49 and ꢁ
/
0.78
0.89 and ꢁ
/0.73
0.50 and ꢁ
/0.32
Scheme 3.
1
time or temperature (determined by H NMR spectro-
scopy).
The structure of the major isomer of 2d was deter-
mined by an X-ray diffraction study. An ORTEP drawing
of 2d is shown in Fig. 4 and selected bond angles and
distances are summarized in Tables 1 and 2, respectively.
Crystallographic data and details of the structure
determination are presented in Table 3.
Scheme 4.
The coordination sphere of Pd including the C1, Cl1,
N1 and N2 atoms can be considered as being essentially
planar, with mean atomic deviation from the best plane
rings, thus the major diastereoisomer has an R,R
(S,S) relative stereochemistry.
As already pointed out this diastereoisomer presents
˚
of the five atoms of 0.024 A. The cis stereochemistry
restricted rotation around the C1Ã
/
C11 and PdÃ
/
N2
between C1ÃPdÃN2 is evident with an angle of 93.028.
/
/
single bonds. Theoretical calculations on the syn and
anti isomers of 2d show that the anti isomer is 5.42
kJ molꢁ1 more stable than its syn analogue corroborat-
ing the experimental results, which indicated the pre-
The two aryl rings are almost parallel with an angle
between the two aryl ring planes of 45.78. Of note is the
anti-relationship between the two 2-substituted aryl

532
M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á536
/
Scheme 5.
in oven dried Schlenk tubes. The alkynes were prepared
according to known procedures. Solvents were dried
with suitable drying agents and distilled under argon
prior to use. All the other chemicals were purchased
from commercial sources (Acros or Aldrich) and used
without further purification. Elemental analyses were
performed by the Analytical Central Service of IQ-USP
(Brazil). NMR spectra were recorded on a Varian Inova
300 spectrometer. Infrared spectra were performed on a
Bomem B-102 spectrometer. Mass spectra were ob-
tained using a GC/MS Shimadzu QP-5050 (EI, 70 eV).
Gas chromatography analyses were performed with a
Hewlett-Packard-5890 Gas Chromatograph with a FID
and 30 m capillary column with a dimethylpolysiloxane
stationary phase.
Scheme 6.
sence of both isomers at room temperature in a 2:1 ratio.
The rotational barrier is expected to be very high due to
the steric congestion between the Cl-vinyl moiety and
the 2-aryl substituent. This suggests that the anti Ásyn
isomerization can only occur through a dissociative
mechanism.
/
The results show that the chloropalladation reaction
of 1-[2-(substituted)-phenyl]-3-N,N-dimethylamino-1-
propynes can lead to palladacycles constituted of stable
atropisomers. The stereoselection on the bridge splitting
reaction of these dimers with 2-methylpyridine is
sufficient for the separation of the atropisomers. This
opens the possibility for the preparation of optically
active organometallic atropisomers, similar to biphenyl
organic compounds [5], by the use of non-racemic
3.2. Theoretical calculations
The energy of all calculated species was obtained by
full geometry optimization without any constrain. The
calculations were performed with the Gaussian 98’
Program [7], at a HF/B3LYP [9] level of theory, using
a Dunning-Huzinaga DZ95 [10] basis set for the non-
propargylamines such as Me2NCH(Me)CÅ
/
CAr.
3. Experimental
3.1. General methods
All reactions involving organometallic compounds
were carried out under argon or nitrogen atmosphere
Scheme 7.

M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á
/536
533
and cuprous iodide (0.45 g) in 250 ml dioxane. The
reaction mixture was refluxed for 4 h and the solvent
was removed under reduced pressure. Distillation of the
residue afforded a colorless liquid of boiling point
114 8C/5 mmHg (71.8 g, 94% yield). GCÁ
[peak]): 159, [M]+ꢂ; 115, [M-NMe2]ꢂ. 1H NMR
(CDCl3): d 7.46Á7.38 (m, 2H, H arom); 7.33Á7.23 (m,
/MS (m/z,
/
/
3H, H arom); 3.45 (s, 2H, CH2N); 2.35 (s, 6H, NMe2).
13C{1H} NMR (CDCl3): d 132.1, 128.5, 128.1 (CH
arom); 124.1 (C arom quat); 85.9, 85.1 (CÅ
/
C); 49.8
(CH2N); 44.4 (NMe2).
3.5. Synthesis of 1-[2-(trifluoromethyl)-phenyl]-3-
(dimethylamino)-1-propyne (2a)
A mixture of 3-dimethylamino-1-propyne (2.0 g, 24.0
mmol), 2-trifluoromethyl-bromobenzene (5.42 g, 24.0
mmol), PdCl2(PPh3)2 (0.20 g, 0.29 mmol), cuprous
iodide (0.026 g, 0.14 mol) and diethylamine (30 ml)
was maintained under gentle reflux for 24 h. Solvent
evaporation under reduced pressure and bulb-to-bulb
distillation furnished a colorless liquid of boiling point
90 8C/16 mmHg (0.88 g, 16% yield). 1H NMR (CDCl3):
Fig. 4. ORTEP plot with atom-labeling scheme of the structure of 2d.
Displacement ellipsoids are at the 50% level; H atoms are omitted for
clarity.
metal atoms and a DZ valence basis set plus an effective
core potential [11] for the palladium.
d 7.52Á7.37 (m, 4H, H arom); 3.45 (s, 2H, CH2N); 2.30
/
(s, 6H, NMe2). 13C{1H} NMR (CDCl3): d 133.9, 131.1,
3.3. X-ray structures analysis of 1bÁ3b and 2d
/
2
127.4 (CH arom); 131.1 (q, 1C, JFC
ꢀ
/
30.6 Hz, C arom
5.1 Hz, CH arom);
273 Hz, CF3); 121.6 (C arom quat);
C); 48.1 (CH2N); 43.6 (NMe2).
3
Crystals were mounted on a glass fiber with perfluor-
opolyether. The measurements were made on a Bruker
SMART-CCD diffractometer with graphite monochro-
mated Mo Ka radiation. For 1b and 3b, frames
corresponding to a sphere of data were collected using
the omega-scan technique, 20 s exposures of 0.38 in
omega were taken. For 2b and 2d, frames corresponding
to at least one complete set of independent reflections
(one asymmetric unit of reciprocal space) were collected
using the omega-scan technique, 10 s exposures of 0.38
in omega were taken. An absorption correction was
applied, in each case, using SADABS based on the laue
symmetry of the reciprocal space, the data were
corrected for Lorentz and polarization effects. The
structures were solved by direct methods and expanded
using Fourier techniques, all non-hydrogen atoms were
refined with anisotropic displacement parameters, hy-
drogen atoms could be located in the Fourier map, but
then were considered at calculated positions. The full-
matrix least-squares refinement against F2 converged.
All calculations were performed using the SHELXTL
crystallographic software package [12].
quat ipso CF3); 125.4 (q, 1C, JFC
123.4 (q, 1C, 1JFC
90.7, 81.0 (CÅ
ꢀ
/
ꢀ
/
/
3.6. Synthesis of 1-[2-(methoxy)-phenyl]-3-
(dimethylamino)-1-propyne (3a)
A mixture of 3-dimethylamino-1-propyne (1.00 g,
12.0 mmol), 2-iodo-anisole (2.30 g, 10.0 mmol),
Pd(PPh3)4 (0.120 g, 0.100 mmol), cuprous iodide
(0.040 g, 0.200 mmol), DMF (1.5 ml) and diethylamine
(20 ml) was maintained under reflux for 24 h. The
volatiles were removed under reduced pressure, ether (20
ml) and KOH solution (10% aqueous, 20 ml) were
added and the mixture was stirred for 5 min. The
organic layer was separated, the aqueous layer was
extracted with ether (2ꢃ10 ml) and the combined
/
organic extract was dried with MgSO4. The solvent
was evaporated and the crude reaction product was
purified by column chromatography (silica-gel, hexanes/
EtOAc: 90/10 v/v) giving a colorless liquid (1.72 g, 75%
yield). IR (film, cmꢁ1): 2232 (nCÅC). 1H NMR (CDCl3):
3
d 7.40 (d, 1H, JHH
3.4. Synthesis of 1-phenyl-3-(dimethylamino)-1-propyne
(1a)
ꢀ
/
7.4 Hz, H arom); 7.25 (t, 1H,
3JHH
ꢀ
/
7.4 Hz, H arom); 6.90Á
/6.84 (m, 2H, H arom);
3.86 (s, 3H, OMe); 3.52 (s, 2H, CH2N); 2.37 (s, 6H,
NMe2). 13C{1H} NMR (CDCl3): d 159.8, 112.3 (C arom
quat); 133.5, 129.3, 120.2, 110.4 (CH arom); 88.6, 81.3
Dimethylamine (40% aqueous solution, 91 ml, 0.72
mol) was added to a stirred mixture of phenylacetylene
(49.0 g, 0.48 mol), paraformaldehyde (30.0 g; 0.53 mol)
(CÅ
/
C); 55.6 (OMe); 48.7 (CH2N); 44.0 (NMe2).

534
M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á536
/
3.7. Synthesis of 1-[2-(methylthio)-phenyl]-3-
(dimethylamino)-1-propyne (4a)
the resulting solid with cold MeOH and drying under
reduced pressure afforded the desired palladacycles.
A mixture of 2-methylthio-phenylacetylene [13] (0.833
g, 5.60 mmol), paraformaldehyde (0.185 mg, 6.20
mmol), dimethylamine (50% aqueous solution, 0.8 ml),
dioxane (5 ml) and cuprous iodide (0.014 g) was refluxed
for 9 h. The solvent was evaporated and the residue was
purified by column chromatography (basic alumina,
activity grade II, hexanes/EtOAc 50/50 v/v), furnishing a
pale yellow oil (0.970 g, 85% yield). IR (film, cmꢁ1):
3.10. Synthesis of palladacycle (1b) [4d]
Accordingly to the described general procedure, a
yellow solid of melting point 172Á175 8C (dec.) was
/
obtained (1.24 g, 88% yield). Anal. (C11H13Cl2NPd)2
(673.11) requires C, 39.26; H, 3.89; N, 4.16. Found: C,
39.40; H, 3.99; N, 4.15. IR (KBr, cmꢁ1): 1600 (nCÄC). 1H
NMR (CDCl3): d 7.35Á
2H, CH2N); 3.59 (s, 2H, CH2N); 2.88 (s, 6H, NMe2);
2.77 (s, 6H, NMe2). 1H NMR (CDCl3ꢂ
Py-d5): d 6.92Á
/6.90 (m, 10H, H arom); 3.61 (s,
2262 (nCÅC). GCÁ
[M]+ꢂ; 204, 10, [M-1]ꢂ; 190, 15, [M-15]ꢂ; 160, 100, [M-
Me2NH]+ꢂ; 82, 12, [Me2NCH2CÅC]ꢂ; 58, 18, [Me2NÄ
CH2]ꢂ. 1H NMR (CDCl3): d 7.44Á
7.06 (m, 4H, H
/MS (m/z, rel int%, [peak]): 205, 2,
/
/
/
/
6.75 (m, 5H, H arom); 3.67 (s, 2H, CH2N); 3.01 (s, 6H,
NMe2). 13C{1H} NMR (CDCl3): d 142.9, 142.7, 141.9,
141.7, 116.1, 115.7 (C arom quat and CÄ
127.7, 127.5, 127.4, 125.9, 125.8 (CH arom); 74.6, 74.3
(CH2N); 53.2, 52.9 (NMe2).
/
arom); 3.59 (s, 2H, CH2N); 2.43 (s, 3H, SMe); 2.18 (s,
6H, NMe2). 13C{1H} NMR (CDCl3): d 147.1, 121.5 (C
arom quat); 132.8, 128.8, 124.4, 124.1 (CH arom); 91.6,
/
C); 128.1,
83.0 (CÅ
/
C); 48.9 (CH2N); 44.4 (NMe2); 15.2 (SMe).
3.11. Synthesis of palladacycle (2b)
3.8. Synthesis of 1-[2-(amino)-phenyl]-3-
(dimethylamino)-1-propyne (5a)
Accordingly to the described general procedure, a
yellow solid was obtained (1.10 g, 65% yield). Anal.
(C12H12Cl2F3NPd)2 (809.11) requires C, 35.63; H, 2.99;
A mixture of 2-iodo-aniline (3.50 g, 15.0 mmol), 3-
dimethylamino-1-propyne (1.89 g, 22.5 mmol),
Pd(PPh3)4 (0.120 g, 0.100 mmol), cuprous iodide
(0.040 g, 0.200 mmol) and DMF (1.5 ml) in diethyla-
mine (20 ml) was stirred overnight. The solvent was
evaporated, ether (20 ml) and aqueous 10% potassium
hydroxide (20 ml) were added and the mixture was
stirred for 5 min. The layers were separated, the aqueous
1
N, 3.46. Found: C, 35.81; H, 2.93; N, 3.45. H NMR
(CDCl3): d 7.60Á
2H, CH2N); 3.82Á
6.1 Hz, CH2N); 3.30 (d, 2H, Jꢀ
/
6.80 (m, 16H, H arom); 3.92Á
3.75 (m, 2H, CH2N); 3.38 (d, 2H, Jꢀ
6.1 Hz, CH2N); 2.98 (s,
/
3.85 (m,
/
/
/
6H, NMe); 2.92 (s, 3H, NMe); 2.88 (s, 3H, NMe); 2.75
(s, 3H, NMe); 2.73 (s, 3H, NMe); 2.60 (s, 3H, NMe);
2.57 (s, 3H, NMe). 13C{1H} NMR (CDCl3): d 141.7,
141.4, 141.0 (CÄ
/
C); 138.3, 138.0, 137.9 (C arom quat);
layer was extracted with ether (2ꢃ10 ml) and the
/
131.2, 131.1, 130.9, 130.7, 129.9, 129.8, 129.7, 129.3,
combined organic extract was dried with MgSO4. The
solvent was evaporated and the crude reaction product
was chromatographed over basic alumina (hexanes/
EtOAc: 90/10 v/v) giving a pale brown solid of melting
3
125.9, 125.7, 125.6 (CH arom); 125.4 (q, 1C, JFC
Hz, CH arom); 124.5, 124.4, 124.3, 124.1 (q, 1C, 1JFC
271 Hz, CF3); (C arom quat ipso CF3: not observed);
118.2, 117.8, 117.7 (CÄC); 76.6, 74.6, 74.5, 74.4 (CH2N);
53.4, 53.2, 53.0, 52.8, 52.7 (NMe). 13C{1H} NMR
ꢀ/5.1
ꢀ
/
/
point 40Á
42 8C (2.00 g, 77% yield). IR (Nujol, cmꢁ1):
/
2208 (nCÅC). GCÁMS (m/z, rel int%, [peak]): 174, 29,
/
(CDCl3ꢂ
/
Py-d5): d 141.9, 141.5 (C arom quat and CÄ
/
[M]+ꢂ; 159, 7, [M-CH3]ꢂ; 130, 100, [M-NMe2]ꢂ; 58,
C); 130.9, 128.9, 125.3, (CH arom); 125.7 (q, 1C, 3JCF
ꢀ
/
1
23, [Me2NÄ
/
CH2]ꢂ. H NMR (CDCl3): d 7.31, 6.72 (d,
1
5 Hz, CH arom); 124.2 (q, 1C, JCF
ꢀ
/
275 Hz, CF3); (C
C); 75.1
3
1H, JHH
3
7.5 Hz, H arom); 7.14, 6.70 (d, 1H, JHH
ꢀ
/
ꢀ
/
arom quat ipso CF3: not observed); 119.4 (CÄ
(CH2N); 53.1, 52.4 (NMe).
/
7.5 Hz, H arom); (4.24 (br s, 2H, NH2); 3.57 (s, 2H,
CH2N); 2.40 (s, 6H, NMe2). 13C{1H} NMR (CDCl3): d
147.8, 107.8 (C arom quat); 132.8, 129.3, 117.3, 114.1
3.12. Synthesis of palladacycle (3b)
(CH arom); 89.5, 81.8 (CÅ
/C); 48.6 (CH2N); 44.1
(NMe2).
Accordingly to the described general procedure, a
yellow solid was obtained (0.78 g, 51% yield). Anal.
(C12H15Cl2NOPd)2 (733.17) requires C, 39.32; H, 4.12;
N, 3.82. Found: C, 39.34; H, 3.92; N, 4.01. IR (KBr,
3.9. Synthesis of palladacycles 1bÁ3b: general procedure
/
A Li2PdCl4 solution was prepared by dissolving PdCl2
(0.745 g, 4.20 mmol) and LiCl (0.45 g, 10.5 mmol) in hot
methanol (15 ml). After dissolution of the solids, this
solution was cooled to 0 8C and the appropriate alkyne
(1a, 2a or 3a, 5.00 mmol) was added. The resulting
suspension was stirred for 1 h. Filtration and washing of
cmꢁ1): 1631 (nCÄC).1H NMR (CDCl3): d 7.18 (t, 1H,
3
3JHH
ꢀ
/
6.9 Hz, H arom); 6.93 (d, 1H, JHH
ꢀ7.4 Hz, H
/
arom); 6.77 (t, 1H, 3JHH
3JHH
7.6 Hz, H arom); 3.68 (s, 3H, OMe); 3.59 (s, 2H,
CH2N); 2.83 (s, 6H, NMe2). 13C{1H} NMR (CDCl3): d
155.1, 139.5 131.2 (C arom quat and CÄC); 128.7, 127.5,
ꢀ7.4 Hz, H arom); 6.65 (d, 1H,
/
ꢀ
/
/

M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á
/536
535
120.0, 110.8 (CH arom); 116.0 (CÄ
/C); 74.2 (CH2N);
solution was concentrated to 1 ml and hexanes (10 ml)
were added. The resulting yellow solid was filtered,
washed with hexanes and dried under reduced proce-
dure.
55.8 (OMe); 52.7 (NMe2).
3.13. Synthesis of palladacycle (4b)
A Li2PdCl4 solution was prepared by dissolving, with
gentle heating, PdCl2 (0.337 g, 1.88 mmol) and LiCl
(0.200 g, 4.70 mmol) in methanol (10 ml). The former
solution was allowed to react with a solution of 1-[2-
(methylthio)-phenyl]-3-(dimethylamino)-1-propyne (4a)
(0.385 g, 1.88 mmol), dissolved in methanol (5 ml). The
resulting suspension was stirred for 30 min, the volatiles
were removed under reduced pressure and the residue
was taken up in a minimum amount of CH2Cl2.
Subsequent chromatographic purification (column, si-
lica-gel, EtOAc) afforded a yellow solid of melting point
3.16. Palladacycle 1c
This compound was obtained accordingly to the
general procedure using palladacycle 1b and pyridine
(0.030 g, 81% yield). Anal. C16H18Cl2N2Pd (415.66)
requires C, 46.23, H, 4.36, N, 6.74. Found: C, 46.61, H,
4.37, N, 6.54. 1H NMR (CDCl3): d 8.30 (d, 2H, 3JHH
3
4.9 Hz, H py); 7.42 (t, 1H, JHH
6.82 (m, 7H, H arom and H py); 3.69 (s, 2H, CH2N);
3.03 (s, 6H, NMe2). 13C{1H} NMR (CDCl3) d 153.3,
138.4, 137.0, 131.7, 128.2, 127.6, 127.3, 125.2, 125.0,
124.3 (CH arom and CH py); 146.1, 142.3 (C arom quat
ꢀ
/
ꢀ
/
6.1 Hz, H py); 6.95Á
/
148Á150 8C (dec.) (0.480 g, 67% yield). Anal.
/
C12H15Cl2NSPd (382.6) requires C, 37.67; H, 3.95; N,
3.66. Found: C, 37.97; H, 4.11; N, 3.67. IR (Nujol,
and CÄ
/
C); 117.4 (CÄ
/
C); 75.2 (CH2N); 53.0 (NMe2).
1
cmꢁ1): 1590 (nCÄC). H NMR (CDCl3): d 8.51 (d, 1H,
Jꢀ
/
7.7 Hz, H arom); 7.43Á7.28 (m, 3H, H arom); 3.95
/
3.17. Palladacycle 2c
(s, 2H, CH2N); 3.00 (s, 6H, NMe2); 2.87 (s, 3H, SMe).
13C{1H} NMR (CDCl3): d 147.8, 145.1, 138.6 (C arom
This compound was obtained accordingly to the
general procedure using the palladacycle 2b and pyridine
(0.032 g, 89% yield). Anal. C17H17Cl2F3N2Pd (483.66)
requires C, 42.22; H, 3.54; N, 5.79. Found: C, 42.37; H,
quat and CÄ
/
C); 130.8, 129.4, 128.8, 127.0 (CH arom);
118.3, (CÄC); 77.8 (CH2N); 52.1 (NMe2); 26.7 (SMe).
/
2.67; N, 5.42. 1H NMR (CDCl3): d 8.32 (d, 2H, 3JHH
ꢀ
/
3.14. Synthesis of palladacycle (5b)
3
4.9 Hz, H py); 7.42 (t, 2H, JHH
ꢀ
/
6.2 Hz, H py); 7.29Á
/
2
6.81 (m, 6H, H arom and H py); 3.92 (d, 1H, JHH
A Li2PdCl4 solution was prepared by dissolving PdCl2
(0.178 g, 1.00 mmol) and LiCl (0.107 g, 2.50 mmol) in
hot methanol (5 ml), under vigorous stirring. After
dissolution of the solids, this solution was cooled to
0 8C and a solution of 1-[2-(amino)-phenyl]-3-(dimethy-
lamino)-1-propyne 5a (0.174 g, 1.00 mmol) in 2 ml of
MeOH was added. The resulting yellow suspension was
stirred at 0 8C for 3 h. The solvent was evaporated to
dryness under reduced pressure and the residue was
extracted with CH2Cl2. The organic solution was filtered
through a plug of Celite and concentrated to 5 ml.
Addition of hexanes, filtration, washing of the resulting
solid with hexanes and drying under reduced pressure
furnished a pale brown solid (0.250 g, 71% yield). Anal.
C11H14Cl2N2Pd (351.57) requires C, 37.58; H, 4.01; N,
7.97. Found: C, 37.88; H, 3.91; N, 7.81. 1H NMR
ꢀ
/
2
15.2 Hz, CH2N); 3.46 (d, 1H, JHH
ꢀ15.2 Hz, CH2N);
/
3.10 (s, 3H, NMe); 2.95 (s, 3H, NMe). 13C{1H} NMR
(CDCl3) d 152.4, 139.9, 124.3 (CH py); 142.1, 141.6 (C
arom quat and CÄ
/
C); 130.9, 128.9, 124.3 (CH arom);
5.1 Hz, CH arom); 124.3 (q, 1C,
274 Hz, CF3); (C arom quat ipso CF3: not
C); 75.2 (CH2N); 53.2 (NMe);
3
125.8 (q, 1C, JFC
1JFC
ꢀ
/
ꢀ
/
observed); 119.5 (CÄ
52.5 (NMe).
/
3.18. Palladacycle 3c
This compound was obtained accordingly to the
general procedure using the palladacycle 3b and pyridine
(0.030 g, 83% yield). Anal. C17H20Cl2N2OPd (445.68)
requires C, 45.81; H, 4.52; N, 6.29. Found: C, 45.60; H,
(CDCl3): d 8.29 (m, 1H, H arom); 7.23Á7.13 (m, 3H, H
arom); 5.62 (br s, 2H, NH2); 3.72 (s, 2H, CH2N); 2.71 (s,
6H, NMe2). 13C{1H} NMR (CDCl3): d 146.2, 145.8,
139.8 (C arom quat and CÄ
(CH arom); 114.2 (CÄC); 77.8 (CH2N); 52.1 (NMe2).
/
4.55; N, 6.19. 1H NMR (CDCl3): d 8.29 (d, 2H, 3JHH
ꢀ
/
3
4.9 Hz, H py); 7.41 (t, 2H, JHH
ꢀ
/
6.2 Hz, H py); 6.98Á
7.4
7.5 Hz, H arom); 3.75
/
/
C); 128.4, 127.0, 126.9, 125.3
6.85 (m, 3H, H arom and H py); 6.64 (t, 1H, 3JHH
ꢀ
/
/
Hz, H arom); 6.34 (d, 1H, 3JHH
ꢀ
/
2
(d, 1H, JHH
2
ꢀ/15.2 Hz, CH2N); 3.62 (d, 1H, JHH
ꢀ
/
3.15. Synthesis of palladacycles 1cÁ
procedure
/
3c, 2d: general
15.2 Hz, CH2N); 3.58 (s, 3H, OMe); 3.08 (s, 3H, NMe);
3.00 (s, 3H, NMe). 13C{1H} NMR (CDCl3) d 154.5,
142.6, 131.2 (C arom quat and CÄ
138.6, 136.7, 128.6, 127.2, 124.9, 123.6, 120.0 (CH arom
and CH py); 117.4 (CÄC); 75.0 (CH2N); 55.1 (OMe);
53.0, 52.6 (NMe).
/
C); 153.3, 152.5,
The dimeric palladacycle 1b, 2b or 3b (0.08 mmol) was
dissolved in CH2Cl2 (5 ml) and the appropriate pyridine
(pyridine or 2-picoline, 0.22 mmol) was added. The
/

536
M.L. Zanini et al. / Inorganica Chimica Acta 350 (2003) 527Á536
/
3.19. Palladacycle 2d
References
[1] A.C. Cope, E.C. Friedrich, J. Am. Chem. Soc. 90 (1968) 909.
[2] (a) See for recent reviews M. Albrecht, G. van Koten, Angew.
Chem. Int. Ed. 40 (2001) 3750;
This compound was obtained accordingly to the
general procedure using the palladacycle 2b and 2-
picoline (0.025 g, 81% yield). Anal. C18H19Cl2F3N2Pd
(497.68) requires C, 43.44; H, 3.85; N, 5.63. Found: C,
(b) J. Dupont, M. Pfeffer, J. Spencer, Eur. J. Inorg. Chem. (2001)
1917.
1
[3] G.R. Newkome, W.E. Puckett, V.R. Gupta, G.E. Kiefer, Chem.
Rev. 86 (1986) 451.
43.31; H, 3.92; N, 5.57. H NMR (CDCl3): d 8.31 (d,
3
1H, JHH
ꢀ
/
5.8 Hz, H arom picoline); 8.27 (d, 1H,
5.8 Hz, H arom picoline); 7.39Á6.56 (m, 14H, H
arom and H arom picoline); 4.02 (d, 1H, JHH
[4] (a) See for the chloropalladation of heterosubstituted alkynes T.
Yukawa, S. Tsutsumi, Inorg. Chem. 7 (1968) 1458;
(b) J.E. Backvall, Y.I.M. Nilsson, R.G.P. Gatti, Organometallics
3JHH
ꢀ
/
/
2
ꢀ
/
15.2
15.2 Hz, CH2N);
15.2 Hz, CH2N) and 3.64 (d, 1H,
15.2 Hz, CH2N); 3.17 (s, 3H, Me picoline); 3.09
¨
2
14 (1995) 4242;
(c) J. Dupont, N.R. Basso, M.R. Meneghetti, Polyhedron 15
(1996) 2299;
Hz, CH2N) and 3.41 (d, 1H, JHH
ꢀ
/
2
3.74 (d, 1H, JHH
2JHH
ꢀ
/
ꢀ
/
(d) J. Dupont, N.R. Basso, M.R. Meneghetti, R.A. Konrath, R.
Burrow, M. Horner, Organometallics 16 (1997) 2386;
(e) G. Ebeling, M.R. Meneghetti, F. Rominger, J. Dupont,
Organometallics 21 (2002) 3221.
(s, 3H, NMe); 3.06 (s, 3H, Me picoline); 3.00 (s, 3H,
NMe), 2.98 (s, 3H, NMe), 2.95 (s, 3H, NMe). 13C{1H}
NMR (CDCl3): d 160.3, 158.7 141.7, 141.2 (C arom
[5] E.L. Eliel, S.H. Wilen, Stereochemistry of Organic Compounds,
quat and CÄ
/
C); 152.0, 151.8, 136.8, 136.7, 131.0, 130.7,
Wiley, New York, 1993, pp. 1142Á1155.
/
129.2, 127.4, 125.5, 125.2, 125.0, 124.9, 121.5 (CH arom
[6] A.D. Ryabov, L.G. Kuzmina, V.A. Polyakov, G.M. Kazankov,
E.S. Ryabova, M. Pfeffer, R. Vaneldik, J. Chem. Soc. Dalton
Trans. (1995) 999.
3
and CH picoline); 126.3, 125.8 (q, 1C, JFC
ꢀ
/
5.4 Hz,
275 Hz, CF3); (C arom
quat ipso CF3: not observed); 119.3, 119.2 (CꢀC); 75.4,
1
CH arom); 124.3 (q, 1C, JFC
ꢀ
/
[7] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A.
Robb, J.R. Cheeseman, V.G. Zakrzewski, J.A. Montgomery Jr.,
R.E. Stratmann, J.C. Burant, S. Dapprich, J.M. Millam, A.D.
Daniels, K.N. Kudin, M.C. Strain, O. Farkas, J. Tomasi, V.
Barone, M. Cossi, R. Cammi, B. Mennucci, C. Pomelli, C.
Adamo, S. Clifford, J. Ochterski, G.A. Petersson, P.Y. Ayala, Q.
Cui, K. Morokuma, D.K. Malick, A.D. Rabuck, K. Raghava-
chari, J.B. Foresman, J. Cioslowski, J.V. Ortiz, B.B. Stefanov, G.
Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. Gomperts, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A.
Nanayakkara, C. Gonzalez, M. Challacombe, P.M.W. Gill, B.
Johnson, W. Chen, M.W. Wong, J.L. Andres, C. Gonzalez, M.
Head-Gordon, E.S. Replogle, J.A. Pople, Gaussian 98, Revision
A.5; Gaussian, Inc., Pittsburgh, PA, 1998.
/
75.2 (CH2N); 53.2, 52.9, 52.5, 52.3 (NMe); 27.5, 27.0
(Me picoline).
4. Supplementary material
Tables of full crystal data, atomic coordinates,
calculated hydrogen coordinates, anisotropic thermal
parameters, and a complete list of bond lengths and
angles have been posited with the Cambridge Crystal-
lographic Data Centre, CCDC Nos. 197910-197913.
Copies of this information may be obtained free of charge
from The Director, CCDC, 12 Union Road, Cambridge,
[8] (a) R.G. Pearson, Inorg. Chem. 12 (1973) 712;
(b) See for recent example of antisymbiotic effect P. Braunstein,
F. Naud, A. Dedieu, M.-M. Rohmer, A. DeCian, S.J. Rettig,
Organometallics 20 (2001) 2966.
[9] (a) C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785;
(b) A.D. Becke, Phys. Rev. A 38 (1988) 3098.
CB2 IE2, UK (fax ꢂ44-1223-336-033; e-mail: depos-
it@ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).
/
[10] T.H. Dunning, Jr., P.J. Hay, in: H.F. Schaefer, III (Ed.), Modern
Theoretical Chemistry, vol. 3, Plenum, New York, 1976, p. 1.
[11] (a) P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 270;
(b) W.R. Wadt, P.J. Hay, J. Chem. Phys. 82 (1985) 284;
(c) P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 299.
[12] G.M. Sheldrick, SHELXTL, Bruker Analytical X-ray-Division,
Madison, WI, 1997
Acknowledgements
This work was supported by grants from FAPERGS
and CNPq (Brazil). Dr. M.R.M. thanks the CNPq for a
visiting scientific grant.
[13] P.A.A. Klusener, J.C. Hanekamp, L. Brandsma, P.V. Schleyer, J.
Org. Chem. 55 (1990) 1311.