Synthesis, structures and catalytic properties of bis(2-pyridylimino)- isoindolatopalladium complexes

Article abstract of DOI:10.1002/ejic.200400179

Reaction of the bis(2-pyridylimino)isoindole derivatives (10-Me)-BPI (1a), (11-Me)-BPI (1b), (11-Br)-BPI (1c), (4-Me)-BPI (1d) and 4-Me-10-tBuBPI (1e) with [PdCl₂(PhCN)₂] and triethylamine in benzene gave the square-planar palladium(

Full text of DOI:10.1002/ejic.200400179

FULL PAPER
Synthesis, Structures and Catalytic Properties of Bis(2-pyridylimino)-
isoindolatopalladium Complexes
Bettina Siggelkow,[a] Markus B. Meder,[a] Christian H. Galka,[a] and Lutz H. Gade*[a]
Keywords: Hydrogenation / N ligands / Palladium
Reaction of the bis(2-pyridylimino)isoindole derivatives (10-
Me)-BPI (1a), (11-Me)-BPI (1b), (11-Br)-BPI (1c), (4-Me)-BPI
(1d) and 4-Me-10-tBuBPI (1e) with [PdCl2(PhCN)2] and tri-
tallated with bis(benzonitrile)dichloropalladium(II) to yield
the PdII complexes [PdCl{11-(Me3SiCC)-BPI}] (5a), [PdCl{11-
(Ph3SiCC)-BPI}] (5b) and [PdCl{11-(PhCC)-BPI}] (5c), respec-
tively. The activity of 2b in the catalytic hydrogenation of C=
C double bonds was tested for the reaction with styrene, 1-
octene and cyclohexene. The stability of the palladium com-
plex, the reproducibility of the reaction kinetics, the different
behaviour towards the three olefins chosen as substrates, as
well as the possibility of isolating the non-decomposed cata-
lyst after several catalytic runs, provides circumstantial evi-
dence for molecular catalysis with the BPI-palladium comple-
xes.
ethylamine in benzene gave the square-planar palladium(II
)
complexes [PdCl{(10-Me)-BPI}] (2a), [PdCl{(11-Me)-BPI}]
(2b), [PdCl{(11-Br)-BPI}] (2c), [PdCl(4-MeBPI)] (2d) and
[PdCl(4-Me-10-tBuBPI)] (2e), respectively. Extraction of the
crude product 2b with aqueous sodium carbonate solution
led to the formation of the dinuclear carbonato-bridged com-
plex [{(11-Me-BPI)Pd}2(µ-CO3)] (3) which was characterized
by an X-ray structure analysis. Reaction of 11-Br-BPI (1c)
with a large excess (6 equiv.) of the acetylenes Me3SiCCH,
Ph3SiCCH and PhCCH under Sonogashira conditions gave
the alkynylated derivatives 11-(Me3SiCC)-BPI (4a), 11-
(Ph3SiCC)-BPI (4b) and 11-(PhCC)-BPI (4c), which were me-
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
this formally protonated site is subsequently involved in the
elimination of the saturated reaction product.
Polydentate ligands have been widely used in the develop-
ment of homogeneous hydrogenation catalysts.[1] In most
cases phosphane or phosphane-heterodonor ligands have
been chosen due to the well-established capacity of the soft
phosphane ligators to stabilize the low-valent intermediates
in the catalytic cycle.[2] A practical disadvantage in the use
of phosphorus-based ligands is their propensity to be oxid-
ized if exposed to air over extended periods of time. This
has encouraged research into non-phosphorus-containing
hydrogenation catalysts which combine molecular stability
with sufficient activity to allow the catalytic hydrogenation
of alkenes at atmospheric dihydrogen pressure.[3]
Costa, Pelagatti et al. have recently studied the hydrogen-
ation activity of palladium() complexes stabilized by po-
lydentate PʝNʝO,[4,5] NʝNʝS,[6] and NʝNʝN ligands.[7]
In particular, the use of tridentate nitrogen donor ligands
gave rise to relatively efficient PdII hydrogenation catalysts.
The activation of dihydrogen is thought to involve the pro-
tonation of a basic site in the polydentate N-ligand and
In view of this work on palladium-catalyzed homo-
geneous hydrogenations we have studied the catalytic ac-
tivity of Pd complexes containing derivatives of the well-
established bis(2-pyridylimino)isoindolate (BPI) ligands
(A).[8Ϫ10] These ligands have been extensively studied in oxi-
dation catalysis;[11] however, there is as yet no report of
their application to other catalytic reactions. This class of
formally anionic ligands appeared to be promising for the
development of new palladium-based hydrogenation cata-
lysts due to their tendency to tautomerise and act as neutral
ligands AЈ, as has been recently established for the free li-
gand in solution and for the Cd complex B by X-ray diffrac-
tion.[12] Given the work by Costa, Pelagatti and co-
workers,[4Ϫ7] this capacity of the BPI ligands was thought
to favour homogeneous hydrogenation activity of their pal-
ladium() complexes.
There are only two previous reports in the literature of
the coordination of BPI ligands to divalent palladium,[13,14]
although with no further investigation of their reactivity. In
this work we report the synthesis and structural characteriz-
ation of several new BPI-Pd complexes, the first results of
the integration of the BPI-ligand unit into more elaborate
molecular architectures and, finally, a first study of the
hydrogenation activity of a BPI-Pd derivative towards sev-
eral alkenes.
[a]
Anorganisch-Chemisches Institut, Universität Heidelberg,
Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
E-mail: lutz.gade@uni-hd.de
3424
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200400179
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435

Bis(2-pyridylimino)isoindolatopalladium Complexes
FULL PAPER
Results and Discussion
Synthesis and Structural Characterization of the BPI-
Palladium Complexes
The bis(2-pyridylimino)isoindole derivatives 1aϪ1e were
prepared according to the synthetic route first described by
Siegl et al. by reaction of a 2-aminopyridine derivative with
an ortho-phthalodinitrile (Scheme 1).[9] A slight modifi-
cation of the reaction conditions — the replacement of n-
butanol by n-hexanol as the solvent — gave significantly
better yields of the ligand precursors than those reported in
the literature.
The preparation of the corresponding square-planar pal-
ladium() complexes 2aϪ2e was carried out in benzene
using [PdCl2(PhCN)2] as the PdII precursor and triethyl-
amine as auxiliary base (Scheme 1). The coordination of
the BPI ligands to palladium() can be conveniently moni-
1
tored by H NMR spectroscopy. The most characteristic
change in the NMR spectra is the coordination shift of the
6-pyridyl protons from ca. δ ϭ 8.4 ppm in the free ligand
to ca. δ ϭ 9.5 ppm in the palladium complexes, and the
disappearance of the NH resonance of the isoindole unit.
Since there is no previous example of an X-ray structure
analysis of a BPI-Pd complex, and in order to establish the
structural details of these compounds, single-crystal X-ray
diffraction studies of compounds [PdCl(11-Br-BPI)] (2c)
and [PdCl(4-Me-10-tBu-BPI)] (2e) were carried out. Their
molecular structures are displayed in Figure 1 and 2,
respectively, and their principal bond lengths and angles are
compared in Table 1.
Both complexes are mononuclear and possess the ex-
pected square-planar coordination geometry. The central
palladium atom is coordinated to the three ligating nitrogen
atoms of the BPI ligand (N1, N3 and N5) as well as to
Scheme 1. Synthesis of the BPI-ligands 1aϪ1e and their pallad-
ation to give the PdII complexes 2aϪ2e
˚
˚
the chloro ligand. The chloropalladium units are slightly bond length is contracted to 1.962(3) A for 2c and 1.957 A
displaced from the molecular plane defined by the three N for 2e. This pattern is consistent with the previously re-
atoms, as is evident from the N1ϪPdϪN5 angles of ported structural data of BPI-transition metal com-
172.0(1)° and 171.0(2)° for 2c and 2e, respectively. This dis- plexes.[9,10] The PdϪCl bond lengths of 2.333(1) A (2c) and
˚
˚
tortion is reflected in an even more pronounced way by the 2.332(3) A (2e) are similar to those found for other chloro-
N3ϪPdϪCl angles [2c: 167.75(9)°; 2e: 166.3(2)°] and may palladium complexes bearing tridentate ligands.[15]
be due to the repulsive interaction of the chloro ligand with
In the metallation of the BPI ligand-precursors stoichio-
the ortho-hydrogen atoms of the pyridyl groups. The PdϪN metric amounts of triethylammonium chloride are formed,
bond lengths to the pyridyl units are in the range of which are usually extracted with water after the complete
˚
2.053Ϫ2.071 A, whereas the amide-type central PdϪN3 conversion into the complexes. In the synthesis of 2b the
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3425

B. Siggelkow, M. B. Meder, C. H. Galka, L. H. Gade
FULL PAPER
Figure 1. Molecular structure of complex 2c; selected bond lengths
and angles are listed in Table 1
Figure 2. Molecular structure of complex 2e; selected bond lengths
and angles are listed in Table 1
Figure 3. a) Molecular structure of complex 3; selected bond
˚
lengths (A) and angles (°): Pd1ϪN1 2.05(1), Pd2ϪN6 2.07(1),
˚
Table 1. Selected bond lengths (A) and angles (°) of complexes 2c
C41ϪO1 1.23(2), Pd1ϪN3 1.93(2), Pd2ϪN8 1.94(1), C41ϪO2
1.34(2), Pd1ϪN5 2.05(1), Pd2ϪN10 2.06(2), C41ϪO3 1.22(2),
Pd1ϪO2 2.04(1), Pd2ϪO1 2.03(1); N1ϪPd1ϪN5 172.5(5),
N1ϪPd1ϪO2 89.7(6), N6ϪPd2ϪO1 90.4(7), N6ϪPd2ϪN10
73.4(5), N3ϪPd1ϪO2 178.3(5), N8ϪPd2ϪO1 175.7(6); b) view
along the PdϪPd axis
and 2e
2c
2e
PdϪN1
PdϪCl
PdϪN5:
C2ϪBr1
2.068(3)
2.333(1)
2.053(3)
1.895(4)
1.962(3)
1.884(4)
92.85(9)
167.75(9)
89.95(8)
172.0(1)
2.071(7)
2.332(3)
2.058(7)
Ϫ
As is evident from the structure represented in Figure 3,
the exchange of the chloro ligands in two of the Pd com-
plexes by a bridging carbonato ligand gives a dinuclear
complex with a stacked arrangement of the two complex
fragments. The relative disposition of the two molecular
halves and their parallel orientation may be due to the com-
bination of a weakly attractive PdϪPd contact and π-stack-
ing interactions between the aromatic rings in the ligands.
PdϪN3
1.957(6)
Ϫ
92.2(2)
166.31(19)
91.1(2)
171.0(2)
C16ϪBr2
ClϪPdϪN1
ClϪPdϪN3
ClϪPdϪN5
N1ϪPdϪN5
˚
The PdϪPd distance of 3.031 A is in the range of previously
crude product was extracted with an aqueous sodium car- established d8-metal-metal contacts.[16] The view along the
bonate solution on one occasion, which led to a partial ex- PdϪPd axis in Figure 3b reveals the slight twist in the
change of the chloro ligand by the carbonate dianion. From orientation of the two planar metal-ligand units
this mixture the dinuclear carbonato-bridged complex (N5ϪPd1ϪPd2ϪN10 ϭ 16.5°).
´
We note that Gagne et al. have reported the crystal struc-
[{(11-Me-BPI)Pd}2(µ-CO3)] crystallized and its structure
was established by a single-crystal X-ray structure analysis. ture of a dinuclear BPI-copper complex containing a bridg-
Its molecular structure is displayed in Figure 3 along with ing carbonato ligand.[9c] In contrast to the Pd complex pre-
2Ϫ
the principal bond lengths and angles.
sented in this work, the CO3 ligand in their Cu complex
3426
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435

Bis(2-pyridylimino)isoindolatopalladium Complexes
FULL PAPER
connects two orthogonally oriented BPI-metal units. Both Synthesis and Structural Characterization of the Alkynyl-
Pd atoms in compound 3 possess an almost ideal square- Substituted BPI-Palladium Complexes
planar coordination geometry and the two halves of the
The synthesis of the corresponding palladium() com-
molecule are structurally almost identical and very similar
plexes was carried out as described above for complexes
to 2c and 2e. The carbonato ligand is almost planar, with
2a؊2e, by reaction of the ligands 4aϪ4c with bis(benzoni-
similar metric parameters to the copper complex mentioned
trile)dichloropalladium() and triethylamine in benzene.
After workup, the orange complexes [PdCl{11-(Me3SiCC)-
above. It is interesting to note the difference in the CϪO
˚
bond lengths [C41ϪO1 1.23(2), C41ϪO3 1.22(2) A,
BPI}] (5a) and [PdCl{11-(Ph3SiCC)-BPI}] (5b) as well as
˚
C41ϪO2 1.34(2) A] in the bridging ligand.
the dark-red compound [{11-(PhCC)-BPI}PdCl] (5c),
respectively, were isolated in good yields (Scheme 3).
The metallation of the BPI ligands 4a and 4b may be
Synthesis of Alkynyl-Substituted BPI Ligands
conveniently monitored by 29Si NMR spectroscopy. The
resonances of the Me3Si-substituted ligand are shifted from
δ ϭ Ϫ17.4 ppm in 4a to δ ϭ Ϫ22.0 ppm in [PdCl{11-(Me3-
SiCC)-BPI}] (5a) and from δ ϭ Ϫ28.5 ppm in 4b to δ ϭ
Ϫ22.1 ppm in [PdCl{11-(Ph3SiCC)-BPI}] (5b). The forma-
tion of the alkynyl-substituted complexes 5a؊5c was con-
firmed by their FAB mass spectra, in which the [M Ϫ Cl]ϩ
cation was found as the principal fragment.
Single crystals of 5a and 5b which were suitable for X-
ray diffraction were obtained from solutions of the com-
pounds in CH2Cl2 (5a) and CH2Cl2/pentane (5b) at ambient
temperature. In order to establish the details of the influ-
ence that the alkynyl substitution exerts upon the molecular
structures of the BPI-palladium complexes, X-ray structure
analyses of both complexes 5a and 5b were carried out.
Their molecular structures are displayed in Figure 4 and 5,
respectively, and their principal bond lengths and angles are
compared in Table 2.
The bis(2-pyridylimino)isoindole ligands give well-de-
fined complex structures and may thus be used as building
blocks in more complex molecular architectures. In order
to test whether the ligand periphery of the BPI ligands may
be modified a posteriori, we studied the alkynylation of the
ligand 1c by the Sonogashira method.[17] The reaction of
11-Br-BPI (1c) with a large excess (6 equiv.) of the acety-
lenes Me3SiCCH, Ph3SiCCH and PhCCH in Et3N using 10
mol % of [Pd(PPh3)4]/CuI gave the alkynylated derivatives
11-(Me3SiCC)-BPI (4a), 11-(Ph3SiCC)-BPI (4b) and 11-
(PhCC)-BPI (4c) as yellow solids in good yields (Scheme 2).
Scheme 2. Synthesis of the alkynyl-substituted BPI ligands 4aϪ4c
Figure 4. Molecular structure of complex 5a; selected bond lengths
and angles are listed in Table 2
The general features of the metal complex structures of
5a and 5b are similar to those of 2c and 2e. As in the case
of the latter, the palladium atom is slightly displaced from
the plane defined by the N-donors, as can be inferred from
the N5ϪPdϪN1 angles [5a: 168.41(6)°; 5b: 167.4(1)°]. The
‘‘bending’’ of the chloro ligands out of the plane of the
BPI-Pd unit is even more pronounced than in 2c and 2e
[N3ϪPdϪCl ϭ 165.30(5)° (5a) and 163.75(8)°(5b)]. This de-
crease of the N3ϪPdϪCl angle may be attributed to in-
creased steric crowding at the 11-position in the series Br Ͻ
Me3Si Ͻ Ph3Si, along with the ortho-H···Cl repulsion, thus
Scheme 3. Synthesis of the alkynyl-substituted BPI-palladium()
complexes 5aϪ5c
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3427

B. Siggelkow, M. B. Meder, C. H. Galka, L. H. Gade
FULL PAPER
Catalytic Hydrogenation of Olefins with [PdCl(4-Me-BPI)]
(2b)
As indicated in the introduction, there is a substantial
interest in the development of molecular non-phosphane-
containing palladium catalysts for homogeneous hydrogen-
ations. A limiting factor is the propensity of many pal-
ladium complexes of that type to undergo degradation un-
der the conditions of the catalytic reaction. Given the sta-
bility of the BPI-Pd complexes and the capacity of the im-
ino units in the ligand framework to act as sites of
intermediate protonation, we hoped that they might hydro-
genate alkenes without decomposition. As a first test system
we chose the complex [PdCl(4-Me-BPI)] (2b) which is sig-
nificantly more soluble in polar organic solvents than the
unsubstituted parent complex. In order to test its activity
towards hydrogenation of CϭC double bonds in different
chemical environments, the hydrogenation of three sub-
strates — styrene, 1-octene and cyclohexene — was investi-
gated.
Figure 5. Molecular structure of complex 5b; selected bond lengths
and angles are listed in Table 2
˚
Table 2. Selected bond lengths (A) and angles (°) of complexes 5a
and 5b
5a
5b
PdϪN1
PdϪN3
PdϪN5
PdϪCl
C6ϪC7
C24ϪC25
2.052(2)
1.958(2)
2.046(2)
2.3350(6)
1.203(3)
1.203(4)
2.034(3)
1.952(2)
2.027(2)
2.3353(8)
C19ϪC20
C39ϪC40
1.190(4)
1.192(4)
N1ϪPdϪN5
ClϪPdϪN3
C2ϪC6ϪC7
C17ϪC39ϪC40
C6ϪC7ϪSi1
C39ϪC40ϪSi2
C21ϪC24ϪC25
C2ϪC19ϪC20
C24ϪC25ϪSi2
C19ϪC20ϪSi1
168.41(6)
165.30(5)
176.8(2)
167.4(1)
163.75(8)
171.1(3)
175.3(3)
177.2(3)
164.2(3)
176.6(2)
179.9(2)
178.7(2)
pushing the Cl ligands out of the plane. The PdϪN bond-
length pattern is again similar to that observed in 2c and
2e, with greater PdϪN distances for the pyridyl groups
˚
˚
[PdϪN5 ϭ 2.046(2) A (5a), 2.027(2) A (5b) and PdϪN1 ϭ
Figure 6. Hydrogenation of styrene at 25 Ϯ 1 °C in THF at a
hydrogen pressure of 1 bar using 2 mol % of the catalyst 2b: a) the
conversion curves for three independent catalytic runs; b) isolation
of the catalyst that had been used in the third run and re-used in
two further catalytic runs
˚
˚
2.052(2) A (5a), 2.034(3) A (5b)] and contracted bond
lengths for the central formally anionic donor [PdϪN3 ϭ
1.958(2) A (5a) 1.952(2) A (5b)].
˚
˚
3428
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435

Bis(2-pyridylimino)isoindolatopalladium Complexes
FULL PAPER
All reactions were carried out at 25 Ϯ 1 °C in THF at a the reaction conditions. This catalyst degradation is evi-
1
hydrogen pressure of 1 bar using 2 mol % of the catalyst 2b. denced by H NMR spectroscopy and the observation of
We first studied the hydrogenation of styrene to ethylben- the proton signal of the free ligand at δ ϭ 8.5 ppm.
zene. The conversion curves for three independent catalytic
As a second substrate, and as an example of a long-chain
runs are displayed in part a of Figure 6 which were carried terminal alkene, the hydrogenation of 1-octene catalyzed by
out under the specified standard conditions and the same 2b was investigated. Of particular interest was the compet-
substrate and catalyst concentrations; in all three cases the ing reaction in this transformation, the isomerization of the
catalyst 2b was isolated without detectible decomposition alkene to a mixture of E- and Z-2-octene. The course of this
after the conversion. In view of this apparent stability of reaction, as followed by GC-MS, is represented in Figure 8.
the catalyst, the sample which had been used in the third
run and had subsequently been isolated, was employed in
two further catalytic runs, again under identical conditions.
As can be seen in part b of Figure 6, this procedure also
did not lead to a significant change in the catalytic activity
of 2b. After each of the three catalytic runs, the solvent and
reaction product were removed in vacuo, the solid residue
1
characterized by H NMR spectroscopy and then used in
the subsequent catalytic conversion. It is evident from the
absence of a signal at δ ϭ 8.5 ppm, which would be due to
the demetallated BPI ligand, that there was no decompo-
sition even after three cycles. The stability of the system is
1
shown by comparison of the H NMR spectra of 2b before
the catalysis (Figure 7, top) with that recorded after the
three cycles of catalysis, isolation of the catalyst and re-use
of the catalyst (Figure 7, bottom). We were not able to de-
tect hydridopalladium intermediates by 1H NMR spec-
troscopy during the course of the catalytic reaction.
Figure 8. Hydrogenation of 1-octene catalyzed by 2b and the con-
comitant isomerization of the alkene to a mixture of E- and Z-2-
octene, as followed by GC-MS
After a short induction period, during which the cata-
lytically active species is generated, the conversion of 1-oc-
tene sets in, giving n-octane and a mixture of Z-2-octene
and E-2-octene. After the complete consumption of 1-oc-
tene, the conversion into n-octane was around 70%, while
27% of the starting material were converted into the mix-
ture of 2-octenes. The hydrogenation of the latter is ex-
tremely slow and practically insignificant within the time-
frame represented in Figure 8.
The lack of activity in the hydrogenation of internal Cϭ
C double bonds was also apparent from the reaction with
cyclohexene. Whereas this substrate is readily hydrogenated
by colloidal or heterogeneous Pd catalysts, it is known to
be converted only very slowly by molecular Pd catalysts.[18]
After 1500 minutes only 5% of the alkene had been con-
verted and even after 9000 minutes the conversion was only
at about 12%. A comparison of the conversion curves for
the hydrogenation of the three alkenes investigated in this
study is given in Figure 9.
1
As previously noted by Elsevier et al. for N-ligand Pd
catalysts, the ‘‘mercury test’’[19] for potential colloidal metal
catalysis is not applicable to palladium compounds such as
2b.[3d,18] However, the stability of complex 2b that we ob-
Figure 7. Top: H NMR spectrum of 2b before the catalysis; bot-
1
tom: H NMR spectrum of the catalyst recorded after three cycles
of catalysis, isolation of the catalyst, and re-use of the catalyst
We found that if the hydrogenation is carried out in meth- served in the catalytic hydrogenations, the reproducibility of
anol instead of THF as solvent, the palladium complex de- the reaction kinetics, the different behaviour towards the
composes during the course of the reaction leading to the three olefins chosen as substrates and, finally, the possibility
precipitation of palladium black, which is inactive under of isolating the non-decomposed catalyst after several cata-
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3429

B. Siggelkow, M. B. Meder, C. H. Galka, L. H. Gade
FULL PAPER
dium() complexes. The possibility of modifying the periph-
eral ligand structure after the assembly of the BPI unit has
been demonstrated by the Sonogashira alkynylation of a
bromopyridyl derivative. This provides the first example of
a possible modular variation of these ligands which is of
particular interest in catalyst design based on these systems.
A detailed study into the hydrogenation activity of one of
the Pd complexes has established a novel active molecular
catalyst for alkene hydrogenation. Current and future work
is aimed towards the elucidation of the mechanism of this
catalytic reaction.
Experimental Section
All manipulations were performed under nitrogen. Solvents were
dried according to standard methods and saturated with nitrogen.
The deuterated solvents used for the NMR spectroscopic measure-
ments were degassed by three successive ‘‘freeze-pump-thaw’’ cycles
Figure 9. A comparison of the conversion curves for the hydrogen-
ation of styrene, 1-octene and cyclohexene
˚
and stored over 4 A molecular sieves. Solids were separated from
lytic runs, provides strong circumstantial evidence for mo-
lecular catalysis with the BPI-palladium complex.
Although the mechanistic details of the catalytic cycle re-
main to be established, and no reaction intermediates could
be detected to date, a reaction sequence based on the mech-
anistic proposal by Costa, Pelagatti and co-workers,[4Ϫ7] is
put forward in Scheme 4. It takes the previously observed
possibility of imino-N protonation in the ligand framework
into account.[12] Preliminary studies with the other BPI de-
rivatives reported in this work indicate an essentially simi-
lar behaviour.
suspensions by filtration through dried Celite or by centrifugation.
1
The H, 13C and 29Si NMR spectra were recorded on Bruker AC
200, Bruker Avance 250 and Bruker AMX 400 FT NMR spec-
trometers, respectively [reference: tetramethylsilane, using the re-
sidual protonated solvent peak (1H) or the carbon resonance (13C)].
Infrared spectra were recorded on a Nicolet Magna IRTM 750
spectrometer. Elemental analyses were carried out by the microana-
lytical service at the Chemistry Department of the University of
Strasbourg. (10-Me)-BPI (1a), (11-Me)-BPI (1b), (11-Br)-BPI (1c),
(4-Me)-BPI (1d)[9] and [PdCl2(PhCN)2][20] were prepared according
to published procedures. All other chemicals used as starting mate-
rials were obtained commercially and used without further purifi-
cation.
Conclusion
Preparation of 4-Me-10-tBuBPI (1e): 4-Methylphthalodinitrile
(1.50 g, 10.6 mmol) and 2-amino-4-(tert-butyl)pyridine (3.96 g ϭ
26.1 mmol) were heated unter reflux in hexanol in the presence of
In this paper we have reported the first detailed synthetic
and structural study of bis(2-pyridylimino)isoindolatopalla- a catalytic amount of CaCl2 (0.16 g, 1.36 mmol) for 18 h. After
Scheme 4. Proposed mechanism of the Pd-catalyzed hydrogenation
3430
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435

Bis(2-pyridylimino)isoindolatopalladium Complexes
FULL PAPER
cooling to room temperature, the solid reaction product was iso-
lated by filtration washed three times with 50 mL of water and then
dried in a dessiccator over P4O10 to give compound 1e as a crystal-
1
line yellow solid. Yield: 2.53 g (5.94 mmol, 56%). M.p. 204 °C. H
NMR (400.16 MHz, C6D6): δ ϭ 1.1, 1.2 (each s, each 9 H, 10-tBu),
3
2.05 (s, 3 H, 4-CH3), 6.84 (m, 2 H, 11-H), 6.94 (br. d, JH,H
ϭ
7.9 Hz, 1 H, 5-H), 7.72 (m, 2 H, 9-H), 8.02 (br. s, 1 H, 3-H), 8.12
3
3
(d, JH,H ϭ 7.9 Hz, 1 H, 6-H), 8.60 (d, JH,H ϭ 5.3 Hz, 2 H, 12-
H), 11.91 (br. s, 1 H, NϪH) ppm. 13C{1H} NMR (100.6 MHz,
C6D6): δ ϭ 21.6 (4-CH3), 30.4 [10-C(CH3)3], 34.5 [10-C(CH3)3],
117.7 (C-11), 121.1 (C-9), 122.9 (C-5), 123.6 (C-6), 132.8 (C-3),
137.2 (C-1, C-2), 141.9 (C-4), 148.1 (C-12), 154.1 (C-7), 161.8 (C-
8, C-10) ppm. IR (KBr): ν˜ ϭ 3237 (m, br), 2962 (m), 2867 (w),
1633 (m), 1590 (s), 1534 (w), 1477 (w), 1401 (w), 1365 (w), 1354
(w), 1310 (vw), 1285 (w), 1265 (w), 1219 (w), 1201 (vw), 1180 (vw),
[PdCl{(11-Me)-BPI}] (2b): Yield: 98%. M.p.: 280 °C. 1H NMR
(300.17 MHz, CD2Cl2, 295 K): δ ϭ 2.38 (s, 6 H, CH3), 7.43 (d,
1108 (vw), 1037 (vw), 928 (m), 890 (m), 826 (m), 716 (m) cmϪ1
.
3
4
3JH,H ϭ 8.2 Hz, 2 H, H-9), 7.61 (dd, JH,H ϭ 5.5, JH,H ϭ 2.9 Hz,
C27H31N5 (425.57): calcd. C 76.20, H 7.34, N 16.46; found C 76.48,
H 7.36, N 16.25.
2 H, H-5), 7.68 (dd, 3JH,H ϭ 8.2, 4JH,H ϭ 2.2 Hz, 2 H, H-10), 7.95
3
4
4
(dd, JH,H ϭ 5.5, JH,H ϭ 2.9 Hz, 2 H, H-6), 9.64 (d, JH,H
ϭ
2.2 Hz, 2 H, H-12) ppm. 13C{1H} NMR (75.48 MHz, CD2Cl2,
295 K): δ ϭ 18.1 (CH3), 122.0 (C-5), 125.8 (C-9), 129.8 (C-11),
131.2 (C-6), 137.9 (C-1,2), 140.5 (C-10), 150.2 (C-12), 152.7 (C-7/
8), 152.9 (C-7/8) ppm. IR (KBr): ν˜ ϭ 2920 (br), 1620 (w), 1587 (s),
1576 (s), 1482 (w), 1473 (s), 1375 (s), 1302 (w), 1243 (w), 1189 (w),
1143 (vw), 1100 (s), 912 (w), 832 (w), 692 (s) cmϪ1. C20H16ClN5Pd
(468.25): calcd. C 51.30, H 3.44, N 14.96; found C 51.75, H 3.30,
N 14.46.
General Procedure for the Preparation of the Palladium(II) Com-
plexes 2a؊2e: The bis(2-pyridyl)isoindole (BPI) derivative (in
general 0.3 mmol) together with 1.1 molar equivalents of
[PdCl2(PhCN)2] and 1.1 molar equivalents of NEt3 were dissolved
in benzene and stirred at room temperature for two days. De-
pending on the substitution pattern of the ligand, the palladium
complex either precipitated directly from the reaction mixture or
remained in solution. For compounds 2aϪ2d direct precipitation
of the reaction product was observed and the resulting solid was
separated by filtration. The co-product NEt3HCl was extracted
from the solid by extraction three times with 50 mL of water and
the crude product thus obtained was recrystallized from CH2Cl2/n-
hexane. In the case of complex 2e the reaction product remained
in solution. After removal of the solvent and the volatiles in vacuo,
the solid residue was extracted with 10 mL of benzene and the
solvent of the extract evaporated in vacuo. After washing three
times with 50 mL of water and 10 mL of hexane, the crude product
thus obtained was recrystallized from CH2Cl2/n-hexane. Com-
pounds 2aϪ2e are deep yellow-ochre crystalline solids.
[PdCl{(11-Br)-BPI}] (2c): Yield: 34%. M.p.: 202 °C. 1H NMR
3
(400.13 MHz, CDCl3, 295 K): δ ϭ 7.47 (d, JH,H ϭ 8.7 Hz, 2 H,
H-9), 7.64 (dd, 3JH,H ϭ 8.7, 4JH,H ϭ 2.2 Hz, 2 H, H-10), 8.06Ϫ8.09
4
(m, 4 H, H-5,6), 10.07 (d, JH,H ϭ 2.2 Hz, 2 H, H-12) ppm.
13C{1H} NMR (75.5 MHz, CD2Cl2, 295 K): δ ϭ 114.9 (C-11),
122.7 (C-5), 127.4 (C-9), 131.6 (C-6), 137.4 (C-1,2), 141.9 (C-10),
148.6 (C-12), 150.7 (C-8), 153.7 (C-7) ppm. FAB-MS: m/z ϭ 562
[M Ϫ Cl]ϩ. IR (KBr): ν˜ ϭ 3450 (br), 3110 (vw), 2962 (w), 2924
(vw), 2361 (vw), 1640 (w), 1598 (w), 1563 (s), 1518 (s), 1454 (s),
1361 (m), 1320 (vw), 1290 (vw), 1261 (m), 1232 (vw), 1185 (s), 1098
(s), 1020 (s), 915 (w), 860 (w), 839 (w), 801 (s), 702 (w), 684 (w)
cmϪ1. C18H10Br2ClN5Pd (597.99): calcd. C 36.15, H 1.68, N 11.71;
found C 36.74, H 2.01, N 11.60.
[PdCl{(10-Me)-BPI}] (2a): Yield: 45%. M.p. 287 °C (dec.). 1H
NMR (300.17 MHz, CDCl3, 295 K): δ ϭ 2.41 (s, 6 H, CH3), 6.88
3
(d, JH,H ϭ 6.6 Hz, 2 H, H-11), 7.40 (s, 2 H, H-9), 7.60 (m, 2 H,
H-5), 8.01 (m, 2 H, H-6), 9.67 (d, 3JH,H ϭ 6.6 Hz, 2 H, H-12) ppm.
13C{1H} NMR (100.61 MHz, CDCl3, 295 K): δ ϭ 20.6 (CH3),
121.3 (C-11), 122.2 (C-9), 126.6 (C-5), 131.3 (C-6), 137.9 (C-1,2),
149.9 (C-7/8/10/12), 151.2 (C-7/8/10/12), 152.7 (C-7/8/10/12), 153.8
(C-7/8/10/12) ppm. IR (KBr): ν˜ ϭ 1581 (vs), 1517 (s), 1466 (s),
1402 (vw), 1376 (w), 1295 (s), 1315 (w), 1180 (s), 1098 (vs), 944 (w)
cmϪ1. C20H16ClN5Pd (468.25): calcd. C 51.30, H 3.44, N 14.96;
found C 50.97, H 2.89, N 15.38.
[PdCl(4-MeBPI)] (2d): Yield: 63%. M.p.: Ͼ165 °C (dec.). 1H NMR
(200.14 MHz, CD2Cl2, 298 K): δ ϭ 2.37 (s, 3 H, 4-CH3), 6.92 (m,
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3431

B. Siggelkow, M. B. Meder, C. H. Galka, L. H. Gade
FULL PAPER
2 H, 11-H), 7.25 (d, JH,H ϭ 7.7 Hz, 1 H, 5-H), 7.36 (d, JH,H
3
3
ϭ
(11-TMS-ethynyl)-BPI (4a): Yield: 50%. M.p.: 168 °C. 1H NMR
3
7.5 Hz, 2 H, 9-H), 7.60 (br. s, 1 H, 3-H), 7.65 (d, JH,H ϭ 7.7 Hz, (300.17 MHz, CDCl3, 295 K): δ ϭ 0.29 (s, 18 H, CH3), 7.32 (d,
3
3
1 H, 6-H), 7.71 (m, 2 H, 10-H), 9.63 (d, JH,H ϭ 6.2 Hz, 2 H, 12-
3JH,H ϭ 7.4 Hz, 2 H, H-9), 7.58 (s, 2 H, H-5), 7.77 (dd, JH,H
ϭ
H) ppm. 13C{1H} NMR (75.5 MHz, [D6]DMSO, 353 K): δ ϭ 21.3
7.4, 4JH,H ϭ 3.6 Hz, 2 H, H-10), 7.97 (s, 2 H, H-6), 8.66 (d, 3JH,H ϭ
(4-CH3), 121.2 (C-11), 123.5 (C-9), 124.2 (C-5), 128.0 (C-6), 133.8 3.6 Hz, 2 H, H-12), 13.72 (s, 1 H, NϪH) ppm. 13C{1H} NMR
(C-3), 136.8 (C-1), 139.6 (C-2), 140.9 (C-10), 144.0 (C-4), 153.6 (C-
(75.48 MHz, CDCl3, 295 K): δ ϭ 0.9 (CH3), 98.2 (C-Si), 102.2 (C-
8), 155.4 (C-7 u. C-12) ppm. IR (KBr): ν˜ ϭ 2917 (w), 1644 (w), Caryle), 116.3 (C-11), 122.6 (C-9), 128.3 (C-5), 131.7 (C-6), 135.5
1579 (s), 1530 (s), 1487 (vw), 1461 (s), 1427 (m), 1367 (m), 1320 (C-1,2), 140.8 (C-10), 150.9 (C-12), 153.8 (C-7), 159.2 (C-8) ppm.
(w), 1289 (m), 1215 (vw), 1182 (w), 1135 (m), 1079 (w), 1016 (w), 29Si NMR (79.5 MHz, CDCl3, 295 K): δ ϭ Ϫ17.4 ppm. IR (KBr):
873 (vw), 826 (vw), 770 (m), 708 (vw) cmϪ1. C19H14ClN5Pd ν˜ ϭ 2959 (s), 2155 (s), 1624 (s), 1566 (s), 1465 (s), 1360 (w), 1307
(454.04): calcd. 50.22, H 3.11, N 15.42; found C 49.84, H 3.21,
N 15.23.
(vw), 1251 (w), 1220 (s), 1096 (w), 1036 (w), 925 (vw), 872 (s), 843
(s), 758 (w), 695 (w) cmϪ1. C28H29N5Si2 (491.74): calcd. C 68.39,
H 5.94, N 14.24; found C 68.52, H 6.51, N 13.63.
1
[PdCl(4-Me-10-tBuBPI)] (2e): Yield: 73%. M.p.: 192 °C (dec.). H
NMR (400.16 MHz, CD2Cl2, 298 K): δ ϭ 1.27 (s, 18 H, 10-tBu),
3
2.39 (s, 3 H, 4-CH3), 6.93 (m, 2 H, 11-H), 7.25 (br. d, JH,H
ϭ
(11-Ph3Si-ethynyl)-BPI (4b): Yield: 69%. M.p.: 198 °C. 1H NMR
(300.17 MHz, CDCl3, 295 K): δ ϭ 7.37Ϫ7.72 (m, 34 H, PhϪH, H-
5, H-9), 7.91 (d, JH,H ϭ 7.0 Hz, 2 H, H-10), 8.07 (s, 2 H, H-6),
7.6 Hz, 1 H, 5-H), 7.35 (m, 2 H, 9-H), 7.57 (br. s, 1 H, 3-H), 7.61
3
(d, JH,H ϭ 7.6 Hz, 1 H, 6-H), 9.51 (m, 2 H, 12-H) ppm. 13C{1H}
3
NMR (100.6 MHz, CD2Cl2, 298 K): δ ϭ 22.3 (4-CH3), 30.5 [10-
C(CH3)3], 35.4 [10-C(CH3)3], 118.2 (C-11), 122.4 (C-5), 123.0 (C-
6), 123.6 (C-9), 132.6 (C-3), 135.9 (C-1), 138.7 (C-2), 142.6 (C-4),
152.4 (C-7/C-8), 153.5 (C-12), 154.1 (C-7/C-8), 164.4 (C-10) ppm.
IR (KBr): ν˜ ϭ 2962 (m), 2867 (w), 1577 (s), 1559 (w), 1521 (w),
1507 (m), 1477 (m), 1402 (w), 1368 (w), 1319 (vw), 1296 (w), 1262
(w), 1214 (vw), 1181 (m), 1145 (w), 1114 (m), 1048 (m), 1022 (w),
949 (vw), 920 (vw), 890 (vw), 797 (w), 714 (w) cmϪ1. C27H30ClN5Pd
(566.44): calcd. C 57.25, H 5.34, N 12.36; found C 57.08, H 5.50,
N 12.16.
8.82 (s, 2 H, H-12), 13.77 (s, 1 H, NϪH) ppm. 13C{1H} NMR
(100.61 MHz, CDCl3, 295 K): δ ϭ 82.0 (CϵCSi), 91.7 (CϵCSi),
106.0 (C-Ph), 116.1 (C-11), 122.5 (C-5/9), 123.0 (C-5/9), 127.9 (C-
Ph), 129.8 (C-Ph), 130.1 (C-Ph), 131.9 (C-6), 135.5 (C-1,2), 141.1
(C-10), 151.0 (C-12), 153.7 (C-7), 158.4 (C-8) ppm. 29Si NMR
(79.5 MHz, CDCl3, 295 K): δ ϭ Ϫ28.5 ppm. FAB-MS: m/z ϭ 864
ϩ
[M ϩ H] . IR (KBr): ν ϭ 3304 (br), 2935 (w), 2676 (s), 2070 (s),
1623 (vs), 1565 (vs), 1459 (s), 1428 (vs), 1185 (w), 1113 (vs), 1035
(w) cmϪ1. C58H41N5Si2 (864.17): calcd. C 80.61, H 4.78, N 8.10;
found C 80.36, H 4.33, N 7.72.
˜
(11-Ph-ethynyl)-BPI (4c): Yield: 77%. M.p.: 246 °C. 1H NMR
(300.17 MHz, CD2Cl2, 295 K): δ ϭ 7.39Ϫ7.45 (m, 10 H, PhϪH),
7.60 (d, JH,H ϭ 7.9 Hz, 2 H, H-9), 7.68Ϫ7.70 (dd, JH,H ϭ 5.5,
General Procedure for the Preparation of the Alkynyl-Substituted
Ligands 4a؊4c: The BPI derivative 1c (0.7 mmol), six molar equiv-
alents of the substituted acetylene, 0.2 molar equivalents of CuI
and 0.2 molar equivalents of tetrakis(triphenylphosphane)pallad-
3
3
3
4
4JH,H ϭ 3.0 Hz, 2 H, H-5), 7.89Ϫ7.93 (dd, JH,H ϭ 7.9, JH,H
ϭ
2.2 Hz, 2 H, H-10), 8.05 (dd, 3JH,H ϭ 5.5, 4JH,H ϭ 2.9 Hz, 2 H, H-
4
ium(0) were stirred in 10 mL of triethylamine at 60 °C. The reaction 6), 8.84 (d, JH,H ϭ 2.2 Hz, 2 H, H-12), 14.07 (s, 1 H, NϪH) ppm.
time was 6 d for 4a, 4 d for 4b and 24 h for 4c. After cooling the
reaction mixture to ambient temperature, the solvent was removed
in vacuo. The residue was redissolved in 10 mL of CH2Cl2, the
solution extracted with 10 mL of water and then dried over mag-
nesium sulfate. The evaporation of the solvent in vacuo yielded the
reaction products as pure yellow microcrystalline solids.
13C{1H} NMR (75.48 MHz, CDCl3, 295 K): δ ϭ 86.5 (CϵC), 92.8
(CϵC), 107.2 (C-Ph), 116.6 (C-11), 122.6 (C-9), 127.6 (C-5), 128.4
(C-Ph), 128.6 (C-Ph), 129.5 (C-Ph), 131.6 (C-6), 135.3 (C-1,2),
140.4 (C-10), 150.5 (C-12), 153.8 (C-7), 158.9 (C-8) ppm. IR (KBr):
ν˜ ϭ 3278 (br), 2962 (s), 2145 (vw), 1638 (s), 1571 (s), 1492 (w),
1463 (w), 1457 (vw), 1261 (s), 1220 (vw), 1095 (s), 1019 (s), 800 (s),
3432
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435

Bis(2-pyridylimino)isoindolatopalladium Complexes
FULL PAPER
693 (vw) cmϪ1. C34H21N5 (499.57): calcd. C 81.74, H 4.23, N 14.02;
found C 82.33, H 4.87, N 14.59.
[PdCl{(11-Ph-ethynyl)-BPI}] (5c): Yield: 136 mg (212 µmol, 53%).
M.p.: 150 °C. 1H NMR (300.17 MHz, CDCl3, 295 K): δ ϭ 7.35
(m, 8 H, PhϪH), 7.46 (d, 3JH,H ϭ 7.0 Hz, 2 H, H-9), 7.54 (m, 4 H,
PhϪH, H-5), 7.85 (d, 3JH,H ϭ 7.0 Hz, 2 H, H-10), 7.92 (s, 2 H, H-
6), 10.07 (s, 2 H, H-12) ppm. 13C{1H} NMR (100.61 MHz, CDCl3,
295 K): δ ϭ 85.2 (CϵC), 94.0 (CϵC), 116.6 (C-11), 122.4 (C-5),
126.0 (C-9), 128.4 (C-Ph), 128.9 (C-Ph), 131.4 (C-Ph), 131.8 (C-
Ph), 132.1 (C-6), 137.4 (C-1,2), 140.9 (C-10), 150.4 (C-12), 153.7
(C-7), 156.2 (C-8) ppm. FAB: m/z ϭ 604 [M Ϫ Cl]ϩ. IR (KBr):
ν˜ ϭ 2963 (s), 2217 (w), 1560 (s), 1491 (w), 1459 (s), 1364 (w), 1261
(s), 1185 (w), 1097 (vs), 1022 (vs) cmϪ1. C34H20ClN5Pd (640.44).
calcd.: calcd. C 63.76, H 3.15, N 10.94; found C 63.32, H 2.99,
N 10.63.
Preparation of Complexes 5a؊5c: The preparation of complexes 5a
and 5c was carried out using 0.3 mmol of the ligand precursors 4a
and 4c following the procedure described for 2e. Complex 5b was
prepared on the same scale as described above for 2aϪ2d. The
alkynyl-substituted complexes were obtained as orange or orange-
red crystalline solids.
[PdCl{(11-TMS-ethynyl)-BPI}](5a): Yield: 49%. M.p.: 197 °C
(dec.). 1H NMR (300.17 MHz, CDCl3, 295 K): δ ϭ Ϫ0.26 (s, 18
3
H, CH3), 7.45 (d, JH,H ϭ 9.0 Hz,, 2 H H-9), 7.58 (m, 2 H, H-5),
3
4
7.82 (dd, JH,H ϭ 9.0, JH,H ϭ 2.2 Hz, 2 H, H-10), 7.96 (m, 2 H,
H-6), 9.91 (d, JH,H ϭ 2.2 Hz, 2 H, H-12) ppm. 13C{1H} NMR
4
(100.61 MHz, CDCl3, 295 K): δ ϭ 99.9 (CϵCSi), 100.2 (CϵCSi),
116.4 (C-11), 122.4 (C-9), 125.9 (C-5), 131.5 (C-6), 137.5 (C-1,2),
141.4 (C-10), 150.7 (C-12), 153.9 (C-7), 156.6 (C-8) ppm. 29Si NMR
(79.5 MHz, CDCl3, 295 K): δ ϭ Ϫ22.0 ppm. FAB-MS: m/z ϭ 596
[M Ϫ Cl]ϩ. IR (KBr): ν˜ ϭ 2959 (w), 2145 (w), 1560 (s), 1474 (s),
1459 (vs), 1364 (w), 1288 (w), 1248 (w), 1185 (w), 1099 (s) cmϪ1
.
C28H28ClN5PdSi2 (632.61): calcd. C 53.16, H 4.46, N 11.07; found
C 53.02, H 4.18, N 10.89.
Catalyst Testing: The catalyst tests were carried out in THF at 1
bar H2 pressure using 2 mol % of palladium catalyst (the catalyst
concentration being ca. 1.5 µmol·mLϪ1). The course of the catalytic
hydrogenations was monitored by GC/MS performed with a Shim-
adzu GC-17A/GCMS-QP5050A. Column: SGE BPX5, 5% phenyl,
polysilylphenylene-siloxane, nonpolar, 30 m, 0.22 mm, carrier gas
He. The products were analyzed by comparison of the recorded
mass spectra and retention times with those of authentic samples.
The measured relative ratio of the products was calibrated by com-
parative measurements with known substance ratios using pure
substances.
GC/MS Parameters for Styrene Hydrogenation: T (start) ϭ 50 °C,
T (injector) ϭ 250 °C, T (interface) ϭ 280 °C, 30.0 m (0.22 mm),
0.7 mL/min He (flow rate), 66.3 kPa (column pressure), tempera-
ture program: 5.0 min, 50 °C; 2 °C/min, 80 °C; 20 °C/min, 250 °C;
retention times: tR (ethylbenzene) ϭ 7.84 min, tR (styrene) ϭ
9.12 min,
1
[PdCl{(11-Ph3Si-ethynyl)-BPI}] (5b): Yield: 42%. M.p.: 202 °C. H
NMR (300.18 MHz, CDCl3, 295 K): δ ϭ 7.37Ϫ7.71 (m, 34 H,
HϪPh, H-5,9), 7.92 (d, JH,H ϭ 8.8 Hz, 2 H, H-10), 8.04 (m, 2 H,
3
H-6), 10.11 (s, 2 H, H-12) ppm. 13C{1H} NMR (75.48 MHz,
CDCl3, 295 K): δ ϭ 82.2 (CϵC), 95.1 (CϵC), 104.5 (C-Ph), 115.9
(C-11), 122.6 (C-9), 126.1 (C-5), 128.1 (C-Ph), 130.1 (C-Ph), 131.8
(CϪPh, C-6), 132.2 (CϪPh, C-8), 132.8 (C-Ph), 137.6 (C-1,2),
141.6 (C-10), 151.2 (C-12), 154.3 (C-7), 157.1 (C-8) ppm. 29Si NMR
(79.5 MHz, CDCl3, 295 K): δ ϭ Ϫ22.1 ppm. FAB-MS: m/z ϭ 968
[M Ϫ Cl]ϩ. IR (KBr): ν˜ ϭ 3065 (s), 2155 (s), 2070 (s), 1624 (s),
1566 (vs), 1483 (w), 1459 (s), 1425 (s), 1359 (vw), 1304 (vw), 1262
(vw), 1218 (w), 1185 (w), 1113 (s), 1028 (w), 997 (w), 846 (vw), 818
GC/MS Parameters for 1-Octene Hydrogenation: T (start) ϭ 35 °C,
T (injector) ϭ 250 °C, T (interface) ϭ 280 °C, 30.0 m (0.22 mm),
1.5 mL/min He (flow rate), 133.2 kPa (column pressure), tempera-
ture program: 8.0 min, 35 °C; 30 °C/min, 250 °C; tR (1-octene) ϭ
5.62 min, tR (n-octane) ϭ 5.93 min, tR [(cis/trans)-2-octene] ϭ
6.35 min.
GC/MS Parameters for Cyclohexene Hydrogenation: T (start) ϭ 35
(w) cmϪ1. C58H40ClN5PdSi2 (1003.0): calcd. C 69.31, H 4.01, N °C, T (injector) ϭ 250 °C, T (interface) ϭ 280 °C, 30.0 m
6.97; found C 69.83, H 4.55, N 6.35.
(0.22 mm), 1.5 mL/min He (flow rate), 133.2 kPa (column press-
3433
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

B. Siggelkow, M. B. Meder, C. H. Galka, L. H. Gade
FULL PAPER
Table 3. X-ray experimental data of compounds 2c, 2e, 3, 5a, and 5b
2c
2e
3
5a
5b
Formula
C39H26Br4Cl8N10Pd2
1450.77
monoclinic
C2/c
12.8115(3)
13.4458(3)
26.3815(7)
Ϫ
91.723(5)
Ϫ
4542.4(2)
4
C31.5H40Cl5N5Pd
772.34
C87H82Cl10N20O10Pd4
C29H30Cl3N5PdSi2
717.53
C58H40ClN5PdSi2
1005.02
Formula mass
Crystal system
Space group
2347.88
orthorhombic
Pbcn
27.7458(5)
14.4426(6)
23.158(1)
Ϫ
triclinic
triclinic
triclinic
¯
¯
¯
P1
P1
P1
˚
a (A)
7.6784(15)
14.752(3)
15.751(3)
74.79(3)
85.90(3)
88.83(3)
1717.2(6)
2
8.3844(1)
12.8717(3)
15.9248(4)
77.111(5)
84.970(5)
80.587(5)
1650.42(6)
2
9.0527(2)
14.2176(2)
19.3151(4)
74.634(5)
88.341(5)
82.949(5)
2378.99(8)
2
˚
b (A)
˚
c (A)
α (°)
β (°)
γ (°)
Ϫ
Ϫ
3
˚
V (A )
9279.9(6)
4
1.68
4712
1.120
Z
ρcalcd. (g·cmϪ3
F000
)
2.12
2792
4.826
1.49
790
0.959
1.44
728
0.905
1.40
1028
0.542
µ (mmϪ1
)
Temperature (K)
Wavelength (A)
173
0.71073
193
0.71073
173
0.71073
173
0.71073
173
0.71073
˚
Radiation
Number of data meas.
Mo-Kα graphite monochromated
8979
5053
19840
10278
16796
Number of data with
I Ͼ 3σ(I)
Number of variables
3684
285
3435 (I Ͼ 2 σ(I)]
494
3886
589
5878
361
7055
604
R
Rw
wR2
GOF
0.029
0.039
Ϫ
0.072
Ϫ
0.186
1.081
0.081
0.100
Ϫ
0.027
0.034
Ϫ
0.036
0.046
Ϫ
1.006
1.006
1.030
1.039
Largest peak in final
Ϫ3
˚
difference (e·A
)
0.301
1.204
1.450
0.308
0.669
ure), temperature program: 8.0 min, 35 °C; 30 °C/min, 250 °C; tR conts/retrieving.html [or from the Cambridge Crystallographic
(cyclohexane) ϭ 2.49 min, tR (cyclohexene) ϭ 2.74 min.
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax:
ϩ44-1223-336033; E-mail: deposit@ccdc.cam.ac.uk].
X-ray Crystallographic Study of 2c, 2e, 3, 5a and 5b: Suitable crys-
tals of the complexes 2c, 2e, 3, 5a and 5b were obtained by layering
concentrated solutions of the compounds in dichloromethane or
chloroform with hexanes and allowing slow diffusion at room tem-
perature. The crystal data for 2c, 3, 5a and 5b were collected on a
Nonius Kappa CCD diffractometer at Ϫ100 °C and transferred to
a DEC Alpha workstation; for all subsequent calculations the Non-
ius OpenMoleN package was used.[21] The data for 2e were col-
lected on a CAD4 (EnrafϪNonius) four-circle diffractometer at
Ϫ80 °C and the structure solution was carried out using the
SHELX-97 structure-solution package.
Acknowledgments
We thank the Deutsche Forschungsgemeinschaft, the CNRS, and
the Institut Universitaire de France for funding. We are grateful to
´
Dr. Andre DeCian and Natalie Gruber for carrying out the X-ray
diffraction studies.
[1]
Early work: [1a] T. P. Dang, H. B. Kagan, J. Chem. Soc., Chem.
[1b]
Commun. 1968, 481.
W. S. Knowles, M. J. Sabacky, B. D.
Vineyard, J. Chem. Soc., Chem. Commun. 1972, 10Ϫ11.
[1c]
H.
B. Kagan, T. P. Dang, J. Am. Chem. Soc. 1972, 94, 6429Ϫ6433.
All structures were solved by direct methods with absorption cor-
rections being part of the scaling procedure of the data reductions.
After refinement of the heavy atoms, difference Fourier maps re-
vealed the maxima of residual electron density close to the posi-
tions expected for the hydrogen atoms; they were introduced as
fixed contributors in the structure-factor calculations with fixed co-
[1d]
M. D. Fryzuk, B. Bosnich, J. Am. Chem. Soc. 1977, 99,
[1e]
6262Ϫ6267.
M. D. Fryzuk, B. Bosnich, J. Am. Chem. Soc.
[1f]
1978, 100, 5491Ϫ5494.
H. Brunner, W. Pieronczyk, Angew.
Chem. 1979, 91, 655Ϫ656; Angew. Chem. Int. Ed. Engl. 1979,
[1g]
18, 620Ϫ621.
W. S. Knowles, Acc. Chem. Res. 1983, 16,
[1h]
106Ϫ112.
H. Takaya, K. Massima, K. Koyano, M. Yagi,
˚
ordinates (CϪH: 0.95 A) and isotropic temerature factors [B(H) ϭ
H. Kumobayashi, T. Taketomi, S. Akutagawa, R. Noyori, J.
Org. Chem. 1986, 51, 629Ϫ635.
2
˚
1.3 Beqv(C) A ] but not refined. The hydrogen atoms of the solvents
were not refined. Full least-square refinements on F2. A final differ-
ence map revealed no significant maxima of electron density. The
scattering factor coefficients and the anomalous dispersion coef-
ficients were taken from the literature.[22] Crystal data and exper-
imental details for the crystals of 2c, 2e, 3, 5a and 5b are given
in Table 3.
[2] [2a]
J. Halpern, in Organotransition Metal Chemistry (Eds.: Y.
Ishida, M. Tsutsui), Pergamon Press, New York, 1975, p. 106.
[2b]J. Halpern, T. Okamoto, A. Zakhariev, J. Mol. Catal. 1977,
2, 65Ϫ68.
[2c]
B. R. James, in Comprehensive Organometallic
Chemistry, vol. 8 (Eds.: G. Wilkinson, F. G. A. Stone, E. W.
Abel), Pergamon Press, Oxford, 1982, p. 285Ϫ370.
[2d]
H.
Brunner, in Applied Homogeneous Catalysis with Organometal-
lic Compounds, vol. 1 (Eds.: B. Cornils, W. A. Herrmann),
VCH, Weinheim, 1996, p. 201Ϫ219.
CCDC-232252 to -232256 (for 2c, 2e, 3, 5a and 5b, respectively)
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge at www.ccdc.cam.ac.uk/
[3] [3a]
B. C. Y. Hui, W. K. Teo, G. L. Rempel, Inorg. Chem. 1973,
3434
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435

Bis(2-pyridylimino)isoindolatopalladium Complexes
FULL PAPER
O. P. Anderson, A. la Cour, A. Dodd, A. D. Garrett, M. Wich-
olas, Inorg. Chem. 2003, 42, 4513Ϫ4515.
[3b]
[12]
[13]
[14]
[15]
12, 757Ϫ762.
365Ϫ398.
M. Cais, Chim. Ind. (Milan) 1979, 61,
[3c]
M. Sodeoka, M. Shibasaki, J. Org. Chem. 1985,
50, 1147Ϫ1149. [3d] R. van Asselt, C. J. Elsevier, J. Mol. Catal.
1991, 65, L13ϪL19.
R. J. Letcher, W. Zhang, C. Bensimon, R. J. Crutchley, Inorg.
Chim. Acta 1993, 210, 183Ϫ191.
[4]
[5]
[6]
´
A. Bacchi, M. Carcelli, M. Costa, A. Leporati, E. Leporati,
P. Pelagatti, C. Pelizzi, G. Pelizzi, J. Organomet. Chem. 1997,
535, 107Ϫ120.
P. Pelagatti, A. Bacchi, M. Carcelli, M. Costa, A. Fochi, P.
Ghiaini, E. Leporati, M. Masi, C. Pelizzi, G. Pelizzi, J. Or-
ganomet. Chem. 1999, 583, 94Ϫ105.
P. Pelagatti, A. Venturini, A. Leporati, M. Carcelli, M. Costa,
A. Bacchi, G. Pelizzi, C. Pelizzi, J. Chem. Soc., Dalton Trans.
1998, 2715Ϫ2721.
D. N. Marks, W. O. Siegl, R. P. Gagne, Inorg. Chem. 1982,
21, 3140Ϫ3141.
See for example: [15a] A. W. Kleij, H. Klijn, J. T. B. H. Jastrzeb-
ski, A. L. Spek, G. van Koten, Organometallics 1999, 18,
[15b]
277Ϫ285.
J. Andrieu, J.-M. Camus, J. Dietz, P. Richard,
R. Poli, Inorg. Chem. 2001, 40, 1597Ϫ1605.
P. Pyykkö, Chem. Rev. 1997, 97, 597Ϫ636. [16b] A. Dedieu,
[16] [16a]
Chem. Rev. 2000, 100, 543Ϫ600.
[17] [17a]
K. Sonogashira, Y. Tohda, N. Hagihara, Tetrahedron Lett.
I. B. Campbell, in Organocopper Re-
agents (Ed.: R. J. K. Taylor), Oxford University Press, Oxford,
Metal-Catalyzed Cross-Coupling Reac-
tions (Eds.: F. Diederich, P. J. Stang), Wiley-VCH, Weinheim,
1998.
[7]
[8]
[17b]
M. Costa, P. Pelagatti, C. Pellizi, D. Rogolino, J. Mol. Catal.
A: Chemical 2002, 178, 21Ϫ26.
1975, 4467Ϫ4470.
[17c]
J. A. Elvidge, R. P. Linsted, J. Chem. Soc. 1952, 5008Ϫ5012.
1994, p. 217Ϫ235.
[9] [9a]
[9b]
[9c]
W. O. Siegl, J. Org. Chem. 1977, 42, 1872Ϫ1878.
W. O.
R. R.
Siegl, Inorg. Nucl. Chem. Lett. 1974, 10, 825Ϫ829.
[18]
´
Gagne, W. A. Marritt, D. N. Marks, W. O. Siegl, Inorg. Chem.
M. W. van Laren, C. J. Elsevier, Angew. Chem. 1999, 111,
3926Ϫ3929; Angew. Chem. Int. Ed. 1999, 38, 3715Ϫ3717.
1981, 20, 3260Ϫ3267. [9d] W. O. Siegl, F. C. Ferris, P. A. Mucci,
[9e]
J. Org. Chem. 1977, 42, 3442Ϫ3443.
R. D. Bereman, G. D.
[19] [19a] G. M. Whitesides, M. Hackett, R. L. Brainard, J.-P. Laval-
Shields, J. R. Dorfman, J. Bordner, J. Inorg. Biochem. 1983,
leye, A. F. Sowinski, A. N. Izumi, S. S. Moore, D. W. Brown,
[19b]
19, 75Ϫ93.
E. M. Staudt, Organometallics 1985, 4, 1819Ϫ1830.
R. H.
[10] [10a]
D. M. Baird, W. P. Maehlmann, R. D. Bereman, P. Singh,
Crabtree, M. F. Mellea, J. M. Mihelcic, J. M. Quirk, J. Am.
Chem. Soc. 1982, 104, 107Ϫ113.
[20] [20a]
[10b]
J. Coord. Chem. 1997, 42, 107Ϫ126.
A. W. Addison, P. J.
[10c]
Burke, K. Henrick, Inorg. Chem. 1982, 21, 60Ϫ63.
E. Bal-
M. S. Kharasch, R. C. Seyler, F. R. Mayo, J. Am. Chem.
[20b]
ogh-Hergovich, J. Kaiser, G. Speier, G. Huttner, A. Jacobi, In-
org. Chem. 2000, 39, 4224Ϫ4229. [10d] P. J. Domaille, R. L. Har-
low, S. D. Ittel, W. G. Peet, Inorg. Chem. 1983, 22, 3944Ϫ3952.
Soc. 1938, 60, 882Ϫ884.
J. R. Doyle, P. E. Slade, H. B.
[20c]
Jonassen, Inorg. Synth. 1960, 6, 216Ϫ219.
Frye, Z. Naturforsch., Teil B 1964, 19, 651.
E. Kuljian, H.
[11] [11a]
[21]
[22]
J. D. Druliner, S. D. Ittel, P. J. Krusic, C. A. Tolman, US
Nonius OpenMoleN, Interactive Structure Solution, Delft, 1997.
D. T. Cromer, J. T. Waber, International Tables for X-ray Crys-
tallography, The Kynoch Press, Birmingham, 1974.
Received March 4, 2004
Patent 4326084, 1982. [11b]L. Saussine, E. Brazi, A. Robine, H.
Mimoun, J. Fischer, R. Weiss, J. Am. Chem. Soc. 1985, 107,
3534Ϫ3540.
M. Giorgi, E. Kuzmann, A. Vertes, Eur. J. Inorg. Chem. 2003,
1735Ϫ1740.
[11c]
´
E. Balogh-Hergovich, G. Speier, M. Reglier,
´
Early View Article
Published Online June 23, 2004
Eur. J. Inorg. Chem. 2004, 3424Ϫ3435
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3435