Transition metal complexes with sterically demanding ligands. I. Synthesis and X-ray crystal structure of 1,5-cyclooctadiene palladium methyl triflate, (COD)Pd(Me)(OTf) and its cationic penta-coordinate adducts with sterically demanding 2,9-diaryl-substit

Article abstract of DOI:10.1016/S0022-328X(98)00997-8

The synthesis, use and X-ray crystal structure of the novel cyclooctadiene Pd-triflate methyl complex 1 is described. Evidence for ionization of the triflate ligand in 1 in solution is presented through IR, ¹⁹F-NMR and conductivity measurements

Full text of DOI:10.1016/S0022-328X(98)00997-8

Journal of Organometallic Chemistry 575 (1999) 214–222
Transition metal complexes with sterically demanding ligands.
I. Synthesis and X-ray crystal structure of 1,5-cyclooctadiene
palladium methyl triflate, (COD)Pd(Me)(OTf) and its cationic
penta-coordinate adducts with sterically demanding
2,9-diaryl-substituted 1,10-phenanthroline ligands
Peter Burger *, Jan M. Baumeister
Anorganisch-chemisches Institut der Uni6ersita¨t Zu¨rich, Winterthurerstr. 190, CH-8057 Zu¨rich, Switzerland
Received 22 July 1998
Abstract
The synthesis, use and X-ray crystal structure of the novel cyclooctadiene Pd–triflate methyl complex 1 is described. Evidence
for ionization of the triflate ligand in 1 in solution is presented through IR, 19F-NMR and conductivity measurements. The high
reactivity of this starting material is exemplified through the preparation of the novel cationic pentacoordinate Pd complexes 4 and
5, from 1 and the sterically demanding 2,9-diarylsubstituted 1,10-phenanthroline ligands 2 and 3. Complexes 4 and 5 have a
pseudo-trigonal bipyramidal structure and display significant differences of the binding mode of the two olefin moieties of the
1
cyclooctadiene ligand. This has been substantiated through H- and 13C-NMR spectroscopic data and for complex 4 by an X-ray
crystallographic study. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Trigonal-bipyramidal Pd complexes; Palladium-triflate; Sterically demanding phenanthroline ligands; Triflate ioniza-
tion; Conductivity measurements
nation gap in the corresponding square planar com-
plexes compared to the N-substituted diimine donors.
This becomes immediately apparent from the inspection
of the ligand framework in both systems presented in
Fig. 1.
This can be rationalized based on the directionality
of the 2,9-substituents in the 1,10-phenanthroline sys-
tem which are pointing more towards the two remain-
ing coordination sites in square planar geometry. As
evidenced by Brookhart et al. in the diimine systems,
the latter are occupied by the olefin and the growing
polymer chain in the proposed resting state of the olefin
polymerization process [2,4].
1. Introduction
Cationic Ni(II) and Pd(II) complexes with sterically
demanding nitrogen ligands have recently attained con-
siderable interest due to their catalytic applications in
the Ziegler-Natta olefin polymerization process [1,2].
The readily available diimine ligands R–NꢀCR%–
R%CꢀNR, where R=bulky aryl substituent, have been
mostly utilized in these systems and allowed to tailor
highly active catalysts and even to design living poly-
merization systems [3]. In order to explore the steric
requirements in these catalysts further, we have turned
to 2,9-diaryl substituted 1,10-phenanthroline ligands
(phen%) for which we anticipated a more narrow coordi-
Prior to catalytic studies, however, novel reactive
starting materials had to be identified for the synthesis
of Pd catalysts with such sterically very demanding
nitrogen donor ligands. Herein, we will report on the
* Corresponding
chburger@aci.unizh.ch.
author.
Fax:
+41-1-635-68-02;
e-mail:
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)00997-8

P. Burger, J.M. Baumeister / Journal of Organometallic Chemistry 575 (1999) 214–222
215
Fig. 1. Steric requirements of ligands in square planar Pd complexes. The triangles represent the size of reasoned coordination gaps.
2.2. Complex synthesis
In a first attempt to prepare the desired organometal-
lic Pd methyl phenanthroline complexes with the steri-
cally demanding ligands 2 and 3, the reaction of the
frequently used starting material, (COD)Pd(Me)(Cl), 4,
with the phenanthroline derivatives 2 and 3 was stud-
ied. However, while compound 4 has been found to be
quite versatile for the synthesis of a variety of Pd
complexes, including those with sterically demanding
ligands [2,7,8], only unchanged 4 was recovered in these
reactions even under very forcing conditions, i.e. high
reaction temperatures and long reaction times. A more
reactive starting material was therefore sought and let
us consider the corresponding triflate (OTf) complex,
(COD)Pd(Me)(OTf), 1, for which more facile substitu-
tion was anticipated due to the more labile OTf group.
Since this propensity of the triflate ligand has now been
widely recognized and used [9–18], we surprisingly had
to note that this complex had not been reported in the
literature. We had therefore to develop a synthesis for 1
and considered direct metathesis of the chloride ligand
Fig. 2. Sterically demanding 2,9-diaryl substituted 1,10-phenanthro-
line ligands.
synthesis and X-ray crystal structure of such a com-
pound, the novel palladium methyl triflate complex,
(COD)Pd(Me)(OTf), 1, and will exemplify its use in the
synthesis of the novel penta-coordinated 2,9-diaryl-sub-
stituted phenanthroline Pd complexes, 5 and 6.
in complex 4 with silver triflate (Eq. (1)).
(1)
As presented in Eq. (1), the desired complex 1 can be
prepared in excellent yield from this reaction and is
obtained as a white, analytically pure solid after recrys-
tallization from CH2Cl2/pentane. Complex 1 is ther-
mally stable in the solid state and can be stored and
handled at room temperature. Since decomposition in
solution (with concomitant formation of Pd metal) is
slow and only observed over an extended period of
time, compound 1 was deemed as an excellent starting
material for the synthesis of a variety of Pd methyl
complexes (vide supra).
2. Results and discussion
2.1. Ligand synthesis
The desired 2,9-diaryl-substituted ligands shown in
Fig. 2 have been prepared in analogy to a route pub-
lished by Sauvage et al. [5] for the novel ligand 2, with
R=4-t-Bu-C6H4, and for the 2,6-dimethoxyphenyl
substituted ligand, 3, following a synthesis reported by
Lu¨ning and coworkers [6].

216
P. Burger, J.M. Baumeister / Journal of Organometallic Chemistry 575 (1999) 214–222
Table 1
Crystal and data collection parameters for compounds 1 and 5
Compound
1
5
Formula
C
10H15F3O3PdS
C42H44F3N2O3PdS·CH2Cl2
Formula weight
Habitus
378.7
908.3
Colorless cube
0.2×0.2×0.2
Monoclinic
P21/c (No. 14)
12.429(3)
7.529(2)
15.134(3)
108.95(1)
1339.5(5)
4
White rect., parallelepiped
0.6×0.4×0.2
Monoclinic
Cc (No. 9)
12.259(2)
24.889(5)
14.625(2)
113.09(1)
4104.8(12)
4
Crystal size (mm)
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
i (°)
V (A )
3
˚
Z
Densitycalc (g cm−3
)
1.878
1.573
1662
1.470
0.688
1872
Absorption coefficient (mm−1
F(000)
)
Temperature (K)
u (A), Mo–Kh
Scan type
298
0.707173
ꢀ
193
0.707173
ꢀ
˚
2U range (°)
4–54
2816, 2816
163
0.067
0.158
4–56
8927, 8296
522
0.0555
0.211
No. of reflections measured
Total, unique no. of parameters
R1 (F2\2|(F2))
wR2 (F2\2|(F2))
Goodness-of-fit, S
1.272
1.35, −1.21
1.055
0.91, −0.72
−3
Res. e− density (e A
)
˚
2.3. X-ray crystal structure of 1
tions to the methyl and the triflate ligands. The aver-
aged carbon–Pd bond length of 239 pm (Pd(1)–C(2)
241.1(8) pm, Pd(1)–C(3) 237.7(7) pm) to the trans-
methyl olefin ligand is apparently 26 pm, or 10%,
longer than the corresponding distance of the olefin
unit trans to the triflate group (Pd(1)–C(6) 214.4(7) pm,
Pd(1)–C(7) 212.0(8) pm). The Pd(1)–O(1) (OTf) bond
distance of 212.6(5) pm is in the range observed in
other palladium triflate complexes [13,14,19]; it is how-
ever somewhat longer than the Pd–methyl bond length
(Pd(1)–C(1)) of 201.7(8) pm. Considering the smaller
covalent radius for carbon compared to oxygen, this
The details of the data collection in Table 1 are given
in Table 1; selected bond lengths and angles are com-
piled in Table 2. The triflate ligand is coordinated to
the Pd center in the solid state which is best illustrated
through the molecular structure presented in Fig. 3.
This leads to tetra-coordination with a square planar
ligand arrangement, taking the midpoints of the olefin
moieties as representatives of the COD ligand. The
most prominent feature in the crystal structure of 1 is
the observed large trans influence which is indicated
through the large differences of the palladium carbon
bond distances of the olefin moieties in the trans posi-
Table 2
˚
Selected bond distances (A) and angles (°) with estimated S.D.s for
complex 1
Pd(1)–C(1)
Pd(1)–C(3)
Pd(1)–C(7)
C(2)–C(3)
Pd(1)–Z1a
2.017(8)
2.377(7)
2.120(8)
1.344(13)
2.29
Pd(1)–C(2)
Pd(1)–C(6)
Pd(1)–O(1)
C(6)–C(7)
Pd(1)–Z2a
2.411(8)
2.144(7)
2.126(5)
1.368(12)
2.02
C(1)–Pd(1)–O(1)
Z2–Pd(1)–C(1)
Sum of angles at
Pd(1)
88.7(3)
91.0
360.3
Z1–Pd(1)–Z2
Z1–Pd(1)–O(1)
86.0
94.6
a Z1 and Z2 are the midpoints of carbon atoms C(2) and C(3) and
C(6) and C(7), respectively.
Fig. 3. Molecular structure of complex 1, (COD)Pd(Me)(OTf); se-
lected distances are presented.

P. Burger, J.M. Baumeister / Journal of Organometallic Chemistry 575 (1999) 214–222
217
Fig. 4. Concentration dependent molar conductivity of complex 1.
implied a weakened Pd–O bond. Hence, it was antici-
pated that ionization of the OTf ligand might still occur
in solution and evidence for this will be presented in the
next section.
M concentration, a strong band at 1321 cm−1, indicative
of a covalent bound OTf ligand, and a very weak band
at 1269 cm−1 in the typical range for an ionic triflate
group were observed [9,12]. The weak intensity of the low
energy w(SꢀO) band at 1269 cm−1 is consistent with the
aforementioned conductivity measurements, since just
very little dissociation would be expected at the 10−3 M
concentration based on the conductivity data. Further
evidence for the preference for covalent bonding of the
triflate ligand in 1 at higher concentrations (in the
10−1–10−2 M range), was obtained through 19F-NMR
spectroscopy in dichloromethane. At ca. 10−1 M con-
centration, the 19F-NMR resonance of the OTf group
appears at l= −79.76 and shifts to higher field (l= −
79.82) at ca. 2×10−2 M concentration. This should be
compared to the 19F-NMR chemical shift of the OTf
2.4. Solution studies of complex 1
2.4.1. Molar conducti6ity
In order to study the binding mode of the triflate group
in solution, we have turned to conductivity measure-
ments of complex 1, in both dichloromethane and in the
more polar solvent, acetone.
Conductivity measurements in CH2Cl2 solvent: At
10−4 M concentration, the molar conductivity, L, of 1
in CH2Cl2 amounts to just L=1 S cm2 mol−1 suggesting
only negligible dissociation of the triflate group. How-
ever, upon lowering of the concentrations of complex 1,
a steep increase of the molar conductivity is observed
(Fig. 4).
The concentration dependence of the molar conductiv-
ity of 1 presented in Fig. 4 clearly demonstrates that
complex 1 behaves as an ionophore, i.e. is only partially
dissociated at higher concentrations and fully dissociated
at very low concentrations.
Molar conductivity of 1 in acetone: In acetone solvent
at 1.1×10−3 M concentration, a molar conductivity of
L=103 S cm2 mol−1 was determined for complex 1.
This is in the typical range for 1:1 electrolytes in acetone
solvent [20] and shows that the triflate group is fully
dissociated, even at this quite high concentration.
group of l= −80.47 in PPN+OTf− (PPN+
=
Ph3PꢀNꢀPPh3+), a source of ionic triflate [21]. The
significant difference of the chemical shifts of the OTf
groups in 1 and PPN+OTf− suggests that the triflate
group is only dissociated to a very a small extent in the
NMR-samples of 1 which is consistent with the IR-spec-
troscopic and conductivity data. There is however a
noticeable trend of the triflate resonance to shift upfield
towards the chemical shift (Dl=0.06) of the free triflate
ion at lower concentrations. In acetone solvent, full
dissociation of the triflate in 1 is indicated through the
19F-NMR resonance at l= −79.1 ppm which is identi-
cal to the chemical shift of PPN+OTf− in this solvent.
The conductivity and IR- and NMR-spectroscopic
data of complex 1 clearly demonstrate that facile and
complete dissociation of the triflate group occurs in polar
solvents such as acetone. In weaker coordinating and less
2.4.2. IR- and 19F-NMR-spectroscopy
In the solution IR-spectrum of 1 in CD2Cl2 at ca. 10−3

218
P. Burger, J.M. Baumeister / Journal of Organometallic Chemistry 575 (1999) 214–222
polar solvents, e.g. dichloromethane, complex 1 be-
haves as an ionophore and displays concentration de-
pendent ionization of the OTf ligand. As will be
presented in the next section, triflate dissociation plays
an important role for the ligand substitution reactions
in complex 1.
(5, L=43 S cm2 mol−1 at 10−3 M concentration) and
suggested cationic phenanthroline Pd adducts with
ionic (non-coordinated) triflate counterions. At this
point, it was not completely clear whether the Pd
centers in complexes 5 and 6 were four- or five-coordi-
nate, i.e. with an p4-bisolefin unit in the latter case.
Prior to an X-ray crystal structure analysis for com-
plex 5, we were therefore glad to note the extended and
excellent work of Albano et al. on penta-coordination
in Pd and Pt complexes bearing dinitrogen donor lig-
ands [22,23]. These authors have put forward that
penta-coordination with a trigonal-bipyramidal struc-
2.5. Formation of penta-coordinated complexes 5 and 6
The facile and clean reactions of complex 1 with the
sterically demanding phenanthroline ligands 2 and 3
presented in Eq. (2) indeed confirmed our expectations.
(2)
1
The H-NMR spectra of complex 5 obtained from
ture is preferred over a square-planar tetra-coordinate
geometry in complexes with sterically demanding ligand
frameworks. The aforementioned observations for the
chemical shifts of the olefinic NMR-resonances in 5 and
6 were similar to their findings in related bisolefin
complexes [23]. Since the latter had been shown to
possess penta-coordinated metal centers, we also as-
sumed a trigonal-bipyramidal structure for complexes 5
and 6. This was later confirmed by the X-ray crystal
structure analysis of complex 5 which is described in
the next section.
the reaction according to Eq. (2), displayed two multi-
plets (1:1 integration ratio) in the olefin range which
immediately indicated that the 1,5-cyclooctadiene group
was still incorporated into the reaction product, 5 (i.e.
that it had not been substituted). Most noticeably, in
CD2Cl2 solution the latter resonances were separated by
ca. 1 ppm in 5 with the downfield triplet (l=4.93) in
proximity to the chemical shift of the olefinic protons in
the free COD ligand (l=5.56). In line with this obser-
vation, the 13C-NMR resonances of the olefinic carbon
atoms corresponding to the downfield triplet in the
1H-NMR spectrum were only slightly shifted (Dl= −
1.0 in 5 and −1.7 in 6) to higher field from the
observed chemical shift in free 1,5-cyclooctadiene
(l(CHolefin)=128.9). The remaining olefinic resonances
in 5 and 6 on the other hand experienced a significant
high-field shift of Dl= −39.6 and −42.1, respectively,
when compared to the free COD ligand indicating
strong Pd–olefin back donation. While it could be quite
safely concluded that the latter resonances originated
from a metal coordinated olefin moiety, the NMR-data
did not allow to distinguish between (a) an p4-binding
mode with differentiated weak and a strong back dona-
tion of the Pd center or (b) an p2-coordination of only
one olefin moiety of the COD ligand. The NMR-spec-
troscopic data allowed to establish an (at least) overall
Cs-symmetrical structure and also revealed an intact Pd
methyl bond evidenced through singlets in the 1H-
NMR spectra for the Pd methyl groups in 5 and 6.
Conductivity measurements of complexes 5 and 6 in
dichloromethane provided support for 1:1 electrolytes
2.6. X-ray crystal structure analysis of 5
The X-ray diffraction study of 5 established the
penta-coordinate trigonal-bipyramidal structure with
an p4-coordination mode of the bisolefin. The molecu-
lar structure of complex 5 is presented in Fig. 5, se-
lected bond angles and distances are given in Table 3,
details of the data collection, solution and refinement in
Table 1.
The equatorial sites are occupied by the phenanthro-
line N,N-donor ligand and by one of the olefin moieties
of the COD (C(40), C(41)) ligand. The other COD
olefin unit (C(44),C(45)) and the Pd–methyl group are
coordinated in the apical positions of the pseudo trigo-
nal-bipyramid and an angle of 173.5° is observed be-
tween the olefin midpoint (Z2) and the methyl ligand
(†(Z2–Pd(1)–C(50)). While the Pd–methyl and Pd–N
ligand distances are in the expected range, a quite
significant difference in the binding modes of the two

P. Burger, J.M. Baumeister / Journal of Organometallic Chemistry 575 (1999) 214–222
219
Fig. 5. Right hand: Molecular structure of cationic complex 5. Left hand: The 2,9-(4-t-butyl-phenyl)-substituents have been omitted for clarity;
selected distances and angles presented. The triflate ion is not shown.
olefin moieties was noticed for the bisolefin ligand.
Rather short Pd carbon bond lengths of 212.2(5) and
213.1(5) pm (Pd(1)–C(40), Pd(1)–C(41)) were observed
for the olefin oriented in the equatorial plane, while
noticeably longer distances were found for the Pd car-
bon bond distances to the apical olefin (Pd(1)–C(44)
237.7(6) pm and Pd(1)–C(45) 244.4(6)). Such a differ-
ence had been recognized earlier by Albano et al. in a
related penta-coordinated platinum COD complex and
plexes with sterically demanding donor ligands. Cur-
rently, we are studying the reaction chemistry of 5 and
6 and will report on olefin and CO insertion processes
in these complexes in due course [25].
4. Experimental section
Reactions were carried out under a dinitrogen atmo-
sphere with thoroughly dried solvents using glovebox
and Schlenk techniques. (COD)Pd(Me)(Cl), 4 [8], and
2,9-di-(2,6-dimethoxyphenyl)-1,10-phenanthroline, 3 [6],
were prepared according to published methods. 1H-,
19F- and 13C-NMR spectra were recorded on a Varian
Gemini 200 and 300 spectrometers. Chemical shifts are
given in ppm and referenced to the residual H solvent
shifts or 13C-NMR solvent shifts and for the 19F-NMR
resonances to the 19F-NMR chemical shift of trifluoro-
toluene. The assignment of 1H-NMR and 13C-NMR
1
was used to explain the observed differences of the H-
and 13C-NMR shifts of the olefin moieties (vide supra)
[22,23]. The stronger bonding to the equatorial olefin
ligand has been rationalized based on the stronger
y-back donation from the higher lying (better donat-
ing) and more extended Pd dxy-orbital, which is ori-
ented in the equatorial plane [22,24].
3. Conclusion
1
resonances is based on NOE, DEPT and selective H–
13C decoupling experiments. IR-spectra were measured
on a Biorad FTS-45 Fourier IR-spectrometer. X-ray
crystal structure analyses have been performed on a
Nicolet-Siemens P4 four-circle diffractometer with
The triflate complex 1 is an excellent and readily
available starting material for the synthesis of com-
Table 3
˚
monochromated Mo–Kh (0.70713 A) beam. CHN-
˚
Selected bond distances (A) and angles (°) with estimated S.D.s for
analyses were carried out with a LECO CHNS-932
elemental analyzer in our institute. Conductivity mea-
surements were performed with an Amel-160 conduc-
tometer using a glass cell with Pt electrodes (K=1.0).
complex 5
Pd(1)–C(50)
Pd(1)–C(41)
Pd(1)–C(45)
Pd(1)–N(2)
C(44)–C(45)
Pd(1)–Z2a
2.041(5) Pd(1)–C(40)
2.131(5) Pd(1)–C(44)
2.444(6) Pd(1)–N(1)
2.377(4) C(40)–C(41)
1.361(12) Pd(1)–Z1a
2.31
2.122(5)
2.377(6)
2.311(4)
1.401(8)
2.01
4.1. 2,9-Di-(4-tert-butylphenyl)-1,10-phenanthroline, 3
(a) Synthesis of 4-lithio-t-butyl benzene: 45 ml (75
mmol) of a 1.6 M solution of n-butyllithium was added
to a stirred solution of 15 g 1-bromo-4-t-butylbenzene
(70 mmol) in 100 ml pentane. After 2 days at room
temperature (r.t.), a white suspension was obtained
from which the desired lithium salt was collected by
filtration. The solid was washed twice with pentane and
N(1)–Pd(1)–N(2)
C(50)–Pd(1)–N(2)
C(50)–Pd(1)–Z(2) 173.5
N(1)–Pd(1)–Z(1)
N(1)–Pd(1)–Z2
73.0(2)
87.1(2)
C(50)–Pd(1)–N(1)
C(50)–Pd(1)–Z(1)
Z1–Pd(1)–Z(2)
N(2)–Pd(1)–Z(1)
N(2)–Pd(1)–Z(2)
90.1(2)
89.5
84.1
143.2
97.3
143.7
95.7
a Z1 and Z2 are the midpoints of carbon atoms C(40) and C(41)
and C(44) and C(45), respectively.

220
P. Burger, J.M. Baumeister / Journal of Organometallic Chemistry 575 (1999) 214–222
finally dried in high vacuum to give 9.5 g (68 mmol,
91%) 4-lithio-t-butyl benzene. (b) Addition to
1,10-phenanthroline: The obtained lithium salt (9.5 g, 68
mmol) was dissolved in 50 ml diethyl ether, cooled to
−70°C and added to a cooled solution (−70° C) of
3.06 g (17 mmol) anhydrous 1,10-phenanthroline in 100
ml toluene. Immediately, a red solution was obtained
which was allowed to warm up to r.t. overnight under
stirring. The solution was then cooled to 0°C and
hydrolyzed slowly with 20 ml H2O giving a yellow
organic phase. The organic phase was separated and the
aqueous phase was extracted twice with CH2Cl2. The
organic phases were combined and dried over Na2SO4.
Upon filtration, 100 g MnO2 (Fluka No. 63548) was
added to the solution and the reaction mixture was
stirred for 30 min at r.t. After this time, the mixture was
filtered through celite giving a pale yellow solution,
which was evaporated to dryness with a rotary
evaporator giving a white, slightly yellowish solid. This
material was taken up in a mixture of CH2Cl2: pentane
(9:1) and filtered through a short column of silica
(40–63 mm) yielding 3 as an analytically pure white
solid. Overall yield: 5.4 g (12.3 mmol; 74% based on
l=16.8 (s, Pd–CH3), 27.5, 31.2 (s, CH2, COD), 98.1
(s, CH, COD, trans to Pd–OTf,), 125.1 (CH, COD,
trans to Pd–methyl). The 13C-NMR resonance of the
triflate group could not be detected. 19F-NMR(282.3
MHz, CD2Cl2, 298 K) l= −79.8 (s, CF3SO3) (cf.
Text). 19F-NMR (282.3 MHz, [D6]acetone, 298 K) l=
−79.1 (s, CF3SO3). IR(SꢀO range, CD2Cl2) 1321 (vs),
1269 (vw) cm−1. Elemental analysis: Calc.: C: 31.72, H:
3.99; Found: C: 31.74, H: 4.19.
4.3. Synthesis of complex 5
At r.t., 760 mg (2.1 mmol) (COD)Pd(Me)(OTf), 1,
and 2.2 mmol of the phenanthroline derivative 2 were
stirred for 15 min in 4 ml acetone upon which precipita-
tion of 5 was observed. Complex 5 was isolated from
this mixture by centrifugation, washed twice with ca. 2
ml acetone and finally dried in high vacuum. Analyti-
cally pure material was obtained by recrystallization
from CH2Cl2/pentane at −36°C. Yield: 1.43 g (1.8
1
mmol, 85% based on (COD)Pd(Me)(OTf)). H-NMR
(200 MHz, CD2Cl2, 298 K): l=0.93 (m, 2H, CH2),
t
1.41 (s, 3H, CH3); 1.43 (s, 18H, Bu), 1.68 (m, 6H,
1
1,10-phenanthroline). H-NMR (200 MHz, CDCl3, 298
CH2), 3.92 (m, 2H, Holefin), 4.93 (m, 2H, Holefin), 7.69 (s,
8H, phenyl), 8.03 (d, J=8 Hz, 2H, H3,8), 8.17 (s, 2H,
H5,6), 8.70 (d, J=8 Hz, 2H, H4,7); 13C{1H}-NMR
(CD2Cl2, r.t., 50.3 MHz): l=162.8 (s, quart. Carom.),
154.0(s, quart. Carom.), 143.5(s, quart. Carom.), 139.7 (s,
CHarom.), 139.1 (s, quart. Carom.), 129.7(s, CHarom.),
130.1 (s, CHarom.), 127.9 (s, CHCOD), 127.9 (s, CHarom.),
125.9 (s, CHarom.), 89.3 (s, CHCOD), 34.2(s, C(CH3)),
t
K): l=1.41 (s, 18H, Bu), 7.6 (d, J=8 Hz, 4H, H2,2%
(tBu-phenyl)), 7.72 (s, 2H, H5,6), 8.09 (d, J=8 Hz, 2H,
H3,8), 8.25 (d, J=8 Hz, 2H, H4,7), 8.38 (d, J=8 Hz, 4H,
phenyl–H3,3%); 13C{1H}-NMR (50.3 MHz, CDCl3, 298
K): l=156.6 (s, quart. Carom.), 152.6 (s, quart. Carom.),
145.7 (s, quart. Carom.), 136.9 (s, CHarom.), 136.5 (s,
quart. Carom.), 127.7 (s, quart. Carom.), 127.4 (s, CHarom.),
125.8 (s, CHarom.), 125.7 (s, CHarom.), 119.7 (s, CHarom.);
34.7 (C(CH3)), 31.3 (C(CH3)). Elemental analysis:
Calc.: C: 86.45, H: 7.25, N 6.30; Found: C: 86.40, H:
7.37, N: 6.23.
31.4 (s, C(CH3)) 26.3 (s, CH2 ), 16.3 (s, Pd–CH3).
COD
The 13C-NMR resonance of the OTf group could not
be detected. 19F-NMR(282.3 MHz, CD2Cl2, 298 K)
l= −80.47 (s, CF3SO3). IR(SꢀO range, CD2Cl2) 1269
cm−1. Elemental Analysis: Calc.: C: 61.27, H: 5.75, N:
3.40; Found: C: 61.00, H: 5.81, N: 3.47.
4.2. Synthesis of (COD)Pd(CH3)(OTf), 1
1.07 g (4.2 mmol) finely powdered AgOTf and 0.91g
(3.4 mmol) (COD)Pd(Me)(Cl), 4, in 10 ml
dichloromethane were stirred for 2 h at r.t. After this
time AgCl and excess AgOTf were removed by filtra-
tion through celite. The volume of the filtrate was
reduced to one third and the remainder layered with 10
ml of pentane. From this mixture, the product was
obtained as colorless crystals within several days upon
cooling at −36°C. The mother liquor was decanted off
and the crystals were washed with a small volume of
cold CH2Cl2, followed by pentane and finally dried in
high vacuum. A second crop could be obtained by
recrystallization from the mother liquor and the wash-
ing solutions. Combined Yield: 1.13 g (3.1 mmol, 90%
based on (COD)Pd(Me)(Cl)). 1H-NMR (200 MHz,
CD2Cl2, 298 K): l=1.23 (s, 3H, CH3), 2.5 (m, 2H,
CH2), 2.63 (m, 2H, CH2), 5.14 (m, 4H, CH), 5.96 (m,
4H, CH); 13C{1H}-NMR (50.3 MHz, CD2Cl2, 298 K):
4.4. Synthesis of complex 6
At r.t., 190 mg (0.55 mmol) (COD)Pd(Me)(OTf), 1,
and 0.55 mmol of the phenanthroline derivative 3 were
dissolved in 5 ml dichloromethane, stirred for 30 min at
r.t. and then concentrated to ca. 3 ml by evaporation in
vacuo. From this solution, 7 crystallized at −36°C. A
further crop could be obtained from the mother liquor
by crystallization after further concentration. Com-
1
bined yield: 410 mg, 0.54 mmol (98%). H-NMR (200
MHz, CD2Cl2, 298 K): l=8.59 (d, J=8 Hz, 2 H), 8.12
(s, 2H, H), 7.78 (d, J=8Hz, 2H), 7.60 (t, J=8 Hz,
2H), 6.80 (t, J=8 Hz, 4H), 5.50 (m, 2 Holefin), 3.77 (s,
6H, OCH3) 3.64 (s, 6H, OCH3) 1.90–1.65 (m, 8H,
CH2(COD)), 1.35-1.1 (m, 2 Holefin), 0.96 (s, 3H, Pd–
CH3); 13C{1H}-NMR (75.4 MHz, acetone-d6, 298 K)
l=159.0 (s, quart. Carom.), 159.0 (s, quart. Carom.),
158.7 (s, quart. Carom.), 144.2 (s, quart. Carom.), 139.7 (s,

P. Burger, J.M. Baumeister / Journal of Organometallic Chemistry 575 (1999) 214–222
221
CHarom.), 133.0(s, CHarom.), 130.4 (s, quart. Carom.),
130.2 (s, CHarom.), 128.4 (s, CHarom.), 126.2 (s, CHCOD),
119.9 (s, quart. Carom) 105.2(s, CHarom.), 104.9 (s,
CHarom.) 86.8 (s, CHCOD), 56.3 (s, OCH3), 55.8 (s,
Forty-eight well-centered reflection in the range of
18°52U530° were used for the cell determination
and refinement and from this a monoclinic cell with
˚
˚
˚
a=12.259(2) A, b=24.889(5) A, c=14.625 (2) A,
i=113.09°(1), space group Cc (No. 9) was derived.
The data were collected using graphite-monochromated
Mo–Kh radiation with 4°52U556° (−155h514,
05k59, 05l519 and Friedel pairs). Three check
reflections were monitored periodically as a check for
crystal decomposition or movement and showed no
significant variation. Intensities were corrected for
Lorentz and polarization effects. The structure was
solved by the Patterson method with the SHELXS-86
program package [26]. The refinement was carried with
SHELXL-93 [27] against F2. All non-hydrogen atoms
were refined anisotropically; the positions of the hydro-
gen atoms were calculated in idealized positions (C–H
OCH3), 32.1 (s, CH2 ) 26.3 (s, CH2 ), 17.1 (Pd–
COD
CH3). 19F-NMR (282CMODHz, acetone-d6, 298 K) l= −
79.1(s, CF3SO3). 19F-NMR (282.1 MHz, CD2Cl2, 298
K) l= −80.47 (s, CF3SO3). Elemental analysis: Calc.:
C: 54.91, H: 4.73, N: 3.37; Found: C: 55.06, H: 4.99, N:
3.40.
4.5. X-ray crystal structure analyses
4.5.1. Complex 1
Single crystals suitable for X-ray diffraction were
obtained by slow crystallization from CH2Cl2: pentane
at −36°C. A colorless cube of approximate dimensions
0.2×0.2×0.2 mm was mounted on a glass fiber using
5 min epoxy resin. Forty-eight well-centered reflection
in the range of 20°52U532° were used for the cell
determination and refinement and from this a mono-
˚
bonds fixed at 0.96 A) and refined as riding model with
2
˚
a fixed isotropic displacement factor of U=0.08 A .
One of the t-butyl groups was found to be disordered
and was refined in two split positions. The occupation
factor of the disordered groups was given free and
converged at 0.76 and 0.24. The refinement converged
at final R-values R (F, I\2|(I)) of R1=0.0555 and
wR2=0.211.
Crystallographic data for complexes 1 and 5 (exclud-
ing structure factors) have been deposited with the
Cambridge Crystallographic Data center as supplemen-
tary publication numbers CCDC-101672 and CCDC-
101673, respectively. Copies of the data can be obtained
free of charge on application to CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: +44-1223-336-
033; e-mail: deposit@ccdc.cam.ac.uk).
˚
˚
clinic cell with a=12.429(2) A, b=7.529(2) A, c=
˚
15.134 A, i=108.95°(1), space group P21/n (No. 14)
was derived. The data were collected on a Nicolet-
Siemens-P4 four circle diffractometer at room tempera-
ture using graphite-monochromated Mo–Kh radiation
with 4°52U554° (−155h514, 05k59, 05l5
19). Three check reflections were monitored periodically
as a check for crystal decomposition or movement and
showed no significant variation. Intensities were cor-
rected for Lorentz and polarization effects. The struc-
ture was solved by the Patterson method using the
SHELXS-86 program package [26] from which the
position of the Pd atom was localized. The position of
the residual non-hydrogen atoms were obtained in sub-
sequent difference Fourier maps during refinement. All
non-hydrogen atoms were refined anisotropically; the
positions of the hydrogen atoms were calculated in
Acknowledgements
We are indebted to Professor Heinz Berke for his
generous support. A loan of PdCl2 from Johnson-
Matthey is gratefully acknowledged.
˚
idealized positions (C–H bonds fixed at 0.96 A) and
refined as riding model with a fixed isotropic displace-
2
˚
ment factor of U=0.08 A . The refinement was carried
out against F2 with the SHELXL93 program [27] and
converged at final R-values R(F, I\2|(I)) of R1=
0.0667 and wR2=0.1582.
References
[1] L.K. Johnson, S. Mecking, M. Brookhart, J. Am. Chem. Soc.
118 (1996) 267.
[2] L.K. Johnson, C.M. Killian, M. Brookhart, J. Am. Chem. Soc.
117 (1995) 6414.
[3] C.M. Killian, D.J. Tempel, L.K. Johnson, M. Brookhart, J. Am.
Chem. Soc. 118 (1996) 11664.
[4] F.C. Rix, M. Brookhart, J. Am. Chem. Soc. 117 (1995) 1137.
[5] C.O. Dietrich-Buchecker, P.A. Marnot, J.P. Sauvage, Tetrahe-
dron Lett. 23 (1982) 5291.
[6] U. Lu¨ning, M. Mu¨ller, Chem. Ber. 123 (1990) 643.
[7] R. van Asselt, E.E.C.G. Gielens, R.E. Ru¨lke, K. Vrieze, C.J.
Elsevier, J. Am. Chem. Soc. 116 (1994) 977.
[8] E.R. Ru¨lke, J.M. Ernsting, A.L. Spek, C.J. Elsevier, P.W.N.M.
van Leeuwen, K. Vrieze, Inorg. Chem. 32 (1993) 5769.
4.5.2. Complex 5
Single crystals suitable for X-ray diffraction were
obtained by slow diffusion of pentane into a solution of
5 in CH2Cl2. The CH2Cl2 solvent is also contained in
the crystals of complex 5 (one molecule CH2Cl2 per
complex 5). A colorless rectangular parallelepiped of
approximate dimensions 0.6×0.4×0.2 mm was
mounted on a glass fiber in Paratone-N and transferred
on the goniometerhead to a Siemens-Nicolet-P4 four
circle diffractometer. The crystal was then cooled to
−80°C in a N2-cryostream and centered in the beam.
.

222
P. Burger, J.M. Baumeister / Journal of Organometallic Chemistry 575 (1999) 214–222
[9] G.A. Lawrance, Chem. Rev. 86 (1986) 17.
[10] P.J. Stang, M.H. Kowalski, M.D. Schiavelli, D. Longford, J.
Am. Chem. Soc. 111 (1989) 3347.
[11] P.J. Stang, C.M. Crittell, Organometallics 9 (1990) 3191.
[12] P.J. Stang, Y.-H. Huang, A.M. Arif, Organometallics 11 (1992)
231.
[19] O.P. Anderson, A.B. Packard, Inorg. Chem. 18 (1979) 1129.
[20] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81.
[21] J. Nitschke, S.P. Schmidt, W.C. Trogler, Inorg. Chem. 24 (1985)
1972.
[22] V.G. Albano, G. Natile, A. Panunzi, Coord. Chem. Rev. 133
(1994) 67.
[13] P.J. Stang, D.H. Cao, G.T. Poulter, A.M. Arif, Organometallics
14 (1995) 1110.
[14] P.J. Stang, D.H. Cao, S. Saito, A.M. Arif, J. Am. Chem. Soc 117
(1995) 6273.
[15] K.A. Woerpel, R.G. Bergman, J. Am. Chem. Soc. 115 (1993)
7888.
[16] M.B. O’Regan, A.H. Liu, W.C. Finch, R.R. Schrock, W.M.
Davis, J. Am. Chem. Soc. 112 (1990) 4331.
[17] P. Burger, R.G. Bergman, J. Am. Chem. Soc. 115 (1993) 10462.
[18] G.R. Frauenhoff, S.R. Wilson, J.R. Shapley, Inorg. Chem. 30
(1991) 78.
[23] V.G. Albano, C. Castellari, M.E. Cucciolito, A. Panunzi, A.
Vitagliano, Organometallics 9 (1990) 1269.
[24] F.P. Fanizzi, L. Maresca, G. Natile, M. Lanfranchini, A. Tiripic-
chio, G. Pacchioni, J. Chem. Soc., Chem. Commun. (1992)
333.
[25] Parts of this study have been presented at the 214th ACS
Meeting, Las Vegas, 1997: J. Baumeister, P. Burger.
[26] G.M. Sheldrick, SHELXS-86, Universita¨t Go¨ttingen, Germany,
1988.
[27] G.M. Sheldrick, SHELXL-93, Universita¨t Go¨ttingen, Germany
1993.
.