Preparation and NMR studies of palladium complexes with a silsesquioxanate ligand

Article abstract of DOI:10.1021/om700827f

Reaction of an incompletely condensed silsesquioxane trisilanol, (c-C ₅H₉)₇Si₇O₉(OH) ₃, with trans-[Pd(I)(Ar)(PMe₃)₂] in the presence of Ag₂O yielded arylpalladium complexes with a monodentate O-coordinated silsesquioxanate ligand, trans-[Pd{O₁₀Si ₇(c-C₅H₉)₇(OH)₂}(Ar) (PMe₃)₂] (4a: Ar = Ph, 4b: Ar = C₆F ₅). X-ray crystallographic results of 4b showed trans coordination of the pentafluorophenyl ligand and the O-coordinated silsesquioxanate ligand to the square-planar Pd(II) center. Variable-temperature ¹H, ¹⁹F{¹H}, and ²⁹Si{¹H} NMR spectra of 4a and 4b revealed dynamic behavior of the molecules in solution.

Full text of DOI:10.1021/om700827f

Organometallics 2008, 27, 519–523
519
Preparation and NMR Studies of Palladium Complexes with a
Silsesquioxanate Ligand
Makoto Tanabe, Kohji Mutou, Neli Mintcheva, and Kohtaro Osakada*
Chemical Resources Laboratory (R1-3), Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
ReceiVed August 13, 2007
Reaction of an incompletely condensed silsesquioxane trisilanol, (c-C5H9)7Si7O9(OH)3, with trans-
[Pd(I)(Ar)(PMe3)2] in the presence of Ag2O yielded arylpalladium complexes with a monodentate
O-coordinated silsesquioxanate ligand, trans-[Pd{O10Si7(c-C5H9)7(OH)2}(Ar)(PMe3)2] (4a: Ar ) Ph, 4b:
Ar ) C6F5). X-ray crystallographic results of 4b showed trans coordination of the pentafluorophenyl
ligand and the O-coordinated silsesquioxanate ligand to the square-planar Pd(II) center. Variable-
1
temperature H, 19F{1H}, and 29Si{1H} NMR spectra of 4a and 4b revealed dynamic behavior of the
molecules in solution.
Introduction
The metal complexes with silsesquioxane-containing ligands
were studied as molecular model compounds of silica-supported
transition-metal catalysts or precursors of metal-based hetero-
geneous catalysts.1 Incompletely condensed silsesquioxanes that
are functionalized with amino and phosphido groups are
employed as the ligands of transition-metal complexes.2,3
Polyhedral oligomeric silsesquioxanes with incompletely con-
densed structures are coordinated to transition metals as the
bulky O-ligands.4 Although the metallasilsesquioxanes of early
Figure 1.
transition metals are stabilized by the M-O bond of the
inherently oxophilic metals, the late transition metal complexes
with directly O-bonded silsesquioxanate ligands are less com-
mon, possibly due to mismatching of the coordinating siloxo
groups and electron-rich metals.5 Abbenhuis6 and Johnson7
prepared platinum complexes containing incompletely con-
densed silsesquioxanates as O,O-chelating bidentate ligands.
Recently, we reported platinum and palladium complexes with
a monodentate silsesquioxanate ligand, trans-[Pt{O10Si7(c-
C5H9)7(OH)2}(Ph)(PR3)2] (1) (PR′3 ) PEt3, PMe2Ph)8 and
[Pd{O10Si7(c-C5H9)7(OH)2}(Ar)(tmeda)] (2a: Ar ) Ph, 2b: Ar
) C6F5, tmeda ) N,N,N′,N′-tetramethylethylenediamine) (Figure
1).9 Two OH groups and the coordinated oxygen atom formed
two intramolecular O-H · · · O hydrogen bonds, which were
revealed by X-ray crystallography and 1H NMR spectroscopy.
In this paper, we report the preparation and dynamic behavior
of the palladium complexes having two PMe3 ligands and a
silsesquioxanate as the O-coordinated ligand.
* To whom correspondence should be addressed. E-mail: kosakada@
res.titech.ac.jp.
(1) For reviews: (a) Feher, F. J.; Budzichowski, T. A. Polyhedron 1995,
14, 3239. (b) Murugavel, R.; Voigt, A.; Walawalkar, M. G.; Roesky, H. W.
Chem. ReV. 1996, 96, 2205. (c) Abbenhuis, H. C. L. Chem. Eur. J. 2000,
6, 25. (d) Lorenz, V.; Fischer, A.; Giessmann, S.; Gilje, J. W.; Gun’ko, Y.;
Jacob, K.; Edelmann, F. T. Coord. Chem. ReV. 2000, 206–207, 321. (e)
Duchateau, R. Chem. ReV. 2002, 102, 3525. (f) Hanssen, R. W. J. M.; van
Santen, R. A.; Abbenhuis, H. C. L. Eur. J. Inorg. Chem. 2004, 675. (h)
Lorenz, V.; Edelmann, F. T. Z. Anorg. Allg. Chem. 2004, 630, 1147.
(2) (a) P-ligands: Wada, K.; Izuhara, D.; Shiotsuki, M.; Kondo, T.;
Mitsudo, T. Chem. Lett. 2001, 734. (b) Nowotny, M.; Maschmeyer, T.;
Johnson, B. F. G.; Lahuerta, P.; Thomas, J. M.; Davis, J. E. Angew. Chem.,
Int. Ed. 2001, 40, 955. (c) van der Vlugt, J. I.; Fioroni, M.; Ackerstaff, J.;
Hanssen, R. W. J. M.; Mills, A. M.; Spek, A. L.; Meetsma, A.; Abbenhuis,
H. C. L.; Vogt, D. Organometallics 2003, 22, 5297. (d) van der Vlugt,
J. I.; Ackerstaff, J.; Dijkstra, T. W.; Mills, A. M.; Kooijman, H.; Spek,
A. L.; Meetsma, A.; Abbenhuis, H. C. L.; Vogt, D. AdV. Synth. Catal. 2004,
346, 399.
Results and Discussion
The reaction of an incompletely condensed silsesquioxane,
(c-C5H9)7Si7O9(OH)3, with trans-[Pd(I)(Ar)(PMe3)2] (3a: Ar )
Ph, 3b: Ar ) C6F5) in the presence of Ag2O at room temperature
produced the palladium complexes with silsesquioxanate and
two trans PMe3 ligands, trans-[Pd{O10Si7(c-C5H9)7(OH)2}-
(Ar)(PMe3)2] (4a: Ar ) Ph, 4b: Ar ) C6F5), in 85% and 78%
yields (eq 1). The obtained complexes are stable under air in
the solid state but are decomposed slowly in CHCl3.
Complex 4a was obtained also by exchange of the auxiliary
ligand of [Pd{O10Si7(c-C5H9)7(OH)2}(Ph)(tmeda)] (2a); treat-
ment of 2a with excess PMe3 yielded 4a at room temperature
in 85% yield, accompanied by cis–trans isomerization (eq 2).
(3) (a) N-ligands: Naka, K.; Itoh, H.; Chujo, Y. Nano Lett. 2002, 2,
1183. (b) Wada, K.; Yano, K.; Kondo, T.; Mitsudo, T. Catal. Today 2006,
117, 242.
(4) (a) Feher, F. J. J. Am. Chem. Soc. 1986, 108, 3850. (b) Feher, F. J.;
Newman, D. A.; Walzer, J. F. J. Am. Chem. Soc. 1989, 111, 1741.
(5) (a) Wolczanski, P. T. Polyhedron 1995, 14, 3335. (b) Marciniec,
B.; Maciejewski, H. Coord. Chem. ReV. 2001, 223, 301.
(6) Abbenhuis, H. C. L.; Burrows, A. D.; Kooijman, H.; Lutz, M.;
Palmer, M. T.; van Santen, R. A.; Spek, A. L. Chem. Commun. 1998, 2627.
(7) Quadrelli, E. A.; Davies, J. E.; Johnson, B. F. G.; Feeder, N. Chem.
Commun. 2000, 1031.
(8) Mintcheva, N.; Tanabe, M.; Osakada, K. Organometallics 2006, 25,
3776.
(9) Mintcheva, N.; Tanabe, M.; Osakada, K. Organometallics 2007, 26,
1402.
10.1021/om700827f CCC: $40.75
2008 American Chemical Society
Publication on Web 01/19/2008

520 Organometallics, Vol. 27, No. 4, 2008
Tanabe et al.
(1)
(2)
Figure 2. ORTEP drawing of 4b at the 50% ellipsoidal level.
Hydrogen atoms, except for two OH hydrogens, and CH2 carbons
of the cyclopentyl groups are omitted for simplicity.
Table 1. Selected Bond Distances and Angles for 4b
bond distances (Å)
bond angles (deg)
Figure 2 shows the molecular structure of 4b determined by
X-ray crystallography. Selected bond distances and angles are
summarized in Table 1. 4b has a square-planar coordination
around the Pd center, having the C6F5 group and the O-
coordinated silsesquioxanate ligand at trans positions. The C6F5
plane is situated perpendicularly to the coordination plane around
the Pd center. The Pd-O1 bond distance of 4b (2.098(3) Å) is
similar to the reported alkoxo-palladium complexes (1.979–2.129
Å),10 aryloxo-palladium complexes (2.020–2.134 Å),11 and the
palladium silsesquioxanate with tmeda ligand 2b (2.000(2) Å).9
The plane formed by Pd, O1, and Si1 atoms is also perpendicular
to the coordination plane. The Pd-O1-Si1 bond angle
(125.6(2)°) is smaller than those of 2b (133.0(1)°),9
[Pd(C6F5)(OSiPh3)(tmeda)] (136.9(2)°, 137.9(2)°),12 and sils-
esquioxanate platinum complexes 1 (130.2(2)°, 134.6(2)°).8 The
O1 · · · O6 and O6 · · · O9 distances of 4b (2.588(4) and 2.771(5)
Å) indicate the presence of two intramolecular O · · · H-O
hydrogen bonds, and the O6-H1 and O9-H2 bonds are
oriented toward O1 and O6, respectively. The shorter distance
between the coordinated oxygen O1 and O6 atoms than that
between O6 and O9 suggests a stronger hydrogen bond of the
former, which is ascribed to the high electron density of the
O1 atom coordinated by the Pd center. The complexes of
platinum,8 palladium,9 and iron13 with O-coordinated silses-
quioxanate ligands were reported to form similar hydrogen
bonds among OH groups and the coordinated oxygen atoms.
IR spectra of 4a and 4b show broad ν(OH) peaks at 3200 and
3300 cm-1, respectively, in the solid state. Incompletely
condensed silsesquioxanes, having a vicinal trisilanol structure,
(c-C5H9)7Si7O9(OH)3, exhibit a peak at a similar position (3200
cm-1), but the silsesquioxane disilanols formed by its methy-
lation, (c-C5H9)7Si7O9(OSiMe3)(OH)2, give rise to the ν(OH)
Pd-O1
2.098(3)
2.322(1)
2.330(1)
2.014(4)
1.609(3)
2.588(4)
2.771(5)
3.826(5)
1.86(6)
P1-Pd-O1
88.68(8)
87.9(1)
Pd-P1
P1-Pd-C1
P2-Pd-O1
P2-Pd-C1
Pd-O1-Si1
O1 · · · H1-O6
O6 · · · H2-O9
Pd-P2
Pd-C1
95.69(8)
88.0 (1)
125.6(2)
172.0(4)
170.0(8)
Si1-O1
O1 · · · O6
O6 · · · O9
O1 · · · O9
O1 · · · H1
O6 · · · H2
2.11(6)
peaks at a higher wavenumber (3471 cm-1).1e Thus, two OH
groups of 4a form strong hydrogen bonds similarly to (c-
C5H9)7Si7O9(OH)3, while 4b contains weaker O-H · · · O hy-
drogen bonds due to the less electron-donating C6F5 ligand of
4b than the C6H5 ligand of 4a.
1H NMR spectra of 4a and 4b at room temperature contain
broadened peaks of the OH hydrogens of the silsesquioxanate
ligand at δ 9.20 (4a) and 8.34 (4b). Figure 3 shows variable-
1
temperature H NMR spectra of 4a at -80 to 50 °C. As the
temperature of the solution is lowered, the OH signal of 4a is
shifted to a lower magnetic field (δ 9.57 at -50 °C) and is
sharpened at -80 °C. Although the crystal structure of 4b shows
the presence of two OH groups that are hydrogen bonded to the
coordinated oxygen or oxygen atom of the other OH group,
the 1H NMR signal of the OH hydrogens is observed as a single
peak even at low temperature; similar results are obtained from
the variable-temperature H NMR studies of Pt complex 1.8
1
(10) (a) Kim, Y.-J.; Osakada, K.; Takenaka, A.; Yamamoto, A. J. Am.
Chem. Soc. 1990, 112, 1096. (b) Kapteijn, G. M.; Dervisi, A.; Grove, D. M.;
Kooijman, H.; Lakin, M. T.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc.
1995, 117, 10939.
(11) (a) Alsters, P. L.; Baesjou, P. J.; Janssen, M. D.; Kooijman, H.;
Sicherer-Roetman, A.; Spek, A. L.; van Koten, G. Organometallics 1992,
11, 4124. (b) Kapteijn, G. M.; Grove, D. M.; Kooijman, H.; Smeets, W. J. J.;
Spek, A. L.; van Koten, G. Inorg. Chem. 1996, 35, 526. (c) Kapteijn, G. M.;
Meijer, M. D.; Grove, D. M.; Veldman, N.; Spek, A. L.; van Koten, G.
Inorg. Chim. Acta 1997, 264, 211. (d) Kim, Y.-J.; Lee, J.-Y.; Osakada, K.
J. Organomet. Chem. 1998, 558, 41. (e) Liu, X.; Renard, S. L.; Kilner,
C. A.; Halcrow, M. A. Inorg. Chem. Commun. 2003, 6, 598.
(12) Ruiz, J.; Vicente, C.; Rodríguez, V.; Cutillas, N.; López, G.; de
Arellano, C. R. J. Organomet. Chem. 2004, 689, 1872.
Figure 3. 1H NMR spectra of 4a in toluene-d8 at -80, -50, -20,
10, and 50 °C.
(13) Liu, F.; John, K. D.; Scott, B. L.; Baker, R. T.; Ott, K. C.; Tumas,
W. Angew. Chem., Int. Ed. 2000, 39, 3127.

Pd Complexes with a Silsesquioxanate Ligand
Organometallics, Vol. 27, No. 4, 2008 521
Scheme 1
Consequently, complex 4a undergoes rapid exchange of the two
OH groups over the NMR time scale even at -80 °C, as shown
in Scheme 1. Broadening of the OH signals of complex 4a above
0 °C may suggest the occurrence of a different dynamic
behavior.
Variable-temperature 29Si{1H} NMR studies of 4a in toluene-
d8 also demonstrate dynamic behavior of the silsesquioxane
molecules, as shown in Figure 4. The 29Si{1H} NMR spectrum
at -50 °C shows five distinct signals at δ -67.7, -65.6, -65.4,
-58.3, and -57.3 (ratio 2:1:1:1:2), similarly to the spectra of
analogous Pt complexes 1 (PR3 ) PEt3, PMe2Ph) at room
temperature.8 The signal at δ -65.4 remains as a sharp peak
even at 50 °C. Two sets of signals at δ -67.7 and -65.6 and
δ -58.3 and -57.3 are broadened at 5 °C due to exchange of
the 29Si nuclei on the NMR time scale. The peak pair at lower
magnetic field with a smaller peak separation (∆ν ) 77.2 Hz
at -50 °C) approaches the weighted average position at 50 °C,
although the peak pair (δ -67.7 and -65.6) with a larger peak
separation (∆ν ) 169 Hz at -50 °C) does not move from their
original position at 50 °C. Coalescence of the latter peak pair
would occur at higher temperature. The NMR spectra at 75 °C
indicated partial decomposition of the complex and did not
provide useful information for the dynamic behavior of the
molecule. The 29Si{1H} NMR spectrum of complex 4b changes
above room temperature, indicating that the same dynamic
process takes place less easily (Figure 5). The spectrum of 4b
at 25 °C shows five signals at δ -67.6, -65.1, -65.0, -58.0,
and -56.9 in 2:1:1:1:2 ratio. Heating the solution at 90 °C
causes broadening of two sets of signals at δ -67.6 and -65.0
and δ -58.0 and -56.9 to give two broadened signals and a
sharp signal. The higher coalescence temperature of the 29Si{1H}
NMR signals of 4b than 4a can be ascribed to the C6F5 group
situated at the trans position of the silsesquioxanate ligand; an
electron-withdrawing C6F5 ligand stabilizes coordination of the
electron-donating silsesquioxanate ligand more significantly than
the C6H5 ligand.
Figure 5. 29Si{1H} NMR spectra of 4b in toluene-d8 containing
Cr(acac)3 (0.02 M) at 25, 50, 60, and 90 °C.
SiC, SiA, SiB, and SiB′,B′′ of structure I, which is consistent with
the 2:1:1:1:2 ratio. Transfer of the Pd to the other OH groups
would form the structures II and III. Approach of the signals
at δ -58.3 and -57.3 to the weight averaged position with
broadening, broadening of the signal at δ -65.6 and -67.7,
and the temperature-independent position of the peak at δ -65.4
(SiA) are consistent with the dynamic behavior of the molecule.
Previously, we proposed intramolecular exchange of the siloxo
ligand of the Pt and Pd complexes with an O-coordinated
silsesquioxanate ligand in order to interpret the 1H and 19F NMR
signals of the C6H5 and C6F5 ligands bonded to the metal center.
The complexes in this study show dynamic behavior via
intramolecular exchange of the hydrogen bonds, shown in
Scheme 2.
The 19F{1H} NMR spectra of 4b change depending on
temperature, as shown in Figure 6. The spectrum at -50 °C
contains a signal for the para fluorine nucleus (δ -158.7), two
signals for ortho (δ -117.1, -117.9), and two signals for meta
(δ -161.5, -162.1) fluorine nuclei. Raising the temperature
causes broadening of the signals for the ortho and meta fluorine
peaks, and the signals are coalesced at 0 °C. Separation of the
19F NMR peaks (318 and 252 Hz) is larger than the pairs of
29Si NMR peaks that are broadened on heating (90.8 and 208
Hz), and the fluxional behavior of the 19F NMR spectra is not
directly related to that observed in the 29Si{1H} NMR spectra.
There is a possible dynamic process other than those in Schemes
1 and 2, and rotation of the aryl ring may occur independently
from the two dynamic processes shown above.
The present study provided the structure of the palladium
complexes with a monodentate silsesquioxanate ligand in the
solid state and in solution. Variable-temperature 29Si NMR
studies of complexes 4a and 4b display the dynamic behavior
that involves switching of the O-H · · · O hydrogen bonds within
the O-coordinated silsesquioxanate ligand.
Scheme 2 depicts a plausible mechanism that accounts for
the dynamic behavior of 4a. The five peaks at δ -67.7, -65.6,
-65.4, -58.3, and -57.3 at -50 °C are assigned to SiC′,C′′
,
Experimental Section
General Procedures. All manipulations of the complexes were
carried out using standard Schlenk techniques under an argon or
nitrogen atmosphere. Hexane and toluene were purified by passing
through a solvent purification system (Glass Contour). 1H, 13C{1H},
19F{1H}, 29Si{1H}, and 31P{1H} NMR spectra were recorded on
a Varian Mercury 300 or JEOL EX-400 spectrometer. Chemical
shifts of the signals in 1H and 13C{1H} NMR spectra were adjusted
to the residual peaks of the solvents used. The peak positions of
the 19F{1H}, 29Si{1H}, and 31P{1H} NMR spectra were referenced
to external CF3COOH (δ -76.5) in toluene-d8, external SiMe4 (δ
Figure 4. 29Si{1H} NMR spectra of 4a in toluene-d8 containing
Cr(acac)3 (0.02 M) at -50, 0, 5, 10, and 50 °C.

522 Organometallics, Vol. 27, No. 4, 2008
Tanabe et al.
Scheme 2
Table 2. Crystallographic Data and Details of Refinement for 4b
0) in toluene-d8, and 85% H3PO4 (δ 0) in C6D6, respectively. The
palladium complexes trans-[Pd(I)(Ph)(PMe3)2],14 [Pd(I)(C6F5)-
(tmeda)],15 and [Pd{(c-C5H9)7Si7O10(OH)2}(Ph)(tmeda)] (2a)9 were
prepared according to the previous reports. Silsesquioxanes,
1,3,5,7,9,11,14-heptacyclopentyltricyclo[7.3.3.1(5,11)]heptasiloxane-
endo-3,7,14-triol (Gelest), Ag2O (Wako Pure Chemical), and
acetone (Kanto Chemical) are commercially available products.
These reagents and solvents are used without any purification. IR
absorption spectra were recorded on a Shimadzu FT/IR-8100
spectrometer. Elemental analysis was carried out with a LECO
CHNS-932 CHNS or Yanaco MT-5 CHN autorecorder.
formula
fw
C47H83F5O12P2PdSi7 · 1/2C7H8
1346.18
cryst color
orange
cryst syst
triclinic
cryst size/mm
space group
0.15 × 0.35 × 0.40
j
P1 (No. 2)
a/Å
b/Å
c/Å
13.700(6)
14.054(6)
17.196(7)
102.186(7)
99.416(5)
91.966(7)
3185(2)
2
1.411
1418
0.5425
20 863
12 827 (Rint ) 0.027)
10 188
797
0.0603
0.1326
1.018
R/deg
ꢀ/deg
γ/deg
V/Å3
Preparation of trans-[Pd(I)(C6F5)(PMe3)2] (3b). To a toluene
(10 mL) solution containing [Pd(I)(C6F5)(tmeda)] (858 mg, 1.7
mmol) at room temperature was slowly added PMe3 (0.43 mL, 4.15
mmol) by a syringe. After stirring for 12 h at room temperature,
the solvent was removed under reduced pressure to give a white
solid, which was washed twice with 3 mL of hexane and dried in
Vacuo to afford 3b (883 mg, 96%). Anal. Calcd for C12H18F5IP2Pd:
C, 26.08; H, 3.28; F, 17.19; I, 22.97. Found: C, 26.17; H, 3.27; F,
Z
Dcalcd/g cm-3
F(000)
µ/mm-1
no. of rflns measd
no. of unique rflns
no. of obsd rflns (I > 2.00σ(I))
no. of variables
R1 (I > 2.00σ(I))
wR2 (I > 2.00σ(I))
GOF
1
16.97; I, 22.64. H NMR (400 MHz, C6D6, room temperature): δ
0.89 (apparent triplet due to virtual coupling, PCH3, 18H, splitting
3.6 Hz). 13C{1H} NMR (75 MHz, C6D6, room temperature): δ 16.5
(apparent triplet due to virtual coupling, PCH3, splitting 16.3 Hz),
137.2 (ddd, C6F5 meta, JF-C ) 254, 30, 13 Hz) 138.3 (m, C6F5 para,
JF-C ) 244 Hz), 146.6 (dd, C6F5 ortho, JF-C ) 221, 16 Hz). The
ipso-carbon signal of the C6F5 group was not observed due to the
low intensity. 19F{1H} NMR (376 MHz, C6D6, room temperature):
δ -163.0 (m, 2F, C6F5 meta, JF-F ) 24, 6 Hz), -160.0 (t, 1F,
C6F5 para, JF-F ) 20 Hz), -118.3 (dd, 2F, C6F5 ortho, JF-F ) 32,
6 Hz). 31P{1H} NMR (162 MHz, C6D6, room temperature): δ
-17.9.
(107 mg, 0.23 mmol) were added (c-C5H9)7Si7O9(OH)3 (199 mg,
0.23 mmol) and Ag2O (63.4 mg, 0.27 mmol). The mixture was
stirred for 46 h at room temperature. When the reaction was
completed by monitoring of the 31P{1H} NMR spectroscopy, the
toluene suspension was filtrated through Celite to remove the
precipitation, and the solvent was pumped off. The residual solid
substance was washed twice with 3 mL portions of acetone and
dried in Vacuo to give 4b as a white solid (237 mg, 85%). Anal.
Calcd for C47H88O12P2PdSi7: C, 46.65; H, 7.33. Found: C, 46.34;
H, 7.25. 1H NMR (400 MHz, C6D6, room temperature): δ 0.98
(apparent triplet due to virtual coupling, 18H, PCH3, splitting 3.2
Hz), 1.21 (m, 7H, CH pentyl), 1.57, 1.74, 1.83, 1.97, 2.22 (56H,
CH2 pentyl), 6.88 (m, 3H, C6H5 meta and para), 7.13 (br, 2H, C6H5
Preparation of trans-[Pd{(c-C5H9)7Si7O10(OH)2}(Ph)(PMe3)2]
(4a). To a toluene (10 mL) solution of trans-[Pd(I)(Ph)(PMe3)2]
1
ortho), 9.20 (br, 2H, OH). H NMR (400 MHz, toluene-d8, -50
°C): δ 0.91 (br, 18H, PCH3), 1.23 (m, 7H, CH pentyl), 1.61, 1.80,
1.87, 2.03, 2.28 (56H, CH2 pentyl), 6.88 (m, 3H, C6H5 meta and
para), 7.04 (br, 1H, C6H5 ortho), 7.19 (br, 1H, C6H5 ortho), 9.57
(br, 2H, OH). 13C{1H} NMR (100 MHz, C6D6, room temperature):
δ 12.8 (apparent triplet due to virtual coupling, PCH3, splitting 14
Hz), 23.1, 23.9, 24.1 (CH pentyl), 27.7, 28.1, 28.4, 29.8 (CH2
pentyl), 123.1 (C6H5 para), 136.7 (C6H5 ortho), 149.0 (t, C6H5 ipso,
JP-C ) 9.0 Hz). 13C{1H} NMR (100 MHz, toluene-d8, -50 °C): δ
13.5 (apparent triplet due to virtual coupling, PCH3, splitting 14
Hz), 22.7, 22.9, 23.4, 23.7, 26.9 (1:1:2:2:1, CH pentyl), 27.4, 27.4,
27.6, 27.8, 27.9, 28.1, 28.2, 28.3, 29.5 (CH2 pentyl), 122.8 (C6H5
para), 137.1 (C6H5 ortho), 149.2 (t, C6H5 ipso, JP-C ) 9.0 Hz).
The meta-carbon signal of the C6H5 group was overlapped with
the solvent signals. 31P{1H} NMR (161 MHz, C6D6, room
temperature): δ -17.9. 29Si{1H} NMR (79.3 MHz, toluene-d8, 0.02
M Cr(acac)3, 25 °C): δ -67.4 (br), -65.1, -58.1 (br), -57.0 (br).
29Si{1H} NMR (79.3 MHz, toluene-d8, 0.02 M Cr(acac)3, -50 °C):
δ -67.7, -65.6, -65.4, -58.3, -57.3 (ratio 2:1:1:1:2). IR data
(KBr): 3200 (br), 2950 (s), 2867 (s), 1119 (s), 951 (s), 735 (m),
Figure 6. 19F{1H} NMR spectra of 4b in toluene-d8 at -50, -25,
-15, and 0 °C.
(14) Kim, Y.-J.; Lee, J.-Y.; Kim, D.-H.; Lee, S.-W. Bull. Korean Chem.
Soc. 1996, 17, 663.
(15) Hughes, R. P.; Ward, A. J.; Golen, J. A.; Incarvito, C. D.;
Rheingold, A. L.; Zakharov, L. N. Dalton Trans. 2004, 2720.
505 (m) cm-1
.

Pd Complexes with a Silsesquioxanate Ligand
Organometallics, Vol. 27, No. 4, 2008 523
Preparation of trans-[Pd{(c-C5H9)7Si7O10(OH)2}(C6F5)-
Reaction of trans-[Pd{(c-C5H9)7Si7O10(OH)2}(Ph)(tmeda)]
(2a) with an Excess of PMe3. To a solution of palladasilsesqui-
oxane 2a (100 mg, 0.085 mmol) in toluene (3 mL) was added an
excess of PMe3 (35 µL, 0.34 mmol) at room temperature. The
reaction mixture was stirred at room temperature for 13 h. The
solvent was removed under reduced pressure. The resulting material
was washed twice with 3 mL of acetone to yield 4a as a white
solid (87.1 mg, 85%).
X-ray Crystallography. Crystals of 4b suitable for an X-ray
diffraction study were sealed in glass capillaries. Data for 4b were
collected at -160 °C on a Rigaku Saturn CCD diffractometer
equipped with monochromated Mo KR radiation (λ ) 0.71073 Å).
Calculations were carried out using the program package Crystal
Structure, version 3.7, for Windows. A full-matrix least-squares
refinement was used for the non-hydrogen atoms with anisotropic
thermal parameters. Hydrogen atoms, except for the OH hydrogens
of 4b, were located by assuming the ideal geometry and were
included in the structure calculations without further refinement of
the parameters. Crystallographic data and details of refinement are
summarized in Table 2.
(PMe3)2](4b). To
a toluene (10 mL) solution of trans-
[Pd(I)(C6F5)(PMe3)2] (65.3 mg, 0.12 mmol) were added (c-
C5H9)7Si7O9(OH)3 (105 mg, 0.12 mmol) and Ag2O (33.4 mg, 0.14
mmol). The mixture was stirred for 4 days at room temperature.
The toluene suspension was filtrated through Celite, and the solvent
was pumped off. The residual solid substance was washed twice
with 3 mL of acetone and dried in Vacuo to give 4b as a white
solid (122 mg, 78%). Anal. Calcd for C47H83O12P2PdSi7: C, 43.42;
H, 6.43; F, 7.31. Found: C, 43.24; H, 6.47; F, 7.14. 1H NMR (400
MHz, C6D6, room temperature): δ 0.93 (apparent triplet due to
virtual coupling, 18H, PCH3, splitting 3.2 Hz), 1.16 (m, 7H, CH
pentyl), 1.56, 1.74, 1.99, 2.21 (56H, CH2 pentyl), 8.34 (br, 2H,
OH). 13C{1H} NMR (100 MHz, toluene-d8, room temperature): δ
13.8 (apparent triplet due to virtual coupling, PCH3, splitting 15
Hz), 23.1, 23.3, 23.8, 24.0, 27.4 (CH pentyl), 27.5, 27.6, 28.1, 28.1,
28.3, 28.4, 28.5, 29.8 (CH2 pentyl), 113.9 (m, C6F5 ipso), 137.1
(m, C6F5 meta, JF-C ) 254 Hz) 138.0 (m, C6F5 para, JF-C ) 244
Hz), 146.9 (m, C6F5 ortho, JF-C ) 227 Hz). 19F{1H} NMR (376
MHz, toluene-d8, room temperature): δ -162.1 (2F, C6F5 meta),
-159.3 (1F, C6F5 para), -117.5 (2F, C6F5 ortho). 19F{1H} NMR
(376 MHz, toluene-d8, -50 °C): δ -162.1 (m, 1F, C6F5 meta),
-161.5 (m, 1F, C6F5 meta), -158.7 (t, 1F, C6F5 para, JF-F ) 20
Hz), -117.9 (d, 1F, C6F5 ortho, JF-F ) 29 Hz), -117.1 (d, 1F,
C6F5 ortho, JF-F ) 29 Hz). 31P{1H} NMR (162 MHz, C6D6, room
temperature): δ -14.3. 29Si{1H} NMR (79.3 MHz, toluene-d8, 0.02
M Cr(acac)3, room temperature): δ -67.6, -65.1, -65.0, -58.0,
-56.9 (ratio 2:1:1:1:2). IR data (KBr): 3300 (br), 2950 (s), 2867
Acknowledgment. This work was financially supported
by a Grant-in-Aid for Scientific Research for Young Chem-
ists (No. 80376962) and for Scientific Research on Priority
Areas, from the Ministry of Education, Culture, Sport,
Science, and Technology of Japan.
Supporting Information Available: Crystallographic data for
4b as a CIF file. This material is available free of charge via the
Internet at http://pubs.acs.org.
(s), 1504.7 (s), 1458 (s), 1111 (w), 951 (s), 504 (m) cm-1
.
OM700827F