[(Piperidinomethyl)silylmethyl] cyclopalladated complexes: Their synthesis, reactivity, and solid state structures

Article abstract of DOI:10.1021/om040028+

The reaction of Ph₂Si(CH₂Li)(CH₂NC ₅H₁₀) (2) (CH₂NC₅H₁₀ = piperidinomethyl) with trans-[PdCl₂(SMe₂)₂] leads to dimeric [Pd{CH₂SiPh₂(CH₂NC ₅H₁₀)-κ²C,N}(μ-Cl)]₂ (3), where the [CH₂-SiPh₂(CH₂NC₅H ₁₀)-κ²C,N] ligand forms a palladacycle, as revealed by the crystal structure of the transoid isomer. In solution, this chloro-bridged dimer exists as a mixture of the cisoid and the transoid isomer. Monodentate ligands cleave the chloro bridges of dimer 3 to give compounds of the type [Pd{CH₂SiPh₂(CH₂NC₅H ₁₀)-κ²C,N}ClL] [L = PPh₃ (4), PMe ₃ (5), CNⁱBu (6), 4-methylpyridine (4-MePy) (7), tetrahydrothiophene (tht) (8), SMe₂ (9)], where the incoming ligand and the metalated carbon center are coordinated cis. The tetrafluoroborate salt of the cationic complex [Pd{CH₂SiPh₂(CH₂NC ₆H₁₀)-κ₂C,N}(4-MePy)₂] (11) is obtained by treating the starting dimer 3 with TlBF₄ and 4-MePy. The addition of Ph₂PCH₂CH₂PPh₂ (dppe) to the starting dimer 3 leads to [{Pd₂[CH₂SiPh ₂(CH₂NC₅H₁₀)-κ²C,N] ₂Cl₂}-(u-dppe)] (13) or to [Pd{CH₂SiPh ₂(CH₂NC₅H₁₀)-κ²C,N} (dppe)]Cl (11), depending on the stoichiometry. NMR data reveal that the Pd-N bond in 11 is transiently opened in solution. [Pd{CH₂SiPh ₂(CH₂NC₅H₁₀)-κ²C,N} (dppe)]BF₄ (14) is obtained from the latter compound upon treatment with TlBF₄. The chelate complexes [Pd{CH₂SiPh ₂(CH₂NC₅H₁₀)-κ²C,N} (acac)] (16) (acac = acetylacetonate) and [Pd{CH₂SiPh ₂(CH₂NC₅H₁₀)-κ²C,N} (S₂CNEt₂)] (15) are obtained by reaction of the starting chloro-bridged dimer 3 with Tl(acac) and NaS₂CNEt₂, respectively. The solid state structures of palladacycles 3, 4, 8, 9, 10, and 15 were determined by X-ray diffraction methods.

Full text of DOI:10.1021/om040028+

3228
Organometallics 2004, 23, 3228-3238
[(P ip er id in om eth yl)silylm eth yl] Cyclop a lla d a ted
Com p lexes: Th eir Syn th esis, Rea ctivity, a n d Solid Sta te
Str u ctu r es
Daniel Schildbach,† Marta Arroyo,‡ Klaus Lehmen,† Susana Mart´ın-Barrios,‡
Luisa Sierra,‡ Fernando Villafan˜e,*,‡ and Carsten Strohmann*,†
Institut fu¨r Anorganische Chemie, Universita¨t Wu¨rzburg, Am Hubland,
97074 Wu¨rzburg, Germany, and Qu´ımica Inorga´nica, Facultad de Ciencias,
Universidad de Valladolid, 47005 Valladolid, Spain
Received March 8, 2004
The reaction of Ph2Si(CH2Li)(CH2NC5H10) (2) (CH2NC5H10 ) piperidinomethyl) with trans-
[PdCl2(SMe2)2] leads to dimeric [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}(µ-Cl)]2 (3), where the [CH2-
SiPh2(CH2NC5H10)-κ2C,N] ligand forms a palladacycle, as revealed by the crystal structure
of the transoid isomer. In solution, this chloro-bridged dimer exists as a mixture of the cisoid
and the transoid isomer. Monodentate ligands cleave the chloro bridges of dimer 3 to give
compounds of the type [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}ClL] [L ) PPh3 (4), PMe3 (5),
CNtBu (6), 4-methylpyridine (4-MePy) (7), tetrahydrothiophene (tht) (8), SMe2 (9)], where
the incoming ligand and the metalated carbon center are coordinated cis. The tetrafluo-
roborate salt of the cationic complex [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}(4-MePy)2] (11) is
obtained by treating the starting dimer 3 with TlBF4 and 4-MePy. The addition of Ph2PCH2-
CH2PPh2 (dppe) to the starting dimer 3 leads to [{Pd2[CH2SiPh2(CH2NC5H10)-κ2C,N]2Cl2}-
(µ-dppe)] (13) or to [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}(dppe)]Cl (11), depending on the
stoichiometry. NMR data reveal that the Pd-N bond in 11 is transiently opened in solution.
[Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}(dppe)]BF4 (14) is obtained from the latter compound upon
treatment with TlBF4. The chelate complexes [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}(acac)] (16)
(acac ) acetylacetonate) and [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}(S2CNEt2)] (15) are obtained
by reaction of the starting chloro-bridged dimer 3 with Tl(acac) and NaS2CNEt2, respectively.
The solid state structures of palladacycles 3, 4, 8, 9, 10, and 15 were determined by X-ray
diffraction methods.
Sch em e 1
In tr od u ction
As part of our systematic studies on metalated orga-
nosilanes, we are interested in the structure and
reactivity of [(aminomethyl)silylmethyl]metal com-
pounds (type A).1,2a,b Two stabilizing effects play a role
in these metal alkyls: the silicon center prevents
â-hydrogen elimination and stabilizes the metalated
R-carbon center. The (aminomethyl) substituent coor-
dinates to the reactive center (intramolecular stabiliza-
tion by chelation) and can induce the essential stereo-
chemical information when chiral amines are introduced.
Thus, this concept allowed the synthesis of highly
diastereomerically enriched [(aminomethyl)silylmethyl]-
lithium compoundsswhere the metalated carbon center
is a stereogenic center with a defined absolute config-
uration (type B)2sleading to two areas for further
study: (a) determining and understanding the directing
factors for the regioselective and/or stereoselective
metalation of organosilanes and (b) transferring the
stereogenic lithiated carbon centers to organic mol-
ecules, heteroelement systems, or different metal com-
plex fragments by metathesis reactions (type C) (Scheme
1).
Dedicated to Professor Wolfdieter A. Schenk on the occasion of
his 60th birthday.
* Corresponding
authors.
E-mail
(C.S.):
mail@
carsten-strohmann.de; (F.V.) fervilla@qi.uva.es.
† Universita¨t Wu¨rzburg.
‡ Universidad de Valladolid.
(1) (a) Strohmann, C.; Abele, B. C.; Lehmen, K.; Villafan˜e, F.; Sierra,
L.; Mart´ın-Barrios, S.; Schildbach, D. J . Organomet. Chem. 2002, 661,
149. (b) Strohmann, C.; Ulbrich, O.; Auer, D. Eur. J . Inorg. Chem. 2001,
1013. (c) Strohmann, C.; Abele, B. C. Organometallics 2000, 19, 4173.
(d) Strohmann, C.; Abele, B. C.; Schildbach, D.; Strohfeldt, K. J . Chem.
Soc., Chem. Commun. 2000, 865. (e) Abele, B. C.; Strohmann, C. In
Organosilicon Chemistry III; Auner, N., Weis, J ., Eds.; VCH: Weinheim
(Germany), 1997; p 206. (f) Strohmann, C.; Lehmen, K.; Ludwig, A.;
Schildbach, D. Organometallics 2001, 20, 4138.
(2) (a) Strohmann, C.; Buchold, D. H. M.; Wild, K.; Schildbach, D.
In Organosilicon Chemistry V; Auner, N., Weis, J ., Eds.; Wiley-VCH:
Weinheim (Germany), 2003; p 155. (b) Strohmann, C.; Lehmen, K.;
Wild, K.; Schildbach, D. Organometallics 2002, 21, 3079. (c) Chan, T.
H.; Pellon, P. J . Am. Chem. Soc. 1989, 111, 8737. (d) Fraenkel, G.;
Duncan, J . H.; Martin, K.; Wang, J . J . Am. Chem. Soc. 1999, 121,
10538.
Herein we report on the coordination of an [(amino-
methyl)silylmethyl] ligand, in particular [(piperidino-
methyl)silylmethyl] ([CH2SiPh2(CH2NC5H10)-κ2C,N]), to
10.1021/om040028+ CCC: $27.50 © 2004 American Chemical Society
Publication on Web 05/18/2004

[(Piperidinomethyl)silylmethyl] Pd Complexes
Organometallics, Vol. 23, No. 13, 2004 3229
palladium complex fragments. There are very few
reports on palladium complex fragments with [(ami-
nomethyl)silylmethyl] ligands, which has prompted us
to investigate the chemical behavior of the nonchiral
ligand [CH2SiPh2(CH2NC5H10)-κ2C,N] prior to any at-
tempt to coordinate a chiral ligand. The rarity of
palladium complexes with these types of nonchiral
ligands makes the corresponding cyclopalladated com-
plexes systems of great synthetic interest, especially in
order to approach the corresponding enantiomerically
enriched systems of type C.
Cyclopalladated complexes are important in several
areas, from the synthesis of organic compounds to
interdisciplinary aspects, such as their use in the design
of new materials.3 The system more commonly used is
a five-membered orthometalated ring containing an sp2-
hybridized carbon and the nitrogen center of an amine
as donor atoms,4 although palladacycles of rather
complicated structures may be designed and have been
described.4 However, this variety has not been extended
to the presence of heteroatoms in the palladacycle in
order to elucidate how these heteroatoms would affect
the stability, the chemical properties, and the structural
aspects of compounds of this type. There are only very
few precedents of palladacycles containing silicon cen-
ters in the ring.5
F igu r e 1. Molecular structure and numbering scheme of
compound 3 in the crystal (ORTEP plot, ellipsoids drawn
at 50% probability level). Selected distances (Å) and angles
(deg): Pd-C(1) 2.034(2), Pd-N 2.126(2), Pd-Cl 2.329(1),
Pd-Cl′ 2.491(1), Pd-Si 2.915(1), Si-C(1) 1.855(3), C(1)-
Pd-N 86.81(9), C(1)-Pd-Cl 89.21(7), N-Pd-Cl 175.72-
(6), C(1)-Pd-Cl′ 163.51(8), Pd-Cl-Pd′ 95.26(3), Cl-Pd-
Cl′ 84.74(3), C(1)-Si-C(14) 104.4(1), Si-C(1)-Pd 97.0(1),
C(14)-Si-Pd 70.43(7), N-C(14)-Si 108.2(2).
carbon by treating Ph2SiMe(CH2NC5H10) (1) with pal-
ladium acetate were not successful: deposition of metal-
lic palladium was observed, and only unreacted silane
was recovered from the solution. This method had been
successively employed to coordinate 2-(trimethylsilyl)-
pyridine or R-(trimethylsilyl)-8-methylquinoline to pal-
ladium(II),5a,7 although these complexes were not crys-
tallographically characterized. Furthermore, there are
only a few reports on solid state structural determina-
tions of silapalladacycles5b,c and of (silylmethyl)palla-
dium compounds.6,8
The molecular structure found for 3 and relevant
distances and angles are shown in Figure 1. The
geometry observed is the transoid isomer of the dimer,
which is centrosymmetrical, the palladium and chlorine
centers of the central four-membered ring being co-
planar. This is in sharp contrast to the reported
structure of the complex [Pd{C(SiMe3)2SiMe2(2-C5H4N)-
κ2C,N}(µ-Cl)]2 (2-C5H4N ) 2-pyridinyl),5b where the
dihedral angle between the coordination planes at the
Cl-Cl axis is 60°. In this case, the cyclometalated ligand
is bulkier and has more donor potential (two SiMe3
substituents instead of two hydrogen atoms). At the
same time, it is more π-acidic (pyridine instead of
piperidine) than our [(piperidinomethyl)silylmethyl]
ligand. It has been suggested that bent halogen-bridged
complexes are formed when the ligands are strong
σ-donors and/or strong π-acceptors.9 Each palladium
Resu lts a n d Discu ssion
Syn th esis of [P d {CH2SiP h 2(CH2NC5H10)-K2C,N}-
(µ-Cl)]2 (3). The reaction between equimolar amounts
of the organolithium compound Ph2Si(CH2Li)(CH2-
NC5H10) (2)1e and trans-[PdCl2(SMe2)2] leads to the
dimer [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}(µ-Cl)]2 (3) in
72% yield (Scheme 2). The doubly cyclometalated mono-
nuclear complex [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}2]
could not be detected. This is in contrast to the observa-
tion that complexes of the type [PdCl2(SR2)2] tend to give
symmetrical doubly cyclometalated compounds when
treated with the appropriate organolithium reagents.6
The attempts to coordinate the [(aminomethyl)silyl-
methyl] ligand by direct metalation of the aliphatic
(3) For examples see: (a) Ryabov, A. D. Synthesis 1985, 233. (b)
Newkome, G. R.; Puckett, W. E.; Gupta, V. K.; Kiefer, G. E. Chem.
Rev. 1986, 86, 451. (c) Ryabov, A. D. Chem. Rev. 1990, 90, 403. (d)
Pfeffer, M. Pure Appl. Chem. 1992, 64, 335. (e) Wild, S. B. Coord. Chem.
Rev. 1997, 166, 291. (f) Steenwinkel, P.; Gossage, R. A.; van Koten, G.
Chem. Eur. J . 1998, 4, 759. (g) Herrmann, W. A.; Bo¨hm, V. P. W.;
Reisinger, C.-P. J . Organomet. Chem. 1999, 576, 23. (h) Rybtschinski,
B.; Milstein, D. Angew. Chem., Int. Ed. 1999, 38, 870. (i) Espinet, P.;
Esteruelas, M. A.; Oro, L. A.; Serrano, J . L.; Sola, E. Coord. Chem.
Rev. 1992, 117, 215. (j) Navarro-Ranninger, C.; Lo´pez-Solera, I.;
Gonza´lez, V. M.; Pe´rez, J . M.; AÄ lvarez-Valde´s, A.; Mart´ın, A.; Raithby,
P.; Masaguer, J . R.; Alonso, C. Inorg. Chem. 1996, 35, 5181. (k) Gianini,
M.; von Zelewsky, A.; Stoeckli-Evans, H. Inorg. Chem. 1997, 36, 6094.
(l) Albert, J .; Cadena, J . M.; Granell, J .; Muller, G.; Ordinas, J . I.;
Panyella, D.; Puerta, C.; San˜udo, C.; Valerga, P. Organometallics 1999,
18, 3511. (m) He, G.; Mok, K. F.; Leung, P.-H. Organometallics 1999,
18, 4027. (n) Vicente, J .; Saura-Llamas, I.; Turp´ın, J .; Ram´ırez de
Arellano, M. C.; J ones, P. G. Organometallics 1999, 18, 2683. (o) Zhao,
G.; Yang, Q.-C.; Mak, T. C. W. Organometallics 1999, 18, 3623. (p)
Dupont, J .; Pfeffer, M.; Spencer, J . Eur. J . Inorg. Chem. 2001, 1917.
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Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: Oxford
(UK), 1995; Vol. 9, Chapter 5.5.
(7) Pereira, M. T.; Pfeffer, M.; Rotteveel, M. A. J . Organomet. Chem.
1989, 375, 139.
(8) [PdCH2SiR3]: (a) Gutie´rrez, E.; Nicasio, M. C.; Paneque, M.;
Ruiz, C.; Salazar, V. J . Organomet. Chem. 1997, 549, 167. (b) Al´ıas,
F. M.; Belderra´ın, T. R.; Carmona, E.; Graiff, C.; Paneque, M.;
Tiripicchio, A. J . Organomet. Chem. 1999, 577, 316. [PdCH(SiR3)2]:
(c) Al´ıas, F. M.; Belderra´ın, T. R.; Paneque, M.; Poveda, M. L.;
Carmona, E.; Valerga, P. Organometallics 1997, 16, 301. (d) Al´ıas, F.
M.; Belderra´ın, T. R.; Paneque, M.; Poveda, M. L.; Carmona, E.;
Valerga, P. Organometallics 1998, 17, 5620. [PdC(SiR3)3]: Other
structures with the Pd-C-Si moiety: (e) Buchanan, R. M.; Pierpoint,
C. G. Inorg. Chem. 1979, 18, 3608. (f) Maassarani, F.; Pfeffer, M.; Le
Borgne, G.; Wehman, E.; van Koten, G. J . Am. Chem. Soc. 1984, 106,
8002. (g) Onitsuka, K.; Segawa, M.; Takahashi, S. Organometallics
1998, 17, 4335. (h) Konze, W. V.; Young, V. G., J r.; Angelici, R. J .
Organometallics 1998, 17, 5275.
(5) (a) Fuchita, Y.; Nakashima, M.; Hiraki, K.; Kawatani, M. J .
Chem. Soc., Dalton Trans. 1988, 785. (b) Eaborn, C.; Hill, M. S.;
Hitchcock, P. B.; Smith, J . D. J . Chem. Soc., Chem. Commun. 2000,
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8773.
(6) Maassarani, F.; Pfeffer, M.; Le Borgne, G.; J astrzebski, J . T. B.
H.; van Koten, G. Organometallics 1987, 6, 1111, and references
therein.

3230 Organometallics, Vol. 23, No. 13, 2004
Schildbach et al.
Sch em e 2
Sch em e 3
center of compound 3 is also intramolecularly coordi-
nated by the nitrogen center and the carbon center of
the corresponding [CH2SiPh2(CH2NC5H10)-κ2C,N] moi-
ety, forming the palladacycle. The carbon donor center
C(1) deviates slightly by 0.21 Å from the square
coordination plane (rms deviation of fitted atoms ) 0.15
Å). The Pd-C(1) distance of 2.034(2) Å is in the range
found for Pd-C(sp3) single bonds (between 2.00 and 2.19
Å).10 The difference in the two distances Pd-Cl ) 2.329-
(1) and Pd-Cl′ ) 2.491(1) Å reflects the strong electron-
donating properties of the (silylmethyl) ligand, giving
rise to a high trans influence. However, the discrepancy
of these distances is similar to those found in other
chloro-bridged cyclopalladated dimers with transoid
geometry,11 regardless of whether the carbon donor
center is part of an aliphatic or aromatic system.12
The conformation of the five-membered palladacycle
Pd-C(1)-Si-C(14)-N may be described as an envelope
with the palladium atom 1.27 Å out of the least-squares
plane defined by the other four atoms in the metalla-
cycle (rms deviation of fitted atoms ) 0.01 Å). Other
palladacycles that may adopt this conformation, such
as those with tetrahedral donor atoms (sp3 carbon and
sp3 nitrogen), are pseudoplanar12b or with envelope
conformation.12a,c,f
The H and 13C NMR spectra of 3 at room tempera-
ture in a CDCl3 solution show the presence of two
isomers in a 65:35 ratio, suggested by two singlets
observed for each PdCH2Si and each SiCH2N methylene
group, indicating the presence of a cisoid isomer (D) and
a transoid isomer (E) (Scheme 3). This is commonly
observed for cyclopalladated systems where the alkyl
group has a strong trans influence.12a,b,14 A slow equi-
librium on the NMR time scale is proposed between the
isomers, since the signals of each isomer coalesce in the
1H NMR spectra recorded at higher temperatures. At
70 °C in C6D6, only one singlet is detected for the
SiCH2N group.
The ratio between these stereoisomers is very similar
in solvents of different polarity (CDCl3, C6D6, and thf-
d8 have been used). This observation is surprising, since
polar solvents usually give rise to an increase in the
ratio of the polar isomer (cisoid).15 Therefore, it is not
possible to assign unequivocally the resonance signals
in the 1H and 13C{1H} NMR spectra to each isomer.
Thus, the major isomer in solution has been tentatively
assigned to the transoid isomer, which is that found in
the crystal structure.
1
The presence of palladium and silicon in a five-
membered palladacycle makes the distance Pd-Si )
2.915(1) Å short and the angle Si-C1-Pd ) 97.0(1)°
small, compared to those found in [(trialkylsilyl)methyl]
palladium complexes (3.2 Å and 110° average).13
1
In the H NMR spectra, a singlet signal is observed
The Si-C stretching absorptions of 3 (and of the other
cyclopalladated complexes described in this work) in the
IR spectrum are found at 1100 cm-1 and in the range
between 800 and 700 cm-1, frequencies slightly lower
than those previously reported (1243 and 850-820
cm-1) for [(trialkylsilyl)methyl] ligands.16
for each methylene group of all the palladacycles
described in this work, unless NMR active heterocores,
such as 31P, are present in the corresponding complex.
This suggests that a ring inversion process, in which
the centers Si and C(14) flip from one side to the other,
is rapid on the NMR time scale.
Rea ctivity of 3 tow a r d Mon od en ta te Liga n d s. To
study the reactivity of complex 3, a variety of mono-
dentate and bidentate ligands of different geometric and
electronic characteristics, neutral or anionic, were cho-
sen. The simplest ligands for reactivity studies of 3 are
monodentate neutral ligands, and the expected product
should be the result of cleaving the chloro bridges of
the starting dimer.3l,12f,17
The phosphines PPh3 and PMe3 react with 3, giving
the mononuclear complexes of the type [Pd{CH2SiPh2-
(CH2NC5H10)-κ2C,N}Cl(PR3)] [R ) Ph (4), Me (5)]. The
phosphorus center and the carbon center of the ring are
(9) Aullo´n, G.; Ujaque, G.; Lledo´s, A.; Alvarez, S.; Alemany, P. Inorg.
Chem. 1998, 37, 804.
(10) (a) Maitlis, P. M.; Espinet, P.; Rusell, M. J . H. In Comprehensive
Organometallic Chemistry, Wilkinson, G., Stone, F. G. A., Abel, E. W.,
Eds.; Pergamon: Oxford (UK), 1982; Vol. 6, pp 333-334. (b) Reference
4, pp 271-272.
(11) The structures obtained after
a search of chloro-bridging
complexes in the Cambridge Crystallographic Database showed similar
discrepancies in the Pd-Cl distances, which seems to indicate that
this feature is not associated with the electronic or steric factors of
the cylopalladated ligand.
(12) Examples with aliphatic donor atoms: (a) Alyea, E. C.; Dias,
S. A.; Ferguson, G.; McAlees, A. J .; McCrindle, R.; Roberts, P. J . J .
Am. Chem. Soc. 1977, 99, 4985. (b) Galli, B.; Gasparrini, F.; Mann, B.
E.; Maresca, L.; Natile, G.; Manotti-Lanfredi, A. M.; Tiripicchio, A. J .
Chem. Soc., Dalton Trans. 1985, 1155. (c) Suggs, J . W.; Lee, K. S. J .
Organomet. Chem. 1986, 299, 297. (d) Dupont, J .; Halfen, R. A. P.;
Schenato, R.; Berger, A.; Horner, M.; Bortoluzzi, A.; Maichle-Mossmer,
C. Polyhedron 1996, 15, 3465. Examples with aromatic donor atoms:
(e) Barr, N.; Dyke, S. F.; Smith, G.; Kennard, C. H. L.; McKee, V. J .
Organomet. Chem. 1985, 288, 109. (f) Zhao, G.; Wang, Q.-G.; Mak, T.
C. W. J . Chem. Soc., Dalton Trans. 1998, 1241.
(14) (a) Mutet, C.; Pfeffer, M. J . Organomet. Chem. 1979, 171, C34.
(b) Dehand, J .; Mutet, C.; Pfeffer, M. J . Organomet. Chem. 1981, 209,
255. (c) Weinberg, E. L.; Hunter, B. K.; Baird, M. C. J . Organomet.
Chem. 1982, 240, 95.
(15) (a) Ladipo, F. T.; Anderson, G. K. Organometallics 1994, 13,
303. (b) Anderson, G. K.; Cross, R. J .; Manojlovic-Muir, L.; Muir, K.
W.; Solomun, T. J . Organomet. Chem. 1979, 170, 385.
(16) (a) Wozniak, B.; Ruddick, J . D.; Wilkinson, G. J . Chem. Soc. A
1971, 3116. (b) Kelly, R. D.; Young, G. B. J . Organomet. Chem. 1989,
361, 123.
(13) A search of the Cambridge Crystallographic Database yielded
8 complexes with 16 Pd-C(sp3)-SiC3 moieties, with Pd-Si distances
3.054-3.371 Å, mean 3.249 Å; and Pd-C-Si angles 99.5-119.2°, mean
109.9°.

[(Piperidinomethyl)silylmethyl] Pd Complexes
Organometallics, Vol. 23, No. 13, 2004 3231
Sch em e 4
Sch em e 5
F igu r e 2. Molecular structure and numbering scheme of
compound 4 in the crystal (ORTEP plot, ellipsoids drawn
at 50% probability level). Selected distances (Å) and angles
(deg): Pd-C(1) 2.067(5), Pd-N 2.212(4), Pd-P 2.238(1),
Pd-Cl 2.404(1), Si-C(1) 1.824(4), Pd-Si 3.069(2), C(1)-
Pd-N 90.0(2), C(1)-Pd-P 92.9(1), N-Pd-P 175.9(1),
C(1)-Pd-Cl 177.7(1), N-Pd-Cl 91.1(1), P-Pd-Cl 86.13-
(5), C(1)-Si-C(14) 100.4(2), C(14)-N-Pd 111.4(3), Si-
C(1)-Pd 103.9(2), N-C(14)-Si 110.2(3).
case of the phosphine complexes 4 and 5, is proposed
for the additional complexes obtained after treatment
of 3 with neutral monodentate ligands: [Pd{CH2SiPh2-
(CH2NC5H10)-κ2C,N}ClL] [L ) CNtBu (6), 4-MePy (7),
tht (8), SMe2 (9)]. The fact that this cis isomer has
always been isolated for cyclometalated complexes of the
type [Pd(C-N)ClL] (C-N ) cyclometalated ligand)19
may be explained considering the higher trans influence
of the carbon donor ligand and of the incoming ligand
L (or the lower trans influence of the nitrogen and the
chloro ligand). The result is a cis configuration, which
is in agreement with the antisymbiotic effect of the soft
palladium(II)center20 or with what has been more
recently defined as the transphobia effect.21
coordinated cis, which was confirmed by an X-ray
diffraction study of 4 (the structure found for 4 and
relevant distances and angles are shown in Figure 2).
The coordination geometry of the complex is essentially
square planar (the phosphorus atom deviates out of a
least-squares plane by only 0.05 Å, rms deviation of
fitted atoms [Pd, Cl, N, C(1), P] ) 0.04 Å), and the Pd-
C(1) distance of 2.067(5) Å is again in the usual range
found for Pd-C(sp3) single bonds (between 2.00 and 2.19
Å).10 The metallacycle shows an envelope conformation,
but this time the silicon is the center located 0.86 Å
outside of the least-squares plane defined by the other
four atoms in the metallacycle (rms deviation of fitted
atoms ) 0.03 Å), which is a smaller value than for
compound 3 (0.86 vs 1.27 Å). The Pd-Si distance [3.069-
(2) Å] and the Si-C1-Pd angle [103.9(2)°] are between
the values found for 3 and other [(trialkylsilyl)methyl]
palladium complexes, as indicated above.13 The dis-
tances and angles are very similar to those found for
the structure of the related complex [Pd{CH2SiMe2(2-
C5H4N)-κ2C,N}Cl(PPh3)].5c
Phosphines and pyridines are usually used to cleave
the chloro bridges in cyclometalated systems in order
to get more soluble species, since the bridged dimeric
chloro complexes are almost insoluble in many solvents
and are sometimes difficult to characterize, whereas the
monomeric species with phosphines or pyridines are
more soluble. We carried out these processes to obtain
compounds 6 and 7 (Scheme 4), which are usually
described in the chemistry of palladacycles19 (even
though our starting product is readily soluble in most
common organic solvents). Stoichiometric amounts of 3
and the ligand CNtBu or 4-MePy were used for the
synthesis of complexes 6 and 7, but large excesses of
tht or SMe2 are needed to obtain 8 or 9 (Scheme 5). The
two latter complexes are stable in solution only when a
1
slight excess of the thioether is present (the H NMR
The coordination of the phosphorus center cis to the
metalated carbon center C(1) is most probably main-
tained in solution, as the resonance signals of these
atoms show low P-H coupling constants in the 1H NMR
and no P-C coupling in the 13C{1H} NMR spectra at
all.18
spectrum of 8 shows the presence of ca. 10% of 3, unless
an excess of tht is added). These facts must be explained
considering the equilibrium shown in Scheme 5, which
(18) P-H couplings in aliphatic palladacycles are lower (ca. 3-4 Hz)
when the R-C and the phosphine are cis than those found when are
trans (ca. 7-8 Hz); see for example: (a) Constable, A. G.; McDonald,
W. S.; Sawkins, L. C.; Shaw, B. L. J . Chem. Soc., Dalton Trans. 1980,
1992. (b) Fuchita, Y.; Hiraki, K.; Matsumoto, Y. J . Organomet. Chem.
1985, 280, C51. P-C coupling in aliphatic metallacycles is very low
(0-13 Hz) when the R-C and the phosphine are cis, but much higher
(70-80 Hz) when trans; see for example ref 14c or: (c) Deeming, A. J .;
Rothwell, I. P. J . Organomet. Chem. 1981, 205, 117.
(19) (a) Omae, I. Chem. Rev. 1979, 79, 287. (b) Bruce, M. I. Angew.
Chem., Int. Ed. Engl. 1977, 16, 73. (c) Reference 10a, p 321.
(20) Pearson, R. G. Inorg. Chem. 1973, 12, 712.
(21) (a) Vicente, J .; Arcas, A.; Bautista, D.; J ones, P. G. Organome-
tallics 1997, 16, 2129. (b) Vicente, J .; Abad, J . A.; Frankland, A. D.;
de Arellano, M. C. R. Chem. Eur. J . 1999, 5, 3066.
The same cis coordination, supported by solid state
structural data for 4 and by NMR spectroscopy in the
(17) (a) Ryabov, A. D.; Kuz’mina, L. G.; Polyakov, V. A.; Kazankov,
G. M.; Ryabova, E. S.; Pfeffer, M.; van Eldik, R. J . Chem. Soc., Dalton
Trans. 1995, 999. Other recent references: (b) Gu¨l, N.; Nelson, J . H.
Organometallics 2000, 19, 91, and references therein. (c) Liu, X.; Mok,
K. F.; Vittal, J . J .; Leung, P.-H. Organometallics 2000, 19, 3722. (d)
Kurita, J .; Usuda, F.; Yasuike, S.; Tsuchiya, T.; Tsuda, Y.; Kiuchi, F.;
Hosoi, S. J . Chem. Soc., Chem Commun. 2000, 191, and references
therein. (e) Aplin, R. T.; Doucet, H.; Hooper, M. W.; Brown, J . M. J .
Chem. Soc., Chem. Commun. 1997, 2097, and references therein.

3232 Organometallics, Vol. 23, No. 13, 2004
Schildbach et al.
F igu r e 4. Molecular structure and numbering scheme of
compound 9 in the crystal (ORTEP plot, ellipsoids drawn
at 50% probability level). Selected distances (Å) and angles
(deg): Pd-C(1) 2.051(2), Pd-N 2.161(2), Pd-S 2.2743(5),
Pd-Cl 2.4281(5), Si-C(1) 1.837(2), Pd-Si 3.148(2), C(1)-
Pd-N 91.59(7), C(1)-Pd-S 88.79(6), N-Pd-S 179.39(4),
C(1)-Pd-Cl 174.49(7), N-Pd-Cl 91.76(4), S-Pd-Cl 87.91-
(2), C(1)-Si-C(14) 101.01(9), C(14)-N-Pd 111.2(1), Si-
C(1)-Pd 108.0(1), N-C(14)-Si 109.8(1).
F igu r e 3. Molecular structure and numbering scheme of
compound 8 in the crystal (ORTEP plot, ellipsoids drawn
at 50% probability level). Selected distances (Å) and angles
(deg): Pd-C(1) 2.062(2), Pd-N 2.175(2), Pd-S 2.2823(7),
Pd-Cl 2.4209(7), Si-C(1) 1.840(2), Pd-Si 3.155(2), C(1)-
Pd-N 91.26(8), C(1)-Pd-S 86.50(7), N-Pd-S 175.35(5),
C(1)-Pd-Cl 177.02(7), N-Pd-Cl 91.66(5), S-Pd-Cl 90.54-
(2), C(1)-Si-C(14) 100.54(10), C(14)-N-Pd 111.29(13),
Si-C(1)-Pd 107.76(11), N-C(14)-Si 110.16(14).
determined: Si deviates from the plane by 0.30 Å, rms
deviation of fitted atoms [Pd, C(1), Si, C(14), N] ) 0.22
Å for compound 8; for compound 9, Si deviates from the
plane by 0.29 Å, rms deviation of fitted atoms [Pd, C(1),
Si, C(14), N] ) 0.21 Å.
Because of the monomeric molecular structures of 8
and 9, an impression of the mechanism of the formation
of the dimer 3 can be gained, which can be regarded as
a two-step process: the formation of the corresponding
thioether complex first (under substitution of a chloro
ligand and extrusion of the first thioether ligand),
followed by the dimerization under extrusion of the
second thioether ligand.22
The attempts to coordinate a second monodentate
ligand, starting either from 3 or from the mononuclear
complexes 4-9, were not successful, although the
coordination of a second PPh3 ligand has been described
for similar cyclopalladated systems.19
Thus, these reactions were carried out with TlBF4 in
order to favor the removal of the chloro ligand and to
obtain cationic species. However, only the 4-MePy ligand
gave satisfactory results,23 yielding [Pd{CH2SiPh2-
(CH2NC5H10)-κ2C,N}(4-MePy)2]BF4 (10) (Scheme 6),
which was characterized from its analytical, spectro-
scopic, and crystallographic data (the structure found
for 10 and relevant distances and angles are shown in
Figure 5). The deviation from the ideal square planar
geometry lies between those values found for the
structures of 3 and 4, as the carbon donor atom deviates
by 0.12 Å from the least-squares plane of fitted atoms
is clearly biased to the right, when stoichiometric
amounts of the thioethers are used.22
The molecular structures of the thioether complexes
8 and 9 (shown together with relevant distances and
angles in Figures 3 and 4) are of particular interest,
since they are most probably intermediates in the
synthesis of the chloro-bridged dimer 3,22 due to the
lability of the sulfur ligands, which can be easily
replaced during ligand exchange reactions (Schemes 2
and 5). As expected, the sulfur and the metalated carbon
center C(1) are coordinated cis in both complexes, and
the geometry at the central palladium center of both
compounds is square planar. For the tht complex 8, the
nitrogen center deviates from a least-squares plane by
0.04 Å (rms deviation of fitted atoms [Pd, Cl, N, C(1),
S] ) 0.04 Å); the sum of the angles around the pal-
ladium center of 8 amounts to 360°. For the dimethyl-
sulfide complex 9, the metalated carbon center C(1)
deviates from a least-squares plane by 0.06 Å (rms
deviation of fitted atoms [Pd, Cl, N, C(1), S] ) 0.05 Å);
the sum of the angles around the palladium center of 9
amounts to 360° as well. The Pd-C distances in both
complexes [2.062(2) Å for 8 and 2.051(2) Å for 9] are
equal within the margin of errors, while the Pd-S
[2.2823(7) Å for 8 and 2.2743(5) Å for 9] as well as the
Pd-Cl and Pd-N distances are virtually identical. For
the envelope conformation of the palladacycle, the
following characteristics for least-squares planes were
(22) The thioether complexes 8 and 9 were detected during the first
reactions between the organolithium 2 and either trans-[PdCl2(tht)2]
or trans-[PdCl2(SMe2)2], which were used as starting materials.
Mixtures of 8 and 3 were obtained in the first case, whereas 9 was
detected as a byproduct in the synthesis of 3 in the second case before
this reaction was finally optimized. In fact, 9 is easily converted into
3 during the workup. Stirring the crude product in an acetone solution
favors the formation of 3, as it is scarcely soluble in this solvent,
whereas 9 is soluble. This method for conversion of 9 into 3 has given
the best results among others employed. Similar behavior is observed
for the tht complex 8, although the removal of tht is more difficult.
(23) Although 10 is the only cyclopalladated complex isolated when
the starting dimer 3 was treated with TlBF4 and 2 equiv of the ligand,
the reaction of 3, TlBF4, and PMe3 led to a very small amount of the
complex trans-[PdPhCl(PMe3)2]. Surprisingly, we have not found any
previous reports on this compound in the literature (see Supporting
Information for its preparation and spectroscopic data), although a
reference of the analogous platinum complex does exist: Arnold, D.
P.; Bennett, M. A. Inorg. Chem. 1984, 23, 2110.

[(Piperidinomethyl)silylmethyl] Pd Complexes
Organometallics, Vol. 23, No. 13, 2004 3233
Sch em e 7
F igu r e 5. Molecular structure and numbering scheme of
compound 10 in the crystal (ORTEP plot, ellipsoids drawn
at 50% probability level). Selected distances (Å) and angles
(deg): Pd-C(1) 2.050(5), Pd-N(1) 2.124(3), Pd-N(2) 2.180-
(4), Pd-N(3) 2.046(3), Si-C(1) 1.846(5), Pd-Si 3.091(2),
N(3)-Pd-C(1) 88.6(2), N(4)-Pd-N(1) 174.26(14), C(1)-
Pd-N(1) 87.2(2), N(4)-Pd-N(2) 87.6(1), C(1)-Pd-N(2)
171.4(2), N(1)-Pd-N(2) 97.2(1), C(1)-Si-C(14) 102.8(2),
C(14)-N(1)-Pd 107.1(2), N(1)-C(14)-Si 110.9(3), Si-
C(1)-Pd 104.9(2).
cesses. In fact, precedents on Si-C bond cleavages by
palladium salts have been reported, although more
drastic reaction conditions than the ones described here
had to be applied.25 Due to the high bond energy of the
Si-F bond, the presence of tetrafluoroborate in the
reaction mixture may also contribute to decomposition
processes.
Sch em e 6
Rea ctivity of 3 tow a r d Bid en ta te Liga n d s. Since
most of the attempts to introduce two neutral ligands
in our system failed, we focused our attention on neutral
bidentate ligands, which should give the corresponding
cationic complexes. Considerable attention was devoted
to cationic palladium complexes with bidentate ligands,
mainly because they potentially catalyze the copolym-
erization of alkenes with carbon monoxide. Diphos-
phines, such as Ph2PCH2CH2CH2PPh2 (dppp), or chelat-
ing nitrogen donor ligands, such as bipyridines, have
shown to be especially efficient in this role.26 In fact, a
palladacycle with dppp has been reported as being
highly efficient in the copolymerization process of eth-
ylene with carbon monoxide,27 and chiral Pd(II) com-
plexes, able to enantioselectively copolymerize propene
and carbon monoxide, have also been described.28 Thus,
we investigated the reactivity of 3 toward a diphosphine,
such as dppe, which can serve as a model for further
studies.
(rms deviation of fitted atoms [Pd, N(1), N(2), N(3), C(1)]
) 0.09 Å). The distance Pd-C(1) ) 2.050(5) Å is similar
to those found for 3 and 4. The difference between the
distances of both Pd-N bonds 2.180(4) and 2.046(3) Å
is similar to that found in 3, but the lack of geometric
constraints in this case, in contrast to 3, should reflect
the strong trans influence of the silylmethyl fragment.
In the envelope conformation of the five-membered ring,
the palladium center is outside of the least-squares
plane of the metallacycle, as described for 3. The Pd-
Si distance of 3.091(2) Å and the angle Si-C(1)-Pd of
104.9(2)° are the largest values of their kind of the
crystallographically studied complexes in this work.
The lack of other cationic complexes, similar to 10,
may be interpreted considering the known Si-C bond
cleavage reactions (mainly in arylsilanes).24 The re-
moval of the chloro ligand from the palladium coordina-
tion sphere by TlBF4 converts the metal center into a
strong electrophile, which may facilitate cleavage pro-
All the processes of compound 3, involving dppe, are
summarized in Scheme 7. The reactions of 3 with dppe
depend on the conditions used: the bridging dppe
complex [{Pd2[CH2SiPh2(CH2NC5H10)-κ2C,N]2Cl2}(µ-
(25) Akhrem, I. S.; Chistovalova, N. M.; Mysov, E. I.; Vol’pin, M. E.
J . Organomet. Chem. 1974, 72, 163.
(26) (a) Sen, A. Acc. Chem. Res. 1993, 26, 303. (b) Drent, E.;
Budzelaar, P. H. M. Chem. Rev. 1996, 96, 663.
(27) Schwarz, J .; Herdtweck, E.; Herrmann, W. A.; Gardiner, M. G.
Organometallics 2000, 19, 3154.
(28) (a) Nozaki, K.; Sato, N.; Takaya, H. J . Am. Chem. Soc. 1995,
117, 9911. (b) Nozaki, K.; Sato, N.; Tonomura, Y.; Yasutomi, M.;
Takaya, H.; Hyama, T.; Matsubara, T.; Koga, N. J . Am. Chem. Soc.
1997, 119, 12779.
(24) (a) Elschenbroich, C.; Salzer, A. Organometallics. A Concise
Introduction, 1st ed.; VCH: Weinheim (Germany), 1989; p 96. (b)
Negishi, E.-I. Organometallics in Organic Synthesis, Vol. 1 of General
Discussions. Organometallics of Main Group Metals in Organic
Synthesis; Wiley & Sons: Chichester (UK), 1980; Chapter 6.4.1.2. (c)
Brook, M. A. Silicon in Organic, Organometallic, and Polymer Chem-
istry; Wiley: New York, 2000; pp 379-596.

3234 Organometallics, Vol. 23, No. 13, 2004
Schildbach et al.
Sch em e 8
dppe)] (13) is obtained when a solution of dppe in
toluene is slowly added to a toluene solution of an
equimolar amount of 3. However, the chelating dppe
complex [Pd{CH2SiPh2(CH2NC5H10)-κ2C,N}(dppe)]Cl (11)
is immediately formed when both starting materials are
dissolved in dichloromethane in a 2:1 molar ratio
(Scheme 7).
The bridging dppe ligand in 13 separates both metal
centers, which behave as independent complex frag-
ments, as shown by the similarity of their spectroscopic
data and those of compound 4 or 5. The cationic complex
11 contains a chelating dppe and a chloride as the
counterion, but there is evidence from NMR spectros-
copy for the transient formation of a species with
structure 12 in solution. The reaction of 11 with TlBF4
yields the tetrafluoroborate salt of the same cation, [Pd-
{CH2SiPh2(CH2NC5H10)-κ2C,N}(dppe)]BF4 (14) (Scheme
7), which does not show any dynamic processes in
solution, probably due to the lack of nucleophilicity of
the tetrafluoroborate anion. For the molecular structure
of compound 14, a chelate complex is proposed.
than what is expected for a 1:1 electrolyte (100-140
S‚cm2‚mol-1 in acetone solution).30 This is in agreement
with the 31P{1H} NMR spectra in (CD3)2CO. The signals
observed at -60 °C are assigned to the ionic species,
whereas those obtained at room temperature with an
excess of chloride in solution are assigned to the neutral
complex (see Experimental Section). An averaged 31P-
{1H} NMR spectrum is observed in (CD3)2CO at room
temperature, but the proposed equilibrium for 11 in
Scheme 7 in (CD3)2CO is not as biased to the neutral
form as in CDCl3. Therefore, the ratio 11:12 is greater
in a donor solvent such as acetone than in a less polar
solvent such as chloroform.31
The studies on the reactivity of 3 were completed with
two bidentate anionic ligands: acac and diethyldithio-
carbamate. These ligands are also being employed to
substitute the halogen bridges in palladacycles in order
to get more soluble monometallic species.19
The reactions of 3 with equimolar amounts of the
corresponding sodium and thallium(I) salts gave [Pd-
{CH2SiPh2(CH2NC5H10)-κ2C,N}(S2CNEt2)] (15) and [Pd-
{CH2SiPh2(CH2NC5H10)-κ2C,N}(acac)] (16) (Scheme 8).
The first compound was studied by X-ray diffraction
methods (the structure found for 15 and relevant
distances and angles are shown in Figure 6).
The sulfur center S(1) deviates by only 0.07 Å from
the essentially square planar coordination plane (rms
deviation of fitted atoms [Pd, S(1), S(2), N, C(1)] ) 0.05
Å). The Pd-C(1) distance of 2.074(2) Å is similar to
those found in the other structures described. The
difference between the two Pd-S distances of compound
15, Pd-S(1) cis and Pd-S(2) trans to the metalated
carbon center C(1) [2.408(1) and 2.280(1) Å], is similar
to the corresponding differences found in compound 3
or 10, reflecting again the strong trans influence of the
[(aminomethyl)silylmethyl] fragment. These distances
are almost identical to those found when a chelating
dithiocarbamato ligand is coordinated trans to two
ligands of very different trans influence, such as an alkyl
group and an alkene.32 The palladium center is out of
the least-squares plane for the metallacycle by 1.19 Å
(rms deviation of fitted atoms [Pd, C(1), Si, C(14), N] )
0.07 Å), as observed for 3 and 10. The deviation in this
For the molecular structure of 11 in the solid state, a
chelate complex is proposed as well. In solution, this is
supported by the NMR spectra of the complex in CDCl3.
The resonance signals of 11, obtained at a temperature
where no dynamic processes, involving 12, occur (-60
°C), are coincident with those of 14. The chelate
coordination of dppe in 11 and 14 is evident from their
31P{1H} NMR spectra, which show two doublets in both
cases. A high deshielding is expected for a phosphorus
atom of the chelating dppe, as a result of the ring
contribution (∆δ) of the five-membered Pd-P-C-C-P
ring,14c,29 which explains the deshielding observed for
the phosphorus atom cis to the metalated carbon center.
On warming to room temperature, the pattern dis-
1
played by the protons of the piperidine ring in the H
NMR spectra of 11 is very different from that found at
lower temperatures or in 14, as their signals are slightly
broad and show resonances at chemical shifts similar
to those of free piperidine. This implies an uncoordi-
nated nitrogen atom. The changes in the 31P{1H} NMR
spectra on warming to room temperature are minor. The
addition of chloride ions by PPNCl [bis(triphenylphos-
phoranylidene)ammonium chloride] to this solution
causes the sharpening of the signals of dppe in the 31P
(29) Garrou, P. E. Chem. Rev. 1981, 81, 229.
(30) Geary, W. J . Coord. Chem. Rev. 1971, 7, 81.
1
NMR and of the (piperidinomethyl) protons in the H
(31) A possible alternative process to the replacement of the nitrogen
donor center by the chloride would be the substitution of the chloride
by one of the phosphorus atoms of dppe. This can be discarded from
the 31P{1H} NMR data: a process involving the decoordination of one
of the phosphorus centers would give rise to severe signal broadening
or large changes in the chemical shifts of both doublets. In fact, strong
shielding should be expected for both phosphorus resonance signals if
the dppe changes from chelate mode to monodentate mode, as the ring
contribution would not be effective. The doublet displayed by the
uncoordinated phosphorus atom would also be very shielded, as it
should show resonance near free dppe (δ ) -13.3).
NMR spectrum. This observation is in agreement with
the equilibrium for 11 proposed in Scheme 7, which is
biased to the side of the neutral form in CDCl3 at room
temperature and almost completely to the side of the
neutral form when an excess of chloride is added by
PPNCl.
The partial coordination of the chloride is supported
by the electrical conductivity data of 30 S‚cm2‚mol-1 for
the system 11/12 in acetone, which is much lower
(32) Bailey, P. M.; Taylor, S. H.; Maitlis, P. M. J . Am. Chem. Soc.
1978, 100, 4711.

[(Piperidinomethyl)silylmethyl] Pd Complexes
Organometallics, Vol. 23, No. 13, 2004 3235
distances short and the Si-C-Pd angles small, when
compared with those found in terminal [(trialkylsilyl)-
methyl] palladium complexes. Furthermore, a shorten-
ing of the Si-C bonds between silicon and the metalated
carbon center [values for Si-C(1) between 1.824(4) and
1.855(3) Å for all four different Si-C(1) bonds discussed
in this paper compared to 1.914(9) Å in a corresponding
nonmetalated silane]2a is an indicator for the stabilizing
effect of silicon centers on metalated R-carbon centers.
It is of great interest to study reactions between the
highly enantiomerically enriched lithium alkyls of type
B with palladium(II) compounds in order to obtain
highly enantiomerically enriched palladium compounds
of type C (Scheme 1), which could be valuable systems,
e.g., for the stereoselective formation of C-C bonds or
insertion reactions in the Pd-C bond. First preliminary
results on corresponding starting compounds have been
published as a review within the scope of the interdis-
ciplinary research unit SFB347 (Selective Reactions of
Metal-activated Molecules) at the University of Wu¨rz-
burg.1a
F igu r e 6. Molecular structure and numbering scheme of
compound 15 in the crystal (ORTEP plot, ellipsoids drawn
at 50% probability level). Selected distances (Å) and angles
(deg): Pd-C(1) 2.074(2), Pd-N(1) 2.155(2), Pd-S(1) 2.280-
(1), Pd-S(2) 2.408(1), Si-C(1) 1.843(2), Pd-Si 3.020(1),
N(2)-C(20) 1.324(3), S(1)-C(20) 1.724(3), S(2)-C(20) 1.712-
(3), C(1)-Pd-N(1) 87.6(1), C(1)-Pd-S(1) 92.9(1), N(1)-
Pd-S(1) 174.21(5), C(1)-Pd-S(2) 168.05(7), N(1)-Pd-S(2)
104.35(6), S(1)-Pd-S(2) 75.12(3), C(1)-Pd-Si 36.82(7),
N(1)-Pd-Si 62.52(5), S(1)-Pd-Si 115.07(2), S(2)-Pd-Si
149.84(3), C(1)-Si-C(14) 105.2(1), C(14)-N(1)-Pd 102.7-
(1), C(20)-S(1)-Pd 88.0(1), C(20)-S(2)-Pd 84.2(1), N(1)-
C(14)-Si 109.2(2).
Exp er im en ta l Section
Gen er a l Com m en ts. Infrared spectra [KBr pellets, 4000-
400 cm-1]: Perkin-Elmer 1720X. 1H NMR [solvent CDCl3;
internal standard CHCl3 (δ ) 7.20)]: Bruker AC-300 or ARX-
300 (300.13 MHz). 31P{1H} NMR [external standard 85%
aqueous H3PO4 (δ ) 0)]: Bruker AC-300 or ARX-300 (121.49
MHz). 13C NMR [solvent and internal standard CDCl3 (δ )
77.00)]: Bruker ARX-300 (75.78 MHz). Assignment of the 13C
NMR data was supported by DEPT experiments and the
relative intensities of the resonance signals. 29Si{1H} and 2D
29Si-1H HMBC NMR [solvent CDCl3; internal standard TMS
(δ ) 0)]: Bruker DRX-300 (59.63 MHz). Microanalyses:
Perkin-Elmer 2400B microanalyzer, Qu´ımica Inorga´nica, Fac-
ultad de Ciencias, Valladolid. Electrical conductivity [ca. 5 ×
10-4 M solutions; range of molar conductivity for 1:1 electro-
lytes ) 100-140 S‚cm2‚mol-1 in acetone]:30 Crison 522. All
reactions were carried out under oxygen-free and dried dini-
trogen following conventional Schlenk techniques. The solvents
were dried according to common procedures. [PdCl2(SMe2)2]
was obtained as described for the tht complex,34 TlBF4,35 and
Tl(acac)36 as reported (CAUTION: Tl(I) derivatives are toxic
and should be handled with care). The rest of the reactants
were obtained from usual commercial suppliers.
case is the second highest after the one found for 3. The
C-S and C-N bond lengths as well as the S-Pd-S or
S-C-S angles found in the dithiocarbamate ligand are
similar to those reported for other dithiocarbamatopal-
ladium complexes.33
Con clu sion s a n d Ou tlook
The palladacycle formed by the [diphenyl(piperidi-
nomethyl)silylmethyl] ligand and different palladium
complex fragments remains intact during reactions in
which bridging chloro ligands are cleaved by neutral
ligands or substituted by anionic bidentate ligands.
However, only the complex with two 4-methylpyridine
ligands could be obtained during the attempts to obtain
cationic complexes with monodentate neutral ligands,
whereas a process involving Pd-N cleavage is detected
in solution of the complex with a neutral bidentate
ligand, such as dppe. Further studies on the reactivity
of the chloro-bridged dimer are currently in progress.
X-ray structural analyses of compounds representa-
tive of the main structural types show the strong trans
influence of the [(piperidinomethyl)silylmethyl] frag-
ment, regardless of neutral or cationic complexes. The
palladacycle adopts an envelope conformation in all the
structures, and the presence of palladium and silicon
in a five-membered palladacycle makes the Pd-Si
Syn th esis of P h 2Si(CH2Li)(CH2NC5H10) (2). In a Schlenk
flask, a solution of 550 mg (1.86 mmol) of Ph2SiMe(CH2NC5H10
)
(1) in n-pentane (4 mL) was cooled to -90 °C, and 1.09 mL of
t-BuLi (in n-pentane, c ) 1.7 mol‚L-1) (1.86 mmol) was added.
After slowly warming the yellow mixture to room temperature,
2 precipitated as an off-white solid. The mixture was stirred
for one additional hour before the solvent was removed in
vacuo. The solid was immediately used for the synthesis of
compound 3. To isolate 2 as yellow single crystals, the solution
has to be warmed from -90 to -30 °C and kept for 6 h at this
temperature, yielding 2 (504 mg, 1.67 mmol, 90%) (after
washing with n-pentane and drying in vacuo).
Syn th esis of [P d {CH2SiP h 2(CH2NC5H10)-K2C,N}(µ-Cl)]2
(3). Solid trans-[PdCl2(SMe2)2] (2.63 g, 8.77 mmol) was added
to a freshly prepared solution of 2 (2.64 g, 8.77 mmol) in thf
(88 mL), cooled to -78 °C. The mixture was stirred for 5 h
and was allowed to warm to room temperature. Two drops of
water were added to hydrolyze a potential excess of organo-
(33) (a) Long, D.-L.; Wong, W.-T.; Shi, S.; Xin, X.-Q.; Huang, J .-S.
J . Chem. Soc., Dalton Trans. 1997, 4361. (b) Reger, D. L.; Collins, J .
E. J . Organomet. Chem. 1995, 491, 159. (c) Hamamura, H.; Kita, M.;
Nonoyama, M.; Fujita, J . J . Organomet. Chem. 1993, 463, 169. (d)
Reger, D. L.; Garza, D. G.; Lebioda, L. Organometallics 1992, 11, 4285.
(e) Reger, D. L.; Garza, D. G.; Lebioda, L. Organometallics 1991, 10,
902.
(34) Uso´n, R.; Fornie´s, J .; Mart´ınez, F.; Toma´s, M. J . Chem. Soc.,
Dalton Trans. 1980, 888.
(35) Arna´iz, F. J . J . Chem. Educ. 1997, 74, 1332.
(36) Taylor, E. C.; Hawks, G. H.; McKillop, A. J . Am. Chem. Soc.
1968, 24, 2421.

3236 Organometallics, Vol. 23, No. 13, 2004
Schildbach et al.
lithium reagent. The volatile components were removed in
vacuo, and the residue was successively washed with n-hexane
(3 × 20 mL) and acetone (3 × 10 mL) and then extracted with
CH2Cl2 (50 mL) and filtered on dry Celite. n-Hexane (ca. 30
mL) was added to the filtrate, which was concentrated and
cooled to -20 °C to give a yellow microcrystalline solid, which
was washed with n-hexane (3 × 10 mL) and dried in vacuo.
The n-hexane and acetone extracts were subjected to the same
treatment after removing the volatile components in vacuo and
Syn t h esis of [P d {CH 2SiP h 2(CH2NC5H 10)-K2C,N}Cl-
(CNtBu )] (6). CNtBu (34.9 mg, 420 µmol) was added to a
solution of 3 (175 mg, 200 µmol) in CH2Cl2 (30 mL), and the
mixture was stirred for 5 min. The solution was filtered on
alumina IV, the volatile components were removed in vacuo,
and the residue was washed with n-hexane (3 × 5 mL) and
vacuum-dried to give 116 mg (56%) of 6 as a colorless solid,
which was recrystallized from CH2Cl2/n-hexane at -20 °C. 1H
NMR: δ 7.56 (m, C6H5, 4H), 7.31 (m, C6H5, 6H), 3.70 (m,
NC5H10, 2H), 2.82 (s, SiCH2N, 2H), 2.42 (m, NC5H10, 2H), 1.7-
1.3 (br m, NC5H10, 6H), 1.45 (s, CCH3, 9H), 0.99 (s, PdCH2Si,
2H). 13C{1H} NMR: δ CNtBu not observed, 136.1 (s, Si-i-C6H5),
134.5 (s, Si-o-C6H5), 129.3 (s, Si-p-C6H5), 127.8 (s, Si-m-C6H5),
59.3 (s, NCH2CH2CH2), 58.0 (s, CNC(CH3)3), 49.9 (s, NCH2-
Si), 30.1 (s, CNC(CH3)3), 23.1 (s, NCH2CH2CH2), 20.7 (s,
NCH2CH2CH2), -1.0 (s, PdCH2Si). 29Si{1H} NMR: δ 1.47.
IR: 3066 w, 2932 m, 2204 s, 1455 w, 1427 m, 1401 w, 1385 w,
1373 w, 1196 m, 1110 m, 866 w, 736 m, 701 m, 544 w, 503 w,
491 w. Anal. Calcd for C24H33ClN2PdSi: C, 55.49; H, 6.40; N,
5.39. Found: C, 55.28; H, 6.23; N, 5.48.
1
extracting with CH2Cl2. Yield: 2.74 g (72%) of 3. H NMR: δ
7.67 (m, C6H5, 4H, cisoid and transoid), 7.34 (m, C6H5, 6H,
cisoid and transoid), 3.37 (m, NC5H10, 2H, cisoid and transoid),
3.00 (s, SiCH2N, 2H, transoid), 2.95 (s, SiCH2N, 2H, cisoid),
2.47 (m, NC5H10, 2H, cisoid), 2.36 (m, NC5H10, 2H, transoid),
1.8-1.2 (br m, NC5H10, 6H, cisoid and transoid), 1.49 (s,
PdCH2Si, 2H, transoid), 1.41 (s, PdCH2Si, 2H, cisoid). Ratio
transoid/cisoid ) 65:35. 13C{1H} NMR: δ 136.1 (s, Si-i-C6H5),
134.7 (s, Si-o-C6H5), 129.3 (s, Si-p-C6H5), 127.9 (s, Si-m-C6H5),
62.4 (s, NCH2CH2CH2, transoid), 61.7 (s, NCH2CH2CH2,
cisoid), 55.2 (s, NCH2Si, transoid), 53.9 (s, NCH2Si, cisoid),
23.1 (s, NCH2CH2CH2), 22.5 (s, NCH2CH2CH2, transoid), 21.6
(s, NCH2CH2CH2, cisoid), 5.2 (s, PdCH2Si, transoid), 2.0 (s,
NCH2CH2CH2, cisoid). 29Si{1H} NMR: δ 0.65. IR: 3045 w,
3004 w, 2941 m, 2861 w, 1441 w, 1427 s, 1378 w, 1111 s, 1037
w, 864 w, 836 w, 792 w, 766 s, 752 s, 736 s, 722 s, 702 s, 518
w, 515 w, 488 m, 462 w, 428 w. Anal. Calcd for C38H48Cl2N2-
Pd2Si2: C, 52.30; H, 5.54; N, 3.21. Found: C, 52.44; H, 5.34;
N, 3.27.
Syn t h esis of [P d {CH2SiP h 2(CH2NC5H10)-K2C,N}Cl(4-
MeP y)] (7). 4-MePy (75.0 mg, 800 µmol) was added to a
solution of 3 (349 mg, 400 µmol) in CH2Cl2 (20 mL), and the
mixture was stirred for 1 h. n-Hexane (20 mL) was added to
the solution, which was concentrated and cooled to -20 °C.
Yellow crystals were obtained and isolated, washed with
n-hexane (3 × 3 mL), and dried in vacuo to give 263 mg (62%)
1
of 7. H NMR: δ 8.50 (d, J ) 5.5 Hz, H2 of MePy, 2H), 7.61
Syn th esis of [P d{CH2SiP h 2(CH2NC5H10)-K2C,N}Cl(P P h 3)]
(4). Solid PPh3 (105 mg, 400 µmol) was added to a solution of
3 (175 mg, 200 µmol) in CH2Cl2 (15 mL), and the solution was
stirred for 1 h. n-Hexane (10 mL) was added to this solution,
which was then concentrated and cooled to -20 °C. Colorless
crystals were obtained and isolated, washed with n-hexane (3
× 3 mL), and dried in vacuo to give 246 mg (88%) of 4. 31P-
(m, C6H5, 4H), 7.31 (m, C6H5, 6H), 7.00 (d, J ) 5.5 Hz, H3 of
MePy, 2H), 3.85 (m, NC5H10, 2H), 2.95 (s, SiCH2N, 2H), 2.55
(m, NC5H10, 2H), 2.28 (s, NC5H4CH3, 3H), 1.8-1.3 (br m,
NC5H10, 6H), 1.03 (s, PdCH2Si, 2H). 13C{1H} NMR: δ 152.4
(s, o-NC5H4CH3), 148.9 (s, p-NC5H4CH3), 136.4 (s, Si-i-C6H5),
134.4 (s, Si-o-C6H5), 129.1 (s, Si-p-C6H5), 127.7 (s, Si-m-C6H5),
125.5 (s, m-NC5H4CH3), 61.4 (s, NCH2CH2CH2), 52.6 (s, NCH2-
Si), 23.0 (s, NCH2CH2CH2), 21.2 (s, NCH2CH2CH2), 20.8 (s,
NC5H4CH3), 5.9 (s, PdCH2Si). 29Si{1H} NMR: δ 0.85. IR: 3064
w, 3042 w, 3007 w, 2934 m, 2856 m, 1618 m, 1503 w, 1455 m,
1427 m, 1372 w, 1258 w, 1227 w, 1213 w, 1154 w, 1110 m,
1072 w, 1029 w, 998 w, 948 w, 867 m, 806 m, 782 m, 735 s,
1
{1H} NMR: δ 37.8 (s). H NMR: δ 7.6 (m, C6H5, 6H), 7.4 (m,
C6H5, 4H), 7.2 (m, C6H5, 15H), 3.93 (m, NC5H10, 2H), 2.87 (d,
4J P,H ) 1.5 Hz, SiCH2N, 2H), 2.49 (m, NC5H10, 2H), 1.7-1.4
(br m, NC5H10, 6H), 0.57 (d, 3J P,H ) 3.5 Hz, PdCH2Si, 2H). 13C-
{1H} NMR: δ 136.9 (s, Si-i-C6H5), 134.6 (d, 2J C,P ) 12 Hz, P-o-
1
702 s, 618 w, 549 s, 502 s, 465 w, 425 w. Anal. Calcd for C25H31
-
C6H5), 134.5 (s, Si-o-C6H5), 132.1 (d, J C,P ) 51 Hz, P-i-C6H5),
3
ClN2PdSi: C, 56.71; H, 5.90; N, 5.29. Found: C, 56.57; H, 5.87;
N, 5.13.
130.1 (s, P-p-C6H5), 129.1 (s, Si-p-C6H5), 127.9 (d, J C,P ) 11
Hz, P-m-C6H5), 127.7 (s, Si-m-C6H5), 59.5 (s, NCH2CH2CH2),
49.3 (s, NCH2Si), 23.5 (s, NCH2CH2CH2), 21.5 (s, NCH2CH2-
CH2), 11.4 (s, PdCH2Si). 29Si{1H} NMR: δ -0.07. IR: 3052 w,
2933 m, 2859 w, 1482 m, 1434 s, 1404 w, 1097 s, 800 w, 781
w, 737 s, 698 vs, 536 s, 513 m, 499 m, 426 w. Anal. Calcd for
Syn th esis of [P d {CH2SiP h 2(CH2NC5H10)-K2C,N}Cl(th t)]
(8). Tht (1.06 g, 12.0 mmol) was added to a mixture of 3 (262
mg, 300 µmol) in acetone (15 mL). The mixture was stirred
for 1 h until a clear solution was obtained. n-Hexane (10 mL)
was added to this solution, which was then concentrated and
cooled to -20 °C. Yellow crystals were obtained and isolated,
washed with n-hexane (3 × 3 mL), and dried in vacuo to give
195 mg (62%) of 8. 1H NMR: δ 7.60 (m, C6H5, 4H), 7.32 (m,
C6H5, 6H), 3.84 (m, NC5H10, 2H), 3.13 (br, H2 of tht, 4H), 2.90
(s, SiCH2N, 2H), 2.51 (m, NC5H10, 2H), 1.99 (m, H3 of tht, 4H),
1.8-1.4 (br m, NC5H10, 6H), 0.92 (s, PdCH2Si, 2H). 13C{1H}
NMR: δ 136.0 (s, Si-i-C6H5), 134.5 (s, Si-o-C6H5), 129.2 (s, Si-
p-C6H5), 127.8 (s, Si-m-C6H5), 60.8 (s, NCH2CH2CH2), 51.2 (s,
NCH2Si), 37.4 (s, SCH2CH2), 29.7 (s, SCH2CH2), 23.1 (s, NCH2-
CH2CH2), 21.2 (s, NCH2CH2CH2), 6.7 (s, PdCH2Si). 29Si{1H}
NMR: δ 0.44. IR: 3062 w, 2929 m, 2858 w, 1427 w, 1407 w,
1386 m, 1354 m, 1302 w, 1157 w, 1104 m, 1030 w, 840 w, 803
m, 784 m, 749 m, 738 s, 698 s, 544 w, 504 w, 491 w. Anal.
Calcd for C23H32ClNPdSSi: C, 52.67; H, 6.15; N, 2.67. Found:
C, 52.73; H, 5.98; N, 2.43.
C
37H39ClNPPdSi: C, 63.61; H, 5.63; N, 2.00. Found: C, 63.43;
H, 5.48; N, 2.27.
Syn t h esis of [P d {CH 2SiP h 2(CH2NC5H 10)-K2C,N}Cl-
(P Me3)] (5). A solution of PMe3 (CAUTION: PMe3 is poten-
tially dangerous; it should be handled only in a well-ventilated
hood) in thf (c ) 1.0 mol‚L-1, 200 µL, 200 µmol) was added to
a solution of 3 (87.3 mg, 100 µmol) in CH2Cl2 (15 mL), and
the mixture was stirred for 1 h. n-Hexane (10 mL) was added
to this solution, which was concentrated and cooled to -20
°C. Colorless crystals were obtained, isolated, washed with
n-hexane (3 × 3 mL), and dried in vacuo to give 44.1 mg (43%)
of 5. 31P{1H} NMR: δ -0.7 (s). 1H NMR: δ 7.57 (m, C6H5, 4H),
4
7.30 (m, C6H5, 6H), 3.65 (m, NC5H10, 2H), 2.79 (d, J P,H ) 1
Hz, SiCH2N, 2H), 2.35 (m, NC5H10, 2H), 1.6-1.2 (br m, NC5H10
,
2
3
6H), 1.43 (d, J P,H ) 11 Hz, PCH3, 9H), 0.55 (d, J P,H ) 4 Hz,
PdCH2Si, 2H). 13C{1H} NMR: δ 137.0 (s, Si-i-C6H5), 134.5 (s,
Si-o-C6H5), 129.1 (s, Si-p-C6H5), 127.7 (s, Si-m-C6H5), 59.3 (s,
NCH2CH2CH2), 49.6 (s, NCH2Si), 23.4 (s, NCH2CH2CH2), 21.5
(s, NCH2CH2CH2), 16.6 (d, 1J C,P ) 34 Hz, PCH3), 2.8 (s, PdCH2-
Si). 29Si{1H} NMR: δ 0.14. IR: 3063 w, 2963 w, 2841 w, 2805
w, 1484 w, 1427 m, 1415 w, 1377 w, 1303 w, 1285 w, 1175 w,
1111 m, 1048 w, 961 s, 855 w, 793 w, 764 s, 748 s, 735 s, 701
s, 546 w, 496 w, 484 w. Anal. Calcd for C22H33ClNPPdSi: C,
51.57; H, 6.49; N, 2.73. Found: C, 51.33; H, 6.52; N, 2.98.
Syn th esis of [P d{CH2SiP h 2(CH2NC5H10)-K2C,N}Cl(SMe2)]
(9). SMe2 (240 mg, 4.00 mmol) was added to a suspension of
3 (175 mg, 200 µmol) in acetone (30 mL). The solution, which
was immediately formed, was stirred for 5 min. n-Hexane (30
mL) was added to this solution, which was concentrated and
cooled to -20 °C. Yellow crystals were obtained and isolated,
washed with n-hexane (3 × 3 mL), and dried in vacuo to give
108 mg (54%) of 9. 1H NMR: δ 7.57 (m, C6H5, 4H), 7.31 (m,

[(Piperidinomethyl)silylmethyl] Pd Complexes
Organometallics, Vol. 23, No. 13, 2004 3237
C6H5, 6H), 3.82 (m, NC5H10, 2H), 2.91 (s, SiCH2N, 2H), 2.50
471 w. Anal. Calcd for C45H48ClNP2PdSi: C, 64.75; H, 5.80;
(m, NC5H10, 2H), 2.35 (s, SCH3, 6H), 1.7-1.3 (br m, NC5H10
,
N, 1.68. Found: C, 64.43; H, 5.57; N, 1.52. Conductivity: ΛM
6H), 1.00 (s, PdCH2Si, 2H). 13C{1H} NMR: δ 136.0 (s, Si-i-
C6H5), 134.3 (s, Si-o-C6H5), 129.2 (s, Si-p-C6H5), 127.7 (s, Si-
m-C6H5), 60.8 (s, NCH2CH2CH2), 51.3 (s, NCH2Si), 23.0 (s,
NCH2CH2CH2), 22.8 (s, SCH3), 21.3 (s, NCH2CH2CH2), 7.0 (s,
PdCH2Si). 29Si{1H} NMR: δ 0.07. IR: 3062 w, 3012 w, 2976
m, 2922 m, 2867 m, 2845 m, 1455 m, 1427 m, 1411 w, 1355 w,
1325 w, 1300 w, 1234 w, 1156 w, 1104 m, 1029 m, 980 m, 947
w, 911 w, 867 m, 840 m, 802 w, 785 m, 738 s, 696 s, 617 w,
543 m, 503 w, 493 w. Anal. Calcd for C21H30ClNPdSSi: C,
50.60; H, 6.07; N, 2.81. Found: C, 50.62; H, 5.95; N, 2.62.
(Me2CO): 30 S‚cm2‚mol-1
.
Syn th esis of [{P d 2[CH2SiP h 2(CH2NC5H10)-K2C,N]2Cl2}-
(µ-d p p e)] (13). During 30 min, a solution of dppe (39.8 mg,
100 µmol) in toluene (10 mL) was added dropwise to a solution
of 3 (87.3 mg, 100 µmol) in toluene (15 mL). All volatile
components were removed in vacuo, and the residue was
recrystallized from CH2Cl2/n-hexane at -20 °C to give 69.9
mg (55%) of 13 as a pale yellow microcrystalline solid. 31P-
1
{1H} NMR: δ 34.6 (s). H NMR: δ 7.5 (m, C6H5, 8H), 7.2-7.0
(m, C6H5, 32H), 3.77 (m, NC5H10, 4H), 2.73 (s, SiCH2N, 4H),
2.63 (br s, PCH2, 4H), 2.43 (m, NC5H10, 4H), 1.65 (br m,
NC5H10, 4H), 1.44 (br m, NC5H10, 8H), 0.40 (br s, PdCH2Si,
4H). 13C{1H} NMR: δ 136.5 (s, Si-i-C6H5), 134.4 (s, Si-o-C6H5),
Syn t h esis of [P d {CH 2SiP h 2(CH2NC5H 10)-K2C,N}(4-
MeP y)2]BF 4 (10). A Schlenk flask was successively charged
with 3 (87.3 mg, 100 µmol), CH2Cl2 (10 mL), 4-MePy (7.40 mg,
400 µmol), and TlBF4 (58.2 mg, 200 µmol), and the mixture
was stirred for 16 h. The mixture was then filtered and
concentrated, and Et2O was added to the filtrate. After cooling
to -20 °C, a white microcrystalline solid was obtained. It was
isolated, washed with n-hexane (3 × 3 mL), and dried in vacuo
2
1
133.3 (d, J C,P ) 3 Hz, P-o-C6H5), 130.7 (d, J C,P ) 25 Hz, P-i-
3
C6H5), 130.1 (s, P-p-C6H5), 128.9 (s, Si-p-C6H5), 128.3 (d, J C,P
) 3 Hz, P-m-C6H5), 127.5 (s, Si-m-C6H5), 58.9 (s, NCH2CH2-
CH2), 48.3 (s, NCH2Si), 24.9 (m, PCH2), 23.4 (s, NCH2CH2CH2),
20.8 (s, NCH2CH2CH2), 8.1 (s, PdCH2Si). 29Si{1H} NMR: δ
1.63. IR: 3064 w, 2927 m, 2856 w, 1587 w, 1484 m, 1467 w,
1455 m, 1435 m, 1380 w, 1356 w, 1314 w, 1261 w, 1178 m,
1156 m, 1104 s, 1030 w, 999 w, 976 w, 865 w, 801 m, 766 s,
731 s, 698 s, 613 w, 520 m, 488 m, 471 w, 436 w, 410 w. Anal.
Calcd for C64H72Cl2N2P2Pd2Si2: C, 60.48; H, 5.71; N, 2.20.
Found: C, 60.14; H, 5.57; N, 2.22.
1
to give 93.0 mg (69%) of 10. H NMR: δ 8.68 (d, J ) 6 Hz, H2
of MePy, 2H), 8.30 (d, J ) 6 Hz, H2 of MePy, 2H), 7.61 (m,
C6H5, 4H), 7.37 (m, C6H5, 6H), 7.23 (d, J ) 6 Hz, H3 of MePy,
2H), 7.03 (d, J ) 6 Hz, H3 of MePy, 2H), 3.16 (s, SiCH2N, 2H),
3.03 (m, NC5H10, 2H), 2.65 (m, NC5H10, 2H), 2.27 (s, NC5H4CH3,
3H), 2.21 (s, NC5H4CH3, 3H), 1.61 (m, NC5H10, 2H), 1.33 (m,
NC5H10, 4H), 0.99 (s, PdCH2Si, 2H). 13C{1H} NMR: δ 151.2
(s, o-NC5H4CH3), 150.5 (s, p-NC5H4CH3), 150.4 (s, p-NC5H4-
CH3), 149.5 (s, o-NC5H4CH3), 136.0 (s, Si-i-C6H5), 134.4 (s, Si-
o-C6H5), 129.5 (s, Si-p-C6H5), 128.1 (s, Si-m-C6H5), 127.2 (s,
m-NC5H4CH3), 126.9 (s, m-NC5H4CH3), 61.9 (s, NCH2CH2CH2),
54.2 (s, NCH2Si), 22.7 (s, NCH2CH2CH2), 21.1 (s, NCH2CH2-
CH2), 21.0 (s, NC5H4CH3), 20.8 (s, NC5H4CH3), 3.9 (s, PdCH2-
Si). 29Si{1H} NMR: δ -0.29. IR: 3065w, 2945 m, 2871 w, 1617
m, 1504 w, 1428 m, 1385 w, 1211 w, 1110 s, 1068 s br, 869 w,
Syn th esis of [P d {CH2SiP h 2(CH2NC5H10)-K2C,N}(d p p e)]-
BF 4 (14). A Schlenk flask was successively charged with 11
(56.0 mg, 67.1 µmol), thf (10 mL), and TlBF4 (19.5 mg, 67.0
µmol), and the mixture was stirred for 9 h. The mixture was
then filtered, and all volatile components were removed in
vacuo. The residue was washed with Et2O (3 × 3 mL) and
recrystallized from thf/n-hexane at -20 °C to give 26.7 mg
(45%) of 14 as a colorless microcrystalline solid. 31P{1H}
3
3
NMR: δ 58.1 (d, J P,P ) 19 Hz), 43.7 (d, J P,P ) 19 Hz). 1H
NMR: δ 7.57 (m, C6H5, 1H), 7.5-7.1 (m, C6H5, 29H), 3.00 (m,
NC5H10, 2H), 2.91 (s, SiCH2N, 2H), 2.82 (m, NC5H10, 2H), 2.27
(m, PCH2, 4H), 1.65 (m, NC5H10, 2H), 1.33 (m, NC5H10, 1H),
818 m, 763 m, 738 m, 704 m, 503 w. Anal. Calcd for C31H38
BF4N3PdSi: C, 55.25; H, 5.68; N, 6.23. Found: C, 55.17; H,
5.42; N, 6.10. Conductivity: ΛM (Me2CO): 100 S‚cm2‚mol-1
-
.
Syn th esis of [P d {CH2SiP h 2(CH2NC5H10)-K2C,N}(d p p e)]-
Cl (11). Dppe (79.7 mg, 200 µmol) was added to a solution of
3 (87.3 mg, 100 µmol) in CH2Cl2 (10 mL), and the solution was
stirred for 5 min. All volatile components were removed in
vacuo, and the residue was washed with Et2O (3 × 3 mL) to
give 127 mg (76%) of 11 as a colorless solid, which was
recrystallized from thf/n-hexane at -20 °C. 31P{1H} NMR: δ
58.4 (d, 3J P,P ) 20 Hz), 42.7 (br d, 3J P,P ) 20 Hz). 31P{1H} NMR
0.89 (m, 2 H of PdCH2Si, and 2H of NC5H10), 0.44 (m, NC5H10
,
1H). 13C{1H} NMR: δ 135.7 (s, Si-i-C6H5), 134.4 (s, Si-o-C6H5),
133.5 (d, 2J C,P ) 13 Hz, P-o-C6H5), 133.3 (d, 2J C,P ) 12 Hz, P-o-
3
C6H5), 132.3 (s, P-p-C6H5), 132.1 (s, P-p-C6H5), 129.8 (d, J C,P
3
) 10 Hz, P-m-C6H5), 129.7 (s, Si-p-C6H5), 129.5 (d, J C,P ) 11
1
Hz, P-m-C6H5), 128.6 (d, J C,P ) 34 Hz, P-i-C6H5), 128.2 (d,
3J C,P ) 36 Hz, P-i-C6H5), 128.0 (s, Si-m-C6H5), 61.4 (s, NCH2-
3
CH2CH2), 47.1 (s, NCH2Si), 29.0 (dd, 1J C,P ) 36 and J C,P ) 18
3
Hz, PCH2), 26.7 (dd, 1J C,P ) 31 and J C,P ) 11 Hz, PCH2), 22.8
3
3
(-60 °C): δ 59.3 (d, J P,P ) 19 Hz), 44.3 (d, J P,P ) 20 Hz).
31P{1H} NMR [(CD3)2CO, after dissolving the solid at -60 °C]:
δ 64.5 (d, 3J P,P ) 19 Hz), 46.2 (d, 3J P,P ) 19 Hz). 31P{1H} NMR
1
(s, NCH2CH2CH2), 19.7 (s, NCH2CH2CH2), 17.0 (d, J C,P ) 71
Hz, PdCH2Si). 29Si{1H} NMR: δ 1.64. IR: 3063 w, 2947 w,
2857 w, 1586 w, 1484 m, 1437 s, 1407 m, 1240 w, 1187 w,
1050 s br, 997 m, 947 w, 884 w, 868 w, 820 m, 799 w, 789 w,
777 m, 753 m, 731 m, 702 s, 676 m, 654 w, 636 w, 615 w, 534
s, 484 s, 430 w. Anal. Calcd for C45H48BF4NP2PdSi: C, 61.00;
H, 5.46; N, 1.58. Found: C, 60.86; H, 5.62; N, 1.76. Conductiv-
3
[(CD3)2CO, excess of PPNCl]: δ 60.5 (d, J P,P ) 25 Hz), 36.5
(d, 3J P,P ) 25 Hz). 31P{1H} NMR [(CD3)2CO]: δ 60.3 (d, 3J P,P
)
3
1
23 Hz), 39.0 (br d, J P,P ) 23 Hz. H NMR: δ 7.4 (br m, C6H5,
20H), 7.33 (m, C6H5, 2H), 7.21 (m, C6H5, 8H), 2.92 (s, SiCH2N,
2H), 2.82 (br, NC5H10, 4H), 2.33 (m, PCH2, 4H), 1.29 (m,
ity: ΛM (Me2CO): 105 S‚cm2‚mol-1
.
1
NC5H10, 4H), 0.91 (m, 2H of PdCH2Si, and 2H of NC5H10). H
NMR (-60 °C): δ 7.77 (m, C6H5, 1H), 7.5-7.1 (m, C6H5, 29H),
Syn t h esis of [P d {CH 2SiP h 2(CH2NC5H 10)-K2C,N}(S2-
CNEt2)] (15). NaS2CNEt2 (40.3 mg, 250 µmol) was added to
a solution of 3 (96.0 mg, 110 µmol) in CH2Cl2 (15 mL), and
the mixture was stirred for 16 h. The mixture was then
filtered, and all volatile components were removed in vacuo.
The residue was recrystallized from CH2Cl2/n-hexane at -20
2.96 (m, NC5H10, 2H), 2.83 (s, SiCH2N, 2H), 2.64 (m, NC5H10
,
2H), 2.18 (m, PCH2, 4H), 1.64 (m, NC5H10, 2H), 1.32 (m,
NC5H10, 1H), 0.82 (m, PdCH2Si, 2H, and NC5H10, 2H), 0.14
(m, NC5H10, 1H). 13C{1H} NMR: δ 135.6 (s, Si-i-C6H5), 134.2
(s, Si-o-C6H5), 133.2 (d, 2J C,P ) 11 Hz, P-o-C6H5), 133.1 (d, 2J C,P
) 10 Hz, P-o-C6H5), 132.1 (s, P-p-C6H5), 131.9 (s, P-p-C6H5),
1
°C to give 96.7 mg (80%) of 15 as yellow crystals. H NMR: δ
3
129.6 (d, J C,P ) 10 Hz, P-m-C6H5), 129.4 (s, Si-p-C6H5), 129.3
7.66 (m, C6H5, 4H), 7.28 (m, C6H5, 6H), 3.71 (q, J ) 7 Hz,
NCH2, 2H), 3.69 (q, J ) 7 Hz, NCH2, 2H), 3.17 (m, NC5H10,
(d, 3J C,P ) 11 Hz, P-m-C6H5), 128.5 (d, 1J C,P ) 21 Hz, P-i-C6H5),
127.9 (m, P-i-C6H5), 127.7 (s, Si-m-C6H5), 61.1 (s, NCH2CH2-
2H), 2.99 (s, SiCH2N, 2H), 2.13 (m, NC5H10, 2H), 1.94 (m,
NC5H10, 2H), 1.58 (m, NC5H10, 2H), 1.22 (m, 2H of NC5H10
1
2
CH2), 47.3 (s, NCH2Si), 28.9 (dd, J C,P ) 17 and J C,P ) 8 Hz,
,
1
2
PCH2), 26.2 (dd, J C,P ) 16 and J C,P ) 4 Hz, PCH2), 22.6 (s,
NCH2CH2CH2), 19.8 (s, NCH2CH2CH2), 16.3 (d, 1J C,P ) 72 Hz,
PdCH2Si). 29Si{1H} NMR: δ 0.88. IR: 3051 w, 2931 m, 1484
m, 1435 s, 1408 m, 1297 w, 1264 w, 1186 w, 1103 s, 1062 m,
999 w, 915 w, 828 m, 776 m, 742 s, 702 s, 659 w, 531 s, 487 m,
and 6H of CH3), 0.65 (s, PdCH2Si, 2H). 13C{1H} NMR: δ 208.5
(s, S2CN), 138.6 (s, Si-i-C6H5), 134.7 (s, Si-o-C6H5), 128.7 (s,
Si-p-C6H5), 127.6 (s, Si-m-C6H5), 63.1 (s, NCH2CH2CH2), 57.9
(s, NCH2Si), 45.0 (s, NCH2CH3), 43.4 (s, NCH2CH3), 24.2 (s,
NCH2CH2CH2), 23.0 (s, NCH2CH2CH2), 12.3 (br s, NCH2CH3),

3238 Organometallics, Vol. 23, No. 13, 2004
Schildbach et al.
Ta ble 1. Cr ysta llogr a p h ic Da ta a n d Str u ctu r e Refin em en t Deta ils for Com p ou n d s 3, 4, 8, 9, 10, a n d 15
10 15
0.40 × 0.40 × 0.30 0.30 × 0.20 × 0.10 0.30 × 0.20 × 0.20 0.30 × 0.20 × 0.20 0.30 × 0.20 × 0.20 0.30 × 0.20 × 0.20
3
4
8
9
cryst size
[mm]
empirical
formula
fw
C
38H48Cl2N2Pd2Si2
C
37H39ClNPPdSi
C23H32ClNPdSSi
C21H30ClNPdSSi
C31H38BF4N3PdSi C24H34N2PdS2Si
872.72
698.64
524.53
498.49
673.96
549.18
cryst syst
space group P21/n (no. 14)
a [Å]
b [Å]
monoclinic
orthorhombic
P212121 (no. 19)
12.165(2)
15.834(3)
17.202(3)
90
orthorhombic
P212121 (no. 19)
10.205(2)
10.581(2)
22.121(4)
90
orthorhombic
P212121 (no. 19)
9.3408(8)
10.4890(9)
22.348(2)
90
monoclinic
P21/n (no. 14)
10.289(2)
10.788(2)
27.852(6)
90
90.34(3)
90
3095.5(11)
monoclinic
P21/n (no. 14)
9.335(2)
12.163(2)
22.548(5)
90
99.39(3)
90
2525.8(9)
9.191(2)
19.474(4)
10.737(2)
90
104.13(3)
90
c [Å]
R [deg]
â [deg]
γ [deg]
cell volume
[Å3]
90
90
90
90
90
90
1863.6(7)
3313.5(10)
2388.6(8)
2189.5(3)
Z
4
4
4
4
4
4
Fcalc
1.555
1.400
1.459
1.512
1.448
1.444
[g cm-3
]
µ [mm-1
no. of reflns 19 632
measd
]
1.202
0.752
21 490
1.036
17 687
1.125
42 407
0.689
26 680
17 069
scan range
[deg]
4.44 e 2θ e 54.00 4.84 e 2θ e 54.00 5.32 e 2θ e 50.00 4.28 e 2θ e 50.00 4.22 e 2θ e 52.00 5.54 e 2θ e 54.00
no. of
3964
7230
4196
3858
5753
5275
unique
reflns
no. of reflns 3545
obsd
5608
4088
3837
4337
4716
[I g 2σ(I)]
Flack param
-0.02(3)
0.0435, 0.0917
-0.032(19)
0.0197, 0.0518
-0.004(15)
0.0151, 0.0401
R1, wR2
0.0348, 0.0999
0.0556, 0.1606
0.0337, 0.0952
2
-0.4 (s, PdCH2Si). 29Si{1H} NMR: δ 0.27. IR: 3061 w, 2968
w, 2928 m, 2853 w, 2809 w, 1504 s, 1461 w, 1426 m, 1379 m,
1358 m, 1303 m, 1275 m, 1212 m, 1149 m, 1109 m, 1075 w,
1036 w, 997 m, 917 m, 845 m, 765 s, 733 w, 713 m, 573 m,
531 w, 502 w, 456 w, 420 w. Anal. Calcd for C24H34N2PdS2Si:
C, 52.49; H, 6.24; N, 5.18. Found: C, 52.25; H, 6.08; N, 5.03.
Syn th esis of [P d {CH2SiP h 2(CH2NC5H10)-K2C,N}(a ca c)]
(16). Tl(acac) (121 mg, 400 µmol) was added to a solution of 3
(175 mg, 200 µmol) in CH2Cl2 (20 mL), and the mixture was
stirred for 8 h. The mixture was then filtered, all volatile
components were removed in vacuo, and the residue was
recrystallized from CH2Cl2/n-hexane at -20 °C to give 146 mg
(73%) of 16 as yellow crystals. 1H NMR: δ 7.66 (m, C6H5, 4H),
Refinement by full-matrix least-squares methods (based on Fo ,
SHELXL-97); anisotropic thermal parameters for all non-H
atoms in the final cycles; the H atoms were refined on a riding
model in their ideal geometric positions, except for H(1A) and
H(1B) at the metalated carbon centers, which were refined
isotropically. SHELXS-90 and SHELXL-97 computer programs
were applied.37 X-ray crystallography data (cif) for 3 (CCDC
231970), 4 (CCDC 231969), 8 (CCDC 231968), 9 (CCDC
231965), 10 (CCDC 231967), and 15 (CCDC 231966) have been
deposited with the Cambridge Crystallographic Data Center
as supplementary publications.
Ack n ow led gm en t. The authors in Valladolid thank
the DGICYT (BQU2002-03414) and the J CyL (VA052/
03) for financial support. The authors in Wu¨rzburg are
grateful to the Institut fu¨r Anorganische Chemie
Wu¨rzburg, the Deutsche Forschungsgemeinschaft (DFG),
the Sonderforschungsbereich (SFB) 347, the Graduierten-
kolleg 690, and the Fonds der Chemischen Industrie
(FCI) for financial support. All authors thank Wacker-
Chemie GmbH for the donation of chemicals. D.S.
thanks the FCI for the grant of a doctoral scholarship.
7.29 (m, C6H5, 6H), 5.19 (s, COCHCO, 1H), 3.33 (m, NC5H10
,
2H), 3.02 (s, SiCH2N, 2H), 2.17 (m, NC5H10, 2H), 1.9 (br,
NC5H10, 2H), 1.86 (s, CH3, 3H), 1.83 (s, CH3, 3H), 1.6-1.2 (br
m, NC5H10, 4H), 1.08 (s, PdCH2Si, 2H). 13C{1H} NMR: δ 187.1
(s, CO), 185.2 (s, CO), 137.7 (s, Si-i-C6H5), 134.7 (s, Si-o-C6H5),
128.9 (s, Si-p-C6H5), 127.7 (s, Si-m-C6H5), 99.2 (s, COCHCO),
61.9 (s, NCH2CH2CH2), 57.8 (s, NCH2Si), 28.3 (s, CH3CO), 27.2
(s, CH3CO), 23.2 (s, NCH2CH2CH2), 22.6 (s, NCH2CH2CH2),
-1.5 (s, PdCH2Si). 29Si{1H} NMR: δ 1.27. IR: 3065 w, 2927
w, 1591 s, 1510 s, 1402 s, 1297 w, 1260 m, 1104 m, 1020 w,
927 w, 872 m, 805 m, 780 s, 731 s, 698 s, 627 w, 605 m, 553
m, 507 m, 497 m, 435 m. Anal. Calcd for C24H31NO2PdSi: C,
57.65; H, 6.25; N, 2.80. Found: C, 57.76; H, 6.27; N, 2.98.
X-r a y Diffr a ction Stu d ies of 3, 4, 8, 9, 10, a n d 15.
Crystals were grown by slow diffusion of hexane (3, 4, 15) or
Et2O (10) into concentrated solutions of the complexes in CH2-
Cl2 at -20 °C and by slow diffusion of hexane (8, 9) into
concentrated solutions of the complexes in Me2CO at -20 °C.
Relevant crystallographic details are given in Table 1. Mea-
surements were carried out on a Stoe IPDS diffractometer (3,
4, 8, 10, 15) and a Bruker APEX-CCD diffractometer (9). The
structures were solved using direct and Fourier methods.
Su p p or tin g In for m a tion Ava ila ble: Atomic positional
parameters for the freely refined atoms, bond lengths and
interbond angles, atomic displacement parameters, and hy-
drogen atom parameters; experimental data for the complex
[PdPhCl(PMe3)2]. This material is available free of charge via
the Internet at http://pubs.acs.org.
OM040028+
(37) (a) Sheldrick, G. M. SHELXS-90, Structure Solving Program
for Crystal Structure Determination; University of Go¨ttingen (Ger-
many): Go¨ttingen, 1990. (b) Sheldrick, G. M. SHELXL-97, A Computer
Program for Refinement of Crystal Structures; University of Go¨ttingen
(Germany): Go¨ttingen, 1997.