A comparative study of the chelating ability of the -N(R)-(CH 2)n-CO-N(R)2 framework in σ-aryl palladium(II) complexes derived from 2-iodoanilines and 2-iodobenzylamines. Synthesis of new types of terdentate [C,N,O] Pd(II)

Article abstract of DOI:10.1021/om051014m

The reaction of iodo anilines 2-IC₆H₄-N(Me)-CH ₂-CO-N(R)₂ (R = Me, 1a; R = Et, 1b) with Pd ₂(dba)₃ afforded binuclear Pd(II) complexes [Pd{η-(N,C)-μ-N(Me)(C₆H₄-2)CH

Full text of DOI:10.1021/om051014m

Organometallics 2006, 25, 1995-2001
1995
A Comparative Study of the Chelating Ability of the
-N(R)-(CH2)n-CO-N(R)2 Framework in σ-Aryl Palladium(II)
Complexes Derived from 2-Iodoanilines and 2-Iodobenzylamines.
Synthesis of New Types of Terdentate [C,N,O] Pd(II) Complexes
and C,N-Bridged Binuclear Pd(II) Compounds
Daniel Sole´,*,† Sandra D´ıaz,† Xavier Solans,‡ and Merce` Font-Bardia‡
Laboratori de Qu´ımica Orga`nica, Facultat de Farma`cia, UniVersitat de Barcelona, AVenida Joan XXIII
s/n, 08028-Barcelona, and Departament de Cristal.lografia, Mineralogia i Dipo`sits Minerals, UniVersitat
de Barcelona, Mart´ı i Franque`s s/n, 08028-Barcelona, Spain
ReceiVed NoVember 24, 2005
The reaction of iodo anilines 2-IC6H4-N(Me)-CH2-CO-N(R)2 (R ) Me, 1a; R ) Et, 1b) with
Pd2(dba)3 afforded binuclear Pd(II) complexes [Pd{η-(N,C)-µ-N(Me)(C6H4-2)CH2C(O)N(R)2}I]2 (R )
Me, 2a; R ) Et, 2b), which by reaction with PPh3 and Tl(TfO) were transformed into the cationic binuclear
Pd(II) complexes [Pd{η-(N,C)-µ-N(Me)(C6H4-2)CH2C(O)N(R)2}(PPh3)]22TfO (R ) Me, 3a; R ) Et,
3b). On the contrary, the reaction of aniline 2-I-4-MeC6H3-N(Me)-CH2CH2-CO-N(Me)2 (4) with
Pd2(dba)3 and PPh3 afforded four-membered azapalladacycle [Pd{κ2C,N-4-MeC6H3{N(Me)CH2CH2C-
(O)N(Me)2}-2}I(PPh3)] (5), which on treatment with Tl(TfO) did not yield a complex with the ligand in
a C,N,O-terdentate fashion, the unstable Pd(II) complex [Pd{κ2C,N-4-MeC6H3{N(Me)CH2CH2C(O)N-
(Me)2}-2}OTf(PPh3)] (6) being obtained instead. On the other hand, 2-IC6H4-CH2-N(Bn)-CH2-CO-
N(Me)2 (7) reacted with Pd2(dba)3 to give the C,N,O-terdentate complex [Pd{κ3C,N,O-C6H4{CH2N(Bn)-
CH2C(O)N(Me)2}-2}I] (8), which by reaction with PPh3 and Tl(TfO) was transformed into the cationic
C,N,O-terdentate complex [Pd{κ3C,N,O-C6H4{CH2N(Bn)CH2C(O)N(Me)2}-2}(PPh3)]TfO (9). Similarly,
treatment of iodo benzylamines 2-IC6H4-CH2-N(R)-CH2CH2-CO-N(Me)2 (R ) Bn, 10a; R ) Me,
10b) with Pd2(dba)3 and then with PPh3 and Tl(TfO) afforded cationic C,N,O-terdentate complexes [Pd-
{κ3C,N,O-C6H4{CH2N(R)CH2CH2C(O)N(Me)2}-2}(PPh3)]TfO (R ) Bn, 12a; R ) Me, 12b). Solid-state
structures of palladium complexes 2a, 2b, 3a‚C6H6‚3THF, and 8 have been determined by X-ray analysis.
Our interest in C,N-cyclopalladated systems has been centered
mainly on the synthesis and reactivity of four-membered
Introduction
In recent years, many multidentate ligands have been
developed in order to obtain new organopalladium complexes
with potential applications in several areas such as organic
synthesis, homogeneous catalysis, and the design of new
materials with interesting properties.1 In addition to classical
palladacycles with monoanionic bidentate [C,N] ligands, interest
has also been focused on cyclometalated palladium compounds
containing terdentate [C,N,L] ligands (L ) heteroatom), in
which the formation of two fused rings imposes an even greater
restriction in the coordination sphere of the metal and has
important chemical consequences.2 Within this class of terden-
tate ligands, the [C,N,N] structural arrangement has been
extensively studied. In contrast, relatively few [C,N,O]-cyclo-
metalated ligands have been reported.3-8
(3) [C,N,O] acetylhydrazone- and semicarbazone-derived complexes: (a)
Nonoyama, M.; Sugimoto, M. Inorg. Chim. Acta 1979, 35, 131-134. (b)
Sugimoto, M.; Nonoyama, M. Inorg. Nucl. Chem. Lett. 1979, 15, 405-
408. (c) Nonoyama, M. J. Inorg. Nucl. Chem. 1980, 42, 297-299. (d)
Nonoyama, M. Inorg. Chim. Acta 1988, 145, 53-56. (e) Tollari, S.;
Palmisano, G.; Demartin, F.; Grassi, M.; Magnaghi, S.; Cenini, S. J.
Organomet. Chem. 1995, 488, 79-83. (f) Vila, J. M.; Pereira, T.; Ortigueira,
J. M.; Torres, M. L.; Castin˜eiras, A.; Lata, D.; Ferna´ndez, J. J.; Ferna´ndez,
A. J. Organomet. Chem. 1998, 556, 21-30. (g) Ferna´ndez, A.; Lo´pez-
Torres, M.; Sua´rez, A.; Ortigueira, J. M.; Pereira, T.; Ferna´ndez, J. J.; Vila,
J. M.; Adams, H. J. Organomet. Chem. 2000, 598, 1-12.
(4) [C,N,O] benzoylhydrazone-derived complexes: Das, S.; Pal, S. J.
Organomet. Chem. 2004, 689, 352-360.
(5) [C,N,O] phenylhydrazone-derived complexes: (a) Albert, J.; Gonza´-
lez, A.; Granell, J.; Moragas, R.; Puerta, C.; Valerga, P. Organometallics
1997, 16, 3775-3778. (b) Albert, J.; Gonza´lez, A.; Granell, J.; Moragas,
R.; Solans, X.; Font-Bardia, M. J. Chem. Soc., Dalton Trans. 1998, 1781-
1785.
(6) [C,N,O] imine-derived complexes: (a) Yang, H.; Khan, M. A.;
Nicholas, K. M. J. Chem. Soc., Chem. Commun. 1992, 210-212. (b) Zhao,
G.; Wang, Q.-G.; Mak, T. C. W. Organometallics 1998, 17, 3437-3441.
(c) Zhao, G.; Wang, Q.-G.; Mak, T. C. W. J. Chem. Soc., Dalton Trans.
1998, 3785-3789. (d) Zhao, G.; Wang, Q.-G.; Mak, T. C. W. J. Organomet.
Chem. 1999, 574, 311-317. (e) Cativiela, C.; Falvello, L. R.; Gine´s, J. C.;
Navarro, R.; Urriolabeitia, E. P. New J. Chem. 2001, 25, 344-352. (f)
Ferna´ndez, A.; Pereira, E.; Ferna´ndez, J. J.; Lo´pez-Torres, M.; Sua´rez, A.;
Mosteiro, R.; Vila, J. M. Polyhedron 2002, 21, 39-48. (g) Ferna´ndez, A.;
Va´zquez-Garc´ıa, D.; Ferna´ndez, J. J.; Lo´pez-Torres, M.; Sua´rez, A.; Castro-
Juiz, S.; Vila, J. M. New J. Chem. 2002, 26, 398-404.
* Corresponding author. E-mail: dsole@ub.edu.
† Laboratori de Qu´ımica Orga`nica, Facultat de Farma`cia.
‡ Departament de Cristal.lografia, Mineralogia i Dipo`sits Minerals.
(1) For recent reviews, see: (a) Dupont, J.; Pfeffer, M.; Spencer, J. Eur.
J. Inorg. Chem. 2001, 1917-1927. (b) Bedford, R. B. Chem. Commun.
2003, 1787-1796. (c) Dupont, J.; Consorti, C. S.; Spencer, J. Chem. ReV.
2005, 105, 2527-2572.
(2) Vila, J. M.; Pereira, M. T.; Sua´rez, A.; Ferna´ndez, J. J.; Ortigueira,
J. M.; Ferna´ndez, A.; Torres, M. L.; Rodr´ıguez, C. Trends Organomet.
Chem. 1999, 3, 71-98.
10.1021/om051014m CCC: $33.50 © 2006 American Chemical Society
Publication on Web 02/28/2006

1996 Organometallics, Vol. 25, No. 8, 2006
Sole´ et al.
Scheme 1
containing a four-membered [C,N] metallacycle fused with a
five-membered [N,O] chelate ring.14 The reaction of 1a with
Pd2(dba)3 (1:0.55 molar ratio) in benzene at room temperature
afforded Pd(II) complex 2a in 71% yield (Scheme 2). Under
similar treatment, 1b gave Pd(II) complex 2b in 88% yield.
Coordination of the amine nitrogen atom to palladium in both
complexes was confirmed by the low-field shift of the N-CH3
(47.4 ppm for 2a and 47.1 ppm for 2b) and N-CH2 resonances
(69.8 ppm for 2a and 69.1 ppm for 2b) in their 13C NMR
azapalladacycles derived from N,N-dialkyl-2-iodoanilines.9 In
this context, we have shown that the formation of the four-
membered [C,N] metallacycle strongly modifies the interaction
of the palladium center with potentially chelating pendant
groups, such as a distal ketone carbonyl group, resulting in
unexpected reaction pathways.9a Moreover, we have also
reported that the four-membered cyclometalated framework
cannot be fit into stable palladium NCN′-pincer complexes since
the latter undergo sequential C-H activation and aerobic
oxidation to give OCN-pincer complexes.10
Continuing our research on this chemistry, we have now
focused our attention on C,N-cyclometalated systems with
pendant auxiliary fragments, which could in principle act as
terdentate [C,N,L] ligands. With this idea in mind we decided
to undertake a comparative study of the chemical behavior of
the four- and five-membered [C,N] metallacycles when fit in
potentially terdentate [C,N,O] ligands in which the O-donor is
the carbonyl of an amido group (Scheme 1). It should be noted
that although the coordination ability of the carbonyl of the
acetamido group11 and its potential to direct the orthopalladation
reaction were recognized a long time ago,12 the use of the amido
framework13 in terdentate [C,N,O] ligands has scarcely been
explored and is in fact limited to a few acylhydrazones.3a-e,4
Herein we report the results obtained in the reactions of
substrates of the types 2-IC6H4-N(R)-(CH2)n-CO-N(R)2 and
2-IC6H4-CH2-N(R)-(CH2)n-CO-N(R)2 (n ) 1, 2) with Pd-
(0) complexes. Different behavior was observed for each
structural type. Thus, we were unable to obtain a terdentate
[C,N,O] palladium complex from 2-iodoanilines; instead, the
corresponding four-membered azapalladacycle (when n ) 2)
or binuclear palladium complexes (when n ) 1) were isolated.
On the contrary, the reaction of 2-iodobenzylamines with Pd-
(0) did afford the corresponding terdentate [C,N,O] palladium
complexes when either n ) 1 or n ) 2. The X-ray crystal
structures of four of the new Pd(II) complexes are also reported.
1
spectra. The H NMR spectra showed a singlet resonance at
3.43 ppm assigned to the N-CH3 protons, shifted to a higher
frequency in accordance with coordination of the palladium atom
to the amine nitrogen. On the other hand, the lower frequency
shift3,4 of the ν(CdO) band (1608 cm-1 for 2a and 1594 cm-1
for 2b) in the IR spectra and the low-field shift of the CdO
resonance (176.6 ppm for 2a and 175.7 ppm for 2b) in the 13
C
NMR spectra were in accordance with coordination of the amide
oxygen to the metal center. All these data were in principle
compatible with a terdentate Pd(II) complex containing a four-
membered [C,N] metallacycle fused with a five-membered
[N,O] chelate ring. However, the X-ray diffraction analysis of
2a and 2b (vide infra) revealed the real structure of these
compounds, which are binuclear palladium species bridged by
two -C6H4-N(Me)-CH2-CO-NR2 ligands, instead of the
expected mononuclear complexes with the ligand coordinating
one palladium atom in a [C,N,O] terdentate fashion.
The reaction of complexes 2a,b with PPh3 and Tl(TfO)
resulted in the removal of the iodine ligand and coordination
by PPh3 to give cationic binuclear palladium complexes 3a,b
in good yields. On the other hand, the reaction of 1a with Pd-
(PPh3)4 (1:1 molar ratio) afforded the corresponding trans-bis-
(triphenylphosphane)palladium(II) complex.9b The attempts to
purify this complex by either chromatography or crystallization
resulted in the formation of an inseparable mixture of two
monophosphine complexes of unknown structure. The mixture
was converted to the cationic binuclear palladium complex 3a
by treatment with Tl(TfO) (47% overall yield from 1a).
Iodoaniline 4, containing two methylene groups between the
aniline N and the carbonyl group, behaved differently from 1a,b.
Thus, while the reaction of 4 with Pd2(dba)3 (1:0.55 molar ratio)
in benzene at room temperature afforded an untreatable mixture
that was not further investigated, when 4 was reacted with both
Pd2(dba)3 and PPh3 (1:0.55:1.1 molar ratio), four-membered
azapalladacycle 5 was obtained in 97% yield (Scheme 3).
Palladium complex 5 is a robust compound that can be purified
by flash chromatography without decomposition and was
characterized by elemental analysis, IR spectrum, and 1H, 13C,
and 31P NMR spectra. The structure of 5 was assigned by
comparing its spectroscopic data with those of related azapal-
ladacycles previously reported by us.9 For 5 the position of the
CdO band in the infrared spectrum is essentially identical with
that of the starting material 4, indicating no CdO coordination.
It is noteworthy that the terdentate [C,N,O] palladium complex
containing a four-membered metallacycle fused with a six-
membered chelate ring could not be obtained, not even when 5
was treated with Tl(TfO) to remove the iodo ligand and facilitate
the coordination of the carbonyl group, the resulting product
instead being palladacycle 6. Unfortunately, palladium complex
6 is unstable in solution, so it was impossible to obtain
analytically pure species and crystals suitable for X-ray studies.
Results and Discussion
The studies were begun with iodoanilines 1a,b, from which
we expected to obtain terdentate [C,N,O] palladium complexes
(7) [C,N,O] 8-hydroxyquinoline-derived complexes: Yoneda, A.; Hakushi,
T.; Newkome, G. R.; Froncsek, F. R. Organometallics 1994, 13, 4912-
4918, and references therein.
(8) [C,N,O] diarylazo complexes: Steiner, E.; L’Eplattenier, F. A. HelV.
Chim. Acta 1978, 61, 2264-2268.
(9) (a) Sole´, D.; Vallverdu´, L.; Solans, X.; Font-Bardia, M.; Bonjoch, J.
J. Am. Chem. Soc. 2003, 125, 1587-1594. (b) Sole´, D.; Vallverdu´, L.;
Solans, X.; Font-Bardia, M.; Bonjoch, J. Organometallics 2004, 23, 1438-
1447.
(10) Sole´, D.; Vallverdu´, L.; Solans, X.; Font-Bardia, M. Chem. Commun.
2005, 2738-2740.
(11) For an example of the acetamido group in which the N competes
with the O coordination for the Pd atom depending on the size of the
cyclometalated ring, see: Dupont, J.; Pfeffer, M.; Daran, J. C.; Gouteron,
J. J. Chem. Soc., Dalton Trans. 1988, 2421-2429.
(12) Heck, R. F. Palladium Reagents in Organic Synthesis; Academic
Press: New York, 1985.
(13) For the preparation of Pd(II) complexes with coordination by one
of the carbonyl groups of the phthaloyl moiety, see: Enzmann, A.; Eckert,
M.; Ponikwar, W.; Polborn, K.; Schneiderbauer, S.; Beller, M.; Beck, W.
Eur. J. Inorg. Chem. 2004, 1330-1340.
(14) The intermediacy of a related palladium(II) complex with a
coordinated ketone carbonyl oxygen has been proposed to explain the
“anomalous” behavior of some (2-haloanilino) alkanones in their Pd(0)-
catalyzed reactions.9a

C,N,O-Terdentate and Binuclear Pd(II) Complexes
Organometallics, Vol. 25, No. 8, 2006 1997
Scheme 2
Scheme 3
Scheme 5
Scheme 4
13C NMR spectrum were in agreement with Pd-O and Pd-N
coordination in complex 8. The [C,N,O] terdentate chelation
was confirmed by X-ray crystal structure resolution of 8 (vide
infra).
Complex 8 reacted with PPh3 and Tl(TfO) to give the cationic
complex 9 resulting from the substitution of the iodo ligand by
PPh3.
However, the structure of 6 could be unambiguously assigned
from its spectroscopic data.
We can conclude that the four-membered [C,N] palladacycle
cannot be introduced into terdentate [C,N,O] palladium com-
plexes in which the O-donor is the carbonyl of an amido group.
Thus, in the reaction of the 2-IC6H4-N(R)-CH2-CO-N(R)2
substrates (1a and 1b) with Pd(0), the formation of a highly
stable five-membered [N,O] chelate ring thwarts the formation
of the four-membered [C,N] palladacycle and forces the
formation of binuclear bridged Pd(II) complexes (2a and 2b).
This might be due to the high strain that would be associated
with the generation of a four- and five-membered ring fused
together and sharing a palladium atom with square-planar
geometry.15 On the other hand, the four-membered [C,N]
palladacycle appears to be more stable than a six-membered
[N,O] chelate ring, as demonstrated by the isolation of azapal-
ladacycles 5 and 6, in which the ligand acts as a two-coordinate,
four-electron donor, without closing the [N,O] chelate ring.
At this point, we turned our attention to 2-iodobenzylamine
type substrates (7, 10a, and 10b). The reaction of 2-iodoben-
zylamine 7, which bears one carbon atom between the amine
N and the carbonyl group, with Pd2(dba)3 (1:0.55 molar ratio)
produced the cyclometalated [C,N,O] palladium(II) complex 8
(99%), which simultaneously contains a five-membered palla-
dacycle and a five-membered [N,O] chelate ring (Scheme 4).
Both the ν(CdO) stretching frequency in the IR spectrum and
the resonances assigned to the NCH2 and CdO carbons in the
Finally, we studied the reactions of 2-iodobenzylamines
10a,b, which have two methylene carbons between the amine
N and the carbonyl group. Treatment of 2-iodobenzylamine 10a
with Pd2(dba)3 (1:0.55 molar ratio) afforded a reaction mixture
from which a slightly soluble compound (11a) was obtained
(Scheme 5). The ν(CdO) stretch clearly shows there is
coordination of the carbonyl group to the palladium atom. On
1
the other hand, both the H NMR and mass spectra point to a
dimeric structure for 11a. A similar reaction was observed
starting from 10b, which on treatment with Pd2(dba)3 afforded
the dimeric complex 11b.16,17 Unfortunately, as we failed to
obtain a single crystal suitable for X-ray studies, the exact
coordination mode in these complexes cannot be established.
However, treatment of 11a with PPh3 and Tl(TfO) gave the
cationic palladium(II) complex 12a, which simultaneously
contains a five-membered palladacycle and a six-membered
[N,O] chelate ring (81% overall yield from benzylamine 10a).
Under similar treatment, 11b afforded palladium complex 12b
in 62% overall yield from 10b. Compounds 12a,b are air-stable
foams, which were characterized by elemental analysis, high-
(16) The 1H NMR spectra of 11a and 11b showed broad signals. If one
proton is assigned to the resonance with the least integration in the spectra
of 11a and 11b, 46 and 38 protons are obtained, respectively, which
corresponds at least to a dimeric structure for these complexes (see
Experimental Section).
(17) For an example in which the simultaneous coordination of sulfur
and oxygen atoms in a multidonor ligand results in the formation of
polymeric species, see: Vicente, J.; Chicote, M.-T.; Rubio, C.; Ram´ırez de
Arellano, M. C.; Jones, P. G. Organometallics 1999, 18, 2750-2759.
(15) However, it should be noted that the generation of a transient
[C,N,O] terdentate [4,5] Pd(II) complex, which then would evolve to the
more stable binuclear Pd(II) complex, could not be completely rejected.

1998 Organometallics, Vol. 25, No. 8, 2006
Sole´ et al.
Figure 2. Molecular structure of 2b (ORTEP view). H atoms are
omitted for clarity. Selected interatomic distances [Å] and angles
[deg]: Pd(1)-Pd(2) ) 3.026(2), Pd(1)-I(1) ) 2.5867(9), Pd(1)-
O(1) ) 2.164(3), Pd(1)-N(3) ) 2.158(3), Pd(1)-C(1) ) 1.968-
(4), Pd(2)-I(2) ) 2.5870(9), Pd(2)-O(2) ) 2.164(3), Pd(2)-N(1)
) 2.157(3), Pd(2)-C(14) ) 1.973(4), O(1)-Pd(1)-I(1) ) 93.52-
(9), O(1)-Pd(1)-N(3) ) 79.30(12), C(1)-Pd(1)-N(3) ) 93.28-
(15), C(1)-Pd(1)-I(1) ) 92.41(12), N(3)-Pd(1)-I(1) ) 169.16(9),
C(1)-Pd(1)-O(1) ) 168.15(14), O(2)-Pd(2)-I(2) ) 94.93(8),
O(2)-Pd(2)-N(1) ) 79.27(12), C(14)-Pd(2)-N(1) ) 93.90(14),
C(14)-Pd(2)-I(2) ) 90.78(11), N(1)-Pd(2)-I(2) ) 167.12(9),
C(14)-Pd(2)-O(2) ) 171.63(13).
Figure 1. Molecular structure of 2a (ORTEP view). H atoms are
omitted for clarity. Selected interatomic distances [Å] and angles
[deg]: Pd(1)-Pd(2) ) 2.9965(18), Pd(1)-I(1) ) 2.5931(15), Pd-
(1)-O(1) ) 2.117(4), Pd(1)-N(2) ) 2.165(4), Pd(1)-C(22) )
1.975(5), Pd(2)-I(2) ) 2.6074(9), Pd(2)-O(2) ) 2.164(4), Pd-
(2)-N(4) ) 2.176(5), Pd(2)-C(11) ) 1.979(5), O(1)-Pd(1)-I(1)
) 89.32(13), O(1)-Pd(1)-N(2) ) 80.46(18), C(22)-Pd(1)-N(2)
) 93.7(2), C(22)-Pd(1)-I(1) ) 95.62(15), N(2)-Pd(1)-I(1) )
167.60(13), C(22)-Pd(1)-O(1) ) 171.6(2), O(2)-Pd(2)-I(2) )
95.99(13), O(2)-Pd(2)-N(4) ) 79.20(18), C(11)-Pd(2)-N(4) )
93.5(2), C(11)-Pd(2)-I(2) ) 90.21(18), N(4)-Pd(2)-I(2) )
165.51(12), C(11)-Pd(2)-O(2) ) 171.9(2).
resolution mass spectrometry, IR spectra, and 1H, 13C, and 31
P
NMR spectra. The IR spectra showed a shift of the ν(CdO)
stretch toward lower numbers compared with the free ligand,
due to Pd-O coordination. On the other hand, the 31P{1H} NMR
spectra of 12a and 12b displayed a phosphorus resonance at δ
1
38.9 and 41.0 ppm, respectively, and the H NMR spectra of
12b showed resonances due to the NCH3 and NCH2Ar protons
coupled to the 31P nucleus of the phosphine ligand (ca. 1.5 and
3.6 Hz, respectively); these data are in agreement with a
phosphorus trans to the coordinated nitrogen arrangement in
these complexes.9 Finally, the ESI-TOF mass spectra of 12a
and 12b showed a set of peaks, centered at 664 and 588 amu,
respectively, which correspond to the [MH - CF3SO3]+ ions.
These findings are in accordance with a monomeric terdentate
[C,N,O]-coordination mode for cationic Pd(II) complexes 12a,b.
In contrast to the failure of iodoanilines 1a,b and 4 to give
the terdentate complexes, 2-iodobenzylamines 7 and 10a,b did
afford terdentate [C,N,O] mononuclear palladium complexes
with either five-membered or six-membered [N,O] chelate rings.
Such strikingly different behavior is a consequence of the
formation of a highly stable five-membered azapalladacycle,18
which allows the ligand to act in a terdentate fashion in both
[5,5]- and [5,6]-fused ring systems.
X-ray Crystal Structures. The molecular structures of
complexes 2a, 2b, 3a‚C6H6‚3THF, and 8 have been determined
by X-ray diffraction studies and are shown in Figures 1-4,
respectively.
In complexes 2a, 2b, and 3a the two palladium centers are
bridged by two -C6H4-N(Me)-CH2-CO-NR2 ligands, each
of which is bonded as a η1-aryl ligand to one palladium atom
and acts as a η2-(N,O) ligand with the second palladium atom.
This arrangement leads to a short Pd-Pd contact [2.9965(18)
Å for 2a, 3.026(2) Å for 2b, and 3.0447(13) Å for 3a], which
is comparable to those found in related binuclear complexes
containing monoanionic three-atom bridging ligands.19 In the
three complexes the bridging ligands are cis with respect to each
Figure 3. ORTEP view of the cation of 3a. H atoms and the phenyl
groups of the PPh3 ligands are omitted for clarity. Selected
interatomic distances [Å] and angles [deg]: Pd(1)-Pd(2) ) 3.0447-
(13), Pd(1)-P(1) ) 2.2657(13), Pd(1)-O(1) ) 2.101(3), Pd(1)-
N(1) ) 2.193(3), Pd(1)-C(12) ) 1.948(4), Pd(2)-P(2) ) 2.2552-
(12), Pd(2)-O(2) ) 2.100(3), Pd(2)-N(3) ) 2.192(3), Pd(2)-C(1)
) 1.972, O(1)-Pd(1)-P(1) ) 92.98(8), O(1)-Pd(1)-N(1) )
80.56(12), C(12)-Pd(1)-N(1) ) 92.67(13), C(12)-Pd(1)-P(1) )
92.78(10), N(1)-Pd(1)-P(1) ) 159.82(8), C(12)-Pd(1)-O(1) )
172.97(11), O(2)-Pd(2)-P(2) ) 91.71(9), O(2)-Pd(2)-N(3) )
81.04(12), C(1)-Pd(2)-N(3) ) 93.18(16), C(1)-Pd(2)-P(2) )
92.58(13), N(3)-Pd(2)-P(2) ) 158.73(8), C(1)-Pd(2)-O(2) )
173.36(1).
other, whereas the ancillary ligands, I in 2a,b or PPh3 in 3a
and the amide carbonyl group, are trans related. This coordina-
tion produces a noncrystallographic pseudo-C2 symmetry axis
in the three compounds. In 2a, 2b, and 3a the palladium atom
displays a distorted square-planar coordination with the four
ligands deviated to the same side of the plane due to the steric
hindrance exerted by the second palladium atom. In the three
complexes the five-membered [N,O] chelate ring has an
envelope form with the nitrogen atom being the out-of-plane
atom.
(18) The formation of the four-membered azapalladacycle has been
calculated to be ≈ 10 kcal mol-1 less favorable than the corresponding
five-membered counterpart. Bosque, R.; Maseras, F. Eur. J. Inorg. Chem.
2005, 4040-4047.
(19) (a) Singhal, A.; Jain, V. K.; Nethaji, M.; Samuelson, A. G.;
Jayaprakash, D.; Butcher, R. J. Polyhedron 1998, 17, 3531-3540. (b)
Dupont, J.; Pfeffer, M.; Daran, J. C.; Jeannin, Y. Organometallics 1987, 6,
899-901, and references therein.

C,N,O-Terdentate and Binuclear Pd(II) Complexes
Organometallics, Vol. 25, No. 8, 2006 1999
to related ligands with different donor atoms in the pendant arm
and also to examine the chemical behavior and potential
application of the new families of palladium(II) complexes are
in progress and will be reported in due course.
Experimental Section
General Information. All reactions were performed under an
argon atmosphere using dry solvents. THF was distilled under
nitrogen from sodium benzophenone ketyl. Benzene was dried over
CaH2 and distilled under nitrogen. Other solvents were used as
received. Chemicals were used as received from Aldrich (Pd2(dba)3),
Fluka (PPh3), and Strem (Tl(TfO)). Chemical shifts are given in
Figure 4. Molecular structure of 8 (ORTEP view). H atoms are
omitted for clarity. Selected interatomic distances [Å] and angles
[deg]: Pd-I ) 2.5979(10), Pd-O ) 2.1815(19), Pd-N(1) )
2.077(2), Pd-C(1) ) 1.973(3), O-Pd-I ) 98.11(5), O-Pd-N(1)
) 80.40(7), C(1)-Pd-N(1) ) 83.39(10), C(1)-Pd-I ) 97.90-
(9).
parts per million (ppm) relative to Me4Si for 1H and 13C NMR. 31
P
NMR spectra were recorded in CDCl3 with external H3PO4 as
reference. IR spectra were recorded on a Nicolet 205 FT infrared
spectrophotometer, and only noteworthy absorptions are listed.
Melting points were determined in a capillary tube and are
uncorrected. Chromatography refers to flash chromatography and
was carried out on SiO2 (silica gel 60, 230-400 mesh ASTM).
Evaporation of solvents was accomplished with a rotatory evapora-
tor. Microanalyses were performed by Centro de Investigacio´n y
Desarrollo (CSIC), Barcelona.
The main intermolecular interactions in binuclear palladium
complexes 2a, 2b, and 3b‚C6H6‚3THF are C-H‚‚‚π-ring
interactions. In 2a intermolecular C-H‚‚‚π-ring interaction
between C(2)-H(2B) and the C(17)‚‚‚C(22) phenyl ring
(distance to the aromatic centroid ) 2.84 Å) produces a chain
of linked molecules along the crystallographic b-axis. On the
other hand, in 2b C-H‚‚‚π-ring interactions between C(23)-
H(23A) and the C(1)‚‚‚C(6) phenyl ring (distance to the aromatic
centroid ) 2.66 Å), and C(12)-H(12C) and the C(14)‚‚‚C(19)
phenyl ring (distance to the aromatic centroid ) 3.10 Å),
produce layers of linked molecules perpendicular to the crystal-
lographic c-axis. Finally, in binuclear cationic complex
3a‚C6H6‚3THF C-H‚‚‚π-ring interactions between C(24)-
H(24) and the C(29)‚‚‚C(34) phenyl ring (distance to the
aromatic centroid ) 3.15 Å), and C(31)-H(31) and the
C(35)‚‚‚C(40) phenyl ring (distance to the aromatic centroid )
2.98 Å), produce bimolecular units implying (x, y, z) and (2-
x, 1-y, -z) molecules. Moreover, in 3a‚C6H6‚3THF the benzene
solvates act as bridges between different bimolecular units also
by means of C-H‚‚‚π-ring interactions [C(32)-H(32)‚‚‚benzene
ring (distance to the aromatic centroid ) 2.85 Å) and C(26)-
H(26)‚‚‚benzene ring (distance to the aromatic centroid ) 3.04
Å)].
In complex 8 the palladium atom shows a square-planar
coordination, the largest deviation from the mean plane being
in the N atom [deviation of 0.016(2) Å]. The two fused five-
membered rings have an envelope form with the nitrogen atom
being in both rings the out-of-plane atom. The main intermo-
lecular interactions in palladium complex 8 are C-H‚‚‚π-ring
interactions between C(15)-H(15B) and the C(1)‚‚‚C(6) phenyl
ring (distance to the aromatic centroid ) 2.75 Å), C(18)-
H(18C) and the C(1)‚‚‚C(6) phenyl ring (distance to the aromatic
centroid ) 3.04 Å), and C(17)-H(17B) and the C(9)‚‚‚C(14)
phenyl ring (distance to the aromatic centroid ) 3.13 Å), which
produce a 3D-net of linked molecules.
[Pd{η-(N,C)-µ-N(Me)(C6H4-2)CH2C(O)N(Me)2}I]2 (2a). To a
solution of amide 1a (100 mg, 0.31 mmol) in benzene (15 mL)
was added Pd2(dba)3 (158 mg, 0.17 mmol). The reddish reaction
mixture was stirred at room temperature for 3 days. The solvent
was evaporated, and the residue was dissolved in dichloromethane
(25 mL) and then filtered through Celite. The filtrate was evaporated
to dryness and the residue triturated with Et2O. The resulting solid
was filtered, washed with Et2O, and dried to give 2a as a brown-
orange solid. Yield: 94 mg, 71%. Single crystals of complex 2a
were grown by slowly evaporating a dichloromethane solution.
Mp: 160-161 °C. IR (film): ν 1608 cm-1. 1H NMR (CDCl3, 300
MHz): δ 2.97 (s, 3H), 3.10 (s, 3H), 3.18 (d, J ) 17.1 Hz, 1H),
3.43 (s, 3H), 6.05 (d, J ) 17.1 Hz, 1H), 6.34 (dd, J ) 7.8 and 1.5
Hz, 1H), 6.50 (ddd, J ) 7.8, 7.2, and 1.5 Hz, 1H), 6.63 (ddd, J )
7.8, 7.2, and 1.5 Hz, 1H), 7.65 (dd, J ) 7.8 and 1.5 Hz, 1H). 13C
NMR (CDCl3, 75.4 MHz): δ 36.8 (CH3), 38.2 (CH3), 47.4 (CH3),
69.8 (CH2), 116.2 (CH), 122.8 (CH), 123.9 (CH), 134.9 (C), 138.0
(CH), 154.7 (C), 176.6 (C). Anal. Calcd for C22H30I2N4O2Pd2
(849.15): C, 31.12; H, 3.56; N, 6.60. Found: C, 31.21; H, 3.69;
N, 6.64.
[Pd{η-(N,C)-µ-N(Me)(C6H4-2)CH2C(O)N(Et)2}I]2 (2b). Op-
erating as in the preparation of 2a, starting from amide 1b (25 mg,
0.072 mmol) and Pd2(dba)3 (37 mg, 0.04 mmol), palladium complex
2b was obtained as a brown-orange solid. Yield: 29 mg, 88%.
Single crystals of complex 2b were grown by slowly evaporating
a dichloromethane-Et2O solution. Mp: 158 °C. IR (film): ν 1594
1
cm-1. H NMR (CDCl3, 300 MHz): δ 1.18 (t, J ) 7.2 Hz, 3H),
1.24 (t, J ) 7.2 Hz, 3H), 3.08 (d, J ) 17.1 Hz, 1H), 3.23 (m, 2H),
3.32 (dq, J ) 14.4 and 7.2 Hz, 1H), 3.43 (s, 3H), 3.67 (dq, J )
14.4 and 7.2 Hz, 1H), 6.12 (d, J ) 17.1 Hz, 1H), 6.34 (dd, J ) 8.1
and 1.5 Hz, 1H), 6.49 (ddd, J ) 8.1, 7.5, and 1.5 Hz, 1H), 6.63 (t,
J ) 7.5 and 1.5 Hz, 1H), 7.66 (dd, J ) 7.5 and 1.5 Hz, 1H). 13C
NMR (CDCl3, 75.4 MHz): δ 12.8 (CH3), 14.0 (CH3), 41.6 (CH2),
43.2 (CH2), 47.1 (CH3), 69.1 (CH2), 116.1 (CH), 122.7 (CH), 123.8
(CH), 135.3 (C), 138.0 (CH), 154.7 (C), 175.7 (C). Anal. Calcd
for C26H38I2N4O2Pd2 (905.25): C, 34.50; H, 4.23; N, 6.19. Found:
C, 34.73; H, 4.24; N, 6.00.
In summary, the -C6H4-N(R)-(CH2)n-CO-N(R)2 (n )
1, 2) and -C6H4-CH2-N(R)-(CH2)n-CO-N(R)2 (n ) 1, 2)
frameworks have been explored for their potential to act as three-
coordinate, six-electron-donor ligands. In this study, we have
shown that the four-membered [C,N] palladacycle is not
compatible with fused five- or six-membered [N,O] chelate rings
and that in the reaction of 2-IC6H4-N(R)-CH2-CO-N(R)2
substrates with Pd(0) this incompatibility results in the formation
of unprecedented C,N-bridged binuclear palladium(II) com-
pounds. On the other hand, the five-membered [C,N] pallada-
cycle fits perfectly into stable terdentate [C,N,O] palladium(II)
complexes involving either five-membered or six-membered
[N,O] chelate rings. Further investigation to extend this study
[Pd{η-(N,C)-µ-N(Me)(C6H4-2)CH2C(O)N(Me)2}(PPh3)]2 2TfO
(3a). To a solution of complex 2a (15 mg, 0.018 mmol) in THF (2
mL) was added Tl(TfO) (13 mg, 0.036 mmol). After stirring at
room temperature for 10 min, PPh3 (10 mg, 0.036 mmol) was added.
The resulting suspension was stirred at room temperature for 2 h.
The mixture was filtered through Celite, washing carefully with

2000 Organometallics, Vol. 25, No. 8, 2006
Sole´ et al.
THF. The filtrate was evaporated to dryness, and the residue was
triturated with a mixture of THF (2 mL) and benzene (1 mL). The
resulting solid was filtered, washed with benzene, and dried to give
complex 3a as a pale yellow solid. Yield: 19 mg, 76%. Single
crystals of complex 3a were grown by slowly evaporating a
dichloromethane-benzene-THF solution. Mp: 155-158 °C. IR
(film): ν 1613 cm-1. 1H NMR (CDCl3, 400 MHz): δ 2.34 (s, 3H),
2.53 (s, 3H), 3.44 (dd, J ) 16 and 4 Hz, 1H), 3.53 (s, 3H), 4.22 (d,
J ) 16 Hz, 1H), 6.58 (t, J ) 7.5 Hz, 1H), 6.72 (d, J ) 8 Hz, 1H),
6.79 (dd, J ) 8 and 7.5 Hz, 1H), 6.92 (dd, J ) 7.5 and 4.5 Hz,
1H), 7.30-7.80 (broad band, 15H). 13C NMR (CDCl3, 100.6
MHz): δ 36.3 (CH3), 39.0 (CH3), 48.0 (CH3), 66.5 (CH2), 120.2
(CH), 120.9 (q, J ) 320.5 Hz, C), 125.2 (CH), 125.6 (CH), 129.5
(CH), 132.1 (CH), 133.8 (CH), 134.9 (d, J ) 5.4 Hz, CH), 139.2
(d, J ) 6.1 Hz, C), 153.3 (C), 175.8 (C), one C was not observed.
31P NMR (CDCl3, 121.5 MHz): δ 27.1. Anal. Calcd for
C60H60F6N4O8P2Pd2S2 (1418.06): C, 50.82; H, 4.26; N, 3.95.
Found: C, 50.71; H, 4.35; N, 3.86.
126.3 (CH), 127.9 (CH), 129.8 (d, J ) 10.8 Hz, CH), 131.7 (d, J
) 51.3 Hz, C), 132.4 (CH), 136.1 (d, J ) 12.0 Hz, CH), 160.5
(C), 172.0 (C). Only the most significant resonances are reported.
Since this compound is unstable, minor resonances were observed
in the 13C NMR experiment.
[Pd{κ3C,N,O-C6H4{CH2N(CH2C6H5)CH2C(O)N(Me)2}-2}I] (8).
To a solution of amide 7 (25 mg, 0.061 mmol) in benzene (4 mL)
was added Pd2(dba)3 (31 mg, 0.034 mmol). The reddish reaction
mixture was stirred at room temperature for 3 days. The reaction
mixture was filtered through Celite, washing carefully with benzene.
The benzene filtrate was discarded, and then the washing was
continued with dichloromethane. The dichloromethane filtrate was
evaporated to dryness to give 8 as a yellow solid. Yield: 31 mg,
99%. Single crystals of complex 8 were grown by slowly evaporat-
ing a dichloromethane-benzene solution. Mp: 198 °C. IR (film):
1
ν 1597 cm-1. H NMR (CDCl3, 300 MHz): δ 2.13 (s, 3H), 2.65
(s, 3H), 3.71 (d, J ) 12.4 Hz, 1H), 3.80 (d, J ) 16.5 Hz, 1H), 3.98
(d, J ) 14.1 Hz, 1H), 4.55 (d, J ) 12.4 Hz, 1H), 5.24 (d, J ) 14.1
Hz, 1H), 5.87 (d, J ) 16.5 Hz, 1H), 6.75 (td, J ) 8.1 and 1.8 Hz,
1H), 6.80-6.92 (m, 2H), 7.30-7.42 (m, 3H), 7.77 (dd, J ) 8.1
and 1.8 Hz, 2H), 8.02 (d, J ) 8.1 Hz, 1H). 13C NMR (CD2Cl2,
75.4 MHz): δ 35.9 (CH3), 38.6 (CH3), 61.8 (CH2), 66.1 (CH2),
70.4 (CH2), 123.1 (CH), 124.3 (CH), 126.6 (CH), 128.8 (CH), 129.8
(CH), 132.3 (CH), 132.4 (C), 142.5 (CH), 143.6 (C), 150.8 (C),
175.9 (C). Anal. Calcd for C18H21IN2OPd (514.70): C, 42.00; H,
4.11; N, 5.44. Found: C, 41.85; H, 4.09; N, 5.16.
[Pd{κ3C,N,O-C6H4{CH2N(CH2C6H5)CH2C(O)N(Me)2}-2}-
(PPh3)] TfO (9). Operating as in the preparation of 3a, starting
from palladium complex 8 (15 mg, 0.029 mmol), Tl(TfO) (16 mg,
0.045 mmol), and PPh3 (11 mg, 0.042 mmol), palladium complex
9 was obtained as a pale yellow foam. Yield: 20 mg, 87%. IR
(film): ν 1609 cm-1. 1H NMR (CDCl3, 300 MHz): δ 2.15 (s, 3H),
3.03 (s, 3H), 4.10 (dd, J ) 12.3 and 5.4 Hz, 1H), 4.37 (dd, J )
14.4 and 3 Hz, 1H), 4.43 (d, J ) 17.4 Hz, 1H), 4.54 (d, J ) 12.3
Hz, 1H), 4.70 (dd, J ) 17.4 and 3.6 Hz, 1H), 4.98 (dd, J ) 14.4
and 2.4 Hz, 1H), 6.36 (dd, J ) 7.5 and 4.2 Hz, 1H), 6.55 (td, J )
7.5 and 1.2 Hz, 1H), 6.94 (td, J ) 7.5 and 1.2 Hz, 1H), 7.08 (d, J
) 7.5 Hz, 1H), 7.20-7.71 (m, 18H), 7.89 (m, 2H). 13C NMR
(CDCl3, 75.4 MHz): δ 35.6 (CH3), 38.7 (CH3), 61.5 (CH2), 65.3
(CH2), 70.1 (CH2), 120.8 (q, J ) 320.5 Hz, C), 124.5 (CH), 125.2
(CH), 126.1 (d, J ) 4 Hz, CH), 128.2 (CH), 128.6 (br, CH), 128.7
(CH), 131.4 (CH), 131.8 (CH), 133.2 (C), 134.6 (d, J ) 12.1 Hz,
CH), 137.6 (d, J ) 9.2 Hz, CH), 145.5 (d, J ) 4.6 Hz, C), 151.9
(C), 177.0 (C), one C was not observed. 31P NMR (CDCl3, 121.5
MHz): δ 38.3. Anal. Calcd for C37H36F3N2O4PPdS (799.15): C,
55.61; H, 4.54; N, 3.51. Found: C, 55.24; H, 4.99; N, 3.69. HRMS
(ESI-TOF): m/z 650.1654 ([MH - CF3SO3]+, 650.1673 calcd for
C36H37N2OPPd).
[Pd{η-(N,C)-µ-N(Me)(C6H4-2)CH2C(O)N(Et)2}(PPh3)]2 2TfO
(3b). Operating as in the preparation of 3a, starting from palladium
complex 2b (22 mg, 0.024 mmol), Tl(TfO) (24 mg, 0.068 mmol),
and PPh3 (17 mg, 0.065 mmol), palladium complex 3b was obtained
as a pale yellow solid. Yield: 34 mg, quantitative. IR (film): ν
1
1595 cm-1. H NMR (CDCl3, 300 MHz): δ 0.73 (t, J ) 7.2 Hz,
3H), 0.77 (t, J ) 7.2 Hz, 3H), 2.64-2.92 (m, 4H), 3.42 (dd, J )
15.6 and 4.2 Hz, 1H), 3.53 (s, 3H), 4.46 (dd, J ) 15.6 and 2.7 Hz,
1H), 6.57 (td, J ) 7 and 1.8 Hz, 1H), 6.79-6.93 (m, 3H), 7.30-
7.80 (broad band, 15H). 13C NMR (CDCl3, 100.6 MHz): δ 12.8
(CH3), 13.6 (CH3), 42.8 (CH2), 45.2 (CH2), 47.2 (CH3), 65.7 (CH2),
120.8 (CH), 120.8 (q, J ) 320.5 Hz, C), 125.4 (CH), 125.8 (CH),
129.6 (d, J ) 9.8 Hz, CH), 132.2 (CH), 133.6 (d, J ) 9.7 Hz,
CH), 134.8 (d, J ) 4.6 Hz, CH), 138.3 (d, J ) 6.3 Hz, C), 152.4
(C), 174.8 (C), one C was not observed. 31P NMR (CDCl3, 121.5
MHz): δ 27.3. These NMR spectra contain small signals due to
the presence of OPPh3, which could not be removed.
[Pd{κ2C,N-4-MeC6H3{N(Me)CH2CH2C(O)N(Me)2}-2}I(P-
Ph3)] (5). To a solution of amide 4 (30 mg, 0.087 mmol) in benzene
(4 mL) were added Pd2(dba)3 (44 mg, 0.048 mmol) and PPh3 (25
mg, 0.095 mmol). The reddish reaction mixture was stirred at room
temperature for 24 h. The mixture was filtered through Celite. The
filtrate was evaporated to dryness, and the residue was purified by
chromatography. Elution with CH2Cl2-MeOH 1% afforded pure
azapalladacycle 5 as a brown foam. Yield: 60 mg, 97%. IR
(film): ν 1645 cm-1. 1H NMR (CDCl3, 300 MHz): δ 1.89 (s, 3H),
2.56 (m, 1H), 2.87 (s, 3H), 3.01 (s, 3H), 3.16 (s, 3H), 3.33-3.72
(m, 3H), 5.56 (d, J ) 0.6 Hz, 1H), 6.77 (d, J ) 8.1 Hz, 1H), 6.83
(dd, J ) 8.1 and 1.8 Hz, 1H), 7.35-7.50 (m, 9H), 7.67-7.77 (m,
6H). 13C NMR (CDCl3, 75.4 MHz): δ 21.9 (CH3), 33.5 (CH2),
35.3 (CH3), 37.7 (CH3), 51.2 (CH3), 56.0 (CH2), 118.8 (CH), 125.5
(d, J ) 10.3 Hz, C), 126.3 (CH), 128.1 (d, J ) 10.9 Hz, CH),
128.8 (d, J ) 7.5 Hz, CH), 130.8 (d, J ) 2.3 Hz, CH), 131.6 (d,
J ) 51.7 Hz, C), 135.0 (d, J ) 11.5 Hz, CH), 134.9 (d, J ) 2.9
Hz, C), 159.3 (d, J ) 4.6 Hz, C), 170.3 (C). 31P NMR (CDCl3,
121.5 MHz): δ 40.9. Anal. Calcd for C31H34IN2OPd (714.91)‚3/
4CH2Cl2: C, 48.98; H, 4.60; N, 3.60. Found: C, 49.32; H, 4.56;
N, 3.60.
[Pd{κ3C,N,O-C6H4{CH2N(CH2C6H5)CH2CH2C(O)N(Me)2}-
2}(PPh3)] TfO (12a). To a solution of amide 10a (25 mg, 0.059
mmol) in benzene (4 mL) was added Pd2(dba)3 (30 mg, 0.033
mmol). The reddish reaction mixture was stirred at room temper-
ature for 45 h. The reaction mixture was filtered through Celite,
washing carefully with benzene. The benzene filtrate was discarded,
and then the washing was continued with dichloromethane. The
dichloromethane filtrate was evaporated to dryness to give 11a as
a yellow solid. Yield: 26 mg, 84%. Dimeric palladium complex
11a: IR (film): ν 1599 cm-1. 1H NMR (CDCl3, 300 MHz): δ 2.92
(br, 18H), 3.40 (br, 2H), 3.60-4.20 (br m, 4H), 4.36 (br, 3H), 4.66
(br, 1H), 6.79 (m, 2H), 6.94 (m, 4H), 7.30-7.44 (m, 6H), 7.62 (m,
[Pd{κ2C,N-4-MeC6H3{N(Me)CH2CH2C(O)N(Me)2}-2}OTf-
(PPh3)] (6). To a solution of complex 5 (25 mg, 0.035 mmol) in
THF (3 mL) was added Tl(TfO) (13 mg, 0.036 mmol), and the
mixture was stirred at room temperature for 3 h. The reaction
mixture was filtered through Celite, washing carefully with THF.
The filtrate was evaporated to dryness to give crude Pd(II) complex
6 (29 mg, quantitative). IR (film): ν 1644 cm-1. 1H NMR (CDCl3,
200 MHz): δ 1.90 (m, 2H), 1.93 (s, 3H), 2.80 (s, 3H), 3.12 (s,
6H), 3.60-3.80 (m, 2H), 5.60 (s, 1H), 6.89 (s, 2H), 7.36-7.65
(m, 15H). 13C NMR (THF-d8, 75.4 MHz): δ 22.5 (CH3), 31.3
(CH2), 36.3 (CH3), 38.4 (CH3), 49.8 (CH3), 59.9 (CH2), 119.9 (CH),
5H), 8.10 (br, 1H). MS (ESI+): m/z 931 (2M+ - I), 401 (M+
I).
-
Operating as in the preparation of 3a, starting from palladium
complex 11a (26 mg, 0.025 mmol), Tl(TfO) (26 mg, 0.075 mmol),
and PPh3 (20 mg, 0.075 mmol), palladium complex 12a was
obtained as a pale yellow foam. Yield: 39 mg, 97%. IR (film): ν
1598 cm-1. 1H NMR (CDCl3, 300 MHz): δ 1.89 (s, 3H), 2.94 (s,

C,N,O-Terdentate and Binuclear Pd(II) Complexes
Organometallics, Vol. 25, No. 8, 2006 2001
Table 1. Selected Crystallographic Data of Complexes 2a, 2b, 3a‚C6H6‚3THF, and 8
2a
2b
3a‚C6H6‚3THF
8
formula
fw
cryst syst
space group
a, Å
C22H30I2N4O2Pd2
849.10
monoclinic
P21/a
17.186(12)
10.020(3)
17.288(8)
90
113.78(4)
90
C26H38I2N4O2Pd2
905.20
monoclinic
P21/c
16.080(13)
11.373(4)
17.164(7)
90
91.09(5)
90
C78H90F6N4O11P2Pd2S2
1712.40
triclinic
C18H21IN2OPd
514.67
monoclinic
P21/n
9.418(4)
12.549(4)
15.614(5)
90
94.89(4)
90
P1h
12.637(6)
13.777(5)
25.508(8)
76.80(3)
76.80(3)
64.27(3)
3852(3)
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
2724(2)
4
2.070
3138(3)
4
1.916
1838.6(11)
4
1.859
2
D
calcd, Mg/m3
1.476
F(000)
1616
1744
1764
1000
cryst size, mm
θ range, deg
0.2 × 0.1 × 0.1
2.38-30.04
8099
7876 (0.0480)
0.0581
0.1 × 0.1 × 0.2
2.15-29.96
9541
9096 (0.0375)
0.0361
0.1 × 0.1 × 0.2
3.45-31.97
28291
16 780 (0.0378)
0.0438
0.1 × 0.1 × 0.2
3.50-28.36
3764
3764 (0.0328)
0.0420
no. of rflns collected
no. of indep rflns (Rint
R1 (I > 2σ(I))
)
wR2 (I > 2σ(I))
0.1426
1.050
0.0940
1.059
0.1003
0.893
0.0919
1.305
goodness of fit on F2
3H), 2.88-3.05 (m, 1H), 3.16-3.48 (m, 3H), 3.83 (d, J ) 13.5
Hz, 1H), 3.90 (d, J ) 13.8 Hz, 1H), 4.24 (d, J ) 13.5 Hz, 1H),
4.82 (d, J ) 13.8 Hz, 1H), 6.31 (dd, J ) 7.8 and 0.9 Hz, 1H), 6.54
(ddd, J ) 7.8, 7.5, and 1.2 Hz, 1H), 6.96 (ddd, J ) 7.5, 7.2, and
0.9 Hz, 1H), 7.14 (dd, J ) 7.2 and 1.2 Hz, 1H), 7.30-7.72 (m,
20H). 13C NMR (CDCl3, 75.4 MHz): δ 31.1 (CH2), 35.6 (CH3),
38.7 (CH3), 52.7 (CH2), 60.8 (CH2), 67.3 (CH2), 120.9 (q, J )
320.4 Hz, C), 124.3 (CH), 125.2 (CH), 125.9 (CH), 128.4 (CH),
128.5 (d, J ) 8.6 Hz, CH), 128.7 (CH), 131.3 (CH), 131.9 (CH),
132.6 (C), 134.2 (br, CH), 136.6 (CH), 143.2 (C), 147.3 (C), 173.8
(C), one C was not observed. 31P NMR (CDCl3, 121.5 MHz): δ
38.9. Anal. Calcd for C38H38F3N2O4PPdS (813.17): C, 56.13; H,
4.71; N, 3.44. Found: C, 56.29; H, 5.11; N, 3.33. HRMS (ESI-
TOF): m/z 664.1814 ([MH - CF3SO3]+, 664.1829 calcd for
C37H39N2OPPd).
[Pd{κ3C,N,O-C6H4{CH2N(Me)CH2CH2C(O)N(Me)2}-2}(PPh3)]-
TfO (12b). To a solution of amide 10b (25 mg, 0.072 mmol) in
benzene (4 mL) was added Pd2(dba)3 (37 mg, 0.04 mmol). The
reddish reaction mixture was stirred at room temperature for 45 h.
The reaction mixture was filtered through Celite, washing carefully
with benzene. The benzene filtrate was discarded, and then the
washing was continued with dichloromethane. The dichloromethane
filtrate was evaporated to dryness to give 11b as a yellow solid.
Yield: 25 mg, 75%. Dimeric palladium complex 11b: 1H NMR
(CDCl3, 300 MHz): δ 2.64 (br, 6H), 2.91 (br, 6H), 2.99 (br, 12H),
3.17 (br, 1H), 3.44 (br, 1H), 3.70 (br, 1H), 3.97 (br, 1H), 4.18 (br,
1H), 4.69 (br, 1H), 6.78 (br, 2H), 6.93 (br m, 4H), 7.61 (br m,
1H), 8.04 (br m, 1H).
7.5, and 1.2 Hz, 1H), 6.90 (ddd, J ) 7.5, 7.2, and 0.9 Hz, 1H),
7.05 (d, J ) 7.2 Hz, 1H), 7.38-7.60 (m, 15H). 13C NMR (CDCl3,
75.4 MHz): δ 29.8 (CH2), 35.6 (CH3), 38.5 (CH3), 44.9 (CH3),
55.5 (CH2), 70.6 (CH2), 120.8 (q, J ) 320.4 Hz, CF3), 123.6 (CH),
125.1 (CH), 125.7 (CH), 128.6 (d, J ) 9.7 Hz, CH), 130.4 (br,
CH), 134.5 (br, CH), 137.1 (CH), 141.4 (C), 148.1 (C), 172.7 (C).
31P NMR (CDCl3, 121.5 MHz): δ 41.0. Anal. Calcd for
C32H34F3N2O4PPdS (737.08): C, 52.14; H, 4.65; N, 3.80. Found:
C, 52.08; H, 4.83; N, 3.78. HRMS (ESI-TOF): m/z 588.1505 ([MH
- CF3SO3]+, 588.1516 calcd for C31H35N2OPPd).
Crystallography. Intensities were collected with an Enraf-
Nonius CAD4 four-circle diffractometer for complexes 2a and 2b
and with a MAR345 diffractometer for complexes 3a‚C6H6‚3THF
and 8. The structure of complex 2a was solved by Patterson
synthesis, and the structures of complexes 2b, 3a‚C6H6‚3THF, and
8 were solved by direct methods, using in all cases the SHELXS97
computer program. The structures were refined by full-matrix least-
squares method with the SHELXL97 computer program.20 Crystal
data for complexes 2a, 2b, 3a‚C6H6‚3THF, and 8 are listed in Table
1, and their ORTEP plots are shown in Figures 1-4, respectively
(H atoms and solvents are omitted for clarity). Other crystal-
lographic data are deposited as Supporting Information.
Acknowledgment. This work was supported by MEC
(Spain)-FEDER (Project CTQ2004-04701/BQU) and DURSI-
Catalonia (Grant 2005SGR-00442). D.S. thanks the DURSI for
“Distincio´ per a la Promocio´ de la Recerca Universita`ria”.
Supporting Information Available: Crystallographic data of
2a, 2b, 3a‚C6H6‚3THF, and 8 are given in PDF and CIF formats.
Characterization data and experimental procedures for the prepara-
tion of starting materials are also given. This material is available
free of charge via the Internet at http://pubs.acs.org.
Operating as in the preparation of 3a, starting from palladium
complex 11b (25 mg, 0.027 mmol), Tl(TfO) (29 mg, 0.082 mmol),
and PPh3 (22 mg, 0.082 mmol), palladium complex 12b was
obtained as a pale yellow foam. Yield: 33 mg, 83%. IR (film): ν
1598 cm-1. 1H NMR (CDCl3, 300 MHz): δ 1.96 (s, 3H), 2.68 (d,
J ) 1.5 Hz, 3H), 3.04 (s, 3H), 2.94-3.28 (m, 3H), 3.64 (dd, J )
13.2 and 3.6 Hz, 1H), 3.64-3.75 (m, 1H), 4.74 (d, J ) 13.2 Hz,
1H), 6.18 (ddd, J ) 7.8, 5.4, and 0.9 Hz, 1H), 6.45 (ddd, J ) 7.8,
OM051014M
(20) Sheldrick, G. M. SHELXL97, computer program for the determi-
nation of crystal structure; University of Go¨ttingen: Germany, 1997.