Dimetalated crown ether schiff base palladacycles. Influence of the carbon chain length on the coordination mode of bidentate phosphines. Crystal and molecular structure of the novel complex [Pd2{1,4-[C(H)=N{9,10- (C8H16O<

Article abstract of DOI:10.1021/om100833w

Reaction of the Schiff base ligand 1,4-[C(H)=N{9,10-(C₈H ₁₆O₅)C₆H₃}]₂C ₆H₄ (a), derived from terephthalaldehyde and 4′-aminobenzo-15-crown-5, with Pd(OAc)₂

Full text of DOI:10.1021/om100833w

386 Organometallics 2011, 30, 386–395
DOI: 10.1021/om100833w
Dimetalated Crown Ether Schiff Base Palladacycles. Influence of the
Carbon Chain Length on the Coordination Mode of Bidentate Phosphines.
Crystal and Molecular Structure of the Novel Complex
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5}-
(Cl)2{μ-Ph2P(CH2)5PPh2}2]
,†
Alberto Fernandez,* Margarita Lopez-Torres, Samuel Castro-Juiz, Manuel Merino,
†
†
†
ꢀ
ꢀ
Digna Vazquez-Garcıa, Jose M. Vila,* and Jesus J. Fernandez
†
,‡
ꢀ ꢀ
†
ꢀ
ꢀ
´
†
´
Departamento de Quımica Fundamental, Universidade da Coruna, E-15071 La Coruna, Spain, and
Departamento de Quımica Inorganica, Universidad de Santiago de Compostela, E-15782 Santiago de
~
~
‡
´
ꢀ
Compostela, Spain
Received August 26, 2010
Reaction of the Schiff base ligand 1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H4 (a), derived from
terephthalaldehyde and 40-aminobenzo-15-crown-5, with Pd(OAc)2 in chloroform at 50 °C for 96 h,
gave the polymeric compound [Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,N0}-
(μ-O2CMe)2]n (1a) after double C-H activation at the C2 and C5 phenyl carbons. The metathesis
reaction of 1a with saturated solutions of NtBu4Cl or NtBu4Br gave [Pd2{1,4-[C(H)dN{9,10-
(C8H16O5)C6H3}]2C6H2-C2,C5,N,N0}(μ-Cl)2]n (2a) and [Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2-
C6H2-C2,C5,N,N0}(μ-Br)2]n (3a), respectively, with exchange of the acetate group by a chloride or
bromine ligand, also respectively, which likewise adopt polymeric arrangements. Further reaction of
2a with thallium acetylacetonate gave the dinuclear complex [Pd2{1,4-[C(H)dN{9,10-(C8H16O5)-
C6H3}]2C6H2-C2,C5,N,N0}{MeC(O)CH-C(O)Me-O,O0}2] (4a), whereas treatment of 2a with mono-
phosphines in a 1:1 molar ratio resulted in splitting of the polymer and yielded the dinuclear
complexes [Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,N0}(Cl)2(L)2] (5a, L = PPh3;
6a, L = P(p-MeOC6H4)3). The reactions of 2a with diphosphines were influenced by the length of the
alkyl chain binding the two phosphorus atoms and the relative palladium atom/diphosphine molar
ratio. Reaction of 2a with dppm in a 2:1 ratio gave the tetranuclear compound [{Pd2[1,4-
{C(H)dN[9,10-(C8H16O5)C6H3]}2C6H2-C2,C5,N,N0](Cl)2}2(μ-Ph2PCH2P-Ph2)2] (7a) with the di-
phosphine in a bridging mode. However, treatment of 2a with dppm or dppe in a 1:1 ratio gave
the dinuclear complexes [Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,N0}(Ph2PRPh2-
P,P0)2][Cl]2 (8a, R = CH2; 9a, R = (CH2)2, respectively) with two chelating phosphines. With the
longer chain diphosphines Ph2P(CH2)nPPh2 (n = 4, dppb; n = 5, dpppe; n = 6, dpph) in a 1:1
palladium/diphosphine molar ratio the dinuclear compounds [Pd2{1,4-[C(H)dN{9,10-(C8H16-
O5)C6H3}]2C6H2-C2,C5}(Cl)2{μ-Ph2P(CH2)nPPh2}2] (10a, n = 4; 11a, n = 5; 12a, n = 6) were
obtained, with two diphosphines intramolecularly bridging both palladium atoms. The molecular
structures of compounds 5a, and 11a have been determined by X-ray diffraction analysis.
1. Introduction
the ether ring, and the solvent; consequently, it is possible to
tailor-make different types ligands for specific uses.3 Thus,
promising potential applications are being studied, such as
the production of sensors, the selective extraction of cations,
the ionic transport in membranes, the preparation of photo-
chemically controlled and electrochemically active receptors,
and compounds with promising anticancer properties.4
Ryabov5 has reported the first cyclopalladated compound
with a crown ether fragment, and, more recently, our
laboratory has previously prepared metalloligands derived
from cyclometalated complexes whose structure determines
the coordination possibilities of the ether crown moieties
and, consequently, improves their selectivity toward cations.6
For example palladium(II) cyclometalated acetate-bridged
Cyclometalated complexes exhibit a good number of
applications, which range from the synthesis of new organic
and organometallic compounds to mesogenic species and
catalytic materials1 as well as promoting unusual coordina-
tion environments.2 On the other hand crown ethers are
ubiquitous in supramolecular chemistry as hosts for cations
such as alkali and alkaline-earth metal cations. Their co-
ordinating properties depend on many structural character-
istics, such as the different cavity size, the conformation of
*To whom correspondence should be addressed. E-mail: qiluaafl@
udc.es; josemanuel.vila@usc.es.
r
pubs.acs.org/Organometallics
Published on Web 01/10/2011
2011 American Chemical Society

Article
Organometallics, Vol. 30, No. 3, 2011 387
complexes bearing a folded structure present a pseudosand-
wich arrangement capable of coordinating relatively large
cations, whereas their derivatives with chlorine bridging
ligands, with a planar structure, essentially showed the same
reactivity as the stand-alone crown ether ligands. Therefore,
by carefully choosing the structural characteristics of a
metalloligand it is possible to modulate its reactivity.7
Furthermore, we were also interested in studying not only
the coordination possibilities of the attached crown ether
rings but likewise their influence in the structure of the
metallacycles, in agreement with our past studies related to
coordination polymers derived from dicyclometalated Schiff
base ligands,8 and we have observed that imine crown ether
ligands also give rise to similar 1D polymers.
Moreover, we have extensively studied the reactivity of
cyclometalated complexes with tertiary diphosphines, and
we have found that it mainly depends on two factors: the
structure of the parent cyclometalated complex and the
relative palladium atom/phosphine molar ratio. While uni-
dentate phosphines usually produce complexes of the same
nuclearity as the parent compound, regardless of the molar
ratio,9 the reactivity of diphosphines is more diverse and
highly dependent on the number of metal centers at the
starting material as well as on the molar ratio used.10 Hence,
reaction of the latter with mononuclear palladacycles may
give species with bridging or with chelating diphosphines,
but with dinuclear complexes the structural possibilities
increase enormously, giving di-, tetra-, or polynuclear
compounds;3i,8,10,11 also the diphosphines may bridged intra-
or intermolecularly.12
With these considerations in mind, we reasoned that
terdentate [C,N,N,C] crown ether Schiff bases should be
adequate to prepare dicyclometalated complexes having a
polymeric structure, that is, coordination polymers. Further-
more, we also tested the reactivity of such ligands toward
tertiary mono- and diphoshines in order to find new, and
hopefully unexpected, results, as has been the case of the
unusual structure found for the compound with dpppe,
where two diphosphines bridge intramolecularly across the
phenyl ring linking the two metal centers.
2. Results and Discussion
(1) (a) Pfeffer, M.; Sutter, J. P.; Rottevel, M. A.; de Cian, A.; Fischer,
J. Tetrahedron 1992, 48, 2427. (b) Ryabov, A. D.; van Eldik, R.; Le Borgne,
G.; Pfeffer, M. Organometallics 1993, 12, 1386. (c) Wild, B. S. Coord.
Chem. Rev. 1997, 166, 291. (d) Chooi, S. Y. M.; Leung, P. H.; Lim, C. C.;
Mok, K. F.; Quek, G. H.; Sim, K. Y.; Tan., M. K. Tetrahedron: Asymmetry
1992, 3, 529. (e) Espinet, P.; Esteruelas, M. A.; Oro, L. A.; Serrano, J. L.; Sola,
E. Coord. Chem. Rev. 1992, 17, 215. (f) Navarro-Ranninger, C.; Lopez
Solera, I.; Rodríguez, J.; García-Ruano, J. L.; Raithby, P. R.; Masaguer, J. R.;
Alonso, C. J. Med. Chem. 1993, 36, 3795. (g) Navarro-Ranninger, C.;
For the convenience of the reader the compounds and
reactions are shown in Schemes 1 and 2. The compounds
were characterized by elemental analysis (C, H, N), mass
spectrometry, IR, and 1H, 31P{1H}, and (in part) 13C{1H} NMR
spectroscopy (data in Experimental Section).
2.1. Synthesis of Cyclometalated Complexes. The Schiff
base ligand 1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H4, a,
was prepared by condensation of terephthalaldehyde and 40-
aminobenzo-15-crown-5 in chloroform and isolated as an
air-stable solid, which was fully characterized (see Experi-
mental Section).
We have previously reported that reaction of potentially
tetradentate [C,N,C,N] Schiff bases derived from terephtha-
laldehyde with palladium(II) acetate in acetic acid produces
cleavage of one imine CdN double bond to give monocy-
clometalated complexes with a free formyl group;13 however,
ꢀ
ꢀ
ꢀ
ꢀ
Lopez-Solera, I.; Gonzalez, V. M.; Perez, J. M.; Alvarez-Valdes, A.; Martin,
A.; Raithby, P. R.; Masaguer, J. R.; Alonso, C. Inorg. Chem. 1996, 35, 5181.
ꢀ
(h) Bose, A.; Saha, C. H. J. Mol. Catal. 1989, 49, 271. (i) Lopez-Torres, M.;
ꢀ
ꢀ
ꢀ
Fernandez, A.; Fernandez, J. J.; Castro-Juiz, S.; Suarez, A.; Vila, J. M.;
ꢀ
Pereira, M. T. Organometallics 2001, 20, 1350. (j) Gomez-Quiroga, A.;
Navarro-Ranninger, C. Coord. Chem. Rev. 2004, 248, 119. (k) Omae, I. J.
Organomet. Chem. 2007, 692, 2608. (l) Ghedini, M.; Aiello, I.; Crispini, A.;
Golemme, A.; La Deda, M.; Pucci, D. Coord. Chem. Rev. 2006, 250, 1373.
(m) Chase, P. A.; Klein-Gebbink, R. J. M.; van Koten., G. J. Organomet.
Chem. 2004, 298, 4016.
ꢀ
(2) Vila, J. M.; Pereira, M. T.; Ortigueira, J. M.; Fernandez, J. J.;
ꢀ
ꢀ
Fernandez, A.; Lopez-Torres, M.; Adams, H. Organometallics 1999, 18,
5484.
(3) (a) Izatt, R. M.; Bradshaw, J. S.; Nielsen, S. A.; Lamb, J. D.;
Christensen, J. J.; Sen, D. Chem. Rev. 1985, 85, 271. (b) Inoue, Y.; Gokel,
G. W., Eds. Cation Binding by Macrocycles; Marcel Dekker: New York,
1990. (c) Lehn, J. M.; Montavon, F. Helv. Chim. Acta 1978, 61, 67. (d) Izatt,
R. M.; Christensen, J. J., Eds. Synthetic Multidentate Macrocyclic Com-
(5) Bezsoudnova, E. Y.; Ryabov, A. D. J. Organomet. Chem. 2001,
622, 38.
ꢀ ꢀ ꢀ
(6) Castro-Juiz, S.; Fernandez, A.; Lopez-Torres, M.; Vazquez-
€
pounds; Academic Press: London, 1978. (e) Vogtle, F.; Weber, E., Eds.
ꢀ ꢀ
Garcıa, D.; Suarez, A.; J. Vila, J. M.; Fernandez, J. J. Organometallics
´
Host-/Guest Complex Chemistry: Macrocycles; Springer-Verlag: Berlin,
1985. (f) Izatt, R. M.; Christensen, J. J., Eds. Synthesis of Macrocycles: The
Design of Selective Complexing Agents. In Progress in Macrocyclic
Chemistry, Vol. 3; Wiley: New York, 1987. (g) Gokel, G. W. Crown Ethers
and Cryptands. In Monographs in Supramolecular Chemistry; The Royal
Society of Chemistry: Cambridge, 1991. (h) Cooper, S. R., Ed. Crown
Compounds: Towards Future Applications; Wiley Interscience: New York,
1992. (i) Yordanov, A. T.; Roundhill, D. M. Coord. Chem. Rev. 1998,
170, 93.
2009, 28, 6657.
(7) Arias, J.; Bardajı, M.; Espinet, P. J. Organomet. Chem. 2006, 691,
4990.
ꢀ
ꢀ
ꢀ
ꢀ
(8) (a) Lopez Torres, M.; Fernandez, A.; Fernandez, J. J.; Suarez, A.;
Castro-Juiz, S.; Pereira, M. T.; Vila, J. M. J. Organomet. Chem. 2002,
ꢀ
ꢀ
ꢀ
655, 127. (b) Fernandez, A.; Pereira, E.; Fernandez, J. J.; Lopez-Torres, M.;
ꢀ
895.
Suarez, A.; Mosteiro, R.; Pereira, M. T.; Vila, J. M. New J. Chem. 2002, 26,
~ ꢀ
(9) (a) Vila, J. M.; Alberdi, G.; Pereira, M. T.; Marino, M.; Fernandez,
A.; Lopez Torres, M.; Ares, R. Polyhedron 2003, 22, 241. (b) Gomez-Blanco,
(4) (a) Pedersen, C. J. J. Am. Chem. Soc. 1967, 89, 2495. (b) Pedersen,
C. J. Science 1988, 241, 536. (c) Steed, J. W. Coord. Chem. Rev. 2001, 215,
171. (d) Xiaotian, Q.; Zaide, Z.; Minggui, X.; Yongchang, Z.; Ying, T.
Talanta 1998, 46, 45. (e) Rosa, D. T.; Young, V. G.; Coucouvanis, D. Inorg.
Chem. 1998, 37, 5042. (f) Dillon, R. E. A.; Stern, C. L.; Shriver, D. F. Solid
State Ionics 2000, 133, 247. (g) Yam, V. W. W.; Tang, R. P. L.; Wong,
K. M. C.; Lu, X. X.; Cheung, K. K.; Zhu, N. Chem.;Eur. J. 2002, 8, 4066.
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
N.; Fernandez, J. J.; Fernandez, A.; Fernandez, J. J.; Vazquez-García, D.; Lopez-
Torres, M.; Rodríguez, A.; Vila, J. M. Polyhedron 2009, 28, 3607.
ꢀ
ꢀ
(10) (a) Naya, L.; Vazquez-Garcı
ꢀ
´
a, D.; Fernandez, A.; Vila, J. M.;
ꢀ
Gomez-Blanco, N.; Fernandez, J. J. J. Organomet. Chem. 2008, 693, 685.
ꢀ
ꢀ
ꢀ
ꢀ
(b) Fernandez, A.; Vazquez-García, D.; Fernandez, J. J.; Lopez-Torres, M.;
ꢀ
ꢀ
ꢀ
Suarez, A.; Castro-Juiz, S.; Vila, J. M. Eur. J. Inorg. Chem. 2002, 2389.
(h) Breccia, P.; Van Gool, M.; Perez-Fernandez, R.; Martín-Santamaría, S.;
Gago, F.; Prados, P.; de Mendoza, J. J. Am. Chem. Soc. 2003, 125, 8270. (i)
Siu, P. K. M.; Lai, S. W.; Lu, W.; Zhu, N.; Che, C. M. Eur. J. Inorg. Chem.
2003, 2749. (j) Ohshita, J.; Uemura, T.; Inoue, T.; Hino, K.; Kunai, A.
Organometallics 2006, 25, 2225. (k) Liu, W.; Chen, Y.; Wang, R.; Zhou,
X. H.; Zuo, J. L.; You, X. Z. Organometallics 2008, 27, 2990. (l) Perekalin,
D. S.; Babak, M. V.; Novikov, V. V.; Petrovskii, P. V.; Lyssenko, K. A.;
Corsini, M.; Zanello, P.; Kudinov, A. R. Organometallics 2008, 27, 3654.
(m) Kelly, M. E.; Dietrich, A.; Gomez-Ruiz, S.; Kalinowski, B.; Kaluderovic,
G. N.; Muller, T.; Paschke, R.; Schmidt, J.; Steinborn, D.; Wagner, C.;
Schmidt, H. Organometallics 2008, 27, 4917.
ꢀ
ꢀ
ꢀ
ꢀ
(11) Fernandez, A.; Fernandez, J. J.; Lopez-Torres, M.; Suarez, A.;
Ortigueira, J. M.; Vila, J. M.; Adams, H. J. Organomet. Chem. 2000,
612, 85.
ꢀ
ꢀ
ꢀ
(12) Lopez-Torres, M.; Juanatey, P.; Fernanez, J. J.; Fernanez, A.;
ꢀ
Suarez, A.; Mosterio, R.; Ortigueira, J. M.; Vila, J. M. Organometallics
2002, 21, 3628.
(13) (a) Vila, J. M.; Gayoso, M.; Pereira, M. T.; Lopez Torres, M.;
ꢀ
ꢀ
Alonso, G.; Fernandez, J. J. J. Organomet. Chem. 1993, 445, 287. (b) Vila,
ꢀ
ꢀ
J. M.; Gayoso, M.; Pereira, M. T.; Lopez-Torres, M.; Fernandez, J. J.;
ꢀ
Fernandez, A. J. Organomet. Chem. 1996, 506, 165.

ꢀ
Fernandez et al.
388 Organometallics, Vol. 30, No. 3, 2011
Scheme 1a
a Conditions: (i) Pd(OAc)2, chloroform; (ii) NtBu4Cl, acetone/water; (iii) NtBu4Br, acetone/water; (iv) Tl(acac), acetone; (v) PPh3 (5a) or
P(p-MeOC6H4)3 (6a), dichloromethane (1:1 palladium/phosphine ratio).
double metalation could be achieved when the synthesis was
carried out in a nonacidic media.8a Thus, reaction of a with
palladium(II) acetate under mild conditions (dry chloroform
at 50 °C) gave 1a; a new doubly cyclometalated acetato-
bridged complex. Unfortunately, the very low solubility of
complex 1a precluded its full characterization, and this was
achieved by the complete analysis of its derivatives (vide
infra). Notwithstanding, the IR spectrum showed strong
bands assigned to the νas(COO) and νs(COO) stretching
vibrations at 1574s and 1411s cm-1, respectively, indicating
the presence of bridging acetate groups.10b,14 Whether 1a is
of dimeric or polymeric nature could not be unambiguously
established, contrary to other doubly cyclometalated com-
plexes derived from Schiff base ligands previously
reported;15 nevertheless, owing to its low solubility, we
(14) Nakamoto, K. IR and Raman Spectra of Inorganic and Coordi-
nation Compounds, 5th ed.; Wiley and Sons: New York, 1997.

Article
Organometallics, Vol. 30, No. 3, 2011 389
Scheme 2a
a Conditions: (i) dppm, acetone (2:1 palladium/dppm ratio); (ii) dppm (8a) or dppe (9a), acetone (1:1 palladium/phosphine ratio); (iii) dppb (10a),
dpppe (11a) or dpph (12a), dichloromethane (1:1 palladium/phosphine ratio).
tentatively propose the formulation depicted in Scheme 1,
i.e., as a polymeric arrangement.
Treatment of 1a with tetrabutylammonium chloride or
with tetrabutylammonium bromide produced the chloro- or
bromo-bridged complexes 2a and 3a, respectively, after
exchange of the acetate bridging groups by the correspond-
ing halide-bridging ligands. The bulky tetrabutylammonium
cation used in the metathesis reaction, as opposed to sodium
chloride, was chosen in order to prevent coordination of
the cation to the crown ether group.6 Compound 2a was

ꢀ
Fernandez et al.
390 Organometallics, Vol. 30, No. 3, 2011
insoluble in common organic solvents, but complex 3a was
sufficiently soluble in DMSO for characterization by NMR
spectroscopy. The 1H NMR spectrum showed a singlet
resonance at δ 7.92 assigned to the equivalent H3 and H6
protons, confirming double metalation at C2 and C5.
In order to more adequately characterize the complexes,
we prepared the very soluble dinuclear species 4a from
reaction of 2a with thallium acetylacetonate. The MS-FAB
spectra showed the corresponding peaks at m/z 1073 as-
signed to [M]þ after consideration of the palladium isotopes,
in accordance with the proposed structure.16 The 1H NMR
spectrum showed the characteristic signals corresponding to
the metalated ligand (two singlets at δ 8.18 and 7.60, with a
1:2 relative integration, were assigned to the HCdN and H3/
H6 proton resonances, respectively) as well as the resonances
at δ 5.36 and 2.09, 1.89, assigned to the CH proton and to the
two inequivalent C-Me groups of each acetylacetonate li-
gand, respectively. In the 13C{1H} NMR spectrum the most
noticeable feature was the high-frequency shift of the CdN,
C1/C4, and C2/C5 resonances (ca. δ 15, 13 and 20, re-
spectively), as compared to their value in the spectrum of
the free ligand; also assigned were the signals corresponding
to the coordinated acac ligands as singlets at δ 188.3 and
185.8 (CO), 100.3 (CH), and 28.1 and 27.5 (C-Me).
2.2. Reactivity with Monophosphines. Reaction of 2a with
the tertiary monophosphines PPh3 and P(p-OMeC6H4)3 in a
palladium atom/phosphine 1:1 molar ratio gave 5a and 6a,
dinuclear species after cleavage of the chloro-bridged bonds
and formation of two new Pd-P bonds per compound. The
MS-FAB spectra showed among others the peaks corre-
sponding to [M]þ, [M - Cl]þ, and [M - 2Cl]þ, indicating
a characteristic fragmentation pattern (see Experimental
Section).
Figure 1. Molecular structure of [Pd2{1,4-[C(H)dN{9,10-(C8-
H16O5)C6H3}]2C6H2-C2,C5,N,N0}(Cl)2(PPh3)2] (5a), with label-
ing scheme. Hydrogen atoms have been omitted for clarity.
The 1H NMR spectra showed the resonances assigned to
the HCdN and H3/H6 protons as doublets due to coupling
to the 31P nucleus [4JPH = 6.4 Hz for HCdN and 5.9 Hz for
H3/H6]. The H3/H6 resonances were shifted toward lower
frequency by more than 1 ppm, as compared to the parent
cyclometalated complexes, due to the shielding effect of the
phosphine phenyl groups. The HCdN proton resonance was
also high field shifted by ca. 1 ppm; this large shift has not
been observed in analogous mononuclear complexes9a,13a
and is probably due to the shielding effects of the phosphine
phenyl rings, which are close to the HCdN group as a result
of double metalation, in accordance with a N-Pd-P trans
geometry. The 31P{1H} NMR spectra showed a singlet
resonance for the two equivalent phosphorus nuclei; the
chemical shift values were also in agreement with a phos-
phorus trans to nitrogen geometry. In the 13C{1H} NMR
spectra the low-field shifts observed for CdN, C1/C4, and
C2/C5 were similar to those observed for 4a. The CdN and
the C2/C5 and C3/C6 resonances appeared as doublets at ca.
δ 174, 149, and 138, respectively, coupled to the phosphorus
nucleus.
are listed in Tables 1 and 2. The structure comprises a half-
molecule of [Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2-
C6H2-C2,C5,N,N0}(Cl)2(PPh3)2] (the dinuclear molecule is
generated by a crystallographic inversion center located in
the middle point of the phenyl ring) and a chloroform solvent
molecule per asymmetric unit.
The coordination sphere around each palladium atom
consists of a nitrogen atom of the imine group, an ortho
carbon atom of the phenyl ring, a chlorine atom, and a
phosphorus atom of a triphenylphosphine ligand. The sum
of angles at palladium is approximately 360°, with the more
noticeable distortion in the somewhat reduced ‘‘bite’’ angle
C(1)-Pd(1)-N(1) of 81.1(2)° consequent upon chelation.
The geometry around the palladium atom is slightly dis-
torted square-planar; the mean deviations from the least-
squares plane [Pd(1), C(1), N(1), P(1), Cl(1); plane 1] is
0.0152 A, and this is nearly coplanar with the metallacycle
[Pd(1), C(met), C(3), C(4), N(1); plane 2. rms 0.0477 A] and
with the metalated phenyl ring, rms 0.009 A (plane 3). Angles
between planes are as follows: 1/2: 4.9°; 2/3: 5°; 1/3: 8.6°.
The palladium-nitrogen bond length, 2.147(5) A, is longer
than the single bond predicted value of 2.011 A and reflects
the trans influence of the phosphorus atom. The palladium-
phosphorus bond distance, 2.266(2) A, is shorter than the
sum of the single-bond radii for palladium and phosphorus,
2.41 A, suggesting some partial double bond between
both atoms, and is similar to others reported earlier.17 The
palladium-chloro and palladium-carbon bond lengths,
2.356(1) and 2.001(6) A, respectively, are in agreement with
previous findings.8
Crystal and Molecular Structure of 5a. Suitable crystals
were grown by slowing evaporating a chloroform/hexane
solution. The labeling scheme is shown in Figure 1. Crystal-
lographic data and selected interatomic distances and angles
ꢀ
(15) (a) Cardenas, D. J.; Echavarren, A. M.; Ramırez de Areyano,
´
M. C. Organometalics 2001, 18, 3337. (b) Chakladar, S.; Paul, P.; Venkat-
subramanian, K.; Nag, K. J. Chem. Soc., Dalton Trans. 1991, 2669.
(16) (a) Tusek-Bozic, L.; Curic, M.; Traldi, P. Inorg. Chim. Acta 1997,
254, 49. (b) Tusek-Bozic, L.; Komac, M.; Curic, M.; Lycka, A.; Dalpaos, M.;
Scarcia, V.; Furlani, A. Polyhedron 2000, 19, 937.

Article
Organometallics, Vol. 30, No. 3, 2011 391
˚
Table 2. Selected Bond Distances (A) and angles (deg) for
Table 1. Crystal and Structure Refinement Data for 5a and 11a
5a and 11aa
5a 2CHCl3
3
11a (C2H5)2O
3
5a
11a
formula
Mr
C
74H74Cl8N2O10P2Pd2
C98H112Cl2N2O11P4Pd2
1709.69
293(2)
0.71073
monoclinic
P21/n
1901.48
293(2)
0.71073
triclinic
P1
Pd(1)-N(1)
2.147(5)
2.001(6)
2.266(2)
temperature (K)
wavelength (A)
cryst syst
space group
cell dimens
a (A)
b (A)
c (A)
R (deg)
β (deg)
Pd(1)-Cmet
2.012(3)
2.3407(7)
2.3240(7)
Pd(1)-P(1)
Pd(1)-P(2)
Pd(1)-P(3)
Pd(1)-Cl(1)
2.356(1)
2.4043(7)
2.015(3)
2.3580(8)
2.3274(8)
2.4042(8)
14.5712(2)
15.8518(1)
17.1185(2)
90
111.384(1)
90
3681.82(7)
2
1.542
13.0434(2)
15.7309(2)
23.6952(1)
88.143(1)
77.156(1)
76.207(1)
4602.46(9)
2
Pd(2)-C(4)
Pd(2)-P(3)
Pd(2)-P(4)
Pd(2)-Cl(2)
C(met)-Pd(1)-N(1)
C(met)-Pd(1)-P(1)
N(1)-Pd(1)-Cl(1)
P(1)-Pd(1)-Cl(1)
C(met)-Pd(1)-P(2)
P(2)-Pd(1)-Cl(1)
C(met2)-Pd(2)-P(4)
P(4)-Pd(2)-Cl(2)
C(met2)-Pd(2)-P(3)
P(3)-Pd(2)-Cl(2)
81.1(2)
γ (deg)
92.90(17)
92.20(13)
93.79(6)
90.25(7)
V (A3)
Z
Dcalc (Mg/m3)
1.372
0.578
88.67(7)
88.16(3)
89.02(7)
88.62(3)
89.61(7)
92.77(3)
μ (mm-1
)
0.881
0.30 ꢀ 0.25 ꢀ 0.20
cryst size (mm)
2θmax (deg)
indep reflns
S
R [F, I > 2σ(I)]
wR [F2, all data]
max F (e A3)
0.35 ꢀ 0.25 ꢀ 0.10
56.56
56.52
9075 (Rint = 0.0541)
1.052
0.0702
0.2059
1.547
22 500 (Rint = 0.0343)
1.063
0.0438
0.1050
0.831
a Symmetry transformations used to generate equivalent atoms: 5a:
#1-x, -yþ1, -z.
The 31P{1H} NMR spectra showed two doublets for the two
inequivalent phosphorus nuclei; the resonance at lower
frequency was assigned to the phosphorus trans to carbon.19
The 31P chemical shifts were clearly influenced by ring size;20
the four-membered ring in 8a gave a negative ΔR (-36.16),21
while the five-membered ring in 9a gave a positive ΔR
(þ16.3). In the 1H NMR spectra the H3/H6 resonances
appeared as a doublet of doublets, as a result of coupling to
both phosphorus nuclei [4J(Ptrans-CH) = 8.8 Hz, 4J(Ptrans-NH) =
5.4 Hz].
Treatment of 2a with 1,4-bis(diphenylphosphino)butane
(dppb), 1,5-bis(diphenylphosphino)pentane (dpppe), or 1,6-
bis(diphenylphosphino)hexane (dpph) in a 1:1 palladium/
diphosphine molar ratio gave 10a-12a. The conductivity
measurements carried out in dry acetonitrile showed the
complexes to be nonelectrolytes; this observation precluded
their formulation with the diphosphines as chelating ligands.
The 31P{1H} NMR spectra showed one singlet at δ 10.2
(10a), 12.3 (11a), and 13.1 (12a), in accordance with four
equivalent phosphorus atoms in each case, and, conse-
quently, the diphosphines must be acting as bridging ligands;
the low value of the chemical shifts were in agreement with a
trans P-Pd-P arrangement in the complexes.
Short contacts between the solvent CHCl3 hydrogen (H1s)
and the O(1) [C(1s)-H(1s), 0.98 A; O(1) H(1s), 2.69 A;
3 3 3
C(1s)-H(1s) O(1), 3.47(1) A, 137°], O(2) [O(2) H(1s),
3 3 3 3 3 3
3.17 A; C(1s)-H(1s) O(2), 3.94(2) A, 137°], O(3) [C(1s)-
3 3 3
H(1s),O(3) H(1s), 3.09 A; C(1s)-H(1s) O(3), 3.70(2) A,
3 3 3 3 3 3
121°], and O(5) [O(5) H(1s), 2.69 A; C(1s)-H(1s) O(1),
3 3 3
3 3 3
3.40(1) A, 129°] crown ether oxygen atoms were found.
2.3. Reactions with Diphosphines. Treatment of 2a with
bis(diphenylphosphino)methane (dppm) in a 2:1 palladium/
diphosphine molar ratio gave 7a.
The phosphorus resonance in the 31P{1H} NMR spec-
trum, ca. δ 33.7 (s, 4P), was downfield shifted from its value
in the free phosphine, suggesting coordination of both
phosphorus atoms to the metal center, in a trans to nitrogen
arrangement, indicating that the diphosphines were bridging
1
ligands between two cyclometalated fragments. In the H
NMR spectra a doublet at δ 5.78 was assigned to the H3/H6
protons, coupled to the phosphorus nuclei [4J(PH) = 6.4
Hz]. The FAB mass spectra showed peaks at m/z = 2587
assigned to the [M - 2Cl]þ fragment, which supports a
tetranuclear structure in which two doubly cyclometalated
ligands are linked by two bridging diphosphines, thus form-
ing a “counterhinged molecular box”, as has been described
before for related cyclometalated complexes.3i,8a This was
confirmed by the chemical shift shown by the H3/H6 reso-
nances, which appeared at δ 5.78, shielded not only by the
phosphine phenyl rings but also by the phenyl rings of the
neighboring cyclometalated ligand, cf. H3/H6 δ 7.98, a; and
H3/H6 δ 6.3, 5a (vide supra).
Treatment of 2a with bis(diphenylphosphino)methane
(dppm) or with 1,2-bis(diphenylphosphino)ethane (dppe),
in a 1:1 palladium/diphosphine molar ratio, gave dinuclear
cyclometalated compounds with two chelated phosphine
ligands, 8a and 9a, respectively, as 1:2 electrolytes, as shown
by molar conductivity measurements in dry acetonitrile.18
In the 1H NMR spectra the HCdN resonance appeared as
a singlet at ca. δ9 ppm (cf. δ 8.53 free ligand), evidencing the
absence of coupling to the 31P nuclei, in agreement with
Pd-N bond cleavage; this would allow free rotation along
the Cphenyl-Cimine bond. This assumption was confirmed by
the chemical shift of the CdN carbon in the 13C{1H} NMR
spectrum of 12a, which appeared at δ 159.2 ppm (cf. δ57.6
free ligand). Therefore, the Schiff base ligand is bonded to
the palladium atoms only through the phenyl carbon atoms.
The FAB mass spectra showed peaks at m/z = 1763 (10a,
[M - Cl]þ), 1827 (11a, [M]þ), and 1855 (12a, [M]þ), indicat-
ing a dinuclear formulation for the complexes (Scheme 2).
These data suggested a structure in which the two palladium
atoms were bridged by two mutually trans diphosphines
(18) Geary, W. J. Coord. Chem. Rev. 1971, 7, 81.
(19) (a) Pregosin, P. S.; Kuntz, R. W. In 31P and 13C NMR of
Transition Metal Phosphine Complexes; NMR Basic Principles and
Progress, Vol. 16; Diehl, P.; Fluck, E.; Kosfeld, R., Eds.; Springer:
Berlin, 1979. (b) K€uhl, O. Phosphorus-31 NMR Spectroscopy; Springer,
Berlin, 2008.
(20) Garrou, P. E. Chem. Rev. 1981, 81, 229.
(21) The difference with respect to an equivalent phosphorus in the
nonchelated analogue 5a, with a PPh3 trans to nitrogen δ 42.7.

ꢀ
Fernandez et al.
392 Organometallics, Vol. 30, No. 3, 2011
Figure 2. Molecular structure of [Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5}(Cl)2{μ-Ph2P(CH2)5PPh2}2] (11a), with
labeling scheme. Hydrogen atoms have been omitted for clarity.
and also by a bidentate [C,C] Schiff base ligand. This
structure resembles a “double-A frame” complex that has
been studied in some detail containing a bridging halide or
hydride, or one of a range of small molecules.22 In the present
case, the length between the palladium atoms is greater, due
to the presence of the phenyl group, which spans across both
metal centers.
the P(1)-Pd(1)-Cl(1) [93.69(3)°] and P(3)-Pd(2)-Cl(2)
[92.77(3)°] bond angles.
Consequent upon the spiral arrangement of the dpppe
ligands, the dihedral angle between the coordination planes
is 48.2°, and these form angles of 67.6° (plane 1) and 65.1°
(plane 2) with the metalated phenyl ring. The Pd-C [2.012(3)
and 2.015(3) A] and Pd-Cl [2.4042(8) and 2.4043(7) A] bond
distances are within the expected values.23 The Pd-P bond
lengths [2.3240(7)-2.3580(8) A] are longer than the Pd-P-
(trans to nitrogen) bond length but similar to the values
found in complex 13a (vide infra) and in other related
complexes.23,24 The metalated ring is planar (rms 0.0334)
(plane 3), but the geometry of the ligand is distorted by
the iminic carbon atoms (C7 and C14) above the plane
(deviations of 0.284 and 0.278 A, respectively). These devia-
tions give the ligand a butterfly wings configuration with the
phenyl rings with the crown ethers folded to the phenyl ring
22.7° and 27.9°.
Crystal Structure of 11a. Suitable crystals were grown by
slowing evaporating a chloroform/ether solution. The label-
ing scheme is shown in Figure 2. Crystallographic data and
selected interatomic distances and angles are listed in Ta-
bles 1 and 2. The structure comprises a molecule of [Pd2{1,4-
[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5}(Cl)2{μ-Ph2P-
(CH2)5P-Ph2}2] and one diethyl ether solvent molecule.
The molecule may be described as a dinuclear complex in
which each palladium atom is bonded to a carbon atom of
the phenyl ring, one chlorine atom, and two phosphorus
atoms from two different diphosphines that bridge across the
palladium atoms, which occupy mutually para positions of
the dimetalated phenyl ring; the distance between the palla-
dium atoms is 6.88 A. The spatial disposition adopted by the
CdN groups precluded any interaction with the palladium
atoms. The two diphosphine ligands are helicoidally twisted
around the Pd-Pd axis, and consequently, the molecule is
chiral. However the centrosymmetric nature of the space
group P1 indicates that both enantiomers are present in the
crystal.
Hence, the products resulting from the reaction of 2a with
the long-chain diphosphines, dppb, dpppe, and dpph, is
strongly influenced by two factors: the length of the alkyl
chain between the two phosphorus atoms and the relative
palladium atom/diphosphine molar ratio. Thus, three dif-
ferent products may be formulated (see Figure 3): (i) tetra-
nuclear complexes in which two diphosphine ligands are
bridging two different dicyclometalated moieties (structure
of type A); (ii) dinuclear complexes with chelating dipho-
sphine ligands (structure of type B); (iii) dinuclear com-
pounds in which the phosphine coordinates to two palladium
atoms bonded to the same ligand (structure of type C).
In order to clarify the influence of these factors on the
structural characteristics of the complexes, we carried out the
reaction of 2a with the diphosphines in different molar ratios
and followed the experiment by 31P{1H} NMR spectroscopy
(see Table 3).
The geometry around the palladium atoms is distorted
square-planar, with the larger distortion from planarity at
Pd(1) (coordination plane rms 0.1113 A, plane 1) than at
Pd(2) [plane 2; rms 0.0277 A]. The angles at palladium are
close to the ideal 90°, with the largest distortions, in the
absence of the strain due to the chelate ring, corresponding to
ꢀ
(22) (a) Clement, S.; Aly, S. M.; Bellows, D.; Fortin, D.; Strohmann,
C.; Guyard, L.; Abd-El-Aziz, A. S.; Knorr, M.; Harvey, P. D. Inorg.
Chem. 2009, 48, 4118. (b) Evrard, D.; Groison, K.; Decken, A.; Mugnier,
Y. P.; Harvey, D. Inorg. Chim. Acta 2006, 359, 2608. (c) Braun, T.; Steffen,
A.; Schorlemer, V.; Neumann, B.; Stammler, H. J. Chem. Soc., Dalton
Trans. 2005, 3331. (d) Stockland, R. A.; Janka, M.; Hoel, G. R.; Rath, N. P.;
Anderson, G. K. Organometallics 2001, 20, 5212. (e) Neve, F.; Ghedini, M.;
Tiripicchio, A.; Ugozzoli, F. Organometallics 1992, 11, 795–801. (f) Kubiak,
C. P.; Eisenberg, R. J. Am. Chem. Soc. 1977, 99, 6129.
(23) (a) Granell, J.; Sales, J.; Vilarrasa, J.; Declercq, J. P.; Germain,
G.; Miravitlles, C.; Solans, X. J. Chem. Soc., Dalton Trans. 1983, 2441.
(b) Takenaka, K.; Minakawa, M.; Uozumi, Y. J. Am. Chem. Soc. 2005, 127,
12273. (c) Albert, J.; Granell, J.; Moragas, R.; Sales, J.; Font-Bardia, M.;
Solans, X. J. Organomet. Chem. 1995, 494, 95.
(24) Granell, J.; Sainz, D.; Sales, J.; Solans, X.; Font-Altaba, M.
J. Chem. Soc., Dalton Trans. 1986, 1785.

Article
Organometallics, Vol. 30, No. 3, 2011 393
Figure 3. Possible products of the reactions between complex 2a and diphosphines Ph2P(CH2)nPPh2 (n = 1-6).
Table 3. Assignment of the 31P{1H} NMR Data for the Products (pure compounds or mixtures) of the Reactions between 2a and
Ph2P(CH2)nPPh2 (n = 1-6)
palladium/diphosphine molar ratio
diphosphine ligand
2:1
1:1
Ph2PCH2PPh2 (dppm)
Ph2P(CH2)2PPh2 (dppe)
A: 33.7s
[Mixture 1 A þ 2 B]
B: 6.54d, -28.60d
B: 59.00d, 42.20d
A: 63.50s
B: 59.00d, 42.20d
[Mixture 5 A þ 1 B þ 1 C]
A: 35.20s
B: 17.81d, -6.95d
C: 11.80s
Ph2P(CH2)3PPh2 (dppp)
Ph2P(CH2)4PPh2 (dppb)
[Mixture 1 A þ 2 B þ 1 C]
A: 35.20s
B: 17.81d, -6.95d
C: 11.80s
C: 10.20s
[Mixture 1 A þ 1 C]
A: 29.27s
C: 10.20s
Ph2P(CH2)5PPh2 (dpppe)
Ph2P(CH2)6PPh2 (dpph)
C: 12.30s
C: 13.10s
Ligand dppm showed a straightforward behavior; thus
reaction with 2a in a palladium/diphosphine 2:1 or 1:1 ratio
exclusively gave compounds 7a (type A) and 8a (type B),
respectively. With dppe a slightly more complicated beha-
vior was found; the reaction in a 2:1 molar ratio afforded a
mixture of complexes with the A and B structure; however
the reaction in a 1:1 ratio yielded only compound 9a, with a
type B structure, which was in accordance with the high
stability of five-membered chelate rings. Surprisingly, the
reaction between 2a and dppp, regardless of the relative
molar ratio used, gave a mixture that contained the three
type of complexes: A, B, and C (see Table 3).
In the case of dppb, a palladium/dppb 2:1 molar ratio gave
rise to complexes with the A and C structure; however when a
1:1 molar ratio was used, only compound 10a (type C
structure) was present in the solution. The products of the
reaction between 2a and the long-chain diphosphines dpppe
and dpph did not depend on the relative molar ratio used,
and only complexes with the type C structure (11a and 12a,
respectively) were detected in solution.
Two conclusions may be drawn from these observations.
On one hand, the tendency of diphosphines to act as inter-
molecularly bridging ligands or as chelating ligands increases
and decreases, respectively, with phosphine chain length;
very long chain diphosphines display intramolecular coordi-
nation. On the other hand, this behavior may be rationalized
in terms of the so-called “effective local concentration” and
steric factors. The “effective concentration” is a concept used
to explain the entropy role in the chelate effect, so once the
first phosphorus atom of the phosphine is bonded to the
palladium atom, the local concentration of the second
phosphorus in the neighborhood of the metal is greater when
the carbon chain is short, the coordination of the second
phosphorus is more likely, and the equilibrium constant is
greater. The steric factor refers to the unfavorable thermo-
dynamic effect due to the ring strain generated when large
chelate rings are formed.
3. Experimental Section
3.1. General Procedures. Solvents were purified by standard
methods.25 Chemicals were reagent grade and were purchased
from Aldrich and Acros. Microanalyses were carried out using a
Carlo Erba elemental analyzer, model 1108. IR spectra were
recorded KBr discs on a Perkin-Elmer 1330. NMR spectra were
obtained as CDCl3 or CD3SOCD3 solutions and referenced to
SiMe4 (1H, 13C{1H}) or 85% H3PO4 31P{1H}) and were re-
corded on a Bruker AC-200F spectrometer. All chemical shifts
were reported downfield from standards. The FAB mass spectra
were recorded using a Quatro mass spectrometer with a Cs ion
gun; 3-nitrobenzyl alcohol (3-NBA) was used as the matrix.
3.2. Synthesis of the Ligand and Complexes. 1,4-[C(H)dN-
{9,10-(C8H16O5)C6H3}]2C6H4 (a). 1,4-(COH)2C6H4 (0.30 g,
2.20 mmol) and NH2[9,10-(C8H16O5)]C6H3 (1.28 g, 4.50 mmol)
were added to 20 cm3 of dry chloroform. The mixture was heated
under reflux in a Dean-Stark apparatus for 12 h. After cooling
to room temperature, the solvent was evaporated to give a
yellow solid. Yield: 95%. Anal. Found: C, 64.9; H, 6.8; N, 4.2.
C36H44N2O10 requires C, 65.0; H, 6.7; N, 4.2. IR: ν(CdN), 1616
m cm-1. 1H NMR (200 MHz, CDCl3, δ ppm, J Hz): 8.53 [s, 2H,
Hi]; 7.98 [s, 4H, H2/H3/H5/H6]; 6.92 [d, 2H, H11, 3J(H11H12)
= 8.3]; 6.90 [d, 2H, H8, 4J(H8H12) = 2.0]; 6.86 [dd, 2H, H12].
13C{1H} NMR (50.28 MHz, CDCl3, δ ppm): 157.6 (CdN); 138.5
(C1, C4); 128.9 (C2, C3, C5, C6); 149.6, 148.1, 145.4 (C7, C9, C10);
114.4, 113.1, 107.9 (C8, C11, C12). FAB-MS: m/z = 663 [M]þ.
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,
N0}(μ-O2CMe)2]n (1a). A pressure tube containing 1,4-[C-
(H)dN{9,10-(C8H16O5)C6H3}]2C6H4 (a) (0.15 g, 0.22 mmol),
(25) Armarego, W. L. F.; Chai, C. L. L. Purification of Laboratory
Chemicals, 5th ed.; Butterworth-Heinemann: Bodmin, 2003.

ꢀ
Fernandez et al.
394 Organometallics, Vol. 30, No. 3, 2011
palladium(II) acetate (0.10 g, 0.44 mmol), and 10 cm3 of dry
chloroform was sealed under argon. The resulting mixture was
heated at 50 °C for 96 h. After cooling to room temperature the
solution was filtered through Celite to remove the black
palladium formed. The solvent was removed under vacuum,
and the precipitate formed was recrystallized from acetone,
filtered off, washed with acetone and diethyl ether, and dried
under vacuum togive complex1a as a red solid. Yield: 77%. Anal.
Found: C, 50.0; H, 4.9; N, 2.8. C40H48N2O12Pd2 requires: C, 49.9;
H, 5.0; N, 2.9. IR: ν(CdN), oc.; νas(COO), 1574s cm-1; νs(COO),
Compound 6a was synthesized following a similar procedure
to that for 5a as a yellow solid but using P(p-OMeC6H4)3.
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,
N0}(Cl)2{P(p-OMe-C6H4)3}2] (6a). Yield: 58%. Anal. Found:
C, 56.4; H, 5.5; N, 1.8. C78H90N2O16P2Cl2Pd2 requires: C,
56.5; H, 5.4; N, 1.7. IR: ν(CdN), 1593s cm-1. 1H NMR (200
4
MHz, CDCl3, δ ppm, J Hz): 7.35 [d, 2H, Hi, J(PHi)= 6.4];
7.06 [d, 2H, H8, 4J(H8H12) = 2.4]; 6.77 [d, 2H, H11,
3J(H11H12) = 8.8]; 6.69 [dd, 2H, H12]; 6.31 [d, 2H, H3/H6,
4J(PH3) = 5.9]. P-phenyl: δ(p-MeO-C6H4)3P; 7,63 [dd, 1H,
Ho, 3J(HoHm) = 8.8, 3J(PHo) = 11,2]; 6.88 [dd, 1H, Hm,
4J(PHm) = 1.5]; 3.81 [s, 3H, (p-MeO-C6H4)3P]. 13C{1H} NMR
(50.28 MHz, CDCl3, δ ppm): 174.5 [d, CdN, 3JPC = 2.1 Hz];
152.6 (C1, C4); 149.3 [d, C2, C5, 2J(PC2) = 3.5]; 148.4, 148.2,
143.4 (C7, C9, C10); 138.1 [d, C3, C6, 2J(PC3) = 9.9]; 115.3,
113.3, 111.7 (C8, C11, C12); P-phenyl: 136.9 [d, Co, 2JPCo =
12.8 Hz]; 113.6 [d, Cm, 3JPCm = 12.1]; 161.5 [d, Cp, 4JPCp =
2.8]; 122.3 [d, Ci, 1JPCi = 57.5]. 31P{1H} NMR (80.96 MHz,
CDCl3, δ ppm): 38.9s. FAB-MS: m/z = 1653 [M]þ; 1615 [M -
Cl]þ; 1580 [M - 2Cl]þ; 1263 [M - Cl - phosphine]þ; 1227
[M - 2Cl - phosphine]þ; 1121 [M - 2Cl - phosphine - Pd]þ.
[{Pd2[1,4-{C(H)dN[9,10-(C8H16O5)C6H3]}2C6H2-C2,C5,N,
N0](Cl)2}2(μ-Ph2PCH2P-Ph2)2] (7a). PPh2(CH2)PPh2 (6.2 mg,
0.016 mmol) was added to a suspension of 2a (30 mg, 0.016
mmol) in acetone (5 cm3). The mixture was stirred for 12 h, and
the orange complex precipitated, was filtered off, and was dried
in vacuo. Yield: 93%. Anal. Found: C, 54.9; H, 4.8; N, 1.9.
1411s cm-1
.
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,
N0}(μ-Cl)2]n (2a). A solution of 1a (0.15 g, 0.08 mmol) in
acetone (10 cm3) was treated with a saturated solution of
NtBu4Cl in ca. 20 cm3 of water. The red precipitate formed
was filtered off, washed with water, and dried under vacuum.
Yield: 92%. Anal. Found: C, 45.4; H, 4.6; N, 3.0. C36H42N2-
O10Pd2Cl2 requires: C, 45.6; H, 4.4; N, 3.0. IR: ν(CdN),
1599 m cm-1
.
Compound 3a was synthesized as a dark orange solid follow-
ing a similar procedure to that for 2a but using NtBu4Br.
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,
N0}(μ-Br)2]n (3a). Yield: 85%. Anal. Found: C, 41.5; H, 4.1; N,
2.7. C36H42N2O12Br2Pd2 requires: C, 41.8; H, 4.0; N, 2.7. IR:
ν(CdN), 1599 m cm-1 1H NMR (200 MHz, DMSO-d6,
.
δ ppm, J Hz): 8.38 [s, 2H, Hi]; 7.92 [s, 2H, H3/H6]; 6.90 [m,
6H, H8, H11, H12].
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,
C
124H132N4O20P4Cl4Pd41requires: C, 55.3; H, 4.9; N, 2.1. IR:
ν(CdN), 1586 m cm-1. H NMR (200 MHz, CDCl3, δ ppm,
N0}{MeC(O)CHC(O)Me-O,O0}2]
(4a).
Acetilacetonate
4
J Hz): 7.06 [d, 2H, H8, J(H8H12) = 2.4]; 6.85 [d, 2H, H11,
thallium(I) (9.7 mg, 0.032 mmol) was added to a suspension
of 2a (30 mg, 0.016 mmol) in acetone (5 cm3). The mixture was
stirred for 24 h. The solution was filtered through Celite to
eliminate the TlCl precipitate, and then the solvent was
removed to give an orange solid, which was recrystallized
from dichloromethane/hexane, filtered off, and dried in vacuo.
3J(H11H12) = 8.8]; 6.63 [dd, 2H, H12]; 5.78 [d, 2H, H3/H6,
4J(PH3) = 6.4]; 4.98 [t, 2H, PCH2P, 2J(PH) = 13.2]. 31P{1H}
NMR (80.96 MHz, CDCl3, δ ppm): 33.7s. FAB-MS: m/z =
2587 [M - 2Cl]þ; 2064 [M - 3Cl - phosphine - Pd]þ; 1295
[(L-2H)Pd2Cl2phosphine]þ; 1153 [(L-2H)PdClphosphine]þ.
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,
N0}(Ph2PCH2Ph2-P,P0)2][Cl]2 (8a). Ph2PCH2PPh2 (dppm, 24
mg, 0.032 mmol) was added to a suspension of 2a (30 mg, 0.016
mmol) in acetone (5 cm3). The mixture was stirred for 24 h, and
the orange solid was precipitated out by addition of water,
filtered off, and dried in vacuo. Yield: 86%. Anal. Found: C,
61.1; H, 5.3; N, 1.5. C92H98N2O10P4Cl2Pd2 requires: C, 61.4;
Yield: 75%. Anal. Found: C, 51.5; H, 5.3; N, 2.6. C46H58
-
N2O14Pd2 requires: C, 51.4; H, 5.4; N, 2.6. IR: ν(CdN),
1600sh, m cm-1; ν(C-O), 1577s, 1395s cm-1; ν(C-C),
1509s, 1264s cm-1 1H NMR (200 MHz, CDCl3, δ ppm,
.
J Hz): 8.18 [s, 2H, Hi]; 7.60 [s, 2H, H3/H6]; 7.16 [d, 2H, H8,
4J(H8H12) = 2.4]; 6.87 [d, 2H, H11, 3J(H11H12) = 8.8]; 6.95
[dd, 2H, H12]; 5.36 [s, 2H, Hacac]; 2.09 [s, 6H, Meacac]; 1.89
[s, 6H, Meacac]. 13C{1H} NMR (50.28 MHz, CDCl3, δ ppm):
188.3, 185.8 (MeCOCHCOMe); 173.3 (CdN); 151.8 (C1, C4);
148.9 (C2, C5); 148.6, 147.1, 141.9 (C7, C9, C10); 129.5
(C3, C6); 114.4, 113.2, 110.6 (C8, C11, C12); 100.3
(MeCOCHCOMe); 28.1, 27.5 (MeCOCHCOMe). FAB-MS:
m/z = 1073 [M]þ; 975 [M - (acac)]þ.
1
H, 5.4; N, 1.6. IR: ν(CdN), 1584sh,w cm-1. H NMR (200
4
MHz, CDCl3, δ ppm, J Hz): 6.46 [d, 2H, H8, J(H8H12) =
4
2.4]; 6.33 [dd, 2H, H3/H6, J(PH3) = 8.8, 5.4]; 5.93 [t, 4H,
PCH2P, 2J(PH) = 6.3]. 31P{1H} NMR (80.96 MHz, CDCl3, δ
ppm): 6.54d, -28.60d, 3J(PP) = 16.94. FAB-MS: m/z = 1643
[M]þ; 1294 [M - phosphine]þ; 1153 [M - Cl - phosphine -
Pd]þ.
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,
N0}(Cl)2(PPh3)2] (5a). PPh3 (8.4 mg, 0.032 mmol) was added to
a suspension of 2a (30 mg, 0.016 mmol) in dicloromethane
(5 cm3). The mixture was stirred for 24 h, and the orange
complex precipitated out by addition of hexane, filtered off,
washed with diethyl ether, and dried in vacuo. Yield: 60%.
Anal. Found: C, 58.6; H, 4.8; N, 1.7. C72H72N2O10P2Cl2Pd2
requires: C, 58.8; H, 4.9; N, 1.9. IR: ν(CdN), 1589 m cm-1. 1H
NMR (200 MHz, CDCl3, δ ppm, J Hz): 7.30 [d, 2H, Hi,
Compound 9a was synthesized as a yellow solid following a
similar procedure to that for 8a but using Ph2P(CH2)2PPh2
(dppe).
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5,N,
N0}{Ph2P(CH2)2PPh2-P,P0}2][Cl]2 (9a). Yield: 92%. Anal.
Found: C, 62.2; H, 5.5; N, 1.7. C90H94N2O10P4Cl2Pd2 re-
quires: C, 62.0; H, 5.4; N, 1.6. IR: ν(CdN), 1586 m cm-1. 1H
NMR (200 MHz, CDCl3, δ ppm, J Hz): 6.31 [d, 2H, H11,
4
3J(H11H12) = 8.8]; 6.22 [d, 2H, H8, J(H8H12) = 2.4]; 6.12
4
4J(PHi)= 6.4]; 7.05 [d, 2H, H8, J(H8H12) = 2.4]; 6.76 [d,
4
[dd, 2H, H3, H6, J(PH3) = 8.8, 5.4]; 2.30 [m, 8H, PCH2].
2H, H11, 3J(H11H12) = 8.8]; 6.65 [dd, 2H, H12]; 6.30 [d, 2H,
H3/H6, 4J(PH3)= 5.9]. 13C{1H} NMR (50.28 MHz, CDCl3, δ
ppm): 174.0 [d, CdN, 3JPC = 1.4 Hz]; 152.9 (C1, C4); 149.1
(C2, C5); 138.1br (C3, C6); 148.2, 147.9, 143.3 (C7, C9, C10);
115.0, 113.1, 111.7 (C8, C11, C12); P-phenyl: 135.3 [d, Co,
2JPC0 = 11.4 Hz]; 128.1 [d, Cm, 3JPCm = 10.6]; 130.7 [br, Cp];
130.9 [d, Ci, 1JPCi = 49.0]. 31P{1H} NMR (80.96 MHz,
CDCl3, δ ppm): 42.7s. FAB-MS: m/z = 1470 [M]þ; 1436
[M - Cl]þ; 1400 [M - 2Cl]þ; 1173 [M - Cl - phosphine]þ;
1137 [M - 2Cl - phosphine]þ; 1031 [M - 2Cl - phosphine -
Pd]þ; 766 [(L - 2H)Pd]þ.
31P{1H} NMR (80.96 MHz, CDCl3, δ ppm): 59.0d, 42.2d,
3J(PP) = 25.1. FAB-MS: m/z = 1672 [M]þ; 1707 [M][Cl]þ;
1274 [M - phosphine][Cl]þ; 1167 [M - phosphine - Pd]þ;
836 [M]þ2
.
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5}-
(Cl)2{μ-Ph2P(CH2)4PPh2}2] (10a). PPh2(CH2)4PPh2 (dppb,
27 mg, 0.064 mmol) was added to a suspension of 2a (30 mg,
0.016 mmol) in dicloromethane (5 cm3). The mixture
was stirred for 24 h, and the orange complex was preci-
pitated out by addition of hexane, filtered off, and dried
in vacuo. Yield: 40%. Anal. Found: C, 61.1; H, 5.3; N, 1.5.

Article
Organometallics, Vol. 30, No. 3, 2011 395
C92H98N2O10P4Cl2Pd2 requires: C, 61.4; H, 5.4; N, 1.6. IR:
ν(CdN), 1609 m cm-1. 1H NMR (200 MHz, CDCl3, δ ppm,
J Hz): 9.01 [s, 2H, Hi]. 31P{1H} NMR (80.96 MHz, CDCl3,
δ ppm): 10.2s. FAB-MS: m/z = 1763 [M - Cl]þ; 1337 [M - Cl -
phosphine]þ; 1301 [M - 2Cl - phosphine]þ; 1195 [M - 2Cl -
phosphine - Pd]þ.
Compound 11a was synthesized as a yellow solid, following a
similar procedure to that for 10a, but using Ph2P(CH2)5PPh2
(dpppe).
C4); 148.8 (C2, C5); 139.9 [br, C3, C6]; 147.9, 144.2, 143.7 (C7,
C9, C10); 114.5, 111.3, 111 (C8, C11, C12). FAB-MS: m/z =
1855 [M]þ; 1820 [M - Cl]þ; 1386 [M - Cl - phosphine]þ; 1257
[M - Cl - phosphine - Pd]þ.
3.3. X-ray Crystallographic Study. Three-dimensional, room-
temperature X-ray data were collected on a Bruker Smart 1k CCD
diffractometer using graphite-monochromated Mo KR radiation.
All the measured reflections were corrected for Lorentz and
polarization effects and for absorption by semiempirical methods
based on symmetry-equivalent and repeated reflections. The
structures were solved by direct methods and refined by full matrix
least-squares on F2. Hydrogen atoms were included in calculated
positions and refined in riding mode.
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5}-
(Cl)2{μ-Ph2P(CH2)5PPh2}2] (11a). Yield: 69%. Anal. Found: C,
61.5; H, 5.8; N, 1.7. C94H102N2O10P4Cl2Pd2 requires: C, 61.8; H,
1
5.6; N, 1.5. IR: ν(CdN), 1607w cm-1. H NMR (200 MHz,
CDCl3, δ ppm, J Hz): 9.17s [s, 2H, Hi]; 7.00 [dd, 2H, H12,
4J(H8H12) = 2.4]; 6.88 [d, 2H, H11, 3J(H11H12) = 8.8].
31P{1H} NMR (80.96 MHz, CDCl3, δ ppm): 12.3s. FAB-MS:
m/z = 1827 [M]þ; 1792 [M - Cl]þ; 1350 [M - Cl - phosphine]þ;
1243[M - Cl- phosphine - Pd]þ;1209[M- 2Cl - phosphine-
Pd]þ.
In general, the atoms corresponding to the crown ether chain
showed less than ideal ellipsoids, indicating a possible disorder
problem. C(13), C(14), C(15), C(16), O(2), and O(3) atoms in the
crystal of 5a also showed large ellipsoids; however, the models
used to take into account of this disorder did not improve
appreciably the final results.
Compound 12a was synthesized as an orange solid, following
a similar procedure to that for 10a, but using Ph2P(CH2)6PPh2
(dpph).
The structure solution and refinement were carried out using
the program package SHELX-97.26
[Pd2{1,4-[C(H)dN{9,10-(C8H16O5)C6H3}]2C6H2-C2,C5}-
(Cl)2{μ-Ph2P(CH2)6P-Ph2}2] (12a). Yield: 62%. Anal. Found:
C, 61.6; H, 5.7; N, 1.4. C96H106N2O10P4Cl2Pd2 requires: C, 62.1;
H, 5.7; N, 1.5. IR: ν(CdN), 1608w cm-1. 1H NMR (200 MHz,
CDCl3, δ ppm, J Hz): 8.93 [s, 2H, Hi]; 6.90 [dd, 2H, H12,
4J(H8H12) = 2.4]; 6.83 [d, 2H, H11, 3J(H11H12) = 8.8].
31P{1H} NMR (80.96 MHz, CDCl3, δ ppm): 13.1s. 13C{1H}
NMR (50.28 MHz, CDCl3, δ ppm): 159.2 (CdN); 149.6 (C1,
Acknowledgment. We thank the Xunta de Galicia
(Project INCITE 10PXIB209226PR; and Grupos Con-
solidados PGIDIT04PXI10301IF and INCITE07PXI1-
03083ES) for financial support.
Supporting Information Available: X-ray crystallographic data
and tables giving atomic coordinates, displacement parameters,
and bond distances and angles for 5a, 11a, and 13a [CCDC no.
789476 (5a), 789477 (11a)]. This material is available free of
charge via the Internet at http://pubs.acs.org.
(26) Sheldrick, G. M. A short history of SHELX. Acta Crystallogr.
2008, A64, 112–122.