Functionalized palladacycles with crown ether rings derived from terdentate [ C, N, N ] ligands. crystal and molecular structure of the dinuclear palladium/silver complex [Pd{3,4-(AgC10H20O 6)C6H2C(Me

Article abstract of DOI:10.1021/om1007902

Reaction of 3,4-(C₁₀H₂₀O₆)C ₆H₃C(Me)=NN(H)[3′-(CF₃)C ₄H₂N₂] (a) and 3,4-(C₁₀H ₂₀O₆)C₆H₃C(Me)=NN(H)(4′

Full text of DOI:10.1021/om1007902

396 Organometallics 2011, 30, 396–404
DOI: 10.1021/om1007902
Functionalized Palladacycles with Crown Ether Rings Derived from
Terdentate [C,N,N] Ligands. Crystal and Molecular Structure of the
Dinuclear Palladium/Silver Complex
[Pd{3,4-(AgC10H20O6)C6H2C(Me)dNN(H)
(40-ClC4H2N2)}(PPh3)][CF3SO3]2
†
Digna Vazquez-Garcıa, Alberto Fernandez,* Margarita Lopez-Torres,
,†
†
ꢀ
ꢀ
ꢀ
Antonio Rodrıguez, Alexis Varela, M. Teresa Pereira, 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 13, 2010
Reaction of 3,4-(C10H20O6)C6H3C(Me)dNN(H)[30-(CF3)C4H2N2] (a) and 3,4-(C10H20O6)C6H3-
C(Me)dNN(H)(40-ClC4H2N2) (b) with Li2[PdCl4] and sodium acetate in methanol at room
temperature yielded the mononuclear cyclometalated complexes [Pd{3,4-(C10H20O6)C6H2C(Me)d
NN(H)[30-(CF3)C4H2N2]}(Cl)] (1a) and Pd{3,4-(C10H20O6)C6H2C(Me)dNN(H)(40-ClC4H2N2)}-
(Cl)] (1b), respectively, with the ligand as terdentate [C,N,N]. The reaction of 1a and 1b with silver
trifluoromethanesulfonate and triphenylphosphine yielded [Pd{3,4-(C10H20O6)C6H2C(Me)d
NN(H)[30-(CF3)C4H2N2]}(PPh3)][CF3SO3] (2a) and [Pd{3,4-(C10H20O6)C6H2C(Me)dNN(H)(40-
ClC4H2N2)}(PPh3)][CF3SO3] (2b) with the phosphine ligand occupying the vacant coordination
position after chlorine abstraction; these were deprotonated at the hydrazine nitrogen after treatment
with sodium acetate, yielding the [Pd{3,4-(C10H20O6)C6H2C(Me)dNN[30-(CF3)C4H2N2]}(PPh3)]
(3a) and [Pd{3,4-(C10H20O6)C6H2C(Me)dNN(40-ClC4H2N2)}(PPh3)] (3b). Further treatment of 2b
with silver trifluoromethanesulfonate gave 5b. Reaction of 2a and 2b with a Ag(I) salt and the tertiary
diphosphine Ph2P(CH2)4PPh2 (dppb) in 2:1 molar ratio gave the dinuclear complexes [{Pd{3,
4-(C10H20O6)C6H2C(Me)dNN(H)[30-(CF3)C4H2N2]}}2(μ-PPh2(CH2)4PPh2)][CF3SO3]2 (4a) and [{Pd[3,
4-(C10H20O6)C6H2C(Me)dNN(H)(40-ClC4H2N2)]}2((μ-PPh2(CH2)4P-Ph2)][CF3SO3]2 (4b) with the
diphosphine as a bridging ligand. The crystal structures of complexes 1a and 5b are described, the
latter crystallized with a Ag(I) atom complexed to the crown ether ring putting forward the ability of
the complex to act as a metaloligand.
1. Introduction
size, the conformation of the ether ring, or the solvent;
consequently, it is possible to tailor-make different types of
ligands for specific uses.1 This has potential applications
such as the production of sensors, the selective extraction of
cations, the ionic transport in membranes, the preparation of
photochemical controlled and electrochemical active recep-
tors, or compounds with promising anticancer properties.2
On the other hand, cyclometalated complexes exhibit a good
number of applications which range from the synthesis of
new organic and organometallic compounds to mesogenic
species and catalytic materials3 as well as promoting unusual
coordination environments.4 Consequently, the combined
structural characteristics of both species could result in the
preparation of new metaloligands: compounds with poten-
tial coordination sites possessing a metal center in their
structure, which should display interesting structural char-
acteristics and promising applications.5 In the past, we have
studied the cyclometalation of tridentate [C,N,N],6 [C,N,
O],7,8 and [C,N,S]9-11 ligands, which yield mononuclear
compounds in the former case, and tetranuclear species
in the latter two, and more recently we have reported the
The ability of crown ethers to form complexes selectively
with ions such as alkaline metal and alkaline-earth metal
cations is a well-known property which depends on several
structural characteristics as, for example, the different cavity
*To whom correspondence should be addressed. For J.M.V.: phone,
34-981-563100 ext 14255; fax, þ34/981-597525; E-mail, josemanuel.
vila@usc.es. For A.F.: fax, þ34/981-167065; E-mail, qiluaafl@udc.es. .
(1) (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-
pounds; Academic Press: London, 1978. (e) Vogtle, F., Weber, E., Eds.;
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.
r
pubs.acs.org/Organometallics
Published on Web 01/10/2011
2011 American Chemical Society

Article
Organometallics, Vol. 30, No. 3, 2011 397
synthesis of new cyclometalated complexes bearing crown
ether rings, derived from Schiff base ligands, whose coordi-
nating abilities were determined not only by the character-
istics of the crown ether cavity but also by the different
structure, planar or folded, adopted by the cyclometalated
fragments. Thus, the geometry constraints imposed by the
presence of the metalated rings modify and enhance in a
synergic manner the coordinating characteristics of the cyclic
crown ether.12 Although Ryabov had reported the first
cyclopalladated compound with a crown-ether fragment,13
similar moieties bearing transition metals in the crown ether
ring were still outstanding, so we reasoned that as in some
respects, from its cation radius, Ag(I) is between the two
alkali cations Na(I) and K(I)14 so the Ag(I) chemical proper-
ties resemble Na(I) and K(I), and the investigation of the
interaction of silver(I) ions with the crown ether pallada-
cycles should be a coherent extension of our research, albeit
because Ag(I) is too large to fit into the cavity of 15-crown-5
rings and thus sandwiched structures are expected to form, it
is about right for the cavity of the 18-crown-6 ones, so only
complexes bearing the latter ring should be considered.
Therefore, here we report the synthesis of new families of
mono- di-, tri-, or tretranuclear metaloligands with planar,
bent, or pseudocubic arrangements derived from pyridazine,
pyrimidine, phenol, or thiosemicarbazone ligands, which are
functionalized with crown ether rings. Attempts to prove
their proficiency as metaloligands has met with success by
the resolution of the molecular structure of the complex
where the Ag(I) cation is located in the crown ether cavity.
(2) (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.
2. Results and Discussion
Synthesis of the Cyclometalated Complexes. The com-
pounds and reactions are shown in Scheme 1. The com-
pounds described in this paper were characterized by
ꢀ
ꢀ
(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.
1
elemental analysis (C, H, N) and by IR and H, 31P-{1H}
NMR, and 13C-{1H} NMR spectroscopy, FAB and ESI
mass spectrometry, and X-ray single crystal diffraction
(data in the Experimental Section).
The reaction of a and b with Li2[PdCl4] and sodium acetate
in methanol at room temperature yielded the cyclometalated
complexes 1a and 1b, respectively. The IR spectra showed
the ν(CdN) stretch shifted to lower wavenumbers due to the
coordination of the imine nitrogen.15,16 The complexes were
insoluble in most organic solvents and only slightly soluble in
DMSO-d6. The 1H NMR spectra showed absence of the H6
resonance as a consequence of metalation at the Pd-C6
carbon. In the IR spectra, the presence of strong bands
assigned to the ν(N-H) stretch suggested that the hydrazine
group was not deprotonated, thus rendering nonelectrolyte
moieties as shown by conductivity measurements in dry
dimethylformamide. The mass spectra showed a cluster of
peaks corresponding to the molecular ion (1b, 645 amu) and
to the fragment resulting from the loss of the chlorine ligand
(1a, 619 amu). The X-ray analysis of 1a confirmed the pro-
posed structure (see below).
(3) (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, M. S.; Y. 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.;
ꢀ
ꢀ
ꢀ
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.
Moreover, in DMSO-d6, the 1H NMR spectra of 1a and 1b
did not show the NH proton resonance. We suggest this may
be attributed to substitution of the chlorine ligand by a
solvent DMSO-d6 molecule with subsequent deprotonation
of the hydrazine group to preserve the neutrality of the
complex, putting forward that this is probably the species
present in solution. A similar behavior has been previously
reported by us.6
Crystal and Molecular Structure of 1a. Suitable crystals of
1a were grown from slow evaporation of an acetonitrile/
methanol solution. The molecular structure is illustrated in
Figure 1. Crystal data are given in Table 1, and selected bond
distances and angles, with estimated standard deviations, are
shown in Table 2.
ꢀ
(4) Vila, J. M.; Pereira, M. T.; Ortigueira, J. M.; Fernandez, J. J.;
ꢀ
ꢀ
Fernandez, A.; Lopez-Torres, M.; Adams, H. Organometallics 1999, 18,
5484.
(5) Arias, J.; Bardajı, M.; Espinet, P. J. Organomet. Chem. 2006, 691,
4990.
ꢀ
ꢀ
ꢀ
ꢀ
(6) Fernandez, J. J.; Fernandez, A.; Lopez-Torres, M.; Vazquez-
Garcıa, D.; Rodrıguez, A.; Varela, A.; Vila, J. M. J. Organomet. Chem.
2009, 694, 2234.
(7) Fernandez, J. J.; Fernandez, A.; Vazquez-Garcia, D.; Lopez-
Torres, M.; Suarez, A.; Gomez-Blanco, N.; Vila, J. M. Eur. J. Inorg.
Chem. 2007, 5408.
ꢀ
ꢀ
ꢀ
ꢀ
(8) Gomez-Blanco, N.; Fernandez, J. J.; Fernandez, A.; Vazquez-
ꢀ
Garcıa, D.; Lopez-Torres, M.; Vila, J. M. Eur. J. Inorg. Chem. 2009,
3071.
~
(9) Vila, J. M.; Pereira, M. T.; Ortigueira, J. M.; Grana, M.; Lata, D.;
Suarez, A.; Fernandez, J. J.; Fernandez, A.; Lopez-Torres, M.; Adams,
ꢀ
ꢀ
ꢀ
ꢀ
H. J. Chem. Soc., Dalton Trans. 1999, 4193.
(10) Amoedo, A.; Adrio, L.; Antelo, J. M.; Martınez, J.; Pereira,
ꢀ
M. T.; Fernandez, A.; Vila, J. M. Eur. J. Inorg. Chem. 2006, 3016.
The asymmetric unit contains one molecule of the complex
and two acetonitrile and one methanol solvent molecules.
The structure consists of discrete molecules in which the
ꢀ
(11) Adrio, L.; Antelo, J. M.; Fernandez, J. J.; Hii, K. K.; Pereira,
M. T.; Vila, J. M. J. Organomet. Chem. 2009, 694, 747.
ꢀ
(12) Castro-Juiz, S.; Fernandez, A.; Lopez-Torres, M.; Vazquez-
Garcıa, D.; Suarez, A.; Vila, J. M.; Fernandez, J. J. Organometallics
ꢀ
ꢀ
ꢀ
ꢀ
2009, 28, 6657.
(13) Bezsoudnova, E. Y.; Ryabov, A. D. J. Organomet. Chem. 2001,
622, 38.
(14) Wang, Q. M.; Mak, T. C. W. Chem.;Eur. J. 2003, 9, 43.
(15) Onoue, H.; Moritani, I. J. Organomet. Chem. 1972, 43, 431.
(16) Onoue, H.; Minami, K.; Nakagawa, K. Bull. Chem. Soc. Jpn.
1970, 43, 3480.

ꢀ ´
Vazquez-Garcıa et al.
398 Organometallics, Vol. 30, No. 3, 2011
Scheme 1a
a (i) Li2PdCl4, (methanol, NaOAc); (ii) (1) AgCF3SO3, (2) PPh3 (acetone, 1:1 molar ratio); (iii) NaOAc (MeOH); (iv) (1) 4a AgCF3SO3, 4b AgClO4; 2:
dppb (acetone, 2:1 molar ratio); (v) AgCF3SO3 (EtOH).
palladium atom is bonded in a slightly distorted square-
planar geometry to the C(6) carbon atom of the phenyl ring,
the N(1) and the pyrimidine N(3) nitrogen atoms and to the
Cl(1) chlorine atom. The angles between adjacent atoms in
the coordination sphere of palladium are close to the ex-
pected value of 90ꢀ, with the most noticeable distortions
corresponding to the N(1)-Pd(1)-N(3) angle of 78.98(9)ꢀ
and the C(1)-Pd(1)-Cl(1) angle of 100.66(6)ꢀ. The sum of
the angles about palladium is approximately 360ꢀ.
˚
The Pd(1)-N(3) bond length [2.135(2) A] is longer than
˚
Pd(1)-N(1) distance [1.968(2) A], showing the stronger trans
influence of the C(1) carbon atom as compared to the Cl(1)

Article
Organometallics, Vol. 30, No. 3, 2011 399
Table 1. Crystallographic Data for Complexes 1a and 5b
1a
5b
empirical formula
C
28H38ClF3N6
C
43H44AgCl4F6N4O12
PPdS2
O7Pd
769.49
293(2)
293(2)
monoclinic
P21/m
9.228(1)
21.284(2)
17.522(2)
formula mass
T [K]
1373.98
293(2)
293(2)
triclinic
P1
15.001(2)
15.156(2)
15.691(3)
113.524(13)
108.545(11)
99.485(9)
2921.4(8)
2
˚
λ [A]
crystal system
space group
˚
a [A]
˚
b [A]
˚
c [A]
R [deg]
β [deg]
γ [deg]
93.064(2)
3
˚
V [A ]
Z
3436.7(5)
4
0.685
0.92, 0.85
1.487
μ [mm-1
max, min transmissions
]
1.000
0.85, 0.75
1.562
F
calcd [gcm-3
]
θ range [deg]
reflections collected
independent reflections
1.91 to 28.30
46118
8543
1.52, 25.00
31393
10270
(Rint = 0.052)
0.0389
0.0980
(Rint = 0.047)
0.1020
0.3243
a
R1
wR2
b
P
P
P
a R1 =
Fo| - |Fc
/
|Fo|, [F > 4σ(F )]. b wR2 = [ [w(Fo2 - Fc2)2/
P
(Fo2)2]1/2, all data.
˚
Table 2. selected Bond Lengths (A) and Angles (deg) for Com-
plexes 1a and 5b
Figure 1. Molecular structure of [Pd{3,4-(C10H20O6)C6H2C(Me)d
NN(H) [30-(CF3)C4H2N2]}(Cl)], 1a, with labeling scheme. Hy-
drogen atoms have been omitted for clarity.
1a
5b
Pd(1)-C(6)
1.985(3)
1.968(2)
2.135(1)
2.312(1)
2.021(9)
2.014(7)
2.132(7)
Pd(1)-N(1)
˚
chlorine. The Pd(1)-C(1) [1.984 (3) A] bond distance is
Pd(1)-N(3)
Pd(1)-Cl(1)
somewhat shorter than the value predicted from their cova-
lent radii.17 Pd-N and Pd-C lengths are similar to values
found earlier.6,18-20
Pd(1)-P(1)
2.270(2)
1.401(12)
1.518(13)
1.312(12)
1.353(10)
1.366(12)
1.319(11)
2.872(9)
2.646(11)
2.77(2)
2.42(2)
2.64(4)
2.76(3)
2.581(9)
2.903(8)
2.399(11)
C(1)-C(6)
1.409(4)
1.464(4)
1.295(3)
1.380(2)
1.360(3)
1.360(3)
C(1)-C(7)
The geometry around the palladium atom [Pd(1), C(6),
N(1), N(3), Cl(1)] is planar (rms = 0.032, plane1). The meta-
lated ring [Pd(1), C(1), C(6), C(7), N(1), plane 2] and the
coordination ring [Pd(1), N(1), N(2), C(8), N(3), plane 3] are
also planar (rms = 0.010 and 0.015, respectively). Planes 1, 2,
and 3 the metalated phenyl ring and the pyrimidine ring are
almost coplanar (largest angle between planes of 6.1ꢀ).
π-π Stacking Interactions in 1a. The term π-π stacking
refers to the particular stacking arrangement adopted by
aromatic rings; however, the nature of the weak interactions
causing this disposition is not well understood.21 In any case,
π-π interactions are strongly dependent on the number
of aromatic rings present in the molecule and, conseque-
ntly, systems with several fused rings experiment attractive
forces which determine their crystal packing and contribute,
for example, to self-assembly or molecular recognition pro-
cesses.22
N(1)-C(7)
N(1)-N(2)
N(2)-C(8)
C(8)-N(3)
Ag(1)-O(1)
Ag(1)-O(2)
Ag(1)-O(3A)
Ag(1)-O(3B)
Ag(1)-O(4a)
Ag(1)-O(4b)
Ag(1)-O(5)
Ag(1)-O(6)
Ag(1)-O(7)
C(6)-Pd(1)-N(1)
N(1)-Pd(1)-N(3)
C(6)-Pd(1)-N(3)
N(1)-Pd(1)-Cl(1)
C(6)-Pd(1)-Cl(1)
Cl(1)-Pd(1)-N(3)
N(1)-Pd(1)-P(1)
C(6)-Pd(1)-P(1)
P(1)-Pd(1)-N(3)
81.10(10)
78.99(7)
160.09(8)
179.53(8)
99.26(8)
80.9(3)
76.4(3)
157.1(3)
100.65(3)
172.4(2)
98.9(2)
104.04(19)
Conventionally, these interactions affect aromatic systems
bearing phenyl or heterocyclic rings; nevertheless, recently
the participation of heterocyclic metalacycles in such inter-
actions has been proposed on the basis of the “pseudoaro-
matic” nature of these rings.23,24
In the crystal of complex 1a, the presence of an aromatic
system formed by the heterocyclic and phenyl rings, plus two
five-membered metalacycles, suggests that π-π interactions
can play an important role in controlling the crystal packing
(17) Pauling., L. The Nature of the Chemical Bond, 3rd ed.; Cornell
University Press, New York, 1960.
(18) Garcıa-Herbosa, G.; Conelly, N. G.; Munoz, A.; Cuevas, J. V.;
~
Orpen, A. G.; Politzer, S. D. Organometallics 2001, 20, 3223.
(19) Ghedini, M.; Aiello, I.; Crispini, A.; La Deda, M. J. Chem. Soc.,
Dalton Trans. 2004, 1386.
(20) Neve, F.; Crispın, A.; Di Pietro, C.; Campagna, S. Organome-
tallics 2002, 21, 3511.
(21) Grimme, S. Angew. Chem., Int. Ed. 2008, 47, 3430.
(22) (a) Amabilino, D. B.; Stoddart, J. F. Chem. Rev. 1995, 95, 2725.
(b) Claessens, C. G.; Stoddart, J. F. J. Phys. Org. Chem. 1997, 10, 254. (c)
Hirsch, K. A.; Wilson, S. R.; Moore, J. S. Chem.;Eur. J. 1997, 3, 765.
(23) Masui, H. Coord. Chem. Rev. 2001, 957, 219.
(24) Ghedini, M.; Aiello, I.; Crispini, A.; Golemme, A.; La Deda, M.;
Pucci, D. Coord. Chem. Rev. 2006, 250, 1373.

ꢀ ´
Vazquez-Garcıa et al.
400 Organometallics, Vol. 30, No. 3, 2011
Figure 2. Intermolecular π,π-stacking interactions. Dashed lines link the centroids of the rings involved in each stacking interaction.
and contribute to the molecular self-assembly. Such interac-
tions involve not only phenyl or heterocyclic rings aromatic
systems but also the participation of heterocyclic metalacy-
cles based on the “pseudoaromatic” nature of these rings.31,32
Consequently, π-π stacking between the metalated [Pd(1),
C(6), C(1), C(7), N(1), ring 2] and the coordination [Pd(1),
N(1), N(2), C(8), N(3), ring 3] rings (separation between ring
nonparallel disposition of the metalated rings and, on the
contrary, they tended to avoid the steric hindrance by
adopting staggered conformations.9,28
Reactivity of the Cyclometalated Complexes. Treatment of
1a and 1b, with silver trifluoromethanesulfonate followed
by triphenylphosphine gave 2a and 2b, with the phosphine
ligand occupying the vacant coordination position after
AgCl removal. The signals corresponding to the H5 [δ ca.
5.7 ppm; 4J (H5P) ca. 5 Hz] and NH [δ ca. 11.3 ppm; 4J (H5P)
ca. 4.7 Hz] protons showed coupling to the phosphorus
nucleus. The H11 and H5 resonances were upfield shifted due
to shielding by the phosphine phenyl rings.29 The 31P-{1H}
NMR spectra showed a singlet resonance ca. δ41 in accor-
dance with a trans phosphorus-to-nitrogen geometry.30,31
The presence of strong bands assigned to the ν(NH) stretch
in the IR spectra showed the ligands were not deprotonated,
in agreement with the cationic nature of the complexes,
confirmed by the conductivity measurements as 1:1 electro-
lytes. Deprotonation at NH was achieved by treatment of 2a
and 2b with a base (sodium acetate) in methanol to give the
neutral complexes 3a and 3b. This behavior, previously
reported for similar complexes,6,16 was confirmed by the
absence of the υ(N-H) band and the NH resonance in the IR
˚
centroids 3.51 A) was observed (Figure 2). In fact, the
metalated and the coordination rings are not stacked in a
roughly “face-to-face” fashion but rather in a “slipped stac-
king” disposition.25 The metalated phenyl and pyrimidine
rings were also parallel and within the distance expected for
π-π “slipped stacking” (distance between the ring centroids,
˚
3.66 A).
Whether this arrangement is a consequence of attractive
interaction between the “metaloaromatic” rings or is requi-
red by the cyclometalated phenyl-pyrimidine ring interaction
cannot be established unambiguously; nevertheless, similar
interactions between metalacycles (vide infra) have been
previously described.19,26 In particular, we have found that
cyclometalated complexes with four fused rings [a phenyl
ring, a metalated chelate, a metal chelate, and a heterocyclic
(pyrazine or pyrimidine) ring] appear stacked as pairs in the
solid state. Within each pair, two cyclometalated moieties are
mutually parallel with a separation and geometric arrange-
ment characteristic of π-π stacked rings.6 These data seem
to indicate the importance of π-π interactions in the crystal
packing of polycyclic cyclometalated complexes and, with
this in mind, we decided to carry out a CSD search to exa-
mine the occurrence of such interactions in similar systems.
Thus, Ghedini et al. studied the aromatic character of
cyclometalated rings, and they found metaloaromaticity in
planar five-membered rings,27 therefore, we decided to re-
strict our search to complexes containing, at least, four fused
rings at the metal, in this case palladium, with 21 crystals,
fulfilling the search conditions (plus the two reported here).
The results may be summarized as follows: in most cases, the
1
and H NMR spectra, respectively. Conductivity measure-
ments in acetonitrile were in accordance with the molecular
nature of 3a and 3b. In the 31P-{1H} NMR spectra, the
phosphorus resonance appeared at δ 38.30 (3a) and 38.28
(3b) ppm, slightly highfield shifted.
Reaction of 1a and 1b with a Ag(I) salt and Ph2P-
(CH2)4PPh2 (dppb) in a 2:1 molar ratio gave the dinuclear
cyclometalated complexes 4a and 4b, as 1:2 electrolytes,
which were fully characterized (see Experimental Section).
The IR and 1H NMR spectra of these complexes were similar
to those of the parent complexes 2a and 2b (vide supra),
indicating a similar coordination sphere for palladium. The
symmetric nature of the complexes was established by
the presence of only one singlet signal in the 31P-{1H} spectra
˚
˚
distances between centroids is less than 4.0 A [3.38-3.71 A]
and angles between ring normal and the centroid vector less
than 20ꢀ [7.2-19.24ꢀ]; stand-alone π-π interactions between
rings were not found; polycyclic systems are arranged in a
“slipped stacking” manner rather than in a “face-to-face”
one. The distance between centroids tends to be shorter with
increasing number of fused rings or when two cyclometa-
lated moieties are connected by a bridging ligand. However,
for short-bite diphosphines such as dppm, which should
favor intermolecular interactions, the structures showed a
(28) (a) Jian-Fang, M.; Yamamoto, Y. Inorg. Chim. Acta 2000, 299,
164. (b) Vila, J. M.; Gayoso, M.; Fernandez, J. J.; Ortigueira, J. M.;
Fernandez, A.; Bailey, N. A.; Adams, H. J. Organomet. Chem. 1994, 471,
259. (c) Vila, J. M.; Ortigueira, J. M.; Gayoso, E.; Gayoso, M.; Castineiras,
A.; Hiller, W.; Strahle, J. Inorg. Chim. Acta 1991, 179, 171. (d) Vicente, J.;
Arcas, A.; Bautista, D.; de Arellano, M. C. R. J. Organomet. Chem. 2002,
663, 164.
(29) Vila, J. M.; Gayoso, E.; Pereira, M. T.; Ortigueira, J. M.;
~
Alberdi, G.; Marino, M.; Alvarez, R.; Fernandez, A. Eur. J. Inorg.
ꢀ
Chem. 2004, 2937.
(30) Pregosin, P. S.; Kuntz, R. W. 31P and 13C NMR of Transition
Metal Phosphine Complexes. In NMR: Basic Principles and Progress,
Diehl, P., Fluck, E., Kosfeld, R., Eds.: Springer: Berlin, 1979.
(25) Janiak, C. J. Chem. Soc., Dalton Trans. 2000, 3885.
~
ꢀ
ꢀ
ꢀ
(26) Castineiras, A.; Sicilia-Zafra, A. G.; Gonzalez-Perez, J. M.;
ꢀ
(31) Albert, J.; Granell, J.; Sales, J.; Font-Bardıa, M.; Solans, X.
ꢀ
Choquesillo-Lazarte, D.; Niclos-Gutierrez, J. Inorg. Chem. 2002, 41,
6956.
Organometallics 1995, 14, 1393.
(32) Bravo, J.; Cativiela, C.; Navarro, R.; Urriolabeitia, E. P.
(27) Crispini, A.; Ghedini, M. J. Chem. Soc., Dalton Trans. 1997, 75.
J. Organomet. Chem. 2002, 650, 157.

Article
Organometallics, Vol. 30, No. 3, 2011 401
heterocyclic N(3) nitrogen atoms, and to the phosphorus
atom of the triphenylphosphine ligand P(1). The angles
between adjacent atoms in the coordination sphere of palla-
dium are close to the expected value of 90ꢀ, with the most
noticeable distortions corresponding to N(1)-Pd(1)-N(3)
[76.4(3)ꢀ] and N(3)-Pd(1)-P(1) [108.0(2)ꢀ]. The sum of
angles about palladium is approximately 360ꢀ.
˚
˚
The Pd-C(6) [2.021(9) A], Pd-P(1) [2.270(2) A], Pd-N-
˚
˚
(1) [2.021(9) A], and Pd-N(3) [2.132(7) A] bond distances
are within the expected values,6,32,33 with allowance for the
differing trans influence of the C(1) and P(1) atoms which is
reflected in the longer Pd(1)-N(3) distance.
The coordination sphere around palladium [Pd(1), C(6),
N(2), N(3), P(1)] is planar (rms = 0.0953; plane1) with a
small tetrahedral distortion, probably caused by the steric
hindrance of the triphenylphosphine ligand. The metalated
[Pd(1), C(1), C(6), C(7), N(1), plane 2] and the coordination
[Pd(1), N(1), N(2), C(8), N(3), plane 3] rings are also planar
(rms = 0.0330; plane 2, and 0.0197; plane 3) and coplanar
with the metalated phenyl and pyridazine rings [largest angle
between planes 7.9ꢀ corresponding to plane 1/metalated
phenyl]; consequently, the molecular cation may be consid-
ered to be planar save for the phosphine phenyls and the
crown ether moiety.
Figure 3. Molecular structure of [Pd{3,4-(C10H20O6)C6H2-
C(Me)dNN(H)(40-ClC4H2N2)}(PPh3)][CF3SO3]2, 5b, with the
cation Ag(I) coordinated to the crown ether oxygens, with
labeling scheme. Hydrogen atoms have been omitted for clarity.
(δ 27.82, 4a, and 30.30, 4b ppm). The mass-FAB spectra
showed clusters of peaks centered at 1813 (4a) and 1569 (4b)
amu, assigned to loss of one triflate (4a) or two perchlorate
(4b) counteranions. The specific molar conductivity mea-
surements, carried out in dry acetonitrile, are in agreement
with 2:1 electrolytes.
The Ag atom is coordinated by a η4-[18]crown-6 ether
˚
Crown Ether Palladacycles As Metaloligands. The com-
plexes described above are potential receptors to be used for
selective coordination of metal cations, owing to the pre-
sence of crown ether rings. Thus, in a similar fashion as des-
cribed by us for the preparation of adducts with nontransi-
tion metals, presently we attempted to coordinate silver
atoms into the 15-crown-5 and 18-crown-6 rings. Attempts
to produce Ag(I) complexes with the 15-crown-5 ether pal-
ladacycles reported earlier by us12 gave either the starting
material or mixtures which we were unable to separate,
however, when complex 2b, bearing a 18-crown-6 ring, was
treated with an equimolar amount of silver trifluoromethyl-
sulfonate, pure 5b was isolated as a red solid, and this
produced the first crystal structure of a crown ether pallada-
cycle accommodating a transition metal in the ether ring
(Scheme 1 and Experimental Section). Thus, treatment of 2b
with AgCF3SO3 in 1:1 molar ratio in ethanol yielded 5b via
complexation of a Ag(I) ion to the crown ether group, as a 1:2
(taking Ag-O distances below 2.8 A as effective binding;
disorder was found in the O(3) and O(4) oxygens, see X-ray
experimental). The remaining Ag-O distances, Ag(1)-O(1)
˚
Ag(1)-O(6), 2.872(9), and 2.903(8) A, respectively, indicate
that the Ag atom is not in the center of the cavity. Although
Ag(I) should fit well into the 18-crown-6 ether ring, a similar
situation of η4-[18]crown bonding has been previously
reported.21 Additional bonding to one oxygen atom of the
triflate anion on one face is present, with a Ag(1)-O(7) bond
˚
distance of 2.399 A. Two factors contribute to the lack of
interactions of the silver atom on the other side of the crown
ether ring: (a) the distortion of the ring minimizes the ex-
posed surface of the Ag(I) atom on the opposite side of the
crown ether, and (b) crystal packing of the molecules, where
the proximity of the pyridazine ring hinders any further
intermolecular contacts. No hydrogen bonding involving
the silver atom was observed, although a N(2)-H(2)
3 3 3
O(11) interaction was found [N(2)-H(2), 0.86A; N(2)-H-
1
˚
(2) O(1), 2.67(2) A]. The molecular cations are arranged
electrolyte. The H NMR spectra showed only one set of
signals, similar to those observed for the parent compound,
3 3 3
as dimers with π-π stacking interactions between the co-
ordination [Pd(1), N(1), N(2), C(8), N(3), ring 3] and the
metalated phenyl [C(1)-C(6)] rings (distance between ring
and the IR spectra show an absorption at 1262 cm-1
,
assigned to the triflate group. The MS-FAB spectra showed,
among others, the corresponding peak assigned to [(L-H)-
AgPd(PPh3)(CF3SO3)]þ, which were characteristic clusters
of isotopic peaks due to the presence of the numerous pal-
ladium isotopes.11
Crystal Structure of Complex 5b. Recrystallization of com-
plex 5b from a solution of chloroform/n-hexane gave red
crystals whose crystalline structure was solved. The crystals
contain a Ag(I) cation, from the silver trifluoromethane
sulfonate, located in the cavity of the crown ether of 5b.
The molecular structure is shown in Figure 3, crystal data are
in Table 1, and selected bond distances and angles are given
in Table 2.
˚
centers, 3.63 A) as well as between two metalacycles [Pd(1),
C(1), C(6), C(7), N(1), ring 2] (distance between ring centers,
˚
3.64 A) (Figure 4). In each dimer, the crown ether moieties
are in a “trans” arrangement and with the silver atom coordi-
nated to opposite faces. The cations are arranged in a linear
fashion along the crystallographic b axis, with planes 1, 2,
and 3 parallel to the a axis (Figure 4).
3. Experimental Section
General Comments. Safety Note. CAUTION: Perchlorate
salts of metal complexes with organic ligands are potentially
explosive. Only small amounts of these materials should be
prepared and handled with great caution.
The crystal structure comprises one complex cation bon-
ded to a silver atom, two CF3SO3- anions, and two chloro-
form molecules per asymmetric unit. The palladium atom
is bonded in a slightly distorted square-planar geometry to
the C(1) carbon atom of the phenyl ring, the N(1) and the
(33) Lai, S. W.; Cheung, T. C.; Chang, M. C. W.; Cheung, K. K.;
Peng, S. M.; Che, C. M. Inorg. Chem. 2000, 39, 255.

ꢀ ´
Vazquez-Garcıa et al.
402 Organometallics, Vol. 30, No. 3, 2011
Figure 4. Intermolecular π,π-stacking interactions. Dashed lines link the centroids of the rings involved in each stacking interaction.
Phosphine phenyls have been omitted for clarity.
General Procedures. Solvents were purified by standard
methods.34 Chemicals were reagent grade. Microanalyses were
carried out using a Carlo Erba elemental analyzer, model 1108.
IR spectra were recorded KBr discs on Perkin-Elmer 1330 and
Mattson spectrophotometers. NMR spectra were obtained as
CDCl3, CD3SOCD3, or CD3COCD3 solutions and referenced
to SiMe4 (1H, 13C-{1H}) or 85% H3PO4 31P-{1H}) and were
recorded on Bruker AC-200 or AC-300F spectrometers. All che-
mical 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) or 3-mercap-
to-1,2-propanediol (1-thioglycerol) were used as the matrix. The
ESI mass spectra were recorded using a QSTAR Elite mass
spectrometer, using acetronitrile or dichloromethane/ethanol as
solvents. Conductivity measurements were made on a CRISON
GLP 32 conductivimeter using 10-3 mol dm-3 solutions in dry
acetonitrile or dimethylformamide.
Synthesis 3,4-(C10H20O6)C6H2CO(Me). A mixture of benzo-
18-crown (2.03 g, 6.49 mmol), phosphoric acid (25.78 g, 263.16
mmol), and acetic anhydride (12 mL) in 50 mL of acetic acid was
refluxed with stirring for 24 h at 60 ꢀC and, after cooling to room
temperature (rt), 200 cm3 of water were added to the crude
product, and the resulting mixture extracted with three 100 mL
portions of CHCl3. An excess of NaHCO3 was added to the or-
ganic phase, and once the evolution of CO2 ceased the solution
was filtered off, dried over anhydrous MgSO4, and the solvent
removed under reduced pressure. The resulting yellow oil was
extracted with four 40 mL portions of hot petroleum ether
60-80. After cooling to rt, the white solid formed was filtered
off and dried under vacuum. Yield: 70%. Anal. Found: C, 61.2;
H, 6.8. C16H21O6 requires C, 61.1; H, 6.8.%. IR: ν(CdO), 1732w
cm-1. 1H NMR (300.13 MHz, CDCl3, δ ppm, J Hz): 7.56 [dd,
1H, H6, 3J (H5H6) = 8.33, 4J (H6H2) = 2.05], 7.52 [d, 1H, H2],
6.87 [d, 1H, H5].
Synthesis of 3,4-(C10H20O6)C6H3C(Me)dNN(H)[30-(CF3)-
C4H2N2] (a). A mixture of 3,4-(C10H20O6)C6H2CO(Me) (0.17 g,
0.482 mmol), NH2N(H)(40-ClC4H2N2) (0.086 g, 0.481 mmol),
and 0.1 cm3 of acetic acid in 50 cm3 of ethanol was stirred for 4 h
to room temperature, after which the solvent was removed to
give the desired product as a yellow solid. Yield 99%. Anal.
Found: C, 53.6; H,5.6; N, 10.8. C23H29N4O6F3 requires C, 53.7;
H, 5.7; N, 10.9%. IR: ν(CdN), 1650sh, m; ν(NH) 3506br cm-1
.
1H NMR (300.13 MHz, CDCl3, δ ppm, J Hz): 8.72 [d, 1H, H11,
3J (H10H11) = 4.9], 8.57 [s, br 1H, NH], 7.51 [d, 1H, H2,
4J(H2H6) = 2.1], 7.30 [dd, 1H, H6, J (H5H6) = 8.4], 7.05 [d,
1H, H10], 6.86 [d, 1H, H5], 2.32 [s, 3H, Me].
3
Compound b was obtained following a similar procedure as a
white solid which precipitated directly from the reaction mixture.
3,4-(C10H20O6)C6H3C(Me)dNN(H)(40-ClC4H2N2) (b). Yield
99%. Anal. Found: C, 54.7; H,6,6; N, 11.5. C22H29N4O6 requires
C, 54.9; H, 6.7; N, 11.6%. IR: ν(CdN) 1608sh; ν(NH), 3409br
cm-1. 1H NMR (300.13 MHz, CDCl3, δ ppm, J Hz): 8.73 [s, br,
3
1H, NH], 7.66 [d, 1H, H11, J (H11H12) = 9.3], 7.41 [d, 1H,
H2, 4J (H2H6) = 2.1], 7.39 [d, 1H, H12], 7.26 [dd, 1H, H6,
3J (H5H6)=8.4], 6.88 [d, 1H, H5], 2.31 [s, 3H, Me(CdN)].
Synthesis of [Pd{3,4-(C10H20O6)C6H2C(Me)dNN(H)[30-
(CF3)C4H2N2]}(Cl)] (1a). A stirred solution of palladium(II)
chloride (0.090 g, 0.510 mmol) and lithium chloride (0.055 mg,
1.31 mmol) in methanol 50 cm3 was treated with 3,4-(C10-
H20O6)C6H3C(Me)dNN(H)[30-(CF3)C4H2N2] (a) (0.245 mg,
0.477 mmol) and sodium acetate (0.043 mg, 0.525 mmol). The
mixture was stirred to room temperature for 48 h. The orange
precipitate formed was filtered off and air-dried. Yield 33%.
Anal. Found: C, 42.2; H, 4.4; N, 8.6. C23H28N4O6F3PdCl requires
C, 42.1; H, 4.3; N, 8.5%. IR: ν(CdN) 1601 m; ν(NH) 3432br
cm-1. 1H NMR (300.13 MHz, CD3SOCD3, δ ppm, J Hz):8.40[d,
1H, H11, 3J (H10H11) = 5.7], 7.30 [d, 1H, H10], 6.80 [s, 1H, H2],
6.73 [s, 1H, H5], 2.31 [s, 3H, Me]. ESI-MS: m/z = 619 [(L-
H)Pd]þ. Specific molar conductivity, Λm = 6.64 S cm2 mol-1 (in
dimethylformamide).
(34) Perrin, D. D.; Armarego, W. L. F.; Perrin, D. L. Purification of
Laboratory Chemicals, 3rd ed.; Pergamon: London, 1998.

Article
Compound 1b was obtained following a similar procedure, as
Organometallics, Vol. 30, No. 3, 2011 403
Table 3. Intermolecular π-π Stacking Parametersa Calculated
Using the Program PLATON35 for 1a
orange solid.
[Pd{3,4-(C10H20O6)C6H2C(Me)dNN(H)(40-ClC4H2N2)}(Cl)]
(1b). Yield 92%. Anal. Found: C, 42.3; H, 4.6; N, 8.9. C22H28-
N4O6Cl2Pd requires C, 42.5; H, 4.5; N, 9.0%. IR: ν(CdN) 1595 m;
parameter
plane 2/plane 3
pyrimidine/phenyl
˚
d(C1-C2) A/R deg
3.510(1)/1.88
3.662(2)/6.12
ν(NH), 3466br cm-1 1H NMR (300.13 MHz, CD3SOCD3,
.
^
˚
d(C1- R(2)) A
3.46
3.45
10.3
10.0
3.47
3.57
12.8
18.6
δ ppm, J Hz): 7.64 [d, 1H, H11, 3J (H11H12) = 10.2], 7.24 [d, 1H,
H12], 6.87 [s, 1H, H2], 6.68 [s, 1H, H5], 2.27 [s, 3H, Me(CdN)].
ESI-MS: m/z = 645 [{(L-H)PdCl}Na. Specific molar conduc-
tivity, Λm = 11.12 S cm2 mol-1 (in dimethylformamide).
Synthesis of [Pd{3,4-(C10H20O6)C6H2C(Me)dNN(H)[30-(CF3)-
C4H2N2]}(PPh3)]-[CF3SO3] (2a). A suspension of 1a (0.039 g,
0.0594 mmol) in acetone (15 cm3) was treated with silver
trifluoromethanesulfonate (0.015 mg, 0.0595 mmol) and stirred
for 4 h. The solution was filtered through Celite to eliminate the
AgCl precipitate. Then PPh3 (0.015 g, 0.0575 mmol) was added
to the filtrate and the resulting solution stirred for another 4 h,
after which the solvent was removed to give a yellow oil. Yield
85%. Anal. Found: C, 48.7; H, 4.1; N, 5.4. C42H43N4O9F6PSPd
requires C, 48.9; H, 4.2; N, 5.4%. IR: ν(CdN), 1606 m; ν(NH)
d(C2- R(1)) A
^
˚
angle V(C1 f C2) ^R1 deg
angle V(C2fC1) ^R2 deg
a CI = centroid of ring I; R = dihedral angle between ring mean
planes. V(CI f CJ) is the vector between ring centroids; ^RI = line
perpendicular to ring I.
46.4; H, 4.4; N, 5.6. C76H84N8O18F12P2S2Pd2 requires C, 46.5; H,
4.3; N, 5.7%. IR: ν(CdN) 1606 m, ν(NH) 3451br, ν (CF3SO3)
1222s, br cm-. 1H MNR (300.13 MHz, CD3COCD3, δppm, J Hz):
10.48 [d, 1H, NH, 4J(PHN)=5.1], 6.68 [d, 1H, H10, 3J(H10H11)=
6], 6.64 [s, 1H, H2], 6.46 [d, 1H, H11], 5.65 [d, 1H, H5, 4J (PH5) =
5.4], 2.37 [s, 3H, Me]. 31P-{1H} NMR (121.49 MHz, CDCl3,
δ ppm): 27.82 (s). ESI-MS: m/z = 1813 [(L-H)2Pd2(dppb)(CF3-
SO3)]þ. Specific molar conductivity, Λm = 235 S cm2 mol-1 (in
acetonitrile).
1
3500br; ν(CF3SO3), 1262s, br cm-1. H MNR (300.13 MHz,
CD3COCD3, δ ppm, J Hz): 11.00 [d, 1H, NH, 4J (PHN)=4.3],
7.08 [s, 1H, H2], 6.90 [d, 1H, H10, 3J (H10H11)=6.0], 6.10 [d,
Compound 4b was obtained following a similar procedure,
but using AgClO4, as a red solid.
4
1H, H11], 5.82 [d, 1H, H5, J (PH5) = 5.1], 2.66 [s, 3H, Me].
31P-{1H} NMR (121.49 MHz, CDCl3, δ ppm): 40.43 (s). ESI-
MS: m/z=881.17 [(L-H)Pd(PPh3)]þ. Specific molar conductiv-
ity, Λm =144.7 S cm2 mol-1 (in acetonitrile).
Synthesis of [{Pd[3,4-(C10H20O6)C6H2C(Me)dNN(H)(40-
ClC4H2N2)]}2{μ-PPh2-(CH2)4PPh2}][ClO4]2 (4b). Yield 96%.
Anal. Found: C, 47.9; H, 4.8; N, 6.3. C72H84N8O20Cl4P2Pd2 re-
quires C, 48.1; H, 4.7; N, 6.2%. IR: ν(CdN) 1478 m, ν(NH) 3461br,
ν(CF3SO3) 1222s, br cm-1.1H MNR (300.13 MHz, CD3COCD3, δ
Compound 2b was obtained following a similar procedure, as
a red solid which was recrystallized from acetone/hexane.
[Pd{3,4-(C10H20O6)C6H2C(Me)dNN(H)(40-ClC4H2N2)}(PPh3)]-
[CF3SO3] (2b). Yield 56%. Anal. Found: C, 49.3; H, 4.2; N, 5.7.
C41H43N4O9ClF3PSPd requires C, 49.4; H, 4.3; N, 5.6%. IR:
3
ppm, J Hz): 7.76 [d, 1H, H11, J (H11H12) = 9.6], 7.52 [d, 1H,
H12], 7.03 [s, 1H, H2], 5.77 [d, 1H, H5, 4J (PH5)=4.2], 2.52 [s, 3H,
Me(CdN)]. 31P-{1H} NMR (121.49 MHz, CDCl3, δ ppm): 30.30
(s). ESI-MS: m/z = 1599.3 [(L-H)2Pd2(dppb)H]þ. Specific molar
conductivity, Λm = 312 S cm2 mol-1 (in acetonitrile).
ν(CdN), 1557 m; ν(NH), 3181br; ν(CF3SO3), 1265s, br cm-1
.
1H MNR (300.13 MHz, CD3COCD3, δ ppm, J Hz): 11.50 [d,
1H, NH, 4J (PHN)=5.1], 7.17 [d, 1H, H12, 3J (H11H12) = 9.3],
6.63 [s, 1H, H2], 5.66 [d, 1H, H5, 4J (PH5) = 4.8], 2.50 [s, 3H,
Me(CdN)]. 31P-{1H} NMR (121.49 MHz, CD3COCD3, δ ppm,
J Hz): 41.70 (s). ESI-MS: m/z = 847 uma [(L-H)Pd(PPh3)]þ.
Specific molar conductivity, Λm=196 S cm2 mol-1 (inacetonitrile).
Synthesis of [Pd{3,4-(C10H20O6)C6H2C(Me)dNN[30-(CF3)-
C4H2N2]}(PPh3)] (3a). A solution of 2a (0.0168 g, 0.0163 mmol)
in 25 cm3 of methanol was treated with a sodium acetate (0.0013 g,
0.0158 mmol), the resulting solution stirred for 3 h, and the solvent
removed to give a red solid, which was recrystallized in dichlor-
omethane/hexane. Yield 33%. Anal. Found: C, 55.8; H, 4.7; N, 6.5.
C41H42N4O6F3PPd requires C, 55.9; H, 4.8; N, 6.4%. IR: ν(CdN)
1585 cm-1. 1H MNR (300.13 MHz, CD3COCD3, δ ppm, J Hz):
6.68 [s, 1H, H2], 6.43 [d, 1H, H10, 3J (H10H11) = 5.7], 5.68 [d, 1H,
H11], 5.65 [d, 1H, H5, 4J (PH5) = 5.4], 2.60 [s, 3H, Me(CdN)].
31P-{1H} NMR (121.49 MHz, CDCl3, δ ppm): 38.30 (s). ESI-MS:
Synthesis of [Pd{3,4-(AgC10H20O6)C6H2C(Me)dNN(H)(40-
ClC4H2N2)}(PPh3)]-[CF3SO3]2 (5b). Silver(I) trifluoromethane
sulfonate (0.030 g, 0.117 mmol) was dissolved in ethanol (1 cm3)
and mixed with a solution of 2b (0.092 g, 0.117 mmol) in ethanol
(10 cm3), and the resulting colorless solution allowed to stand in
the dark for 1 week, resulting in the deposition of the product as
a red solid, which was recrystallized from chloroform/n-hexane.
Yield 45%. Anal. Found: C, 37.2 H, 3.1; N, 3.9. C42H43AgClF6-
N4O12PPdS2 CHCl3 requires C, 37.6; H, 3.2; N, 4.1%. IR: ν(CdN)
3
1
1435 m, ν(NH), 3170br; ν(CF3SO3), 1262s, br cm-1. H NMR
4
(300.13 MHz, CD3COCD3, δ ppm, J Hz): 11.20 [d, 1H, NH, J
(PHN) = 5.0], 7.21 [d, 1H, H12, 3J (H11H12) = 9.3], 6.65 [s, 1H,
H2], 5.60 [d, 1H, H5, 4J (PH5) = 4.6], 2.48 [s, 3H, Me]. 31P-{1H}
NMR (211.49 MHz, CDCl3, δppm): 41.0 (s). ESI-MS: m/z = 1106
[(L-H)AgPd(PPh3)(CF3SO3)]þ. Specific molar conductivity, Λm =
250 S cm2 mol-1 (in acetonitrile).
m/z = 880 [(L-H)Pd(PPh3)]þ. Specific molar conductivity, Λm
8.33 S cm2 mol-1 (in acetonitrile).
=
X-ray Crystallographic Study. Three-dimensional, room tem-
perature X-ray data were collected on a Bruker Smart 1k CCD
using graphite-monochromated Mo KR radiation. All the mea-
sured 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, except HN(2) (1a and 5b crystals) and MeOH (1a)
hydrogens, which were located in a difference Fourier map and
refined in riding mode. Serious disorder problems were found in
the crystal of 5b. The C(15) to C(20) carbon atoms and O(3) and
O(4) oxygen atoms of the crown ether ring were found to be
disordered and, consequently, refined in two complementary
positions with 53 and 47% occupancies. C-C and C-O bond
distances were restrained to reasonable values. The two triflate
ions showed thermal ellipsoids with unusual elongation due to a
disorder problem; several different models were used with
unreasonably results and consequently were not considered
Compound 3b was obtained similarly, as a violet solid.
Synthesis of [Pd{3,4-(C10H20O6)C6H2C(Me)dNN(40-ClC4-
H2N2)}(PPh3)] (3b). Yield 30%. Anal. Found: C, 56.6; H, 4.8; N,
6.7. C40H42N4O6ClPPd requires C, 56.7; H, 4.9; N, 6.6%. IR:
1
ν(CdN) 1435 m, cm-1. H MNR (300.13 MHz, CD3COCD3, δ
ppm, J Hz): 6.61 [s, 1H, H2], 5.63 [d, 1H, H5, 4J (PH5) = 3.6], 2.29
[s, 3H, Me]. 31P-{1H} NMR (211.49 MHz, CDCl3, δ ppm): 38.28
(s). ESI-MS: m/z = 846 [(L-H)Pd(PPh3)]þ. Specific molar con-
ductivity, Λm = 9.02 S cm2 mol-1 (in acetonitrile).
Synthesis of [{Pd{3,4-(C10H20O6)C6H2C(Me)dNN(H)[30-
(CF3)C4H2N2]}}2{μ-PPh2(CH2)4PPh2}][CF3SO3]2 (4a). Silver tri-
fluoromethanesulfonate (109 mg, 0.166 mmol) was added to a
solution of 1a (0.043 mg, 0.066 mmol) in acetone (25 cm3). The
resulting mixture was stirred for 2 h and filtered through Celite to
remove the AgCl precipitate formed. Ph2P(CH2)4PPh2 (0.013 g,
0.017 mmol) was then added to the filtrate, the solution stirred for
another 4 h, and the solvent removed to give a red solid which was
recrystallized from acetone/hexane. Yield 90%. Anal. Found: C,

ꢀ
Vazquez-Garcıa et al.
´
404 Organometallics, Vol. 30, No. 3, 2011
Table 4. Intermolecular π-π Stacking Parametersa Calculated
after the solvent removal. PLATON/SQUEEZE was also used to
study the effects of one of the disordered triflates, whose
effects were removed, after which the wR2 converged to a
reasonably 0.22; however, in order to preserve the electro-
neutrality, the final refinement included the two triflate coun-
terions in the model. Regardless of the disorder problems, the
results are clearly sufficient to establish the connectivity of the
molecule without any ambiguity. Refinement converged with
allowance for thermal anisotropy of all non-hydrogen atoms. The
structure solution and refinement were carried out using the
program package SHELX-97.36
Using the Program PLATON35 for 5b
parameter
ring 2/ring 2
ring 3/phenyl
˚
d(C1-C2) A/R deg
3.637(6)/ 0.0
3.50
3.50
3.635(5)/3.83
3.43
3.42
^
˚
d(C1- R(2)) A
^
˚
d(C2- R(1)) A
angle V(C1 f C2) ^R1 deg
angle V(C2 f C1) ^R2 deg
15.5
15.5
19.6
19.0
a CI = centroid of ring I; R = dihedral angle between ring mean
planes. V(CI f CJ) is the vector between ring centroids; ^RI = line
perpendicular to ring I.
Acknowledgment. We thank the Xunta de Galicia
(project INCITE 10PXIB209226PR and Grupos Conso-
lidados PGIDIT04PXI10301IF and INCITE07PXI-
103083ES) for financial support.
during the refinement. PLATON/SQUEEZE35 was used to
remove the effects of two ill-defined solvent molecules from
the data (Tables 3 and 4). The potential solvent volume was
299 A3 (10% of the cell volume) and accounted for a total of
94 electrons. wR2 improved from approximately 0.40 to 0.32
Supporting Information Available: X-ray crystallographic
data, tables giving atomic coordinates, displacement para-
meters, and bond distances and angles for 1a and 5b, (CCDC
no. 772696 (1a), 772697 (5b)). This material is available free of
charge via the Internet at http://pubs.acs.org.
(35) Spek., A. L. PLATON: A Multipurpose Crystallographic Tool;
University of Utrecht: The Netherlands, 2001.
(36) A Short History of SHELX. Sheldrick, G. M. Acta Crystallogr.,
Sect. A: Found. Crystallogr. 2008, 64, 112-122.