Self-assembly of polymer and sheet structures in palladium(II) complexes containing carboxylic acid substituents

Article abstract of DOI:10.1021/ic020239b

A series of complexes trans-[PdCl₂L₂] has been prepared by the reaction of [PdCl₂(PhCN)₂ and/or Na₂[PdCl₄] with L = pyridine or quinoline ligands having one or two carboxylic acid groups. T

Full text of DOI:10.1021/ic020239b

Inorg. Chem. 2002, 41, 5174−5186
Self-Assembly of Polymer and Sheet Structures in Palladium(II)
Complexes Containing Carboxylic Acid Substituents
Zengquan Qin, Michael C. Jennings, and Richard J. Puddephatt*
Department of Chemistry, UniVersity of Western Ontario, London, Canada N6A 5B7
Kenneth W. Muir
Department of Chemistry, Glasgow UniVersity, Glasgow G12 8QQ, U.K.
Received March 28, 2002
A series of complexes trans-[PdCl2L2] has been prepared by the reaction of [PdCl2(PhCN)2] and/or Na2[PdCl4] with
L ) pyridine or quinoline ligands having one or two carboxylic acid groups. These complexes can form 1-D polymers
through O−H‚‚‚O hydrogen bonding between the carboxylic acid groups, as demonstrated by structure determinations
of [PdCl2(NC H -4-COOH)2], [PdCl2(NC H -3-COOH)2], and [PdCl2(2-Ph-NC H -4-COOH)2]. In some cases, solvation
5
4
5
4
9 5
breaks down the O−H‚‚‚O hydrogen-bonded structures, as in the structures of [PdCl2(NC H -3-COOH)2]‚2DMSO
5
4
and [PdCl2(2-Ph-NC H -4-COOH)2]‚4DMF, while pyridine-2-carboxylic acid underwent deprotonation to give the
9
5
chelate complex [Pd{NC H -2-C(O)O)2]. The complexes trans-[PdCl2L2], L ) pyridine-3,5-dicarboxylic acid or 2,6-
5
4
dimethyl pyridine-3,5-dicarboxylic acid, self-assembled to give 2-D sheet structures, with hydrogen bonding between
the carboxylic acid groups mediated by solvate methanol or water molecules. In the cationic complexes [PdL′2L2]2+
(L′2 ) Ph2PCH PPh2, Ph2P(CH ) PPh2; L ) pyridine carboxylic acid; anions X- ) CF SO -), hydrogen bonding
2
2 3
3
3
between the carboxylic acid groups and anions or solvate acetone molecules occurred, and only in one case was
a polymeric complex formed by self-assembly.
Introduction
acid groups into coordination compounds is already known
to give interesting supramolecular architectures.6
The design of supramolecular architectures by self-
assembly of small building blocks has become a major
research area.1 While hydrogen bonding often controls
supramolecular organic structures in both natural2 and
synthetic3 systems, metal complexes are more commonly
assembled through coordination chemistry.4 More recently,
the combination of both coordination chemistry and hydrogen
bonding has proved to be particularly useful for assembly
of complex structures.5,6 It is well-known that carboxylic
acids can take part in hydrogen bonding to give centrosym-
metric dimers, and also form other hydrogen bonding motifs
in some cases (Chart 1), and the incorporation of carboxylic
In this paper, the structures arising from supramolecular
assembly of complexes trans-[PdCl2L2] and cis-[Pd(L′L′)-
L2]2+ are reported, where L is a ligand containing both a
pyridine donor and one or two free carboxylic acid groups
that are capable of taking part in hydrogen bonding, and L′L′
is a chelate ligand such as dppm [bis(diphenylphosphino)-
methane] or dppp [bis(diphenylphosphino)propane] to lock
in the cis stereochemistry. The aim was to prepare 1- or 2-D
polymers by self-assembly and, in particular, to study
systematically the opportunities and limitations in the
(3) (a) Alcala, R.; Martines-Carrera, S. Acta Crystallogr. 1972, B28, 1671.
(b) Duchamp, D. J.; Marsh, R. E. Acta Crystallogr. 1969, B25, 5. (c)
Yang, J.; Marendaz, J.-L.; Geib, S. J.; Hamilton, A. D. Tetrahedron
Lett. 1994, 35, 3665. (d) Zafar, A.; Yang, J.; Geib, S. J.; Hamilton,
A. D. Tetrahedron Lett. 1996, 37, 2327. (e) Kolotuchin, S. V.; Fenlon,
E. E.; Wilson, S. R.; Loweth, C. J.; Zimmerman, S. C. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 2654. (f) Seto, C. T.; Whitesides, G. M. J.
Am. Chem. Soc. 1993, 115, 1330. (g) Ashton, P. R.; Collins, A. N.;
Fyfe, M. C. T.; Menzer, S.; Stoddart, J. F.; Williams, D. J. Angew.
Chem., Int. Ed. Engl. 1997, 36, 735. (h) Zimmerman, S. C.; Zeng, F.;
Reichert, D. E. C.; Kolotuchin, S. V. Science 1996, 271, 1095. (i)
Simard, M.; Su, D.; Wuest, J. D. J. Am. Chem. Soc. 1991, 113, 4696.
* Author to whom correspondence should be addressed. E-mail:
pudd@uwo.ca.
(1) (a) Lehn, J.-M. Angew. Chem., Int. Ed. Engl. 1990, 29, 1304-1319.
(b) Conn, M. M.; Rebek, J., Jr. Chem. ReV. 1997, 97, 1647. (c)
Desiraju, G. R. Angew. Chem., Int. Ed. Engl. 1995, 34, 2311. (d) Philp,
D.; Stoddart, J. F. Angew. Chem., Int. Ed. Engl. 1996, 35, 1154. (e)
Lawrence, D. S.; Jiang, T.; Levett, M. Chem. ReV. 1995, 95, 2229.
(2) Jeffery, G. A.; Saenger, W. Hydrogen Bonding in Biological Systems;
Springer-Verlag: Berlin, 1994.
5174 Inorganic Chemistry, Vol. 41, No. 20, 2002
10.1021/ic020239b CCC: $22.00 © 2002 American Chemical Society
Published on Web 09/10/2002

Self-Assembly of Polymers and Sheets
Chart 1
Chart 2
combined use of carboxylic acid units and coordination
chemistry of palladium(II) for self-assembly of interesting
structures. Some of the results have been communicated,6a,b
and the hydrogen bonding in related carboxamide derivatives
has been described.6k
1
ligands, as monitored by the H NMR spectra. Complexes
5-7 which either contain bulky organic substituents (5) or
relatively flexible pyridyl groups (6, 7) are also soluble in
dimethyl formamide (DMF). The complexes were character-
ized by elemental analysis, by their IR and 1H NMR (when
soluble) spectra, and, in some cases, by X-ray structure
determinations. The IR spectra as Nujol mulls for the
complexes contain peaks due to ν(OH) ) 2568-3226 cm-1
and ν(CdO) ) 1697-1735 cm-1, as expected if the
carboxylic groups are involved in hydrogen bonding.7
Results and Discussion
Neutral Palladium(II) Complexes with Pyridine or
Quinoline Carboxylic Acid Ligands. Several new com-
plexes trans-[PdCl2L2] (1-7, Chart 2) were prepared by
displacement of the weakly bound benzonitrile ligands in
trans-[PdCl2(PhCN)2] by corresponding ligands L or by the
displacement of two chloride ligands from Na2[PdCl4] by
ligands L. All new complexes are yellow, air-stable solids.
These complexes have very limited solubility in most
common organic solvents, but high solubility in dimethyl
sulfoxide (DMSO) which can both break down hydrogen-
bonded polymers and, in some cases, displace the pyridine
ligands from palladium. For example, complex 4 reacted on
dissolution in DMSO with displacement of the pyridyl
Structure determinations were carried out for the com-
plexes [PdCl2(NC5H4-4-COOH)2] (1), [PdCl2(NC5H4-3-
COOH)2] (2), 2‚2DMSO, [PdCl2(2-Ph-NC9H5-4-COOH)2]
(5), and 5‚4DMF. Views of their structures are shown in
Figures 1-6, and selected bond distances and angles are
listed in Tables 1-6. As expected, all three unsolvated
complexes 1, 2, and 5, which were grown by very slow
diffusion of the reagents together (see Experimental Section),
self-assembled into infinite 1-D polymeric chains through
pairwise, intermolecular hydrogen bonding between car-
(4) (a) Lehn, J.-M. Supramolecular Chemistry-Concepts and PerspectiVes;
VCH: New York, 1995. (b) Puddephatt, R. J. Chem. Commun. 1998,
1055. (c) Kickham, J. E.; Loeb, S. J. Inorg. Chem. 1995, 34, 5656.
(d) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. ReV. 2000, 100,
853.
(5) (a) Braga, D.; Grepioni, F.; Desiraju, G. R. Chem. ReV. 1998, 98,
1375. (b) Burrows, A. D.; Chan, C. W.; Chowdhry, M. M.; McGrady,
J. E.; Mingos, D. M. P. Chem. Soc. ReV. 1995, 329. (c) Aakero¨y, C.
B.; Beatty, A. M. Chem. Commun. 1998, 1067. (d) Chowdhry, M.
M.; Mingos, D. M. P.; White, A. J. P.; Williams, D. J. Chem. Commun.
1996, 899. (e) Huch, W. T. S.; Hulst, R.; Timmerman, P.; van Veggel,
F. C. J. M.; Reinhoudt, D. N. Angew. Chem., Int. Ed. Engl. 1997, 36,
1006. (f) Munakata, M.; Wu, L.-P.; Yamamoto, M.; Kuroda-Sowa,
T.; Maekawa, M. J. Am. Chem. Soc. 1996, 118, 3117. (g) Kumar, R.
K.; Balasubramanian, S.; Goldberg, I. Inorg. Chem. 1998, 37, 541.
(h) Aakero¨y, C. B.; Beatty, A. M.; Leinen. D. S. Angew. Chem., Int.
Ed.. 1999, 38, 1815.
(6) (a) Qin, Z.; Jenkins, H. A.; Coles, S. J.; Muir, K. W.; Puddephatt, R.
J. Can. J. Chem. 1998, 77, 155. (b) Qin, Z.; Jennings, M. C.;
Puddephatt, R. J.; Muir, K. W. CrystEngComm 2000, 11. (c) Braga,
D.; Maini, L.; Grepioni, F. Angew. Chem., Int. Ed. 1998, 37, 2240.
(d) Stepnicka, P.; Podlaha, J.; Gyepes, R.; Polasek, M. J. Organomet.
Chem. 1998, 552, 293. (e) Bishop, P.; Marsh, P.; Brisdon, A. K.;
Brisdon, B. J.; Mahon, M. F. J. Chem. Soc., Dalton Trans. 1998, 675.
(f) Desmartin, P. G.; Willianms, A. F.; Bernardinelli, G. New J. Chem.
1995, 19, 1109. (g) Fraser, C. S. A.; Jenkins, H. A.; Jennings, M. C.;
Puddephatt, R. J. Organometallics 2000, 19, 1635. (h) Gianneschi,
N. C.; Tiekink, E. R. T.; Rendina, L. M. J. Am. Chem. Soc. 2000,
122, 8474. (i) Schneider, W.; Bauer, A.; Schmidbaur, H. Organome-
tallics 1996, 15, 5445. (j) Wilton-Ely, J. D. E. T.; Schier, A.; Mitzel,
N. W.; Schmidbaur, H. J. Chem. Soc., Dalton Trans. 2001, 7, 1058.
(k) Qin, Z.; Jennings, M. C.; Puddephatt, R. J. Inorg. Chem. 2001,
40, 6220.
boxylic acid groups of the type R2 (8) (Type A, Chart 1).8
2
In each case, the palladium atom lies on a crystallographic
inversion center so that the angles N-Pd-N and Cl-Pd-
Cl are 180°. In the case of complex 1 (Figure 1), the two
pyridine rings are coplanar in the complex molecule because
of crystallographic symmetry, but they twist from the PdN2-
Cl2 coordination plane, with torsion angle C(1)-N(1)-Pd-
(1)-Cl(1) ) 125° (Figure 1). The carboxylic acid group is
essentially coplanar with the pyridine ring to which it is
bonded, with torsion angle C(2)-C(3)-C(4)-O(2) ) -4.5°,
suggesting conjugation between them. Infinite linear chains
were formed because of R22(8) intermolecular carboxylic acid
hydrogen bonding with O‚‚‚H ) 1.71 Å, O‚‚‚H-O ) 179°,
O‚‚‚O ) 2.637(3) Å, typical of such bond parameters in
carboxylic acid derivatives (Figure 1, Table 2).6 The
polymeric chains pack parallel to one another, and there is
some evidence of weak interaction between each chloride
ligand and the pyridyl C(2)-H group of a molecule in an
adjacent chain (Table 2). In addition, the centroid distances
(7) Lambert, J. B.; Shurvell, H. F.; Lightner, D.; Cooks, R. G. Structural
Spectroscopy; Prentice Hall: Englewood Cliffs, NJ, 1998.
(8) Bernstein, J.; Davis, R. E.; Shimoni, L.; Chang, N.-L. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 1555.
Inorganic Chemistry, Vol. 41, No. 20, 2002 5175

Qin et al.
Figure 1. View of part of the 1-D polymeric chain formed by hydrogen
bonding between carboxylic acid substituents in complex 1, and of molecules
in two neighboring chains.
Figure 3. Different orientations of molecules of complex 2 in neighboring
sheets, as required to maximize intersheet CH‚‚‚ClPd or CH‚‚‚OC hydrogen
bonding.
the pyridine ring with regard to the coordination plane PdN2-
Cl2 is similar to that in complex 1, with torsion angle C(1)-
N(1)-Pd(1)-Cl(1) ) 124.5°. Also as in 1, the carboxylic
acid group is approximately coplanar with the pyridyl ring,
as shown by the torsion angle C(1)-C(2)-C(3)-O(1) )
-5.1°. However, the packing motif in 2 is different from
that in 1. There are sheets in which polymeric chains pack
parallel to one another, with weak secondary Pd‚‚‚Cl bonds
(Pd‚‚‚Cl ) 3.42 Å), as shown in Figure 2. However, the
chains in adjacent sheets run crosswise as shown in Figure
3, and there are weak pyridyl C-H‚‚‚ClPd hydrogen bonding
interactions that cross-link the sheets. The overall structure
is compact (note the high density) with very small cavities.
As would be expected, the hydrogen-bonded poly-
meric chains that exist in complex 2 are not present in the
structure of 2‚2DMSO because the DMSO molecules
hydrogen bond to each of the carboxyl groups as shown in
Figure 4. DMSO serves as a strong hydrogen bond acceptor,
as indicated by the hydrogen bonding between the OH groups
in the complex and the SdO groups in DMSO with H‚‚‚O
) 1.74 Å, O-H‚‚‚O ) 171°, O‚‚‚O ) 2.550(3) Å (Tables
Figure 2. View of part of the 1-D zigzag chain formed by hydrogen
bonding between carboxylic acid substituents in complex 2, with pairwise
Cl‚‚‚Pd interactions connecting them to give a sheet structure.
between neighboring pyridyl rings in different polymeric
chains are 3.955 Å, allowing weak π-stacking interactions.
These intermolecular secondary bonding effects lead to a
compact structure in the solid state, with no large cavities
or channels (Figure 1).
The structure of complex 2 is given in Figure 2, with data
in Table 3. It follows from the molecular symmetry that the
COOH groups are located on opposite sides of the PdCl2N2
coordination plane. Thus, zigzag chains are naturally formed
through the intermolecular hydrogen bonding between the
carboxylic acid groups with O‚‚‚H ) 1.94 Å, O‚‚‚H-O )
173°, O‚‚‚O ) 2.634(3) Å (Figure 2). The conformation of
5176 Inorganic Chemistry, Vol. 41, No. 20, 2002

Self-Assembly of Polymers and Sheets
Figure 4. View of the structure of complex 2‚2DMSO, showing
the hydrogen bonding OH‚‚‚O to DMSO molecules. There is also weak
C-H‚‚‚O and O-H‚‚‚S hydrogen bonding that is not illustrated.
Figure 6. View of the structure of 5‚4DMF showing hydrogen bonding
between carboxylic acid groups and DMF solvate molecules. The other
two DMF molecules which are not involved in hydrogen bonding are
omitted for clarity.
Table 1. Selected Bond Distances (Å) and Angles (deg) for Complex 1
Pd(1)-N(1)
C(4)-O(1)
2.021(2)
1.245(4)
Pd(1)-Cl(1)
C(4)-O(2)
2.3051(7)
1.280(4)
N(1)-Pd(1)-Cl(1)
O(1)-C(4)-O(2)
90.48(7)
123.6(3)
O(1)-C(4)-C(3)
O(2)-C(4)-C(3)
120.0(3)
116.4(3)
Table 2. Hydrogen Bonding Interactions and Close Contacts in the
Complexes
H‚‚‚A
(Å)
D‚‚‚A
(Å)
D-H‚‚‚A
(deg)
complex
D-H‚‚‚A
1
O-H‚‚‚O
1.71 2.637(4)
2.77 3.535(4)
1.94 2.634(3)
2.89 3.467(3)
1.74 2.550(3)
2.51 3.263(4)
1.83 2.655(3)
1.79 2.600(2)
2.48 3.214(2)
1.73 2.538(2)
2.47 3.159(2)
2.49 3.408(3)
1.71 2.526(5)
1.87 2.665(3)
2.27 3.087(3)
1.62 2.579(3)
2.01 2.795(3)
3.273(3)
179
142
173
128
171
138
168
172
136
169
131
164
169
161
168
174
174
C(2B)-H‚‚‚Cl(1)
O-H‚‚‚O
2
C(4B)-H‚‚‚Cl(1)
2‚2DMSO O(2)-H‚‚‚O(3A)(DMSO)
C(4)-H‚‚‚O(2B)
5
O-H‚‚‚O
Figure 5. View of the part of the polymeric structure of 5 showing
hydrogen bonding between carboxylic groups.
5‚4DMF
O(1)-H‚‚‚O(5)(DMF)
C(35)-H‚‚‚O(2)
O(4)-H‚‚‚O(6)(DMF)
C(38)-H‚‚‚O(3)
2, 4). A weak O-H‚‚‚S hydrogen bond is also possible
(Figure 4) though the associated parameters indicate that it
is weak [OH‚‚‚S ) 2.69 Å, O-H‚‚‚S ) 158°]. The most
8
9
C(4B)-H‚‚‚O(8)
O(12)-H‚‚‚O(21)(MeOH)
O(12)-H‚‚‚O(21)
O(9)-H‚‚‚Cl
interesting feature is that the centrosymmetric R2 (10) rings
2
formed by weak C-H‚‚‚O-C hydrogen bonding between
neighboring molecules give rise to polymeric chains. The
C-H‚‚‚O-C hydrogen bond’s parameters, H‚‚‚O ) 2.51 Å,
C-H‚‚‚O ) 138°, O‚‚‚C ) 3.263(4) Å, are consistent with
Desiraju’s criteria for the presence of C-H‚‚‚O hydrogen
bonding.9 The structural parameters of the complex molecule
are comparable to those of solvate-free molecule 2 except
that the C-O bond (1.308(4) vs 1.263(4) Å in 2) is longer
and the CdO bond (1.194(4) vs 1.261(4) Å in 2) is shorter,
as expected for the different hydrogen bonding motifs (the
presence of almost equal CO distances in 2 could be a result
of disorder, but the H atoms were located in reasonable
positions so this is considered unlikely; it is an expected
10
11
13
O(2)-H‚‚‚O(3)
O(3)-H‚‚‚O(1)
O(3)-H‚‚‚Cl
O(29)-H‚‚‚O(36)(Otf)
O(19)-H‚‚‚O(w)
O(37)‚‚‚O(w)
1.91 2.724(6)
1.71 2.538(6)
2.862(6)
1.85 2.689(7)
1.87 2.708(7)
1.88 2.722(6)
1.85 2.68(1)
162
169
O(2B)-H‚‚‚O(43A)
O(4B)-H‚‚‚O(11B)
O(2A)-H‚‚‚O(22A)
O(12)-H‚‚‚O(96)(Me2CO)
O(24)-H‚‚‚O(102)(Me2CO) 1.88 2.68(1)
O(19)-H‚‚‚O(47)
O(29)-H‚‚‚O(37)
173
176
175
167
160
159
161
14
17
1.86 2.660(6)
1.86 2.672(4)
result of strong H-bonding). The polymeric chains in
2‚2dmso pack parallel to one another to form a compact
structure. In addition, CH bonds of DMSO take part in weak
C-H‚‚‚Cl-Pd hydrogen bonds involving the Cl-Pd groups
of neighboring chains (not shown).
(9) Desiraju, G. R.; Steiner, T. The Weak Hydrogen Bond in Structural
Chemistry and Biology; Oxford University Press: Oxford, 1999.
Inorganic Chemistry, Vol. 41, No. 20, 2002 5177

Qin et al.
Table 3. Selected Bond Distances (Å) and Angles (deg) for Complex 2
Pd(1)-N(1)
O(1)-C(3)
2.022(2)
1.263(4)
Pd(1)-Cl(1)
O(2)-C(3)
2.3048(7)
1.261(4)
N(1)-Pd(1)-Cl(1)
O(1)-C(3)-O(2)
90.07(7)
123.9(3)
O(1)-C(3)-C(2)
O(2)-C(3)-C(2)
119.3(3)
116.8(3)
Table 4. Selected Bond Distances (Å) and Angles (deg) for Complex
2‚2DMSO
Pd(1)-N(1)
C(3)-O(1)
2.018(2)
1.194(4)
Pd(1)-Cl(1)
C(3)-O(2)
2.2989(9)
1.308(4)
N(1)-Pd(1)-Cl(1)
O(1)-C(3)-O(2)
90.00(7)
124.6(3)
O(1)-C(3)-C(2)
O(2)-C(3)-C(2)
122.6(3)
112.8(3)
Table 5. Selected Bond Distances (Å) and Angles (deg) for Complex 5
Pd-N
O(1)-C(10)
2.035(2)
1.219(3)
Pd-Cl
O(2)-C(10)
2.3078(7)
1.312(3)
N-Pd-Cl
91.79(6)
O(1)-C(10)-C(3)
121.8(2)
O(1)-C(10)-O(2)
125.1(2)
O(2)-C(10)-C(3)
113.1(2)
Table 6. Selected Bond Distances (Å) and Angles (deg) for Complex
5‚4DMF
Figure 7. (a) Molecular structure of complex 8. (b) View of part of the
offset columnar structure; each level is part of a sheet structure formed via
weak C-H‚‚‚O hydrogen bonding (not shown).
Pd(1)-N(2)
Pd(1)-N(1)
Pd(1)-Cl(1)
Pd(1)-Cl(2)
2.006(9)
2.074(9)
2.308(4)
2.315(3)
O(1)-C(8)
O(2)-C(8)
O(3)-C(24)
O(4)-C(24)
1.34(2)
1.15(2)
1.24(2)
1.27(2)
Chart 3
N(2)-Pd(1)-Cl(1)
N(1)-Pd(1)-Cl(1)
N(2)-Pd(1)-Cl(2)
O(2)-C(8)-O(1)
O(2)-C(8)-C(7)
O(1)-C(8)-C(7)
89.6(3)
90.7(3)
90.3(3)
125.3(11)
124.1(11)
110.3(11)
N(1)-Pd(1)-Cl(2)
N(2)-Pd(1)-N(1)
Cl(1)-Pd(1)-Cl(2)
O(3)-C(24)-O(4)
O(3)-C(24)-C(23)
O(4)-C(24)-C(23)
89.4(3)
179.6(5)
179.8(2)
122.3(10)
122.7(11)
114.5(10)
The structure of complex 5 is shown in Figure 5, with
data in Table 5. This complex gives a structure that is
remarkably similar to that of complex 1, with linear chains
assembled through hydrogen bonding and with O‚‚‚H ) 1.83
Å, O‚‚‚H-O ) 168°, O‚‚‚O ) 2.655(3) Å. In contrast to
the ligand orientation in complexes 1 and 2, the quinoline
ring is close to perpendicular to the coordination plane PdN2-
Cl2, as indicated by the Cl-Pd-N-C torsion angles of
-108° and 81°. The dihedral angle between the phenyl and
pyridine rings is 59.2(1)°. The C-C-C(10)-O(1) torsion
angle of 34.8° in 5 indicates that the carboxylic acid group
deviates significantly from the quinoline ring plane. All these
differences probably arise in order to minimize steric contacts
between the two large ligands. It is clear from Figure 5 that
there are intramolecular edge-to-face π-stacking interactions
[centroid distance 4.851 Å] between orthophenylene and
phenyl groups in the complex. There are also intermolecular
π-stacking interactions [centroid distance 3.62 Å] between
quinoline rings and intermolecular π-stacking interactions
between phenyl rings (not shown).
are also different, as shown by the hydrogen bond parameters
(H-atoms were located for this structure, Table 2). The
dihedral angle between the phenyl and quinoline rings (51.4°)
and that between the carboxyl group and the quinoline ring
(16.6°) are smaller than those in unsolvated complex 6.
Pyridine Carboxylate Complex. The reaction of pyridine-
2-carboxylic acid with [PdCl2(PhCN)2] or with Na2[PdCl4]
yielded a white, insoluble product, [Pd(NC5H4-2-C{O}O)2]
(8) (Chart 3). The IR spectrum of 8 displayed two absorption
bands due to ν(CO2) at 1676 and 1606 cm-1, and there was
no band for ν(OsH), indicating that deprotonation of the
carboxylic acid group had occurred with formation of a
palladium carboxylate unit. Crystals of complex 8 were
obtained over a period of several months by diffusion of an
acetone solution of [PdCl2(PhCN)2] into an aqueous solution
of the ligand. The molecular structure of complex 8 is shown
in Figure 7, with selected bond parameters in Table 7. The
coordination sphere around the palladium atom is ap-
proximately square planar with two pyridine-2-carboxylate
ligands coordinated in a bidentate N,O fashion to give a
planar neutral molecule (Figure 7a). The five-membered
There is no interesting supramolecular association in the
structure of 5‚4DMF (Figure 6, Table 6). Two of the four
solvate DMF molecules take part in hydrogen bonding with
the carboxylic groups of the complex molecule to form R2 -
2
(7) rings, which include O-H‚‚‚O and C-H‚‚‚O hydrogen
bonds, as shown in Figure 6, while the third DMF is located
above the R2 (7) rings and has contact with an OH group of
2
the COOH substituent (not shown). The hydrogen bonds
formed by each of the carboxylic acid groups with DMF
5178 Inorganic Chemistry, Vol. 41, No. 20, 2002

Self-Assembly of Polymers and Sheets
Table 7. Selected Bond Distances (Å) and Angles (deg) for Complex 8
Pd-N(1)
Pd-O(9)
1.998(2)
2.003(2)
C(7)-O(8)
C(7)-O(9)
1.213(3)
1.310(4)
N(1)-Pd-O(9)
O(8)-C(7)-O(9)
82.36(9)
124.5(3)
O(8)-C(7)-C(6)
O(9)-C(7)-C(6)
120.5(3)
115.0(3)
chelate ring had a bite angle NsPdsO ) 82.36(9)°, similar
to values in other pyridine-2-carboxylate complexes.10 The
palladium atom lies at a crystallographic inversion center
so that the angles NsPdsN and OsPdsO are 180°. The
CdO bond length (1.213(3) Å) and the CsO bond length
(1.310(4) Å) are typical.10 The molecules stack into columns
with Pd‚‚‚Pd ) 3.71 Å (Figure 7b), and with π-stacking
attractions between unsaturated groups.11 There are also weak
intermolecular CdO‚‚‚HsC hydrogen bonds, with the
distances O‚‚‚H ) 2.49 Å and O‚‚‚C ) 3.408(3) Å and angle
OsH‚‚‚C ) 164°, that cross-link the columns to give an
infinite 3-D network. The intermolecular attractions that give
rise to the overall network structure are presumably respon-
sible for the complex being insoluble. Clearly, the easy
deprotonation of the carboxylic acid group to give a chelated
carboxylate group is a limitation on the use of ortho
substituted carboxylic acid groups in supramolecular chem-
istry.
Neutral Palladium(II) Complexes with Pyridine Dicar-
boxylic Acid Ligands. Two complexes, [PdCl2{NC5H3-3,5-
(COOH)2}] (9) and [PdCl2{2,6-Me2-NC5H3-3,5-(COOH)2}]
(10), (Chart 3) were synthesized by displacement of the
weakly bound benzonitrile ligands of trans-[PdCl2(PhCN)2]
in THF by the corresponding ligand. Both are pale yellow,
air-stable solids. Unlike complexes 1 and 2, which are
insoluble in most organic solvents, both complexes 9 and
10 are soluble in THF, methanol, and ethanol, although the
ligands have very limited solubility in these solvents.
The structure of 9‚2MeOH is shown in Figure 8, and
selected bond distances and angles are given in Table 8. Each
molecule of 9 lies on an inversion center and displays the
expected trans-[PdCl2L2] structure (Figure 8a). The two
pyridine rings are approximately perpendicular to the PdN2-
Cl2 square coordination plane, as indicated by the torsion
angle Cl-Pd-N-C ) 88.1°. The two carboxylic acid groups
in each ligand lie in the plane of the pyridine ring, but they
are oriented so that their hydroxyl groups are respectively
syn and anti with respect to the palladium atom. The anti
carboxylic acid groups are related by the inversion center,
and they take part in hydrogen bonding mediated by
methanol molecules. This hydrogen bonding forms planar
Figure 8. (a) View of the structure of 9‚2MeOH, showing the hydrogen
bonding to methanol solvate molecules. (b) View of part of the sheet
structure formed by combination of hydrogen-bonded R4 (12) rings and
4
O-H‚‚‚Cl units.
Table 8. Selected Bond Distances (Å) and Angles (deg) for Complex 9
Pd-N(1)
C(7)-O(8)
C(7)-O(9)
2.005(3)
1.192(5)
1.330(4)
Pd-Cl
C(10)-O(11)
C(10)-O(12)
2.301(1)
1.210(5)
1.288(5)
N(1)-Pd-Cl
91.66(9)
O(9)-C(7)-C(5)
O(11)-C(10)-O(12)
O(11)-C(10)-C(3)
112.0(3)
125.5(4)
120.7(4)
O(8)-C(7)-O(9)
O(8)-C(7)-C(5)
O(12)-C(10)-C(3)
125.2(4)
122.7(3)
113.8(4)
rings containing pairs of palladium atoms are formed (Figures
8a, 8b). Because the chloride ligands of each PdCl2 group
hydrogen bond to the carboxylic groups of different zigzag
chains, the combination of the two hydrogen bonding
schemes leads to the corrugated 2-D structure shown in
Figure 8b. The overall structure is compact, and there are
no cavities which might give rise to further solvent inclusion.
Complex 10 was recrystallized from acetone by slow
evaporation to give the solvate 10‚4H2O, whose structure is
shown in Figure 9. There is also evidence for disordered
acetone molecules in the crystals. The molecules of 10
display crystallographic 2/m (C2h) symmetry. In the mol-
ecules of 10, the pyridine rings are tilted by only 6° from
orthogonality with the PdN2Cl2 coordination plane despite
the steric crowding that results from the two extra o-methyl
groups in each pyridine ring. The Pd-N bonds (Table 9) in
centrosymmetric R4 (12) rings (Type B, Chart 1) and gives
4
a zigzag chain structure. The zigzag chains pack parallel to
one another, and pairs of Pd atoms in adjacent chains are
interlinked by hydrogen bonding between the syn carbox-
ylic acid groups and chloride ligands [O‚‚‚Cl 3.087(3) Å,
H‚‚‚Cl 2.27 Å, O-H‚‚‚Cl 168°]. Centrosymmetric R2 (16)
2
(10) (a) Hoare, J. L.; Cavell, K. J.; Hecker, R.; Skelton, B. W.; White, A.
H. J. Chem. Soc., Dalton Trans. 1996, 2197. (b) Jin, H.; Cavell, K.
J.; Skelton, B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 1995,
2159.
(11) (a) Hunter, C. A.; Sanders, J. K. M. J. Am. Chem. Soc. 1990, 112,
5525. (b) Hunter, C. A. Chem. Soc. ReV. 1994, 23, 101.
Inorganic Chemistry, Vol. 41, No. 20, 2002 5179

Qin et al.
Chart 4
carboxylic acid group takes part in hydrogen bonding
mediated by water molecules, thereby forming slightly
puckered, centrosymmetric R4 (12) rings (Type B, Chart 1),
4
similar to those formed in 2-benzoylbenzoic acid.12 The water
molecules also take part in weak hydrogen bonding to the
chloride ligands. The final outcome of the self-assembly
process is the formation of stacks of molecules related by
translation along the c-axis. Adjacent molecules of 10 within
each stack are held together by Cl‚‚‚HsO(water) and Cd
O‚‚‚HsO(water) hydrogen bonds from the same water
molecule, while R4 (12) rings link each stack to its four
4
nearest neighbors (Figure 9b). Channels running parallel to
c are thereby formed which are large enough (144 Å3 per
cell) to accommodate disordered molecules of acetone.13 The
nature of the hydrogen bonding network in 10 suggests that
the solid should be resistant to degradation by heating. This
expectation is fulfilled: thermogravimetric analysis indicated
no weight loss on heating to 200 °C, and only ∼4% weight
loss at 260 °C; the decomposition temperature was 264 °C.
This high thermal stability suggests the potential use of
complex 10 as a functional porous material.
Cationic Palladium(II) Complexes with Pyridine Car-
boxylic Acid Ligands. A great number of cationic palla-
dium(II) supramolecules, including squares, cages, and
catenanes, have been synthesized using chelated cis-palla-
dium(II) precursors,4d and several cationic palladium(II)
complexes containing two or four carboxylic acid groups
(Chart 4), which have the potential to self-assemble by
supramolecular association via hydrogen bonding, were
prepared similarly. The reactions of [Pd(dppp)(OTf)2] (OTf
) triflate)14 or [Pd(dppm)(OTf)2] with carboxylic acid or
dicarboxylic acid pyridyl ligands gave the compounds 11-
19 in high yields (Chart 4). All complexes are air-stable,
colorless solids, albeit hygroscopic. The complexes were
Figure 9. (a) View of the structure of 10‚4H2O and (b) view of part of
the sheet structure formed by hydrogen bonding with a cross section of the
porous channel structure.
1
characterized by elemental analysis and IR, H NMR, and
31P{1H} NMR spectra. Those with dppp as chelate ligand
give 31P NMR signals in the range δ ) 9.15-10.15, with
the exception of 15 whose 31P resonance is at 16.26 ppm. In
the case of the dppm chelated complexes, their 31P signals
ranged from -36.99 to -38.97 ppm.
Table 9. Selected Bond Distances (Å) and Angles (deg) for Complex
10
Pd-N
O(1)-C(5)
2.063(3)
1.213(4)
Pd-Cl
O(2)-C(5)
2.311(1)
1.310(4)
N-Pd-Cl
O(1)-C(5)-O(2)
90.0
123.6(3)
O(1)-C(5)-C(2)
O(2)-C(5)-C(2)
124.1(3)
112.3(2)
X-ray crystal structure determinations were carried out for
four of the cationic palladium(II) complexes. Views of their
10 are 0.06 Å longer than those in 9, thereby helping to
relieve short intramolecular H‚‚‚H and H‚‚‚Pd contacts
involving the three hydrogen atoms of the methyl group.
Crystallographic symmetry requires the four carboxylic acid
groups in a molecule to be equivalent. The OH groups in 10
therefore are all anti to the Pd atom, as is shown by the
C(1)sC(2)sC(5)sO(2) torsion angle of -169.1(3)°. Each
(12) Lalancette, R. A.; Vanderhoff, P. A.; Thompson, H. W. Acta
Crystallogr. 1990, C46, 1682.
(13) (a) Spek, A. L. Acta Crystallogr., Sect. A 1990, 46, C34. (b) Spek, A.
L. PLATON, A Multipurpose Crystallographic Tool; Utrecht Univer-
sity: Utrecht: The Netherlands, 1998.
(14) (a) Doyle, J. R.; Slade, P. E.; Jonassen, H. B. Inorg. Synth. 1960, 6,
216. (b) Stang, P. J.; Cao, D. H.; Saito, S.; Arif, A. M. J. Am. Chem.
Soc. 1995, 117, 6273.
5180 Inorganic Chemistry, Vol. 41, No. 20, 2002

Self-Assembly of Polymers and Sheets
Figure 10. View of the structure of complex 11 showing hydrogen bonding
between carboxylic acid groups and water molecule as well as triflate anion,
leading to a polymeric structure. Phenyl groups are omitted for clarity.
Figure 12. (a) View of the molecular structure of 13 showing hydrogen
bonding between COOH groups and triflate counter ions. (b) View of part
of the chain structure formed via hydrogen bonding and O‚‚‚Pd interactions.
Only one of the two independent molecules is shown.
Figure 11. (a) View of the molecular structure of 17 showing hydrogen
bonding between COOH groups and triflate counter ions. (b) View of part
of the chain structure (all phenyl groups are omitted for clarity) formed by
H-bonding and O‚‚‚Pd interactions.
structures are shown in Figures 10-13. The coordination
geometry about the cationic palladium(II) metal centers is
roughly square planar in each case. The potential intermo-
lecular hydrogen bonding between carboxyl groups was not
present in any case, but the carboxylic acid groups take part
in hydrogen bonding with either triflate anions or solvate
acetone molecules.
Figure 13. View of the molecular structure of complex 14 showing
hydrogen bonding between COOH groups and solvate acetone molecules
and O‚‚‚Pd interaction. The other solvates and phenyl groups are omitted
for clarity.
The structure of [Pd(dppp)(NC5H4-4-COOH)2](CF3SO3)2
(11) is shown in Figure 10, while selected bond distances
and angles are given in Table 10. There is cis-PdP2N2
coordination, and the pyridine rings lie roughly orthogonal
to the coordination plane. The two carboxylic acid groups
are approximately coplanar to the pyridine rings to which
they are connected. One carboxylic acid group takes part in
hydrogen bonding O(19)-H(19A)‚‚‚O(w) [O(19)‚‚‚O ) 2.54
Å] with a solvate water molecule, while the other carboxylic
acid group forms hydrogen bonding O(29)-H(29A)‚‚‚O(36)
(OTf) [O(29)‚‚‚O(36) ) 2.72 Å] with a triflate anion (Figure
10). The second oxygen atom of the triflate anion hydrogen
bonds to the water molecule [O(37)‚‚‚O ) 2.86 Å]. The
combination of the hydrogen bonding interactions leads to
an infinite polymeric chain, as shown in Figure 10. The
adjacent polymeric chains further aggregate to give a 2-D
sheet structure through the contacts Pd‚‚‚O(38) ) 3.11 Å.
In the structure of complex 17 shown in Figure 11 (see
also Table 11), both carboxylic acid groups in the complex
Inorganic Chemistry, Vol. 41, No. 20, 2002 5181

Qin et al.
Table 10. Selected Bond Distances (Å) and Angles (deg) for Complex
Table 13. Selected Bond Distances (Å) and Angles (deg) for Complex
11
14
Pd-N(11)
2.098(3)
2.103(3)
1.176(6)
1.305(6)
Pd-P(2)
2.2734(10)
2.2806(11)
1.197(6)
Pd-N(11)
Pd-N(21)
2.115(6)
2.120(6)
Pd-P(1)
Pd-P(2)
2.264(2)
2.272(2)
Pd-N(21)
Pd-P(1)
C(17)-O(18)
C(17)-O(19)
C(27)-O(28)
C(27)-O(29)
N(11)-Pd-N(21)
N(11)-Pd-P(2)
N(11)-Pd-P(1)
83.1(2)
93.58(17)
175.79(18)
P(1)-Pd-P(2)
N(21)-Pd-P(1)
N(21)-Pd-P(2)
90.13(9)
93.05(18)
175.25(18)
1.329(6)
N(11)-Pd-N(21)
N(11)-Pd-P(2)
N(11)-Pd-P(1)
O(18)-C(17)-O(19) 124.1(5)
O(18)-C(17)-C(14) 123.6(5)
O(19)-C(17)-C(14) 112.2(4)
83.90(14) P(2)-Pd-P(1)
91.43(9) N(21)-Pd-P(1)
177.24(10) N(21)-Pd-P(2)
91.12(4)
93.53(10)
175.22(10)
while the other one does not form an interesting supramo-
lecular structure.
No noteworthy supramolecular structure was formed in
the highly solvated crystal of 14‚5.35(acetone) (Table 13),
but the carboxylic acids take part in hydrogen bonding to
acetone molecules or triflate anion as shown in Figure 13.
O(28)-C(27)-O(29) 125.0(4)
O(28)-C(27)-C(24) 122.8(4)
O(29)-C(27)-C(24) 112.2(4)
Table 11. Selected Bond Distances (Å) and Angles (deg) for Complex
17
Pd-N(21)
Pd-N(11)
C(17)-O(18)
C(17)-O(19)
2.114(3)
2.124(2)
1.231(7)
1.297(7)
Pd-P(2)
Pd-P(1)
C(27)-O(28)
C(27)-O(29)
2.2589(11)
2.2671(11)
1.204(5)
Conclusions
1.327(5)
Both neutral and cationic palladium(II) complexes con-
taining carboxylic acid groups that are capable of taking part
in hydrogen bonding can be readily prepared, and the nature
and scope of the subsequent self-assembly have been
determined in many cases. The complexes trans-[PdCl2L2],
where L ) NC5H4-4-COOH, NC5H4-3-COOH, 2-Ph-NC9H5-
4-COOH, can self-assemble to give 1-D polymers through
N(21)-Pd-N(11)
N(11)-Pd-P(2)
N(11)-Pd-P(1)
O(18)-C(17)-O(19) 124.0(5)
O(18)-C(17)-C(13) 121.8(5)
O(19)-C(17)-C(13) 114.2(5)
92.92(11) P(2)-Pd-P(1)
71.58(4)
98.82(10)
169.61(10)
96.74(7)
N(21)-Pd-P(1)
N(21)-Pd-P(2)
168.26(7)
O(28)-C(27)-O(29) 124.6(4)
O(28)-C(27)-C(23) 122.4(4)
O(29)-C(27)-C(23) 113.0(4)
Table 12. Selected Bond Distances (Å) and Angles (deg) for Complex
13
formation of pairwise O-H‚‚‚O hydrogen bonds giving R2 -
2
Pd(A)-N(1A)
Pd(A)-N(2A)
Pd(A)-P(2A)
Pd(A)-P(1A)
2.104(5)
2.110(5)
2.2721(19)
2.2784(19)
Pd(B)-N(1B)
Pd(B)-N(2B)
Pd(B)-P(2B)
Pd(B)-P(1B)
2.100(5)
2.118(5)
2.277(2)
2.2803(19)
(8) rings, as shown by structure determinations of the
complexes 1, 2, and 5 (Figures 1-3 and 5). However,
crystallization from DMSO or DMF gave the solvated
complexes 2‚2DMSO and 5‚4DMF, in which hydrogen
bonding to solvent molecules is preferred (Figures 4 and 6).
Interestingly, in complex 2‚2DMSO, the molecules take part
in weak intermolecular C-H‚‚‚O hydrogen bonding leading
to a 1-D polymeric tape structure. Pyridine-2-carboxylic acid
gave a neutral chelate complex, [Pd(NC5H4C{O}O)2], in
which deprotonation of the carboxylic acid group occurred,
thus illustrating a limitation of this approach to forming
hydrogen-bonded polymers. The complex forms stacked
columns in the solid state with CO‚‚‚HC hydrogen bonding
cross-linking them to give a highly insoluble complex with
a 3-D network structure (Figure 7).
N(1A)-Pd(A)-N(2A) 87.56(18) N(1B)-Pd(B)-N(2B) 87.44(19)
N(1A)-Pd(A)-P(2A) 176.75(15) N(1B)-Pd(B)-P(2B) 178.52(14)
N(2A)-Pd(A)-P(2A)
N(1A)-Pd(A)-P(1A)
90.33(14) N(2B)-Pd(B)-P(2B)
92.86(14) N(1B)-Pd(B)-P(1B)
91.51(15)
91.01(14)
N(2A)-Pd(A)-P(1A) 178.75(15) N(2B)-Pd(B)-P(1B) 178.35(15)
P(2A)-Pd(A)-P(1A)
89.19(7) P(2B)-Pd(B)-P(1B)
90.05(7)
molecule lie on the same side of the cis-PdN2P2 coordination
plane, and they are twisted out of the pyridyl planes.
However, they are oriented differently so that one adopts
the anti conformation with respect to the pyridyl nitrogen
atom while the other is syn. Each of the carboxylic acid
groups takes part in hydrogen bonding O-H‚‚‚O(OTf) with
one triflate counterion (Figure 11). Furthermore, one of the
oxygen atoms of a triflate interacts with the palladium(II)
center of the adjacent molecule [Pd‚‚‚O(36) ) 2.935 Å],
finally leading to a coiled polymeric chain (Figure 11b).
The complexes trans-[PdCl2L2], 9‚2MeOH and 10‚4H2O,
containing pyridine dicarboxylic acid ligands, form similar
R4 (12) rings by hydrogen bonding between carboxylic acid
4
groups mediated by methanol or water molecules. However,
in 9‚2MeOH, half of the carboxylic acid groups take part in
that type of hydrogen bonding while the other half form
hydrogen bonds with Cl-Pd groups, forming an interesting
2-D sheet structure (Figure 8). In 10‚4H2O, all carboxylic
acid groups form the same type of hydrogen bonding, leading
to formation of 2-D sheets with large cavities (Figure 9).
The 2-D sheets pack together to give a porous crystal
structure with channels along the c-axis.
Several new cationic palladium(II) complexes containing
pyridine carboxylic acid ligands were prepared, but there was
no hydrogen bonding between the carboxylic groups. Instead,
anions or solvate molecules take part in hydrogen bonding
with the carboxylic acid groups. However, interesting su-
pramolecular structures were obtained through the combina-
tion of hydrogen bonding between the carboxylic acid groups
There are two independent but similar molecules in the
structure of 13‚0.875(acetone) (Figure 12 and Table 12). As
expected, the sulfur atoms in the ligands do not coordinate
to the palladium(II) center. The orientation of the CH2COOH
groups in the two independent molecules is different. Three
of the four carboxylic groups take part in hydrogen bonding
with triflate counterions, while one does not. All hydrogen
bonding parameters can be found in Table 2. There are close
interactions between an oxygen atom of a triflate anion and
a palladium(II) center in both independent molecules, with
Pd(A)‚‚‚O(33A) ) 3.06 Å and Pd(B)‚‚‚O(41) ) 2.89 Å,
respectively. One molecule (PdB in the crystal structure)
gives polymeric chains through the combination of hydrogen
bonding and Pd‚‚‚O interactions, as shown in Figure 12b,
5182 Inorganic Chemistry, Vol. 41, No. 20, 2002

Self-Assembly of Polymers and Sheets
[PdCl2(NC9H6-3-COOH)2] (4). To a solution of [Pd(PhCN)2Cl2]
(95.8 mg, 0.25 mmol) in a 1:1 benzene/methanol mixture (10 mL)
was added a solution of quinoline-3-carboxylic acid (86.6 mg, 0.50
mmol) in a 1:1 benzene/methanol mixture (10 mL). A yellow
precipitate was formed rapidly. The mixture was stirred for 2 h.
The pale yellow powder was obtained by filtration, washed with
acetone, and dried in vacuo. Yield: 91%. Anal. Calcd for C20H14-
Cl2N2O4Pd: C, 45.87; H, 2.69; N, 5.35. Found: C, 45.55; H, 2.69;
N, 5.23. IR (Nujol): ν(CdO) 1710 cm-1, νOH ) 2652 cm-1. Mp:
350 °C, decomposed. Because this complex can only be dissolved
in DMSO and there is an exchange between the ligand and DMSO,
good NMR spectra cannot be obtained.
and triflate counteranions and secondary Pd‚‚‚O bonding
interactions (Figures 10 and 11). Given this competition for
hydrogen bonding, it is clearly necessary to choose recrys-
tallization solvents and counterions carefully when designing
new materials. Carboxamide groups hydrogen bond more
strongly than carboxylic acids and so give a wider range of
supramolecular structures in palladium(II) complexes,6k but
the carboxylic acids do give novel and interesting 1-D
polymer and 2-D network structures. There is clearly scope
for further developments.
Experimental Section
[PdCl2(2-Ph-NC9H5-4-COOH)2] (5). To a solution of [Pd-
(PhCN)2Cl2] (95.9 mg, 0.25 mmol) in benzene (10 mL) was added
a solution of 2-phenyl-quinoline-4-carboxylic acid (124.7 mg, 0.50
mmol) in acetone (10 mL). A yellow precipitate was formed after
2 h. The mixture was stirred for a further 2 h. The yellow powder
was obtained by filtration, washed with acetone, and dried in vacuo.
Yield: 80%. Anal. Calcd for C32H22Cl2N2O4Pd: C, 56.87; H, 3.28;
N, 4.14. Found: C, 56.20; H, 3.34; N, 4.00. IR (Nujol): νCdO 1715
cm-1, νOH ) 2610 cm-1. 1H NMR (DMF-d7): δ 9.11 (d, 3JHH ) 8
Hz, 2H, H8); 8.71 (dd, 3JHH ) 8 Hz, 4JHH ) 1 Hz, 2H, H5); ∼8.21-
8.30 (br, m, 4H, H6,7); ∼7.78-8.14 (br, m, 12H, 2H3 + 2Ph). Mp:
294 °C, decomposed. Single crystals of 5 were obtained by a
diffusion reaction of 2-phenyl-quinoline-4-carboxylic acid solution
in acetone and [Pd(PhCN)2Cl2] solution in toluene. Single crystals
of 5‚4DMF were obtained from saturated DMF solution of the
complex. TGA indicated solvent loss over the temperature range
70-150 °C.
NMR spectra were recorded by using a Varian Gemini 300 NMR
spectrometer. 1H and 13C{1H} chemical shifts are reported relative
to tetramethylsilane(TMS). 31P{1H} chemical shifts were referenced
to 85% H3PO4 as an external reference. Infrared spectra were
recorded as Nujol mulls on a Perkin-Elmer 2000 FTIR spectrometer.
All manipulation of air- or water-sensitive materials was carried
out using standard Schlenk techniques under an atmosphere of
nitrogen or in a drybox. [PdCl2(PhCN)2], [Pd(dppp)(CF3SO3)2], and
[Pd(dppm)(CF3SO3)2] were prepared following the literature pro-
cedures.14
[PdCl2(NC5H4-4-COOH)2] (1). To an aqueous solution (10 mL)
of Na2[PdCl4] (0.50 mmol), prepared in situ by the reaction of PdCl2
and NaCl, was added pyridine-4-carboxylic acid (123.1 mg, 1.00
mmol) in distilled water (10 mL). A pale yellow precipitate was
formed immediately. The mixture was stirred for a further 2 h to
ensure completion of the reaction. The solid was collected by
filtration, washed with distilled water and acetone, and dried in
vacuo to afford a pale yellow powder. Yield: 93%. Anal. Calcd
for C12H10Cl2N2O4Pd: C, 34.03; H, 2.38; N, 6.61. Found: C, 33.51;
H, 2.46; N, 6.17. IR (Nujol): νCdO 1705 cm-1, νOH ) 2568, 2677
cm-1. 1H NMR (DMF-d7): δ 9.10 (d, 3JHH ) 7 Hz, 4H, H2,6); 8.07
[PdCl2(NC5H4-4-CH2COOH)2] (6). It was prepared by a similar
procedure as for 1 except that 4-pyridylacetic acid was used. A
pale yellow product was obtained. Yield: 82%. Anal. Calcd for
C14H14Cl2N2O4Pd: C, 37.23; H, 3.12; N, 6.20. Found: C, 37.13;
H, 3.14; N, 6.04. IR (Nujol): νCdO 1735 cm-1, νOH ) 3226 cm-1
.
3
1H NMR (CD3OD/CD3CN): δ 8.65 (d, JHH ) 7 Hz, 4H, H2,6);
3
(d, JHH ) 7 Hz, 4H, H3,5). 13C{1H} NMR (DMSO-d6): δ 164.7
3
7.37 (d, JHH ) 7 Hz, 4H, H3,5); 3.80 (s, 4H, CH2). Mp: 300 °C,
(COOH), 154.0 (C2), 140.7 (C3), 124.4 (C4). Mp: >350 °C,
decomposed. Yellow needle crystals of 1 were obtained by slow
diffusion of [PdCl2(PhCN)2] in acetone into a solution of pyridine-
4-carboxylic acid in water in about one month.
decomposed.
[PdCl2(NC5H4-4-SCH2COOH)2] (7). This compound was pre-
pared by a similar procedure as for 1 except that (4-pyridylthio)-
acetic acid was used. A yellow product was obtained. Yield: 84%.
Anal. Calcd for C14H14Cl2N2O4PdS2: C, 32.61; H, 2.74; N, 5.43.
[PdCl2(NC5H4-3-COOH)2] (2). This was prepared by a similar
procedure as for 1 except that pyridine-3-carboxylic acid was used.
The product was obtained as a yellow solid. Yield: 96%. Anal.
Calcd for C12H10Cl2N2O4Pd: C, 34.03; H, 2.38; N, 6.61. Found:
Found: C, 31.55; H, 2.74; N, 5.09. IR (Nujol): νCdO 1719 cm-1
,
1
3
νOH ) 2608 cm-1. H NMR (DMF-d7): δ 8.56 (d, JHH ) 7 Hz,
3
4H, H2,6); 7.51 (d, JHH ) 7 Hz, 4H, H3,5); 4.22 (s, 4H, SCH2);
C, 34.14; H, 2.39; N, 6.44. IR (Nujol): νCdO 1706 cm-1, νOH
)
1
4
2667, 2776 cm-1. H NMR (DMF-d7): δ 9.41 (d, JHH ) 2 Hz,
13.62 (br s, COOH). Mp: 222 °C, decomposed.
2H, H2); 9.13 (dd, 3JHH ) 6 Hz, 4JHH ) 2 Hz, 2H, H6); 8.58 (ddd,
[Pd(NC5H4-2-C{O}O)2] (8). This compound was prepared by
a similar procedure as for 1 except that pyridine-2-carboxylic acid
was used. The product was obtained as a white solid. Yield: 99%.
The compound also can be synthesized by the reaction of [PdCl2-
(PhCN)2] and pyridine-2-carboxylic acid in acetone. Anal. Calcd
for C12H8N2O4Pd: C, 41.11; H, 2.30; N, 7.99. Found: C, 40.22;
4
4
3
3JHH ) 8 Hz, JHH ) 2 Hz, JHH ) 2 Hz, 2H, H4); 7.83 (dd, JHH
) 8 Hz, 3JHH ) 6 Hz, 2H, H5). 13C{1H} NMR (DMSO-d6): δ 164.2
(COOH), 156.3 (C2), 153.5 (C6), 140.0 (C3), 128.4 (C4), 125.6 (C5).
Mp: >350 °C, decomposed. Yellow needle crystals of 2‚2DMSO
were grown from a saturated solution of 2 in DMSO. TGA showed
weight loss of DMSO from 165 to 180 °C. Yellow needle crystals
of 2 were obtained by slow diffusion of pyridine-3-carboxylic acid
in methanol into a solution of [PdCl2(PhCN)2] in chloroform in
about one month.
H, 2.28; N, 7.70. IR (Nujol): νCdO 1676 cm-1 (s); νC-O 1606
-
cm-1 (m). Mp: >330 °C, decomposed. Colorless needle crystals
of 3 were obtained by slow diffusion of [PdCl2(PhCN)2] in acetone
into a solution of pyridine-2-carboxylic acid in water in about 2
months.
[PdCl2(NC9H6-4-COOH)2] (3). This compound was prepared
by a similar procedure as for 1 except that quinoline-4-carboxylic
acid was used. The product was obtained as a pale yellow solid.
Yield: 95.8%. Anal. Calcd for C20H14Cl2N2O4Pd: C, 45.87; H,
2.69; N, 5.35. Found: C, 45.55; H, 2.69; N, 5.23. IR (Nujol): νCd
[PdCl2(NC5H3-3,5-(COOH)2)2] (9). To a solution of pyridine-
3,5-dicarboxylic acid (66.8 mg, 0.40 mmol) in THF (30 mL) was
added [Pd(PhCN)2Cl2] (76.7 mg, 0.20 mmol), giving a yellow
solution. The resulting solution was stirred for 3 h and then was
concentrated to 10 mL, and pentane (50 mL) was added, giving a
yellow precipitate. The yellow powder was obtained by filtration,
washed with pentane, and dried in vacuo. Yield: 95%. Anal. Calcd
1697 cm-1, νOH ) 2628 cm-1. Mp: 330 °C, decomposed. The
O
complex was soluble only in DMSO, but it decomposed rapidly so
that NMR spectra could not be recorded.
Inorganic Chemistry, Vol. 41, No. 20, 2002 5183

Qin et al.
Table 14. Crystallographic Data for the Complexes
1
2
2‚2DMSO
8
5
5‚4DMF
formula
C12H10Cl2N2O4Pd
C12H10Cl2N2O4Pd
C16H22Cl2N2-
O6PdS2
C12H8N2O4Pd
C32H22Cl2N2O4Pd
C44H50Cl2N6O8Pd
fw
423.52
423.52
579.78
350.60
675.82
968.20
temp (K)
λ (Å)
295(2)
0.71073
triclinic, P1h
295(2)
294(2)
0.71073
triclinic, P1h
200(2)
150(2)
0.69150
triclinic, P1h
294(2)
0.71073
triclinic, P1
0.71073
monoclinic,
P21/c
0.71073
monoclinic,
P21/c
cryst syst,
space group
a (Å)
b (Å)
c (Å)
3.9554(2)
7.4830(4)
12.5456(7)
75.625(3)
88.898(3)
80.313(3)
354.47(3), 1
1.984
3.92340(10)
13.5352(6)
13.4180(6)
90
96.0520(10)
90
708.58(5), 2
1.985
1.702
4.7722(10)
10.139(2)
12.788(3)
107.353(10)
90.549(10)
96.331(10)
586.4(2), 1
1.642
3.7077(2)
12.8197(5)
11.5267(6)
90
91.008(3)
90
547.80(5), 2
2.126
1.706
8.145(2)
9.422(2)
10.092(2)
65.601(2)
75.142(2)
78.015(3)
677.2(3), 1
1.657
7.9009(2)
9.3964(2)
15.9253(2)
77.992(1)
77.342(1)
82.234(1)
1123.34(3), 1
1.431
R (deg)
â (deg)
γ (deg)
V (Å3), Z
D
calcd (g/cm3)
µ (mm-1
F(000)
)
1.701
208
1.230
292
0.925
340
0.590
500
416
344
θ range (deg)
1.68-24.99
2.14-27.49
-4 to 5
-13 to 19
-19 to 16
6533
2.12-24.98
3.18-27.49
-4 to 4
-16 to 16
-14 to 14
7363
2.2-27.0
-10 to 9
-12 to 12
-12 to 13
3927
1.33-25.00
-10 to 10
-12 to 12
-21 to 19
7079
range h
-5 to 5
0 to 6
range k
range l
-8 to 10
-15 to 17
3711
1251
0.3522, 0.3118
-12 to 12
-17 to 17
1933
reflns collected
unique reflns
max and min
transmn
1618
0.2790, 0.2451
1933
1933
0.9196, 0.7266
2752
0.870, 0.577
7079
0.2790, 0.2451
GOF on F2
final R indices
[I >2σ(I)]
1.021
R1 ) 0.0238
1.026
R1 ) 0.0275
1.065
R1 ) 0.0278
0.997
R1 ) 0.0271
1.017
R1 ) 0.0353
1.083
R1 ) 0.0304
wR2 ) 0.0582
R1 ) 0.0271
wR2 ) 0.0690
R1 ) 0.0387
wR2 ) 0.0769
R1 ) 0.0306
wR2 ) 0.0625
R1 ) 0.0447
wR2 ) 0.0949
R1 ) 0.0364
wR2 ) 0.0835
R1 ) 0.0418
R indices
(all data)
wR2 ) 0.0607
wR2 ) 0.0752
wR2 ) 0.0784
wR2 ) 0.0664
wR2 ) 0.0954
wR2 ) 0.1078
11‚ClCH2CH2-
Cl‚H2O
9‚2CH3OH
10‚4H2O
13
14
17
formula
C16H18Cl2N2O10Pd
C18H26Cl2N2O12Pd
C43H40Cl2F6N2-
O11P2PdS2
1178.13
200(2)
0.71073
orthorhombic,
Pbca
19.8192(2)
17.1480(2)
29.6791(2)
90
C
45.63H45.25F6N2-
10.88 P2Pd S4
C
59.05H68.10F6-
N2O19.35P2PdS2
C
39.50H32ClF6-
N2O10P2Pd S2
O
fw
temp (K)
λ (Å)
cryst syst,
space group
a (Å)
575.62
215(2)
0.71073
triclinic, P1h
639.71
150(2)
0.69150
monoclinic, C2/m
1206.17
150(2)
0.71073
triclinic, P1h
1461.92
150(2)
0.71073
monoclinic, P2(1)/c
1076.58
200(2)
0.71073
orthorhombic,
Pbcn
14.2300(2)
24.6236(3)
25.7343(3)
90
4.9006(4)
7.9416(9)
14.2851(15)
97.815(6)
99.871(6)
100.030(6)
531.42(9), 1
1.799
11.625(2)
20.765(4)
6.5940(10)
90
116.12(3)
90
1429.2(4), 2
1.487
0.891
12.24(3)
19.737(4)
23.865(5)
75.76(3)
84.96(3)
72.70(3)
5340.9(19), 4
1.500
12.6459(8)
39.284(3)
14.8286(9)
90
107.204(3)
90
7036.9(8), 4
1.380
0.451
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3), Z
90
90
90
90
10086.73(17), 8
1.552
0.700
9017.1(2), 8
1.586
0.716
D
calcd (g/cm3)
µ (mm-1
F(000)
)
1.181
288
0.641
2456
648
4768
3013
4336
θ range (deg)
3.60-30.05
2.12-27.07
-14 to 15
-26 to 20
-8 to 8
4263
2.59-27.53
-25 to 25
-22 to 22
-38 to 38
3927
4.08-25.36
4.08-20.63
-12 to 12
-30 to 38
-14 to 14
18113
2.70-27.48
-18 to 18
-31 to 31
-33 to 33
132331
range h
0 to 6
0 to 14
range k
range l
-11 to 11
-20 to 19
6582
3043
0.8245, 0.7729
-22 to 23
-28 to 28
51930
19353
0.9535, 0.8309
reflns collected
unique reflns
max and min
transmn
1594
161575
0.8308, 0.7101
6768
0.9520, 0.9313
10342
0.9651, 0.8139
GOF on F2
final R indices
[I > 2σ(I)]
1.038
R1 ) 0.0516
1.051
R1 ) 0.0438
1.054
R1 ) 0.0555
0.916
R1 ) 0.0590
1.094
R1 ) 0.0677
1.018
R1 ) 0.0560
wR2 ) 0.0985
R1 ) 0.0744
wR2 ) 0.1087
R1 ) 0.0473
wR2 ) 0.1570
R1 ) 0.0862
wR2 ) 0.1364
R1 ) 0.1371
wR2 ) 0.1682
R1 ) 0.0836
wR2 ) 0.1772
R1 ) 0.0870
R indices
(all data)
wR2 ) 0.1085
wR2 ) 0.1107
wR2 ) 0.1794
wR2 ) 0.1593
wR2 ) 0.1778
wR2 ) 0.1945
for C14H10Cl2O8N2Pd‚H2O: C, 31.75; H, 2.28; N, 5.29. Found: C,
31.45; H, 2.60; N, 5.00. IR (Nujol): νCdO 1721, 1745 cm-1; νOH
2521 cm-1. 1H NMR (CD3OD): δ 9.54 (d, 4JHH ) 2 Hz, 4H, H2,6);
(COOH), 158.28 (C2), 141.57 (C3), 129.97 (C4). Mp: 316 °C,
decomposed. Single crystals of 9‚2MeOH suitable for X-ray
structure determination were obtained from the solution of the
complex in methanol by very slow evaporation in several months.
4
8.94 (t, JHH ) 2 Hz, 2H, H4). 13C{1H} NMR (CD3OD): 164.96
5184 Inorganic Chemistry, Vol. 41, No. 20, 2002

Self-Assembly of Polymers and Sheets
[PdCl2(2,6-Me2-NC5H-3,5-(COOH)2)2] (10). It was prepared
by a similar procedure as for 9 except that 2,6-dimethyl-pyridine-
3,5-dicarboxylic acid was used and the reaction was carried out
for 24 h, because of the insolubility of the ligand in THF. A yellow
product was obtained. Yield: 96%. Anal. Calcd for C18H18Cl2N2O8-
Pd‚2H2O‚2THF: C, 41.75; H, 5.12; N, 3.75. Found: C, 41.38; H,
[Pd(dppp)(2,6-Me2-NC5H-3,5-(COOH)2)2] (CF3SO3)2 (15).
This compound was prepared in a similar way as for 11 except
that 2,6-dimethyl-pyridine-3,5-dicarboxylic acid was used. A white
product was obtained. Yield: 77%. Anal. Calcd for C47H44F6N2O14P2-
PdS2: C, 46.76; H, 3.67; N, 2.32. Found: C, 47.21; H, 3.93; N,
1
2.08. IR (Nujol): νCdO 1730, 1648 cm-1; νOH 3462 cm-1 (s). H
NMR (acetone): δ 8.03 (s, 2H, H4); ∼7.10-7.95 (br m, 20H, 4
Ph); 3.15 (br, 4H, PCH2); 2.30 (br, 2H, PCH2CH2); 2.97 (br s, 12H,
CH3). 31P{1H} NMR (acetone): δ 16.26 (s). Mp: 195 °C.
[Pd(dppm)(NC5H4-4-COOH)2] (CF3SO3)2 (16). This compound
was prepared in a similar way as for 11 except that [Pd(dppm)-
(CF3SO3)2] was used. White product was obtained. Yield: 88%.
Anal. Calcd for C39H32F6N2O10P2PdS2: C, 45.25; H, 3.12; N, 2.71.
5.03; N, 3.88. IR (Nujol): νCdO 1698, 1724 cm-1; νOH 2626 cm-1
.
1H NMR (acetone): δ 8.84 (s, 2H, H4); 4.13 (s, 12H, CH3); 3.62
(m, 8H, O-CH2/THF), 1.78 (m, 8H, CH2/THF). 13C{1H} NMR
(acetone): 165.82 (COOH), 165.40 (C2), 143.38 (C3), 127.20 (C4),
26.84 (CH3). THF: 67.99, 26.10. Mp: 245 °C, decomposed. Single
crystals of 10‚4H2O were grown from an acetone solution of the
complex.
Found: C, 44.80; H, 3.17; N, 2.59. IR (Nujol): ν(CdO) 1733 cm-1
;
[Pd(dppp)(NC5H4-4-COOH)2] (CF3SO3)2 (11). To a mixture
of [Pd(dppp)2(SO3CF3)2] (81.7 mg, 0.10 mmol) and pyridine-4-
carboxylic acid (24.6 mg, 0.20 mmol) was added THF (15.0 mL).
The resulting solution changed in color from yellow to colorless.
The solution was stirred for a total of 4 h and then was concentrated
to about 5 mL. After pentane (50 mL) was added to the described
solution, a white precipitate was formed. The white solid product
was obtained by filtration, washed with pentane, and dried in vacuo.
Yield: 90%. Anal. Calcd for C41H36F6N2O10P2PdS2: C, 46.32; H,
ν
OH 2655, 3462. 1H NMR (acetone): δ 9.23 (br s, 4H, H2,6 -Py);
7.96 (br m, 12H, H3,5-Py + H2,6-Ph); 7.66 (br m, 4H, H4-Ph);
2
7.53 (br m, 8H, H3,5-Ph); 5.23 (t, JPH ) 12.0 Hz, 2H, PCH2);
12.50 (br s, 2H, COOH). 31P{1H} NMR (acetone): δ ) -36.99
(s). Mp: 146 °C.
[Pd(dppm)(NC5H4-3-COOH)2] (CF3SO3)2 (17). This compound
was prepared in a similar way as for 16 except that pyridine-3-
carboxylic acid was used. A white solid product was obtained.
Yield: 97%. Anal. Calcd for C39H32F6N2O10P2PdS2: C, 45.25; H,
3.41; N, 2.63. Found: C, 46.02; H, 3.65; N, 2.50. IR (Nujol): νCd
3.12; N, 2.71. Found: C, 45.46; H, 3.21; N, 2.57. IR (Nujol): νCd
1
1732 cm-1; νOH 3455 cm-1. H NMR (acetone): δ 9.22 (br s,
O
1
1730 cm-1; νOH 2665, 3437 cm-1. H NMR (acetone): δ 9.39
4H, H2,6); ∼7.20-7.80 (br m, 24H, H3,5-Py + 4Ph); 3.40 (br, 4H,
PCH2); 2.40 (br, 2H, PCH2CH2); 12.00 (br, COOH). 31P{1H} NMR
(acetone): δ 9.15 (s). Mp: 176 °C. Colorless single crystals of 11
were grown from a solution of the complex in 1,2-dichloroethane/
hexane.
O
(br s, 2H, H6 -Py); 9.34 (s, 2H, H2 -Py); 8.53 (br, 2H, H4 -Py);
7.78 (br, 2H, H5-Py); 7.96 (br m, 8H, H2,6-Ph); 7.66 (br m, 4H,
H4-Ph); 7.53 (br m, 8H, H3,5-Ph); 5.27 (t, JPH ) 12 Hz, 2H,
2
PCH2). 31P{1H} NMR (acetone): δ ) -37.93 (s). Mp: 198 °C,
decomposed. Colorless single crystals of 17 were obtained from a
solution of the complex in 1,2-dichloroethane/acetone/hexane.
[Pd(dppm)(NC5H4-4-SCH2COOH)2] (CF3SO3)2 (18). This
compound was prepared in a similar way as for 16 except that
pyridine-3-carboxylic acid was used. The product was obtained as
a white solid. Yield: 88%. Anal. Calcd for C41H36F6N2O10P2PdS4:
C, 43.68; H, 3.22; N, 2.48. Found: C, 43.10; H, 3.32; N, 2.37. IR
[Pd(dppp)(NC5H4-3-COOH)2] (CF3SO3)2 (12). This compound
was prepared in a similar way as for 11 except that pyridine-3-
carboxylic acid was used. A white solid product was obtained.
Yield: 90%. Anal. Calcd for C41H36F6N2O10P2PdS2: C, 46.32; H,
3.41; N, 2.63. Found: C, 46.56; H, 3.31; N, 2.50. IR (Nujol): νCd
1
1746 cm-1; νOH 3189 cm-1. H NMR (acetone): δ 9.43 (br, s,
O
2H, H2); 9.27 (br, s, 2H, H6); 8.18 (br, s, 2H, H4); ∼7.30-7.80 (br
m, 22H, H5-Py + 4Ph); 3.40 (br, 4H, PCH2); 2.40 (br, 2H, PCH2-
CH2); 12.00 (br s, 2H, COOH). 31P{1H} NMR (acetone): δ 9.38
(s). Mp: 192 °C. Colorless single crystals of 12 were obtained from
a solution of the complex in THF/pentane.
1
(Nujol): νCdO 1727, 1628 cm-1; νOH 2665, 3457 cm-1. H NMR
(acetone): δ 8.72 (br s, 4H, H2,6 -Py); 8.10 (br s, 4H, H3,5-Py);
7.40-7.90 (br m, 20H, H of Ph); 5.15 (br, 2H, PCH2); 4.08 (br s,
4H, SCH2). 31P{1H} NMR (acetone): δ ) -37.62 (s). Mp: 152
°C, decomposed.
[Pd(dppp)(NC5H4-4-SCH2COOH)2] (CF3SO3)2 (13). This com-
pound was prepared in a similar way as for 11 except that
(4-pyridylthio)acetic acid was used. A white product was obtained.
Yield: 81%. Anal. Calcd for C43H40F6N2O10P2PdS4: C, 44.70; H,
Pd(dppm)(NC5H3-3,5-(COOH)2)2] (CF3SO3)2 (19). This com-
pound was prepared in a similar way as for 16 except that pyridine-
3,5-dicarboxylic acid was used. The product was obtained as a white
solid. Yield: 90%. Anal. Calcd for C41H32F6N2O14P2PdS2: C, 43.81;
H, 2.87; N, 2.49. Found: C, 43.59; H, 2.93; N, 247. IR (Nujol):
3.49; N, 2.42. Found: C, 44.67; H, 3.24; N, 2.31. IR (Nujol): νCd
1
1727 cm-1; νOH 3450 cm-1. H NMR (acetone): δ 8.62 (br s,
ν
CdO 1734 cm-1; νOH 2655, 3457 cm-1. 1H NMR (acetone): δ 9.67
O
4H, H2,6); 7.02 (br s, 4H, H3,5); ∼7.24-7.90 (br m, 20H, 4Ph);
3.34 (br, 4H, PCH2); 2.40 (br, 2H, PCH2CH2); 3.92 (s, 4H, SCH2).
31P{1H} NMR (acetone): δ 9.19 (s). Mp: 179 °C. Colorless single
crystals of 13 were obtained from a solution of the complex in
acetone/pentane.
(br s, 4H, H2,6); 8.82 (s, 2H, H4-Py); 7.42-8.06 (m, 20H, 4Ph);
5.35 (br, 2H, PCH2). 31P NMR (acetone): δ -38.97 (s). Mp: 178
°C, decomposed.
X-ray Structure Determinations. Crystals were mounted on
glass fibers. Data were collected using a Nonius Kappa-CCD
diffractometer and Mo X-rays except for the poorly diffracting
crystals 5 and 10‚4H2O for which it was necessary to use
synchtrotron radiation in conjunction with a Bruker SMART
[Pd(dppp)(NC5H3-3,5-(COOH)2)2] (CF3SO3)2 (14). This com-
pound was prepared in a similar way as for 11 except that pyridine-
3,5-dicarboxylic acid was used. A white product was obtained.
Yield: 83%. Anal. Calcd for C43H36F6N2O14P2PdS2: C, 44.68; H,
(15) Programs used. For structure solution and refinement: Sheldrick, G.
M. SHELXTL 5.1; Institu¨t fu¨r Anorganische Chemie der Universita¨t:
Go¨ttingen, Germany, 1998. For data collection and processing: (a)
Otwinowski, Z.; Minor, W. COLLECT (Nonius) and DENZO-
SCALEPACK. Processing of X-ray Diffraction Data Collected in
Oscillation Mode; Methods in Enzymology, Volume 276, Macromo-
lecular Crystallography, part A; Carter, C. W.; Sweet, R. M., Eds.;
Academic Press: New York, 1997; p 307-326. (b) SAINT & SADABS;
Bruker: Madison, WI, 1995.
3.15; N, 2.43. Found: C, 44.74; H, 3.59; N, 2.18. IR (Nujol): νCd
O
1
1734, 1641 cm-1; νOH 3447 cm-1. H NMR (acetone): δ 9.68
(br s, 4H, H2,6); 8.55 (br s, 2H, H4); ∼7.20-7.90 (br m, 20H, 4
Ph); 3.40 (br, 4H, PCH2); 2.40 (br, 2H, PCH2CH2). 31P{1H} NMR
(acetone): δ 10.14 (s). Mp: 210 °C. Single crystals of 14‚5.35-
(acetone) were grown by slow evaporation of an acetone solution.
The complex easily lost acetone of solvation at room temperature.
Inorganic Chemistry, Vol. 41, No. 20, 2002 5185

Qin et al.
diffractometer. In all cases, cell dimensions were derived from the
complete data set. The structures were solved by direct methods
and refined by least squares on F2. Anisotropic thermal parameters
were applied to all non-hydrogen atoms. A summary of crystal-
lographic data can be found in Table 14.15
to EPSRC for synchrotron beam time at the C.L.R.C.
Daresbury Laboratory, Warrington, U.K.
Supporting Information Available: Crystal data in CIF format.
This material is available free of charge via the Internet at
http://pubs.acs.org.
Acknowledgment. We thank the NSERC (Canada) for
financial support, and R.J.P. thanks the Government of
Canada for a Canada Research Chair. We are also grateful
IC020239B
5186 Inorganic Chemistry, Vol. 41, No. 20, 2002