Cyclometallated [C,N,O] complexes as metalloligands: Synthesis and structural characterisation of new Di-, Tri-, tetra- And pentanuclear heterometallic complexes

Article abstract of DOI:10.1002/ejic.200900052

Reaction of the Schiff-base ligands 4-(4-NC₅H₄)C ₆H₄C(H)=N(C₆H₃OH-₂-tBu-5) (a) and (4-NC₅H₄)C(H)=N(C₆H ₃OH-2-tBu-S) (b) with palladium(II) acetate in toluene at 60 °C gave the tetranuclear orthometallated palladium complexes 1a and 1b, respectively, as air-stable solids. Treatment of la and lb with triphenylphosphane gave the mononuclear species 2a and 2b upon splitting of the polynuclear structure. Reaction, of la with the tertiary diphosphanes Ph ₂P(CH₂)₄PPh₂ (dppb), Fe(C ₅H₄PPh₂)₂ (dppf), Ph ₂PC(H)=C(H)PPh₂ (tdppe) and. Ph₂P(CH ₂)₆PPh₂ (dpph), and lb with dppb and dppf, in a 1:2 molar ratio gave complexes 3a-6a and 3b and 4b, respectively, Reaction of 2a, 4a and 6a with hexacarbonyl.chrom.ium. or -tungsten and 2b and 3b with hexacarbonylchromium, -molybdenum, or -tungsten in thf under UV activation gave complexes 7a-12a and 5b-10b, respectively, which contain an M(CO)₅ fragment coordinated to the pyridine nitrogen atom. Treatment of 2b with [RuCl₂(CO)(dmf)(PPh3J₂] in chloroform at room temperature for 2 d afforded 11b. Treatment of ligands (2-NC₅H ₄)C(H)=N(C₆H₄OH-2) (c) and (2-NC ₅H₄)C(H)=N(C₆H₃OH- ₂-tBu-5) (d) with palladium(II) acetate yielded the mononuclear palladium acetate complexes 1c and 1d, respectively. Treatment of 1c and 1d with aqueous sodium chloride, or, alternatively, treatment of c and d with K ₂[PdCl₄], gave chloropalladium complexes 2c and 2d, respectively. Treatment of 2c and. 2d with silver Perchlorate and triphenylphosphane in acetone gave the mononuclear phosphane complexes 3c and 3d, respectively.

Full text of DOI:10.1002/ejic.200900052

FULL PAPER
DOI: 10.1002/ejic.200900052
Cyclometallated [C,N,O] Complexes as Metalloligands: Synthesis and
Structural Characterisation of New Di-, Tri-, Tetra- and Pentanuclear
Heterometallic Complexes
Nina Gómez-Blanco,[a] Jesús J. Fernández,*[a] Alberto Fernández,[a]
Digna Vázquez-García,[a] Margarita López-Torres,[a] and José M. Vila*[b]
Keywords: Palladium / Metallation / Phosphanes / Polynuclear complexes / Carbonyl complexes / Metalloligands
Reaction of the Schiff-base ligands 4-(4-NC5H4)C6H4C-
(H)=N(C6H3OH-2-tBu-5) (a) and (4-NC5H4)C(H)=N(C6H3-
OH-2-tBu-5) (b) with palladium(II) acetate in toluene at 60 °C
gave the tetranuclear orthometallated palladium complexes
1a and 1b, respectively, as air-stable solids. Treatment of 1a
which contain an M(CO)5 fragment coordinated to the pyr-
idine nitrogen atom. Treatment of 2b with [RuCl2(CO)(dmf)-
(PPh3)2] in chloroform at room temperature for 2 d afforded
11b. Treatment of ligands (2-NC5H4)C(H)=N(C6H4OH-2) (c)
and (2-NC5H4)C(H)=N(C6H3OH-2-tBu-5) (d) with palladi-
and 1b with triphenylphosphane gave the mononuclear spe- um(II) acetate yielded the mononuclear palladium acetate
cies 2a and 2b upon splitting of the polynuclear structure.
Reaction of 1a with the tertiary diphosphanes Ph2P(CH2)4-
PPh2 (dppb), Fe(C5H4PPh2)2 (dppf), Ph2PC(H)=C(H)PPh2 (t-
dppe) and Ph2P(CH2)6PPh2 (dpph), and 1b with dppb and
dppf, in a 1:2 molar ratio gave complexes 3a–6a and 3b and
4b, respectively. Reaction of 2a, 4a and 6a with hexacarbon-
ylchromium or -tungsten and 2b and 3b with hexacarbon-
ylchromium, -molybdenum or -tungsten in thf under UV acti-
vation gave complexes 7a–12a and 5b–10b, respectively,
complexes 1c and 1d, respectively. Treatment of 1c and 1d
with aqueous sodium chloride, or, alternatively, treatment of
c and d with K2[PdCl4], gave chloropalladium complexes 2c
and 2d, respectively. Treatment of 2c and 2d with silver per-
chlorate and triphenylphosphane in acetone gave the mono-
nuclear phosphane complexes 3c and 3d, respectively.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
nuclear complexes containing a monodentate phosphane,
thus giving rise to a new class of bidentate [P,S] chelating
metalloligands capable of coordinating a second metal cen-
tre and therefore with possible uses as building blocks in
the construction of polynuclear structures.[13]
In our quest for new types of metalloligands bearing cy-
clometallated units, we have recently studied metallacycles
containing pyridine and pyrimidine rings. Although the lat-
ter have been extensively studied as building blocks in the
construction of supramolecular assemblies,[14–22] few exam-
ples in which the heterocyclic ring is part of a cyclometall-
ated ligand have been reported.[23–25]
Herein we describe the synthesis of new terdentate
[C,N,O] palladacycles bearing uncoordinated pyridine rings,
a new type of metalloligand which is capable of forming
di-, tri-, tetra- or pentanuclear complexes with up to three
different metal centres.
Introduction
The field of cyclometallation chemistry is an area of
growing importance.[1] Metallacycles exhibit interesting lu-
minescent and electronic properties[2] and are used as
metallomesogens[3] in medicine and biology[4] and in cata-
lytic and synthetic processes.[5] Furthermore, they possess
potential applications as chiral auxiliaries[6] and are widely
used as building blocks in supramolecular species.[7]
We have been interested in the study of cyclometallated
complexes derived from terdentate [C,N,O] ligands such as
Schiff bases with phenolate oxygen atoms,[8–12] which form
tetranuclear structures with eight-membered Pd4O4 cores.
We have also shown that the related tetranuclear species
derived from terdentate [C,N,S] thiosemicarbazones react
with bis(diphenylphosphanyl)methane to give new mono-
[a] Departamento de Química Fundamental, Universidade da Co-
ruña,
15071 A Coruña, Spain
Results and Discussion
Fax: +34-981-167065
E-mail: qiluaafl@udc.es
[b] Departamento de Química Inorgánica, Universidad de Santi-
ago de Compostela
For the convenience of the reader, the compounds and
reactions discussed herein are shown in Schemes 1, 2 and 3.
All compounds described in this paper were characterised
15782 Santiago de Compostela, Spain
Fax: +34-981-595012
E-mail: josemanuel.vila@usc.es
by elemental analysis (C, H, N), IR and H and 31P{1H}
1
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NMR spectroscopy and, in part, FAB and ESI mass spec- H) stretch also indicates loss of the OH proton. The
trometry and X-ray single-crystal diffraction (data in the ν(C=N) band is shifted to lower wavenumber with respect
Experimental Section).
to that of the free ligand due to N-coordination of the im-
Treatment of the Schiff-base ligands a and b with palladi- ine.[26,27] In the H NMR spectra, absence of the H6 and
um(II) acetate in toluene at 60 °C gives the tetranuclear or- OH resonances is in agreement with metallation of the li-
tho-metallated palladium complexes 1a and 1b, respectively, gand and OH deprotonation, respectively. All resonances
as air-stable solids. The absence of ν(COO) bands in the IR were found to be highfield-shifted with respect to those of
spectra precluded formation of the dinuclear species with the uncoordinated ligand, with the most noticeable shifts
bridging acetate ligands typically obtained when using pal- corresponding to the H5 and HC=N signals. The low δ val-
ladium(II) acetate as the metal salt; the absence of an ν(O– ues for these signals arise from the tetrameric structure of
1
Scheme 1. (i) Pd(OAc)2, toluene, 60 °C; (ii) PPh3, acetone (1:4); (iii) Ph2PRPPh2, chloroform or acetone (1:2); (iv) Fe(C5H4PPh2)2, dichlo-
romethane (1:2); (v) M(CO)6, UV (365 nm), thf.
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Cyclometallated [C,N,O] Complexes as Metalloligands
Scheme 2. (i) Pd(OAc)2, toluene, 60 °C; (ii) PPh3, dichloromethane (1:4); (iii) Ph2P(CH2)4PPh2, dichloromethane (1:2); (iv) Fe(C5H4PPh2)2,
dichloromethane (1:2); (v) M(CO)6, UV (365 nm), thf; (vi) [RuCl2(CO)(dmf)(PPh3)2], chloroform.
the complexes, which places these protons in the proximity
of the shielding zone of the phenyl rings of a neighbouring
metallated unit; a similar behaviour has been described by
us previously.[8,10,11]
In the absence of an X-ray structural analysis for 1a and
1b, we tentatively assign a tetranuclear formulation on the
basis of the mass spectrometric data and of our previous
findings in related compounds. Thus, the FAB mass spectra
display a cluster of peaks with the characteristic isotopic
pattern corresponding to the tetranuclear structure (m/z =
1740 and 1434 for 1a and 1b, respectively). The mass spec-
trum of 1a also shows peaks assigned to fragments corre-
sponding to two thirds and one half of the molecular mass.
Treatment of 1a and 1b with triphenylphosphane gave
the mononuclear species 2a and 2b, respectively, due to
splitting of the polynuclear structure by Pd–Obridging bond
1
cleavage. The H NMR spectra of 2a and 2b show the H5
Scheme 3. (i) Pd(OAc)2, toluene, 60 °C; (ii) NaCl, water/methanol;
and HC=N proton resonances coupled to the 31P nucleus
(iii) K2[PdCl4], water/ethanol (complex 2c); (iv) AgClO4, PPh3, ace-
tone (1:1).
[4JP,H = 1.8 (2a) and 3.8 Hz (2b) for H5 and ca. 10 Hz for
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HC=N]. In the 31P{1H} spectra, the unique phosphorus 31P nuclei, in accordance with the symmetric nature of the
resonance is a singlet at δ ≈ 34.5 ppm for 2a and δ ≈ dinuclear complexes. The FAB mass spectra of these com-
33.0 ppm for 2b; these findings are in agreement with the plexes show a set of peaks assigned to the molecular ions,
phosphorus atom being trans to the nitrogen atom.[8,10,11] with the corresponding isotopic patterns. The crystal struc-
The HC=N proton resonances [δ = 7.98 (2a) and 7.86 ppm ture of 4a was determined by single-crystal X-ray diffrac-
(2b)] are lowfield-shifted with respect to those for 1a and tion, thereby confirming the proposed structure.
1b, whereas the H5 resonances [δ = 6.37 (2a) and 7.18 ppm
(2b)] are shifted to high field due to shielding of the phos-
Crystal Structure of 4a
phane phenyl rings.[8,10,11] The FAB mass spectra show the
peaks assigned to the molecular ions (m/z = 693 and 630
for 2a and 2b, respectively).
Suitable crystals were grown by slowly concentrating a
1,2-dichloroethane/dichloromethane/n-hexane solution of
Reaction of 1a with the tertiary diphosphanes Ph2P- the complex. The molecular structure is illustrated in Fig-
(CH2)4PPh2 (dppb), Fe(C5H4PPh2)2 (dppf), Ph2PC(H)= ure 1. Crystal data are given in the Experimental Section,
C(H)PPh2 (t-dppe) and Ph2P(CH2)6PPh2 (dpph) and of 1b and selected bond lengths and angles with estimated stan-
with dppb and dppf, in a 1:2 molar ratio gave complexes dard deviations are listed in Table 1.
3a–6a and 3b and 4b, respectively. The IR and NMR spec-
The asymmetric unit comprises one half molecule of 4a
tra of these complexes were found to be similar to those of with an inversion centre located on the Fe atom of the dppf
the mononuclear triphenylphosphane complexes 2a and 2b. ligand. The structure consists of discrete trinuclear mole-
1
Thus, the H NMR spectra show coupling of the H5 and cules in which two cyclometallated moieties are bridged by
HC=N resonances to the 31P nuclei. Only one singlet is ob- a dppf ligand. The palladium atoms are coordinated to the
served in the 31P{1H} NMR spectra for the two equivalent Schiff-base ligand through the C(6) carbon atom of the
Figure 1. Molecular structure of 4a with labelling scheme. Hydrogen atoms have been omitted for clarity.
Table 1. Selected bond lengths [Å] and angles [°] for complexes 2c, 3c and 4a.
2c
3c
4a
Pd(1)–N(1)
Pd(1)–N(2)
Pd(1)–O(1)
Pd(1)–Cl(1)
N(1)–Pd(1)–N(2)
N(2)–Pd(1)–O(1)
O(1)–Pd(1)–Cl(1)
N(1)–Pd(1)–Cl(1)
N(1)–Pd(1)–O(1)
N(2)–Pd(1)–Cl(1)
2.018(4)
1.945(4)
2.012(3)
2.295(2)
81.0(2)
84.2(2)
92.3(1)
98.6(1)
165.2(2)
176.3(1)
Pd(1)–N(1)
Pd(1)–N(2)
Pd(1)–O(1)
Pd(1)–P(1)
N(1)–Pd(1)–N(2)
N(2)–Pd(1)–O(1)
O(1)–Pd(1)–P(1)
N(1)–Pd(1)–P(1)
N(1)–Pd(1)–O(1)
N(2)–Pd(1)–P(1)
2.069(3)
1.989(3)
2.016(2)
2.300(1)
79.7(1)
Pd(1)–C(6)
Pd(1)–N(1)
Pd(1)–O(1)
Pd(1)–P(1)
C(6)–Pd(1)–N(1)
N(1)–Pd(1)–O(1)
O(1)–Pd(1)–P(1)
C(6)–Pd(1)–P(1)
C(6)–Pd(1)–O(1)
N(1)–Pd(1)–P(1)
1.982(7)
2.022(5)
2.101(5)
2.275(2)
81.7(2)
79.4(2)
102.7(1)
96.5(2)
83.4(1)
92.61(7)
104.40(8)
162.6(1)
175.62(9)
160.7(2)
174.8(2)
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Cyclometallated [C,N,O] Complexes as Metalloligands
phenyl ring, the N(1) atom, the phenolate O(1) oxygen in some cases are possibly due to the aforementioned insta-
atom, and the P(1) phosphorus atom of the coordinated bility.
dppf in a slightly distorted square-planar geometry. The
The reaction of 2b with [RuCl2(CO)(dmf)(PPh3)2] in
angles between adjacent atoms in the coordination sphere chloroform at room temperature for 2 d afforded 11b. The
of the palladium atom are close to the expected value of IR spectrum of this complex shows a strong band at
90°, with the most noticeable distortions corresponding to 1943 cm–1 assigned to the ν(CO) stretch. Its 1H NMR spec-
N(1)–Pd(1)–O(1) [79.4(2)°] and O(1)–Pd(1)–P(1) [102.7(1)°]. trum is similar to that of the parent complex 2b, although
The sum of the angles around the palladium atom is ca. the H3 resonance is shifted considerably upfield to δ =
360°.
5.43 ppm due to the presence of the ruthenium fragment
The Pd(1)–N(1) [2.022(5) Å] and Pd(1)–O(1) [2.101(5) Å] coordinated to the adjacent nitrogen atom. The 31P{1H}
bond lengths are similar to others reported for related com- NMR spectrum shows two singlets assigned to the 31P nu-
pounds;[8,28–30] the Pd(1)–O(1) bond length shows the clei of the triphenylphosphane ligands bonded to the palla-
strong trans influence of the C(6) carbon atom.
dium atom [δ = 31.3 ppm (1 P)] and ruthenium [δ =
The geometry around the palladium atom [Pd(1), C(6), 22.5 ppm (2 P)] atoms. The ESI mass spectrum shows a
N(1), O(1), P(1)] is planar (r.m.s. = 0.060, plane1). The cluster of peaks centred at m/z = 1311 for the molecular
metallated ring [Pd(1), C(1), C(6), C(7), N(1), plane 2] and ion.
the coordination ring [Pd(1), N(1), C(8), C(13), O(1), plane
The reaction of c and d with palladium(II) acetate
3] are also planar (r.m.s. = 0.016 and 0.048, respectively). yielded the mononuclear acetate complexes 1c and 1d,
Planes 1, 2, 3, the metallated phenyl ring and the phenol respectively, rather than the expected tetranuclear com-
ring are approximately coplanar.
pounds (see above). The ν(C=N) stretch in the IR spectra
The reaction of 2a, 4a and 6a with hexacarbonylchro- of these complexes [1572 (1c) and 1566 cm–1 (1d)] is shifted
mium or -tungsten, and of 2b and 3b with hexacarbon- to lower wavenumbers with respect to those of the free li-
ylchromium, -molybdenum or -tungsten, in thf under UV gands due to N-coordination of the ligands.[26,27] The differ-
activation gave 7a–12a and 5b–10b (see Schemes 1 and 2), ences between the strong bands assigned to the symmetric
which contain an M(CO)5 fragment coordinated to the pyr- and asymmetric ν(COO) vibrations in the IR spectra [237
idine nitrogen atom.
(1c) and 216 cm–1 (1d)] are in agreement with terminal ace-
The IR spectra of the complexes show three bands in the tate ligands[34] (see Experimental Section). Loss of the OH
carbonyl region characteristic of [M(CO)5L] complexes proton was confirmed by the absence of the ν(O–H) band
1
1
with pseudo C4v symmetry.[31–33] The H NMR spectra are and the OH signal in the IR and H NMR spectra, respec-
similar to those of the parent complexes 2a, 4a, 6a, 2b and tively, and the presence of the H2 proton resonance in the
3b, with only minor shifts in all resonances. The most no- 1H NMR spectra precluded metallation of the pyridine
table difference corresponds to the protons adjacent to the ring. However, the H5 resonance was found to be shifted
pyridine nitrogen atom, where the H15/H17 resonances are by around 0.8 ppm to high field due to coordination
shifted upfield in the spectra of complexes with the pyridine through the pyridine nitrogen atom. The HC=N resonance
ring coordinated to the Cr(CO)5 fragment and to low field was also shifted by ca. +0.3 ppm, thereby indicating coordi-
in those coordinated to W(CO)5. In the spectra of the b nation through the imine nitrogen atom. This shift is
derivatives, the H3 and H5 resonances are lowfield-shifted smaller than that observed in the tetrameric complexes 1a
[δ(H3,H5): Cr(CO)5 complex Ͻ Mo(CO)5 complex Ͻ and 1b. The FAB mass spectra show peaks centred at m/z =
W(CO)5 complex]. The mass spectra of all complexes show 303 (1c) and 359 (1d) assigned to loss of the acetate ligand.
a set of peaks assignable to the molecular ions (see Experi-
mental Section).
Treatment of 1c and 1d with aqueous sodium chloride,
or, alternatively, treatment of c and d with K2[PdCl4], gave
The complexes are all air-stable as solids, although in complexes 2c and 2d, respectively, after acetate/chlorine ex-
solution they decompose to give, in some cases, intractable change. Complex 2c has been prepared previously by treat-
1
mixtures. The derivatives of ligand b are considerably more ment of the ligand with Li2[PdCl4].[35] The H NMR and
stable than those of a, and complexes prepared with the IR spectra show absence of the O2CMe resonance and of
carbonylmolybdenum reagent are less stable than their the ν(COO) bands, respectively. The molecular structure of
chromium or tungsten analogues. This is probably the complex 2c was determined by X-ray single-crystal diffrac-
reason why we were unable to prepare the carbonylmolyb- tion.
denum complexes from ligand a or, in cases where only
small amounts of complexes were obtained, they could not
be isolated. We have also observed that decomposition oc-
curs much faster in acetone, acetonitrile or alcohols than in
chloroform, dichloromethane or thf. In fact, the b deriva-
Crystal Structure of 2c
Suitable crystals were grown by slowly concentrating a
tives are stable in solution for long periods without notice- chloroform/n-hexane solution of the complex. The molecu-
able decomposition. Furthermore, we studied the decompo- lar structure is illustrated in Figure 2. Crystal data are given
sition of 7a in dichloromethane, which is complete after two in the Experimental Section, and selected bond lengths and
months, in detail and found that it leads to the tetranuclear angles with estimated standard deviations are listed in
complex 1a and [M(CO)5(PPh3)]. The low yields obtained Table 1.
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J. J. Fernández, J. M. Vila et al.
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are also parallel and within the distance expected for a π–
π “slipped stacking”. Whether this disposition is a conse-
quence of an attractive interaction between the “metalloar-
omatic” rings or is a requirement of the pyridine–plane 3
interaction has not yet been established.
Figure 2. Molecular structure of 2c with labelling scheme. Hydro-
gen atoms have been omitted for clarity.
Figure 3. Intermolecular π–π stacking interactions in 2c. Dashed
lines link the centres of the rings involved in each interaction.
The structure consists of discrete molecules separated by
van der Waals distances in which the palladium atom is
bonded in a slightly distorted square-planar geometry to
the ligand through the N(1) nitrogen atom of the pyridine
ring, the imine N(2) atom, the O(1) phenolate oxygen atom,
and the Cl(1) chlorine atom. The angles between adjacent
atoms in the coordination sphere of the palladium atom are
close to the expected value of 90°, with the most noticeable
distortions corresponding to N(1)–Pd(1)–N(2) [81.0(2)°]
and N(1)–Pd(1)–Cl(1) [98.6(1)°]. The sum of the angles
about the palladium atom is ca. 360°. The Pd(1)–N(1)
[2.018(4) Å] and Pd(1)–N(2) [1.945(4) Å] bond lengths are
similar to those reported for related compounds.[36–40] The
Pd(1)–O(1) bond [2.012(3) Å] is somewhat shorter than the
value predicted from the covalent radii of these two
atoms[41] but similar to values found earlier.[28–32]
Table 2. Intermolecular π–π stacking parameters in the crystal of
2c identified by using PLATON;[52] c1 and c2 are the centroids of
the corresponding planes.
Parameter
Plane 3/pyridine Plane 2/plane 2
d(c1–c2) [Å]/α [°]
d[Ќc1–P(2)] [Å]/β [°]
d[Ќc2–P(1)] [Å]/γ [°]
3.387(3)/1.14
3.36–5.79
3.37–6.60
3.375(2)/0.02
3.34–7.95
3.34–7.95
Treatment of 2c and 2d with silver perchlorate and tri-
phenylphosphane in acetone gave the mononuclear com-
plexes 3c and 3d, respectively, where the phosphane ligand
occupies the coordination position left vacant after AgCl
1
removal. The H NMR spectra of these complexes show
coupling of the HC=N proton to the 31P nucleus (JP,H
≈
13 Hz). The H5 resonance does not show coupling to the
phosphorus nuclei, although it is upfield-shifted due to
shielding by the phosphane phenyl rings.[8,46,47] The FAB
mass spectra show peaks corresponding to [(L-H)Pd-
(PPh3)]+ fragments with loss of the perchlorate counterion,
and the conductivity measurements carried out in dry ace-
tonitrile are in agreement with 1:1 electrolyte complexes.
The geometry around the palladium atom [Pd(1), N(1),
N(2), O(1), Cl(1)] is planar (r.m.s. = 0.035, plane1). The
coordination rings [Pd(1), C(1), C(6), N(1), N(2), plane 2]
and [Pd(1), N(2), C(7), C(12), O(1), plane 3] are also planar
(r.m.s. = 0.010 and 0.015, respectively). Planes 1, 2 and 3,
the phenol ring and the pyridine ring are nearly coplanar
(largest angle 3.9° between plane 2 and the phenol ring).
The presence of an aromatic system constituted by the
fusion of heterocyclic and phenyl rings, plus two five-mem-
bered metallacycles, indicates that π–π interactions are
likely to play an important role in controlling the crystal
Crystal Structure of 3c
Suitable crystals were grown by slowly concentrating an
packing in this type of structure. Thus, π–π interactions acetone solution of complex 3c. The molecular structure is
were observed between the pyridine ring (plane 1) and coor- illustrated in Figure 4. Crystal data are given in the Experi-
dination plane 3 on the one hand, and between the two mental Section, and selected bond lengths and angles with
coordination planes 2 of two symmetrically related mole- estimated standard deviations are listed in Table 1.
cules [distance between ring centres: 3.387(2) (py–plane 3)
The crystal structure comprises one [Pd{2-(NC5H4)C-
–
and 3.375(2) Å (plane 2–plane 2)] on the other (Figure 3 (H)=N[2Ј-(O)C6H4]}(PPh3)]+ cation and one ClO4 anion
and Table 2). In fact, within the packing dimer, the pyridine per asymmetric unit. The palladium atom is bonded in a
and coordination rings are not stacked in a roughly “face- slightly distorted square-planar geometry to the N(2) nitro-
to-face” fashion but rather show a so-called “slipped stack- gen atom of the pyridine ring, the imine N(1) atom and
ing”.[42] Similar interactions have been described pre- O(1) phenolate oxygen atom of the ligand, and the phos-
viously[43–45] and strongly suggest an active electronic de- phorus P(1) atom of the triphenylphosphane. The angles
localisation within the metal chelate rings with some degree between adjacent atoms in the coordination sphere of the
of “metalloaromaticity”. The metal chelate rings (planes 2) palladium atom are close to the expected value of 90°, with
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Eur. J. Inorg. Chem. 2009, 3071–3083

Cyclometallated [C,N,O] Complexes as Metalloligands
ring [Pd(1), N(2), C(7), C(12), O(1), plane 3] and the phenol
ring [distance between ring centres: 3.474(2) Å; Figure 5
and Table 3].
Table 3. Intermolecular π–π stacking parameters in the crystal of
3c identified by using PLATON;[52] c1 is the centroid of plane 3,
and c2 is the centroid of the phenol ring.
Parameter
Plane 3/phenol ring
d(c1–c2) [Å]/α deg
d[Ќc1–P(2)] [Å]/β [°]
d[Ќc2–P(1)] [Å]/γ [°]
3.474(2)/1.19
3.41–10.06
3.42–11.04
Conclusions
Figure 4. Structure of the cation of 3c with labelling scheme. Hy-
drogen atoms have been omitted for clarity.
We have shown that it is possible to obtain cyclometal-
lated compounds with donor atoms that are able to bind
the most noticeable distortions corresponding to N(2)– further to additional metal atoms. Thus, compounds de-
Pd(1)–N(1) [79.7(1)°] and N(1)–Pd(1)–P(1) [104.4(1)°]. The rived from Schiff-base ligands bearing pyridine rings may
sum of the angles about palladium is ca. 360°. The Pd–O(1) behave as metalloligands by coordination to a second metal
[2.016(2)], Pd–P(1) [2.300(1)], Pd–N(1) [2.069(3)] and Pd– atom through the non-coordinated nitrogen atom of the
N(2) [1.989(3)] bond lengths are close to expected val- heterocycle (ligands a and b). This is hindered in the case
ues.[31,48]
of the ortho-substituted pyridines, where the palladium
The coordination sphere around the palladium atom atom binds to the nitrogen atom itself in the absence of a
[Pd(1), O(1), N(2), N(1), P(1), plane 1] is planar (r.m.s. = Pd–C σ-bond (ligands c and d). Hence, the palladacycles
0.029). The [Pd(1), C(1), C(6), N(1), N(2), plane 2] and described herein yield heteromultinuclear complexes upon
[Pd(1), N(2), C(7), C(12), O(1), pane 3] rings are also planar reaction with carbonyl transition metal complexes, which in
(r.m.s. = 0.021 and 0.016, respectively) and coplanar with the case of the dinuclear compound with bridging dppf as
the pyridine and the phenol rings; consequently, the cation starting material yields a unique pentanuclear complex
is planar with the exception of the phosphane phenyl bearing three different metal atoms (11a, 12a). The deriva-
groups. In the crystal, the cations are arranged in dimers tives of ligand b, where the heterocycle supports a Pd–C σ-
with π–π stacking interactions between the metal chelate bond, have been shown to be considerably more stable than
Figure 5. Intermolecular π–π stacking interactions in 3c. Dashed lines link the centres of the rings involved in each stacking interaction.
Eur. J. Inorg. Chem. 2009, 3071–3083
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3077

J. J. Fernández, J. M. Vila et al.
FULL PAPER
3
3
H, Hi, H5), 8.37 (d, JH2,H3 = 7.5 Hz, 1 H, H2), 7.84 (td, JH2,H3
= 3JH3,H4 = 7.5, 4JH3,H5 = 1.5 Hz, 1 H, H3), 7.50 (m, 3JH3,H4 = 7.5,
those of a, where the heterocycle is a substituent of the
metallated ring. Similarly, complexes prepared with the car-
bonylmolybdenum reagent are less stable than their chro-
mium or tungsten analogues, and only in the case of b com-
pounds could the three group-6 metal complexes be ob-
tained.
4
3
3JH4,H5 = 4.8, JH2,H4 = 1.2 Hz, 1 H, H4), 7.27 (dd, JH8,H9 = 7.7,
4JH8,H10 = 1.5 Hz, 1 H, H8), 7.12 (m, 1 H, H10), 6.91 (dd, 3JH10,H11
4
3
3
= 7.7, JH9,H11 = 1.5 Hz, 1 H, H11), 6.84 (td, JH8,H9 = JH9,H10
=
3
7.7, JH9,H11 = 1.5 Hz, 1 H, H9) ppm.
(2-NC5H4)C(H)=N(C6H3OH-2-tBu-5) (d): Yield: 0.254 g (91%).
C16H18N2O (254.14): calcd. C 75.6, H 7.1, N 11.0; found C 75.5,
H 7.3, N 10.7. IR: ν = 1588 (s) ν(C=N) cm–1. 1H NMR (300 MHz,
˜
Experimental Section
[D6]DMSO): δ = 8.22 (br., 1 H, OH), 8.73 (s, 1 H, Hi), 8.68 (d,
3
3JH4,H5 = 4.7 Hz, 1 H, H5), 8.34 (d, JH2,H3 = 7.7 Hz, 1 H, H2),
General Procedures: Solvents were purified by standard methods.[49]
Chemicals were reagent grade. The phosphanes PPh3, t-Ph2PC-
(H)=(H)CPPh2 (t-dppe), Ph2P(CH2)4PPh2 (dppb), Ph2P(CH2)6-
PPh2 (dpph) and Fe(C5H4PPh2)2 (dppf) were purchased from Ald-
rich-Chemie. [RuCl2(CO)(dmf)(PPh3)2] (dmf = N,NЈ-dimethylform-
amide) was prepared according to literature methods.[50] Micro-
analyses were carried out by using a Carlo Erba Elemental Ana-
lyzer, Model 1108. IR spectra were recorded with a Bruker VEC-
TOR 22 spectrometer. NMR spectra were obtained for CDCl3 and
CD3SOCD3 solutions and referenced to SiMe4 (1H) or 85% H3PO4
(31P{1H}) with Bruker AV-300F or AC-500F spectrometers. All
chemical shifts are reported downfield from these standards. The
FAB mass spectra were recorded by using a Quatro mass spectrom-
eter with a Cs ion gun; 3-nitrobenzyl alcohol was used as the ma-
trix. The ESI mass spectra were recorded with a QSTAR Elite mass
spectrometer by using dichloromethane/acetonitrile or dichloro-
methane/ethanol as solvents. Conductivity measurements were per-
formed with a CRISON GLP 32 conductivimeter for 10–3  solu-
tions in dry acetonitrile.
3
3
4
7.93 (td, JH2,H3 = JH3,H4 = 7.7, JH3,H5 = 1.4 Hz, 1 H, H3), 7.49
(m, 3JH3,H4 = 7.4, 3JH4,H5 = 4.8, 4JH2,H4 = 1.1 Hz, 1 H, H4), 7.22 (d,
4JH8,H10 = 2.4 Hz, 1 H, H8), 7.14 (dd, 3JH10,H11 = 8.4 Hz, JH8,H10
=
3
2.4 Hz, 1 H, H10), 6.83 (d, JH10,H11 = 8.4 Hz, 1 H, H11), 1.27 (s,
9 H, tBu) ppm.
Synthesis of the Complexes
Preparation of 1a: A 50-mL Schlenk pressure tube containing li-
gand
a (0.100 g, 0.304 mmol), palladium acetate (0.069 g,
0.306 mmol) and dry toluene (20 mL) was sealed under argon and
the resulting mixture heated at 60 °C for 24 h. After cooling to
room temperature, the resulting violet solid was filtered off and
dried under vacuum. Yield: 0.025 g (19%). C88H80N8O4Pd4
(1739.31): calcd. C 60.7, H 4.6, N 6.4; found C 60.6, H 4.7, N 6.1.
1
IR: ν = 1578 (m sh) ν(C=N) cm–1. H NMR (300 MHz, CDCl ):
˜
3
3
δ = 8.77 (d, JH14,H15 = 6.5 Hz, 2 H, H15, H17), 7.84 (s, 1 H, Hi),
7.53 (d, JH14,H15 = 6.5 Hz, 2 H, H14, H18), 7.26 (d, JH2,H3
3
3
=
6.0 Hz, 1 H, H2), 7.14–7.06 (m, 3 H, H3, H5, H10), 6.89 (d,
4JH8,H10 = 1.4 Hz, 1 H, H8), 6.61 (d, 3JH10,H11 = 8.8 Hz, 1 H, H11),
1.29 (s, 9 H, tBu) ppm. FAB MS: m/z 869.2 [{(L-H2)Pd}2H]+, 1304
[{(L-H2)Pd}3H]+, 1740 [{(L-H2)Pd}4H2]+.
Syntheses of the Ligands
Preparation of 4-(4-NC5H4)C6H4C(H)=N(C6H3OH-2-tBu-5) (a): 4-
(4-NC5H4)C6H4CHO (0.202 g, 1.10 mmol) was added to a solution
of 2-amino-4-tert-butylphenol (0.181 g, 1.10 mmol) in dry chloro-
form (50 mL) and the solution heated under reflux in a Dean–Stark
apparatus. After cooling to room temperature, the chloroform was
removed to give a yellow solid. Yield: 0.249 g (81%). C22H22N2O
(330.42): calcd. C 80.0, H 6.7, N 8.5; found C 79.5, H 6.5, N 8.2.
Complexes 1b, 1c and 1d were prepared in a similar manner and
isolated as violet solids.
1b: Yield: 0.023 g (23%). C64H64N8O4Pd4 (1458.95): calcd. C 53.6,
H 4.5, N 7.1; found C 53.7, H 4.7, N 7.3. IR: ν = 1567 (m) ν(C=N)
˜
1
3
cm–1. H NMR (300 MHz, CDCl3): δ = 8.38 (d, JH2,H3 = 5.4 Hz,
1 H, H3), 7.69 (br., 1 H, Hi or H5), 7.41 (br., 1 H, Hi or H5), 7.10
(dd, 3JH10,H11 = 9.0, 4JH8,H10 = 2.0 Hz, 1 H, H10), 6.93 (d, 3JH8,H10
IR: ν = 1601 (s) ν(C=N), 3432 (w) ν(OH) cm–1. 1H NMR
˜
3
(300 MHz, CDCl3): δ = 8.77 (s, 1 H, Hi), 8.71 (d, JH14,H15
=
5.9 Hz, 2 H, H15, H17), 8.06 (d, 3JH2,H3 = 8.3 Hz, 2 H, H2, H6 or
3
= 2.0 Hz, 1 H, H8), 6.90 (d, JH2,H3 = 5.4 Hz, 1 H, H2), 6.52 (d,
3
3JH10,H11 = 9.0 Hz, 1 H, H11), 1.21 (s, 9 H, tBu) ppm. FAB-MS:
H3, H5), 7.77 (d, JH2,H3 = 8.3 Hz, 2 H, H2, H6 or H3, H5), 7.83
+
(br., 1 H, OH; signal from a spectrum recorded in [D6]DMSO),
m/z = 1434 [(L-H2)Pd]4
.
3
4
7.57 (d, JH14,H15 = 5.9 Hz, 2 H, H14, H18), 7.34 (d, JH8,H10
=
2.2 Hz, 1 H, H8), 7.28 (dd, 3JH10,H11 = 8.7, JH8,H10 = 2.2 Hz, 1 H,
4
1c: Yield: 0.107 g (97%). C14H12N2O3Pd (362.68): calcd. C 46.4, H
3
3.3, N 7.7; found C 46.2, H 3.6, N 7.4. IR: ν = 1572 (s, sh) ν(C=N),
˜
H10), 6.98 (d, JH10,H11 = 8.7 Hz, 1 H, H11), 1.36 (s, 9 H, tBu)
1556 (s, sh) νas(COO), 1319 (m) νs(COO) cm–1. 1H NMR
ppm.
(300 MHz, CDCl3): δ = 8.34 (s, 1 H, Hi), 8.15 (td, 3JH2,H3 = 3JH3,H4
Schiff bases b, c and d were prepared in a similar manner and
isolated as yellow (b), orange (c) or pale-green (d) solids.
4
4
= 7.8, JH3,H5 = 1.5 Hz, 1 H, H3), 7.91 (d, JH4,H5 = 5.4 Hz, H5),
3
7.76 (d, JH2,H3 = 7.8 Hz, 1 H, H2), 7.59 (m, 1 H, H4), 7.35 (dd,
3JH8,H9 = 8.1, JH8,H10 = 1.3 Hz, 1 H, H8), 7.04 (m, 1 H, H10),
4
(4-NC5H4)C(H)=N(C6H3OH-2-tBu-5) (b): Yield: 0.252 g (90%).
6.48–6.40 (m, 2 H, H9, H11), 1.82 (s, 3 H, OAc) ppm. FAB MS:
C16H18N2O (254.14): calcd. C 75.6, H 7.1, N 11.0; found C 76.1,
m/z = 303 [(L-H)Pd]+.
H 7.1, N 11.1. IR: ν = 1602 (s) ν(C=N) cm–1. 1H NMR (300 MHz,
˜
CDCl3): δ = 9.02 (s, 1 H, OH; signal from a spectrum recorded in
1d: Yield: 0.098 g (77%). C18H20N2O3Pd (418.78): calcd. C 51.7, H
3
[D6]DMSO), 8.79 (d, JH2,H3 = 4.5 Hz, 2 H, H3, H5), 8.71 (s, 1 H,
4.8, N 6.7; found C 52.2, H 4.3, N 7.0. IR: ν = 1566 (m, sh)
˜
3
3
Hi), 7.77 (d, JH2,H3 = 4.5 Hz, 2 H, H2, H6), 7.31 (d, JH8,H10
=
ν(C=N), 1540 (m, sh) νas(COO), 1324 (m) νs(COO) cm–1. 1H NMR
(300 MHz, CDCl3): δ = 8.40 (s, 1 H, Hi), 8.13 (td, 3JH2,H3 = 3JH3,H4
2.2 Hz, 1 H, H8), 7.10 (dd, 3JH8,H10 = 2.2, JH10,H11 = 8.8 Hz, 1 H,
H10), 6.98 (d, JH10,H11 = 8.8 Hz, 1 H, H11), 1.35 (s, 9 H, tBu)
3
3
4
4
= 7.8, JH3,H5 = 1.5 Hz, 1 H, H3), 7.89 (d, JH4,H5 = 5.6 Hz, H5),
ppm.
3
7.72 (d, JH2,H3 = 7.8 Hz, 1 H, H2), 7.55 (m, 1 H, H4), 7.28 (d,
3
4
(2-NC5H4)C(H)=N(C6H4OH-2) (c): Yield: 0.205 g (94%).
4JH8,H10 = 2.2 Hz, 1 H, H8), 7.14 (dd, JH10,H11 = 8.9, JH8,H10
=
3
C12H10N2O (198.22): calcd. C 72.7, H 5.1, N 14.1; found C 72.4,
2.2 Hz, 1 H, H10), 6.39 (d, JH10,H11 = 8.9 Hz, 1 H, H11), 1.87 (s,
1
H 5.3, N 14.0. IR: ν = 1627 (s) ν(C=N), 3373 (s) ν(OH) cm–1. H 3 H, OAc), 1.21 (s, 9 H, tBu) ppm. FAB MS: m/z = 359
˜
NMR (300 MHz, [D6]DMSO): δ = 9.98 (br., 1 H, OH), 8.70 (m, 2
[(L-H)Pd]+.
3078
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 3071–3083

Cyclometallated [C,N,O] Complexes as Metalloligands
Preparation of Complex 2a: PPh3 (0.056 g, 0.209 mmol) was added
to a suspension of 1a (0.091 g, 0.052 mmol) in acetone (20 mL).
This mixture was stirred for 72 h and the solvent removed to give
a violet solid, which was recrystallised from dichloromethane/hex-
ane and dried under vacuum. Yield: 0.016 g (11%). C40H35N2OPPd
(697.11): calcd. C 68.9, H 5.1, N 4.0; found C 68.1, H 5.3, N 3.9.
2b: Yield: 0.030 g (23%). C34H31N2OPPd (621.02): calcd. C 65.7,
H 5.0, N 4.5; found C 65.4, H 4.7, N 4.3. IR: ν = 1575 (m) ν(C=N)
˜
1
3
cm–1. H NMR (300 MHz, CDCl3): δ = 8.07 (d, JH2,H3 = 4.8 Hz,
4
4
1 H, H3), 7.86 (d, JP,Hi = 9.90 Hz, 1 H, Hi), 7.18 (d, JH5,P
=
1.8 Hz, 1 H, H5), 7.06 (dd, 3JH10,H11 = 8.8, JH8,H10 = 2.3 Hz, 1 H,
H10), 7.01 (d, JH8,H10 = 2.3 Hz, 1 H, H8), 6.91 (d, JH2,H3
4.8 Hz, 1 H, H2), 6.45 (d, JH10,H11 = 8.8 Hz, H11), 1.25 (s, 9 H,
4
4
3
=
3
IR: ν = 1538 (m, sh) ν(C=N) cm–1. 1H NMR (300 MHz,H15
=
˜
5.7 Hz, 2 H, H15,H17), 7.98 (d, 4JP,Hi = 10.2 Hz, 1 H, Hi), 7.21 (d, tBu) ppm. 31P{1H} NMR (121.49 MHz, CDCl3): δ = 33.02 (s)
3JH2,H3 = 7.8 Hz, 1 H, H2), 7.10 (dd, JH2,H3 = 7.8, JH3,H5
=
ppm. FAB MS: m/z = 620 [(L-H2)Pd(PPh3)]+.
3
4
4
1.7 Hz, 1 H, H3), 7.07 (d, JH8,H10 = 2.2 Hz, 1 H, H8), 7.04 (dd,
3b: Yield: 0.071 g (30%). C60H60N4O2P2Pd2 (1143.93): calcd. C
3JH10,H11 = 8.7, JH8,H10 = 2.2 Hz, 1 H, H10), 6.66 (d, JH14,H15
=
3
3
63.0, H 5.3, N 4.9; found C 62.8, H 5.5, N 4.7. IR: ν = 1578 (m)
˜
3
5.7 Hz, 2 H, H14, H18), 6.48 (d, JH10,H11 = 8.7 Hz, 1 H, H11),
ν(C=N) cm–1. 1H NMR (300 MHz, CDCl3): δ = 8.07 (d, 3JH2,H3
=
6.37 (dd, JP,H5 = 3.8, JH3,H5 = 1.7 Hz, 1 H, H5] ppm. 31P{1H}
NMR (121.49 MHz, CDCl3): δ = 34.58 (s) ppm. FAB MS: m/z =
696 [(L-H2)Pd(PPh3)]+.
4
4
4
4.7 Hz, 1 H, H3), 7.03 (dd, 3JH10,H11 = 8.8, JH8,H10 = 2.3 Hz, 1 H,
4
3
H10), 6.98 (d, JH8,H10 = 2.3 Hz, 1 H, H8), 6.85 (d, JH2,H3
=
3
4.7 Hz, 1 H, H2), 6.34 (d, JH10,H11 = 8.8 Hz, H11), 1.27 (s, 9 H,
tBu) ppm; Hi and H5 signals hidden beneath the phenyl proton
signals. 31P{1H} NMR (121.49 MHz, CDCl3): δ = 28.46 (s) ppm.
FAB MS: m/z = 892 [{(L-H2)Pd2(dppb)}H]+, 1144 [(L-H2)2Pd2-
(dppb)]+.
Complexes 3a, 4a, 5a, 6a, 2b, 3b and 4b were prepared as violet
solids according to a similar procedure by using dichloromethane
(4a, 2b, 3b, 4b), chloroform (3a, 6a) or acetone (5a) as solvents.
Complex 5a was recrystallised from acetone/hexane instead of
dichloromethane/hexane. An excess of the cyclometallated complex
1b (10%) was used in the synthesis of 2b.
4b: Yield: 0.135 g (51%). C66H60N4FeO2P2Pd2 (1271.84): calcd. C
62.3, H 4.7, N 4.4; found C 61.6, H 4.9, N 4.2. IR: ν = 1576 (m)
˜
3a: Yield: 0.113 g (42%). C72H68N4O2P2Pd2 (1296.12): calcd. C
ν(C=N) cm–1. 1H NMR (300 MHz, CDCl3): δ = 8.07 (d, 3JH2,H3
4.6 Hz, 1 H, H3), 7.83 (d, 4JP,Hi = 10.1 Hz, 1 H, Hi), 7.11 (d, 3JP,H5
=
66.7, H 5.3, N 4.3; found C 67.1, H 5.5, N 4.0. IR: ν = 1535 (m)
˜
1
3
3
4
ν(C=N) cm–1. H NMR (300 MHz, CDCl3): δ = 8.37 (d, JH14,H15 = 1.9 Hz, 1 H, H5), 7.07 (dd, JH10,H11 = 8.9, JH8,H10 = 2.3 Hz, 1
4
4
3
= 6.1 Hz, 2 H, H15, H17), 7.91 (d, JP,Hi = 8.2 Hz, 1 H, Hi), 7.16
H, H10), 7.03 (d, JH8,H10 = 2.3 Hz, 1 H, H8), 6.89 (d, JH2,H3
4.6 Hz, 1 H, H2), 6.50 (d, 3JH10,H11 = 8.9 Hz, 1 H, H11], 5.14–4.30
H, tBu) ppm. 31P{1H} NMR
=
3
(d, JH2,H3 = 7.8 Hz, 1 H, H2), 7.09–7.05 (m, 2 H, H3, H8), 7.0
(dd, 3JH10,H11 = 8.8, 4JH8,H10 = 2.1 Hz, 1 H, H10), 6.69 (d, 3JH14,H15 (br., CHferrocene), 1.28 (s,
9
= 6.1 Hz, 2 H, H14, H18), 6.39–6.35 (m, 2 H, H5, H11), 1.28 (s, 9
H, tBu) ppm. 31P{1H} NMR (121.49 MHz, CDCl3): δ = 30.22 (s)
ppm. FAB MS: m/z = 1296 [(L-H2)2Pd2(dppb)]+.
(121.49 MHz, CDCl3): δ = 23.09 (s) ppm. FAB MS: m/z = 928
[(L-H2)Pd(dppf)]+, 1271 [{(L-H2)2Pd2(dppf)}H]+.
Preparation of 7a: A solution of Cr(CO)6 (14.4 mg, 0.065 mmol) in
4a: Yield: 0.151 g (51%). C78H68FeN4O2P2Pd2 (1422.22): calcd. C dry and deoxygenated tetrahydrofuran (6 mL) was prepared in a
65.8, H 4.8, N 3.9; found C 66.1, H 5.0, N 3.6. IR: ν = 1534 (m)
25-mL Schlenk flask under argon and irradiated with UV light
˜
1
3
ν(C=N) cm–1. H NMR (300 MHz, CDCl3): δ = 8.37 (d, JH14,H15 (365 nm) for 45 min. The resulting yellow solution was transferred
4
= 5.2 Hz, 2 H, H15, H17), 7.95 (d, JP,Hi = 10.5 Hz, 1 H, Hi), 7.20 dropwise by cannula to a deoxygenated solution of 2a (43.2 mg,
3
3
4
(d, JH2,H3 = 7.7 Hz, 1 H, H2), 7.09 (dd, JH2,H3 = 7.7, JH3,H5
=
0.062 mmol) in thf (8 mL). During the addition, the violet solution
of 2a changed colour to dark blue. This solution was stirred for
24 h and the solvent removed under vacuum to give a blue solid,
4
1.4 Hz, 1 H, H3), 7.07 (d, JH8,H10 = 2.2 Hz, 1 H, H8), 7.03 (dd,
3JH10,H11 = 8.7, JH8,H10 = 2.2 Hz, 1 H, H10), 6.62 (d, JH14,H15
=
4
3
3
5.2 Hz, 2 H, H14, H18), 6.51 (d, JH10,H11 = 8.7 Hz, 1 H, H11), which was chromatographed on a column packed with alumina.
4
4
6.33 (dd, JP,H5 = 3.9, JH3,H5 = 1.4 Hz, 1 H, H5], 5.22–4.28 (br.,
Elution with dichloromethane afforded an oil, which was treated
CHferrocene), 1.28 (s, 9 H, tBu) ppm. 31P{1H} NMR (121.49 MHz, with light petroleum (60–80 °C) and the blue solid obtained filtered
CDCl3): δ = 24.91 (s) ppm. FAB MS: m/z = 1424 [(L-H2)2-
off and dried in vacuo. Yield: 7.2 mg (13%). C45H35CrN2O6PPd
(889.16): calcd. C 60.8, H 4.0, N 3.1; found C 61.1, H 4.3, N 2.9.
Pd2(dppf)]+.
IR: ν = 1606 (m) ν(C=N), 2065 (w), 1980 (w, sh), 1924 (s) ν(CO)
˜
5a: Yield: 0.208 g (79%). C70H62N4O2P2Pd2 (1266.05): calcd. C
cm–1. 1H NMR (500 MHz, CDCl3): δ = 8.32 (d, 3JH14,H15 = 6.5 Hz,
66.4, H 4.9, N 4.4; found C 66.0, H 5.2, N 4.2. IR: ν = 1535 (m)
˜
3
2 H, H15, H17), 8.02 (m, 1 H, Hi), 7.25 (d, JH2,H3 = 6.5 Hz, 1 H,
1
3
ν(C=N) cm–1. H NMR (300 MHz, CDCl3): δ = 8.35 (d, JH14,H15
3
H2), 7.08–7.12 (m, 3 H, H3, H8, H10), 6.57 (d, JH14,H15 = 4.5 Hz,
3
= 5.3 Hz, 2 H, H15, H17), 7.16 (d, JH2,H3 = 7.8 Hz, 1 H, H2),
7.09–7.05 (m, 3 H, H3, H8, H10), 6.71 (d, JH14,H15 = 5.3 Hz, 2 H,
2 H, H14, H18), 6.53 (br., 1 H, H11), 6.38 (br., 1 H, H5), 1.27 (s,
9 H, tBu) ppm. 31P{1H} NMR (121.49 MHz, CDCl3): δ = 34.50
(s) ppm. ESI-MS: m/z = 889 [(L-H2)Pd(PPh3){Cr(CO)5}H]+.
3
3
H14, H18), 6.43 (d, JH10,H11 = 9.4 Hz, 1 H, H11), 6.35 (m, 1 H,
H5), 1.30 (s, 9 H, tBu) ppm. 31P{1H} NMR (121.49 MHz, CDCl3):
δ = 30.22 (s), 30.88 (s) ppm. FAB MS: m/z = 1267 [{(L-H2)2Pd2(t-
dppe)}H]+.
Complexes 8a–12a and 5b–10b were obtained as blue (8a–12a) or
green (5b–10b) solids by using the appropriate hexacarbonyl com-
plex and applying a procedure similar to that described for 7a.
6a: Yield: 0.110 g (40%). C74H72N4O2P2Pd2 (1324.18): calcd. C
67.1, H 5.5, N 4.2; found C 66.7, H 5.6, N 4.1. IR: ν = 1534 (m)
8a: Yield: 21.5 mg (34%). C45H35N2O6PPdW (1021.00): calcd. C
˜
1
3
ν(C=N) cm–1. H NMR (300 MHz, CDCl3): δ = 8.38 (d, JH14,H15 52.9, H 3.4, N 2.7; found C 52.5, H 4.3, N 2.5. IR: ν = 1608 (m)
˜
4
= 5.8 Hz, 2 H, H15, H17), 7.93 (d, JP,Hi = 10.2 Hz, 1 H, Hi), 7.16 ν(C=N), 2069 (w), 1977 (w sh), 1919 (s) ν(CO) cm–1. 1H NMR
3
(d, JH2,H3 = 7.8 Hz, 1 H, H2), 7.09–7.02 (m, 2 H, H3, H8), 6.70
(500 MHz, CDCl3): δ = 8.52 (d, 3JH14,H15 = 6.5 Hz, 2 H, H15,H17),
(dd, 3JH10,H11 = 8.8, 4JH8,H10 = 2.1 Hz, 1 H, H10), 6.69 (d, 3JH14,H15 7.98 (d, JP,Hi = 10.0 Hz, 1 H, Hi), 7.24 (d, JH2,H3 = 8.0 Hz, 1 H,
4
3
3
4
= 5.8 Hz, 2 H, H14, H18), 6.51 (d, JH10,H11 = 8.8 Hz, 1 H, H11), H2), 7.10 (dd, JH2,H3 = 8.0, JH3,H5 = 1.75 Hz, 1 H, H3), 7.08–
4
4
3
6.38 (dd, JP,H5 = 3.9, JH3,H5 = 1.5 Hz, 1 H, H5), 1.27 (s, 9 H, 7.05 (m, 2 H, H8, H10), 6.59 (d, JH14,H15 = 6.5 Hz, 2 H, H14,
tBu) ppm. 31P{1H} NMR (121.49 MHz, CDCl3): δ = 29.98 (s) H18), 6.49 (d, 3JH10,H11 = 9.5 Hz, 1 H, H11), 6.35 (dd, 4JP,H5 = 3.8,
ppm. FAB MS: m/z = 1325 [{(L-H2)2Pd2(dpph)}H]+.
4JH3,H5 = 1.75 Hz, 1 H, H5), 1.29 (s, 9 H, tBu) ppm. 31P{1H} NMR
Eur. J. Inorg. Chem. 2009, 3071–3083
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3079

J. J. Fernández, J. M. Vila et al.
FULL PAPER
3
(121.49 MHz, CDCl3): δ = 34.51 (s) ppm. ESI-MS: m/z = 1020 [(L- 6.42 (d, JH10,H11 = 9 Hz, 1 H, H11), 1.24 (s, 9 H, tBu) ppm.
H2)Pd(PPh3){W(CO)5}H2]+.
31P{1H} NMR (121.49 MHz, CDCl3): δ = 33.56 (s) ppm. FAB MS:
m/z = 858 [(L-H2)Pd(PPh3){Mo(CO)5}]+.
9a: Yield: 15.9 mg (15%). C84H72Cr2N4O12P2Pd2 (1708.27): calcd.
7b: Yield: 28.1 mg (48%). C39H31N2O6PPdW (944.91): calcd. C
C 59.1, H 4.2, N 3.3; found C 58.4, H 4.3, N 3.0. IR: ν = 1606 (m)
˜
ν(C=N), 2067 (w), 1978 (w, sh), 1900 (s) ν(CO) cm–1. 1H NMR
49.6, H 3.3, N 3.0; found C 49.0, H 3.5, N 3.1. IR: ν = 2079 (w),
˜
1
1984 (w, sh), 1910 (s) ν(CO) cm–1. H NMR (500 MHz, CDCl3): δ
3
(300 MHz, CDCl3): δ = 8.27 (d, JH14,H15 = 6.6 Hz, 2 H, H15,
3
4
H17), 7.96 (d, 4JP,Hi = 10.2 Hz, 1 H, Hi), 7.21 (d, 3JH2,H3 = 7.8 Hz,
= 8.32 (d, JH2,H3 = 5.7 Hz, 1 H, H3), 7.79 (d, JP,Hi = 9.90 Hz, 1
H, Hi), 7.38 (d, JP,H5 = 2.1 Hz, 1 H, H5), 7.07 (dd, JH10,H11
9.0, JH8,H10 = 1.5 Hz, 1 H, H10), 7.01 (d, JH8,H10 = 1.5 Hz, 1 H,
4
3
3
=
1 H, H2), 7.07–7.04 (m, 3 H, H3, H8, H10), 6.53 (d, JH14,H15
=
4
4
3
6.6 Hz, 2 H, H14, H18), 6.47 (d, JH10,H11 = 9.3 Hz, 1 H, H11),
3
3
4
4
H8), 6.82 (d, JH2,H3 = 5.7 Hz, 1 H, H2), 6.41 (d, JH10,H11
=
6.30 (dd, JP,H5 = 3.6, JH3,H5 = 1.8 Hz, 1 H, H5), 1.27 (s, 9 H,
tBu) ppm. 31P{1H} NMR (121.49 MHz, CDCl3): δ = 34.53 (s)
ppm. ESI-MS: m/z = 1324 [{(L-H2)2Pd2(dpph)}H]+, 1516 [{(LH2)2-
9.0 Hz, 1 H, H11), 1.24 (s, 9 H, tBu) ppm. 31P{1H} NMR
(121.49 MHz, CDCl3): δ = 33.46 (s) ppm. FAB MS: m/z = 945 [(L-
H2)Pd(PPh3){W(CO)5}]+.
Pd2(dpph)}{Cr(CO)5}H]+,
(CO)5}2H]+.
1709.16
[{(L-H2)2Pd2(dpph)}{Cr-
8b: Yield: 10.4 mg (11%). C70H60Cr2N4O12P2Pd2 (1528.02): calcd.
C 55.0, H 3.9, N 3.7; found C 54.8, H 4.1, N 3.7. IR: ν = 1519 (m,
˜
10a: Yield: 89.2 mg (73%). C84H72N4O12P2Pd2W2 (1971.96): calcd.
sh) ν(C=N), 2063 (w), 1978 (w, sh), 1925 cm–1 (s) ν(CO). 1H NMR
C 51.2, H 3.7, N 2.8; found C 50.8, H 3.7, N 3.1. IR: ν = 1607 (m)
˜
3
ν(C=N), 2069 (w), 1975 (w, sh), 1887 (s) ν(CO) cm–1. 1H NMR
(300 MHz, CDCl3): δ = 8.07 (d, JH2,H3 = 5.7 Hz, 1 H, H3), 7.03
(dd, 3JH10,H11 = 9.0, 4JH8,H10 = 2.4 Hz, 1 H, H10), 6.94 (d, 4JH8,H10
3
(300 MHz, CDCl3): δ = 8.50 (d, JH14,H15 = 6.7 Hz, 2 H, H15,
3
H17), 7.93 (d, 4JP,Hi = 10.2 Hz, 1 H, Hi), 7.18 (d, 3JH2,H3 = 7.8 Hz,
= 2.4 Hz, H8), 6.67 (d, JH2,H3 = 5.7 Hz, 1 H, H2), 6.30 (d,
3JH10,H11 = 9.0 Hz, 1 H, H11 d), 1.26 (s, 9 H, tBu) ppm; Hi and
H5 signals hidden by the phenyl proton signals. 31P{1H} NMR
(121.49 MHz, CDCl3): δ = 28.46 (s) ppm. ESI-MS: m/z = 1336
[(L-H2)2Pd2(dppb){Cr(CO)5}H]+, 1527 [(L-H2)2Pd2(dppb){Cr-
(CO)5}2]+.
3
1 H, H2), 7.06–7.03 (m, 3 H, H3, H8, H10), 6.59 (d, JH14,H15
=
3
6.7 Hz, 2 H, H14, H18), 6.49 (d, JH10,H11 = 9.6 Hz, 1 H, H11),
4
4
6.32 (dd, JP,H5 = 3.6, JH3,H5 = 1.8 Hz, 1 H, H5), 1.27 (s, 9 H,
tBu) ppm. 31P{1H} NMR (121.49 MHz, CDCl3): δ = 30.30 (s)
ppm. FAB MS: m/z = 1969 [{(L-H2)2Pd2(dpph)}{W(CO)5}2]+.
9b: Yield: 4.0 mg (4%). C70H60Mo2N4O12P2Pd2 (1615.91): calcd. C
11a: Yield: 35.9 mg (32%). C88H68Cr2FeN4O12P2Pd2 (1808.13):
52.0, H 3.7, N 3.5; found C 52.4, H 4.0, N 3.6. IR: ν = 1517 (m,
˜
calcd. C 58.4, H 3.8, N 3.1; found C 58.0, H 4.0, N 2.9. IR: ν =
˜
sh) ν(C=N), 2069 (w), 1982 (w, sh), 1902 (s) ν(CO) cm–1. 1H NMR
1
1605 (m) ν(C=N), 2065 (w), 1980 (w, sh), 1916 (s) ν(CO) cm–1. H
3
(300 MHz, CDCl3): δ = 8.12 (d, JH2,H3 = 5.4 Hz, 1 H, H3), 7.04
3
NMR (300 MHz, CDCl3): δ = 8.26 (d, JH14,H15 = 6.6 Hz, 2 H,
(dd, 3JH10,H11 = 9.0, 4JH8,H10 = 2.1 Hz, 1 H, H10), 6.95 (d, 4JH8,H10
4
3
H15, H17), 7.92 (d, JP,Hi = 10.2 Hz, 1 H, Hi), 7.19 (d, JH2,H3
=
3
= 2.1 Hz, H8), 6.73 (d, JH2,H3 = 5.4 Hz, 1 H, H2), 6.33 (d,
7.8 Hz, 1 H, H2), 7.06–7.01 (m, 3 H, H3, H8, H10), 6.52–6.47 (m,
3JH10,H11 = 9.0 Hz, 1 H, H11 d), 1.26 (s, 9 H, tBu) ppm; Hi and
H5 signals hidden by the phenyl proton signals. 31P{1H} NMR
(121.49 MHz, CDCl3): δ = 28.59 (s) ppm. ESI-MS: m/z = 1144.24
[(L-H2)2Pd2(dppb)H]+, 1380 [(L-H2)2Pd2(dppb){Mo(CO)5}H]+,
1616 [(L-H2)2Pd2(dppb){Mo(CO)5}2]+.
4
4
3 H, H11, H14, H18), 6.25 (dd, JP,H5 = 4.1, JH3,H5 = 1.7 Hz, 1
H, H5), 5.20–4.31 (m, CHferrocene), 1.27 (s, 9 H, tBu) ppm. 31P{1H}
NMR (121.49 MHz, CDCl3): δ = 24.68 (s) ppm. FAB MS: m/z =
1809 [{(L-H2)2Pd2(dppf)}{Cr(CO)5}2H2]+.
12a: Yield: 87.3 mg (68%). C88H68FeN4O12P2Pd2W2 (2071.81):
10b: Yield: 17.0 mg (19%). C70H60Mo2N4O2P2Pd2 (1455.92): calcd.
calcd. C 51.0, H 3.3, N 2.7; found C 50.8, H 3.5, N 2.5. IR: ν =
˜
C 46.9, H 3.4, N 3.1; found C 46.7, H 3.5, N 3.3. IR: ν = 1517 (m,
˜
1
1607 (m) ν(C=N), 2069 (w), 1974 (w, sh), 1883 (s) ν(CO) cm–1. H
sh) ν(C=N), 2067 (w), 1971 (w, sh), 1890 (s) ν(CO) cm–1. 1H NMR
3
NMR (300 MHz, CDCl3): δ = 8.48 (d, JH14,H15 = 6.6 Hz, 2 H,
3
(300 MHz, CDCl3): δ = 8.29 (d, JH2,H3 = 5.7 Hz, 1 H, H3), 7.04
4
3
H15, H17), 7.92 (d, JP,Hi = 10.5 Hz, 1 H, Hi), 7.21 (d, JH2,H3
=
(dd, 3JH10,H11 = 9.0, 4JH8,H10 = 2.4 Hz, 1 H, H10), 6.95 (d, 4JH8,H10
7.8 Hz, 1 H, H2), 7.09–7.01 (m, 3 H, H3, H8, H10), 6.53–6.48 (m,
3
= 2.4 Hz, H8), 6.71 (d, JH2,H3 = 5.7 Hz, 1 H, H2), 6.31 (d,
4
4
3 H, H11, H14, H18), 6.28 (dd, JP,H5 = 3.9, JH3,H5 = 1.5 Hz, 1
H, H5), 5.22–4.31 (m, CHferrocenes), 1.27 (s, 9 H, tBu) ppm. 31P{1H}
NMR (121.49 MHz, CDCl3): δ = 24.67 (s) ppm. FAB MS: m/z =
2072 [{(L-H2)2Pd2(dppf)}{W(CO)5}2]+.
3JH10,H11 = 9.0 Hz, 1 H, H11 d), 1.26 (s, 9 H, tBu) ppm; Hi and
H5 signals hidden by the phenyl proton signals. 31P{1H} NMR
(121.49 MHz, CDCl3): δ = 28.41 (s) ppm. ESI-MS: m/z = 1791 [(L-
H2)2Pd2(dppb){W(CO)5}2H]+.
5b: Yield: 10.1 mg (6%). C39H31CrN2O6PPd (813.06): calcd. C
Preparation of 11b:
A solution of complex 2b (0.0202 g,
57.6, H 3.8, N 3.4; found C 57.0, H 4.0, N 3.2. IR: ν = 1522 (m,
˜
0.0325 mmol) in dry and deoxygenated chloroform (15 mL) was
prepared in a 50-mL Schlenk flask under argon. A solution of
[RuCl2(CO)(dmf)(PPh3)2] (0.0260 g, 0.0326 mmol) in dry and
deoxygenated chloroform (10 mL) was added dropwise, with mag-
netic stirring, to the resulting violet solution, upon which the col-
our of the solution changed to deep blue. The solution was stirred
at room temperature for 2 d and the solvent removed in vacuo to
give a solid, which was chromatographed on a column packed with
alumina. Elution with dichloromethane/methanol (2%) afforded
the desired product as a green oil, which was dried in vacuo. Yield:
10.0 mg (23%). C71H61N2O2P3Cl2RuPd (1345.57): calcd. C 63.7, H
sh), ν(C=N), 2061 (w), 1949 (w, sh), 1894 (s) ν(CO) cm–1. 1H NMR
3
(500 MHz, CDCl3): δ = 8.15 (d, JH2,H3 = 5.5 Hz, 1 H, H3), 7.83
4
4
(d, JP,Hi = 10.0 Hz, 1 H, Hi), 7.23 (d, JP,H5 = 2.0 Hz, 1 H, H5),
3
4
7.11 (dd, JH10,H11 = 5.4, JH8,H10 = 1.5 Hz, 1 H, H10), 7.01 (d,
4JH8,H10 = 1.5 Hz, 1 H, H8), 6.82 (d, JH2,H3 = 5.5 Hz, 1 H, H2),
3
3
6.41 (d, JH10,H11 = 5.4 Hz, 1 H, H11), 1.29 (s, 9 H, tBu) ppm.
31P{1H} NMR (121.49 MHz, CDCl3): δ = 33.57 (s) ppm. FAB MS:
m/z = 813 [(L-H2)Pd(PPh3){Cr(CO)5}H]+.
6b: Yield: 6.9 mg (12%). C39H31MoN2O6PPd (857.01): calcd. C
54.6, H 3.6, N 3.3; found C 54.1, H 3.9, N 3.2. IR: ν = 1519 (m,
˜
sh) ν(C=N), 2069 (w), 1981 (w, sh), 1902 (s) ν(CO) cm–1. 1H NMR
4.6, N 2.1; found C 62.5, H 4.0, N 2.6. IR: ν = 1587 (s), ν(C=N),
˜
3
(500 MHz, CDCl3): δ = 8.20 (d, JH2,H3 = 5.5 Hz, 1 H, H3), 7.85
1943 (s) ν(CO) cm–1. 1H NMR (300 MHz, CDCl3): δ = 8.09 (d,
4
4
4
(d, JP,Hi = 10.00 Hz, 1 H, Hi), 7.27 (d, JP,H5 = 2.0 Hz, 1 H, H5),
3JH2,H3 = 6.1 Hz, 1 H, H2), 6.95 (d, JH8,H10 = 2.1 Hz, 1 H, H8),
3
4
3
3
7.11 (dd, JH10,H11 = 9.0, JH8,H10 = 2.0 Hz, 1 H, H10), 7.01 (d,
6.31 (d, JH10,H11 = 9.0 Hz, H11), 5.47 (d, JH2,H3 = 6.1 Hz, 1 H,
4JH8,H10 = 2.0 Hz, 1 H, H8), 6.83 (d, JH2,H3 = 5.5 Hz, 1 H, H2), H3), 1.26 (s, 9 H, tBu) ppm; Hi and H5 signals hidden by the
4
3080
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© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 3071–3083

Cyclometallated [C,N,O] Complexes as Metalloligands
phenyl proton signals. 31P{1H} NMR (121.49 MHz, CDCl3): δ =
31.31 (s), 22.49 (s) ppm. ESI-MS: m/z = 1311 [(L-H2)Pd(PPh3)-
{RuCl(PPh3)2Cl(CO)}]+.
the solvent removed to give a violet solid, which was recrystallised
from chloroform/hexane. Yield: 0.127 g (75%). C30H24ClN2O5PPd
(77.59): calcd. C 54.1, H 3.6, N 4.2; found C 53.8, H 3.7, N 3.9. IR:
ν = 1595 (m) ν(C=N), 1133 (s) ν(ClO ) cm–1. 1H NMR (300 MHz,
˜
4
Preparation of 2c. Method 1: A saturated aqueous solution of NaCl
4
3
CDCl3): δ = 8.77 (d, JP,Hi = 12.9 Hz, 1 H, Hi), 8.12 (td, JH2,H3
=
(25 mL) was added dropwise to
a solution of 1c (0.101 g,
3JH3,H4 = 7.8, JH3,H5 = 1.4 Hz, 1 H, H3), 7.89 (dd, JH2,H3 = 7.8,
4
3
0.279 mmol) in acetone (25 mL) and the resulting mixture stirred
for 24 h. The red precipitate formed was filtered off, washed with
water and dried under vacuum to give complex 2c as a red solid.
Yield: 0.097 g (90%). C14H9ClN2OPd (363.11): calcd. C 46.3, H
4JH2,H4 = 1.4 Hz, 1 H, H2), 7.49 (dd, JH8,H9 = 8.2, JH8,H10
=
3
4
1.3 Hz, 1 H, H8), 7.22 (m, 1 H, H4), 7.08 (m, 1 H, H10), 6.76 (d,
3
3JH4,H5 = 5.6 Hz, 1 H, H5), 6.59 (m, 1 H, H9), 6.40 (d, JH10,H11
=
7.0 Hz, 1 H, H11) ppm. 31P{1H} NMR (121.49 MHz, CDCl3): δ =
25.71 (s) ppm. FAB MS: m/z = 565 [(L-H)Pd(PPh3)]+. Specific mo-
lar conductivity (in acetonitrile): Λm = 81.4 Scm2 mol–1.
2.5, N 7.7; found C 46.2, H 2.8, N 7.4. IR: ν = 1577 (m) ν(C=N)
˜
cm–1. 1H NMR (300 MHz, [D6]DMSO): δ = 8.44 (s, 1 H, Hi), 8.35
3
3
3
(d, JH4,H5 = 5.4 Hz, 1 H, H5), 8.14 (td, JH2,H3 = JH3,H4 = 7.8,
4JH3,H5 = 1.5 Hz, 1 H, H3), 7.76 (d, JH2,H3 = 7.8 Hz, 1 H, H2),
3
Preparation of 3d: This complex was prepared in a similar manner
to 3c. Yield: 0.119 g (65%). C34H32ClN2O5PPd (721.48): calcd. C
3
4
7.60 (m, 1 H, H4), 7.38 (dd, JH8,H9 = 8.2, JH8,H10 = 1.2 Hz, 1 H,
H8), 7.04 (m, 1 H, H10), 6.49–6.43 (m, 2 H, H9, H11) ppm. FAB
MS: m/z = 339 [(L-H)Pd]+. Method 2: Ethanol (10 mL) was added
to a stirred solution of potassium tetrachloropalladate (0.318 g,
0.974 mmol) in water (2 mL). The fine yellow suspension of potas-
sium tetrachloropalladate obtained was treated with ligand c
(0.200 g, 1.010 mmol, 15% excess) and the resulting mixture stirred
for 72 h. The red precipitate formed was filtered off and dried un-
der vacuum. Yield: 0.230 g (65%).
56.6, H 4.5, N 3.9; found C 56.4, H 4.5, N 3.7. IR: ν = 1596 (m)
˜
1
ν(C=N), 1034 (s) ν(ClO4) cm–1. H NMR (300 MHz, CDCl3): δ =
4
3
4
8.59 (d, JP,Hi = 13.0 Hz, 1 H, Hi), 8.15 (dd, JH2,H3 = 7.8, JH2,H4
3
4
= 1.4 Hz, 1 H, H2), 7.91 (td, JH2,H3
= =
3JH3,H4 = 7.8, JH3,H5
4
1.4 Hz, 1 H, H3), 7.40 (d, JH8,H10 = 2.2 Hz, 1 H, H8), 7.11 (dd,
3JH10,H11 = 9.0, JH8,H10 = 2.2 Hz, 1 H, H10), 6.91 (m, 1 H, H4),
4
3
6.60 (m, 1 H, H5), 6.38 (d, JH10,H11 = 9.0 Hz, 1 H, H11), 1.27 (s,
9 H, tBu) ppm. 31P{1H} NMR (121.49 MHz, CDCl3): δ = 25.27
(s) ppm. FAB MS: m/z = 621 [(L-H)Pd(PPh3)]+. Specific molar
conductivity (in acetonitrile): Λm = 101.8 Scm2 mol–1.
Preparation of 2d: Complex 2d was prepared as a red solid accord-
ing to Method 1. Yield: 0.094 g (85%). C16H17ClN2OPd (395.19):
calcd. C 48.6, H 4.3, N 7.1; found C 48.0, H 3.8, N 6.9. IR: ν =
˜
X-ray Crystallographic Study: Three-dimensional, room tempera-
ture X-ray data were collected with a Bruker Smart 1k CCD dif-
fractometer by using graphite-monochromated Mo-Kα radiation.
All the measured reflections were corrected for Lorentz and polar-
ization effects and for absorption by semi-empirical 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 posi-
tions and refined in riding mode. The Cl(1), Cl(2) and Cl(3) chlo-
rine atoms of the chloroform solvent molecule in the crystal of 2c
were disordered and, consequently, refined in two complementary
positions with occupancies of 50%. Refinement converged upon
allowing for the thermal anisotropy of all non-hydrogen atoms.
1
1602 (m) ν(C=N) cm–1. H NMR (300 MHz, CDCl3): δ = 8.49 (s,
3
4
1 H, Hi), 8.32 (dd, JH4,H5 = 5.5, JH3,H5 = 1.2 Hz, 1 H, H5), 8.12
3
3
4
(td, JH2,H3 = JH3,H4 = 7.8, JH3,H5 = 1.5 Hz, 1 H, H3), 7.72 (d,
3JH2,H3 = 7.8 Hz, 1 H, H2), 7.57 (m, 1 H, H4), 7.32 (d, JH8,H10
=
4
2.2 Hz, 1 H, H8), 7.13 (dd, 3JH10,H11 = 8.9, JH8,H10 = 2.2 Hz, 1 H,
H10), 6.40 (m, 1 H, H11) ppm. FAB MS: m/z = 360.1 [(L-H)-
PdH]+.
4
Preparation of 3c: Silver perchlorate (53 mg, 0.255 mmol) was
added to a solution of 2c (87 mg, 0.257 mmol) in acetone (15 mL).
The resulting mixture was then stirred for 5 h and PPh3 (67 mg,
0.255 mmol) added. The mixture was stirred for a further 24 h and
filtered through Celite to remove the AgCl precipitate formed and
Table 4. Crystal and structure refinement data for 2c, 3c and 4a.
2c
3c
4a
Empirical formula
Mr
T [K]
C13H10Cl4N2OPd
458.43
293(2)
C30H24ClN2O5PPd
665.33
293(2)
C80H72Cl2N4O2P2FePd2
1522.91
293(2)
λ [Å]
0.71073
monoclinic
P21/n
13.026(1)
7.093(1)
17.324(1)
0.71073
0.71073
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
triclinic
triclinic
¯
¯
P1
P1
9.053(1)
10.113(1)
16.302(2)
84.840(2)
79.405(2)
66.158(2)
1341.6(3)
2
11.012(2)
11.213(2)
13.935(2)
97.622(3)
94.350(3)
95.215(3)
1691.7(5)
1
90.179(2)
γ [°]
V [Å3]
1600.7(2)
4
1.824
0.80ϫ0.14ϫ0.10
56.6
Z
µ [mm–1]
Crystal size [mm]
2θmax [°]
0.896
0.14ϫ0.13ϫ0.05
56.6
0.916
0.24ϫ0.19ϫ0.04
50.4
Reflections collected
Unique reflections
Transmissions
R [F, I Ͼ 2σ(I)]
wR [F2, all data]
ρmax [eÅ3]
11382
17848
17828
3989 (Rint = 0.08)
0.83, 0.32
0.0496
0.0867
0.418
6612 (Rint = 0.05)
0.95, 0.88
0.0402
0.1030
0.843
5955 (Rint = 0.10)
0.96, 0.81
0.0534
0.1376
0.607
Eur. J. Inorg. Chem. 2009, 3071–3083
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3081

J. J. Fernández, J. M. Vila et al.
FULL PAPER
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Structure solution and refinement were carried out by using the
program package SHELX-97.[51] Further details can be found in
Table 4. CCDC-259264 (2c), -259265 (3c), and -259266 (4a) contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
We thank the Ministerio de Educación y Ciencia (CTQ2006-15621-
C02-02/BQU), the Xunta de Galicia and the Universidad de La
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Published Online: April 6, 2009
Eur. J. Inorg. Chem. 2009, 3071–3083
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3083