Cyclometallation of phenylhydrazones: Synthesis, reactivity, crystal structure analysis and novel trinuclear palladium(II) cyclometallated compounds with [C, N, N′] terdentate ligands

Article abstract of DOI:10.1016/j.jorganchem.2005.04.039

Reaction of the ligand C₆H₅N(H)N=CMe(C ₅H₄N) (a) with palladium(II) acetate in toluene gave the mononuclear cyclometallated complex [Pd{C₆H₄N(H)N= CMe(C₅H₄N)}(AcO)] (1

Full text of DOI:10.1016/j.jorganchem.2005.04.039

Journal of Organometallic Chemistry 690 (2005) 3669–3679
www.elsevier.com/locate/jorganchem
Cyclometallation of phenylhydrazones: Synthesis, reactivity,
crystal structure analysis and novel trinuclear palladium(II)
cyclometallated compounds with [C,N,N0] terdentate ligands
a
Alberto Fernandez , Digna Vazquez-Garcıa , Jesus J. Fernandez
a
,a,1
*
´
Margarita Lopez-Torres , Antonio Suarez , Jose M. Vila
´
´
´
´
,
a
a
b,
*
´
´
´
a
´
Departamento de Quımica Fundamental, Universidad de La Corun˜a, E-15071 La Corun˜a, Spain
´ ´
Departamento de Quımica Inorganica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
b
Received 30 December 2004; received in revised form 9 April 2005; accepted 26 April 2005
Available online 27 June 2005
Abstract
Reaction of the ligand C6H5N(H)N@CMe(C5H4N) (a) with palladium(II) acetate in toluene gave the mononuclear cyclometal-
lated complex [Pd{C6H4N(H)N@CMe(C5H4N)}(AcO)] (1a). Reaction of 1a with sodium chloride gave the analogous chlorine com-
pound [Pd{C6H4N(H)N@CMe(C5H4N)}(Cl)] (3a) which could also be prepared by reaction of a with lithium tetrachloropalladate
and sodium acetate in methanol for 48 h; whereas shorter reaction times afforded the non-cyclometallated complex
[Pd{C6H5N(H)N@CMe(C5H4N)}(Cl)2] (2a). Reaction of the ligand 2-ClC6H4N(H)N@CMe(C5H4N) Æ HCl (b), with palladium(II)
acetate, or with lithium tetrachloropalladate and sodium acetate, yielded the cyclometallated complex [Pd2-ClC6H3-
N(H)N@CMe(C5H4N)(Cl)] (1b). Treatment of 3a and 1b with silver trifluoromethanesulphonate (triflate) and triphenylphosphine
in acetone gave the mononuclear complexes [Pd{2-RC6HnN(H)N@CMe(C5H4N)}(PPh3)][CF3SO3], (R = H, n = 4, 4a; R = Cl,
n = 3, 2b) with the ligand as C,N,N0 terdentate and substitution of chlorine by triphenylphosphine. Reaction of 3a and 1b with silver
triflate and the tertiary diphosphine Ph2P(CH2)4PPh2 (dppb) in a 2:1 molar ratio gave the dinuclear cyclometallated complexes
[{Pd[2-RC6H3N(H)N@CMe(C5H4N)]}2(l-Ph2P(CH2)4PPh2)][CF3SO3]2 (R = H, 5a; R = Cl, 3b) with a l2-diphosphine bridging
ligand. Similarly, treatment of 3a and 1b with silver triflate and the tertiary triphosphines MeC(CH2PPh2)3 (tripod) and
(Ph2PCH2CH2)2PPh (triphos), in 3:1 molar ratio, gave the novel trinuclear complexes [{Pd[C6H4N(H)N@CMe(C5H4N)]}3{l3-
MeC(CH2Ph2)3}][CF3SO3]3 (6a) and [{Pd[2-ClC6H3N(H)N@CMe(C5H4N)]}3{l3-(PPh2CH2CH2)2PPh}][CF3SO3] (4b) regioselec-
3
tively, with the phosphine as a l3-bridging ligand. When the reaction between 3a and triphos was carried out in 1:1 molar ratio the
mononuclear complex [Pd{C6H4N(H)N@CMe(C5H4N)}{(PPh2CH2CH2)2PPh-P,P,P}][ClO4] (7a) was obtained. The crystal struc-
tures of 2b, 3a and 4a have been determined by X-ray crystallography.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Palladium; Cyclometallation; Phosphines; Phenylhydrazones; Crystal structure
1. Introduction
compounds are usually classified according to the me-
tal, to the donor atom, or to chelate ring size; by far
the most well-studied examples are five-membered
palladacycles containing nitrogen–Pd and C(phenyl)–
Pd bonds. The cyclometallation reaction, i.e., the
intramolecular activation of aromatic C–H bonds of
coordinated ligands by transition metals, has
been widely investigated [1–5]. They exhibit a good
Cyclometallated complexes are well documented for
a great variety of metal centres and ligands. These
*
Corresponding author. Tel.: +3481528073; fax: +34/981 595012.
E-mail addresses: qideport@usc.es (J.M. Vila), qiluaafl@udc.es
´
(J.J. Fernandez).
1
Fax: +34/981 167065.
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.04.039

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A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3670
number of applications which range from the synthesis
of new organic and organometallic compounds, to
mesogenic species and catalytic materials [6–14] as
well as promoting unusual coordination environments
[15].
2. Results and discussion
2.1. Preparation of the cyclometallated complexes
The compounds and reactions are shown in Schemes
1 and 2. The compounds described in this paper were
characterized by elemental analysis (C, H, N) and by
IR spectroscopy and by 1H, 31P–{1H} and, in part,
13C–{1H} NMR spectroscopy, FAB mass spectrometry
and X-ray single crystal diffraction (data in Section 4).
Reaction of C6H5N(H)N@CMe(C5H4N) (a) with
palladium(II) acetate in toluene at 60 ꢁC gave the mono-
nuclear cyclometallated complex [PdC6H4N(H)N@
CMe(C5H4N)(AcO)] (1a) which was fully characterized.
The IR spectrum of 1a showed the m(C@N) stretch at
1592 cmꢀ1, shifted to lower wavenumbers (as compared
to the uncoordinated phenylhydrazone) due to N-coor-
dination of the ligand [24,25]. The resonance assigned
In the past, we have been interested in palla-
dium(II) and platinum(II) cyclometallated complexes
derived from [C,N,X] (X = N, O, S) terdentate ligands
[16–22]. For example, Schiff bases readily react with
palladium(II) salts to give mononuclear cyclomet-
allated complexes with the ligand as [C,N,N0] terden-
tate [18–22]. Treatment of the latter with neutral
ligands such as tertiary mono- or diphosphines pro-
duced cleavage of the metal–N0 bond prior to ring-
opening of the five-membered metallacycle. When the
cyclometallated compound was treated first with a sil-
ver(I) salt the chlorine ligand was removed as silver
chloride and the vacant coordination site was occu-
pied by the phosphine [18–22]. The diphosphine che-
lated to the metal only when the complexes were
reacted with excess ligand. Furthermore, reaction of
the cyclometallated complexes with the tertiary
triphosphine (Ph2PCH2CH2)2PPh (triphos), produced
Pd–N bond cleavage upon chelation of triphos [20];
complexes with triphos coordinating three different
cyclometallated palladium(II) moieties were, to the
best of our knowledge, hitherto unknown.
In the present paper, we report the synthesis of
cyclometallated complexes derived from 2-acetylpyri-
dine phenylhydrazones with the ligand in a C,N,N0
terdentate fashion. Although the synthesis of com-
pound 3a has been previously reported [23], it is in-
cluded here because: (a) its crystal structure was
outstanding, and is now described in this work; (b)
it is an intermediate in the preparation of the phos-
phine derivatives. We have also found that the reac-
tion of the present complexes with tertiary
monophosphines, in the absence of AgCF3SO3, did
not produce cleavage of the Pd–Npyridine bond. We
therefore reasoned that the strong binding of the
phenylhydrazone ligand to the palladium atom, leav-
ing only one easily accessible coordination position,
should hinder chelation of the bi- or tridentate phos-
phines. However, this was not the case with di- and
triphosphines and chelation could only be prevented
by reaction of the cyclometallated complexes with
AgCF3SO3 followed by treatment with the tertiary
diphosphine Ph2P(CH2)4PPh2, dppb, or with the
triphosphines (Ph2PCH2CH2)2PPh, triphos, and
MeC(CH2PPh2)3, (tripod); in the latter case, to yield
the unprecedented trinuclear cyclometallated com-
plexes with the phosphine acting as a l3-bridging li-
gand. However, when the cyclometallated complex
was only reacted with excess triphos, a mononuclear
complex was obtained, with Pd–Npyridine bond
cleavage.
1
to the NH proton appeared at d 11.60 ppm in the H
NMR spectrum, downfield shifted by approximately
4 ppm (as compared to ligand a), confirming the forma-
tion of the cyclometallated ring (vide infra). The absence
of the H6 proton resonance showed that metallation oc-
curred at the C6 carbon. The strong bands assigned to
the symmetric and asymmetric m(COO) vibrations in
the IR spectrum, were in agreement with those expected
for terminal acetate ligands [26] (see Section 4). These
findings and the presence of a cluster of peaks centred
at 316 a.m.u. in the mass FAB spectrum corresponding
to the [M + H+–AcOH] fragment supported a mononu-
clear formulation for 1a.
Reaction of 2-ClC6H4N(H)N@CMe(C5H4N) Æ HCl
(b) with palladium(II) acetate in dichloromethane did
not yield the expected cyclometallated complex, similar
to 1a; instead, complex [Pd{2-ClC6H3N(H)N@CMe-
(C5H4N)}(Cl)] (1b) with a terminal chlorine ligand, was
obtained. The 1H NMR spectrum also showed the reso-
nance corresponding to the NH proton, downfield shifted
as compared to the uncoordinated ligand, and absence of
the H6 proton signal. Compound 1b could also be synthe-
sized by reaction of b with lithium tetrachloropalladate
and sodium acetate in methanol. However, reaction of b
with Pd2(dba)3 (dba; dibenzylideneacetone) did not give
the expected oxidative addition product; instead, a large
amount of black palladium and an untreatable reaction
mixture were obtained.
Treatment of a with lithium tetrachloropalladate and
sodium acetate in methanol for 24 h yielded the non-
cyclometallated complex [Pd{C6H5N(H)N@CMe(C5H4-
N)}(Cl)2] (2a) as an orange solid. In the 1H NMR
spectrum, a doublet signal at d 6.96 was assigned to
the H2 and H6 proton resonances, and a signal at d
8.66 to the NH proton. The latter was considerably less
downfield shifted, as compared to the uncoordinated li-
gand a, than in the cyclometallated derivatives of a. The
low-frequency shift of the m(C@N) stretch (as compared

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A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3671
Cl
N
Cl
N
Pd
H
N
2+
Me
R
Me
2a
N
Pd
Ph2
HN
P
-
N
2CF3SO3
Pd
vi
P
N
NH
Ph2
i
N
Me
4
R
v
3
2
5
6
R = H, 5a
R = Cl, 3b
R
1
HN
Cl
R
i
Pd
11
10
N
N
HN
ii
N
N
7
Me
8
9
Me
R = H, a
R = Cl, b
R = H, 3a
R = Cl, 1b
iv
+
ii
iii
PPh3
N
R
-
Pd
CF3SO3
HN
N
Me
OAc
Pd
R = H, 4a
R = Cl, 2b
HN
N
N
Me
1a
Scheme 1. (i) 3a, 1b, Li2PdCl4, (methanol, NaAcO); (ii) 1a, Pd(AcO)2, (toluene), 1b, Pd(AcO)2, (dichloromethane); (iii) NaCl (acetone/water); (iv) 1,
AgCF3SO3; 2, PPh3 (acetone, 1:1 molar ratio); (v) 1, AgCF3SO3; 2, dppb (acetone, 2:1 molar ratio); (vi) NaAcO, acetone.
to the free ligand) was indicative of coordination to the
nitrogen atom [25,26]. The low conductivity shown by
the solutions of 2a in dry acetonitrile and the presence
in the mass FAB spectrum of clusters of peaks at 317
[M + 2H+ ꢀ 2HCl] and 351 [M + H+ ꢀ HCl] a.m.u.
were in agreement with the mononuclear formulation
proposed for the complex.
In the course of this work Ghedini et al. [27] have
reported mononuclear cyclometallated compounds with
2-benzoyl-N-phenylhydrazones, inclusive of the crystal
structure of a similar compound to 3a; however, the
comprehensive reaction scheme for the mononuclear
compounds described here shows the full synthetic
routes between the ligands and compounds.
Reaction of a with lithium tetrachloropalladate and
sodium acetate in methanol for 48 h yielded the cyclo-
metallated complex [Pd{C6H4N(H)N@CMe(C5H4N)}-
(Cl)] (3a). The NMR and IR data were similar to those
described for 1a, vide supra, with the most noticeable
difference being the absence of the MeCOO signal, in
2.2. Crystal structure of 3a
Suitable crystals were grown by slowly evaporating a
chloroform/n-hexane solution of the complex. The molec-
ular structure is illustrated in Fig. 1. Crystal data are given
in Table 1 and selected bond distances and angles with
estimated standard deviations are shown in Table 2.
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 C(1) carbon atom of the phenyl ring,
the N(2) and pyridine N(3) nitrogen atoms, and to the
Cl(1) chlorine atom. The angles between adjacent atoms
in the coordination sphere of palladium are close to the
expected value of 90ꢁ with the most noticeable distor-
tions corresponding to the N(2)–Pd(1)–N(3) angle of
78.85(8)ꢁ and the N(3)–Pd(1)–Cl(1) angle of
101.04(6)ꢁ. The sum of the angles about palladium is
approximately 360ꢁ.
1
the H NMR spectrum, and the m(COO) bands in the
IR spectrum. The presence of a cluster of peaks centred
at 352 a.m.u. in the mass FAB spectrum corresponding
to the molecular ion confirmed the proposed formula-
tion. The 13C–{1H} NMR spectrum showed the
C@N, and C1 signals considerably downfield shifted
as compared to the uncoordinated ligand by ca.
10 ppm. The resonance for C6 was shifted to higher
frequency by ca. 20 ppm compared to the free donor,
confirming metallation of the carbon atom. There
was no noticeable quadrupolar broadening of these res-
onances by coupling with the 105Pd (22.2% natural
abundance, I = 5/2) nucleus. Complex 3a could also
be prepared by treatment of a solution of 1a with an
aqueous solution of sodium chloride, or alternatively,
by reaction of 2a with sodium acetate, although this
method gave low yields.
˚
The Pd(1)–N(2) 1.975(2) A and Pd(1)–N(3) 2.150(2)
bond distances are similar to others reported for related
compounds [21,23,28–30]. The Pd(1)–N(3) bond length

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A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3672
+
Ph2
P
-
Pd PPh
ClO4
HN
N
P
N
Ph2
Me
3+
HN
N
NH
N
Me
7a
Pd
Pd
P
P
Me
Me
Ph2
Ph2
-
N
N
3CF3SO3
iii
PPh2
Pd
N
i
N
N
H
Cl
R
Me
Pd
HN
6a
N
N
Me
Cl
ii
3+
Cl
R = H, 3a
R = Cl, 1b
HN
N
NH
N
Ph
Pd
Pd
-
P
P
3CF3SO3
Me
Me
Ph2
Ph2
P
N
N
N
Pd
N
N
H
Cl
Me
4b
Scheme 2. (i) 1, AgCF3SO3; 2, tripod (acetone, 3:1 molar ratio); (ii), 1, AgCF3SO3; 2, triphos (acetone, 3:1 molar ratio); (iii) 1, triphos (acetone, 1:1
molar ratio); 2, NaClO4.
is longer than Pd(1)–N(2) distance, showing the stronger
trans influence of the C(1) carbon atom as compared to
the Cl(1) chlorine. The Pd(1)–C(1) bond distance of
C3
C4
C2
˚
1.980(3) A is somewhat shorter than the value predicted
Cl1
from their covalent radii [31] but similar to values found
earlier [21,23,28–30].
C1
The geometry around the palladium atom [Pd(1),
C(1), N(2), N(3), Cl(1)] is planar (r.m.s. = 0.0186,
plane1). The metallated ring [Pd(1), C(1), C(6), N(1),
N(2), plane 2] and the coordination ring [Pd(1), N(2),
C(7), C(8), N(3), plane 3] are also planar (r.m.s. =
0.0027 and 0.0080, respectively). Planes 1, 2, 3, the met-
allated phenyl ring and the pyridine ring are nearly
coplanar (largest angle 3.7ꢁ between the metallated phe-
nyl and the pyridine rings).
C5
Pd1
C6
N1
N3
N2
C12
C11
C7
C8
2.3. Reactivity of the cyclometallated complexes
C10
C9
Treatment of 3a and 1b with silver trifluoro-
methanesulphonate (triflate) and triphenylphosphine in
Fig. 1. Molecular structure of [Pd{C6H4N(H)N@CMe(C5H4N)}(Cl)]
(3a), with labelling scheme. Hydrogen atoms have been omitted for
clarity.
acetone
gave
the
mononuclear
complexes
[Pd{C6H4N(H)N@CMe(C5H4N)}(PPh3)][F3CSO3] (4a)

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A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3673
Table 1
Crystal and structure refinement data
3a
4a
2b
Formula
Mr
C13H12N3ClPd
352.11
293(2)
C32H27F3N3O3PPdS
728.00
293(2)
C32H26ClF3N3O3PPdS Æ CHCl3
881.81
Temperature (K)
˚
Wavelength (A)
293(2)
0.71073
0.71073
Orthorhombic
Pbcn
0.71073
Triclinic
Crystal system
Space group
Unit cell dimensions
Triclinic
ꢀ
ꢀ
P1
P1
˚
a (A)
10.288(1)
11.532(1)
21.742(2)
10.180(1)
12.502(9)
13.986(11)
116.238(1)
97.976(1)
96.478(1)
1550.5(2)
2
10.654(1)
11.844(1)
14.647(1)
81.057(1)
80.041(1)
86.990(1)
1797.7(1)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
2579.5(3)
8
1.629
Z
l (mmꢀ1
Crystal size (mm)
)
1.559
0.34 · 0.18 · 0.10
56.6
1.629
0.50 · 0.45 · 0.20
56.6
0.55 · 0.40 · 0.35
56.6
2hmax (ꢁ)
Reflections
Collected
Unique
17058
9986
12422
3195 (Rint = 0.04)
0.59, 0.46
0.0285
7017 (Rint = 0.02)
0.92, 0.78
0.0453
8532 (Rint = 0.02)
0.83, 0.64
0.0330
Transmissions
R [F, I > 2r(I)]
wR [F2, all data]
0.0726
0.264
0.1298
0.861
0.0895
0.557
0.0087(5)
3
˚
max q (e A )
Extinction coefficient
Table 2
˚
Selected bond distances (A) and angles (ꢁ) for complexes 3a, 4a and 2b
3a
4a
2b
Pd(1)–C(1)
Pd(1)–N(2)
Pd(1)–N(3)
Pd(1)–Cl(1)
C(1)–C(6)
C(6)–N(1)
N(1)–N(2)
1.980(3)
1.975(2)
2.150(2)
2.3166(7)
1.409(4)
1.404(4)
1.362(3)
Pd(1)–C(1)
Pd(1)–N(2)
Pd(1)–N(3)
Pd(1)–P(1)
C(1)–C(6)
C(6)–N(1)
N(1)–N(2)
2.014(4)
2.028(3)
2.175(3)
2.278(1)
1.415(6)
1.390(5)
1.353(5)
Pd(1)–C(1)
Pd(1)–N(2)
Pd(1)–N(3)
Pd(1)–P(1)
C(1)–C(6)
C(6)–N(1)
N(1)–N(2)
2.007(2)
2.016(2)
2.155(3)
2.2816(6)
1.415(3)
1.402(3)
1.375(3)
C(1)–Pd(1)–N(2)
C(1)–Pd(1)–N(3)
N(2)–Pd(1)–N(3)
C(1)–Pd(1)–Cl(1)
N(3)–Pd(1)–Cl(1)
C(6)–C(1)–Pd(1)
C(1)–C(6)–N(1)
N(2)–N(1)–C(6)
N(2)–N(1)–Pd(1)
82.50(10)
161.35(10)
78.85(8)
97.59(8)
101.04(6)
111.2(2)
117.3(2)
114.2(2)
114.9(2)
C(1)–Pd(1)–N(2)
C(1)–Pd(1)–N(3)
N(2)–Pd(1)–N(3)
C(1)–Pd(1)–P(1)
N(3)–Pd(1)–P(1)
C(6)–C(1)–Pd(1)
C(1)–C(6)–N(1)
N(2)–N(1)–C(6)
N(2)–N(1)–Pd(1)
81.70(15)
157.97(15)
76.42(13)
94.02(12)
107.96(9)
110.5(3)
C(1)–Pd(1)–N(2)
C(1)–Pd(1)–N(3)
N(2)–Pd(1)–N(3)
C(1)–Pd(1)–P(1)
N(3)–Pd(1)–P(1)
C(6)–C(1)–Pd(1)
C(1)–C(6)–N(1)
N(2)–N(1)–C(6)
N(2)–N(1)–Pd(1)
81.58(8)
158.39(9)
76.91(7)
94.07(7)
107.52(5)
110.4(2)
120.0(2)
112.3(2)
115.7(1)
118.4(4)
115.4(3)
114.0(3)
and [Pd{2-ClC6H3N(H)N@CMe(C5H4N)}(PPh3)][F3C-
SO3] (2b) with the phosphine ligand occupying the va-
cant coordination position left by the chlorine ligand
with a phosphorus-to-nitrogen trans geometry [34–37].
The conductivity measurements carried out in dry aceto-
nitrile showed the complexes to be 1:1 electrolytes.
As we [18–22] have shown before, when cyclometal-
lated complexes derived from terdentate C,N,N0 ligands
with Pd–N bonds were reacted with tertiary phosphines
in the appropriate molar ratio, species with the phos-
phine coordinated to the metal centre were obtained,
with cleavage of, at least, one Pd–N bond; this was
prevented in those cases where a vacant coordination
was created by initial treatment with a silver(I) salt.
1
after AgCl removal. The H NMR spectra of the com-
plexes showed the hydrazine NH proton signal at d
10.31 (4J(HNP) = 4.4 Hz) and d 8.80 for 4a and 2b,
respectively. The upfield shift of the H5 and H11 reso-
nances (as compared to 3a and 1b) was due to shielding
by the phosphine phenyl rings [32,33], confirming coor-
dination of the ligand. The 31P–{1H} NMR spectra
showed a singlet resonance at ca. d 42 in accordance

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A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3674
However, when the complexes 3a and 1b reported here
were reacted directly with triphenylphosphine, without
previous removal of the chlorine ligand, no breakage
of the Pd–N bond was observed, putting forward the
greater strength of the Pd–Npyridine bond in these com-
pounds. The compounds obtained were 1:1 electrolytes,
bearing the same cation, with the anion being Clꢀ in-
stead of CF3SOꢀ3 .
C3
C2
C4
P1
C1
Cl1
C5
2.4. Crystal structures of 4a and 2b
C6
Pd1
Suitable crystals were grown by slowly evaporating
dichloromethane/n-hexane and chloroform/n-hexane
solutions of the complexes 4a and 2b, respectively. The
molecular structures are illustrated in Figs. 2 and 3.
Crystal data are given in Table 1 and selected bond dis-
tances and angles with estimated standard deviations are
shown in Table 2.
N1
N3
N2
C12
C7
C11
C8
C10
Both crystal structures comprise one [Pd{2-
RC6HnN(H)N@CMe(C5H4N)}(PPh3)]+ (R = H, n = 4,
4a; R = Cl, n = 3, 2b) cation and one CF3SOꢀ3 anion
per asymmetric unit.
C9
Fig. 3. Cation of [Pd{2-ClC6H3N(H)N@CMe(C5H4N)}(PPh3)][CF3-
SO3] (2b), with labelling scheme. Hydrogen atoms have been omitted
for clarity.
The palladium atom is bonded in a slightly distorted
square-planar geometry to the C(1) carbon atom of the
phenyl ring, the N(2) and pyridine N(3) nitrogen atoms,
and to the phosphorus atom of the triphenylphosphine
ligand P(1). The angles between adjacent atoms in the
coordination sphere of palladium are close to the ex-
pected value of 90ꢁ with the most noticeable distortions
corresponding to the N(2)–Pd(1)–N(3) [76.4(1)ꢁ and
76.91(7)ꢁ for 4a and 2b, respectively] and N(3)–Pd(1)–
P(1) [107.96(9)ꢁ and 107.52(5)ꢁ for 4a and 2b, respec-
tively] angles. The sum of the angles about palladium
is approximately 360ꢁ.
˚
The Pd–C [2.014(4) and 2.007(2) A, for 4a and
˚
2b, respectively], Pd–P [2.278(1) and 2.2816(6) A, for
4a and 2b, respectively], Pd–N(2) [2.028(3) and
˚
2.016(2) A, for 4a and 2b, respectively] and Pd–N(3)
˚
[2.175(3) and 2.155(3) A, for 4a and 2b] bond distances
are within the expected values for these type of com-
plexes [23,29,38,39]. The Pd–N(3) bond length shows
the larger trans influence of the C(1) carbon as com-
pared to the P(1) phosphorus.
The coordination sphere around palladium [Pd(1),
C(1), N(2), N(3), P(1)] is planar (r.m.s. = 0.0345 and
0.0759, for 4a and 2b, respectively; plane 1) with a small
tetrahedral distortion, probably caused by the steric hin-
drance of the triphenylphosphine ligand. The metallated
[Pd(1), C(1), C(6), N(1), N(2)] and the coordination
[Pd(1), N(2), C(7), C(8), N(3)] rings are also planar
(r.m.s. = 0.0088 and 0.0175 for 4a and 2b, respectively;
plane 2, and 0.0255 and 0.0221 for 4a and 2b, respec-
tively; plane 3) and coplanar with the metallated phenyl
and pyridine rings; consequently the 4a and 2b cations
are planar with the exception of the phosphine phenyls.
Hydrogen bonding between the N(1)–H(1) hydrogen
and O(1) oxygen atom of the triflate anion was found in
C3
C2
P1
C4
C1
Pd1
C5
C6
N3
C12
N1
N2
C11
C7
C8
C10
C9
˚
complex 2b [N(1)–H(1), 0.81(3) A; O(1) ꢁ ꢁ ꢁ H(1),
˚
˚
2.43(3) A; N(1)–H(1) ꢁ ꢁ ꢁ O(1), 3.160(3) A, 151(3)ꢁ].
Reaction of 3a and 1b with silver triflate and the ter-
tiary diphosphine Ph2P(CH2)4PPh2(dppb) in a 2:1 molar
Fig. 2. Cation of [Pd{C6H4N(H)N@CMe(C5H4N)}(PPh3)][CF3 SO3]
(4a), with labelling scheme. Hydrogen atoms have been omitted for
clarity.

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A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3675
ratio gave the dinuclear cyclometallated complexes
[{Pd{C6H4N(H)N@CMe(C5H4N)}2 (l-Ph2P(CH2)4-PPh2)]-
[CF3SO3]2 5a and [{Pd{2-ClC6H3N(H)N@CMe-
(C5H4N)}2(l-Ph2P(CH2)4PPh2)][CF3SO3]2 (3b) which
pared to 1b, both in the terminal cyclometallated
groups, as well as in the central one, by the influence
of the phosphine phenyl rings (see Section 4). The 31P–
{1H} NMR spectrum showed a doublet at d 35.9 as-
signed to the two equivalent terminal phosphorus nuclei,
and a triplet at d 33.1, for the central phosphorus nu-
cleus. All chemical shifts were characteristic of a P–
Pd–N trans geometry [34–37].
Treatment of 3a with the tertiary triphosphine
(Ph2PCH2CH2)2PPh (triphos), in a 1:1 molar ratio, fol-
lowed by sodium perchlorate, gave the mononuclear
complex [Pd{C6H4N(H)N@CMe(C5H4N)}{(PPh2CH2-
CH2)2PPh–P,P,P}][ClO4] (7a) as an air-stable solid,
which was fully characterized (see Section 4). The con-
ductivity data in acetonitrile solution showed the com-
pound was a 1:1 electrolyte. The FAB-mass spectrum
showed a set of peaks centred at 851 uma assigned to
the [M + H+ ꢀ HClO4] fragment.
1
were fully characterized (see Section 4). The H NMR
spectra of the complexes were analogous to those de-
scribed for complexes 4a and 2b, suggesting a similar
coordination situation for the palladium atoms. The
symmetric nature of the complexes was established by
the presence of only one singlet signal in the 31P–1H
spectra ca. d 29.5. The conductivity measurements car-
ried out in dry acetonitrile have shown the complexes
to be 1:2 electrolytes. The mass-FAB spectra have
shown the presence of clusters of peaks centred at
1209 and 1277 uma, for 5a and 3b, respectively, corre-
sponding to the loss of one triflate counteranion.
2.5. Reactions with triphosphines
The phosphorus resonances in the 31P–{1H} NMR
spectrum were downfield shifted from their values in
the free phosphine suggesting coordination of the three
phosphorus atoms to the metal centre. A triplet reso-
nance at d 94.2 was assigned to the central 31P nucleus,
trans to the phenyl carbon atom, and a doublet at d 21.8
was assigned to the two equivalent mutually trans phos-
phorus nuclei. The latter signal appeared at lower fre-
quency in accordance with the high trans influence of
the phosphine ligand [34]. The resonance of the proton
in the ortho position to the metallated carbon appeared
as a triplet showing coupling to the central 31P atom
[J(PH5) = 7.1 Hz]; no coupling was observed to the ter-
minal phosphorus nuclei. These data are in accordance
with a disposition in which the metallated ring is nearly
perpendicular to the plane defined by the three phospho-
rus atoms [15,40]. The shift of the m(C@N) stretching
vibration to lower wavenumbers indicates the existence
of palladium–nitrogen interaction. These results
strongly agree with those previously obtained by us in
related penta-coordinated palladium(II) species, and
hence we propose a similar disposition of the triphos li-
gand in this case [15,40]. The H11 proton resonance ap-
peared at d 8.49, downfield shifted as compared to the
phosphine derivatives of ligand a mentioned above, indi-
cating that H11 does not fall within the shielding zone of
the phosphine phenyl rings, due to the cleavage of the
Pd–Npyridine bond.
Treatment of 3a with silver triflate followed by reac-
tion with the tertiary triphosphine MeC(CH2PPh2)3 (tri-
pod) in a 3:1 molar ratio, gave the unprecendented
trinuclear complex [{Pd[C6H4N(H)N@CMe(C5H4N)]}3
{l3–CH3C(CH2Ph2)3}][CF3SO3]3 (6a) as an air-stable
solid, which was fully characterized (see Section 4).
The conductivity data in acetonitrile solution showed
the compound was a 1:3 electrolyte. The 1H NMR spec-
trum of the complex showed only one set of signals in
accordance with three equivalent cyclometallated moie-
ties, each of which was bonded to one of the phosphorus
atoms of the terdentate phosphine ligand, and whose
pattern was similar to that of compound 4a, i.e., with
the NH signal ca. d 10 and the resonances corresponding
to H5 and H11 protons shifted to high field, due to the
shielding effect of the phosphine phenyl rings. Likewise,
only one signal at d 3.3 (multiplet, 6H) was assigned to
the three phosphine methylene groups. The 31P–{1H}
NMR spectrum showed only one singlet resonance at
d 23.2, for the three equivalent phosphorus nuclei, a va-
lue in agreement with a P–Pd–N trans geometry [34–37].
Treatment of 1b with silver triflate followed by reac-
tion with the tertiary triphosphine (Ph2PCH2CH2)2PPh
(triphos), in a 3:1 molar ratio, gave the new trinuclear
complex [{Pd[2-ClC6H3N(H)N@CMe(C5H4N)]}3{l3-
(PPh2CH2CH2)2PPh}][CF3SO3]3 (4b) as an air-stable so-
lid, which was fully characterized (see Section 4). The
conductivity data in acetonitrile solution showed the
compound was a 1:3 electrolyte. The 1H NMR spectrum
showed two groups of resonances with an integration ra-
tio of 2:1; one assigned to the two equivalent cyclomet-
allated groups coordinated to the terminal phosphorus
atoms, and the other one to the cyclometallated moiety
bonded to the central phosphorus atom. The NH proton
resonances were at d 10.01 for the former, and at d 9.90
for the latter. The signals corresponding to the H5 and
H11 protons were shifted to lower frequency, as com-
3. Conclusions
We have shown that 2-acetylphenylhydrazones may
be readily metallated at the phenyl ring by palladium(II)
salts rendering mononuclear cyclometallated com-
pounds with chlorine or mono-coordinated acetate li-
gands, and with the organic moiety as terdentate
through the aromatic carbon atom, and the azomethine

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A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3676
and pyridine nitrogen atoms, with two fused rings at the
metal centre: the metallacycle and the coordination ring.
Varying the reaction conditions, in the present case a
lower reaction time suffices, may only lead to coordina-
tion compounds with absence of a Pd–C bond, that in
turn may be transformed into the corresponding cyclo-
metallated species. The reactivity of the latter towards
tertiary phosphines leads to the mono-, di or trinuclear
compounds. These trinuclear species are the first exam-
ples of a triphosphine acting as a l3-bridging ligand and
linking three cyclometallated moieties together. The
strength of the Pd–Npyridine bond hinders ring opening
upon reaction of the compounds with triphenylphos-
phine, even in the absence of a silver(I) salt. However,
with bi- or tridentate phosphines chelation prevails
and Pd–Npyridine bond cleavage may only be prevented
by treatment of the compounds with silver trifluorome-
thanesulfonate, prior to the reaction with the corre-
sponding phosphine.
temperature (r.t.). The yellow precipitate formed was fil-
tered off and dried in air. Yield 58%. Anal. Found: C,
73.7; H, 6.1; N, 19.8. C13H13N3 requires C, 73.9; H,
6.2; N, 19.9%. IR: m(C@N), 1604s cmꢀ1, m(NAH),
3205, 3175m cmꢀ1 1H NMR (200 MHz, CDCl3, d
.
ppm, J Hz): 2.40 [s, 3H, Me]; 7.60 [s, 1H, NH]; 8.57
[dd, 1H, H11, 3J(H11H10) = 3.9, 4J(H11H9) = 0.9];
3
6.91 [dt, 1H, J(HH) = 6.8, J(HH) = 1.5], 7.3 [m, 5H];
4
3
4
7.69 [dt, 1H, J(HH) = 8.3, J(HH) = 1.9]; 8.19 [d, 1H,
3J(HH) = 8.3]. 13C–1H NMR (50.28 MHz, CDCl3, d
ppm): 148.8, 147.5, 144.4 (C@N, C1, C7); 147.3 (C11);
129.2 (C3, C5); 136.6 (C9); 122.8, 120.7 (C8, C10);
113.5 (C2, C6); 122.2 (C4); 10.0 (Me). Specific
molar conductivity, Km = 2.9 ohmꢀ1 cm2 molꢀ1 (in
acetonitrile).
Compound b was prepared similarly from 2-chloro-
rophenylhydrazine hydrochloride as a yellow solid.
4.2.2. 2-ClC6H4N(H)N@CMe(C5H4N) Æ HCl b
Yield 78%. Anal. Found: C, 58.6; H, 4.7; N, 10.1.
C13H12N3Cl Æ HCl requires C, 58.2; H, 4.9; N, 10.4%.
4. Experimental
IR: m(C@N), 1609s cmꢀ1, m(NAH), 3265m cmꢀ1 1H
.
NMR (200 MHz, CDCl3, d ppm, J Hz): 2.68 [s, 3H,
Safety note. Caution: perchlorate salts of metal com-
plexes with organic ligands are potentially explosive.
Only small amounts of these materials should be pre-
pared and handled with great caution.
Me]; 6.99 [t, 1H, 3J(HH) = 7.5]; 7.4 [m, 2H]; 7.6 [m,
3
1H]; 8.01 [d, 1H, J(HH) = 7.8]; 8.3 [m, 2H]; 8.61 [s,
3
1H, NH]; 8.97 [d, 1H, H11, J(H11H10) = 4.8]; specific
molar conductivity, Km = 42.3 ohmꢀ1 cm2 molꢀ1 (in
acetonitrile).
4.1. General procedures
4.2.3. Preparation of [Pd{C6H4N(H)N@CMe-
(C5H4N)}(OAc)] 1a
Solvents were purified by standard methods [41].
Chemicals were reagent grade. The phosphines PPh3,
Ph2P(CH2)4PPh2(dppb), (Ph2PCH2CH2)2PPh (triphos)
and MeC(CH2PPh2)3 (tripod) were purchased from Al-
drich-Chemie. Microanalyses were carried out using a
Carlo Erba Elemental Analyzer, Model 1108. IR spectra
were recorded as Nujol mulls or KBr discs on a Perkin–El-
mer 1330 and on a Mattson spectrophotometers. NMR
spectra were obtained as CDCl3 solutions and referenced
to SiMe4 (1H, 13C–{1H}) or 85% H3PO4 31P–({1H}) and
were recorded on a Bruker AC-2005 spectrometer. All
chemical shifts were reported downfield from standards.
The FAB mass spectra were recorded using a Quatro mass
spectrometer with a Cs ion gun; 3-nitrobenzyl alcohol
(3-NBA), 2-hydroxyethyl disulfide (2-HEDS) or 3-
mercapto-1,2-propanediol (1-thioglycerol) were used as
the matrix. Conductivity measurements were made on a
CRISON GLP 32 conductivimeter using 10ꢀ3 mol dmꢀ3
solutions in dry acetonitrile.
A
pressure tube containing C6H5N(H)N@
CMe(C5H4N), a, (138 mg, 0.65 mmol), palladium(II)
acetate (146 mg, 0.65 mmol) and 20 cm3 of dry toluene
was sealed under argon. The resulting mixture was
heated at 60 ꢁC for 12 h. After cooling to r.t., the solu-
tion was filtered through cellite to remove the black pal-
ladium formed. The solvent was removed under vacuum
to give a yellow solid. Yield 51%. Anal. Found: C, 48.0;
H, 4.1; N, 11.0. C15H15N3O2Pd requires C, 47.9; H, 4.0;
N, 11.2%. IR: m(C@N), 1592s cmꢀ1, m(N–H), 3125m
cmꢀ1; mas (COO), 1504m cmꢀ1; ms(COO), 1385m cmꢀ1
.
1H NMR (200 MHz, CDCl3, d ppm, JHz): 2.04 [s, 3H,
AcO]; 2.24 [s, 3H, Me]; 6.2, 6.1 [m, 3H, H2, H3, H4];
6.8 [m, 3H, H5, H8, H10]; 7.60 [t, 1H, H9,
3J(H10H9) = 7.8]; 7.95 [d, 1H, H11, 3J(H11H10) =
4.4]; 11.6 [s, 1H, NH]. FAB-MS: m/z = 316
[M + H+ ꢀ AcOH], (in 3-NBA and 2-HEDS).
4.2.4. Preparation of [Pd{2-ClC6H3N(H)N@CMe-
(C5H4N)}(Cl)] 1b
4.2. Syntheses
Method 1.
A
pressure tube containing 2-
4.2.1. Preparation of C6H5N(H)N@CMe(C5H4N) a
A mixture of phenylhydrazine (1.02 g, 8.42 mmol), 2-
acetylpyridine (0.92 g, 8.42 mmol) and 0.1 cm3 of acetic
acid in 50 cm3 of ethanol was stirred for 4 h at room
ClC6H4N(H)N@CMe(C5H4N) Æ HCl (b) (22 mg, 0.08
mmol), palladium(II) acetate (18 mg, 0.08 mmol) and
20 cm3 of dry dichloromethane was sealed under argon.
The resulting mixture was stirred for 12 h at room tem-

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A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3677
perature (r.t.) and the solvent removed under vacuum to
give a yellow solid. Yield 58%.
CDCl3, d ppm, J Hz): 2.32 [s, 3H, Me]; 6.5 [m, 2H,
H2, H4]; 6.83 [dt, 1H, H3, 3J(H4H3) = 7.6, 4J(H5-
H3) = 1.4]; 7.11 [dd, 1H, H5, 3J(H5H4) = 7.3,
Method 2. A stirred solution of lithium tetrachloro-
palladate (200 mg, 0.76 mmol) in methanol 50 cm3 was
treated with 2-ClC6H4N(H)N@CMe(C5H4N) Æ HCl (a)
(200 mg, 0.76 mmol) and sodium acetate (63 mg,
0.76 mmol). The mixture was stirred at room tempera-
ture for 24 h. The yellow precipitate formed was filtered
off, and dried in air. Yield 65%. Anal. Found: C, 40.3;
H, 2.9; N, 11.0. C13H11N3Cl2 Pd requires C, 40.4; H,
2.9; N, 10.9%. IR: m(C@N), 1577s cmꢀ1, m(NAH),
3
4J(H5H3) = 1.4]; 7.52 [dt, 1H, H10, J(H11H10) = 5.5,
4J(H10H8) = 0.9]; 7.68 [d, 1H, H8, 3J(H9H8) = 7.8];
8.03 [dt, 1H, H9, 3J(H10H9) = 7.8, 4J(H11H9) = 1.4];
8.32 [dd, 1H, H11, 3J(H11H10) = 5.5, 4J(H11H9)
= 1.4]; 10.7 [s, 1H, NH]. 13C–{1H} NMR (50.28 MHz,
CDCl3, d ppm): 158.0, 156.0, 144.0 (C@N, C1, C7);
148.6 (C11); 134.8 (C6); 140.6, 135.4, 125.8, 125.5,
123.2, 119.4, 108.7 (C2, C3, C4, C5, C8, C9, C10);
12.8 (Me). FAB-MS: m/z = 316 [M + H+ ꢀ HCl], (in 3-
NBA).
3270m cmꢀ1 1H NMR (200 MHz, CDCl3, d ppm,
.
JHz): 2.42 [s, 3H, Me]; 6.60 [t, 1H, H4, 3J(H4H3) =
7.3]; 6.94, 7.12 [d, 2H, H3, H5, 3J(HH) = 7.3, 6.8];
7.62 [t, 1H, H10, 3J(H10H9) = 7.8]; 7.82 [d, 1H, H8,
3J(H9H8) = 7.8]; 8.10 [t, 1H, H9, 3J(H10H9) = 7.8];
8.39 [d, 1H, H11, 3J(H11H10) = 3.9]; 10.14 [s, 1H,
NH]. FAB-MS: m/z = 351 [M + H+ ꢀ HCl], (in 3-
NBA).
4.2.7. Preparation of [Pd{C6H4N(H)N@CMe-
(C5H4N)}(PPh3)][F3CSO3] 4a
Silver trifluoromethanesulfonate (46 mg, 0.18 mmol)
was added to a solution of 2a (63.9 mg, 0.18 mmol) in ace-
tone (15 cm3). The resulting mixture was stirred for 2 h
and filtered through celite to remove the AgCl precipitate.
PPh3 (47.3 mg, 0.18 mmol) was added to the filtrate, the
solution stirred for another 2 h and the solvent removed
to give an orange solid which was recrystallized from ace-
tone/hexane. Yield 41%. Anal. Found: C, 52.6; H, 3.9; N,
5.8. C32H27N3O3F3 PSPd requires C, 52.7; H, 3.7; N,
4.2.5. Preparation of [Pd{C6H5N(H)N@CMe-
(C5H4N)}(Cl)2] 2a
A stirred solution of lithium tetrachloropalladate
(200 mg, 0.76 mmol) in methanol 50 cm3 was
treated with C6H5N(H)N@CMe(C5H4N) (a) (162 mg,
0.76 mmol) and sodium acetate (63 mg, 0.76 mmol).
The mixture was stirred to room temperature for 24 h.
The orange precipitate formed was filtered off, and dried
in air. Yield 88%. Anal. Found: C, 40.4; H, 3.3; N, 10.7.
C13H13N3Cl2Pd requires C, 40.2; H, 3.4; N, 10.8%. IR:
5.7%. IR: m(C@N), 1599s cmꢀ1, m(NAH), 3125s cmꢀ1
.
1H NMR (200 MHz, CDCl3, d ppm, J Hz): 2.49 [s, 3H,
3
Me]; 5.90 [d, 1H, H11, J(H11H10) = 4.5]; 6.05 [m, 2H,
H4, H5]; 6.75 [m, 2H]; 6.95 [d, 1H, H2, 3J(H3H2) = 7.8];
10.31 [d, 1H, NH, 4J(P–NH) = 4.4]. 31P–1H NMR
(80.96 MHz, CDCl3, d ppm) 42.0s. Specific molar con-
ductivity, Km = 136.4 ohmꢀ1 cm2 molꢀ1 (in acetonitrile).
Compounds 2b and 5a were obtained following a
similar procedure, using a complex/diphosphine 1:1
and 2:1 molar ratios, respectively, as yellow solids.
1
m(C@N), 1596s cmꢀ1, m(NAH); 3227s cmꢀ1. H NMR
(200 MHz, CDCl3, d ppm, J Hz): 2.32 [s, 3H, Me];
6.96 [d, 2H, H2, H6, 3J(H3H2) = 7.8]; 7.13 [t, 1H,
H4, 3J(H5H4) = 7.8]; 7.37 [t, 2H, H3, H5, 3J(H4H3)
= 7.8]; 7.75 [dt, 1H, H10, 3J(H11H10) = 6.8,
4J(H10H8) = 1.4]; 7.95 [dd, 1H, H8, 3J(H9H8) =
4
4
7.8, J(H10H8) = 1.4]; 8.25 [dt, 1H, H9, J(H11H9) =
3
4.2.8. [Pd{2-ClC6H3N(H)N@CMe(C5H4N)}(PPh )]
3
1.4, J(H9H8) = 7.8]; 8.66 [s, 1H, NH]; 9.18 [dd, 1H,
[F3CSO3] 2b
Yield 54%. Anal. Found: C, 50.4; H, 3.5; N, 5.7.
C32H26N3O3F3PSClPd requires C, 50.4; H, 3.4; N,
H11, 3J(H11H10) = 6.8, 4J(H11H9) = 1.4]. FAB-MS:
m/z = 317 [M + 2H+ ꢀ 2HCl], 351 [M + H+ ꢀ HCl] (in
3-NBA).
5.5%. IR: m(C@N), 1569s cmꢀ1, m(NAH), 3180m cmꢀ1
.
1H NMR (200 MHz, CDCl3, d ppm, J Hz): 2.64 [s,
3H, Me]; 6.1 [m, 3H, H4, H5, H11]; 6.85 [m, 2H]; 8.80
[s, 1H, NAH]. 31P–1H NMR (80.96 MHz, CDCl3, d
ppm) 41.5s. Specific molar conductivity, Km =
125.6 ohmꢀ1 cm2 molꢀ1 (in acetonitrile). FAB-MS:
m/z = 613 [MH–CF3SO3]+ (in 3-NBA).
4.2.6. Preparation of [Pd{C6H4N(H)N@CMe-
(C5H4N)}(Cl)] 3a
Method 1. Complex 3a was obtained following a sim-
ilar procedure to the one used for 2a but stirring the
reaction mixture for 48 h, as a yellow solid. Yield 80%.
Method 2. An aqueous solution of NaCl (ca. 10ꢀ2 M)
was added dropwise to a solution of 1a (68 mg,
0.08 mmol) in 15 cm3 of acetone. The resulting mixture
was stirred for 24 h. The orange precipitate formed
was filtered of, washed with water and dried under vac-
uum to give complex 3a as an orange solid. Yield 85%.
Anal. Found: C, 44.4; H, 3.3; N, 11.8. C13H12N3ClPd re-
quires C, 44.3; H, 3.4; N, 11.9%. IR: m(C@N), 1599s
4.2.9. Preparation of [{Pd[C6H4N(H)N@CMe-
(C5H4N)]}2(l-Ph2P(CH2)4PPh2)][F3CSO3]2 5a
Yield 46%. Anal. Found: C, 49.5; H, 3.9; N, 6.1.
C56H52N6O6F6P2S2Pd2 requires C, 49.5; H, 3.9; N,
6.2%. IR: m(C@N), 1598s cmꢀ1, m(NAH), 3220s cmꢀ1
.
1H NMR (200 MHz, CDCl3, d ppm, J Hz): 2.40 [s,
3H, Me]; 5.88 [t, 2H, H4, 3J(H4H3) = 7.3]; 6.09 [dt,
1H, H5, 3J(H5H4) = 7.3, 4J(PH5) = 5.3]; 6.19 [d, 1H,
cmꢀ1, m(NAH), 3228s cmꢀ1
.
1H NMR (200 MHz,

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3678
3
H11, J(H11H10) = 4.9]; 6.6 [m, 2H]; 6.79 [d, 1H, H2,
3J(H3H2) = 7.3]; 10.06 [d, 1H, NH, 4J(P–HN) = 3.4].
31P–{1H} NMR (80.96 MHz, CDCl3, d ppm) 29.8s. Spe-
cific molar conductivity, Km = 217 ohmꢀ1 cm2 molꢀ1
(in acetonitrile). FAB-MS: m/z = 1209 [M + H+ ꢀ
CF3SO3H], 743 [M + 2H+ ꢀ 2CF3SO3H-L-Pd], (in 2-
HEDS).
m/z = 886 [M + 3H+ ꢀ 3CF3SO3H–L–Pd], (in 3-NBA,
2-HEDS and 1-thioglycerol).
4.2.13. Preparation of [Pd{C6H4N(H)N@CMe-
(C5H4N)}{(PPh2CH2CH2)2PPh-P,P,P}][ClO4] 7a
(PPh2CH2CH2)2PPh (98 mg, 0.18 mmol) was added to
a suspension of 3a (65 mg, 0.18 mmol) in acetone
(20 cm3). The mixture was stirred for 1 h, after which an
excess of sodium perchlorate was added. The mixture
was stirred for a further 4 h and the orange complex pre-
cipitated out by addition of water, filtered off and dried in
vacuo. Yield 90%. Anal. Found: C, 59.1; H, 4.8; N, 4.1.
C47H45N3O4ClP3Pd Æ CH2Cl2 requires C, 59.3; H, 4.7;
N, 4.4%. IR: m(C@N), 1562s cmꢀ1, m(NAH), 3052s
Compound 3b was prepared similarly, as a green solid.
4.2.10. [{Pd[2-ClC6H3N(H)N@CMe(C5H4N)]}2-
(l-Ph2P(CH2)4PPh2)][F3CSO3]2 3b
Yield 54%. Anal. Found: C, 47.2; H, 3.5; N, 6.0.
C56H50N6O6Cl2F6P2S2Pd2 requires C, 47.1; H, 3.5; N,
5.9%. IR: m(C@N), 1599s cmꢀ1, m(NAH), 3202m cmꢀ1
.
1H NMR (200 MHz, CDCl3, d ppm, J Hz): 2.59 [s,
3H, Me]; 6.0 [m, 2H, H4, H5]; 6.42 [d, 1H, H11, J
cmꢀ1. H NMR (200 MHz, CDCl3, d ppm, J Hz): 1.85
1
[s, 3H, Me]; 6.07 [t, 1H, H5, 3J(H5H4) = 7.1,
4J(PH5) = 7.1]; 6.30 [t, 1H, H4, 3J(H3H4) = 7.1]; 8.49 [s,
1H, H11, 3J(H10H11) = 3.9]. 31P–{1H} NMR
(80.96 MHz, CDCl3, d ppm) 94.2t, 21.8d [J(PP) =
21.8]. Specific molar conductivity, Km = 150.4 ohmꢀ1
cm2 molꢀ1 (in acetonitrile). FAB-MS: m/z = 851 [M +
H+ ꢀ HClO4], (in 3-NBA).
3
(H11H10) = 4.9]; 6.61 [d, 1H, H3, 3J (H4H3) = 7.8];
6.82 [t, 1H, J (HH) = 6.1]; 9.01 [d, 1H, NH, 4J (P–
3
HN) = 3.4]. 31P–{1H} NMR (80.96 MHz, CDCl3, d
ppm) 29.3s. Specific molar conductivity, Km =
250 ohmꢀ1 cm2 molꢀ1 (in acetonitrile). FAB-MS:
m/z = 1277 [M + H+ ꢀ CF3SO3H], 778 [M + 2H+ ꢀ
2CF3SO3H–L–Pd], (in 2-HEDS).
Compounds 6a and 4b were obtained following a
similar procedure as orange solids, but using a com-
plex/triphosphine 3:1 molar ratio.
4.2.14. X-ray crystallographic study
Three-dimensional, room temperature X-ray data
were collected on a Siemens Smart CCD diffractometer
by the x scan method using graphite-monochromated
Mo Ka radiation. All the measured reflections were cor-
rected for Lorentz and polarisation effects and for absorp-
tion 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 calcu-
lated positions (except the N–NH hydrogens which were
located in a difference Fourier map) and refined in riding
mode. The S(1), C(1s), F(3) and O(1), atoms of the trif-
luoromethanesulphonate ion in complex 4a were found
to be disordered over two positions (with occupancies of
approximately 50%). The refinement was carried out tak-
ing into account both components. Refinement con-
verged at a final R = 0.0285, 0.0453 and 0.0330 (for
complexes 3a, 4a and 2b, respectively, observed data, F)
and wR2 = 0.0726, 0.1298 and 0.0895 (for complexes 3a,
4a and 2b, respectively, unique data, F2), with allowance
for thermal anisotropy of all non-hydrogen atoms. The
structure solution and refinement were carried out using
the program package SHELX-97 [42].
4.2.11. [{Pd[C6H4N(H)N@CMe(C5H4N)]}3{l3-CH3C-
(CH2Ph2)3P}][F3CSO3]3 6a
Yield 40%. Anal. Found: C, 49.5; H, 3.7; N, 6.1.
C83H75N9O9F9P3S3Pd3 requires C, 49.3; H, 3.7; N,
6.2%. IR: m(C@N), 1598s cmꢀ1, m(NAH), 3206s cmꢀ1
.
1H NMR (200 MHz, CDCl3, d ppm, J Hz): 2.05 [s,
3H, Me], 2.44 [s, 9H, Me], 3.3 [m, 6H, CH2], 6.07,
6.47 [m, 3H, H4, H5, H11], 10.9 [s, 1H, NH]. 31P–
{1H} NMR (80.96 MHz, CDCl3, d ppm) 23.2s. Specific
molar conductivity, Km = 374 ohmꢀ1 cm2 molꢀ1 (in ace-
tonitrile). FAB-MS: m/z = 942 [M + 3H+ ꢀ 3CF3SO3H–
L–Pd], (in 3-NBA and 2-HEDS).
4.2.12. [{Pd[2-ClC6H3N(H)N@CMe(C5H4N)]}3{l3-
(PPh2CH2CH2)2PPh}][F3CSO3]3 4b
Yield 23%. Anal. Found: C, 44.7; H, 3.3; N, 6.1.
C76H66N9O9Cl3F9P3S3Pd3 requires C, 44.8; H, 3.3; N,
6.2%. IR: m(C@N), 1583s cmꢀ1, m(NAH), 3220m cmꢀ1
.
1H NMR (200 MHz, CDCl3, d ppm, J Hz): 2.48, 2.63
[s, 6H, Me, s, 3H, Me], 2.9 [m, 4H, CH2], 3.3 [m, 4H,
CH2], 5.4, 5.7 [t, 1H, H5, t, 2H, H5, J(PH5) = 7.5,
3J(H4H5) = 7.5]; 5.87 [m, 1H, H4]; 6.10 6.32 [d, 1H,
H11, d, 2H, H11, 3J(H11H10) = 5.1]; 6.47, 6.59 [d,
1H, H3, d, 2H, H3, 3J(H4H3) = 7.7]; 9.90, 10.01 [s,
1H, NH, s, 2H, NAH]. 31P–{1H} NMR (80.96 MHz,
CDCl3, d ppm) 35.9d, 33.1t, J(PP) = 34.7. Data in italics
are for the cyclometallated fragment bonded to the cen-
tral phosphorus atom. Specific molar conductivity,
Km = 370 ohmꢀ1 cm2 molꢀ1 (in acetonitrile). FAB-MS:
5. Supplementary material
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data
Centre as supplementary Publication No. 259264 (2b),
No. 259265 (3a), and No. 259266 (4a). Copies of the

´
A. Fernandez et al. / Journal of Organometallic Chemistry 690 (2005) 3669–3679
3679
´
[19] J.M. Vila, M.T. Pereira, J.M. Ortigueira, D. Lata, M. Lopez-
´ ´
Torres, J.J. Fernandez, A. Fernandez, H. Adams, J. Organomet.
data can be obtained free of charge on application to
The Director, CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK, e-mail: deposit@ccdc.cam.ac.uk.
Chem. 566 (1998) 93.
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[20] A. Fernandez, J.J. Fernandez, M. Lopez-Torres, A. Suarez, J.M.
Ortigueira, J.M. Vila, H. Adams, J. Organomet. Chem. 612
(2000) 85.
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[21] A. Fernandez, P. Urıa, J.J. Fernandez, M. Lopez-Torres, A.
Sua´rez, D. Va´zquez-Garc´ıa, M.T. Pereira, J.M. Vila, J. Organo-
met. Chem 620 (2001) 8.
Acknowledgements
´
We thank the Ministerio de Educacion y Cultura
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(Proyecto PGIDIT03PXIC1050PN) and the Universi-
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dination Compounds, fifth ed., Wiley, New York, 1997.
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¨