Cyclometallated complexes derived from pyrimidin- and pyridazinehydrazones: Structural evidence of intermolecular "chelate metal ring" π-π interactions

Article abstract of DOI:10.1016/j.jorganchem.2009.03.003

Reaction of 3,4-(Me)₂C₆H₃C(Me){double bond, long}NN(H)[3′-(CF₃)C₄H₂N₂] (a) and 3,4-(Me)₂C₆H₃C(Me){double bond, long}NN(H)(4′-ClC₄H₂N₂) (b) with palladium(II) acetate gave the mononuclear cyclometallated complexes [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)[3′-(CF₃)C₄H₂N₂]}(OAc)] (1a) and [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)(4′-ClC₄H₂N₂)}(OAc)] (1b) with the ligand as terdentate [C,N,N]. Treatment of a and b with Li₂[PdCl₄] and sodium acetate in methanol at room temperature yielded the mononuclear cyclometallated complexes [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)[3′-(CF₃)C₄H₂N₂]}(Cl)] (2a) and [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)(4′-ClC₄H₂N₂)}(Cl)] (2b), respectively. Recrystallization of 2b from a dimethylsulfoxide solution gave [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(4′-ClC₄H₂N₂)}][(CH₃)₂S{double bond, long}O] after deprotonation of the hydrazine nitrogen. The reaction of 2a and 2b with silver trifluoromethanesulfonate and triphenylphosphine, yielded [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)[3′-(CF₃)C₄H₂N₂]}-(PPh₃)][CF₃SO₃] (3a) and [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)(4′-ClC₄H₂N₂)}(PPh₃)]-[CF₃SO₃] (3b) with the phosphine ligand occupying the vacant coordination position after chlorine abstraction; these were deprotonated at the hydrazine nitrogen after treatment with sodium acetate. Reaction of 2a with Ph₂P(CH₂)₂AsPh₂ (arphos), after AgCl removal gave mononuclear complex Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)[3′-(CF₃)C₄H₂N₂]}(Ph₂P(CH₂)₂AsPh₂)][ClO₄] (5a) with a non-coordinated As atom. Reaction of 2a and 2b with a Ag(I) salt and the tertiary diphosphine Ph₂P(CH₂)₄PPh₂ (dppb) in 2:1 molar ratio gave the dinuclear complexes [{Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)[3′-(CF₃)C₄H₂N₂]}}₂(μ-Ph₂P(CH₂)₄PPh₂)][CF₃SO₃]₂ (6a) and [{Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)(4′-ClC₄H₂N₂)}}₂(μ-Ph₂P(CH₂)₄PPh₂)][ClO₄]₂ (6b) with the diphosphine as a bridging ligand. Similarly, treatment of 1b with silver triflate followed by reaction with the tertiary triphosphine (Ph₂PCH₂CH₂)₂PPh (triphos), in a 3:1 molar ratio, gave the new trinuclear complex [{Pd[3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)(4′-ClC₄H₂N₂)]}₃{μ₃-(Ph₂PCH₂CH₂)₂PPh}][CF₃SO₃]₃ (8b). However, reaction of 2a and 2b with (triphos), in 1:1 molar ratio gave the mononuclear complexes [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)[3′-(CF₃)C₄H₂N₂]}{(Ph₂PCH₂CH₂)₂PPh-P,P,P}][ClO₄] (7a) and [Pd{3,4-(Me)₂C₆H₂C(Me){double bond, long}NN(H)(4′-ClC₄H₂N₂)}-{(Ph₂PCH₂CH₂)₂PPh-P,P,P}][ClO₄] (7b) with a is five-coordinated palladium. The crystal structures of 2b, 3a, 3b, 7a and 7a have been determined by X-ray crystallography and they show π-π interactions between the metallacycle and the heterocyclic pyrimidine or pyridazine rings, which controls the crystal packing.

Full text of DOI:10.1016/j.jorganchem.2009.03.003

Journal of Organometallic Chemistry 694 (2009) 2234–2245
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Cyclometallated complexes derived from pyrimidin- and pyridazinehydrazones:
Structural evidence of intermolecular ‘‘chelate metal ring”
p–
p
interactions
a
a
a
Jesús J. Fernández a, , Alberto Fernández , Margarita López-Torres , Digna Vázquez-García ,
*
Antonio Rodríguez a, Alexis Varela a, José M. Vila b,
*
a Departamento de Química Fundamental, Universidad de La Coruña, E-15071 La Coruña, Spain
b Departamento de Química Inorgánica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
a r t i c l e i n f o
a b s t r a c t
Reaction of 3,4-(Me)2C6H3C(Me)@NN(H)[30-(CF3)C4H2N2] (a) and 3,4-(Me)2C6H3C(Me)@NN(H)
(40-ClC4H2N2) (b) with palladium(II) acetate gave the mononuclear cyclometallated complexes [Pd{3,4-
Article history:
Received 13 January 2009
Received in revised form 27 February 2009
Accepted 2 March 2009
(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}(OAc)]
(1a)
and
[Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-
ClC4H2N2)}(OAc)] (1b) with the ligand as terdentate [C,N,N]. Treatment of a and b with Li2[PdCl4] and
sodium acetate in methanol at room temperature yielded the mononuclear cyclometallated complexes
[Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}(Cl)] (2a) and [Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-
ClC4H2N2)}(Cl)] (2b), respectively. Recrystallization of 2b from a dimethylsulfoxide solution gave
[Pd{3,4-(Me)2C6H2C(Me)@NN(40-ClC4H2N2)}][(CH3)2S@O] after deprotonation of the hydrazine nitrogen.
The reaction of 2a and 2b with silver trifluoromethanesulfonate and triphenylphosphine, yielded
[Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}-(PPh3)][CF3SO3] (3a) and [Pd{3,4-(Me)2C6H2C(Me)@
NN(H)(40-ClC4H2N2)}(PPh3)]-[CF3SO3] (3b) with the phosphine ligand occupying the vacant coordination
position after chlorine abstraction; these were deprotonated at the hydrazine nitrogen after treatment
with sodium acetate. Reaction of 2a with Ph2P(CH2)2AsPh2 (arphos), after AgCl removal gave mononu-
clear complex Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}(Ph2P(CH2)2AsPh2)][ClO4] (5a) with a
non-coordinated As atom. Reaction of 2a and 2b with a Ag(I) salt and the tertiary diphosphine
Ph2P(CH2)4PPh2 (dppb) in 2:1 molar ratio gave the dinuclear complexes [{Pd{3,4-(Me)2C6H2C(Me)@
Available online 9 March 2009
Keywords:
Palladium
Cyclometallation
Phosphines
p–p Interactions
Metalloaromaticity
NN(H)[30-(CF3)C4H2N2]}}2(
l
-Ph2P(CH2)4PPh2)][CF3SO3]2 (6a) and [{Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-
ClC4H2N2)}}2( -Ph2P(CH2)4PPh2)][ClO4]2 (6b) with the diphosphine as a bridging ligand. Similarly, treat-
l
ment of 1b with silver triflate followed by reaction with the tertiary triphosphine (Ph2PCH2CH2)2PPh
(triphos), in a 3:1 molar ratio, gave the new trinuclear complex [{Pd[3,4-(Me)2C6H2C(Me)@NN(H)(40-
ClC4H2N2)]}3{
1:1 molar ratio gave
l3-(Ph2PCH2CH2)2PPh}][CF3SO3]3 (8b). However, reaction of 2a and 2b with (triphos), in
the
mononuclear complexes
[Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-
(CF3)C4H2N2]}{(Ph2PCH2CH2)2PPh-P,P,P}][ClO4] (7a) and [Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-ClC4H2N2)}-
{(Ph2PCH2CH2)2PPh-P,P,P}][ClO4] (7b) with a is five-coordinated palladium. The crystal structures of
2b, 3a, 3b, 7a and 7a have been determined by X-ray crystallography and they show
p–p interactions
between the metallacycle and the heterocyclic pyrimidine or pyridazine rings, which controls the crystal
packing.
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
ples are five-membered palladacycles containing nitrogen–Pd
and C(phenyl)–Pd bonds [1–9]. They exhibit a good number of
In the precedent decades the chemistry of cyclometallated tran-
sition metal complexes has attracted much attention. These com-
pounds are usually classified according to the metal, to the donor
atom, or to chelate ring size; by far the most well-studied exam-
applications which range from the synthesis of new organic and
organometallic compounds, to mesogenic species and catalytic
materials [10–22] as well as promoting unusual coordination envi-
ronments [23].
In the past, we have been interested in palladium(II) and plat-
inum(II) cyclometallated complexes derived from terdentate li-
gands; for example, Schiff bases readily react with palladium(II)
salts to give mononuclear cyclometallated complexes with the li-
gand as terdentate [C,N,N0] [24–27]. Treatment of the latter with
neutral ligands such as tertiary mono- or diphosphines produces
* Corresponding authors. Fax: +34 981 167065 (J.J. Fernández), +34 981 595012
(J.M. Vila).
E-mail addresses: quiluafl@udc.es (J.J. Fernández), josemanuel.vila@usc.es
(J.M. Vila).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.03.003

J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
2235
´
cleavage of the metal–N bond prior to ring-opening of the five-
membered metallacycle; however, removal of the chlorine ligand
by reaction with a silver (I) salt yields a vacant coordination site
that may be occupied by the phosphine ligand, precluding
metalꢀnitrogen bond cleavage. Nevertheless, in some cases the
strength of the Pd–N bond prevents ring-opening, even when
an excess of mono- or diphosphine is used [28]. Pd–N bond cleav-
age may also be achieved by reaction with the tertiary triphos-
phine (Ph2PCH2CH2)2PPh (triphos) upon chelation. However, in
spite that the tendency of triphos to act as a chelating ligand is
patent [23,26,29], in some cases it may behave as a bridging li-
gand coordinating three different cyclometallated moieties
[28,30].
The synthesis and reactivity of the structurally related cyclo-
metallated complexes derived from acetyl- or phenylpyridine
phenylhydrazones has been fully studied [31–35] with the corre-
sponding hydrazone having an acidic NH hydrogen which is part
of the cyclometallated ring [32]. A similar acidic behavior has been
observed in some of the complexes described herein, where the NH
group is part of the PdNN(H)CN chelate ring.
Furthermore, the classical concept of ‘‘metalloaromaticity” [36]
as an indication of aromatic properties in a chelate metallacycle is
useful in describing the compound’s planar conjugated ring struc-
ture, its electron delocalization, ring currents, and tendency toward
equivalent, partial bond orders, as well as the impact of these prop-
erties in NMR chemical shifts, among others. Since metalloaroma-
ticity affects bond orders and geometrical parameters within the
cycles, aromaticity indices based on experimental bond lengths,
typically used in the analysis of five or six-membered organic het-
erocycles, have also been considered in the analysis of the ‘‘aro-
matic” character of five-membered cyclopalladated rings [37].
This ‘‘aromatic” character has also been claimed to explain the dif-
ferent reactivity of the complexes towards, for example, ligand-ex-
change reactions [38] or the superior stability of ‘‘exo”
cyclometallated rings [39,40].
2. Results and discussion
2.1. Preparation of the complexes
The compounds and reactions are shown in Schemes 1–3. The
compounds described in this paper were characterized by elemen-
tal analysis (C, H, N), by IR and 1H and 31P–{1H} NMR spectroscopy,
FAB and ESI mass spectrometry and X-ray single crystal diffraction
(data in Section 6).
Reaction of 3,4-Me2C6H3C(Me)@NN(H)[30-(CF3)C4H2N2] (a) and
3,4-Me2C6H3C(Me)@NN(H)(40-ClC4H2N2) (b) with palladium(II)
acetate in toluene at 60 °C, or in dichloromethane at room temper-
ature, gave the mononuclear complexes [Pd{3,4-Me2C6H2C(Me)@
NN(H)[30-(CF3)C4H2N2]}(OAc)] (1a) and [Pd{3,4-Me2C6H2C(Me)@
NN(H)(40-ClC4H2N2)}(OAc)] (1b) which were fully characterized
(Schemes 1 and 2). The IR spectra showed the
m(C@N) stretch
(1547, 1a and 1588, 1b cmꢀ1) shifted to lower wavenumbers due
to N-coordination of the ligand [43,44]. The resonance assigned
to the hydrazine HN proton appeared at d 11.97 (1a) and d 10.3
(1b) ppm in the 1H NMR spectra, downfield shifted as compared
to the ligands, as a consequence of the formation of the coordina-
tion ring. In the NMR spectrum of 1a the H11 resonance was
shifted to lower frequency due to the coordination of the pyrimi-
dine ring through the adjacent nitrogen atom; absence of the H6
proton resonance was in accordance with metallation. The strong
bands assigned to the symmetric and asymmetric m(COO) vibra-
tions in the IR spectrum, were in agreement with terminal acetate
ligands [45] (see Section 6). These findings and the presence of a
cluster of peaks in the mass spectra centered at 413 (1a) and 379
(1b) amu assigned to the [MꢀAcO] fragment and at 438
(1b) amu, assigned to the molecular ion, supported a mononuclear
formulation for the complexes.
Treatment of a and b with Li2[PdCl4] and sodium acetate in
methanol at room temperature yielded [Pd{3,4-Me2C6H2C(Me)@
NN(H)[30-(CF3)C4H2N2]}(Cl)] (2a) and [Pd{3,4-Me2C6H2C(Me)@
NN(H)(40-ClC4H2N2)}(Cl)] (2b). The IR spectra showed the
New structural evidence of metalloaromaticity is given by the
existence of
p–p stacking interactions, generated by metal che-
m(C@N) stretch shifted to lower wavenumbers due to the coordi-
lated rings. An interesting example has been reported recently in
the case of a copper (II) 1,10-phenanthroline derivative in which
the metallacycle of the N,N type is involved in an intramolecular
nation of the C@N nitrogen. The complexes were insoluble in
most organic solvents and only slightly soluble in d6-DMSO.
The 1H NMR spectra showed the absence of H6 consequent on
formation of the Pd–C6 bond. Although in the IR spectra (KBr
effective ‘‘metal chelate ring/aromatic ring”
tion [41]. Examples of metallacycles of the C,N type, that is, cyclo-
metallated rings, that contribute to stacking interactions
p–p stacking interac-
discs) the presence of bands assigned to the m(N–H) stretch sug-
p–p
gested that the NH groups were present in the complexes, sur-
prisingly, the 1H NMR spectra of 2a and 2b in DMSO-d6
solution did not show the NH resonance. Then, single crystals
of 2b were obtained by slowly evaporating a DMSO solution of
the complex and the resolution of the molecular structure
showed that the anionic chlorine ligand had been replaced by
a solvent molecule and, to preserve the neutrality of the com-
plex, the hydrazone group was deprotonated, putting forward
that this was the species present in solution. We found this pro-
cess was not reversible.
within the molecular arrangement, are given by the cyclopalladat-
ed phenylhydrazone or azobenzene complexes [35,42].
Herein we report the synthesis of cyclometallated complexes
derived from pyrimidin- and pyridazinhydrazones with the ligand
in a terdentate C,N,N0 fashion. In addition, we also report the reac-
tion of these complexes with tertiary mono- di- and triphosphines,
as well as with the phosphino arsine Ph2P(CH2)2AsPh2 (arphos).
Treatment with the tertiary diphosphine Ph2P(CH2)4PPh2, dppb,
or with the triphosphine (Ph2PCH2CH2)2PPh, triphos yielded com-
plexes in which the phosphine is a bridging ligand, this being
one of the few examples of a trinuclear cyclometallated complex
3. Crystal structure of [Pd{3,4-(Me)2C6H2C(Me)NN(40-
ClC4H2N2)}{(CH3)2SO}]
with triphos as a
l3-bridging phosphine, however the reaction
with arphos yielded a mononuclear complex with an uncoordi-
nated arsenic atom.
Suitable crystals were grown by slowly evaporating a dimethyl-
sulfoxide solution of the complex. The molecular structure is illus-
trated 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 asymmetric unit contains one molecule of the complex ly-
ing on a crystallographic mirror plane, except for the DMSO
methyl. The structure consists of discrete molecules 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(1)
We also comment on the crystal structures of several cyclomet-
allated complexes with an aromatic system constituted by the fu-
sion of heterocyclic and phenyl rings, plus two five-membered
metallacycles, in which the presence of
important role in controlling the crystal packing. Examples of
stacking previously reported involved metal chelate-phenyl ring
p–p interactions plays an
p–
p
interactions [35,41,42], however in the present paper we describe
metallacycle–pyrimidine or –pyrazine ring interactions, and possi-
ble interactions between the coordination rings.

2236
J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
CF3
N
2+
+
N
NH
N
AsPh2
Ph2
P
Ph2
P
-
2CF3SO3
Pd
Pd
P
N
HN
Pd
-
ClO4
Ph2
N
N
N
N
HN
N
6a
CF3
CF3
5a
vi
Mea
4
v
Meb
+
3
5
6
2
PPh3
PPh3
1
Cl
iii
iv
ii
-
Pd
Pd
N
Pd
CF3SO3
11
10
N
HN
N
N
N
N
N
N
N
N
N
N
7
HN
N
HN
CF3
a
4a
2a
CF3
CF3
CF3
3a
i
vii
DMSO
+
OAc
Ph2
P
PPh
DMSO
Pd
Pd
-
Pd
ClO4
N
HN
1a
N
N
N
N
P
N
N
Ph2
N
NH
F3C
Cl
N
CF3
N
CF3
2a in DMSO solution
7a
Scheme 1. (i) Pd(AcO)2, (toluene or dichloromethane); (ii) Li2PdCl4, (methanol, NaAcO); (iii) 1: AgCF3SO3; 2: PPh3 (acetone, 1:1molar ratio); (iv) NaAcO (methanol); (v) 1:
AgCF3SO3; 2: arphos (acetone, 1:1 molar ratio); (vi) 1: AgCF3SO3; 2: dppb (acetone, 2:1 molar ratio); (vii) triphos (acetone, 1:1molar ratio); 2: NaClO4.
Mea
+
Meb
4
3
5
6
2
PPh3
1
Cl
N
-
iii
ii
Pd
CF3SO3
Pd
N
HN
N
N
N
N
N
N
N
Cl
HN
3b
iv
Cl
HN
Cl
10
11
b
2b
i
DMSO
DMSO
OAc
Pd
Pd
N
N N
N
N N
PPh3
HN
Cl
N
Cl
Pd
1b
N
N N
2b in DMSO solution
N
Cl
4b
Scheme 2. (i) Pd(AcO)2, (toluene or dichloromethane); (ii) Li2PdCl4, (methanol, NaAcO); (iii) 1: AgCF3SO3; 2: PPh3 (acetone, 1:1molar ratio); (iv) NaAcO (methanol); (v) 1:
AgCF3SO3; 2: arphos (acetone, 1:1 molar ratio); (vi) 1: AgCF3SO3; 2: dppb (acetone, 2:1 molar ratio); (vii) triphos (acetone, 1:1molar ratio); 2: NaClO4.
and the pyridazine N(3) nitrogen atoms, and to the S(1) sulfur
atom of the coordinated DMSO. The angles between adjacent
atoms in the coordination sphere of palladium are close to the ex-
pected value of 90° with the most noticeable distortions corre-
sponding to the N(1)–Pd(1)–N(3) angle of 77.62(9)° and the
C(1)–Pd(1)–S(1) angle of 100.77(8)°. The sum of the angles about
palladium is approximately 360°.
[28,32,33,35,46–48]. The Pd(1)–N(3) bond length is longer than
Pd(1)–N(1) distance, showing the stronger trans influence of the
C(1) carbon atom as compared to the S(1) sulfur.
The geometry around the palladium atom [Pd(1), C(1), N(1),
N(3), S(1)] is planar (r.m.s. = 0.000, plane1). The metallated ring
[Pd(1), C(1), C(6), C(7), N(1), plane 2] and the coordination ring
[Pd(1), N(1), N(2), C(8), N(3), plane 3] are also planar
(r.m.s. = 0.000). Planes 1, 2, 3, the metallated phenyl ring and the
pyridazine ring are coplanar.
The Pd(1)–N(1) 1.983(2) Å and Pd(1)–N(3) 2.092(2) bond dis-
tances are similar to others reported for related compounds

J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
2237
Cl
2+
N
N
NH
N
Ph2
P
-
2ClO4
Pd
Pd
P
N
Ph2
HN
N
N
Cl
6b
i
3+
Cl
Ph
P
ii
N
N
Pd
Pd
Pd
P
Ph2
Ph
2
P
Cl
3F3CS
HN
NH
N
N N
N
N
N
N
N
HN
Cl
N
Pd
N
2b
iii
Cl
Cl
N
H
8b
+
Ph2
P
Pd
-
P
Ph
ClO4
N
P
Ph2
N
NH
N
Cl
7b
Scheme 3. (i) 1: AgCF3SO3; 2: dppb (acetone, 2:1 molar ratio); (ii) 1: AgCF3SO3; 2: triphos (acetone, 3:1 molar ratio); (iii) triphos (acetone, 1:1molar ratio); 2: NaClO4.
N(2), C(8), N(3), plane 3] rings (distance between ring centers,
O1
3.69 Å) were observed (Fig. 2). In fact, within the packing dim-
mer, the cyclometallated and the pyridazine rings, and the two
coordination rings are not stacked in a roughly ‘‘face-to-face”
manner showing a so-called ‘‘slipped stacking” [49]. Similar
interactions have been described previously [35,41,42] and
strongly suggest an active electronic delocalization within the
metal chelate rings, such that it could exhibit some degree of
C3
C2
C4
C5
S1
C1
Pd1
‘‘metalloaromaticity”. However, in the present case the
bonded rings were the metallacycle ring and the heterocyclic
pyridazine ring. The two coordination rings were also parallel
p p
ꢀ
C6
C7
N4
N3
Cl1
and within the distance expected for a
p p ‘‘slipped stacking”;
ꢀ
N1
N2
C8
C11
C10
whether this disposition is consequence of an attractive interac-
tion between the ‘‘metalloaromatic” rings or is required by
metallacycle–pyridazine interaction cannot be established at
present.
C9
Fig. 1. Molecular structure of [Pd{3,4-(Me)2C6H2C(Me)@NN(40-ClC4H2N2)}
{(CH3)2S@O}], with labelling scheme. Hydrogen atoms have been omitted for
clarity.
Reaction of 2a and 2b with triphenylphosphine, after chlorine
removal with silver trifluoromethanesulfonate, gave [Pd{3,4-
(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}-(PPh3)][CF3SO3]
(3a)
and
[Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-ClC4H2N2)}-
The spatial arrangement of the molecules shows they are set in
rows with alignment of the palladium atoms parallel to the a and c
crystallographic axes and defining a plane that contains the molec-
ular planes. These planes are parallel with an interplanar distance
of 3.61 Å (Fig. 2).
The presence of an aromatic system constituted by the fusion
of the heterocyclic and phenyl rings, plus two five-membered
metallacycle and coordination rings, indicated that, in this type
(PPh3)][CF3SO3] (3b) with the phosphine ligand occupying the va-
cant coordination position after AgCl removal. The 1H NMR spectra
of the complexes showed the hydrazine NH proton signal at d 11.8
(3a) and 11.52 (3b) (4J(HNP) = 5.4 Hz). The upfield shift of the H5 [d
5.7 ppm; 4J(H5P) ca. 5 Hz] and H11 (in 3a) resonances (as com-
pared to the parent complexes) was due to shielding by the phos-
phine phenyl rings [50,51], confirming coordination of the ligand.
The 31P–{1H} NMR spectra showed a singlet resonance ca. d 39 in
accordance with a trans phosphorus-to-nitrogen geometry [52–
55]. The conductivity measurements carried out in dry acetonitrile
were in agreement with 1:1 electrolytes. The ESI mass spectra
showed the peaks corresponding to the loss of the triflate
counterions.
of structures,
trolling the crystal packing. Consequently
p
–
p
interactions can play an important role in con-
interactions be-
p–p
tween the pyridazine and the metallacycle [Pd(1), C(1), C(6),
C(7), N(1), plane 2] rings (distance between ring centers,
3.69 Å) as well as between the two coordination [Pd(1), N(1),

2238
J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
Table 1
Crystallographic data for complexes 2b, 3a, 3b, 7a and 7b.
2b
3a
3b
7a
7b
Empirical formula
Formula mass
T (K)
C16H19Cl N4OPdS
457.26
293(2)
C35H30Cl3F6N4O3PPdS
941.41
293(2)
C33H29N4O3F3ClPPdS
791.48
293(2)
C49.25H47.25N4O4F3Cl1.75P3Pd
1077.51
293(2)
C48H47N4O4Cl2P3Pd
1014.11
293(2)
k (Å)
0.71073
Monoclinic
P21/m
10.333(1)
7.225(1)
12.123(1)
99.218(1)
893.4(1)
2
0.71073
Monoclinic
P21/n
11.141(1)
14.091(1)
25.970(3)
99.307(2)
4023.2(8)
4
0.71073
Monoclinic
C2/c
20.923(2)
14.766(1)
23.208(2)
108.639(2)
6793.8(10)
8
0.71073
Monoclinic
P21/n
10.938(1)
22.288(1)
20.8394(1)
91.994(1)
5077.2(4)
4
0.71073
Monoclinic
P21/c
18.918(1)
11.828(1)
22.616(1)
111.086 (1)
4721.8(5)
4
Crystal system
Space group
a (Å)
b (Å)
c (Å)
b (°)
V (Å3)
Z
l
(mmꢀ1
)
1.316
0.819
0.790
0.609
0.654
Maximum, minimum transmissions
0.87, 0.57
1.700
2.00–28.26
12263
0.90, 0.76
1.559
1.59–28.44
28398
0.90, 0.86
1.548
1.72–28.30
45614
0.86, 0.78
1.410
1.34–28.30
6944
0.95, 0.90
1.423
1.86–28.19
59671
qcalc (g cmꢀ3
h Range (°)
)
Reflections collected
Independent reflections
2380 (Rint = 0.034)
0.0227
0.0540
9958 (Rint = 0.055)
0.0485
0.1358
8426 (Rint = 0.133)
0.0593
0.1475
12596 (Rint = 0.038)
0.0456
0.1547
11585 (Rint = 0.056)
0.0430
0.1232
a
R1
b
wR2
P
P
a
R1
=
||Fo| ꢀ |Fc||/ |Fo|, [F > 4
r
(F)].
P
P
2
2
wR2 ¼ ½ ½wðF2o ꢀ F2c Þ
wðF2oÞ ꢁ1=2, all data.
b
Table 2
Selected bond lengths (Å) and angles (°) for complexes 2b, 3a, 3b, 7a and 7b.
2b 3a
3b
7a
7b
Pd(1)–C(1)
Pd(1)–P(1)
Pd(1)–N(1)
Pd(1)–N(3)
2.018(3)
2.020(4)
2.233(1)
2.032(3)
2.188(3)
2.003(5)
2.268(1)
2.009(4)
2.107(4)
2.067(3)
2.305(1)
2.410(3)
2.059(3)
2.320(1)
2.448(3)
1.983(2)
2.092(2)
2.260(1)
Pd(1)–S(1)
Pd(1)–P(2)
Pd(1)–P(3)
C(1)–C(6)
C(6)–C(7)
N(1)–C(7)
N(1)–N(2)
N(2)–C(8)
C(8)–N(3)
C(1)–Pd(1)–N(1)
N(1)–Pd(1)–P(1)
C(1)–Pd(1)–P(1)
N(1)–Pd(1)–N(3)
C(1)–Pd(1)–N(3)
P(1)–Pd(1)–N(3)
N(1)–Pd(1)–S(1)
C(1)–Pd(1)–S(1)
S(1)–Pd(1)–N(3)
P(2)–Pd(1)–P(1)
P(2)–Pd(1)–N(1)
C(1)–Pd(1)–P(2)
N(1)–Pd(1)–P(3)
P(1)–Pd(1)–P(3)
P(2)–Pd(1)–P(3)
C(1)–Pd(1)–P(3)
2.313(1)
2.329(1)
1.399(5)
1.465(5)
1.283(4)
1.383(4)
1.363(5)
1.332(5)
74.60(12)
115.34(8)
92.30(10)
2.323(1)
2.297(1)
1.405(4)
1.473(4)
1.295(4)
1.395(3)
1.364(4)
1.319(4)
74.59(10)
97.92(7)
92.68(8)
1.416(4)
1.467(4)
1.304(3)
1.378(3)
1.325(4)
1.378(3)
1.422(5)
1.449(6)
1.291(5)
1.375(5)
1.364(5)
1.368(5)
80.86(15)
171.27(9)
94.77(12)
76.43(12)
157.10(14)
108.12(8)
1.426(6)
1.475(7)
1.299(6)
1.380(6)
1.377(7)
1.339(6)
81.40(10)
81.15(19)
176.59(13)
101.82(14)
77.79(17)
158.64(18)
99.34(12)
77.62(9)
159.01(10)
177.83(7)
100.77(8)
100.21(6)
86.72(3)
110.30(7)
174.94(10)
107.34(8)
36.84(3)
85.53(3)
114.74(6)
170.64(9)
116.66(7)
145.10(3)
84.24(3)
84.42(3)
92.94(10)
92.09(8)
of the triphenylphosphine ligand P(1). The angles between adja-
cent atoms in the coordination sphere of palladium are close to
the expected value of 90° with the most noticeable distortions cor-
responding to the N(1)–Pd(1)–N(3) [76.4(1)° and 77.8(2)° for 3a
and 3b, respectively] and N(3)–Pd(1)–P(1) [108.1(8)° for 3a] and
C(1)–Pd(1)–P(1) [101.8(1)° for 3b] angles. The sum of the angles
about palladium is approximately 360°.
The Pd–C [2.020(4) and 2.003(5) Å, for 3a and 3b, respectively],
Pd–P [2.233(1) and 2.268(1) Å, for 3a and 3b, respectively], Pd–
N(1) [2.032(3) and 2.009(4) Å, for 3a and 3b, respectively] and
Pd–N(3) [2.188(3) and 2.107(4) Å, for 3a and 3b] bond distances
are within the expected values for these type of complexes
4. Crystal structures of 3a and 3b
Suitable crystals were grown by slowly evaporating chloroform/
n-hexane solutions of the complexes 3a and 3b. The molecular
structures are illustrated in Figs. 3 and 4. Crystal data are given
in Table 1 and selected bond distances and angles with estimated
standard deviations are shown in Table 2.
Both crystal structures comprise one cation, one CF3SO3ꢀ anion
and, in the case of 3a, a chloroform molecule per asymmetric unit.
The palladium atom is bonded in a slightly distorted square-planar
geometry to the C(1) carbon atom of the phenyl ring, the N(1) and
the heterocyclic N(3) nitrogen atoms, and to the phosphorus atom

J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
2239
N(1), N(2), C(8), N(3), plane 3] (distance between ring centers,
3.62 Å) as well as between the metallacylce [Pd(1), C(1), C(6),
C(7), N(1), plane 2] and the pyrimidine ring (distance between ring
centers, 3.69 Å) (Fig. 5).
As for the crystal structure of 3b the cations are arranged in
lines parallel to the crystallographic b axis and, with the exception
of the phosphine rings the molecular planes are parallel to each
other.
p–p Stacking interactions are present between the pyrida-
zine and the metallated phenyl rings (distance between ring cen-
ters, 3.66 Å) of two adjacent rows (Fig. 6).
Acetylpyridine phenylhydrazone derivatives, where the NH
nitrogen is part of the cyclometallated ring, behave as protic acids
[32]. The deprotonation experimented by 2a and 2b in DMSO led
us to think that a similar behavior could be observed for 3a and
3b. Consequently, treatment of the cyclometallated complexes 3a
and 3b with a base (sodium acetate) in methanol produced depro-
tonation of the hydrazine nitrogen to give the neutral complexes
[Pd{3,4-(Me)2C6H2C(Me)@NN[30-(CF3)C4H2N2]}(PPh3)] (4a) and
[Pd{3,4-(Me)2C6H2C(Me)@NN[30-(CF3)C4H2N2]}(PPh3)] (4b). Ab-
Fig. 2. Intermolecular
involved in each stacking interaction.
p,p-stacking interactions. Dashed lines link ring centers
sence of the m(N–H) stretch in the IR spectra and of the NH reso-
nance in the 1H NMR spectra evidenced deprotonation of the NH
group. In the 31P–{1H} NMR spectra the phosphorus resonance
was at d 39.40 (3a) and 38.54 (3b) ppm, slightly highfield shifted.
Conductivity measurements in acetonitrile were in accordance
with the molecular nature of 4a and 4b. Treatment of the latter
compounds with acetic acid gave the corresponding NH proton-
ated compounds as the acetate salts.
C3
C4
C2
P1
C1
C5
Treatment of 2a with Ph2P(CH2)2AsPh2 (arphos), after AgCl
removal with silver perchlorate, in 1:1 molar ratio gave the mono-
nuclear complex Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}
(Ph2P(CH2)2AsPh2)][ClO4] (5a). Along with the dP value, coupling of
the H5 proton resonance, d 5.63 ppm, to the 31P nucleus showed
coordination of the arsinophopshine through the phosphorus
atom. The H4 resonance, d 6.04, was upfield shifted due to shield-
ing by the phosphine phenyl rings. Conductivity measurements
carried out in dry acetonitrile were in agreement with 1:1 electro-
lytes, and the FAB mass spectrum showed the peaks centered at
855 assigned to [MꢀClO4].
C6
C7
Pd1
N3
N1
N2
C11
C10
C8
N4
C9
Reaction of 2a and 2b with a Ag(I) salt Ph2P(CH2)4PPh2 (dppb) in a
2:1 molar ratio gave the dinuclear cyclometallated complexes
[{Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}}2(
l
-Ph2P(CH2)4-
PPh2)][CF3SO3]2 (6a) and [{Pd{3,4-(Me)2C6H2C(Me)@ NN(H)(40-
ClC4H2N2)}}2( -Ph2P(CH2)4PPh2)][ClO4]2 (6b), as 1:2 electrolytes,
Fig. 3. Cation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}(PPh3)]-[CF3SO3]
(3a), with labelling scheme. Hydrogen atoms have been omitted for clarity.
l
which were fully characterized (see Section 6). The symmetric nature
of the complexes was established by the presence of only one singlet
signal in the 31P–{1H} spectra (d 26.82, 6a and 31.03, 6b ppm). The
mass-FAB spectra showed clusters of peaks centered at 1253 (6a)
and 1185 (6b) uma, assigned to loss of triflate (6a) or perchlorate
(6b) counteranions.
Treatment of 1b with silver triflate followed by reaction with
(Ph2PCH2CH2)2PPh (triphos), in a 3:1 molar ratio, gave the new tri-
nuclear complex [{Pd[3,4-Me2C6H2C(Me)@NN(H)(40-ClC4H2N2)]}3-
[28,32,47,56,57]. The Pd–N(3) bond length shows the greater trans
influence of the C(1) carbon as compared 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. = 0.0544 and 0.0369, for 3a and 3b,
respectively; plane 1) with a small tetrahedral distortion, probably
caused by the steric hindrance of the triphenylphosphine ligand.
The metallated [Pd(1), C(1), C(6), C(7), N(1), plane 2] and the coor-
dination [Pd(1), N(1), N(2), C(8), N(3), plane 3] rings are also planar
(r.m.s. = 0.0031 and 0.0196 for 3a and 3b, respectively; plane 2,
and 0.0347 and 0.0157 for 3a and 3b, respectively; plane 3) and
coplanar with the metallated phenyl and pyridine rings; conse-
quently the 3a and 3b cations are planar with the exception of
the phosphine phenyls.
Hydrogen bonding between the N(2)–H(2a) hydrogen and O(1)
oxygen atom of the triflate anion was found in complex 3a [N(2)–
H(2a), 0.78 Å; N(2)–H(2)ꢂ ꢂ ꢂO(1), 2.926(5) Å, 177°] and between the
N(2)–H(1) hydrogen and O(3) in 3b [N(2)–H(1), 0.87(6)Å;
O(3)ꢂ ꢂ ꢂH(1), 2.07(6)Å; N(2)–H(1)ꢂ ꢂ ꢂO(3), 2.94(2) Å, 178(5)°].
In the structure of 3a the cations are arranged as dimmers with
{l3-(Ph2PCH2CH2)2PPh-P,P,P}][CF3SO3]3 (8b), as a 1:3 electrolyte.
The 1H NMR spectrum showed two sets of signals with an integra-
tion ratio of 2:1, for the three cyclometallated moieties, with one
set assigned to the 2 equiv. cyclometallated groups coordinated
to the terminal phosphorus atoms, and the other to the metallacy-
cle bonded to the central phosphorus atom. The H5 resonances
were assigned as doublets at 5.19 [terminal; 4J(PH) = 4.8 Hz] and
4.53 ppm [central; 4J(PH5) = 4.5 Hz], highfield shifted by the influ-
ence of the phosphine phenyl rings; the NH proton resonances also
showed coupling to the 31P nuclei 11.35 and 11.14 [4J(PH) =
5.1 Hz] ppm. The 31P–{1H} NMR spectrum showed a doublet at d
27.5 and a triplet at d 24.7 assigned to the 2 equiv. terminal phos-
phorus nuclei and to the central phosphorus nucleus, respectively.
p–p
stacking interactions between the coordination rings [Pd(1),
The ESI mass spectrum showed
a
cluster of peaks

2240
J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
nuclei. The latter signal appeared at lower frequency in accordance
with the higher trans influence of the phosphine ligand [53]. The
resonance of the proton in the ortho position to the metallated car-
bon appeared as a doublet showing coupling to the central 31P
atom [J(PH5) ca. 9 Hz]; no coupling was observed to the terminal
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 phosphorus atoms [23,26,28,29]. The conduc-
tivity data in acetonitrile solution showed the compounds were 1:1
electrolytes. The FAB mass spectra showed a set of peaks centered
at 947 and 912 (for 7a and 7b, respectively) uma assigned to the
[MꢀClO4] fragments.
C3
C4
C2
C1
C5
P1
Pd1
C6
C7
N3
N1
N2
5. Crystal structures of 7a and 7b
N4
C11
Cl1
Suitable crystals were grown by slowly evaporating chloroform/
n-hexane solutions of 7a and 7b. The molecular structures are
illustrated in Figs. 7 and 8. Crystal data are given in Table 1 and se-
lected bond distances and angles with estimated standard devia-
tions are shown in Table 2.
C8
C10
C9
Fig. 4. Cation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-ClC4H2N2)}(PPh3)][CF3SO3]
(3b), with labelling scheme. Hydrogen atoms have been omitted for clarity.
ꢀ
The crystal structure comprises one cation, one ClO4 anion
and, in the crystal of 7b, a disordered chloroform molecule per
asymmetric unit. The palladium atom is bonded to the C(1) carbon
atom of the metallated ring and to the three phosphorus atoms
P(1), P(2) and P(3), of the triphos ligand. A fifth interaction to the
N(1) nitrogen completes the coordination sphere about the palla-
dium atom.
The Pd(1)–N(1) distance of 2.410(3) and 2.448(3) Å for 7a and
7b, respectively, is somewhat longer than the values of
2.338(3) Å, reported recently by us in a similar complex with a tri-
phos ligand [29], and of 2.23(2) Å found in an authentic penta-
coordinated palladium(II) complex [58]. However, the Pd–N bond
length is shorter than the weak interactions in the range
2.576(4)–2.805(5) Å found in other five-coordinated complexes of
palladium [59–64]. The
s parameter, an index of trigonality [65]
as a general descriptor of five-co-ordinate molecules, is 0.63 and
0.42, for complexes 7a and 7b, respectively, nearly half-way be-
tween the trigonal-bipyramidal (s = 1) and the square pyramidal
(s
= 0) geometry; therefore, coordination around the palladium
atom may be viewed as a distorted trigonal-bipyramid, with the
Pd(1), N(1), P(1) and P(3) atoms in the equatorial plane and
the metallated carbon atom and the central phosphorus atom at
the apical position, or alternatively it may be regarded as square
pyramidal with the Pd(1), C(1), P(1), P(2) and P(3) atoms in the ba-
sal plane and the nitrogen at the apical position (see Tables 3–5).
The Pd(1)–C(1) bond distance [2.067(3) and 2.059(3) Å, for 7a
and 7b, respectively], and the Pd(1)–P(1), Pd(1)–P(2) and Pd(1)–
P(3) bond lengths [2.305(1), 2.313(1) and 2.329(1) Å for 7a and
2.320(1), 2.323(1) and 2.297(1) Å for 7b] were in agreement with
those found in related Pd(II) complexes [23,29,66].
Fig. 5. Intermolecular
link ring centers involved in each stacking interaction.
p,p-stacking interactions in the crystal of 3a. Dashed lines
Intramolecular
cyclic ring and the phenyl ring of the central phosphorus atom.
Additionally intermolecular interactions were also observed
between the pyridazine rings of two centrosymmetrically related
cations of 7b (Fig. 9 and Table 6).
p–p stacking was observed between the hetero-
centered at 1972 uma assigned to the trinuclear fragment
[MꢀCF3SO3]+.
p–p
Reaction of 2a and 2b with the tertiary triphosphine
(Ph2PCH2CH2)2PPh (triphos), in
a
1:1 molar ratio, followed
Hydrogen bonding between the N(2)–H(31) hydrogen and O(1)
oxygen atom of the perchlorate anion was found in complex 7b
by sodium perchlorate, gave the mononuclear complexes [Pd{3,
4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}{(PPh2CH2CH2)2PPh-P,
[[N(2)–H(31),
H(31)ꢂ ꢂ ꢂO(1), 3.188(8) Å, 142(6)°].
0.74(6) Å;
O(1)ꢂ ꢂ ꢂH(31),
2.57(6) Å;
N(2)–
P,P}][ClO4]
(7a)
and
[Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-
ClC4H2N2)}-{(PPh2CH2CH2)2PPh-P,P,P}][ClO4] (7b), as air-stable
1:1 electrolytes, which were fully characterized (see Section 6).
The FAB mass spectra showed a set of peaks centered at 947 (7a)
and 912 (7b) uma assigned to the [M–ClO4] fragments.
6. Experimental
Safety Note. Caution: Perchlorate salts of metal complexes with
organic ligands are potentially explosive. Only small amounts of
these materials should be prepared and handled with great
caution.
A triplet resonance ca. d 87 ppm was assigned to the central 31P
nucleus, trans to the phenyl carbon atom, and a doublet ca. d
42 ppm was assigned to the 2 equiv. mutually trans phosphorus

J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
2241
Fig. 6. Intermolecular
p,p
-stacking interactions in the crystal of 3b. Dashed lines link ring cneters involved in each stacking interaction.
6.1. General procedures
C4
Solvents were purified by standard methods [67]. Chemicals
were reagent grade. The phosphines PPh3, Ph2P(CH2)4PPh2 (dppb),
(Ph2PCH2CH2)2PPh (triphos) were purchased from Aldrich and
Ph2P(CH2)2AsPh2 (arphos) was purchased from Alfa. Microanalyses
were carried out using a Carlo Erba Elemental Analyzer, Model
1108. IR spectra were recorded KBr discs on a Perkin–Elmer 1330
and on a Mattson spectrophotometers. NMR spectra were obtained
as CDCl3, CD3SOCD3 or CD3COCD3 solutions and referenced to
SiMe4 (1H, 13C–{1H}) or 85% H3PO4 31P–{1H}) and were recorded
on a Bruker AC-300F or a Bruker AC-500F spectrometer. All chem-
ical shifts were reported downfield from standards. The FAB mass
spectra were recorded using a Quatro mass spectrometer with a Cs
ion gun; 3-nitrobenzyl alcohol (3-NBA) or 3-mercapto-1,2-pro-
panediol (1-thioglycerol) were used as the matrix The ESI mass
spectra were recorded using a QSTAR Elite mass spectrometer,
using acetonitrile or dichloromethane/ethanol as solvents. Conduc-
tivity measurements were made on a CRISON GLP 32 conductivi-
meter using 10ꢀ3 mol dmꢀ3 solutions in dry acetonitrile or
dimethylformamide.
C5
C6
C3
C2
C7
C1
P1
N1
P3
Pd1
N2
C8
N4
N3
P2
C9
C11
C10
Fig. 7. Cation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2N2]}-{(PPh2CH2-
CH2)2PPh-P,P,P}][ClO4] (7a) with labelling scheme. Hydrogen and phenyl ring
atoms have been omitted for clarity.
6.2. Syntheses
6.2.1. Preparation of 3,4-(Me)2C6H3C(Me)@NN(H)[30-(CF3)C4H2N2] (a)
A
mixture of 2-hydrazino-4-(trifluoromethyl)pyrimidine
(0.476 g,
2.67 mmol),
3,4-dimethylacetophenone
(0.389 g,
4J(H2H6) = 1.7], 7.17 [d, 1H, H5, 3J(H5H6) = 7.9], 2.33, 2.31 [s, 3H;
br 6H, Me(C@N), Mea, Meb].
2.63 mmol) and 0.1 cm3 of acetic acid in 50 cm3 of ethanol was
stirred for 4 h at room temperature (r.t.). The yellow precipitate
formed was filtered off and dried in air. Yield 0.673 g, 83%. Anal.
Calc. for C15H15N4F3: C, 58.4; H, 4.2; N, 18.2. Found: C, 58.3;
6.2.3. Preparation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)-
C4H2N2]}(OAc)] (1a)
H,4.1; N, 18.4%. IR:
(300 MHz, CDCl3,
m
(C@N) 1585s,
ppm, Hz): d = 8.75 [d, 1H, H11,
m
(N–H) 3229s cmꢀ1. RMN 1H
Method 1: A pressure tube containing 3,4-(Me)2C6H3C(Me)@
NN(H)[30-(CF3)C4H2N2] (a) (138 mg, 0.450 mmol), palladium(II)
acetate (101 mg, 0.450 mmol) and 20 cm3 of dry toluene was
sealed under argon. The resulting mixture was heated at 60 °C
for 24 h. After cooling to r.t. the solution was filtered to give a
red solid. Yield 0.145 g, 68%. Anal. Calc. for C17H17N4O2PdF3: C,
d
J
3J(H10H11) = 4.9], 8.48 [s, 1H, NH], 7.63 [s, br 1H, H2,
4J(H2H6) = 1.8], 7.53 [dd, 1H, H6, 3J(H6H5) = 7.9, 4J(H2H6) = 1.8],
7.15 [d, 1H, H5, 3J(H5H6) = 7.9], 7.05 [d, 1H, H10,
3J(H10H11) = 4.9], 2.34 2.31, 2.29 [s 3H; s 3H; s3H, Me(C@N),
Mea, Meb].
43.2; H, 3.6; N, 11.8. Found: C, 43.3; H, 3.5; N, 11.7%. IR:
m(C@N)
Compound b was prepared similarly from 3-chlororo-6-hydra-
zinpyridazine as a white solid.
1547m, (N–H) 3268m. as(COO) 1434s, .
m
m
m
s(COO) 1300 m cmꢀ1
RMN 1H (300 MHz, CD3SOCD3, d ppm, J Hz): 11.97 [s, 1H, NH],
8.19 [d, 1H, H11, 3J(H10H11) = 5.7], 6.79 [s, 1H, H2], 6.55 [s, 1H,
H5], 6.32 [d, 1H, H10], 2.20, 2.11, 2.07 [s, 3H; br 6H, Me(C@N),
Mea, Meb], 1.89 [s, 3H, OAc]. FAB-MS: m/z = 413 [(L-H)Pd]+.
Specific molar conductivity, Km = 6.46 ohmꢀ1 cm2 molꢀ1 (in
acetonitrile).
6.2.2. 3,4-(Me)2C6H3C(Me)@NN(H)(40-ClC4H2N2) (b)
Yield 0.441 g, 61%. Anal. Calc. for C14H15N4Cl: C, 61.2; H, 5.5; N,
20.4. Found: C, 61.1; H, 5.7; N, 20.1%. IR: m(C@N) 1612sh, m(C@N)
3236sh cmꢀ1. RMN 1H (300 MHz, CDCl3, d ppm, J Hz): 8.49 [s, br
1H, NH], 7.67 y 7.38 [2d, 2H, H11, H12, 3J (H10H11) = 9.3], 7.54
[s, br 1H, H2, 4J(H2H6) = 1.7], 7.48 [dd, 1H, H6, 3J(H5H6) = 7.9,
Method 2: A pressure tube containing 3,4-(Me)2C6H3C(Me)@
NN(H)[30-(CF3)C4H2N2] (a) (152 mg, 0.490 mmol), palladium(II)

2242
J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
C4
C3
C2
C5
C6
C1
C7
P1
N1
N2
Pd1
P3
N3
N4
C8
C9
P2
C11
Cl1
C10
Fig. 8. Cation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-ClC4H2N2)} {(PPh2CH2-
CH2)2PPh-P,P,P}][ClO4] (7b) with labelling scheme. Hydrogen and phenyl ring
atoms have been omitted for clarity.
Fig. 9. Inter- and intramolecular
Dashed lines link ring centers involved in each stacking interaction. Terminal
phosphine phenyl rings have been omitted for clarity.
p,p-stacking interactions in the crystal of 7b.
Table 3
Intermolecular
p–p stacking parameters for 2b using the program PLATON [69].
Parameter
Plane 2/pyridazine
Plane 3/plane 3
d(c1–c2) (Å/
a
°)
3.69/0.0
3.61/11.6
3.61/11.6
3.69/0.0
3.61/11.7
3.61/10.7
d(\c1–P(2)) (Å/b °)
H10; d, 2H, H11, 3J(H10H11) = 9.6], 6.70 [s, 1H, H5], 2.19 [s, 3H,
Me(C@N)], 2.07 [s, 6H, Mea, Meb], 1.90 [s, 3H, OAc]. FAB-MS: m/
z = 382 uma [(L-H)Pd]+. ESI-MS: m/z = 440.0 [M]+. Specific molar
conductivity, Km = 5.96 ohmꢀ1 cm2 molꢀ1 (in dimethylfor-
mamide).
d(\c2–P(1)) (Å/
c °)
Table 4
Intermolecular
p–p stacking parameters for 3a using the program PLATON.
Parameter
Plane 2/pyrimidine
Plane 3/plane 3
6.2.5. Preparation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)-
C4H2N2]}(Cl)] (2a)
d(c1–c2) (Å/
a
°)
3.69/8.3
3.58/5.9
3.67/14.2
3.62/0.0
3.59/7.2
3.59/7.2
d(\c1–P(2)) (Å/b °)
A
stirred solution of palladium(II) chloride (133.2 mg,
0.7510 mmol) and lithium chloride (863.9 mg, 1.502 mmol) in
methanol was treated with 3,4-(Me)2C6-
(50 cm3)
d(\c2–P(1)) (Å/
c °)
H3C(Me)@NN(H)[30-(CF3)C4H2N2] (a) (237 mg, 0.770 mmol) and
sodium acetate (43 mg, 0.80 mmol). The mixture was stirred at
r.t. for 24 h. The yellow precipitate formed was filtered off, and
dried in air. Yield 0.310 g, 92%. Anal. Calc. for C15H14N4ClPdF3: C,
Table 5
Intermolecular
p–
p
stacking parameters for 3b using the program PLATON.
Cyclometallated phenyl/pyridazine
Parameter
40.1; H, 12.5; N, 3.2. Found: C, 40.4; H, 12.3; N, 3.1%. IR:
m(C@N)
d(c1–c2) (Å/
d(\c1–P(2)) (Å/b °)
d(\c2–P(1)) (Å/
°)
a
°)
3.66/4.1
3.56/16.8
3.51/13.4
1570s,
m
(N–H) 3281w cmꢀ1. RMN 1H (300 MHz, CD3SOCD3, d
ppm, J Hz): 8.44 [d, 1H, H11, 3J(H10H11) = 5.4], 7.30 [d, 1H, H10],
7.00 [s, 1H, H2], 6.82 [s, 1H, H5], 2.31 [s, 3H, Me(C@N)], 2.12 [s,
6H, Mea, Meb]. FAB-MS: m/z = 413 [(L-H)Pd]+. Specific molar con-
ductivity, Km = 17.09 ohmꢀ1 cm2 molꢀ1 (in dimethylformamide).
Complex 2b was synthesized following a similar procedure as a
yellow solid.
c
acetate (112 mg, 0.490 mmol) and 20 cm3 of dry dichloromethane
was sealed under argon. The resulting mixture was stirred for 24 h
at r.t. and the solvent removed under vacuum to give a red solid.
Yield 0.188 g, 81%.
Complex 1b was prepared similarly as a yellow solid.
6.2.6. [Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-ClC4H2N2)}(Cl)] (2b)
Yield 0.296 g, 95%. Anal. Calc. for C14H14N4Cl2Pd: C, 40.5; H, 3.4;
6.2.4. [Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-ClC4H2N2)}(OAc)] (1b)
N, 13.5. Found: C, 40.4; H, 3.3; N, 13.2%. IR: m(C@N) 1540 m, m(N–H)
Yield: method 1, 0.092 g, 43%; method 2, 0.099 g, 46%. IR:
m
3241sh cmꢀ1. RMN 1H (300 MHz, CD3SOCD3, d ppm, J Hz): 7.60 y
7.25 [d, 2H, H10; d, 2H, H11, 3J(H10H11) = 9.6], 7.07 [s, 1H, H2],
6.78 [s, 1H, H5], 2.27 [s, 3H, Me(C@N)], 2.11 [s, 6H, Mea, Meb].
FAB-MS: m/z = 382 [(L-H)Pd]+. Specific molar conductivity,
Km = 17.21 ohmꢀ1 cm2 molꢀ1 (in dimethylformamide).
(C@N) 1588 m,
m(N–H) 3111sh, mas(COO) 1497 m, ms(COO) 1421s
cmꢀ1. Anal. Calc. for C16H17N4O2PdCl: C, 43.7; H, 3.9; N, 12.8.
Found: C, 43.5; H, 3.6; N, 12.7%. RMN 1H (300 MHz, CD3SOCD3, d
ppm, J Hz): 10.3 [br, 1H, NH], 7.14 [s, 1H, H2], 6.90 y 6.77 [d, 2H,

J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
2243
Table 6
Intermolecular
p–p stacking parameters for 7a and 7b using the program PLATON.
Parameter
7a
7b
7b
Pyrimidine ring/phosphine phenyl
Pyridazine ring/phosphine phenyl
Pyrazine ring/pyrazine ring
d(c1–c2) (Å/
a)
3.52/12.7
3.37/3.8
3.51/16.4
3.56/14.7
3.21/12.5
3.48/25.6
3.76/0.0
3.36/26.7
3.36/26.7
d(\c1–P(2)) (Å)
d(\c2–P(1)) (Å)
6.2.7. Preparation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2-
N2]}(PPh3)]-[CF3SO3] (3a)
1.57 [s, 3H, Mea]. RMN 31P–{1H} (121.49 MHz, CDCl3, d ppm, J
Hz): 38.54 s. ESI-MS: m/z = 641.1 [M+H]+. Specific molar conduc-
tivity, Km = 1.36 ohmꢀ1 cm2 molꢀ1 (in acetonitrile).
Silver trifluoromethanesulfonate (46 mg, 0.18 mmol) was
added to a suspension of 2a (35 mg, 0.079 mmol) in acetone
(15 cm3). The resulting mixture was stirred for 4 h and filtered
through celite to remove the AgCl precipitate formed. PPh3
(18.6 mg, 0.071 mmol) was added to the filtrate and the resulting
orange solution was stirred for another 2 h. The solvent was re-
moved to give a red solid which was recrystallized from chloro-
6.2.11. Preparation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2-
N2]}(PPh2(CH2)2As-Ph2)][ClO4] (5a)
Silver trifluoromethanesulfonate (21.6 mg, 0.0840 mmol) was
added to a solution of 2a (30.9 mg, 0.0688 mmol) in acetone
(15 cm3). The resulting mixture was stirred for 4 h and filtered
through cellite to remove the AgCl precipitate formed.
Ph2P(CH2)2AsPh2 (26.2 mg, 0.0592 mmol) was then added to the
filtrate and the solution stirred for another 2 h, after which an ex-
cess of sodium perchlorate was added. The mixture was stirred for
a further 1 h and a pink complex precipitated out by addition of
water, filtered off and dried in vacuo. Yield 56.0 mg, 99%. Anal. Calc.
for C41H38N4PdO4PF3ClAs: C, 51.5; H, 4.0; N, 5.8. Found: C, 51.6; H,
form/hexane.
C34H29N4PdO3PF6S: C, 49.6; H, 3.9; N, 8.3. Found: C, 49.7; H, 3.8;
N, 8.2%. IR: (C@N) 1534s, (N–H) 3215m, (CF3SO3) 1250s. RMN
Yield
35.1 mg,
60%.
Anal.
Calc.
for
m
m
m
1H (300 MHz, CDCl3, d ppm, J Hz): 11.8 [br, 1H, NH, (DMSO-d6)],
6.94 [s, 1H, H2], 6.53 [d, 1H, H11, 3J(H10H11) = 5.7], 6.19 [d, 1H,
H10], 5.69 [d, 1H, H5, 4J(PH5) = 5.1], 2.53 [s, 3H, Me(C@N)], 2.09
[s, 3H, Meb], 1.65 [s, 3H, Mea]. RMN 31P–{1H} (121.49 MHz, CDCl3,
d ppm, J Hz): 37.90 s. ESI-MS: m/z = 675.1 [MꢀCF3SO3]+. Specific
molar conductivity, Km = 181 ohmꢀ1 cm2 molꢀ1 (in acetonitrile).
Compound 3b was prepared similarly, but recrystallized from
dichloromethane/hexane, as a yellow solid.
4.1; N, 5.1%. IR:
m(C@N) 1548m, m(N–H) 3185m, m(ClO4) 1380s
cmꢀ1. RMN 1H (300 MHz, CDCl3, d ppm, J Hz): 6.59 [s, 1H, H2],
6.09, 6.04 [d, 1H, d, 1H, 3J(H10H11) = 5.8, H10, H11], 5.83 [d, 1H,
H5, 4J(PH5) = 4.5], 2.22 [s, 3H, Me(C@N)], 2.15 [s, 3H, Meb], 2.03
[s, 3H, Mea]. RMN 31P-{1H} (121.49 MHz, CDCl3, d ppm, J Hz):
21.63 [s]. FAB-MS: m/z = 855. [MꢀClO4]+. Specific molar conductiv-
ity, Km = 109.5 ohmꢀ1 cm2 molꢀ1 (in acetonitrile).
6.2.8. [Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-ClC4H2N2)}(PPh3)][CF3SO3]
(3b)
Yield 30.9 mg, 55%. Anal. Calc. for C33H29N4ClPdO3PF3S: C, 50.1;
6.2.12. Preparation of [{Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4-
H2N2]}}2(l-PPh2(CH2)4PPh2)][CF3SO3]2 (6a)
H, 3.7; N, 7.1. Found: C, 49.9; H, 3.8; N, 7.2%. IR:
m(C@N) 1562m,
m
(N–H) 3285m,
m
(CF3SO3) 1306s cmꢀ1. RMN 1H (300 MHz, CDCl3,
d ppm, J Hz): 11.52 [d, 1H, NH, 4J(PH) = 5.4], 7.18 [d, 1H, H10 or
H11, 3J(H10H11) = 9.6], 6.80 [s, 1H, H2], 5.76 [d, 1H, H5,
J(PH5) = 4.8], 2.50 [s, 3H, Me(C@N)], 2.18 [s, 3H, Meb], 2.07 [s,
3H, Mea]. RMN 31P-{1H} (121.49 MHz, CDCl3, d ppm, J Hz):
40.61s. FAB-MS: m/z = 643 [MꢀCF3SO3]+. Specific molar conductiv-
ity, Km = 109.6 ohmꢀ1 cm2 molꢀ1 (in acetonitrile).
Silver trifluoromethanesulfonate (42.3 mg, 0.164 mmol) was
added to a solution of 2a (50.7 mg, 0.112 mmol) in acetone
(15 cm3). The resulting mixture was stirred for 4 h, and filtered
through celite to remove the AgCl precipitate. Ph2P(CH2)4PPh2
(26.2 mg, 0.0592 mmol) was added to the filtrate and the resulting
solution stirred for another 2 h. The solvent removed to give a yel-
low solid which was recrystallized from dichloromethane/hexane,
filtered off, and dried in air. Yield 63.4 mg, 73%. Anal. Calc.
C60H56N8Pd2O6P2F12S2: C, 46.4; H, 3.6; N, 7.2. Found: C, 46.5; H,
6.2.9. Preparation of [Pd{3,4-(Me)2C6H2C(Me)@NN[30-(CF3)C4H2N2]}
(PPh3)] (4a)
A stirred solution of compound 3a (30 mg, 0.036 mmol) in
methanol, 50 cm3, was treated with sodium acetate (3.3 mg,
0.040 mmol). The mixture was stirred at room temperature for
15 h. The solvent removed to give a red solid which was recrystal-
lized from dichloromethane/hexane, filtered off, and dried in air.
Yield 8.3 mg, 34%. Anal. Calc. for C33H28N4PdPF3: C, 58.7; H, 4.2;
3.5; N, 7.1%. IR:
m(C@N) 1532m, m(N–H) 3308 m, m(CF3SO3) 1750s
cmꢀ1. RMN 1H (300 MHz, CDCl3, d ppm, J Hz): 11.5 [br, 1H, NH],
6.69 [s, 1H, H2], 6.50 [d, 1H, H10, 3J(H10H11) = 5.7], 6.35, [d, 1H,
H11], 5.86 [d, 1H, H5, 4J(PH5) = 5.4], 2.51 [s, 3H, Me(C@N)], 2.18
[s, 3H, Meb], 2.04 [s, 3H, Mea]. RMN 31P–{1H} (121.49 MHz, CDCl3,
d ppm, J Hz): 26.82 [s]. FAB-MS: m/z = 841 [(L-H)Pd(dppb)+H]+,
1253 uma [Mꢀ2CF3SO3]+. Specific molar conductivity, Km = 269
ohmꢀ1 cm2 molꢀ1 (in acetonitrile).
N, 8.3. Found: C, 58.6; H, 4.2; N, 8.2%. IR:
m .
(C@N) 1547s cmꢀ1
RMN 1H (300 MHz, CDCl3, d ppm, J Hz): 6.74 [s, 1H, H2]; 5.75 [d,
1H, H5, 4J(PH5) = 4.8]; 5.70 [d, 1H, H11, 3J(H10H11) = 5.7]; 2.53
[s, 3H, Me(C@N)], 2.05 [s, 3H, Meb]; 1.58 [s, 3H, Mea]. RMN 31P–
{1H} (121.49 MHz, CDCl3, d ppm, J Hz): 39.40 s. ESI-MS: m/
Compound 6b was obtained following a similar procedure as a
yellow solid, but using silver perchlorate instead of silver
trifluoromethanesulfonate.
z = 674.1
ohmꢀ1 cm2 molꢀ1 (in acetonitrile).
Compound 4b was obtained following a similar procedure as a
red solid.
[M]+.
Specific
molar
conductivity, Km = 8.41
6.2.13. [{Pd{3,4-(Me)2C6H2C(Me)@NN(H)(40-ClC4H2N2)}}2
(l-PPh2(CH2)4PPh2)][CLO4]2 (6b)
Yield 54.3 mg, 70%. Anal. Calc. for C56H56N8Pd2O8P2Cl4: C, 48.5;
H, 4.1; N, 8.1. Found: C, 48.6; H, 4.2; N, 8.2%. IR: m(C@N) 1601m, m
6.2.10. [Pd{3,4-(Me)2C6H2C(Me)@NN[30-(CF3)C4H2N2]}(PPh3)] (4b)
(N–H) 3263 m, m
(ClO4) 1100s cmꢀ1. RMN 1H (300 MHz, CD3SOCD3,
Yield 13.4 mg, 58%. Anal. Calc. for C32H28N4PdClP: C, 59.9; H,
d ppm, J Hz): 7.19 [d, 1H, H10 H11, 3J(H10H11) = 9.6], 6.91 [s, 1H,
H2], 5.57 [d, 1H, H5, 4J(PH5) = 4.2], 2.37 [s, 3H, Me(C@N)], 1.99
[s, 3H, Meb], 1.50 [s, 3H, Mea]. RMN 31P–{1H} (121.49 MHz,
4.4; N, 8.7. Found: C, 59.6; H, 4.2; N, 8.7%. IR: m .
(C@N) 1603 m cmꢀ1
RMN 1H (300 MHz, CDCl3, d ppm, J Hz): 6.62 [s, 1H, H2]; 5.63 [d,
1H, H5, 4J(PH5) = 3.6]; 2.31 [s, 3H, Me(C@N)], 2.09 [s, 3H, Meb],
CD3SOCD3,
d
ppm,
J
Hz): 31.03 s. MS-FAB: m/z = 758.9

2244
J.J. Fernández et al. / Journal of Organometallic Chemistry 694 (2009) 2234–2245
[{(L-H)Pd}2]H+, 1185 uma [Mꢀ2ClO4]+. Specific molar conductivity,
Km = 101.5 ohmꢀ1 cm2 molꢀ1 (in dimethylformamide).
Compound 8b was obtained as a yellow solid following a similar
procedure to the one used for 6a, but using a complex/phosphine
3:1 molar ratio.
ence Fourier map) and refined in riding mode. The Cl(1), Cl(2) and
Cl(3) chlorine atoms of the chloroform solvent molecule in the
crystal of 3a were disordered and, consequently, refined in two
complementary positions with occupancies of 60% and 40%. The
S(1), C(33), F(1) and oxygen, atoms of the trifluoromethanesulfo-
nate ion in complex 3b were found to be disordered over two posi-
tions (with occupancies of approximately 63% and 37%). Disorder
was also present in the CF3 group of 7a which F(1), F(2) and F(3)
fluorine atoms were refined in complementary positions (occupan-
cies of 70% and 30%). The refinement was carried out taking into
account both components. Refinement converged with allowance
for thermal anisotropy of all non-hydrogen atoms. The structure
solution and refinement were carried out using the program pack-
age SHELX-97 [68].
6.2.14. [{Pd[3,4-(Me)2C6H2C(Me)@NN(H)(40ClC4H2N2)]}3{
l3-(PPh2-
CH2CH2)2PPh}] [CF3SO3]3 (8b)
Yield 74.9 mg, 63%. Anal. Calc. for C79H75N12Pd3O9Cl3P3F9S3: C,
44.7; H, 3.6; N, 7.8. Found: C, 44.6; H, 3.5; N, 7.9%. IR: (C@N)
1601m, (N–H) 3311 m,
(CF3SO3) 1254s cmꢀ1 RMN 1H
m
m
m
.
(300 MHz, CDCl3, d ppm, J Hz): 11.35 [d, 2H, NH, 4J(PH) = 5.1],
11.14 [d, 1H, NH, 4J(PH) = 5.1], 5.19 [d, 2H, H5, 4J(PH5) = 4.8], 4.53
[d, 1H, H5, 4J(PH5) = 4.5], 2.40 [s, 6H, Me(C@N)], 2.32 [s, 3H,
Me(C@N)], 2.05 [s, 6H, Mea], 1.98 [s, 3H, Mea], 1.50 [s, 6H, Meb],
1.23 [s, 3H, Meb]. 31P–{1H} NMR (121.49 MHz, CDCl3, d ppm)
27.52 d, 24.71t, J(PP) = 21.0. Data in italics are for the cyclometal-
lated fragment bonded to the central phosphorus atom. MS-FAB:
7. Supplementary material
CCDC 705890, 705891, 705892, 705893 and 705894 contain the
supplementary crystallographic data for 2b, 3a, 3b, 7a and 7b.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif.
m/z = 913 uma
[(L-H)Pd(trifos)]+.
ESI-MS:
m/z = 1972.1
[MꢀCF3SO3]+. Specific molar conductivity, Km = 304 ohmꢀ1 cm2
molꢀ1 (in acetonitrile).
6.2.15. Preparation of [Pd{3,4-(Me)2C6H2C(Me)@NN(H)[30-(CF3)C4H2-
N2]}{(PPh2CH2 CH2)2PPh-P,P,P}][ClO4] (7a)
Acknowledgments
(PPh2CH2CH2)2)PPh (54.8 mg, 0.103 mmol) was added to a sus-
pension of 2a (50.0 mg, 0.111 mmol) in acetone (20 cm3). The mix-
ture 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 yellow complex precipitated out by addition of water fil-
tered off and chromatographed on a column packed with silica
gel. Elution with dichloromethane–ethanol 1% afforded the desired
product as a yellow solid. Yield 29.1 mg, 27%. Anal. Calc. for
C49H47N4PdO4P3ClF3: C, 56.2; H, 4.5; N, 5.3. Found: C, 56.6; H,
We thank the Ministerio de Educación y Ciencia (CTQ2006-
15621-C02-02/BQU), the Xunta de Galicia and the Universidad de
la Coruña for financial support.
References
[1] I. Omae, in: Organometallic Intramolecular-Coordination Compounds, Elsevier
Science, Amsterdam–New York, 1986.
[2] V.V. Dunina, O.A. Zalevskaya, V.M. Potapov, Russ. Chem. Rev. 571 (1984) 250.
[3] G.R. Newkome, W.E. Puckett, W.K. Gupta, G.E. Kiefer, Chem. Rev. 86 (1986)
451.
4.2; N, 5.1%. IR:
m(C@N) 1584m, m(N–H) 3250 m, m(ClO4) 1099s
cmꢀ1. RMN 1H (300 MHz, CDCl3, d ppm, J Hz): 7.97 [d, 1H, H10,
3J(H10H11) = 4.5], 7.90 [s, br, 1H, NH], 6.57 [d, 1H, H11], 5.56 [d,
1H, H5, 4J(PH5) = 8.31], 2.12 [s, 3H, Me(C@N)], 2.08 [s, 3H, Meb],
1.51 [s, 3H, Mea]. RMN 31P–{1H} (121.49 MHz, CDCl3, d ppm, J
Hz): 87.78 [t, 1P, P, 2J(PP) = 69.6], 42.75 d. ESI-MS: m/z = 947.2
[MꢀClO4]+. Specific molar conductivity, Km = 92.4 ohmꢀ1
cm2 molꢀ1 (in acetonitrile).
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Yield 62.7 mg, 60%. Anal. Calc. for C48H47N4PdCl2O4P3: C, 56.8;
H, 4.7; N, 5.6. Found: C, 56.5; H, 4.5; N, 5.8%. IR:
m(C@N) 1589m,
m
(N–H) 3115m,
m
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ppm, J Hz): 9.35 [s, br, 1H, NH], 6.94, 6.50 [d, 1H, H10, H11,
3J(H10H11) = 9.3], 5.66 [d, 1H, H5, 4J(PH5) = 8.5], 2.18 [s, 3H,
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