Reactivity of tetranuclear complexes of Pd(II) with potentially homo- and heterobidentate ligands

Article abstract of DOI:10.1016/j.poly.2007.06.012

Reaction of the cyclometallated compounds [Pd{2,3,4-(MeO)₃C₆HC(H){double bond, long}N[2-(O)-5-RC₆H₃]}]₄ (1a: R = H, 1b: R = ^tBu) with the phosphine PPh₂[2-(COH)C₆H₄], in a complex/phosphine 1:4 molar ratio gave the mononuclear cyclometallated complexes [{Pd{2,3,4-(MeO)₃C₆HC(H){double bond, long}N[2-(O)-5-RC₆H₃}}{PPh₂[2-(HOC)C₆H₄]}] (2a: R = H; 2b: R = ^tBu), upon cleavage of the tetranuclear structure. Treatment of complex 1a with the diarsine AsPh₂(CH₂)₂Ph₂As (dppae) in a 1:2 or 1:4 molar ratio only yielded the dinuclear compound [{Pd{2,3,4-(MeO)₃C₆HC(H){double bond, long}N[2-(O)C₆H₄]}}₂{μ-AsPh₂(CH₂)₂Ph₂As}] (3a), regardless the molar ratio used. Reaction of the cyclometallated tetramers with Ph₂P(CH₂)₂Ph₂As (arphos) in a 1:4 molar ratio gave the mononuclear cyclometallated complexes [Pd{2,3,4-(MeO)₃C₆HC(H){double bond, long}N[2-(O)C₆H₄]}{PPh₂(CH₂)₂Ph₂As-P}] (4a) and [Pd{2,3,4-(MeO)₃C₆HC(H){double bond, long}N[2-(O)-5-^tBuC₆H₃]}{PPh₂(CH₂)₂Ph₂As-P}] (4b), with the P, As ligand coordinated through the phosphorus atom, as air-stable solids. Treatment of 1a with arphos in a 1:2 molar ratio gave the dinuclear complex [{Pd{2,3,4-(MeO)₃C₆HC(H){double bond, long}N[2-(O)C₆H₄]}}₂{μ-PPh₂(CH₂)₂Ph₂As}] (5a). Reaction of 1b with the diphosphine Ph₂P(C₆H₄)O(C₆H₄)PPh₂ gave the dinuclear compound [{Pd{2,3,4-(MeO)₃C₆HC(H){double bond, long}N[2-(O)-^tBuC₆H₃]}}₂{μ-PPh₂(C₆H₄)O(C₆H₄)Ph₂P}] (6b) for all the complex 1b/phosphine molar ratios tested. Reaction of the cyclometallated tetramer 1a with PPh₂[4-(NMe₂)C₆H₄] (in 1:2 or 1:4 molar ratio) produced the mononuclear cyclometallated complex [Pd{2,3,4-(MeO)₃C₆HC(H){double bond, long}N[2-(O)C₆H₄]}{PPh₂[4-(NMe₂)C₆H₄]}] (7a) as an air-stable solid.

Full text of DOI:10.1016/j.poly.2007.06.012

Polyhedron 26 (2007) 4567–4572
www.elsevier.com/locate/poly
Reactivity of tetranuclear complexes of Pd(II) with potentially
homo- and heterobidentate ligands
a,
a
a
*
´
´
´
´
´
´
Jesus J. Fernandez , Alberto Fernandez , Digna Vazquez-Garcıa ,
a
a
b,
*
´
´
Margarita Lopez-Torres , Antonio Suarez , Jose M. Vila
a
Departamento de Quı´mica Fundamental, Universidad de La Corun˜a, E-15071 La Corun˜a, Spain
Departamento de Quı´mica Inorga´nica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
b
Received 30 April 2007; accepted 9 June 2007
Available online 27 June 2007
Abstract
Reaction of the cyclometallated compounds [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-5-RC6H3]}]4 (1a: R = H, 1b: R = tBu) with the
phosphine PPh2[2-(COH)C6H4], in a complex/phosphine 1:4 molar ratio gave the mononuclear cyclometallated complexes [{Pd{2,3,4-
(MeO)3C6HC(H)@N[2-(O)-5-RC6H3}}{PPh2[2-(HOC)C6H4]}] (2a: R = H; 2b: R = tBu), upon cleavage of the tetranuclear structure.
Treatment of complex 1a with the diarsine AsPh2(CH2)2Ph2As (dppae) in a 1:2 or 1:4 molar ratio only yielded the dinuclear compound
[{Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}}2{l-AsPh2(CH2)2Ph2As}] (3a), regardless the molar ratio used. Reaction of the cyclomet-
allated tetramers with Ph2P(CH2)2Ph2As (arphos) in a 1:4 molar ratio gave the mononuclear cyclometallated complexes [Pd{2,3,4-
(MeO)3C6HC(H)@N[2-(O)C6H4]}{PPh2(CH2)2Ph2As-P}] (4a) and [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-5-tBuC6H3]}{PPh2(CH2)2-
Ph2As-P}] (4b), with the P,As ligand coordinated through the phosphorus atom, as air-stable solids. Treatment of 1a with arphos in
a 1:2 molar ratio gave the dinuclear complex [{Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}}2{l-PPh2(CH2)2Ph2As}] (5a). Reaction of
1b with the diphosphine Ph2P(C6H4)O(C6H4)PPh2 gave the dinuclear compound [{Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-tBuC6H3]}}2
{l-PPh2(C6H4)O(C6H4)Ph2P}] (6b) for all the complex 1b/phosphine molar ratios tested. Reaction of the cyclometallated tetramer 1a
with PPh2[4-(NMe2)C6H4] (in 1:2 or 1:4 molar ratio) produced the mononuclear cyclometallated complex [Pd{2,3,4-
(MeO)3C6HC(H)@N[2-(O)C6H4]}{PPh2[4-(NMe2)C6H4]}] (7a) as an air-stable solid.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Palladium; Metallation; Phosphines; As ligand; [P,As] ligand; [P,N] ligand
1. Introduction
[13]; they are also useful as therapeutic agents in anticancer
drugs [14] or as structural fragments on polystyrene-immo-
bilized catalysts [15]. Numerous reactions of cyclometal-
lated compounds with tertiary phosphines have been
reported by us and others [16].
In the past, we have been interested in palladium(II) and
platinum(II) cyclometallated complexes derived from
[C,N,X] (X = O,S) terdentate ligands. Those derived
from [C,N,S] thiosemicarbazones I (Fig. 1) [17–20] or from
Schiff bases with phenolate oxygen atoms II (Fig. 1) [21,22]
show tetranuclear structures, with eight-membered Pd4X4
cores (X = O,S), bearing two different types of
P–X bonds: P–Xchelating and P–Xbridging, which bind the
ligand tightly to the metal centre. The reaction of these
compounds with mono and bidentate tertiary phosphines
Cyclometallation and phosphines constitute relevant
topics in organometallic chemistry and several reviews cov-
ering the former have appeared [1–8]. Tertiary mono- and
polydentate phosphine ligands stabilize a great variety of
metal complexes in different oxidation states and phos-
phine containing complexes are good catalysts [9,10], e.g.,
in the hydrogenation of aldehydes [11] and aromatic
ketones [12] or the carbonylation of metal–methyl bonds
*
Corresponding authors. Tel.: +34 9 8152800; fax: +34 981 595012
´
(J.M. Vila), +34 981 167065 (J.J. Fernandez).
E-mail addresses: qiluaafl@udc.es (J.J. Fernandez), qideport@usc.es
(J.M. Vila).
´
0277-5387/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.06.012

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J.J. Ferna´ndez et al. / Polyhedron 26 (2007) 4567–4572
Treatment of 1a and 1b with PPh2[2-(COH)C6H4] in 1:4
molar ratio or with Ph2P[4-(NMe2)C6H4] in 1:2 or 1:4 molar
ratios, afforded the mononuclear complexes [Pd{2,3,
4-(MeO)3C6HC(H)@N[2-(O)C6H4}{PPh2[2-HOC)C6H4]}]
(2a) [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-5-tBuC6H3} {P
Ph2[2-(HOC)C6H4]}] (2b) and [Pd{2,3,4-(MeO)3C6HC-
(H)@N[2-(O)C6H4]}{PPh2[4-(NMe2)C6H4]}] (7a), respec-
tively, as air stable solids, in which the tetrameric structure
was cleaved after P–Obridging bond cleavage. Coordination
of the palladium atom to the C@N moiety was confirmed
by the shift to lower wavenumbers of the m(C@N) band, as
compared to the free ligand [21,24,25]. Absence of the
m(OH) band was in agreement with the presence of a pheno-
late oxygen bonded to the palladium atom [21,22]. These
findings were observed for the remaining compounds and
shall not be discussed further (see Section 4). The proton res-
onances were unequivocally assigned (see Section 4); those
ascribed to H5 and HC@N appeared as doublets due to cou-
pling with the 31P nucleus with J values of ca. 4 and 10 Hz,
respectively. In the 31P–{1H} spectra the phosphorus reso-
nance signal appeared as a singlet ca. d 33.0 ppm; these find-
ings were in agreement with a phosphorus trans to nitrogen
arrangement [21,26–30]. The signals assigned to the H5
and 4-OMe protons were shifted to lower frequency, as com-
pared to the cyclometallated complexes 1a and 1b, due to
shielding of phosphine phenyl rings. We have previously
observed similar shifts in related complexes, confirming the
relative trans disposition of the nitrogen atom and the
phosphine ligand [17,31]. The FAB mass spectra showed
the cluster of peaks characteristic of the [M]+ fragment at
680, 2a, 738, 2b, and 697, 7a uma.
Reaction of 1a with AsPh2(CH2)2Ph2As (dppae) in a
1:2 ratio in acetone, gave the dinuclear cyclometallated
complex [{Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}}2
{l-AsPh2(CH2)2Ph2As}] (3a) as an air stable solid. In
the 1H NMR spectrum the HC@N and H5 proton
resonances appeared as singlets at d 7.57 and 5.51 ppm,
respectively. The H5 and 4-OMe resonances were shifted
towards lower frequency by ca. 0.2 and 1.2 ppm,
respectively, due to the shielding effects of the diarsine
phenyl rings. Only one set of signals was observed for
the proton resonances, indicative of the symmetrical nat-
ure of the compounds. The FAB mass spectrum showed
two clusters of peaks centred at 1271 and 878 uma,
assigned to the molecular ion and to loss of one cyclomet-
allated unit, respectively. Compound 3a was also isolated
when excess dppa was used, establishing the strength of
the Pd–Ochelating bond, which was not cleaved even under
these reaction conditions.
R
R
Pd
M
H
N
R
O
R
N
I
S
N
4
NHR
n
II
M = Pd
M = Pd, Pt
Ph2
P
PPh2
X
Pd
Pd Cl
Cl
Me
N
S
N
NHR
III
Fig. 1. Cyclometallated complexes with [C, N, X] (X = O, S) ligands.
brings about opening of the tetranuclear structure due to
the P–Xbridging bond cleavage, whereas the P–Xchelating
bond persists, even when large excess of the phosphine
was used, putting forward its unusual strength. More
recently, we have shown that reaction of the tetranuclear
tetramers derived from thiosemicarbazones (X = S) with
bis(diphenylphosphino)methane caused cleavage of the
tetranuclear structure to give new mononuclear complexes,
in which the phosphine is monodentate, where one
phosphorus atom is uncoordinated. These complexes
represent a new class of bidentate [P,S] chelating metalloli-
gands capable of coordinating a second metal centre and,
therefore, may be used as building blocks in the construc-
tion of polynuclear structures III (Fig. 1) [23].
We reasoned that the similar behavior of terdentate
[C,N,O] Schiff base species towards nucleophiles, in terms
of a strong P–Ochelating bond, could be used to explore a
new range of compounds upon reaction of the former with
phosphines, arsines, and mixed phosphorus/arsenic
ligands. Therefore, herein, we report the reactivity of com-
plexes [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-5-RC6H3]}]4
(1a: R = H, 1b: R = tBu) with bidentate [P,O], [P,As],
[P,P], [As,As] and [P,N] ligands.
Treatment of 1a or 1b with Ph2P(CH2)2Ph2As (arphos) in
the appropriate molar ratio afforded compounds [Pd{2,3,4-
(MeO)3C6HC(H)@N[2-(O)C6H4]}{PPh2(CH2)2Ph2As-P}]
(4a), [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-5-tBuC6H3]} {P
Ph2(CH2)2Ph2As-P}] (4b), and [{Pd{2,3,4-(MeO)3C6HC
(H)@N[2-(O)C6H4]}}2{l-PPh2(CH2)2Ph2As}] (5a). Coordi-
nation of the ligand through the phosphorus atom was
confirmed by: (a) the multiplicity of the H5 and HC@N
2. Results and discussion
The compounds and reactions are shown in Scheme 1.
The compounds were characterised by IR and by 1H,
31P–{1H} spectroscopy and, in part, FAB mass spectrome-
try; the elemental analysis (C,H,N) supports the expected
elemental composition (data in Section 4).

J.J. Ferna´ndez et al. / Polyhedron 26 (2007) 4567–4572
4569
OMe
O
N
MeO
MeO
Pd
OMe
OMe
OMe
As
P
MeO
MeO
Ph2
O
Ph2
Pd
As
Ph2
N
R
O
OMe
Pd
N
O
3
ii
i
1-2
OMe
OMe
MeO
MeO
OMe
Ha
Hb
4
MeO
MeO
MeO
MeO
5
3
P
Ph2
AsPh2
Ph2
P
NMe2
vi
Pd
2
Pd
N
R
Pd
O
iii
Ha
Hb
N
O
N
O
8
11
10
9
R
4
8
4-5
a: R= H, b: R= tBu
iv
tBu
v
O
N
Hi'
OMe
O
N
Pd
OMe
N
OMe
MeO
MeO
Pd
MeO
MeO
H5
Pd
As
OMe
Ph2
P
P
O
H5'
OMe
Ph2
Ph2
P
Pd
Ph2
OMe
OMe
OMe
N
O
Hi
O
6
7
But
Scheme 1. (i) Phosphine (acetone, 1:4 molar ratio), (ii) dppae (acetone, 1:2 or 1:4 molar ratio), (iii) arphos (acetone, 1:4 molar ratio), (iv) arphos (acetone,
1:2 molar ratio), (v) diphosphine (acetone, 1:2 or 1:4 molar ratio), (vi) phosphine (dichloromethane, 1:2 or 1:4 molar ratio).
resonances, which were observed as doublets by coupling to
the 31P nucleus; (b) the chemical shift of the phosphorus res-
onance signal at d 32.5 (4a), d 33.4 (4b) and d 34.0 (5a), down-
field shifted from its position in the spectrum of the free
phosphine, and also in agreement with a phosphorus trans
to nitrogen coordination to the metal center [21,26–30].
The asymmetric nature of compound 5a was evidenced by
the two distinct sets of proton signals observed for both
cyclometallated moieties. Accordingly, two doublet reso-
nances at d 8.14 and d 5.42, were assigned to the H5 and
HC@N protons, respectively, coupled to the 31P nucleus
[MH]+ ions; their isotopic pattern confirmed the mononu-
clear formula of the complexes. For compound 5a a cluster
of peaks at 1226 uma was consistent with a dinuclear
formula.
Treatment of 2b with Ph2P(C6H4)O(C6H4)Ph2P in a 1:2
or 1:4 molar ratio at room temperature in acetone gave the
dinuclear compound [{Pd{2,3,4-(MeO)3C6HC(H)@N[2-
(O)-tBuC6H3]}}2{l-PPh2(C6H4)O(C6H4)Ph2P}] (6b) (the
use of excess phosphine only gave 6b and unreacted 2b),
after column chromatography (see Section 4). Therefore,
the diphosphine could not behave as monodentate through
only one phosphorus atom. Thus, both sets of HC@N and
H5 resonances showed coupling to the phosphorus nuclei
[4J(HP) = 10.7 and 4J(HP) = 3.7 Hz], and the 31P–{1H}
NMR spectrum revealed a singlet at d 28.2, in agreement
with equivalent phosphorus nuclei.
4
with [4J(HiP) = 10.5 Hz, J(H5P) = 3.9 Hz], and two sing-
lets were ascribed to the H50 and H0C@N protons at d 7.58
and d 5.56, respectively.
In the FAB mass spectra the set of peaks at 834 and 890
uma, for 4a and 4b, respectively, were assigned to the

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J.J. Ferna´ndez et al. / Polyhedron 26 (2007) 4567–4572
4
3. Conclusions
3J(H11H10) = 7.6, J(H9H11) = 1.5]. FAB-MS: m/z = 1566
[M]+; 391 [M/4]+.
We have shown that Schiff base ligands derived from 2-
aminophenols secure three metal coordination sites in
cyclometallated palladium(II) compounds and leave but
one bonding site for further reaction with nucleophiles,
such as tertiary phosphines or arsines. Consequently, the
P–Ochelating bond remained throughout all the processes
in this study, and it was not cleaved upon reaction with
the nucleophiles tested. Additional coordinating atoms on
the phosphine ligand, such as nitrogen or oxygen, did not
show any relevant bonding properties. However, diphos-
phines or diarsines could bridge two cyclometallated moie-
ties, rendering dinuclear species.
4.3. [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-
5-tBuC6H3]}]4 (1b)
Anal. Calc for C68H68N4O16Pd4: C, 50.3; H, 4.2; N, 3.5.
Found: C, 50.1; H, 4.1; N, 3.5%. IR: m(C@N), 1571sh, m
1
t
cmꢀ1. H NMR (200 MHz, CDCl3): d = 1.24 [s, 9H, Bu];
3.38, 3.81, 4.03 [s, 9H, MeO]; 5.81 [s, 1H, H5]; 6.75 [d,
1H, H8, 4J(H8H10) = 2.2]; 6.99 [dd, 1H, H10,
4
3J(H10H11) = 8.8, J(H8H10) = 2.2]; 7.35 [d, 1H, H11]; 7.54
[s, 1H, HC@N]. FAB-MS: m/z = 1792 [MH]+; 896 [M/2]+.
In the case of arphos, this ligand showed to be versatile
in its coordination to the cyclometallated complexes 1a and
1b. Thus, by adjusting the relative molar ratio, mono- or
dinuclear complexes could be prepared, with the ligand
behaving as mono- or bidentate, respectively. Still, arphos
did not act as a chelating ligand, regardless of the reaction
conditions employed.
4.4. [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}-
{PPh2[2-(HOC)C6H4]}] (2a)
PPh2(4-(HOC)C6H4) (49.8 mg, 0.31 mmol) was added to
a
suspension of [Pd{2,3,4-(MeO)3C6HC(H)@N(2-(O)-
C6H4)] (36.9 mg, 0.31 mmol) in acetone (15 cm3). The mix-
ture was stirred for 12 h and the solvent removed to give a
violet solid which was recrystallized from dichlorometh-
ane/hexane. Yield 56%. Anal. Calc. for C35H29NO5PPd: C,
61.7; H, 4.3; N, 2.0. Found: C, 61.5; H, 4.3; N, 1.9%. IR:
m(C@O), 1697s cmꢀ1, m(C@N), 1572s cmꢀ1. FAB-MS: m/
4. Experimental
4.1. General procedures
z = 680 [M]+. H NMR (300 MHz, CDCl3, d ppm, J Hz):
1
4
Solvents were purified by standard methods [32]. Chem-
icals were reagent grade. The phosphines PPh2[2-(HOC)
C6H4], PPh2(CH2)2Ph2As (arphos), Ph2P(C6H4)O(C6H4)
Ph2P and Ph2P[4-(NMe2)C6H4] were purchased from
Aldrich-Chemie. Ph2As(CH2)2Ph2As (dppae) were pur-
chased from ALFA. Microanalyses were carried out using
a Carlo Erba Elemental Analyzer, Model 1108. The cyclo-
metallated complexes 1a and 1b were synthesized using the
procedure reported recently by us [21]. IR spectra were
recorded as KBr discs on a Perkin–Elmer 1330 and on
Mattson spectrophotometers. NMR spectra were obtained
in CDCl3 and referenced to CHCl3 (1H and 13C–{1H}) or
85% H3PO4 (31P–{1H}) and were recorded on Bruker
AC-2005 or Bruker AVANCE 300 spectrometers. 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 was
used as the matrix.
10.37 [d, 1H, HC@O, J(HP) = 2.4], 8.14 [d, 1H, HC@N,
4J(HP) = 10.8], 7.59 [t, 1H,3J(HH) = 7.6], 7.10 [d, 1H, H8,
3J(H8H9) = 7.1], 6.89 [m, 2H, H10, H11], 6.30 [m, 2H, H9,
H11], 5.54 [s, 1H, H5, J(H5P) = 4.9], 3.94 (s, 3H, MeO),
4
3.72 (s, 3H, MeO), 2.95 (s, 3H, MeO). 31P–{1H} NMR
(121.44 MHz, CDCl3, d ppm): 33.3 s.
Compound 2b was obtained following a similar proce-
dure as a violet solid.
4.5. [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-
5-tBuC6H3]}{PPh2[2-(HOC)C6H4]}] (2b)
Yield 66%. Anal. Calc. for C39H38NO5PPd: C, 63.4; H, 5.2;
N, 1.9. Found: C, 63.4; H, 5.1; N, 1.8%. IR: m(C@O), 1697s
cmꢀ1, m(C@N), 1571s cmꢀ1. FAB-MS: m/z = 738 [M]+. H
1
NMR (200 MHz, CDCl3, d ppm, J Hz): 10.34 [d, 1H, HC@O,
4J(HP) = 2.4], 8.11 [d, 1H, HC@N, 4J (HP) = 10.7], 7.02 [d,
1H, H8, 4J(H8H10) = 2.3], 6.92 [dd, 1H, H10,
3J(H10H11) = 8.6, 4J(H8H10) = 2.3], 6.22 [d, 1H, H11,
Analytical and spectroscopic data for the cyclometal-
lated starting complexes 1a and 1b.
4
3J(H10H11) = 8.6], 5.52 [s, 1H, H5, J(H5P) = 3.9], 3.98 (s,
3H, MeO), 3.74 (s, 3H, MeO), 2.95 (s, 3H, MeO), 1.24 (s,
9H, tBu). 31P–{1H} NMR (80.96 MHz, CDCl3, d ppm) 33.3 s.
Compound 3a was obtained following a similar proce-
dure, as a red solid, but using a complex cyclometallated/
diarsine 1:4 or 1:2 molar ratio.
4.2. [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}]4 (1a)
Anal. Calc. for C64H60N4O16Pd4: C, 49.1; H, 3.8; N, 3.6.
Found: C, 48.9; H, 3.8; N, 3.5%. IR: m(C@N), 1589sh, m
1
cmꢀ1. H NMR (200 MHz, CDCl3, d ppm, J Hz): 3.51 [s,
3H, OMe]; 3.82 [s, 3H, OMe]; 4.02 [s, 3H, OMe]; 5.67
[s, 1H, H5]; 7.57 [s, 1H, HC@N]; 6.62 [dd, 1H, H8,
3J(H8H9) = 7.6, 4J(H8H10) = 1.5]; 6.37 [dt, 1H, H9,
3J(H9H10) = 7.5, 4J(H9H11) = 1.5]; 6.91 [dt, 1H, H10,
3J(H10H11) = 7.5, 4J(H8H10) = 1.5]; 7.44 [d, 1H, H11,
4.6. [{Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}}2-
{l-AsPh2(CH2)2Ph2As}] (3a)
Yield 49%, using 1:2 molar ratio and 21% using 1:4
molar ratio. Anal. Calc. for C58H54N2O8Pd2As2: C, 54.8;

J.J. Ferna´ndez et al. / Polyhedron 26 (2007) 4567–4572
4571
H, 4.3; N, 2.2. Found: C, 54.7; H, 4.2; N, 2.1%. IR:
PCH2CH2As). 31P–{1H} NMR (80.96 MHz, CDCl3, d
ppm): 34.0 s.
m(C@N), 1572s cmꢀ1
.
FAB-MS: m/z = 1271 [MH]+; 878, [LPd(AsPh2(CH2)2-
Ph2As)]+. 1H NMR (200 MHz, CDCl3, d ppm, J Hz):
7.57 [s, 1H, HC@N], 6.9 [m, 2H, H8,H10], 6.59 [d, 1H,
H11, 3J(H10H11) = 7.8], 6.35 [t, 1H, H9, J(H8H9) = 7.1],
5.51 [s, 1H, H5], 3.01 (s, br, 2H, AsCH2), 3.93 (s, 3H,
MeO), 3.71 (s, 3H, MeO), 2.63 (s, 3H, MeO).
4.10. [{Pd{2,3,4-(MeO)3C6HC(H)@N[2-
(O)-tBuC6H3]}}2{l-PPh2(C6H4)O(C6H4)Ph2P}] (6b)
A suspension of complex 1b in acetone was treated
with PPh2(C6H4)O(C6H4)Ph2P (cyclometallated complex/
diphosphine 1:4 or 1:2 molar ratio) in acetone and the
resulting mixture was stirred for 24 h. The solvent was then
removed under vacuum to give a violet solid which was
chromatographed on a column packed with silica gel. Elu-
tion with CH2Cl2–C2H5OH (99:1) afforded a violet oil after
solvent removal, which was recrystallized from dichloro-
methane–hexane to give the desired product as a violet
solid. Yield 27%. Anal. Calc. for C76H74N2O9P2Pd2: C,
68.2; H, 5.2; N, 1.4. Found: C, 68.1; H, 5.1; N, 1.3%. IR:
Compounds 4a, 4b were prepared similarly, as violet sol-
ids, using a cyclometallated complex/arsinophosphine 1:4
molar ratio.
4.7. [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}-
{PPh2(CH2)2Ph2As-P}] (4a)
Yield 64%. Anal. Calc. for C42H39NO4PPdAs: C, 60.5;
H, 4.7; N, 1.7. Found: C, 60.4; H, 4.6; N, 1.6%. IR:
m(C@N), 1569s cmꢀ1. FAB-MS: m/z = 834 [MH]+. 1H
NMR (200 MHz, CDCl3, d ppm, J Hz): 8.15 [d, 1H,
m(C@N), 1565s cmꢀ1
.
1H NMR (300 MHz, CDCl3, d
4
ppm, J Hz): 8.00 [d, 1H, HC@N, J(HP) = 10.7], 5.59 [d,
4
3
4
HC@N, J(HP) = 9.7], 7.13 [dd, 1H, H8, J(H8H9) = 8.0,
4J(H8H10) = 1.4], 6.96 [dt, 1H, H10, 3J(H9H10) = 8.0,
4J(H8H10) = 1.4], 6.63 [d, 1H, H11, 3J(H10H11) = 8.0],
6.39 [t, 1H, H9, 3J(H9H10) = 8.0], 5.47 [d, 1H, H5,
4J(H5P) = 2.4], 3.94 (s, 3H, MeO), 3.72 (s, 3H, MeO),
2.95 (s, 3H, MeO), 2.48 (br, 4H, PCH2CH2As). 31P–{1H}
NMR (80.96 MHz, CDCl3, d ppm): 32.5 s.
1H, H5, J(H5P) = 3.7], 4.00 (s, 3H, MeO), 3.77 (s, 3H,
MeO), 3.02 (s, 3H, MeO), 1.27 (s, 9H, Bu). 31P–{1H}
t
NMR (121.44 MHz, CDCl3, d ppm): 28.2 s.
Compound 7a was obtained as a violet solid following a
similar procedure to the one used for 6b but using dichlo-
romethane as solvent.
4.11. [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}-
{PPh2[4-(NMe2)C6H4]}] (7a)
4.8. [Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)-
5-tBuC6H3]}{PPh2(CH2)2Ph2As-P}] (4b)
Yield 67%, using 1:4 molar ratio, and 36% using 1:2
molar ratio. Anal. Calc. for C36H35N2PdO4P: C, 62.0; H,
5.1; N, 4.0. Found: C, 62.1; H, 5.1; N, 4.1%. IR:
m(C@N), 1572s cmꢀ1. FAB-MS: m/z = 697 [M]+. 1H
NMR (300 MHz, CDCl3, d ppm, J Hz): 8.17 [d, 1H,
Yield 56%. Anal. Calc. for C46H47NO4PPdAs: C, 62.1;
H, 5.3; N, 1.6. Found: C, 62.2; H, 5.1; N, 1.5%. IR:
m(C@N), 1571s cmꢀ1. FAB-MS: m/z = 890 [MH]+. 1H
NMR (200 MHz, CDCl3, d ppm, J Hz): 8.13 [d, 1H, Hi,4J
4
(HiP) = 10.2], 7.08 [d, 1H, H8, J(H8H10)= 2.4], 7.03 [dd,
HC@N,
4J(HP) = 10.4],
7.11
[dd,
1H,
H8,
1H, H10, J(H10H11) = 8.5, J(H8H10) = 2.4], 6.57 [d, 1H,
H11, 3J(H10H11) = 8.5], 5.48 [s, 1H, H5, 4J(H5P) = 3.4],
3.97 (s, 3H, MeO), 3.72 (s, 3H, MeO), 2.95 (s, 3H, MeO),
3J(H8H9) = 7.5, 4J(H8H10) = 1.9], 6.89 [dt, 1H, H10,
3J(H10H11) = 8.4, 4J(H8H10) = 1.9], 6.68 [dd, Hb,
3J(HaHb) = 8.0, 4J(HbP) = 1.6], 6.44 [d, 1H, H11,
3
4
2.47 (br, 4H, PCH2CH2As), 1.29 (s, 9H, Bu). 31P–{1H}
3J(H10H11) = 8.4], 6.34 [t, 1H, H9, J(H9H10) = 7.5], 5.61
t
3
NMR (80.96 MHz, CDCl3, d ppm): 33.4 s.
Compound 5a was obtained following a similar proce-
dure as violet solid but using a complex cyclometallated/
arphos 1:2 molar ratio.
[d, 1H, H5, 4J(H5P) = 4.9], 3.95 [s, 3H, MeO], 3.73 [s,
3H, MeO], 2.97 [s, 3H, MeO], 2.98 [s, 6H, Me2]. 31P–
{1H} NMR (121.44 MHz, CDCl3, d ppm): 32.3 s.
Acknowledgements
4.9. [{Pd{2,3,4-(MeO)3C6HC(H)@N[2-(O)C6H4]}}2-
{l-PPh2(CH2)2Ph2As}] (5a)
´
We thank the Ministerio de Educacion y Ciencia (Pro-
ject CTQ2006-15621-C02-01/BQU) for financial support.
Yield 64%. Anal. Calc. for C42H39NO4PPdAs: C, 60.5;
H, 4.7; N, 1.7. Found: C, 60.4; H, 4.6; N, 1.6%. IR:
m(C@N), 1572s cmꢀ1. FAB-MS: m/z = 1226 [M]+; 834
[LPd(arphos)]+. 1H NMR (200 MHz, CDCl3, d ppm, J
Hz): 8.14 [d, 1H, HC@N, 4J(HP) = 10.5], 7.58 [s, 1H,
H0C@N], 7.12 [d, br, 1H, H8], 6.95 [t, br, 1H, H10], 6.59
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