Seeking new metalloligands: Synthesis and reactivity of palladacycles with pyridine and pyrimidine rings

Article abstract of DOI:10.1016/j.poly.2009.05.005

Treatment of the Schiff base ligands 4-(NC₅H₄)C₆H₄C(H){double bond, long}N[2′-(OH)C₆H₄] (a), 3,5-(N₂C₄H₃)C₆H₄C(H){double bond, long}N[

Full text of DOI:10.1016/j.poly.2009.05.005

Polyhedron 28 (2009) 2679–2683
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Seeking new metalloligands: Synthesis and reactivity of palladacycles
with pyridine and pyrimidine rings
a
a
a
Jesús J. Fernández a, , Nina Gómez-Blanco , Alberto Fernández , Digna Vázquez-García ,
*
Margarita López-Torres 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
Treatment of the Schiff base ligands 4-(NC5H4)C6H4C(H)@N[20-(OH)C6H4] (a), 3,5-(N2C4H3)C6H4C(H)@
N[20-(OH)-C6H4] (b) and 3,5-(N2C4H3)C6H4C(H) @N[20-(OH)-50-tBuC6H3] (c) with palladium (II) acetate
in toluene gave the poly-nuclear cyclometallated complexes [Pd{4-(NC5H4)C6H3C(H)@N[20-(O)C6H4]}]4
(1a), [Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-C6H4]}]4 (1b) and [Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-
50-tBuC6H3]}]4 (1c) respectively, as air stable solids, with the ligand acting as a terdentate [C,N,O] moiety
after deprotonation of the –OH group. Reaction of the cyclometallated complexes with triphenylphos-
phine gave the mononuclear species [Pd{4-(NC5H4)C6H3C(H) @N[20-(O)C6H4]}(PPh3)], (2a), [Pd{3,5-
(N2C4H3)C6H3C(H)@N[20-(O)C6H4]}(PPh3)], (2b) and [Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-50-tBuC6H3)}
(PPh3)], (2c) in which the polynuclear structure has been cleaved and the coordination of the ligand
has not changed [C,N,O]. When the cyclometallated complexes 1b and 1c were treated with the diphos-
phines Ph2P(CH2)4PPh2 (dppb), Ph2PC5H4FeC5H4PPh2 (dppf) and Ph2P(CH2)2PPh2 (t-dppe) in a 1:2 molar
Article history:
Received 14 January 2009
Accepted 5 May 2009
Available online 12 May 2009
Keywords:
Palladium
Metallation
Phosphines
Metalloligands
ratio the dinuclear cyclometallated complexes [{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-(O)C6H4}]}2(
P(CH2)4PPh2)], (3b), [{Pd[3,5-(N2C4H3)C6H3C(H) @N{20-(O)-50-tBuC6H3}]}2(
-Ph2P(CH2)4PPh2)], (3c), [{Pd
[3,5-(N2C4H3)C6H3C(H)@N{20-(O)C6H4}]}2( 5-C5H4)Fe( 5-C5H4)PPh2)], (4b), [{Pd[3,5-(N2C4H3-
-Ph2P(
C6H3C(H)@N{20-(O)-50-tBuC6H3}]}2( 5C5H4)Fe( 5C5H4)P-Ph2)], (4c) and [{Pd[3,5-(N2C4H3)C6H3-
-Ph2P(
C(H)@N{20-(O)-50-tBuC6H3}]}2(
-Ph2P(CH@CH)PPh2)], (5c) were obtained as air stable solids.
Ó 2009 Elsevier Ltd. All rights reserved.
l-Ph2-
l
l
g
g
l
g
g
l
1. Introduction
and P–Xbridging, which bind the ligand tightly to the metal centre.
More recently, we have shown that reaction of the tetranuclear tet-
ramers derived from thiosemicarbazones (X@S) with bis(diphenyl-
phosphino)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
metalloligands capable of coordinating a second metal centre and,
therefore, may be used as building blocks in the construction of
polynuclear structures [18].
On the other hand, ligands with pyridine and pyrimidine rings
have been extensively studied as building blocks in the construc-
tion of supramolecular assemblies [19–27]. We reasoned that the
combination of the unusual structure shown by the cyclometallat-
ed tetramers with ligands containing pyridine o pyrimidine rings
could result in a new type of metalloligands with potential applica-
tions in the construction of supramolecular aggregates, and these
results are presented herein.
The chemistry of cyclometallated transition metal complexes
has attracted much attention in past decades. They are usually clas-
sified according to the metal, to the donor atom, or to chelate ring
size; by far the most well-studied examples are five-membered pal-
ladacycles [1]. They exhibit a good number of applications which
range from the use as chiral auxiliaries [2], as building blocks for
molecular architectures of higher complexity [3] or as compounds
with interesting mesogenic [4] and luminescent and electronic
properties [5], as well as their potential use in medicine and biology
[6] and in catalytic and synthetic processes [7].
We have been interested in palladium(II) and platinum(II)
cyclometallated complexes derived from [C,N,X] (X = O, S) terden-
tate ligands. Those derived from [C,N,S] thiosemicarbazones [8–13]
or from Schiff bases with phenolate oxygen atoms [14–17] show
tetranuclear structures, with eight- membered Pd4X4 cores
(X = O, S), bearing two different types of P–X bonds: P–Xchelating
2. Results and discussion
* Corresponding authors. Fax: +34 981 167065 (J.J. Fernández), tel.: +34 981
563100x14255; fax: +34 981 595012 (J.M. Vila).
For the convenience of the reader the compounds and reactions
are shown in Schemes 1 and 2. The compounds described in this
E-mail addresses: qiluaafl@udc.es (J.J. Fernández), josemanuel.vila@usc.es
(J.M. Vila).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.05.005

2680
J.J. Fernández et al. / Polyhedron 28 (2009) 2679–2683
paper were characterised by elemental analysis (C, H, N) and by IR
and by 1H, 31P–{1H} spectroscopy and, in part, FAB mass spectrom-
etry (data in Section 3).
C@N nitrogen, was confirmed by the shift to lower wavenumbers
of the (C@N) band, as compared to the free ligand
[14,16,17,27,28]. Absence of the (OH) band in the IR spectra and
m
m
Reaction of the Schiff base ligands a, b and c with palladium (II)
acetate in toluene at 60 °C gave [Pd{4-(NC5H4)C6H3C(H)@N[20-
(O)C6H4]}]4, 1a, [Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-C6H4]}]4, 1b
of the OH resonance in the 1H NMR spectra was in agreement with
the presence of a phenolate oxygen bonded to the palladium atom
[14,16,17]. These findings were observed for the remaining com-
pounds and shall not be discussed further (see Section 3). The mass
FAB spectra showed the cluster of peaks characteristic of the [M]+
fragment at 640, 2a, 641, 2b, and 697, 2c, uma.
and
respectively, as air stable solids. The IR spectra showed the shift
of the (C@N) stretch toward lower wavenumbers, as compared
to the free ligand, due to N-coordination of the imine [28,29].
The absence of the (O–H) band (present in the spectra of the free
ligands at 3415, a, 3336, b and 3226, c, cmꢀ1) was in accordance
with loss of the –OH proton. The absence of (COO) bands in the
[Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-50-tBuC6H3]}]4,
1c,
m
Reaction of 1b–1c with the diphosphines, dppb, trans-dppe and
dppf in 1:2 molar ratio gave the dinuclear cyclometallated
m
complexes [{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-(O)C6H4}]}2(
l
-Ph2P-
(CH2)4PPh2)] 3b, [{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-(O)-50-tBuC6-
H3}]}2(
-Ph2P(CH2)4PPh2)] 3c, [{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-
(O)C6H4}]}2-( -Ph2P(
5-C5H4)Fe( 5-C5H4)PPh2)] 4b, [{Pd[3,5-(N2-
C4H3)C6H3C(H)@N{20-(O)-50-tBuC6H3}]}2( 5C5H4)Fe-
-Ph2P(
5C5H4)P-Ph2)] 4c and [{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-(O)-
50-tBuC6H3}]}2(
-PPh2(trans-(CH)2)PPh2)] 5c, as air stable solids
m
IR spectra precludes the formation of the compounds as the typical
dinuclear species with bridging acetate ligands, as found earlier
when using palladium (II) acetate as the metal salt. Unfortunately
the insolubility of 1a, 1b and 1c precluded their characterization in
solution. Nevertheless, the characterization of their phosphine
derivatives, vide infra, unambiguously established metallation at
the phenyl ring through the position adjacent to the imino group.
However, the tetrameric nature of the complexes has not been
unequivocally determined. The tetranuclear disposition of similar
complexes have been described by us [14,16,17] and others
[15,30]; their spectra and reactivity were similar to the one shown
by 1a, 1b and 1c, however, only the FAB-mass spectra 1c showed
the expected molecular ion whilst 1a and 1b spectra showed peaks
corresponding to 2/3 and 1/2, respectively of the mass expected for
a tetramer. Consequently, the tetranuclear formulation given here
for complexes 1a, 1b and 1c is only tentative.
Treatment a, b and c with PPh3 in 1:4 molar ratio afforded the
mononuclear complexes [Pd{4-(NC5H4)C6H3C(H)@N[20-(O C6H4]}-
(PPh3)] 2a, [Pd{3,5-(N2C4H3)C6H3C(H) @N-[20-(O)C6H4]}(PPh3)] 2b,
and [Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-50-tBuC6H3)}-(PPh3)] 2c.
The proton resonances were unequivocally assigned (see Section
3). The spectra showed the absence of the signal corresponding
to H6 consequent on Pd–C bond formation. The H5 resonance
was coupled to the 31P nucleus, with 4J(PH) ca. 4 Hz, and to H3
[3J(H3H5) = 1.7 Hz]. The signal assigned to HC@N was as a doublet
by coupling to the 31P nucleus with 4J(PH) ca. 10 Hz. In the 31P–{1H}
spectra the phosphorus resonance was a singlet ca. d34.5 ppm, in
agreement with a phosphorus trans to nitrogen arrangement
[14,16,17,31–34]. The signals assigned to the H5 and H14, H18 pro-
tons were strongly shifted to lower frequency, as compared to the
uncoordinated ligands 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 [14,16,9]. The H15, H17 protons in 2a
and H16 in 2b and 2c were also affected by the shielding but to
a lesser extent. Coordination of the palladium atom trough the
l
l
g
g
l
g
(g
l
(see Section 3). Again, as with 2b and 2c, the spectroscopic data
confirm the proposed structures for 1b and 1c. Thus, the most
noticeable characteristics were the absence of the
m(OH) band
and the shift to lower wavenumbers of the (C@N) band in the
m
IR spectra; and in the 1H NMR spectra, absence of the H6 reso-
nance and coupling of the H5 and HC@N protons to the 31P nucleus,
as a consequence of the coordination of the diphosphine. In the
31P–{1H} NMR spectra only one singlet was assigned for the two
equivalent nuclei; accordingly, only one set of signals was
observed for the two equivalent metallated moieties, in accordance
with the symmetric nature of the dinuclear complexes. The mass
FAB spectra of the complexes showed the set of peaks correspond-
ing to the [MH]+ ions with the expected isotopic pattern.
As for reactivity of complex 1a with the aforementioned diphos-
phines, although the IR data seemed similar to that of the b and c
derivatives, the products were to insoluble for NMR characteriza-
tion and their mass spectra did not show the expected peaks for
the molecular ions; thus, their isolation was not pursued further.
3. Experimental
3.1. General procedures
Solvents were purified by standard methods [35]. Chemicals
were reagent grade. The phosphines PPh3, Ph2P(CH@CH)PPh2
(trans-dppe), Ph2P(CH2)4PPh2 (dppb) and Ph2PC5H4FeC5H4PPh2
(dppf) were purchased from Aldrich-Chemie. Microanalyses were
carried out using a Carlo Erba Elemental Analyzer, Model 1108.
IR spectra were recorded as KBr discs on a Perkin–Elmer 1330.
NMR spectra were obtained as CDCl3 and CD3SOCD3 solutions
and referenced to SiMe4 (1H) or 85% H3PO4 (31P–{1H}) and were re-
corded on a BRUKER AV-300F or BRUKER AC-500F 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.
N
N
N
15
14
17
18
4. Syntheses
5
6
3
2
i
ii
PPh3
4.1. Preparation of 4-(NC5H4)C6H4C(H)@N[2-(OH)C6H4] (a)
Pd
Pd
O
N
N
O
N
OH
4-(NC5H4)C6H4COH (0.508 g, 2.77 mmol) was added to a solution
of 2-aminophenol (0.305 g, 2.79 mmol) in 50 cm3 of dry chloroform.
The solution was heated under reflux in a Dean-Stark apparatus for
8 h. After cooling to room temperature the chloroform was removed
to give a yellow solid. Yield 99%. Anal. calc. C18H14N2O requires C,
8
9
11
10
a
4
2a
1a
78.8; H, 5.1; N, 10.2. Found: C, 78.9; H, 5.1; N, 10.1%. IR:
m(O–H),
3415sh cmꢀ1 (C@N), 1600s, m cmꢀ1. RMN 1H (300 MHz, CDCl3, d
;
m
Scheme 1. (i) Pd(OAc)2, toluene; (ii) PPh3 (chloroform, 4:1 molar ratio).

J.J. Fernández et al. / Polyhedron 28 (2009) 2679–2683
2681
16
N
N
18
14
5
6
3
2
N
OH
b,
R=H
c , R=tBu
8
11
10
9
i
R
N
N
N
N
R
N
N
N
O
P
ii
iii
Ph2
P
PPh3
O
Pd
Pd
Pd
Pd
N
R
N
R
O
Ph2
O
N
R
N
N
4
1b, 1c
2b, 2c
3b, 3c
v
iv
R
tBu
N
N
N
N
N
O
N
O
N
Pd
Ph2
P
Ph
P2
Pd
Fe
P
Ph
2
Pd
P
Pd
Ph2
O
O
N
R
N
N
N
N
tBu
4b, 4c
5c
Scheme 2. (i) Pd(OAc)2 (toluene); (ii) PPh3 (chloroform, 2b, acetone, 2c, 4:1 molar ratio); (iii) dppb (acetone, 3b, chloroform, 3c, 2:1 molar ratio); (iv) dppf (chloroform 4b,
acetone, 4c, 2:1 molar ratio); (v) t-dppe, (acetone, 2:1 molar ratio).
ppm, J Hz): d = 8.77 [s, 1H, HC@N); 8.72 (d, 2H, H15,H17,
3J(H14H15) = 6.1 Hz]; 8,68 (s, br, 1H, –OH/ resonance taken from a
spectrum recorded in DMSO-d6); 8.05 [d, 2H, H2,H6 ó H3,H5,
3J(H2H3) = 8.3 Hz]; 7.77 [d, 2H, H3,H5 or H2,H6, 3J(H2H3) = 8.3 Hz];
7,57 [d, 2H, H14, H18, 3J(H14H15) = 6.1 Hz]; 7.35 [dd, 1H, H8,
3J(H8H9) = 8.2 Hz, 4J(H8H10) = 1.4 Hz], 7.26 [m, 1H, H10,
3J(H9H10) = 3J(H10H11) = 8.2 Hz; 4J(H8H10) = 1.4 Hz]; 7,04 [dd,
1H, H11, 3J(H10H11) = 8.2 Hz, 4J(H9H11) = 1.3 Hz]; 6.94 [m, 1H,
H9, 3J(H8H9) = 3J(H9H10) = 8.2 Hz, 4J(H9H11) = 1.3 Hz].
3,5-(N2C4H3)C6H4C(H)@N[20-(OH)-50-tBuC6H3] (c). Yield 80%.
Anal. calc. C21H21N3O requires C, 76.1; H, 6.4; N, 12.7. Found: C,
76.2; H, 6.5; N, 12.7%. IR:
m ; m(C@N),
(O–H), 3226sh, m cmꢀ1
1622m cmꢀ1. RMN 1H (300 MHz, CDCl3, d ppm, J Hz): d = 9.25 (s,
1H, H16); 9.01 (s, 2H, H14, H18); 8.89 (s, br 1H, –OH/resonance ta-
ken from a spectrum recorded in DMSO-d6); 8.76 (s, 1H, HC@N);
8.07 [d, 2H, H3, H5 or H2, H6, 3J(H2H3) = 8.3 Hz]; 7.70 [d, H3,H5
or H2, H6, 3J(H2H3) = 8.3 Hz]; 7.34 [d, 1H, H8, 4J(H8H10) = 2.2 Hz];
7.27 [dd, 1H, H10, 3J(H10H11) = 8.5 Hz, 4J(H8H10) = 2,2 Hz]; 6.97
t
Ligands b and c were prepared similarly as yellow solids.
[d, 1H, H11, 3J(H10H11) = 8.5 Hz], 1.35 (s, 9H, Bu).
3,5-(N2C4H3)C6H4C(H)@N[20-(OH)-C6H4](b). Yield 95%. Analc.alc.
C17H13N3O requires C, 74.2; H, 4.8; N, 15.3. Found: C, 74.2; H, 4.9;
4.2. Preparation of [Pd{4-(NC5H4)C6H3C(H)@N[2-(O)C6H4]}]4 (1a)
N, 15.4%. IR: m ; m
(O–H), 3336s cmꢀ1 (C@N), 1621s cmꢀ1. RMN 1H
(300 MHz, CDCl3, d ppm, J Hz): d = 9.26 (s, 1H, H16); 9.08 (s, br
1H, –OH/ resonance taken from a spectrum recorded in DMSO-
d6); 9.02 (s, 2H, H14, H18); 8.77 (s, 1H, HC@N); 8.08 [d, 2H, H3,
H5 or H2, H6, 3J(H2H3) = 8.2 Hz]; 7.72 [d, 2H, H3, H5 or H2,
H6, 3J(H2H3) = 8.2 Hz]; 7.35 [dd, 1H, H8, 3J(H8H9) = 7.8 Hz,
4J(H8H10) = 1.4 Hz]; 7.23 [m, 1H, H10, 3J(H9H10) = 3J(H10H11) =
7.8 Hz, 4J(H8H10) = 1,4 Hz]; 7.05 [dd, 1H, H11, 4J(H8H10) = 7.8 Hz,
4J(H9H11) = 1.2 Hz]; 6.94 [m, 1H, H9, 3J(H8H9) = 3J(H9H10) =
7.8 Hz, 4J(H9H11) = 1.2 Hz].
A
pressure tube containing 4-(NC5H4)C6H4C(H)@N[20-
(OH)C6H4] (0.125 g, 0.456 mmol), palladium acetate (0.101 g,
0.452 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 room temperature the resulting violet solid was
filtered off and dried under vacuum. Yield 26%. Anal.
calc.
C72H48N8O4Pd4 requires C, 57.1; H, 3.2; N, 7.4. Found: C, 57.0;
H, 3.1; N, 7.3%. IR:
1136.1 [(3/4M)H]+.
m . FAB-MS: m/z =
(C@N), 1579sh, cmꢀ1

2682
J.J. Fernández et al. / Polyhedron 28 (2009) 2679–2683
Compounds 1b and 1c were prepared similarly as violets solids.
6.34 [m, 2H, H9, H11]; 6.29 [m, 1H, H5, 4J(PH5) = 3.5 Hz,
4J(H3H5) = 1.6 Hz]. 31P–{1H} NMR (121.49 MHz, CDCl3, d ppm)
30.22s. FAB-MS: m/z = 1186.1 [MH]+.
[Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-C6H4]}]4 (1b).Yield 43%.
Anal. calc. C68H44N12O4Pd4 requires C, 53.8; H, 2.9; N, 11.1. Found:
C, 53.7; H, 2.7; N, 11.2%. IR:
m
(C@N), 1590s cmꢀ1. FAB-MS: m/z =
Compounds 3c, 4b, 4c and 5c were obtained as violet solids fol-
lowing a similar procedure to the one described for 3b but using
the appropriate phosphine.
760.0 [(M/2)H]+.
[Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-50-tBuC6H3]}]4 (1c) Yield
21%. Anal. calc. C84H76N12O4Pd4 requires C, 57.9; H, 4.4; N, 9.6.
[{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-(O)-50-tBuC6H3}]}2(
l-
Found: C, 57.8; H, 4.5; N, 9.7%. IR:
m
(C@N), 1580m cmꢀ1. FAB-MS:
Ph2P(CH2)4PPh2)] (3c). Yield 47%. Anal. calc. C70H66N6O2P2Pd2 re-
quires C, 64.8; H, 5.1; N, 6.5. Found: C, 64.6; H, 5.3; N, 6.4%. IR:
m/z = 1741.2 [M]+; 871.3 [(M/2)H]+.
m
(C@N), 1578m cmꢀ1 1H NMR (300 MHz, CDCl3): d = 9.01(s, 1H,
.
4.3. Preparation of [Pd{4-(NC5H4)C6H3C(H)@N[2-(O)C6H4]}(PPh3)]
(2a)
H16); 8.15 (s, 2H, H14, H18); 7.91 [d, 1H, HC@N, 4J(PH) = 10.1 Hz];
7.18 [d, 1H, H2, 3J(H2H3) = 7.7 Hz]; 7.05 [d, 1H, H8,
4J(H8H10) = 2.3 Hz]; 7.00 [dd, 1H, H3, 3J(H2H3) = 7.7 Hz,
4J(H3H5) = 1.8 Hz]; 6.98 [dd, 1H, H10, 3J(H10H11) = 8.8 Hz,
4J(H8H10) = 2.3 Hz]; 6.33 [d, 1H, H11, 3J(H10H11) = 8.8 Hz]; 6.27
PPh3 (16 mg, 0.015 mmol) was added to a suspension of 1a
(24 mg, 0.016 mmol) in chloroform (20 cm3). The mixture was stir-
red for 72 h and the solvent removed to give a violet solid which
was recrystallized from dichloromethane/hexane. Yield 68%. Anal.
calc. C36H27N2OPPd requires C, 67.5; H, 4.3; N, 4.4. Found: C, 67.6;
[dd, 1H, H5, 4J(PH5) = 3.7 Hz, 4J(H3H5) = 1.8 Hz]; 1.28 (s, 9H, Bu).
t
31P–{1H} NMR (121.49 MHz, CDCl3,
d
ppm) 30.33s. FAB-MS:
m/z = 1298.2 [MH]+.
H, 4.3; N, 4.5%. IR:
m
(C@N), 1537sh cmꢀ1. 1H NMR (300 MHz, CDCl3):
[{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-(O)C6H4}]}2(
l
-Ph2P(g5
-
d = 8.38 [d, 2H, H15,H17, 3J(H14H15) = 5.9 Hz]; 7.98 [d, 1H, HC@N,
4J(PH) = 10.1 Hz], 7.22 [d,1H, H2, 3J(H2H3) = 7.7 Hz]; 7.12 [dd, 1H,
H8, 3J(H8H9) = 8.0 Hz, 4J(H8H10) = 1.5 Hz]; 7.10 [dd, 1H, H3, 3J
(H2H3) = 7.7 Hz, 4J(H3H5) = 1.7 Hz]; 6.97 [m, 1H, H10,
3J(H10H11) = 8.5 Hz, 3J(H9H10) = 7.1 Hz, 4J(H8H10) = 1.5 Hz]; 6.65
[d, 2H, H14, H18, 3J(H14H15) = 5.9 Hz]; 6.54 [dd, 1H, H11, 3J
(H10H11) = 8.5 Hz, 4J(H9H11) = 1,0 Hz]; 6.42 [dd, 1H, H5,
4J(PH5) = 3.8 Hz, 4J(H3H5) = 1.7 Hz]; 6.37 (t, 1H, H9). 31P–{1H}
NMR (121.49 MHz, CDCl3, d ppm) 34.60s. FAB-MS: m/z = 640.1 [M]+.
Compounds 2b and 2c were prepared as violets solids following
a similar procedure to that used for 2a, but using reaction times of
24 h and acetone as solvent in the case of 2c.
C5H4)Fe(
FePd2 requires C, 62.2; H, 3.8; N, 6.4. Found: C, 62.4; H, 3.9; N,
6.5%. IR:
(C@N), 1582s cmꢀ1 1H NMR (300 MHz, CDCl3): d = 9.02
g
5-C5H4)PPh2)] (4b). Yield 65%. Anal. calc. C68H50N6O2P2-
m
.
(s, 1H, H16); 8.07 (s, 2H, H14, H18); 7.91 [d, 1H, HC@N,
4J(PH) = 10.4 Hz]; 7.22 [d, 1H, H2, 3J(H2H3) = 7.7 Hz]; 7.09-7.03
(m, 2H, H3, H8); 6.95 (m, 1H, H10); 6.56 (d, 1H, H11); 6.32 (t,
1H, H9); 6.21 [m, 1H, H5, 4J(PH5) = 3.8 Hz, 4J(H3H5) = 1.4 Hz].
31P–{1H} NMR (121.49 MHz, CDCl3,
d ppm) 24.56s. FAB-MS:
m/z = 1314.1 [MH]+.
[{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-(O)-50-tBuC6H3}]}2(
l-
Ph2P(
C76H66N6O2P2FePd2 requires C, 64.0; H, 4.7; N, 5.9. Found: C,
64.2; H, 4.5; N, 5.8%. IR:
(C@N), 1584m cmꢀ1 1H NMR
g
5C5H4)Fe(
g
5C5H4)-PPh2)] (4c). Yield 69%. Anal.
calc.
[Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)C6H4]}(PPh3)] (2b). Yield
71%. Anal.calc. C35H26N3OPPd requires C, 65.5; H, 4.1; N, 6.5. Found:
m
.
(300 MHz, CDCl3): d = 9,01 (s, 1H, H16); 8.07 (s, 2H, H14, H18);
7.94 [d, 1H, HC@N, 4J(PH) = 10,5 Hz]; 7.22 [d, 1H, H2,
3J(H2H3) = 7.8 Hz]; 7.06–7.01 [m, 3H, H3, H8, H10); 6.50 (d, 1H,
H11, 3J(H10H11) = 8.6 Hz]; 6.19 [m, 1H, H5, 4J(PH5) = 3.8 Hz,
4J(H3H5) = 1.6 Hz]; (CH)ferrocene = 5.19–4.32 (m, 4H); 1.28 (s, 9H,
tBu). 31P–{1H} NMR (121.49 MHz, CDCl3, d ppm) 24.67s. FAB-MS:
m/z = 1426.2 [MH]+.
C, 65.6; H, 4.3; N, 6.4%. IR: m
(C@N), 1583m cmꢀ1. 1H NMR (300 MHz,
CDCl3): d = 9.03 (s, 1H, H16); 8.13 (s, 2H, H14, H18); 7.98 [d, 1H,
HC@N, 4J(PH) = 10 Hz]; 7.24 [d, 1H, H2, 3J(H2H3) = 7.7 Hz], 7.12
[dd, 1H, H8, 3J(H8H9) = 8.0 Hz, 4J(H8H10) = 1.4 Hz]; 7.05 [dd, 1H,
H3, 3J(H2H3) = 7.7 Hz, 4J(H3H5) = 1.7 Hz]; 6.97 [m, 1H, H10,
3J(H10H11) = 8.3 Hz, 3J(H9H10) = 8 Hz, 4J(H8H10) = 1.4 Hz]; 6.54
[dd, 1H, H11, 3J(H10H11) = 8.3 Hz, 4J(H9H11) = 0.9 Hz]; 6.38 [t, 1H,
H9, 3J(H8H9) = 3J(H9H10) = 8 Hz, 4J(H9H11) = 0.9 Hz]; 6.28 [dd, 1H,
H5, 4J(PH5) = 3.7 Hz, 4J(H3H5) = 1.7 Hz]. 31P–{1H} NMR (121.49
MHz, CDCl3, d ppm) 34.46s. FAB-MS: m/z = 641.1 [M]+.
[{Pd[3,5-(N2C4H3)C6H3C(H)@N{20-(O)-50-tBuC6H3}]}2(
l-
Ph2P(CH=CH)PPh2)] (5c). Yield 89%. Anal.calc. C68H62N6O2P2Pd2 re-
quires C, 64.3; H, 4.9; N, 6.6. Found: C, 64.3; H, 4.8; N, 6.7%. IR:
m
(C@N), 1579m cmꢀ1 1H NMR (300 MHz, CDCl3): d = 9.00 (s, 1H,
.
[Pd{3,5-(N2C4H3)C6H3C(H)@N[20-(O)-50-tBuC6H3)}(PPh3)] (2c).
Yield 67%. Anal. calc. C39H34N3OPPd requires C, 67.1; H, 4.9; N,
H16); 8.14 (s, 2H, H14, H18); 7.92 [d, 1H, HC@N, 4J(PH) = 10,1 Hz];
7.19 [d, 1H, H2, 3J(H2H3) = 7.8 Hz]; 7.08 [d, 1H, H8,
4J(H8H10) = 2.3 Hz], 7.05–7.00 (m, 2H, H3, H10); 6.41 [d, 1H,
H11, 3J(H10H11) = 9.4 Hz]; 6.22 (m, 1H, H5); 1.29 (s, 9H, tBu)
ppm. 31P–{1H} NMR (121.49 MHz, CDCl3, d ppm) 30.96s. FAB-MS:
m/z = 1268.2 [MH]+.
6.0. Found: C, 67.2; H, 4.8; N, 6.1%. IR: m .
(C@N), 1580m cmꢀ1 1H
NMR (300 MHz, CDCl3): d = 9.02 (s, 1H, H16); 8.14 (s, 2H, H14,
H18); 7.98 [d, 1H, HC@N, 4J(PH) = 10.2 Hz], 7.23 [d, 1H, H2,
3J(H2H3) = 7.7 Hz]; 7.07–7.02 (m, 3H, H3, H8, H10); 6.48 [d, 1H,
H11, 3J(H10H11) = 8,6 Hz]; 6.25 [dd, 1H, H5, 4J(PH5) = 3.7 Hz,
t
4J(H3H5) = 1.7 Hz]; 1.27 (s, 9H, Bu). 31P–{1H} NMR (121.49 MHz,
Acknowledgments
CDCl3, d ppm) 34.46s. FAB-MS: m/z = 697.2 [M]+.
We thank the Ministerio de Ciencia e Innovación (Projects
CTQ2006-15621-C02-02/BQU, CTQ2006-15621-C02-01/BQU), the
Xunta de Galicia and the Universidad de la Coruña for financial
support.
4.4. Preparation of [{Pd[3,5-(N2C4H3)C6H3C(H)@N{2-(O)C6H4}]}2(l-
Ph2P(CH2)4PPh2)] (3b)
Ph2P(CH2)4PPh2 (11.3 mg, 0.013 mmol) was added to a suspen-
sion of 1b (21.0 mg, 0.014 mmol) in acetone (20 cm3). The mixture
was stirred for 72 h and the solvent removed to give a violet solid
which was recrystallized from acetone/hexane. Yield 65%. Analc. alc.
C62H50N6O2P2Pd2 requires C, 62.8; H, 4.2; N, 7.1. Found: C, 62.9; H,
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