Synthesis and crystal structure analysis of ferrocenylthiosemicarbazone complexes of palladium(II): Unusual σpd-C bond cleavage

Article abstract of DOI:10.1016/j.poly.2005.10.003

The reaction of the thiosemicarbazones (η⁵-C ₅H₅)Fe(η⁵-C₅H ₄)C(H)NN(H)C(S)NHR (R = H, a; R = Me, b) with K₂PdCl ₄ afforded octanuclear cyclometallated complexes [Pd{(η ⁵-C₅H₅)Fe(η⁵-C₅H ₃)C(H)NNC(S)NHR}]₄ (R = H, 1a; R = Me, 1b). Reaction of complexes 1a and 1b with tertiary diphosphines in 1:2 molar ratio and subsequent recrystallization from CH₂Cl₂/n-C₆H ₁₄ gave rise to tetranuclear complexes [{Pd[(η⁵-C ₅H₅)Fe(η⁵-C₅H ₄)C(H)NNC(S)NHR](Cl)}₂(μ-Ph₂P(CH ₂)_nPPh₂)] (R = H, n = 4, 2a; R = Me, n = 1, 2b; n = 4, 3b). Treatment of complexes 1a and 1b with tertiary monophosphines in 1:4 molar ratio and subsequent recrystallization from CH₂Cl ₂/n-C₆H₁₄ gave rise to dinuclear complexes [Pd{(η⁵-C₅H₅)Fe(η⁵-C ₅H₄)C(H)NNC(S)-NHR}(Cl)(P)] (R = H: P = PPh₃, 3a; P = PPh₂Et, 4a; P = P(C₆D₅)₃, 5a; R = Me: P = PPh₃, 4b; P = PPh₂Et, 5b; P = P(C ₆D₅)₃, 6b). The crystal structures of 2a and 2b have been determined by X-ray crystallography.

Full text of DOI:10.1016/j.poly.2005.10.003

Polyhedron 25 (2006) 1449–1456
www.elsevier.com/locate/poly
Synthesis and crystal structure analysis of
ferrocenylthiosemicarbazone complexes of palladium(II):
Unusual rPd–C bond cleavage
a
a
a
a
´
Marta Marino , Eduardo Gayoso , Jose M. Antelo , Luis A. Adrio ,
˜
b
a,
*
´
´
Jesu´s J. Fernandez , Jose M. Vila
a
Departamento de Quı´mica Inorga´nica, Universidad de Santiago de Compostela, Avenida de las Ciencias s/n, E-15782 Santiago de Compostela, Spain
b
Departamento de Quı´mica Fundamental, Universidad de La Corun˜a, E-15071 La Corun˜a, Spain
Received 16 September 2005; accepted 11 October 2005
Available online 22 November 2005
Abstract
The reaction of the thiosemicarbazones (g5-C5H5)Fe(g5-C5H4)C(H)@NN(H)C(@S)NHR (R = H, a; R = Me, b) with K2PdCl4 affor-
ded octanuclear cyclometallated complexes [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)NHR}]4 (R = H, 1a; R = Me, 1b). Reaction of
complexes 1a and 1b with tertiary diphosphines in 1:2 molar ratio and subsequent recrystallization from CH2Cl2/n-C6H14 gave rise to
tetranuclear complexes [{Pd[(g5-C5H5)Fe(g5-C5H4)C(H)@NN@C(S)NHR](Cl)}2(l-Ph2P(CH2)nPPh2)] (R = H, n = 4, 2a; R = Me,
n = 1, 2b; n = 4, 3b). Treatment of complexes 1a and 1b with tertiary monophosphines in 1:4 molar ratio and subsequent recrystallization
from CH2Cl2/n-C6H14 gave rise to dinuclear complexes [Pd{(g5-C5H5)Fe(g5-C5H4)C(H)@NN@C(S)–NHR}(Cl)(P)] (R = H: P = PPh3,
3a; P = PPh2Et, 4a; P = P(C6D5)3, 5a; R = Me: P = PPh3, 4b; P = PPh2Et, 5b; P = P(C6D5)3, 6b). The crystal structures of 2a and 2b
have been determined by X-ray crystallography.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Palladium; Cyclometallation; Phosphines; Thiosemicarbazones; Crystal structure
1. Introduction
bone of the molecule, or a substituent in ancillary ligands,
and also due to the unique geometries and electronic prop-
erties that ferrocene provides [9]. One of the developments
in this area over the past two decades is the cyclometalla-
tion of ferrocene derivatives, which usually results in the
formation of planar chiral cyclometallated metallocenes;
the resulting products distinguish the reaction from the
cyclometallation of other ligands, and they exhibit great
potential use in asymmetric synthesis. The most common
ligands are by far [C,N] bidentate ligands [10], and their
application as highly active catalysts for the Heck reaction
[11] and for asymmetric intramolecular aminopalladation
[12] has been established, as well as being auxiliary reagents
for chiral recognition or discrimination [13].
Cyclometallated complexes [1] have generated a great
interest in the past mainly due to their applications as pre-
cursors of new organometallic and organic compounds [2],
their use in homogeneous catalysis [3] as chiral recognition
agents [4], or their promising photochemical [5] and lumi-
nescent properties [6].
The synthesis, isolation and characterization of ferro-
cene marked an imported point in the evolution of modern
organometallic chemistry [7] and a half century later,
research into ferrocene-containing compounds, and of a
great deal of analogous sandwiched compounds with tran-
sition metals other than iron, is quickly growing [8], owing
to the role the ferrocene moiety plays, itself being the back-
More recently a great effort has been made in order to
extend the work in this area to the isolation and
characterization of similar complexes derived from terden-
tate [C,N,X] ligands. Thus, palladacycles derived from
*
Corresponding author. Tel.: +34 981 52800; fax: +34 981 595012.
E-mail address: qideport@usc.es (J.M. Vila).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.10.003

1450
M. Marin˜o et al. / Polyhedron 25 (2006) 1449–1456
[C(sp2/aryl or sp3),N,X] terdentate ligands are well known
and many examples have been reported with X = N [14], S
[15], O [16], mainly due to the potential hemilability of the
Pd–X bond in these systems, which plays an important
role in homogeneous catalysis. Nevertheless all the exam-
ples reported for those complexes containing terdentate
[C(sp2/ferrocene),N,X] ligands are scarce, and to the best
of our knowledge only compounds with X = N [17] and S
[17b,17d,18] have been described, and recently ferrocene-
based pincer complexes of palladium have been reported,
bearing a terdentate [P,C,P] ligand [19]. Ferrocene-based
cyclometallated complexes with [C,N,S] ligands are mainly
with thioethers, and the unique examples derived from thi-
osemicarbazones have been recently reported by us [20]. As
a continuation of our studies related to ferrocenylthiosemic-
arbazone ligands, herein we report the synthesis and charac-
terization of new polynuclear organometallic and
coordination compounds, the latter being generated after
unusual rPd–C bond cleavage in the starting material.
3
4
2
5
CpFe
Pd
CpFe
i
N
S
NHR
N
N
NHR
HN
4
S
1a, 1b
a: R = H
b: R = Me
ii
iii
N
N
NHR
Pd
S
Cl
CpFe
N
PPh2
N
NHR
Pd
S
Cl
CpFe
Ph2P
Pd
P
FeCp
Cl
S
2. Results and discussion
3a-5a
4b-6b
N
RHN
N
2a
2b, 3b
2.1. Synthesis and characterization
The thiosemicarbazones (g5-C5H5)Fe(g5-C5H4)C(H)@
NN(H)C(@S)NHR (R = H, a; R = Me, b) were obtained
by reaction of ferrocenecarboxaldehyde with thiosemicar-
bazide or with 4-methylthiosemicarbazide, respectively, in
H2O in the presence of HCl at room temperature. The
NH2 protons gave rise to two characteristic resonances at
Scheme 1. (i) K2PdCl4, ethanol/water; (ii) Ph2P(CH2)nPPh2 (n = 1, 2b;
n = 4, 2a, 3b) 1:2 molar ratio, acetone, CH2Cl2/hexane; (iii) P(PPh3, 3a, 4b;
PPh2Et, 4a, 5b; P(C6D5)3, 5a, 6b) 1:4 molar ratio, acetone, CH2Cl2/hexane.
1
The absence of the signal for the NH group in the H
NMR spectra was in agreement with deprotonation [22].
The NH2 (1a) and NHMe (1b) resonances appeared as a
singlet (5.34 ppm) and a broad signal (5.37 ppm), respec-
tively, shifted to lower frequency with respect to the spectra
of the free ligands. Metallation of the ligand was clear from
the absence of the AA0XX0system of the C5H4 ring; three
proton resonances were assigned to the new C5H3 ring
(see Section 4). In the IR spectra, the presence of the
m(N–H) band ca. 3420 cmꢀ1 indicated the NHR group
was not coordinated, and absence of the m(N–H) band
for the NNH group confirmed deprotonation of the latter
[23]. The m(C@N) band was shifted to lower wavenumbers
upon complex formation [24] in an opposite trend to that
observed in other thiosemicarbazones complexes [23],
which can be attributed to the C,N moiety being part of
the five-membered metallacycle [25]. The band assigned
to the m(C@S) stretching vibration ca. 870 cmꢀ1 in the free
ligands disappeared in the spectra of the complexes, in
accordance with loss of the C@S double bond character
upon deprotonation of the NH group.
1
6.33 and 7.10 ppm in the H NMR spectrum of ligand a
which were attributed to the restricted rotation of the NH2
group about the C(@S)NH2 axis. The NH protons showed
resonances at 9.79 (a), 7.34 (NHMe, b) and 9.41 ppm
(NH, b). A singlet ca. 7.80 ppm was assigned to the HC@N
proton, and two apparent triplets ca. 4.50 ppm were
ascribed to the H2/H5 and H3/H4 protons of the substi-
tuted ferrocenyl ring, as a simplification of the expected 20
lines of the theoretical spectrum for an AA0XX0 spin system.
The C5H5 resonance appeared as a singlet at 4.20 ppm. The
resulting new complexes derived from a and b are shown in
Scheme 1. Preparative details, characterising microanalyti-
cal, IR, 1H and 31P–{1H} NMR data are in Section 4.
Thus, treatment of a suspension of K2PdCl4 in EtOH/
H2O with the corresponding thiosemicarbazone afforded
the cyclometallated complexes [Pd{(g5-C5H5)Fe(g5-
C5H3)C(H)@NN@C(S)NHR}]4 (R = H, 1a; R = Me, 1b),
with the ligand in the E/Z configuration for which an octa-
nuclear structure is proposed following the trend for these
and other related compounds of tridentate [C,N,S] ligands
[21]; the FAB mass spectra of 1a and 1b showed clusters of
peaks, centred at 1566 and 1622 amu, which correspond to
[M]+, supporting the proposed formulation. The sulfur
atom of each cyclometallated moiety displaying two
different coordination modes: chelating, as part of the
PdNNC(NHR)S coordination ring, and bridging, linking
two cyclometallated moieties through the metal atoms.
Treatment of complexes 1a and 1b with tertiary
diphosphines (1:2 molar ratio) or monophosphines (1:4
molar ratio) in acetone at room temperature and ulterior
recrystallization from CH2Cl2/n-C6H14 gave rise to tetra-
nuclear or dinuclear complexes, respectively, with loss of
the metallated ring upon cleavage of the rPd–C bond,
as opposed to the case of similar complexes with ferroce-
nylthiosemicarbazones obtained by us earlier [21b], where

M. Marin˜o et al. / Polyhedron 25 (2006) 1449–1456
1451
Fig. 1. Molecular structure of [{Pd[(g5-C5H5)Fe(g5-C5H4)C(H)@NN@C(S)NH2](Cl)}2{l-Ph2P(CH2)4PPh2}] (2a), with labelling scheme. Hydrogen
atoms have been omitted for clarity.
1
the metal–carbon bond was retained. These results,
together with our most recent findings1, allow us to antic-
ipate possible reasons for the behaviour of these com-
plexes: (a) the absence of the MeC@N methyl group in
the present complexes seems to favour demetallation of
the cyclopentadienyl ring; (b) under the reaction condi-
tions employed the source of chlorine should be either
dichloromethane, which would put forward the non-spec-
tator character of this solvent, or possibly traces of acid in
the solvent; (c) it is also noteworthy to point out that the
latter could account for the proton source and act as
catalyst in the process [26]. Thus, reaction of 1a and 1b
with tertiary diphosphines (Ph2PCH2PPh2, Ph2P(CH2)4-
PPh2, 1:2 molar ratio) or with tertiary monophosphines
(PPh3, PPh2Et, P(C6D5)3, 1:4 molar ratio) gave the tetra-
nuclear complexes [{Pd[(g5-C5H5)Fe(g5-C5H4)C(H)@NN@
C(S)NHR]-(Cl)}2(l-PP)] (2a, 3b: PP = Ph2P(CH2)4PPh2;
2b, PP = Ph2PCH2PPh2; see Scheme 1) and the dinuclear
complexes [Pd{(g5-C5H5)Fe(g5-C5H4)C(H)@NN@C(S)-
NHR}(Cl)(P)] (3a, 4b: P = PPh3; 4a, 5b: P = PPh2Et; 5a,
6b, P = P(C6D5)3; see Scheme 1), respectively; with the
diphosphine acting as a bridging ligand between the two
palladium atoms in the former case. In the IR spectra,
the absence of the m(C@S) stretching vibration and of
the m(N–H) band for the NNH group, as well as the shift
to lower wavenumbers of the m(C@N) band was in accor-
dance with [N,S] coordination of the deprotonated ferr-
ocenylthiosemicarbazone ligands to the palladium atom.
A band ca. 310 cmꢀ1 was assigned to the m(Pd–Cl) vibra-
tion, in accordance with the now present terminal Pd–Cl
bonding. In the H NMR spectra, two apparent triplets
assigned to the H2/H5 and H3/H4 protons (AA0XX0 sys-
tem) confirmed the regeneration of the substituted ferro-
cene ring, whilst absence of the –NH resonance
suggested the hydrazynic nitrogen atom remained depro-
tonated. The HC@N resonance ca. d 8.30 ppm appeared
as a doublet due to coupling with the 31P nucleus
[4J(PHi) ca. 4.0 Hz], thereby indicating a phosphorus
trans to nitrogen geometry, within the terms of the ‘‘trans-
phobic effect’’ [27]; in the case of complexes 2a, 2b, 3b, the
1H NMR spectra showed only one set of signals putting
forward the symmetric nature of these complexes. The
31P–{1H} NMR spectra showed a singlet, shifted to
higher frequency from the spectrum of the free phosphine,
in agreement with phosphorus coordination to metal cen-
ter; for complexes 2a, 2b, 3b, this showed that the two
phosphorus nuclei were equivalent [28] as might be
1
expected from the H NMR data (vide supra).
2.2. Molecular structures of compounds 2a and 2b
Suitable crystals of 2a and 2b were grown by slowly
evaporating CH2Cl2/n-C6H14 solutions. The molecular
structure of each neutral compound with the numbering
scheme is illustrated in Figs. 1 and 2, respectively. Selected
bond lengths and angles are listed in Table 1. The struc-
tures consist in discrete molecules separated by van der
Waals distances (Table 2).
The crystal structures comprise a half molecule per
asymmetric unit, and exhibit C2 symmetry about the
PCH2CH2–CH2CH2P bond (2a) or the central PCH2P
group (2b). The four-coordinated palladium(II) atoms are
bonded to an iminic nitrogen atom and a thioamide sul-
phur atom of the deprotonated thiosemicarbazone ligand,
and to a chlorine atom (trans to S). A phosphorus atom
from the diphosphine ligand, which bridges the two palla-
dium atoms, completes the metal coordination sphere. The
sum of angles about palladium are 360.28ꢁ (2a) and 360.05ꢁ
1
Recently, we have found that related ligands with five-membered rings,
such as pyrrol, furane and thiophene thiosemicarbazones, are difficult to
metallate or they do not undergo cyclometallation at all when the imine
carbon, C@N, is bonded to hydrogen (for pyrrol derivatives see J.M. Vila
et al., Z. Anorg. Allg. Chem., 635 (2005) 2197); however, ligands with
alkyl substituted C@N groups readily undergo cyclometallation (A.
Amoedo, Ph.D. Dissertation, Universidad de Santiago de Compostela,
Santiago).

1452
M. Marin˜o et al. / Polyhedron 25 (2006) 1449–1456
(2b), with the distortion most noticeable in the somewhat
reduced ‘‘bite’’ angle of the thiosemicarbazone moiety con-
sequent upon chelation (83.37(15)ꢁ for 2a, 83.1(3)ꢁ for 2b).
The geometry around the palladium atom is slightly dis-
torted square-planar, the mean deviation from the least
squares plane (plane 1: Pd(1), N(1), S(1), P(1), Cl(1) are
0.0783 (2a) and 0.0731 (2b)). The metallated rings (plane
2: Pd(1), S(1), C(12), N(1), N(2), r.m.s. 0.0261 (2a),
0.0433 (2b)) are also planar and coplanar with the palla-
dium coordination plane (angles between planes: 1/2
3.83(0.12)ꢁ (2a), 4.56(0.10)ꢁ (2b)).
˚
The palladium–nitrogen bond lengths (2.107(5) A, 2a;
˚
2.079(9) A, 2b) are longer than the predicted single bond
˚
value of 2.011 A, based on the sum of covalent radii for
2
˚
nitrogen(sp ) and palladium, 0.701 and 1.31 A, respectively
[29] and reflects the trans influence of the phosphorus atom
Fig. 2. Molecular structure of [{Pd[(g5-C5H5)Fe(g5-C5H4)C(H)@NN@C(S)NHMe](Cl)}2(l-Ph2PCH2PPh2)] (2b), with labelling scheme. Hydrogen atoms
have been omitted for clarity.
Table 1
Crystal and structure refinement data
2a
2b
Formula
C52H52Cl2Fe2N6P2Pd2S2
C53H52Cl8Fe2N6P2Pd2S2
Formula weight
Temperature (K)
Wavelength (A)
1282.46
293(2)
0.71073
monoclinic
P2(1)/c
10.339(3)
17.785(5)
13.894(4)
90
93.389(5)
90
2550.4(12)
2
1.670
1.544
1507.17
293(2)
0.71073
monoclinic
P2/c
15.408(4)
8.750(2)
22.489(5)
90
94.400(5)
90
3023.0(12)
2
1.656
1.572
1508
˚
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V ( A )
Z
Dcalc (Mg/m3)
Absorption coefficient (mmꢀ1
F(000)
)
1292
0.34 · 0.29 · 0.09
1.86–26.43
Crystal size (mm3)
0.36 · 0.33 · 0.31
1.33–26.44
ꢀ14/19, ꢀ10/10, ꢀ28/28
16756
h Range for data collection (ꢁ)
Index ranges
Reflections collected
ꢀ5/2, ꢀ12/22, ꢀ17/16
13790
Independent reflections [Rint
Completeness to h = 26.43ꢁ
Absorption correction
Refinement method
]
5209 [0.0621]
99.3%
6147 [0.1091]
98.9%
SADABS
SADABS
full-matrix least-squares on F2
Data/restraints/parameters
Goodness-of-fit on F2
Transmissions
5209/0/307
0.955
0.870, 0.600
6147/0/339
0.881
0.6414, 0.6014
Final R indices [I > 2r(I)]
R indices (all data)
Largest difference in peak and hole (e A
R1 = 0.0457, wR2 = 0.0762
R1 = 0.1219, wR2 = 0.0883
0.748 and ꢀ0.502
R1 = 0.0550, wR2 = 0.1196
R1 = 0.2005, wR2 = 0.1851
0.635 and ꢀ0.686
ꢀ3
˚
)

M. Marin˜o et al. / Polyhedron 25 (2006) 1449–1456
1453
Table 2
further proof for our proposal, which shall be communi-
cated in the near future.
˚
Selected bond distances (A) and angles (ꢁ) for 2a and 2b
2a
Pd(1)–N(1)
Pd(1)–P(1)
S(1)–C(12)
N(2)–C(12)
N(1)–C(11)
P(1)–C(13)
2.107(5)
2.2543(16)
1.776(6)
1.280(7)
1.281(6)
1.825(6)
Pd(1)–S(1)
Pd(1)–Cl(1)
N(1)–N(2)
N(3)–C(12)
C(1)–C(11)
C(14)–C(13)
2.2436(17)
2.3397(16)
1.390(6)
1.344(7)
1.436(7)
1.518(7)
4. Experimental
Solvents were purified by standard methods [32], chem-
icals were reagent grade. Microanalyses were carried out at
the Servicio de Analisis Elemental at the University of San-
´
tiago using a Carlo Erba Elemental Analyzer, Model 1108.
IR spectra were recorded on a Perkin–Elmer 1330 and on a
Mattson spectrophotometer. NMR spectra were obtained
as CDCl3 solutions and referenced to SiMe4 (1H) or 85%
H3PO4 (31P–{1H}) and were recorded on Bruker WM250
and AMX-300 spectrometers (only selected data is pre-
sented for compounds containing phosphine). All chemical
shifts are reported downfield from standards. The FAB
mass spectra were recorded with a Fisons Quatro mass
spectrometer with a Cs ion gun; 3-nitrobenzyl alcohol
was used as the matrix.
N(1)–Pd(1)–S(1)
S(1)–Pd(1)–P(1)
S(1)–Pd(1)–Cl(1)
C(11)–N(1)–N(2)
N(2)–N(1)–Pd(1)
C(12)–S(1)–Pd(1)
83.37(15)
92.54(6)
173.41(6)
115.9(5)
119.9(4)
96.6(2)
N(1)–Pd(1)–P(1)
N(1)–Pd(1)–Cl(1)
P(1)–Pd(1)–Cl(1)
C(11)–N(1)–Pd(1)
C(12)–N(2)–N(1)
N(2)–C(12)–S(1)
175.04(14)
94.47(15)
89.90(6)
124.2(4)
113.3(5)
126.6(5)
2b
Pd(1)–N(1)
Pd(1)–P(1)
S(1)–C(12)
N(1)–N(2)
N(3)–C(12)
C(1)–C(11)
2.079(9)
2.257(3)
1.773(11)
1.401(10)
1.313(12)
1.425(13)
Pd(1)–S(1)
Pd(1)–Cl(1)
N(1)–C(11)
N(2)–C(12)
N(3)–C(13)
P(1)–C(26)
2.242(3)
2.350(3)
1.285(12)
1.296(13)
1.485(13)
1.815(7)
4.1. (g5-C5H5)Fe(g5-C5H4)C(H)@NN(H)C(@S)NH2 (a)
N(1)–Pd(1)–S(1)
S(1)–Pd(1)–P(1)
S(1)–Pd(1)–Cl(1)
C(12)–S(1)–Pd(1)
C(11)–N(1)–Pd(1)
C(12)–N(2)–N(1)
83.1(3)
94.89(11)
171.99(11)
97.3(4)
124.1(7)
112.5(9)
N(1)–Pd(1)–P(1)
N(1)–Pd(1)–Cl(1)
P(1)–Pd(1)–Cl(1)
C(11)–N(1)–N(2)
N(2)–N(1)–Pd(1)
N(2)–C(12)–S(1)
178.0(3)
94.2(3)
87.86(10)
114.5(9)
121.0(6)
125.6(8)
To a stirred suspension of thiosemicarbazide (0.213 g,
2.336 mmol) in water (40 cm3) a few drops of HCl 36%
and ferrocenecarboxaldehyde (0.5 g, 2.336 mmol) were
added. The resulting mixture was stirred for 4 h at r.t., fil-
tered off, washed with water and dried in vacuo to yield an
orange solid.
˚
[30,31]. The palladium–sulfur bond lengths, (2.2436(17) A,
Yield: 91.4%. Anal. Calc. for C12H13N3FeS: C, 50.2; H,
4.6; N, 14.7; S, 11.2. Found: C, 49.7; H, 4.4; N, 14.2; S,
11.1%. IR: m(N–H) 3431m, 3151w, m(C@N) 1592m,
˚
2a; 2.242(3) A, 2b) are shorter than the expected value of
˚
2.33 A (based on the sum of the covalent radii for sulfur
1
m(C@S) 876 cmꢀ1. H NMR (d ppm, J Hz): 4.20 (s, 5H,
˚
and palladium, 1.02 and 1.31 A, respectively). The Pd–P
bond distances, 2.2543(16) (2a) and 2.257(3) (2b) are
shorter than the sum of the single bond radii for palladium
and phosphorus (2.41 A), whilst the Pd–Cl bond lengths,
2.3397(16) (2a) and 2.350(3) A (2b), are slightly longer than
the sum of the covalent radii (2.30 A). The S–C and C–N
C5H5), 4.32 (t, 2H, H3/H4, N = 3.4), 4.58 (t, 2H, H2/H5,
N = 3.4), 6.33, 7.10 (s, 2H, NH2), 7.80 (s, 1H, HC@N),
9.79 (s, 1H, NH).
Ligand b was prepared as an orange air-stable solid
following a similar procedure.
˚
˚
˚
bond lengths in the chelate ring [S(1)–C(12), 1.776(6),
4.2. (g5-C5H5)Fe(g5-C5H4)C(H)@NN(H)C(@S)NHMe (b)
˚
N(2)–C(12), 1.280(7) A, 2a; S(2)–C(39), 1.773(11), N(5)–
˚
C(39), 1.296(13) A, 2b] are consistent with increased single
and double bond character, respectively.
Yield: 93.5%. Anal. Calc. for C13H15N3FeS: C, 51.8; H,
5.0; N, 14.0; S, 10.6. Found: C, 51.5; H, 5.0; N, 13.5; S,
10.1%. IR: m(N–H) 3430m, 3143w, m(C@N) 1609m,
3. Conclusions
1
m(C@S) 873 cmꢀ1. H NMR (d ppm, J Hz): 3.24 (d, 3H,
3
The results reported in the present paper show that ferr-
ocenyl thiosemicarbazones are readily metallated to give
the corresponding cyclopalladated octanuclear complexes.
However, reaction of the latter with tertiary mono- and
diphosphines yields products with cleavage of the Pd–C
bond, protonation of the cyclopentadienyl ring, and
Pd–Cl bond formation. These results, together with very
recent findings from our laboratory, allow us to point out
several factors responsible for this behaviour such as are
the absence of an alkyl group on the imine carbon atom,
the presence of traces of acid in CH2Cl2, and the not so
negligible reactivity of this solvent. We are currently under-
taking the research of related chemistry aimed at providing
NHMe, J(HMe) = 4.8 Hz), 4.20 (s, 5H, C5H5), 4.40 (at,
2H, H3/H4, N = 3.8), 4.57 (at, 2H, H2/H5, N = 3.8), 7.34
(b, 1H, NHMe), 7.69 (s, 1H, HC@N), 9.41 (s, 1H, NH).
4.3. [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)-
NH2}]4 (1a)
To a stirred solution of K2PdCl4 (200 mg, 0.613 mmol)
in EtOH (40 cm3) and H2O (6 cm3), (g5-C5H5)Fe(g5-
C5H4)C(H)@NN(H)C(@S)NH2 (a) (193 mg, 0.674 mmol)
were added. The mixture was stirred for 24 h at r.t. and
the resulting precipitate filtered off, washed with cold etha-
nol and dried in vacuo.

1454
M. Marin˜o et al. / Polyhedron 25 (2006) 1449–1456
1
Yield: 53.3%. Anal. Calc. for C48H44Fe4N12Pd4S4: C,
Cl) 323m cmꢀ1. H NMR (d ppm, J Hz): 2.97 (b, 3H,
NHMe), 4.23 (s, 5H, C5H5), 4.87 (t, 2H, H3/H4,
N = 3.8), 5.04 (t, 2H, H2/H5, N = 3.8), 5.48 (b, 1H,
NHMe), 8.33 (d, 1H, HC@N, 4J(PH) = 4.1). 31P–{1H}
NMR (d ppm) 23.7s.
36.8; H, 2.8; N, 10.7; S, 8.2. Found: C, 36.3; H, 2.8; N,
10.3; S, 8.3%. IR: m(N–H) 3428m, m(C@N) 1525w. 1H
NMR (d ppm, J Hz): 3.88 (b, 1H, H4), 4.06 (s, 5H,
C5H5), 4.23 (b, 1H, H3), 4.35 (b, 1H, H2), 5.34 (s, 2H,
NH2), 7.59 (s, 1H, HC@N).
Compound 1b was prepared as a red air-stable solid
following a similar procedure.
4.8. [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)NH2}-
(Cl)(PPh3)] (3a)
4.4. [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)-
NHMe}]4 (1b)
To a stirred solution of compound 1a (30 mg,
0.019 mmol) in acetone (15 cm3) triphenylphosphine
(20 mg, 0.077 mmol) was added. The mixture was stirred
for 24 h at r.t., filtered off, dried in vacuo and the orange
residue recrystallized from CH2Cl2/n-C6H14. Yield:
52.1%. Anal. Calc. for C30H27ClFeN3PPdS: C, 52.2; H,
3.9; N, 6.1; S, 4.6. Found: C, 52.0; H, 3.8; N, 6.4; S,
4.7%. IR: m(N–H) 3449m, m(C@N) 1533m, m(Pd–Cl)
Yield: 56.5%. Anal. Calc. for C52H52Fe4N12Pd4S4: C,
38.5; H, 3.2; N, 10.4; S, 7.9. Found: C, 38.1; H, 3.1; N,
10.5; S, 7.5%. IR: m(N–H) 3417m, m(C@N) 1601m. 1H
NMR (d ppm,
J
Hz): 2.95 (d, 3H, NHMe,
3J(HMe) = 4.8), 3.90 (d, 1H, H4, 3J(H3H4) = 1.2), 4.08
(s, 5H, C5H5), 4.33 (b, 1H, H3), 4.40 (b, 1H, H2), 5.37
(b, 1H, NHMe), 7.63 (s, 1H, HC@N).
304m cmꢀ1 1H NMR (d ppm, J Hz): 4.24 (s, 5H,
.
C5H5), 4.46 (t, 2H, H3/H4, N = 3.4), 4.96 (t, 2H, H2/H5,
N = 3.4), 4.63 (s, 2H, NH2), 8.41 (d, 1H, HC@N,
4J(PH) = 4.0). 31P–{1H} NMR (d ppm) 26.2s.
Compounds 4a, 5a and 4b–6b were prepared as air-
stable solids following a similar procedure.
4.5. [{Pd[(g5-C5H5)Fe(g5-C5H4)C(H)@NN@C(S)NH2]-
(Cl)}2{l-Ph2P(CH2)4PPh2}] (2a)
To
a stirred solution of compound 1a (30 mg,
0.018 mmol) in acetone (15 cm3) 1,4-bis(diphenylphosph-
ino)butane (dppb) (16 mg, 0.038 mmol) was added. The
mixture was stirred for 24 h at r.t., filtered off and the sol-
vent removed under reduced pressure. The red residue was
recrystallized from CH2Cl2/n-C6H14.
4.9. [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)NH2}-
(Cl)(PPh2Et)] (4a)
Yield: 56.9%. Anal. Calc. for C26H27ClFeN3PPdS: C,
48.6; H, 4.2; N; 6.5; S, 5.0. Found: C, 48.3; H, 4.1; N,
6.2; S, 4.9%. IR: m(N–H) 3437m, m(C@N) 1535m, m(Pd–
Yield: 66.9%. Anal. Calc. for C52H52Cl2Fe2N6P2Pd2S2:
C, 48.7; H, 4.1; N, 6.6; S, 5.0. Found: C, 48.5; H, 4.0; N,
6.2; S, 4.9%. IR: m(N–H) 3457m, m(C@N) 1533m, m(Pd–
Cl) 303m cmꢀ1 1H NMR (d ppm, J Hz): 4.22 (s, 5H,
.
C5H5), 4.45 (t, 2H, H3/H4, N = 3.4), 4.95 (t, 2H, H2/H5,
N = 3.4), 4.65 (s, 2H, NH2), 8.34 (d, 1H, HC@N,
4J(PH) = 4.2). 31P–{1H} NMR (d ppm) 26.5s.
Cl) 305m cmꢀ1 1H NMR (d ppm, J Hz): 4.22 (s, 5H,
.
C5H5), 4.45 (t, 2H, H3/H4, N = 3.4), 4.93 (t, 2H, H2/H5,
N = 3.4), 4.68 (s, 2H, NH2), 8.31 (d, 1H, HC@N,
4J(PH) = 4.2). 31P–{1H} NMR (d ppm) 19.1s.
Compounds 2b and 3b were prepared as red air-stable
solids following a similar procedure.
4.10. [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)NH2}-
(Cl){P(C6D5)3}] (5a)
Yield: 59.5%. Anal. Calc. for C30H12D15ClFeN3PPdS:
C, 51.1; H, 6.0; N, 6.0; S, 4.6. Found: C, 51.4; H, 5.9; N,
5.4; S, 4.9%. IR: m(N–H) 3445m, m(C@N) 1534m, m(Pd–
4.6. [{Pd[(g5-C5H5)Fe(g5-C5H4)C(H)@NN@C(S)-
NHMe](Cl)}2(l-Ph2PCH2PPh2)] (2b)
Cl) 302m cmꢀ1 1H NMR (d ppm, J Hz): 4.24 (s, 5H,
.
Yield: 61.7%. Anal. Calc. for C51H50Cl2Fe2N6P2Pd2S2:
C, 48.3; H, 4.0; N, 6.6; S, 5.1. Found: C, 48.0 H, 4.2; N,
6.8; S 4.9%. IR: m(N–H) 3440m, m(C@N) 1596m, m(Pd–
C5H5), 4.46 (t, 2H, H3/H4, N = 3.4), 4.96 (t, 2H, H2/H5,
N = 3.4), 4.69 (s, 2H, NH2), 8.41 (d, 1H, HC@N,
4J(PH) = 4.2). 31P–{1H} NMR (d ppm) 26.0s.
1
Cl) 302m cmꢀ1. H NMR (d ppm, J Hz): 2.94 (d, 3H,
3
NHMe, J(HMe) = 4.9), 4.14 (s, 5H, C5H5), 4.19 (t, 2H,
4.11. [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)NH-
Me}(Cl)(PPh3)] (4b)
H3/H4, N = 3.8), 4.40 (t, 2H, H2/H5, N = 3.8), 5.39 (b,
1H, NHMe), 8.21 (d, 1H, HC@N, 4J(PH) = 4.5). 31P–
{1H} NMR (d ppm) 23.5s.
Yield: 61.3%. Anal. Calc. for C31H29ClFeN3PPdS: C,
52.9; H, 4.2; N, 6.0; S, 4.6. Found: C, 53.4; H, 3.9; N,
5.6; S, 4.3%. IR: m(N–H) 3422m, m(C@N) 1596m, m(Pd–
4.7. [{Pd[(g5-C5H5)Fe(g5-C5H4)C(H)@NN@
C(S)NHMe](Cl)}2{l-Ph2P(CH2)4PPh2}] (3b)
1
Cl) 324m cmꢀ1. H NMR (d ppm, J Hz): 2.97 (d, 3H,
NHMe, 3J(HMe) = 4.9), 3.95 (b, 1H, NHMe), 4.22 (s,
5H, C5H5), 4.45 (t, 2H, H3/H4, N = 3.8), 5.00 (t, 2H,
H2/H5, N = 3.8), 3.95 (b, 1H, NHMe), 8.41 (d, 1H,
Yield: 56.5%. Anal. Calc. for C56H54Cl2Fe2N6P2Pd2S2:
C, 49.5; H, 4.3; N, 6.4; S, 4.9. Found: C, 49.1; H, 4.0; N,
6.4; S, 4.4%. IR: m(N–H) 3417m, m(C@N) 1596m, m(Pd–
4
HC@N, J(PH) = 4.1). 31P–{1H} NMR (d ppm) 23.3s.

M. Marin˜o et al. / Polyhedron 25 (2006) 1449–1456
1455
4.12. [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)NH-
Me}(Cl)(PPh2Et)] (5b)
support, and the Xunta de Galicia, incentive PGI-
DIT03PXIC20912PN, for financial support.
Appendix A. Supplementary data
Yield: 63.8%. Anal. Calc. for C27H29ClFeN3PPdS: C,
49.4; H, 4.5; N, 6.4; S, 4.9. Found: C, 50.0; H, 4.7; N,
6.1; S, 5.1%. IR: m(N–H) 3423m, m(C@N) 1592m, m(Pd–
Crystallographic data (excluding structure factors) for
the structures reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre as sup-
plementary publication numbers 279562 (2a) and 279563
(2b). Copies of the data can be obtained free of charge
on application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK. Supplementary data associated with this
article can be found, in the online version, at
doi:10.1016/j.poly.2005.10.003.
1
Cl) 299m cmꢀ1. H NMR (d ppm, J Hz): 3.00 (d, 3H,
NHMe, 3J(HMe) = 4.6), 3.88 (b, 1H, NHMe), 4.20 (s,
5H, C5H5), 4.44 (t, 2H, H3/H4, N = 3.8), 4.99 (t, 2H,
H2/H5, N = 3.8), 8.34 (d, 1H, HC@N, 4J(PH) = 3.7).
31P–{1H} NMR (d ppm) 26.5s.
4.13. [Pd{(g5-C5H5)Fe(g5-C5H3)C(H)@NN@C(S)NH-
Me}(Cl){P(C6D5)3}] (6b)
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5.6; S, 3.9%. IR: m(N–H) 3428s, m(C@N) 1593m, m(Pd–Cl)
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