Versatility in the mode of coordination [(C)-, (N,S), (C,N)- or (C,N,S)-] of the Schiff base: C6H5-CH=N-CH2-CH2-SEt to palladium(II). X-ray crystal structures of cis-[Pd{C6H5-CH=N-CH2-CH 2-SEt}Cl2]

Article abstract of DOI:10.1016/S0022-328X(01)00821-X

The reaction of ligand C₆H₅-CH=N-CH₂-CH₂-SEt (1) with Na₂[PdCl₄] is studied. It yields, depending on the experimental conditions, two different sorts of palladium(II) complexes: cis-[Pd{C₆H₅-CH=N-CH₂-CH ₂-SEt}Cl₂] (2b) and [Pd{C₆H₄-CH=N-CH₂-CH₂-SEt}Cl] (3b). Compounds 2b and 3b differ in the mode of binding of the ligand to the palladium: as a neutral (N,S) group in 2b or as a monoanionic (C,N,S)^- terdentate ligand in 3b. The results presented here show that the formation of 3b is promoted thermally and requires the presence of sodium acetate. The cyclopalladated complex 3b reacts with PPh₃, in a 1:1 or 1:2 molar ratio, to produce [Pd{C₆H₄-CH=N-CH₂-CH ₂-SEt}Cl(PPh₃)] (4b) or [Pd{C₆H₄-CH=N-CH₂-CH ₂-SEt}Cl(PPh₃)₂] (5b), respectively. All the complexes have been characterised by elemental analysis, infrared and NMR spectroscopy. Compounds 2b and 3b have also been characterised structurally: 2b is triclinic, space group P1?, with a=8.081(2), b=8.230(2), c=10.836(2) ?, α=109.16(3), β=96.65(3) and γ=92.29(3)° and 3b is triclinic, space group P1?, with a=10.201(2), b=11.927(2), c=17.568(4) ?, α=104.35(3), β=94.21(3) and γ=111.56(3)°. The structural studies confirmed the mode of binding of the ligand to the palladium and revealed that the ligand has the Z-form in 2b and the E-form in 3b. Semiempirical calculations based on the pm3(tm) method have also been used to explain the isomerisation of 2b.

Full text of DOI:10.1016/S0022-328X(01)00821-X

Journal of Organometallic Chemistry 629 (2001) 97–108
www.elsevier.com/locate/jorganchem
Versatility in the mode of coordination [(C)−, (N,S), (C,N)− or
(C,N,S)−] of the Schiff base: C6H5–CHꢀN–CH2–CH2–SEt to
palladium(II). X-ray crystal structures of
cis-[Pd{C6H5–CHꢀN–CH2–CH2–SEt}Cl2] and
[Pd{C6H4–CHꢀN–CH2–CH2–SEt}Cl]
Xavier Riera a, Amparo Caubet a,*, Concepcio´n Lo´pez a,*, Virtudes Moreno a,
Eva Freisinger b, Michael Willermann b, Bernhard Lippert b
a Departament de Qu´ımica Inorga`nica, Facultat de Qu´ımica, Uni6ersitat de Barcelona, Mart´ı i Franque`s 1-11, E-08028 Barcelona, Spain
b Fachbereich Chemie, Uni6ersita¨t Dortmund, Otto-Hahn Strasse 6, D-44227 Dortmund, Germany
Received 23 February 2001; accepted 29 March 2001
Abstract
The reaction of ligand C6H5–CHꢀN–CH2–CH2–SEt (1) with Na2[PdCl4] is studied. It yields, depending on the experimental
conditions, two different sorts of palladium(II) complexes: cis-[Pd{C6H5–CHꢀN–CH2–CH2–SEt}Cl2] (2b) and [Pd{C6H4–
CHꢀN–CH2–CH2–SEt}Cl] (3b). Compounds 2b and 3b differ in the mode of binding of the ligand to the palladium: as a neutral
(N,S) group in 2b or as a monoanionic (C,N,S)− terdentate ligand in 3b. The results presented here show that the formation of
3b is promoted thermally and requires the presence of sodium acetate. The cyclopalladated complex 3b reacts with PPh3, in a 1:1
or 1:2 molar ratio, to produce [Pd{C6H4–CHꢀN–CH2–CH2–SEt}Cl(PPh3)] (4b) or [Pd{C6H4–CHꢀN–CH2–CH2–
SEt}Cl(PPh3)2] (5b), respectively. All the complexes have been characterised by elemental analysis, infrared and NMR spec-
(
troscopy. Compounds 2b and 3b have also been characterised structurally: 2b is triclinic, space group P1, with a=8.081(2),
,
(
b=8.230(2), c=10.836(2) A, h=109.16(3), i=96.65(3) and k=92.29(3)° and 3b is triclinic, space group P1, with a=10.201(2),
,
b=11.927(2), c=17.568(4) A, h=104.35(3), i=94.21(3) and k=111.56(3)°. The structural studies confirmed the mode of
binding of the ligand to the palladium and revealed that the ligand has the Z-form in 2b and the E-form in 3b. Semiempirical
calculations based on the pm3(tm) method have also been used to explain the isomerisation of 2b. © 2001 Elsevier Science B.V.
All rights reserved.
Keywords: Schiff base; Palladium; Thioimine; Cyclometallation
racemic mixtures of Lewis bases, as chiral recognitors,
etc. [2]. In addition, the antitumor activity of some
1. Introduction
palladium(II) or platinum(II) compounds containing
(C,N)− bidentate groups have also been published in
recent years [3]. Despite the variety of cyclopalladated
complexes containing bidentate (C,N)−, (C,P)−, (C,S)−
ligands described so far, those having monoanionic and
terdentate groups are not so common [4]. In particular,
palladacycles holding (C,N,S)− ligands are scarce and
practically restricted to a few benzylthio- or benzosul-
phinyl-substituted azobenzenes [5,6].
Palladium(II) and platinum(II) complexes containing
‘M(L)Cl2’ cores, where L represents a neutral bidentate
group or anionic (C,X)− {X=N, S or P} group have
attracted great interest in the last decade [1], mainly due
to their applications in a wide variety of areas, i.e.: as
precursors in organic and organometallic syntheses, as
catalysts, as auxiliary substrates for the separation of
* Corresponding authors. Tel.: +34-93-4021274; fax: +34-93-
4907725.
E-mail address: conchi.lopez@qu.ub.es (C. Lo´pez).
We have recently reported the syntheses of C6H5–
CHꢀN–CH2–CH2–SEt (1) (Fig. 1) and the study of its
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00821-X

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X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
2. Results and discussion
2.1. Syntheses of the compounds
When the stoichiometric amount of ligand 1 was
added to a solution of Na2[PdCl4] (in methanol) at
room temperature, a pale yellow solid formed immedi-
ately (Scheme 1, step (a)). Its characterisation data (see
below) were consistent with those expected for cis-
[Pd{C6H5–CHꢀN–CH2–CH2–SEt}Cl2] (2b), in which
the ligand acts as a neutral (N,S) donor group. Accord-
ing to the NMR studies and the X-ray crystal structure
of 2b (see below), the ligand has the Z-form in solution
as well as in the solid state.
It has been recently reported that the reaction of 1
with cis-[PtCl2(dmso)2] produced the coordination com-
plex: cis-[Pt{C6H5–CHꢀN–CH2–CH2–SEt}Cl2] (2a)
(Fig. 1), but when the reaction was performed in the
Fig. 1. Schematic view of ligand: C6H5–CHꢀN–CH2CH2SEt (1) and
the platinum(II) derivatives described previously.
reactivity towards platinum(II) salts [7]. These studies
have allowed the isolation and characterisation of dif-
ferent types of platinum(II) complexes (2a–4a in Fig. 1)
which differ in the mode of binding of the ligand 1 to
the metal ion. In view of these results, we decided to
elucidate whether this versatility of bonding of 1 could
also be extended to palladium(II). We herein describe
the results obtained in the reaction of ligand 1 with
palladium(II) salts.
presence of sodium acetate the |(Csp , phenyl–H) bond
2
underwent activation giving cis-[Pt{C6H4–CHꢀN–
CH2–CH2–SEt}Cl] (3a) (Fig. 1), in which the ligand
behaves as a (C,N,S)− terdentate group [7]. In addition,
the coordination complex 2a could be also transformed
into the platinacycle 3a by treatment with
Na(CH3COO) in refluxing methanol [7]. On this basis,
we decided to test whether this sort of reaction could
also be extended to the palladium(II) analogue: cis-
Scheme 1. (i) Na2[PdCl4] in methanol at room temperature. (ii) Na(CH3COO) in refluxing MeOH (see text). (iii) Na2[PdCl4] and Na(CH3COO)
in refluxing MeOH. (iv) PPh3 in CDCl3 at room temperature.

X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
99
[Pd{C6H5–CHꢀN–CH2–CH2–SEt}Cl2] (2b). The reac-
tion of 1 with stoichiometric amounts of Na2[PdCl4]
and Na(CH3COO) in refluxing methanol for 2 h, fol-
lowed by the working up of the solution gave two
complexes: the unreacted 2b and small amounts (ca.
19%) of a new compound 3b. The charaterisation data
of 3b, based on elemental analyses and {1H and 13C}-
NMR data (see below), were consistent with those
expected for the cyclopalladated complex: [Pd{C6H4–
CHꢀN–CH2–CH2–SEt}Cl] (3b), in which the ligand
acts as a monoanionic (C,N,S)− group.
In addition, the molar ratio 3b:2b increased with time
{i.e. 60:40 for a reaction time of 5 h) (Scheme 1, step
(b)). Similar results were obtained when 2b was treated
with sodium acetate in refluxing methanol (Scheme 1,
step (c)). The formation of 3b from 2b requires: (a) the
isomerisation of the coordinated ligand from the Z-
form in 2b to the E-form in 3b; and (b) the activation
[Pt{C6H4–CHꢀN–CH2–CH2–SEt}Cl] (3a) [7]. Com-
plex 3a reacted with PPh3 (in a 1:1 molar ratio) to
produce: [Pt{C6H4–CHꢀN–CH2–CH2–SEt}Cl(PPh3)]
(4a). However, no evidence for cleavage of the Pt–N
bond was detected by 31P-NMR spectroscopy, when
compounds 3a or 4a were treated with larger excess of
PPh3 [7].
2.3. Characterisation
The compounds prepared in this work are orange or
yellow solids which are stable at room temperature and
have been characterised by elemental analysis, infrared
and NMR (1H, 13C and 31P (for 4b and 5b)) spec-
troscopy. Compounds 2b and 3b were also character-
ised structurally. In all cases, elemental analysis was
consistent with the proposed formulae (see Section 3).
The most relevant feature observed in the infrared
spectra of the compounds is a sharp and intense band
in the range: 1550–1650 cm−1 which is due to the
stretching of the ꢁCꢀN– group. For 2b–4b this band
is shifted to lower wavenumbers when compared with 1
{w(ꢁCꢀN–): 1644 cm−1 [7]}, thus suggesting that the
imine nitrogen binds to the palladium(II). Proton and
13C{1H}-NMR spectroscopic data for 2b–5b are pre-
sented in Section 3. In all cases the assignments of the
signals were carried out with the aid of 2D-{1H–13C}
heteronuclear NMR experiments.
Previous NMR studies on palladium(II) compounds
containing Schiff bases have shown that the variations
observed in the positions of the imine proton in the free
imines and in the palladium(II) derivatives is indicative
of the conformation of the ligand (E- or Z-form)
[8–10]. If the ligand is in the Z-form, the paramagnetic
anisotropy of the metal, which is close to the imine
proton, produces a downfield shift of the imine proton
signal when compared with the free ligand [8]. In
constrast, for complexes containing the ligand in the
E-form, the resonance of the imine proton is shifted
upfield. So, comparison of the 1H-NMR spectra of
2b–4b and that of the free ligand 1 not only reveals the
mode of coordination of the ligand but also its confor-
mation (E- or Z-form). The small lowfield shift of the
signal due to the –CHꢀN– proton in 2b [l=8.64 ppm
in dmso-d6], when compared with 1 {l=8.36 ppm [7]
in dmso-d6}, suggested [11–13] a Z-form of the imine
in this complex and a weak –CH···Cl interaction. The
use of molecular models further indicates that in 2b the
relative arrangement of the imine proton and the Cl(2)
atom bound to the palladium might likewise be suitable
for this type of interaction. The X-ray crystal structure
of 2b (see below) confirms this hypothesis. This sort of
interaction is similar to those reported in solution as
well as in the solid state for palladium(II) and platinum-
(II) complexes derived from arylimines (in the Z-form)
having fluorine or chlorine groups at the ortho- sites
[11–13].
of the |(Csp , phenyl–H) bond.
2
The formation of the metallacycle 3b requires the
appropiate orientation of the |(Csp2 –H) bond and the
abstraction of HCl, and this is only possible if the
ligand is in the E-form. This finding is similar to that
reported for the platinum(II) analogue (3a) [7] in which
the ligand also behaves as a (C,N,S)− terdentate group.
On the other hand, since 1 has a prochiral S-donor
atom and there is no other source of chiral induction in
the reactions described above, compounds 2b and 3b
are expected to consist of equimolar amounts of the
two enantiomers (S and R).
2.2. Comparison of the reacti6ity of the Pd–N and
Pd–S bonds in compounds 3
The different nature of the four atoms linked to the
palladium(II) in complex 3b, prompted us to study
whether the addition of phosphine ligands could induce
the cleavage of any of the bonds between the terdentate
group and the central atom. This would modify the
hapticity and mode of binding of the ligand, and it is
well known that these changes are important in cata-
lytic processes. On this basis we studied the reactivity of
complex 3b with PPh3. When 3b was treated with the
equimolar amount of PPh3 the monomeric cyclopalla-
dated
compound:
[Pd{C6H4–CHꢀN–CH2–CH2–
SEt}Cl(PPh3)] (4b) formed (Scheme 1, step (d)).
Complex 4b arises from cleavage of the Pd–S bond and
incorporation of a PPh3 in the coordination sphere of
the palladium(II). Further treatment of 4b with PPh3 in
a 1:1 molar ratio leads to cleavage of the Pd–N bond
and the formation of [Pd{C6H4–CHꢀN–CH2–CH2–
SEt}Cl(PPh3)2] (5b) (Scheme 1, step (e)), in which two
PPh3 ligands in a trans-arrangement are bound to the
palladium. This reaction involves the opening of the
metallacycle. The results obtained here differ from
those reported for the cycloplatinated derivative

100
X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
Fig. 2. Section of the 2D-{1H–13C} NMR spectrum {500 MHz} of complex 3b (in CD2Cl2). The numbers refer to the labelling of the atoms shown
in Scheme 1.
In contrast to these trends, the signal of the imine
proton in 3b [l=7.93 ppm (in CD2Cl2)] appeared at
higher fields than in 1 [l=8.32 ppm (in CD2Cl2)], thus
suggesting that the imine adopts the E-form. As men-
tioned above the formation of the metallacycle with a
by van der Waals contacts. In each molecule the palla-
dium is tetracoordinated, bound to two chlorines, Cl(1)
and Cl(2), the imine nitrogen and the sulphur atom,
and is in a slightly distorted square-planar environment
[17].
The variations observed in the two Pd–Cl bond
|(Pd–Csp , phenyl) bond requires a trans-arrangement of
2
,
lengths [Pd–Cl(1): 2.296(1) A and Pd–Cl(2): 2.325(1)
the phenyl ring and the alkyl chain bound to the
nitrogen (E-form). The X-ray crystal structure of 3b
also confirms this finding.
The most relevant features observed in the 13C{1H}-
NMR spectra of the free ligand and its palladium(II)
compounds (see Section 3) are the lowfield shifts of
imine carbon signals (in compounds 2b–4b) and of the
carbon carrying the metal in compounds 3b–5b. This
trend, together with the magnitude of the shift, is
similar to that reported for related palladium(II) com-
pounds derived from organic Schiff bases [7,14,15].
On the other hand, the 2D-{1H–13C} NMR spectra
of 3b (Fig. 2) showed only four cross-peaks in the
aromatic region, thus confirming that palladation took
place at the phenyl ring.
Compounds 4b and 5b were also characterised by
31P-NMR spectroscopy. In both cases the spectra dis-
played singlets at 41.26 ppm (4b) and at 28.90 ppm
(5b). The positions of these signals are consistent with
the values reported for palladated complexes containing
one or two PPh3 ligands in a trans-arrangement at the
palladium(II), respectively [9,10,14–16].
Fig. 3. Molecular structure and atom labelling scheme for 2b.
Table 1
,
Selected bond lengths (A) and bond angles (°) for 2b
Bond lengths
Pd(1)–N(1)
Pd(1)–Cl(1)
S(1)–C(11)
N(1)–C(21)
2.038(3)
2.296(1)
1.812(4)
1.267(5)
Pd(1)–S(1)
Pd(1)–Cl(2)
S(1)–C(31)
N(1)–C(12)
2.255(1)
2.325(1)
1.832(7)
1.482(5)
2.4. Description of the crystal structure of 2b
Bond angles
N(1)–Pd(1)–S(1)
S(1)–Pd(1)–Cl(1)
S(1)–Pd(1)–Cl(2)
N(1)–C(12)–C(11) 108.1(3)
Pd(1)–S(1)–C(11) 98.3(1)
Pd(1)–N(1)–C(21) 123.1(3)
86.80(9)
89.47(4)
176.96(4)
N(1)–Pd(1)–Cl(1)
N(1)–Pd(1)–Cl(2)
Cl(1)–Pd(1)–Cl(2)
N(1)–C(21)–C(1)
Pd(1)–S(1)–C(31)
Pd(1)–N(1)–C(12)
176.26(9)
92.84(9)
90.90(4)
129.9(4)
92.7(3)
A perspective drawing of the molecular structure of
2b, together with the atom labelling scheme is depicted
in Fig. 3, and a selection of bond lengths and angles is
presented in Table 1.
The structure of 2b consists of discrete molecules of
cis-[Pd{C6H5–CHꢀN–CH2–CH2–SEt}Cl2] separated
114.9(2)
Estimated S.D. values in parenthesis.

X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
101
torsion angle: C(12)–N(1)–C(21)–C(1)=8.2(6)° indi-
cates that the ligand adopts the Z-form.
The phenyl ring is planar [20]. It forms an angle of
63.42(10)° with the coordination plane of the metal and
it is nearly orthogonal to the functional ꢁCꢀN– group
[the angle between the normals to their main planes is
99.66(5)°].
In 2b, the distance between the imine hydrogen
,
[H(21)] and the Cl(2) atom is clearly smaller [2.58(4) A]
Fig. 4. ORTEP diagram of one of the three independent molecules (C)
found in the crystal structure of compound 3b, together with the
atom labelling scheme.
,
than the sum of the van der Waals radii of Cl (1.75 A)
,
and H (1.20 A) [21,22], thus suggesting a weak –
CH···Cl(2) interaction. Similar type interactions have
also been described for imines containing chloro or
fluoro groups in the ortho-sites of the aryl rings, such as
in: 4-Me–C6H4–NꢀCH–C6F5 [23], [(h5-C5H5)Fe{(h5-
C5H5–CH2–NꢀCH(2,6-Cl2–C6H3)}] [13], and other
palladium(II) complexes containing cis-‘Pd(L)Cl2’
cores, where L represents a neutral (N,N) group [24].
Table 2
,
Selected bond lengths (A) and bond angles (°) for the three non-
equivalent molecules (A, B and C) found in the crystal structure of 3b
Molecule A
Molecule B
Molecule C
Bond lengths
Pd(1)–N(1)
Pd(1)–S
1.994(4)
2.421(1)
2.311(1)
1.987(4)
1.278(6)
1.409(6)
1.449(6)
1.506(7)
1.810(6)
1.817(5)
1.468(5)
1.986(4)
2.391(2)
2.311(1)
1.987/5)
1.257(6)
1.412(6)
1.431(7)
1.504(7)
1.829(4)
1.808(5)
1.458(6)
1.992(4)
2.416(1)
2.312(1)
2.007(7)
1.265(5)
1.420(6)
1.448(7)
1.501(6)
1.820(4)
1.810(4)
1.471(6)
,
The intermolecular Pd···Pd distance [3.647(1) A] is
clearly larger than the sum of the van der Waals radii
Pd(1)–Cl
,
(ca. 3.20 A) [21,22], which suggests that there is no
Pd(1)–C(2)
N(1)–C(7)
C(1)–C(2)
C(7)–C(1)
C(8)–C(9)
C(9)–S(1)
S(1)–C(10)
N(1)–C(8)
direct bonding between the two metals.
Finally it should be mentioned that since the space
group is centrosymmetric, both enantiomers of 2b (R
and S) are present in the unit cell. This finding is
consistent with the fact that there was no source of
chiral induction in the reaction media and consequently
the formation of the racemate should be expected, in
principle.
Bond angles
N(1)–Pd(1)–C(2)
N(1)–Pd(1)–Cl(1) 174.1(1)
81.0(2)
80.8(2)
178.7(1)
84.8(1)
98.0(1)
165.6(1)
96.5(1)
117.3(5)
113.4(5)
112.1(4)
124.0(5)
102.0(2)
108.4(2)
116.2(4)
81.3(2)
176.1(1)
85.1(1)
N(1)–Pd(1)–S(1)
C(2)–Pd(1)–Cl
C(2)–Pd(1)–S(1)
S(1)–Pd(1)–Cl(1)
N(1)–C(7)–C(1)
C(7)–C(1)–C(2)
C(1)–C(2)–Pd(1)
C(8)–N(1)–C(7)
C(9)–S(1)–C(10)
C(10)–S(1)–Pd
C(7)–N(1)–Pd
84.7(1)
95.3(1)
2.5. Description of the crystal structure of 3b
95.2(1)
165.6(1)
97.07(6)
116.3(5)
113.6(4)
112.7(3)
122.4(5)
100.7(3)
104.6(2)
116.2(3)
165.6(1)
98.53(5)
117.1(4)
113.9(5)
111.3(4)
124.4(4)
102.0(2)
105.2(12)
116.2(4)
The molecular structure of 3b consists of discrete
molecules of [Pd{C6H4–CHꢀN–CH2–CH2–SEt}Cl]
separated by van der Waals forces. Three non-equiva-
lent molecules [hereinafter referred to as A, B and C]
form the asymmetric unit of the structure. The ORTEP
diagram of one of the these molecules (C) is depicted in
Fig. 4, and a selection of bond lengths and angles is
presented in Table 2.
Estimated S.D. values are given in parenthesis.
Each molecule contains a [5,5,6] tricyclic system
derived from the fusion of a five-membered chelate ring
formed by the coordination of the sulphur and nitrogen
atoms to the palladium(II), a five-membered palladacy-
cle, and the phenyl ring. In each molecule the palladium
atom is in a slightly distorted square-planar environ-
ment [25], coordinated to a chlorine, the two het-
eroatoms (S and N) of the ligand and the ortho-carbon
of the phenyl ring {C(2)}, thus confirming that metalla-
tion at the phenyl ring had taken place and conse-
quently, in 3b the ligand acts as a (C,N,S)− terdentate
group.
,
A] can be related to the different influence of the donor
atoms in a trans-arrangement [Nimine and Sthioether
,
respectively].
The metallacycle, formed by the ‘–N–CH2–CH2–S–’
fragment and the palladium, has an envelope-like con-
formation [18] in which the C(12) atoms deviate by
,
0.581(5) A from the least-square planes through Pd(1),
N(1), S(1) and C(11), directed toward C(2).
,
The ꢁCꢀN– bond length [1.267(5) A] is similar to
the values reported in the literature for related palladium-
(II) compounds containing imine ligands [19]. The func-
tional ꢁCꢀN– group, which is not included in the
metallacycle (exocyclic) forms an angle of ca. 26.6° with
the coordination plane of the metal and the value of the
The Pd–N and Pd–Cl bond lengths as well as the
N–Pd–S bond angles in the three molecules do not
differ significantly from those obtained for the coordi-
nation complex 2b (Table 2), and the Pd–C bond

102
X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
175.8(4) and 174.1(4)° for molecules A–C, respectively]
indicate that the ligands have the E-form. As men-
tioned above, the preparation of 3b can be achieved
using 2b [in which the ligand has the Z-form] as
starting material. Consequently, the different arrange-
ment of the substituents on the imine group in 2b and
3b confirms that the isomerisation of the ligand takes
place during the cyclopalladation process.
The phenyl rings are planar [28] and they form angles
of 2.4(3), 0.1(2) and 2.4(3)° (in molecules A–C) with
the functional group, and of 6.4(3), 4.1(3) and 4.2(3)°
(for molecules A–C) with the coordination plane of the
palladium.
The five-membered chelate rings, formed by the coor-
dination of the nitrogen and sulphur to the palladium,
have an envelope-like conformation in which the C(9)
atoms are out of the main plane defined by Pd(1), N(1),
C(8) and S(1) [29]. Except for the Pd–S bond distance,
the remaining bond lengths and angles in these rings do
not differ significantly from those found in 2b (see
above).
length is in good agreement with the values reported for
palladacycles containing a |(Pd–Csp , aryl) bond [19].
2
On the other hand, comparison of data shown in
Tables 1 and 2 reveals that the Pd–S bond length in the
cyclopalladated complex 3b is clearly greater than in
the coordination compound 2b. This fact can be at-
tributed to the stronger trans-influence of the metal-
lated carbon atom as compared to a chlorine ligand
[26]. Bond angles around the palladium vary from ca.
80.8(2) to 98.0(1)° and for the three molecules the
minimum of these values corresponds to the C(7)–
Pd(1)–N(1) angle.
The palladacycles, which are formed by the sets of
atoms Pd, N, C(1), C(2) and C(7), are practically planar
[27] and contain the functional ꢁCꢀN– group (endo-
cyclic), and their main planes form angles of 2.4(3)° (in
A), 3.0(3)° (in B) and 3.0(3)° (in C) with their attached
phenyl rings. The ꢁCꢀN– bond lengths in 3b agree
with the values reported for most of Schiff bases and
their palladium(II) derivatives, and the values of the
torsion angles: C(1)–C(7)–N(1)–C(8) [177.3(5),
In addition, for the three molecules, the Cl···H(3)
,
distance [2.820(2), 2.914(2) and 2.925(2) A for A, B and
C] are somewhat shorter than the sum of the van der
,
,
Waals radii of Cl (1.75 A) and H (1.20 A) [21,22]. This
finding could be indicative of a weak –CH···Cl
interaction.
The shortest intramolecular Pd···Pd and S···S dis-
,
tances are [3.514(2) and 5.027(3) A] clearly greater than
the sum of their van der Waals radii [21,22], which
suggest that there is no direct interaction between these
pairs of atoms.
2.6. Solution studies
In order to evaluate whether the cyclopalladation
process could also be promoted by coordinating lig-
ands, a solution of 2b (in dmso-d6) was prepared and its
1H-NMR spectra was recorded at different times (Fig.
5, A–C). The proton NMR spectrum of the freshly
prepared solution showed only one singlet at 8.64 ppm
(Fig. 5, A), but after 12 h at room temperature (20°C)
the spectrum exhibited higher complexity and an addi-
tional singlet appeared at lower fields [l=9.07 ppm]
(Fig. 5, B). Besides, the relative intensities of the two
singlets varied with time (Fig. 5, C). These observations
suggested that complex 2b underwent degradation with
time and that new species formed in solution.
The chemical shift of the new signal [l=9.07 ppm]
and that of the –CHO proton of benzaldehyde [l=
10.03 ppm in dmso-d6] were significantly different. This
indicated that the degradation of 2b could not be
related to hydrolysis. Consequently, the changes de-
1
tected in the H-NMR spectra of 2b with time probably
are due to other causes, one of which could involve the
replacement of one or the two chlorines in 2b by the
Fig. 5. Section of the proton NMR spectra of 2b (in dmso-d6) at
different times: t=0 (A), 12 h (B), and 24 h (C), at 20°C.

X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
103
involved in a weak hydrogen interaction with the Cl(2)
1
atom, and the H-NMR studies indicated that this is
also the case in solution. Consequently, if the replace-
ment of the Cl(2) ligand by the dmso-d6 takes place,
this interaction will vanish and the signal due to the
imine proton should shift to lower fields {by ca. 0.60–
1.20 ppm} when compared with the free ligand 1, as
observed for the signal at l=9.07 ppm. In view of
these trends we tentatively assume that complex 2b
undergoes a solvolysis process in the presence of dmso-
d6, to produce 2%b.
In order to test whether this reaction could be pro-
moted thermally, a freshly prepared solution of 2b (in
dmso-d6) was heated up to 50°C for varying reaction
1
periods and studied by H-NMR spectroscopy (Fig. 6,
A–D). After 20 min the 1H-NMR spectrum of the
solution in the range 10.2–6.5 ppm became more com-
plex and four singlets at 10.02, 9.07, 8.60 and 8.40 ppm
appeared (Fig. 6, B). The position of the signal at lower
field [l=10.02 ppm] is coincident with that expected
for benzaldehyde in dmso-d6, the two singlets at 8.60
and 9.07 ppm are due to the imine proton of complex
2b and of the new species (2%b) formed in the solvolysis
process described above. The remaining singlet at 8.40
ppm can be ascribed to the –CHꢀN– proton of the
metallated complex 3b. This fact is also supported by
the presence of a multiplet centered at ca. 6.7–6.9 ppm
which is due to the proton of the aryl ring next to the
metallated carbon. It should be noted that the intensi-
ties of the four singlets varied with time. For longer
reaction periods (60 or 90 min) the relative intensities of
these signals changed (Fig. 6, C–D). It is worth noting
that the assignments of the signals seen in the proton
NMR spectra of these samples were also supported by
13C-NMR data. These observations suggested that an
increase in the temperature and the reaction time fa-
voured not only the hydrolysis of the ligand, but also
Fig. 6. Variations of 1H-NMR spectra (in the range 10.2–8.2 ppm) of
a freshly prepared solution of 2b at 50°C, in dmso-d6 (A), and after
20, 60 or 90 min at 50°C (B–D, respectively). The peaks labelled
correspond to the signals of the –CHO proton of the benzaldehyde
formed in the course of the reaction and to the protons of the imine
group in compounds 2b, 2%b and 3b. The additional doublet corre-
sponds to the resonance of the H2 and H6 protons of the phenyl ring
of 2b.
the activation of the |(Csp , phenyl–H) bond. Most of the
2
studies reported so far on cyclopalladation of N-donor
ligands involve the use of bases [i.e. Na(CH3COO) or
the ligand itself] to favour the formation of the |(Pd–
C) bond [30]. Besides, when organic Schiff bases are
used as ligands, the cyclopalladation reaction is gener-
ally carried out under refluxing conditions, suggesting
that the formation of the palladacycle is thermally
promoted. The results obtained from the studies in
solution agree with these general trends, since they
reveal that the formation of benzaldehyde takes place
upon heating, and consequently, the 2-ethylthioethy-
lamine will be released. These two factors (a basic
medium and an increase of the temperature) will favour
the activation of the |(Csp , phenyl–H) bond.
2
Scheme 2.
These findings are similar to those recently described
for the di-m-chloro-bridged cycloplatinated complexes:
[Pt{C6H2N–[2-C6H4–4-R%-6-C6H5]}(m-Cl)]2 [R=H (6a)
or O–C8H17 (6b)] (Scheme 2), which rearranged in
solvent [dmso-d6, which has good donor abilities]. Ac-
cording to the X-ray data of 2b the imine proton is

104
X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
dimethylsulphoxide (dmso) to produce the mononu-
clear bis(cycloplatinated) derivatives [Pt{C6H2N–[2-
C6H4–4-R%-6-C6H4]}Cl (dmso)] [R=H (7a) or
O–C8H17 (7b)] (Scheme 2) through the activation of the
ortho |(Csp2 –H) bond of the phenyl ring [31].
variation can be ascribed to two factors: A higher bulk
of the ferrocenyl group as compared to phenyl [35],
which may hinder, at least partially, the isomerisation
process and/or the different electron donor ability of
the terminal donor atom [Sthioether in 2c or Namine in 8].
2.7. Theoretical approaches to rationalise the
isomerisation of 2b
2.8. Conclusions
The results presented here provide a useful method to
tunethemodeofcoordinationoftheimine1topalladium-
(II) as a neutral (N,S) bidentate ligand (in 2b), as a
monoanionic group acting as monodentate (C)− (in
5b), bidentate (C,N)− (in 4b) or even as a terdentate
(C,N,S)− group (in 3b). In addition, comparison of the
results summarised here and those reported for the
platinum(II) compounds reveal that: (a) the imine binds
to the palladium(II) or to the platinum(II) giving the
coordination complexes cis-[M{C6H5–CHꢀN–CH2–
CH2–SEt}Cl2] [M=Pt (2a) or Pd (2b)] in which the
ligand has a Z-conformation; (b) the presence of
Na(CH3COO) favours the isomerisation of the imine
In an attempt to understand the results obtained in
the reactions of ligand 1 with Na2[PdCl4] and the
isomerisation of the coordinated imine, semiempirical
methods based on the pm3(tm) model of the SPARTAN
5.0 program [32] were carried out. The geometries of all
the molecules used in this study were fully optimised
before calculation of the formation enthalpies (DHform.
)
and the molecular orbitals. In order to test the validity
of the program, the geometry of 2b was optimised and
compared with the X-ray data (see above). The struc-
tural parameters (bond lengths, bond angles and the
relative orientation of the phenyl ring and the coordina-
tion plane of the palladium) in the optimised geometry
were in excellent agreement with the structural data of
2b obtained by X-ray diffraction. In addition, some
authors have recently reported the high degree of agree-
ment between the optimised geometries obtained with
the pm3(tm) for other five-membered palladacycles and
their X-ray data [33]. This suggests that for compounds
of this kind this semiempirical method gives fairly
accurate optimised geometries.
and the activation of the |(Csp , phenylꢂH) bond to give
2
the cyclometallated complexes: [M{C6H4–CHꢀN–
CH2–CH2–SEt}Cl] [M=Pt (3a) or Pd (3b)] in which
the imine has the E form; this finding suggests that the
energy required for the isomerisation of the ligand in 2a
and 2b should be small, in good agreement with the
results obtained from the semiempirical calculations;
and (c) the formation of the |(M–Csp , phenyl) bond is
2
promoted thermally. Besides these facts, the results
obtained in the reaction of the cyclometallated com-
plexes 3 or 4 with PPh3 show that the Pd–N bond in 3b
or 4b is more labile than the Pt–N bonds in their
platinum(II) analogues (3a or 4a). Previous studies on
cyclopalladated and cycloplatinated complexes contain-
ing identical (C,N)− bidentate groups have shown that
in this sort of compounds the Pd–N bond is shorter
than the Pt–N bond [36]. In contrast to these results,
for compounds 3 the trend is just the opposite: the
As a first approach to this problem, the two isomers
of cis-[Pd{C6H5–CHꢀN–CH2–CH2–SMe}Cl2] (Fig. 7)
[which differ in the conformation of the ligand: Z-form
in 2c and E- form in 2d] were used for the semiempiri-
cal calculations.
The formation enthalpy (DHform.) for the two isomers
2c and 2d was calculated with the aid of the SPARTAN
5.0 program [32] giving DHform. = −51.24 kcal mol−1
for 2c and −51.74 kcal mol−1 for the isomer 2d in
which the imine adopts the E-form. This confirmed that
DH for the isomerisation reaction is small (−0.50 kcal
mol−1). It has been recently reported that the energy
required for the isomerisation of the ligand in cis-
[Pd{(p5 - C5H5)Fe{(h5 - C5H4)–CHꢀN–CH2–CH2–N-
(CH3)2]}Cl2] (8) [34] is −4.32 kcal mol−1, which is
greater than the value obtained for complex 2c. This
,
Pt–N bond lengths are 1.963(7) and 1.948(6) A for the
two non-equivalent molecules of 3a, while the Pd–N
,
bond lengths in 3b are 1.994(4), 1.986(4) and 1.992(4) A
for molecules A–C. On this basis, the greater lability of
the Pd–N bond in 3b compared with that of the Pt–N
bond in 3a could be related to these structural
differences.
3. Experimental
Elemental analyses (C, H, N and S) were carried out
at the Serveis Cientifico-Te`cnics (Universitat de
Barcelona). Infrared spectra were obtained with a
NICOLET-IMPACT 400 spectrophotometer using KBr
Fig. 7. Schematic view of the two isomers (2c and 2d) of cis-
[Pd{C6H4–CHꢀN–CH2CH2SMe}Cl2].
1
pellets. Routine and high resolution H-NMR spectra

X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
105
were obtained with Gemini-200 MHz and Varian-500
MHz instruments, respectively. The solvents used for
the NMR experiments are specified in the characterisa-
tion section of each one of the compounds, where the
chemical shifts (l) are given in ppm, and the coupling
constants (J) in Hz. 13C{1H}-NMR spectra were ob-
tained with a Bruker-250DXR instrument using CDCl3
as solvent and Si(CH3)4 as internal standard, except
otherwise when noted. 31P-NMR studies were per-
ferred to an erlenmeyer and concentrated to dryness on
a rotary evaporator. The deep yellow residue was then
dissolved in CH2Cl2 (ca. 15 cm3) and filtered out
through Celite. Slow evaporation of the filtrate at ca.
20°C produced bright yellow microcystals of 3b, which
were collected by filtration and air-dried. Yield: 160 mg,
68%.
3.4. Method (b)
formed with
a Bruker-250DXR instrument using
CDCl3 as solvent and P(OCH3)3 as reference
Compound 2b (104 mg, 0.28 mmol) and
Na(CH3COO) (22 mg, 0.28 mmol) were suspended in
25 cm3 of methanol and refluxed for 12 h. After this
period the brownish solution was allowed to evaporate
at r.t. to ca. 15 cm3 and filtered out. The filtrate was
then transferred to an open vessel and allowed to
evaporate at r.t. The brownish residue was then treated
with CH2Cl2 and filtered out through Celite to remove
the small amounts of metallic palladium formed in the
course of the reaction and the inorganic salts. Slow
evaporation of the filtrate at ca. 20°C produced bright
yellow microcrystals of 3b. This complex can be recrys-
tallised from CH2Cl2. Yield: 73 mg, 75%. Characterisa-
tion data: Anal. Calc. for C11H14ClNPdS·1/8CH2Cl2
(found): C, 38.77 (38.9); H, 4.24 (4.1); N, 4.06 (4.1); S,
[l31P{P(OCH3)3}=140.17 ppm].
3.1. Materials and synthesis
The ligand C6H5–CHꢀN–CH2–CH2–SEt (1) was
prepared as described previously [7]. Except methanol,
which was HPLC grade, the remaining solvents used
for the preparation of the complexes were dried and
distilled before use.
3.2. cis-[Pd{C6H5–CHꢀN–CH2–CH2–SEt}Cl2] (2b)
The imine 1 (100 mg, 0.52 mmol) was dissolved in 5
cm3 of methanol. Then a solution of 153 mg (0.52
mmol) of Na2[PdCl4] in 5 cm3 of methanol was added
at room temperature (r.t.) (ca. 20°C). The reaction
mixture was stirred for 30 min and the solid formed
was collected by filtration, washed with small amounts
of methanol (ca. 3 cm3), air-dried and later dried over
silica gel. Yield: 138 mg, 72.1%. Characterisation data:
Anal. Calc. for C11H15Cl2NPdS (found): C, 35.65
(35.7); H, 4.11 (4.1); N, 3.78 (3.8); S, 8.65 (8.4)%. IR:
9.29 (9.25)%. IR: {w(ꢁCꢀN–)}=1609 cm−1
.
1H-
3
NMR data (in CD2Cl2) [37]: 1.46 [t, 3H, –CH3, J(H–
3
H)=15], 2.98 [q, 2H, S–CH2–, J(H–H)=15], 3.04 [t,
2H, ꢂCH2–S, 3J(H–H)=12], 3.90 [t, 2H, N–CH2–,
3J(H–H)=12], 7.23 [dd, 1H, H3, 3J(H–H)=7.5,
4J(H–H)=1.5], 7.07 [td, 1H, H4, 3J(H–H)=7.5,
4J(H–H)=1.5], 7.16 [td, 1H, H5, 3J(H–H)=7.5,
4J(H–H)=1.5], 7.66 [dd, 1H, H6, 3J(H–H)=7.5,
4J(H–H)=1.5], 7.93 [t, 1H, –CHꢀN–, 4J(H–H)=
2.0]. 13C-NMR data (in CD2Cl2) [37]: 13.05 [–CH3],
29.02 [SꢂCH2–], 36.32 [–CH2–S], 56.84 [–N–CH2–],
126.21 [C3], 124.12 [C4], 130.05 [C5], 134.29 [C6] and
174.21 [–CHꢀN–].
1
w(ꢁCꢀN–)=1634 cm−1. H-NMR data (in dmso-d6)
[37]: 1.49 [t, 3H, –CH3], 2.70–2.90 [br. m, 2H, S–CH2–
], 3.10–3.20 [br. m, H, –CH2–S], 4.10–4.50 [br. m, 2H,
N–CH2–], 8.51 [d, 2H, H2 and H6], 8.64 [s, 1H,
–CHꢀN–] and 7.30–7.60 [m, 3H, H3, H4 and H5].
13C-NMR data (in dmso-d6) [37]: 14.92 [–CH3], 32.10
[–SCH2–], 35.40 [–CH2S–], 60.16 [–NCH2–], 173.16
[–CHꢀN–] and 128.49, 129.54, 129.99, 132.06 and
132.57 [Caromatic].
3.5. [Pd{C6H4–CHꢀN–CH2–CH2–SEt}Cl(PPh3)] (4b)
Triphenylphosphine (38 mg, 0.145 mmol) was added
to a solution formed by 50 mg (0.149 mmol) of 3b
dissolved in 20 cm3 of CH2Cl2 and stirred at r.t. for 20
min. The resulting yellow solution was then allowed to
evaporate at r.t. The solid formed was collected by
filtration washed with three portions of ca. 1 cm3 of
n-hexane and air-dried. Yield: 71 mg, 82%. Characteri-
sation data: Anal. Calc. for C29H29ClNPPdS (found):
C, 58.40 (58.1); H, 4.90 (4.8); N, 2.35 (2.3); S, 5.38
3.3. [Pd{C6H4–CHꢀN–CH2–CH2–SEt}Cl] (3b)
This complex was prepared using either ligand 1 or
2b as starting material.
3.3.1. Method (a)
The Schiff base 1 (133 mg, 0.69 mmol), Na2[PdCl4]
(203 mg, 0.69 mmol) and Na(CH3COO) (57 mg, 0.69
mmol) were suspended in 25 cm3 of methanol. The
resulting mixture was refluxed for 12 h and filtered out.
The bright yellow filtrate was concentrated on a rotary
evaporator to ca. 15 cm3. The yellow solid formed (2b)
was removed by filtration and the filtrate was trans-
1
(5.3)%. IR: {w(ꢁCꢀN–)}=1637 cm−1. H-NMR data
(in CD2Cl2) [37]: 1.17 [t, 3H, –CH3, 3J(H–H)=15],
3.12 [t, 2H, CH2S, 3J(H–H)=15], 2.52 [q, 2H, SCH2–,
3J(H–H)=12], 4.22 [br., 2H, NCH2–], 6.35 [m, 1H,
H3], 6.55 [t, 1H, H4], 6.92 [t, 1H, H5], 8.31 [d, 1H,
–CHꢀN–] and 7.45–7.70 [m, 17H, H6 and protons of

106
X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
Table 3
2.81 [t, 2H, ꢂCH2ꢂS], 3.80 [t, 2H, –NCH2–], 8.20 [s,
1H, –CHꢀN–], 6.80–7.80 [m, 34H, aromatic]. 13C-
NMR (in CDCl3) selected data [37]: 14.79 [–CH3],
26.20 [SCH2–], 32.32 [–CH2ꢂS], 61.55 [–NCH2–],
161.19 [–CHꢀN–]. 31P-NMR data: 28.90.
Crystal data and details of the structure refinement of 2b and 3b
2b
3b
Empirical formula
Formula weight
T (K)
u(Mo–Ka) (A)
Crystal system
Space group
C11H15Cl2NPdS
370.60
173(2)
0.71069
triclinic
C
11H14ClNPdS
334.14
293(2)
0.71069
triclinic
,
3.7. Crystallography
(
(
P1
P1
A prismatic orange crystal of 2b (0.34×0.17×0.04
mm) or bright yellow crystal of 3b (0.1×0.1×0.1 mm)
was selected. Intensity data for 2b and 3b were collected
,
a (A)
8.081(2)
8.230(2)
10.836(2)
109.16(3)
96.65(3)
92.29(3)
673.8(3)
1.827
10.201(2)
11.927(2)
17.568(4)
104.35(3)
94.21(3)
111.56(3)
1893.5(7)
1.758
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
on a Enraf–Nonius KappaCCD [38] (Mo–Ka=
,
0.71069 A, graphite monochromator) with sample-to-
detector distances of 29.2 and 30.1 mm, respectively.
They covered the whole sphere of reciprocal space by
measurements of 36 frames rotating about ꢀ in steps of
1° with scan times of 45 (2b) and 30 (3b) s per frame.
Preliminary orientation matrices and unit cell parame-
ters were obtained from the peaks of the first ten
frames, respectively, and refined using the whole data
set. Frames were integrated and corrected for Lorentz
and polarisation effects using DENZO [39]. The scaling
as well as the global refinement of the crystal parame-
ters were performed by SCALEPACK [39]. Reflections,
which were partially measured on previous and follow-
ing frames, are used to scale this frames on each other.
Merging of redundant reflections in part eliminates
absorption effects and also considers a crystal decay if
present. For 2b a total of 2155 reflections were collected
in the range 2.565q525.35° of which 1745 reflections
were non-equivalent by symmetry [Rint (on I)=0.040].
For 3b, 5994 reflections were collected in the range
2.565q524.71° [Rint (on I)=0.058]. The number of
reflections assumed as observed [Fo\4|(Fo)] was 1745
for 2b and 3875 for 3b. Lorentz polarisation, but no
further absorption corrections were made.
3
,
V (A )
Dcalc (Mg m−3
)
v (mm−1
F(000)
)
1.901
368
1.814
996
[ Range (°)
h, k, l ranges
2.56–25.35
05h519,
−95k59,
−125l512
2155
2.56–24.71
05h511,
−145k513,
−205l520
5994
No. of total reflections
No. of independent
reflections
[Rint (on F)]
Refinement method
1745
3875
0.040
0.058
Full-matrix
Full-matrix
least-squares on least-squares on F2
F2
2155
207
1.009
No. of data
5994
414
0.886
R1=0.0314,
wR2=0.0673
R1=0.0584,
wR2=0.0713
0.417 and −0.526
No. of parameters
Goodness-of-fit on F2
Final R indices
[I\2|(I)]
R1=0.0257,
wR2=0.0584
R1=0.0381,
wR2=0.0950
0.342 and
−0.530
R indices (all data)
Largest difference peak
and hole (e A )
3
,
The structures were solved by Patterson using
SHELXS-86 computer program and refined by full ma-
trix least-squares method with the SHELXL-93 program
[40]. ƒ, ƒ% and ƒ%% were taken from the literature [41].
Further details concerning the crystal structures of 2b
and 3b are presented in Table 3.
PPh3]. 13C-NMR data (in CD2Cl2) [37]: 13.87 [–CH3],
26.92 [S–CH2–], 34.11 [–CH2–S], 59.37 [N–CH2–],
138.32 [C3], 130.73 [C4], 124.89 [C5], 177.25 [–CHꢀN–]
and four additional doublets centered at: 134.41,
131.95, 131.22 and 128.71 due to the 13C nuclei of the
PPh3 ligand. 31P-NMR data: 41.26.
3.8. Computational details
3.6. [Pd{C6H4–CHꢀN–CH2–CH2–SEt}Cl(PPh3)2]
(5b)
The calculations were performed with the SPARTAN
5.0 suite of programs [32] using a Silicon Graphics
This reaction was carried out in an NMR tube using
the following procedure: triphenylphosphine (15 mg,
0.057 mmol) was added to a solution of 3b (20 mg,
0.029 mmol) in 0.7 cm3 of CDCl3. The resulting mixture
was shaken vigorously at r.t. for ca. 5 min. The result-
ing pale yellow solution was studied by NMR spec-
troscopy. Characterisation data: 1H-NMR data (in
CDCl3) [37]: 1.29 [t, 3H, –CH3], 2.56 [q, 2H, SCH2–],
workstation (INDIGO-2 power XZ). The pm3(tm)
method was used with the default parameters provided
by the program. Geometrical restrictions were not im-
posed in any case. The calculations were carried out
using the option SFC=converge. The number of cycles
required for the optimisation of the geometries was
greater than the default value. A minimum of 2000
cycles was necessary for the palladium(II) compounds.

X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
107
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4. Supplementary material
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Chakravorty, Inorg. Chem. 25 (1986) 2214.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 157800 and 157801 for com-
pounds 2b and 3b. Copies of this information may be
obtained from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: +44-1233-336-033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
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Acknowledgements
We thank the Ministerio de Educacio´n y Cultura and
the Ministerio de Ciencia y Tecnolog´ıa of Spain and to
the Generalitat de Catalunya for financial support
(grants: PB98-1236, BQU2000-0652 and 1997-SGR-
044).
[10] J. Albert, R.M. Ceder, M. Go´mez, J. Granell, J. Sales,
Organometallics 11 (1992) 1536.
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(b) R. Bosque, C. Lo´pez, X. Solans, M. Font-Bardia,
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[17] The least-squares equation of the plane defined by the atoms
S(1), Cl(1), Cl(2) and N(1) is: (0.0036)XO+(1.0000)YO+(−
0.0044)ZO=1.7743. The deviations from the mean plane are:
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atoms Pd(1), S(1), N(1) and C(11) is: (0.0494)XO+
(0.9984)YO+(−0.0270)ZO=1.7723. The deviations from the
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Synthesis and Structure, vol. 3, Blackie Academic and Profes-
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atoms
[C(1)–C(6)]
is:
(0.7523)XO+(0.4426)YO+(−
0.4880)ZO=1.244. The deviations from the mean plane are:
C(1): −0.009(3); C(2): 0.000(3); C(3): 0.007(4); C(4): −0.005(3);
,
C(5): −0.003(3) and C(6): 0.010(3) A.
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108
X. Riera et al. / Journal of Organometallic Chemistry 629 (2001) 97–108
[25] The least-squares equation of the plane defined by the atoms:
(0.7352)XO+(0.5899)YO+(0.3339)ZO=7.2030. The C(9)
,
Cl(1), C(2), N(1) and S(1) for molecules A, B and C are, for A
atom deviates by 0.5772 A towards the opposite direction of the
C(10) atom. For B: (0.3986)XO+(0.7424)YO+(0.5385)ZO=
:
(0.6899)XO+(0.6173)YO+(0.3781)ZO=7.1387 (deviations
,
from the mean plane: Cl(1): −0.040; C(2): 0.058; N(1): −0.061
1.808. The C(9) atom deviates by 0.7017 A towards the direction
of the C(10) atom. For C: (0.8154)XO+(0.3298)YO+
,
and S(1): 0.044 A); for B: (0.3982)XO+(0.7544)YO+
,
(0.5218)ZO=1.8486 (deviations from the mean plane: Cl(1):
(0.4558)ZO=10.6279. The C(9) atom deviates by 0.5162 A
,
−0.0001; C(2): −0.001, N(1): −0.001 and S(1): 0.001 A) and
towards the opposite direction of the C(10) atom.
[30] A.D. Ryabov, I.K. Sakodinskaya, A.K. Yatsimirsky, J. Chem.
Soc. Dalton Trans. (1985) 2629.
for C: (0.8283)XO+(0.3907)YO+(0.4016)ZO=10.8172 (devia-
tions from the mean plane: Cl(1): −0.044; C(2): 0.061, N(1):
,
−0.065 and S(1): 0.048 A).
[31] G.N.V. Gave, F.P. Fanizzi, R.J. Deeth, W. Errington, J.P.
Rourke, Organometallics 19 (2000) 1355.
[32] SPARTAN 5.0. Wavefunction Inc., Irvine, CA, 1995.
[33] C. Lo´pez, R. Bosque, X. Solans, M. Font-Bard´ıa, New J. Chem.
22 (1998) 977.
[26] (a) G.E. Hartwell, R.V. Lawrence, M.J. Smas, J. Chem. Soc.
Chem. Commun. (1970) 912;
(b) M.I. Bruce, B.L. Goodall, F.G.A. Stone, J. Organomet.
Chem. 60 (1973) 343.
[27] The least-squares equation of the plane defined by the atoms:
Pd(1), C(1), C(2), C(7) and N(1) for molecules A, B and C are,
for A: (0.7374)XO+(0.5911)YO+(0.3344)ZO=2.4007 (devia-
tions from the main plane: Pd(1): −0.025; C(1): −0.015; C(2):
[34] A. Caubet, C. Lo´pez, R. Bosque, X. Solans, M. Font-Bard´ıa, J.
Organomet. Chem. 577 (1999) 292.
[35] C. Hansch, A. Leo, D. Koekman, Exploring QSAR. Hydropho-
bic, Electronic and Steric Constants, ACS- professional reference
books, Washington, DC, 1995.
,
0.023, C(7): −0.096 and N(1): 0.024 A); for B: (0.4292)XO+
(0.7262)YO+(0.5191)ZO=2.0466 (deviations from the main
plane: Pd(1): −0.024; C(1): −0.022; C(2): 0.025; C(7): −0.007
[36] (a) R. McCrindle, G. Ferguson, A. McAlees, G.J. Arsenault, A.
Gupta, M.C. Jennings, Organometallics 14 (1995) 2741;
(b) J.M. Wisner, T.J. Bartczak, J.A. Ibers, Organometallics 5
(1986) 2044;
,
and N(1): 0.023 A) and for C: (0.7869)XO+(0.4406)YO+
(4321)ZO=10.8793 (deviations from the main plane: Pd(1):
0.025; C(1): 0.036; C(2): −0.032; C(7): 0.047 and N(1): −0.023
(c) J.M. Wisner, J.M. Bartczak, J.A. Ibers, J.J. Low, W.A.
Goddard, J. Am. Chem. Soc. 108 (1986) 347;
,
A).
[28] The least-squares equation of the plane defined by the atoms:
C(1), C(2), C(3), C(4), C(5) and C(6) for molecules A, B and C
are, for A: (0.7532)XO+(5867)YO+(0.2976)ZO=7.1857 (max-
imum deviations were found for C(4): −0.008 and C(6): 0.006
(d) K.J. Cavell, H.Jin, B.W. Skelton, A.H. White, J. Chem. Soc.
Dalton Trans. (1993) 1973.
[37] Labelling of the atoms refers to that shown in Scheme 1.
[38] NONIUS BV, KappaCCD package, Ro¨ntgenweg 1, Delft, The
Netherlands.
[39] Z. Otwinowsky, W. Minor, Methods Enzymol. 276 (1996) 307.
[40] G.M. Sheldrick, SHELXS-97 and SHELXL-97 programs for the
solution and refinement of crystal structures, Universita¨t Go¨ttin-
gen, Go¨ttingen, Germany, 1997.
[41] International Tables of X-ray Crystallography, vol. IV, Kynoch
Press, Birmingham, 1974, pp. 99, 100 and 149.
,
A); for B: (0.4721)XO+(0.7049)YO+(0.5293)ZO=2.4007
,
(maximum deviations for C(1): 0.008 and C(2): −0.007 A) and
for molecule C: (0.7870)XO+(0.4756)YO+(0.3931)ZO=
10.9007 (maximum deviations for C(4): −0.011 and C(6): +
,
0.011 A).
[29] The least-squares equations of the mean planes defined by the
atoms Pd, N, C(8) and S(1) in molecules A, B and C are: for A
.