Synthesis, characterization and X-ray structural determination of palladium(0)-olefin complexes containing pyridin-thioethers as ancillary ligands. Equilibria and rates of olefin and ligand exchange

Article abstract of DOI:10.1016/S0022-328X(00)00014-0

The synthesis of Pd(0)-olefin complexes with pyridin-thioether ligands R′N-SR is reported. X-ray structure determinations of selected species are described. The dynamic behavior was studied by variable-temperature ¹H-NMR spectrometry. Equilibrium constants for olefin and chelate ligand exchange were determined by UV-vis spectrophotometry in chloroform at 25°C. The following metal-olefin stability order was observed: tetramethylethylenetetracarboxylate (tmetc)≈naphthoquinone (nq)a similar extent, as found in similar Pd(II) complexes. When the entering olefin is tmetc, the approach to equilibrium is slow so that both second-order rate constants k₂ and k_-2 could be determined along with their activation parameters for the reversible reaction of [Pd(η²-nq)(HN-SⁱPr)] with tmetc. The results indicate an associative mechanism to be operative in these olefin exchange processes.

Full text of DOI:10.1016/S0022-328X(00)00014-0

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 601 (2000) 1–15
Synthesis, characterization and X-ray structural determination of
palladium(0)–olefin complexes containing pyridin-thioethers as
ancillary ligands. Equilibria and rates of olefin and ligand
exchange
Luciano Canovese a,*, Fabiano Visentin a, Gavino Chessa a, Paolo Uguagliati a,
Alessandro Dolmella b
a Dipartimento di Chimica, Uni6ersita’ di Venezia, Venice, Italy
b Dipartimento di Scienze Farmaceutiche, Uni6ersita’ di Pado6a, Padua, Italy
Received 16 November 1999; accepted 5 January 2000
Abstract
The synthesis of Pd(0)–olefin complexes with pyridin-thioether ligands R%NꢀSR is reported. X-ray structure determinations of
1
selected species are described. The dynamic behavior was studied by variable-temperature H-NMR spectrometry. Equilibrium
constants for olefin and chelate ligand exchange were determined by UV–vis spectrophotometry in chloroform at 25°C. The
following metal–olefin stability order was observed: tetramethylethylenetetracarboxylate (tmetc):naphthoquinone (nq)Bfuma-
ronitrile (fn):maleic anhydride (ma)ꢀtetracyanoethylene (tcne). The ligand exchange equilibrium constants indicate that
a-diimines and pyridin-thioethers affect the stability of the metal–bidentate ligand arrangement to a similar extent, as found in
similar Pd(II) complexes. When the entering olefin is tmetc, the approach to equilibrium is slow so that both second-order rate
constants k2 and k−2 could be determined along with their activation parameters for the reversible reaction of [Pd(h2-
nq)(HNꢀSiPr)] with tmetc. The results indicate an associative mechanism to be operative in these olefin exchange processes.
© 2000 Elsevier Science S.A. All rights reserved.
Keywords: Palladium–olefin complexes; Thioethers; Equilibria; Olefin and ligand exchange
stability of these zero-valent metal–olefin complexes,
either as final products or reacting substrates, is of
1. Introduction
prime importance in the mechanistic pattern, being
dictated by the nature of both the bidentate ligand and
the olefin. In this context, we investigated equilibria
and rates of olefin displacement in Pd(0) a-diimine
complexes by activated, electron-poor olefins [3]. Equi-
librium constants increased with increasing electron
affinity of the entering olefin, whereas an associative
pathway is operating for the slow, kinetically moni-
tored reaction. These studies are among the few de-
scribed so far concerning the stability and reactivity of
zero-valent olefin complexes. Recently it has been
shown that back donation of electron density from the
metal to the olefin is the major factor affecting stability.
Substitution of the olefin may occur via either asso-
ciative or dissociative mechanisms, depending on the
We have been systematically studying the mechanism
of nucleophilic attack at the allyl moiety in h3-allyl
palladium(II) cationic complexes containing bi- and
terdentate (NN, NP, NS, NSN, SNS, PNN, NNN)
ligands in the presence of activated olefins (ol) by
tetraphenylborate ion or amines. The reactions involve
allylphenylation or -amination with concomitant for-
mation of palladium(0) olefin complexes of the type
[Pd(ol)(polydentate ligand)] [1]. We have also studied
the reverse of the amination reaction, i.e. the oxidative
allyl transfer from allylammonium cations to [Pd(h2-
ol)(a-diimine)] [2]. It has become apparent that the
* Corresponding author.
E-mail address: cano@unive.it (L. Canovese)
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00014-0

2
L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
Table 1
steric requirements of the bidentate ligand [4]. Associa-
tive paths had also been proposed for olefin ex-
changein[Pt(C2H4)(PPh3)2][5]and[Pd(olefin)(PMePh2)2] -
[6] and for substitution of coordinated alkynes in
[Pt(alkyne)(PPh3)2] complexes [7]. An interesting dy-
namic behavior is displayed by recently described palla-
dium(0) complexes containing chelating diimines [4,8],
P,N- [9], and P,S-donor ligands [10].
Several of these palladium–olefin substrates have
interesting applications in some catalytic reactions ei-
ther as precursors or as active species [8,11]. In view of
these promising features and of the paucity of quantita-
tive equilibrium and kinetic data available for these
systems, we have investigated the thermodynamics and
mechanism of substitution of the coordinated olefin by
other, electron-poor olefins in complexes of N,S-donor
chelating ligands R%NꢀSR of the type [Pd(ol)(R%NꢀSR)]
2
t
,
Selected bond lengths (A) and angles (°) for [Pd(h -ma)(HNꢀS Bu)]
and [Pd(h2-tcne)(HNꢀSMe)]
[Pd(h2-ma)(HNꢀStBu)]
[Pd(h2-tcne)(HNꢀSMe)]
Bond lengths
PdꢀS(1)
PdꢀN(1)
PdꢀC(11)
PdꢀC(12)
S(1)ꢀC(6)
S(1)ꢀC(7)
C(11)ꢀC(12)
O(2)ꢀC(13)
O(2)ꢀC(14)
2.328(1)
PdꢀS(1)
2.352(3)
2.118(3)
2.048(3)
2.063(3)
1.799(4)
1.832(3)
1.413(5)
1.397(4)
1.400(4)
PdꢀN(1)
S(1)ꢀC(6)
S(1)ꢀC(7)
PdꢀC(8)
PdꢀC(9)
C(8)ꢀC(9)
2.091(7)
1.817(9)
1.82(1)
2.085(9)
2.046(9)
1.48(1)
Bond angles
S(1)ꢀPdꢀN(1)
S(1)ꢀPdꢀC(11)
S(1)ꢀPdꢀC(12)
N(1)ꢀPdꢀC(11)
N(1)ꢀPdꢀC(12)
C(11)ꢀPdꢀC(12)
PdꢀS(1)ꢀC(6)
PdꢀS(1)ꢀC(7)
PdꢀN(1)ꢀC(1)
81.10(8) S(1)ꢀPdꢀN(1)
83.3(2)
160.5(2)
118.4(3)
116.2(3)
157.9(4)
42.1(4)
95.3(3)
102.5(4)
99.6(5)
162.8(1)
122.9(1)
115.8(1)
156.0(1)
40.2(1)
97.0(1)
116.4(1)
119.1(2)
S(1)ꢀPdꢀC(8)
S(1)ꢀPdꢀC(9)
N(1)ꢀPdꢀC(8)
N(1)ꢀPdꢀC(9)
C(8)ꢀPdꢀC(9)
PdꢀS(1)ꢀC(6)
PdꢀS(1)ꢀC(7)
C(6)ꢀS(1)ꢀC(7)
C(10)ꢀC(8)ꢀC(11)
C(12)ꢀC(9)ꢀC(13)
C(12)ꢀC(11)ꢀC(13) 108.0(3)
C(11)ꢀC(12)ꢀC(14) 106.6(3)
C(13)ꢀO(2)ꢀC(14)
115.4(8)
116.0(9)
108.4(2)
(Scheme 1) in chloroform. We hoped to relate the
resulting equilibrium and kinetic data to steric and
electronic properties of the chelating ligand, the coordi-
nated olefin, and the entering one.
Scheme 1.
2. Results and discussion
2.1. X-ray diffraction studies
The molecular structure of complex [Pd(h2-
ma)(HNꢀStBu] has been confirmed by X-ray crystallog-
raphy. The ORTEP diagram is shown in Fig. 1, while the
selected bond distances and angles are listed in Table 1.
The bidentate HNꢀStBu ligand is coordinated to
palladium and the coordination plane also comprises
the double bond (C(11)ꢁC(12)) of maleic anhydride.
The palladium is situated on the least-squares plane
defined by N,S,C(11) and C(12) atoms within a devia-
,
tion of 0.026 A from the plane. The coordinated anhy-
,
dride is virtually planar (maximum deviation 0.04 A by
O(2)) and makes a dihedral angle of 78.5° with the
mean coordination plane and 91.0° with the pyridine
ring.
The five-membered PdꢀN(1)ꢀC(1)ꢀC(6)ꢀS(1) ring as-
sumes an envelope conformation (Cs), with N(1), C(1)
and S(1) below the mean plane by −0.14, −0.07 and
Fig. 1. Molecular structure of [Pd(h2-ma)(HNꢀStBu)] in the crystal
(50% probability displacement ellipsoids for non-H atoms and circles
of arbitrary size for H atoms).
,
−0.26 A, respectively, while the Pd and C(6) atoms lie
,
above this plane by +0.19 and +0.28 A, respectively.

L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
3
The C(11)ꢀC(12) bond distance is significantly longer
back donation from Pd to tcne. The five-membered
,
(0.11 A) than in the free olefin, in line with other
chelate ring PdꢀS(1)ꢀC(6)ꢀC(5)ꢀN(1) adopts an envel-
,
Pd(0)–ma complexes (Ref. [4] and references therein).
ope (Cs) conformation with S(1) above (by 0.69 A) the
,
The Pd(0)ꢀS distance (2.328(1) A) is marginally
PdꢀN(1)ꢀC(5)ꢀC(6) plane. The PdꢀN(1) distance
,
,
,
shorter than the values of 2.365(1) [12] and 2.354(1) A
(2.091(7) A) agrees with the mean value (2.11 A) ob-
served for other 17 crystal structures [13] containing
both sulfur and N (sp2) donor atoms, while the PdꢀS(1)
[10] found in the two other complexes containing the
zero-valent metal, while it closely approaches the mean
,
,
distance (2.352(3) A) is remarkably longer than the
mean value (2.29 A) in the same complexes.
In the unit cell the molecules are well separated, the
value (2.323 A) encountered in 377 Pd(II)ꢀS entries
,
,
[13]. Analogously, the Pd(0)ꢀN distance (2.118(3) A) is
slightly shorter than those observed for Pd(0)ꢀN in the
complexes reported so far (2.13 [14] and 2.16 A [15]).
The remaining bond distances are in the expected range
and deserve no comment.
,
,
shortest intermolecular interaction (2.59 A) being be-
tween the N(2) atom and the hydrogen at C(1) of the
molecule at 2−x, 1−y, 2−z.
An ORTEP diagram of the molecular structure of
[Pd(h2-tcne)(HNꢀSMe)] is shown in Fig. 2, while the
selected bond distances and angles are listed in Table 1.
This complex represents the sixth example of an
X-ray structure containing the Pd(0)(tcne) fragment
[12,16]. The CꢁC bond of h2-coordinated tcne lies in
the coordination plane and the palladium atom is situ-
ated on the least-squares plane defined by S(1), N(1),
2.2. NMR spectra and solution beha6ior
1
Selected H-NMR data at low temperature for the
h2-olefin–Pd(0) complexes under study are listed in
Tables 2 and 3, whereas 1H- and 13C{1H}-NMR data at
room temperature are reported in the Section 4.
It is convenient to distinguish the metal species on
the basis of the type of olefin involved, i.e. symmetri-
cally tetra-substituted (tcne, tmetc), type E (fn), and
type Z (ma, nq). The corresponding complexes together
with their diastereoisomers (when present) are shown in
Scheme 2.
,
C(8) and C(9) within a deviation of 0.04 A from the
plane; the slight distortion from square planarity
around the Pd center is reflected by the dihedral angle
of 6.0° between PdꢀS(1)ꢀN(1) and PdꢀC(8)ꢀC(9)
planes. Although the distances of PdꢀC(8) and PdꢀC(9)
are slightly different from each other, they are close to
those found in previous structures (in the range 2.054–
2.2.1. Symmetric olefins
The low-temperature H-NMR spectra of complexes
1
,
2.111 A) [12,16]. The coordinated tcne is non-planar
bearing these olefins display two characteristic features,
namely an AB quartet ascribable to the CH2S endo-
cyclic protons and four singlets from the four different
carboxylate methyl protons (in the case of ol=tmetc).
These observations point to the presence of one single
isomer, the enantiomeric forms due to the sulfur abso-
lute configuration going undetected under our experi-
mental conditions. Moreover, this evidence rules out a
possible distinction between the two conformers arising
from conformational flexibility of the five-membered
N,S-chelate ring.
and each cyano group is bent away from the Pd; the
dihedral angle between two planes, one plane contain-
ing N(2), C(10), C(8), C(11) and N(3) and the other
containing N(4), C(12), C(9), C(13) and N(5), is 127.7°.
,
The CꢁC bond distance (1.49(1) A) is longer than that
,
of the uncoordinated one [17] by 0.15 A, as a result of
2.2.2. Type E olefins
In the case of ol=fn two diastereoisomers are possi-
ble, namely the Re and Si species referred to the olefin
face coordinated to the metal center. Accordingly, the
1H-NMR spectra at low temperature should show two
AB systems due to CH2S and two further AB systems
due to olefin protons. The isomer relative population
depends on the substituents R and R% (Tables 2 and 3).
However, the isomers Re and Si were not distin-
guishable.
2.2.3. Type Z olefins
As can again be seen in Scheme 2, in the case of
complexes of Z-type olefins (ma, nq), two distinct
diastereoisomers (together with their undetected enan-
Fig. 2. Molecular structure of [Pd(h2-tcne)(HNꢀSMe)] in the crystal
(50% probability displacement ellipsoids for non-H atoms and circles
of arbitrary size for H atoms).

4
L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
Table 2
Selected 1H-NMR data for [Pd(h2-ol)(R%NꢀSR)] at low temperaturea
Complex
CH2ꢀS
Olefin protons
R, R% or H6 (characteristic
signals)
Stereoisomers
ratio
[Pd(h2-fn)(HNꢀSMe)]
[Pd(h2-fn)(HNꢀSEt)]
Pd(h2-fn)(HNꢀSiPr)]
Pd(h2-fn)(HNꢀStBu)]
[Pd(h2-fn)(HNꢀSPh)]
A%=4.16 B%=4.04 JAB=16.7
A%%=4.25 B%%=4.08 JAB=16.5
A%=4.24 B%=4.41 JAB=16.4
A%%=4.15 B%%=4.13 JAB=16.1
A%=4.26 B%=4.16 JAB=16.7
A%%=4.20 B%%=4.16 JAB=16.7
Not resolved
A%=3.07 B%=3.02 JAB=9.5
A%%=3.09 B%%=2.98 JAB=9.4
A%=3.10 B%=3.02 JAB=9.4
A%%=3.09 B%%=2.98 JAB=9.4
A%=3.11 B%=2.99 JAB=9.3
A%%=3.10 B%%=3.02 JAB=9.4
A%=3.11 B%=2.98 JAB=9.5
A%%=3.07 B%%=3.02 JAB=9.2
A%=3.19 B%=3.16 JAB=9.4
A%%=3.22 B%%=3.14 JAB=9.4
A%=3.19 B%=3.11 JAB=9.5
A%%=3.17 B%%=3.13 JAB=9.4
Not resolved
CH3, 2.22, 2.30
1.55:1
1:1
CH2CH3, 2.76, 1.28 (t), 2.62
CH(CH3)2, 3.05, 1.30
C(CH3)3, 1.37, 1.35
2:1
2:1
A%=4.58 B%=4.44 JAB=16.5
A%%=4.58 B%%=4.41 JAB=16.5
1.25:1
2:1
[Pd(h2-fn)(MeNꢀSPh)] A%=4.58 B%=4.49 JAB=16.4
A%%=4.54 B%%=4.57 JAB=16.4
CH3, 2.77, 2.81
[Pd(h2-nq)(HNꢀSMe)] A%=4.08 B%=3.96 JAB=16.4
A%%=4.08 B%%=3.94 JAB=16.4
CH3, 1.89 (s), 2.32 (s)
1.6:1
3:1
[Pd(h2-nq)(HNꢀSEt)]
A%=4.08 B%=3.92 JAB=16.5
A%=4.77 B%=4.71 JAB=6.9
CH2CH3, 2.33 (m) 0.7 (t),
2.80 (m) 1.3 (t)
A%%=4.15 B%%=4.02 JAB=16.5
A%=4.16 B%=3.88 JAB=16.8
A%%=4.75 B%%=4.69 JAB=6.9
A%=4.78 B%=4.67 JAB=6.7
[Pd(h2-nq)(HNꢀSiPr)]
CH(CH3)2, 2.84 (bs) 0.93
(bd), 0.42 (bd), 3.24 (bs)
1.35 (bd), 1.30 (bd)
2.6:1
A%%=4.16 B%%=4.02 JAB=16.5
A%%=4.78 B%%=4.70 JAB=6.7
A%=4.78 B%=4.66 JAB=6.9
A%%=4.74 B%%=4.66 JAB=6.9
Not resolved
4.82 (bs)
A%=4.85 B%=4.70 JAB=7.1
[Pd(h2-nq)(HNꢀStBu)] 4.07 (bs)
C(CH3)3, 0.89, 1.43
1.7:1
2:1
4.04
Not resolved
[Pd(h2-nq)(HNꢀSPh)]
4.33 (bs)
[Pd(h2-nq)(MeNꢀSPh)] Not resolved
CH3, 2.76 (s), 2.58 (s)
1.9:1
1:0.8
4.36 (bm)
A%%=4.79 B%%=4.65 JAB=7.2
b
b
[Pd(h2-ma)(HNꢀSMe)]
CH3H6, 2.18, 8.67, 2.20, 8.80
b
b
b
b
[Pd(h2-ma)(HNꢀSEt)]
CH2CH3H6, 2.67 (bm) 1.17 (t) 2.25:1
8.67, 2.48 (bm) 1.25 (t) 8.76
b
[Pd(h2-ma)(HNꢀSiPr)]
CH(CH3)2H6, 2.91 (bm) 1.30
(bd) 8.6, 3.05 (bm) 1.14 (d) 8.3
C(CH3)3, 1.26, 1.36
2:1
b
[Pd(h2-ma)(HNꢀStBu)]
1.8:1
1.4:1
2:1
[Pd(h2-ma)(HNꢀSPh)]
4.47 (bs)
4.17 (bs)
A%=4.20 B%=4.13 JAB=3.8
A%%=4.20 B%%=4.17 JAB=3.8
H6, 8.66, 8.77
CH3, 2.77 (s), 2.70 (s)
[Pd(h2-ma)(MeNꢀSPh)] 4.46 (bs)
4.52 (bs)
a A%, B%=chemical shift (in ppm) more abundant diastereoisomer; A%%, B%%=chemical shift (in ppm) less abundant diastereoisomer; JAB=cou-
pling constant (in Hz) AB systems.
b ꢁCH2ꢀS and olefinic protons are almost isochronous and therefore not resolved.
tiomers) are possible, namely the exo and endo rotamers
related to the mutual orientations of the group X within
the olefin cycle with respect to the sulfur substituent R.
Accordingly, two couples of AB systems are observed.
Moreover, an unequal isomer distribution population
(Tables 2 and 3) is observed in almost all cases. The
relative position of groups X and R was not determined.
ligand rotation and rearrangement (olefin pseudo-
rotation);
5. ancillary ligand intermolecular exchange.
Although these mechanisms are not equivalent, an ap-
propriate combination of two of them is sufficient to
explain the observed fluxionality of each species.
For symmetric olefin complexes (ol=tcne, tmetc),
increasing the temperature causes the collapse of the
CH2S AB system accompanied by reduction to two of
the initially four singlets belonging to methylcarboxyl-
ato protons. This phenomenon, which is independent of
sample concentration, can only arise from inversion of
the stereogenic coordinated sulfur (mechanism (1))
[10,18].
2.2.4. Fluxional beha6ior
On increasing the temperature, all complexes undergo
two distinct fluxional processes, which can be inter-
preted by the following different mechanisms:
1. inversion of sulfur configuration;
2. olefin rotation (propeller-like);
3. Pd–olefin bond cleavage and recombination;
4. PdꢀN or PdꢀS bond cleavage followed by ancillary
This behavior is similar to that observed for Pd(II)
complexes, in which sulfur inversion is the only possible

L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
5
t
mechanism [19]. One might argue that comparison
among mechanisms involving palladium atoms in dif-
ferent oxidation states is not warranted. However, in
our experience we noticed that sulfur inversion is al-
ways the first fluxional phenomenon occurring in any
Pd complex bearing pyridin-thioether ligands and that
the solution behavior of Pd(0) complexes containing
electron-withdrawing olefins is similar in many respects
to that of Pd(II) complexes [1g].
On increasing the temperature further, the collapse of
the surviving singlets is observed. Any of the proposed
mechanisms combined with mechanism (1) is consistent
with the increase in molecular symmetry.
substituents (R=iPr, Bu), we cannot exclude a con-
comitant dissociation mechanism due to steric interac-
tion between the bulky R groups and the hindered
olefin tmetc [9,11,20].
As for the complexes with E-type olefins such as fn,
which turns out to be more strongly bound and less
sterically hindered than tmetc (see below), their flux-
ional behavior is somewhat more complicated and less
diagnostic than the previously described cases. Sulfur
inversion brings about the interchange between the
diastereoisomers (Scheme 2) with concomitant reduc-
tion to two of the four AB systems (two arising from
CH2ꢀS endocyclic protons and two from olefinic pro-
tons). Propeller-like olefin rotation is probably the next
process taking place on increasing the temperature.
Indeed, such rotation will not alter the chirality of
palladium (persistence of the Si or Re face for coordi-
nated olefins). Thus, one would expect to observe the
persistence of an AB system for CH2ꢀS protons while
the olefin proton AB system disappears (combination
of mechanisms (1) and (2)). This is clearly borne out by
[Pd(h2-fn)(MeNꢀSPh)] and [Pd(h2-fn)(HNꢀSEt)], in
which the CH2ꢀS proton AB system barely persists at
T:273 and 296 K, respectively, while the olefin pro-
tons give rise to a singlet (l=3.16 and 3.09 ppm,
respectively). This finding rules out any of the dissocia-
tive mechanisms (3) or (5) (Fig. 3).
However, we propose the view that the second ob-
served fluxional phenomenon involves propeller-like
rotation of the olefin, or olefin pseudo-rotation (mecha-
nism (4)), which in this case cannot a priori be ruled
out. In the case of the more sterically demanding
Table 3
Selected 1H-NMR signals at low temperature for complexes [Pd(h2-
tcne)(R%NꢀSR)] and [Pd(h2-tmetc)(R%NꢀSR)]
Complex
CH2ꢀS
COOCH3
[Pd(h2-tcne)(HNꢀSMe)]
[Pd(h2-tcne)(HNꢀSEt)]
[Pd(h2-tcne)(HNꢀSiPr)]
[Pd(h2-tcne)(HNꢀStBu)]
[Pd(h2-tcne)(HNꢀSPh)]
[Pd(h2-tcne)(MeNꢀSPh)]
A=4.38 B=4.13
J
AB=16.8
A=4.35 B=4.19
AB=17.1
A=4.34 B=4.22
AB=16.9
A=4.34 B=4.27
AB=17.1
A=4.69 B=4.53
AB=16.8
A=4.70 B=4.64
AB=16.8
[Pd(h2-tmetc)(HNꢀSMe)] A=4.26 B=4.04
AB=16.8
J
As for complexes bearing Z-type olefins, again two
rotamers (exo and endo) along with their enantiomers
are expected (Scheme 2). Sulfur inversion causes the
disappearance of two of the four AB systems. The
olefin rotation ensuing from a further increase in tem-
perature (which will convert exo into endo forms and
vice versa) coupled to the persisting sulfur inversion will
explain the symmetry of 1H-NMR spectra at higher
temperatures.
J
J
J
J
3.62
J
3.60
3.58
3.57
3.61
3. Olefin substitution rate and equilibria
[Pd(h2-tmetc)(HNꢀSEt)]
A=4.28 B=4.11
AB=16.8
J
3.1. Olefin substitution rate constants
3.59
3.58
3.57
3.56 (2 Me)
The rate of approach to equilibrium (1)
[Pd(h2-tmetc)(HNꢀSiPr)]
A=4.29 B=4.15
AB=16.6
[Pd(h2-nq)(R%NꢀSR)]+tmetc
J
A
B
X [Pd(h2-tmetc)(R%NꢀSR)]+nq
(1)
3.60 (2 Me)
3.58 (3 Me)
[Pd(h2-tmetc)(MeNꢀStBu)] A=4.23 B=4.13
AB=15.2
C
D
J
in chloroform at 25°C was determined by UV–vis
spectrophotometric techniques. Spectral changes with
time were monitored in the range 540–300 nm in the
presence of a constant excess of tmetc over the metal
substrate ([Pd]0=1×10−4 mol dm−3), in order to
provide pseudo-first order conditions and to minimize
the contribution of the reverse reaction (k−2) to the
overall spectral changes. Under these conditions the
absorbance Dt obeys the mono-exponential rate law
Dt=Dꢁ+(D0−Dꢁ) exp(−kobst), where D0, Dꢁ and
3.54 (1Me)
3.62 (2 Me)
[Pd(h2-tmetc)(HNꢀSPh)]
A=4.59 B=4.45
AB=16.5
J
3.56 (1 Me)
3.33 (1 Me)
3.62
[Pd(h2-tmetc)(MeNꢀSPh)] A=4.57 B=4.51
AB=16.5
J
3.59
3.58
3.28

6
L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
Scheme 2.
kobs are the initial, final absorbance, and the observed
rate constant, respectively. The kobs values, determined
by non-linear regression where D0, Dꢁ and kobs are the
parameters to be optimized, fit the expression
−d[A]/dt=k2[A]([B]0−[A]0+[A])−k−2([A]0−[A])2
(3)
where [A]0 and [B]0 are initial concentrations and [C]=
[D]=[A]0−[A]=[B]0−[B]. The absorbance was given
by
kobs=k2[tmetc]
(2)
Dt=mA[A]+mC[C]+mD[D]
(4)
The resulting values for k2 are listed in Table 4.
The k−2 parameters were determined by carrying out
kinetic runs under second-order conditions in both
directions, with tmetc concentrations comparable to
(mB$0 in the wavelength range examined), where the
species concentrations are derived from integration of
Eq. (3) [3] and the relevant mass-balance equations.
Non-linear regression of Dt values was carried out
using k−2 as the parameter to be optimized, with the k2
term being held fixed at the value determined earlier
under pseudo-first-order conditions. This allowed re-
those of the metal complex ([Pd]=1×10−4 mol dm−3
,
[tmetc]=1×10−4–6×10−4 mol dm−3). Absorbance
data were fitted to time according to the rate model for
second-order reversible reactions [3]:

L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
7
moval of the strong correlation between k2 and k−2
,
compatible with slow decomposition phenomena. On
the other hand, the reverse reaction of [Pd(h2-
tmetc)(HNꢀStBu)] with excess free nq could not be
monitored owing to unfavorable spectral features (viz.
the overly high extinction coefficients of nq).
From Table 4 it appears that both k2 and k−2 are
affected by the steric hindrance of the R substituent at
the thioetheric sulfur. An LFER of log k2 versus the
front strain steric parameter S of R [21] is shown in
Fig. 4.
which is peculiar to the model being fitted and would
unfavorably affect the convergence rate of the fitting
procedure. The k−2 values are listed in Table 4, in
which the equilibrium constants KE for Eq. (1), as the
ratios k2/k−2, are also reported. In the case of complex
[Pd(h2-nq)(HNꢀStBu)], which reacts very slowly with
tmetc, only pseudo-first-order conditions for the for-
ward reaction could be employed to achieve conversion
to an appropriate extent in a reasonable time period
Fig. 3. Selected 1H-NMR spectra of [Pd(h2-fn)(MeNꢀSPh)] in CD2Cl2 at different temperatures.
Table 4
Second-order rate constants for the forward and reverse reactions (k2 and k−2) and calculated equilibrium constants (KE) for equilibrium reaction
(1); equilibrium constants for olefin substitution reactions (reaction (5)) in CHCl3 at 25°C
Complex
tmetc
KE
k2 ( mol−1 dm3 s−1
)
k−2 (mol−1 dm3 s−1
)
tmetc (k2/k−2
)
fn
1791
ma
[Pd(h2-nq)(HNꢀSMe)]
[Pd(h2-nq)(HNꢀSEt)]
[Pd(h2-nq)(HNꢀSiPr)]
[Pd(h2-nq)(HNꢀStBu)]
[Pd(h2-nq)(HNꢀSPh)]
[Pd(h2-nq)(MeNꢀSPh)]
6495
42917
7.592.5
2.190.3
0.0590.03 a
14.695
1.590.6
1.990.6
0.790.1
0.690.4 a
0.590.7
0.890.2
1891
1692
991
6.990.4
7.290.3
4994
14.690.5
1.4090.06
(2.9590.04)10−2
6.790.2
1292
6.790.4
5.590.2
8.490.9
1691
1.790.1
2.290.5
a Calculated values (see text).

8
L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
pected. Steric hindrance to approach by the entering
olefin is also exerted by the R% substituent in position 2
of the pyridine ring (cf. k2 and k−2 for R%NꢀSR,
R%=H, Me, R=Ph). This is compounded by some
rate-depressing effect due to the donor ability of the Me
group, which is expected to disfavor formation of the
18-electron bis-olefin-activated complex through in-
creased basicity of the pyridine nitrogen. However, the
contributions of these phenomena to the overall rate
effect are hard to untangle. The KE values for equi-
librium in Eq. (1), obtained as the rate constant ratios
k2/k−2 (Table 4), are close to unity in all cases, as
expected on the basis of the similar stability of the two
Pd(0)–olefin complexes involved as far as this is gov-
erned by the electron-withdrawing ability of the olefin
substituents. This feature seems to be hardly affected by
the bidentate ligand since it also occurs with other
complexes [3].
Fig. 4. Plot of log k2 for the reaction of [Pd(h2-nq)(HNꢀSR)] with
tmetc vs. the front strain steric parameter S of substituent R.
3.2. Olefin substitution equilibrium constants
On the other hand, changes in electronic effects on
changing R are hardly likely to affect the activation
process of olefin attack. This suggests that these pro-
cesses of olefin substitution are essentially associative in
nature. This is confirmed by the comparatively low
activation enthalpy (DHc =10.290.5 kcal mol−1) and
fairly negative activation entropy (DSc = −2492 cal
Equilibrium constants for the reactions
[Pd(h2-nq)(R%NꢀSR)]+ol X [Pd(h2-ol)(R%NꢀSR)]+nq
1
2
(ol=ma, fn)
(5)
in CHCl3 were determined by recording spectral
changes in the range 300–600 nm of mixtures obtained
by adding appropriate microaliquots of solutions of ol
to a solution of 1 ([Pd]0 ca. 1×10−4 mol dm−3) in the
thermostatted cell compartment of the spectrophotome-
ter. The equilibria were rapidly established. Absorbance
data were analyzed at 400 nm where the change in
absorbance was the largest and the olefins ol and nq do
not absorb appreciably.
Under these conditions abstract factor analysis [22]
of the observed spectral changes indicated that at most
two independently absorbing species were present, i.e.
complexes 1 and 2. The absorbance data Du were fitted
by non-linear least-squares according to the model
mol−1
K
−1) for the k2 step relating to [Pd(h2-
nq)(HNꢀSiPr)] reacting with tmetc, as deduced from the
temperature dependence of k2 in the range 15–45°C
analyzed with the Eyring equation. Similar activation
parameters had been determined for olefin substitution
in analogous [Pd(h2-ol)(N–N%)] complexes reacting
with tmetc (ol=nq, dmf; N–N%=2-NC5H4CHꢁ
NC6H4OMe-4) [3]. The low activation enthalpy and the
highly negative activation entropy found for these reac-
tions are in agreement with an associative mechanism
in which both the entering and the leaving olefins are
present in an 18-electron transition state of an activa-
tion process involving considerable freezing of degrees
of freedom. Associative mechanisms involving a bis-
olefin-activated state have been proposed for olefin or
alkyne substitution or exchange in Pd and Pt zero-
valent complexes [4–7]. Similar adverse effects of the
steric requirements of R are observed for the reverse
reaction path k−2, although the lack of the value for
R=tBu limits the LFER to only three experimental
KE=[2][nq]/[1][ol]
[Pd]tot=[1]+[2]
[nq]+[ol]=[nq]0+[ol]0
[nq]=[nq]0+[2]
Du=m1[1]+m2[2]
i
points (R=Me, Et, Pr).
A gross estimate of k−2 (R=tBu) can be attempted
by extrapolation of the straight line to the appropriate
front strain parameter. The ensuing value is fairly close
to that determined from equilibrium and kinetic data,
as described below. Activation parameters for k−2 are
very close to those for the forward step k2, indicating a
common associative mechanism for both paths, as ex-
The parameters to be optimized were KE and m2. The
latter was either held constant at the experimentally
accessible value (from the spectrum of complex 2 inde-
pendently prepared) or allowed to float during the
iterative process. In the latter case the final, optimized
value turned out to coincide with that determined di-
rectly (Fig. 5).

L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
9
3.3. Ligand exchange equilibrium constants
We devised a procedure to evaluate the olefin ex-
change equilibrium constant KE for the reaction of
[Pd(h2-nq)(HNꢀStBu)] with tmetc by the use of the
following equilibrium network:
Fig. 5. Fit of absorbance at 400 nm to [fn] for the reaction of
The appropriate K* data were available from our previ-
ous work [3]. The ligand exchange equilibrium con-
E
[Pd(h2-nq)(HNꢀSiPr)] with fn in CHCl3 at 25°C.
stants Kexc and K* (ol=tmetc) were determined by
exc
spectrophotometric titration involving addition of ap-
propriate aliquots of CHCl3 solutions of HNꢀStBu to
solutions of [Pd(h2-fn)(N–N%)] or [Pd(h2-tmetc)(N–N%)]
([Pd]0 ca. 1×10−4 mol dm−3). Absorbance data were
analyzed according to a procedure analogous to that
described above for the olefin substitution equilibria.
The KE values are also listed in Table 4.
As can be seen, the KE values cover a narrow range,
spanning at most one order of magnitude. In particular,
the complexes with ma and fn are in general more
stable (KEꢂ1) than those of nq, thanks to the higher
electron-withdrawing ability of the former olefins, ma
being more efficient than fn in this respect. This behav-
ior is in agreement with our previous findings about
olefin exchange in [Pd(h2-ol)(a-diimine)] complexes [3].
Changing the bidentate ligand from 2-NC5H4CHꢁ
NC6H4OMe-4 to the present pyridin-thioether ligands
does not significantly affect the olefin exchange equi-
librium constants, other things being equal. However a
moderate adverse effect of the steric requirement of the
sulfur alkyl substituent (R) can be detected for both ma
and fn. This might indicate that some sort of leveling in
the electron-withdrawing properties of the olefins in-
volved takes place, due to steric hindrance that over-
comes the increasing electron-releasing ability of R,
which would be expected to enhance the stability of
complexes containing the more electronegative olefins
ma and fn [23].
The resulting Kexc and K* are 791 and 2.590.6(ol=
exc
tmetc). Since K* (ol=tmetc)=0.2890.17 [3], relation-
E
ship (8) yields KE=0.1090.07.
This calculated value combined with the measured
one (KE=5.590.2 Table 4; referring to the exchange
reaction between [Pd(h2-nq)(HNꢀStBu)] and fn) yields
the equilibrium constant for the non-directly accessible
case, in which tmetc exchanges with nq when the
pyridin-thioether ligand is HNꢀSꢀtBu (see Table 4).
In the case of ol=nq, ma, the K* and KE values
E
were available from our previous work [3] and the
present work, respectively (Table 4), so that Eqs. (7)
and (8) were used to evaluate K* . The ensuing K*
exc
exc
values are 592 (ol=nq) and 593 (ol=ma). These
data indicate that the relative bonding abilities of
HNꢀStBu and 2-NC5H4CHꢁNC6H4OMe-4 ligands for
these Pd(0) moieties are almost independent of olefin
and confined in a very narrow interval, thereby reflect-
ing the observed feature in the case of Pd(II) h3-allyl
complexes [1g,h].
The discriminating effect of the higher electron
affinity [23] of ma and fn is clearly borne out when an
electron-donor methyl substituent is introduced into
position 2 of the pyridine ring in complexes with R=
Ph (cf. Table 4). As for the displacement of nq by
tmetc, steric and electronic effects are much harder to
discuss owing to the narrow range covered and the
large uncertainties arising from the kinetic origin of the
KE values.
The KE value for ol=tmetc, as deduced from net-
work (7) and reported in Table 4 as a calculated value
(0.690.4), allows us to evaluate the k−2 rate constant
for the reaction of [Pd(h2-tmetc)(HNꢀStBu)] with nq
from the rate constant k2 for the reverse reaction (Table
4). The resulting value (0.0590.04 mol−1 dm3 s−1) is
in good agreement with that grossly estimated from the
LFER based on front strain steric parameters S (see
above) [21].

10
L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
4. Experimental
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.02 (2H, s);
SꢀCH2, 2.57 (2H, q, J=7.4 Hz); SCH2ꢀCH3, 1.06 (3H, t,
J=7.4 Hz); HCꢁCH, 4.93 (2H, s, Hg); H3, H5, 7.35 (2H,
m); H4, 7.75 (td, J=7.7, 1.7 Hz); H6, 8.47 (d, J=5.3
Hz); Hf, 7.48 (2H, m); He, 8.04 (2H, m). 13C{1H}-NMR
(in CDCl3, r.t.), l (ppm): CH2ꢀS, 41.6; SꢀCH2, 31.27;
SCH2ꢀCH3, 13.98; C2, 158.0; C3, 125.1; C4, 138.2; C5,
123.1; C6, 150.2; HCꢁCH, 64.6 (Cg); Ce, 124.3 (2C); Cf,
131.2 (2C).
The pyridin-thioether ligands (R%NꢀSR) [1g] and the
complex Pd2(DBA)3·CHCl3 [24] were prepared accord-
ing to published procedures. All other chemicals were
commercial grade and were purified or dried, where re-
quired, by standard methods [25].
4.1. Preparation of complexes [Pd(p2-ol)(R%NꢀSR)]
4.1.3. [Pd(p2-nq)(HNꢀSiPr)]
The synthesis, the complete characterization and ele-
mental analysis of the complexes [Pd(h2-fn)(R%NꢀSR)]
(R%=H, R=Et, tBu, Ph; R%=Me, R=Ph) are reported
elsewhere [1f,g]. However a standard preparative proce-
dure is reported here for [Pd(h2-nq)(HNꢀSMe)]. Because
of the straightforward method of preparation, all com-
plexes under study can be completely characterized by
their multinuclear NMR spectral data and by their pecu-
liar IR features. Therefore we only report herein the ele-
mental analysis of some representative complexes.
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (orange microcrystals, yield
86%). IR (in KBr) (cm−1): wCꢁO, 1632, 1616; wCꢁN, 1585.
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.03 (2H,
bs); SꢀCH, 2.96 (1H, sept, J=6.7 Hz); CH(CH3)2, 1.09
(6H, bs); HCꢁCH, 4.91 (2H, bs, Hg); H3, H5, 7.4 (2H,
m); H4, 7.75 (td, J=7.7, 1.7 Hz); H6, 8.46 (d, J=5.0
Hz); He, 8.04 (2H, m); Hf, 7.48 (2H, m). 13C{1H}-NMR
(in CDCl3, r.t.), l (ppm): CH2ꢀS, 41.4; SꢀCH, 40.5;
CH(CH3)2, 22.5; C2, 158.5; C3, 125.1; C4, 138.14; C5,
124.2; C6, 149.8; HCꢁCH, 61.84 (Cg); Ce, 124.2; (2C); Cf,
131 (2C).
4.1.1. [Pd(p2-nq)(HNꢀSMe)]
To a solution of HNꢀSMe (0.06 g, 0.44 mmol) in an-
hydrous acetone (10 cm3) Pd2DBA3·CHCl3 (0.21 g, 0.2
mmol) and naphthoquinone (0.07 g, 0.44 mmol) were
added under nitrogen. The reaction mixture was stirred
for 1 h and the initial dark suspension turned to orange–
red. Addition of activated charcoal and filtration on
Celite removed metallic palladium yielding an orange–
red solution. Reduction to small volume (3–4 cm3) and
addition of diethyl ether (15 cm3) gave an orange precip-
itate, which was filtered off and washed with diethyl
ether in excess to remove the free DBA. The crystals
were dried under vacuum and stored under inert atmo-
sphere (orange microcrystals, 0.12 g, yield 75%). Found:
C, 50.72; H, 3.55; N, 3.38. C17H15NO2SPd requires: C,
4.1.4. [Pd(p2-nq)(HNꢀStBu)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (orange microcrystals, yield
83%). IR (in KBr) (cm−1): wCꢁO, 1628 (s), 1587 (s); wCꢁN
1
obscured. H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS,
4.03 (2H, s); C(CH3)3, 1.22 (9H, s); HCꢁCH, 4.87, 4.89
(2H, Hg, bs); H3, 7.4 (1H, d, J=7.6 Hz); H4, 7.75 (td,
J=7.6, 1.2 Hz); H5, 7.5 (partially obscured by H3); H6,
8.5 (d, J=5.1 Hz); He, 8.03 (2H, m); Hf, 7.47 (2H, m).
13C{1H}-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 38.7;
C(CH3)3, 48.9; C(CH3)3, 30.1 (3C); C2, 158.7; C3, 124.2;
C4, 138.1; C5, 122.6; C6, 149.7; HCꢁCH, 60.7, 66.1 (2C,
Cg); Ce, 124.8, 125.3 (2C); Cf, 131.0, 131.3 (2C).
50.57; H, 3.74; N, 3.47%. IR (in KBr) (cm−1): wCꢁO
,
1
1626, 1610 (d)): wCꢁN, 1581 (s), 1556 (s). H-NMR (in
CDCl3, r.t.), l (ppm): CH2ꢀS, 4.00 (2H, s); SꢀCH3, 2.18
(3H, s); HCꢁCH, 4.94 (2H, s, Hg); H3, H5, 7.38 (2H, m);
H4, 7.77 (td, J=7.7, 1.7 Hz); H6, 8.51 (d, J=5.7 Hz);
He, 8.04 (2H, m); Hf, 7.48 (2H, m). 13C{1H}-NMR (in
CDCl3, r.t.), l (ppm): CH2ꢀS, 43.6; SꢀCH3, 20.0; C2,
157.1; C3, 124.7; C4, 137.9; C5, 123.2; C6, 150.4;
HCꢁCH, 65.0 (2C, Cg, broad); Ce, 124.2 (2C); Cf, 131.0
(2C).
4.1.5. [Pd(p2-nq)(HNꢀSPh)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (dark orange microcrystals, yield
84%). IR (in KBr) (cm−1): wCꢁO, 1620, 1626; wCꢁN, 1586
(s) 1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.33
(2H, s); HCꢁCH, 4.96 (2H, Hg, s); H3, H5, Hb, Hc, Hd,
7.25 (7H, m); H4, 7.73 (td, J=7.7, 1.7 Hz); H6, 8.51 (d,
J=5.3 Hz); He, 8.00 (2H, m); Hf, 7.47 (2H, m).
13C{1H}-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 46.25;
Ca (obscured); Cb, 129.0; Cc, 131.1; Cd, 128.6; C2, 156.9;
C3, 124.1; C4, 137.9; C5, 122.8; C6, 148.8; HCꢁCH (ob-
scured); Ce, 125.0 (2C); Cf, 131.4 (2C).
4.1.2. [Pd(p2-nq)(HNꢀSEt)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (red–brown microcrystals, yield
84%). IR (in KBr) (cm−1): wCꢁO, 1625 (s); wCꢁN, 1587 (s).

L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
11
4.1.6. [Pd(p2-nq)(MeNꢀSPh)]
4.1.10. [Pd(p2-ma)(HNꢀStBu)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (red–brown microcrystals, yield
79%). IR (in KBr) (cm−1): wCꢁO, 1639, 1630; wCꢁN, 1589,
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.32 (2H,
s); pyrꢀCH3, 2.81 (3H, s); HCꢁCH, 4.9 (2H, s Hg); H4,
7.56 (t, J=8.0 Hz); H5, 7.07 (d, J=8.0 Hz); H3, Hb,
Hc, Hd, 7.27 (6H, m); He, 7.98 (2H, m); Hf, 7.50 (2H,
m). 13C{1H}-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS,
47.0; pyrꢀCH3, 28.2; Cb, 129.2; Cc, 131.5; Cd, 128.9; C2,
159.0; C3, 123.7; C4, 137.9; C5, 120.4; C6, 156.5; Ce,
125.7, 125.3 (2C); Cf, 131.3, 132.2 (2C); CꢁO, 185.4.
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
86%). IR (in KBr) (cm−1): wCꢁO, 1790 (s), 1724 (s);
1
wCꢁN, 1601. H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS,
4.17 (2H, s); SꢀC(CH3)3, 1.42 (9H, s,) HCꢁCH, 4.14
(2H, s); H3, 7.49 (d, J=7.8 Hz); H4, 7.82 (td, J=7.8,
1.7 Hz); H5 (dd, J=7.8, 5.2 Hz); H6, 8.82 (d, J=5.2).
13C{1H}-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 39.1;
SꢀC(CH3)3, 48.9; C(CH3)3, 30.5; HCꢁCH, 45.5; C2,
158.6; C3, 124.1; C4, 138.4; C5, 123.0; C6, 153.0.
4.1.11. [Pd(p2-ma)(HNꢀSPh)]
4.1.7. [Pd(p2-ma)(HNꢀSMe)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)]. (yellow microcrystals, yield
82%) IR (in KBr) (cm−1): wCꢁO, 1791, 1724; wCꢁN, 1597.
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.45 (2H,
s); HCꢁCH, 4.26 (2H, s); H3, H5, Hc, Hd, 7.37 (5H, m);
Hb, 7.57 (2H, m); H4, 7.80 (td, J=7.7, 1.7 Hz); H6, 8.86
(d, J=5.3 Hz). 13C{1H}-NMR (in CDCl3, r.t.), l
(ppm): CH2ꢀS, 47.2; HCꢁCH, 47.0; Cb, 129.7; Cc,
131.8; Cd, 129.4; C3, 129.4; C4, 138.5; C5, 123.4; C6,
153.1.
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
80%). Found: C, 38.81; H, 3.05; N, 4.02. C11H11-
NO3SPd requires: C, 38.44; H, 3.23; N, 4.08%. IR (in
KBr) (cm−1): wCꢁO, 1795 (s), 1722 (s); wCꢁN, 1599,
1H-NMR (in CDCl3, r.t.), l (ppm): CH2S, 4.11 (2H, s);
SꢀCH3, 2.34 (3H, s); HCꢁCH, 4.17 (2H, s); H4, 7.84
(td, J=7.7, 1.7 Hz); H3, 7.5 (d, J=7.7 Hz); H5, 7.35
(dd, J=7.7, 5.2 Hz); H6, 8.85 (d, J=5.2 Hz). 13C{1H}-
NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 44.0; SꢀCH3,
19.8; HCꢁCH, 46.0; C2, 156.9; C3, 124.0; C4, 138.2; C5,
123.7; C6, 153.0; CꢁO, 71.5.
4.1.12. [Pd(p2-ma)(MeNꢀSPh)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
86%). IR (in KBr) (cm−1): wCꢁO, 1794 (s), 1726 (s);
4.1.8. [Pd(p2-ma)(HNꢀSEt)]
1
wCꢁN, 1601. H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS,
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield 75%)
(decomposes slowly in the solid and in chlorinated
4.49 (2H, s); pyrꢀCH3, 2.88 (3H, s); HCꢁCH, 4.23 (2H,
s); H3, Hb, Hc, Hd, 7.43 (6H, m); H4, 7.66 (t, J=8.0
Hz); H5, 7.21 (d, J=8.0 Hz). 13C{1H}-NMR (in
CDCl3, r.t.), l (ppm): CH2ꢀS, 46.7; pyrꢀCH3, 29.1;
HCꢁCH, 45.6; Cb, 129.3; Cc, 131.3; Cd, 129.0; C2,
161.1; C3, 123.6; C4, 138.0; C5, 120.3; C6, 156.4.
solvents). IR (in KBr) (cm−1): wCꢁO, 1790, 1724; wCꢁN
,
1
1598. H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.13
(2H, s); SꢀCH2, 2.73 (2H, q, J=7.4 Hz); SCH2ꢀCH3,
1.34 (3H, t, J=7.4 Hz); HCꢁCH, 4.20 (2H, bs); H4,
7.83 (td, J=7.7, 1.6 Hz); H3, 7.48 (d, J=7.7 Hz); H5,
7.35 (td, J=7.7, 4.9 Hz); H6, 8.85 (d, J=4.9 Hz).
13C{1H}-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 42.3;
SꢀCH2, 31.3; SCH2ꢀCH3, 14.25; HCꢁCH, 45.78; C2,
157.6; C3, 124.2; C4, 138.41; C5, 123.5; C6, 153.2 C.
4.1.13. [Pd(p2-fn)(HNꢀSMe)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (white microcrystals, yield 75%,
decomposes slowly in chlorinated solvent). Found: C,
41.03; H, 3.38; N, 12.81. C11H11N3SPd requires: C,
40.81; H, 3.43; N, 12.98%. IR (in KBr) (cm−1): wCꢂN
,
4.1.9. [Pd(p2-ma)(HNꢀSiPr)]
1
2196 (s); wCꢁN, 1598 (s). H-NMR (in CDCl3, r.t.), l
(ppm): CH2ꢀS, 4.16 (2H, s); SꢀCH3, 2.39 (3H, s);
HCꢁCH, 3.10 (2H, s); H3, 7.51 (d, J=7.7 Hz); H4, 7.86
(td, J=7.7, 1.7 Hz); H5, 7.38 (dd, J=7.7, 5.1 Hz); H6,
8.95 (d, J=5.1 Hz). 13C{1H}-NMR (in CDCl3, r.t.), l
(ppm): SꢀCH2, 44.3; SꢀCH3, 20.0; HCꢁCH, 22.4; CꢂN,
122.3; C2, 157.1; C3, 124.2; C4, 138.4; C5, 123.9; C6,
153.4.
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield 90%,
decomposes slowly in chlorinated solvents). IR (in KBr)
(cm−1): wCꢁO, 1790 (s), 1722 (s); wCꢁN, 1600. H-NMR
1
(in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.15 (2H, s); SꢀCH,
3.08 (1H, sept, J=6.7 Hz); CH(CH3)2, 1.36 (6H, d,
J=6.7 Hz); HCꢁCH, 4.15 (2H, s); H4, 7.83 (td, J=7.7,
1.6 Hz); H3, 7.48 (d, J=7.7 Hz); H5, 7.33 (dd, J=7.7,
4.7); H6, 8.83 (d, J=4.7 Hz). 13C{1H}-NMR (in
CDCl3, r.t.), l (ppm): CH2ꢀS, 41.1; SꢀCH, 40.9;
CH(CH3)2, 23.0; HCꢁCH, 45.8 (b); C2, 158.1; C3,
124.1; C4, 138.4; C5, 123.2; C6, 153.1; CꢁO, 171.0 (b).
4.1.14. [Pd(p2-fn)(HNꢀSEt)]
The title complex [1f] was prepared in the same way
as [Pd(h2-nq)(HNꢀSMe)] (white microcrystals, yield

12
L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
63%, decomposes slowly in chlorinated solvents). IR (in
CDCl3, r.t.), l (ppm): CH2ꢀS, 4.51 (2H, s); pyrꢀCH3,
2.93 (3H, s); HCꢁCH, 3.18 (2H, s); H4, 7.67 (t, J=7.7
Hz); H3, H5, Hb, Hc, Hd, 7.40 (m). 13C{1H}-NMR (in
CDCl3, r.t.), (ppm): CH2ꢀS, 46.9; pyrꢀCH3, 29.4;
HCꢁCH, 23.0; CꢂN, 122.3; ca. 131.4; Cb, 129.6; Cc,
131.6; Cd, 129.3; C2, 161.1; C3, 123.9; C4, 138.3; C5,
120.7; C6, 156.7.
1
KBr) (cm−1): wCꢂN, 2197 (s): wCꢁN, 1597. H-NMR (in
CDCl3, r.t.), l (ppm): CH2ꢀS, 4.16, 4.21(2H, J=16.2
Hz, AB syst.); SꢀCH2, 2.88 (2H, q, J=7.4 Hz);
CH2CH3, 1.40 (t, J=7.4 Hz); HCꢁCH, 3.10 (2H, bs);
H3, 7.5 (d, J=7.7 Hz); H4, 7.85 (td, J=7.7, 1.5 Hz);
H5, 7.35 (dd, J=7.7, 5.1 Hz); H6, 8.9 (d, J=5.1 Hz).
13C{1H}-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 42.14;
SꢀCH2, 31.1; CH2ꢀCH3, 14.0; HCꢁCH, 22.5; CꢂN,
122.41; C2, 157.6; C3, 124.14; C4, 138.4; C5, 123.61; C6,
153.4.
4.1.19. [Pd(p2-tmetc)(HNꢀSMe)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
94%). Found: C, 40.60; H, 4.11; N, 2.69.
C17H21NO8SPd requires: C, 40.37; H, 4.18; N, 2.77%.
IR (in KBr) (cm−1): wCꢁO, 1724, 1691; wCꢁN, 1601.
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.14 (2H,
s); SꢀCH3, 2.48 (3H, s); OꢀCH3, 3.7 (12H, s); H3, 7.42
(d, J=7.7 Hz); H4, 7.78 (td, J=7.7, 1.7 Hz); H5, 7.32
(dd, J=7.7, 5.4 Hz); H6, 9.13 (d, J=5.4 Hz). 13C{1H}-
NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 43.9; SꢀCH3,
20.5; OꢀCH3, 52; CꢁO, 169.9; C2, 157.3; C3, 123.7; C4,
137.7; C5, 123.1; C6, 153.7.
4.1.15. [Pd(p2-fn)(HNꢀSiPr)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals yield 80%,
decomposes slowly in chlorinated solvents). IR (in KBr)
(cm−1): wCꢂN, 2197 (s); wCꢁN, 1599. 1H-NMR (in CDCl3,
r.t.), l (ppm): CH2ꢀS, 4.20 (2H, s); SꢀCH, 3.12 (1H,
sept, J=6.7 Hz); CH(CH3)2, 1.43 (6H, d, J=6.7 Hz);
HCꢁCH, 3.12 (2H, s); H3, 7.5 (d, J=7.7 Hz); H4, 7.85
(td, J=7.7, 1.6 Hz); H5, 7.35 (dd, J=7.7, 5.3 Hz); H6,
8.92 (d, J=5.3 Hz). 13C{1H}-NMR (in CDCl3, r.t.), l
(ppm): CH2ꢀS, 41.0; SꢀCH, 40.6; CH(CH3)2, 22.9;
HCꢁCH, 22.4; CꢂN, 122.5; C2, 158.0; C3, 124.1; C4,
138.4; C5, 123.3; C6, 153.3.
4.1.20. [Pd(p2-tmetc)(HNꢀSEt)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
91%). IR (in KBr) (cm−1): wCꢁO, 1740, 1724, 1701,
4.1.16. [Pd(p2-fn)(HNꢀStBu)]
1668; wCꢁN, 1598. H-NMR (in CDCl3, r.t.), l (ppm):
1
The title complex [1g] was prepared in the same way
as [Pd(h2-nq)(HNꢀSMe)] (white microcrystals, yield
87%, decomposes slowly in the solid). IR (in KBr)
(cm−1): wCꢂN, 2199 (s); wCꢁN, 1597. 1H-NMR (in CDCl3,
r.t.), l (ppm): CH2ꢀS, 4.2 (2H, s); SꢀC(CH3)3, 1.5 (9H,
s); HCꢁCH, 3.1 (2H, bs); H3, 7.51 (d, J=7.7 Hz); H4,
7.84 (J=7.7, 1.6 Hz); H5, 7.34 (dd, J=7.7, 5.1 Hz);
H6, 8.85 (d, J=5.1 Hz). 13C{1H}-NMR (in CDCl3,
r.t.), l (ppm): CH2ꢀS, 39.0; SꢀC(CH3)3, 48.6; C(CH3)3,
30.4; HCꢁCH, 22.3; CꢂN, 122.6; C2, 158.0; C3, 124.0;
C4, 138.4; C5, 123.2; C6, 153.1.
CH2ꢀS, 4.16 (2H, s); SꢀCH2, 2.86 (2H, q, J=7.4 Hz);
CH2ꢀCH3, 1.34 (3H, t, J=7.4 Hz); OꢀCH3, 3.72 (12 H,
s); H3, 7.41 (d, J=7.7 Hz); H4, 7.77 (td, J=7.7, 1.7
Hz); H5, 7.31 (dd, J=7.7, 5.2 Hz); H6, 9.14 (d, J=5.2
Hz). 13C{1H}-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS,
41.9; SꢀCH2, 31.5; CH2ꢀCH3, 14.14; OꢀCH3, 52.21; C2,
158.0; C3, 123.86; C4, 137.92; C5, 122.9; C6, 153.8; CꢁO,
169.9, 169.4
4.1.21. [Pd(p2-tmetc)(HNꢀSiPr)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
87%). IR (in KBr) (cm−1): wCꢁO, 1738, 1722, 1701,
4.1.17. [Pd(p2-fn)(HNꢀSPh)]
1
The title complex [1f] was prepared in the same way
as [Pd(h2-nq)(HNꢀSMe)] (white microcrystals, yield
78%). IR (in KBr) (cm−1): wCꢂN, 2199 (s); wCꢁN, 1601.
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.5 (2H, s);
HCꢁCH, 3.2 (2H, s); H3, H5, Hb, Hc, Hd, 7.4 (7H, m);
H4, 7.88 (td, J=7.7, 1.6 Hz); H6, 8.95 (d, J=5.0 Hz).
13C{1H}-NMR (in CDCl3, r.t.), (ppm): CH2ꢀS, 47.1;
HCꢁCH, 23.3; CꢂN, 122.0; Cb, 129.4; Cc, 132.0; Cd,
129.3; C2, 156.7; C3, 124.0; C4, 138.3; C5, 123.3; C6,
152.9.
1674; wCꢁN, 1598. H-NMR (in CDCl3, r.t.), l (ppm):
CH2ꢀS, 4.16 (2H, s); SꢀCH, 3.23 (1H, sept, J=6.7 Hz);
CH(CH3)2, 1.37 (6H, d J=6.7 Hz); OꢀCH3, 3.70 (6H,
s), OꢀCH3, 3.71 (6H, s); H3, 7.41 (d, J=7.7 Hz); H4,
7.76 (td, J=7.7, 1.7 Hz); H5, 7.32 (dd, J=7.7, 5.3 Hz);
H6, 9.16 (d, J=5.3 Hz). 13C{1H}-NMR (in CDCl3,
r.t.), l (ppm): CH2ꢀS, 40.4; SꢀCH, 40.61; CH(CH3)2,
22.7; OꢀCH3, 52.1; C2, 158.33; C3, 123.74; C4, 137.9;
C5, 122.7; C6, 153.8; CꢁO, 169.4, 169.9.
4.1.22. [Pd(p2-tmetc)(HNꢀStBu)]
4.1.18. [Pd(p2-fn)(MeNꢀSPh)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
90%). IR (in KBr) (cm−1): wCꢁO, 1710, 1691; wCꢁN, 1595
The title complex [1g] was prepared in the same way
as [Pd(h2-nq)(HNꢀSMe)] (yellowish microcrystals, yield
82%, decomposes slowly in chlorinated solvents). IR (in
1
(s). H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.16
1
KBr) (cm−1): wCꢂN, 2200 (s); wCꢁN, 1602. H-NMR (in
(2H, s); C(CH3)3, 1.43 (9H, s); OꢀCH3, 3.70 (6H, s),

L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
13
OꢀCH3, 3.71 (6H, s); H3, 7.42 (d, J=7.7 Hz); H4, 7.76
(td, J=7.7, 1.7 Hz); H5, 7.28 (dd, J=7.7, 5.3 Hz); H6,
9.15 (d, J=5.3 Hz). 13C{1H}-NMR (in CDCl3, r.t.), l
(ppm): CH2ꢀS, 38.9; SꢀC, 48.0; C(CH3)3, 29.8; OꢀCH3,
52.1; C2, 158.6; C3, 123.7; C4, 137.9; C5, 122.5; C6,
153.7.
113.2; C2, 158.33; C3, 125.1; C4, 139.8; C5, 124.1; C6,
153.
4.1.27. [Pd(p2-tcne)(HNꢀSiPr)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
88%). IR (in KBr) (cm−1): wCꢂN, 2222 (s); wCꢁN, 1605
4.1.23. [Pd(p2-tmetc)(HNꢀSPh)]
(s). H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.32
1
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
88%). IR (in KBr) (cm−1): wCꢁO, 1736, 1699; wCꢁN, 1601.
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.45 (2H,
s); OꢀCH3, 3.57 (6H, s), OꢀCH3, 3.75 (6H, s); H3, H5,
Hc, Hd, 7.31 (5H, m); Hb, H4, 7.72 (3H, m); H6, 9.21 (d,
J=5.4 Hz). 13C{1H}-NMR (in CDCl3, r.t.), l (ppm):
CH2ꢀS, 47.3; CꢁC, n.v.; OꢀCH3, 52.2 (6C), OꢀCH3,
52.3 (6C); ca. 132.7; Cb, 129.3; Cc, 132.5; Cd, 129.1; C2,
157.3; C3, 124.0; C4, 138.0; C5, 123.0; C6, 153.9; CꢁO,
169.3, 169.6.
(2H, s); SꢀCH, 3.30 (1H, sept, J=6.7 Hz); CH(CH3)2,
1.51 (6H, d, J=6.7 Hz); H3, 7.63 (d, J=7.7 Hz); H4,
8.00 (td, J=7.7, 1.5 Hz); H5, 7.52 (dd, J=7.7, 5.3 Hz);
H6, 8.82 (d, J=5.3 Hz). 13C{1H}-NMR (in CDCl3,
r.t.), l (ppm): CH2ꢀS, 41.9; SꢀCH, 40.8; CH(CH3)2,
22.8; C2, 158.7; C3, 125.4; C4, 140.2; C5, 124.1; C6, 153.
4.1.28. [Pd(p2-tcne)(HNꢀStBu)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
87%). IR (in KBr) (cm−1): wCꢂN, 2226 (s); wCꢁN, 1602
1
(s). H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.33
4.1.24. [Pd(p2-tmetc)(MeNꢀSPh)]
(2H, s); C(CH3)3, 1.57 (9H, s); H3, 7.65 (d, J=7.8 Hz);
H4, 8.00 (td, J=7.8 Hz, 1.6 Hz); H5, 7.31 (dd, J=7.8,
5.3 Hz); H6, 8.82 (d, J=5.3 Hz). 13C{1H}-NMR (in
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
94%). IR (in KBr) (cm−1): wCꢁO, 1718, 1691 (d); wCꢁN
,
CDCl3, r.t.),
l
(ppm): CH2ꢀS, 38.8; SꢀC, 50.7;
1
1603. H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.48
(2H, s); pyr–CH3, 2.88 (3H, s); OꢀCH3, 3.56 (6H, s);
OꢀCH3, 3.71 (6H, s); H3, Hb, Hc, Hd, 7.26 (6H, m
centr.); H4, 7.57 (t, J=7.7 Hz); H5, 7.10 (d, J=7.4
Hz). 13C{1H}-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS,
46.9; pyrꢀCH3, 28.5; CꢁC (obscured); OꢀCH3, 52.1; Cb,
128.9; Cc, 129.3; Cd, 128.9; C2, 161.9; C3, 123.5; C4,
137.9; C5, 120.4; C6, 157.0; CꢁO, 169.6.
C(CH3)3, 30.1; CꢂN, 113.1; C2, 158.9; C3, 125.1; C4,
139.9; C5, 123.6; C6, 152.7.
4.1.29. [Pd(p2-tcne)(HNꢀSPh)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
83%). IR (in KBr) (cm−1): wCꢂN, 2224 (s); wCꢁN, 1603
1
(s). H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.63
(2H, s); H4, 7.99 (td, J=7.7, 7.1 Hz); H3, H5, Hb, Hc,
Hd, 7.58 (7H, m); H6, 8.89 (d, J=5.2 Hz). 13C{1H}-
NMR (in (CD3)2CO, r.t.), l (ppm): CH2ꢀS, 46.59;
CꢂN, 114.4; Cb, 131.8; Cc, 131.0; Cd, 130.8; C2, 160.2;
C3, 126.4; C4, 141.5; C5, 125.8; C6, 153.8.
4.1.25. [Pd(p2-tcne)(HNꢀSMe)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
89%). Found: C, 41.91; H, 2.33; N, 18.51. C13H9N5SPd
requires: C, 41.78; H, 2.43; N, 18.74%. IR (in KBr)
(cm−1): wCꢂN, 2226 (s); wCꢁN, 1599 (s). 1H-NMR (in
CDCl3, r.t.), l (ppm): CH2ꢀS, 4.3 (2H, s); SꢀCH3, 2.58
(3H, s); H3, 7.63 (d, J=7.7 Hz); H4, 8.01 (td, J=7.7,
1.6 Hz); H5, 7.54 (dd, J=7.7, 5.4 Hz); H6, 8.87 (d,
J=5.4 Hz). 13C{1H}-NMR (in (CD3)2CO, r.t.), l
(ppm): CH2ꢀS, 44.7; SꢀCH3; 20.6; CꢂN, 114.7; C2,
161.0; C3, 126.3; C4, 141.4; C5, 126.2; C6, 154.1.
4.1.30. [Pd(p2-tcne)(MeNꢀSPh)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
88%). IR (in KBr) (cm−1): wCꢂN, 2232 (s); wCꢁN, 1605.
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.67 (2H,
s); pyrꢀCH3 (3H, s); H4, 7.83 (t, J=7.7 Hz); H5, 7.36
(d, J=7.7 Hz); H3, Hb, Hd, 7.53 (6H, m). 13C{1H}-
NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 46.8; pyrꢀCH3,
29.7; Cb, 130.6; Cc, 131.0; Cd, 130.4; C2, 161.8; C3,
125.0; C4, 139.9; C5, 121.0; C6, 157.3.
4.1.26. [Pd(p2-tcne)(HNꢀSEt)]
The title complex was prepared in the same way as
[Pd(h2-nq)(HNꢀSMe)] (yellow microcrystals, yield
98%). IR (in KBr) (cm−1): wCꢂN, 2224 (s); wCꢁN, 1603.
1H-NMR (in CDCl3, r.t.), l (ppm): CH2ꢀS, 4.31 (2H,
bs); SꢀCH2, 2.95 (2H, q, J=7.4 Hz); CH2ꢀCH3, 1.50
(3H, t, J=7.4 Hz); H3, 7.63 (d, J=7.7 Hz); H4, 8.02 (t,
J=7.7 Hz,); H5, 7.55 (dd, J=7.7, 5.1 Hz); H6, 8.86 (d,
J=5.1 Hz). 13C{1H}-NMR (in CDCl3, r.t.), (ppm):
CH2ꢀS, 41.7; SꢀCH2, 31.4; CH2ꢀCH3, 14.0; CꢂN,
5. IR and NMR measurements
The IR, 1H-, and 13C{1H}-NMR spectra were
recorded on a Nicolet Magna™ 750 spectrophotometer
and on a Bruker AC™ 200 spectrometer, respectively.
The temperature-dependent 1H-NMR spectra were ana-

14
L. Cano6ese et al. / Journal of Organometallic Chemistry 601 (2000) 1–15
Table 5
ligand) to a solution of the complex under study at a
controlled temperature (25°C). The spectral features of
the resulting mixtures were recorded by means of a
Lambda 40 Perkin–Elmer spectrophotometer. Mathe-
matical and statistical data analysis was carried out on
a personal computer equipped with a locally adapted
version of Marquardt’s algorithm [28] written in
TURBOBASIC™.
Crystallographic data for complexes [Pd(h2-ma)(HNꢀStBu)] and
[Pd(h2-tcne)(HNꢀSMe)
Empirical formula
Formula weight
Crystal system
Space group
Unit cell dimensions
C14H17NO3PdS
385.75
C13H9 N5PdS
373.71
Triclinic
Monoclinic
P21/c
(
P1 (No. 2)
,
a (A)
9.016(4)
9.126(4)
9.903(4)
112.18(3)
96.03(3)
102.32(3)
721.5(5)
2
10.21(1)
9.517(8)
14.95(1)
90
100.62(8)
90
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
7. X-ray structural analysis
Data collection, crystal, and refinement parameters
are collected in Table 5. Accurate values for the unit-
cell dimensions were determined from the angular set-
ting of 50 reflections with [ between 9 and 14° and
intensity data were measured using the ꢀ–2[ scan
technique. The structures were solved using heavy-atom
methods, completed by subsequent difference Fourier
synthesis, and refined on F2 by full-matrix least-squares
procedures. All non-hydrogen atoms were refined with
anisotropic displacement coefficients and all assigned
hydrogen atoms were treated as idealized contributions.
All software and sources of the scattering factors are
contained in the SHELXTL/PC (version 5.03) program
library [29].
3
,
Volume (A )
Z
1431(2)
4
Dcalc (Mg m−3
)
1.776
1.735
Crystal color, habit
Crystal size (mm)
Diffractometer
Yellow, block
0.15×0.12×0.07
Nicolet Siemens
R3n/V
Yellow, block
0.15×0.12×0.11
Nicolet Siemens
R3n/V
,
Wavelength (A)
0.71073
14.39
0.71073
14.39
v (MoꢀKa) (cm−1
)
Temperature (K)
[ Range for data col- 2.3–25
lection (°)
Number of reflections 2556
collected
Number of unique
reflections
293(2)
293(2)
2.5–22.1
1864
2338 [Rint=0.0249] 1753 [Rint=0.050]
Absorption correlation Empirical, „-scan
Empirical, „-scan
1.00/0.683
T
max/Tmin
0.968/0.686
Refinement method
Full-matrix least-
squares on F2
2556/182
Full-matrix least-
squares on F2
1699/182
8. Supplementary material
Number of data/
parameters
Tables of atomic coordinates and isotropic thermal
parameters, bond lengths and angles, anisotropic ther-
mal parameters, and H-atom coordinates are available
upon request. Crystallographic data for the structural
analysis have been deposited with the Cambridge Crys-
tallographic Data Centre for compound X. Copies of
this information may be obtained free of charge from:
The Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (Fax: +44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk).
Goodness-of-fit
R(F) a [I\2|(I)]
R(wF2) a
1.077
0.024
0.055
1.155
0.063
0.164
1.09 and −1.13
Largest diff. peak and 0.361 and −0.412
−3
,
hole (e A
)
a R(F)=S(ꢀFoꢀ−ꢀFcꢀ)/SꢀFoꢀ; R(wF2)=[S[w(Fo2−Fc2)2]/S[w(F2o)2]]1/2
.
lyzed using the SWAN program [26] and the first-order
rate constants determined were fitted to the appropriate
temperatures by
equation [27].
a reparametrized Eyring–Polanyi
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