Cationic olefin Pd(II) complexes bearing α-iminoketone N,O-ligands: Synthesis, intramolecular and interionic characterization and reactivity with olefins and alkynes

Article abstract of DOI:10.1016/j.jorganchem.2003.11.020

Complexes [Pd(η¹, η²-5-OMe- C₈H₁₂)(N,O)]BF₄ (N,O=2,6-(i-Pr) ₂(C₆H₃)N=C(Ph)-C(Ph)=O, 1; 2,6-(i-Pr)₂(C₆H₃)N=C(Me)- C(Ph)=O, 2; 2-benzoylpyridine, 3) were synthesized by the reactions of [Pd(η¹,η²-5-OMe-C₈ H₁₂)Cl]₂ with the suitable N,O-ligand. They were tested as catalysts for olefin or alkyne polymerizations. During such reactions 1-3 quantitatively transformed into their η¹,η²-1-OMe-C₈H₁₂ isomers (1a-3a). The same isomerization occurred in methylene chloride, even in the absence of olefins or alkynes, with a much slower rate. All complexes were fully characterized in solution by multinuclear and multidimensional low temperature NMR spectroscopy. The solid state structures of complexes 1 and 1a were investigated by X-ray single crystal studies. ¹⁹F, ¹H-HOESY NMR experiments carried out in methylene chloride-d₂ at 217 K indicated that the anion prefers to locate on the side of N,O-ligand shifted toward the O-arm in 1-1a and 2-2a while it approaches the N-arm in 3 and 3a compounds.

Full text of DOI:10.1016/j.jorganchem.2003.11.020

Journal of Organometallic Chemistry 689 (2004) 647–661
www.elsevier.com/locate/jorganchem
Cationic olefin Pd(II) complexes bearing a-iminoketone
N,O-ligands: synthesis, intramolecular and interionic
characterization and reactivity with olefins and alkynes
a
Barbara Binotti , Carla Carfagna , Elisabetta Foresti , Alceo Macchioni
a
b
c,
*
,
b
Piera Sabatino , Cristiano Zuccaccia , Daniele Zuccaccia
c
c
a
Istituto di Scienze Chimiche, Universitꢀa di Urbino, Piazza Rinascimento, 6 – 61029 Urbino, Italy
Dipartimento di Chimica ‘‘G. Ciamician’’, Universitꢀa di Bologna, Via Selmi, 2 – 40126, Bologna, Italy
b
c
Dipartimento di Chimica, Universitꢀa di Perugia, Via Elce di Sotto, 8 – 06123 Perugia, Italy
Received 5 August 2003; accepted 10 November 2003
Abstract
Complexes [Pd(g1, g2-5-OMe–C8H12)(N,O)]BF4 (N,O ¼ 2,6-(i-Pr)2(C6H3)N@C(Ph)–C(Ph)@O, 1; 2,6-(i-Pr)2(C6H3)N@C(Me)–
C(Ph)@O, 2; 2-benzoylpyridine, 3) were synthesized by the reactions of [Pd(g1,g2-5-OMe–C8H12)Cl]2 with the suitable N,O-ligand.
They were tested as catalysts for olefin or alkyne polymerizations. During such reactions 1–3 quantitatively transformed into their
g1,g2-1-OMe–C8H12 isomers (1a–3a). The same isomerization occurred in methylene chloride, even in the absence of olefins or
alkynes, with a much slower rate. All complexes were fully characterized in solution by multinuclear and multidimensional low
temperature NMR spectroscopy. The solid state structures of complexes 1 and 1a were investigated by X-ray single crystal studies.
19F, 1H-HOESY NMR experiments carried out in methylene chloride-d2 at 217 K indicated that the anion prefers to locate on the
side of N,O-ligand shifted toward the O-arm in 1–1a and 2–2a while it approaches the N-arm in 3 and 3a compounds.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Palladium compounds; N,O-ligands; X-ray structure; Ion pairs; HOESY NMR
1. Introduction
by the bidentate g1,g2-5-methoxycyclooctenyl-ligand,
are active catalysts for the styrene/CO co-polymeriza-
tion carried out in mild conditions. Their performances
were found to be strongly affected by the nature of the
counteranion Xꢀ and, in particular, little coordinating
anions increase the catalytic performances because
compete in a smaller extent with the incoming substrate
(CO or olefin) [6]. Similar compounds bearing pyrazolyl
[7] and a-diimine [8] ligands were synthesized and they
showed a catalytic activity toward styrene/CO copoly-
merization lower than that of the ‘‘bipy complex’’. In
particular, by studying a series of compounds bearing
(2,6-(R)2–C6H3)N@C(R0)–C(R0)@N(2,6-(R)2–C6H3) li-
gands, it was found that an increased steric hindrance in
the apical positions decreases the catalytic perfor-
mances. Due to the paucity of studies on palladium
compounds bearing neutral N,O-ligands [9] we decided
to take into account them, also because their possible
Palladium(II) compounds of general formula
[Pd(Me)L(N,N)]X (L ¼ labile ligand) have been shown
to catalyze both olefin polymerizations [1] and olefin/CO
co-polymerizations [2]. An enormous number of N,N-
ligands has been employed, among which a-diimine (2,6-
(R)2–C6H3)N@C(R0)-C(R0)@N(2,6-(R)2–C6H3) ligands
[3] were shown to be very versatile in that their elec-
tronic and steric features can be easily tuned by a suit-
able choice of R and R0 substituents. Some years ago,
Milani et al. [4] showed that also analogous palladium
compounds [Pd(g1,g2-5-OMe–C8H12)(bipy)]X (bipy ¼
2,20-bipirydine) [5], in which L and Me are substituted
* Corresponding author. Tel.: +39-075-5855579; fax: +39-075-
5855598.
E-mail address: alceo@unipg.it (A. Macchioni).
0022-328X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.11.020

648
B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
hemilabile nature [10], trying to maintain the favourable
features of diimine ligands. The natural choice fell on a-
iminoketone compounds.
[Pd(g1,g2-C8H12OMe)Cl]2 [17] with two equivalents of
the suitable N,O-ligand in CH2Cl2 at )20 °C with sub-
sequent addition of AgBF4. The reaction yield was al-
ways higher than 85%. The isomer having the O-arm
trans to the Pd–C r-bond prevalently formed in agree-
ment with previous studies carried out by Cavell and
co-workers [9a].
Compounds 1–2 and 3 presented as orange and yel-
low powders, respectively. They were not stable in both
solution and in the solid state in the presence of mois-
ture and even in its absence were little thermally stable in
solution. By leaving compounds 1–3 in CH2Cl2 solution
at low temperature in the presence of a weak nucleophile
(see the section 2.5 for details) the quantitative isomer-
ization to 1a–3a was observed (Scheme 2).
In this paper, we report the synthesis of novel palla-
dium [Pd(g1,g2-C8H12OMe)(N,O)]BF4 compounds
(N,O ¼ 2,6-(i-Pr)2(C6H3)N@C(Ph)–C(Ph)@O, 1; 2,6-(i-
Pr)2(C6H3)N@C(Me)–C(Ph)@O, 2; 2-benzoylpyridine,
3) and their complete characterization both in solution
and in the solid state. The results of catalytic tests and
the reactivity toward olefins, alkynes, CO and other
nucleophiles are also presented. During such studies we
found that complexes 1–3 quantitatively isomerize to
1a–3a, bearing g1,g2-1-OMe- instead of g1,g2-5-OMe-
cyclooctenyl ligand, through an unprecedented reaction
that we have previously communicated [11]. Here we
give a full account of the preparation and character-
ization of 1a–3a. In addition, since several years we have
been interested on the investigation of anion–cation in-
teractions in solution through NOE [12] and PGSE [13]
NMR methodologies owing to the fact that they
strongly affect the reactivity and structure of metallor-
ganic compounds [14]. Consequently, the interionic
structure of the synthesized compounds has been in-
vestigated in solution by means of 19F, 1H-HOESY
NMR spectroscopy and compared with that observed in
the solid state.
Complexes 1a–3a showed the same thermal stability
problems of 1–3.
2.2. Characterization in solution
All complexes were characterized at 217 K in CD2Cl2
by 1H, 13C, 19F, 1H-COSY, 1H-NOESY, 19F, 1H-HO-
1
ESY, 1H, 13C-HMQC NMR and H, 13C-HMBC NMR
spectroscopies. The temperature was kept at 217 K for
two reasons: (1) as stated above, compounds are little
thermally stable and (2) dynamical processes make the
resonances broad above ca. 273 K. Selected data are
reported in Table 1 while numbering is illustrated in
Chart 1.
2. Results and discussion
The assignment of the cyclooctenylmethoxy 1H
and 13C resonances for complexes 1–3 was obtained
starting from the C5 resonance that is well known and
separated from other carbon resonances. H5 was easily
assigned from the 1H, 13C-HMQC spectrum. All the
proton resonances of the cyclooctenyl group were
then assigned following the scalar connectivity in the
1H-COSY spectrum. The carbon resonances of this group
2.1. Syntheses
Ligands 2,6-(i-Pr)2(C6H3)N@C(Ph)–C(Ph)@O [15]
and 2,6-(i-Pr)2(C6H3)N@C(Me)–C(Ph)@O [16] were
synthesized by direct condensation of equimolar
amounts of the diones O@C(R)–C(Ph)@O (R ¼ Me or
Ph) and 2,6-(i-Pr)2(C6H3)NH2.
Organometallic complexes 1–3 were synthesized ac-
cording to Scheme 1 through the reaction of the dimer
were again identified from the 1H, 13C-HMQC spectrum.
1
The assignment of the cyclooctenylmethoxy H and 13
C
resonances for complexes 1a–3a and the consequent in-
dividuation of the g1,g2-5-OMe to g1,g2-1-OMe- isom-
erization derived from the observation of (1) only one
olefin 1H resonance in the 1H NMR spectra (H2), (2) five
instead of four CH2 groups in the 13C-J modulated NMR
spectra, and (3) a quaternary carbon at d values typical of
vinylether compounds in the 13C NMR spectra (C1).
-
Ph
BF4
O
+
R
Pd
N
MeO
Cl
CH2Cl2
Pd
N, O-ligand
1:R=Ph 2:R=Me
AgBF4
-
BF4
T = 253K
Ph
MeO
2
O
+
Pd
N
3
MeO
Scheme 1.
Scheme 2.

B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
649
Table 1
Selected 1H NMR (ppm),a 13C NMR (ppm)a and IR (cmꢀ1)bdata for the complexes [Pd(g1,g2-C8H12OMe)(N,O)]BF4, 1–3, 1a–3a and uncoordi-
nated N,O ligands (1–3lig)
1
1a
1lig
2
2a
2lig
3
3a
3lig
H1
H2
H5
H6
H9
C1
6.50
6.16
3.07
2.42
2.37
6.40
6.08
3.09
2.43
2.39
6.34
6.04
3.72
3.30
3.37
5.88
2.32
1.63
3.91
5.78
2.34
1.52
3.82
5.63
3.34
1.98
3.81
112.9
156.0
111.7
156.2
109.1
155.6
C2
C5
106.3
80.9
60.8
78.8
63.6
107.0
80.7
57.9
78.5
60.8
106.4
81.8
56.9
76.2
57.6
C6
C9
35.7
57.5
35.3
57.4
35.3
57.0
56.3
56.1
57.3
C10
C11
mCO
199.8
174.4
1626.4
199.3
173.1
1626.1
197.2
166.2
1671.0
198.9
178.2
1629.8
198.1
176.4
1630.3
193.7
168.9
1666.6
201.0
151.6
1618.1
200.2
155.6
1621.2
194.7
154.9
1667.5
a In CD2Cl2 at 217 K.
b In nujol.
21
15
15
15
16
16
16
22
20
17
23
17
17
14
14
13
14
13
32
32
31
30
31
19
18
11
18
10 11
30
26
18 19
13
12
12
12
20
10
10
3
26
28
25
24
25
24
11
N
27
27
21
N
N
O
O
O
3
8
3
4
4
4
29
33
29
9
9
OMe
OMe
OMe
+
+
Pd
+
Pd
28
33
2
1
2
1
2
1
9
Pd
5
5
6
5
6
34
34
35
35
6
7
8
7
8
7
1
2
3
21
15
15
16
16
15
16
22
20
32
17
23
17
17
14
13
14
13
14
32 31
30
31
30
19
18
11
18
10 11
18
19
13
12
12
12
20
21
10
3
10
3
26
28
26
28
25
24
25
11
24
27
27
N
N
4
N
4
O
O
O
4
3
29
29
33
35
+
Pd
+
Pd
+
5
6
5
5
6
2
1
2
1
2
33
35
Pd
1
34
34
6
MeO
MeO
MeO
8
7
8
7
8
7
9
9
9
1a
2a
Chart 1.
3a
The coordination of N,O-ligands to palladium was
evidenced by a deshielding [9a,18] of C10 and C11 and
by a decrease [19] in the CO stretching frequencies
(Table 1). For compounds 1–2 and 1a–2a, four different
resonances were observed for the methyl groups 31, 32,
34 and 35 [8,20]. The stereochemistry of the prevalent
isomer observed for all complexes was easily deduced by
1H-NOESY experiments. For 1–3 compounds, the res-
onances pointing toward the metal (H31 and H35 for 1
and 2; H21 for 3) showed dipolar interactions with H5,
H6, and H9 only ensuring that the N-arm is in cis rel-
ative position with respect to the Pd–C r-bond. The
specificity of the NOE contacts is still higher in that the
interactions of H31 with H5 and H9, and between H35
and H6 were observed for 1 and 2 (Fig. 1). An analo-
gous situation was met for 1a–3a compounds: the di-
polar interactions between H31 and H35 for 1a and 2a
and H21 for 3a with H5 were observed while those with
H9 were not present. Again the N-arm is in cis relative
position with respect to the Pd–C r-bond but OMe is far
away from the N-aryl substituents. Another possibility
for understanding the stereochemistry of compounds
comes from the comparative analysis of the chemical
shifts values. H5, H6, and H9 chemical shifts are very
similar for compounds 1 and 2. On the contrary, they
are much lower that those of compound 3. Due to the

650
B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
1
15
16
cannot be detected in the standard H NMR spectra. It
is known that the intensity of the cross peaks, in such a
situation of two species in equilibrium with one that is
strongly predominant, is the average of those of the
single species and is, consequently high. This provided
the opportunity to determine also the chemical shifts
relative to the species present in little amount (Table 2).
It is reasonable to believe that these species that
equilibrate with 1–3 are the isomers in which N-arm is
in trans position relative to the Pd–C r-bond (Scheme 3).
A hint to this hypothesis comes from the trends of the
chemical shifts reported in Table 2. In fact, H5, H6 and
H9 in the O,N isomer are no more affected by the above-
introduced shielding effect of the aromatic ring of 2,6-
(i-Pr)2(C6H3)-substituents and they resonate at much
higher frequencies.
17
14
32
31
30
18
11
H9
13
12
10
26
28
25
24
H18
27
N
O
3
8
4
29
33
9
OMe
+
Pd
2
1
5
6
34
35
7
H5
H6
H33
H30
ppm
1.15
1.20
1.25
1.30
1.35
1.40
1.45
H32
H34
1H
H35
2.3. Interionic characterization in solution
H31
As mentioned in Section 1, anion–cation interactions
play a key role in many chemical processes mediated by
organometallic compounds [14] and is, consequently, of
fundamental importance to investigate them especially
in solution, where they really ‘‘work’’. Although the
interionic structure in solution of a few square planar
compounds have been studied [6–8,20,22], the com-
pounds here reported are rather unique in that (a)
contain four different functionalities bonded to the me-
tal and, in particular, (b) allow to compare, for the first
time, the effect on the interionic structure of a weak and
sterically little hindered O-arm with a stronger and en-
cumbered N-arm. The anion–cation relative position
was investigated in CD2Cl2 at 217 K for all compounds
by means of 19F, 1H-HOESY NMR spectroscopy. The
observed interionic interactions are collected in Table 3.
1.50
ppm
3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4
1H
Fig. 1. Section of the 1H-NOESY NMR spectrum (400.13 MHz, 217
K, CD2Cl2) of complex 2 showing the intramolecular contacts of H31
with H5 and H9, and between H35 and H6.
fact that the aromatic ring of 2,6-(i-Pr)2(C6H3)-substit-
uents is known to orient almost perpendicular to the
square planar coordination plane, the observed shield-
ing for H5, H6, and H9 has to be attributed to their
proximity with the p-electrons of such substituent [21].
This is only possible if the N-arm is in cis relative po-
sition with respect to the Pd–C r-bond. As a confir-
mation, only H5, that remains in the proximity of
palladium and in cis position with respect to 2,6-
(i-Pr)2(C6H3)-substituents, undergoes the same shielding
effect in complexes 1a–2a.
N
O
5
O
N
5
9
9
1
+
OMe
+
OMe
Exchange cross peaks were clearly visible in the H-
2
2
Pd
Pd
NOESY spectra of compounds 1–3 for H1, H2, H5,
H6 and H9 resonances. Such resonances correlated
with frequencies where signals were not apparently
present. This indicates that compounds 1–3 are in
equilibrium with species present in so little amount that
6
6
1
1
N,O
O,N
Scheme 3.
Table 2
Chemical shifts for 1–3 isomers in which the N-arm is trans to the Pd–C r-bond (in bold) deduced from the exchange cross peaks observed in the 1H-
NOESY NMR phase sensitive spectra recorded in CD2Cl2 at 217 K
1
2
3
N,O
O,N
Dd
0.62
N,O
O,N
Dd
0.53
N,O
O,N
Dd
0.49
H1
H2
H5
H6
H9
6.50
6.16
3.07
2.42
2.37
5.88
5.31
3.56
3.43
3.24
6.40
6.08
3.09
2.43
2.39
5.87
5.44
3.53
3.51
3.19
6.34
6.04
3.72
3.30
3.37
5.85
5.41
3.51
3.48
3.19
0.85
)0.49
)1.01
)0.87
0.64
)0.44
)1.08
)0.80
0.63
0.21
)0.18
0.18

B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
651
Table 3
Interionic contacts (ꢁ ꢁ ꢁ strong; ꢁꢁ medium; ꢁ weak; ꢂ very weak)
bonded to C10. By the way, the observation of interionic
interactions between BF4ꢀand H18 (in 2) and H19/H23
(in 1), and with H30 and H33 suggests that the anion
locates above or below the coordination plane and it is
shifted toward O-arm of the N,O-ligand. As a confir-
mation, weak interionic contacts are also observed for
H1 and H2. A similar situation was found for complexes
1a and 2a with a significant new finding that gives value
to the interionic structure deduced for 1 and 2: a contact
between the anion and H9, that in these compounds is in
cis relative position to the O-arm, is now present. The
strongest contacts in the 19F, 1H-HOESY NMR spectra
of compounds 3 and 3a are between the anion and H19
and H20 of the pyridine ring (Fig. 2). The interactions
that for other compounds were the strongest ones (with
H13/H17), in the case of 3 and 3a have similar intensity
than those with H18 and H21 and weak interactions are
observed even for H5 (in 3 and 3a), H6 and H9 (in 3).
These observations suggest that in these cases the anion
is shifted on the side of N-arm. As a confirmation, it
does not interact with H1 and H2 protons and it inter-
acts with H9 only in compound 3 (Fig. 2).
detected in the 19F, 1H-HOESY NMR spectra (376.6 MHz) recorded
ꢁ
in CD2Cl2 at 217 K and Hꢃ ꢃ ꢃB contacts (<5.0 A) detected by X-ray
diffraction
1
1a
2
2a
3
3a
H1
H2
ꢁ
ꢁ
ꢁ
ꢁ
ꢁꢁ
ꢁꢁ
3.86
4.35
3.56
H3
H5
H6
H9
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
ꢁꢁ
ꢁꢁ
ꢂ
4.38
ꢁꢁ
H13/H17
ꢁꢁ
ꢁ ꢁ ꢁ ꢁ ꢁ ꢁ ꢁꢁ
ꢁꢁ
3.70
ꢁꢁ
4.23
ꢁꢁ
H14/H16
H18
H19/H23
ꢁꢁ
ꢁꢁ
ꢁꢁ
ꢁꢁ
ꢁꢁ
ꢁꢁ
ꢁꢁ
ꢁꢁ
ꢁ
ꢁ
ꢁ ꢁ ꢁ ꢁ ꢁ ꢁ
ꢁ ꢁ ꢁ ꢁ ꢁ ꢁ
3.75
ꢁ
3.56
ꢁ
H20/H22
H21
H30
ꢁꢁ
ꢁꢁ
ꢁ
ꢁ
ꢁꢁ
ꢁꢁ
3.35
4.44
H31
H32
4.99
ꢂ
ꢂ
ꢁ
ꢂ
ꢁ
The interionic structure of compounds [Pd(g1,g2-
C8H12OMe)(bipy)]X, similar to 3 and 3a, was previously
studied [6] and it was found that, independently of Xꢀ
nature, the anion occupies the axial positions even if it
slightly prefers to locate close to the bipy ligand and, in
particular, close to the N-arm trans to the Pd–C r-bond.
4.40
ꢁ
H33
H34
H35
ꢁ
ꢁꢁ
ꢁ
ꢁꢁ
ꢁ
ꢂ
ꢂ
ꢂ
ꢀ
For compounds 1 and 2, BF4 mainly interacts with
protons belonging to the N,O-ligand and, in particular,
with H13/H17 and H14/H16 of the phenyl moiety
ꢀ
In complexes 3 and 3a, BF4 prefers the position close
to the py-ring that is now cis to the Pd–C r-bond
ꢀ
Fig. 2. 19F, 1H-HOESY NMR spectra (376.6 MHz, 217 K, CD2Cl2) of compounds 3 and 3a, showing that BF4 specifically interacts with aromatic
protons, especially those of the pyridine-ring, and only in the case of compound 3 it gives a contact with H9 (OMe).

652
B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
Table 4
Ph
O
Ph
O
Ph
O
Me
N
Ph
N
ꢁ
Selected bond lengths (A) and angles (°) for 1 and 1a
N
1
1a
2.156(4)
+
+
+
Pd
Pd
Pd
Pd–N
2.129(3)
2.171(3)
2.165(5)
2.147(5)
Pd–O(1)
Pd–C(1)
Pd–C(2)
Pd–C(5)
Pd–C(6)
N–C(11)
O(1)–C(10)
C(1)–C(2)
C(10)–C(11)
2.194(4)
2.276(5)
2.172(6)
2.013(5)
olefin
olefin
olefin
C
C
C
2.025(5)
1.293(6)
1.218(5)
1.353(8)
1.521(6)
-
1.276(7)
1.221(7)
1.346(9)
1.537(7)
= BF4
Fig. 3. Schematic representation of the anion–cation relative position
as a function of the structural features of N,O-ligands showing the
gradual shift of the anion toward the O-arm as the steric hindrance in
the N-arm increases.
N–Pd–O(1)
N–Pd–C(1)
75.5(1)
164.3(2)
158.1(2)
75.0(2)
161.8(2)
161.0(2)
100.0(2)
N–Pd–C(2)
N–Pd–C(5)
N–Pd–C(6)
(Fig. 3). This can be due to a higher accumulation of
positive charge on the pyridine-ring [23] respect to the
phenyl ring and/or to a repulsion exerted by the lone
pair on the carbonyl-oxygen. Going from 3/3a to 2/2a
compounds, –C(Me)@N(2,6-(i-Pr)2–C6H3) moiety sub-
stitute the pyridine-ring and the anion shift toward the
O-arm (Fig. 3) due to two effects: (1) a smaller accu-
mulation of positive charge on C11 and (2) an increased
steric hindrance introduced in the back of N-arm. The
introduction of a Ph- instead of a Me-moiety in the
imine carbon (C11), that occurs for compounds 1 and
1a, leads to a similar interionic structure but with a
general loss of specificity in the interionic interactions,
as previously observed [8], probably due to the fact that
the positive charge present in C11 is smaller than for
complex 2/2a and more difficult to approach.
100.4(2)
101.5(2)
96.9(2)
O(1)–Pd–C(1)
O(1)–Pd–C(2)
O(1)–Pd–C(5)
O(1)–Pd–C(6)
C(1)–Pd–C(5)
C(1)–Pd–C(6)
C(2)–Pd–C(5)
C(2)–Pd–C(6)
93.7(2)
103.9(2)
173.1(2)
172.9(2)
80.8(2)
89.0(2)
90.0(2)
82.4(2)
between the two complexes lie in the position of the
methoxy group in the cyclooctenyl ligand [C(5) in 1 and
C(1) in 1a] and the sp3 coordinated carbon [C(6) in 1
and C(5) in 1a]. As a consequence, 1 exhibits four
stereogenic centres and 1a only three. Both crystals
contain discrete [Pd(g1,g2-5-OMe–C8H12)(2,6-(i-Pr)2
(C6H3)N@C(Ph)–C(Ph)@O] units and [BF4]ꢀ counteri-
ons, but the existence of a preferential ion pair can be
detected on the basis of the Pdꢃ ꢃ ꢃB distances (4.249 and
2.4. X-ray studies
ꢁ
The structures of the isomeric cations 1 and 1a, are
shown in Fig. 4; a preliminary description of 1 has al-
ready been done [11]. The main structural differences
4.266 A for the nearest neighbor anion and 5.98 and
ꢁ
6.94 A for the second one in 1 and 1a, respectively).
Table 4 reports relevant bond distances and angles for
C9
O2
C7
C6
C34
C4
C7
C5
C5
C3
C4
C3
C35
C8
C6
C8
C33
C35
C32
C33
C31
C30
C1
C2
O2
C24
C31
C24
C32
C1
Pd
C2
C30
N
C34
Pd
N
F4
O1
F3
C11
C11
O1
F2
C18
C9
C18
F2
C10
C12
B
C10
C12
B
F4
F1
F1
F3
1
1a
Fig. 4. ORTEP drawing of complex 1 and 1a with thermal ellipsoids plot (50% probability for all non-hydrogen atoms).

B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
653
the two complexes. The palladium atom is in a distorted
square planar coordination environment. Two coordi-
nation sites are occupied by an alkyl carbon atom [C(6)
and C(5) in 1 and 1a, respectively] and the olefinic
[C(1)@C(2)] bond of the cyclooctenyl ligand. The other
two sites are defined by the N and O atoms of the a-
iminoketone ligand which forms a five-membered ring,
with the N-arm trans to the C(1)@C(2) bond and the O
atom trans to the sp3 carbon atom. The different at-
tachment of the methoxy substituent in the two isomers,
at C(5) in 1 and C(1) in 1a, is reflected in a weaker in-
teraction of Pd with C(1) in the latter: in fact, Pd–C(1)
the solid state do not always correspond to the strongest
contacts observed in solution.
2.5. Mechanism of isomerization and catalytic properties
An investigation of the reactivity of complexes 1–3
towards unsaturated molecules was carried out. Isola-
tion of organo-palladium compounds deriving from the
stoichiometric insertion of olefins, alkynes and carbon
monoxide in such complexes was not possible. Indeed,
the addition of a stoichiometric amount of phenylacet-
ylene to methylene chloride-d2 solution of 1–3 at 0 °C,
resulted in isomerization of the methoxycyclooctenyl
ligand (Scheme 2), formation of a small amount of
oligomers and disappearance of the alkyne. The isom-
erization appeared to be quantitative in a few minutes
on the basis of NMR spectroscopy: 5 min for 2, 15 min
for 1 and 50 min for 3; the reaction times could be
related to the different nature of the two types of N,O-
ligands: 2-benzoylpyridine and a-iminoketones. Fur-
thermore, complete isomerization of complex 1 was
obtained after 90 min using p-methylstyrene, while in
absence of weak nucleophiles the reaction took place in
29 h. Also carbon monoxide bubbling through a meth-
ylene chloride solution of 1 produced 1a together with
unidentified species due to the decomposition occurring
during the reaction. Good yields of 1a–3a were achieved
by adding a stoichiometric amount of phenylacetylene
to a methylene chloride solution of 1–3 at )30 °C. After
3 days the solution was evaporated; pure samples of 1a–
3a were obtained through re-crystallization with di-
chloromethane/hexane. A possible mechanism for the
isomerization reaction could involve b-hydride elimina-
tion of H5, in agreement with the literature [24], and the
formation of a five-coordinated hydrido-complex having
the weakly interacting carbonyl oxygen in apical posi-
tion [9a] (Scheme 4). This complex could dissociate the
vinylether olefin bond or the O-arm of the N,O-ligand,
due to the competition with external nucleophiles. A
final hydrido migration onto the olefin carbon C2 yields
square planar compounds 1a–3a where the N-arm re-
mains in trans position with respect to the olefin bond.
Even though it is known that methoxycyclooctenyl-
ligands can coordinate in several ways [24a], this is the
first time that an g1,g2-5-methoxycyclooctenyl to g1,g2-
1-methoxycyclooctenyl-ligand isomerization has been
observed [11].
ꢁ
and Pd–C(2) interactions are 2.165(5) and 2.147(5) A in
ꢁ
1 and 2.276(5) and 2.172(6) A in 1a, respectively. It is
noteworthy that in 1a the O(1)ꢃ ꢃ ꢃO(2) contact, 2.920(6)
ꢁ
A, is slightly shorter than the van der Waals contact (ca.
ꢁ
3 A) and O(1) is involved in a H-bond interaction with
ꢁ
H(9) (C(9)–H(9)ꢃ ꢃ ꢃO(1) 2.42 A, angle 118.4°). Probably,
the lengthening of the Pd–C(1) interaction with respect
to Pd–C(2) results from the contributions of non-
bonded and bonded effects: the short Oꢃ ꢃ ꢃO contact and
the electron-withdrawing effect of O(2) on C(1). On the
other hand, the Pd–N and Pd–O bond lengths are
slightly shorter in 1 than in 1a: 2.129(3) versus 2.156(4)
ꢁ
ꢁ
A and 2.171(3) versus 2.194(4) A, respectively. The Pd–
C(alkyl) interactions are quite comparable [Pd–C(6)
ꢁ
ꢁ
2.025(5) A in 1 and Pd–C(5) 2.013(5) A in 1a]. The five-
membered ring is almost planar with the maximum de-
ꢁ
viation for C(10) and C(11) (average ꢄ 0.06 A in 1 and
ꢁ
ꢄ0.09 A in 1a). The C(1)@C(2) bond distance is 1.353(8)
ꢁ
and 1.346(9) A in 1 and 1a respectively, quite compa-
rable with that found in [Pd(g1,g2-C8H12OMe)bipy]þ
ꢁ
1.367(6) A [6].
The nearest [BF4]ꢀ counterion is positioned invari-
ably close to the less-encumbered O-arm of the five-
membered ring, in accord with the NMR evidence for
the ion pair in solution. The anion-containing pocket
remains similar in 1 and 1a notwithstanding the sterical
encumbrance of the methoxy substituent placed in the
vicinity (Fig. 4). The structure of the ion pair is stabi-
lized by a number of C–Hꢃ ꢃ ꢃF interactions, only one of
which involves the nearest ion pair: C(23)–H(23)ꢃ ꢃ ꢃF(4)
ꢁ
ꢁ
2.45 A, angle 136.0° and C(21)–H(21)ꢃ ꢃ ꢃF(3) 2.68 A,
angle 107.4° for 1 and 1a, respectively.
For complexes 1 and 1a, a comparison between the
solution and solid state interionic structures was carried
out. In Table 3 the interionic Hꢃ ꢃ ꢃB distances shorter than
ꢁ
5 A are reported together with the relative intensities of
With the aim to check whether other nucleophiles
were also able to promote the isomerization process and
to trap possible hydrido-intermediates, stoichiometric
reactions of complexes 1–3 with NEt4Cl, PPh3 and free
N,O-ligand were carried out. In no case it was possible
to isolate hydrido-species. In particular, from the reac-
tion of complex 2 with NEt4Cl the formation of the
[Pd(g1,g2-C8H12OMe)Cl]2 dimer and the presence of
free N,O-ligand were observed. Using PPh3 the isom-
the interionic interactions in solution. From the qualita-
tive point of view, the anion locates close to the O-arm of
the bidentate N,O-ligand in both solution and solid state
(Fig. 4) interacting with the same protons (this is true if
one considers that the two intimate ion pairs, with the
anion above or below the coordination plane, exist in
solution at the same time), while in the solid state only one
of this is present. Instead, the shortest Hꢃ ꢃ ꢃB distances in

654
B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
H
N
+
Pd
Nu
OMe
H
N
O
OMe
N 5
O
N
O
+
Pd
+
+
Pd
OMe
OMe
Pd
2
migratory
insertion
OR
β-elimination
H
OMe
O
N
+
Pd
O
Nu
Scheme 4.
erization of 1 to 1a was detected by NMR spectroscopy
together with other unidentified species. Finally, the
reaction of 3 with 2-benzoylpyridine led to the synthesis
of [Pd(g1,g2-5-OMe–C8H12)(2-benzoylpyridine)2]BF4
complex (4) bearing two N,O-ligands coordinated to the
metal throughout the N-arms.
7.17–6.85 (meta and para protons) and 6.80–6.50 (ortho
protons). These data, together with the IR absorptions
at 697, 740 and 756 cmꢀ1, have been attributed to reg-
ular cis-transoidal structure of the polymer [26]. The
content of cis sequences, determined from the NMR
spectra [26b], was estimated to be 90%. A less stereo-
regular cis-transoidal polyphenylacetylene was pro-
duced by complex 1 (10 g of polymer/g Pd, cis content
<70%). This is probably due to the less rigidity of this
compound with respect to 3. Also complexes 1a and 4
resulted to be active in the phenylacetylene homopoly-
merization with yields comparable to those obtained
using 1 and 3, respectively. The molecular weights (Mw)
of polyphenylacetylenes are in the range 5900–12 200;
these values are similar to those reported using other
Pd(II) catalysts [27].
Palladium compounds stabilized by N,N-ligands are
successfully used in many catalytic reactions but only
very few examples concerning with applications in ca-
talysis of complexes containing neutral N,O-ligands
have been reported in the literature. While a-iminoke-
tone Ni(II) compounds were tested in the homopoly-
merization of ethylene, norbornenes and styrenes [9b],
Cavell and co-workers [9a] showed the catalytic prop-
erties of cationic methyl-phosphine Pd(II) complexes
bearing N,O-ligands, where N,O are 2-pyridinecarb-
oxylates or 2-pyridinecarboxamides. These compounds
are active catalysts for ethylene/CO copolymerization
but with a modest activity in comparison with com-
plexes containing dppp-like ligands [2]. However, they
have been very useful to study the elementary steps of
the copolymerization process. In the light of the reac-
tivities reported in the literature, complexes 1 and 3 were
tested as catalysts for p-methylstyrene/CO copolymeri-
zation and for olefin and alkyne homopolymerizations.
Both compounds were found to be totally inactive in
producing polyketones in mild conditions (PCO ¼ 1 atm,
T ¼ ꢀ5 °C) and the copolymerization reaction with 1
gave only atactic [25] poly(p-methylstyrene) (26 g of
polymer/g Pd). 1 and 3 showed very low activity also in
the p-methylstyrene homopolymerization giving only
traces of poly(p-methylstyrene). Instead they were able
to polymerize the more reactive phenylacetylene. Hom-
opolymerization of phenylacetylene promoted by 3 was
carried out in dichloromethane at 0 °C using an alkyne/
palladium molar ratio of 300/1; 30 g of polymer/g Pd
were achieved after 24 h by precipitation with methanol.
The 1H NMR spectrum of the obtained polyphenyl-
acetylene displayed a sharp singlet at 5.90 ppm due to
the vinylic proton, in addition to a set of multiplets at
3. Conclusion
(g1,g2-5-OMe–C8H12)Pd(II) complexes (1–3) and
their (g1,g2-1-OMe–C8H12)Pd(II) isomers (1a–3a)
bearing N,O-iminoketone ligands were synthesized and
fully characterized in both solution and solid state, al-
though their limited stability. The 1–3 to 1a–3a isom-
erization was found to be accelerated by weak
nucleophiles such as olefins and alkynes.
The anion–cation relative orientation was investi-
gated in solution through 19F, 1H-HOESY NMR ex-
periments. It was found that the electronic favored
position for the anion is to lay above and below the
square planar coordination plane and, in particular,
close to the back side of the N-arm. This situation can
be only completely reached for compounds 3–3a in
which the steric hindrance in the apical position is al-
most absent. On passing to compounds 2–2a and 1–1a
and, consequently, increasing the apical encumbrance,
the anion shifts toward the O-arm (Fig. 3). The inter-
ionic structure found in solution for 1–1a showed a good
agreement with that observed in the solid state.

B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
655
Eventually, complexes 1, 1a, 3 and 4 resulted to be
active catalysts for the phenylacetylene homopolymer-
ization, producing in moderate yields polyphenylacet-
ylene with a cis-transoidal structure; instead, they
showed a very low activity both in the p-methyl-
styrene homopolymerization and p-methylstyrene/CO
co-polymerization.
ilar to that reported in the literature [15]. A mixture of 1
g of benzil (4.76 mmol) and 0.9 ml of 2,6-diisopropy-
laniline (4.76 mmol) in 100 ml of acetic acid was heated
to reflux. After 8 h the mixture was cooled to 20 °C and
yellow crystalline material was obtained overnight. The
solid was filtered off, washed with acetic acid (3 ꢅ 5 ml)
and dried under vacuum, yielding 1.06 g of 2,6-(i-
Pr)2(C6H3)N@C(Ph)–C(Ph)@O (2.86 mmol, yield:
60%). IR (Nujol, cmꢀ1): 1671.0 (C@O). 1H NMR
(CDCl3, 293 K): d 8.21, 7.99, 7.63, 7.53, 7.34, 7.21, 6.95
(aromatic protons, 13H), 2.94 (br, CH(CH3)2, 2H), 1.12,
1.02 (d br, CH(CH3)2, 6H each). 13C{1H} NMR
(CDCl3, 293 K): d 197.3 (s, C@O), 165.9 (s, C@N), 145.2
(s, C@N–Cipso), 136.8, 135.7, 134.1, 132.0, 130.7, 129.3,
129.0, 128.4, 124.6, 123.9, 122.8 (s, aromatic carbons),
28.9 (s, CH(CH3)2), 24.4 (s, CH(CH3)2), 21.6 (s,
CH(CH3)2.
4. Experimental
4.1. General remarks
Manipulation of all complexes were carried out
employing standard Schlenk techniques and dry, ox-
ygen-free nitrogen atmosphere. All solvents were dried
and purified by standard methods and freshly distilled
under nitrogen. p-Methylstyrene and phenylacetylene
were dried over calcium hydride and distilled before
use. The other CP grade chemicals were used as re-
ceived. Methylene chloride-d2 was degassed and stored
4.3. Preparation and characterization of 2,6-(i-Pr)2-
(C6H3)N@C(Me)–C(Ph)@O
The 2,6-(i-Pr)2(C6H3)N@C(Me)–C(Ph)@O ligand
was syntesized according to the method described in the
literature for similar 1-phenyl-1,2-propanedione
monoimine compounds [16]. A 0.66 ml (3.50 mmol)
sample of 2,6-diisopropylaniline was added to a meth-
anolic solution (1 ml) of 1-phenyl-1,2-propanedione
(0.47 ml, 3.50 mmol) at 25 °C, in the presence of cata-
lytic amount of formic acid. After 9 h the mixture was
cooled to )20 °C and yellow crystalline material was
obtained in 1 h. The solid was filtered off, washed with
cold methanol (3 ꢅ 5 ml) and dried under vacuum,
yielding 774 mg of 2,6-(i-Pr)2(C6H3)N@C(Me)–
C(Ph)@O (2.52 mmol, yield: 72%). IR (Nujol, cmꢀ1):
ꢁ
over 3 A molecular sieves. Carbon monoxide (CP
grade 99.99%) was supplied by Air Liquide. Com-
plexes Pd(C8H12)Cl2 and [Pd(g1,g2-C8H12OMe)Cl]2
were prepared as reported in the literature [17]. 2-
Benzoylpyridine was purchased from Aldrich. Ele-
mental analyses (C, H, N) were carried out with a
Fisons Instruments 1108 CHNS-O elemental analyzer.
IR spectra were measured at room temperature as
Nujols mulls between KBr disks on a FT-IR 1725 X
Perkin–Elmer spectrophotometer. One- and two-di-
mensional 1H, 13C, 19F NMR spectra were measured
on a Bruker DRX 400 spectrometer. Referencing is
relative to TMS (1H and 13C) and CCl3F (19F). NMR
samples were prepared dissolving about 20 mg of
compound in 0.5 ml of methylene chloride-d2. Two-
dimensional H-NOESY and 19F, H-HOESY spectra
were recorded with a mixing time of 500–800 ms.
The molecular weights (Mw) of polymers and the
molecular weight distributions (Mw=Mn) were deter-
mined by gel permeation chromatography versus poly-
styrene standards. The analyses were recorded on a
Knauer HPLC (K-501 Pump, K-2501 UV-detector)
1
1666.6 (C@O). H NMR (CDCl3, 293 K, J values in
Hz):d 8.26 (d, aromatic protons, 2H), 7.77 (m, aromatic
proton, 1H), 7.54 (m, aromatic protons, 2H), 7.21 (m,
aromatic protons, 3H), 2.81 (sept, 3JHH ¼ 6:6,
CH(CH3)2, 2H), 2.08 (s, C(N)–CH3, 3H), 1.25, 1.20 (d,
3JHH ¼ 6:6, CH(CH3)2, 6H each). 13C{1H} NMR
(CDCl3 293 K): d 193.0 (s, C@O), 168.2 (s, C@N), 144.8,
135.2, 135.0, 133.4, 130.6, 128.4, 124.5, 123.2 (s, aro-
matic carbons), 28.4 (s, CH(CH3)2), 23.5 (s, CH(CH3)2),
22.9 (s, CH(CH3)2), 17.6 (s, C(N)–CH3).
1
1
4
ꢁ
with a PLgel 5 lm 10 A GPC column and chloroform
as solvent (flow rate 0.6 ml/min). Samples were prepared
dissolving 0.7 mg of polyphenylacetylene or 2 mg of
poly(p-methylstyrene) in 10 ml of CHCl3. The statistical
calculations were performed using the Bruker Chrom-
star software program.
4.4. Preparation and characterization of 1
The 2,6-(i-Pr)2(C6H3)N@C(Ph)–C(Ph)@O ligand
(332 mg, 0.90 mmol) was added to a stirred solution of
[Pd(g1,g2-C8H12OMe)Cl]2 (253 mg, 0.45 mmol) in
dichloromethane (10 ml) at 25 °C. After 10 min the
obtained yellow solution was cooled to )20 °C and
transferred into a Schlenk tube containing AgBF4 (185
mg, 0.95 mmol). The stirring reaction mixture was
slowly warmed to )10°C. After 2.5 h, during which time
4.2. Preparation and characterization of 2,6-(i-Pr)2-
(C6H3)N@C(Ph)–C(Ph)@O
The
synthesis
of 2,6-(i-Pr)2(C6H3)N@C(Ph)–
C(Ph)@O ligand was carried out with a procedure sim-

656
B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
AgCl precipitated, the mixture was filtered through
Celite. A red oil was obtained after evaporation of the
solvent under vacuum. The product, upon treatment
with cold hexane (3 ꢅ 5 ml), gave compound 1 as an
orange powder (550 mg, 0.78 mmol, yield: 87%). Crystal
suitable for an X-ray structure determination were ob-
tained by slow diffusion of hexane into a dichlorome-
thane solution of 1 at )30 °C. IR (Nujol, cmꢀ1): 1626.4
C14 and C16), 129.4, 125.9, 125.1 (s, C26, C27 and C28),
111.7 (s, C1), 107.0 (s, C2), 80.7 (s, C5), 57.9 (s, C6), 56.1
(s, C9), 33.7 (s, C7), 31.6 (s, C4), 29.7 (s, C33), 28.9 (s,
C30 and C3), 25.9 (s, C8), 25.0 (s, C34), 24.6 (s, C31),
24.3 (s, C18), 24.2 (s, C32), 23.7 (s, C35). 19F NMR
(CD2Cl2, 217 K) d )151.56 (10BF4), )151.62 (11BF4).
Anal. Calc. for C30H40BF4NO2Pd: C, 56.31; H, 6.30; N,
2.19. Found: C, 56.48; H, 6.42; N, 2.07%.
1
(C@O). H NMR (CD2Cl2, 217 K, J values in Hz): d
3
4
7.76 (tt, JHH ¼ 7:4, JHH ¼ 1:1, H15), 7.61 (brd, H13
4.6. Preparation and characterization of 3
and H17), 7.48 (tt, 3JHH ¼ 7:6, 4JHH ¼ 1:1, H21), 7.46 (t,
3
3JHH ¼ 7:9, H14 and H16), 7.40 (dd, JHH ¼ 7:7,
Complex 3 was synthesized according to the proce-
dure described for 1
using 315 mg of [Pd(g1,
3
4JHH ¼ 1:5, H26), 7.36 (t, JHH ¼ 7:7, H27), 7.27 (t,
3
3JHH ¼ 7:7, H20 and H22), 7.18 (dd, JHH ¼ 7:7,
g2-C8H12OMe)Cl]2 (0.56 mmol), 205 mg of the 2-ben-
zoylpyridine ligand (1.12 mmol) and 230 mg of AgBF4
(1.18 mmol). A 516 mg (1.00 mmol, yield: 90%) sample
of 3 was collected as an yellow powder. IR (Nujol,
cmꢀ1): 1618.1 (C@O). 1H NMR (CD2Cl2, 217 K, J
values in Hz): d 8.84 (br, H21), 8.47 (br, H19), 8.30 (br,
H18), 8.18 (br, H20), 7.84 (m, H13, H17 and H15), 7.67
4JHH ¼ 1:5, H28), 6.95 (brd, H19 and H23), 6.50 (m,
3
H1), 6.16 (m, H2), 3.25 (sept, JHH ¼ 6:6, H33), 3.07
(brd, H5), 2.85 (brd, H3), 2.63 (m, H30), 2.52 (sept,
3JHH ¼ 6:6, H30), 2.42 (m, H6), 2.37 (s, H9), 2.35 (m,
H8 and H80), 2.20 (m, H7), 2.00 (m, H4), 1.89 (m,
3
H40),1.41 (d, JHH ¼ 6:6, H35), 1.32 (m, H70), 1.26 (d,
3
3
3JHH ¼ 6:6, H31), 1.22 (d, JHH ¼ 6:6, H34), 0.20 (d,
(t, JHH ¼ 7:5, H14 and H16), 6.34 (br, H1), 6.04 (br,
3JHH ¼ 6:6, H32). 13C{1H} NMR (CD2Cl2, 217 K): d
199.8 (s, C10), 174.4 (s, C11), 140.0, 139.9, 136.0, 134.5,
130.9 (s, aromatic quaternary carbons), 137.9 (s, C15),
134.2 (s, C21), 132.3 (s, C13 and C17), 129.8 (s, C14 and
C16), 129.7 (s, C27), 129.6 (s, C28), 125.1 (s, C26), 112.9
(s, C1), 106.3 (s, C2), 80.9 (s, C5), 60.8 (s, C6), 56.3 (s,
C9), 34.4 (s, C7), 31.2 (s, C4), 30.4 (s, C33), 28.8 (s, C3),
28.5 (s, C30), 26.0 (s, C8), 25.4 (s, C31), 24.6 (s, C34),
23.4 (s, C35), 22.4 (s, C32). 19F NMR (CD2Cl2, 217 K):
d )152.65 (10BF4), )152.70 (11BF4). Anal. Calc. for
C35H42BF4NO2Pd: C, 59.89; H, 6.03; N, 2.00. Found:
C, 59.91; H, 6.21; N, 1.95%.
H2), 3.72 (brt, H5), 3.37 (s, H9), 3.30 (br, H6), 2.75 (m,
H3 and H30), 2.39 (m, H8, H80 and H7), 2.12 (H4 and
H40), 1.58 (H70). 13C{1H} NMR (CD2Cl2, 217 K): d
201.0 (s, C10), 151.6 (s, C11), 150.9 (s, C21), 150.8 (s,
C12), 142.5 (s, C19), 136.1 (s, C15), 133.4 (s, C18), 132.6
(s, C20), 131.3 (s, C13 and C17), 129.9 (s, C14 and C16),
109.1 (s, C1), 106.4 (s, C2), 81.8 (s, C5), 57.3 (s, C9), 56.9
(s, C6), 34.6 (s, C7), 30.8 (s, C4), 28.7 (s, C3), 26.1 (s,
C8). 19F NMR (CD2Cl2, 217 K): d )152.38 (10BF4),
)152.43 (11BF4). Anal. Calc. for C21H24BF4NO2Pd: C,
48.91; H, 4.69; N, 2.72. Found: C, 49.03; H, 4.74; N,
2.74%.
4.5. Preparation and characterization of 2
4.7. Preparation and characterization of 1a
Complex 2 was synthesized according to the proce-
dure described for
Complex 1a was obtained according to the following
procedures:
1
using 155 mg of [Pd(g1,
g2- C8H12OMe)Cl]2 (0.28 mmol), 172 mg of the 2,6-
(i-Pr)2(C6H3)N@C(Me)–C(Ph)@O ligand (0.56 mmol)
and 115 mg of AgBF4 (0.59 mmol). A 320 mg (0.50
mmol, yield: 90%) sample of 2 was collected as an or-
ange powder. IR (Nujol, cmꢀ1): 1629.8 (C@O). 1H
NMR (CD2Cl2, 217 K, J values in Hz): d 7.97 (d,
A: Complex 1 (88 mg, 0.13 mmol) was dissolved in
dichloromethane (1.5 ml) at )50 °C. To the resulting red
solution, phenylacetylene (13.8 ll, 0.13 mmol) was ad-
ded. The reaction mixture was stirred at )50 °C for 10
min and warmed to )30 °C. After 72 h at this temper-
ature, the red-brown solution was evaporated in a vac-
uum obtaining a brownish oil which, upon treatment
with cold hexane (3 ꢅ 5 ml), gave a brown powder.
Recrystallization with dichloromethane/hexane gave
compound 1a as an orange powder (63 mg, 0.09 mmol,
yield: 70%). Crystal suitable for an X-ray structure de-
termination were obtained by slow diffusion of hexane
into a dichloromethane solution of 1a at )30 °C. IR
3
3JHH ¼ 7:5, H13 and H17), 7.85 (t, JHH ¼ 7:5, H15),
3
7.68 (d, JHH ¼ 7:5, H14 and H16), 7.39 (m, H26, H27
and H28), 6.40 (m, H1), 6.08 (m, H2), 3.09 (m, H5), 3.04
3
3
(sept, JHH ¼ 6:7, H33), 2.91 (sept, JHH ¼ 6:7, H30),
2.80 (brd, H3), 2.61 (m, H30), 2.49 (s, H18), 2.43 (m,
H6), 2.39 (s, H9), 2.30 (m, H8 and H80), 2.19 (m, H7),
1.99 (m, H4), 1.87 (m, H40), 1.40 (d, JHH ¼ 6:7, H31),
3
1.35 (d, JHH ¼ 6:7, H35), 1.26 (m, H70), 1.20 (d,
(Nujol, cmꢀ1): 1626.1 (C@O). H NMR (CD2Cl2, 217
3
1
3JHH ¼ 6:7, H34), 1.17 (d, JHH ¼ 6:7, H32). 13C{1H}
K, J values in Hz): d 7.74 (t, JHH ¼ 7:5, H15), 7.59
3
3
NMR (CD2Cl2, 217 K): d 198.9 (s, C10), 178.2 (s, C11),
139.8, 139.1, 137.6, 134.4 (s, aromatic quaternary car-
bons), 136.9 (s, C15), 131.1 (s, C13 and C17), 129.9 (s,
(brd, H13 and H17), 7.45 (t, 3JHH ¼ 7:5, H14 and H16),
3
7.44 (t, JHH ¼ 7:9, H21 burried under H14 and H16),
3
3
7.39 (t, JHH ¼ 7:7, H27), 7.32 (d, JHH ¼ 7:7, H26),

B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
657
3
3
7.24 (t, JHH ¼ 7:9, H20 and H22), 7.22 (d, JHH ¼ 7:7,
(s, C30), 24.9 (s, C32), 24.4 (s, C35), 24.3 (s, C18), 23.8
(s, C31),, 23.3 (s, C34), 23.0 (s, C7), 22.4 (s, C3). 19F
NMR (CD2Cl2, 217 K): d )152.10 (10BF4), )152.16
(11BF4). Anal. Calc. for C30H40BF4NO2Pd: C, 56.31; H,
6.30; N, 2.19. Found: C, 56.48; H, 6.39; N, 2.23%.
Complex 2a was also obtained using phenylacetylene
according to the procedure B reported for 1a: starting
from 38 mg (0.06 mmol) of 2 in 0.5 ml of methylene
chloride-d2, a quantitative formation of 2a was observed
after 5 min at 0 °C.
H28), 6.88 (brd, H19 and H23), 5.88 (t, 3JHH ¼ 7:9, H2),
3.91 (s, H9), 2.88 (m, H8 and H33), 2.77 (m, H80 and
H30), 2.32 (m, H5 and H4), 2.20 (m, H3 and H30), 1.95
(m, H7 and H70), 1,63 (brt, H6), 1.33 (t, JHH ¼ 6:6,
3
3
3
H35), 1.31 (t, JHH ¼ 6:6, H31), 0.90 (t, JHH ¼ 6:6,
H34), 0.62 (brd, H40), 0.53 (t, JHH ¼ 6:6, H32), 0.44 (t,
3
3JHH ¼ 6:6, H60). 13C{1H} NMR (CD2Cl2, 217 K): d
199.3 (s, C10), 173.1 (s, C11), 156.0 (s, C1), 140.8 (s,
C24), 138.6 (s, C25), 137.6 (s, C15), 137.2 (s, C29), 133.7
(s, C21), 133.4 (s, C12), 132.0 (s, C13 and C17), 131.3 (s,
C18), 130.6 (s, C19 and C23), 129.9 (s, C14 and C16),
129.4 (s, C20 and C22), 129.4 (s, C27 burried under C20
and C22), 125.6 (s, C28), 125.2 (s, C26), 78.8 (s, C2),
63.6 (s, C5), 57.5 (s, C9), 40.6 (s, C4), 35.7 (s, C8 and
C6), 29.2 (s, C30), 28.9 (s, C33), 24.9 (s, C35), 24.2 (s,
C32), 23.7 (s, C31), 22.8 (s, C7), 22.7 (s, C34), 22.4 (s,
C3). 19F NMR (CD2Cl2, 217 K): d )152.60 (10BF4),
)152.70 (11BF4). Anal. Calc. for C35H42BF4NO2Pd: C,
59.89; H, 6.03; N, 2.00. Found: C, 59.93; H, 6.11; N,
2.03%.
4.9. Preparation and characterization of 3a
Complex 3a was synthesized according to the proce-
dure A described for 1a using 93 mg of 3 (0.18 mmol)
and 20 ll of phenylacetylene (0.18 mmol). A 72 mg (0.14
mmol, yield: 75%) sample of 3a was collected as a yellow
powder. IR (Nujol, cmꢀ1): 1621.2 (C@O). 1H NMR
(CD2Cl2, 217 K, J values in Hz): d 8.77 (brd,
3JHH ¼ 5:0, H21), 8.40 (brt, 3JHH ¼ 7:7, H19), 8.29 (brd,
3JHH ¼ 7:7, H18), 8.13 (m, H20), 7.84 (m, H13, H17 and
3
B: Phenylacetylene (6.6 ll, 0.06 mmol) was added to a
methylene chloride-d2 solution (0.5 ml) of 1 (42 mg, 0.06
mmol) in an NMR tube at )70 °C. Then, the reaction
mixture was warmed to 0 °C. After 15 min the yield of
1a appear to be quantitative on the basis of NMR
spectroscopy. The same result was obtained after 90 min
using p-methylstyrene (7.9 ll, 0.06 mmol) in equal op-
erating conditions.
H15), 7.68 (t, JHH ¼ 7:4, H14 and H16), 5.63 (dd,
3JHH ¼ 8:8, 3JHH ¼ 5:1, H2), 3.81 (s, H9), 3.34 (m, H5),
2.93 (brd, H8), 2.83 (m, H80), 2.63 (m, H4), 2.22 (m, H3
and H30), 2.03 (m, H7 and H70), 1.98 (m, H6), 1.04 (m,
H60), 1.02 (m, H40). 13C{1H} NMR (CD2Cl2, 217 K): d
200.2 (s, C10), 155.6 (s, C1), 150.9 (s, C21), 150.8 (s,
C11), 141.9 (s, C19), 136.0 (s, C15), 134.4 (s, C12), 132.9
(s, C18), 132.3 (s, C20), 131.4 (s, C13 and C17), 129.9
(C14 and C16), 76.2 (s, C2), 57.0 (s, C9), 57.6 (s, C5),
40.5 (s, C4), 35.9 (s, C8), 35.3 (s, C6), 23.0 (s, C7), 22.4
(s, C3). 19F NMR (CD2Cl2, 217 K): d )152.44 (10BF4),
)152.50 (11BF4). Anal. Calc. for C21H24BF4NO2Pd: C,
48.91; H, 4.69; N, 2.72. Found: C, 48.89; H, 4.73; N,
2.68%.
C: Keeping a methylene chloride-d2 solution (0.5 ml)
of 1 (40 mg, 0.06 mmol) at 0 °C for 29 h finally resulted
in a quantitative formation of 1a.
4.8. Preparation and characterization of 2a
Complex 2a was synthesized according to the pro-
cedure A described for complex 1a using 90 mg of 2
(0.14 mmol) and 15.4 ll of phenylacetylene (0.14
mmol). A 70 mg (0.11 mmol, yield: 75%) sample of 2a
was collected as an orange powder. IR (Nujol, cmꢀ1):
1630.3 (C@O).1H NMR (CD2Cl2, 217 K, J values in
Complex 3a was also obtained using phenylacetylene
according to the procedure B reported for 1a: starting
from 31 mg (0.06 mmol) of 3 in 0.5 ml of methylene
chloride-d2, a quantitative formation of 3a was observed
after 50 min at 0 °C.
3
Hz): d 7.93 (d, JHH ¼ 7:6, H13 and H17), 7.86 (t,
4.10. Preparation and characterization of 4
3
3JHH ¼ 7:6, H15), 7.69 (d, JHH ¼ 7:6, H14 and H16),
7.39 (m, H26, H27 and H28), 5.78 (brt, H2), 3.82 (s,
3
Complex 3 (26 mg, 0.05 mmol) and 2-benzoylpyri-
dine (9 mg, 0.05 mmol) were dissolved in 0.5 ml of
methylene chloride-d2 in an NMR tube at ) 30 °C. A
quantitative formation of [Pd(g1,g2-5-OMe–C8H12)(2-
benzoylpyridine)2]BF4 (4) was observed in few minutes
by NMR spectroscopy. The solution was evaporated in
a vacuum obtaining a yellow oil which, upon treatment
with cold hexane (3 ꢅ 2 ml), gave a yellow powder.
A 25 mg (0.036 mmol, 72%) sample of 4 was collected.
H9), 3.05 (sept, JHH ¼ 6:6, H30), 2.87 (m, H8 and
H33), 2.73 (m, H80), 2.41 (s, H18) 2.34 (m, H4 and H5),
2.18 (m, H3 and H30), 1.91 (m, H7 and H70), 1.52 (brt,
3
3
H6), 1.39 (d, JHH ¼ 6:6, H31), 1.35 (d, JHH ¼ 6:6,
3
3
H35), 1.19 (d, JHH ¼ 6:6, H32), 1.15 (d, JHH ¼ 6:6,
H34), 0.68 (brd, H40), 0.42 (brd, H60). 13C{1H} NMR
(CD2Cl2, 217 K): d 198.1 (s, C10), 176.4 (s, C11), 156.2
(s, C1), 140.4, 138.1, 137.9, 134.3 (s, aromatic quater-
nary carbons), 136.9 (s, C15), 130.9 (s, C13 and C17),
130.0 (s, C14 and C16), 129.0, 125.32, 125.29 (s, C26,
C27 and C28), 78.5 (s, C2), 60.8 (s, C5), 57.4 (s, C9),
40.6 (C4), 35.8, (s, C8), 35.3 (s, C6), 29.6 (s, C33), 29.1
1
IR (Nujol, cmꢀ1): 1666.8 (C@O). H NMR (CD2Cl2,
217 K, J values in Hz): d 9.07 (br, H21), 7.96 (br, H19),
3
7.75 (br, H18, H13 and H17), 7.58 (t, JHH ¼ 7:3, H14,
H16 and H15), 7.51 (br, H20), 5.87 (br, H1), 5.03 (br,

658
B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
H2), 3.50 (br, H5), 2.98 (s, H9), 2.72 (br, H3 or H30),
2.59 (br, H6), 2.50 (br, H30 or H3), 2.31 (br, H8 or
H80), 2.17 (br, H80 or H8), 2.06 (br, H7 or H70), 1.95
(br, H4 or H40), 1.90 (br, H40 or H4), 1.31 (br, H70 or
H7). 13C{1H} NMR (CD2Cl2, 217 K): d 194.8 (s, C10),
153.0 (s, C11), 152.5 (s, C21), 139.4 (s, C19), 135.6 (s,
C15), 130.9 (s, C13 and C17), 129.6 (s, C14 and C16),
128.8 (br, C20), 128.3 (s, C12), 106.1 (br, C1), 100.6
(br, C2), 82.0 (s, C5), 56.6 (s, C9), 47.6 (br, C6), 34.6 (s,
C7), 29.5 (s, C4), 28.3 (s, C3), 27.0 (s, C8). 19F NMR
(CD2Cl2, 217 K): d )152.82 (10BF4), )152.88 (11BF4).
Anal. Calc. for C33H33BF4N2O3Pd: C, 56.72; H, 4.76;
N, 4.01. Found: C, 56.98; H, 4.83; N, 3.97%.
mg (0.07 mmol) of 1a. A 50 mg (7 g of polymer/g Pd)
sample of cis-transoidal polyphenylacetylene was col-
lected (cis content <70%). For IR, 1H NMR and
13C{1H} NMR spectra, see Section 4.11. Anal. Calc. for
(C8H6)n: C, 94.08; H, 5.92. Found: C, 94.00; H, 5.96%.
Mw ¼ 5900; Mw=Mn ¼ 3:2.
4.14. Phenylacetylene homopolymerization by 4
The polymerization reaction was carried out accord-
ing to the procedure described for complex 1 using 49
mg (0.07 mmol) of 4. A 190 mg (26 g of polymer/g Pd)
sample of cis-transoidal polyphenylacetylene was col-
lected (cis content ffi 90%). For IR, 1H NMR and
13C{1H} NMR spectra, see Section 4.12. Anal. Calc. for
(C8H6)n: C, 94.08; H, 5.92. Found: C, 94.30; H, 5.00%.
Mw ¼ 12100; Mw=Mn ¼ 2:7.
4.11. Phenylacetylene homopolymerization by 1
A dichloromethane solution (1 ml) of phenylacetylene
(2.4 ml, 21 mmol) was added to a solution of 1 (47 mg,
0.07 mmol) in the same solvent (1.5 ml) cooled to )30 °C
(alkyne/palladium molar ratio 300:1). The reaction
mixture was slowly warmed to 0 °C and allowed to react
for 24 h, whereupon it changed from red to red brown
color. The resulting polyphenylacetylene was precipi-
tated with methanol, washed with methanol and dried
under vacuum to give an orange powder. A 70 mg (10 g
of polymer/g Pd) sample of cis-transoidal polyphenyl-
acetylene was collected (cis content <70%). IR (Nujol,
cmꢀ1): 1596, 917, 897, 843, 757, 742, 696. 1H NMR
(CDCl3, 293 K): d 7.50–6.20 (br, aromatic protons), 5.90
(br, vinylic proton). 13C{1H} NMR (CDCl3, 293 K): d
142.3 (br, Ph–C@CH), 139.9 (br, Ph–Ci), 131.0 (br, Ph–
C@CH), 128.3 (br, Ph–Co), 127.8 (br, Ph–Cm), 126.8 (br,
Ph–Cp). Anal. Calc. for (C8H6)n: C, 94.08; H, 5.92.
Found: C, 93.70; H, 6.10%. Mw ¼ 10400; Mw=Mn ¼ 2:1.
4.15. Attempted p-methylstyrene/CO copolymerization
by 1
Complex 1 (78 mg, 0.11 mmol) was dissolved at )10
°C in 5 ml of dichloromethane under nitrogen atmo-
sphere. The resulting solution was transferred into a
thermostated Schlenk flask equipped with a carbon
monoxide gas line and a tank for the CO. The 1 solution
was allowed to react with CO for 2 min at )10 °C,
during which formation of palladium metal was ob-
served. Then p-methylstyrene (4.4 ml, 33 mmol) was
added (olefin/palladium molar ratio 300:1). The reaction
mixture was slowly warmed to )5 °C; the starting red
solution became yellow with visible metallic palladium
traces. After 4 h the resulting gray polymer was pre-
cipitated with methanol and washed with methanol. To
remove metallic palladium the polymer was redissolved
in chloroform, filtered through Celite, precipitated with
methanol and dried under vacuum. A 300 mg sample of
atactic poly(p-methylstyrene) (26 g of polymer/g Pd) was
collected. IR (Nujol, cmꢀ1): 723, 814, 1020, 1039, 1113,
4.12. Phenylacetylene homopolymerization by 3
The polymerization reaction was carried out accord-
ing to the procedure described for complex 1 using 37
mg (0.07 mmol) of 3. A 213 mg (30 g of polymer/g Pd)
sample of cis-transoidal polyphenylacetylene was col-
lected (cis content ffi 90%). IR (Nujol, cmꢀ1): 1597, 918,
1
1455, 1512. H NMR (CDCl3, 293 K): d 6.94 (br, aro-
matic protons, 2H), 6.54 (br, aromatic protons, 2H),
2.38 (br, CH3), 1.94 (br, CH), 1.47 (br, CH2). 13C{1H}
NMR (CDCl3, 293 K): d 143.4–142.6 (br, Ph–Cipso),
134.6 (br, Ph–Cp), 128.7 (s, Ph–Co), 127.7 (s, Ph–Cm),
44.4 (br, CH2), 40.0 (s, CH), 21.1 (s, CH3). Mw ¼ 18300;
Mw=Mn ¼ 3:2.
1
889, 843, 756, 740, 697. H NMR (CDCl3, 293 K): d
7.17–6.85 (m, Ph–Hm and Ph–Hp, 3H), 6.80–6.50 (m,
Ph–Ho, 2H) 5.90 (s, C@CH, 1H). 13C{1H} NMR
(CDCl3, 293 K): d 142.9 (s, Ph–C@CH), 139.4 (s, Ph–
Ci), 131.9 (s, Ph–C@CH), 127.8 (s, Ph–Co), 127.6 (s, Ph–
Cm), 126.8 (s, Ph–Cp). Anal. Calc. for (C8H6)n: C, 94.08;
H, 5.92. Found: C, 93.80; H, 6.10%. Mw ¼ 12200;
Mw=Mn ¼ 2:1.
4.16. Attempted p-methylstyrene/CO copolymerization
by 3
The reaction was carried out according to the pro-
cedure described for complex 1 by using 82 mg (0.16
mmol) of 3. Traces of homopolymer were obtained by
adding methanol.
4.13. Phenylacetylene homopolymerization by 1a
The polymerization reaction was carried out accord-
ing to the procedure described for complex 1 using 45

B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
659
4.17. Attempted p-methylstyrene homopolymerization
by 1
the decomposition into palladium metal occurred during
the reaction.
Complex 1 (48 mg, 0.07 mmol) was dissolved in 2 ml
of dichloromethane at )30 °C. After addition of 2.7 ml
(21 mmol) of p-methylstyrene (olefin/palladium molar
ratio 300:1), the solution was slowly warmed up to 0 °C
and allowed to react for 48 h, whereupon it changed
from red to brown. The formation of palladium metal
was observed during this time. Traces of homopolymer
were obtained by adding methanol.
4.20. Reactivity of 1 with PPh3
Complex 1 (35 mg, 0.05 mmol) and PPh3 (13 mg, 0.05
mmol) were dissolved in 0.5 ml of methylene chloride-d2
in an NMR tube at )78 °C. The reaction was monitored
by NMR spectroscopy at )56 °C. The isomerization of 1
to 1a, together with the formation of other unidentified
species, were observed.
4.18. Attempted p-methylstyrene homopolymerization
by 3
4.21. Reactivity of 2 with NEt4Cl
Complex 2 (32 mg, 0.05 mmol) and NEt4Cl (8.3 mg,
0.05 mmol) were dissolved in 0.5 ml of methylene
chloride-d2 in an NMR tube at )60 °C. After a few
seconds the reaction mixture changed from red to yellow
The reaction was carried out according to the pro-
cedure described for complex 1 by using 37 mg (0.07
mmol) of 3. Traces of homopolymer were obtained by
adding methanol.
and
a
white solid precipitated. The formation
of [Pd(g1,g2-C8H12OMe)Cl]2 and free 2,6-(i-Pr)2-
(C6H3)N@C(Me)–C(Ph)@O ligand were detected by
NMR spectroscopy.
4.19. Reactivity of 1 with carbon monoxide
Complex 1 (49 mg, 0.07 mmol) was dissolved in 0.5
ml of methylene chloride-d2 in an NMR tube at )20 °C
and CO was blubbed for 5 min in the resulting solution.
The reaction was monitored by NMR spectroscopy at
)56 °C. The solution was slowly warmed up to 0 °C and
allowed to react for 5 min. The 1H and 13C NMR
spectra of the solution revealed the formation of com-
plex 1a and other unidentified species probably due to
4.22. X-ray crystallography
Crystals of 1 and 1a suitable for X-ray single crystal
studies were precipitated from dichloromethane/hexane.
Diffraction intensities were collected at room tempera-
ture on an Enraf-Nonius CAD-4 diffractometer using
graphite monochromated Mo K radiation for 1, while a
Table 5
Crystal data and details of structure refinement for complexes 1 and 1a
1
1a
Empirical formula
Formula weight
T (K)
C35H42BF4NO2Pd ꢃ 2CH2Cl2
C35H42BF4NO2Pd ꢃ CH2Cl2
871.76
293
786.83
223
ꢁ
k (A)
0.71069
monoclinic
P21=c
0.71069
monoclinic
P21=n
Crystal system
Space group
Unit cell dimensions
ꢁ
a (A)
10.607(3)
22.665(5)
16.730(4)
99.81(3)
3963(2)
4
10.407(1)
18.226(1)
19.031(1)
99.03(2)
3564.9(5)
4
ꢁ
b (A)
ꢁ
c (A)
b (°)
3
ꢁ
V (A )
Z
Density (Mg/m3)
F ð000Þ
1.461
1784
1.466
1616
Crystal size (mm)
h range for data collection
Index range
0.20 ꢅ 0.20 ꢅ 0.35
2.5–20
0.15 ꢅ 0.25 ꢅ 0.30
2.5–23
ꢀ10 6 h 6 10, 0 6 k 6 21, 0 6 l 6 16
3834
3671/0/416
ꢀ11 6 h 6 11, ꢀ20 6 k 6 20, ꢀ20 6 l 6 20
25 678
4919/5/388
Number of reflections collected
Data/restraints/parameters
Goodness-of-fit onF 2
Final R indices [I > 2rðIÞ]
R indices (all data)
1.035
1.067
R1 ¼ 0:0364, wR2 ¼ 0:0912
R1 ¼ 0:0413, wR2 ¼ 0:0957
0.609 and )0.543
R1 ¼ 0:0582, wR2 ¼ 0:1502
R1 ¼ 0:0666, wR2 ¼ 0:1577
0.848 and )0.874
ꢀ3
ꢁ
Largest diffraction peak and hole (e A
)

660
B. Binotti et al. / Journal of Organometallic Chemistry 689 (2004) 647–661
[10] C.S. Slone, D.A. Weinberger, C.A. Mirkin, in: K.D. Karlin (Ed.),
Progress in Inorganic Chemistry, Wiley, New York, 1999;
P. Braunstein, F. Naud, Angew. Chem., Int. Ed. Engl. 40 (2001)
680.
Bruker AXS SMART 2000 CCD diffractometer at 223K
was employed for 1a. The data for this latter were col-
lected using 0.3° wide x scans, crystal-to-detector dis-
tance of 5.0 cm, and corrected for absorption
empirically using the SADABS routine. Data collections
nominally covered a full sphere of reciprocal space with
20 s exposure time per frame.
Crystal data and details of structure refinement are
reported in Table 5. Both structures were solved by
direct methods and refined on F 2 by full-matrix least-
[11] A. Macchioni, C. Zuccaccia, B. Binotti, C. Carfagna, E. Foresti,
P. Sabatino, Inorg. Chem. Commun. 5 (2002) 319.
[12] A. Macchioni, Eur. J. Inorg. Chem. 195 (2003), and references
therein.
[13] B. Binotti, A. Macchioni, C. Zuccaccia, D. Zuccaccia, Comments
Inorg. Chem. 23 (2002) 417.
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ꢁ
H atoms were geometrically positioned (C–H 0.96 A)
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Two molecules of dichloromethane solvent for 1 and
one for 1a were found. Refinement converged at a final
R ¼ 0:036, wR2 ¼ 0:091, S ¼ 1:035 for 1, R ¼ 0:058,
wR2 ¼ 0:150, S ¼ 1:067 for 1a. Molecular graphics were
prepared using ORTEP3 for WindowsNT [29].
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Acknowledgements
J. Lacour, J.J. Jodry, C. Ginglinger, S. Torche-Haldimann,
Angew. Chem., Int. Ed. Engl. 37 (1998) 2379;
This work was supported by grants from the Minis-
ꢀ
nologica (MURST, Rome, Italy), Programma di
Rilevante Interesse Nazionale, Cofinanziamento 2002–
2003.
€
A. Kovacevic, S. Grundemann, J.R. Miecznikowski, E. Clot, O.
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