Insertion reactions of unsymmetrical ester-activated alkynes with o-benzylamine palladacycles: A regioselectivity study

Article abstract of DOI:10.1016/S0020-1693(03)00149-X

The regioselectivities of the insertion reactions of RC≡CCO₂Et (R=Ph, CF₃) into the aryl-palladium bond of several five-membered, ortho-palladated dimethylbenzylamine complexes, [PdCl(C₆H₄CH₂NMe₂

Full text of DOI:10.1016/S0020-1693(03)00149-X

Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
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Insertion reactions of unsymmetrical ester-activated alkynes with
o-benzylamine palladacycles: a regioselectivity study
Amy E. Kelly a, Stuart A. Macgregor c, Anthony C. Willis a,1, John H. Nelson b,
Eric Wenger a,*
a Research School of Chemistry, Australian National University, Building 35, Canberra, ACT 0200, Australia
b Department of Chemistry, University of Nevada, Reno, NV 89557-0020, USA
c Department of Chemistry, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, UK
Received 26 June 2002; accepted 2 September 2002
Dedicated to Professor Martin Bennett whose lifelong passion for organometallic chemistry has been an inspiration for generations of chemists
Abstract
The regioselectivities of the insertion reactions of RCÅ
membered, ortho-palladated dimethylbenzylamine complexes, [PdCl(C6H4CH2NMe2ꢁ
kC,N)(L)] [LꢀPEt3 (2), DMPP (3)], [Pd(C6H4CH2NMe2ꢁkC,N)(NCMe)(L)]PF6 [Lꢀ
[Pd(OSO2CF3)(C6H4CH2NMe2ꢁkC,N)(DMPP)] (6), [Pd(C6H4CH2NMe2ꢁkC,N)(solvent)]PF6 (7) and [Pd(C6H4CH2NMe2ꢁ
/
CCO2Et (Rꢀ
/
Ph, CF3) into the arylꢁ
kC,N)]2 (1), [PdCl(C6H4CH2NMe2ꢁ
MeCN (4), PEt3 (9), DMPP (5)],
/
palladium bond of several five-
/
/
/
/
/
/
/
/
kC,N)(DMPP)(solvent)]PF6 (8), have been compared with the help of multinuclear NMR spectroscopy. In general, the carboxylate
group in the resulting seven-membered palladacycles is preferentially located next to the phenyl group of the benzylamine moiety,
but this substitution pattern can be reversed by use of complexes containing electron-deficient and/or coordinatively-unsaturated
palladium centres. A mechanism, based both on the experimental results described in this paper and on DFT computations, is
proposed.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Palladacycles; Alkyne insertion; Regiochemistry; NMR spectroscopy; DFT calculation; Dimethylbenzylamine
1. Introduction
heterocyclic molecules. In this context, metallacycles
formed with Group 10 metals have attracted most
The insertions of unsaturated molecules into metalꢁ
carbon bonds are fundamental reactions in organome-
tallic chemistry, and the reactions involving alkenes and
CO have been extensively exploited in both organic
syntheses and industrial processes [1,2]. Alkyne insertion
reactions have also been widely studied experimentally,
but mostly in the context of transition metal-catalysed
/
attention [8ꢁ
be prepared directly by cleavage of a Cꢁ
a suitable donor atom [22ꢁ24]. Palladacycles have also
proved to be efficient catalysts for a large variety of
transformations, including the Heck reaction [25,26].
Several mechanistic studies of the insertions of
/
21], especially palladacycles that can often
/
H bond close to
/
alkynes into Niꢁ
/
C and PdꢁC bonds have been reported
/
cyclotrimerization and oligomerization reactions [3ꢁ7].
/
[27ꢁ32], but very few are concerned with the factors
/
Recently, however, insertion reactions of alkynes invol-
ving metallacycles have proved very useful in the
preparation of synthetically important polycyclic and
governing the regiochemistry of these insertions. Both
electronic and steric effects have been invoked to explain
the regioselectivities observed for the insertions of
alkynes into Pdꢁaryl bonds [16,19,33], but, although
/
the latter argument is generally preferred, neither could
satisfactorily be applied in all cases. Furthermore, in
some cases, the insertion reactions of ester-activated
alkynes, RCO2R?, gave conflicting regioselectivities. For
* Corresponding author. Tel.: ꢂ
0750.
/
61-2-6125-3931; fax: ꢂ61-2-6125-
/
E-mail address: wenger@rsc.anu.edu.au (E. Wenger).
1
Single crystal X-ray diffraction unit.
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00149-X

80
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
example, the reactions of PhCÅ
/
CCO2Et with
corresponding palladacycles [PdCl(C6H4CH2NMe2ꢁ
kC,N)(L)] [LꢀPEt3 (2), DMPP (3); DMPPꢀ3,4-
dimethyl-1-phenylphosphole]. When more than one
equiv. of phosphine ligand was added, the PdꢁN bond
of the palladacycle was also cleaved, leading to bis(pho-
sphine) adducts. For example, addition of excess PEt3 to
1 afforded [PdCl(o-C6H4CH2NMe2)(PEt3)2] (10); the
palladacycle 2 being restored by treatment of 10 with
sulfur.
/
[PdCl(C6H4CH2NMe2ꢁkC,N)]2 (1) have been shown
/
/
/
to give a seven-membered palladacycle having the
carboxylate group in the b-position of the resulting
vinyl group (see 11b in Scheme 2) [34], whereas the same
/
reaction with the cationic species [Pd(C6H4NÄ
kC,N)(L)]ꢂ (Lꢀ
1 or 2 equiv. of CH3NO2) gave the
alternative a-isomer [35].
/
NPhꢁ
/
/
Recently, studies of the insertions of various alkynes
undertaken with the phosphanickelacycles [NiBr(C6H4-
Abstraction of the chloride ligand from complexes 1
to 3 was achieved readily by treatment with AgPF6. In
acetonitrile, the corresponding solvated cationic com-
CH2PPh2ꢁ
have suggested that electronic factors such as alkyne
frontier orbital control and the polarisation of the Niꢁ
/
kC,P)(PR3)] [PR3ꢀ/PEt3, PPh(CH2Ph)2]
/C
plexes
[LꢀMeCN (4), PEt3 (9), DMPP (5)] were formed,
and the products can be isolated as moisture sensitive
solids. The complex [Pd(OSO2CF3)(C6H4CH2NMe2ꢁ
[Pd(C6H4CH2NMe2ꢁkC,N)(NCMe)(L)]PF6
/
bond, which is highly dependent on the trans-ligand,
were important in determining the regiochemical out-
/
come of these reactions [36ꢁ/38]. In this paper, we report
/
a spectroscopic investigation similar to that carried out
with the nickelacycles [37]. The insertions of ester-
activated alkynes with various benzylamine pallada-
cycles were studied with the aim of determining the main
factors influencing the regiochemistry of these reactions.
kC,N)(DMPP)] (6) was prepared similarly by treatment
of 1 with AgOSO2CF3.
Similar reactions carried out between AgPF6 and 1 or
3 in CH2Cl2 or CH3NO2 led to very reactive, ill-defined
cationic complexes that have been formulated as
[Pd(C6H4CH2NMe2ꢁ
/
kC,N)(solvent)]PF6 (7) and [Pd-
(C6H4CH2NMe2ꢁkC,N)(DMPP)(solvent)]PF6 (8), re-
/
spectively; these complexes were not isolated and were
used directly for the reactions with the alkynes. The
resonances in the 13C NMR spectra of 7 in either
CD2Cl2 or CD3NO2 were very broad, but they suggested
that coordination of the solvent molecules may occur in
these species, although the number attached to the metal
centre remained unclear. Complex 8 in CH2Cl2 did not
show conclusive evidence of solvation and it is possible
that this complex forms a highly unsaturated 14e
species.
2. Experimental results
2.1. Preparation of the five-membered palladacycles
The five-membered palladacycle [PdCl(C6H4CH2-
NMe2ꢁkC,N)]2 (1) was prepared by ortho-palladation
/
of dimethylbenzylamine as reported previously [24,39].
This dinuclear complex was readily cleaved by treatment
with 1 equiv. of tertiary phosphine (Scheme 1). Addition
of PEt3 or DMPP to 1 led quantitatively to the
1
The H NMR spectra of the mononuclear complexes
2ꢁ
region 2.4ꢁ
groups in the region 3.4ꢁ
/
9 showed only one signal for the NMe2 groups in the
2.9 ppm and one resonance for the NCH2
4.0 ppm, indicative of an
/
/
average planar geometry of the five-membered ring in
solution although, in the solid state, 3 posseses a folded
five-membered ring (see below). The phosphine ligands
in the palladacycles are always located trans to the
amine donor and their group of chloro-complex chemi-
cal shift is only slightly affected by changes in the ligand
trans to the PdꢁC bond, cf. dP 33.0 for the PEt3 2 versus
/
33.8 for cationic 9, while the phosphorus atom of
DMPP appears at dP 37.0 in 3, 35.0 in cationic 5, 36.6
in the triflate adduct 6 and 35.3 for the CH2Cl2-solvated
species 8.
2.2. Reactions of the five-membered palladacycles with
ester-activated alkynes
Treatment of complexes 1ꢁ
CCO2Et (RꢀPh, CF3) resulted in the formation of
seven-membered palladacycles (Scheme 2), the substitu-
/
8 with the alkynes RCÅ
/
/
Scheme 1.

A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ
/97
81
tions of which were determined spectroscopically. The
conditions and isomer ratios are summarised in Table 1.
The seven-membered metallacycles 11 and 13ꢁ22 are
/
non-planar and show two 1H NMR signals for the
inequivalent benzylic protons of the palladacycle in the
region dH 3.0ꢁ/4.0 and two signals for the NMe2 group
between dH 2.0ꢁ/3.0. Due to the formation of mixtures
and the sensitivity of most cationic products to moist-
ure, multinuclear NMR spectroscopy proved to be the
most convenient technique to assign the structure of the
products. Attempted reactions of the palladacycles with
RCÅ
/
CCO2Et (RꢀH, Me) were always accompanied by
/
decomposition, probably due to b-hydride eliminations
occuring in the insertion products, hence reactions with
these alkynes were abandoned.
In order to assess the validity of the NMR techniques
we planned to use, the previously reported insertion of
PhCÅ
/
CCO2Et into the PdꢁC bond of the dinuclear
/
species 1 was repeated [34]. Spectroscopic determination
of the substitution pattern could not be achieved on the
seven-membered dinuclear species 11b, hence the latter
was cleaved by addition of PEt3, 1 equiv. leading to
[PdCl{C(Ph)Ä
(13b), showing a 31P NMR signal at dP 24.9, while 2
equiv. of phosphine gave [PdCl{C(Ph)ÄC(CO2Et)-
/
C(CO2Et)C6H4CH2NMe2ꢁ
/
kC,N}(PEt3)]
/
C6H4CH2NMe2}(PEt3)2] (12) (dP 10.4). For this reac-
tion, determination of the regioselectivity proved easier
by use of 12 rather than the palladacycle 13b, but for all
the other reactions, the spectroscopic analyses were
carried out with the seven-membered palladacycles.
The geometry of the b-CO2Et product2 12 was con-
firmed by use of the GEOSY pulse sequence: irradiation
of the CH2 protons of the PEt3 ligands (dH 1.20ꢁ1.54)
/
gave a clear response from the doublet at dH 7.58 due to
Scheme 2.
2
The nomenclature a and b refers to the position of the
substituents on the vinyl fragment of the palladacycle.
Table 1
Regioisomer distributions for the reactions of the five-membered palladacycles 1ꢁ
/
8 with the alkynes PhCÅ
/
CCO2Et (A) and F3CCÅ
/
CCO2Et (B)
CO2R in b
Entry Complex
Alkyne Solvent
T (8C)/time
CO2R in a
1
2
[PdCl(C6H4CH2NMe2 ꢁ
[PdCl(C6H4CH2NMe2 ꢁ
[PdCl(C6H4CH2NMe2 ꢁ
[Pd(C6H4CH2NMe2 ꢁ
[Pd(C6H4CH2NMe2 ꢁ
[Pd(C6H4CH2NMe2 ꢁ
[PdCl(C6H4CH2NMe2 ꢁ
[PdCl(C6H4CH2NMe2 ꢁ
/
kC,N)]2 (1)
A
A
A
A
A
A
B
B
B
B
B
B
B
B
CH2Cl2
C6H5Me
C6D6
20 8C/2 h
60 8C/16 h
50 8C/24 h
20 8C/1.5 h
40 8C/16 h
20 8C/0.5 h
20 8C/16 h
50 8C/24 h
40 8C/2 h
40 8C/3 h
40 8C/3 h
20 8C/1 h
20 8C/1 h
0 8C/5 min
0
14
100
86
/
kC,N)(PEt3)] (2)
3
/
kC,N)(DMPP)] (3)
B/
5
0
ꢀ95
/
4
/
kC,N)(NCMe)2]PF6 (4)
kC,N)(DMPP)(NCMe)]PF6 (5)
kC,N)(solvent)]PF6 (7)
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
C6D6
100
87
40
70
70
59
62
73
16
55
6
5
/
13
60
30
30
41
38
27
84
45
94
6
/
7
/
kC,N)]2 (1)
8
/
kC,N)(DMPP)] (3)
9
[Pd(OSO2CF3)(C6H4CH2NMe2 ꢁ
/
kC,N)(DMPP)] (6)
CD2Cl2
CD2Cl2
CD3CN
CH2Cl2
CH3NO2
CH2Cl2
10
11
12
13
14
[Pd(C6H4CH2NMe2 ꢁ
[Pd(C6H4CH2NMe2 ꢁ
[Pd(C6H4CH2NMe2 ꢁ
[Pd(C6H4CH2NMe2 ꢁ
[Pd(C6H4CH2NMe2 ꢁ
/
kC,N)(DMPP)(NCMe)]PF6 (5)
kC,N)(DMPP)(NCMe)]PF6 (5)
kC,N)(DMPP)(solvent)]PF6 (8)
kC,N)(solvent)]PF6 (7)
/
/
/
/
kC,N)(solvent)]PF6 (7)

82
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
NMe2ꢁkC,N}(PEt3)] (13b) which was obtained inde-
/
pendently from addition of PEt3 to 11b; the minor
species was tentatively assigned to the alternative a-
CO2Et regioisomer 13a.
The insertion reaction of PhCÅ/CCO2Et with
the cationic complex 4 led to only one insertion
product which was identified by X-ray crystallography
as
being
[Pd{C(Ph)Ä
/
C(CO2Et)C6H4CH2NMe2ꢁ
/
kC,N}(NCMe)2]PF6 (15b) (see below). The same regio-
chemistry was determined spectroscopically by GOESY
analysis of the PEt3 adduct 16b, formed by addition of 1
equiv. of the phosphine to the reaction mixture contain-
ing 15b, which showed a clean response of the doublet at
dH 7.68 due to the o-proton of the phenyl substituent
when irradiating the CH2 group of the PEt3 ligand.
When the reaction was carried out with [Pd(C6H4-
Fig. 1. Principal interactions observed during the GOESY experi-
ments with 12 and 14b.
the ortho-hydrogen atoms of the a-phenyl substituent
(Fig. 1), hence indicating the proximity of the latter to
the phosphine ligand.
Both 19F and 31P NMR spectroscopy, when applic-
able, proved convenient for the investigation of the
geometry of the palladacycles with some trends, identi-
fied during this work, being particularly useful for the
assignment of the regioisomers (see also Table 2):
CH2NMe2ꢁkC,N)(solvent)]PF6 (7), the very reactive
/
insertion products were first stabilised by addition of
MeCN, and then treated with 1 equiv. of PEt3 to give a
40:60 mixture of two isomers. The minor product
was readily identified as being 16b, the major product
i) the 31P NMR chemical shift of a phosphine-adduct
bearing the carboxylate substituent in the b-position
was always more shielded than that of the opposite
isomer having the carboxylate adjacent to the metal
centre,
being,
in
this
case,
the
opposite
regio-
kC,N}-
isomer [Pd{C(CO2Et)Ä
/
C(Ph)C6H4CH2NMe2ꢁ
/
(PEt3)(NCMe)]PF6 (16a). The latter was identified
from its deshielded 31P NMR chemical shift (dP 29.6)
and from the 13C NMR signal of the carbonyl group
which is observed as a doublet, indicative of its
proximity to the phosphine ligand. Similar reaction of
ii) the 19F chemical shift of the vinylic CF3 group was
always observed in the region dF
for the b-CO2Et isomers whereas the alternative a-
CO2Et isomers were more shielded (dF 58.0 to
61.0), and
ꢃ
/
50.0 to ꢃ
/
53.0
PhCÅ
/
CCO2Et
with
[Pd(C6H4CH2NMe2ꢁkC,N)-
/
(DMPP)(NCMe)]PF6 (5) led to a 87:13 mixture of the
two regioisomers, the major one showing a 31P NMR
signal at dP 25.4 while the resonance of the minor one
appeared at dP 27.4. In this case, the GOESY analysis
proved inconclusive but, by analogy with the data for
16b and based on trend (i) discussed above, the major
ꢃ
/
ꢃ
/
iii) when a JPF coupling was observed, the isomer
bearing the CF3 group adjacent to the metal showed
4
always a JPF value of approximately 5ꢁ
/
7 Hz while
the 5JPF coupling measured for the a-CO2Et isomer
was in the range 0ꢁ2 Hz.
insertion compound was formulated as [Pd{C(Ph)Ä
C(CO2Et)C6H4CH2NMe2ꢁkC,N}(DMPP)(NCMe)]PF6
(17b) and the minor one as the opposite isomer (17a).
The insertion reactions carried out with CF3CÅ
CCO2Et were easier to analyse due to the presence of
the NMR active CF3 group. The reaction mixture of
dinuclear 1 with this alkyne at room temperature was
treated subsequently with PEt3 and 31P NMR analysis
showed a 70:30 mixture of two regioisomers, the signal
of the major species appearing as a quartet with a JFP
value of 5.8 Hz, while the coupling of the second signal
was only 2.0 Hz; the corresponding CF3 signals
appeared at dF
spectrum. The 13C NMR of the major species showed
the quaternary carbon atom bonded to palladium (dC
2
148.27), identified by its characteristic JPC value of 2.1
Hz, also strongly coupled with the CF3 group (JFC
32.5 Hz) implying that this carbon atom was bearing the
CF3 substituent. Therefore, the major product was
/
/
/
In contrast to the reaction of 1, the insertion reactions
of the alkynes with the five-membered palladacycles
bearing phosphine ligands (2, 3, 5, 6 and 8) required
/
heating (Table 1). The reaction of 3 with PhCÅ
/
CCO2Et
in C6D6 at 50 8C for 24 h showed the formation of only
one insertion product (14b) having a singlet at dP 27.5 in
the 31P NMR spectrum; in CD2Cl2 this singlet appeared
at dP 26.9 and a very small peak at dP 27.2, tentatively
assigned to the opposite isomer 14a, was also observed.
The product 14b was identified by the GOESY pulse
sequence as being the b-CO2Et isomer [PdCl{C(Ph)Ä
/
ꢃ
/
50.4 and ꢃ
60.0 in the 19F NMR
/
C(CO2Et)C6H4CH2NMe2ꢁ
/
kC,N}(DMPP)] (Fig. 1)
and, in this case, the assignment was confirmed by
single crystal X-ray analysis (see below).
The major isomer isolated from the reaction of 2 with
ꢀ
/
PhCÅ
/
CCO2Et at 60 8C for 16 h showed a 31P NMR
signal at dP 24.9 together with a second minor signal at
dP 27.0. The chemical shift of the major product was
identified as being [PdCl{C(CF3)Ä
NMe2ꢁkC,N}(PEt3)] (18b) while the minor one was
/
C(CO2Et)C6H4CH2-
identical to that of [PdCl{C(Ph)Ä/C(CO2Et)C6H4CH2-
/

A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ
/97
83
Table 2
Comparison of the phosphine ligands 31P and the CF3 groups 19F NMR chemical shifts for the seven-membered palladacycles 11ꢁ
a-position, bꢀCO2Et in b-position; when observed, the JPF values (averaged, Hz) are given in parenthesis)
/22 (aꢀ/CO2Et in
/
Palladacycle
d(31P)
d(19F)
Palladacycle
d(31P)
d(19F)
13a
14a
16a
17a
18a
19a
20a
21a
22a
27.0
27.2
29.6
27.4
32.1
29.9
27.1
13b
14b
16b
17b
18b
19b
20b
21b
22b
24.9
26.9
25.8
25.4
29.7
28.1
24.8
ꢃ
/
60.0 (2.0)
60.7 (1.9)
60.7
ꢃ
/
50.4 (5.7)
52.8 (7.0)
52.9 (5.9)
52.8
ꢃ
/
ꢃ
/
ꢃ
/
ꢃ
/
ꢃ
/
60.6
ꢃ
/
27.0
ꢃ
/
58.5
25.8
ꢃ
/
52.4 (6.4)
formulated as [PdCl{C(CO2Et)Ä
/
C(CF3)C6H4CH2-
spectrum of the a-CO2Et regioisomer (21a), obtained
almost pure from the reaction carried out in CH2Cl2, the
signal due to the aromatic proton H6 (dH 7.65) appeared
as a doublet of quartets, indicative of a coupling with
the CF3 substitutent, hence confirming the location of
the latter close to the phenyl moiety.
NMe2ꢁ
/
kC,N}(PEt3)] (18a). The structure of 18b was
confirmed by X-ray diffraction analysis (see below).
The reaction of the DMPP-palladacycle (3)
with CF3CÅ
but gave
Cl{C(CF3)Ä
(19b) and [PdCl{C(CO2Et)Ä
/
CCO2Et required heating to 50 8C
a
similar 70:30 ratio between [Pd-
/
C(CO2Et)C6H4CH2NMe2ꢁ
/
kC,N}(DMPP)]
/
C(CF3)C6H4CH2NMe2ꢁ
/
kC,N}(DMPP)] (19a), the two compounds having
NMR data analogous to those of the PEt3 adducts
18b and 18a, respectively. Both structures were con-
firmed by GOESY analyses. The same NMR identifica-
tion methodology was used successfully for
the assignment of the seven-membered pallada-
3. Molecular structures of [PdCl(C6H4CH2NMe2
/
ꢁ
kC,N)(DMPP)] (3), [PdCl{C(Ph)Ä
/
C(CO2Et)C6H4CH2NMe2
/
kC,N}(DMPP)] (14b),
ꢁ
[Pd{C(Ph)Ä
/
C(CO2Et)C6H4CH2NMe2
/
ꢁ
kC,N}(NCMe)2]PF6 (15b) and [PdCl{C(CF3)Ä
/
cycles [Pd(OSO2CF3){C(CF3)Ä
Me2ꢁkC,N}(DMPP)] (20b) and [Pd(OSO2CF3){C(CO2-
Et)ÄC(CF3)C6H4CH2NMe2ꢁkC,N}(DMPP)] (20a), ob-
tained from reaction of the triflate analogue
/C(CO2Et)C6H4CH2N-
C(CO2Et)C6H4CH2NMe2
/
kC,N}(PEt3)] (18b)
ꢁ
/
/
/
The molecular geometries of the palladacycles 3, 14b,
15b and 18b are shown in Figs. 2ꢁ5, respectively;
/
[Pd(OSO2CF3)(C6H4CH2NMe2ꢁ
or the cationic species [Pd{C(CF3)Ä
C6H4CH2NMe2ꢁ
and
[Pd{C(CO2Et)Ä
/
kC,N)(DMPP)]
(6),
C(CO2Et)-
selected values of bond lengths and angles are given in
Table 3.
In the molecular structure of 3, the palladium atom is
in a pseudo square-planar environment, the data being
similar to those of the methylated analogue [PdCl-
/
/
kC,N}(DMPP)(NCMe)]PF6
(22b)
/
C(CF3)C6H4CH2NMe2ꢁ
/
kC,N}-
(DMPP)(NCMe)]PF6 (22a) (see also Table 2). The latter
were obtained in various ratios (see Table 1) either by
(C6H4CH(Me)NMe2ꢁkC,N)(DMPP)] [40].
/
reaction of [Pd(C6H4CH2NMe2ꢁ
Me)]PF6 (5) in CH2Cl2 or CD3CN, or by reaction of
the solvated species [Pd(C6H4CH2NMe2ꢁkC,N)-
/
kC,N)(DMPP)(NC-
The seven-membered palladacycles in 14b, 15b and
18b have boat-conformations similar to those of related
/
phosphanickelacycles [37] or palladacycles [34,41ꢁ43].
/
(DMPP)(solvent)]PF6 (8), initially formed by abstrac-
tion of the chloride with AgPF6 in CH2Cl2. In the latter
reaction, CH3CN was added subsequently in order to
stabilise the insertion products.
The carboxylate substituents are located on the b-
carbon of the vinyl fragment (C(29) for 14b, C(21) for
15b and C(18) for 18b). The dihedral angle between the
plane defined by N(1)ꢁ
/
Pd(1)ꢁ
/
C and that of the
The cationic complex [Pd(C6H4CH2NMe2ꢁ
(solvent)]PF6 (7) was reacted similarly with CF3CÅ
/
kC,N)-
aromatic ring C(1)ꢁC(6) is 97.738 in 15b and 93.518 in
/
/
18b, while in 14b it is increased to 102.748, probably due
to the bulk of the phosphole ligand. The distances in
CCO2Et in either CH2Cl2 or CH3NO2. The insertions
occured readily at room temperature or even 0 8C to
form reactive mixtures of insertion products that were
stabilised by addition of CH3CN. The resulting pallada-
these complexes are unexceptional. In 15b, the Pdꢁ
distance for the acetonitrile coordinated trans to Pdꢁ
NMe2 is shorter than that of the same ligand trans to
/N
/
˚
cycles [Pd{C(CF3)Ä
(NCMe)2]PF6 (21b) and [Pd{C(CO2Et)Ä
CH2NMe2ꢁkC,N}(NCMe)2]PF6 (21a) were then read-
ily identified by NMR spectroscopy. In the H NMR
/
C(CO2Et)C6H4CH2NMe2ꢁ
/
kC,N}-
Pdꢁ
trans-influence of those two groups. This influence is
also reflected in the Pd(1)ꢁN(1) distance which is
elongated when the basicity of the trans phosphine
/
C (2.037(6) versus 2.135(5) A), reflecting the relative
/
C(CF3)C6H4-
/
/
1

84
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
Fig. 2. Molecular structure of [PdCl(C6H4CH2NMe2 ꢁ
levels; hydrogen atoms have been omitted for clarity.
/
kC,N)(DMPP)] (3) with selected atom labeling. Thermal ellipsoids show 30% probability
Fig. 3. Molecular structure of [PdCl{C(Ph)Ä
/
C(CO2Et)C6H4CH2NMe2 ꢁkC,N}(DMPP)] (14b) with selected atom labeling. Thermal ellipsoids show
/
30% probability levels; hydrogen atoms have been omitted for clarity.

A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ
/97
85
Fig. 4. Molecular structure of the cation of [Pd{C(Ph)Ä
/
C(CO2Et)C6H4CH2NMe2 ꢁkC,N}(NCMe)2]PF6 (15b) with selected atom labeling. Thermal
/
ellipsoids show 30% probability levels; hydrogen atoms have been omitted for clarity.
Fig. 5. Molecular structure of [PdCl{C(CF3)Ä
/
C(CO2Et)C6H4CH2NMe2 ꢁkC,N}(PEt3)] (18b) with selected atom labeling. Thermal ellipsoids show
/
30% probability levels; hydrogen atoms have been omitted for clarity.

86
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
Table 3
CH2Cl2 instead of MeCN, the ratio of the b-product
decreased slightly (entry 10 in Table 1), the same ratio of
approximately 60:40 in favour of the b-isomer being
observed with the more labile triflate complex 6. This
ratio decreased even further to 55:45 when the reaction
of solvated complex 7 was carried out in CH3NO2 (entry
13).
The regioselectivity of these insertions is altered even
more dramatically when coordinatively unsaturated
palladacycles are used in a poorly coordinating solvent
such as CH2Cl2. Reaction of the cationic complex 7 with
˚
Selected values of bond lengths (A) and bond angles (8) for the
palladacycles 3, 14b, 15b and 18b
3
15b
14b
18b
Bond lengths
Pd(1)ꢁ
Pd(1)ꢁ
Pd(1)ꢁ
Pd(1)ꢁ
CÄ
C d
/
L1 a
L2 b
N(1)
C c
2.233(1)
2.4046(12)
2.156(3)
2.005(4)
2.037(6) 2.2360(8) 2.2537(6)
2.135(5) 2.4055(8) 2.3669(7)
/
/
2.091(5) 2.159(2)
1.979(6) 2.008(3)
1.327(8) 1.354(4)
2.186(2)
2.014(2)
1.333(3)
/
/
Bond angles
N(1)ꢁPd(1)ꢁ
N(1)ꢁPd(1)ꢁ
CꢁPd(1)ꢁ
L2
/
/
C a
L1
82.07(15)
170.3(1)
89.4(2)
90.6(1)
91.40(8)
PhCÅ
/
CCO2Et gave the opposite a-CO2Et product as
/
/
175.0(2) 169.75(7) 171.91(6)
173.9(2) 172.55(8) 174.46(6)
the major isomer. Similarly, insertions of CF3CÅ
/
/
/
174.13(11)
CCO2Et with the palladacycles 7 and 8 in CH2Cl2
(entries 12 and 14) forms preferentially the product with
the carboxylate in the a-position regardless of the
presence or absence of the auxilliary phosphine ligand,
which suggests that the latter is dissociated during the
insertion step (see below).
a
b
c
L1 is trans to Pd(1)ꢁ
/
N(1): P(1) for 3, 14b and 18b, N(3) for 15b.
C: Cl(1) for 3, 14b and 18b, N(2) for 15b.
L2 is trans to Pd(1)ꢁ
C(1) for 3, C(14) for 15b, C(22) for 14b and C(16) for 18b.
/
d
C(14)ꢁ/C(21) for 15b, C(22)ꢁ
/
C(29) for 14b, C(16)ꢁC(18) for 18b.
/
˚
ligand is increased, e.g. 2.2360(8) A for the phosphole
Systems in which similar changes in regioselectivity
occur, viz. the electron-withdrawing group of the alkyne
is located adjacent to the metal in the insertion product,
have been previously reported. They generally involve
electrophilic palladium complexes, e.g. reaction of the
˚
complex 14b and 2.2537(6) A for the PEt3 adduct 18b.
4. Discussion
cationic
nitromethane-adduct
[Pd(C6H4NÄ
/
NPhꢁ
/
The reactions of the ortho-palladated benzylamine
kC,N)(solvent)]ꢂ [35] (see Introduction) or the palla-
dium-catalysed preparation of coumarins by reaction of
complexes 1ꢁ
/
8 with the two alkynes RCÅ
/
CCO2Et (Rꢀ
/
Ph or CF3) proved to be very clean and suitable for the
study of the regiochemistry by spectroscopic means. The
choice of the auxiliary phosphine ligand DMPP in
complexes 3, 5, 6 and 8 was prompted by the presence
of the two methyl groups facilitating the GOESY
experiments and the increased lability of this ligand
EtCÅ
sphere in which an electron-deficient palladiumꢁ
bonyl complex can be postulated.
The insertion of an alkyne into a Pdꢁ
shown in several cases to take place from a four-
coordinate palladium intermediate formed initially by
displacement of an auxilliary ligand by the incoming
alkyne, e.g. exchange of one PPh3 from trans-
[PdCl(R)(PPh3)2] by the alkyne [28], or, in the case of
dinuclear species such as 1, opening of the halide bridge
[31]. This dissociative mechanism is reflected by the
/
CC(O)Me with o-iodophenol under CO atmo-
/car-
/C bond has been
when compared to trialkylphosphine ligands [44ꢁ
hence allowing insertions under milder conditions.
However, this ligand is known to undergo DielsꢁAlder
/46],
/
reactions with alkenes [47], but with alkynes insertion
occurs in preference to cycloaddition [43].
Both alkynes insert readily to form seven-membered
palladacycles, giving preferentially the regioisomer bear-
ing the carboxylate in the b-position. This isomer is
different conditions required by complexes 1ꢁ
with the alkynes (Table 1). When a coordination site cis
to the PdꢁC bond is readily available, e.g. by use of
/8 to react
/
formed almost exclusively when PhCÅ
acted with the palladacycles 1ꢁ5, which is in agreement
with the previously reported reaction of this alkyne with
1 or related complexes [11,34,48ꢁ51]. However, inser-
CCO2Et give increased amounts of the
/CCO2Et is re-
dinuclear 1 (entries 1 and 7) or its solvated analogues
prepared by halide abstraction with AgPF6 (entries 4, 6
and 13), the alkynes react readily at room temperature;
in poorly coordinating solvents such as CH2Cl2 (entry
14), the cationic complex 7 reacts even at 0 8C. However,
when a better cis-donor ligand such as a phosphine is
present, heating is required in order to exchange the
ligand for the alkyne prior to insertion, hence the
presence of a phosphine ligand does not affect the
regioselectivity of the reaction but only the reaction
conditions. In the case of reported reactions of ortho-
palladated benzylamine complexes with styrene, it has
also been postulated that opening of the palladacycle by
/
/
tions with CF3CÅ
/
a-CO2Et isomer, which is presumably due to the
reduced polarisation of the triple bond in the latter
alkyne [37]. The insertions of CF3CÅ/CCO2Et with
complexes 1, 3 and 5 always gave a ratio of approxi-
mately 70:30 in favour of the b-CO2Et isomer. This
regiochemistry is in contrast with the result obtained for
the insertion of this alkyne with [NiBr(C6H4CH2PPh2ꢁ
/
kC,P)(PR3)], in which only the product bearing the
ester group adjacent to the metal was formed [37].
However, when the reaction of 5 was carried out in
cleavage of the PdꢁN bond could occur [52], but such a
/

A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ
/97
87
mechanism has not been observed during the kinetic
studies carried out with 1 and alkynes [31].
electron-rich carbon atom of the alkyne is interacting
with the carbon atom bonded to palladium. An inter-
action involving frontier orbitals has been proposed for
the regiocontrol of alkyne insertions with phosphanick-
elacycles [37,38], but orbital control during the reaction
The mechanism we propose for the insertions of RCÅ
/
CCO2Et is illustrated in Scheme 3. Addition of the
alkyne will initially lead to the four-coordinate inter-
mediate 23, in which the ligand cis to the PdꢁC bond is
displaced. DFT calculations suggest that this is likely
even when a labile ligand such as NCMe is located in the
/
of F3CCÅ
/
CCO2Et with 1 would favour formation of the
a-CO2Et product which is in contrast with the experi-
mental results. The difference between the two systems
may arise from the fact that the mechanism for the
nickel analogue involves five-coordinate intermediates
in which the metal centre is more electron-rich than is
palladium in the three- or four-coordinated ones.
trans position. Addition of HCÅ
complex CHCH2NH2ꢁ
[Pd(CHÄ
Me)]ꢂ, in which NCMe is trans to Pdꢁ
intermediate CHCH2NH2ꢁ
[Pd(CHÄ
CH)(NCMe)]ꢂ (27) to be more stable than [Pd(CHÄ
CHCH2NH2ꢁkC,N)(HCÅ
CH)(PH3)]ꢂ (28) in which
the phosphine rearranged to the trans position (energy
of 27ꢀ free
free PH3 is 24.7 kJ molꢃ1 lower than 28ꢂ
/
CH to the model
kC,N)(PH3)(NC-
C, showed the
kC,N)(HCÅ
/
/
/
/
/
/
/
The increased formation of an a-CO2Et isomer
observed with electrophilic palladacycles could poten-
tially be caused by two different transition states. An
increase of the charge on the palladium atom may
favour a transition state such as 25 in which the
electron-rich alkyne carbon interacts preferentially
with the metal centre. However, DFT calculations
showed that the lowest transition state for an insertion
/
/
/
/
NCMe) (Fig. 6). The lowest-energy geometries com-
puted for these species show the alkyne to be perpendi-
cular to the coordination plane of the palladium centre.
Computations carried out with [Pd(CHÄ
/
CHCH2-
NH2)(h2-PhCÅCCO2H)]ꢂ (Fig. 7) indicated that the
parallel isomer 29 , showing a weak interaction between
/
from the model complexes [Pd(CHÄ
/
CHCH2NH2)(h2-
PhCÅ
/
CCO2H)]ꢂ would favour the b-CO2H product by
jj
32.5 kJ molꢃ1 (Fig. 7). Alternatively, as the pallada-
cycles favouring a-CO2H products are mostly coordina-
tively unsaturated species, a coordination of the ester
group to the metal during the insertion step cannot be
ruled out (as depicted in 26). Such an interaction has
been postulated for the insertions of alkynylphosphines
[53] or thioalkynes [54] into nickelacycles or for the
palladium-catalysed reaction of arylpropiolamide with
iodoarenes [55]. However, the DFT calculations carried
the carboxylate group and the metal centre, and the
isomer with the alkyne perpendicular to the coordina-
tion plane, 29Þ, had very similar energies, as previously
reported for [PdCl(Me)(NH3)(h2-C2H2)] [30].
The formation of the b-CO2Et product is thought to
arise from a transition state (24) in which the more
out with the model complex [Pd(CHÄ
/
CHCH2NH2)(h2-
PhCÅ
/
CCO2H)]ꢂ did not identify any interaction of this
type as being present in the transition state leading to
the a-CO2H isomer, but it remains the most likely
explanation.
In summary, we have shown that the regiochemistry
of the insertion of an alkyne into the PdꢁC bond of
/
palladacycles formed from dimethylbenzylamine is de-
pendent on the coordination environment of the metal
centre. By use of highly electron-deficient, coordina-
tively unsaturated palladacycles, the regioselectivity can
be reversed when compared to that usually found for
these reactions. The regiochemistry observed in these
reactions is thought to depend mostly on the coordina-
tion ability of the ester group to the metal centre during
the insertion step, process that could also involve
participation of the counter-ion or dissolved silver salts.
The main difficulty encountered in this work arises from
the ill-defined coordination environment of the cationic
palladacycles in solution, hence these reactions will
require further investigations by use of computational
and spectroscopic methods in order to identify the exact
nature of the reactive species that undergo insertion.
Scheme 3.

88
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
Fig. 6. Optimized geometries (A, 8) and relative energies (kJ molꢃ1) computed for the cationic model complexes [Pd(CHÄ
kC,N)(HCÅ CHCH2NH2 ꢁkC,N)(HCÅ
CH)(NCMe)]ꢂ (27) and [Pd(CHÄ CH)(PH3)]ꢂ (28).
/
CHCH2NH2 ꢁ
/
˚
/
/
/
/
Fig. 7. Optimized geometries (A, 8) and relative energies (kJ molꢃ1) for the two isomers of [Pd(CHÄ
/
CHCH2NH2)(h2-PhCÅ
/
CCO2H)]ꢂ (29 and
˚
jj
29Þ) and fully optimized transition states computed for the insertion steps leading to the alternative a-CO2H and b-CO2H seven-membered
palladacycles.

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89
5. Experimental
5.2.1.2. [PdCl(C6H4CH2NMe2)(PEt3)2] (10). This
compound was obtained quantitatively by addition of
2.1 equiv. of PEt3 to a solution of 1 in CH2Cl2. 1H NMR
(200 MHz, C6D6): d 0.93 (app. quint, 18H, JHH 7.6,
CH3 of PEt3), 1.45 (br m, 12H, CH2 of PEt3), 2.30 (br s,
6H, NMe2), 3.75 (br s, 2H, NCH2), 7.02 (app. t, 2H, J
6.5, Harom), 7.50 (app. d, 2H, J 6.5, Harom).
5.1. General procedures
All experiments, unless otherwise specified, were
carried out under argon using standard Schlenk techni-
ques. All solvents were dried and degassed prior to use.
NMR spectra were recorded on a Varian XL-200E (1H
at 200 MHz, 13C at 50.3 MHz, 31P at 81.0 MHz), a
Varian Gemini 300BB or Varian Mercury 300 (1H at 300
MHz, 13C at 75.4 MHz, 31P at 121.4 MHz), or a Varian
Inova-500 instrument (1H at 500 MHz, 13C at 125.7
31P{1H} NMR (81 MHz, C6D6): d 13.6.
5.2.1.3. [PdCl(C6H4CH2NMe2ꢁkC,N)(DMPP)] (3).
/
This complex was prepared following the procedure
published for analogous DMPP-coordinated pallada-
cycles [40].
MHz). The chemical shifts (d) for H and 13C are given
1
1H NMR (500 MHz, CDCl3): d 2.06 (app t, 6H, J 1.0,
in ppm relative to residual signals of the solvent and to
external 85% H3PO4 for 31P. The spectra of all nuclei
1
(except H) were H-decoupled. The coupling constants
CH3DMPP), 2.81 (d, 6H, JPH 2.5, NMe2), 3.95 (d, 2H,
4
2
4
4JPH 2.5, CH2), 6.67 (dq, 2H, JPH 32.5, JHH 1.0, Ha-
1
DMPP), 6.81 (app td, 1H, 3JHHꢀ4
/
JPH 7.5, 4JHH 1.2, H6),
(J) are given in Hz with an estimated error of 90.2 Hz.
/
6.91 (ddd, 1H, JH4H5 7.5, JH3H4 7.0, JHH 1.2, H4),
3
3
4
The regioselectivities were investigated by use of the
GOESY pulse sequence on the Inova-500 spectrometer.
Mass spectra of the complexes were obtained on a ZAB-
SEQ4F spectrometer by the fast-atom bombardment
(FAB) technique using matrices of either 3-nitrobenzyl
alcohol (NBA) or 3-nitrophenyl octyl ether (NOPE).
6.97 (app td, JH4H5ꢀ3
/
JH5H6 7.5, JHH 1.2, H5), 7.05
(dd, JH3H4 7.0, JHH 1.2, H3), 7.33ꢁ7.38 (m, 2H, Hm),
7.90 (m, 2H, Ho).
3
4
3
4
/
7.39ꢁ
/
7.43 (m, 1H, Hp), 7.85ꢁ
/
13C{1H} NMR (125.7 MHz, CDCl3): d 17.62 (d, JPC
12.8, CHD3 MPP), 49.96 (d, JPC 2.5, NMe2), 72.54 (d, JPC
3.1, CH2), 123.06 (C4ꢁ
5.9, C3ꢁ
46.9, Ci), 128.60 (d, JPC 11.2, Cm ꢁ
Cp ꢁH), 133.81 (d, JPC 13.1, Co ꢁ
H), 136.84 (d, JPC 12.3,
C6ꢁ
/
H), 124.20 (C5ꢁ
H), 126.11 (d, JPC 52.4, Caꢁ
H), 126.13 (d, JPC
H), 130.91 (d, JPC 2.6,
/
H), 125.55 (d, JPC
The products of the insertion reactions (11ꢁ22) were
/
/
/
generally unstable, and have been studied primarily in
situ by multinuclear NMR spectroscopy. However, the
palladacycles 14b, 15b and 18b could be crystallized and
micro-analytical data were obtained in-house.
/
/
/
/
H), 148.75 (d, JPC 3.5, C2), 148.84 (d, JPC 2.0, C1ꢁ
/
Pd), 151.89 (d, JPC 10.8, Cb).
31P{1H} NMR (81 MHz, C6D6): d 37.0.
5.2. Starting materials
5.2.1.4. [Pd(C6H4CH2NMe2ꢁkC,N)(NCMe)2]PF6
/
The fluoro-alkyne CF3CÅ
/
CCO2Et [56] and the di-
(4). The cationic complex 4 was prepared by reaction of
1 with AgPF6 in MeCN, following a procedure similar
to that used for the preparation of the corresponding
BF4 salt [34]. After filtration of the solution through
Celite to remove AgCl, the volume was reduced in vacuo
and the product was crystallised by addition of ether.
1H NMR (500 MHz, CD2Cl2): d 2.34 (s, 3H, NCMe),
2.47 (s, 3H, NCMe), 2.85 (s, 6H, NMe2), 4.00 (s, 2H,
nuclear palladacycle [PdCl(C6H4CH2NMe2ꢁ
/
kC,N)]2
(1) [39] were prepared following published procedures.
5.2.1. Preparation of the five-membered palladacycles
and related complexes
5.2.1.1. [PdCl(C6H4CH2NMe2ꢁkC,N)(PEt3)] (2).
/
CH2), 6.94ꢁ
/
6.98 (m, 2H, H3,4), 7.00 (br d, 1H, JHH 7.0,
This compound was formed quantitatively by addition
of 1 equiv. of PEt3 to a solution of 1 in CH2Cl2. The
complex was recrystallised from a CH2Cl2 solution
layered with hexane.
H5), 7.10 (ddd, 1H, JHH 7.0, 6.0, 2.0, H2).
5.2.1.5. [Pd(C6H4CH2NMe2ꢁ
/
Complex 2 also obtained from treatment of the
diphosphine adduct 10 with sulfur in CH2Cl2. After
removal of the solvent in vacuo, the solid was washed
with hexane and the complex was purified by column
chromatography eluted with hexane containing increas-
kC,N)(PEt3)(NCMe)]PF6 (9). This complex was
prepared as described above by reaction of 2 with
AgPF6. This compound was prepared exclusively for
NMR identification purposes and was not purified
further.
1
ing amounts of ether. H NMR (300 MHz, C6D6): d
1H NMR (500 MHz, CD2Cl2): d 1.20 (dt, 9H, J 17.5,
0.99 (dt, 9H, JHH 7.5, JPH 17.1, CH3 of PEt3), 1.73 (dq,
6H, JHH 7.5, JPH 9.9, CH2 of PEt3), 2.44 (d, 6H, JPH 2.7,
NMe2), 3.43 (d, 2H, JPH 2.4, NCH2), 6.88 (dd, 1H, J
7.5, CHP3Et), 1.91ꢁ1.94 (m, 6H, CHP2Et), 2.69 (d, 3H, JPH
2.5, NCMe), 2.85 (s, 6H, NMe2), 3.99 (d, 2H, JPH 2.0,
/
CH2N), 6.94 (m, 3H, H3-5), 7.08ꢁ7.12 (m, 1H, H6).
/
2.7, Harom), 7.02ꢁ
/
7.05 (m, 2H, Harom), 7.16ꢁ
/
7.20 (m,
31P{1H} NMR (81.0 MHz, CD2Cl2): d 33.8 (s, PEt3),
143.9 (sept, JPF 711, PF6).
1H, Harom). 31P{1H} NMR (81 MHz, C6D6): d 33.0.
ꢃ
/

90
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
5.2.1.6. [Pd(C6H4CH2NMe2ꢁ
/
filtered through Celite and treated with 2.2 equiv. of
PEt3. After 30 min, the solvent was removed in vacuo
and the resulting solid was rinsed with pentane. Mon-
itoring of the reaction by 31P NMR spectroscopy
showed the presence of only one product,
kC,N)(DMPP)(NCMe)]PF6 (5). The compound was
prepared as described above, starting from 3.
1H NMR (300 MHz, CD2Cl2): d 2.19 (br s, 6H,
CH3DMPP), 2.35 (s, 3H, NCMe), 2.83 (d, 6H, JPH 2.7,
4
NMe2), 4.02 (d, 2H, 4JPH 2.1, CH2), 6.43 (br d, 2H, 2JPH
[PdCl{C(Ph)Ä
/
C(CO2Et)C6H4CH2NMe2}(PEt3)2] (12).
34.8, Ha-DMPP), 6.75 (ddd, 1H, JPH 7.5, JHH 6.0, JHH
1H NMR (500 MHz, C6D6): d 0.76 (t, 3H, JHH 7.3,
CHE3 t), 0.90 (app. quint, 18H, JHH 7.8, CH3 of PEt3),
1.50 (br m, 12H, CH2 of PEt3), 2.17 (s, 6H, NCH3), 3.54
(s, 2H, NCH2), 3.86 (q, 2H, JHH 7.3, CHE2 t), 6.94 (t, 1H,
JHH 7.4, Hp-Ph), 7.08 (t, 2H, JHH 7.6, Hm-Ph), 7.23 (td,
1H, JHH 7.3, 1.5, H3or4), 7.27 (td, 1H, JHH 7.3, 1.4,
H4or3), 7.58 (d, 2H, JHH 7.3, Ho-Ph), 7.85 (d, 1H, JHH
7.3, H2or5), 8.75 (d, 1H, JHH 7.3,H5or2).
4
3
4
3
1.2, H6), 6.82 (tdd, 1H, JH3H4 7.2, J 1.8, 0.6, H4), 7.04
3
4
(app td, JH H ꢀ3JH H 7.5, JHH 1.2, H5), 7.11 (dd,
/
4
5
5 6
3JH H 7.5, 4JHH 1.5, H3), 7.42ꢁ
7.58 (m, 1H, Hp), 7.71ꢁ7.79 (m, 2H, Ho).
13C{1H} NMR (50.3 MHz, CD2Cl2):
/
4.49 (m, 2H, Hm), 7.51ꢁ
/
3
4
/
d
3.05
(CHN3 CMe), 17.91 (d, JPC 12.9, CHD3 MPP), 50.80 (d, JPC
2.2, NMe2), 71.92 (d, JPC 3.1, CH2), 124.05 (C4ꢁ
124.24 (d, JPC 51.6, CaꢁH), 124.57 (d, JPC 46.3, Ci),
125.90 (C5ꢁH), 126.45 (d, JPC 5.9, C3ꢁ
H), 128.60 (d, JPC
11.6, Cm ꢁH), 133.25 (d, JPC 2.5, Cp ꢁ
H), 134.03 (d, JPC
13.4, Co ꢁH), 136.97 (d, JPC 13.5, C6ꢁ
H), 144.09 (br s,
Pd), 155.16 (d, JPC 10.5, Cb).
/
H),
/
GOESY (500 MHz, C6D6): irradiation at d 1.20ꢁ1.54
/
/
/
gave responses from d 0.90 (quint), and 7.58 (d);
irradiation at d 7.58 gave responses from d 7.08 (t),
6.94 (t), 3.86 (q), 1.49 (m) and 0.90 (quint).
/
/
/
/
C2), 149.56 (d, JPC 2.1, C1ꢁ
/
13C{1H} NMR (125.7 MHz, C6D6): d 8.41 (CHP3Et),
13.76 (CHO3 Et), 15.10 (t, JPC 12.6, CHP2Et), 45.98
(CH3NMe), 60.03 (CHO2 Et), 61.55 (CH2N), 126.03 (CH),
126.16 (CH), 127.30 (CH), 127.62 (CH), 128.47 (CH),
128.81 (CH), 130.71 (CH), 134.74 (t, JPC 4.6, C), 137.60
(C), 139.98 (C), 148.81 (C), 169.09 (CO), 169.44 (C).
31P{1H} NMR (81 MHz, C6D6): d 10.4.
31P{1H} NMR (81 MHz, CD2Cl2): d 35.0 (s, DMPP),
144.0 (sept, JPF 711, PF6).
ꢃ
/
5.2.1.7. [Pd(OSO2CF3)(C6H4CH2NMe2ꢁ
/
kC,N)(DMPP)] (6). A solution of 3 (0.78 g, 1.68
mmol) in CH2Cl2 (10 ml) was treated with AgOSO2CF3
(440 mg, 1.7 mmol) and a white precipitate formed
instantaneously. Monitoring by 31P NMR spectroscopy
showed the reaction to be quantitative. The solution was
filtered through Celite and removal of the solvent in
vacuo gave pure 6 as an off-white solid.
5.2.2.2. [PdCl(C6H4CH2NMe2ꢁ
with PhCÅCCO2Et. The reaction of 2 (ca. 30 mg) with
excess PhCÅCCO2Et in a mixture of toluene (0.5 ml)
/
kC,N)(PEt3)]
(2)
/
/
and C6D6 (0.1 ml) was carried out in an NMR tube
heated to 60 8C overnight. The reaction was monitored
by 31P{1H} NMR spectroscopy, showing the presence of
1H NMR (300 MHz, CD2Cl2): d 2.14 (dd, 6H, J 1.5,
4
1.0, CHD3 MPP), 2.79 (d, 6H, JPH 2.7, NMe2), 3.95 (d,
4
2H, JPH 2.2, CH2), 6.52 (dq, 2H, JPH 33.7, JHH 1.0,
2
[PdCl{C(Ph)Ä
/
C(CO2Et)C6H4CH2NMe2ꢁ
/
4
3
4
Ha-DMPP), 6.71 (ddd, 1H, JPH 7.8, JHH 5.9, JHH 1.0,
kC,N)}(PEt3)] (13b) as the major species, a minor
insertion product that may be the alternative regioi-
H6), 6.78 (br td, 1H, 3JH H 7.0, J 1.7, H4), 7.01 (app td,
3
4
4
3
3JH H ꢀ3
4JHH 2.0, H3), 7.40ꢁ
2H, Ho).
/
JH H 7.1, JHH 1.0, H5), 7.06 (dd, JH H 7.3,
4
5
5
6
3
4
somer
kC,N)}(PEt3)] (13a) (ratio 13b/13aꢀ
decomposition products.
[PdCl{C(CO2Et)Ä
/
C(Ph)C6H4CH2NMe2ꢁ
/
/
4.55 (m, 3H, Hm,p), 7.86ꢁ
7.95 (m,
/
/86:14), and some
13C{1H} NMR (75.4 MHz, CD2Cl2): d 17.86 (d, JPC
12.9, CHD3 MPP), 49.72 (d, JPC 2.3, NMe2), 71.48 (d, JPC
The product 13 was also obtained from the treatment
of 12 with sulfur.
13b: 31P{1H} NMR (81 MHz, C6D6): d 24.9.
13a: 31P{1H} NMR (81 MHz, C6D6): d 27.0.
3.3, CH2), 120.33 (q, JFC 318.8, CF3), 124.17 (C4ꢁ
/
H),
H),
124.99 (d, JPC 48.7, Ci), 125.32 (d, JPC 50.4, Caꢁ
125.57 (C5ꢁH), 126.53 (d, JPC 5.8, C3ꢁ
11.5, Cm ꢁH), 131.99 (d, JPC 2.6, Cp ꢁ
13.5, Co ꢁH), 137.06 (d, JPC 13.2, C6ꢁ
5.9, C2), 149.31 (d, JPC 2.1, C1ꢁ
/
/
/
H), 129.22 (d, JPC
H), 134.49 (d, JPC
H), 140.08 (d, JPC
/
/
/
/
5.2.2.3. Reaction of [PdCl(C6H4CH2NMe2ꢁ
(DMPP)] (3) with PhCÅCCO2Et. A C6D6 solution
of 3 (0.95 mg, 0.2 mmol) in an NMR tube was treated
/kC,N)-
/
Pd), 154.20 (d, JPC 10.6,
/
Cb).
31P{1H} NMR (81 MHz, CD2Cl2): d 36.6 (s, DMPP).
with PhCÅCCO2Et (0.48 ml, 0.3 mol) and heated 24 h at
/
50 8C. Monitoring by 31P NMR spectroscopy showed
the formation of only one insertion product (traces of a
second isomer observed in CD2Cl2, see text). The
solution was evaporated to dryness and the residue
dissolved in chlorobenzene. Diffusion of pentane yielded
5.2.2. Reactions of the palladacycles with alkynes
5.2.2.1. Reaction of [PdCl(C6H4CH2NMe2ꢁ
/
kC,N)]2
(1) with PhCÅCCO2Et. A solution of complex 1 (0.1
/
g, 0.19 mmol) in CH2Cl2 (10ml) was treated with PhCÅ
/
single crystals of [PdCl{C(Ph)Ä
NMe2ꢁkC,N}(DMPP)] (14b) suitable for X-ray analy-
sis.
/C(CO2Et)C6H4CH2-
CCO2Et (61ml, 0.38 mmol) and the mixture was stirred
for 2 h at room temperature (r.t.). The solution was
/

A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ
/97
91
1H NMR (500 MHz, CDCl3): d 0.92 (t, JHH 7.1,
CHO3 Et), 1.89 (d, 3H, J 1.5, CHD3 MPP), 2.10 (s, 3H,
C6H4CH2NMe2ꢁ
titatively.
1H NMR (500 MHz, CD2Cl2): d 0.83 (dt, 9H, J 17.5,
7.5, CHP3Et), 0.99 (t, 3H, JHH 7.0, CHE3 t), 1.26ꢁ
1.34 (m,
3H, CH2PEt), 1.47ꢁ1.56 (m, 3H, CHP2Et), 2.34 ( br s, 3H,
NCMe), 2.69 (d, 6H, JPH 2.5, NMe2), 3.14 (dd, 1H, JHH
12.5, JPH 4.0, CH2N), 3.85ꢁ
3.91 (m, 1H, CHE2 t), 3.95ꢁ
4.01 (m, 1H, CH2Et), 4.11 (d, 1H, JHH 12.5, CH2N),
7.35ꢁ
7.55 (m, 5H, Harom), 7.59ꢁ7.63 (m, 2H, Harom),
7.68 (d, 2H, J 7.5, HPh), 7.70 (d, 1H, J 7.0, H6).
/
kC,N}(PEt3)(NCMe)]PF6 (16b) quan-
4
CH3DMPP), 2.58 (d, 3H, JPH 2.0, NMe), 2.84 (d, 3H,
4JPH 2.0, NMe), 3.14 (dd, 1H, 2JHH 11.7, 4JPH 3.9, CH2),
3.87 (dq, 1H, 2JHH 10.8, 3JHH 7.1, CHO2 Et), 3.97 (dq, 1H,
/
/
2JHH 10.8, JHH 7.1, CH2OEt), 4.05 (d, 1H, JHH 11.7,
3
2
CH2), 6.32 (br d, 1H, JPH 32.2, Ha-DMPP), 6.55 (br d,
/
/
2
1H, 2JPH 32.3, Ha-DMPP), 7.12 (td, 2H, J 7.3, 2.4, Harom),
7.15ꢁ
/
7.18 (m, 3H, Harom), 7.19ꢁ
/
7.23 (m, 1H, Harom),
/
/
7.21 (d, 2H, J 5.4, HPh), 7.27ꢁ7.29 (m, 2H, Harom), 7.30
/
(ddd, 2H J 7.3, 2.0, 1.5, Harom), 7.36 (td, 1H, J 7.3, 1.5,
Harom), 7.40 (dd, 1H, J 7.3, 1.4, Harom).
GOESY (500 MHz, CD2Cl2): irradiation at d 1.48ꢁ
/
1.56 gave responses from d 0.83 (m), and 7.68 (d);
GOESY (500 MHz, C6D6): irradiation at d 2.10 gave
responses from d 6.55 (d), and 7.16 (m), 7.29 (m) and
7.21 (d, strong).
irradiation at d 0.75ꢁ0.86 gave responses from d 1.30
(m), 1.51 (m) and 7.68 (d).
13C{1H} NMR (75.4 MHz, CD2Cl2): d 2.70 (CH3,
NCMe), 7.69 (d, JPC 2.2, CHP3Et3), 13.76 (CH3OEt), 16.17
(d, JPC 28.6, CH2PEt3), 49.99 (br s, NMe2), 61.17
(CHO2 Et), 65.73 (d, JPC 2.2, CH2N), 122.62 (br s,
/
13C{1H} NMR (50.3 MHz, CDCl3): d 13.70 (CHO3 Et),
17.52 (d, JPC 12.8, CHD3 MPP), 17.68 (d, JPC 13.0,
CHD3 MPP), 50.33 (d, JPC 2.0, NMe), 51.43 (d, JPC 2.2,
NMe), 60.42 (CH2OEt), 66.09 (d, JPC 2.4, CH2), 124.93 (d,
NCMe), 123.95 (CH), 126.50ꢁ
/
131.62 (m, CH), 132.39
JPC 52.0, Caꢁ
126.98 (CH), 127.09 (d, JPC 51.8, Caꢁ
(2CHPh) 127.93 (CH), 128.15 (2CHPh), 128.28 (d, JPC
3.1, Cm ꢁH), 128.95 (CH), 130.18 (d, JPC 2.5, Cp ꢁ
H),
131.48 (CH), 133.28 (d, JPC 11.9, Co ꢁ
H), 135.19 (C),
/
H), 126.41 (d, JPC 82.6, Ci), 126.68 (CH),
(d, J 3.3, C), 141.69 (C), 142.46 (C), 143.45 (br s, Cꢁ
/Pd),
/H), 127.62
149.37 (C), 167.52 (CO).
31P{1H} NMR (81.0 MHz, CD2Cl2): d 25.8, ꢃ
(sept, JPF 711, PF6).
/143.9
/
/
/
142.35 (d, JPC 2.5, C), 144.33 (d, JPC 6.0, C), 150.65 (d,
JPC 10.6, Cb), 151.96 (d, JPC 11.2, Cb), 167.62 (d, JPC
2.5, C), 169.71 (d, JPC 1.9, CO).
5.2.2.5. Reaction of [Pd(C6H4CH2NMe2ꢁ
/
kC,N)-
(DMPP)(NCMe)]PF6 (5) with PhCÅCCO2Et. An
/
NMR scale reaction was carried out between 5 (30
mg) and the alkyne (25 ml), the reaction being complete
after heating the mixture for 16 h at 40 8C. Monitoring
by 31P NMR spectroscopy showed a 87:13 mixture of
31P{1H} NMR (81 MHz, C6D6): d 27.5.
FAB MS(C32H35ClNO2PPd, NBA): 639 [Mꢂ], 602
[Mꢂꢃ
Cl].
Anal. Calc. for C32H35ClNO2PPd: C, 60.2; H, 5.5; N,
/
[Pd{C(Ph)Ä
kC,N}(DMPP)(NCMe)]PF6 (17b) and [Pd{C(CO2Et)Ä
C(Ph)C6H4CH2NMe2ꢁkC,N}(DMPP)(NCMe)]PF6
/
C(CO2Et)C6H4CH2NMe2ꢁ
/
2.2. Found: C, 59.6; H, 5.6; N, 2.2%.
/
/
(17a).
5.2.2.4. Reaction of [Pd(C6H4CH2NMe2ꢁ/kC,N)(NC-
17b: 1H NMR (500 MHz, CD2Cl2): d 0.98 (t, JHH 7.0,
Me)2]PF6 (4) with PhCÅCCO2Et. A solution of PhCÅ
/
/
CHO3 Et), 1.97 (br s, 6H, CHD3 MPP), 2.06 (s, 3H, NCMe),
2.77 (br s, 3H, NMe), 2.81 (br s, 3H, NMe), 3.21 (br d,
CCO2Et (0.35 ml, 0.2 mmol) in CH2Cl2 was added to a
solution of 4 (0.1 g, 0.2 mmol) in CH2Cl2 and the
misture was stirred for 90 min at r.t. The solution was
filtered through Celite and the solvent was evaporated.
The yellow residue was washed with hexane and dried in
1H, JHH 12.0, CH2), 3.89ꢁ
/
4.05 (m, 2H, CHO2 Et), 4.10
2
(d, 1H, JHH 12.0, CH2), 6.06 (br d, 1H, JPH 35.5, Ha-
2
2
DMPP), 6.31 (br d, 1H, 2JPH 35.5, Ha-DMPP), 6.81 (m, 1H,
Harom), 7.08ꢁ7.13 (m, 1H, Harom), 7.28 (t, 2H, J 7.5,
/
vacuo to give pure [Pd{C(Ph)Ä
/
C(CO2Et)C6H4CH2N-
Harom), 7.35 (br d, 1H, J 2.5, Harom), 7.39ꢁ
7.54 (m, 4H,
/
Me2ꢁkC,N}(NCMe)2]PF6 (15b) in 93% yield. Yellow
/
Harom), 7.43 (t, 2H, J 8.0, Harom), 7.49 (s, 1H, Harom),
7.61 (d, 2H, J 4.5, Harom).
needles of 15b suitable for single crystal X-ray analysis
were obtained by slow evaporation of a CH2Cl2 solu-
tion.
1H NMR (500 MHz, CD2Cl2): d 0.85 (t, 3H, JHH 7.0,
CHE3 t), 2.26 (br s, 6H, 2xNCMe), 2.84 (s, 6H, NCH3),
13C{1H} NMR (75.4 MHz, CD2Cl2): d 2.56 (CH3,
NCMe), 13.84 (CHO3 Et), 17.77 (d, JPC 12.0, CHD3 MPP),
52.48 (br s, NMe2), 61.22 (CHO2 Et), 65.93 (d, JPC 2.2,
CH2), 121.59 (d, JPC 48.6, Caꢁ
/
H), 122.09 (d, JPC 3.8,
NCMe), 125.53 (d, JPC 48.4, Ci), 127.91 (CH), 128.33
(2CHPh), 128.35 (CH), 128.87 (d, JPC 2.2, Cm ꢁ
H),
3.16 (d, 1H, JHH 11.5, NCH2), 3.84ꢁ
/
3.91 (m, 2H, CHE2 t),
7.42 (m, 4H,
4.01 (d, 1H, JHH 11.5, NCH2), 7.40ꢁ
/
/
Harom), 7.48 (td, 2H, J 7.5, 1.0, Harom), 7.59 (t, 2H, J
8.0, Harom), 7.73 (d, 1H, JHH 7.0, H2).
129.08 (CH), 129.20 (CH), 129.25 (CH), 129.34 (CH),
131.70 (CH), 132.38 (d, J 4.9, C), 133.96 (d, JPC 12.1,
Anal. Calc. for C24H30F6N3O2PPd: C, 41.20; H, 4.43;
N, 5.77. Found: C, 40.63; H, 3.91; N, 5.53%.
Addition of 1 equiv. of PEt3 to an NMR solution of
Co ꢁ
/
H), 135.15 (C), 141.82 (C), 144.33 (d, JPC 6.0, Cꢁ
/
Pd), 154.06 (d, JPC 3.6, Cb), 160.27 (d, JPC 4.1, CO).
31P{1H} NMR (81 MHz, C6D6): d 25.4 (s, DMPP),
144.1 (sept, JPF 711, PF6).
15b in CD2Cl2 produced [Pd{C(Ph)Ä
/C(CO2Et)-
ꢃ
/

92
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
17a: 31P{1H} NMR (81.0 MHz, C6D6): d 27.4 (s,
DMPP), ꢃ144.1 (sept, JPF 711, PF6).
1.79 (m, 6H, CHP2Et), 2.38 (d, 3H, JPH 1.9, NMe), 2.44
(dd, 1H, JHH 11.6, JPH 5.0, CH2N), 2.58 (d, 3H, JPH 2.5,
/
2
3
NMe), 3.91 (dq, 1H, JHH 10.7, JHH 7.1, CHO2 Et), 3.94
(d, 1H, 2JHH 11.6, CH2N), 4.10 (dq, 1H, 2JHH 10.7, 3JHH
7.1, CHO2 Et), 6.84 (dd, 1H, J 7.5, 1.1, H3), 7.01 (td, 1H, J
7.5, 1.4, H4or5), 7.36 (td, 1H, J 7.5, 1.4, H5or4), 7.64 (dd,
1H, J 7.5, 1.4, H6).
5.2.2.6. Reaction of [Pd(C6H4CH2NMe2ꢁ
/kC,N)-
(solvent)]PF6 (7) with PhCÅCCO2Et in CH2Cl2. A
/
solution of 1 (162 mg, 0.29 mmol) in CH2Cl2 (5 ml) was
treated with AgPF6 (156 mg, 0.62 mmol) for 20 min at
r.t., then the mixture was filtered through Celite and the
resulting orange solution was cooled to 0 8C. The alkyne
(96 ml, 0.58 mmol) was added dropwise and the mixture
was stirred for 1.5 h at r.t., before addition of 1 ml of
MeCN. The resulting solution was filtered again
through Celite and removal of the solvent gave 0.327
mg of a yellow solid containing 15a and 15b. Part of this
solid (0.27 mg) (ca. 0.4 mmol) was treated with PEt3 (59
ml, 0.4 mmol) and 31P NMR spectroscopy showed the
13C{1H} NMR (125.7 MHz, C6D6): d 8.16 (d, JPC 2.7,
CHP3Et), 13.92 (CH3OEt), 16.81 (d, JPC 31.2, CH2PEt), 49.77
(br s, NMe), 49.90 (d, JPC 2.3, NMe), 61.19 (CHO2 Et),
1
3
65.47 (d, JPC 2.5, NMe2), 125.78 (qd, JFC 274.6, JPC
5.7, CF3), 127.35 (CH), 127.56 (CH), 128.48 (CH),
5
132.42 (C6ꢁ
/
H), 134.94 (d, JPC 0.9, C2), 139.44 (qd,
3JFC 8.7, JPC 2.5, C7), 141.71 (app quint, JFCꢀ4
/
JPC
Pd), 167.76
3
4
1.3, C1), 148.27 (qd, 2JFC 32.5, 2JPC 2.1, C8ꢁ
(q, JFC 1.9, CO).
/
4
mixture to contain unreacted 9 (22%), [Pd{C(Ph)Ä
C(CO2Et)C6H4CH2NMe2 ꢁkC,N}(PEt3)(NCMe)]PF6
(16b) (31%) and [Pd{C(CO2Et)ÄC(Ph)C6H4CH2NMe2ꢁ
kC,N}(PEt3)(NCMe)]PF6 (16a) (47%) (ratio 16b:16aꢀ
40:60, insertion yieldꢀ78%).
16a: H NMR (300 MHz, CD2Cl2): d 1.01 (dt, 9H, J
/
19F NMR (188.2 MHz, C6D6): d ꢃ
/
50.4 (d, JPF 5.7).
31P{1H} NMR (81 MHz, C6D6): d 29.7 (q, JPF 5.7,
/
/
/
PEt3).
/
Anal. Calc. for C21H32ClF3NO2PPd: C, 45.2; H, 5.8;
/
N, 2.5. Found: C, 44.9; H, 5.5; N, 2.4%.
1
18a: 19F NMR (188.2 MHz, C6D6): d ꢃ
/
60.0 (app. s).
31P{1H} NMR (81 MHz, C6D6): d 32.1 (q, JPF 2.0,
PEt3).
18.3, 7.6, CH3PEt), 1.02 (t, 3H, JHH 6.9, CHE3 t), 1.75ꢁ
2.08
/
(m, 6H, CHP2Et), 2.34 ( br s, 3H, NCMe), 2.73 (d, 3H,
JPH 2.5, NMe), 2.80 (d, 3H, JPH 1.8, NMe), 3.17 (dd,
1H, JHH 11.7, JPH 4.5, CH2N), 3.95ꢁ
CHE2 t), 4.13 (d, 1H, JHH 11.7, CH2N), 7.22ꢁ
3H, Harom), 7.32ꢁ7.48 (m, 4H, Harom), 7.68 (d, 2H, J
7.5, HPh).
13C{1H} NMR (75.4 MHz, CD2Cl2): d 2.70 (CH3,
NCMe), 8.15 (d, JPC 2.8, CHP3Et3), 13.98 (CH3OEt), 16.40
(d, JPC 29.6, CH2PEt3), 50.64 (br s, NMe2), 61.02
(CHO2 Et), 65.63 (d, JPC 2.7, CH2N), 122.62 (br s,
/
4.08 (m, 2H,
5.2.2.8. Reaction of [PdCl(C6H4CH2NMe2ꢁ
(DMPP)] (3) with F3CCÅCCO2Et. A mixture of 3
(0.12 mg, 0.28 mmol) and F3CCÅCCO2Et (79 ml, 0.56
mmol) in C6D6 (1 ml) was heated for 24 h at 50 8C to
yield a mixture of [PdCl{C(CF3)ÄC(CO2Et)C6H4CH2-
NMe2ꢁkC,N}(DMPP)] (19b) and [PdCl{C(CO2Et)Ä
C(CF3)C6H4CH2NMe2ꢁkC,N}(PEt3)] (19a) in a 70:30
ratio (yield estimated from 31P NMR spectrum ꢀ
90%).
The two isomer could not be separated.
19b: 1H NMR (500 MHz, CD2Cl2): d 1.31 (t, 3H, JHH
7.0, CHO3 Et), 2.01 (s, 3H, CHD3 MPP), 2.21 (s, 3H,
CH3DMPP), 2.82 (d, 3H, JPH 2.0, NMe), 2.84 (d, 3H,
JPH 2.0, NMe), 3.16 (dd, 1H, JHH 11.5, JPH 5.0, CH2N),
4.04 (d, 1H, 2JHH 11.5, CH2N), 4.17 (dq, 1H, 2JHH 10.7,
/
kC,N)-
/7.27 (m,
/
/
/
/
/
/
/
/
NCMe), 126.50ꢁ131.62 (m, CH), 134.23 (C), 134.78
/
(C), 141.12 (C), 142.22 (C), 146.34 (C), 171.10 (d, JPC
6.6, CO).
31P{1H} NMR (81.0 MHz, CD2Cl2): d 29.4 (s, PEt3),
ꢃ143.9 (sept, JPF 711, PF6).
/
2
3
5.2.2.7. Reaction of [PdCl(C6H4CH2NMe2ꢁ
(1) with F3CCÅCCO2Et. A mixture of 1 (85 mg, 0.15
mmol) and F3CCÅCCO2Et (50 ml, 0.35 mmol) in
/kC,N)]2
3JHH 7.1, CHO2 Et), 4.27 (dq, 1H, JHH 10.7, JHH 7.1,
/
CHO2 Et), 6.31 (br d, 1H, 2JPH 32.0, Ha-DMPP), 6.58 (br d,
2
/
1H, JPH 33.0, Ha-DMPP), 7.21 (dd, 1H, J 6.0, 2.0,
CH2Cl2 (5 ml) was stirred for 16 h at r.t. The solution
was then treated with PEt3 (50 ml, 0.34 mmol) and sulfur
(ca. 20 mg) was added subsequently to remove excess
phosphine. Monitoring by 31P NMR spectroscopy
Harom), 7.15ꢁ
/
7.18 (m, 3H, Harom), 7.19ꢁ
/
7.23 (m, 1H,
Harom), 7.21 (d, 2H, J 5.4, HPh), 7.30 (td, 2H J 7.5, 2.5,
Harom), 7.37ꢁ7.48 (m, 6H, Harom), 7.63 (dd, 2H, J 12.0,
7.3, Ho).
/
showed formation of [PdCl{C(CF3)Ä
CH2NMe2ꢁkC,N}(PEt3)] (18b) and [PdCl{C(CO2Et)Ä
C(CF3)C6H4CH2NMe2ꢁkC,N}(PEt3)] (18a) in a 70:30
/
C(CO2Et)C6H4-
1H NMR (500 MHz, C6D6): d 0.93 (t, 3H, JHH 7.0,
CHO3 Et), 1.34 (s, 3H, CH3DMPP), 1.74 (s, 3H, CH3DMPP),
2.40 (d, 3H, JPH 1.5, NMe), 2.49 (dd, 1H, JHH 11.5, JPH
5.0, CH2N), 2.59 (d, 3H, JPH 2.0, NMe), 3.87 (d, 1H,
/
/
/
ratio. The solvent was removed in vacuo and the major
2
3
compound was isolated and purified by preparative
2JHH 11.5, CH2N), 3.90 (dq, 1H, JHH 10.7, JHH 7.1,
TLC (SiO2, hexaneꢁether 2:1). Single crystals of 18b
/
CHO2 Et), 4.06 (dq, 1H, 2JHH 10.7, 3JHH 7.1, CHO2 Et), 6.43
2
2
were obtained from an ether solution layered with
hexane.
(br d, 1H, JPH 32.0, Ha-DMPP), 6.70 (br d, 1H, JPH
33.0, Ha-DMPP), 6.84 (d, 1H, J 7.5, H3), 6.95ꢁ
7.01 (m,
/
1
18b: H NMR (300 MHz, C6D6): d 0.75 (dt, 9H, J
4H, Hmꢂ4,5), 7.08 (td, 1H, J 7.5, 1.0, Hp), 7.35 (d, 1H, J
7.5, H6), 7.81 (ddd, 2H, J 12.0, 7.5, 1.0, Ho).
17.0, 7.7, CH3PEt), 0.96 (t, 3H, JHH 7.1, CHO3 Et), 1.53ꢁ
/

A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ
/97
93
GOESY (500 MHz, C6D6): irradiation at d 0.93 gave
responses from d 3.89 (dq), 4.06 (dq) and 7.35 (d).
13C{1H} NMR (125.7 MHz, CD2Cl2): d 14.18
(CHO3 Et), 17.50 (d, JPC 13.7, CH3DMPP), 17.82 (d, JPC
13.6, CHD3 MPP), 50.34 (d, JPC 2.7, NMe), 50.85 (br s,
NMe), 61.66 (CH2OEt), 65.80 (d, JPC 2.7, CH2), 124.89
5.2.2.9. Reaction of [Pd(C6H4CH2NMe2ꢁ
(solvent)]PF6 (7) with F3CCÅ
mixture of [PdCl(C6H4CH2NMe2ꢁ
0.44 mmol) and AgPF6 (246 mg, 0.97 mmol) in CH3NO2
(5 ml) was stirred for 1 h at r.t. After filtration of the
silver salts via a Celite plug, the orange solution
/
kC,N)-
/
CCO2Et in CH3NO2. A
/
kC,N)]2 (1) (244 mg,
containing 7 was cooled to 0 8C and CF3CÅ
/
CCO2Et
(qd, JFC 274.0, JPC 6.4, CF3), 125.58ꢁ
126.32 (d, JPC 53.1, Ci), 127.27 (CH), 128.04ꢁ
CH), 131.17 (d, JPC 2.6, Cp ꢁ
H), 132.38 (CH), 133.68 (d,
JPC 11.8, Co ꢁH), 134.76 (q, JFC 1.1, C2), 139.84 (qd, JFC
8.5, JPC 3.4, C7), 140.65 (dq, JPC 1.8, JFC 1.1, C1), 143.12
(qd, JFC 33, JPC 3.7, C8ꢁPd), 151.24 (d, JPC 12.0, Cb),
152.93 (d, JPC 11.6, Cb), 167.43 (app. quint, J 1.3, CO).
19F NMR (188.2 MHz, C6D6): d ꢃ
52.8 (d, JPF 7.0).
31P{1H} NMR (81 MHz, C6D6): d 28.1 (q, JPF 7.0,
DMPP).
FAB MS(C27H30ClF3NO2PPd, NBA): 631 [Mꢂ], 594
Cl].
/
127.00 (m, CH),
(0.13 ml, 0.88 mmol) was added dropwise and the
instantaneous reaction yielded a yellow solution. Mon-
itoring by 19F NMR showed the reaction to be very
clean but several isomers of each insertion product were
formed. After addition of CH3CN (0.4 ml), the spectrum
/
128.96 (m,
/
/
/
simplified to two CF3 singlets assigned to [Pd{C(CF3)Ä
C(CO2Et)C6H4CH2NMe2ꢁkC,N}(NCMe)2]PF6 (21b)
and C(CF3)C6H4CH2NMe2ꢁkC,N}-
/
/
/
[Pd{C(CO2Et)Ä
/
/
(NCMe)2]PF6 (21a) in a 55:45 ratio. Attempted crystal-
lisation led to decomposition.
1
21b: H NMR (300 MHz, CD3NO2): d 1.25 (t, 3H,
[Mꢂꢃ
/
JHH 6.9, CHO3 Et), 2.29 (s, 3H, NCCH3), 2.37 (s, 3H,
NCCH3), 2.67 (s, 3H, NMe), 3.00 (s, 3H, NMe), 3.30 (d,
19a: 1H NMR (500 MHz, CD2Cl2): d 1.07 (t, 3H, JHH
7.0, CHO3 Et), 1.99 (s, 3H, CHD3 MPP), 2.20 (s, 3H,
CH3DMPP), 2.79 (d, 3H, JPH 2.0, NMe), 2.93 (d, 3H,
JPH 2.0, NMe), 3.12 (dd, 1H, JHH 12.0, JPH 5.0, CH2N),
2
1H, JHH 12.0, CH2N), 3.85 (d, 1H, JHH 12.0, CH2N),
4.17ꢁ
/
4.30 (m, 2H, CHO2 Et), 7.41 (dd, 1H, J 7.4, 1.6, H3),
7.54ꢁ
/
7.66 (m, 4H, Harom).
2
3
3.73 (dq, 1H, JHH 10.7, JHH 7.1, CHO2 Et), 4.09 (d, 1H,
13C{1H} NMR (50.3 MHz, CD3NO2): d 2.76
(CH3CN), 3.09 (CH3CN), 14.44 (CHO3 Et), 54.20
(NMe2), 63.43 (CH2OEt), 68.10 (CH2N), 122.96 (br s,
CH3CN), 124.08 (q, JFC 273.9, CF3), 124.16 (s,
2JHH 12.0, CH2N), 4.12 (dq, 1H, JHH 10.7, JHH 7.1,
2
3
CHO2 Et), 6.37 (br d, 1H, 2JPH 32.0, Ha-DMPP), 6.78 (br d,
1H, 2JPH 31.0, Ha-DMPP), 7.29 (m, 1H, Harom), 7.37ꢁ
7.48
/
(m, 6H, Harom), 7.78 (dd, 2H, J 12.0, 7.3, Ho).
CH3CN), 130.07 (2ꢄ
135.29 (s, C2), 139.25 (s, C1), 142.02 (q, JFC 7.4, C7),
166.25 (s, CO); C8ꢁ
Pd not located.
19F NMR (188.2 MHz, CD2Cl2): d ꢃ
JPF 711, PF6).
/CH), 131.11 (CH), 133.74 (CH),
1H NMR (500 MHz, C6D6): d 0.79 (t, 3H, JHH 7.0,
CHO3 Et), 1.22 (s, 3H, CH3DMPP), 1.68 (s, 3H, CH3DMPP),
2.46 (dd, 1H, JHH 11.5, JPH 5.0, CH2N), 2.59 (d, 3H,
JPH 1.5, NMe),2.67 (d, 3H, JPH 2.0, NMe), 3.57 (dq, 1H,
/
/
52.8, ꢃ72.9 (d,
/
3
2
2JHH 10.7, JHH 7.1, CH2OEt), 3.92 (d, 1H, JHH 11.5,
21a: 1H NMR (200 MHz, CD2Cl2): d 1.37 (t, 3H, JHH
7.2, CHO3 Et), 2.24 (s, 3H, NCCH3), 2.30 (s, 3H, NCCH3),
2.59 (s, 3H, NMe), 2.99 (s, 3H, NMe), 3.05 (d, 1H, JHH
CH2N), 4.00 (dq, 1H, 2JHH 10.7, 3JHH 7.1, CH2OEt), 6.50
(br d, 1H, JPH 32.0, Ha-DMPP), 6.81 (d, 1H, J 7.5, H3),
2
6.93 (br d, 1H, JPH 33.0, Ha-DMPP), 6.95ꢁ
/
7.01 (m, 4H,
mꢂ4,5), 7.10 (td, 1H, J 7.5, 1.0, Hp), 7.39 (br d, 1H, J
7.5, H6), 7.99 (m, 2H, J 12.0, 7.5, 1.0, Ho).
2
2
12.0, CH2N), 3.83 (d, 1H, JHH 12.0, CH2N), 4.32 (q,
2H,3JHH 7.0, CH2OEt), 7.41 (dd, 1H, J 7.4, 1.6, H3), 7.51
(td, 1H, J 7.2, 1.6, H4 or 5), 7.59 (td, 1H, J 7.2, 1.6, H5 or
4), 7.65 (br dq, 1H, JHH 7.4, JFH 1.1, H6).
H
GOESY (500 MHz, C6D6): irradiation at d 0.79 gave
responses from d 3.57 (dq), 4.00 (dq) and 6.93 (d), 6.98
(m) and 7.99 (m); irradiation at d 7.99 gave responses
from d 6.99 (m), 6.93 (d), 6.50 (d), 3.60 (m) and 0.79 (t).
13C{1H} NMR (125.7 MHz, CD2Cl2): d 13.95
(CHO3 Et), 17.61 (d, JPC 13.9, CH3DMPP), 17.74 (d, JPC
13.9, CHD3 MPP), 49.82 (d, JPC 2.0, NMe), 50.71 (d, JPC
2.7, NMe), 60.96 (CHO2 Et), 65.41 (d, JPC 2.7, CH2),
121.44 (q, JFC 277.2, CF3), 124.92 (qd, JFC 29.8, JPC 2.7,
13C{1H} NMR (50.3 MHz, CD2Cl2):
d
2.87
(CH3CN), 3.44 (CH3CN), 14.37 (CHO3 Et), 53.46
(NMe2), 61.96 (CH2OEt), 67.42 (CH2N), 119.51 (q, JFC
277.2, CF3), 121.21 (br s, CH3CN), 121.26 (s, CH3CN),
126.22 (q, JFC 30.3, C7), 128.97 (CH), 129.17 (q, JFC 1.3,
C6ꢁ
(s, C1), 145.32 (br, C8ꢁ
19F NMR (188.2 MHz, CH3NO2ꢂ
72.9 (d, JPF 711, PF6).
/
H), 130.00 (CH), 132.27 (CH), 133.51 (s, C2), 135.80
Pd), 168.03 (s, CO).
CD2Cl2): d ꢃ
/
/
/60.6,
C8ꢁ
Ci), 128.04ꢁ
2.8, Cp ꢁ
H), 131.75 (CH), 132.26 (CH), 133.86 (d, JPC
11.9, Co ꢁ
/
Pd), 125.58ꢁ
/
127.00 (m, CH), 126.04 (d, JPC 52.7,
ꢃ
/
/128.96 (m, CH), 129.31 (CH),131.33 (d, JPC
/
5.2.2.10. Reaction of [Pd(C6H4CH2NMe2ꢁ
(solvent)]PF6 (7) with F3CCÅCCO2Et in CH2Cl2. As
described above, [PdCl(C6H4CH2NMe2ꢁkC,N)]2 (1)
/kC,N)-
/
H), 135.96 (s, C2), 138.33 (app quint, J 0.9,
/
C1), 151.22 (d, JPC 12.6, Cb), 152.58 (d, JPC 12.0, Cb),
157.84 (dq, JPC 4.8, JFC 2.9, C7), 170.91 (d, JPC 6.0, CO).
/
(191 mg, 0.35 mmol) was treated with AgPF6 (192 mg,
0.76 mmol) in CH2Cl2. After filtration, the orange
solution containing 7 was cooled to 0 8C and CF3CÅ
CCO2Et (0.1 ml, 0.7 mmol) was added dropwise and
19F NMR (188.2 MHz, C6D6): d ꢃ
/
60.7 (app. s).
31P{1H} NMR (81 MHz, C6D6): d 29.9 (q, JPF 1.9,
DMPP).
/

94
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
/
instantaneous reaction yielded a yellow solution. After
addition of CH3CN (0.4 ml), the solvent was removed in
vacuo to yield a clean pale yellow solid containing
with ether to yield a yellow powder that was shown by
NMR spectroscopy to contain a 16:84 mixture of 22b
and 22a.
mainly the a-product 21a (ratio between 21b and 21aꢀ
/
FAB MS (C29H33F3N2PPdO2ꢂ, NBA): m/z 594
6:94).
[MꢂꢃNCMe]ꢂ.
/
5.2.2.11. Reaction of [Pd(C6H4CH2NMe2ꢁ
/
kC,N)-
5.2.2.14. Reaction of [Pd(OSO2CF3)(C6H4CH2NMe2ꢁ
kC,N)(DMPP)] (6) with F3CCÅCCO2Et. The reac-
CCO2Et in
CD2Cl2 required heating to 40 8C for 2 h, yielding a
59:41 mixture of the two regioisomers [Pd(OSO2CF3)-
/
(DMPP)(NCMe)]PF6 (5) with F3CCÅCCO2Et in
/
/
CD2Cl2. Complex 5 (40 mg, 0.7 mmol) the alkyne (25
ml, 0.15 mmol) and CD2Cl2 (0.5 ml) were mixed in an
NMR tube and the reaction was monitored by 31P
NMR spectroscopy. The reaction was complete after 3 h
tion on an NMR scale between 6 and F3CCÅ
/
{C(CF3)Ä
(20b) and [Pd(OSO2CF3){C(CO2Et)Ä
NMe2ꢁkC,N}(DMPP)] (20a). The reaction was not
/
C(CO2Et)C6H4CH2NMe2 ꢁ
/
kC,N}(DMPP)]
at 40 8C, giving a 62:38 mixture of [Pd{C(CF3)Ä
C(CO2Et)C6H4CH2NMe2ꢁkC,N}(DMPP)(NCMe)]PF6
(22b) and [Pd{C(CO2Et)ÄC(CF3)C6H4CH2NMe2ꢁ
/
/
C(CF3)C6H4CH2-
/
/
/
/
very clean (yield ca 70%) and the solution decomposed
kC,N}(DMPP)(NCMe)]PF6 (22a).
readily.
22b: 13C{1H} NMR (75.4 MHz, CD2Cl2): d 2.67 (br s,
NCCH3), 14.15 (CHO3 Et), 17.75 (d, JPC 14.8, CHD3 MPP),
17.88 (d, JPC 14.4, CHD3 MPP), 51.43 (br s, NMe2), 61.12
20b: 19F NMR (188.2 MHz, CD2Cl2): d ꢃ
52.9 (d, JPF
/
5.9), ꢃ
31P{1H} NMR (81 MHz, CD3CN): d 24.8 (q, JPF 5.9,
DMPP).
20a: 19F NMR (188.2 MHz, CD2Cl2): d ꢃ
78.4 (s, SO3CF3).
31P{1H} NMR (81 MHz, CD3CN): d 27.1 (s, DMPP).
/78.4 (s, SO3CF3).
(CHO2 Et), 65.98 (s, CH2), 121.57 (d, JPC 53.4, Caꢁ
/
H),
H), 124.28 (d, JPC 51.4, Ci),
CF3),
122.92 (d, JPC 57.0, Caꢁ
/
/60.7 (s),
127.40 (CH), 128.90ꢁ
/
137.10 (m, Cꢂ
/
CHꢂ
/
NCꢂ
/
ꢃ
/
139.31 (C), 139.84 (m, C), 155.09 (d, JPC 11.3, Cb),
155.46 (d, JPC 11.1, Cb), 166.03 (CO).
19F NMR (188.2 MHz, CD2Cl2): d ꢃ
/
52.4 (d, JPF
5.3. X-ray crystallography of palladacycles 3, 14b, 15b×
/
6.4), ꢃ
/
72.7 (d, JPF 711, PF6).
31P{1H} NMR (81 MHz, CD2Cl2): d 25.8 (q, JPF 6.4,
0.5CH2Cl2 and 18b
DMPP), ꢃ
/
144.0 (sept, JPF 711, PF6).
Crystal data, details of data collection, data proces-
sing, structure analysis and structure refinement are in
Table 4.
The crystals were mounted onto a glass fiber and the
data were recorded at 200 K on a Nonius kCCD
diffractometer equipped with a 95 mm camera and
22a: 13C{1H} NMR (75.4 MHz, CD2Cl2): d 2.67 (br s,
NCCH3), 14.10 (CHO3 Et), 18.47 (d, JPC 17.6, CHD3 MPP),
44.83 (s, NMe2), 62.49 (d, JPC 2.5, CHO2 Et), 65.74 (d, JPC
2.5, CH2), 128.90ꢁ
JPC 6.3, C), 154.40ꢁ
Cb), 165.49 (m, CO).
19F NMR (188.2 MHz, CD2Cl2): d ꢃ
/
137.10 (m, Cꢂ
/
CHꢂCF3), 145.78 (d,
/
/
155.00 (m, C), 163.65 (d, JPC 18.6,
graphite monochromated Mo Ka radiation (lꢀ
/
0.71073
˚
/
58.5 (s), ꢃ
/
72.7
A). The data were measured by use of the program
COLLECT [57], while the intensities of the reflections were
processed and the data reduced by use of the computer
programs Denzo and Scalepak [58]. The structures of 3
(d, JPF 711, PF6)
31P{1H} NMR (81 MHz, CD2Cl2): d 27.0 (s, DMPP),
144.0 (sept, JPF 711, PF6).
ꢃ
/
and 15×
/
CH2Cl2 were solved by direct methods (SIR-92)
5.2.2.12. Reaction of [Pd(C6H4CH2NMe2ꢁ
(DMPP)(NCMe)]PF6 (5) with F3CCÅCCO2Et in
CD3CN. An NMR tube containing 5 (79 mg, 0.14
mmol) and F3CCÅCCO2Et (25 ml, 0.15 mmol) in
/
kC,N)-
[59] and those of 14b and 18b were solved by the
Patterson method (PATTY) [60].
/
The crystallographic asymmetric unit of 3 consists of
one molecule of palladacycle with all atoms in general
/
CD3CN (0.5 ml) was heated to 40 8C for 3 h for the
reaction to be complete, forming quantitatively a
mixture of 22b and 22a in a 73:27 ratio.
positions. The hydrogen atoms were included in the
˚
refinement at calculated positions (CꢁH 1.00 A) and left
riding with their carbon of attachment. The methyl
hydrogen atoms were orientated to best fit peaks in a
difference electron density map. The maximum and
/
5.2.2.13. Reaction of [Pd(C6H4CH2NMe2ꢁ
/
kC,N)-
(DMPP)(solvent)]PF6 (8) with F3CCÅCCO2Et in
/
minimum peaks in the final difference Fourier map were
0.75 e Aꢃ3, respectively, the biggest peaks
˚
1.75 and ꢃ
being located close to the palladium atom.
The terminal atom of the ethyl group of 14b was
disordered over two sites. The relative occupancy has
been refined with the isotropic displacement factor of
the minor site being set equal to Ueq of the major,
anisotropically refined one. The hydrogen atoms were
CHsCl2. Complex 3 (202 mg, 0.44 mmol) was stirred
with AgPF6 (120 mg, 0.46 mmol) in CH2Cl2 (5 ml) for
30 min at r.t. The solution was filtered through Celite
and cooled to 0 8C. The alkyne (78 ml, 0.55 mmol) was
added dropwise and the solution was then stirred for 1 h
at r.t. after which 0.4 ml of CH3CN were added. The
solvent was removed vacuo and the residue was washed
/

A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ
/97
95
Table 4
Crystal and structure refinement data for palladacycles 3, 14b, 15b×
/0.5CH2Cl2 and 18b
Molecular compound
3
14b
15b
18b
Crystal data
Chemical formula
C
21H25ClNPPd
C32H35ClNO2PPd
2(C24H28N3O2Pdꢂ)×
CH2Cl2
/
2(PF6ꢃ)×
/
C21H32ClF3NO2PPd
fw
464.26
monoclinic
C2/c (no. 15)
638.46
triclinic
¯
P1 (no. 2)
1368.66
orthorombic
Pnna (no. 52)
560.31
triclinic
¯
P1 (no. 2)
Crystal system
Space group
Unit cell dimensions
˚
a (A)
21.4365(5)
10.3813(3)
18.5103(5)
9.0562(3)
11.5445(3)
16.2941(4)
72.666(2)
79.840(2)
69.247(2)
1515.87(8)
1.399
14.9330(4)
12.3519(4)
32.0645(11)
9.2048(2)
9.7985(2)
14.3784(3)
71.7077(7)
87.8117(7)
78.2936(8)
1205.24(4)
1.544
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
99.310(1)
3
˚
V (A )
4065.0(2)
1.517
5914.3(3)
1.537
Dcalc (g cmꢃ3
)
Z
8
2
4
2
0.987
m (mmꢃ1
)
1.127 (Mo Ka)
0.782 (Mo Ka)
0.836 (Mo Ka)
Data collection, processing and refinement
2u max (8)
Data collected (h,k,l)
50.18
(ꢃ25, ꢃ
11, 22)
54.98
49.92
60.12
/
/
12, ꢃ
/
22) to (25, (ꢃ
/
11, ꢃ
/
14, ꢃ
/
18) to (11, (ꢃ
38)
39245
5202 (4.8)
2222 [I ꢀ
/14, ꢃ
/
11, ꢃ
/
33) to (17, 14, (ꢃ
/
12, ꢃ
/
13, ꢃ20) to (12,
/
14, 21)
29094
13, 20)
31917
Total reflections
Unique reflections (Rint, %)
Observed reflections
24658
3609 (3.0)
2862 [I ꢀ
6825 (6.2)
5783 [I ꢀ
integration (0.893ꢁ
7043 (7.1)
5642 [I ꢀ
integration (0.794ꢁ0.888)
/
3s(I)]
/2s(I)]
/
3s(I)]
/3s(I)]
Absorption correction (trans- integration (0.956ꢁ
/
/
0.945) integration (0.855ꢁ
/0.960)
/
mission factors)
No. of parameters
0.989)
226
347
0.0462
0.0542
361
0.0329
0.0355
271
0.0345
0.0437
R
0.0383
0.0364
Rw
included in the refinement at calculated positions (Cꢁ
/
H
biggest peaks being located close to the palladium atom
or within the PF6ꢃ anions.
In the refinement of 18b, the hydrogen atoms were
˚
0.95 A) and were frequently recalculated. The methyl
hydrogen atoms were orientated to best fit peaks in a
difference electron density map. The maximum and
˚
H 0.95 A) and were
included at calculated positions (Cꢁ
/
frequently recalculated. The maximum and minimum
peaks in the final difference Fourier map were 0.92 and
minimum peaks in the final difference Fourier map were
˚
0.90 and ꢃ
1.11 e Aꢃ3, respectively, the biggest peaks all
/
ꢃ3
˚
0.76 e A
ꢃ
/
.
The calculations were performed with use of the
˚
being located within 1 A of the palladium atom.
The crystallographic asymmetric unit of 15b×CH2Cl2
C(CO2Et)C6H4CH2-
/
crystallographic software packages TEXSAN [61], MAXUS
[62] and CRYSTALS [63]. The neutral atom scattering
factors were taken from Ref. [64]. Mass attenuation
coefficients used were those implemented in MAXUS [62].
consists of one cation [Pd{C(Ph)Ä
/
NMe2}(NCMe)2]ꢂ, two PF6 anions and one molecule
of CH2Cl2, the two anions and the solvent molecule
being located on crystallographic twofold symmetry
operations. Four coplanar F atoms of one anion were
disordered and were modelled by four sites with
anisotropic displacement factors with occupancy p,
5.4. Computational details
All calculations used the Amsterdam density func-
tional program ADF1999 [65]. A triple-z-STO basis set
was employed for Pd while all other atoms were
described by a double-z plus polarisation STO basis
set. The frozen core approximation was employed with
the 1s electrons of C, N and O atoms, up to and
including the 2p electrons of P and the 3d electrons of
Pd being frozen in calculations. All geometry optimisa-
tions used the optimisation procedure developed by
Versluis and Ziegler [66] and incorporated the gradient
while the four minor sites (1ꢃp) were modelled
isotropically with restraints imposed on their distan-
/
ces.The hydrogen atoms were included in the refinement
˚
at calculated positions (CꢁH 1.00 A) and left riding with
/
their carbon of attachment. The methyl hydrogen atoms
of the acetonitrile ligands were orientated to best-fit
peaks in a difference electron density map. The max-
imum and minimum peaks in the final difference Four-
0.50 e Aꢃ3, respectively, the
˚
ier map were 0.38 and ꢃ
/

96
A.E. Kelly et al. / Inorganica Chimica Acta 352 (2003) 79ꢁ97
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