Synthesis, characterization and reactivity of ionic palladium(II) complexes containing bidentate nitrogen ligands in a unidentate coordination mode1,2

Article abstract of DOI:10.1016/S0022-328X(98)00596-8

The novel ionic complexes [Pd(Me)(p-An-BIAN)(L-L)]SO₃CF₃ (L-L=p-An-BIAN (bis(anisylimino)acenaphthene) (1a), phen (2a), dmphen (3a), dppe (4a), dppp (5a)) have been synthesized via the reaction of [Pd(Me)(NCMe)(p-An-BIAN)]SO₃

Full text of DOI:10.1016/S0022-328X(98)00596-8

Journal of Organometallic Chemistry 573 (1999) 3–13
Synthesis, characterization and reactivity of ionic palladium(II)
complexes containing bidentate nitrogen ligands in a unidentate
coordination mode1,2
J.H. Groen a, B.J. de Jong a, J.-M. Ernsting a, P.W.N.M. van Leeuwen a, K. Vrieze a,*,
W.J.J. Smeets b, A.L. Spek b,3
a Anorganisch Chemisch Laboratorium, J.H. 6an’t Hoff Research Instituut, Uni6ersiteit 6an Amsterdam, Nieuwe Achtergracht 166,
1018 WV Amsterdam, The Netherlands
b Bij6oet Center for Biomolecular Research, Laboratorium 6oor Kristal en Structuurchemie, Uni6ersiteit Utrecht, Padualaan 8,
3584 CH Utrecht, The Netherlands
Received 17 December 1997; received in revised form 14 January 1998
Abstract
The novel ionic complexes [Pd(Me)(p-An-BIAN)(LꢀL)]SO3CF3 (LꢀL=p-An-BIAN (bis(anisylimino)acenaphthene) (1a), phen
(2a), dmphen (3a), dppe (4a), dppp (5a)) have been synthesized via the reaction of [Pd(Me)(NCMe)(p-An-BIAN)]SO3CF3 with
LꢀL. The X-ray crystal structure of complex 1a has been determined and shows a distorted square planar geometry in which one
˚
˚
BIAN ligand is coordinated in a bidentate fashion (PdꢀN(1)=2.037(4) A; PdꢀN(2)=2.189(4) A) and, interestingly, the other
˚
˚
BIAN ligand in a unidentate fashion (PdꢀN(3)=2.066(4) A; PdꢀN(4)=2.714(6) A). Spectroscopic data of the mixed ligand
complexes [Pd(Me)(p-An-BIAN)(LꢀL)]SO3CF3 (LꢀL=phen (2a), dppe (4a), dppp (5a)) indicate that the LꢀL ligand is coordi-
nated in a bidentate fashion and the p-An-BIAN ligand in a unidentate fashion, which is in agreement with the larger
complexation strength of the phen, dppe and dppp ligands, as compared with that of the p-An-BIAN ligand. In contrast, complex
3a (LꢀL=dmphen) contains a bidentate p-An-BIAN ligand and a unidentate dmphen ligand, which can be explained by the
sterically demanding methyl groups of the dmphen ligand. Complexes 1a–4a underwent insertion of carbon monoxide, resulting
in the formation of acetylpalladium complexes [Pd(C(O)Me)(p-An-BIAN)(LꢀL)]SO3CF3 (1b–4b). Since mass-law retardation by
excess p-An-BIAN has been observed for CO insertion for complexes 1a and 4a, it is proposed that the mechanism involves
dissociation of the unidentate nitrogen ligand. Complexes 1a–5a and 1b–4b show fluxional behavior due to flipping of the
unidentate nitrogen ligand. Complexes 1a–3a and 1b–3b also show fluxional behavior due to site exchange of the nitrogen atoms
of the bidentate nitrogen ligand. A mechanism for this exchange process has been proposed. This mechanism involves (a)
substitution of a nitrogen atom of the bidentate nitrogen ligand by the uncoordinated nitrogen atom of the unidentate nitrogen
ligand, (b) flipping of the unidentate nitrogen ligand, and (c) a second nitrogen substitution reaction. Reaction of the
acetylpalladium complexes 1b–4b with norbornadiene led to dissociation of the unidentate nitrogen ligand and formation of the
known alkylpalladium complexes [Pd(C7H8C(O)Me)(p-An-BIAN)]SO3CF3 (1c), [Pd(C7H8C(O)Me)(phen)]SO3CF3 (2c), 1c, and
[Pd(C7H8C(O)Me)(dppe)]SO3CF3 (4c), respectively. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Bis(anisylimino)acenapthene ligand; carbon monoxide insertion; palladium(II)
1. Introduction
* Corresponding author.
1 Dedicated to Professor Brian Johnson on the occasion of his 60th
birthday in recognition of his outstanding contributions to
organometallic and inorganic chemistry.
In the application of organopalladium complexes in
homogeneous catalysis, mainly complexes containing
phosphorus ligands have been employed to stabilize
these complexes [1–3]. In recent years there has been a
growing interest in the use of bi- and terdentate nitro-
2 Netherlands Institute for Research in Catalysis (NIOK) publica-
tion UvA 98-03-05.
3 To whom correspondence concerning crystallographic data
should be addressed.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00596-8

4
J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
gen ligands in homogeneously catalyzed processes. For
example, ionic palladium(II) complexes containing a
bidentate nitrogen ligand such as bpy and phenanthro-
line can be used as catalyst in the copolymerization of
CO and alkenes [4–12]. By using complexes containing
the rigid bidentate nitrogen ligand bis(ani-
sylimino)acenaphthene (p-An-BIAN), we succeeded in
the synthesis and full characterization of key intermedi-
ates of the CO/alkene copolymerization [13] and more
recently, of the CO/allene copolymerization [14]. Since
insertion reactions into carbon–palladium bonds play a
crucial role in these processes, we [13,15–20] and others
[21–23] have extensively investigated the mechanistic
aspects of insertion reactions in complexes containing
bi- and terdentate nitrogen ligands. Brookhart et al.
[23] carried out a mechanistic study of CO and ethylene
insertions in ionic palladium(II) complexes of the type
[Pd(R)(solv)(NꢀN)]BAr4 and found that the insertion
mechanism involves substitution of the weakly coordi-
nating solvent molecule by the substrate. Extensive
studies of CO [15], alkene [17,24], and allene [19] inser-
tion reactions in neutral complexes Pd(R)X(NꢀN) (R=
alkyl, acyl; X=halide, NꢀN=flexible or rigid
bidentate nitrogen ligand) indicated that the mechanism
may involve intermediates containing a bidentate nitro-
gen ligand coordinated as a unidentate. Interestingly, a
significant retardation of both alkene and allene inser-
tion reactions upon addition of free bidentate nitrogen
ligand was explained by formation of an intermediate
species of the type Pd(R)X(NꢀN)2, which, however,
could not be observed [19,24].
CF3 [26] and [Pd(Me)(NCMe)(dppp)]SO3CF3 [26] were
prepared according to the literature. All other starting
chemicals were used as commercially obtained. 1H-,
13C- and 31P-NMR spectra (300.13, 75.48, and 121.50
MHz, respectively) were recorded on a Bruker AMX
300 spectrometer at 20°C. Chemical shifts are in ppm
relative to TMS (1H and 13C) and 85% H3PO4 (31P) as
external standards (s=singlet, d=doublet, dd=dou-
blet of doublets, pst=pseudotriplet, m=multiplet,
br=broad). 15N chemical shifts, which are in ppm
relative to nitromethane as external standard, were
extracted from gradient-selected (1H, 15N)-HMQC ex-
periments [27–29] on a Bruker DRX 300 spectrometer.
Adopted numbering schemes for p-An-BIAN, 1,10-
phenanthroline (phen) and 2,9-dimethyl-1,10-phenan-
throline (dmphen) are as follows:
Here, we report the synthesis and characterization of
novel complexes of the type Pd(Me)(p-An-
BIAN)(LꢀL)]SO3CF3 (LꢀL=p-An-BIAN; 1,10-phen-
anthroline
(phen);
2,9-dimethyl-1,10-phenanthro-
line (dmphen); 1,2-bis(diphenylphosphino)ethane (dp-
pe); 1,3-bis(diphenylphosphino)propane (dppp). These
complexes contain the bidentate p-An-BIAN ligand
and a second bidentate ligand LꢀL, one of which is
coordinated in a bidentate fashion, the other in a
unidentate fashion. Furthermore, we present a study of
the fluxional behavior of these complexes and of their
the reactivity toward CO.
IR spectra were obtained on a Bio-Rad FTS-7 spec-
trophotometer and mass spectra on a JEOL JMS SX/
SX102A four-sector mass spectrometer, coupled to a
JEOL MS-MP7000 data system.
2. Experimental
2.2. Synthesis of [Pd(Me)(p-An-BIAN)(LꢀL)]SO3CF3
(LꢀL=pꢀAn-BIAN (1a), phen (2a), dmphen (3a), dppe
(4a), dppp (5a))
2.1. General comments
All manipulations were carried out in an atmosphere
of purified dry nitrogen by using standard Schlenk
techniques. Solvents were dried and stored under nitro-
gen. Carbon monoxide 99.5% was purchased from
HoekLoos and was used without further purification.
The compounds p-An-BIAN [25], [Pd(Me)(NCMe)(p-
An-BIAN)]SO3CF3 [13], [Pd(Me)(NCMe)(dppe)]SO3-
To a solution of [Pd(Me)(NCMe)(p-An-BIAN)]SO3-
CF3 (89.3 mg, 0.13 mmol) in dichloromethane (20 ml)
p-An-BIAN (65.9 mg, 0.17 mmol) was added.
After stirring at 20°C for 5 min, the dark brown
solution was evaporated to dryness. Washing the
residue with diethylether (2×20 ml) and hexane
(2×20 ml) and drying in vacuo, yielded [Pd(Me)(p-An-

J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
5
BIAN)2]SO3CF3 (1a) as a brown solid compound
(130.4 mg, 95%).
4.00 (s, H12), 2.6 (4H, m, CH2P), 1.95 (2H, m,
CH2CH2P), 0.38 (dd, J=6.5, 3.2 Hz, MeꢀPd). 31P-
NMR (CDCl3): l 23.6 (d, J=53 Hz, P cis to Me),
−2.0 (d, J=53 Hz, P trans to Me). Mass found:
m/z=925.2283. [C54H49N2O2P2Pd]+ calc.: m/z=
925.2323.
Complexes 2a–5a could be synthesized from
[Pd(Me)(NCMe)(p-An-BIAN)]SO3CF3 and LꢀL or
from [Pd(Me)(NCMe)(LꢀL)]SO3CF3 and p-An-BIAN
in the same way (81–93%). No correct microanalyses
were obtained for 2a–5a due to the presence of a
small amount (5–10%) of [Pd(Me)(LꢀL)2]SO3CF3 or
other unidentified impurities.
2.3. Synthesis of [Pd(C(O)Me)(p-An-BIAN)(LꢀL)]SO3-
CF3 (LꢀL=p-An-BIAN (1b), phen (2b))
1
1a: H-NMR (CDCl3): l 8.08 (d, J=8.3 Hz, H5),
7.50 (pst, H4), 7.0 (20H, m, H3, H9, H10), 3.89 (s,
H12), 0.70 (s, PdꢀMe). 13C-NMR (CDCl3): l 166.9
(C1), 159.4 (C11), 143.5 (C7), 140.8 (C8), 131.6 (C5),
131.6 (C6), 128.9 (C4), 127.2 (C2), 125.2 (C3), 122.4
(C10), 115.5 (C9), 56.2 (C12), 7.1 (PdꢀMe). 15N-NMR
A solution of [Pd(Me)(p-An-BIAN)2]SO3CF3 (1a)
(39.4 mg, 0.037 mmol) in 20 ml of dichloromethane
was stirred at 20°C in a CO atmosphere. After 10
min, the solution was filtered through Celite and the
residue was extracted with dichoromethane (5 ml).
The combined filtrates were evaporated to dryness
and the product was washed with hexane (2×20 ml),
yielding 1b as a dark brown solid (34.3 mg, 85%).
Complex 2b was synthesized from 2a in the same
way (73%).
(CDCl3):
l −97.1. Mass found: m/z=905.2319.
[C53H43N4O4Pd]+ calc.: m/z=905.2239. Anal. Found:
C, 61.23; H, 4.07; N, 5.33. C54H43F3N4O7PdS calc.: C,
61.45; H, 4.11; N, 5.31.
1
2a: H-NMR (CDCl3): l 8.82 (dd, J=5.1, 1.2 Hz,
H13), 8.55 (dd, J=8.3, 1.2 Hz, H15), 8.06 (d, J=8.3
Hz, H5), 7.96 (dd, J=8.3, 5.1 Hz, H14), 7.90 (s,
H18), 7.51 (pst, H4), 7.13 (6H, m, H3, H10), 6.98 (d,
J=8.9 Hz, H9), 3.82 (s, H12), 1.06 (s, PdꢀMe). 13C-
NMR (CDCl3): l 162.9 (C1), 158.3 (C11), 148.4
(C13), 145.5 (C17), 142.4 (C8), 141.2 (C7), 138.5
(C15), 130.9 (C6), 130.4 (C5), 130.0, 127.9, 127.9,
125.7 (C2, C14, C16, C18), 127.3 (C4), 124.5 (C3),
120.9 (C10), 115.0 (C9), 55.4 (C12), 2.1 (PdꢀMe). 15N-
NMR (CDCl3): l −79.7 (BIAN nitrogen atoms),
−138.0 (phen nitrogen atoms). Mass found: m/z=
693.1443. [C39H31N4O2Pd]+ calc.: m/z=693.1482.
1
1b: H-NMR (CDCl3): l 8.09 (d, J=8.3 Hz, H5),
7.52 (pst, H4), 7.20 (d, J=8.9 Hz, H10), 7.15 (d,
J=7.3 Hz, H3), 6.89 (d, J=8.9 Hz, H9), 3.80 (s,
H12), 1.89 (s, C(O)Me). 13C-NMR (CDCl3): l 221.4
(CO), 165.1 (C1), 158.9 (C11), 142.8 (C7), 139.9 (C8),
131.0 (C5), 131.0 (C6), 128.2 (C4), 126.6 (C2), 124.5
(C3), 122.1 (C10), 114.9 (C9), 55.4 (C12), 30.3
(C(O)Me). IR (KBr): 1708 cm−1, w(CO). Mass found:
m/z=933.2246. [C54H43N4O5Pd]+
calc.: m/z=
933.2268. Anal. Found: C, 61.09; H, 3.95; N, 5.23.
C55H43F3N4O8PdS calc.: C, 60.97; H, 4.00; N, 5.17.
1
1
3a: H-NMR (CDCl3): l 8.31 (d, J=8.2 Hz, H15),
2b: H-NMR (CDCl3): l 8.70 (d, J=5.0 Hz, H13),
8.11 (d, J=8.4 Hz, H5), 7.79 (s, H18), 7.76 (d, J=
8.2 Hz, H14), 7.49 (pst, H4), 7.01 (2 H, br, H3), 6.8
(8H, br, H9, H10), 3.80 (6H, br, H12), 3.35 (s, H19),
0.61 (s, PdꢀMe). 13C-NMR (CDCl3): l 159.0 (C13),
158.6 (C11), 144.4 (C17), 141.8 (C8), 137.7 (C15),
131.3 (C16), 131.0 (C5), 128.5 (C4), 127.7 (C2), 125.9
(C3), 124.9, 124.6 (C14, C18), 121.6 (br, C10), 114.4
(br, C9), 55.4 (C12), 28.0 (C19), 2.4 (PdꢀMe), signals
of C1, C6, and C7 were not observed. 15N-NMR
(CDCl3): l −114.0 (dmphen nitrogen atoms), signals
of BIAN nitrogen atoms were not observed. Mass
found: m/z=721.1770. [C41H35N4O2Pd]+ calc.: m/z=
721.1795.
8.60 (d, J=8.2 Hz, H15), 8.10 (d, J=8.3 Hz, H5),
7.98 (s, H18), 7.94 (dd, J=8.2, 5.0 Hz, H14), 7.54
(pst, H4), 7.15 (d, J=7.4 Hz, H3), 7.01 (d, J=8.9
Hz, H10), 6.94 (d, J=8.9 Hz, H9), 3.83 (s, H12),
2.57 (s, C(O)Me). 13C-NMR (CDCl3): l 229.8 (CO),
163.4 (C1), 158.5 (C11), 149.6 (C13), 144.2 (C7), 141.5
(C8), 139.9 (C17), 138.9 (C15), 131.0 (C6), 130.9 (C5),
129.9, 128.1, 127.5, 127.4, 125.8, 124.9 (C2, C3, C4,
C14, C16, C18), 120.9 (C10), 115.1 (C9), 55.4 (C12),
34.6 (C(O)Me). IR (KBr): 1693 cm−1, w(CO). Mass
found: m/z=721.1408. [C40H31N4O3Pd]+ calc.: m/z=
721.1431. No correct microanalysis was obtained due
to the presence of a small amount (5–10%) of
[Pd(C(O)Me)(phen)2]SO3CF3.
1
4a: H-NMR (CDCl3): l 8.04 (d, J=8.4 Hz, H5),
7.6–7.2 (22H, m, PhꢀP, H4), 6.99 (d, J=7.2 Hz,
H3), 6.89 (d, J=8.7 Hz, H10), 6.67 (d, J=8.7 Hz,
H9), 3.95 (s, H12), 2.6–2.1 (4H, m, CH2P), 0.57 (dd,
J=6.3, 2.8 Hz, MeꢀPd). 31P-NMR (CDCl3): l 59.1
(d, J=27 Hz, P cis to Me), 39.1 (d, J=27 Hz, P
trans to Me). Mass found: m/z=911.2171.
[C53H47N2O2P2Pd]+ calc.: m/z=911.2148.
2.4. Synthesis of [Pd(C(O)Me)(p-An-BIAN)(LꢀL)]SO3-
CF3 (LꢀL=dmphen (3b), dppe (4b))
A solution of [Pd(Me)(p-An-BIAN)(dmphen)]SO3-
CF3 (3a) (30.2 mg, 0.035 mmol) in dichloromethane
(20 ml) was placed in a 100 ml stainless-steel auto-
clave, and CO was introduced up to 15
1
5a: H-NMR (CDCl3): l 8.00 (d, J=8.3 Hz, H5),
7.43 (pst, H4), 7.3–6.9 (30H, m, PhꢀP, H3, H9, H10),

6
J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
bar. After stirring at 20°C for 30 min, the pressure was
released and the solution was filtered through Celite.
The residue was extracted with dichloromethane (5 ml)
and the combined filtrates were evaporated to dryness.
The product was washed with hexane (2×20 ml) and
dried in vacuo, yielding a dark brown product (0.025
mmol, 71%).
fractometer. Numerical details have been collected in
Table 1. Cell parameters were derived from the setting
angles of 25 SET4 reflections [32]. The triclinic unit cell
was checked for the presence of possible higher metrical
symmetry with the program LEPAGE [33] with nega-
tive result. The structure was solved with Patterson
techniques using the program DIRDIFF-96 [34] and
refined on F2 using SHELXL-96 [35]. A final difference
Fourier map did not show any significant features other
than absorption artifacts near Pd and Cl. All geometri-
cal calculations and the illustration were done with
PLATON [36]. Full details may be obtained from one
of the authors (A.L.S.).
Complex 4b was obtained from 4a in the same way
by using 25 bar of CO (86%).
1
3b: H-NMR (CDCl3): l 8.36 (d, J=8.3 Hz, H15),
8.10 (d, J=8.3 Hz, H5), 7.86 d (J=8.3 Hz, H14), 7.81
(s, H18), 7.49 (pst, H4), 7.03 (d, J=7.3 Hz, H3), 6.7
(8H, br, H9, H10), 3.76 (s, H12), 3.61 (s, H19), 1.74 (s,
C(O)Me). 13C-NMR (CDCl3): l 166.8 (C1), 159.6,
158.6 (C11, C13), 144.1 (C7), 141.4 (C8), 139.2 (C17),
138.2 (C15), 131.2 (C6), 131.1 (C5), 128.4 (C4), 127.4
(C16), 126.1 (C2), 125.9, 125.5, 124.8 (C3, C14, C18),
121.2 (C10), 114.4 (C9), 55.4 (C12), 31.0 (C(O)Me),
28.0 (C19), signal of C(O)Me was not observed. IR
3. Results and discussion
3.1. Synthesis and characterization of complexes 1a–5a
The
reaction
of
the
ionic
complex
(KBr): 1704 cm−1
, w(CO). Mass found: m/z=
[Pd(Me)(NCMe)(p–An-BIAN)]SO3CF3 with LꢀL led to
the formation of the stable complexes [Pd(Me)(p-An-
BIAN)(LꢀL)]SO3CF3 (LꢀL=p-An-BIAN (1a), phen
(2a), dmphen (3a), dppe (4a), dppp (5a)) (Equation 1).
749.1808. [C42H35N4O3Pd]+ calc.: m/z=749.1744. No
correct microanalysis was obtained, due to the presence
of a small amount (5–10%) of [Pd(C(O)Me)(dmphen)2-
]SO3CF3.
1
4b: H-NMR (CDCl3): l 8.04 (d, J=8.3 Hz, H5),
7.6–6.8 (32H, m, PhꢀP, H3, H4, H9, H10), 3.96 (s,
H12), 2.7–2.2 (4H, m, CH2P), 1.82 (br, C(O)Me). 31P-
NMR (CDCl3): l 37.9 (d, J=46 Hz, P cis to Me), 30.3
Table 1
Crystal data and details of the structure determination for 1a
Empirical formula
Formula weight
Crystal system
Space group
C53H43N4O4Pd, CF3O3S, 2(CH2Cl2)
1225.30
triclinic
P1 (No. 2)
11.332(2), 14.561(4), 17.407(7)
92.73(3), 94.56(3), 111.833(18)
2648.5(14)
(d, J=46 Hz, P trans to Me). IR (KBr): 1675 cm−1
,
w(CO). Mass found: m/z=940. [C54H48N2O3P2Pd]+
calc.: m/z=940. No correct microanalysis was ob-
tained, due to the presence of a small amount (5–10%)
of unidentified impurities.
˚
a, b, c (A)
h, i, k (°)
3
˚
V (A )
Z
2
Dcalcd (g cm−3
F(000)
)
1.536
1248
6.6
2.5. Reaction of acetylpalladium complexes 1b–4b with
norbornadiene
v [Mo–Kh] (cm−1
Crystal size (mm)
Temperature (K)
)
0.12×0.25×0.88
150
Mo–Kh (graphite–monochrom.), 0.71073
1.2, 25.0
To a solution of the acetylpalladium complex 1b–4b
(ca. 0.02 mmol) in dichloromethane (20 ml) one equiva-
lent of norbornadiene was added. After stirring the
mixture at 20°C for 10 min (for 1b, 2b and 4b) or 1 h
(for 3b), the solvent was evaporated and the product
was washed with hexane (2×20 ml) and dried in
vacuo. The products, which had formed quantitatively,
˚
Radiation (A)
qmin, qmax (°)
Scan [type and
range] (°)
Hor. and vert. aper- 3.00, 4.00
ture (mm)
1.10+0.35 tan q
Data set
−13:13; −17:17; 0:20
1
were characterized by H-NMR spectroscopy, and in
Total, unique data, 9652, 9313, 0.097
the case of 4b by 31P-NMR spectroscopy aswell. The
Rint
Observed data
No. of reflns and
params
R, ꢀR, S
Weighting scheme
6612 [I\2.0|(I)]
9313, 690
NMR spectra showed that the known complexes
[Pd(C7H8C(O)Me)(p-An-BIAN)]SO3CF3
[13]
(1c),
[Pd(C7H8C(O)Me)(phen)]SO3CF3 [30] (2c), 1c and
[Pd(C7H8C(O)Me)(dppe)]SO3CF3 [31] (4c) had formed,
respectively.
0.0608, 0.1510, 1.01
ꢀ=1/[|2(F20)+(0.0703P)2+2.1899P] where
P=(F20+2F2c)/3
Max. and av. shift/ 0.00, 0.00
error
2.6. Structure determination of 1a
Min. and max.
resd. dens.
−1.00, 0.70
−3
˚
X-ray data were collected for a dark cut-to-size crys-
(eA
)
tal on an Enraf-Nonius CAD4T/Rotating Anode dif-

J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
7
The reactions occurred instantaneously and the
products were formed in high yield (81–95%). Com-
plexes 2a–5a could also be prepared by the reaction
of complexes [Pd(Me)(NCMe)(LꢀL)]SO3CF3 with one
equivalent of p-An-BIAN. Due to the low solubility
of the starting complexes [Pd(Me)(NCMe)(phen)]SO3-
palladium atom is surrounded by four nitrogen atoms
of two p-An-BIAN ligands and by the carbon atom
of a methyl group. Whereas one p-An-BIAN ligand is
coordinated in a bidentate fashion (Pd(1)ꢀN(1)=
˚
˚
2.037(4) A; Pd(1)ꢀN(2)=2.189(4) A), the other p-An-
BIAN ligand is coordinated in an asymmetric fashion
with only one nitrogen atom at bonding distance from
CF3
and
[Pd(Me)(NCMe)(dmphen)]SO3CF3
in
dichloromethane, the preferred way to prepare com-
plexes 2a and 3a is the former route.
˚
the palladium center (Pd(1)ꢀN(3)=2.066(4) A) and
Complexes 1a–5a were characterized by 1H-NMR
and mass spectroscopy. Complexes 1a–3a were further
characterized by 13C-NMR spectroscopy and com-
plexes 4a and 5a by 31P-NMR spectroscopy. Unfortu-
nately, no correct analytical data could be obtained
for 2a–5a due to the presence of small amounts (5–
10%) of [Pd(Me)(LꢀL)2]SO3CF3 (for complexes 2a and
3a) and unidentified impurities (for complexes 4a and
5a). Purification of complexes 2a–5a by crystallisation
from dichloromethane/hexane or dichloromethane/di-
ethylether was attempted, but unfortunately failed. In
contrast, crystals of 1a suitable for an X-ray structural
determination were obtained from dichloromethane/
hexane (vide infra). All methylpalladium complexes
1a–5a show a characteristic MeꢀPd resonance at 0.3–
the other nitrogen atom at a much longer distance
˚
(Pd(1)ꢀN(4)=2.714(6) A). An almost identical asym-
metric coordination fashion has been reported for the
p-An-BIAN ligand in Pd(p3-C5H8C(O)Me)Cl(p-An-
BIAN) [14] and for the dmphen ligand in Pd(p3-
C5H9)Cl(dmphen) [37], PtCl(dmphen)(PPh3)2]Cl [38]
and PtX2(dmphen)(L) (X=Cl, I; L=PPh3, CO,
N(O)Ph) [38,39]. When Pd(1)ꢀN(4) is considered as a
bond, the geometry of 1a might be described as dis-
torted square pyramidal with the nitrogen atoms N(1),
N(2), N(3), and the carbon atom C(100) occupying
the basal positions and the nitrogen atom N(4) posi-
tioned on the apical site. Elongation of the apical
bond is quite common in square pyramidal complexes
and several values of the ratio of the axial/equatorial
bond length are available, e.g. 1.17 for [Ni(CN)5]2−
[40], 1.16 for PdBr2(PR3)3 (PR3=2-phenylisophos-
phindoline) [41], 1.15 for Pd(p3-C5H9)Cl(dmphen) [37],
and 1.14 for PtI2(dmphen)(CO) [39]. Since these values
are considerably smaller than the ratio of 1.31 for
complex 1a, the geometry of 1a can be regarded as
approximately square planar.
1
1.1 ppm in the H-NMR spectra and in the case of
1a–3a at 2–10 ppm in the 13C-NMR spectra. As ex-
pected, the 31P-NMR spectra of complexes 4a and 5a
show two resonances. In comparison with complexes
Pd(Me)Cl(PꢀP) and [Pd(Me)(NCMe)(PꢀP)]SO3CF3
(PꢀP=dppe, dppp, dppb, dppf) [26], the lowest fre-
quency resonance is assigned to the phosphorus atom
positioned trans to the methyl group.
The Pd(1)ꢀN(2) distance is longer than the
Pd(1)ꢀN(1) distance due to the relatively large trans
influence [42] of the methyl group. The methyl–palla-
3.2. Molecular structure of
[Pd(Me)(p-An-BIAN)2]SO3CF3 (1a)
˚
dium distance of 2.029(6) A and the Pd(1)ꢀN(1),
Pd(1)ꢀN(2) and Pd(1)ꢀN(3) distances are as expected
and can be compared with those found for other
methylpalladium complexes bearing a bi- or terdentate
nitrogen ligand [15,16,18,25,43–45].
The molecular structure of 1a with the adopted
numbering scheme is shown in Fig. 1. Selected bond
distances and angles are reported in Table 2. The

8
J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
Fig. 1. ORTEP drawing (50% probability level) and adopted numbering scheme of [Pd(Me)(p-An-BIAN)2]SO3CF3 (1a); hydrogen atoms, SO3CF3
anion and CH2Cl2 have been omitted for clarity.
as doublet of doublets, which indicates that the
diphosphine ligand is coordinated in a bidentate fash-
ion and the p-An-BIAN ligand in a unidentate fash-
ion. To determine the coordination modes of the
nitrogen ligands in complexes 2a and 3a, nitrogen
chemical shifts were determined for complexes 1a–3a
and for the free ligands p-An-BIAN, phen and dm-
phen (see Table 3) [46].
3.3. Coordination modes of the bidentate ligands in
complexes 1a–5a
Complexes 1a–5a contain two bidentate ligands,
one of which is coordinated in a bidentate fashion,
the other in a unidentate fashion. In the 1H-NMR
spectra of 4a and 5a the Me–Pd resonance appears
Table 2
Table 3
˚
Selected bond distances (A) and angles (°) for complex 1a (with
estimated S.D.s in parentheses)
15N-NMR data of p-An-BIAN, phen, dmphen and complexes 1a–3a
(with CIS values in parentheses)a
˚
Bond distances (A)
Compound
15N Chemical shift
(ppm)b
Pd(1)ꢀN(1)
Pd(1)ꢀN(2)
Pd(1)ꢀN(3)
Pd(1)ꢀN(4)
Pd(1)ꢀC(100)
N(1)ꢀC(8)
2.037(4)
2.189(4)
2.066(4)
2.714(6)
2.029(6)
1.302(6)
N(2)ꢀC(19)
N(3)ꢀC(34)
N(4)ꢀC(45)
C(8)ꢀC(19)
C(34)ꢀC(45)
1.294(7)
1.281(8)
1.270(8)
1.489(8)
1.515(8)
p–An-BIAN
phen
dmphen
[Pd(Me)(p−An-BIAN)2]SO3CF3 (1a)
[Pd(Me)(p-An-BIAN)(phen)]SO3CF3
(2a)
−40.3
−74.4
−80.2
−97.1 (−56.8)
−138.0 (−63.6), phen
N;
−79.7 (−39.4), BIAN
N
Bond angles (°)
N(1)ꢀPd(1)ꢀN(2)
N(1)ꢀPd(1)ꢀN(3)
N(1)ꢀPd(1)ꢀN(4)
N(1)ꢀPd(1)ꢀC(100)
N(2)ꢀPd(1)ꢀN(3)
N(2)ꢀPd(1)ꢀN(4)
79.54(16)
174.01(18)
115.61(17)
91.1(2)
101.85(15)
97.92(17)
N(3)ꢀPd(1)ꢀC(100)
N(4)ꢀPd(1)ꢀC(100)
Pd(1)ꢀN(1)ꢀC(8)
Pd(1)ꢀN(1)ꢀC(5)
Pd(1)ꢀN(2)ꢀC(19)
Pd(1)ꢀN(2)ꢀC(20)
Pd(1)ꢀN(3)ꢀC(31)
Pd(1)ꢀN(3)ꢀC(34)
87.2(2)
88.4(2)
114.2(4)
128.5(3)
110.3(3)
128.1(3)
114.7(4)
124.4(4)
[Pd(Me)(p-An-BIAN)(dmphen)]SO3CF3 −114.0 (−33.8),
(3a)c
dmphen N
N(2)ꢀPd(1)ꢀC(100) 170.3(2)
N(3)ꢀPd(1)ꢀN(4) 70.10(17)
a Recorded in CDCl3 at 20°C.
b CIS values are given in parentheses.
c Signal of BIAN nitrogen atoms was not observed.

J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
9
In the range 253–293 K, the 15N-NMR spectra of 1a
in CDCl3 show an averaged signal for the four BIAN
nitrogen atoms at −79.7 ppm. In the case of complex
2a, the 15N-NMR spectrum at 293 K shows averaged
signals for the phen and BIAN nitrogen atoms at
−138.0 and −79.7 ppm, respectively. In the range
223–293 K, the 15N-NMR spectra of 3a in CDCl3
exhibit an averaged signal of the dmphen nitrogen
atoms at ca. −114 ppm, whereas signals of the BIAN
nitrogen atoms were not observed. It is known that
signals of nitrogen atoms show a dramatic low-fre-
quency shift ranging from −50 to −90 ppm upon
coordination to palladium [47,48]. Whereas the aver-
aged coordination induced shift (CIS, Dl) of −63.6
ppm for the phen nitrogen atoms in 2a indicates that
the phen ligand is coordinated in a bidentate fashion,
the relatively low averaged CIS value of −39.4 ppm
for the BIAN nitrogen atoms in 2a suggests a uniden-
tate coordination fashion of the BIAN ligand. Simi-
larly, the low averaged CIS value of −33.8 ppm for the
dmphen nitrogen atoms in 3a suggests that a unidentate
coordination of the dmphen ligand and, as a conse-
quence, a bidentate coordination of the BIAN ligand.
From these results it is evident that the coordination
mode of the p-An-BIAN ligand in complexes
[Pd(Me)(p-An-BIAN)(LꢀL)]SO3CF3 (1a–5a) is highly
dependent on the nature of the LꢀL ligand. In the case
of LꢀL=dppe (4a) and dppp (5a), which coordinate
more strongly to a palladium(II) center than the p-An-
BIAN ligand, a bidentate coordination mode of the
LꢀL ligand is preferred, while the BIAN ligand is
coordinated in a unidentate fashion. The large |-coor-
dinating ability of the phen ligand as compared with
that of the p-An-BIAN ligand [49] favours for 2b a
structure in which the p-An-BIAN ligand is coordi-
nated as a unidentate. The bidentate coordination of
the p-An-BIAN ligand in complex 3a is most probably
caused by the more favorable unidentate coordination
of the dmphen ligand, which bears two sterically de-
manding methyl groups adjacent to the nitrogen donor
atoms. Coordination of the dmphen ligand in a biden-
tate fashion may lead to considerable steric interactions
between these methyl groups and the other ligands, as
has been observed for the complexes PtCl2(dmphen)
[50] and Pd(Me)Cl(dmphen) [43].
3.4. Synthesis and characterization of complexes 1b–4b
Methylpalladium complexes 1a–4a reacted with CO
to give the corresponding acetylpalladium complexes
1b–4b (Equation 2).
In the case of complexes 1a and 2a the reactions were
completed within 1 min under ambient conditions in
dichloromethane (1 bar CO pressure, 20°C), showing
rates comparable with those found for the neutral
complexes Pd(Me)Cl(Ar-BIAN) [13,24], but the rates
were lower than those observed for the ionic complexes
[Pd(Me)(NCMe)(Ar-BIAN)]SO3CF3 [13]. Complexes 3a
and 4a reacted much more slowly with CO and a CO
pressure of 15 and 25 bar, respectively, was required for
a rapid conversion. Complex 5a also reacted with CO
as could be concluded from the disappearance of the
resonances of 5a in the 1H- and 31P-NMR spectra.
However, only uncharacterized compounds were
obtained.
Interestingly, the insertion of CO into the
methylꢀpalladium bond of 1a was strongly retarded by
addition of free p-An-BIAN. Whereas carbonylation of
1a was completed within 1 min in the absence of free
p-An-BIAN, in the presence of 1.5 equivalents of p-An-
BIAN, the conversion of 1a to 1b was only 5% after 1
min. Similar to 1a, the carbonylation of 4a is inhibited
by free p-An-BIAN (75% conversion to 4b after 30 min
in the absence of free p-An-BIAN, 15% conversion
after 30 min in the presence of 1.5 equivalents of free
p-An-BIAN). Unfortunately, the influence of free nitro-
gen ligand on the carbonylation rates of 2a or 3a could
not be studied due to nitrogen ligand substitution
reactions.
The stable acetylpalladium complexes 1b–4b were
1
isolated and characterized by H-NMR, IR, and mass
spectroscopy. Complexes 1b–3b were further character-
ized by 13C-NMR spectroscopy and complex 4b by
31P-NMR spectroscopy. Unfortunately, no correct ana-
lytical data could be obtained for 2b–4b due to the
presence of small amounts (5–10%) of [Pd(C(O)-
Me)(LꢀL)2]SO3CF3 (for complexes 2b and 3b) and
unidentified impurities (for complex 4b). Formation of
complexes 1b–4b after the reaction of complexes 1a–4a
with CO is clear from the high-frequency

10
J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
Scheme 1. Two proposed mechanisms for CO insertion reaction in complexes 1a–4a.
shift of the methyl resonance from 0.3–1.1 to 1.7–2.6 ppm
in the 1H-NMR spectra, the observation of a CO
stretching frequency in the IR spectra (1690–1710 cm−1),
and in the case of 1a–3a from the resonances of the
C(O)Megroupinthe13C-NMRspectra(ca. 225ppm(CO)
and ca. 32 ppm (Me)). Insertion of CO into the
methyl–palladium bond of 4a is also evident from the
low-frequency shift of the phosphorus resonances from
59.1/39.1 to 37.9/30.3 ppm in the 31P-NMR spectrum [26].
The small shift of the phosphorus trans to the R group
as compared with that of the phosphorus in cis position
and the increasing coupling constant 2J(P,P) from 27 to
46Hzuponcarbonylationof4ahavebeenobservedbefore
for the carbonylation of complexes Pd(Me)Cl(PꢀP) and
[Pd(Me)(NCMe)(PꢀP)]SO3CF3 (PꢀP=dppe, dppp, dp-
pb, dppf) [26].
a ligand donor atom by CO, i.e. the making of the PdꢀCO
bond occurs before the breaking of a ligand–palladium
bond. A possible mechanism for CO insertion in com-
plexes 1a–4a involves CO association, dissociation of the
unidentate nitrogen ligand, a rate-determining migratory
COinsertion,andcoordinationofthedissociatednitrogen
ligand (Scheme 1, pathway A).
Such a mechanism is in agreement with the retardation
of the CO insertion in complex 1a and 4a upon addition
of an excess free p-An-BIAN and it explains the obser-
vation that rate of CO insertion for [Pd(Me)(dppe)
(L)]SO3CF3 and [Pd(Me)(p-An-BIAN)(L)]SO3CF3 de-
creases in the order L=MeCNꢀp-An-BIAN, i.e. with
increasing PdꢀL bond strength. Furthermore, CO inser-
tion in [Pd(Me)(dppe)(p-An-BIAN)]SO3CF3 (4a) via
pathway A is completely in agreement with extensive
studies of CO [26,51–53] and alkene insertion reactions
[31,53] in complexes of the type [Pd(R)(PꢀP)(L)]Y (R=
Me, Ph, C(O)Me; PꢀP=bidentate phosphine ligand;
Y=SO3CF3,BF4;L=MeCN,PPh3),whichrevealedthat
insertion predominantly occurs via dissociation of the L
ligand.
3.5. Mechanism of CO insertion in complexes 1a–4a
The observation that the rate of CO insertion in
complexes [Pd(Me)(p-An-BIAN)(LꢀL)]SO3CF3 de-
creases in the order LꢀL=p-An-BIAN (1a)ꢀdmphen
(3a), i.e. with increasing steric demand of the unidentate
nitrogen ligand, indicates an associative substitution of
Analternativepathway(Scheme1, pathwayB)involves
formation of species containing two unidentate bonded

J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
11
Scheme 2. Proposed mechanisms for exchange processes in complexes 1–5.
bidentateligandsviadissociationoftheLatompositioned
trans to the methyl group, which has a relatively large
trans influence [42]. Isomerization followed by a rate-de-
termining CO insertion and association of the L atom
leadstotheproduct.Recently,formationofsimilarspecies
containing two unidentate NꢀN ligands has been pro-
posed to explain the retardation of alkene and allene
insertionreactionsofcomplexesofthetypePd(R)X(NꢀN)
upon addition of free nitrogen ligand [19,24]. Further-
more, coordination of two bidentate nitrogen ligands in
a unidentate fashion has been observed recently for
[Rh(nbd)(iPr-6-Me-PyCa)2]SO3CF3 (iPr-6-Me-PyCa=
2-(N-2-propanecarbaldimino)-6-methylpyridine) [54].
PathwayBexplainstheincreaseoftherateofCOinsertion
for complexes [Pd(Me)(LꢀL)(p-An-BIAN)]SO3CF3 in the
order LꢀL=dppeꢁp-An-BIAN:phen, i.e. with in-
creasingPdꢀLbondstrength. However, thispathwaydoes
not account for the observed retardation of the CO
insertion in 1a and 4a upon addition of free p-An-BIAN.
Therefore, we prefer pathway A for CO insertion in
complexes 1a–4a.
lent, indicating nitrogen donor atom site exchange that
is fast on the 1H-NMR time scale. In contrast, at 203 K
the 1H-NMR spectra of 3a,b exhibit separate signals for
the acenaphthene protons on both sides of the p-An-
BIAN ligand, which are sharp for 3a and broadened for
3b. Coalescence of these signals is reached at 273 K for
3a and at 243 K for 3b. Intermolecular nitrogen ligand
exchange can be excluded as source of the observed
exchange processes, since addition of free p-An-BIAN to
1a gave sharp signals for the individual resonances of free
and coordinated p-An-BIAN. In the range 203–293 K
the 31P-NMR spectra of complexes 4a,b and 5a show two
sharp doublets, indicating that phosphorus donor atom
site exchange is slow on the 31P-NMR time scale.
Analogous to what has been proposed for the platin-
um(II) complexes [PtX(NꢀN)(PR3)2]X (X=Cl, Br, I,
BF4; R=Et, n-Bu, Ph; NꢀN=phen, dmphen, 1,8-naph-
thyridine) [38,55] and PtX2(dmphen)(PPh3) (X=Cl, Br,
I) [38], the equivalence of both sides of the unidentate
nitrogen ligand in complexes 1–4 and 5a can be explained
by a dynamic process involving fast exchange of the two
nitrogen atoms at the same coordination site (flipping)
(Mechanism A in Scheme 2). Since flipping of the
unidentate nitrogen ligand is fast on the NMR time scale,
even at the lowest temperature used, a detailed study of
this dynamic process could not be performed. A mecha-
nism (Scheme 2, mechanism B1) which explains the
nitrogen donor atom site exchange in complexes 1–3
involves (a) substitution of the nitrogen atom positioned
trans to the R group by the uncoordinated nitrogen atom,
3.6. Fluxional beha6ior of complexes 1a,b–4a,b and 5a
In the range 203–293 K, the 1H-NMR spectra of
1a,b–4a,b and 5a show averaged signals for each pair of
protons on either sides of the unidentate bonded nitrogen
1
ligand. In the same temperature range, the H-NMR
spectra of complexes 1a,b and 2a,b also show that both
sides of the bidentate bonded nitrogen ligand (p-An-
BIAN and phen, respectively) are magnetically equiva-

12
J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
which may occur rather easily due to the large trans
influence [42] of the R group, (b) flipping of the unidentate
LꢀL ligand (vide supra), and (c) nitrogen substitution
similar to (a).
than that observed for the ionic complex
[Pd(C(O)Me)(NCMe)(p-An-BIAN)]SO3CF3 [13]. In con-
trast, complex 3b reacted much more slowly with norbor-
nadiene and conversion to 1c and free dmphen was only
completed after 1 h. Since the products 1c, 2c, and 4c are
similar to those obtained after reaction of norbornadiene
with complexes [Pd(C(O)R)(NCMe)(LꢀL)]SO3CF3 and
Pd(C(O)R)X(LꢀL) (R=Me, Et, iPr, Ph; LꢀL=NꢀN,
PꢀP; X=Cl, Br, I), which mechanisms have been studied
extensively [13,22,24,31,53], norbornadiene insertion in
complexes 1b–4b was not studied any further.
An alternative mechanism (Scheme 2, mechanism B2)
which may explain the nitrogen donor atom site exchange
in complexes 1–3 involves (a) dissociation of the nitrogen
atom positioned trans to the R group, resulting in a
T-shaped intermediate, in which both nitrogen ligands are
coordinated in a unidentate fashion, (b) a cis–trans
isomerization, which is known to proceed fast in T-shaped
intermediates [56], and (c) nitrogen association. Both
mechanisms B1 and B2 explain the fast nitrogen donor
atom site exchange in complexes 1–3 as compared with
the phosphorus donor atom site exchange in complexes
4a,b and 5a, which contain strongly coordinating biden-
tate phosphine ligands. Furthermore, mechanisms B1 and
B2 explain the slow nitrogen donor atom exchange in
complex 3a as compared with that in complex 3b, which
contains an acetyl group with a relatively large trans
influence [42]. Only mechanism B1, however, explains the
slow nitrogen donor atom exchange process in complex
3a as compared with those in 1a and 2a; a bidentate
coordination fashion of the dmphen ligand is unfavorable
because of the sterically demanding methyl groups of the
dmphen ligand (vide supra). Therefore, we prefer a
mechanism involving intermediates in which the initially
unidentate nitrogen ligand is bound as a bidentate, i.e.
mechanism B1.
Acknowledgements
This work was supported by The Netherlands Founda-
tion for Chemical Research (SON) with financial support
from The Netherlands Organisation for Scientific Re-
search (NWO).
References
[1] W.A. Herrmann, B. Cornils, Angew. Chem. Int. Ed. Engl. 36
(1997) 1049.
[2] E. Drent, Pure Appl. Chem. 62 (1990) 661.
[3] G.W. Parshall, S.D. Ittel, Homogeneous Catalysis, 2nd edn,
Wiley, New York, 1992.
[4] E. Drent, Eur. Pat. Appl. 1986, 0229408; Chem. Abstr 108
(1988) 6617b.
[5] E. Drent, Neth. Appl. 1986, 86/1199; Chem. Abstr. 108 (1988)
168148b.
[6] E. Drent, Neth. Appl. 1986, 86/2595; Chem. Abstr. 109 (1988)
171100f.
3.7. Norbornadiene insertion in complexes 1b–4b
The reaction of the acetylpalladium complexes 1b–4b
with norbornadiene led to insertion of the alkene into the
acetyl–palladium bond, resulting in formation of the
alkylpalladium complexes [Pd(C7H8C(O)Me)(p-An-
BIAN)]SO3CF3 (1c) [13], [Pd(C7H8C(O)Me)(phen)]SO3-
CF3 (2c) [30], 1c [13], and [Pd(C7H8C(O)Me)(dppe)]SO3-
CF3 (4c) [31] together with the free nitrogen ligands
p-An-BIAN, p-An-BIAN, dmphen and p-An-BIAN,
respectively (Equation 3).
The reactions of complexes 1b, 2b, and 4b with
norbornadiene occurred within 5 min, showing rates
comparable with those found for the neutral complexes
Pd(C(O)Me)Cl(Ar-BIAN [13,24], but the rates were lower
[7] E. Drent, Eur. Pat. Appl. 1989, 315279; Chem. Abstr. 111 (1989)
233894v.
[8] E. Drent, Neth. Appl. 1989, 89/1928; Chem. Abstr. 115 (1991)
30163r.
[9] M. Barsacchi, G. Consiglio, L. Medici, G. Petrucci, U.W. Suter,
Angew. Chem. Int. Ed. Engl. 30 (1991) 989.
[10] M. Brookhart, F.C. Rix, J.M. DeSimone, J.C. Barborak, J. Am.
Chem. Soc. 114 (1992) 5894.
[11] A. Sen, Z. Jiang, Macromolecules 26 (1993) 911.
[12] S. Bartolini, C. Carfagna, A. Musco, Macromol. Rapid Com-
mun. 16 (1995) 9.
[13] R. van Asselt, E.E.C.G. Gielens, R.E. Ru¨lke, K. Vrieze, C.J.
Elsevier, J. Am. Chem. Soc. 116 (1994) 977.
[14] J.H. Groen, C.J. Elsevier, K. Vrieze, W.J.J. Smeets, A.L. Spek,
Organometallics 15 (1996) 3445.

J.H. Groen et al. / Journal of Organometallic Chemistry 573 (1999) 3–13
13
[15] R.E. Ru¨lke, J.G.P. Delis, A.M. Groot, C.J. Elsevier, P.W.N.M.
van Leeuwen, K. Vrieze, K. Goubitz, H. Schenk, J. Organomet.
Chem. 508 (1996) 109.
[16] R.E. Ru¨lke, V.E. Kaasjager, D. Kliphuis, C.J. Elsevier,
P.W.N.M. van Leeuwen, K. Vrieze, K. Goubitz, Organometal-
lics 15 (1996) 668.
[35] G.M. Sheldrick, SHELXL-96. Program for Crystal Structure
Refinement; University of Go¨ttingen, Germany, 1996.
[36] A.L. Spek, Acta Crystallogr. A46 (1990) C34.
˚
[37] S. Hansson, P.-O. Norrby, M.P.T. Sjo¨gren, B. Akermark, M.E.
Cucciolito, F. Giardano, A. Vitagliano, Organometallics 12
(1993) 4940.
[17] J.H. Groen, M.J.M. Vlaar, P.W.N.M. van Leeuwen, K. Vrieze,
H. Kooijman, A.L. Spek, J. Organomet. Chem. 551 (1998) 67.
[18] J.H. Groen, A. de Zwart, M.J.M. Vlaar, P.W.N.M. van
Leeuwen, K. Vrieze, H. Kooijman, W.J.J. Smeets, A.L. Spek,
P.H.M. Budzelaar, Q. Xiang, R.P. Thummel, Eur. J. Inorg.
Chem., in press.
[38] F.P. Fanizzi, M. Lanfranchi, G. Natile, A. Tiripicchio, Inorg.
Chem. 33 (1994) 3331.
[39] F.P. Fanizzi, L. Maresca, G. Natile, M. Lanfranchi, A. Tiripic-
chio, G. Pacchioni, J. Chem. Soc. Chem. Commun. (1992) 333.
[40] A. Terzis, K.N. Raymond, T.G. Spiro, Inorg. Chem. 9 (1970)
2415.
[19] J.G.P. Delis, J.H. Groen, K. Vrieze, P.W.N.M. van Leeuwen, N.
Veldman, A.L. Spek, Organometallics 16 (1997) 551.
[20] J.G.P. Delis, P.G. Aubel, K. Vrieze, P.W.N.M. van Leeuwen, N.
Veldman, A.L. Spek, F.J.R. van Neer, Organometallics 16
(1997) 2948.
[21] B.A. Markies, P. Wijkens, J. Boersma, H. Kooijman, N. Veld-
man, A.L. Spek, G. van Koten, Organometallics 13 (1994) 3244.
[22] B.A. Markies, D. Kruis, M.H.P. Rietveld, K.A.N. Verkerk, J.
Boersma, H. Kooijman, M.T. Lakin, A.L. Spek, G. van Koten,
J. Am. Chem. Soc. 117 (1995) 5263.
[23] F.C. Rix, M. Brookhart, P.S. White, J. Am. Chem. Soc. 118
(1996) 4746.
[24] J.H. Groen, J.G.P. Delis, P.W.N.M. van Leeuwen, K. Vrieze,
Organometallics 16 (1997) 68.
[25] R. van Asselt, C.J. Elsevier, W.J.J. Smeets, A.L. Spek, R.
Benedix, Recl. Trav. Chim. Pays-Bas 113 (1994) 88.
[26] G.P.C.M. Dekker, C.J. Elsevier, K. Vrieze, P.W.N.M. van
Leeuwen, Organometallics 11 (1992) 1598.
[27] R.E. Hurd, B.K. John, J. Magn. Reson. 91 (1991) 648.
[28] J. Ruiz-Cabello, G.W. Vuister, C.T.W. Moonen, P. van
Gelderen, J.S. Cohen, P.C.M. van Zijl, J. Magn. Reson. 100
(1992) 282.
[41] J.W. Collier, F.G. Mann, D.G. Watson, H.R. Watson, J. Chem.
Soc. (1964) 1803.
[42] T.G. Appleton, H.C. Clark, L.E. Manzer, Coord. Chem. Rev. 10
(1973) 335.
[43] V. De Felice, V.G. Albano, C. Castellari, M.E. Cucciolito, A. De
Renzi, J. Organomet. Chem. 403 (1991) 269.
[44] J.G.P. Delis, P.W.N.M. van Leeuwen, K. Vrieze, N. Veldman,
A.L. Spek, J. Fraanje, K. Goubitz, J. Organomet. Chem. 514
(1996) 125.
[45] J.G.P. Delis, M. Rep, R.E. Ru¨lke, P.W.N.M. van Leeuwen, K.
Vrieze, J. Fraanje, K. Goubitz, Inorg. Chim. Acta 250 (1996) 87.
[46] J.-M. Ernsting, J.H. Groen, C.J. Elsevier, to be published.
[47] P.S. Pregosin, R. Ru¨edi, C. Anklin, Magn. Reson. Chem. 24
(1986) 255.
[48] R.E. Ru¨lke, J.M. Ernsting, C.J. Elsevier, A.L. Spek, P.W.N.M.
van Leeuwen, K. Vrieze, Inorg. Chem. 32 (1993) 5769.
[49] The observations that (i) tmeda (N,N,N%,N%-tetramethylethylene-
diamine) in Pd(Me)Cl(tmeda) can be substituted by phen, but
not by p-An-BIAN [30] and (ii) addition of one equivalent of
isocyanide to Pd(Me)Cl(NꢀN) results in substitution of NꢀN for
p-An-BIAN, but not for phen [20] indicate that the |-coordinat-
ing ability of phen is larger than that of p-An-BIAN.
[50] F.P. Fanizzi, F.P. Intini, L. Maresca, G. Natile, M. Lanfranchi,
A. Tiripicchio, J. Chem. Soc. Dalton Trans. (1991) 1007.
[51] I. To´th, C.J. Elsevier, J. Am. Chem. Soc. 115 (1993) 10388.
[52] P.W.N.M. van Leeuwen, C.F. Roobeek, H. van der Heijden, J.
Am. Chem. Soc. 116 (1994) 12117.
[29] W. Wilker, D. Leibfritz, W. Kerssebaum, W. Bermel, Magn.
Reson. Chem. 31 (1993) 287.
[30] J.H. Groen, P.W.N.M. van Leeuwen, K. Vrieze, unpublished
results.
[31] G.P.C.M. Dekker, C.J. Elsevier, K. Vrieze, P.W.N.M. van
Leeuwen, C.F. Roobeek, J. Organomet. Chem. 430 (1992) 357.
[32] J.L. de Boer, A.J.M. Duisenberg, Acta Crystallogr. A40 (1984)
C410.
[53] P.W.N.M. van Leeuwen, K.F. Roobeek, Recl. Trav. Chim.
Pays-Bas 114 (1995) 73.
[54] H.F. Haarman, F.R. Bregman, J.-M. Ernsting, N. Veldman,
A.L. Spek, K. Vrieze, Organometallics 16 (1997) 54.
[55] K.R. Dixon, Inorg. Chem. 16 (1977) 2618.
[56] R. Romeo, Comments Inorg. Chem. 11 (1990) 21, and references
therein.
[33] A.L. Spek, J. Appl. Crystallogr. 21 (1988) 578.
[34] P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, S.
Garcia-Granda, R.O. Gould, J.M.M. Smits, C. Smykalla, The
DIRDIF-96 Program System. Tech. Rep. Crystallography Labo-
ratory, University of Nijmegen, The Netherlands, 1996.