Stepwise successive insertion of carbon monoxide and allenes into palladium-carbon bonds of complexes containing the rigid bidentate nitrogen ligand bis(p-anisylimino)acenaphthene

Article abstract of DOI:10.1021/om960163p

Propadiene, 3-methyl-1,2-butadiene (DMA), and 2,4-dimethyl-2,3-pentadiene (TMA) reacted via migratory insertion with both neutral and ionic Pd(R)X(p-An-BIAN) (R = Me (1), C(O)-Me (2); X = Cl (a), SO₃CF₃ (b)) complexes, containing the

Full text of DOI:10.1021/om960163p

Organometallics 1996, 15, 3445-3455
3445
Step w ise Su ccessive In ser tion of Ca r bon Mon oxid e a n d
Allen es in to P a lla d iu m -Ca r bon Bon d s of Com p lexes
Con ta in in g th e Rigid Bid en ta te Nitr ogen Liga n d
Bis(p-a n isylim in o)a cen a p h th en e
J ohannes H. Groen, Cornelis J . Elsevier, and Kees Vrieze*
Anorganisch Chemisch Laboratorium, J . H. van ’t Hoff Research Instituut, Universiteit van
Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands
Wilberth J . J . Smeets and Anthony L. Spek†
Bijvoet Centre for Biomolecular Research, Laboratorium voor Kristal- en Structuurchemie,
Universiteit Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands
Received March 5, 1996X
Propadiene, 3-methyl-1,2-butadiene (DMA), and 2,4-dimethyl-2,3-pentadiene (TMA) reacted
via migratory insertion with both neutral and ionic Pd(R)X(p-An-BIAN) (R ) Me (1), C(O)-
Me (2); X ) Cl (a ), SO3CF3 (b)) complexes, containing the rigid nitrogen ligand bis(p-
anisylimino)acenaphthene (p-An-BIAN), resulting in the novel and stable allylpalladium
complexes Pd(η3-C3H4R)X(p-An-BIAN) (R ) Me (3), C(O)Me (6)), Pd(η3-C5H8R)X(p-An-BIAN)
(R ) Me (4), C(O)Me (7)), and Pd(η3-C7H12R)X(p-An-BIAN) (R ) Me (5), C(O)Me (8)),
respectively (X ) Cl (a ), SO3CF3 (b)). The neutral complexes 6a and 7a reacted with carbon
monoxide to form the acylpalladium complexes Pd(C(O)C3H4C(O)Me)Cl(p-An-BIAN) (9) and
Pd(C(O)C5H8C(O)Me)Cl(p-An-BIAN) (10), respectively, while the analogous trifluoromethane-
sulfonate complexes 6b and 7b were completely inert toward CO. Complexes 9 and 10
reacted again with propadiene and DMA, respectively, to yield the allylpalladium complexes
Pd(η3-C3H4C(O)C3H4C(O)Me)Cl(p-An-BIAN) (11) and Pd(η3-C5H8C(O)C5H8C(O)Me)Cl(p-An-
BIAN) (12), respectively. Also insertion of norbornadiene in complex 10 was possible, yielding
the ionic complex [Pd(C7H8C(O)C5H8C(O)Me)(p-An-BIAN)]Cl (13a ), which reacted with
AgSO3CF3 to give [Pd(C7H8C(O)C5H8C(O)Me)(p-An-BIAN)]SO3CF3 (13b). The novel com-
plexes 9-12 are the first isolated and fully characterized complexes formed by successive
insertion reactions of carbon monoxide and allenes, while 13a is the first isolated complex
containing a metal-bonded ter-oligomer of carbon monoxide, an allene, and norbornadiene.
The X-ray crystal structure of 7a has been determined and shows a distorted square
pyramidal geometry in which the BIAN ligand is bonded to the palladium center in an
unusual asymmetric fashion (Pd-N(1) ) 2.144(7) Å; Pd-N(2) ) 2.600(8) Å).
In tr od u ction
of polyketones.6-14 The most favored mechanism of this
copolymerization proceeds via successive stepwise inser-
tion reactions of carbon monoxide and the alkene into
palladium-carbon bonds. To explain the sometimes
observed formation of spiroketals, Consiglio et al. pro-
posed an alternative mechanism involving palladium-
carbene intermediates,10 but very recently Sen et al.
showed that spiroketals can be formed from polyke-
tones.13
Although much is known about the CO/alkene
copolymerization,6-13 relatively little is known about the
alternating insertion of CO and alkenes on a metal
center. Elegant work of Brookhart et al. has resulted
in the in situ characterization of acyl complexes of the
The insertion of unsaturated molecules like carbon
monoxide, alkenes, alkynes, and allenes into metal-
carbon bonds is a very important step in many transi-
tion metal catalyzed processes.1-4 Two very interesting,
recently developed examples in which a palladium-
based catalyst is used are the alkoxy carbonylation of
alkynes5 and in particular the copolymerization of
carbon monoxide and alkenes, resulting in the formation
* To whom correspondence should be addressed.
† To whom correspondence concerning crystallographic data should
be addressed.
X Abstract published in Advance ACS Abstracts, J uly 1, 1996.
(1) Yamamoto, A. Organotransition Metal Chemistry; Wiley: New
York, 1986.
(6) Drent, E.; van Broekhoven, J . A. M.; Doyle, M. J . J . Organomet.
Chem. 1991, 417, 235.
(7) Sen, A.; Lai, T.-W. J . Am. Chem. Soc. 1982, 104, 3520.
(8) Lai, T.-W.; Sen, A. Organometallics 1984, 3, 866.
(9) Sen, A. Acc. Chem. Res. 1993, 26, 303.
(10) Batistini, A.; Consiglio, G. Organometallics 1992, 11, 1766.
(11) Brookhart, M.; Rix, F. C.; DeSimone, J . M.; Barborak, J . C. J .
Am. Chem. Soc. 1992, 114, 5894.
(12) Bartolini, S.; Carfagna, C.; Musco, A. Macromol. Rapid Com-
mun. 1995, 16, 9.
(2) Tkatchenko, I. In Comprehensive Organometallic Chemistry;
Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon Press:
Oxford, 1982; Vol. 8.
(3) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987.
(4) Cazes, B. Pure Appl. Chem. 1990, 62, 1867.
(5) Drent, E.; Arnoldy, P.; Budzelaar, P. H. M. J . Organomet. Chem.
1993, 455, 247.
(13) J iang, Z.; Sen, A. J . Am. Chem. Soc. 1995, 117, 4455.
(14) Drent, E.; Budzelaar, P. H. M. Chem. Rev. 1996, 96, 663.
S0276-7333(96)00163-X CCC: $12.00 © 1996 American Chemical Society
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3446 Organometallics, Vol. 15, No. 15, 1996
Groen et al.
without further purification. p-An-BIAN24 and Pd(R)X(p-An-
BIAN) (R ) Me (1), C(O)Me (2); X ) Cl (a ), SO3CF3 (b))19 were
prepared according to the literature. The allylpalladium
dimers [Pd(η3-C3H4R)Cl]2, [Pd(η3-C5H8R)Cl]2, and [Pd(η3-
C7H12R)Cl]2 were prepared by the reaction of Pd(R)Cl(COD)
(R ) Me, C(O)Me; COD ) 1,5-cyclooctadiene) with propadiene,
3-methyl-1,2-butadiene (dimethylallene, DMA), and 2,4-di-
methyl-2,3-pentadiene (tetramethylallene, TMA), respec-
tively.25 All other starting chemicals were used as com-
mercially obtained. Silver trifluoromethanesulfonate was
stored under nitrogen in the dark. 1H and 13C NMR spectra
were recorded on a Bruker AMX 300 spectrometer (300.13 and
75.48 MHz, respectively). Chemical shifts are in ppm relative
to TMS as external standard. 19F NMR spectra were recorded
on a Bruker AC 100 spectrometer (94.20 MHz) at 20 °C,
relative to CFCl3 as external standard. IR spectra were
obtained on a Bio-Rad FTS-7 spectrophotometer. Elemental
analyses were carried out by Dornis und Kolbe, Mikroana-
lytisches Laboratorium, Mu¨lheim a.d. Ruhr, Germany.
Neu tr a l Allylp a lla d iu m Com p lexes 3a -8a . Meth od A.
Propadiene was bubbled for 1 min through a solution of Pd-
(Me)Cl(p-An-BIAN) (1a ) (219.7 mg, 0.40 mmol) in 25 mL of
dichloromethane. In the case of DMA and TMA 0.44 mmol
(1.1 equiv) was added. After being stirred at 20 °C for 16 h in
the case of propadiene and DMA and for 3 days in the case of
TMA the dark red solution was evaporated to dryness and the
product was washed with diethyl ether (2 × 20 mL) and dried
in vacuo. The products could be isolated in high yields (88-
97%).
In the same way were synthesized by the reaction of Pd-
(C(O)Me)Cl(p-An-BIAN) (2a ) with propadiene, DMA, and TMA
(reaction times and yields in parentheses) Pd(η3-C3H4C(O)Me)-
Cl(p-An-BIAN) (6a , 15 min, 95%), Pd(η3-C5H8C(O)Me)Cl(p-An-
BIAN) (7a , 15 min, 90%), and Pd(η3-C7H12C(O)Me)Cl(p-An-
BIAN) (8a , 16 h, 87%), respectively.
Meth od B. To a solution of [Pd(η3-C3H4Me)Cl]2 (39.4 mg,
0.10 mmol) in 20 mL of dichloromethane was added p-An-
BIAN (86.3 mg, 0.22 mmol). After being stirred at 20 °C for
5 min, the solution was evaporated and the residue was
washed with diethyl ether (2 × 20 mL) and dried in vacuo,
resulting in Pd(η3-C3H4Me)Cl(p-An-BIAN) (3a ) (0.18 mmol,
90%).
type [Pd(C(O)[CH(Ar)CH2C(O)]nMe)(bpy)(CO)]BAr4 (n
) 1-3), formed via successive insertion of CO and 4-tert-
butyl styrene into ionic acylpalladium complexes.11
Very recently Brookhart also succeeded in the in situ
characterization of [Pd(C(O)Me)(phen)(C2H4)]BAr4 and
[Pd(Me)(phen)(CO)]BAr4, two believed key intermedi-
ates in the palladium(II) mediated CO/ethene copolym-
erization.15 Boersma et al. reported a sequential inser-
tion of CO and norbornene, starting from the neutral
methyl complex Pd(Me)X(bpy) (X ) I, Cl).16,17 However,
varying the anion with each step was required to
accomplish this sequential insertion. Elsevier et al.
reported a sequential insertion of CO and norborna-
diene, also starting from a neutral palladium methyl
complex but without the need of varying the anion. By
starting from the complex Pd(Me)Cl(p-An-BIAN), bear-
ing the rigid bidentate nitrogen ligand bis(p-anisylimi-
no)acenaphthene (p-An-BIAN), metal-bonded co-oligo-
mers up to [Pd(C7H8C(O)C7H8C(O)Me)(p-An-BIAN)]Cl
could be isolated and fully characterized.18,19 The
stability and reactivity of the acyl- and alkylpalladium
intermediates were attributed to the rigidity of the
BIAN ligand, which is able to stabilize otherwise labile
organometallic intermediates.20
At this point, we wanted to study whether the
stability and reactivity of complexes containing the
BIAN ligand would also facilitate co-oligomerization of
CO and other unsaturated molecules than strained
alkenes. We have chosen to turn our attention to
allenes, since it is known that R-diimine ligand contain-
ing palladium complexes are able to catalyze the copo-
lymerization of allenes and CO.21 Furthermore, it has
been shown very recently that the electrophilic central
carbon atom of allenes reacts in a fast and clean fashion
with the nucleophilic R group of complexes of the type
Pd(R)X(L) (R ) alkyl, acyl; X ) Cl, Br, BF4; L )
bidentate, tridentate nitrogen ligand).22,23 Here we
describe the isolation and full characterization of novel
acyl-, allyl-, and alkylpalladium complexes, formed after
successive CO, allene, and norbornadiene insertions,
respectively.
Complexes 4a -8a were synthesized from the corresponding
allylpalladium dimers in the same way (86-92%).
3a . MS: found, m/ z ) 554 (calcd for C30H27N2O2Pd, 554).
No correct microanalysis was obtained, probably due to the
presence of a small amount of [Pd(η3-C3H4Me)Cl]2.
4a . Anal. Found (calcd for C32H31ClN2O2Pd): C, 62.01
(62.25); H, 5.05 (5.06); N, 4.49 (4.54).
Exp er im en ta l Section
5a . Anal. Found (calcd for C34H35ClN2O2Pd): C, 62.95
(63.26); H, 5.47 (5.47); N, 4.40 (4.34).
Gen er a l Com m en ts. All manipulations were carried out
in an atmosphere of purified dry nitrogen by using standard
Schlenk techniques. Solvents were dried and stored under
nitrogen. Carbon monoxide 99.5% was purchased from Hoek-
Loos and propadiene from Air Products, which were used
6a . IR (KBr): 1692 cm-1, ν(CO). Anal. Found (calcd for
C
31H27ClN2O3Pd): C, 60.18 (60.30); H, 4.35 (4.41); N, 4.62
(4.54).
7a . IR (KBr): 1690 cm-1, ν(CO). Anal. Found (calcd for
33H31ClN2O3Pd): C, 61.26 (61.40); H, 4.83 (4.84); N, 4.38
(4.34).
8a . IR (KBr): 1700 cm-1, ν(CO). MS: found, m/ z ) 638
C
(15) Rix, F. C.; Brookhart, M. J . Am. Chem. Soc. 1995, 117, 1137.
(16) Markies, B. A.; Verkerk, K. A. N.; Rietveld, M. H. P.; Boersma,
J .; Kooijman, H.; Spek, A. L.; van Koten, G. J . Chem. Soc., Chem.
Commun. 1993, 1317.
(17) Markies, B. A.; Kruis, D.; Rietveld, M. H. P.; Verkerk, K. A.
N.; Boersma, J .; Kooijman, H.; Lakin, M. T.; Spek, A. L.; van Koten,
G. J . Am. Chem. Soc. 1995, 117, 5263.
(calcd for C35H35N2O3Pd, 638). No correct microanalysis was
obtained, probably due to the presence of a small amount of
[Pd(η3-C7H12C(O)Me)Cl]2.
(18) van Asselt, R.; Gielens, E. E. C. G.; Ru¨lke, R. E.; Elsevier, C. J .
J . Chem. Soc., Chem. Commun. 1993, 1203.
(19) van Asselt, R.; Gielens, E. E. C. G.; Ru¨lke, R. E.; Vrieze, K.;
Elsevier, C. J . J . Am. Chem. Soc. 1994, 116, 977.
(20) van Asselt, R.; Rijnberg, E.; Elsevier, C. J . Organometallics
1994, 13, 706.
(21) Drent, E. Neth. Appl. 1988, 88/1168; Chem. Abstr. 1990, 113,
24686f.
(22) Ru¨lke, R. E.; Kliphuis, D.; Elsevier, C. J .; Fraanje, J .; Goubitz,
K.; van Leeuwen, P. W. N. M.; Vrieze, K. J . Chem. Soc., Chem.
Commun. 1994, 1817.
Ion ic Allylp a lla d iu m Com p lexes 3b-8b. Meth od A. To
a solution of Pd(Me)Cl(p-An-BIAN) (1a ) (82.4 mg, 0.15 mmol)
in a mixture of 20 mL of dichloromethane and 1 mL of
acetonitrile was added AgSO3CF3 (43.7 mg, 0.17 mmol). After
the solution was stirred for 1 min in the dark at 20 °C
propadiene was bubbled through for 1 min or in the case of
DMA and TMA 0.17 mmol (1.1 equiv) was added. After being
(24) van Asselt, R.; Elsevier, C. J .; Smeets, W. J . J .; Spek, A. L.;
Benedix, R. Recl. Trav. Chim. Pays-Bas 1994, 113, 88.
(25) Ankersmit, H. A.; Veldman, N.; Spek, A. L.; Eriksen, K.;
Goubitz, K.; Vrieze, K.; van Koten, G. Inorg. Chim. Acta, in press.
(23) Ru¨lke, R. E. Insertion Reactions with Novel Palladium Com-
plexes; Dutch PhD Thesis; University of Amsterdam: Amsterdam, The
Netherlands, 1995; pp 103-128.
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Insertion of CO and Allenes into Pd-C Bonds
Organometallics, Vol. 15, No. 15, 1996 3447
stirred for 10 min in the dark at 20 °C, the red solution was
evaporated to dryness. After addition of 20 mL of dichlo-
romethane the solution was filtered through Celite filter aid.
The residue was extracted with dichloromethane (5 mL), and
the combined filtrates were evaporated to dryness. The
product was washed with diethyl ether (2 × 20 mL) and dried
in vacuo, giving 3b-5b in yields varying from 65 to 85%.
Meth od B. To a solution of [Pd(η3-C3H4Me)Cl]2 (24.4 mg,
0.062 mmol) in a mixture of 25 mL of dichloromethane and 1
mL of acetonitrile were added AgSO3CF3 (36.0 mg, 0.14 mmol)
and p-An-BIAN (54.9 mg, 0.14 mmol). After being stirred for
15 min in the dark at 20 °C, the solution was evaporated to
dryness. After addition of 20 mL of dichloromethane the
solution was filtered through Celite filter aid. The residue was
extracted with dichloromethane (5 mL), and the combined
filtrates were evaporated to dryness. The residue was washed
with diethyl ether (2 × 20 mL) and dried in vacuo, giving [Pd-
(η3-C3H4Me)(p-An-BIAN)]SO3CF3 (3b) (0.11 mmol, 85%).
P d (C(O)C5H8C(O)Me)Cl(p-An -BIAN) (10) was obtained
from Pd(η3-C5H8C(O)Me)Cl(p-An-BIAN) (7a ) in the same way
by using 25 bar of CO (83%). IR (KBr): 1699, 1677 cm-1
,
ν(CO). Anal. Found (calcd for C34H31ClN2O4Pd): C, 60.51
(60.63); H, 4.61 (4.64); N, 4.21 (4.16).
P d (η3-C3H 4C(O)C3H 4C(O)Me)Cl(p -An -BIAN)
(11).
Through a solution of Pd(C(O)C3H4C(O)Me)Cl(p-An-BIAN) (9)
(42.7 mg, 0.066 mmol) in 25 mL of dichloromethane, propa-
diene was bubbled for 1 min. After being stirred at 20 °C for
15 min, the dark red solution was evaporated to dryness and
the product was washed with diethyl ether (2 × 20 mL). After
being dried in vacuo, a red solid was obtained (0.050 mmol,
76%). IR (KBr): 1696, 1675 cm-1, ν(CO). Anal. Found (calcd
for C35H31ClN2O4Pd‚CH2Cl2): C, 56.79 (56.12); H, 4.51 (4.32);
N, 3.74 (3.64).
P d (η3-C5H8C(O)C5H8C(O)Me)Cl(p-An -BIAN) (12) was
obtained from Pd(C(O)C5H8C(O)Me)Cl(p-An-BIAN) (10) in the
same way (83%). IR (KBr): 1700, 1685 cm-1, ν(CO). Anal.
Found (calcd for C39H39ClN2O4Pd): C, 62.74 (63.16); H, 5.45
(5.30); N, 3.89 (3.78).
Complexes 4b (70%) and 5b (76%) were synthesized from
the corresponding allylpalladium dimers in the same way.
[P d (C7H8C(O)C5H8C(O)Me)(p-An -BIAN)]Cl (13a ). Nor-
bornadiene (2.5 µL, 0.024 mmol) was added to a solution of
Pd(C(O)C5H8C(O)Me)Cl(p-An-BIAN) (10) (15.3 mg, 0.023 mmol)
in 20 mL of chloroform at 20 °C. After 30 min the solution
was evaporated to dryness and the product was washed with
diethyl ether (2 × 20 mL) and dried in vacuo, giving a red
product (0.015 mmol, 67%), which was too unstable in the solid
state to allow outside microanalysis. IR (KBr): 1605 cm-1 (br),
ν(CO).
Meth od C. To a solution of 3a -5a (0.05 mmol) in a mixture
of 25 mL of dichloromethane and 1 mL of acetonitrile was
added AgSO3CF3 (0.06 mmol, 1.2 eq.). After being stirred for
10 min in the dark at 20 °C, the solution was evaporated to
dryness. After addition of 20 mL dichloromethane the solution
was filtered through Celite filter aid. The residue was
extracted with dichloromethane (5 mL), and the combined
filtrates were evaporated to dryness. The product was washed
with diethyl ether (2 × 20 mL) and dried in vacuo, giving 3b-
5b in virtually quantitative yields.
With the same methods [Pd(η3-C3H4C(O)Me)(p-An-BIAN)]-
SO3CF3 (6b), [Pd(η3-C5H8C(O)Me)(p-An-BIAN)]SO3CF3 (7b),
and [Pd(η3-C7H12C(O)Me)(p-An-BIAN)]SO3CF3 (8b) were syn-
thesized.
[P d (C7H8C(O)C5H8C(O)Me)(p-An -BIAN)]SO3CF 3 (13b).
To a solution of [Pd(C7H8C(O)C5H8C(O)Me)(p-An-BIAN)]Cl
(13a ) (23.0 mg, 0.030 mmol) in a mixture of 20 mL of
dichloromethane and 1 mL of acetonitrile was added AgSO3-
CF3 (8.5 mg, 0.033 mmol), and the mixture was stirred in the
dark at 20 °C. After 15 min, the mixture was evaporated to
dryness. After addition of 20 mL of dichloromethane the
solution was filtered through Celite aid and the residue was
extracted with dichloromethane (5 mL). The combined fil-
trates were evaporated to dryness and the product was washed
with diethyl ether (2 × 20 mL) and dried in vacuo, yielding a
dark red product (0.017 mmol, 57%). IR (KBr): 1600 cm-1
(br), ν(CO); 1252, 1155, 1031, 637 cm-1, ν(SO3CF3). 19F
NMR (CDCl3): -78.5 ppm. Anal. Found (calcd for
3b. IR (KBr): 1265, 1152, 1032, 638 cm-1, ν(SO3CF3). 19F
NMR (CDCl3): -78.5 ppm. Anal. Found (calcd for
C
31H27F3N2O5PdS): C, 52.75 (52.96); H, 3.95 (3.87); N, 4.04
(3.98).
4b. IR (KBr): 1269, 1151, 1031, 637 cm-1, ν(SO3CF3). 19F
NMR (CDCl3): -78.6 ppm. Anal. Found (calcd for
33H31F3N2O5PdS): C, 54.08 (54.21); H, 4.35 (4.28); N, 3.88
(3.83).
5b. IR (KBr): 1263, 1165, 1030, 638 cm-1, ν(SO3CF3). 19F
NMR (CDCl3): -78.3 ppm. Anal. Found (calcd for
35H35F3N2O5PdS): C, 55.26 (55.38); H, 4.74 (4.65); N, 3.58
(3.69).
C
C
42H39F3N2O7PdS.1.5CH2Cl2): C, 51.86 (51.90); H, 4.29 (4.21);
N, 2.77 (2.78).
C
Str u ctu r e Deter m in a tion a n d Refin em en t of 7a . A red
rod-shaped crystal of 7a was mounted on top of a glass fiber
(using the inert-oil technique) and transferred to the cold
nitrogen stream of an Enraf-Nonius CAD4T diffractometer for
data collection at 150 K (rotating anode, 60 kV, 100 mA,
monochromated Mo KR radiation, ω-scan mode). Unit cell
parameters were determined from a least-squares treatment
of the SET4 setting angles of 25 reflections with 9.92 < θ <
13.83°. The unit cell parameters were checked for the presence
of higher lattice symmetry.26 A total of 5476 reflections were
collected and merged into an unique dataset of 4988 reflec-
tions. Data were collected for Lp, for a linear decay (8.8%) of
the three intensity control reflections during the 14.5 h of X-ray
exposure time, and for absorption (using the DIFABS27 method;
correction range 0.665-1.302). The structure was solved with
Patterson methods (DIRDIF28) and subsequent difference
Fourier analyses. Refinement on F2 with all unique reflections
was carried out by full-matrix least-squares techniques. The
dichloromethane solvate molecule is disordered over two
locations in a 0.105(5):0.895(5) ratio. Hydrogen atoms were
introduced on calculated positions and included in the refine-
6b. IR (KBr): 1701 cm-1, ν(CO); 1252, 1153, 1030, 637 cm-1
,
ν(SO3CF3). 19F NMR (CDCl3): -78.6 ppm. Anal. Found
(calcd for C32H27F3N2O6PdS): C, 52.42 (52.58); H, 3.88 (3.73);
N, 3.94 (3.83).
7b. IR (KBr): 1701 cm-1, ν(CO); 1263, 1152, 1030, 637 cm-1
,
ν(SO3CF3). 19F NMR (CDCl3): -78.7 ppm. Anal. Found
(calcd for C34H31F3N2O6PdS): C, 54.02 (53.80); H, 4.12 (4.12);
N, 3.73 (3.69).
8b. IR (KBr): 1707 cm-1, ν(CO); 1264, 1155, 1031, 638 cm-1
,
ν(SO3CF3). 19F NMR (CDCl3): -78.7 ppm. Anal. Found
(calcd for C36H35F3N2O6PdS): C, 54.78 (54.93); H, 4.55 (4.48);
N, 3.59 (3.56).
P d (C(O)C3H4C(O)Me)Cl(p-An -BIAN) (9). A solution of
Pd(η3-C3H4C(O)Me)Cl(p-An-BIAN) (6a ) (168.2 mg, 0.26 mmol)
in 20 mL of dichloromethane was brought into a 100 mL
stainless-steel autoclave, and CO was introduced up to 50 bar.
After the solution was stirred at 20 °C for 2 h, the pressure
was released and the solution was filtered through Celite filter
aid. The residue was extracted with dichloromethane (5 mL),
and the combined filtrates were evaporated to dryness. The
product was washed with diethyl ether (2 × 20 mL) and dried
in vacuo, yielding a dark brown product (0.24 mmol, 93%). IR
(KBr): 1701, 1686 cm-1, ν(CO). Anal. Found (calcd for
(26) Spek, A. L. J . Appl. Crystallogr. 1988, 21, 578.
(27) Walker, N.; Stuart, D. Acta Crystallogr. 1983, A39, 158.
(28) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF Program System. Technical report of the Crystallography
Laboratory; University of Nijmegen: Nijmegen, The Netherlands, 1992.
C
32H27ClN2O4Pd): C, 59.38 (59.55); H, 4.41 (4.22); N, 4.30
(4.34).
+
+

3448 Organometallics, Vol. 15, No. 15, 1996
Groen et al.
Ta ble 1. Cr ysta l a n d Refin em en t Da ta for
Sch em e 1
P d (η3-C5H8C(O)Me)Cl(p-An -BIAN) (7a )
(a) Crystal Data
formula
Mr
C33H31ClN2O3Pd‚CH2Cl2
730.43
cryst system
space group
a-c (Å)
â (deg)
V (Å3)
monoclinic
P21/c (No. 14)
16.3463(9), 10.8381(8), 19.609(2)
114.19(1)
3169.1(5)
Z
D
4
calcd (g‚cm-3
)
1.531
1488
8.8
F(000)
µ (cm-1)
cryst size (mm)
0.10 × 0.13 × 0.42
(b) Data Collection
θ
min, θmax
1.14, 24.00
radiation
Mo KR (graphite-monochrom),
0.710 73 Å
∆ω (deg)
0.83 + 0.35 tan θ
3.00 + 1.50 tan θ, 4.00
hor and vert
aperture (mm)
ref reflns
2h1h6, 3h2h1h, 4h0h2h
h, -18 to 17; k, -12 to 0;
l, -22 to 0
data set
tot. data
5476
tot. unique data
obsd data
4988
4557 [Fo2 > -1.0σ(Fo2)]
(c) Refinement
no. of reflns and params
weighting scheme
final R1, wR2, S
(∆/σ)av and max in
final cycle
4557, 421
in the case of the ionic complexes 1b and 2b allene
insertion resulted in ionic allylpalladium complexes. In
contrast, allene insertion into the Pd-R bond of the
complexes 1a and 2a resulted in the formation of
neutral allylpalladium complexes (Scheme 1).
w ) 1.0/[σ2(Fo2) + (0.0395P)2]
0.0689, 0.1287, 0.992
0.000, 0.003
ment riding on their carrier atoms. All non-hydrogen atoms,
except the minor disorder chloride atoms, were refined with
anisotropic thermal parameters; hydrogen atoms with isotropic
thermal parameters related to the Ueq of the carrier atoms.
Weights were introduced in the final refinement cycles;
convergence was reached at R1 ) 0.0689 and wR2 ) 0.1287.
A final difference Fourier analysis shows no features outside
the range -0.51 to 0.61 e/Å3. Crystal data and numerical
details of the structure determination are given in Table 1.
Neutral atom scattering factors and anomalous dispersion
factors were taken from the ref 29. All calculations were
performed with SHELXL9330 and the PLATON31 package
(geometrical calculations and illustrations) on a DEC-5000
cluster.
Reaction with propadiene, 3-methyl-1,2-butadiene
(dimethylallene, DMA), and 2,4-dimethyl-2,3-pentadi-
ene (tetramethylallene, TMA) with 1a led to the forma-
tion of the insertion products Pd(η3-C3H4Me)Cl(p-An-
BIAN) (3a ), Pd(η3-C5H8Me)Cl(p-An-BIAN) (4a ), and
Pd(η3-C7H12Me)Cl(p-An-BIAN) (5a ), respectively. Com-
plexes 3a and 4a were formed in high yields within 16
h, and complex 5a was formed within 72 h. The
reactions of propadiene and DMA with 2a were much
faster compared to the reactions of these allenes with
1a . The allene insertion products Pd(η3-C3H4C(O)Me)-
Cl(p-An-BIAN) (6a ) and Pd(η3-C5H8C(O)Me)Cl(p-An-
BIAN) (7a ) were formed quantitatively within 2 min.
Insertion of TMA proceeded much slower, and only after
16 h a complete conversion of 2a to Pd(η3-C7H12C(O)-
Me)Cl(p-An-BIAN) (8a ) was observed. Both complexes
1b and 2b reacted instantaneously with propadiene,
DMA, and TMA to form the ionic complexes [Pd(η3-C3H4-
Me)(p-An-BIAN)]SO3CF3 (3b), [Pd(η3-C5H8Me)(p-An-
BIAN)]SO3CF3 (4b), [Pd(η3-C7H12Me)(p-An-BIAN)]SO3-
CF3 (5b), [Pd(η3-C3H4C(O)Me)(p-An-BIAN)]SO3CF3 (6b),
[Pd(η3-C5H8C(O)Me)(p-An-BIAN)]SO3CF3 (7b), and [Pd-
(η3-C7H12C(O)Me)(p-An-BIAN)]SO3CF3 (8b). All ionic
allylpalladium complexes could also be obtained in high
yields by the reaction of the corresponding halide
complexes with AgSO3CF3.
Resu lts
In ser tion of Allen es in to Alk yl- a n d Acyl-
P a lla d iu m Bon d s. The reaction of the neutral pal-
ladium complexes Pd(R)Cl(p-An-BIAN) (R ) Me (1a ),
C(O)Me (2a )) and the in situ synthesized ionic com-
plexes [Pd(R)(p-An-BIAN)NCMe]SO3CF3 (R ) Me (1b),
C(O)Me (2b)) with allenes led to insertion of the latter
into the Pd-R bond. Similar to previously reported
allene insertion reactions, the insertion takes place via
migration of the R group to the central most electro-
philic carbon atom of the allene.22,23,32-36 As expected,
(29) International Tables for Crystallography; Wilson, A. J . C., Ed.;
Kluwer Academic Publishers: Dordrecht, The Netherlands, 1992; Vol.
C.
(30) Sheldrick, G. M. SHELLXL93. Program for Crystal Structure
Refinement; University of Go¨ttingen: Go¨ttingen, Federal Republic of
Germany, 1993.
(31) Spek, A. L. Acta Crystallogr. 1990, A46, C34.
(32) Stevens, R. R.; Shier, G. D. J . Organomet. Chem. 1970, 21, 495.
(33) Chrisholm, M. H.; Clark, H. C.; Hunter, D. H. J . Chem. Soc.,
Chem. Commun. 1971, 809.
The reaction of the allylpalladium dimers [Pd(η3-
C3H4R)Cl]2, [Pd(η3-C5H8R)Cl]2, and [Pd(η3-C7H12R)Cl]2
(R ) Me, C(O)Me) with 2 equiv of p-An-BIAN also led
to the formation of the allylpalladium complexes 3a , 4a ,
5a , 6a , 7a , and 8a , respectively (Scheme 2).
(34) Chrisholm, M. H.; J ohns, W. S. Inorg. Chem. 1975, 14, 1189.
(35) Clark, H. C.; Milne, C. R. C.; Wong, C. S. J . Organomet. Chem.
1977, 136, 265.
(36) De Felice, V.; Cucciolito, M. E.; De Renzi, A.; Ruffo, F.; Tesauro,
D. J . Organomet. Chem. 1995, 493, 1.
+
+

Insertion of CO and Allenes into Pd-C Bonds
Organometallics, Vol. 15, No. 15, 1996 3449
Sch em e 2
These reactions occurred instantaneously and, as has
been described earlier for other Pd(allyl)(Ar-BIAN),37
Pd(allyl)(DAB),38 and Pd(allyl)(Pyca)39 complexes, in
some cases in solution equilibria existed. In the case
of 3a , 4a , 5a , and 8a equilibria with the corresponding
allylpalladium dimer and free p-An-BIAN were ob-
served, as could be derived from the presence of signals
F igu r e 1. ORTEP drawing (50% probability level) and
adopted numbering scheme of Pd(η3-C5H8C(O)Me)Cl(p-An-
BIAN) (7a ). Hydrogen atoms and CH2Cl2 have been omit-
ted for clarity.
1
attributable to the dimer and free p-An-BIAN in the H
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for P d (η3-C5H8C(O)Me)Cl(p-An -BIAN) (7a )
NMR spectra of 3a , 4a , 5a , and 8a (10, 13, 33, and 21%,
respectively, of the corresponding allylpalladium dimer
at 20 °C). Addition of 2 equiv of AgSO3CF3 before the
addition of 2 equiv of p-An-BIAN to the corresponding
dimer resulted in the formation of the ionic complexes
3b-8b (Scheme 2). The allylpalladium complexes 3a -
8b were as a solid as well in solution stable at 20 °C for
several weeks and were fully characterized (vide infra).
Crystals of 7a suitable for X-ray diffraction were
obtained by slow evaporation of a solution of 7a in
dichloromethane at 4 °C.
X-r a y Cr ysta l Str u ctu r e of P d (η3-C5H8C(O)Me)-
Cl(p -An -BIAN) (7a ). The molecular structure of Pd-
(η3-C5H8C(O)Me)Cl(p-An-BIAN) (7a ) with the adopted
numbering scheme is shown in Figure 1. Selected bond
distances and angles are reported in Table 2.
Bond Distances
Pd(1)-Cl(1)
Pd(1)-N(1)
Pd(1)-N(2)
Pd(1)-C(29)
Pd(1)-C(30)
Pd(1)-C(31)
C(27)-C(29)
C(28)-C(29)
C(29)-C(30)
2.405(3)
2.144(7)
2.600(8)
2.174(9)
2.060(9)
2.127(10)
1.521(14)
1.481(13)
1.425(13)
C(30)-C(31)
C(30)-C(32)
C(32)-C(33)
O(3)-C(32)
N(1)-C(5)
1.409(12)
1.510(13)
1.508(15)
1.218(12)
1.439(12)
1.272(11)
1.260(11)
1.443(12)
1.512(12)
N(1)-C(8)
N(2)-C(19)
N(2)-C(20)
C(8)-C(19)
Bond Angles
Cl(1)-Pd(1)-N(1)
N(1)-Pd(1)-C(31)
Cl(1)-Pd(1)-C(29)
N(1)-Pd(1)-N(2)
92.2(2) C(29)-C(30)-C(31) 120.3(7)
100.8(3) C(30)-C(32)-C(33) 119.8(8)
96.8(2) C(30)-C(32)-O(3)
119.4(9)
69.8(3) C(27)-C(29)-C(30) 119.3(8)
Pd(1)-C(30)-C(32) 118.1(6) C(28)-C(29)-C(30) 122.8(8)
and square pyramidal.40 An almost identical coordina-
tion fashion has been observed earlier for the 2,9-
dimethyl-1,10-phenanthroline ligand in Pd(η3-C5H9)Cl-
(dmfen)41 and Pt(CO)I2(dmfen).42 All other distances
and angles are as expected. The allyl triangle makes
an angle of 104(1)° with regard to the plane defined by
Pd(1), N(1), Cl(1), and the barycenter of the allyl
triangle, which is comparable with those found for other
R-diimine ligand containing allylpalladium complexes,
e.g. 107.3(6)° for [Pd(η3-C7H12C(O)Me)(bpy)]SO3CF3,22
106.5(8)° for Pd(η3-C5H9)Cl(dmfen),41 and 109.4° for
[Pd(η3-C3H4Me)(bpy)]SO3CF3.43 Also the palladium-
carbon distances of 2.174(9), 2.060(9), and 2.127(10) Å
The geometry of 7a can be described as distorted
square pyramidal, with the nitrogen atom N(1), the
chloride atom Cl(1), and the terminal allyl carbon atoms
C(29) and C(31) positioned on the basal sites and the
second nitrogen atom N(2) occupying the apical site. The
allyl ligand is bonded almost symmetrically to the
palladium center (2.174(9) and 2.127(10) Å for Pd(1)-
C(29) and Pd(1)-C(31), respectively). The BIAN ligand
is coordinated in an asymmetric fashion: N(1) is at
bonding distance from the palladium center (Pd(1)-N(1)
) 2.144(7) Å), while N(2) is at a nonbonding distance
(Pd(1)-N(2) ) 2.600(8) Å). Since the palladium atom
lies 0.210(1) Å above the plane defined by N(1), Cl(1),
and the barycenter of the allyl triangle, the geometry
of 7a can be seen as intermediate between square planar
(40) The distance of the palladium atom from the plane defined by
N(1), Cl(1) and the barycenter of the allyl triangle found in 7a (0.210-
(1) Å) lies in between the value for an ideal square planar geometry (0
Å) and the calculated value for an ideal square pyramidal geometry
(about 1.1 Å).
(41) Hansson, S.; Norrby, P.-O.; Sjo¨gren, M. P. T.; Åkermark, B.;
Cucciolito, M. E.; Giardano, F.; Vitagliano, A. Organometallics 1993,
12, 4940.
(42) Fanizzi, F. P.; Maresca, L.; Natile, G.; Lanfranchi, M.; Tirip-
icchio, A.; Pacchioni, G. J . Chem. Soc., Chem. Commun. 1992, 333.
(43) Albinati, A.; Kunz, R. W.; Ammann, C. J .; Pregosin, P. S.
Organometallics 1991, 10, 1800.
(37) van Asselt, R.; Vrieze, K.; Elsevier, C. J . J . Organomet. Chem.
1994, 480, 27.
(38) Crociani, B.; Boschi, T.; Uguagliati, P. Inorg. Chim. Acta 1981,
48, 9.
(39) Crociani, B.; Di Bianca, F.; Giovenco, A.; Boschi, T. Inorg. Chim.
Acta 1987, 127, 169.
+
+

3450 Organometallics, Vol. 15, No. 15, 1996
Groen et al.
for Pd(1)-C(29), Pd(1)-C(30), and Pd(1)-C(31), respec-
tively, are within the expected values for allylpalladium
complexes. The R-diimine plane of the BIAN ligand is
roughly planar (torsion angle N(1)-C(8)-C(19)-N(2) )
-2.9(12)°) and makes a dihedral angle of 83.0(5)° with
the plane defined by Pd(1), N(1), Cl(1), and the bary-
center of the allyl triangle. The angles between the
plane of the acenaphthene backbone and the aromatic
substituents on the nitrogen atoms are 77.3(4) and 77.8-
(4)°, which is larger than found for free p-Tol-BIAN (55-
60°)24 but smaller than the angles observed for Pd(Me)-
Cl(o,o′-iPr2C6H3-BIAN) (about 84°),24 in which two ortho
isopropyl substituents are present on the aromatic
groups.
decarbonylation reaction and led to the immediate
formation of 6b and 7b, respectively. In the solid state
both complexes 9 and 10 were much more stable toward
decarbonylation (no trace of complexes 6a and 7a ,
respectively, after 20 h in vacuo).
The acylpalladium complexes 9 and 10 reacted rapidly
and almost quantitatively with propadiene and DMA,
resulting in the formation of the novel allylpalladium
complexes Pd(η3-C3H4C(O)C3H4C(O)Me)Cl(p-An-BIAN)
(11) and Pd(η3-C5H8C(O)C5H8C(O)Me)Cl(p-An-BIAN)
(12), respectively (eq 2). Complexes 11 and 12 are the
first isolated and fully characterized complexes, ob-
tained via successive CO and allene insertion reactions.
Su ccessive In ser tion of CO a n d Allen es. The
reaction of complexes 6a and 7a with carbon monoxide
resulted in the insertion of CO into the allyl-palladium
bond to give the acylpalladium complexes Pd(C(O)-
C3H4C(O)Me)Cl(p-An-BIAN) (9) and Pd(C(O)C5H8C(O)-
Me)Cl(p-An-BIAN) (10), respectively (eq 1). The pres-
Complex 10 also reacted with the strained alkene
norbornadiene resulting in formation of the insertion
product [Pd(C7H8C(O)C5H8C(O)Me)(p-An-BIAN)]Cl (13a)
(eq 3). In contrast to all other performed insertion
ence of methyl substituents on the terminal allyl carbon
atoms has a remarkable influence on this CO insertion.
Thus a CO pressure of 50 bar was required for a
complete conversion of 6a , while for the conversion of
7a , which contains two methyl substituents on one
terminal allyl carbon atom, a CO pressure of 25 bar was
sufficient for a complete conversion. In contrast to 6a
and 7a , complex 8a , in which there are two methyl
substituents on each of the terminal allyl carbon atoms,
was even completely inert toward CO; after 18 h under
a CO pressure of 50 bar at 20 °C no reaction was
observed. As observed for 8a , complex 5a did not react
with CO (50 bar, 18 h). Similar to complexes 6a and
7a , complexes 3a and 4a reacted with CO to form the
CO insertion products Pd(C(O)C3H4Me)Cl(p-An-BIAN)
and Pd(C(O)C5H8Me)Cl(p-An-BIAN), respectively, but
in contrast to 6a and 7a a complete conversion was not
possible (50 and 60% conversion after 24 h under 50
bar of CO for 3a and 4a , respectively). Also because of
immediate decarbonylation upon releasing the CO pres-
sure, these CO insertion products could not be isolated
nor characterized.
The nature of the anion in the allylpalladium com-
plexes also plays an important role in the CO insertion
reaction. The ionic complexes 3b-8b did not undergo
CO insertion under 50 bar of CO at 20 °C, and only slow
decomposition resulting in palladium blackening was
observed.
The CO insertion into the allyl-palladium bond of 6a
and 7a is a reversible reaction. In solution, decarbo-
nylation of the acyl complexes 9 and 10 took place,
resulting in the re-formation of 6a and 7a , respectively,
without decomposition (complete decarbonylation after
16 h for 9 and 2 days for 10 in dichloromethane at 20
°C or within 1 h for 9 and within 2 h for 10 in refluxing
dichloromethane). Abstraction of the chloride ion from
9 and 10 by addition of AgSO3CF3 accelerated the
reactions and to the insertion reaction of norbornadiene
into the acyl-palladium bond of Pd(C(O)Me)Cl(p-An-
BIAN),19 dichloromethane is not a proper solvent for this
reaction as the insertion is very slow and unselective,
resulting in several uncharacterized norbornadiene
insertion products, together with the decarbonylation
product 7a . However, carrying out the reaction in
chloroform allowed one to obtain the desired norborna-
diene insertion product 13a quantitatively. The differ-
ence in reactivity between norbornadiene and DMA was
examined by a competition experiment. When a mix-
ture of 1 equiv of norbornadiene and 1 equiv of DMA
was added to a solution of 10 in CDCl3 at 20 °C, an
almost exclusive formation of 12 (>99%) and virtually
no formation of 13a (<1%) was observed in the 1H NMR
spectrum of the reaction solution, indicating that the
insertion reaction of norbornadiene is much slower than
the insertion of DMA in complex 10 .
Norbornadiene also reacted with complex 9 resulting
in the insertion product [Pd(C7H8C(O)C3H4C(O)Me)(p-
An-BIAN)]Cl, but because of the relative fast decarbo-
nylation of 9 only a mixture of the norbornadiene
insertion product and 6a could be obtained, while the
norbornadiene insertion product could not be isolated
nor characterized. The complex [Pd(C7H8C(O)-
C5H8C(O)Me)(p-An-BIAN)]SO3CF3 (13b) has been ob-
tained by reacting 13a with 1 equiv of AgSO3CF3.
The complexes 11, 12, and 13a all showed further
reactivity toward CO and allenes/norbornadiene, but
+
+

Insertion of CO and Allenes into Pd-C Bonds
Organometallics, Vol. 15, No. 15, 1996 3451
Ta ble 3. 1H NMR Da ta (δ) for Com p lexes 3-13a
H3
H4
H5
H9,10
H12
other signals
3a
3b
4a
4b
5a
5b
6a
6b
7a
7b
8a
8b
9c
7.22 d (7.3)
7.45 pst
8.00 d (8.3)
7.50 d (8.8),
7.06 d (8.8)
7.48 d (8.7),
7.11 d (8.7)
7.44 d (8.4),
7.07 d (8.4)
7.40 d (8.5),
7.15 d (8.5)
7.35 d (8.7),
7.12 d (8.7)
7.26 d (8.9),
7.18 d (8.9)
7.47 d (8.8),
7.04 d (8.8)
7.51 br,
7.09 d (8.8)
7.49 d (8.6),
7.03 d (8.6)
7.45 d (8.9),
7.13 d (8.9)
7.44 d (8.8),
7.06 d (8.8)
7.33 br,
7.15 d (8.6)
7.24 m,
7.00 m
7.27 m,
7.03 m
7.46 d (8.8),
7.04 d (8.8)
7.46 d (8.7),
7.03 d (8.7)
7.35 d (8.8),
7.09 d (8.8)
7.45 d (8.8),
7.08 d (8.8)
7.34 m
3.92 s
3.2 br, Hsyn,anti; 1.96 s, Me
7.29 d (7.3)
7.11 d (7.4)
b
7.53 pst
7.44 pst
7.52 pst
7.46 pst
7.52 pst
7.47 pst
7.52 pst
7.43 pst
7.52 pst
7.42 pst
7.51 pst
7.50 pst,
8.10 d (8.3)
7.99 d (8.3)
8.09 d (8.2)
8.03 d (8.3)
8.09 d (8.3)
8.00 d (8.2)
8.09 d (8.1)
7.98 d (8.3)
8.08 d (8.3)
7.97 d (8.3)
8.07 d (8.3)
3.94 s
3.92 s
3.95 s
3.93 s
3.96 s
3.91 s
3.94 s
3.90 s
3.94 s
3.91 s
3.93 s
3.86 s
3.87 s
3.91 s
3.90 s
3.93 s
3.96 s,
3.44 s, Hsyn; 3.37 s, Hanti; 2.15 s, Me
3.41 br, Hsyn; 3.30 br, Hanti; 1.91 s, Me; 1.06 s, Mesyn, 1.04 s, Meanti
3.63 s, Hsyn; 3.49 s, Hanti; 2.07 s, Me; 1.19 s, Mesyn; 0.72 s, Meanti
1.85 s, Me; 1.49 s, Mesyn; 0.98 s, Meanti
6.93 d (7.3)
6.89 d (7.3)
7.33 d (7.3)
7.26 d (7.2)
7.20 d (7.3)
7.08 d (7.3)
7.00 d (7.1)
6.88 d (7.3)
6.67 d (6.5)b
6.55 d (6.8)b
7.33 d (7.2)
7.18 d (7.3)
1.92 s, Me; 1.53 s, Mesyn; 0.83 s, Meanti
3.3 br, Hsyn,anti; 2.19 s, C(O)Me
3.93 s, Hsyn; 3.78 s, Hanti; 2.31 s, C(O)Me
3.4 br, Hsyn,anti; 2.14 s, C(O)Me; 1.23 s, Mesyn; 0.95 s, Meanti
3.84 d (2.6), Hsyn; 3.61 d (2.6), Hanti; 2.40 s, C(O)Me; 1.27 s, Mesyn
0.70 s, Meanti
2.34 s, C(O)Me; 1.49 s, Mesyn; 1.04 s, Meanti
;
2.35 s, C(O)Me; 1.57 s, Mesyn; 0.66 s, Meanti
8.08 d (7.7),
8.06 d (7.7)
8.06 d (8.4),
8.03 d (8.4)
8.00 d (8.2)
6.04 s, dCH;d 5.61 s, dCH;e 3.95 s, CH2; 2.21 s, C(O)Me
1.89 s, C(O)Me; 1.73 s, dCMe;g 1.28 s, dCMeh
7.43 pst
7.50 pst,
7.43 pst
10c,f
11
12
i
6.06 s, dCH;d 5.64 s, dCH;e 3.51 s, CH2; 3.4 br, Hsyn,anti; 2.31 s,
C(O)Me
i
7.98 d (8.3)
8.12 d (8.3)
3.57 s, CH2; 3.3 br, Hsyn,anti; 2.15 s, C(O)Me; 1.96 s, Mesyn; 1.60 s,
Meanti; 1.27 s, dCMe;g 0.96 s, dCMeh
13a f,j 7.02 d (6.2)
13bk 7.65 d (7.2),
7.52 pst
7.58 pst,
2.22 s, C(O)Me; 1.97 s, Mesyn; 1.79 s, Meanti
8.14 d (7.3),
8.11 d (7.3)
3.76 d (18.5), CHH; 3.69 d (18.5), CHH; 2.16 s, C(O)Me; 2.00 s,
dCMe;g 1.79 s, dCMeh
6.82 d (7.2)
7.51 pst
3.95 s
7.17 m
a
Recorded at 300.13 MHz in CDCl3 at 20 °C, unless noted otherwise, J (Hz) in parentheses (s ) singlet, d ) doublet, dd ) doublets of
b
doublet, pst ) pseudotriplet, m ) multiplet, br ) broad). Signal of (other) H3 is overlapping with signal of H9,10
.
c Recorded at -40 °C.
Olefinic proton cis to C(O)Me. e Olefinic proton trans to C(O)Me. f Signal of CH2 is overlapping with signal of H12
.
Me group cis to
d
g
h
i
j
C(O)Me. Me group trans to C(O)Me. Signal of H4 is overlapping with signals of H9,10
. Signals of C7H8 moiety: 5.95 dd (5.3, 2.8 Hz),
dCH; 5.56 dd (5.3, 3.2 Hz), dCH; 3.07/2.45 s, CHCd; 2.40 d (6.6 Hz), CHC(O)R; 2.07 dd (6.6, 1.5 Hz), Pd-CH; 1.82 d (9.1 Hz), CHH; 1.35
k
d (9.1 Hz), CHH. Signals of C7H8 moiety: 6.03 dd (5.4, 2.9 Hz), dCH; 5.46 dd (5.4, 3.2 Hz), dCH; 3.17/2.29 s, CHCd; 2.58 d (5.8 Hz),
CHC(O)R; 2.02 dd (5.8, 1.5 Hz), Pd-CH; 1.60 d (9.3 Hz), CHH; 1.32 d (9.3 Hz), CHH.
due to the complexity of the NMR spectra the charac-
terization of the products was very difficult.
1200-1250 cm-1 and above 1300 cm-1 indicates that
the trifluoromethanesulfonate group is not coordinated
to the palladium center.20 The high equivalent conduc-
Sp ect r oscop ic Ch a r a ct er iza t ion of Com p lexes
3-8. The allylpalladium complexes 3-8, formed by
insertion reactions of allenes into palladium-carbon
tivities for 3b-8b (in the range of 25-45 Ω-1 cm2 mol-1
)
in dichloromethane at 20 °C are in agreement with an
ionic structure. Although the molecular structure of 7a
clearly shows the presence of a neutral complex, in
which the chloride is coordinated (vide supra), in solu-
tion an equilibrium between the neutral and an ionic
structure, in which the chloride is dissociated, may be
present for complexes 3a -8a (eq 4). The observed
1
bonds, were isolated and characterized by H and 13C
NMR (Tables 3 and 4, respectively) and IR spectroscopy.
Selected compounds were also characterized by 19F
NMR and mass spectroscopy and microanalysis.
Formation of the allyl complexes 3-8 is clear from
the observed syn and anti methyl and proton signals in
1
the H NMR spectra and, in the case of 6-8, the low-
frequency shift of the 13CO resonance from 223.4 ppm
for 2a 19 to about 200 ppm in the 13C NMR. Complexes
6-8 all show in the IR a CO stretching frequency in
the region 1690-1700 cm-1, which is in agreement with
those reported for other (allyl-2-acetyl)palladium com-
pounds.22 The trifluoromethanesulfonate complexes
3b-8b all show in the 19F NMR one resonance at about
-79 ppm, and in the IR all expected vibrations of the
trifluoromethanesulfonate group are observed. The
absence of SO stretching frequencies in the region
equivalence of the syn and anti protons on one end of
the allyl moiety of complexes 7a ,b in the H NMR upon
adding an equimolar amount of 7a to a solution of 7b
1
+
+

3452 Organometallics, Vol. 15, No. 15, 1996
Ta ble 4. 13C NMR Da ta (δ) for Com p lexes 3-13a
Groen et al.
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
allylb
other signals
3a 167.5
3b 171.8
4a 168.1
127.1
126.1
127.1
125.3
126.1
125.7
128.9 131.8
129.3 132.7
129.0 131.9
131.8 144.8 142.6
132.1 146.9 142.3
131.8 145.5 142.2
115.4
115.8
115.6
122.7
123.2
122.2
159.4
160.3
159.3
56.3 130.7, 62.1 24.0, Me
56.5 136.7, 64.6 24.4, Me
56.4 123.2, 85.3, 24.7, Me; 23.2/21.6,
60.9
Mesyn,anti
4b n.o.
126.2
126.3
126.2
128.1
125.1
128.3
126.3
126.4
126.5
124.7
125.2
124.8
129.4 132.7
129.3 132.6
129.4 132.7
128.5 130.9
128.3 131.8
128.4 130.8
132.0 146.6 141.5
131.8 145.7 141.0
131.8 146.1 140.8
131.7 143.4 142.5
131.1 146.1 141.4
131.6 143.1 142.6
116.0
115.9
116.0
115.3
114.8
115.1
122.6
121.6
121.7
122.3
122.2
122.1
160.0
159.3
159.5
159.1
159.2
158.7
56.5 127.3, 87.3, 24.3, Me; 22.3/21.8,
63.6 Mesyn,anti
5a 170.6
5b 171.7
6a 163.9
6b 171.0
7a 163.6
56.4 118.0, 86.1 27.5/26.3, Mesyn,anti
19.9, Me
;
;
56.4 118.7, 86.8 27.3/26.1, Mesyn,anti
19.9, Me
56.1 111.2, 56.4 196.0, C(O)Me; 25.9,
C(O)Me
55.5 123.1, 63.1 194.9, C(O)Me; 26.0,
C(O)Me
56.4 111.4, 83.5, 200.8, C(O)Me; 28.6,
54.8
C(O)Me; 26.4/24.8,
Mesyn,anti
7b 172.3
8a 165.7
8b 171.7
126.2
127.2
125.3
126.1
124.6
125.7
129.0 132.4
128.0 130.4
128.5 131.9
131.8 146.7 141.3
130.9 143.2 141.5
130.9 145.7 139.6
115.8
114.5
115.1
122.4
121.1
121.0
159.8
159.9
158.6
56.2 125.8, 87.3, 200.6, C(O)Me; 29.9,
61.2
C(O)Me; 23.6/22.9,
Mesyn,anti
55.4 119.2, 79.6 205.6, C(O)Me; 33.0,
C(O)Me; 25.7/25.5,
Mesyn,anti
55.5 123.4, 83.8 203.6, C(O)Me; 30.4,
C(O)Me; 24.1,
Mesyn,anti
9c
170.7
165.1
126.1
125.6
126.1
125.6
128.1
128.3
125.3
124.7
125.3
124.7
124.7
124.9
128.5 131.6
128.4 131.0
128.5 131.6
128.4 130.9
128.6 130.9
128.6 130.9
129.8 144.1 140.0
139.9
130.7 144.2 139.5
137.7
131.7 143.5 142.4
131.6 143.1 142.6
114.6
114.0
115.0
113.9
115.3
115.2
123.3
122.4
123.3
122.1
122.4
122.0
158.6
158.3
158.7
158.5
158.9
158.7
55.7
55.6
55.6
55.5
d
e
f
10c 171.3
165.1
11 163.8
12 163.8
56.2 110.1, 56.4
56.2 111.5, 83.7, g
54.7
13a n.o.
126.3
125.6,
125.0
125.9
125.6,
124.7
129.4 132.7
128.5 132.3,
131.9 145.7 138.9
131.1 145.0 138.2,
115.4
124.1
160.1
159.7,
159.2
56.5
55.7
h
i
13b 174.8,
115.1,
123.6,
165.3
131.6
137.9
114.7,
122.9,
114.4
122.7
a
Recorded at 75.48 MHz in CDCl3 at 0 °C, unless noted otherwise. See Table 3 for the adopted numbering scheme (n.o. ) not observed).
Resonances of allyl carbon atoms are listed in the order central, most substituted, and less substituted carbon atom. c Recorded at -40
b
°C. 222.4, PdC(O)R; 198.5, RC(O)Me; 137.7, CdCH2; 130.8, dCH2; 48.2, CH2; 25.8, C(O)Me. e 222.3, PdC(O)R; 204.5, RC(O)Me; 144.1,
d
dCMe2; 129.6, CdCMe2; 49.9, CH2; 29.8, C(O)Me; 22.8/22.1, CMe2. f 199.4, C3H4C(O)R; 195.1, RC(O)Me; 143.1, CdCH2; 129.4, dCH2;
39.8, CH2; 26.0, C(O)Me. g 203.9, C5H8C(O)R; 200.2, RC(O)Me; 144.7, dCMe2; 130.7, CdCMe2; 42.5, CH2; 31.1, C(O)Me; 26.6/24.8, Mesyn,anti
;
h
23.8/23.6, CMe2. 229.2, C7H8C(O)R; 202.8, RC(O)Me; 147.9, dCMe2; 130.9, CdCMe2; 42.4, CH2; 31.9, C(O)Me; 25.0/24.4, CMe2. Signals
of C7H8 moiety: 136.0/134.5, dCH; 61.8, CHC(O)R; 49.9, PdCH; 49.1/47.3, CHCd; 46.4, CH2. 236.6, C7H8C(O)R; 201.7, RC(O)Me; 148.0,
i
dCMe2; 129.8, CdCMe2; 41.1, CH2; 31.1, C(O)Me; 24.1/23.6, CMe2. Signals of C7H8 moiety: 134.5/133.0, dCH; 61.7, CHC(O)R; 49.8,
PdCH; 48.7/46.0, CHCd; 45.1, CH2.
in CDCl3 indicates an intermolecular transfer of the
chloride ion from 7a to 7b, which is fast on the NMR
time scale. Also the observed equivalent conductivities
for 3a -8a in dichloromethane at 20 °C (2.1-4.5 Ω-1 cm2
mol-1), which are in between that of the neutral complex
2a (0.1 Ω-1 cm2 mol-1) and those of the ionic complexes
3b-8b (25-45 Ω-1 cm2 mol-1), point to the presence of
F igu r e 2. Possible products I and II from the insertion of
CO in complex 7a .
an equilibrium between the neutral and ionic structure
for complexes 3a -8a .
of 1670-1710 cm-1. These data are comparable to those
reported for Pd(C(O)C7H8C(O)Me)Cl(p-An-BIAN),19 Pd-
(C(O)C7H10C(O)Me)X(bpy) (X ) Cl, I),17 and [Pd(C(O)-
Sp ectr oscop ic Ch a r a cter iza tion of Com p lexes 9
a n d 10. The acylpalladium complexes Pd(C(O)C3H4C-
(O)Me)Cl(p-An-BIAN) (9) and Pd(C(O)C5H8C(O)Me)Cl-
(p-An-BIAN) (10), obtained via the reaction of CO with
6a and 7a , respectively, were isolated and fully char-
acterized (Tables 3 and 4). Complex 9 shows two
characteristic alkene proton resonances in the region
11
CH(Ar)CH2C(O)Me)CO(bpy)]BAr4 and suggest the
formation of a neutral complex, i.e. coordination of the
chloride to the palladium center and no formation of a
six-membered palladacycle or coordination of the carbon-
carbon double bond to palladium. Also the low equiva-
lent conductivities of 0.39 Ω-1 cm2 mol-1 for 9 and 0.25
Ω-1 cm2 mol-1 for 10 in dichloromethane at 20 °C are
in agreement with this structure.
1
of 5-7 ppm in the H NMR spectrum and two alkene
carbon resonances of 130.8 and 137.7 ppm in the 13C
NMR spectrum. In contrast to the reaction of CO with
6a , insertion of CO into the allyl-palladium bond of 7a
may lead to two different products, I and II (Figure 2).
Sp ect r oscop ic Ch a r a ct er iza t ion of Com p lexes
11-13. Complexes 11 and 12, formed after the reaction
of propadiene and DMA with 9 and 10, respectively,
1
The absence of signals in the 5-7 ppm region in the H
NMR region of 10 indicates that structure I is the
correct structure for 10.
Complexes 9 and 10 both show two 13CO resonances
(at about 222 and 200 ppm) in the 13C NMR spectra and
two CO stretching frequencies in the IR in the region
1
were isolated and characterized by H NMR, 13C NMR
(Tables 3 and 4, respectively), and IR spectroscopy and
elemental analysis. The formation of 11 and 12 is
apparent from the presence of a broad allyl proton signal
1
at 3.3-3.4 ppm in the H NMR spectra, similar to 6a
+
+

Insertion of CO and Allenes into Pd-C Bonds
Organometallics, Vol. 15, No. 15, 1996 3453
and 7a , and a frequency shift of one 13CO resonance
from about 222 ppm to 199.4 ppm for 11 and to 203.9
ppm for 12 in the 13C NMR.
Sch em e 3
Complex [Pd(C7H8C(O)C5H8C(O)Me)(p-An-BIAN)]Cl
(13a ), formed after the insertion of norbornadiene into
the acyl-palladium bond of 10, was characterized by
1H NMR, 13C NMR (Tables 3 and 4, respectively), and
IR spectroscopy. Unfortunately 13a is too unstable in
the solid state to allow outside microanalysis. Cis
addition of Pd-C(O)R to the exo face of the alkene may
be inferred from the coupling constant 3J (CHC(O)R,
Pd-CH) of 6.6 Hz.44 The observed chemical shift
difference of about 0.4 ppm for the two remaining alkene
protons in the C7H8C(O)R fragment in the 1H NMR,
together with the high chemical shift of 229.2 ppm in
the 13C NMR and the low CO stretching frequency of
1601 cm-1 in the IR for the CO in the C7H8C(O)R
fragment indicate that the oxygen atom of this CO is
coordinated to the palladium resulting in a five-
membered palladacycle.17,19,44,45 The observed high
equivalent conductivity of 19.0 Ω-1 cm2 mol-1 in dichlo-
romethane at 20 °C is also in agreement with a
structure, in which the chloride is dissociated. [Pd-
(C7H8C(O)C5H8C(O)Me)(p-An-BIAN)]SO3CF3 (13b), ob-
tained by reacting 13a with 1 equiv of AgSO3CF3, is in
contrast to 13a stable enough to obtain correct analyti-
cal data.
3a -8a .47 In the case of these chloride complexes an
equilibrium between the five-coordinate neutral complex
and a four-coordinate ionic species might be responsible
for the observed exchange process (eq 4). It should be
noted that for none of these complexes any exchange of
syn and anti positioned groups occurred in the temper-
ature range of -70 to -30 °C, showing that during this
fluxional process the allyl moieties remain coordinated
in an η3-fashion.
Interestingly, in the case of the chloride complexes
3a , 4a , 6a , and 7a at higher temperatures (-30 to 20
°C) now also the syn and anti protons of the CH2 moiety
for 4a , 7a and CH2 moieties for 3a , 6a interchange,
showing that an η3-η1-η3 isomerization process48,49
occurs, whereby the palladium atom has to move from
one face of the allyl group to the other and vice versa,
thereby rendering the coordination plane a mirror plane
1
on the H NMR time scale (Scheme 3). In contrast, the
analogous trifluoromethanesulfonate complexes 3b, 4b,
6b, and 7b do not show syn-anti proton exchange in the
same temperature range (-30 to 20 °C). However, in
the presence of 5 bar of CO (at 20 °C) the syn and anti
proton signals are broadening. It might well be that
CO takes up the role of the chloride ion causing the
BIAN ligand to become unidentate bonded.
F lu xion a l Beh a vior of Com p lexes 3-8. The ionic
complexes 3b, 5b, 6b, and 8b, containing a bidentate
bonded BIAN ligand and a symmetrically substituted
allyl moiety, show in the 1H NMR at 300.13 MHz in the
temperature range of -70 to -30 °C one averaged signal
for each pair of acenaphthene protons on either side of
the BIAN ligand, as expected. However, in the case of
4b and 7b, which both contain an asymmetrically
substituted allyl moiety, we also discern that both sides
of the BIAN ligand are magnetically equivalent in the
1H NMR time scale in the same temperature range.
Since this process occurs intramolecularly, as addition
of free ligand gave sharp signals for both free and
coordinated BIAN at 20 °C, we have to assume for 4b
and 7b a process involving a mechanism via nitrogen
dissociation and a cis-trans isomerization of the formed
T-shaped intermediate (which might be stabilized by
coordination of a solvent molecule or the trifluo-
romethanesulfonate ion), followed by nitrogen associa-
tion. A similar mechanism has been proposed by
Pregosin et al.43 and has been confirmed later by
Ba¨ckvall et al. for ionic palladium complexes containing
an asymmetrically substituted allyl moiety and the
bidentate bonded 2,2′-bipyrimidyl ligand.46
Discu ssion
In ser tion of Allen es in to Alk yl- a n d Acyl-
P a lla d iu m Bon d s. Analogous to insertion reactions
of CO50-52 and alkenes53 in square planar organo-
palladium(II) and -platinum(II) complexes, the inser-
tion of allenes may occur via a four-coordinate inter-
mediate (Scheme 4, pathway 1 and 2) or via a five-
coordinate intermediate (Scheme 4, pathway 3).
The results of extensive kinetic studies on the inser-
tion of allenes into the Pd-C(O)Me bond of Pd(C(O)-
Me)Cl(p-An-BIAN) (2a ) carried out very recently in our
laboratory,54 indicate that the insertion may take place
via dissociation of one of the nitrogen atoms of the p-An-
BIAN ligand (insertion via a neutral four-coordinate
intermediate; pathway 2) or via an associative pathway
(pathway 3) rather than via dissociation of the halide
(insertion via an ionic four-coordinate intermediate;
pathway 1). Although p-An-BIAN is a rigid bidentate
ligand and insertion via dissociation of one of the
coordinating nitrogen atoms appeared unlikely,19 we
As observed for the analogous trifluoromethane-
sulfonate complexes, the chloride complexes 3a -8a also
show one averaged signal for the pairs of acenaphthene
protons on both sides of the BIAN ligand in the 1H NMR
in the temperature range -70 to -30 °C. Analogous to
3b-8b, complete dissociation of the BIAN ligand can
be excluded as the source of the observed exchange for
(47) Addition of free BIAN to a solution of 3a -8a in CDCl3 gave
sharp signals for both free and coordinated BIAN at 20 °C, indicating
that ligand exchange is slower than the observed fluxional process.
(48) Vrieze, K. In Dynamic Nuclear Magnetic Resonance Spectros-
copy; J ackman, L. M., Cotton, F. A., Eds.; Academic Press: New York,
1975; pp 441-487.
(49) Vrieze, K.; Volger, H. C.; van Leeuwen, P. W. N. M. Inorg. Chim.
Acta Rev. 1969, 3, 109.
(50) Garrou, P. E.; Heck, R. F. J . Am. Chem. Soc. 1976, 98, 4115.
(51) Anderson, G. K.; Cross, R. J . J . Chem. Soc., Dalton Trans. 1979,
1246.
(52) Anderson, G. K.; Cross, R. J . Acc. Chem. Res. 1984, 17, 67.
(53) Torn, D. L.; Hoffmann, R. J . Am. Chem. Soc. 1978, 100, 2079.
(54) Delis, J . G. P.; Groen, J . H.; Vrieze, K.; van Leeuwen, P. W. N.
M.; Veldman, N.; Spek, A. L. To be published.
(44) Brumbaugh, J . S.; Whittle, R. R.; Parvez, M.; Sen, A. Organo-
metallics 1990, 9, 1735.
(45) Dekker, G. P. C. M.; Elsevier, C. J .; Vrieze, K.; van Leeuwen,
P. W. N. M.; Roobeek, C. F. J . Organomet. Chem. 1992, 430, 357.
(46) Gogoll, A.; O¨ rnebro, J .; Grennberg, H.; Ba¨ckvall, J .-E. J . Am.
Chem. Soc. 1994, 116, 3631.
+
+

3454 Organometallics, Vol. 15, No. 15, 1996
Groen et al.
Sch em e 4
Sch em e 5
into Pd-R bonds of complexes of the type Pd(R)Cl(bpy),
and has been explained by a more efficient overlap of
the π-orbitals of the C(O)Me group (homo) with acces-
sible π-orbitals of the precoordinated allene (lumo) in
the transition state, while a Me group bonded to
palladium does not have suitable orbitals for this type
of overlap.23
As observed earlier, the insertion rate decreases with
increasing substitution at the allenic termini: propa-
diene ≈ DMA . TMA.23,58 This order may be explained
by considering both the initial state, in which the allene
is precoordinated perpendicular to the coordination
plane, and the transition state, in which the allene is
coordinated in an in-plane position. In the case of TMA,
coordinated at a carbon-carbon double bond containing
two sterically demanding methyl groups, the later will
be much more destabilized than in the case of propa-
diene or DMA, both coordinated at a nonsubstituted
carbon-carbon double bond.
Su ccessive In ser tion of CO a n d Allen es. The
propensity of the BIAN ligand to form reactive yet stable
isolable complexes, such in contrast to e.g. bpy, has
allowed us to study a novel example of the stepwise
copolymerization via successive insertion of CO and
allenes into palladium-carbon bonds by starting from
a neutral acylpalladium complex. There are two pos-
sible mechanisms for the CO insertion reaction into the
allyl-palladium bond (Scheme 5; pathway 1 and 2).59
Both possible mechanisms are proposed to proceed via
the formation of an η1-allyl type of intermediate prior
to the insertion reaction. Several studies on insertion
reactions of CO, CO2, SO2, and allenes into palladium-
allyl bonds indicate that insertion takes place via this
type of intermediate.58,60-62 Both mechanisms explain
why the ionic allylpalladium complexes 3b-8b do not
undergo CO insertion. The weakly coordinating trif-
luoromethanesulfonate anion is in pathway 1 unable to
stabilize the η1-allyl type of intermediates. In pathway
2 the trifluoromethanesulfonate anion will not be able
to stabilize the CO insertion product by coordination,
but one might think of stabilization of the product via
coordination of the distal carbonyl group resulting in a
six-membered palladacycle. However, the observed
cannot rule out insertion via this mechanism. The
molecular structure of complex 7a for example clearly
shows a more or less unidentate coordinated p-An-BIAN
ligand, while the starting compound 2a contains a
bidentate coordinated BIAN ligand, indicating that
dissociation of a nitrogen atom of the BIAN ligand has
occurred during the insertion reaction. Also Natile et
al.42 have demonstrated that rigid bidentate nitrogen
ligands like dmphen and phen can be bonded to a
palladium(II) or platinum(II) center in various modes
ranging from bidentate to unidentate, depending on the
donor and acceptor properties of the trans ligands.55 It
certainly should be noted that in our case the differences
between the intermediates of the three pathways are
really rather small. Because of the rigidity of the p-An-
BIAN ligand the formation of an unidentate bonded
ligand cannot be accompanied by a turning away of the
dissociated nitrogen atom from the palladium center.
Also the difference between ionic four-coordinate com-
plexes and five-coordinate complexes will be small,
because in chloroform and dichloromethane the chloride
might remain in the neighborhood of the palladium to
form an ion pair.19,56
The rate of the insertion reaction of allenes into the
Pd-R bond of complexes of the type Pd(R)X(p-An-BIAN)
is highly dependent on the nature of the X and R ligand
and the allene used. The relative high reactivity of the
ionic methyl- and acylpalladium complexes 1b and 2b
can be related to the formation of a more easily
accessible coordination site. Stevens and Shier also
observed that abstraction of the halide in trans-Pd-
(PPh3)2(R)Br (R ) Me, Ph) facilitated propadiene inser-
tion into the Pd-R bond.32 Rate enhancement by
abstraction of the halide has been observed in general
for insertion reactions in square planar organo-pal-
ladium and -platinum complexes.17,19,45,57
The influence of the R group in Pd(R)Cl(p-An-BIAN)
on the allene insertion rate is clear from the much
higher reactivity of 2a (R ) C(O)Me) compared to 1a
(R ) Me) toward allene insertion reactions. The same
trend has been observed for allene insertion reactions
(55) Also zerovalent palladium complexes containing monodentate
coordinated rigid bidentate nitrogen ligands have been observed: (a)
Klein, R. A.; Witte, P.; van Belzen, R.; Elsevier, C. J .; Fraanje, J .;
Goubitz, K.; Numan, M. To be published. (b) Klein, R. A.; van Belzen,
R.; Elsevier, C. J .; Fraanje, J .; Goubitz, K. To be published.
(56) Oslinger, M.; Powell, J . Can. J . Chem. 1973, 51, 274.
(57) Dekker, G. P. C. M.; Elsevier, C. J .; Vrieze, K.; van Leeuwen,
P. W. N. M. Organometallics 1992, 11, 1598.
(58) Hughes, R. P.; Powell, J . J . Organomet. Chem. 1973, 60, 409.
(59) Ozawa, F.; Son, T.-i.; Osakada, K.; Yamamoto, A. J . Chem. Soc.,
Chem. Commun. 1989, 1067.
(60) Hung, T.; J olly, P. W.; Wilke, G. J . Organomet. Chem. 1980,
190, C5.
(61) Santi, R.; Marchi, M. J . Organomet. Chem. 1979, 182, 117.
(62) Behr, A.; J uszak, K.-D. J . Organomet. Chem. 1983, 255, 263.
+
+

Insertion of CO and Allenes into Pd-C Bonds
Organometallics, Vol. 15, No. 15, 1996 3455
immediate formation of the decarbonylation products
6b and 7b upon abstracting the chloride ion from 9 and
10, respectively, by addition of AgSO3CF3 indicates that
ionic CO insertion products cannot be stabilized by
formation of a six-membered palladacycle. Stabilization
of the CO insertion products by coordination of CO is
also unlikely since it is known that these kinds of
species are generally unstable and readily decarbony-
late.19 The inertness of both 5a and 8a toward CO is
probably due to the fact that it is highly unlikely that
the necessary η1-allyl type of intermediate, in which the
palladium center is bonded to a carbon atom bearing
two sterically demanding methyl substituents, will be
formed. This kind of intermediate, as far as we are
aware, has never been observed. The observation of
syn-anti proton exchange in the ionic complexes 6b and
7b in the presence of CO (vide supra) points to the
likelihood of the formation of an η1-allyl type of inter-
mediate by coordination of CO, which therefore favors
pathway 2.
The acylpalladium complexes 9 and 10 reacted almost
quantitatively with 1,2-propadiene and DMA to give the
allylpalladium complex 11 and 12, respectively, both
containing alternating inserted CO and allene frag-
ments. Also the strained alkene norbornadiene reacted
with complex 10 to give the alkyl complex 13a . Com-
plexes 11 and 12 are the first isolated allyl complexes,
containing alternating inserted CO and allene frag-
ments, while complex 13a is the first isolated alkylpal-
ladium complex, containing a metal-bonded ter-oligomer
of carbon monoxide, an allene, and norbornadiene.
Con clu sion
The reactivity of organo-palladium complexes, con-
taining the bidentate nitrogen p-An-BIAN ligand, has
made it possible to carry out for the first time a
stoichiometric co-oligomerization of CO and allenes, and
also a ter-oligomerization of CO, allenes, and norbor-
nadiene, leading to metal-bonded polyketone fragments.
Furthermore, the stability of these complexes has al-
lowed us to isolate and characterize the acyl- and
allylpalladium intermediates, formed after each CO and
allene insertion, respectively. Hereby we again have
demonstrated the ability of the rigid bidentate nitrogen
BIAN ligand in stabilizing and activating organo-
palladium complexes.
Ack n ow led gm en t. This work was supported by the
Netherlands Foundation for Chemical Research (SON)
with financial support from the Netherlands Organiza-
tion for Scientific Research (NWO).
Su p p or tin g In for m a tion Ava ila ble: Listings of final
atomic coordinates, bond distances and angles, torsion angles,
and equivalent isotropic and anisotropic thermal parameters
for 7a (8 pages). Ordering information is given on any current
masthead page.
OM960163P
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