Synthesis of the first stable palladium allenylidene complexes

Article abstract of DOI:10.1021/om800843e

Oxidative addition of BrC=CC(=O)NR₂ to [Pd(PPh₃) ₄] affords the trans-alkynylbromopalladium complexes trans-[Br(PPh₃)₂Pd-C=CC(=O)NR₂] (NR₂ = NMe₂ (2a), N(CH₂

Full text of DOI:10.1021/om800843e

348
Organometallics 2009, 28, 348–354
Synthesis of the First Stable Palladium Allenylidene Complexes
Florian Kessler, Normen Szesni, Kaija Po˜hako, Bernhard Weibert, and Helmut Fischer*
Fachbereich Chemie, UniVersita¨t Konstanz, Fach 727, 78457 Konstanz, Germany
ReceiVed September 1, 2008
Oxidative addition of BrCt CC(dO)NR2 to [Pd(PPh3)4] affords the trans-alkynylbromopalladium
complexes trans-[Br(PPh3)2Pd-Ct CC(dO)NR2] (NR2 ) NMe2 (2a), N(CH2)4) (2b)). Subsequent reaction
of 2a,b with PiPr3 in excess gives trans-[Br(PiPr3)2Pd-Ct CC(dO)NR2] (5a,b). The analogous reaction
of 2b with P(C6H4OMe-4)3 gives trans-[Br(P{C6H4OMe-4}3)2Pd-Ct CC(dO)NR2] (7b), and that of 2a
with trifluoroacetate gives trans-[(F3CCOO)(PPh3)2Pd-Ct CC(dO)NMe2] (9a). Methylation of 2a,b,
7b, and 9a with either MeOTf or [Me3O]BF4 and ethylation of 2a,b with [Et3O]BF4 yield the first cationic
allenylidene complexes of palladium, trans-[R*(PR′3)2Pd-Ct CC(OMe)NR2]+X- (R* ) Br, CF3COO;
i
R′ ) Ph, C6H4OMe-4, Pr; X ) OTf, BF4).
in ring-closing metathesis,6 in ring-opening metathesis,7 in the
Introduction
dehydrogenative dimerization of tin hydrides,8 and in selective
transetherification of substituted vinyl ethers.9
The synthesis of the first allenylidene complexes,
LnMdCdCdC(R1)R2, was reported in 1976 simultaneously by
Fischer et al. (M ) Cr, W)1 and Berke (M ) Mn).2 Fischer’s
synthesis involved Lewis acid induced ethanol abstraction
from ethoxycarbene complexes [(CO)5MdC(OEt)(CHdC-
(NMe2)Ph)]. Berke obtained the manganese allenylidene com-
plex [Cp(CO)2MndCdCdC(tBu)2] on treatment of the methyl
propiolate complex [Cp(CO)2Mn(HCt CCOOMe)] with an
Allenylidene complexes of palladium have been unknown
until now, and consequently their catalytic activity has not been
studied. This is surprising, especially when considering the broad
range of applications of palladium complexes in organic
synthesis and catalysis.10 Many commonly used catalysts for
CC coupling reactions such as, for example, the Mizoroki-Heck
reaction or the Suzuki coupling reaction are based on palladium
complexes.
t
excess of BuLi, presumably via an alkynyl complex as an
We now report on the synthesis and the spectroscopic
properties of the first palladium allenylidene complexes from
readily available N,N-dimethylpropiolamides as the C3 source.
intermediate. Since then a large number of allenylidene com-
plexes of many transition metals have been prepared, including
complexes of titanium, chromium, tungsten, manganese, rhe-
nium, iron, ruthenium, osmium, rhodium, and iridium.3 Most
syntheses now use propargylic alcohols, HCt CC(R)(R′)OH,
as sources of the allenylidene C3 fragment. Coordination of the
propargylic alcohol to the transition metal is followed by its
rearrangement into a hydroxyvinylidene ligand. On subsequent
elimination of water, allenylidene ligands are formed. This
strategy was originally introduced by Selegue.4 Some of these
complexes have been used as catalyst precursors:5 for instance,
Results and Discussion
Initially, we envisioned the transmetalation of allenylidene
ligands from chromium to palladium, since N-heterocyclic
carbene ligands such as pyrazolin-3-ylidene and pyrazolidin-
(6) (a) Fu¨rstner, A.; Picquet, M.; Bruneau, C.; Dixneuf, P. H. Chem.
Commun. 1998, 1315. (b) Picquet, M.; Touchard, D.; Bruneau, C.; Dixneuf,
P. H. New J. Chem. 1999, 23, 141. (c) Osipov, S. N.; Artyushin, O. I.;
Kolomiets, A. F.; Bruneau, C.; Picquet, M.; Dixneuf, P. H. Eur. J. Org.
Chem. 2001, 3891. (d) Picquet, M.; Bruneau, C.; Dixneuf, P. H. Chem.
Commun. 1998, 2249. (e) Se´meril, D.; Le Noˆtre, J.; Bruneau, C.; Dixneuf,
P. H.; Kolomiets, A. F.; Osipov, S. N. New J. Chem. 2001, 25, 16. (f)
Schanz, H.-J.; Jafarpour, L.; Stevens, E. D.; Nolan, S. P. Organometallics
1999, 18, 5187. (g) Jafarpour, L.; Huang, J.; Stevens, E. D.; Nolan, S. P.
Organometallics 1999, 18, 3760. (h) Le Gendre, P.; Picquet, M.; Richard,
P.; Moise, C. J. Organomet. Chem. 2002, 643-644, 231. (i) Fu¨rstner, A.;
Mu¨ller, T. J. Am. Chem. Soc. 1999, 121, 7814. (j) Fu¨rstner, A.; Thiel, O. R.
* To whom correspondence should be addressed. E-mail: helmut.
fischer@uni-konstanz.de. Fax: +7531-883136.
(1) Fischer, E. O.; Kalder, H. J.; Frank, A.; Ko¨hler, F. H.; Huttner, G.
Angew. Chem. 1976, 88, 683; Angew. Chem., Int. Ed. Engl. 1976, 15, 623.
(2) Berke, H. Angew. Chem. 1976, 88, 684; Angew. Chem., Int. Ed. Engl.
1976, 15, 624.
(3) For reviews see: (a) Bruce, M. I.; Swincer, A. G. AdV. Organomet.
Chem. 1983, 22, 59. (b) Bruce, M. I. Chem. ReV. 1991, 91, 197. (c) Doherty,
S.; Corrigan, J. F.; Carty, A. J.; Sappa, E. AdV. Organomet. Chem. 1995,
37, 39. (d) Werner, H. J. Chem. Soc., Chem. Commun. 1997, 903. (e) Bruce,
M. I. Chem. ReV. 1998, 98, 2797. (f) Touchard, D.; Dixneuf, P. H. Coord.
Chem. ReV. 1998, 178-180, 409. (g) Cadierno, V.; Gamasa, M. P.; Gimeno,
J. Eur. J. Inorg. Chem. 2001, 571. (h) Winter, R. F.; Za´lis, S. Coord. Chem.
ReV. 2004, 248, 1565. (i) Rigaut, S.; Touchard, D.; Dixneuf, P. H. Coord.
Chem. ReV. 2004, 248, 1585. (j) Cadierno, V.; Gamasa, M. P.; Gimeno, J.
Coord. Chem. ReV. 2004, 248, 1627. (k) Cadierno, V.; Crochet, P.; Gimeno,
J. In Metal Vinylidenes and Allenylidenes in Catalysis; Bruneau, C., Dixneuf,
P. H., Eds.; Wiley-VCH: Weinheim, Germany, 2008; p 61 ff.
(4) Selegue, J. P. Organometallics 1982, 1, 217.
¨
J. Org. Chem. 2000, 65, 1738. (k) Ozdemir, I.; Cetinkaya, E.; Cetinkaya,
B.; Cicek, M.; Se´meril, D.; Bruneau, C.; Dixneuf, P. H. Eur. J. Inorg. Chem.
2004, 418. (l) Akiyama, R.; Kobayashi, S. Angew. Chem. 2002, 114, 2714;
Angew. Chem., Int. Ed. 2002, 41, 2602.
(7) (a) Saoud, M.; Romerosa, A.; Peruzzini, M. Organometallics 2000,
19, 4005. (b) Castarlenas, R.; Se´meril, D.; Noels, A. F.; Demonceau, A.;
Dixneuf, P. H. J. Organomet. Chem. 2002, 663, 235. (c) Alaoui Abdallaoui,
I.; Se´meril, D.; Dixneuf, P. H. J. Mol. Catal. A 2002, 182-183, 577.
(8) Maddock, S. M.; Finn, M. G. Angew. Chem. 2001, 113, 2196; Angew.
Chem., Int. Ed. 2001, 40, 2138.
(9) Saoud, M.; Romerosa, A.; Manas Carpio, S.; Gonsalvi, L.; Peruzzini,
M. Eur. J. Inorg. Chem. 2003, 1614.
(10) See e.g.: (a) Heck, R. F. Palladium Reagents in Organic Synthesis;
Academic Press: London, 1985. (b) de Meijere, A., Diederich, F. Eds. Metal-
Catalyzed Cross-Coupling Reactions; Wiley-VCH: Weinheim, Germany,
2004. (c) Tsuji, J. Palladium Reagents and Catalysis; Wiley: Chichester,
U.K., 2004.
(5) For recent reviews see: (a) Castarlenas, R.; Fischmeister, C.; Bruneau,
C.; Dixneuf, P. H. J. Mol. Catal. A 2004, 213, 31. (b) Bruneau, C.; Dixneuf,
P. H. Angew. Chem. 2006, 118, 2232; Angew. Chem., Int. Ed. 2006, 45,
2176.
10.1021/om800843e CCC: $40.75
2009 American Chemical Society
Publication on Web 12/09/2008

Palladium Allenylidene Complexes
Scheme 1
Organometallics, Vol. 28, No. 1, 2009 349
Scheme 2
3-ylidene proved readily transferable from pentacarbonylchro-
mium complexes to gold, palladium, and platinum in high
yield.11 The analogous transmetalation of several allenylidene
ligands from chromium to tungsten likewise proceeded quickly
in yields ranging from 83 to 97%.12 However, all attempts to
transfer allenylidene ligands from chromium to palladium met
with failure. Therefore, the strategy had to be changed and an
approach starting from alkynyl complexes was investigated.
Recently, we developed an easy to perform one-pot synthesis
for π-donor-substituted allenylidene pentacarbonyl complexes
of chromium and tungsten. Sequential reaction of the solvent
complexes [(CO)5M(THF)] (M ) Cr, W) with appropriate
deprotonated alkynes as the C3 source and [R3O]BF4 as the
alkylating agent afforded the corresponding amino- and alkoxy-
allenylidene complexes in very good yields.13 Modification of
this route turned out to also be applicable to the preparation of
palladium allenylidene complexes.
Scheme 3
Terminal halogenoalkynes are known to react with zerovalent
palladium complexes by oxidative addition, affording stable
palladium(II) alkynyl complexes.14 Thus, treatment of a suspen-
sion of [Pd(PPh3)4] in CH2Cl2 at ambient temperature with
BrCt CC(dO)NMe2 (1a) afforded the neutral alkynyl complex
2a (Scheme 1). Bromoalkyne 1a was obtained by reaction of
propynoic acid dimethylamide with N-bromosuccinimide (NBS).
Pure alkynyl complex 2a was isolated, after repeated crystal-
lization from mixtures of CH2Cl2 and Et2O, as a colorless solid
in 85% yield. The subsequent alkylation of 2a at -50 °C with
a slight excess of MeOTf proceeded smoothly and afforded the
cationic palladium allenylidene complex 3a-OTf as a light
yellow solid in 91% yield after crystallization from pentane-
CH2Cl2 mixtures (Scheme 1). The corresponding BF4 salt, 3a-
BF4, was obtained when [Me3O]BF4 instead of MeOTf was used
as the alkylation agent. The complexes 2b, 3b-OTf, 3b-BF4,
4a-BF4, and 4b-BF4 were synthesized accordingly.
Modification of the properties of the allenylidene complex
can be achieved by variation of the terminal substituents of the
allenylidene ligand and the coligands at palladium. The variation
of the terminal substituents was achieved by starting from alkyne
1b instead of 1a and employing [Et3O]BF4 as the alkylation
agent; otherwise the same reaction sequence was followed
(Scheme 1).
The metal-bound CR atom and the terminal Cγ atom in
allenylidene complexes are electrophilic centers (see resonance
forms II and III in Scheme 4).3 Therefore, nucleophilic additions
to these centers might compete with substitution of halides for
the bromide ligand or of phosphines for the PPh3 ligands. To
avoid such side reactions at the allenylidene ligand, the alkynyl
complexes 2a,b were chosen as the starting compounds for the
modification of the coligand set in allenylidene complexes.
Treatment of a solution of 2a,b in CH2Cl2 with 2.2 equiv of
the more nucleophilic phosphines PiPr3 and P(C6H4OMe-4)3 led
to quantitative exchange of both PPh3 ligands. Complexes 5a,b
and 7b were obtained as colorless or pale yellow solids after
several recrystallization cycles from Et2O in 70-74% yield.
These alkynyl complexes were subsequently converted into
cationic allenylidene complexes by alkylation with MeOTf. The
resulting allenylidene complexes were then isolated in 98% (6a-
OTf), 97% (6b-OTf), and 91% yield (8b-OTf) (Scheme 2).
When Ag+[CF3COO]- was added to a solution of 2a in
CH2Cl2, AgBr instantaneously precipitated and the trifluoroac-
(11) Kessler, F.; Szesni, N.; Maass, C.; Hohberger, C.; Weibert, B.;
Fischer, H. J. Organomet. Chem. 2007, 692, 3005.
(12) Szesni, N.; Drexler, M.; Fischer, H. Organometallics 2006, 25,
3989.
(13) (a) Fischer, H.; Szesni, N.; Roth, G.; Burzlaff, N.; Weibert, B. J.
Organomet. Chem. 2003, 683, 301. (b) Fischer, H.; Szesni, N. Coord. Chem.
ReV. 2004, 248, 1659.
(14) (a) Burgess, J.; Howden, M. E.; Kemmitt, R. D. W.; Sridhara, N. S.
J. Chem. Soc., Dalton Trans. 1978, 1577. (b) Klein, H. F.; Zettel, B. D.
Chem. Ber. 1995, 128, 343. (c) Mann, G.; Baranano, D.; Hartwig, J. F.;
Rheingold, A. L.; Guzai, I. A. J. Am. Chem. Soc. 1998, 120, 9205. (d)
Weigelt, M.; Becher, D.; Poetsch, E.; Bruhn, C.; Steinborn, D. Z. Anorg.
Allg. Chem. 1999, 625, 1542. (e) Osakada, K.; Hamada, M.; Yamamoto,
T. Organometallics 2000, 19, 458.

350 Organometallics, Vol. 28, No. 1, 2009
Kessler et al.
Scheme 4
etato complex 9a was isolated as a colorless solid in 96% yield.
Alkylation of 9a with MeOTf or [Me3O]BF4 finally afforded
the allenylidene complexes 10a-OTf and 10a-BF4 in 90% and
86% yields, respectively (Scheme 3).
All new alkynyl and allenylidene complexes were character-
ized by spectroscopic means and by elemental analysis. The
structures of 5b and 10a-BF4 were additionally established by
X-ray diffraction studies.
From the observation of only one singlet in the 31P NMR
spectra it followed that the two phosphine ligands are mutually
trans. There was no indication of the presence of a cis isomer.
Two singlets for the two N-bound methyl groups in the NMR
spectra of all alkynyl complexes indicated a rather high barrier
to rotation around the C(sp2)-N bond. From the coalescence
of the two signals of complex 2a in C2D2Cl4 at 115 °C an energy
barrier of ∆Gq ) 76.1 ( 0.4 kJ/mol was calculated. The barrier
is slightly lower than that in free propiolamides (RCt CC-
(dO)NMe2, R ) H, Me, Ph: 79.6-82.1 kcal/mol),15 indicating
minor back-donation from palladium to the alkynyl ligand and
almost negligible interaction of the metal with the C(dO)NMe2
fragment. The resonances of the alkynyl ligand in the 13C NMR
spectra compared well with those of known palladium alkynyl
complexes.14d As expected, increasing the electron density at
palladium in the series 9a, 2a, 7b led to a shift of the 13C
resonance of the metal-bound alkynyl CR atom to lower field.
The resonances of Cꢀ and Cγ were unaffected by varying the
substitution pattern of the metal center.
Figure 1. Structure of the alkynyl complex 5b in the crystal
(ellipsoids drawn at the 50% probability level; hydrogen atoms
omitted for clarity). Important distances (Å) and angles (deg):
Pd(1)-C(1) ) 1.947(3), Pd(1)-Br(1) ) 2.4629(8), Pd(1)-P(1) )
2.3581(9), Pd(1)-P(2) ) 2.3500(9), C(1)-C(2) ) 1.209(5),
C(2)-C(3) ) 1.454(4), C(3)-O(1) ) 1.244(4), C(3)-N(1) )
1.331(4), N(1)-C(4) ) 1.466(5); C(1)-Pd(1)-Br(1) ) 176.41(9),
Pd(1)-C(1)-C(2) ) 175.6(3), C(1)-C(2)-C(3) ) 168.1(3),
C(2)-C(3)-O(1) ) 120.5(3), C(2)-C(3)-N(1) ) 117.5(3).
The formation of the cationic allenylidene complexes by
alkylation of the alkynyl complexes was accompanied by a
pronounced shift of the CR resonance to lower field by about
45 ppm, a shift of the Cꢀ resonance to higher field (∆δ ≈ 11
ppm) and a shift of the ν(CC) vibration to lower energy by
10-15 cm-1. The resonances of the Cγ atom and the N-CH3
groups were again almost unaffected by the alkylation. Similar
trends have been observed on alkylation of alkynylpentacarbo-
nylchromate complexes to give neutral allenylidene complexes.12
The extent of these shifts and the observation of two resonances
Figure 2. Structure of the cation of complex 10a-BF4 in the crystal
(ellipsoids drawn at the 50% probability level; hydrogen atoms,
two molecules of methylene chloride, and the anion BF4- omitted
for clarity). Important distances (Å) and angles (deg): Pd(1)-C(1)
) 1.925(3), Pd(1)-O(1) ) 2.067(2), Pd(1)-P(1) ) 2.3338(9),
Pd(1)-P(2) ) 2.3303(9), C(1)-C(2) ) 1.217(4), C(2)-C(3) )
1.420(4), C(3)-N(1) ) 1.296(4), C(3)-O(3) ) 1.330(4), O(3)-C(4)
) 1.446(4), O(1)-C(7) ) 1.267(3), O(2)-C(7) ) 1.223(4);
C(1)-Pd(1)-O(1) ) 178.69(9), Pd(1)-C(1)-C(2) ) 176.7(2),
C(1)-C(2)-C(3) ) 172.6(3), C(2)-C(3)-N(1) ) 123.0(3),
C(2)-C(3)-O(3) ) 120.8(3), N(1)-C(3)-O(3) ) 116.2(3).
1
for the dimethylamino substituent in the H and 13C NMR
spectra demonstrate the importance of the zwitterionic resonance
forms II and III for the overall bond description of these cationic
allenylidene complexes (Scheme 4).12 As in 2a, 5a, 7b, and
9a, both phosphine ligands are mutually trans, as indicated by
the presence of only one signal for both phosphorus nuclei in
the 31P NMR spectra.
A comparison of the spectroscopic data of these cationic
palladium allenylidene complexes with those of the related
neutral complexes [(CO)5MdCdCdC(NMe2)OMe] (M ) Cr,
W) reveals that in cationic palladium allenylidene complexes
the alkynyl character (see III in Scheme 4) is significantly more
pronounced than in the corresponding group 6 complexes, as
evidenced by the ν(CC) vibration at higher energy by about
were determined by X-ray diffraction studies. The complex 10a-
BF4 crystallizes from dichloromethane with two molecules of
CH2Cl2; the BF4- anion is slightly disordered. In both complexes
the palladium atom engages in square-planar coordination. In
5b the plane formed by the atoms C(3), O(1), and N(1) and the
coordination plane of palladium are almost coplanar (torsion
angle O(1)-C(3)-Pd(1)-P(1) ) 12.0°). In contrast, the alle-
nylidene plane (formed by the atoms C(3), N(1), and O(3)) and
the trifluoracetate plane in 10a-BF4 are perpendicular (89.6 and
87.9°, respectively) to the coordination plane of palladium. In
both complexes the Pd-C3 chain is slightly bent: Pd-C(1)-C(2)
) 175.6(3)° (5b) and 176.7(2)° (10a-BF4), C(1)-C(2)-C(3)
) 168.1(3)° (5b) and 172.6(3)° (10a-BF4). However, a modest
70-90 cm-1
.
The solid-state structures of the alkynyl complex 5b (Figure
1) and of the cationic allenylidene complex 10a-BF4 (Figure 2)
(15) (a) Oki, M. Applications of Dynamic NMR Spectroscopy to Organic
Chemistry; VCH: Deerfield Beach, FL, 1985. (b) Jackman, L. M., Cotton,
F. A., Eds. Dynamic Nuclear Magnetic Resonance Spectroscopy; Academic
Press: New York, 1975.

Palladium Allenylidene Complexes
Organometallics, Vol. 28, No. 1, 2009 351
(5:1) as the eluant. Removal of the solvent gave 1.36 g (7.9 mmol;
deviation from linearity of the MC3 fragment in allenylidene
complexes is often observed.3
1
79%) of 1 as a colorless solid. H NMR (400 MHz, CDCl3): δ
2.88 (s, 3H, NCH3), 3.12 (s, 3H, NCH3). 13C NMR (100 MHz,
The Pd-C bond (1.925(3) Å) in the allenylidene complex
10a-BF4 is close to the shorter limit of observed Pd-C bond
lengths and is shorter than the Pd-C bond in the related cationic
N-heterocyclic carbene (NHC) complexes trans-[L(PR3)2Pd-
(NHC)]+ (1.97-2.01 Å)16 or in the neutral alkynyl complexes
trans-[L(PR3)2Pd-Ct CR] (1.947(3) Å in 5b; range usually
observed 1.95-2.07 Å14d,17). Similarly to other neutral π-donor-
substituted allenylidene complexes of chromium and tung-
sten11-13,18 the C(1)-C(2) bond is very short (1.217(4) Å) and
only slightly longer than in the alkynyl complex 5b (1.209(5)
Å). Conversely, the C(2)-C(3) bond in 10a-BF4 (1.420(4) Å)
is rather long and is even longer than that in [(CO)5CrdCd
CdC(O-adamantyl)NMe2] (1.366(7) Å)18 but, as expected, is
shorter than in 5b (1.454(4) Å). The terminal bonds of the chain,
C(3)-O(3) and C(3)-N(3), however, compare well with those
in related complexes.
In summary, the first isolable palladium allenylidene com-
plexes are accessible by a straightforward two-step synthesis
from readily available bromoalkynes. The new complexes are
remarkably stable. For instance, after heating for 14 h at 160
°C the intensity of the ν(CC) vibration in the IR spectra of 3a-
OTf only decreased to a minor degree, thus confirming the
stability of the new allenylidene complexes. They exhibit all
characteristic features of π-donor-substituted allenylidene
complexes.
CD2Cl2): δ 34.0 (NCH3), 38.0 (NCH3), 55.2 (Ct CBr), 73.4
(Ct CBr), 153.0 (C(O)NMe2). IR (CH2Cl2): ν(Ct C) 2198 cm-1
.
EI-MS (70 eV): m/z (%) 176 (48) [M+], 161 (100) [(M - CH3)+].
Anal. Calcd for C5H6BrNO (176.01): C, 34.12; H, 3.44; N, 7.96.
Found: C, 34.09; H, 3.51; N, 8.05.
1-Bromo-N,N-tetramethylenepropiolamide (1b). The synthesis
of 1b was carried out analogously to 1a. The crude product was
purified by column chromatography using CH2Cl2 as solvent. Yield:
1.72 g (8.51 mmol; 85%) of 1b as a white powder. 1H NMR (400
MHz, CDCl3): δ 1.90 (m, 4H, CH2CH2), 3.44 (t, J ) 7.0 Hz, 2H,
NCH2), 3.61 (t, J ) 7.0 Hz, 2H, NCH2). 13C NMR (100 MHz,
CDCl3): δ 24.6 (CH2), 25.3 (CH2), 45.4 (NCH2), 48.0 (NCH2), 53.8
(Ct CBr), 74.6 (Ct CBr), 177.4 (C(O)NC4H8). IR (CH2Cl2):
ν(CCC) 2196 cm-1. EI-MS (70 eV): m/z (%) 202 (79) [M+], 146
(22) [(M - C4H8)+], 132 (100) [(M - NC4H8)+], 122 (29) [(M -
Br)+], 99 (100) [(M - Br - Ct C)+]. Anal. Calcd for C7H8BrNO
(202.05): C, 41.61; H, 3.99; N, 6.93. Found: C, 42.46; H, 4.37; N,
8.21.
trans-Bromobis(triphenylphosphine)(3-dimethylamino-3-oxy-1-
propynyl)palladium(II) (2a). A suspension of 1.16 g (1 mmol) of
[Pd(PPh3)4] in 30 mL of CH2Cl2 was treated with 0.26 g (1.5 mmol)
of 1a at ambient temperature. The mixture was stirred for 30 min,
upon which it becomes a clear yellow solution. Then, 100 mL of
dry Et2O was added. The light yellow precipitate was filtered off
and washed repeatedly with Et2O (3 × 30 mL) and pentane (2 ×
50 mL). Repeated crystallization of the crude product from CH2Cl2/
Et2O gave 0.69 g (0.85 mmol; 85%) of pure 2a as an off-white
powder. 1H NMR (400 MHz, CD2Cl2): δ 2.19 (s, 3H, NCH3), 2.49
(s, 3H, NCH3), 7.38-7.47 (m, 18H, ArH), 7.68-7.73 (m, 12H,
ArH). 13C NMR (100 MHz, CD2Cl2): δ 33.2 (NCH3), 37.6 (NCH3),
Experimental Section
All reactions were performed under a nitrogen atmosphere by
using standard Schlenk techniques. Solvents were dried by distil-
lation from CaH2 (CH2Cl2), LiAlH4 (pentane), and sodium (Et2O).
The yields refer to analytically pure compounds and are not
2
104.1 (t, JPC ) 10.8 Hz, Pd-Ct C), 107.7 (Pd-Ct C), 128.4 (t,
1
3JPC ) 4.8 Hz, m-C), 130.9 (p-C), 131.4 (t, JPC ) 25.0 Hz, i-C),
2
135.3 (t, JPC ) 6.7 Hz, o-C), 154.4 (C(O)NMe2). 31P NMR (162
1
optimized. H, 13C, 19F, and 31P NMR spectra were recorded on a
MHz, CD2Cl2): δ 24.7. IR (CH2Cl2): ν(Ct C) 2109 cm-1; ν(CO)
1609 cm-1. UV-vis (CH2Cl2): λmax (nm) (log ꢀ) 240 (4.489), 305
(4.314). FAB-MS: m/z (%) 725 (28) [(M - Br)+]. Anal. Calcd for
C41H36BrNOP2Pd · CH2Cl2 (807.01): C, 56.56; H, 4.29; N, 1.57.
Found: C, 57.09; H, 4.60; N, 1.55.
Jeol JNX 400, a Varian Inova 400, or a Bruker Avance 400
spectrometer at ambient temperature. Chemical shifts are reported
relative to the residual solvent peaks or tetramethylsilane (1H, 13C)
and 100% H3PO4 (31P). Other instrumentation: IR, Biorad FTS 60;
MS, Finnigan MAT 312; elemental analysis, Heraeus Elementar
Vario EL. N,N-Dimethylpropiolamide19 and [Pd(PPh3)4]20 were
synthesized according to literature procedures. All other reagents
were used as obtained from commercial suppliers.
1-Bromo-N,N-dimethylpropiolamide (1a). A solution of 0.97 g
(10 mmol) of N,N-dimethylpropiolamide in 40 mL of acetone was
treated at ambient temperature with 2.16 g (12 mmol) of NBS and
150 mg (0.9 mmol) of AgNO3. After 60 min the reaction mixture
was poured onto 200 mL of ice water. The aqueous phase was
extracted three times with 30 mL portions of ethyl acetate. The
combined organic extracts were dried over MgSO4. The solid was
then filtered off and the solvent removed in vacuo. The crude
product was filtered over a short plug of silica using CH2Cl2/acetone
trans-Bromobis(triphenylphosphine)(3-N,N-tetramethyleneamino-
3-oxy-1-propynyl)palladium(II) (2b). A suspension of 1.16 g
(1 mmol) of [Pd(PPh3)4] in 30 mL of dry CH2Cl2 was treated with
0.30 g (1.5 mmol) of 1b at ambient temperature. The mixture was
stirred for a further 30 min, upon which it became a clear yellow
solution. The solvent was removed in vacuo, and the crude product
was purified by column chromatography using petroleum ether/
CH2Cl2/acetone mixtures. Yield: 0.71 g (0.85 mmol; 85%) of 2b
as a pale yellow powder. 1H NMR (400 MHz, CDCl3): δ 1.37 (m,
2H, CH2), 1.56 (m, 2H, CH2), 2.26 (t, J ) 7.0 Hz, 2H, NCH2),
3.03 (t, J ) 7.0 Hz, 2H, NCH2), 7.34-7.40 (m, 18 H, ArH),
7.67-7.72 (m, 12 H, ArH). 13C NMR (100 MHz, CDCl3): δ 24.6
(CH2) 25.0 (CH2), 44.2 (NCH2), 46.9 (NCH2), 105.0 (t, 3JPC ) 5.8
Hz, Pd-Ct C), 107.1 (t, 2JPC ) 13.4 Hz, Pd-Ct C), 128.0 (t, 3JPC
) 4.8 Hz, m-C), 130.4 (p-C), 130.9 (t, 1JPC ) 24.9 Hz, i-C), 135,0
(t, 2JPC ) 6.7 Hz, o-C), 152.9 (C(O)NC4H8). 31P NMR (162 MHz,
CDCl3): δ 21.7. IR (CH2Cl2): ν(CCC) 2115 cm-1. UV-vis
(CH2Cl2): λmax (nm) (log ꢀ) 302 (4.373). FAB-MS: m/z (%) 834
(7) [M+], 751 (8) [(M - Br - 2H)+], 489 (16) [(M - Br - 2H -
PPh3)+], 367 (41) [(M - Br - 2H - PPh3 - C7H8NO)+]. Anal.
Calcd for C43H38BrNOP2Pd (833.04): C, 62.00; H, 4.60; N, 1.68.
Found: C, 61.86; H, 4.63; N, 1.57.
(16) See e.g.: (a) Fu¨rstner, A.; Seidel, G.; Kremzow, D.; Lehmann, C. W.
Organometallics 2003, 22, 907. (b) Schneider, S. K.; Roembke, P.; Julius,
G. R.; Raubenheimer, H. G.; Herrmann, W. A. AdV. Synth. Catal. 2006,
348, 1862. (c) Schuster, O.; Raubenheimer, H. G. Inorg. Chem. 2006, 45,
7997.
(17) (a) Behrens, U.; Hoffmann, K. J. Organomet. Chem. 1977, 129,
273. (b) van der Voort, E.; Spek, A. L.; de Graaf, W. Acta Crystallogr.,
Sect. C: Cryst. Struct. Commun. 1987, 43, 2311. (c) Osakada, K.; Sakata,
R.; Yamamoto, T. Organometallics 1997, 16, 5354. (d) Kim, Y.-J.; Lee,
S.-H.; Lee, S.-H.; Jeon, S.-I.; Lim, M. S.; Lee, S. W. Inorg. Chim. Acta
2005, 358, 650.
(18) Szesni, N.; Weibert, B.; Fischer, H. Inorg. Chim. Acta 2006, 359,
617.
(19) Crow, W. D.; Leonard, N. J. J. Org. Chem. 1965, 30, 2660.
(20) Tellier, F.; Sauvetre, R.; Normant, J. F. J. Organomet. Chem. 1985,
292, 19.
trans-Bromobis(triphenylphosphine)(3-dimethylamino-3-meth-
oxy-1,2-propadienylidene)palladium(II) Trifluoromethanesulfonate
(3a-OTf). A solution of 0.5 g (0.62 mmol) of 2a in 30 mL of CH2Cl2
was treated dropwise with 0.07 mL (0.62 mmol) of MeOTf at -50

352 Organometallics, Vol. 28, No. 1, 2009
Kessler et al.
°C. After 10 min at -50 °C, the solution was warmed to ambient
temperature. The progress of the reaction was followed by IR
spectroscopy. When all of the starting material was consumed, the
solvent was removed in vacuo. The remaining residue was washed
twice with 30 mL of Et2O and recrystallized from mixtures of
CH2Cl2 and pentane. Pure 3a-OTf (0.55 g, 0.56 mmol; 91%) was
cm-1. UV-vis (CH2Cl2): λmax (nm) (log ꢀ) 300 (4.376). FAB-MS:
m/z (%) 847 (19) [(M - BF4)+], 586 (16) [(M - BF4 - PPh3)+],
505 (9) [(M - BF4 - PPh3 - Br)+], 324 (40) [(M - BF4 - 2
PPh3)+]. Anal. Calcd for C44H41BBrF4NOP2Pd · 0.5CH2Cl2 (934.89):
C, 54.69; H, 4.33; N, 1.43. Found: C, 54.52; H, 4.51; N, 1.35.
trans-Bromobis(triphenylphosphine)(3-dimethylamino-3-ethoxy-
1,2-propadienylidene)palladium(II) Tetrafluoroborate (4a-BF4).
The synthesis of 4a-BF4 from 91 mg (0.11 mmol) of 2a and 21
mg (0.11 mmol) of [Et3O]BF4 in 5 mL of CH2Cl2 was carried out
analogously to 3a-OTf. Yield: 77 mg (0.08 mmol; 76%) of 4a-
1
obtained as a light yellow powder. H NMR (400 MHz, CD2Cl2):
δ 3.23 (s, 3H, NCH3), 3.40 (s, 3H, NCH3), 3.74 (s, 3H, OCH3),
7.03-7.11 (m, 18H, ArH), 7.21-7.25 (m, 12H, ArH). 13C NMR
(100 MHz, CD2Cl2): δ 35.1 (NCH3), 40.3 (NCH3), 61.7 (OCH3),
1
3
1
96.1 (Cꢀ), 120.9 (q, JCF ) 316.4 Hz, CF3), 128.9 (t, JPC ) 5.8
BF4 as a yellow powder. H NMR (400 MHz, CD2Cl2): δ 1.01 (t,
1
Hz, m-C), 129.9 (t, JPC ) 25.3 Hz, i-C), 132.2 (p-C), 135.4 (t,
J ) 7.0 Hz, 2 H, CH3), 2.69 (s, 3 H, NCH3), 2.90 (s, 3 H, NCH3),
3.54 (q, J ) 7.0 Hz, 2 H, CH2), 7.45-7.56 (m, 18 H, ArH),
7.67-7.72 (m, 12 H, ArH). 13C NMR (100 MHz, CD2Cl2): δ 14.3
(OCH2CH3), 37.5 (NCH3), 41.4 (NCH3), 71.9 (OCH2CH3), 93.1
(t, 3JPC ) 4.8 Hz, Cꢀ), 128.8 (t, 3JPC ) 5.8 Hz, m-C), 130.1 (t, 1JPC
) 25.9 Hz, i-C), 131.7 (p-C), 135.0 (t, 2JPC ) 5.8 Hz, o-C), 149.3
(t, 2JPC ) 12.5 Hz, CR), 152.9 (Cγ). 31P NMR (162 MHz, CD2Cl2):
δ 24.8. IR (CH2Cl2): ν(CCC) 2099 cm-1. UV-vis (CH2Cl2): λmax
(nm) (log ꢀ) 300 (4.335). FAB-MS: m/z (%) 834 (44) [(M - BF4)+],
2JPC ) 6.0 Hz, o-C), 150.9 (t, JPC ) 5.5 Hz, CR), 154.1 (Cγ). 31P
3
NMR (162 MHz, CD2Cl2): δ 24.5. IR (THF): ν(CCC) 2099 cm-1
.
UV-vis (CH2Cl2): λmax, nm (log ꢀ) 236 (4.563), 298 (4.361). FAB-
MS: m/z (%) 821 (56) [(M - CF3SO3)+], 560 (48) [(M - CF3SO3
- PPh3)+]. Anal. Calcd for C43H39BrF3NO4P2PdS (971.11): C,
53.18; H, 4.05; N, 1.44. Found: C, 53.49; H, 4.46; N, 1.34.
trans-Bromobis(triphenylphosphine)(3-dimethylamino-3-meth-
oxy-1,2-propadienylidene)palladium(II) Tetrafluoroborate (3a-
BF4). The synthesis of 3a-BF4 from 1.0 g (1.24 mmol) of 2a and
0.25 g (1.70 mmol, 1.4 equiv) of [Me3O]BF4 in 60 mL of CH2Cl2
was carried out analogously to 3a-OTf. Yield: 0.70 g (0.77 mmol;
62%) of 3a-BF4 as a yellow powder. 1H NMR (400 MHz, CD2Cl2):
δ 2.69 (s, 3 H, NCH3), 2.91 (s, 3 H, NCH3), 3.31 (s, 3 H, OCH3),
7.45-7.56 (m, 18 H, ArH), 7.66-7.71 (m, 12 H, ArH). 13C NMR
(100 MHz, CD2Cl2): δ 37.7 (NCH3), 41.7 (NCH3), 61.3 (OCH3),
128.8 (t, 3JPC ) 5.6 Hz, m-C), 130.2 (t, 1JPC ) 25.7 Hz, i-C), 131.8
573 (18) [(M
-
BF4
-
PPh3)+]. Anal. Calcd for
C43H41BBrF4NOP2Pd (922.88): C, 55.96; H, 4.48; N, 1.52. Found:
C, 56.02; H, 4.50; N, 1.44.
trans-Bromobis(triphenylphosphine)(3-N,N-tetramethyleneamino-
3-ethoxy-1,2-propadienylidene)palladium(II) Tetrafluoroborate (4b-
BF4). The synthesis of 4b-BF4 from 0.81 g (0.97 mmol) of 2b and
0.18 g (0.97 mmol) of [Et3O]BF4 in 30 mL of CH2Cl2 was carried
out analogously to 3a-OTf. Yield: 0.92 g (0.96 mmol; 99%) of
4b-BF4 as a yellow powder. 1H NMR (400 MHz, CD2Cl2): δ 0.95
(t, J ) 7.0 Hz, 3 H, OCH2CH3), 1.86 (m, 2 H, CH2), 2.67 (t, J )
7.0 Hz, 2 H, NCH2), 3.31 (t, J ) 7.0 Hz, 2 H, NCH2), 3.48 (q, J
) 7.0 Hz, 2 H, OCH2CH3), 7.42-7.50 (m, 18 H, ArH), 7.62-7.67
(m, 12 H, ArH). 13C NMR (100 MHz, CD2Cl2): δ 14.2 (OCH2CH3),
24.1 (CH2), 24.3 (CH2), 48.8 (NCH2), 51.3 (NCH2), 70.7
2
(p-C), 135.1 (t, JPC ) 6.4 Hz, o-C); CR, Cꢀ, Cγ not observed. 31P
NMR (162 MHz, CD2Cl2): δ 24.7. IR (CH2Cl2): ν(CCC) 2098 cm-1
.
UV-vis (CH2Cl2): λmax (nm) (log ꢀ) 298 (4.368). FAB-MS: m/z
(%) 822 (72) [(M - BF4)+], 560 (37) [(M - BF4 - PPh3)+]. Anal.
Calcd for C42H39BBrF4NOP2Pd · 0.5CH2Cl2 (908.85): C, 53.66; H,
4.24; N, 1.47. Found: C, 53.83; H, 4.51; N, 1.49.
3
(OCH2CH3), 94.1 (Cꢀ), 128.4 (t, JPC ) 5.7 Hz, m-C), 129.8 (t,
trans-Bromobis(triphenylphosphine)(3-N,N-tetramethyleneamino-
3-methoxy-1,2-propadienylidene)palladium(II) Trifluoromethane-
sulfonate (3b-OTf). The synthesis of 3b-OTf from 0.32 g (0.38
mmol) of 2b and 0.04 mL (0.38 mmol) of MeOTf in 20 mL of
CH2Cl2 was carried out analogously to 3a-OTf. Yield: 0.82 g (0.82
2
1JPC ) 26.0 Hz, i-C), 131.4 (p-C), 134.7 (t, JPC ) 5.7 Hz, o-C),
145.8 (CR), 150.1 (Cγ). 31P NMR (162 MHz, CD2Cl2): δ 21.8. IR
(CH2Cl2): ν(CCC) 2101 cm-1; ν(CO) 1604 cm-1. UV-vis
(CH2Cl2): λmax (nm) (log ꢀ) 297 (4.462). FAB-MS: m/z (%) 861
(50) [(M - BF4)+], 600 (37) [(M - BF4 - PPh3)+]. Anal. Calcd
for C45H43BBrF4NOP2Pd (948.92): C, 56.96; H, 4.57; N, 1.48.
Found: C, 56.83; H, 4.53; N, 1.55.
1
mmol; 97%) of 3b-OTf as a yellow powder. H NMR (400 MHz,
CD2Cl2): δ 1.70 (m, 2 H, CH2), 1.87 (m, 2 H, CH2), 2.68(t, J )
7.0 Hz, 2 H, NCH2), 3.27 (s, 3 H, OCH3), 3.34 (t, J ) 7.0 Hz, 2
H, NCH2), 7.42-7.50 (m, 18 H, ArH), 7.63-7.67 (m, 12 H, ArH).
trans-Bromobis(triisopropylphosphine)(3-dimethylamino-3-oxy-
1-propynyl)palladium(II) (5a). At ambient temperature, a solution
of 0.55 g (0.68 mmol) of 2a in 30 mL of CH2Cl2 was treated with
0.29 mL (1.50 mmol, 2.2 equiv) of PiPr3. The progress of the
reaction was monitored by IR spectroscopy. When all of the starting
material was consumed (60 min), the solvent was removed in vacuo
and the crude product purified by column chromatography using a
petroleum ether/Et2O mixture as the eluant. Removal of the solvent
13C NMR (100 MHz, CD2Cl2): δ 24.2 (CH2), 24.4 (CH2), 48.9
3
(NCH2), 51.4 (NCH2), 60.4 (OCH3), 93.8 (Cꢀ), 128.5 (t, JPC
)
5.6 Hz, m-C), 129.8 (t, 1JPC ) 25.9 Hz, i-C), 131.4 (p-C), 134.7 (t,
2JPC ) 6.2 Hz, o-C), 147.8 (CR), 150.9 (Cγ). 31P NMR (162 MHz,
CDCl3): δ 24.9. IR (CH2Cl2): ν(CCC) 2100 cm-1; ν(CO) 1612
cm-1. UV-vis (CH2Cl2): λmax (nm) (log ꢀ) 296 (4.437). FAB-MS:
m/z (%) 847 (32) [(M - OTf)+], 586 (20) [(M - OTf - PPh3)+],
505 (11) [(M - OTf - PPh3 - Br)+], 323 (59) [(M - OTf - 2
PPh3)+]. Anal. Calcd for C45H41BrF3NO4P2PdS (997.15): C, 54.20;
H, 4.14; N, 1.40. Found: C, 54.16; H, 4.19; N, 1.36.
1
gave 0.29 g (0.47 mmol, 70%) of pure 5a as a white powder. H
NMR (400 MHz, CD2Cl2): δ 1.35 (q, J ) 7.04 Hz, 36H, CH(CH3)2),
2.82 (s, 3H, NCH3), 2.89 (m, 6H, CH(CH3)2), 3.10 (s, 3H, NCH3).
13C NMR (100 MHz, CD2Cl2): δ 20.1 (CH(CH3)2), 24.7 (t, 2JPC
)
)
trans-Bromobis(triphenylphosphine)(3-N,N-tetramethyleneamino-
3-methoxy-1,2-propadienylidene)palladium(II) Tetrafluoroborate
(3b-BF4). The synthesis of 3b-BF4 from 0.48 g (0.58 mmol) of 2b
and 0.10 g (0.69 mmol, 1.2 equiv) of [Me3O]BF4 in 30 mL of
CH2Cl2 was carried out analogously to 3a-OTf. Yield: 0.52 g (0.56
3
11.5 Hz, CH(CH3)2), 33.7 (NCH3), 38.0 (NCH3), 103.7 (t, JPC
2
4.8 Hz, Pd-Ct C), 107.7 (t, JPC ) 12.6 Hz, Pd-Ct C), 155.3
(C(O)NMe2). 31P NMR (162 MHz, CD2Cl2): δ 42.1. IR (THF):
ν(Ct C) 2098 cm-1; ν(CO) 1605 cm-1. UV-vis (CH2Cl2): λmax
(nm) (log ꢀ) 251 (4.134), 288 (4.167). MS (FAB): m/z (%) 604
(19) [M+], 523 (24) [(M - Br)+], 362 (11) [(M - Br - P(iPr)3)+].
Anal. Calcd for C23H48BrNOP2Pd (602.91): C, 45.82; H, 8.02; N,
2.32. Found: C, 46.03; H, 7.97; N, 2.39.
1
mmol; 97%) of 3b-BF4 as a yellow powder. H NMR (400 MHz,
CDCl3): δ 1.69 (m, 2 H, CH2), 1.86 (m, 2 H, CH2), 2.67 (t, J ) 7.0
Hz, 2 H, NCH2), 3.24 (s, 3 H, OCH3), 3.34 (t, J ) 7.0 Hz, 2 H,
NCH2), 7.37-7.51 (m, 18 H, ArH), 7.63-7.70 (m, 12 H, ArH).
13C NMR (100 MHz, CDCl3): δ 24.5 (CH2), 24.7 (CH2), 49.2
trans-Bromobis(triisopropylphosphine)(3-N,N-tetramethylene-
amino-3-oxy-1-propynyl)palladium(II) (5b). The synthesis of 5b
from 1.23 g (1.48 mmol) of 2b and 0.62 mL (3.25 mmol, 2.2 equiv)
of PiPr3 in 30 mL of CH2Cl2 was carried out analogously to 5a.
The crude product was purified by column chromatography using
3
(NCH2), 51.7 (NCH2), 60.7 (OCH3), 94.3 (Cꢀ), 128.8 (t, JPC
)
5.3 Hz, m-C), 130.1 (t, 1JPC ) 26.0 Hz, i-C), 131.7 (p-C), 135.1 (t,
2JPC ) 6.2 Hz, o-C), 151.2 (CR), 154.1 (Cγ). 31P NMR (162 MHz,
CD2Cl2): δ 25.0. IR (CH2Cl2): ν(CCC) 2101 cm-1; ν(CO) 1609

Palladium Allenylidene Complexes
Organometallics, Vol. 28, No. 1, 2009 353
an ether/CH2Cl2/acetone mixture. Yield: 0.65 g (1.03 mmol; 70%)
of 5b as a white powder. 1H NMR (400 MHz, CDCl3): δ 1.38 (m,
36 H, CH(CH3)2), 1.87 (br, 4H, CH2CH2), 2.94 (m, 6 H, CH(CH3)2),
ꢀ) 317 (4.420). FAB-MS: m/z (%) 1013 (20) [M+], 933 (85) [(M
- Br)+], 580 (27) [(M - Br - P(C6H4OMe-p)3)+]. Anal. Calcd
for C49H50BrNO7P2P d × 0.5 CH2Cl2 (1013.21): C, 56.32; H, 4.87;
N, 1,33. Found: C, 55.69; H, 4.86; N, 1.02.
3.40 (t, J ) 6.6 Hz, 2H, NCH2), 3.53 (t, J ) 6.6 Hz, 2H, NCH2).
2
13C NMR (100 MHz, CDCl3): δ 19.6 (CH(CH3)2), 24.0 (t, JPC
)
trans-Bromobis[tris(4-methoxyphenyl)phosphine](3-N,N-tetram-
ethyleneamino-3-methoxy-1,2-propadienylidene)palladium(II) Tri-
fluoromethanesulfonate (8b-OTf). The synthesis of 8b-OTf from
0.58 g (0.57 mmol) of 7b and 0.07 mL (0.57 mmol) of MeOTf in
20 mL of CH2Cl2 was carried out analogously to 3a-OTf. Yield:
0.62 g (0.52 mmol; 91%) of 8b-OTf as a yellow powder. 1H NMR
(400 MHz, CDCl3): δ 1.68 (m, 2H, CH2), 1.85 (m, 2H, CH2), 2.72
(m, 2H, NCH2), 3.35 (m, 2H, NCH2), 3.78 (s, 3H, OCH3), 3.81 (s,
18 H, OCH3), 6.92-6.95 (m, 12 H, ArH), 7.52-7.57 (m, 12 H,
ArH). 13C NMR (100 MHz, CDCl3): δ 24.1 (CH2), 24.4 (CH2),
48.7 (NCH2), 51.3 (NCH2), 55.4 (OCH3), 60.5 (OCH3), 93.9 (Cꢀ),
11.6 Hz, CH(CH3)2), 24.3 (CH2), 25.2 (CH2), 44.3 (NCH2), 47.0
(NCH2), 103.9 (t, 3JPC ) 4.8 Hz, Pd-Ct C), 106.0 (t, 2JPC ) 12.4
Hz, Pd-Ct C), 153.1 (C(O)NC4H8). 31P NMR (162 MHz, CDCl3):
δ 41.7. IR (CH2Cl2): ν(CCC) 2106 cm-1. UV-vis (CH2Cl2): λmax
(nm) (log ꢀ) 287 (4.224). FAB-MS: m/z (%) 629 (39) [M+], 549
(18) [(M - Br)+], 470 (6) [(M - P(iPr)3)+], 389 (9) [(M - Br -
P(iPr)3)+], 347 (6) [(M - P(iPr)3)+ - C7H8NO], 267 (38) [(M -
Br - P(iPr)3 - C7H8NO)+]. Anal. Calcd for C25H50BrNOP2Pd
(628.95): C, 47.74; H, 8.01; N, 2,23. Found: C, 47.68; H, 7.74; N,
2.57.
1
2
114.0 (ArC), 121.6 (t, JPC ) 28.7 Hz, ArC), 136,3 (t, JPC ) 7.1
Hz, ArC), 151.1 (Cγ), 161.8 (ArC), 177.0 (CR). 31P NMR (162 MHz,
CDCl3): δ 20.4. 19F NMR (376 MHz, CDCl3): δ -78.2. IR
(CH2Cl2): ν(CCC) 2098 cm-1. UV-vis (CH2Cl2): λmax (nm) (log
ꢀ) 328 (4.352). FAB-MS: m/z (%) 1028 (8) [(M - OTf)+], 948 (8)
[(M - OTf - Br)+], 595 (23) [(M - OTf - Br - P(C6H4OMe-
p)3)+]. Anal. Calcd for C51H53BrF3NO10P2PdS (1177.32): C, 52.03;
H, 4.54; N, 1.19. Found: C, 52.10; H, 4.72; N, 1.26.
trans-Bromobis(triisopropylphosphine)(3-dimethylamino-3-meth-
oxy-1,2-propadienylidene)palladium(II) Trifluoromethanesulfonate
(6a-OTf). The synthesis of 6a-OTf from 0.3 g (0.50 mmol) of 5a
and 0.06 mL (0.50 mmol) of MeOTf in 30 mL of CH2Cl2 was
carried out analogously to 3a-OTf. Complex 6a-OTf was recrystal-
lized from Et2O. Yield: 0.37 g (0.49 mmol; 98%) of 6a-OTf as a
1
colorless powder. H NMR (400 MHz, CD2Cl2): δ 1.35 (q, J )
7.04 Hz, 36H, CH(CH3)2), 2.85 (m, 6H, CH(CH3)2), 3.25 (s, 3H,
NCH3), 3.45 (s, 3H, NCH3), 4.20 (s, 3H, OCH3). 13C NMR (100
trans-(Trifluoroacetato)bis(triphenylphosphine)(3-dimethylamino-
3-oxy-1-propynyl)palladium(II) (9a). A suspension of 0.55 g (0.68
mmol) of 2a and 0.15 g (0.68 mmol) of CF3COOAg in 30 mL of
dry CH2Cl2 was stirred for 30 min. The precipitate (AgBr) that
formed was filtered off. The solvent of the crude reaction mixture
was removed in vacuo. Crystallization of the crude product from
CH2Cl2/Et2O gave 0.54 g (0.65 mmol; 96%) of 9a as a colorless
powder. 1H NMR (400 MHz, CD2Cl2): δ 1.93 (s, 3H, NCH3), 2.47
(s, 3H, NCH3), 7.41-7.51 (m, 18H, ArH), 7.71-7.79 (m, 12H,
ArH). 13C NMR (100 MHz, CD2Cl2): δ 33.2 (NCH3), 37.2 (NCH3),
2
MHz, CD2Cl2): δ 20.0 (CH(CH3)2), 25.0 (t, JPC ) 11.8 Hz,
CH(CH3)2), 38.3 (NCH3), 42.1 (NCH3), 61.7 (OCH3), 94.6 (t, 3JPC
1
2
) 3.8 Hz, Cꢀ), 121.4 (q, JCF ) 320.0 Hz, CF3), 150.3 (t, JPC
)
10.6 Hz, CR), 153.7 (Cγ). 31P NMR (162 MHz, CD2Cl2): δ 45.3.
IR (THF): ν(CCC) 2083 cm-1. UV-vis (CH2Cl2): λmax (nm) (log
ꢀ) 247 (4.103), 279 (4.371). FAB-MS: m/z (%) 618 (75) [(M -
OTf)+], 458 (48) [(M - OTf - P(iPr)3)+]. Anal. Calcd for
C25H51BrF3NO4P2PdS (767.01): C, 40.80; H, 6.98; N, 1.90. Found:
C, 39.38; H, 6.33; N, 1.54.
2
93.8 (t, JPC ) 10.7 Hz, Pd-Ct C), 107.4 (Pd-Ct C), 107.4
trans-Bromobis(triisopropylphosphine)(3-N,N-tetramethylene-
amino-3-methoxy-1,2-propadienylidene)palladium(II) Trifluo-
romethanesulfonate (6b-OTf). The synthesis of 6b-OTf from 0.18 g
(0.27 mmol) of 5b and 0.03 mL (0.27 mmol) of MeOTf in 10 mL
of CH2Cl2 was carried out analogously to 3a-OTf. Yield: 0.21 g
3
1
(CF3COO), 128.4 (t, JPC ) 5.7 Hz, m-C), 129.6 (t, JPC ) 25.0
2
Hz, i-C), 131.2 (p-C), 134.1 (t, JPC ) 5.3 Hz, o-C), 154.3
(C(O)NMe2), 174.3 (CF3COO). 31P NMR (162 MHz, CD2Cl2): δ
23.9. IR (THF): ν(Ct C) 2114 cm-1; ν(CO) 1680, 1609 cm-1
.
1
UV-vis (CH2Cl2): λmax (nm) (log ꢀ) 239 (4.513), 297 (4.449). FAB-
MS: m/z (%) 727 (11) [(M - CF3COO)+], 631 (62) [(M - CF3COO
- C5H6NO)+], 369 (62) [(M - CF3COO - C5H6NO - PPh3)+].
Anal. Calcd for C43H36F3NO3P2Pd · CH2Cl2 (840.13): C, 57.13; H,
4.14; N, 1.51. Found: C, 57.52; H, 4.30; N, 1.81.
(0.26 mmol; 97%) of 6b-OTf as a white powder. H NMR (400
MHz, CDCl3): δ 1.33 (m, 36 H, CH(CH3)2), 2.02 (br, 4H, CH2CH2),
2.84 (m, 6 H, CH(CH3)2), 3.76 (t, J ) 7.0 Hz, 4 H, NCH2), 4.15
(s, 3 H, OCH3). 13C NMR (100 MHz, CDCl3): δ 19.9 (CH(CH3)2),
1
24.7 (t, JPC ) 11.1 Hz, CH(CH3)2), 24.3 (CH2), 24.5 (CH2), 49.3
3
(NCH2), 51.8 (NCH2), 60.7 (OCH3), 95.3 (t, JPC ) 3.8 Hz, Cꢀ),
trans-(Trifluoroacetato)bis(triphenylphosphine)(3-dimethylamino-
3-methoxy-1,2-propadienylidene)palladium(II) Trifluoromethane-
sulfonate (10a-OTf). The synthesis of 10a-OTf from 0.49 g (0.58
mmol) of 9a and 0.07 mL (0.62 mmol) of MeOTf in 30 mL of
CH2Cl2 was carried out analogously to 3a-OTf. Recrystallization
from mixtures of CH2Cl2 and pentane afforded 0.52 g (0.52 mmol,
90%) of pure 10a-OTf as a colorless powder. 1H NMR (400 MHz,
CD2Cl2): δ 2.46 (s, 3H, NCH3), 2.80 (s, 3H, NCH3), 3.03 (s, 3H,
1
2
120.8 (q, JCF ) 320.0 Hz, CF3), 147.1 (t, JPC ) 11.6 Hz, CR),
151.1 (Cγ). 31P NMR (162 MHz, CDCl3): δ 45.1. IR (CH2Cl2):
ν(CCC) 2086 cm-1; ν(CO) 1612 cm-1. UV-vis (CH2Cl2): λmax (nm)
(log ꢀ) 280 (4.365). FAB-MS: m/z (%) 644 (70) [(M - OTf)+],
483 (65) [(M - OTf - PPh3)+], 403 (13) [(M - OTf - PPh3 -
Br)+]. Anal. Calcd for C27H53BrF3NO4P2PdS (793.05): C, 40.89;
H, 6.74; N, 1.77. Found: C, 40.85; H, 7.19; N, 1.54.
OCH3), 7.38-7.47 (m, 18H, ArH), 7.58-7.65 (m, 12H, ArH). 13
C
trans-Bromobis[tris(4-methoxyphenyl)phosphine](3-N,N-tetram-
ethyleneamino-3-oxy-1-propynyl)palladium(II) (7b). The synthesis
of 7b from 0.42 g (0.50 mmol) of 2b and 0.39 g (1.10 mmol, 2.2
equiv) of P(C6H4OMe-4)3 in 30 mL of CH2Cl2 was carried out
analogously to 5a. The crude product was purified by column
chromatography using a petroleum ether/CH2Cl2/acetone mixture.
Yield: 0.37 g (0.37 mmol; 74%) of 7b as a pale yellow powder.
1H NMR (400 MHz, CDCl3): δ 1.40 (m, 2H, CH2), 1.58 (m, 2H,
CH2), 2.32 (t, J ) 6.8 Hz, 2H, NCH2), 3.06 (t, J ) 6.6 Hz, 2H,
NCH2), 3.78 (s, 18H, OCH3), 6.85-6.87 (m, 12 H, ArH), 7.57-7.61
NMR (100 MHz, CD2Cl2): δ 38.0 (NCH3), 41.5 (NCH3), 61.2
(OCH3), 95.6 (Cꢀ), 110.9 (CF3COO), 120.0 (SO3CF3), 128.3 (t, 1JPC
) 25.8 Hz, i-C), 129.3 (t, 3JPC ) 5.8 Hz, m-C), 132.1 (p-C), 134.7
2
3
(t, JPC ) 6.7 Hz, o-C), 137.9 (t, JPC ) 5.7 Hz, CR), 153.7 (Cγ),
172.8 (CF3COO). 31P NMR (162 MHz, CD2Cl2): δ 25.9. IR (THF):
ν(CCC) 2102 cm-1; ν(CO) 1678 cm-1. UV-vis (CH2Cl2): λmax (nm)
(log ꢀ) 251 (4.359), 307 (4.528). FAB-MS: m/z (%) 855 (13) [(M
- OTf)+], 592 (80) [(M - OTf - PPh3)+], 478 (39) [(M - OTf -
PPh3
-
CF3COO)+]. Anal. Calcd for C45H39F6NO6P2-
(m, 12 H, ArH). 13C NMR (100 MHz, CDCl3): δ 24.5 (CH2), 24.9
PdS · 0.5CH2Cl2 (1004.23): C, 52.21; H, 3.85; N, 1.34. Found: C,
51.94; H, 4.07; N, 1.44.
3
(CH2), 44.1 (NCH2), 47.0 (NCH2), 55.1 (OCH3), 104.5 (t, JPC
)
3
3.5 Hz, Pd-Ct C), 109.2 (t, JPC ) 9.0 Hz, Pd-Ct C), 113.5
trans-(Trifluoracetato)bis(triphenylphosphine)(3-dimethylamino-
3-methoxy-1,2-propadienylidene)palladium(II) Tetrafluoroborate
(10a-BF4). The synthesis of 10a-BF4 from 0.47 g (0.56 mmol) of
9a and 99 mg (0.67 mmol, 1.2 equiv) of [Me3O]BF4 in 30 mL of
2
(ArC), 122.7 (t, JPC ) 27.8 Hz, ArC), 136.3 (ArC), 153.1
(C(O)NC4H8), 161.1 (ArC). 31P NMR (162 MHz, CDCl3): δ 20.2.
IR (CH2Cl2): ν(CCC) 2114 cm-1. UV-vis (CH2Cl2): λmax (nm) (log

354 Organometallics, Vol. 28, No. 1, 2009
Kessler et al.
CH2Cl2 was carried out analogously to 3a-OTf. Yield: 0.45 g (0.48
mmol; 86%) of 10a-BF4 as an off-white powder. H NMR (400
1.515 g cm-3, F(000) ) 2248, µ ) 0.733 mm-1, 2θmax ) 53.7°,
index ranges -14 e h e 14, -29 e k e 29, -23 e l e 22, 70 118
data: (10 300 unique), R(int) ) 0.0879, 586 parameters, R1 (I >
2σ(I)) ) 0.0406, wR2 ) 0.0959, goodness of fit on F2 1.023, ∆Fmax
1
MHz, CDCl3): δ 2.55 (s, 3 H, NCH3), 2.89 (s, 3 H, NCH3), 3.10
(s, 3 H, OCH3), 7.49-7.57 (m, 18 H, ArH), 7.68-7.72 (m, 12 H,
ArH). 13C NMR (100 MHz, CD2Cl2): δ 38.0 (NCH3), 41.7 (NCH3),
(∆Fmin) ) 1.132 (-0.975) e Å-3
.
1
3
Single crystals suitable for an X-ray structural analysis of 5b
were grown from CDCl3 and those of 10a-BF4 by slow diffusion
of hexane into a concentrated solution of 10a-BF4 in CH2Cl2 at 4
°C. The measurements were performed at 100(2) K with a crystal
mounted on a glass fiber on a Stoe IPDS II diffractometer (graphite
monochromator, Mo KR radiation, λ ) 0.710 73 Å). The structures
were solved by direct methods using the SHELX-97 program
package.21 The positions of the hydrogen atoms were calculated
by assuming ideal geometry, and their coordinates were refined
together with those of the attached carbon atoms as the riding model.
All other atoms were refined anisotropically.
61.3 (OCH3), 128.4 (t, JPC ) 25.9 Hz, i-C), 129.4 (t, JPC ) 5.7
2
Hz, m-C), 132.2 (p-C), 134.9 (t, JPC ) 6.4 Hz, o-C), 153.8 (Cγ);
CR, Cꢀ, CF3COO not observed. 31P NMR (162 MHz, CD2Cl2): δ
26.2. IR (THF): ν(CCC) 2103 cm-1; ν(CO) 1678 cm-1. UV-vis
(CH2Cl2): λmax (nm) (log ꢀ) 307 (4.450). FAB-MS: m/z (%) 854
(33) [(M - BF4)+], 663 (100) [(M - BF4 - CF3COO - Ph)+],
631 (49) [(M - BF4 - CF3COO - CCC(OMe)NMe2)+], 592 (68)
[(M - BF4 - PPh3)+], 479 (37) [(M - BF4 - PPh3 - CF3COO)+],
369 (82) [(M - BF4 - PPh3 - CF3COO - CCC(OMe)NMe2)+].
Anal. Calcd for C44H39BF7NO3P2Pd (941.96): C, 56.10; H, 4.17;
N, 1.49. Found: 56.03; H, 4.22; N, 1.42.
X-ray Structural Analysis of 5b and 10a-BF4. Data for 5b:
C25H50BrNOP2Pd · CDCl3, Mr ) 748.28, monoclinic, space group
P21/c, a ) 8.9048(18) Å, b ) 11.445(2) Å, c ) 32.830(7) Å, ꢀ )
91.24(3)°, V ) 3345.1(12) Å3, Z ) 4, dcalcd )1.486 g cm-3, F(000)
) 1536, µ ) 2.104 mm-1, 2θmax ) 51.3°, index ranges -10 e h
e 10, -13 e k e 13, -39 e l e 39, 36 114 data (6273 unique),
R(int) ) 0.0931, 319 parameters, R1 (I > 2σ(I)) ) 0.0343, wR2
) 0.0776, goodness of fit on F2 1.042, ∆Fmax (∆Fmin) ) 0.649
Acknowledgment. Support of this work by the Wacker-
Chemie GmbH (gift of chemicals) is gratefully acknowledged.
Supporting Information Available: CIF files of the complexes
5b and 10a-BF4 and tables giving the bond distances, bond angles,
and torsion angles of 5b and 10a-BF4. This material is available
free of charge via the Internet at http://pubs.acs.org.
(-0.855) e Å-3
.
OM800843E
Data for 10a-BF4: C46H43BCl4F7NO3P2Pd, Mr ) 1111.76, mono-
clinic, space group P21/n, a ) 11.612(2) Å, b ) 23.143(5) Å, c )
(21) Sheldrick, G. M. SHELXTL-97, Programs for Crystal Structure
Analysis; University of Go¨ttingen, Go¨ttingen, Germany, 1997.
18.136(4) Å, ꢀ ) 90.71(3)°, V ) 4873.5(17) Å3, Z ) 4, dcalcd
)