Palladium Alkyl complexes containing β-Phosphonato - Phosphine P,O Ligands and their reactivity toward CO-Ethylene or -Acrylate insertion

Article abstract of DOI:10.1021/om801020e

Neutral and cationic square-planar Pd(II) complexes containing the β-phosphonato-phosphine ligand rac-Ph₂PCH(Ph)P(O)(OEt) ₂ (1) or the new α-silyl-phosphonato-phosphine ligand Ph ₂PCH(SiMe₃)-P(O)(OMe)₂ (4) have been prepared. Reaction of 4 with [Pd(μ-Cl)(dmba)]₂ (dmba = o-C₆H ₄CH₂NMe₂) afforded an equilibrium mixture of [Pd(dmba){Ph₂PCH(SiMe₃)P(O)(OMe)₂}]Cl (5) and [PdCl(dmba){Ph₂PCH(SiMe₃)P(O)(OMe)₂}] (5 ), which illustrates the hemilabile behavior of the ligand in this system. From the stepwise insertion reaction of CO and ethylene into the Pd - C bond of [PdCKMe) {Ph₂PCH(Ph)P(O)(OEt)₂ }] (2a), the metallacyclic complex [Pd{CH₂CH₂C(O)Me{Ph₂PCH(Ph)P(O)-(OEt) ₂][BF₄] (10) was obtained which features the first acetyl - ethylene coupling product containing a phosphine - phosphonate ligand. Chloride abstraction from 2a led to the cationic complex [PdMe(NCMe) {Ph ₂PCH(Ph)P(O)(OEt)₂ }][BF₄] (8), which reacted sequentially with CO and methyl acrylate to afford [Pd{CH[C(O)OMe][CH ₂C(O)Me]} {Ph₂PCH(Ph)P(O)(OEt)₂}][BF ₄] (11). The reaction between 8 and the P,O-ligand Ph ₂PNHC(O)Me resulted in an equilibrated ligand exchange where the heteroleptic system is preferred over the mixture of the two homoleptic complexes. The complexes 2a and 10 · 1/2CHC1₃ have been characterized by X-ray diffraction and represent rare examples of crystal structures showing a (diethyl)methylphosphonate ligand coordinated to a metal center.

Full text of DOI:10.1021/om801020e

1688
Organometallics 2009, 28, 1688–1696
Palladium Alkyl Complexes Containing ꢀ-Phosphonato-Phosphine
P,O Ligands and Their Reactivity toward CO-Ethylene or -Acrylate
Insertion
Adel Hamada and Pierre Braunstein*
Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), UniVersite´ de Strasbourg,
4 rue Blaise Pascal, F-67070 Strasbourg Cedex, France
ReceiVed October 24, 2008
Neutral and cationic square-planar Pd(II) complexes containing the ꢀ-phosphonato-phosphine ligand
rac-Ph2PCH(Ph)P(O)(OEt)2 (1) or the new R-silyl-phosphonato-phosphine ligand Ph2PCH(SiMe3)-
P(O)(OMe)2 (4) have been prepared. Reaction of 4 with [Pd(µ-Cl)(dmba)]2 (dmba ) o-C6H4CH2NMe2)
afforded an equilibrium mixture of [Pd(dmba){Ph2PCH(SiMe3)P(O)(OMe)2}]Cl (5) and
[PdCl(dmba){Ph2PCH(SiMe3)P(O)(OMe)2}] (5′), which illustrates the hemilabile behavior of the ligand
in this system. From the stepwise insertion reaction of CO and ethylene into the Pd-C bond of
[PdCl(Me){Ph2PCH(Ph)P(O)(OEt)2}] (2a), the metallacyclic complex [Pd{CH2CH2C(O)Me{Ph2PCH(Ph)P(O)-
(OEt)2][BF4] (10) was obtained which features the first acetyl-ethylene coupling product containing a
phosphine-phosphonate ligand. Chloride abstraction from 2a led to the cationic complex
[PdMe(NCMe){Ph2PCH(Ph)P(O)(OEt)2}][BF4] (8), which reacted sequentially with CO and methyl
acrylate to afford [Pd{CH[C(O)OMe][CH2C(O)Me]}{Ph2PCH(Ph)P(O)(OEt)2}][BF4] (11). The reaction
between 8 and the P,O-ligand Ph2PNHC(O)Me resulted in an equilibrated ligand exchange where the
heteroleptic system is preferred over the mixture of the two homoleptic complexes. The complexes 2a
and 10 · 1/2CHCl3 have been characterized by X-ray diffraction and represent rare examples of crystal
structures showing a (diethyl)methylphosphonate ligand coordinated to a metal center.
hydrosoluble compounds.11 It is also interesting to note that
Introduction
condensation processes involving phosphonate functions have
been applied to the preparation of catalysts11b,d or to the
Heterodifunctional P,O ligands combine a soft phosphorus
donor moiety with a harder oxygen functionality and are
receiving much attention not only as potentially hemilabile
ligands but also because of the interesting and often unique
properties and reactivity of their transition metal complexes.1-6
Among the large number of known metal complexes with
P,O ligands, those which associate a phosphine and a
phosphonate, phosphinate, or phosphate function are rela-
tively scarce and have mainly been described with one or
more phosphonate groups -P(O)(OR)2 (R ) alkyl, aryl) as
the oxygen donor function.7-10 The transformation of phos-
phonic esters into the corresponding acids -P(O)(OH)2 or salts
-P(O)(OM)2 (M ) Na, Li...) allows the formation of
immobilization of metal complexes.11b,d,12-17
We have recently described Pd(II) complexes in which a
heterofunctional enolphosphato-phosphine Ph2PCHdCPh-
[OP(O)(OR)2]7 or the ꢀ-phosphonatophosphine Ph2PCH(Ph)-
P(O)(OEt)2 (1) behaved as a rigid and/or hemilabile P,O
chelate.9
The chelating ability of 1 was compared to that of other
potential P,O chelates, and on the basis of competition experi-
ments, 1 was found to be a stronger chelate than the related
(11) See, e.g.: (a) Glo¨ckler, J.; Klu¨tzke, S.; Meyer-Zaika, W.; Reller,
A.; Garcia-Garcia, F. J.; Strehblow, H.-H.; Keller, P.; Rentschler, E.; Kla¨ui,
W. Angew. Chem, Int. Ed. 2007, 46, 1164. (b) Schull, T. L.; Henley, L.;
Deschamps, J. R.; Butcher, R. J.; Maher, D. P.; Klug, C. A.; Swider-Lyons,
K.; Dressick, W. J.; Bujoli, B.; Greenwood, A. E.; Byington Congiardo,
L. K.; Knight, D. A. Organometallics 2007, 26, 2272. (c) Schull, T. L.;
Butcher, R. J.; Dressick, W. J.; Brandow, S. L.; Byington, L. K.; Knight,
D. A. Polyhedron 2004, 23, 1375. (d) Harper, B. A.; Knight, D. A.; George,
C.; Brandow, S. L.; Dressick, W. J.; Dalcey, C. S.; Schull, T. L. Inorg.
Chem. 2003, 42, 516.
(12) (a) Poojary, D. M.; Zhang, B.; Bellinghausen, P.; Clearfield, A.
Inorg. Chem. 1996, 35, 5254. (b) Clearfield, A. Dalton Trans. 2008, 6089.
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2008, 9, 1838.
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M. K.; Dobrynin, A. B.; Litvinov, I. A. Z. Anorg. Allg. Chem. 2007, 633,
1995.
* To whom correspondence should be addressed. Fax: (+33) (0)3 90
24 13 22. E-mail: braunstein@chimie.u-strasbg.fr.
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1999, 48, 233. (b) Braunstein, P.; Naud, F. Angew. Chem., Int. Ed. 2001,
40, 680.
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C. F.; Suranna, G.-P. J. Mol. Catal. A: Chem. 2000, 157, 41.
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Kuhn, P.; Se´meril, D.; Jeunesse, C.; Matt, D.; Neuburger, M.; Mota, A.
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10.1021/om801020e CCC: $40.75
2009 American Chemical Society
Publication on Web 02/27/2009

Palladium Alkyl Complexes
Organometallics, Vol. 28, No. 6, 2009 1689
It is interesting to note that with the related diphosphine-
phosphonate ligands (Ph2P)2CHP(O)(OR)2 (R ) Me, Ph),
spontaneous deprotonation of the PCHP moiety was observed
with Pd(II) precursor complexes containing a basic enough
ligand, such as a methyl or a cyclometalated dmba chelate
(dmbaH ) C6H5CH2NMe2).28 Here, in contrast, the Pd-bound
methyl ligand does not promote the deprotonation of ligand 1.
Complex 2a is related to the P,O diphosphine monooxide
keto- or amido-phosphine P,O-ligands Ph2PCH2C(O)Ph18 and
Ph2PCH2C(O)NPh2,19 respectively. We describe here organo-
metallic Pd(II) methyl complexes with the P,O chelate 1 and,
as a continuation of previous work in this area,20-23 the
formation of metallacyclic complexes resulting from the initial
CO-ethene or CO-methyl acrylate insertions into their Pd-Me
bond.
Pd(II) complex [PdMeCl{Ph2PCH2P(O)Ph2}] (2b)29 and to the
Pt(II) complex with ligand 1, [PtMeCl{Ph2PCH(Ph)P(O)-
(OEt)2}] (2c).24 The geometry around the metal centers is square
planar and a comparison between the structural parameters of
2a, 2b and 2c is provided in Table 1.
Results and Discussion
The Pd(II) complex [PdCl(Me){Ph2PCH(Ph)P(O)(OEt)2}]
(2a) was obtained in 93% yield by the reaction of the
ꢀ-phosphonatophosphine 1 with [PdCl(Me)(COD)] (COD )
1,5-cyclooctadiene, C8H12) (eq 1). Its IR ν(PO) absorption band
at 1186 cm-1 and its 31P NMR spectrum (AB spin system,
2+3J(P,P) ) 45 Hz) are consistent with the structure drawn.
The Pd-P distance of 2.219(1) Å in 2a is in agreement with
literature data for related P,O systems such as the diphosphine
monoxide complex 2b29 and is shorter than Pd-P bonds for
dppm complexes in general,30 whereas the Pd-O distance of
2.265(2) Å is significantly longer. This is consistent with the
trans influence of the methyl group, which forms a strong bond
to palladium as indicated by the Pd-C(1) bond length of
2.029(3) Å. This value is at the lower limit for Pd-C(sp3) bonds
and is much shorter than the sum of the covalent radii of Pd(II)
and C(sp3) (2.07 Å). The Pd-Cl distance of 2.362(1) Å falls in
the expected range for a trans Cl-Pd-P arrangement.18,29,30
Although no classical intermolecular hydrogen bonding was
detected in complex 2a, non-conventional C(23)-H(23) · · · Cl(1)
hydrogen bonds are present (Figure 2) that involve a Cl ligand
and a C-H atom of a POCH2CH3 methylene group. Furthermore,
intermolecular interactions exist between Cl(1) and the
PC(2)H(2)P hydrogen and the phenyl C(4)-H(4) hydrogen
atoms.
The dimethyl(diphenylphosphino)(trimethylsilyl)methyl-
phosphonate ligand 4 (eq 2), which is related to 1, was
synthesized from the silylphosphonate 3 (prepared by Savignac’s
procedure using methyl(dimethyl)phosphonate, see Experimental
Section),31 by deprotonation with LDA or n-BuLi and treatment
of the resulting anion with PPh2Cl. Its 31P{1H} NMR spectrum
in CDCl3 consisted of two doublets at δ -16.8 and 33.0 (2J(P,P)
) 19 Hz) for the phosphine and the phosphonate functions,
respectively. These values are similar to those found for its
The structure of 2a in the solid state was established by X-ray
diffraction. An ORTEP view of one molecule of 2a is presented
in Figure 1, and selected bond distances and angles are given
in Table 1. The PdO oxygen and the phosphine donor atoms
chelate the metal center and, as expected for a Pd(II) complex
with d8 electronic configuration, the overall coordination
geometry around the metal is square-planar. The trans relation-
ship between the soft phosphine and Cl ligands and the harder
oxygen and methyl groups, respectively, is consistent with
previous findings with the Pt analog of 2a24 and in related
systems.22,25-27 The phenyl group attached to the carbon atom
R to the phosphorus atoms is almost orthogonal to the metal
coordination plane.
(18) Bouaoud, S. E.; Braunstein, P.; Grandjean, D.; Matt, D.; Nobel,
D. Inorg. Chem. 1986, 25, 3765.
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2000, 2205.
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Figure
1.
ORTEP
view
of
one
molecule
of
[PdCl(Me){Ph2PCH(Ph)P(O)(OEt)2}] (2a). Thermal ellipsoids en-
close 50% of the electron density (H atoms are not shown).

1690 Organometallics, Vol. 28, No. 6, 2009
Hamada and Braunstein
Table 1. Comparison of Selected Structural Data between Complexes 2a, 2b, and 2c
2a
2b
2c
Pd-C(1)
2.029(3)
2.362(1)
2.219(1)
2.265(2)
178.3(1)
176.4(2)
89.8(2)
2.024(6)
2.378(2
2.204(2)
2.2761(4)
174.8(2)
171.69(6)
90.6(2)
Pt-C(1)
2.0316(4)
2.389(2)
2.145(2)
2.231(5)
176.40(1)
-
Pd-Cl
Pt-Cl
Pd-P(1)
Pd-O(1)
C(1)-Pd-O(1)
Cl-Pd-P(1)
C(1)-Pd-Cl
P(1)-Pd-O(1)
Pt-P(1)
Pt-O(1)
C(1)-Pt-O(1)
-
C(1)-Pt-Cl
P(1)-Pt-O(1)
88.92(6)
89.8(1)
87.77(6)
89.2(1)
diethyl analog.32 In the H NMR spectrum of 4 (CDCl3), the
SiMe3 protons give rise to a signal at 0.05 ppm, the PCHP proton
to a doublet of doublets centered at 2.45 ppm (2J(PO,H) ) 22.2
different stereoelectronic properties and trans-effect/influence
and by their potential hemilabile behavior in metal complexes.33
In 2002, Drent et al. reported the use of alkoxyarylphosphine
ligands bearing sulfonic acid groups that, when combined in
situ with palladium acetate or [Pd2(dba)3], were able to promote
the formation of nonalternating polyketones from carbon
monoxide and ethylene.65,66 Furthermore, the copolymerization
of ethylene and methyl acrylate afforded copolymers with the
1
2
Hz, J(P,H) ) 1.2 Hz), whereas the magnetically inequivalent
MeO groups resonate as two doublets at 3.32 and 3.47 ppm
(3J(PO,H) ) 11.1 Hz). In the IR spectrum (KBr), the ν(PdO)
vibration was found at 1248 s cm-1
.
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For comparison, 4 was reacted with [Pd(µ-Cl)(dmba)]2 (dmba
) o-C6H4CH2NMe2) in a 2:1 ratio, which afforded a yellow
1
solid. The presence of two species was confirmed by H and
31P{1H} NMR spectroscopy. At room temperature, the 31P{1H}
NMR spectrum (CDCl3) consisted of two pairs of doublets at δ
34.2 (2+3J(P,P) ) 34 Hz) and 29.5 (2+3J(P,P) ) 34 Hz) and at
δ 28.2 (2J(P,P) ) 7 Hz), and 26.3 (2J(P,P) ) 7 Hz) which are
suggested to correspond to the PdO and P resonances of
[Pd(dmba){Ph2PCH(SiMe3)P(O)(OMe)2}]Cl (5) and [PdCl-
(dmba){Ph2PCH(SiMe3)P(O)(OMe)2}] (5′), respectively (for the
31P{1H} NMR spectrum, see Figure S-1, Supporting Informa-
tion). The smaller value of the J(PP) coupling constant in the
monodentate vs the chelate form of the ligand is consistent with
previous observations.9 The hemilability of coordinated 4
(Scheme 1) would result in solution in a slow equilibrium on
the NMR time scale between 5 and 5′.33
(48) Sen, A. Catalytic Synthesis of Alkene-Carbon Monoxide Copoly-
mers; Kluwer Academic: Dordrecht, The Netherlands, 2003.
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B. W.; White, A. H. Dalton. Trans. 2004, 3251.
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Addition of AgBF4 to the 5/5′ mixture in a NMR tube led to
anion exchange and induced the quantitative formation of the
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van Leeuwen, P. W. N. M. Chem. Commun. 2005, 3478.
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cationic complex [Pd(dmba){Ph2PCH(SiMe3)P(O)(OMe)2}]-
[BF4] (6) (see Experimental Section and Figure S-2, Supporting
Information).
1. CO/Olefin Insertion into a Pd-Me Bond. The palladium
catalyzed alternating insertion of carbon monoxide and olefins
leads to the formation of polyketones, and theoretical and
experimental studies have established the kinetic and thermo-
dynamic factors that control the chain growth by alternating
CO and olefin migratory insertion into the metal-alkyl or
metal-acyl bond, respectively.5,34-51 Palladium complexes
containing P,P chelating ligands are effective in CO/
ethylene42,45-47,52-55 and CO/propylene35,56 copolymerization,
whereas aromatic olefins, such as styrene and its derivatives,
are efficiently copolymerized when N,N ligands chelate the
palladium center.57-61 The interest for unsymmetrical bidentate
ligands, particularly of the P,N-2,4,62 and P,O types,6,20,22,25,63,64
is motivated by the simultaneous presence of donor groups with
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Palladium Alkyl Complexes
Organometallics, Vol. 28, No. 6, 2009 1691
Figure 2. View of the intermolecular interactions in the solid-state structure of 2a. The square-brackets indicate the directions of the
polymeric network. Symmetry operations: (i) x, y, -1+z; (ii) 0.5-x, y, -0.5+z.
Scheme 1
acrylate units statistically placed in the polyethylene chain. This
was the first example of transition metal catalysis providing a
low temperature/low pressure route to such copolymers.
1.1. CO Insertion into the Pd-Me Bond of a Neutral
Pd(II) Complex. Insertion of CO into the Pd-Me bond of
complex 2a in CH2Cl2 under mild conditions resulted in the
formation of the acetyl complex 7 (eq 3), which is characterized
by a ν(CO) absorption at 1711 cm-1 in the IR spectrum and by
31P{1H} NMR resonances at δ 23.6 (d, 2+3J(P,P) ) 44 Hz, PPh2)
and 34.1 (d, 2+3J(P,P) ) 44 Hz, PO). This indicates that the
acyl ligand resides in cis position relative to the phosphine
donor, like the methyl ligand in 2a. Complex 7 did not insert
ethylene under usual conditions (see eq 3).
1.2. Stepwise Ethene/methylacrylate/CO Insertion
into the Pd-Me Bond of Cationic Pd(II) Complexes
Containing a P,O Chelate. We have previously structurally
characterized Pd(II) complexes resulting from CO/ethene inser-
tion and containing a P,O or a P,N ligand.20-22,25 and consider-
The acetyl complex 9 was prepared either from 7 by chloride
abstraction in the presence of MeCN or by carbonylation
reaction of 8 (Scheme 2). It is characterized by a ν(CO) vibration
at 1716 cm-1 in the IR spectrum and two doublets in the 31P{1H}
NMR spectrum at δ 26.5 (PPh2, 2+3J(P,P) ) 40 Hz) and 35.6
(PO,2+3J(P,P) ) 40 Hz). Only one isomer of the acetyl complex
was observed, in which the C(O)Me group is cis to the P donor
atom, as indicated by the typical shift of the 31P resonance of
the phosphine donor when going from 8 to 9 (∆δ ) -11 ppm).
The stability of complex 9 in the solid state or in solution
contrastswithobservationsmadewithothercationicacetyl-palladium
complexes which rapidly decomposed.38,67
ing the interest in the copolymerization of olefins with polar
monomers, we have also structurally characterized Pd(II)
complexes resulting from insertion of methyl acrylate into a
Pd(II)-acetyl bond.22,23 Expecting for a cationic complex a
higher reactivity than that of the corresponding neutral complex,
we
have
prepared
[PdMe(NCMe){Ph2PCH(Ph)P(O)-
(OEt)2}][BF4] (8) by reaction of 2a with one molar equiv of
AgBF4 in a 50/50 mixture of acetonitrile and dichloromethane
(Scheme 2). At room temperature, its 31P{1H} NMR spectrum
in CDCl3 showed two doublets at δ 37.4 (P, 2+3J(P,P) ) 40
Hz) and 38.8 (PO, 2+3J(P,P) ) 40 Hz).

1692 Organometallics, Vol. 28, No. 6, 2009
Hamada and Braunstein
Scheme 2. All Reactions Were Performed at Room
Temperature
Figure 3. View of the molecular structure of the cation in complex
10 · 1/2CHCl3 (H atoms are not shown). Selected bond lengths [Å]
and angles [deg]: Pd-P(1) 2.208(2), Pd-O(1) 2.201(5), Pd-C(24)
2.008(7), Pd-(O4) 2.132(4), C(24)-(25) 1.54(1), C(25)-C(26)
1.49(1), C(26)-O(4) 1.247(8), C(26)-C(27) 1.49(1), P(1)-C(2)
1.858(6), P(2)-C(2) 1.812(7); P(1)-Pd-O(4) 175.4(2), P(1)-
Pd-O(1) 91.4(2), P(1)-C(2)-P(2) 106.0(3), C(24)-Pd-O(4)
82.9(2), O(1)-Pd-O(4) 93.0(2).
acrylate, a reaction of high current interest (Scheme 2).20,21,66,70
This reaction is more demanding than that of ethylene, but it
was found to be much faster than recently observed for related
Pd(II) complexes with P,O ligands.20 It occurred within 1 h at
ambient temperature and pressure and led to the formation of
complex 11. Owing to the presence of two stereogenic centers
in this 2,1-insertion product, it was obtained as a 65/35 mixture
of diastereoisomers, as indicated by 31P{1H} NMR (two AB
Insertion of ethylene into the Pd-acyl bond of 9 occurred at
ambient temperature and pressure and afforded complex 10. The
reaction was completed after ca. 1 h. Coordination of the ketonic
oxygen to palladium (ν(CO) ) 1637 cm-1) leads to a stabilizing
chelation that disfavors ꢀ-hydrogen elimination. Complex 10
is stable at room temperature for several minutes in solution
and for months in the solid state, in contrast to other chelated
1
spin systems) and H NMR spectroscopy (see Experimental
Section).
A solution of the P,O chelate complex 10 in CH2Cl2 was
purged with CO to form the R-keto chelate complex 12 (Scheme
1). Although the desired complex could not be isolated pure,
the IR spectrum showed two ν(CdO) vibrations at 1659 and
1708 cm-1 assigned to the coordinated ketonic and acyl CO,
respectively.
complexes with a P,P or a P,O chelate.68,69 The H NMR
1
spectrum of 10 shows for the CH2 protons of the inserted
ethylene second order multiplets (for the Pd-CH2 and CH2CdO
protons), consistent with the presence of a stereogenic center
in the molecule (see Experimental Section). This complex
features the first acetyl-ethylene coupling product containing
a phosphine-phosphonate ligand.
2. Competing Chelation Experiments. To evaluate the
chelating ability of ligand 1 in the presence of another P,O donor
The structure of 10 in 10 · 1/2CHCl3 was determined by X-ray
diffraction (Figure 3). The Pd(II) center is chelated by P,O and
C,O ligands, with a cis arrangement of the two oxygen atoms
that forms a O(1)-Pd-O(4) angle of 93.0(2)°.
The phenyl group at C(2) assumes a different orientation in
2a and 10 (see Figure 4). In complex 2a, it occupies an axial
site with respect to the chelate mean plane whereas in 10, it is
in an equatorial position. The angle between the C(2)-Cipso bond
and the P1-C(2)-P2 plane is 127.70(1)° and 135.69(1)° in 2a
and 10, respectively. The Pd-C(24) distance of 2.008(7) Å
compares well with that in related molecules.20-22
(70) (a) Johnson, L. K.; Mecking, S.; Brookhart, M J. Am. Chem. Soc.
1996, 118, 267. (b) Mecking, S.; Johnson, L. K.; Wang, L.; Brookhart, M.
J. Am. Chem. Soc. 1998, 120, 888. (c) Gibson, V. C.; Tomov, A. Chem.
Commun. 2001, 1964. (d) Reddy, K. R.; Surekha, K.; Lee, G.-H.; Peng,
S.-M.; Chen, J.-T.; Liu, S.-T Organometallics 2001, 20, 1292. (e) Michalak,
A.; Ziegler, T. Organometallics 2001, 20, 1521. (f) Michalak, A.; Ziegler,
T. J. Am. Chem. Soc. 2001, 123, 12266. (g) Liu, S.; Elyashiv, S.; Sen, A.
J. Am. Chem. Soc. 2001, 123, 12738. (h) Drent, E.; van Dijk, R.; van Ginkel,
R.; van Oort, B.; Pugh, R. I. Chem. Commun. 2002, 744. (I) Deubel, D. V.;
Ziegler, T. Organometallics 2002, 21, 1603. (j) Michalak, A.; Ziegler, T.
Organometallics 2003, 22, 2660. (k) Albe´niz, A. C.; Espinet, P.; Lo´pez-
Ferna´ndez, R. Organometallics 2003, 22, 4206. (l) He, X.; Yao, Y.; Luo,
X.; Zhang, J.; Liu, Y.; Zhang, L.; Wu, Q. Organometallics 2003, 22, 4952.
(m) Waltman, A. W.; Younkin, T. R.; Grubbs, R. H. Organometallics 2004,
23, 5121. (n) Szabo, M. J.; Jordan, R. F.; Michalak, A.; Piers, W. E.; Weiss,
T.; Yang, S.-Y.; Ziegler, T. Organometallics 2004, 23, 5565. (o) Popeney,
C.; Guan, Z. Organometallics 2005, 24, 1145. (p) Kochi, T.; Yoshimura,
K.; Nozaki, K. Dalton Trans. 2006, 25. (q) Borkar, S.; Yennawar, H.; Sen,
A. Organometallics 2007, 26, 4711. (r) Sen, A.; Borkar, S. J. Organomet.
Chem. 2007, 692, 3291. (s) Popeney, C. S.; Camacho, D. H.; Guan, Z.
J. Am. Chem. Soc. 2007, 129, 10062. (t) Berkenfeld, A.; Mecking, S. Angew.
Chem., Int. Ed. 2008, 47, 2538. (u) Brasse, M.; Ca´mpora, J.; Palma, P.;
Alvarez, E.; Cruz, V.; Ramos, J.; Reyes, M. L. Organometallics 2008, 27,
4711. (v) Nakamura, A.; Munakata, K.; Kochi, T.; Nozaki, K. J. Am. Chem.
Soc. 2008, 130, 8128.
After the insertion of ethylene into the palladium-acetyl bond
of the cationic complex 9, we examined the insertion of methyl
(67) 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.
(68) Zuideveld, M. A.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.;
Klusener, P. A. A.; Stil, H. A.; Roobeek, C. F. J. Am. Chem. Soc. 1998,
120, 7977.
(69) Braunstein, P.; Fryzuk, M. D.; Dall, M. L.; Naud, F.; Rettig, S. J.;
Speiser, F. J. Chem. Soc., Dalton Trans. 2000, 1067.

Palladium Alkyl Complexes
Organometallics, Vol. 28, No. 6, 2009 1693
former case. The first acetyl-ethylene coupling pro-
duct
containing
a
phosphine-phosphonate
ligand,
[Pd{CH2CH2C(O)Me{Ph2PCH(Ph)P(O)}(OEt)2}][BF4](10), was
obtained from the stepwise insertion reaction of CO and ethylene
into the Pd-C bond of [PdCl(Me){Ph2PCH(Ph)P(O)(OEt)2}]
(2a). The cationic complex [PdMe(NCMe){Ph2PCH(Ph)P(O)-
(OEt)2}][BF4] (8) reacted sequentially with CO and methyl
acrylate to afford [Pd{CH[C(O)OMe][CH2C(O)Me]}-
{Ph2PCH(Ph)P(O)(OEt)2}][BF4] (11). However, further insertion
reaction of ethylene into the newly formed Pd-C bond was
not observed under our experimental conditions.
Experimental Section
General Considerations. All the reactions and manipulations
were carried out under an inert atmosphere of purified nitrogen
using standard Schlenk tube techniques. Solvents were purified over
appropriate drying agents and freshly distilled under nitrogen before
use. Nitrogen (Air Liquide, R-grade) was passed through BASF
R3-11 catalyst and molecular sieves columns to remove residual
oxygen and water. Elemental C, H, and N analysis were performed
by the “Service de microanalyses” (Universite´ de Strasbourg,
France). Infrared spectra were recorded in the 4000-400 cm-1 range
in the solid state (KBr) on a Bruker IF66FT or Perkin-Elmer 1600
Series FTIR or, pure, on a Thermo Nicolet 6700 instrument,
equipped with a SMART Orbit Diamond ATR accessory. The 1H,
31P{1H}, and 13C{1H} NMR spectra were recorded at 300.13,
121.49, and 75.5 MHz, respectively.
Figure 4. Views of the comparative orientations of the C(2)-bound
phenyl group in the PC(Ph)P moiety in complexes 2a (top) and 10
(bottom).
Synthesis. The compounds rac-Ph2PCH(Ph)P(O)(OEt)2,9
Ph2PNHC(O)Me,19 and [PdCl(Me)(COD)]71 (COD ) 1,5-cyclooc-
tadienne, C8H12) and [Pd(µ-Cl)(dmba)]272 were prepared according
to literature procedures.
ligand, we first reacted a molar equiv of 1 with complex 8 and
obtained complex 13. A dynamic, temperature-dependent in-
tramolecular dynamic equilibrium 13h13′ takes place (Scheme
3), as indicated by variable-temperature 31P{1H} NMR spec-
troscopy (see Figure S-3, Supporting Information), where the
two phosphonato PdO groups alternatively bind to the Pd
center. This mutual exchange of the two PdO functions is
facilitated by the proximity of the uncoordinated oxygen atoms
and results in hemilabile bahavior.33 Because of the presence
of two stereogenic centers in the molecule, a mixture of
diastereoisomers was obtained, in an approximate 1:1 ratio, that
we did not attempt to separate. For each diastereoisomer, the
phosphines give rises to a triplet in the dynamic regime owing
to coupling with two PdO functions. At lower temperature, the
PdO resonance remains broad owing to the presence of
diastereoisomers with very similar chemical shifts.
We then reacted the acetamidophosphine ligand
Ph2PNHC(O)Me with 8 in a 1:1 ratio (Scheme 3). This afforded
complex 14, which contains both ligands but with 1 being
chelated to the metal. From this heteroleptic complex, a ligand
exchange reaction affords a mixture of the homoleptic com-
plexes 13 and 15, with 14 being the major species present at
equilibrium (Scheme 3). This indicates that the heteroleptic
system is preferred over the mixture of the two homoleptic ones.
Complex 15 has been reported previously, and it was found
that its monodentate and chelating ligands are in dynamic
exchange, resulting in a broad 31P NMR resonance at δ 60.2
ppm.19
[PdCl(Me){Ph2PCH(Ph)P(O)(OEt)2}] (2a). In a 100 mL Schlenk
tube containing [PdCl(Me)(COD)] (1.30 g, 4.92 mmol) in CH2Cl2
(25 mL) was added Ph2PCH(Ph)P(O)(OEt)2 (1) (2.03 g, 4.92 mmol).
The solution was stirred for 20 min at room temperature and the
solvent was removed under reduced pressure. The beige residue
was washed with diethyl ether (2 × 20 mL) and pentane (2 × 20
mL) and dried in vacuum overnight to afford a beige powder. Yield
1.93 g (93%). Anal. Found: C, 50.83; H, 5.17%. Calcd for
C24H29ClO3P2Pd: C, 50.63; H, 5.13%. X-ray quality crystals were
1
obtained by slow diffusion of pentane into a CH2Cl2 solution. H
NMR (CDCl3): δ 0.91 (t, 3H, 3J(P,H) ) 1.6 Hz, PdCH3), 1.05 (m,
6H, CH3CH2O), 3.91 (dd, 1H, 2J(P,H) ) 1.94 Hz, 2J(PO,H) ) 7.14
Hz, PCHPh), 4.05 (m, 4H, CH3CH2O), 7.08-7.86 (m, 15H,
aromatics); 31P{1H} NMR (CDCl3): AB spin system δA 35.6 (d,
2+3J(P,P) ) 45 Hz, PPh2), δB 36.0 (d, 2+3J(P,P) ) 45 Hz, PO). IR
(KBr): ν(P ) O) 1186 s cm-1
.
(MeO)2P(O)CH2SiMe3 (3). In a 250 mL Schlenk tube containing
a solution of n-BuLi in hexane (20.13 mL, 32.23 mmol, 1.6 M
Aldrich) cooled at -20 °C, was added a solution of diisopropy-
lamine (3.500 g, 32.23 mmol) in THF (30 mL). After the reaction
mixture was stirred for 10 min, a solution of MeP(O)(OMe)2 (2.000
g, 16.11 mmol) in THF (30 mL) was added, and the mixture was
further stirred for 10 min during which the temperature was kept
below -65 °C. It was then cooled again to -78 °C, and a solution
of MeSiCl (1.750 g, 1.98 mL, 16.11 mmol) in THF (20 mL) was
added dropwise. The temperature was then allowed to warm to 0
°C while stirring was maintained. The reaction mixture was
quenched at -20 °C by addition of a degassed 5N HCl solution
In conclusion, we have prepared new square-planar Pd(II)
complexes containing the ꢀ-phosphonato-phosphine ligand rac-
(71) (a) Ru¨lke, R. E.; Ernsting, J. M.; Spek, A. L.; Elsevier, C. J.; van
Leeuwen, P. W. N. M.; Vrieze, K. Inorg. Chem. 1993, 32, 5769. (b) Ladipo,
F. T.; Anderson, G. K. Organometallics 1994, 13, 303.
Ph2PCH(Ph)P(O)(OEt)2
phosphonato-phosphine ligand Ph2PCH(SiMe3)P(O)(OEt)2 (4)
and examples of hemilabile behavior were described in the
(1)
or
the
new
R-silyl-
(72) Cope, A. C.; Friedrich, E. C. J. Am. Chem. Soc. 1968, 90, 909.

1694 Organometallics, Vol. 28, No. 6, 2009
Scheme 3. All Reactions Were Performed at Room Temperature in CH2Cl2
Hamada and Braunstein
until pH 4 was reached. The organic layer was then collected and
the aqueous phase was extracted with diethyl ether (2 × 20 mL).
The combined organic phases were then dried over degassed
MgSO4, the solvent was evaporated under reduced pressure,
affording a liquid compound (yield 2.470 g, 78%). 1H NMR
(CDCl3): δ 0.01 (s, 9H, SiCH3), 0.94 (2H, d, 2J(PO,H) ) 22.0 Hz,
filtration, the volatiles were removed under reduced pressure. The
residue was washed with diethyl ether (2 × 10 mL) and pentane
(2 × 10 mL), which afforded a yellow solid (0.160 g, 78%). Anal.
Found: C, 44.86; H, 5.38; N, 1.98. Calcd for C27H38BF4NO3P2PdSi · 1/
3CH2Cl2: C, 44.60; H, 5.29; N, 1.90. 1H NMR (CDCl3): δ 0.68 (s,
9H, SiMe3), 1.16 (s, 3H, NMe), 1.18 (s, 3H, NMe), AB spin system:
3
2
P(O)CH2Si), 3.53 (6H, d, J(PO,H) ) 11.1 Hz, OCH3); 31P{1H}
2.87 (2J(H,H) ) 5.0 Hz, Me2NCHH), 2.90 J(H,H) ) 5.0 Hz,
NMR (CDCl3): δ 36.8 (s, PO); IR (THF): ν(PdO) 1250 s cm-1
.
Me2NCHH), 3.32 (dd, 1H, 2J(PO,H) ) 16.9 Hz, 2J(P,H) ) 12 Hz,
PCHP), 3.72 (d, 3H, 3J(P,H) ) 1.7 Hz, POMe), 3.75 (d, 3H, 3J(P,H)
) 1.7 Hz, POMe), 6.33-7.96 (14H, m, aromatics); 31P{1H} NMR
(CDCl3): δ 21.1 (d, 2+3J(P,P) ) 29 Hz, PPh2), 44.9 (d, 2+3J(P,P) )
Ph2PCH(SiMe3)P(O)(OMe)2 (4). In a 250 mL Schlenk tube
cooled to -78 °C was placed a solution of n-BuLi in hexane (3.18
mL, 5.09 mmol, 1.6 M Aldrich) to which was added a solution of
Me3SiCH2P(O)(OMe)2 (3) (1.000 g, 5.09 mmol) in THF (20 mL).
The mixture was stirred for 10 min. during which the temperature
was kept below -78 °C, and a solution of Ph2PCl (1.120 g, 0.91
mL, 5.09 mmol) in THF (10 mL) was added. After it was stirred
for 15 min, the mixture was brought back to room temperature
over 10 min, the solvents were eliminated under reduced pressure,
and the solid was washed with hexane (2 × 10 mL). The compound
was extracted with diethyl ether (2 × 20 mL). After filtration and
removal of the volatiles under vacuum, ligand 4 was obtained as a
29 Hz, PO); IR (KBr): ν(PdO) 1178 cm-1
.
[PdCl{C(O)Me}{Ph2PCH(Ph)P(O)(OEt)2}] (7). A CH2Cl2 so-
lution of 2 was placed under a CO atmosphere and stirred at room
temperature for 1 h. The solvent was removed under reduced
pressure and the powder was washed with diethyl ether (2 × 20
mL) and pentane (2 × 20 mL). It was then dried in vacuum
overnight to afford a pale green powder. Anal. Found: C, 50.23;
H, 4.96%. Calcd for C25H29ClO4P2Pd: C, 50.27; H, 4.89%. 1H NMR
4
(CDCl3): δ 1.05 (m, 6H, CH3CH2O), 2.20 (d, J(P,H) ) 1.0 Hz,
1
yellow solid (0.968 g, 50%). H NMR (CDCl3): δ 0.05 (s, 9H,
2
3H, CH3CO), 4.05 (m, 4H, CH3CH2O), 4.22 (dd, 1H, J(P,H) )
2
2
SiMe3), 2.45 (dd, 1H, J(PO,H) ) 22.2 Hz, J(P,H) ) 1.2 Hz,
22.2, 12.7 Hz, PCHPh), 7.13-7.80 (m, 15H, Ph); 31P{1H} NMR
(CDCl3): δ 23.6 (d, 2+3J(P,P) ) 44 Hz, PPh2), 34.1 (d, 2+3J(P,P) )
3
PCHP), 3.32 (d, 3H, J(PO,H) ) 11.1 Hz, POCH3), 3.47 (d, 3H,
3J(PO,H) ) 11.1 Hz, POCH3), 7.20-7.80 ppm (10H, m, aromatics);
44 Hz, PO). IR (KBr): ν(CO) 1711 s cm-1
.
31P{1H} NMR (CDCl3): δ -16.8 (d, 2J(P,P) ) 19 Hz, PPh2), 33.0
(d, J(P,P) ) 19 Hz, PO); IR (KBr): ν(PdO) 1248 cm-1
.
2
[PdMe{NCMe}{Ph2PCH(Ph)P(O)(OEt)2}][BF4] (8). Complex
2 (1.52 g, 2.67 mmol) was dissolved in a 1:1 CH2Cl2/MeCN mixture
(20 mL) and AgBF4 (0.52 g, 2.67 mmol) was added at room
temperature. The reaction mixture was stirred for 2 h. After filtration
and removal of the volatiles under vacuum, the residue was washed
with diethyl ether (2 × 20 mL) and pentane (2 × 20 mL) and dried
in vacuum overnight to afford a pale brown powder. Anal. Found:
C, 47.26; H, 4.88; N, 1.88%. Calcd for C26H32BF4NO3P2Pd: C,
47.19; H, 4.87; N, 2.12%. 1H NMR (CDCl3): δ 0.81 (d, 2J(P,H) )
[PdCl(dmba){Ph2PCH(SiMe3)P(O)(OMe)2}] (5′). Solid [Pd(µ-
Cl)(dmba)]2 (0.619 g, 1.12 mmol) and 4 (0.853 g, 2.24 mmol) were
placed in a Schlenk flask and CH2Cl2 (20 mL) was added at ambient
temperature. The yellow solution was stirred for 2 h and the volatiles
were removed under reduced pressure. The residue was washed
with Et2O (2 × 10 mL) and pentane (2 × 20 mL), which afforded
a yellow solid (0.761 g, 40%). Anal. Found: C, 43.49; H, 5.01; N
1.84%. Calcd for C27H38ClNO3P2PdSi · 1.5CH2Cl2: C, 42.85; H,
5.27; N 1.78%. 1H NMR (CDCl3): δ 0.16 (s, 9H, SiMe3), 2.80 (d,
3
1.5 Hz, 3H, PdCH3), 1.04 (t, 3H, J(H,H) ) 7 Hz, CH3CH2O),
3
4
4
1.09 (t, 3H, J(H,H) ) 7.0 Hz, CH3CH2O), 2.40 (s, 3H, NCCH3),
6H, J(P,H) ) 2.7 Hz, NMe2), 2.84 (d, 6H, J(P,H) ) 2.5 Hz,
1
4.06 (m, 4H, CH3CH2O), 4.65 (dd, H,2J(P,H) ) 20.8, 14.1 Hz),
2
NMe2), 3.50 (dd, 2H, J(H,H) ) 7.9 Hz, NCH2), 3.74 (d, 6H,
7.15-7.94 (m, 15H, Ph).31P{1H} NMR (CDCl3): δ 37.4 (d,
2+3J(P,P) ) 40 Hz, PPh2), 38.8 (d, 2+3J(P,P) ) 40 Hz, PO).
3J(PO,H) ) 11.3 Hz, OCH3), 3.89 (dd, 1H, J(P,H) ) 4.2 Hz,
2
2J(PO,H) ) 21.3 Hz, PCHP), 6.63-7.96 (14H, m, aromatics);
31P{1H} NMR (CDCl3): δ 26.3 (d, J(P,P) ) 7.0 Hz), 28.2 (d,
2
[Pd{C(O)Me}(NCMe)2}{Ph2PCH(Ph)P(O)(OEt)2}][BF4] (9).
The reaction of 7 (0.135 g, 0.22 mmol) with AgBF4 (0.044 g, 0.22
mmol) afforded the new acetyl complex as a beige powder (0.12
g, 80%). Anal. Found: C, 44.97; H, 4.52%. Calcd. for
C27H32BF4NO4P2Pd · 0.5 CH2Cl2: C, 45.11; H, 4.54. NMR 1H
2J(P,P) ) 7.0 Hz). IR (pure): ν(PdO) 1261 m cm-1
.
[Pd(dmba){Ph2PCH(SiMe3)P(O)(OMe)2}][BF4] (6). Solid 5
(0.200 g, 0.30 mmol) and AgBF4 (0.060 g, 0.30 mmol) were mixed
in a Schlenk flask and CH2Cl2 (15 mL) was added at ambient
temperature. The yellow mixture was stirred for 1 h, and after
3
(CDCl3): δ 1.14 (t, 3H, J(H,H) ) 7 Hz, CH3CH2O), 1.16 (t, 3H,

Palladium Alkyl Complexes
Organometallics, Vol. 28, No. 6, 2009 1695
3J(H,H) ) 7 Hz, CH3CH2O), 2.04 (d, 3H, 4J(P,H) ) 1.1 Hz,
C(O)CH3), 2.24 (s, 3H, NCCH3), 4.06 and 4.21 (m, 4H, CH3CH2O),
Table 2. Crystal Data and Details of the Structure Determination
for 2a and 10 · 1/2CHCl3
2
4.8 (dd, 1H, J(P,H) ) 33, 27 Hz, PCHPh), 7.03-7.80 (m, 15H,
2a
(10 · 1/2CHCl3)
Ph); 31P{1H} NMR (CDCl3): δ 26.5 (d, 2+3J(P,P) ) 40 Hz, PPh2),
Chemical
formula
Mr
C24H29ClO3P2Pd
2(C27H33O4P2Pd) · 2
(BF4) · CHCl3
1472.74
35.6 (d, 2+3J(P,P) ) 40 Hz, PO). IR (KBr): ν(CO) 1716 s cm-1
.
569.26
Cell setting,
space group
Temp. (K)
a (Å)
b, (Å)
c (Å)
Orthorhombic, Aba2
Monoclinic, Pc
[Pd{CH2CH2C(O)Me}{Ph2PCH(Ph)P(O)(OEt)2}][BF4]
(10). Complex 10 was prepared by strirring a solution of complex
9 (0.15 g, 0.21 mmol) in CH2Cl2 (30 mL) under 1 atm of ethylene.
A pale-green solid was obtained after washing with pentane and
diethyl ether (2 × 20 mL), which was dried under vacuum (0.12
g, 88%). Crystals suitable for X-ray diffraction were obtained by
recrystallization from CHCl3/pentane. Anal. found: C, 46.15; H,
5.05%. Calcd for C27H33BF4O4P2Pd · 0.5 CH2Cl2: C, 45.93; H, 4.77.
173(2)
173(2)
32.473(5)
17.736(3)
8.873(2)
90
5110.3(16)
8
1.480
Mo KR
2320
9.6834(2)
16.8383(4)
19.4651(5)
99.3120(10)
3132.00(13)
2
1.562
Mo KR
1492
ꢀ (deg)
V (Å3)
Z
Dcalc (Mg m-3
radiation
F(000)
)
3
1H NMR (300 MHz, CDCl3): δ 1.12 (t, 6H, J(H,H) ) 6.9 Hz,
CH3CH2O), 1.72-1.75 (m, 1H, PdCHHCH2), 1.93-1.97 (m, 1H,
PdCHHCH2), 3.06 and 3.16 (ABM2 spin system (A ) B ) M )
H), 2H, 2J(H,H) ) 12 Hz, 3J(H,H) ) 3 Hz, PdCH2CH2), 4.07-4.20
(m, 4H, CH3CH2O), 4.71 (dd, 1H, 2J(PO,H) ) 21.9 Hz, 2J(P,H) )
14.4 Hz, PCHP), 7.15-7.92 (m, 15H, aromatics); 31P{1H} NMR
(CDCl3): AB spin system δ 37.2 (d, 2+3J(P,P) ) 38 Hz, Ph2P) and
38.4 (d, 2+3J(P,P) ) 38 Hz, PO); IR(KBr): ν(CO) 1637, ν(PO) 1175
µ (mm-1
)
0.98
0.88
Crystal size
(mm)
0.10 × 0.10 × 0.10
0.35 × 0.25 × 0.10
Rint
0.038
0.035, 0.080, 1.02
0.052
0.049, 0.128, 1.00
R[F2 > 2σ(F2)],
wR(F2), S
F
max, Fmin (e Å-3
)
30.0, 2.4
5525
1.03, -1.09
8323
n° of reflexions
(I > 2σ(I))
cm-1
.
n° of parameters
280
733
[Pd{CH[C(O)OMe][CH2C(O)Me]}{Ph2PCH(Ph)P(O)-
(OEt)2}][BF4] (11). Methyl acrylate (15.6 mmol) was added to a
solution of 9 (0.12 g, 0.17 mmol) in CH2Cl2 (40 mL). The solution
was stirred for 1 h at room temperature. After filtration and removal
of the volatiles under vacuum, the pale gray residue was washed
with diethyl ether (2 × 15 mL) and pentane (2 × 20 mL) and dried
in vacuum to afford complex 11 (0.10 g, 79%). Anal. Found: C,
45.37; H, 5.08%. Calcd for C29H35BF4O6P2Pd · 0.5CH2Cl2: C, 45.68;
H, 4.67. 31P{1H} NMR (CDCl3): (diastereoisomeric ratio 1/2: 65/
35), major diastereoisomer: δ 36.1 and 38.6 (AB spin system,
2J(P,P) ) 38 Hz); minor diastereoisomer: δ 34.9 and 37.7 (AB
spin system, 2J(P,P) ) 39 Hz). The labeling of the protons is shown
below:
[Pd{C(O)CH2CH2C(O)Me}{Ph2PCH(Ph)P(O)(OEt)2}]-
[BF4] (12). A solution of 10(0.090 g, 0.129 mmol) in CH2Cl2 (30
mL) was purged with CO. The product was not isolated pure. IR
(KBr): ν(COuncoord.) 1708, ν(COcoord.) 1659, ν(PdO) 1178
cm-1
.
[PdMe{Ph2PCH(Ph)P(O)(OEt)2}{Ph2PCH(Ph)P(O)-
(OEt)2}][BF4] (13). To a Schlenk tube containing 8 (0.300 g, 0.45
mmol) dissolved in CH2Cl2 (25 mL) was added 1. The solution
was stirred for 90 min at room temperature, and the solvent was
removed under vacuum. The residue was washed with diethyl ether
(2 × 20 mL) and pentane (2 × 20 mL) and dried in vacuum
overnight to afford a gray solid (0.400, 50%) as a mixture as
diasteroisomers (ca. 1:1). (Anal. Found: C, 53.83; H, 5.20. Calcd
1
for C47H55O6P4PdBF4: C, 54.65; H, 5.37%). H NMR (CDCl3): δ
3
0.31 (t, 3H, J(P,H) ) 6.0 Hz, PdCH3, diastereoisomer 1), 0.37
3
(dd, 3H, J(P,H) ) 5.7 and 6.1 Hz, PdCH3, diastereoisomer 2),
1.01-1.10 (m, 2 × 12H, OCH2CH3, diastereoisomers 1 + 2),
3.78-3.98 (m, 8H, OCH2CH3, diastereoisomer 1), 4.01-4.16 (m,
8H, OCH2CH3, diastereoisomer 2), 4.80 (t, 2H, 2J(P,H) ) 10.4 Hz)
2
and 4.88 (d, 2H, J(P,H) ) 9.0 Hz) (we cannot state for which
PCHP proton or diastereoisomer), 7.14-7.83 (m, 30H, diastereoi-
somers 1 + 2); 31P{1H} NMR complicated pattern, owing to the
presence of diastereoisomers, which includes, at low temperature
(240 K): δ 28.9 (t, J(P,P) ) 23 Hz, PPh2, diastereoisomer 2), 29.9
(t, J(P,P) ) 21 Hz, PPh2, diastereoisomer 1), and a broad multiplet
1H NMR (300 MHz, CDCl3): δ 1.08-1.19 (m, 2 × 6H,
OCH2CH3), 2.51 (s, 3H, CH3CO, major diastereoisomer), 2.62 (s,
3H, CH3CO, minor diastereoisomer), 2.99 (s, 3H, CH3COO), minor
diastereoisomer), 3.15 (s, 3H, CH3COO, major diastereoisomer),
3.27 (dd, 3J(Ha,Hb) ) 6.5 Hz, 2J(Hb,Hc) ) 18.8 Hz, major
diastereoisomer), 3.62 (dd, 3J(Ha,Hb) ) 5.3 Hz, 2J(Hb,Hc) ) 18.3
centered at δ 32.3 for PO. IR(KBr): ν(PO) 1248 and 1163 cm-1
.
[PdMe{Ph2PCH(Ph)P(O)(OEt)2}{Ph2PNHC(O)Me}][BF4] (14).
The ligand Ph2PNHC(O)Me (0.037 g, 0.15 mmol) was added to a
solution of 8 (0.10 g, 0.151 mmol) dissolved in CH2Cl2 (25 mL),
the solution was stirred for 2 h at room temperature, and the solvent
was removed under vacuum. The beige residue was washed with
diethyl ether (2 × 20 mL) and pentane (2 × 20 mL) and dried
under vacuum overnight to afford a beige solid (0.07 g, 61%). Anal.
Found: C, 53.22; H, 4.93; N, 1.49. Calcd for C38H43BF4O4NP3Pd:
1
Hz, minor diastereoisomer). H NMR (500 MHz, CDCl3): 2.25
(apparence of dt, 3J(Ha,Hb) ) 1.1 Hz, 2J(Ha,Hc) ) 6.2 Hz, 3J(Hb,P)
) 2.6 Hz, Ha major diastereoisomer), 2.51 (s, 3H, CH3CO, major
diastereoisomer), 2.62 (s, 3H, CH3CO, minor diastereoisomer), 2.74
(dd, 3J(Ha,Hb) ) 1.6 Hz, 2J(Ha,Hc) ) 6.0 Hz, 4J(Ha,P) ) 2.4 Hz,
Ha, minor diastereoisomer), 3.27 (dd, 3J(Ha,Hb) ) 6.5 Hz,
2J(Hb,Hc) ) 18.8 Hz, major diastereoisomer, Hc), 3.62 (dd,
3J(Ha,Hb) ) 5.3 Hz, 2J(Hb,Hc) ) 18.3 Hz, minor diastereoisomer,
Hc), 2.99 (s, 3H, CH3COO), minor diastereoisomer), 3.15 (s, 3H,
CH3COO, major diastereoisomer), 3.99-4.13 (m, 4H, OCH2CH3,
major diastereoisomer), 6.93-7.96 (br, 40, aromatics); IR(KBr):
ν(PO) 1167 cm-1, ν(COcoord.) 1632 cm-1, ν(COuncoord.) 1710
1
C, 52.83; H, 5.02; N, 1.62. H NMR (CDCl3): δ 0.41 (br t, 3H,
3J(H,H) ∼ 3 Hz, PdCH3), 0.96 (t, 3H, 3J(H,H) ) 7.0 Hz,
3
OCH2CH3), 1.06 (t, 3H, J(H,H) ) 6.9 Hz, OCH2CH3), 2.42 (s,
3H, NCOCH3), 3.67-3.99 (m, 4H, OCH2CH3), 4.85 (d of virtual
2
+
triplets, 1H, 2J(H,H) ) 24 Hz,
4J(H,H) ) 12 Hz, PCHP),
cm-1
.
7.14-8.28 (m, 25H), 9.25 (br, 1H, NH); 31P{1H} NMR: δ 28.9 (br

1696 Organometallics, Vol. 28, No. 6, 2009
Hamada and Braunstein
2
2
d, J(P,P) ) 404 Hz, CP), 26.3 (br, PO), 67.8 (d, J(P,P) ) 404
Hz, PN). IR(KBr): ν(COuncoord.) 1702s, ν(COcoord.) 1606s,
Acknowledgment. This work was supported by the Centre
National de la Recherche Scientifique and the Ministe`re de
l‘Enseignement Supe´rieur et de la Recherche. We are grateful
to Drs. L. Brelot and A. DeCian and Prof. R. Welter
(Universite´ de Strasbourg) for the resolution of the crystal
structures, to Dr. X. Morise for his contribution and
discussions and to M. Mermillon-Fournier for technical
assistance.
ν(POuncoord.) 1240s, ν(POcoord.) 1162s cm-1
.
Crystal Structure Determinations. Crystals of 2a and 10
suitable for X-ray diffraction were obtained by slow diffusion of
hexane into a dichloromethane solution of the complex at 5 °C.
Diffraction data were collected on a Kappa CCD diffractometer
using graphite-monochromated Mo KR radiation (λ ) 0.71073 Å)
(Table 2). Data were collected using phi-scans and the structures
were solved by direct methods using the SHELX 97 software73,74
and the refinement was by full-matrix least-squares on F2. No
absorption correction was used. All non-hydrogen atoms were
refined anisotropically with H atoms introduced as fixed
contributors (dC-H ) 0.95 Å, U11 ) 0.04). Crystallographic data
(excluding structure factors) have been deposited in the Cam-
bridge Crystallographic Data Center as Supplementary publica-
tion no CCDC 706582 and 70658. Copies of the data can be
obtained free of charge on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: (+44)1223-336-033; e-mail:
deposit@ccdc.cam.ac.uk).
Supporting Information Available: 31P{1H} NMR spectrum
of the equilibrium mixture 5/5′ (Figure S-1), 31P{1H} NMR
resonances of 6 (Figure S-2), and 31P{1H} NMR spectrum of
complex 13 at different temperatures (Figure S-3). Crystallographic
details for all structures in the form of CIF files. This material is
available free of charge via the Internet at http://pubs.acs.org.
OM801020E
(73) Sheldrick, G. M. SHELXL97, Program for the refinement of crystal
structures; University of Go¨ttingen: Germany, 1997.
(74) Kappa CCD Operation Manual; Nonius BV: Delft, The Nether-
lands, 1997.