Synthesis, X-ray, and NMR studies on palladium BINAP complexes containing oxazolidinone and acetylacetonate anions

Article abstract of DOI:10.1021/om0700157

A series of monocationic palladium BINAP complexes, [Pd(rac-BINAP)(an oxazolidinone anion)][X] and [Pd(rac-BINAP)(an acetylacetonate anion)][X] (X = a, CF₃SO₃^-; b, BF₄^-) (9-13), have been synthesized and characterized. A dicationic intermediate, pertinent to the Pd-catalyzed hydroamination reaction, arising from the reaction of the bis-aquo complex [Pd(H₂O)₂(rac-BINAP)] ₂(CF₃SO₃)₂ and 1 equiv of an oxazolidinone, has been characterized via low-temperature NMR studies. The structures of the complexes [Pd(rac-BINAP)(CH₃-C(O)-C(CH ₃)-C(O)-CH₃)](BF₄), 12b, and [Pd(μ-OH)(rac-BINAP)]₂(CF₃SO₃)₂ have been determined by X-ray diffraction. The solid-state structures of two separate forms of the BF₄^- salt 12b were obtained. One form of the salt can be thought of as a tight ion pair, whereas the second form contains a dichloromethane solvent molecule, packed in approximately a fifth coordination position together with a relatively remote BF₄ ^- anion. These structures represent a rare example where both ion pairing and strong solvation could be individually characterized. PGSE diffusion coefficients (D values) were measured for both the CF₃SO ₃^- and BF₄^- salts of 9-13 in CD ₂Cl₂. In addition, D values were obtained for the CF ₃SO₃^- salts in THF and CDCl₃ solutions. The amount of ion pairing decreases in the sequence CDCl₃ > THF > CD₂Cl₂. The ¹H, ¹⁹F-HOESY spectra for the salts in CDCl₃ suggest that the CF₃SO₃^- is approaching the positive metal and phosphorus centers via a pathway that brings it closest to the P-phenyl groups but remote from the chelating anion.

Full text of DOI:10.1021/om0700157

Organometallics 2007, 26, 2111-2121
2111
Synthesis, X-ray, and NMR Studies on Palladium BINAP Complexes
Containing Oxazolidinone and Acetylacetonate Anions
Devendrababu Nama and Paul S. Pregosin*
Laboratory of Inorganic Chemistry, ETHZ, 8093 Zu¨rich, Switzerland
Alberto Albinati* and Silvia Rizzato
Department of Structural Chemistry (DCSSI), UniVersity of Milan, 20133 Milan, Italy
ReceiVed January 8, 2007
A series of monocationic palladium BINAP complexes, [Pd(rac-BINAP)(an oxazolidinone anion)][X]
-
-
and [Pd(rac-BINAP)(an acetylacetonate anion)][X] (X ) a, CF3SO3 ; b, BF4 ) (9-13), have been
synthesized and characterized. A dicationic intermediate, pertinent to the Pd-catalyzed hydroamination
reaction, arising from the reaction of the bis-aquo complex [Pd(H2O)2(rac-BINAP)]2(CF3SO3)2 and 1
equiv of an oxazolidinone, has been characterized via low-temperature NMR studies. The structures of
the complexes [Pd(rac-BINAP)(CH3-C(O)-C(CH3)-C(O)-CH3)](BF4), 12b, and [Pd(µ-OH)(rac-
BINAP)]2(CF3SO3)2 have been determined by X-ray diffraction. The solid-state structures of two separate
-
forms of the BF4 salt 12b were obtained. One form of the salt can be thought of as a tight ion pair,
whereas the second form contains a dichloromethane solvent molecule, packed in approximately a fifth
-
coordination position together with a relatively remote BF4 anion. These structures represent a rare
example where both ion pairing and strong solvation could be individually characterized. PGSE diffusion
-
-
coefficients (D values) were measured for both the CF3SO3 and BF4 salts of 9-13 in CD2Cl2. In
addition, D values were obtained for the CF3SO3- salts in THF and CDCl3 solutions. The amount of ion
1
pairing decreases in the sequence CDCl3 > THF > CD2Cl2. The H,19F-HOESY spectra for the salts in
CDCl3 suggest that the CF3SO3- is approaching the positive metal and phosphorus centers via a pathway
that brings it closest to the P-phenyl groups but remote from the chelating anion.
Introduction
Mono- and/or dicationic Pd(II) salts play an important role
in a number of catalytic transformations, e.g., allylic alkylation,1
aldol condensation,2 ene-type Michael additions,3 and selected
hydroamination reactions.4 Recently, Sodeoka and co-workers,5
and later Hii and co-workers,6 have made extensive use of
palladium(II) BINAP complexes as catalyst precursors. For the
enantioselective Michael reaction using 1,3-diketones as sub-
strates, Sodeoka7 has generated the monocationic palladium tert-
tion. Li and Hii,6b in their studies on Pd(BINAP)-catalyzed
hydroamination reactions, using unsaturated oxazolidinones as
reagents, consider the dicationic chelating intermediate, B,
shown above, as potentially relevant. Jorgensen and co-workers8
have proposed a related dicationic oxazolidinone complex of
nickel.
It is now fairly normal to use a number of different anions in
cationic palladium chemistry. Occasionally, there are reports
suggesting that the anion may play a specific role,9-14 e.g., in
butyl-substituted enolate, A, shown, and found this salt to be a
fairly stable intermediate. This type of chiral palladium complex
is also relevant in the area of catalytic enantioselective fluorina-
(1) Trost, B. M.; Crawley, M. L. Chem. ReV. 2003, 103, 2921-2943.
(2) Kleij, A. W.; Gebbink, R.; van den Nieuwenhuijzen, P. A. J.;
Kooijman, H.; Lutz, M.; Spek, A. L.; van Koten, G. Organometallics 2001,
20, 634-647. Nesper, R.; Pregosin, P. S.; Puntener, K.; Wo¨rle, M. HelV.
Chim. Acta 1993, 76, 2239-2249.
(3) Phua, P. H.; White, J. P.; de Vries, J. G.; Hii, K. K. AdV. Synth.
Catal. 2006, 348, 587-592. Ogasawara, M.; Yoshida, K.; Hayashi, T.
Organometallics 2000, 19, 1567-1571.
(4) Hartwig, J. F. Pure Appl. Chem. 2004, 76, 507-516.
(5) (a). Hamashima, Y.; Takano, H.; Hotta, D.; Sodeoka, M. Org. Lett.
2003, 5, 3225-3228. (b) Hamashima, Y.; Hotta, D.; Umebayashi, N.;
Tsuchiya, Y.; Suzuki, T.; Sodeoka, M. AdV. Synth. Catal. 2005, 347, 1576-
1586.
(6) (a) Li, K. L.; Horton, P. N.; Hursthouse, M. B.; Hii, K. K. J.
Organomet. Chem. 2003, 665, 250-257. (b) Li K. L.; Hii, K. K. Chem.
Commun. 2003, 1132-1133. (c) Phua, P. H.; de Vries, J. G.; Hii, K. K.
AdV. Synth. Catal. 2005, 347, 1775-1780. (d) Li, K. L.; Phua, P. H.; Hii,
K. K. Tetrahedron 2005, 61, 6237-6242.
(7) (a) Hamashima, D.;. Sodeoka, M. Chem. Rec. 2004, 4, 231-242.
(b) Hamashima, Y.; Hotta, D.; Sodeoka, M. J. Am. Chem. Soc. 2002, 124,
11240-11241. (c) Fujii, A.; Hagiwara, E.; Sodeoka, E. M. J. Am. Chem.
Soc. 1999, 121, 5450-5458.
(8) Zhuang, W.; Hazell, R. G.; Jørgensen, K. A. Chem. Commun. 2001,
1240-1241. See also: Evans, D. A.; Thomson, R. J.; Franco, F. J. Am.
Chem. Soc. 2005, 127, 10816-10817, for a related structure as a nickel
complex.
(9) Fagnou, K.; Lautens, M. Angew. Chem., Int. Ed. 2002, 41, 27-47.
Lautens, M.; Fagnou, K.; Yang, D. Q. J. Am. Chem. Soc. 2003, 125, 14884-
14892.
(10) Krossing, I.; Raabe, I. Angew. Chem., Int. Ed. 2004, 43, 2066-
2090.
(11) Drago, D.; Pregosin, P. S.; Pfaltz, A. Chem. Commun. 2002, 286-
287.
(12) Firestone, M. A.; Rickert, P. G.; Seifert, S.; Dietz, M. L. Inorg.
Chim. Acta 2004, 357, 3991-3998.
(13) Lancaster, N. L.; Welton, T. J. Org. Chem. 2004, 69, 5986-5992.
10.1021/om0700157 CCC: $37.00 © 2007 American Chemical Society
Publication on Web 03/17/2007

2112 Organometallics, Vol. 26, No. 8, 2007
Nama et al.
Scheme 1
1
determining the nature of the product and/or the reaction
kinetics.9 Generally speaking, the anion may affect the solubility
of the catalyst, accelerate or decelerate reactions, and occasion-
ally improve reaction selectivity. Presumably the anion is not
always “innocent” and may (a) block or actually take up a
coordination position, (b) affect the cation via ion pairing, or
(c) induce aggregation, i.e., significantly change the cation
structure.
the cation and anion can be measured separately (e.g., via H
and 19F NMR measurements), as their relative magnitudes can
be revealing. In a given solvent, identical D values for the cation
and anion suggest strong ion pairing25 (in the absence of
hydrogen bonding, encapsulation effects, etc.). The measured
D values are in turn used to calculate a hydrodynamic radius
(rH) using the Stokes-Einstein relation (eq 1) by correcting for
the solvent viscosity.
Increasingly, pulsed field gradient spin-echo (PGSE) diffu-
sion measurements15 are used to investigate possible ion pairing
and/or aggregation of salts in solution.16-26 The measurement
of self-diffusion coefficients (D values) is especially useful when
kT
6πηD
rH )
(1)
where k is the Boltzmann constant, η is the solution viscosity,
and T is the temperature. Diffusion data, when combined with
HOESY (or NOESY) measurements, assist in the understanding
(14) Faller, J. W.; Fontaine, P. P. Organometallics 2005, 24, 4132-
4138.
(15) Price, W. S. Concepts Magn. Reson. 1997, 9, 299-336. Price, W.
S. Concepts Magn. Reson. 1998, 10, 197-237. Stilbs, P. Prog. Nucl. Magn.
Reson. Spectrosc. 1987, 19, 1.
(22) Ferna´ndez, I.; Mart´ınez-Viviente, E.; Pregosin, P. S. Inorg. Chem.
2004, 43, 4555-4557. Martinez-Viviente, E.; Pregosin, P. S.: Vial, L.;
Herse C.; Lacour, J. Chem.-Eur. J. 2004, 10, 2912-2918. Nama, D.;
Kumar, P. G. A.; Pregosin, P. S.; Geldbach, T. J.; Dyson, P. J. Inorg. Chim.
Acta 2006, 359, 1907-1911. M. Alajarin, M.; Pastor, A.; Orenes, R. A.;
Martinez-Viviente, E.; Pregosin, P. S. Chem.-Eur. J. 2006, 12, 877-886.
(23) Brand, T.; Cabrita, E. J.; Berger, S. Prog. Nucl. Magn. Reson.
Spectrosc. 2005, 46, 159-196.
(16) Jaing, Q.; Ru¨egger, H.; Venanzi, L. M. Inorg. Chim Acta 1999,
290, 64-79.
(17) Stahl, N. G.; Zuccaccia, C.; Jensen, T. R.; Marks, T. J. J Am. Chem
Soc. 2003, 125, 5256-5257.
(18) Burini, A.; Fackler, J. P.; Galassi, R.; Macchioni, A.; Omary, M.
A.; Rawashdeh-Omary, M. A.; Pietroni, B. R.; Sabatini, S.; Zuccaccia, C.
J. Am. Chem. Soc. 2002, 124, 4570-4571.
(19) Binotti, B.; Macchioni, A.; Zuccaccia, C.; Zuccaccia, D. Comments
Inorg. Chem. 2002, 23, 417-450.
(24) Cohen, Y.; Avram, L.; Frish, L. Angew. Chem., Int. Ed. 2005, 44,
520-554.
(20) Zuccaccia, C.; Stahl, N. G.; Macchioni, A.; Chen, M. C.; Roberts,
J. A.; Marks, T. J. J. Am. Chem. Soc. 2004, 126, 1448-1464.
(21) Ludwig, M.; Kadyrov, R.; Fiedler, H.; Haage, K.; Selke, R. Chem.-
Eur. J. 2001, 7, 3298-3304.
(25) Pregosin, P. S. Prog. Nucl. Magn. Reson. Spectrosc. 2006, 49, 261-
288. Pregosin, P. S.; Kumar P. G. A.; Fernandez, I. Chem. ReV. 2005, 105,
2977-2998.
(26) Macchioni, A. Chem. ReV. 2005, 105, 2039-2073.

Palladium BINAP Complexes
Organometallics, Vol. 26, No. 8, 2007 2113
Table 1. 1H and 13C Chemical Shift Dataa for Complex 14
and Oxazolidinone, 8
Table 2. Bond Lengths (Å) and Bond Angles (deg) for
Complex 12b
12b‚CH2Cl2
Pd-O(2)
2.026(3)
2.259(1)
1.811(4)
1.838(4)
1.825(4)
1.292(5)
89.0(1)
Pd-O(1)
2.025(3)
2.264(1)
1.825(4)
1.818(3)
1.822(4)
1.281(5)
89.23(9)
177.3(1)
91.57(3)
107(1)
Pd-P(1)
Pd-P(2)
P(1)-C(111)
P(1)-C(6)
P(1)-C(121)
P(2)-C(221)
P(2)-C(211)
O(2)-C(4L)
O(2)-Pd-P(1)
O(2)-Pd-P(2)
P(1)-Pd-P(2)
F-B-F (av)
P(2)-C(6′)
O(1)-C(2L)
O(2)-Pd-O(1)
O(1)-Pd-P(1)
O(1)-Pd-P(2)
B-F (av)
δ 1H
δ 13C
174.2(1)
90.42(9)
1.4(3)
8
1
2
3
4
5
6
7
1.95
7.1-7.2
7.1-7.2
19.5
148.2
121.1
165.8
154.7
63.0
12b
Pd-O(2)
2.021(4)
2.251(2)
1.802(6)
1.819(6)
1.834(5)
1.275(7)
88.3(2)
176.9(1)
90.8(1)
1.25(3)
Pd-O(1)
2.032(4)
2.253(2)
1.823(6)
1.799(5)
1.837(8)
1.276(7)
88.5(1)
171.4(1)
92.32(5)
108(2)
Pd-P(1)
Pd-P(2)
P(1)-C(121)
P(2)-C(221)
P(1)-C(6)
O(1)-C(2L)
O(2)-Pd-O(1)
O(1)-Pd-P(1)
O(1)-Pd-P(2)
B-F (av)
P(1)-C(111)
P(2)-C(211)
P(2)-C(6′)
O(2)-C(4L)
O(2)-Pd-P(1)
O(2)-Pd-P(2)
P(1)-Pd-P(2)
F-B-F (av)
4.01
4.40
43.5
14
1.56
5.01
1
2
3
4
5
6
7
19.0
157.3
119.5
165.4
158.8
66.2
5.86
4.50
4.28
Solution Structures. The reaction of 2 with, for example,
imide 4 produces 1 equiv of water via the deprotonation of the
weakly acidic NH proton and the generation of Pd(II) salts
9-11. The new products are readily identified via NMR
spectroscopy. As an example, for the CF3SO3- complex 10a in
45.7
a δ 31P ) 37. 4, δ ) 35.6, 2J(31P,31P) ) 9.5 Hz; 400 MHz, 203 K CD2Cl2.
of how ions interact and, specifically, the relative position of
the anion with respect to the cation.23,25,26
Here we report the use of the bis-aquo complex 1, [Pd(H2O)2-
(BINAP)]2(anion)2, 1a,b (anion ) a, CF3SO3-; b, BF4-),
containing racemic BINAP, to generate the bridging hydroxide
species [Pd(µ-OH)(BINAP)]2(anion)2, 2a,b (anion ) a, CF3SO3-;
b, BF4-), which then reacts, cleanly, with the unsaturated
N-imides 3, 4, and 5 or the 1,3-diketones 6 and 7 to afford a
new set of monocationic Pd(II) BINAP complexes, 9 to 13, in
good to excellent yield (see Scheme 1). We also show that
crotonyl oxazolidinone[(E)-3-but-2-enoyloxazolidin-2-one], 8,
coordinates to the Pd(BINAP) fragment via chelation of the two
oxygen atoms to form a modest amount of the new, catalytically
relevant, complex 14 (see eq 2). Finally, using PGSE diffusion
dichloromethane at room temperature, the 31P{1H} NMR
2
spectrum shows an AB system, J(PP) ) 33.5 Hz, with the
nonequivalent phosphorus nuclei, appearing at δ 35.5 and 35.1.
1
In the H NMR spectrum, one finds new resonances for the
methyl and olefinic protons. Specifically, the CH3 is found at
δ 1.6, and the two olefinic resonances, CH3CHdCH, as a
strongly coupled spin system at δ 5.7-5.9. The corresponding
ligand positions for 4 are δ 2.0, for the methyl signal, and δ
7.1-7.2 for the CH3CHdCH moiety. We believe that several
of these low-frequency proton chemical shifts in 10a arise from
a mixture of anisotropic (P-phenyl on the BINAP proximate to
the olefin) and chelation effects. Interestingly, all of the BINAP
complexes reveal a rather broad aromatic proton resonance
between δ 6 and 7. Earlier NMR studies32,33 have shown that
this signal is associated with restricted rotation of the P-axial
phenyl groups.
and HOESY NMR methods, we consider the nature of the ion
pairing, with a view to recognizing possible steric effects in
catalysis due to the position of the anion.
Results and Discussion
The well-known5,7 diaquo complex [Pd(H2O)2(BINAP)]2-
(anion)2 represents a source of [Pd(µ-OH)(BINAP)]2(anion)2.
Allowing these bridged hydroxy complexes, 2a,b, to react with
the appropriate unsaturated N-imides ligand precursors, 3-5,
or 1,3-diketones, 6 and 7, in dichloromethane solution affords
the monocationic Pd(II) BINAP complexes 9-11 and 12 and
13 (anion ) a, CF3SO3-; b, BF4-). The new chelating anions
are generated using the bridging hydroxide ligand, and we note
that related enolate complexes of palladium have been reported
by several groups.27-31
(28) Ketz, B. E.; Cole, A. P.; Waymouth, R. M. Organometallics 2004,
23, 2835-2837.
(29) Vicente, J.; Areas, A.; Fernandez-Hernandez, J. M.; Bautista, D.;
Jones, P. G. Organometallics 2005, 24, 2516-2527.
(30) Gavrielatos, E.; Athanasellis, G.; Heaton, B. T.; Steiner, A.; Bickley,
J. F.; Igglessi-Markopoulou, O.; Markopoulos, J. Inorg. Chim. Acta 2003,
351, 21-26.
(31) Tian, G. L.; Boyle, P. D.; Novak, B. M. Organometallics 2002, 21,
1462-1465.
(32) Trabesinger, G.; Albinati, A.; Feiken, N.; Kunz, R. W.; Pregosin,
P. S.; Tschoerner, M. J. Am. Chem. Soc. 1997, 119, 6315.
(33) Nama, D.; Schott, D.; Pregosin, P. S.; Veiros, L. F.; Calhorda, M.
J. Organometallics 2006, 25, 4596.
(27) Braun, M.; Meier, T. Synlett 2006, 661-676.

2114 Organometallics, Vol. 26, No. 8, 2007
Nama et al.
1
Figure 1. Variable-temperature 31P (left) and H (right) NMR spectra from a solution of complex 14. The AX spin system in 31P{1H}
spectra is visible (CD2Cl2, 20 mM, 500 MHz).
CH proton and the generation of Pd(II) enolate complexes 12
and 13, respectively. For complex 13a, in dichloromethane
solution at room temperature, the 31P{1H} NMR spectrum shows
an AX doublet, 2J(PP) ) 38 Hz, with the resonances appearing
1
at δ 30.3 and 34.8. In the H NMR spectrum the absence of
doublet multiplicity associated with the central methyl group
is consistent with the deprotonated and complexed ligand.
Further, the OCH2 moiety now appears as two diastereotopic
CH2 protons, δ 2.65 and 2.90, shifted to low frequency due to
the proximate P-phenyl aromatic ring. In the 13C{1H} NMR
spectrum, the central carbon, between the two carbonyl carbons,
appears at δ 90.5, ∆δ 29 ppm, and is no longer attached to a
proton. The 2D 13C,1H long-range correlation reveals the two
carbonyl carbons (COMe, COOC2H5) at δ 184.2 and 169.8,
respectively. This same 13C correlation allows one to assign the
1
two, singlet, H methyl groups of 13a in that the signal at δ
1.70 reveals cross-peaks to both 13C carbonyl resonances, via
1
Figure 2. Section of H,1H NOESY spectrum of complex 14,
showing exchange between free ligand 8 and chelated ligand in
complex 14 (CD2Cl2 500 MHz, 203 K).
3
the two different J(13C,1H) pathways.
NMR Characterization of Dicationic Complex 14. The
addition of ligand 8 to the precursor complex [Pd(µ-OH)-
(BINAP)]2(CF3SO3)2, 2a, in dichloromethane does not yield
complex 14. However, reaction of ligand 8 with the aquo
Continuing, in the 13C{1H} NMR spectrum of 10a, the two
olefinic carbons, C2 and C3, are found at δ 145.9 (CH3CHd
CH) and 129.6 (CH3CHdCH). These values do not correspond
to a coordinated olefin, as the coordination chemical shifts, ∆δ
()δ for 10a - δ for 4), are only -0.7 and 4.9 ppm,
respectively.49 It is useful to note that the deprotonation and
complexation of 4 results in a small low-frequency (-0.7 ppm)
change in the â-olefinic carbon chemical shift. This is not what
one expects if this position is to be more electrophilic and thus
more readily attacked by an amine nucleophile. A 2D 13C,1H
long-range correlation reveals the two amide carbonyl carbons
at δ 172.8 and 173.2. These chemical shift values are consistent
with chelation of the anion of 4 to the metal through the oxygen
atoms. Similar 31P{1H}, 1H, and 13C{1H} NMR data were found
in complexes 9 and 11.
complex [Pd(H2O)2(BINAP)]2(CF3SO3)2, 1a, in dichloromethane
solution affords a mixture, which, via a low-temperature
measurement, can be shown to contain ca. 16% of 14 plus
unreacted starting material (see Figure 1). Both the 1H and 31P-
{1H} spectra at room temperature gave broad resonances,
suggesting dynamic behavior. The 31P{1H} NMR spectrum,
which revealed a single broad peak at ca. δ 36.2 at room
temperature, sharpens on cooling to 213 K, to reveal a major
In a similar fashion, addition of ligand 6 or 7 to a dichlo-
romethane solution of the bridged complexes 2a,b (anion ) a,
CF3SO3; b, BF4) results in the abstraction of the weakly acidic

Palladium BINAP Complexes
Organometallics, Vol. 26, No. 8, 2007 2115
Figure 5. ORTEP view of the cation of 2a with thermal ellipsoids
drawn at the 50% probability level. Selected bond lengths (Å) and
bond angles (deg): Pd(1)-OH1, 2.060(3), Pd(1)-OH2 2.080(3),
Pd(1)-P(21) 2.225(1), Pd(1)-P(11) 2.233(1), Pd(2)-P(22) 2.226-
(1), Pd(2)-P(12) 2.232(1), Pd(1)-Pd(2) 3.1378(5), Pd(2)-OH1
2.062(3), Pd(2)-OH2 2.076(3), OH1-Pd(1)-OH2 79.7(1), OH1-
Pd(1)-P(21) 93.3(1), OH2-Pd(1)-P(21) 171.3(1) OH1-Pd(1)-
P(11) 170.8(1), OH2-Pd(1)-P(11) 95.1(1), P(21)-Pd(1)-P(11)
92.49(5), OH1-Pd(1)-Pd(2) 40.4(1), OH2-Pd(1)-Pd(2) 40.92-
(9), P(21)-Pd(1)-Pd(2) 130.99(3), P(11)-Pd(1)-Pd(2) 135.70-
(3), OH1-Pd(2)-OH2 79.8(1), OH1-Pd(2)-P(22) 95.0(1), OH2-
Pd(2)-P(22) 171.2(1), OH1-Pd(2)-P(12) 171.1(1), OH2-Pd(2)-
P(12) 92.2(1), P(22)-Pd(2)-P(12) 93.51(5).
14 - δ for 8), are +9.1 and -1.6 ppm, respectively; that is,
complexation of 8 results in a very significant high-frequency
(+9.1 ppm) change in the â-olefinic carbon chemical shift.
These 13C values are not consistent with direct olefin coordina-
tion, but the relatively large change for the â-olefinic carbon is
what one expects if this carbon atom is to become more
electrophilic through complexation and thus more readily
attacked by a nucleophile. This is in contrast to what one finds
for the 13C data for 10, noted above.
Figure 3. Views of the ion-paired (top, 12b) and the solvent-
separated (bottom, 12b‚CH2Cl2) salts.
1
From a phase-sensitive H,1H NOESY spectrum at 203 K,
one finds exchange cross-peaks arising from the free oxazoli-
dinone, 8, and the chelated ligand in complex 14 (see Figure
2). The ease with which model salt 14 exchanges the complexed
chelating ligand is clearly important for the mechanism of a
catalytic reaction involving this type of substrate, since the
addition product, once formed, must dissociate from the
palladium to make room for the new substrate. While 14
represents only a minor component, it is obviously stable enough
to be characterized and is clearly relevant to the palladium-
catalyzed hydroamination chemistry noted in the Introduction.
X-ray Data. The solid-state structures of two separate forms
-
of the BF4 complex, 12b and 12b‚CH2Cl2, were determined
by X-ray diffraction methods. Initially it was thought that two
different materials had recrystallized; however as can been from
Figure 3a (top), one form of the salt 12b can be thought of as
a tight ion pair, whereas the second form (Figure 3b, bottom)
contains a dichloromethane solvent molecule, packed in ap-
proximately a fifth coordination position together with a
relatively remote BF4- anion. Together these structures represent
an unprecedented example of a salt where the structures of both
the solVent-stabilized cation and the tight ion-paired salt can
be characterized. This is, admittedly, a fortunate coincidence,
in that the solution diffusion studies reveal only an average D
value for the two ions; nevertheless, these solid-state data help
us to envision structural aspects of these two extreme forms.
The two palladium cations are not very different, and Figure
4 shows a view of one of these. The local coordination geometry
about the Pd atoms is distorted square planar, and the metric
Figure 4. ORTEP view of the cation of 12b with thermal ellipsoids
drawn at the 50% probability level.
component (starting material), as a sharp singlet, along with a
minor component as an AX spin system containing signals at
2
ca. δ 35.5 and 37.5, J(PP) ) 9.5 Hz.
Cooling of the solution to 203 K changes and resolves the
1
broad H NMR spectrum for this solution and reveals new
proton resonances for the minor component, 14 (see Figure 1),
and these chemical shift data are given in Table 1. We note
that one of the olefinic resonances of 14 overlaps a water signal.
The conventional 13C{1H} NMR spectrum and the 2D 13C,1H
long-range correlation both reveal the two CH olefin carbons,
C2 and C3, at δ 157.3 and 119.5, respectively (Table 1). These
values, once again, are not consistent with olefin complexa-
tion. The C2 and C3 coordination chemical shifts, ∆δ () δ for

2116 Organometallics, Vol. 26, No. 8, 2007
Table 3. Diffusion Constantsa and Radiib for Complexes 9 to 13 in CD2Cl2
Nama et al.
-
-
a (CF3SO3
)
b (BF4 )
cation(1H)
anion(19F)
cation(1H)
anion(19F)
compd
D
rH
(rH)
D
rH
(rH)
D
rH
(rH)
D
rH
(rH)
9
8.11
8.02
7.35
8.27
8.11
6.5
6.6
7.2
6.4
6.5
(7.1)
(7.1)
(7.7)
(7.0)
(7.1)
13.13
11.86
13.39
12.40
11.70
4.0
4.5
4.0
4.3
4.5
(5.0)
(5.2)
(4.9)
(5.1)
(5.3)
8.00
7.74
7.79
8.53
8.37
6.6
6.8
6.8
6.2
6.3
(7.1)
(7.3)
(7.3)
(6.8)
(6.9)
13.70
13.96
14.06
14.02
14.02
3.9
3.8
3.8
3.8
3.8
(4.8)
(4.8)
(4.8)
(4.8)
(4.8)
10
11
12
13
b
a 400 MHz, 2 mM; D values, 10-10 m2 s-1. rH values, Å; “c” corrected rH values are in parentheses as suggested in ref 48. Estimated radii for the
solvents rvdw ) 2.49 (CD2Cl2), η(CH2Cl2) ) 0.414 × 10-3 kg m-1 s-1 at 299 K.
Figure 6. 1H,19F-HOESY spectra for the complexes 9a to 13a (CF3SO3 anion) in CDCl3, all showing selective contacts primarily to the
P-phenyl ring protons and not to the chelated anionic ligand. In complex 12, one finds a weak contact (shown by arrow) to the methyl
group (six protons). The empty circles indicate the absence of an NOE cross-peak (400 MHz, 298 K).
values for the two cations do not differ significantly (see Table
2). The various Pd-donor atom separations are normal,34 as are
the local coordination angles about the palladium atoms.
However, we note that, to accommodate the square planar
structure, the acetyl acetonate angles, O(1)-C(2L)-C(3L) )
126.1(4)° and O(2)-C(4L)-C(3L) ) 127.1(4)°, in both cations
are larger than the 120° values expected for sp2 hybridization.
As expected, the chiral pocket for the coordinated BINAP ligand
reveals pseudoaxial and pseudoequatorial P-phenyl groups.35-38
There are two further modest structural differences between
these two compounds: (1) The dihedral angle between the
complexed acac ligand and the Pd,O1,O2,P1,P2 plane is 5.3-
(8)° for the CH2Cl2-solvated salt and 23.9° for the tight ion
pair. Consequently, the coordinated acac is bent away from the
closely positioned BF4 anion. (2) The Pd-P distances are
slightly longer (>5σ) for the CH2Cl2-solvated salt than for the
tight ion pair.
-
These do not represent major structural changes; however,
they do indicate that the cation is responding to the two different
environments.
(34) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.
In the course of our preparative work, crystals of the dinuclear
µ-OH salt, 2a, suitable for diffraction studies were obtained,
and a view of this dication is given in Figure 5. The structure
of the analogous p-tolyl salt has been reported by Sodeoka.7b
The various metric parameters are rather standard, and we note
that the four-membered Pd-O-Pd-O ring takes a distorted
butterfly shape; that is, the ring is not flat. The dihedral angle
between the two tetrahedrally distorted square planar Pd
coordination planes is 18.6(1)°.
(35) Ammann, C. J.; Pregosin, P. S.; Ruegger, H.; Albinati, A.; Lianza,
F.; Kunz, R. W. J. Organomet. Chem. 1992, 423, 415-430. Pregosin, P.
S.; Ruegger, H.; Salzmann, R.; Albinati, A.; Lianza, F.; Kunz, R. W.
Organometallics 1994, 13, 83-90. Pregosin, P. S.; Ruegger, H.; Salzmann,
R.; Albinati, A.; Lianza, F.; Kunz, R. W. Organometallics 1994, 13, 5040-
5048. Barbaro, P.; Pregosin, P. S.; Salzmann, R.; Albinati, A.; Kunz, R.
W. Organometallics 1995, 14, 5160. Drommi, D.; Nesper, R.; Pregosin, P.
S.; Trabesinger, G.; Zurcher, F. Organometallics 1997, 16, 4268-4275.
Magistrato, A.; Merlin, M.; Pregosin, P. S.; Rothlisberger, U.; Albinati, A.
Organometallics 2000, 19, 3591.
(36) Zhang, X.; Mashima, K.; Koyano, K.; Sayo, N.; Kumobayashi, H.;
Akutagawa, S.; Takaya, H. J. Chem. Soc., Perkin Trans. 1994, 2309-2322.
(37) Oestreich, M.; Dennison, P. R.; Kodanko, J. J.; Overman, L. E.
Angew. Chem., Int. Ed. 2001, 40, 1439-1442. Marshall, W. J.; Grushin,
V. V. Organometallics 2003, 22, 555-562.
Diffusion Studies. PGSE diffusion data for the Pd(BINAP)
-
-
CF3SO3 and BF4 salts, 9-13, in dichloromethane solution
are given in Table 3. The rH values for cations fall in the range
6.2-7.2 Å (Table 3) and are in reasonable agreement with our
earlier data on Pd BINAP complexes.33 For 12b, the rH value
of 6.2 Å is in excellent agreement with the rx-ray value of 6.3
(38) Pregosin, P. S.; Ru¨egger, H. In ComprehensiVe Coordination
Chemistry II, Vol. 2; McCleverty, A., Meyer, T. J., Eds.; Elsevier:
Amsterdam, 2004; p 1. Pregosin, P. S.; Martinez-Viviente, E.; Kumar, P.
G. A. Dalton Trans. 2003, 4007, and references therein.

Palladium BINAP Complexes
Organometallics, Vol. 26, No. 8, 2007 2117
Table 4. Diffusion Constantsa and Radiib for 9a-13a in THF-d8 and CDCl3 and, for 12, in CD3CN
-
a (CF3SO3
anion(19F)
)
THF
CDCl3
cation(1H)
cation(1H)
anion(19F)
compd
D
rH
(rH)
D
rH
(rH)
D
rH
(rH)
D
rH
(rH)
9
6.43
6.28
6.06
6.78
6.55
7.4
7.6
7.8
7.0
7.3
(7.9)
(8.1)
(8.4)
(7.6)
(7.8)
9.25
9.30
8.93
9.24
9.43
5.1
5.1
5.3
5.1
5.0
(6.0)
(6.0)
(6.1)
(6.0)
(5.9)
5.66
5.53
5.26
5.82
5.88
7.2
7.4
7.8
7.0
7.0
(7.8)
(7.9)
(8.2)
(7.6)
(7.5)
5.96
6.46
6.08
6.30
6.29
6.9
6.3
6.7
6.5
6.5
(7.4)
(6.9)
(7.4)
(7.1)
(7.1)
10
11
12
13
CD3CN
cation(1H)
anion(19F)
D
rH
D
rH
12
10.22
6.2
23.86
2.7
b
a 400 MHz, 2 mM; D values, 10-10 m2 s-1. rH values, Å; “c” corrected rH values as suggested in ref 48, are in parentheses. Estimated radii for the
solvents: rvdw ) 2.68 (THF), rvdw )2.60 (CDCl3), η(CHCl3) ) 0.534 × 10-3 kg m-1 s-1 at 299 K, η(THF) ) 0.461 × 10-3 kg m-1 s-1 at 299 K. η(CH3CN)
) 0.345 × 10-3 kg m-1 s-1 at 299 K, 2.60 (CDCl3), η(CHCl3) ) 0.534 × 10-3 kg m-1 s-1 at 299 K, η(THF) ) 0.461 × 10-3 kg m-1 s-1 at 299 K,
η(CH3CN) ) 0.345 × 10-3 kg m-1 s-1 at 299 K.
Table 5. Experimental Data for the X-ray Diffraction Study of Compounds 2a‚0.5(H2O), 12b, and 12b‚(CH2Cl2)
2a‚0.5(H2O)
12b
12b‚(CH2Cl2)
formula
mol wt
C90H69F6O8.5P4Pd2S2
1800.24
295(2)
Bruker APEX
monoclinic
P21/c (14)
20.0621(5)
18.7386(4)
23.2203(5)
90.
96.572(1)
90.
8672.0(3)
4
1.379
6.04
C50H41BF4O2P2Pd
928.98
295(2)
Bruker SMART
orthorombic
Pna21 (33)
19.891(3)
16.856(2)
12.518(2)
90.
90
90.
4197.2(1)
4
1.470
5.77
C51H43BCl2F4O2P2Pd
1013.90
295(2)
Bruker APEX
triclinic
data coll. T, K
diffractometer
cryst syst
space group (no.)
a, Å
P1h (2)
11.560(4)
11.609(4)
18.806(6)
78.198(7)
75.174(6)
73.210(7)
2312(1)
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
2
F
(calcd), g cm-3
1.456
6.42
µ, cm-1
radiation
Mo KR (graphite monochrom., λ ) 0.71073 Å)
θ range, deg
no. of indep data
no. of obsd reflns (no)
1.49 < θ < 26.09
17 073
12 120
2.03 < θ < 21.36
4719
4196
1.85 < θ < 25.99
8988
7094
2
2
[|Fo| > 2.0σ(|F| )]
no. of params refined (nv)
Rint
978
541
560
0.0506
0.0616
0.1705
1.031
0.0575
0.0315
0.0726
1.012
0.0375
0.0515
0.1431
1.018
R (obsd reflns)a
Rw2 (obsd reflns)b
GOFc
2
2
2
2 2
2
2
a R ) ∑ (|Fo - (1/k)Fc|)/∑|Fo|. b Rw ) [∑w(Fo - (1/k)Fc )2/∑w|Fo | ]. c GOF ) [∑w(Fo - (1/k)Fc )2/(no - nv)]1/2
.
Å found for the ion-paired structure and only slightly smaller
than the rx-ray value of 6.5 Å found for the dichloromethane-
solvated species. The corresponding radii for the CF3SO3- anion,
4.0-4.5 Å, are somewhat larger than the values estimated for
the solvated anion in methanol solution (ca. 3 Å25,38). Clearly,
the anion and cation are not moving at an identical rate. The
BF4- anion shows rH values in the range 3.8-3.9 Å (Table 3),
which are also a bit larger than for the isolated anion in methanol
solution.25,38 As in previous studies we assign these results to
partial ion pairing in dichloromethane solution.
cations and anions in THF solution suggest that these mono-
cations are more strongly, but not completely, associated with
the anions.
Continuing with the CF3SO3- salts, using CDCl3 as solvent,
the rH values for cations are even larger and fall in the range
7.2-7.8 Å. The corresponding radii for the CF3SO3 anion, ca.
6.3-6.9 Å (Table 4), are now ca. 2 Å larger than in dichlo-
romethane. These cation and anion rH values suggest that the
change of solvent from dichloromethane to THF and then to
CDCl3 has resulted in an increasingly tight ion pair. To contrast
the CDCl3 data, we have measured the diffusion for complex
12a in CD3CN, a much more polar solvent. As expected, the
rH value for the CF3SO3- anion, at 2.7 Å, approaches the value
of the solvated anion.
-
In THF solution the rH values for the cations of the CF3SO3
salts, 9a to 13a, are larger and fall in the range 7.0-7.8 Å (Table
4), whereas those for the anion now span the range 5.0-5.3 Å.
Ion pairing is usually more pronounced in THF than in
dichloromethane,25 and we suggest that this is reflected in these
increased radii; however, the larger solvent THF will also
contribute to the increase in the size of the cation rH, relative
to dichloromethane solutions. In any case, the rH values for the
A plot of the D value for the CF3SO3- anion versus dielectric
constant of the solvent (CHCl3 (4.8) < THF (7.6) < CH2Cl2
(8.9) < CH3CN (37.5)) is not linear. However, the graph (not
shown) clearly shows that the diffusion constant of the anion

2118 Organometallics, Vol. 26, No. 8, 2007
Nama et al.
appropriate drying agents, distilled under nitrogen. Deuterated
solvents were dried by distillation over molecular sieves and stored
under nitrogen. The ligands rac-BINAP (Strem), silver salts
(Aldrich), and 1,3-diketones 3-methyl-2,4-dione, 6, ethyl 2-methy-
lacetoacetate, 7, and (E)-3-but-2-enoyloxazolidin-2-one, 8 (Acros
Organics), were purchased from commercial sources and used as
received. The dichloro-metal complex PdCl2L2, L2 ) racemic
BINAP, and the R,â-unsaturated N-imides (3, 4, and 5) were
synthesized according to the literature.40 1H, 31P, 13C, and 19F NMR
spectra were recorded with Bruker DPX-250, 300, 400, and 500
MHz spectrometers at room temperature unless otherwise noted.
Elemental analysis and mass spectra were performed at ETH Zu¨rich.
Crystallography. Crystals of [Pd(rac-BINAP)(CH3-C(O)-
C(CH3)-C(O)-CH3)](BF4), 12b, suitable for X-ray diffraction were
obtained from a dichloromethane/hexane solution. In the same
crystallization batch, crystals with two different colors (red and
yellow, respectively) and crystal habits were present. Thus data
were collected for both; one turned out to be the expected compound
(12b) and the other a solvento complex (12b‚CH2Cl2). The two
crystals belong to different space groups with completely different
molecular packings.
increases (faster motions, less ion pairing) with an increase in
dielectric constant of the solvent.
1H,19F-HOESY NMR Experiments. To further explore the
ion paring, and to place the cation in three-dimensional space,
1
relative to the anion, H,19F-HOESY spectra for 9a-13a in
chloroform solution were measured, and these are shown in
Figure 6 . In all of these spectra the strongest cross-peaks arise
due to the fluorine spins of the CF3SO3- anion interacting with
P-phenyl (probably ortho) aromatic protons of the complexed
BINAP. There are almost no contacts to either the chelating
N-imide or the acetylacetonate. [There is a weak contact to the
strongest methyl signal in 12. The P-phenyl ortho aromatic
protons of the complexed BINAP can be partially assigned via
a
31P,1H COSY correlation.]
Consequently, we believe that the anion is (a) approaching
the positive metal and phosphorus centers via a pathway that
brings it closest to the P-phenyl groups and (b) avoiding the
region of the negatively charged chelating ligands. The illustra-
tion below offers two possible pathways of approach. It is not
necessary that the anion (indicated as a red ball) approach from
a “vertical” position (dotted arrow), as this is not sterically
favored.
Dark yellow crystals of [Pd(µ-OH)(BINAP)]2(CF3SO3)2, 2a, were
obtained from dichloromethane/ether solution. The crystals were
mounted on Bruker diffractometers, equipped with CCD detectors,
for the unit cell and space group determinations. Selected crystal-
lographic and other relevant data are listed in Table 5 and in the
Supporting Information.
Data were corrected for Lorentz and polarization factors with
the data reduction software SAINT41 and empirically for absorption
using the SADABS program.42 The structures were solved by direct
and Fourier methods and refined by full matrix least-squares43 (the
function minimized being ∑[w(Fo2 - 1/kFc2)2]). For all structures,
no extinction correction was deemed necessary. The scattering
factors used, corrected for the real and imaginary parts of the
anomalous dispersion, were taken from the literature.44 All calcula-
tions were carried out by using the PC version of the programs
WINGX,45 SHELX-97,43 and ORTEP.46
Structural Study of [Pd(rac-BINAP)(CH3-C(O)-C(CH3)-
C(O)-CH3)](BF4), 12b. The space group was unambiguously
determined from the systematic absences, while the cell constants
were refined by least-squares, at the end of the data collection. The
data were collected by using ω scans, in steps of 0.5°. For each of
the 1440 collected frames, the counting time was 30 s. The least-
squares refinement was carried out using anisotropic displacement
parameters for all non-hydrogen atoms. The BF4 anion is disordered,
as can be seen from the large ADPs, preventing an accurate
determination of the geometry. The final Fourier difference map
did not reveal any significant feature. The contribution of the
hydrogen atoms, in their calculated positions, C-H ) 0.96 Å, B(H)
) aB(Cbonded) Å2 (a ) 1.3 or 1.5 for methyl groups), was included
in the refinement using a riding model.
Conclusions
The Pd(BINAP) dication, 14, postulated by Hii, in connection
with the enantioselective Pd-catalyzed hydroamination reaction,
clearly exists in solution and can be characterized at low
temperature. It is not the major component of the mixture;
however, its dynamic nature is consistent with the ease with
which a possible product could be eliminated from the palladium
moiety to allow the next substrate molecule to complex.
The new Pd complexes, 9-13, might be generated in a
catalytic solution containing a labile Pd(II)(BINAP) moiety, a
diketone such as 6, and a base. These conditions are fulfilled
in a number of literature reports. However, their relative stability
and the 13C data for the olefinic carbons suggest that these may
not be important in the palladium-catalyzed reactions, in
agreement with a suggestion by Sodeoka.7a However, a related
Ru-enolate has recently been suggested as an active intermediate
in an asymmetric Michael addition reaction.39
Structural Study of [Pd(rac-BINAP)(CH3-C(O)-C(CH3)-
C(O)-CH3)](BF4)‚CH2Cl2, 12b‚CH2Cl2. The space group was
assumed to be P1h and confirmed by the successful refinement. The
As expected, the ion pairing in 9-13 is strongly solvent
dependent, but, even in chloroform solution, where one finds
the largest amount of ion pairing, there is no reason to believe
that the ion pair would hinder attack of, for example, a
nucleophile on the double bond of the complexed enolate, since
the counteranion prefers to remain remote from the coordinated
chelated anion.
(39) Althaus, M.; Bonaccorsi, C.; Mezzetti, A.; Santoro, F. Organome-
tallics 2006, 25, 3108-3110.
(40) Myers, J. K.; Jacobsen, E. N. J. Am. Chem. Soc. 1999, 121, 8959-
8960.
(41) BrukerAXS, SAINT, Integration Software; Bruker Analytical X-ray
Systems: Madison, WI, 1995.
(42) Sheldrick, G. M. SADABS, Program for Absorption Correction;
University of Go¨ttingen: Go¨ttingen, Germany, 1996.
(43) Sheldrick, G. M. SHELX-97, Structure Solution and Refinement
Package; Universita¨t Go¨ttingen, 1997.
Together, the structures of the two forms of the acetyl
acetonate BF4- complex, 12b, provide a rare structural picture
of a tight ion pair versus a solvent-separated analogue. Moving
the anion closer to the metal affects the cation structure.
(44) International Tables for X-ray Crystallography; Wilson, A. J. C.,
Ed.; Kluwer Academic Publisher: Dordrecht, The Netherlands, 1992; Vol.
C.
(45) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(46) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565.
Experimental Section
General Comments. All air-sensitive manipulations were carried
out under a nitrogen atmosphere. All solvents were dried over

Palladium BINAP Complexes
Organometallics, Vol. 26, No. 8, 2007 2119
cell constants were refined by least-squares, at the end of the data
collection. The data were collected by using ω scans, in steps of
0.3°. For each of the 1860 collected frames, the counting time was
30 s. The least-squares refinement was carried out using anisotropic
displacement parameters for all non-hydrogen atoms of the cation.
The BF4- group, again, showed positional disorder of the fluorine
atoms. Two different orientations for the F atoms were clearly
shown in the difference Fourier maps; split F atoms, in the two
orientations, were used to model the disordered anion and refined
isotropically (refined sof 0.5 for each site). The Fourier difference
maps also showed the presence of a clathrated CH2Cl2 molecule,
which was refined anisotropically. The H atoms were included in
the refinement as described above.
Structural Study of [Pd(µ-OH)(BINAP)]2(CF3SO3)2‚0.5H2O,
2a‚0.5H2O. The space group was unambiguously determined from
the systematic absences. The values of the cell parameters were
refined at the end of the data collection. The data were collected
by using ω scans, in steps of 0.3°. For each of the 1878 collected
frames, the counting time was 30 s. The least-squares refinement
of the cation was carried out using anisotropic displacement
parameters for all non-hydrogen atoms. Fourier difference maps
revealed the presence of a water molecule that was refined
anisotropically with an sof of 0.5 for each site. The two triflate
counterions are disordered. Anisotropic refinement of only one
cation led to a significantly better fit (as judged from a Hamilton’s
test47); the other was refined isotropically. The contribution of the
hydrogen atoms, in their calculated positions (C-H ) 0.96 Å, B(H)
) 1.3B(Cbonded) Å2), was included in the refinement using a riding
model.
TXI probe on a 400 MHz spectrometer at a set temperature of
298 K. A mixing time of 800 ms was used, and 16 scans were
taken for each of the 512 t1 increments recorded. The delay between
increments was set to 1 s (DS 4, DE 7.14 µs, pulse width (PW):
F1 3601.1 Hz, F2 1132.2 Hz).
1
(E)-N-(2-Phenylacetyl)but-2-enamide (3). H NMR (CD2Cl2,
400 MHz, 25 °C): δ 2.00 (t, 3H, J ) 6.4 Hz), 7.2 (m, 3H), 7.5-
7.9 (m, 5H), 8.86 (s, 1H). 13C{1H} NMR (CD2Cl2, 100 MHz,
25 °C): δ 18.7 (CH3), 55.9 (OCH3), 124.6 (CH3CHdCH), 128.1
(Ar), 129.2 (Ar), 133.4 (Ar), 133.6 (Ar), 147.0 (CH3CHdCH),
166.2 (ArCdO), 167.4 (NCdO).
(E)-N-(2-(4-Methoxyphenyl)acetyl)but-2-enamide (4). 1H NMR
(CD2Cl2, 400 MHz, 25 °C): δ 2.00 (t, 3H, J ) 5.6 Hz), 7.1 (m,
2H), 7.0 (d, 2H, J ) 8.8 Hz), 7.8 (d, 2H, J ) 8.8 Hz), 8.5 (s, 1H).
13C{1H} NMR (CD2Cl2, 100 MHz, 25 °C): δ 18.7 (CH3), 55.9
(OCH3), 114.5 (Ar), 124.7 (CH3CHdCH), 125.6 (Ar), 130.2 (Ar),
146.6 (CH3CHdCH), 165.4 (ArCdO), 167.3 (NCdO).
(E)-5-Methyl-N-(2-phenylacetyl)hex-2-enamide (5). 1H NMR
(CD2Cl2, 300 MHz, 25 °C): δ 1.00 (d, 3H, J ) 8.8 Hz), 1.85 (m,
1H), 2.2 (t, 2H, J ) 9.2 Hz), 7.1-7.9 (m, 7H), 8.42 (s, 1H). 13C-
{1H} NMR (CD2Cl2, 100 MHz, 25 °C): δ 22.5 (CH3)2, 28.3 (CH-
(CH3)2), 42.1 (CH2CH(CH3)2), 124.2 (CH2CHdCH), 128.1 (Ar),
129.2 (Ar), 133.4 (Ar), 133.7 (Ar), 150.8 (CH2CHdCH), 166.2
(ArCdO), 167.4 (NCdO).
1
3-Methyl-2,4-dione (6). H NMR (CD2Cl2, 250 MHz, 25 °C):
δ 1.3 (d, 3H, J ) 7.0 Hz), 2.20 (s, 3H), 3.67 (q, 1H, J ) 7.0 Hz),
2.1 (s, 3H). 13C{1H} NMR (CD2Cl2, 62.9 MHz, 25 °C): δ 12.3
(CHCH3), 28.6 (CH3CdO), 61.5 (CHCH3), 190.4 (s).
1
Ethyl 2-methylacetoacetate (7). H NMR (CD2Cl2, 400 MHz,
25 °C): δ 1.28 (t, 3H, J ) 7.2 Hz), 1.31 (d, 3H, J ) 7.2 Hz), 2.23
(s, 3H), 3.52 (q, 1H, J ) 7.2 Hz), 4.20 (q, 2H, J ) 7.2 Hz). 13C-
{1H} NMR (CD2Cl2, 62.9 MHz, 25 °C): δ 12.8 (CHCH3), 14.2
(CH3CH2), 28.6 (CH3CdO), 53.9 (CHCH3), 61.6 (CH3CH2), 170.8
(C2H5CdO), 203.9 (CH3CdO).
[3-[(E)-2-Butenoyl]-1,3-oxazolidin-2-one] (8). 1H NMR (CD2-
Cl2, 500 MHz, 203 K): δ 1.95 (d, 3H, J ) 6.4 Hz), 4.01 (t, 2H,
J ) 8.3 Hz), 4.4 (t, 2H, J ) 7.9 Hz), 7.1-7.2 (m, 2H). 13C{1H}
NMR (CD2Cl2, 125 MHz, 203 K): δ 19.5 (CH3CH), 43.5 (NCH2),
63.0 (OCH2), 121.1(CHdCHCdO), 148.2 (CH3CH), 154.7 (OCd
O), 165.8 (NCdO).
Diffusion Measurements. All of the PGSE measurements were
carried out using the stimulated echo pulse sequence and performed
on a Bruker Avance spectrometer, 400 MHz, equipped with a
microprocessor-controlled gradient unit and a multinuclear inverse
probe with an actively shielded Z-gradient coil. The shape of the
gradient pulse was rectangular, and its length was 1.75 ms. The
gradient strength was incremented in 4% steps from 4% to 60%,
so that 12-15 points could be used for regression analysis. The
time between midpoints of the gradients was 167.75 ms, and
gradient recovery time was set to 100 µs for all experiments. All
the diffusion 1H spectra were acquired using 16K points, 16
transients, a 5 s relaxation delay, and a 1.5 s acquisition time. All
the 19F spectra were acquired using 16K points, 16 or 8 transients,
a relaxation delay of 5 times T1 (approximately 15-20 s), and a 4
s acquisition time. Both the 1H and 19F diffusion experiments were
processed using Bruker software with an exponential multiplication
(EM) window function and a line broadening of 1.0 HZ. The
measurements were carried out without spinning at a set temperature
of 299 K within the NMR probe. As indicated in Table 3 and 4,
diffusion values were measured on 2 mM CD2Cl2, CDCl3, and d8-
THF solutions. Cation diffusion rates were measured using the 1H
signal from the aromatic protons of BINAP and/or from chelated
ligand signals. Anion diffusion was obtained from the 19F reso-
nances. The error in the D values is thought to be (0.06. The
solvent viscosities used for the calculation of rH were 0.414, 0.534,
and 0.461 for CD2Cl2, CDCl3, and d8-THF, respectively.
[Pd(rac-BINAP)(C11H10NO2)][CF3SO3] (9a). To 1 equiv of [Pd-
(µ-OH)(rac-BINAP)]2[CF3SO3]2 (99.5 mg, 1790.36 g mol-1, 55.6
× 10-3 mol) was added 2 equiv of the C11H11NO2 (21 mg, 189 g
mol-1, 111.1 × 10-3 mol) in dichloromethane. The reaction mixture
was stirred at 25 °C for 3 h. The resulting yellow solution was
reduced in Vacuo. The resulting residue was washed with Et2O to
afford [C56H42P2O5NF3PdS], 9a (yield: 100 mg, 0.094 mol 84%).
CHN % {found (calcd)} [Pd(rac-BINAP)(C11H10NO2)][CF3SO3]‚
1
NOE Measurements. The H,1H NOESY NMR experiments
were acquired by the standard three-pulse sequence (noesyph) using
a 1 s relaxation delay and 600 ms of mixing time on a Bruker
500 MHz spectrometer at a set temperature of 203 K (DS 16, DE
6.0 µs, pulse width (PW): F1 4496.4 Hz, F2 4496.4 Hz). The
19F,1H-HOESY NMR experiments were acquired by the standard
four-pulse sequence (invhoesy) and carried out using a doubly tuned
1
H2O: C {62.07 (61.95)}, H {4.10 (4.03)}, N {1.29 (1.29)}. H
NMR (CD2Cl2, 400 MHz, 25 °C): δ 1.65 (d, 3H, H1, J ) 6.5 Hz),
5.7-6.0 (m, 2H, H2/3), 6.7-7.9 (m, 37H). 31P{1H} NMR (CD2-
Cl2, 161 MHz, 25 °C): δ 33.5 ppm (d, AB spin, J ) 32 Hz). 19F
NMR (CD2Cl2, 282 MHz, 25 °C): δ -78.8 (s). 13C{1H} NMR
(CD2Cl2, 100 MHz, 25 °C): δ 18.2 (s, C1), 128.1 (s, C8), 128.8
(s, C9), 129.6 (s, C3), 130.1 (s, C7), 135.4 (s, C6), 146.5 (s, C2),
173.3 (d, C5, 1JCN ) 3 Hz), 174.1 (d, C4, 1JCN ) 3 Hz), 120-180
ppm. (BINAP) MS (ESI; m/z): M+ 916.2, [M - C11H10NO2]+
729.0.
(47) Hamilton, W. C. Acta. Crystallogr. 1965, 17, 502.
(48) Zuccaccia, D.; Macchioni, A. Organometallics 2005, 24, 3476-
3486.
(49) Mann, B. E.; Taylor, B. F. 13C NMR Data for Organometallic
Compounds; Academic Press: London, 1981.

2120 Organometallics, Vol. 26, No. 8, 2007
Nama et al.
1
[Pd(rac-BINAP)(C12H12NO3)][CF3SO3] (10a). To 1 equiv of
H {4.27 (4.23)}. H NMR (CD2Cl2, 400 MHz, 25 °C): δ 1.58 (s,
6H, H1,6), 1.8 (s, 3H, H4), 6.7-7.8 (m, 32H). 31P{1H} NMR (CD2-
Cl2, 161 MHz, 25 °C): δ 31.9 ppm (s). 19F NMR (CD2Cl2, 282
MHz, 25 °C): δ -78.8 (s). 13C{1H} NMR (CD2Cl2, 100 MHz,
25 °C): δ 16.0 (s, C4), 26.9 (t, C1/C6, JCP ) 5 Hz), 104.3 (s, C3),
185.5 (s, C2/C5), 120-180 ppm. (BINAP) MS (ESI; m/z): M+
841.1, [M - C6H9O2]+ 729.0.
[Pd(rac-BINAP)(C7H11O3)][CF3SO3] (13a). To 1 equiv of [Pd-
[Pd(µ-OH)(rac-BINAP)]2[CF3SO3]2 (2.8 mg, 1790.36 g mol-1, 23.9
× 10-3 mol) was added 2 equiv of the C12H13NO3(10.6 mg,
219.2 g mol-1, 48.3 × 10-3 mol) in dichloromethane. The reaction
mixture was stirred at 25 °C for 3 h. The resulting yellow solution
was reduced in Vacuo. The resulting residue was washed with Et2O
to afford 10a (yield: 45 mg, 0.0410 mol, 85%). CHN % {found
(calcd)} [Pd(rac-BINAP)(C12H12NO3)][CF3SO3]‚H2O: C {61.48
(61.89)}, H {4.17 (4.11)}, N {1.26 (1.30)}. 1H NMR (CD2Cl2, 400
MHz, 25 °C): δ 1.63 (d, 3H, H1 J ) 6.0 Hz), 3.8 (s, 3H, H10),
5.7-5.9 (m, 2H, H2/3), 6.6-7.9 (m, 36H). 31P{1H} NMR (CD2-
(µ-OH)(rac-BINAP)] 2[CF3SO3]2 (40.7 mg, 1790.36 g mol-1, 24.4
× 10-3 mol) was added 2 equiv of the C7H12O3 (7.0 µL, 144.17 g
mol-1, 1.019 g cm-3) in dichloromethane. The reaction mixture
was stirred at 25 °C for 3 h. The resulting yellow solution was
reduced in Vacuo. The resulting residue was washed with Et2O to
afford 13a (yield: 42 mg, 0.045 mol, 89%). CHN % {found
(calcd)} [Pd (rac-BINAP)(C7H11O3)][CF3SO3]‚H2O: C {60.10
2
Cl2, 161 MHz, 25 °C): δ 33.5 ppm (d, AB spin, JPP ) 33 Hz).
19F NMR (CD2Cl2, 282 MHz, 25 °C): δ -78.8 (s). 13C{1H} NMR
(CD2Cl2, 100 MHz, 25 °C): δ 18.2 (s, C1), 55.6 (s, C10), 113.4
(s, C8), 127.9 (s, C6), 129.6 (s, C3), 132.5 (s, C7), 135.4 (s, C6),
145.9 (s, C2), 164.7 (s, C9), 172.8 (d, C5), 173.2 (d, C4, 1JCN ) 3
Hz), 120-180 ppm. (BINAP) MS (ESI; m/z): M+ 946.3.
1
(60.02)}, H {4.49 (4.46)}. H NMR (CD2Cl2, 400 MHz, 25 °C):
δ 0.75 (t, 3H, H7, J ) 7.1 Hz), 1.47 (s, 3H, H1), 1.7 (s, 3H, H4),
2.7-2.9 (m, 2H, H6), 6.7-7.8 (m, 32H). 31P{1H} NMR (CD2Cl2,
2
2
161 MHz, 25 °C): δ 30.4 ppm (d, Jpp ) 38 Hz), 34.7 (d, Jpp
)
[Pd(rac-BINAP)(C14H16NO2)][CF3SO3] (11a). To 1 equiv of
38 Hz). 19F NMR (CD2Cl2, 282 MHz, 25 °C): δ -154 (s). 13C-
{1H} NMR (CD2Cl2, 100 MHz, 25 °C): δ 13.0 (s, C4), 14.3 (s,
C7), 25.8 (s, C1), 60.9 (s, C6), 90.5 (s, C3), 169.8 (s, C2), 184.2
(s, C5), 120-180 ppm. (BINAP) MS (ESI; m/z): M+ 871.2, [M -
C7H11O3]+ 729.0.
[Pd(rac-BINAP)(C11H10NO2)][BF4] (9b). To 1 equiv of [Pd-
(µ-OH)(rac-BINAP)]2[BF4]2 (33.1 mg, 1665.84 g mol-1, 19.8 ×
10-3 mol) was added 2.1 equiv of the C11H11NO2 (6.7 mg, 189 g
mol-1, 35.4 × 10-3 mol) in dichloromethane. The reaction mixture
was stirred at 25 °C for 3 h. The resulting yellow solution was
reduced in Vacuo. The resulting residue was washed with Et2O to
1
[Pd(µ-OH)(rac-BINAP)] 2[CF3SO3]2 (35 mg, 1790.36 g mol-1, 19.5
× 10-3 mol) was added 3 equiv of the C14H17NO2 (13.6 mg
231.13 g mol-1, 58.8 × 10-3 mol) in dichloromethane. The reaction
mixture was stirred at 25 °C for 3 h. The resulting yellow solution
was reduced in Vacuo. The resulting residue was washed with Et2O
afford [C55H42BF4NO2P2Pd], 9b (yield: 31 mg, 87%). H NMR
(CD2Cl2, 400 MHz, 25 °C): δ 1.65 (d, 3H, H1, J ) 6.8 Hz), 5.7-
6.0 (m, 2H, H2/3), 6.7-7.9 (m, 37H). 31P{1H} NMR (CD2Cl2, 161
MHz, 25 °C): δ 33.5 ppm (d, AB spin, J ) 32 Hz). 19F NMR
(CD2Cl2, 282 MHz, 25 °C): δ -153.9 (s). 13C{1H} NMR (CD2-
Cl2, 100 MHz, 25 °C): δ 18.0 (s, C1), 128.1 (s, C8), 128.9 (s,
C9), 129.6 (s, C3), 130.1 (s, C7), 135.4 (s, C6), 146.5 (s, C2), 173.3
1
to afford 11a (yield: 58 mg, 89%). H NMR (CD2Cl2, 400 MHz,
25 °C): δ 0.81 (t, 6H, J ) 5.2 Hz, H1,3), 1.53 (m, 1H, H2), 1.9
1
1
(m, 2H, H4), 5.3-6.0 (m, 2H, H5,6), 6.7-7.8 (m, 37H). 31P{1H}
(d, C5, JCN ) 3 Hz), 174.0 (d, C4, JCN ) 3 Hz), 120-180.
(BINAP) MS (ESI; m/z): M+ 916.2, [M - C11H10NO2]+ 729.0.
[Pd(rac-BINAP)(C12H12NO3)][BF4] (10b). To 1 equiv of [Pd-
(µ-OH)(rac-BINAP)]2[BF4]2 (51 mg, 1665.84 g mol-1, 30.6 × 10-3
2
NMR (CD2Cl2, 161 MHz, 25 °C): δ 33.6 ppm (d, Jpp ) 33 Hz),
2
34.7 (d, Jpp ) 33 Hz). 19F NMR (CD2Cl2, 282 MHz, 25 °C): δ
-79.1(s). 13C{1H} NMR (CD2Cl2, 100 MHz, 25 °C): δ 22.4 (s,
C3), 22.6 (s, C1), 28.0 (s, C4), 41.9 (s, C2), 129.5 (s, C6), 150.1
(s, C5), 173.3 (s, C8), 174.0 (s, C7) 120-180 ppm. (BINAP) MS
(ESI; m/z): M+ 871.2, [M - C14H16NO2]+ 729.0.
mol) was added 2 equiv of the C12H13NO3 (13.4 mg, 219.2 g mol-1
,
61.1 × 10-3 mol) in dichloromethane. The reaction mixture was
stirred at 25 °C for 3 h. The resulting yellow solution was reduced
in Vacuo. The resulting residue was washed with Et2O to afford
10b (yield: 55 mg, 0.0410 mol, 87%). 1H NMR (CD2Cl2, 400 MHz,
25 °C): δ 1.63 (d, 3H, H1 J ) 6.8 Hz), 3.8 (s, 3H, H10), 5.7-5.9
(m, 2H, H2/3), 6.6-7.9 (m, 36H). 31P{1H} NMR (CD2Cl2, 161
MHz, 25 °C): δ 33.5 (d, AB spin, 2JPP ) 33 Hz). 19F NMR (CD2-
Cl2, 282 MHz, 25 °C): δ -153.9 (s). 13C{1H} NMR (CD2Cl2, 100
MHz, 25 °C): δ 17.9 (s, C1), 55.8 (s, C10), 113.4 (s, C8), 127.9
(s, C6), 129.6 (s, C3), 132.5 (s, C7), 135.4 (s, C6), 145.8 (s, C2),
[Pd(rac-BINAP)(C6H9O2)][CF3SO3] (12a). To 1 equiv of [Pd-
1
(µ-OH)(rac-BINAP)]2[CF3SO3]2 (50 mg, 1790.36 g mol-1, 27.9
× 10-3 mol) was added 2 equiv of the C6H10O2 (6.5 µL, 144.14 g
mol-1, 0.981 g cm-3) in dichloromethane. The reaction mixture
was stirred at 25 °C for 3 h. The resulting yellow solution was
reduced in Vacuo. The resulting residue was washed with Et2O to
afford 12a (yield: 48 mg, 0.048 mol, 86%). CHN % [Pd(rac-
BINAP)(C6H9O2)][CF3SO3]‚H2O: {found (calcd)} C {61.73 (60.86)},
164.2 (s, C9), 172.8 (d, C5), 173.2 (d, C4, JCN ) 3 Hz), 120-
180. (BINAP) MS (ESI; m/z): M+ 946.3.
[Pd(rac-BINAP)(C14H16NO2)][BF4] (11b). To 1 equiv of [Pd-
(µ-OH)(rac-BINAP)]2[BF4]2 (52.3 mg, 1665.84 g mol-1, 31.4 ×
10-3 mol) was added 3 equiv of the C14H17NO2 (21.8 mg,
231.13 g mol-1, 94.3 × 10-3 mol) in dichloromethane. The reaction
mixture was stirred at 25 °C for 3 h. The resulting yellow solution

Palladium BINAP Complexes
Organometallics, Vol. 26, No. 8, 2007 2121
was reduced in Vacuo. The resulting residue was washed with Et2O
(CD2Cl2, 161 MHz, 25 °C): δ 30.4 (d, 2Jpp ) 38 Hz), 34.7 (d, 2Jpp
) 38 Hz). 19F NMR (CD2Cl2, 282 MHz, 25 °C): δ -154 (s). 13C-
{1H} NMR (CD2Cl2, 100 MHz, 25 °C): δ 13.0 (s, C4), 14.3 (s,
C7), 25.8 (s, C1), 60.9 (s, C6), 90.5 (s, C3), 169.9 (s, C2), 184.0
(s, C5), 120-180. (BINAP) MS (ESI; m/z): M+ 871.2, [M -
C7H11O3]+ 729.0.
[Pd(rac-BINAP)(C7H9NO3)][CF3SO3]2 (14). 1H NMR (CD2Cl2,
500 MHz, 203 K): δ 1.56 (d, 3H, H1, J ) 6.8 Hz), 4.28 (m, 2H,
H7), 4.5 (t, 2H, H6, J ) 9.8 Hz), 5.0 (m, 1H, H2), 5.86(d, 1H,
H3). 13C{1H} NMR (CD2Cl2, 125 MHz, 203 K): δ 19.0 (s, C1),
45.7 (d, C7), 66.2 (s, C6), 119.5 (s, C3), 157.3 (s, C2), 158.8 (s,
C5), 165.4 (s, C4). 31P{1H} NMR (CD2Cl2, 202 MHz, 203 K): δ
37.4 (d, J ) 9.5 Hz), 35.6 (d, J ) 9.5 Hz).
1
to afford 11b (yield 54 mg, 82%). H NMR (CD2Cl2, 400 MHz,
25 °C): δ 0.81 (t, 6H, J ) 5.2 Hz), 1.53 (m, 1H), 1.9 (m, 2H),
5.3-6.0 (m, 2H), 6.7-7.8 (m, 37H). 31P{1H} NMR (CD2Cl2, 161
MHz, 25 °C): δ 33.6 (d, AB spin, 2JPP ) 32 Hz). 19F NMR (CD2-
Cl2, 282 MHz, 25 °C): δ -154.0 (s). 13C{1H} NMR (CD2Cl2, 100
MHz, 25 °C): δ 22.4 (s, C3), 22.6 (s, C1), 28.0 (s, C4), 41.9 (s,
C2), 129.5 (s, C6), 150.1 (s, C5), 173.3 (s, C8), 174.0 (s, C7), 120-
150. (BINAP) MS (ESI; m/z): M+ 871.2, [M - C14H16NO2]+ 729.0.
[Pd(rac-BINAP)(C6 H9O2)][BF4] (12b). To 1 equiv of [Pd(µ-
OH)(rac-BINAP)]2[BF4]2 (54.8 mg, 1665.84 g mol-1, 27.9 × 10-3
mol) was added 2 equiv of the C6H10O2 (7.7 µL, 144.14 g mol-1
,
0.981 g cm-3) in dichloromethane. The reaction mixture was stirred
at 25 °C for 3 h. The resulting yellow solution was reduced in
Vacuo. The resulting residue was washed with Et2O to afford 12b
(yield: 50 mg, 0.053 mol, 96%). CHN % {found (calcd)} [Pd-
(rac-BINAP)(C6H9O2)][BF4]: C {63.92 (64.57)}, H {4.60 (4.55)}.
1H NMR (CD2Cl2, 400 MHz, 25 °C): δ 1.57 (s, 6H), 1.82 (s, 3H),
6.7-7.8 (m, 32H). 31P{1H} NMR (CD2Cl2, 161 MHz, 25 °C): δ
31.9 (s). 19F NMR (CD2Cl2, 282 MHz, 25 °C): δ -154 (s). 13C-
{1H} NMR (CD2Cl2, 100 MHz, 25 °C): δ 15.9 (s, C4), 26.6 (t,
C1/C6, JCP ) 5 Hz), 104.3 (s, C3), 185.3 (s, C2/C5), 120-180.
(BINAP) MS (ESI; m/z): M+ 840.9, [M - C6H9O2]+ 729.0.
[Pd(rac-BINAP)(C7H11O3)][BF4] (13b). To 1 equiv of [Pd(µ-
OH)(rac-BINAP)]2[BF4]2 (67.0 mg, 1665.84 g mol-1, 40.2 × 10-3
Crystallographic data have been deposited at the Cambridge
Crystallographic Data Centre (CCDC Nos. 624568 (2a), 624569
(12b), and 624570 (12b‚CH2Cl2)).
Acknowledgment. P.S.P. thanks the Swiss National Science
Foundation and the ETH Zurich for support, as well as the
Johnson Matthey Organization for the loan of palladium salts.
A.A. thanks MURST for a grant (PRIN 2004).
Supporting Information Available: Experimental details and
a full listing of crystallographic data, including tables of positional
and isotropic equivalent displacement parameters, anisotropic
displacement parameters, calculated positions of the hydrogen
atoms, bond distances, bond angles, and torsional angles for
compounds 2a, 12b, and 12b‚CH2Cl2. This material is available
free of charge via the Internet at http://pubs.acs.org.
mol) was added 2 equiv of the C7H12O3 (11.4 µL, 144.17 g mol-1
,
1.019 g cm-3) in dichloromethane. The reaction mixture was stirred
at 25 °C for 3 h. The resulting yellow solution was reduced in
Vacuo. The resulting residue was washed with Et2O to afford 13b
1
(yield: 47 mg, 0.045 mol, 86%). H NMR (CD2Cl2, 400 MHz,
25 °C): δ 0.75 (t, 3H, H7, J ) 7.1 Hz), 1.47 (s, 3H, H1), 1.7 (s,
3H, H4), 2.7-2.9 (m, 2H, H6), 6.7-7.8 (m, 32H). 31P{1H} NMR
OM0700157