Synthesis of β-P,N aminophosphines and coordination chemistry to PdII. X-ray structures of [PdCl2(Ph2PCH2CH(Ph)NHPh-κP,κN)] and [PdCl(η3-C3H5)(Ph2 PCH2CH(Ph)NHPh-κP)]

Article abstract of DOI:10.1021/ic000867y

The reaction of the C=N bond in PhCH=NPh with the carbanionic species Ph₂PCH₂^-, leading to the N-phenyl β-aminophosphine Ph₂PCH₂CH(Ph)NHPh, L¹, is described. This molecule reacts with different organic electrophiles to afford related compounds Ph₂PCH₂CH(Ph)NPhX (X = SiMe₃, L²; COPh, L⁴), [Ph₂MePCH₂CH(Ph)NHPh]⁺(I^-), L³, and [Ph₂PCH₂CH(Ph)N(Ph)CO]₂, L⁵, containing two amido and two phosphino functions. The coordination properties of L¹, L², and L⁴ have been studied in palladium chemistry. The X-ray structure of [PdCl₂(Ph₂PCH₂-CH(Ph)NHPh-κP, κN)] shows the bidentate coordination mode for the L¹ ligand with equatorial C_Ph-N_Ph phenyl groups. [PdCl₂(Ph₂PCH₂CH(Ph)NHPh-κP,κN)] crystallizes at 298 K in the space group P2_1/n with cell parameters a = 10.689(2) A, b = 21.345(3) A, c =12.282(2) A, β = 90.294(12)°, Z = 4, D_calcd = 1.526. The reaction between 2 equiv of L¹ and [PdCl(η³-C₃H₅)]₂ affords the [PdCl(η³-C₃H₅) (Ph₂PCH₂CH(Ph)NHPh-κP)] complex in which an unexpected N-H···Cl intramolecular interaction has been observed by an X-ray diffraction analysis. [PdCl(η³-C₃H₅) (Ph₂PCH₂CH(Ph)NHPh-κP)] crystallizes at 298 K in the monoclinic space group Cc with cell parameters a = 10.912(1) A, b = 17.194(2) A, c = 14.169(2) A, β = 100.651(9)°, Z = 4, D_calcd = 1.435. Neutral and cationic alkyl or allyl palladium chloride complexes containing L¹ are also reported as well as a neutral allyl palladium chloride complex containing L⁴. Variable-temperature ³¹p{¹H} NMR studies on the allyl complexes show that the η³/η¹ allyl interconversion is enhanced by a positive charge and also by a N-H···Cl intramolecular interaction.

Full text of DOI:10.1021/ic000867y

Inorg. Chem. 2001, 40, 1597-1605
1597
Synthesis of â-P,N Aminophosphines and Coordination Chemistry to PdII. X-ray Structures
of [PdCl2(Ph2PCH2CH(Ph)NHPh-KP,KN)] and [PdCl(η3-C3H5)(Ph2PCH2CH(Ph)NHPh-KP)]
Jacques Andrieu,* Jean-Michel Camus, Jochen Dietz, Philippe Richard, and Rinaldo Poli
Laboratoire de Synthe`se et d’Electrosynthe`se Organome´talliques, Universite´ de Bourgogne,
Faculte´ des Sciences “Gabriel”, 6, Boulevard Gabriel, 21000 Dijon, France
ReceiVed August 1, 2000
The reaction of the CdN bond in PhCHdNPh with the carbanionic species Ph2PCH2-, leading to the N-phenyl
â-aminophosphine Ph2PCH2CH(Ph)NHPh, L1, is described. This molecule reacts with different organic electrophiles
to afford related compounds Ph2PCH2CH(Ph)NPhX (X ) SiMe3, L2; COPh, L4), [Ph2MePCH2CH(Ph)NHPh]+(I-),
L3, and [Ph2PCH2CH(Ph)N(Ph)CO]2, L5, containing two amido and two phosphino functions. The coordination
properties of L1, L2, and L4 have been studied in palladium chemistry. The X-ray structure of [PdCl2(Ph2PCH2-
CH(Ph)NHPh-κP,κN)] shows the bidentate coordination mode for the L1 ligand with equatorial CPh-NPh phenyl
groups. [PdCl2(Ph2PCH2CH(Ph)NHPh-κP,κN)] crystallizes at 298 K in the space group P21/n with cell parameters
a ) 10.689(2) Å, b ) 21.345(3) Å, c ) 12.282(2) Å, â ) 90.294(12)°, Z ) 4, Dcalcd ) 1.526. The reaction
between 2 equiv of L1 and [PdCl(η3-C3H5)]2 affords the [PdCl(η3-C3H5)(Ph2PCH2CH(Ph)NHPh-κP)] complex in
which an unexpected N-H‚‚‚Cl intramolecular interaction has been observed by an X-ray diffraction analysis.
[PdCl(η3-C3H5)(Ph2PCH2CH(Ph)NHPh-κP)] crystallizes at 298 K in the monoclinic space group Cc with cell
parameters a ) 10.912(1) Å, b ) 17.194(2) Å, c ) 14.169(2) Å, â ) 100.651(9)°, Z ) 4, Dcalcd ) 1.435. Neutral
and cationic alkyl or allyl palladium chloride complexes containing L1 are also reported as well as a neutral allyl
palladium chloride complex containing L4. Variable-temperature 31P{1H} NMR studies on the allyl complexes
show that the η3/η1 allyl interconversion is enhanced by a positive charge and also by a N-H‚‚‚Cl intramolecular
interaction.
Introduction
neutral and cationic palladium complexes is the examination
of the consequences of a relatively weak electron-donating
-NHPh group on the κP versus κP,κN coordination mode as
well as on hemilability.
The synthesis and the coordination studies of aminophos-
phines have been the subject of detailed investigations owing
to catalytic applications of the corresponding Ru,1-3 Ni,4,5 Rh,6,7
and Pd8,9 complexes. However, the synthesis of aminophos-
phines in which the heteroatoms are separated by two carbon
atoms (named hereafter â-P,N) requires a multistep reaction or
a tedious method.10-13 Moreover, functional phosphines of this
type containing a secondary amine have received little atten-
tion.10,11 In particular, no study of the potential hemilabile
character of such ligands has been reported. Therefore, we were
interested in elaborating a short synthetic method allowing
opening of the access not only to new â-P,N ligands but also
to their complexes. A particular interest for such ligands in
We have recently reported that the CdN double bond in free
organic or (CO)3Cr-coordinated benzaldimines undergoes the
addition of Ph2PH to afford the first stable chiral R-P,N
ligands.14,15 Then, we wished to extend the reactivity of the
-
N-phenylbenzaldimines toward Ph2PCH2 in order to open a
one-step access to related â-aminophosphines. In fact, the
carbanionic Ph2PCH2- reagent16-18 has allowed preparation of
â-alcohol-phosphines by a similar addition to the CdO double
bond of benzophenone or hexafluoroacetone.16,19
Experimental Section
All reactions were performed in Schlenk-type flasks under argon.
Solvents were purified and dried under argon by conventional methods.
The 1H, 31P{1H}, and 13C{1H} NMR spectra were recorded on a Bruker
AC 200 instrument for both room and higher temperature experiments.
* Author to whom correspondence should be addressed. E-mail:
Jacques.Andrieu@u-bourgogne.fr. Tel/fax: + 03 80 39 60 73.
(1) Yang, H.; Alvarez, M.; Lugan, N.; Mathieu, R. J. Chem. Soc., Chem.
Commun. 1995, 1721-1722.
(2) Yang, H.; Lugan, N.; Mathieu, R. An. Quim. Int. Ed. 1997, 93, 28-
38.
1
1
The H-1H and H-13C COSY, DEPT-135, and the variable- (low-)
temperature experiments were recorded on a Bruker 500 DRX
(3) Yang, H.; Alvarez-Gressier, M.; Lugan, N.; Mathieu, R. Organome-
tallics 1997, 16, 1401-1409.
(4) Hayashi, T.; Konishi, M.; Fukushima, M.; Kanehira, K.; Hioki, T.;
Kumada, M. J. Org. Chem. 1983, 48, 2195-2202.
(5) Nagel, U.; Nedden, H. G. Chem. Ber. 1997, 5355-542.
(6) Arena, C. G.; Nicolo`, F.; Drommi, D.; Bruno, G.; Faraone, F. J. Chem.
Soc., Chem. Commun. 1994, 2251-2252.
(12) Basset, M.; Davies, D. L.; Neild, N.; Prouse, L. J. S.; Russell, D. R.
Polyhedron 1991, 10, 507-507.
(13) Barluenga, J.; Lo´pez, F.; Palacios, F. Synthesis 1989, 298-300.
(14) Andrieu, J.; Dietz, J.; Poli, R.; Richard, P. New J. Chem. 1999, 23,
581-583.
(7) Kostas, I. D.; Screttas, C. G. J. Organomet. Chem. 1999, 585, 1-6.
(8) Drent, E.; Arnoldy, P.; Budzelaar, P. H. M. J. Organomet. Chem. 1993,
455, 247- 253.
(15) Andrieu, J.; Baldoli, C.; Maiorana, S.; Poli, R.; Richard, P. Eur. J.
Org. Chem. 1999, 3095-3097.
(16) Peterson, D. J. J. Organomet. Chem. 1967, 8, 199-208.
(17) Kyba, E. P. J. Am. Chem. Soc. 1975, 97, 2554-2555.
(18) Kyba, E. P. J. Am. Chem. Soc. 1976, 98, 4805-4809.
(19) Boere´, R. T.; Montgomery, C. D.; Payne, N. C.; Willis, C. J. Inorg.
Chem. 1985, 24, 3680-3687.
(9) Newkome, G. R. Chem. ReV. 1993, 93, 2067-2089.
(10) Albinati, A.; Lianza, F.; Berger, H.; Pregosin, P. S.; Ru¨egger, H.; Kunz,
R. W. Inorg. Chem. 1993, 32, 478-486.
(11) Nagel, U.; Nedden, H. G. Chem. Ber. 1997, 130, 385-397.
10.1021/ic000867y CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/01/2001

1598 Inorganic Chemistry, Vol. 40, No. 7, 2001
Andrieu et al.
instrument. Numbering scheme used for the L1 ligand: Ha, Hb, and Hc
are the nonequivalent PCH2 and the NCH protons, respectively.
Numbering scheme used for the allyl ligand: C1, C2, and C3 are trans
to the P atom, the central carbon, and cis to the P atom, respectively.
Whenever diastereoisomeric forms are present, the carbon and proton
chemical shifts are noted C, H and C′, H′ respectively. The infrared
spectra were recorded in Nujol or in CH2Cl2 solution with an IFS 66
Perkin-Elmer instrument. The elemental analyses were performed at
the LSEO in Dijon. Compounds [Pd(η3-C3H5)(µ-Cl)]2, [PdCl2(COD)],
and [Pd(CH3)Cl(COD)] were prepared according to the literature.20,21
The reagents n-BuLi (2.5 M in hexanes), PhCHdNPh, and Ph2PCH3
were commercial products from Aldrich and were used as received.
Synthesis of Ph2PCH2CH(Ph)NHPh, L1. Lithiation of methyl-
diphenylphosphine was carried out according to Peterson’s procedure
from TMEDA (2.0 mL, 13.25 mmol) and n-BuLi (5.3 mL, 13.25
mmol).16 After the mixture was stirred for 15 min at room temperature,
methyldiphenylphosphine (2.5 mL, 13.25 mmol) was added. The
mixture was stirred further, leading to a bright yellow precipitate within
30 min. The precipitate was dissolved by addition of 4 mL of THF.
After stirring for an additional 30 min, N-benzylideneaniline (1.79 g,
9.88 mmol) was added and the mixture was stirred overnight. The
reaction mixture was then transferred into 30 mL of degassed water.
The organic phase was separated, and the water phase was separated
and extracted twice with 20 mL of Et2O. After drying over MgSO4,
the solvent was removed in vacuo. Addition of 5 mL of cold dry
methanol afforded a precipitate, which was isolated by filtration.
Recrystallization from cold methanol afforded the ligand L1 as a white
powder, which was isolated by filtration and dried in vacuo for 3 h.
Yield: 1.82 g (48.3% relative to the imine used).1H NMR (CDCl3):
7.70-6.21 (m, 20H aromatics), 4.38 (m, 2H, NCH + NH), 2.59 (m,
5.05 (m, 1H, NCH), 4.56 (s, br, 1H, NH), 3.05 (d, 3H, CH3P, 2J(P,H)
) 14.3 Hz), 2.85 (m, 2H, PCH2). 31P{1H} NMR (CDCl3): 21.41 (s).
13C{1H} NMR (CDCl3): 146.1-114.6 (m, 24C aromatics), 54.1 (d,
2
1C, NCH, J(P,C) ) 3.8 Hz), 31.6 (d, 1C, PCH2, J(P,C) ) 48.0 Hz),
and 11.3 (d, 1C, PCH3, J(P,C) ) 54.6 Hz). Anal. Calcd for C27H27-
NPI: C, 61.96; H, 5.20; N, 2.68. Found: C 61.83; H, 5.437; N, 2.55.
Synthesis of Ph2PCH2CH(Ph)N(Ph)C(O)Ph, L4. To a suspension
of L1 (0.200 g, 0.525 mmol) in 20 mL of Et2O was added Et3N (0.18
mL, 1.29 mmol). The mixture was cooled to 0 °C, and benzoyl chloride
(70 µL, 0.545 mmol) was then introduced. After stirring for 2.5 h, the
suspension was hydrolyzed by addition of 13 mL of 0.1 M NaOH.
The colorless organic phase was separated, and the aqueous phase was
extracted with 10 mL of Et2O. After filtration of the combined organic
layers, the solvent was removed in vacuo yielding yellow oil. The
product was obtained as a colorless oil following removal of the volatile
impurities by heating at 120 °C under vacuum for 2 h. Yield: 0.235 g
(92%).1H NMR (C6D6): 7.14-6.65 (m, 25H aromatics), 6.49 (m, 1H,
NCHc), 3.09 part A of ABMX system for the PCHaHb-CHc (ddd, 1H,
PCHa, 2J(Ha,Hb) ) 14.0 Hz, 2J(P,Ha) ) 11.0 Hz, 3J(Ha,Hc) ) 3.0 Hz),
2.76 part B of ABMX system for the PCHaHb-CHc (ddd, 1H, PCHb,
2J(Hb,Ha) ) 14.0 Hz, 2J(P,Hb) ) 5.0 Hz, 3J(Hb,Hc) ) 2.5 Hz). 31P{1H}
NMR (CDCl3): -22.25 (s). 13C{1H} NMR (CDCl3): 171.6 (s, 1C, NC-
2
(O)Ph), 140.7-127.9 (m, 30C aromatics), 57.4 (d, 1C, NCH, J(P,C)
) 16.2 Hz) and 32.2 (d, 1C, PCH2, J(P,C) ) 14.3 Hz). IR (Nujol):
ν(CdO) ) 1642 cm-1 (s). Elemental analysis of the pure ligand could
not be performed due to its sensitive and very viscous nature. It was
used without further purification.
Synthesis of [Ph2PCH2CH(Ph)N(Ph)C(O)]2, L5. To a suspension
of L1 (0.500 g, 1.313 mmol) in 15 mL of Et2O was added Et3N (0.5
mL, 3.58 mmol). The mixture was cooled to 0 °C, and oxalyl chloride
(57 µL, 0.653 mmol) was then introduced. After stirring for 3 h at
room temperature, the suspension was hydrolyzed by 33 mL of degassed
0.1 M NaOH. The colorless organic phase was separated, and the
aqueous phase was extracted with 3 × 10 mL of Et2O. After drying of
the combined organic layers over MgSO4 and filtering, the solvent was
removed in vacuo and a yellow residue was obtained. The pure ligand
was obtained as a white powder by crystallization from cold methanol.
Yield: 0.330 g (61%).1H NMR (CDCl3): 7.29-6.64 (m, 40H aromat-
ics), 5.71 (m, 2H, NCH), 2.40 (m, 4H, PCH2). 31P{1H} NMR (CDCl3):
-23.93 (s) and -24.01 (s) (two diastereoisomers in ca. 1:1 ratio). 13C-
{1H} NMR (CDCl3): 164.5 (s, 1C, NC(O)Ph) and 164.4 (s, 1C, NC′-
1
2H, PCH2). H NMR (C6D6): 7.70-6.21 (m, 20 H aromatics), 4.37
(m, 1H, NCHc), 4.19 (s, br, 1H, NH, exchange with D2O), 2.43 part A
of ABMX system for the PCHaHb-CHc (ddd, 1H, PCHa, 2J(Ha,Hb) )
14.0 Hz, 2J(P,Ha) ) 4.8 Hz, 3J(Ha,Hc) ) 1.3 Hz), 2.28 part B of ABMX
2
system for the PCHaHb-CHc (ddd, 1H, PCHb, J(Hb,Ha) ) 14.0 Hz,
2J(P,Hb) ) 9.9 Hz, 3J(Hb,Hc) ) 3.8 Hz). 31P{1H} NMR (CDCl3): -22.02
(s). 13C{1H} NMR (CDCl3): 147.4-113.9 (m, 24 C aromatics), 56.6
2
(d, 1C, NCH, J(P,C) ) 15.0 Hz) and 39.5 (d, 1C, PCH2, J(P,C) )
15.9 Hz). IR (Nujol): ν(ΝΗ) ) 3390 cm-1 (w). Anal. Calcd for C26H24-
NP: C, 81.87; H, 6.33; N, 3.67. Found: C, 82.21; H, 6.34; N, 3.37.
Synthesis of Ph2PCH2CH(Ph)N(Ph)(Si(CH3)3), L2. This ligand has
been prepared similarly to L1, from PPh2Me (2.1 mL, 0.011 mol),
n-BuLi (6.7 mL, 0.011 mol), TMEDA (1.6 mL, 0.011 mol), and
PhCHdNPh (1.95 g, 0.011 mol). The mixture was left to stir overnight.
Instead of the addition of distilled water, Me3SiCl (1.4 mL, 0.011 mol)
was added dropwise. There was a color change from red to pale yellow,
and the mixture was stirred for 3 h. The solvent was removed. The
dark brown residue was then dissolved in 20 mL of toluene and filtered
through Celite. Due to high solubility in common solvents (i.e., ether
or pentane), the product could not be purified by washing. Consequently,
the product was purified by removal of Ph2PCH3 and TMEDA by
vacuum distillation at 110 °C, leading to a sensitive and very viscous
white oil. Yield: 2.57 g (48%).1H NMR (C6D6): 7.52-6.84 (m, 20H
aromatics), 4.55 (m, 1H, NCH), 2.84 part A of ABX system for the
PCHaHb (dd, 1H, PCHa, 2J(P,Ha) ) 13.7 Hz, 2J(Hb,Ha) ) 7.4 Hz), 2.74
2
(O)Ph), 139.3-127.9 (m, 48C aromatics), 55.3 (d, 1C, NCH, J(P,C)
2
) 18.7 Hz), 54.9 (d, 1C, NC′H, J(P,C′) ) 18.7 Hz), 31.2 ppm (d, 1
C, PCH2, J(P,C) ) 14.7 Hz) and 30.5 ppm (d, 1C, PC′H2, J(P,C′) )
14.8 Hz). IR (Nujol): ν(CdO) ) 1664 (vs) and 1643 (vs) cm-1. Anal.
Calcd for C54H46N2O2P2: C, 79.40; H, 5.67; N, 3.43. Found: C, 79.41;
H, 5.73; N, 3.73.
Synthesis of [PdCl2(Ph2PCH2CH(Ph)NHPh-KP,KN)], 1. To a
mixture of [PdCl2(COD)] (0.600 g, 2.10 mmol) and L1 (0.804 g, 2.10
mmol) was added 10 mL of toluene. The resulting solution was refluxed
for 2 h. The mixture was then cooled to room temperature. A green-
yellow solid was separated by filtration and washed with pentane,
followed by extraction in CH2Cl2 and filtration through Celite (in order
to eliminate some traces of palladium metal). After evaporation of the
solvent, a yellow powder was obtained, which was washed with pentane
and dried in vacuo. Yellow single crystals of 1 were obtained by slow
diffusion from CH2Cl2/pentane. Yield: 0.680 g (58%). 1H NMR
(CDCl3): 7.74-6.99 (m, 20H aromatics), 8.10 (s, br, 1H, NH exchange
with D2O), 3.79 (m, 2H, NCH + PCHa), 2.48 (m, 1H, PCHb). 31P{1H}
NMR (CDCl3): 38.77 (s). 31P{1H} NMR (CD2Cl2): 40.88 (s). No 13C-
{1H} NMR spectra were recorded due to the low solubility of 1 in
CDCl3 or in CD2Cl2. Anal. Calcd for C26H24NPPdCl2: C, 55.89; H,
4.33; N, 2.51. Found: C, 55.59; H, 4.67; N, 2.81.
Synthesis of [PdCl2{Ph2PCH2CH(Ph)N(Ph)(Si(CH3)3)-KP,KN}],
2. To a mixture of [PdCl2(COD)] (0.119 g, 0.42 mmol) and L2 (0.208
g, 0.45 mmol) was added 10 mL of toluene. The orange solution was
refluxed for a few minutes and then stirred for 2 days at room
temperature. After filtration, the solvent was removed in vacuo, yielding
an orange powder, which was washed with pentane and dried in vacuo.
The product was purified by slow diffusion from CH2Cl2/pentane (ratio
1:3) at - 30 °C. Yield: 0.202 g (71%). 1H NMR (CDCl3): 7.48-6.57
2
part B of ABX system for the PCHaHb (dd, 1H, PCHb, J(P,Hb) )
13.7 Hz, 2J(Hb,Ha) ) 7.4 Hz), 0.17 (s, br, 9H, Si(CH3)3). 31P{1H} NMR
(CDCl3): -20.94 (s). 13C{1H} NMR (CDCl3): 144.6-124.2 (m, 24 C
2
aromatics), 58.7 (d, 1C, NCH, J(P,C) ) 17.6 Hz), 34.3 ppm (d, 1C,
PCH2, J(P,C) ) 13.9 Hz) and -1.1 (s, 3C, Si(CH3)3). Elemental analysis
of the pure ligand could not be performed due to its air sensitivity and
very viscous nature. It was used without further purification.
Synthesis of [Ph2CH3PCH2CH(Ph)NHPh](I), L3. To a solution of
L1 (0.165 g, 0.433 mmol) in 4 mL of toluene was added MeI (27 µL,
0.433 mmol). A white precipitate formed, and the mixture was stirred
for 60 h. The solid was isolated by filtration, washed 3 times with 4
mL of toluene and 3 times with 5 mL of pentane, and dried in vacuo.
Yield: 0.186 g (82%). 1H NMR (C6D6): 7.90-6.35 (m, 20H aromatics),
(20) Hartley, F. R.; Jones, S. R. J. Organomet. Chem. 1974, 66, 465-473.
(21) Ladipo, F. T.; Anderson, G. K. Organometallics 1994, 13, 303-306.

Synthesis of â-P,N Aminophosphines
Inorganic Chemistry, Vol. 40, No. 7, 2001 1599
(m, 20H aromatics), 4.77 (m, br, 1H, NCH), 3.22 (d, 1H, PCHa, 2J(P,Ha)
6. The complex [PdCl(η3-C3H5)]2 (0.097 g, 0.26 mmol) and the ligand
L1 (0.202 g, 0.53 mmol) were stirred in 10 mL of CH2Cl2 at room
temperature for 30 min. The solution was added to NaPF6 (0.223 g,
1.30 mmol). After stirring for 3 h, the mixture was filtered through
Celite. The filtrate was concentrated in vacuo to ca. 2 mL, and the
addition of 15 mL of pentane yielded a white powder. The solid was
2
) 11.6 Hz), 3.18 (d, 1H, PCHb, J(P,Hb) ) 12.5 Hz), - 0.07 (s, 9H,
Si(CH3)3). 31P{1H} NMR(CDCl3): 28.42 (s). 13C{1H} NMR (CDCl3):
143.9-124.9 (m, 24C aromatics), 58.4 (s, 1C, NCH), 33.0 (d, 1C, PCH2,
J(P,C) ) 27.5 Hz) and -1.0 (s, 3C, Si(CH3)3). Anal. Calcd for C29H32-
NPCl2SiPd: C, 55.21; H, 5.07; N, 2.21. Found: C, 54.92; H, 4.86; N,
2.47.
1
isolated by filtration and dried in vacuo. Yield: 0.315 g (89%). H
NMR (CDCl3, 298 K): 7.83-6.60 (m, 20H + 20H′ aromatics), 6.53
Synthesis of [PdCl(CH3)(Ph2PCH2CH(Ph)NHPh-KP,KN)], 3. To
a solution of [PdCl(CH3)(COD)] (0.094 g, 0.355 mmol) in 5 mL of
CH2Cl2 was added a solution of L1 (0.135 g, 0.355 mmol) in 10 mL of
CH2Cl2. The mixture was stirred for 4 h and then filtered through Celite.
The solution was concentrated to 2 mL, and then 15 mL of Et2O was
added with stirring, leading to a white powder, which was washed with
20 mL of Et2O. After filtration, the product was crystallized by slow
diffusion from CH2Cl2/pentane and obtained as pale yellow crystals.
Yield: 0.123 g (56%). 1H NMR (CDCl3): 8.02-6.94 (m, 20H
aromatics), 6.27 (d, 1H, NH, 3J(P,H) ) 11.5 Hz, exchange with D2O),
3.87 (m, 1H, NCH), 3.45 (m, 1H, PCHa), 2.66 (m, 1H, PCHb) and
0.75 (d, 3 H, CH3, 2J(P,H) ) 3.5 Hz). 31P{1H} NMR(CDCl3): δ 40.15
(s). 13C{1H} NMR (CDCl3): 145.9-124.0 (m, 24C aromatics), 66.2
3
(d, 1H, NH exchange with D2O, J(H,P) ) 11 Hz), 6.33 (d, 1H′, NH′
3
exchange with D2O, J(H′,P) ) 12 Hz), 5.85 (apparent tt, 1H′, CH2′-
(allyl), 3J(H2′,H1a′) ) 3J(H2′,H3a′) ) 14 Hz, 3J(H2′,H1s′) ) 3J(H2′,H3s′)
3
3
) 7 Hz), 5.61 (apparent tt, 1H, CH2(allyl), J(H2,H1a) ) J(H2,H3a) )
14 Hz, 3J(H2,H1s) ) 3J(H2,H3s) ) 7 Hz), 4.37 (d, 1H, CH1a(allyl),
3J(H1a,H2) ) 14 Hz), 4.35 (d, 1H′, CH1a′(allyl), 3J(H1a′,H2′) ) 14 Hz),
4.19 (m, 1H′, NCHc′), 4.09 (m, 1H, NCHc), 4.00 (d, 1H, CH3s(allyl),
3
3J(H3s,H2) ) 7 Hz), 3.74 (d, 1H, CH3s′(allyl), J(H3s′,H2′) ) 7 Hz),
3.66 (t, 1H, CH1s(allyl), 3J(H1s,H2) ) 3J(H1a,P) ) 7 Hz), 3.37 (dt, 1H,
2
2
3
PCHa, J(Ha,P) ) J(Ha,Hb) ) 15 Hz, J(Ha,Hc) ) 2.5 Hz), 3.18 (dt,
1H′, PCHa′, J(Ha′,P) ) J(Ha′,Hb′) ) 15 Hz, J(Ha′,Hc′) ) 2.5 Hz),
2
2
3
3.07-2.94 (m, 4 H, CH3a′ (allyl) + CH1s′ (allyl) + PCHb + PCHb′),
2.75 (d, 1H, CH3a(allyl), 3J(H3a,H2) ) 14 Hz). 31P{1H} NMR (CDCl3,
2
(d, 1C, NCH, J(P,C) ) 28.2 Hz), 39.2 (d, 1C, PCH2, J(P,C) ) 27.5
-
298 K): 31.64 (s) (both diastereoisomers) and -143.34 (hept, PF6
,
Hz) and -4.2 (s, 1C, CH3). Anal. Calcd for C27H27NPPdCl.CH2Cl2:
C, 53.96; H, 4.69; N, 2.25. Found: C, 54.38; H, 4.59; N, 2.59.
Synthesis of [PdCl(η3-C3H5)(Ph2PCH2CH(Ph)NHPh-KP)], 4. To
a solution of [Pd(η3-C3H5)(µ-Cl)]2 (0.150 g, 0.821 mmol) in 5 mL of
CH2Cl2 was slowly added a solution of L1 (0.313 g, 0.821 mmol) in
10 mL of CH2Cl2. The mixture was stirred for 4 h. Yellow crystals of
4 suitable for an X-ray structure analysis were obtained by slow
diffusion of pentane into a CH2Cl2 solution. Yield: 0.329 g (71%). 1H
NMR (CDCl3, 298 K): 7.38-6.37 (m, 20H aromatics), 4.52 (m, 1H,
NCH), 4.00 (s, br, 1H, NH exchange with D2O), 3.50 (m, 1H, PCHa)
and 2.50 (m, 1H, PCHb). 31P{1H} NMR (CDCl3, 298 K): 16.65 (s).
13C{1H} NMR (CDCl3, 298 K): 146.8-113.2 (m, 24C aromatics), 53.9
(s, 1C, NCH), 35.8 (d, 1C, PCH2, J(P,C) ) 22.1 Hz). 1H NMR (CDCl3,
233 K): 7.83-6.58 (m, 20H + 20H′ aromatics), 5.55 (m, 1H, CH2-
(allyl)), 5.50 (m, 1H, CH2′(allyl)), 4.85 (s, br, 1H, NCH), 4.77 (s, br,
1H, NCH′), 4.11 (s, b, 2H, NH + NH′), 3.66 (m, 8H, CH1a, CH3s,
CH1a′, CH3s′ of allyl fragment plus PCH2 and PCH2′) and 2.59 (m, 8H,
CH1s, CH3a and CH1s′, CH3a′ of allyl fragment). 31P{1H} NMR (CDCl3,
233 K): 17.12 (s) and 16.23 (s). 13C{1H} NMR (CDCl3, 233 K):
146.4-126.3 (m, 24C + 24C′ aromatics), 117.8 (d, 1C, C2(allyl),
3J(P,C) ) 17 Hz), 116.6 (d, 1C′, C2′(allyl), 3J(P,C′) ) 17 Hz), 80.5 (d,
J(P,F) ) 716 Hz). 31P{1H} NMR (CD3CN, 298 K): 31.24 (s) (both
diastereoisomers) and -143.24 (hept, PF6-, J(P,F) ) 708 Hz). 13C-
{1H} NMR (CDCl3, 298 K): 148.4-121.3 (m, 24C + 24C′ aromatics),
123.0 (s, 1C, C2(allyl)), 120.6 (s, 1C′, C2′(allyl)), 87.1 (d, 1C, C1(allyl),
2J(P,C) ) 26.9 Hz), 84.6 (d, 1C′, C1′(allyl), 2J(P,C′) ) 28.3 Hz), 68.8
(s, 1C, NCH), 68.5 (s, 1C′, NC′H), 52.1 (s, 1C, C3(allyl)), 51.4 (s, 1C′,
C3′(allyl)), 37.9 (d, 1C, PCH2, J(P,C) ) 22.6 Hz), 37.7 (d, 1C′, PC′H2,
J(P,C) ) 21.4 Hz). 31P{1H} NMR (CDCl3, 233 K): 31.70 (s), 31.63
(s) and 143.30 (hept, PF6-, J(P,F) ) 711 Hz). Anal. Calcd for C29H29F6-
NP2Pd: C, 51.69; H, 4.34; N, 2.08. Found: C, 51.70; H, 4.56; N, 2.29.
31P{1H} NMR Experiments of the Phosphine Exchange Leading
to 7a-c. (a) With 1 equiv of L1. To a mixture of 6 (12 mg, 0.018
mmol) and L1 (7 mg, 0.018 mmol) was added 5 mL of CH2Cl2. The
solution was stirred for 15 min, and the solvent was removed in vacuo.
31P{1H} NMR (CDCl3, 298 K): 24.90 (s) and -143.34 (hept, PF6
J(P,F) ) 716 Hz) for 7a.
,
-
(b) With 1 equiv of PMe3. To a solution of 6 (17 mg, 0.025 mmol)
in THF (4 mL) was added PMe3 (25 µL, 0.025 mmol, 1 M in THF).
The solution was stirred for 15 min, and the solvent was removed in
vacuo. The variable-temperature experiments were carried out in CD3-
CN solution. 31P{1H} NMR (CDCl3, 298 K): 24.90 (s) for 7a, -18.49
2
2
1C, C1(allyl), J(P,C) ) 31.4 Hz), 80.3 (d, 1C′, C1′(allyl), J(P,C′) )
31.6 Hz), 59.4 (s, 1C, NCH), 57.3 (s, 1C′, NC′H), 54.0 (s, 1C, C3-
(allyl)), 53.2 (s, 1C, C3(allyl)), 34.9 (d, 1C, PCH2, J(P,C) ) 23.9 Hz),
34.6 ppm (d, 1C′, PC′H2, J(P,C′) ) 24.4 Hz). IR (Nujol): ν(NH) )
3300 cm-1 (w). Anal. Calcd for C29H29NPPdCl: C, 61.71; H, 5.18; N,
2.48. Found: C, 61.60; H, 5.30; N, 2.85.
2
2
(s) for 7b, 13.61 (d, J(P,P) ) 40 Hz) and -18.46 (d, J(P,P) ) 40
Hz) for 7c, and -143.34 (hept, PF6-, J(P,F) ) 716 Hz). 31P{1H} NMR
(CD3CN, 298 K): 24.90 (s) for 7a, -18.49 (s) for 7b, 14.72 (d, 2J(P,P)
) 42 Hz) and -17.20 (d, 2J(P,P) ) 42 Hz) for 7c, and -143.23 (hept,
PF6-, J(P,F) ) 705 Hz).
Synthesis of [Pd(CH3)(Ph2PCH2CH(Ph)NHPh-KP,KN)(NCMe)]-
(BF4), 5. The solid [PdCl(CH3)(COD)] (0.070 g, 0.26 mmol) and the
ligand L1 (0.100 g, 0.26 mmol) were stirred overnight in 10 mL of
CH2Cl2 at room temperature. The solvent was removed, leaving a white
solid, which was washed twice with 20 mL of ether and dried in vacuo.
The crude product was dissolved in 5 mL of CH2Cl2 and was then
added to AgBF4 (0.048 g, 0.26 mmol) in the presence ca. 0.5 mL of
acetonitrile. After stirring for 30 min, the mixture was filtered through
Celite. The filtrate was concentrated to ca. 2 mL. Addition of 20 mL
of ether yielded a white precipitate, which was isolated by filtration
(c) With 2 equiv of PMe3. To the above CDCl3 solution containing
7a-c was added a second equivalent of PMe3 (25 µL, 0.025 mmol, 1
M in THF). The mixture was then stirred for 10 min. 31P{1H} NMR
(CDCl3, 298 K): -18.49 (s, br) for 7b, -21.79 (s) for free L1 and
-143.34 (hept, PF6-, J(P,F) ) 716 Hz) for 7b.
Synthesis of [PdCl(η3-C3H5)(Ph2PCH2CH(Ph)N(Ph)C(O)Ph-KP)],
8. To a mixture of [PdCl(η3-C3H5)]2 (0.074 g, 0.200 mmol) in 5 mL of
CH2Cl2 was slowly added a solution of L4 (0.196 g, 0.400 mmol) in
10 mL of CH2Cl2. The mixture was stirred for 3 h. The solvent was
removed in vacuo. The addition of 10 mL of Et2O afforded a white
powder, which was isolated by filtration and washed with pentane and
dried under vacuum. Yield: 0.150 g (56%). 1H NMR (CDCl3, 298 K):
7.46-7.08 (m, 25H + 25H′ aromatics), 6.41 (m, 2H, NCH + NCH′),
1
and dried in vacuo. Yield: 0.080 g (49%). H NMR (CDCl3): 8.02-
6.97 (m, 20H aromatics), 6.39 (d, 1H, NH, exchange with D2O, 3J(P,H)
3
3
) 11.7 Hz), 3.94 (ddd, 1H, NCHc, J(Hc,P) ) 25 Hz, J(Hc,Ha) ) 7
Hz, 3J(Hc,Hb) ) 3 Hz), 3.40 (dt, 1H, PCHa, 3J(Ha,Hc) ) 7 Hz, 2J(P,Ha)
) 2J(Ha,Hb) ) 14 Hz), 2.70 (dt, 1H, PCHb, 3J(Hb,Hc) ) 3 Hz, 2J(P,Hb)
3
3
5.32 (apparent tt, 1H, CH2(allyl), J(H2,H1a) ) J(H2,H3a) ) 12 Hz,
3J(H2,H1s) ) J(H2,H3s) ) 6 Hz), 5.11 (apparent tt, 1H′, CH2′(allyl),
3
) J(Hb,Ha) ) 14 Hz), 1.93 (s, 3H, CH3CN) and 0.48 (d, 3H, CH3,
2
3J(H2′,H1a′) ) J(H2′,H3a′) ) 12 Hz, J(H2′,H1s′) ) J(H2′,H3s′) ) 6
3
3
3
3J(P,H) ) 1.8 Hz). 31P{1H} NMR (CDCl3): δ 42.7 (s). 13C{1H} NMR
(CDCl3): 122.3-145.3 (m, 24C aromatics), 118.5 (s, 1C, NCCH3),
Hz), 4.56 (t, 1H, CH1s(allyl), J(H1s,H2) ) J(H1a,P) ) 6 Hz), 3.70-
3.42 (m, 6H, PCH2 + PCH2′ + CH1a(allyl) + CH1a′(allyl)), 3.28-3.20
(m, 3H, CH3s(allyl) + CH3s′(allyl)), 2.67 (d, 1H, CH3(allyl), 3J(H3a,H2)
3
3
2
65.4 (d, 1C, NCH, J(P,C) ) 5.5 Hz), 39.0 (d, 1C, PCH2, J(P,C) )
) 12 Hz), 2.18 (d, 1H, CH3a′(allyl), J(H3a′,H2) ) 12 Hz). 31P{1H}
3
28.9 Hz), 2.2 (s, NCCH3), -4.6 (s, Pd-CH3). Anal. Calcd for C29H30-
BF4N2PPd: C, 55.20; H, 4.79; N, 4.44. Found: C, 54.91; H, 4.91; N,
4.68.
Synthesis of [Pd(η3-allyl)(Ph2PCH2CH(Ph)NHPh-KP,KN)](PF6),
NMR (CDCl3, 298 K): 15.69 (s) and 14.73 (s). 13C{1H} NMR (CDCl3,
298 K): 171.4 (s, 1C, NC(O)Ph), 171.3 (s, 1C, NC′(O)Ph), 140.7-
127.8 (m, 30C + 30C′ aromatics), 118.1 (s, 1C, C2(allyl)), 117.6 (s,

1600 Inorganic Chemistry, Vol. 40, No. 7, 2001
Andrieu et al.
Scheme 1
2
1C′, C2′(allyl)), 79.7 (d, 1C, C1 (allyl), J(P,C) ) 32.7 Hz), 79.4 (d,
PCH3 was detected at -26.4 ppm in the presence of a new peak
at -22.0 ppm corresponding to L1. The ligand was purified by
crystallization in cold methanol and did not decompose by P-C
bond cleavage in contrast to analogous R-P,N ligands.14,15 The
1H, 13C, 31P chemical shifts found for the ligand L1 were
consistent with the â-P,N (Ph2PCH2CH(Ph)NHPh) ligand which
has been previously obtained by a tedious multistep reaction.13
An attempt to use the same procedure with (Ph)2CdNPh led
unfortunately to a mixture of unidentified phosphorus-containing
products.
1C′, C1′(allyl), J(P,C′) ) 32.7 Hz), 59.9 (s, 1C, C3(allyl)), 59.8 (s,
2
1C′, C3′(allyl)), 58.7 (s, NCH), 57.9 (s, 1C′, NC′H), 31.2 (d, 1C, PCH2,
J(P,C) ) 21.4 Hz), 30.8 (d, 1C′, PC′H2, J(P,C′) ) 20.1 Hz). IR (CH2-
Cl2): ν(CdO) ) 1641 cm-1 (vs). Anal. Calcd for C36H33ClNOPPd:
C, 64.68; H, 4.98; N, 2.10. Found: C, 64.43; H, 5.09; N, 2.55.
Crystal Structure Analysis of 1 and 4. Pale yellow crystals of 1
and 4 suitable for X-ray analysis were obtained by layering n-pentane
onto a saturated methylene chloride solution of 1 or 4 at room
temperature. Data for both compounds were collected on an Enraf-
Nonius diffractometer at 293 K using Mo KR radiation. A 6% decay
found for 1 was linearly corrected.22
In order to explore whether the â-P,N ligand could open the
access to related N,N-disubstituted ligands, we have investigated
the reactivity of the deprotonated form I. The reaction with CH3I
afforded Ph2PCH3 instead of the expected ligand, see Scheme
1. In the same manner, the addition of H2O led to diphenylphos-
phine, although only as a minor byproduct. A reasonable
explanation for the formation of these products is that the anionic
nitrogen atom could exhibit a lower reactivity (or nucleophi-
licity) than expected due to the negative charge being delocalized
on the N-phenyl fragment. Consequently, the phosphorus atom
competes effectively as a nucleophile toward the electrophic
reagents H+ or CH3+. This assumption is in agreement with
the easy phosphorus alkylation of L1 with 1 equiv of CH3I (see
experimental part), which affords the stable phosphonium salt
L3 [Ph2MeP+CH2CH(Ph)NH(Ph)](I-). The expected byproduct
of the methylation of I is an aziridine which was not further
characterized. Further confirmation of this course of action
comes from the following observations. The ligand L3 is stable,
but the addition of a strong base such as t-BuOK led to the
formation of Ph2PCH3, which was detected by 31P{1H} NMR.
An analogous phosphonium ligand containing an oxygen instead
of a nitrogen function, namely, [Ph2MeP+CH2C(Ph)2OH](I-),
led to a similar P-C bond cleavage upon deprotonation with
formation of Ph2MePdO and (Ph)2CdCH2.16
Both structures were solved via a Patterson search program23 and
refined with full-matrix least-squares methods23,24 based on F2. All non-
hydrogen atoms were refined with anisotropic thermal parameters. For
compound 1, except for the disordered solvate molecule, the hydrogen
atoms of the complex were included in their calculated positions and
refined with a riding model. One chlorine atom of the methylene
chloride solvate molecule is disordered and occupies two positions with
occupation factors imposed as x and (1 - x) with x refined to 0.56. In
4, except for the allyl ligand hydrogen atoms and those bonded to the
nitrogen atom which were found by a Fourier difference synthesis, the
hydrogen atoms of the complex were included in their calculated
positions and refined with a riding model. After refinement of 4, the
Flack absolute structure parameter25 converged to 0.00(6) (1.04(6) for
the inverted structure). Experimental details and final agreement indices
are reported in Table 3.
Results and Discussion
Synthesis of the â-Aminophosphine L1 and Some Related
Ligands. The Ph2PCH2-Li+ salt was prepared according to
Peterson’s procedure.16 As the deprotonation reaction of the Ph2-
PCH3 precursor does not proceed beyond 85% (due to a
secondary reaction as documented in the literature17,18), a
substoichiometric amount of imine was used to afford the
desired ligand L1 as shown in Scheme 1. After hydrolysis, the
composition of the crude product was analyzed by NMR
spectrocopy. In the 31P{1H} NMR spectrum, the excess of Ph2-
In regards to these observations, we wished to find an
alternative synthetic method to alkylate the nitrogen anion. This
method is based on the use of an electrophilic reagent which is
more reactive toward the attack by harder bases relative to softer
ones, such as TMSCl (chlorotrimethylsilane) or an acyl chloride.
In the latter case, the acyl group in the expected product could
lead to the corresponding alkyl fragment by a further reduction
reaction.11 Both related ligands L2 and L4 (see Scheme 1) have
(22) Harms, K.; Wocadlo, S. XCAD4. Program for Processing CAD4
Diffractometer Data; University of Marburg: Marburg, Germany,
1995.
(23) Sheldrick, G. M. SHELXS and SHELXL97; University of Go¨ttingen:
Go¨ttingen, Germany, 1997.
(24) North, A. C. T.; Phillips, D. C.; Mathews, F. S. Acta Crystallogr.,
Sect. A 1968, A24, 351-359.
(25) Flack, H. D. Acta Crystallogr. 1983, A39, 876-881.

Synthesis of â-P,N Aminophosphines
Inorganic Chemistry, Vol. 40, No. 7, 2001 1601
2
3
Table 1. 13C{1H} NMR Data for the Ligands L1-L5 (Chemical Shifts in ppm; JPC or JPC in Hz in Parentheses)
L5
dia1, dia2
L1
L2
L3
L4
PC
NC
39.5 (16)
56.6 (15)
34.3 (14)
58.7 (18)
31.6 (48)
54.1 (4)
32.2 (14)
57.4 (16)
30.8 (15), 31.2 (15)
54.9 (19), 55.3 (19)
P-Ph
Cipso
138.1 (12)
138.7 (13)
133.3 (19)
138.6 (14)
139.4 (15)
133.0 (20)
133.2 (20)
128.0
128.2
128.5
118.3 (15)
121.6 (14)
132.5 (10)
132.8 (9)
130.7 (12)
131.1 (11)
135.1
138.6 (12)
138.9 (12)
133.1 (19)
133.9 (20)
128.7
128.9
129.5
138.3 (15), 138.4 (15)
138.4 (16), 138.5 (16)
132.9 (19), 133.0 (19)
133.7 (20), 133.8 (20)
128.8, 128.9
128.9, 129.0
129.0, 129.1
Cortho
Cmeta
Cpara
129.1
129.3
129.0
129.1
128.7
135.7
129.6
129.2, 129.2
C-Ph
Cipso
Cortho
Cmeta
Cpara
144.9 (5)
126.5
129.2
143.4 (5)
128.7
131.2
141.5 (14)
127.2
129.4
140.7 (6)
128.8
131.2
139.1 (4), 139.3 (4)
128.7, 128.8
131.7, 131.8
127.6
127.0
128.4
127.9
127.9, 128.0
N-Ph
Cipso
Cortho
Cmeta
Cpara
147.4
113.9
129.4
117.8
144.6
128.4
128.8
124.2
146.1
114.6
129.4
118.9
137.5
128.1
129.3
128.3
171.6 CdO
140.6 COPhipso
129.0 COPhortho
129.1 COPhmeta
129.1 COPhpara
136.2, 136.5
128.4, 128.5
128.9, 128.9
128.6, 128.8
164.4, 164.5 CdO
other
1.1 SiMe3
11.3 (54) Me
signal
assign-
ments
been successfully obtained in good yields. By extension of this
procedure, ligand L5 was prepared by using oxalyl chloride (see
Scheme 1). According to Nagel’s reduction procedure, we have
attempted to convert the amide function in the ligand L4 to a
tertiary amine group. Unfortunately, even after 7 days of reflux
in THF in the presence of an excess of LiAlH4 and after
hydrolysis, the reaction did not lead to the expected ligand but
rather to L1. This observation shows that the reduction stops
after the formation of the iminium salt, which then hydrolyzes
to L1.26 We might expect that the replacement of the N-phenyl
substituent with an unconjugated fragment such as an alkyl or
benzyl group will eventually increase the nucleophilic character
of the amine function. The preparation of new imines and their
use as starting materials for the synthesis of other â-P,N are
currently in progress. The 13C NMR data of ligands L1-5 are
given in Table 1.
The reaction between PdCl2(COD) (COD ) 1,5-cycloocta-
diene) and L1 or L2 in a 1:1 ratio leads to the formation of the
complexes 1 and 2, see eq 1. The presence of the NH or NSi-
(CH3)3 protons in the 1H NMR confirms that HCl or ClSi(CH3)3
elimination has not occurred.
However, a structural ambiguity persists. The NMR properties
are consistent with either a mononuclear structure of type II
(with a P,N chelate)18,27 or a chloride-bridged dinuclear one of
type III (well-known with other bifunctional ligands such as
ketophosphines).29,30
Coordination Properties of L1 and L2 toward Palladium-
(II) Complexes. It is well-known that N,N-disubstitued ami-
nophosphines act as mono- or bidentate ligands in palladium(II)
and platinum(II) complexes, with a hemilabile character.27
Moreover, Sadler and Habtemariam have shown by 31P{1H}
and 195Pt NMR spectroscopy in aqueous solution that the
equilibrium between the dangling and chelating forms in bis-
(â-P,N) (with â-P,N ) Ph2P(CH2)2NMe2) platinum(II) com-
plexes is pH dependent and can be controlled by the N-sub-
stituents. Indeed, when the tertiary amine in the Ph2P(CH2)2NMe2
ligand is replaced by a primary amine, the hemilabile character
is lost.28 In regard to these coordination properties, our ligand
contains a secondary amine substituted by a phenyl group, which
is not a particularly strong electron-donating group. Thus, we
wished to examine the consequences of the weak donor character
of the amine function in the κP versus κP,κN coordination mode
of L1 and L2.
The 31P{1H} NMR spectrum shows a signal at δ 38.8 for 1
and 28.4 ppm for 2 which may be consistent with both
coordination modes. The NH proton resonance for complex 1
is found at 8.10 ppm, in constrast to 4.19 ppm for the free ligand,
but this does not unambiguously prove structure II. Conse-
quently, a structure analysis by X-ray diffraction was carried
out for complex 1 (see below). This shows that, indeed, the
mononuclear structure-type II is adopted. Compound 2 has
spectroscopic properties similar to those of 1, and a mononuclear
formulation is also assigned to this compound.
(26) Kuehne, M. E.; Shannon, P. J. J. Org. Chem. 1977, 42, 2082-2087.
(27) Dekker, G. P. C. M.; Buijs, A.; Elsevier, C. J.; Vrieze, K.; van
Leeuwen, P. W. N. M.; Smeets, W. J. J.; Spek, A. L.; Wang, Y. F.;
Stam, C. H. Organometallics 1992, 11, 1937-1948.
(28) Habtemariam, A.; Sadler, P. J. Chem. Commun. (Cambridge) 1996,
1785-1786.
(29) Andrieu, J.; Braunstein, P.; Naud, F. J. Chem. Soc., Dalton Trans.
1996, 2903-2909.
(30) Andrieu, J.; Braunstein, P.; Naud, F.; Adams, R. D.; Layland, R. Bull.
Soc. Chim. Fr. 1996, 133, 669-672.

1602 Inorganic Chemistry, Vol. 40, No. 7, 2001
Andrieu et al.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
Compounds 1 and 4
compound 1
compound 4
Pd-N
2.106(4)
Pd-C(27)
2.176(7)
2.135(7)
2.135(7)
2.280(2)
2.371(2)
1.29(2)
1.33(1)
3.304(4)
0.75
Pd-P
2.1969(15) Pd-C(28)
2.3776(14) Pd-C(29)
2.2846(16) Pd-P
0.874
2.605
Pd-Cl(1)
Pd-Cl(2)
N-H
Pd-Cl
(N)H‚‚‚Cl
C(27)-C(28)
C(28)-C(29)
N‚‚‚Cl
N-H
(N)H‚‚‚Cl
2.55
N-Pd-P
85.64(11)
91.94(11)
174.93(12) C(28)-Pd-Cl
172.54(6)
90.36(6)
C(27)-Pd-Cl
C(27)-Pd-P
99.7(4)
N-Pd-Cl(1)
N-Pd-Cl(2)
P-Pd-Cl(1)
P-Pd-Cl(2)
163.3(18)
131.6(9)
128.6(7)
165.9(22)
97.3(4)
C(28)-Pd-P
C(29)-Pd-Cl
C(29)-Pd-P
P-Pd-Cl
C(27)-C(28)-C(29) 129(2)
N-H‚‚‚Cl 175
Cl(1)-Pd-Cl(2) 92.41(6)
N-H‚‚‚Cl 144
Figure 1. An ORTEP view of complex 1 with thermal ellipsoids drawn
at the 30% probability level. Hydrogen atoms of phenyl groups are
omitted for clarity.
96.7(1)
interaction, whereas one is observed in the related allyl
palladium chloride complex (see below). However, we found
that the distance between the N atom of one complex and the
Cl from another one (3.33 Å) (N-H ) 0.874 Å; H‚‚‚Cl ) 2.605
Å; N-H‚‚‚Cl ) 144°) is significantly smaller than the sum of
the N-H bond length and the van der Waals radii of the H and
Cl atoms.32 Consequently, compound 1 is in fact an H-bonded
dimer in the solid state with two N-H‚‚‚Cl intermolecular
bridges in the Pd2N2H2Cl2 eight-membered ring. However, it
is possible that this dimeric structure is not maintained in
solution, especially in solvents capable of establishing H-
bonding interactions.
Table 3. Crystallographic Data for Compounds 1 and 4
compound 1
compound 4
chemical formula
fw
space group
a, Å
b, Å
C26H24Cl2NPPd‚CH2Cl2
643.66
P21/n
10.689(2)
21.345(3)
12.282(2)
90.294(12)
2802.2(8)
4
C29H29ClNPPd
564.35
Cc
10.912(1)
17.194(2)
14.169(2)
100.651(9)
2612.6(5)
4
c, Å
â, deg
V, Å3
Z
T, K
D
293(2)
1.526
293(2)
1.435
calcd, g/cm3
The centrosymmetric unit cell of 1 contains the enantiomeric
pair of one diastereoisomer (see ORTEP view in Figure 1). It
is interesting to examine the arrangement of the phenyl
substituents on the carbon and on the nitrogen atoms. In fact,
as the L1 ligand used is a racemate and as coordination generates
a second chiral center at the N atom in addition to that already
present at the C atom, four stereoisomers should be expected.
However, only two are observed in this structure, which are
the (S,R, eq, eq) and (R,S, eq, eq), see below.
λ, Å
0.71073
1.117
0.039
0.099
1.063
0.71073
0.89
0.024
0.060
1.073
µ, mm-1
R(Fo)a
Rw(Fo )b
2
GOFc
a R1 ) ∑(|Fo| - |Fc|)/∑|Fo|. bwR2 ) [∑w(Fo2 - Fc2)2/∑[w(Fo )2]1/2
2
where w ) 1/[σ2(Fo + (0.0523P)2 + 2.70P] for 1 and w ) 1/[σ2(Fo
2
2
+ (0.037P)2 + 0.58P] for 4 where P ) (Max(Fo ,0) + 2Fc2)/3. GOF
2
c
) [∑w(Fo - Fc2)2/(N - Nv)]1/2
.
2
o
X-ray Structure Analysis of Complex 1. The structure of
complex 1 shows that the ligand L1 adopts a κP,κN coordination
mode in a square planar coordination geometry for the palladium
center. The selected bond lengths and bond angles (see Table
2) of complex 1 compare with those of the only other examples
of PdCl2 complexes containing similar saturated aminophosphine
ligands, namely, PdCl2[{Ph2PCH2CH((CH2)nSMe)NMe2}-κP,κN]
(with n ) 2 or 3).31 The Pd-P, Pd-N, Pd-Cl(1), and Pd-
Cl(2) distances are very close to those found in the above-
mentioned complexes. The Pd-Cl bond length trans to the P
atom [2.3776(14) Å] is longer than that trans to the N atom
[2.2846(16) Å] owing to the stronger trans influence of a tertiary
phosphine with respect to an amine. The Cl(1)-Pd-Cl(2),
N-Pd-Cl(2), Cl(1)-Pd-N, and P-Pd-Cl(2) angles reveal
only minor distortions from the ideal value. The P-Pd-N angle
of 85.64(11)° is normal for this type of five-membered-ring
complex.31
The hydrogen substituents on adjacent carbon and nitrogen
atoms in the five-membered ring are almost completely stag-
gered (Hax-Hax) as it has also been observed, in the solid state,
for other complexes containing either a diamine or a diphosphine
ligand.33,34 This arrangement tends to minimize the energy of
the cyclic structure by analogy with cyclopentane or cyclohex-
ane.33 However, a (Heq-Heq) arrangement has been observed
in solution by NMR coupling constant analysis for a similar
palladium-coordinated â-P,N ligand (â-P,N ) {(p-CH3C6H4)2-
PCH2CH(i-Pr)NHCH2(p-C6H4OCH3)}) and confirmed by cal-
culations. The energy difference between the two possible
It is interesting to observe that there are no N-H‚‚‚Cl
intramolecular interactions. The H-N-Pd-Cl dihedral angle
of 87.5° in 1 certainly does not favor the establishment of this
(32) Bondi, A. J. Phys. Chem. 1964, 68, 441-451.
(33) Corey, E. J.; Bailar, J. C. J. Am. Chem. Soc. 1959, 81, 2620-2628.
(34) Fryzuk, M. D.; Bosnich, B. J. Am. Chem. Soc. 1977, 99, 6262-6267.
(31) Cross, G.; Vriesema, B. K.; Boven, G.; Kellog, R. M.; van Bolhuis,
F. J. Organomet. Chem. 1989, 370, 357-381.

Synthesis of â-P,N Aminophosphines
Inorganic Chemistry, Vol. 40, No. 7, 2001 1603
Scheme 2
conformations was found to be about 1 kcal/mol.18 We wished
to examine whether the observed solid state conformation of 1
is retained in solution. On the basis of the H-C-C-H dihedral
angles of the P-CHaHb-CHc(Ph)N fragment experimentally
found to be 60° and 180° in solid state, the corresponding
Figure 2. 31P{1H} NMR spectra at variable temperature for complex
4 in CDCl3.
3
palladium structure with a â-aminophosphine in the κP coor-
dination mode. It is interesting to note that the free secondary
amine function does not transfer the proton to the allyl ligand
to lead to propene (a key step suggested for nickel-based
butadiene dimerization catalysts36,37) nor to reductive elimination
to lead to Pd(0) and an allyl phosphinoammonium salt (a key
step suggested for palladium-based allyl amination catalysts37-40).
The reaction of the neutral complexes 3 and 4 with chloride-
abstracting reagents leads to the corresponding stable cationic
complexes 5 and 6, see Scheme 2. Like for complex 4, the allyl
coupling constants J(H,H) are predicted to be ca. 4 Hz (for
the (Haeq-Hcax) conformation) and 15 Hz (for the (Hbax-Hc
)
ax
conformation).35 However, the solution structure for 1 could
not be elucidated by 1H NMR spectroscopy owing to an overlap
of multiplet signals related to the PCHa-CHN protons.
Coordination Properties of L1 in Neutral and Cationic
Methyl and Allyl Palladium Complexes. The reaction between
the ligand L1 and [PdCl(CH3)(COD)] leads to the formation of
3, see Scheme 2. In this complex, L1 behaves as a chelating
ligand, κP,κN, on the basis of its chemical shift in the 31P{1H}
NMR spectrum at 40.1 ppm which is close to the value observed
for complex 1. This P,N coordination mode is also in agreement
with the NH proton chemical shift (doublet at 6.27 ppm in 3
1
protons of 6 are invisible in the room temperature H NMR
spectrum due to the dynamic η3/η1 allyl rearrangement. At lower
temperatures, the decoalescence allows the detection of the allyl
protons for two distinct diastereoisomers. The 31P{1H} reso-
nances are found at 31.70 and 31.63 ppm at lower temperature,
and the 31P{1H} coalescence is found at 233 K for 6 versus
285 K for 4.
3
with J(P,H) ) 11.5 Hz, versus broad singlet at 4.40 ppm in
1
L1). The CH3 group is found at 0.75 ppm in the H NMR
spectrum with a typical small cis phosphorus coupling constant
3
of J(P,H) ) 3.5 Hz.27 This configuration is certainly due to
X-ray Structure Analysis of Complex 4. The geometry of
4 is shown in Figure 3, and selected bond distances and angles
are collected in Table 2. The unit cell contains the enantiomeric
pair of one diastereoisomer. The structure confirms the typical
geometry of an η3-allyl group and the typical stereochemistry
of d8 palladium(II). The allyl group is oriented with the central
C atom pointing away from the amine function of the κP-
coordinated L1 ligand. The different Pd-C bond lengths are in
agreement with the larger trans influence of the phosphine ligand
with respect to the chloro ligand, see Table 2.41-43
the larger trans influence of the tertiary phosphine relative to
the amine, as is well-known for other methyl palladium chloride
complexes containing neutral P,N ligands.27 When a palladium
monochloride complex containing an allyl instead of a methyl
group is used in the reaction with ligand L1, a new complex 4
is formed, see Scheme 2. Its 1H NMR spectrum does not show
the presence of the allyl fragment at room temperature, and a
single peak is observed at 16.6 ppm in the 31P{1H} NMR
spectrum. This value is very different from those found for
complexes 1-3 and seems to indicate a κP coordination mode.
At lower temperatures, the 1H and 31P{1H} NMR spectra show
all the allyl protons and the presence of two diastereiosomers
in an approximate 1:1 ratio. The coalescence temperature for
the 31P signals is found at ca. 280 K, see Figure 2.
(36) Denis, P.; Jean, A.; Crizy, J. F.; Mortreux, A.; Petit, F. J. Am. Chem.
Soc. 1990, 112, 1292-1294.
(37) Monflier, E.; Tilloy, S.; Me´liet, C.; Mortreux, A.; Fourmentin, S.;
Landy, D.; Surpateanu, G. New J. Chem. 1999, 23, 469-472.
(38) Crociani, B.; Antonaroli, S.; Bandoli, G.; Canovese, L.; Visentin, F.;
Uguagliati, P. Organometallics 1999, 18, 1137-1147.
(39) Canovese, L.; Visentin, F.; Chessa, G.; Niero, A.; Uguagliati, P. Inorg.
Chim. Acta 1999, 293, 44-52.
In order to fully characterize 4, we have carried out an X-ray
structure analysis (see below) which confirms a neutral allyl
(35) Haasnoot, C. A. G.; De Leeuw, F. A. A. M.; Altona, C. Tetrahedron
1980, 36, 2783- 2792.
(40) Canovese, L.; Visentin, F.; Uguagliati, P.; Chessa, G.; Pesce, A. J.
Organomet. Chem. 1998, 566, 61-71.

1604 Inorganic Chemistry, Vol. 40, No. 7, 2001
Andrieu et al.
Scheme 3
peak at 24.9 ppm. The latter is attributed to complex 7a, which
has not been further characterized, see Scheme 3. In this case
the phosphorus atom of ligand L1 is sufficiently strong to open
the P,N chelate. By analogy with this experiment, when 1 equiv
of the PMe3 is added to complex 6, the 31P{1H} NMR peaks of
6 and free PMe3 disappear and are replaced by two new singlets
and by one AB pattern. These are consistent with the presence
of the three complexes 7a-c. Moreover, when a second
equivalent of PMe3 was added to this solution, the 31P{1H}
NMR peaks of 7a and 7c disappeared whereas a singlet
corresponding to free L1 ligand appeared and the intensity of
the signal of 7b increased. This P-coordination of the additional
ligand could be preceded by the formation of a complex
containing a free coordination site generated by the known η3/
η1 allyl rearrangement. This view would seem consistent with
the observation of only one signal in the 31P{1H} NMR spectra
of complexes 6, 7a-c, because of the very rapid allyl inter-
conversion at room temperature. When the mixture of complexes
7a-c is heated in CD3CN at different temperatures, the
intensities of all signals decrease at the same time until they
disappear at 323 K, see Figure 4, indicating a rapid equilibration
for the mixture of the three complexes (see Scheme 3). This
equilibrium is similar to one reported for methyl palladium
chloride complexes containing mixed functional P,O ligands.29,30
Figure 3. An ORTEP view of complex 4 with thermal ellipsoids drawn
at the 30% probability level. Hydrogen atoms of phenyl groups are
omitted for clarity.
In contrast to 1, compound 4 exhibits an intramolecular
H-bonding interaction, N-H‚‚‚Cl. The N‚‚‚Cl distance of 3.303
Å (N-H ) 0.75 Å; H‚‚‚Cl ) 2.55 Å) is significantly shorter
than the sum of the N-H bond length and the van der Waals
radii of H and Cl atoms, 3.80 Å,32 and the N-H‚‚‚Cl
arrangement is close to linear (175°). Other examples of this
type of interaction in seven-membered rings have been recently
reported for a copper(I) chloride complex containing the ligand
[NH{Si(Me)2CH2PPh2}2]-κP,κP44 and for [PtBr(C6H4CH(Me)-
NMe2-(R)-2-C,N)(C6H4CH(Me)NHMe2-(R)-2-C)].45 This in-
tramolecular H-bonding interaction is also confirmed by infrared
spectroscopy. The ν(N-H) for 4 is shifted at 3300 cm-1 whereas
it was found at 3390 cm-1 for the free ligand L1.
It is interesting to mention the recent van Leeuwen’s work
on the allylic alkylation catalyzed by [(C4H7)Pd(P,N)]+ or
[(C9H9)Pd(P,N)]+ (P,N ) aminophosphinite), in which he
reports that the presence of an additional equivalent of P,N
ligand decreases the regioselectivity of the branched product
in the catalytic allylic alkylation from 22% to 8%. To explain
this observation, it was proposed that a bis(aminophosphinite-
κP) coordinated complex is reversibly formed in equilibrium
with the mono κP,κN coordinated complex.46 Our results above
provide evidence in support of this assumption. Indeed, variable-
temperature 31P{1H} NMR experiments show clearly the easy
P,N opening in cationic allyl palladium complex 6 by addition
of PMe3 or L1 as well as a partial phosphine decoordination
leading to ligand redistribution.
Phosphine Redistribution in the Cationic Allyl Palladium
Chloride Complex 6. In order to evaluate the donor and/or the
labile character of the amine function in the cationic complex
6, we have recorded its phosphorus NMR spectra in CDCl3 and
CD3CN. As no significant shift is observed as a function of the
solvent, we conclude that the acetonitrile is not sufficiently
strong to open the P,N chelate. However, a phosphorus NMR
monitoring of the reaction of 6 with 1 equiv of â-P,N ligand in
CDCl3 showed the absence of the resonances corresponding to
the free ligand and to complex 6 and the presence of a new
(41) Albert, J.; Cadena, J. M.; Granell, J.; Muller, G.; Ordinas, J. I.;
Panyella, D.; Puerta, C.; San˜udo, C.; Valerga, P. Organometallics 1999,
18, 3511-3518.
(42) Hayashi, T.; Iwamura, H.; Naito, M.; Matsumoto, Y.; Uozumi, Y. J.
Am. Chem. Soc. 1994, 116, 775-776.
Coordination Properties of L4 in the Neutral Allyl Pal-
ladium Chloride Complex 8. As the ligand L4 contains a good
oxygen atom donor in the amide function, we have carried out
(43) Mason, R.; Russell, D. R. J. Chem. Soc., Chem. Commun. 1966, 26-
27.
(44) Fryzuk, M. D.; Le Page, M. D.; Montgomery, C. G.; Rettig, S. J.
Inorg. Chem. Commun. 1999, 2, 378-380.
(45) Wehman-Ooyevaar, I. C. M.; Grove, D. M.; Kooijman, H.; van der
Sluis, P.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 1992, 114,
9916-9924.
(46) Haaren, R. J.; Druijven, C. J. M.; van Strijdonck, G. P. F.; Oevering,
H.; Reek, J. N. H.; Kamer, P. C. J.; van Leeuwen, P. W. N. M. J.
Chem. Soc., Dalton Trans. 2000, 1549-1554.

Synthesis of â-P,N Aminophosphines
Inorganic Chemistry, Vol. 40, No. 7, 2001 1605
Scheme 4
Figure 5. 31P{1H} NMR spectra at variable temperature for complex
8 in CD3CN.
Conclusion
A â-aminophosphine L1 has been prepared in only one step
by the reaction of the CdN bond in N-phenylbenzaldimine
toward the carbanionic species Ph2PCH2-. When this ligand
adopts a κP,κN coordination mode, a new chiral nitrogen center
is generated. Its absolute configuration is fixed by that of the
adjacent carbon atom, with the C- and N-bonded phenyl groups
occupying equatorial positions. In cationic palladium complexes,
we have also shown that the N atom chirality may be lost by
its hemilabile character in the presence of strong donors (i.e.,
tertiary phosphines). The synthesis of optically pure ligand L1
and related ligands is currently in progress.
Figure 4. 31P{1H} NMR spectra at variable temperature for phosphine
exchange on complexes 7a, 7b, and 7c in CD3CN.
preliminary investigations of its coordination properties to the
1
neutral allyl palladium system. The reaction with /2 equiv of
[PdCl(η3-C3H5)]2 in CDCl3 solution leads to the formation of
complex 8, see Scheme 4. The IR spectrum exhibits an
absorption band at 1641 cm-1 identical to that found for the
free ligand at 1642 cm-1, excluding the O-coordination mode
of the functional ligand and suggesting a κP coordination mode
analogous to that shown for complex 4. A similar κP coordina-
tion has also been reported for a related palladium complex
containing a phosphino-ester ligand.47,48 However, in contrast
to complexes 6 and 7a-c which exhibit only one set of
On the other hand, when L1 behaves as a monodentate ligand,
an unexpected N-H‚‚‚Cl intramolecular interaction has been
observed in the solid state. The variable-temperature 31P{1H}
NMR experiments have shown that the allyl interconversion
rate is strongly affected by the electronic effects in these related
palladium complexes. Indeed, this rate is higher for a cationic
complex than for a related neutral one owing to the increase of
the metal electrophilic character. Surprisingly, different allyl
interconversion rates have also been observed for neutral
complexes containing either L1 with a secondary amine function
or L4 ligand with an amide function. This latter observation is
rationalized for the first time on the basis of an electron-
withdrawing effect generated by the N-H‚‚‚Cl intramolecular
interaction. The effects of this type of weak interaction on the
organometallic reactivity and in homogeneous catalysis are also
currently examined.
1
resonances by NMR, the H, 13C{1H}, 31P{1H} NMR spectra
of the reaction product show the presence of two complexes in
the same ratio (ca. 1:1) in CDCl3 or in CD3CN solutions at
room temperature, see Scheme 4. The presence of two com-
plexes is consistent with the slow interconversion of two
diastereoisomers. The variable-temperature 31P{1H} NMR in-
vestigation (see Figure 5) shows a coalescence temperature for
8 at ca. 322 K.
Under the assumption that the allyl rearrangement rate can
be qualitatively correlated with the coalescence temperatures,
the rate decreases in the order 6 > 4 > 8. A steric effect of the
amine or amide function in L1 or L4 could reasonably be
excluded as the factor determining this rate difference, because
these functions are relatively far from the allylic carbon atoms.
Rather, the data suggest an electronic control, since the formal
charge on the metal center decreases in the order 6 (cationic)
> 4 (neutral with H-bond) > 8 (neutral without H-bond). A
greater effective positive charge may render the η3/η1 allyl
rearrangement more facile by reducing the M-allyl back-bonding
component.
Acknowledgment. We knowledge the Conseil Re´gional de
Bourgogne, the MENRT, and the CNRS for financial support
of this work, the European Commission for an Erasmus
exchange undergraduate student program concerning J.D. from
the University of Kaiserslautern, Germany, and the MENRT
for a student followship to J.M.C.
Supporting Information Available: X-ray crystallographic files
in CIF format for complexes 1 and 4. This material is available free of
charge via the Internet at http://pubs.acs.org.
(47) Britovsek, G. J. P.; Keim, W.; Mecking, S.; Sainz, D.; Wagner, T. J.
Chem. Soc., Chem. Commun. 1993, 1632-1633.
(48) Mecking, S.; Keim, W. Organometallics 1996, 15, 2650-2656.
IC000867Y