Synthesis and characterization of new (N-diphenylphosphino)- isopropylanilines and their complexes: Crystal structure of (Ph 2P=S)NH-C6H4-4-CH(CH3)2 and catalytic activity of palladium(II) complexes in the Heck and Suzuki cross-coupling reactions

Article abstract of DOI:10.1002/aoc.1576

Three new (N-diphenylphosphino)-isopropylanilines, having isopropyl substituent at the carbon 2- (1) 4- (2) or 2,6- (3) were preparedfromtheaminolysisof chlorodiphenylphosphine with 2-isopropylaniline, 4-isopropylanilineor2,6-diisopropylaniline, respectively, under anaerobic conditions. Oxidation of 1,2 and 3 with aqueous hydrogen peroxide, elemental sulfur or gray selenium gave the corresponding oxides, sulfides and selenides (Ph₂P=E)NH-C₆H₄-2-CH(CH₃) ₂, (Ph₂P=E)NH-C₆H₄-4- CH(CH ₃)₂ and (Ph₂P=E)NH-C₆H ₄-2,6-{CH(CH₃)₂}₂, where E = O, S, or Se, respectively. The reaction of [M(cod)Cl₂] (M = Pd, Pt; cod = 1,5-cyclooctadiene) with two equivalents of 1,2 or 3 yields the corresponding monodendate complexes [M((Ph₂P)NH-C₆H₄-2- CH(CH₃)₂)₂Cl₂], M = Pd 1d, M = Pt 1e, [M((Ph₂P)NH-C₆H₄-4-CH(CH₃) ₂)₂Cl₂], M = Pd 2d, M = Pt 2e and [M((Ph ₂P)NH-C₆H₄-2,6-(CH(CH₃) ₂)₂)₂Cl₂], M = Pd 3d, M = Pt 3e, respectively. All the compounds were isolated as analytically pure substances and characterized by NMR, IR spectroscopy and elemental analysis. Furthermore, representative solid-state structure of [(Ph₂P S)NH-C ₆H₄-4-CH(CH₃)₂] (2b) was determined using single crystal X-ray diffraction technique. The complexes 1d-3d were tested and found to be highly active catalysts in the Suzuki coupling and Heck reaction, affording biphenyls and stilbenes, respectively. Copyright

Full text of DOI:10.1002/aoc.1576

Full Paper
Received: 5 June 2009
Revised: 8 September 2009
Accepted: 26 September 2009
Published online in Wiley Interscience: 26 November 2009
(www.interscience.com) DOI 10.1002/aoc.1576
Synthesis and characterization of new
(N-diphenylphosphino)-isopropylanilines
and their complexes: crystal structure
of (Ph2P S)NH–C6H4 –4–CH(CH3)2
and catalytic activity of palladium(II)
complexes in the Heck and Suzuki
cross-coupling reactions
a
a∗
b
b
˙
¨
Murat Aydemir , Akın Baysal , Nevin Gu¨rbu¨z , Ismail Ozdemir ,
a
c
d
d
¨
Bahattin Gu¨mgu¨m , Saim Ozkar , Nagihan C¸aylak and Leyla Tatar Yıldırım
Three new (N-diphenylphosphino)-isopropylanilines, having isopropyl substituent at the carbon 2- (1) 4- (2) or 2,6- (3) were
preparedfromtheaminolysisofchlorodiphenylphosphinewith2-isopropylaniline,4-isopropylanilineor2,6-diisopropylaniline,
respectively, under anaerobic conditions. Oxidation of 1,2 and 3 with aqueous hydrogen peroxide, elemental sulfur or gray
selenium gave the corresponding oxides, sulfides and selenides (Ph2P E)NH–C6H4 –2-CH(CH3)2, (Ph2P E)NH–C6H4 –4-
CH(CH3)2 and (Ph2P E)NH–C6H4 –2,6-{CH(CH3)2}2, where E = O, S, or Se, respectively. The reaction of [M(cod)Cl2] (M =
Pd, Pt; cod = 1,5-cyclooctadiene) with two equivalents of 1,2 or 3 yields the corresponding monodendate complexes
[M((Ph2P)NH–C6H4 –2-CH(CH3)2)2Cl2], M = Pd 1d, M = Pt 1e, [M((Ph2P)NH–C6H4 –4-CH(CH3)2)2Cl2], M = Pd 2d, M = Pt 2e
and [M((Ph2P)NH–C6H4 –2,6-(CH(CH3)2)2)2Cl2], M = Pd 3d, M = Pt 3e, respectively. All the compounds were isolated as
analytically pure substances and characterized by NMR, IR spectroscopy and elemental analysis. Furthermore, representative
solid-state structure of [(Ph2P S)NH–C6H4 –4-CH(CH3)2] (2b) was determined using single crystal X-ray diffraction technique.
The complexes 1d–3d were tested and found to be highly active catalysts in the Suzuki coupling and Heck reaction, affording
c
biphenyls and stilbenes, respectively. Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Supporting information may be found in the online version of this article.
Keywords: aminophosphine; crystal structure; catalysis; Heck reaction; Suzuki coupling
Introduction
Because of their remarkable catalytic potential and their
large versatility, palladium complexes have become the most
popular organometallics used in organic synthesis.[9] In particular,
palladium catalyzes most of the carbon–carbon bond formation
reactions such as Heck and Suzuki reactions,[10] which are
powerful tools for the preparation of unsymmetrical biaryl[11,12]
and stilbene compounds.[13] Recently, various bulky and electron-
The effects of ligands on structure and reactivity of transition
metal complexes are important topics of research in coordina-
tion and organometallic chemistry as well as in homogeneous
catalysis.[1] The large impact of phosphine ligand has become evi-
dentfromtheimportantdiscoveryoftheWilkinsonhydrogenation
catalyst.[2] Thus, there is immense interest in the development of
new phosphorus(III) ligands for various applications, principally
those of homogeneous metal-catalyzed reactions.[3] Phospho-
rus–nitrogen containing ligands have particular use in catalysis
where it is necessary for part of ligand to dissociate to allow an or-
ganic fragment to coordinate and undergo transformations. Small
variations in the ligands can cause significant changes in their
coordination behavior and the structural features of the resulting
complexes.[4] The presence of P–N ligands enables many different
and important catalytic processes to occur including Heck[5,6] and
Suzuki[7,8] reactions.
∗
Correspondence to: Akın Baysal, Dicle University, Department of Chemistry,
TR-21280 Diyarbakır, Turkey. E-mail: akinb@dicle.edu.tr
a
b
c
Dicle University, Department of Chemistry, TR-21280 Diyarbakır, Turkey
¨
Inonu¨ University, Department of Chemistry, TR-44280 Malatya, Turkey
Middle East Technical University, Department of Chemistry, TR-06531 Ankara,
Turkey
d
Hacettepe University, Department of Physics Engineering, Beytepe, TR-06800
Ankara, Turkey
c
Appl. Organometal. Chem. 2010, 24, 17–24
Copyright ꢀ 2009 John Wiley & Sons, Ltd.

M. Aydemir et al.
rich phosphanes have been developed as ligands to promote the
cross-couplingreactions.[14] Wehaveshownthataminophosphine
and bis(aminophosphine) palladium(II) complexes offer distinct
advantages over the Pd–phosphine system in the Suzuki and
Heck cross-coupling reactions.[15,16]
Preparation of (N-diphenylphosphino)-4-isopropylaniline, 2
A dry and degassed THF (50 ml) solution of 4-isopropylaniline
(0.38g, 2.75 mmol) was cooled to −78 ◦C in an acetone and dry
ice bath. To the cooled solution was added dropwise a hexane
solution of n-BuLi (2 ml, 2.75 mmol) over 1 h. After the addition
the mixture was stirred at −78 ◦C for 1 h and another 30 additional
minutes at room temperature. The reaction solution was cooled to
−78 ◦C again and a solution of diphenylchlorophosphine (0.64 g,
2.75 mmol) in THF (10 ml) was added dropwise to the reaction
medium. Stirring was continued for a further 1 h at −78 ◦C.
Then the cooling bath was removed and the mixture was stirred
overnight at room temperature. The solution was evaporated to
dryness in vacuo and CH2Cl2 (30 ml) was added. Lithium chloride,
which precipitated, was removed by filtration under argon and
thenthevolatileswasevaporatedinvacuotoleaveayellowviscous
Herein, we report the preparation of the three new
(N-diphenylphosphino)isopropylanilines, having isopropyl sub-
stituent at the carbon 2- (1), 4- (2) or 2,6- (3) from the
aminolysis of the respective aniline with one equivalent of
chlorodiphenylphosphine in the presence of a base, as well as
their oxides (a), sulfides (b), selenides (c) and complexes with
Pd2+ (d) and Pt2+ (e). The structures of all new compounds were
elucidated by a combination of multinuclear NMR spectroscopy,
IR spectroscopy and elemental analysis. Furthermore, the X-ray
crystal structure of (N-diphenylthiophosphino)-4-isopropylaniline,
[(Ph2P S)NH–C6H4 –4-CH(CH3)2] (2b) was determined, and per-
tinent features of this structure were described. In addition,
extending our program in the design and study to develop useful
catalystsfortheC–Ccouplingreaction, palladiumcomplexeswere
tested as catalyst in the Suzuki–Heck type coupling reactions.
1
oil compound 2; yield 0.85 g (97%). 31P–{ H} NMR (162.0 MHz,
CDCl3): δ = 31.8 (s) ppm (see Supporting Information for 1H and
13C NMR data). IR (KBr): υ = 899 (P–N), 1439 (P–Ph), 3377 (N–H)
cm−1. C21H22NP (319.39 g mol−1): calcd C 78.98, H 6.94, N 4.39;
found C 78.85, H 6.87, N 4.34.
Preparation of (N-diphenylphosphino)-2,6-diisopropylaniline, 3
Experimental Section
Chlorodiphenylphosphine (1.10 g, 4.75 mmol) was added drop-
wise over a period of 30 min to a stirred solution of 2,6-
diisopropylaniline (0.94 g, 4.75 mmol) and triethylamine (0.49 g,
4.75 mmol) in CH2Cl2 (50 ml) at 0 ◦C with vigorous stirring. The
mixture was stirred at r.t. for 2 h, and the solvent was removed
under reduced pressure. After addition of dry diethyl ether, the
white precipitate (triethylammonium chloride) was filtered off un-
der argon and the solvent removed in vacuo which was washed
with cold diethyl ether (2 × 15 ml) and dried in vacuo to produce
Materials and Methods
All reactions and manipulations were performed under argon
unless otherwise stated. 2-Isopropylaniline, 4-isopropylaniline,
2,6-diisopropylaniline and Ph2PCl were purchased from Fluka
and used directly. Analytical grade and deuterated solvents were
purchased from Merck. The starting materials [MCl2(cod)] (M = Pd,
Pt, cod = 1,5-cyclooctadiene)[17,18] were prepared according to
literature procedures. Solvents were dried using the appropriate
reagents and distilled prior to use. Infrared spectra were recorded
as KBr disks in the range 4000–400 cm−1 on a Mattson 1000 ATI
Unicam FT-IR spectrometer. 1H (400.1 MHz), 13C NMR (100.6 MHz)
1
yellow viscous oil compound 3; yield 1.65 g (96%). 31P–{ H} NMR
(162.0 MHz, CDCl3): δ = 45.5 (s) ppm (see Supporting Information
for 1H and 13C NMR data). IR (KBr): υ = 802 (P–N), 1438 (P–Ph),
3344 (N–H) cm−1. C24H28NP (361.47 g mol−1): calcd C 79.75, H
7.81, N 3.88; found C 79.68, H 7.77, N 3.85.
1
and 31P–{ H} NMR (162.0 MHz) spectra were recorded on a Bruker
Avance 400 spectrometer, with δ referenced to external TMS and
85% H3PO4, respectively. GC analyses were performed on an HP
6890N gas chromatograph equipped with capillary column (5%
biphenyl, 95% dimethylsiloxane, 30 m × 0.32 mm × 0.25 µm).
Elemental analysis was carried out on a Fisons EA 1108 CHNS-
O instrument. Melting points were determined by Gallenkamp
Model apparatus with open capillaries.
Synthesis and Characterization of Chalcogenides
See Supporting Information.
Synthesis of Complexes
Preparation of dichlorobis((N-diphenylphosphino)-2-
isopropylaniline)palladium(II), 1d
Synthesis of Ligands
[Pd(cod)Cl2] (0.10 g, 0.36 mmol) and 1 (0.23 g, 0.72 mmol) were
dissolved in dry THF (25 ml) and stirred for 3 h. The volume was
concentrated to ca. 1–2 ml under reduced pressure and addition
of diethyl ether (20 ml) gave 1d as a clear yellow solid. The
product was collected by filtration and dried in vacuo; yield 0.26 g
Preparation of (N-diphenylphosphino)-2-isopropylaniline, 1
Chlorodiphenylphosphine (0.33 g, 1.41 mmol) was added drop-
wise over a period of 20 min to a stirred solution of 2-
isopropylaniline (0.20 g, 1.41 mmol) and triethylamine (0.14 g,
1.41 mmol) in THF–CH2Cl2 (1 : 2) (30 ml) at 0 ◦C with vigorous
stirring. The mixture was stirred at room temperature (r.t.) for 2 h,
and the solvent was removed under reduced pressure. After ad-
dition of THF, the white precipitate (triethylammonium chloride)
was filtered off under argon and the solvent removed in vacuo,
which was washed with cold diethyl ether (2 × 15 ml) and dried in
vacuo to produce dark yellow viscous oil compound 1; yield 0.43 g
(89%); m.p. >300 ◦C (dec.). 31P–{ H} NMR (162.0 MHz, DMSO):
1
δ = 38.9 (s) ppm (see Supporting Information for 1H and 13C NMR
data). IR (KBr): υ = 893 (P–N), 1442 (P–Ph), 3446 (N–H) cm−1
.
C42H44N2P2PdCl2 (816.11 g mol−1): calcd C 61.81, H 5.43, N 3.43;
found C 61.74, H 5.36, N 3.40.
Preparation of dichlorobis((N-diphenylphosphino)-4-
isopropylaniline)palladium(II), 2d
1
(92%). 31P–{ H} NMR (162.0 MHz, CDCl3): δ = 29.0 (s) ppm (see
Supporting Informationfor1Hand13C NMRdata). IR(KBr): υ = 899
(P–N), 1439 (P–Ph), 3391 (N–H) cm−1. C21H22NP (319.39 g mol−1):
calcd C 78.98, H 6.94, N 4.39; found C 78.87, H 6.85, N 4.35
[Pd(cod)Cl2] (0.10 g, 0.36 mmol) and 2 (0.23 g, 0.72 mmol) were
dissolved in dry THF (25 ml) and stirred for 2 h. The volume was
c
www.interscience.wiley.com/journal/aoc
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2010, 24, 17–24

New (N-diphenylphosphino)-isopropylanilines and their complexes
concentrated to ca. 1–2 ml under reduced pressure and addition
of diethyl ether (20 ml) gave 2d as a yellow solid. The product was
collected◦by filtration and dried in vacuo; yield 0.27 g (92%); m.p.
Single-crystal X-ray diffraction analysis of
(Ph2PS)NH–C6H4 –4-CH(CH3)2, 2b
Asuitableprismaticcolorlesscrystalof2bwasgluedtoathinquartz
glass and mounted on the goniometry of an Enraf Nonious CAD4
difractometer. Intensity data were collected at room temperature
by operating in ω/2θ scan mode with graphite monochromated
MoKα radiation, λ = 0.71073 Å (operating at 40 kV and 40 mA).
Data reduction was performed using XCAD4.[19] The structure
was solved by direct methods and refinement using the program
SHELX[20] in the WinGX package.[21] A full-matrix least-squares
refinement on F2 converged at R = 0.0484. Semi-empirical
absorption corrections were applied using psi-scans.[22] All non-
hydrogenatomswererefinedanisotropically.Thehydrogenatoms
of the N and C19 atoms are taken from a difference Fourier map
and their positional parameters fixed, while the other hydrogen
atoms are in calculated positions using the riding method with
Uiso(H) = 1.5 Ueq(CH3) and Uiso(H) = 1.2 Ueq(C). The hydrogen
bond and molecular packing geometry of the title molecule was
calculated with PLATON.[23] The graphical representations of the
structure were made with ORTEP[24] and MERCURY.[25]
1
264–266 C. 31P–{ H} NMR (162.0 MHz, DMSO): δ = 36.6 [(s), cis-
isomer], 34.1 [(s), trans-isomer] ppm (see Supporting Information
for 1H and 13C NMR data). IR (KBr): υ = 917 (P–N), 1434 (P–Ph),
3425 (N–H) cm−1. C42H44N2P2PdCl2 (816.11 g mol−1): calcd C
61.81, H 5.43, N 3.43; found C 61.74, H 5.39, N 3.40.
Preparation of dichlorobis((N-diphenylphosphino)-2,6-
diisopropylaniline)palladium-(II), 3d
[Pd(cod)Cl2] (0.08 g, 0.28 mmol) and 3 (0.20 g, 0.56 mmol) were
dissolved in dry CH2Cl2 (20 ml) and stirred for 2 h. The volume
was concentrated to ca. 1–2 ml under reduced pressure and
addition of diethyl ether (25 ml) gave 3d as a clear yellow solid.
The product was collected◦by filtration and dried in vacuo; yield:
1
0.21 g, 84%; m.p. 249–251 C. 31P–{ H} NMR (162.0 MHz, DMSO):
δ = 64.1 (s) ppm (see Supporting Information for 1H and 13C NMR
data). IR (KBr): υ = 802 (P–N), 1438 (P–Ph), 3262 (N–H) cm−1
.
C48H56N2P2PdCl2 (900.27 g mol−1): calcd C 64.04, H 6.27, N 3.11;
found C 63.96; H 6.21; N 3.09.
Preparation of dichlorobis((N-diphenylphosphino)-2-
isopropylaniline)platinum(II), 1e
General Procedure for the Suzuki Coupling Reaction
Complexes 1–3d (0.01 mmol), aryl bromide (1.0 mmol), phenyl-
boronic acid (1.5 mmol), Cs2CO3 (2 mmol) and dioxane (3 ml) were
placed into a small Schlenk tube in argon atmosphere and the
mixture was heated at 80 ◦C for 7.0 h for 1d, at 80 ◦C for 6.0 h
for 2d and at 70 ◦C for 4.0 h for 3d. After completion of the reac-
tion, the mixture was cooled, extracted with ethyl acetate–hexane
(1 : 5), filtered through a pad of silicagel with copious washing,
concentrated and purified by flash chromatography on silica gel.
The purity of the compounds was checked by GC and NMR and
yields are based on aryl bromide.
[Pt(cod)Cl2] (0.14 g, 0.36 mmol) and 1 (0.23 g, 0.72 mmol) were
dissolved in dry THF (25 ml) and stirred for 3 h. The volume was
concentrated to ca. 1–2 ml under reduced pressure and addition
of diethyl ether (20 ml) gave 1e as a white solid. The product was
collected◦by filtration and dried in vacuo; yield 0.29 g (89%); m.p.
1
209–211 C. 31P–{ H} NMR (162.0 MHz, DMSO): δ = 28.6 [(s) ppm,
J(PPt): 3924.0 Hz] (see Supporting Information for 1H and 13C NMR
data). IR (KBr): υ = 918 (P–N), 1439 (P–Ph), 3435 (N–H) cm−1
.
C42H44N2P2PtCl2 (904.77 g mol−1): calcd C 55.76, H 4.90, N 3.09;
found C 55.69, H 4.85, N 3.05.
Preparation of dichlorobis((N-diphenylphosphino)-4-
isopropylaniline)platinum(II), 2e
General Procedure for the Heck Coupling Reaction
Complexes 1–3d (0.01 mmol), aryl bromide (1.0 mmol), styrene
(1.5 mmol), K2CO3 (2 mmol) and DMF (3 ml) for 1–3d were placed
into a small Schlenk tube in argon atmosphere and the mixture
was heated to 120 ◦C for 1–3d. After completion of the reaction,
the mixture was cooled, extracted with ethyl acetate–hexane
(1 : 5), filtered through a pad of silicagel with copious washing,
concentrated and purified by flash chromatography on silica gel.
The purity of the compounds was checked by GC and NMR and
yields are based on aryl bromide.
[Pt(cod)Cl2] (0.14 g, 0.36 mmol) and 2 (0.23 g, 0.72 mmol) were
dissolved in dry THF (25 ml) and stirred for 2 h. The volume was
concentrated to ca. 1–2 ml under reduced pressure and addition
of diethyl ether (20 ml) gave 2e as a yellow solid. The product
was collected ◦by filtration and dried in vacuo; yield 0.31 g (95%);
1
m.p. 190–192 C. 31P–{ H} NMR (162.0 MHz, DMSO): δ = 32.6 [(s),
cis-isomer, J(PPt): 3926.0 Hz], 24.1 [(s), trans-isomer, J(PPt): 3336.0 Hz]
1
13
(see Supporting Information for H and C NMR data). IR (KBr):
υ = 910 (P–N), 1435 (P–Ph), 3417 (N–H) cm−1. C42H44N2P2PtCl2
(904.77 g mol−1): calcd C 55.76, H 4.90, N 3.10; found C 55.71, H
4.84, N 3.05.
Results and Discussion
Preparation of dichlorobis((N-diphenylphosphino)-2,6-
diisopropylaniline)platinum-(II), 3e
Aminolysis appears to be the most common method
used for the synthesis of phosphinoamines and
bis(phosphino)amines,[26,27] whereby the solvent has a sig-
nificant influence on the rate and product of the aminol-
ysis. (N-diphenylphosphino)isopropylanilines, having isopropyl
substituent at the carbon 2- (1) or 2,6- (3) were easily
prepared from the aminolysis of H2N–C6H4 –2-CH(CH3)2 or
H2N–C6H4 –2,6-{CH(CH3)2}2, respectively, with one equivalent of
chlorodiphenylphosphine in the presence of triethylamine at 0 ◦C
using THF–CH2Cl2 (1 : 2) and CH2Cl2 as solvents, respectively.
Compounds 1 and 3 were isolated as viscous oily compounds
[Pt(cod)Cl2] (0.10 g, 0.28 mmol) and 3 (0.20 mg, 0.56 mmol) were
dissolved in dry CH2Cl2 (20 ml) and stirred for 2 h. The volume was
concentratedtoca.1–2 mlbyevaporationunderreducedpressure
and addition of diethyl ether (25 ml) gave 3e as a white solid.
The product was collected◦by filtration and dried in vacuo; yield
0.22 g, 80%; m.p. 294–296 C. 31P–{ H} NMR (162.0 MHz, DMSO):
1
δ = 28.4[(s) ppm, J(PPt):3893.0 Hz](seeSupportingInformationfor
1H and 13C NMR data). IR (KBr): υ = 833 (P–N), 1438 (P–Ph), 3413
(N–H) cm−1. C48H56N2P2PtCl2 (988.93 g mol−1): calcd C 58.30, H
5.71, N 2.83; found C 58.22, H 5.66, N 2.80.
c
Appl. Organometal. Chem. 2010, 24, 17–24
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
www.interscience.wiley.com/journal/aoc

M. Aydemir et al.
Scheme 1. Synthesis of (N-diphenylphosphino)-2-isopropylaniline, (Ph2P)NH–C6H4 –2-CH(CH3)2, (N-diphenylphosphino)-4-isopropylaniline,
(Ph2P)NH–C6H4 –4-CH(CH3)2 and (N-diphenylphos-phino)-2,6-diisopropylaniline, (Ph2P)NH–C6H4 –2,6-{CH(CH3)2}2 and their chalcogenides.
in high yields (92 and 96%, respectively) under anaerobic condi- oxidation when exposed to air or moisture. The solution of 1–3 in
tions. However, the attempt to prepare (N-diphenylphosphino)-4- CDCl3, prepared under anaerobic conditions, oxidized gradually
isoprophylaniline (2) hardly succeed, due to the formation of N,N- to give respective oxide and bis(diphenylphosphino)monoxide
bis(diphenylphosphino)-4-isopropylaniline, [(Ph2P)2N–(C6H4)–4- [P(O)Ph2PPh2] derivatives.
CH(CH3)2]. Therefore, the preparation of 2 was achieved only with
Compounds 1–3 were fully characterized by NMR, IR spec-
one equivalent of Ph2PCl, in the presence of n-BuLi at −78 ◦C as a troscopy and elemental analysis. The IR spectra of 1–3 showed
yellow viscous oil compound (97%) (Scheme 1).
characteristic absorption bands at 3391, 3377 and 3344 cm−1
,
The 31P–{H} NMR spectra taken from the crude solutions of respectively, due to υ(N–H) stretching. The 31P–{ H} NMR
1–3 display in addition to the prominent single resonances at spectra of compounds 1–3 showed single resonances at 29.0,
29.0, 31.8 or 45.5 ppm for the main products 1–3, respectively, 31.8 and 45.5 ppm, respectively, comparable to those of other
1
1
two doublets at 16.8 ppm and −22.1 ppm with a J(PP) value aminophosphines.[29] The phenyl carbons displayed well-resolved
of 286 Hz, indicating the formation of iminobiphosphine [- signals in the 13C–{ H} NMR spectra. In the P(III) compounds
1
N
PPh2 –PPh2] structure.[28] Additionally, the observation of 1–3, the coupling constant between i-carbon and the phos-
a singlet at δ −14.3 ppm and doublets at δ 34.4 ppm and phorus was relatively small, 1J(PC) = 13.1, 20.0 and 16.0 Hz,
1
at δ −23.7 ppm with J(PP) 218 Hz indicates the formation of respectively, while the couplings between o-carbon and the phos-
PPh2PPh2 and P(O)Ph2PPh2, respectively. These by-products were phorus were relatively large, 2J(PC) = 21.1, 21.1 and 20.0 Hz,
easily removed by washing with copious amount of dry diethyl respectively. The coupling constants between m-carbon and the
3
ether. The compounds 1–3 are not stable in solution toward phosphorus were J(PC) = 6.0, 6.0 and 6.0 Hz, respectively, and
Scheme 2. Reactions of aminophosphines 1,2 or 3 with [M(cod)Cl2] (M = Pd, Pt).
c
www.interscience.wiley.com/journal/aoc
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2010, 24, 17–24

New (N-diphenylphosphino)-isopropylanilines and their complexes
Figure 1. ORTEP drawing of the title compound 2b with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
the coupling between p-carbon and the phosphorus was not
observed.
higher magnetic field by 12.2, 9.7, and 20.3 ppm compared with
the parent compounds 1–3, respectively.
The sulfides 1b–3b and selenides1c–3c were prepared by
the addition of elemental S and Se to1–3 in THF, respectively.
To probe the reactivity of compounds 1–3, reactions with
aqueous hydrogene peroxide, elemental sulfur and gray selenium
were carried out (Scheme 1). The oxides 1a, 2a and 3a were easily
prepared by addition of excess aqueous hydrogen peroxide to 1,2
1
The 31P–{ H} NMR showed single resonances at δ(P) 52.8 ppm,
δ(P) 56.1 ppm and δ(P) 60.8 ppm for 1b–3b, respectively. Com-
1
pounds 1c–3c were analyzed by 31P–{ H} NMR spectroscopy,
1
or 3, respectively. The 31P–{ H} NMR spectra of 1a–3a showed
which exhibited singlet resonances at 49.3, 52.6, and 58.1 ppm,
with 1J(31P-77Se) of 791, 762, and 770 Hz, respectively.
singletsatδ(P) 16.8,22.1,and25.2 ppmwhichwereshiftedtowards
The coordination chemistry of the ligands 1–3 was studied
by forming palladium and platinum complexes. The reaction
of [M(cod)Cl2] (M = Pd, Pt; cod = 1,5-cyclooctadiene) with
two equivalents of 1–3 in dichloromethane at room tem-
perature afforded the corresponding monodendate complexes
[M{(Ph2P)NH–C6H4 –2-CH(CH3)2} Cl2], M = Pd 1d, M = Pt 1e,
[M{(Ph2P)NH–C6H4 –4-CH(CH3)2}22Cl2], M = Pd 2d, M = Pt 2e
and [M{(Ph2P)NH–C6H4 –2,6-(CH(CH3)2)2}2Cl2], M = Pd 3d, M =
Pt 3e, respectively, as the main products in high yields (80–90%;
Scheme 2).Inthecomplexes1d–3dand1e–3e,thenitrogenatom
of the amine group was not involved in coordination to the metal
centers because the phosphorus atoms are much stronger donors
and thus coordination to the metal center takes place preferen-
tially at the phosphorus atoms. The formation of complexes1d,3d,
Table 1. Crystal data and results of structure refinement for 2b
Formula
[{(C6H5)2PS}NH C6H4
CH(CH3)2]
Formula weight (g mol−1
)
351.44
Crystal system, space group
Unit cell dimensions (Å, deg)
Monoclinic, P 21/n
a = 12.253(2),
b = 9.7934(10),
c = 15.932(2),
β = 92.628(10)
Cell volume (Å3)/Z
1909.8(4)/4
1.222
Calculated density (g cm−3
)
Crystal color/shape/size (mm)
colorless/prism/0.4 ×
1
1e and 3e was followed by 31P–{ H} NMR spectra which gave
0.3 × 0.3
F(000)
744
singlet signals growing at δ 38.9, 64.1, 28.6 and 28.4 ppm for
1d,3d, 1e and 3e, respectively. The complexes 1e and3e showed
Absorption coefficient (mm−1
)
0.255
1
Absorption correction type
Psi-scan
0.912/0.935
2.44–26.3
large JPtP coupling 3924 and 3893 Hz, respectively, which are
characteristic of phosphines having mutually cis-arrangement.[30]
T
max/Tmin
1
The 31P–{ H}-NMR spectra of complexes 2d and 2e showed two
θ-range for data collection (deg)
Limiting indices
−15 ≤ h ≤ 15,
−12 ≤ k ≤ 0,
−19 ≤ l ≤ 19
sharp singlets at δ 36.6, 34.1 and 32.6, 24.1 ppm with relative
intensity ratios of ∼5 : 3 and ∼3 : 2, attributable to the mixture of
Reflections collected/unique
7725/3881
[Rint = 0.0484]
Data/parameters/restraints
Goodness-of-fit on F2
3881/221/2
1.097
Table 2. Coordination geometry around the P atom for 2b (Å, deg)
P–S
1.9447(9)
1.6603(18)
1.805(2)
S–P–N
S–P–C1
S–P–C7
N–P–C7
N–P–C1
C1–P–C7
115.53(8)
115.39(8)
111.51(8)
106.99(11)
99.44(10)
106.92(10)
Final R indices [I > 2σ(I)]
R1 = 0.0460,
wR2 = 0.1243
P–N
P–C1
P–C7
N–H
Largest difference peak and hole (e Å−3
)
0.249, −0.392
1.807(2)
Further details on the structural investigation are available on request
from the Cambridge Crystallographica Data Centre, quoting the
depository number CCDC 720017.
0.9417(18)
c
Appl. Organometal. Chem. 2010, 24, 17–24
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
www.interscience.wiley.com/journal/aoc

M. Aydemir et al.
1
cis- and trans- forms of2d and 2e, respectively. From the 31P–{ H}
and the compositions of the six complexes were confirmed by
elemental analysis.
NMR data it can be concluded that 2d and 2e are on the verge
of preferential cis- and trans-geometry. Upon redisolving and
stirring for 24 h, no change in the cis : trans ratio was observed.
It is difficult to make an unequivocal assignment of the signals
to the respective isomers. However, in the case of complex 2e,
an assigment can be made on the basis of 1J(Pt–P) coupling
constants. It is known that in platinum(II) complexes PtCl2(PR3)2,
the 1J(Pt–P) coupling constant in the cis-isomer is larger than
that in the trans-isomer.[31,32] Therefore, the signal with the large
1J(135Pt–31P) coupling constant of 3926.0 Hz for 2e is assigned to
the cis arrangement of phosphines around the platinum(II) center
Palladium(II) complexes were found to be stable in the solid
state, but decomposed in solution when exposed to air. The
decomposition of the complexes was followed in situ by 31P NMR
spectroscopy.Theresonancescorrespondingtocomplexes1d–3d
gradually disappeared with concomitant formation of Ph2P(O)H
and Ph2P(O)OH as indentified by signals at δ = 21 and 35 ppm,
respectively.[35]
A single crystal of [(Ph2P S)NH–C6H4 –4-CH(CH3)2] 2b suitable
for X-ray diffraction studies was obtained by slow diffusion of
diethyl ether into solution of the compound in dichloromethane.
while the signal with the small J (135Pt–31P) coupling constant
1
Solid-state Crystal Structure of [(Ph2P S)NH–C6H4 –4-
CH(CH3)2], 2b
of 3336.0 Hz is assigned to the trans arrangement. The chemical
shifts for 2d can help us in assigning the signals to the respec-
tive isomer. By comparing to the literature values, the signal at δ
36.6 ppm was tentatively assigned to the cis-isomer and the one
at δ 34.1 ppm to the trans-isomer. In the nonchelating phosphine
complexes, the phosphorus signal of the cis-isomers has been al-
ways observed at lower field than that of the trans-isomer.[33,34] In
the IR spectra, the υ(P–N) vibrations were observed as very strong
bands at ca. 893, 917, 802 for 1d–3d and 918, 910, and 833 cm−1
for 1e–3e. Furthermore, 1H NMR spectral data of the complexes
1d–3d and 1e-3e were consistent with the structures proposed
The compound (Ph2P S)NH–C6H4 –4-CH(CH3)2 crystallizes in
monoclinic crystal system with an asymmetric unit formula of
PNSC21H22 (Fig. 1). The crystallographic data are listed in Table 1.
The bond distances and bond angles around the P atom are given
in Table 2. The P atom has a distorted tetrahedral coordination
sphere consisting of one N, one S and two C atoms of the phenyl
rings at bond distances P–S = 1.9447(9), P–N = 1.6603(18),
P–C1 = 1.805(2) and P–C7 = 1.807(2) Å. The bond angles within
the coordination sphere are close to the ideal value of 109◦,
Table 3. The Suzuki coupling reactions of aryl bromides with phenylboronic acid
Entry
R
Cat
Product
Conv.(%)
Yield(%)
1
2
4-CH3C(O)-
1d
2d
94.36
91.74
92.25
90.33
3
4
5
3d
1d
2d
92.20
93.85
95.73
89.23
93.46
94.62
4-CH(O)-
4-H
6
7
8
3d
1d
2d
88.46
82.20
73.34
87.52
75.78
69.78
9
3d
1d
2d
82.28
75.45
64.34
81.85
72.68
61.36
10
11
4-CH3O-
4-CH3-
12
13
14
3d
1d
2d
70.83
74.85
70.30
67.51
70.84
63.08
15
3d
65.18
60.08
Reaction conditions: 1.0 mmol of p-R-C6H4Br aryl bromide, 1.5 mmol of phenylboronic acid, 2.0 mmol Cs2CO3 0.01 mmol catalyst, dioxane (3.0 ml).
Purity of compounds was checked by NMR and yields are based on arylbromide. All reactions were monitored by GC, 80 ◦C, 7.0 h for 1d; 80 ◦C, 6.0 h
for 2d; 70 ◦C, 4.0 h for 3d.
c
www.interscience.wiley.com/journal/aoc
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2010, 24, 17–24

New (N-diphenylphosphino)-isopropylanilines and their complexes
except the N–P–C1 angle of 99.44(10)◦. The distortion of this
angle from ideal tetrahedral geometry is a consequence of the
steric repulsion in the (N-diphenylphosphino)-2-isopropylaniline
molecule.
p-bromobenzaldehyde, p-bromobenzene, p-bromoanisole and p-
bromotoluene reacted cleanly with phenylboronic acid in high
yields (Table 3).
The Heck Coupling Reactions
The Suzuki Coupling Reactions
For the choice of base, we surveyed Cs2CO3, K2CO3 and KtOBu.
Finally, we found that use of 1.0% mmol, 2 equivalents of K2CO3 in
DMF at 120 ◦C for 1d–3d led to the best conversions. We initially
tested the catalytic activities of 1d–3d for the coupling of p-
bromoacetophenonewithstyrene.Acontrolexperimentindicated
that the coupling reaction did not occur in the absence of 1d–3d.
Under the determined reaction conditions, a wide range of aryl
bromides bearing electron-donating and electron-withdrawing
groups reacted with styrene, affording the coupled products in
excellent yields. As expected, electron-deficient bromides were
beneficialfortheconversions(Table 4).Usingarylchloridesinstead
ofarylbromidesyieldedonlyasmallamountofstilbenederivatives
under the conditions employed for bromides.
The palladium complexes 1d–3d were tested as catalyst in the
Suzuki reaction of aryl halides with boronic acid, which is one of
the most efficient methods for C–C bond formation.[36] Among
the bases (Cs2CO3, K2CO3 and KtOBu) screened, Cs2CO3 gave
the best yields. Following optimization of experiments we found
that the use of 0.01 mmol the palladium complexes 1d–3d with
Cs2CO3 as the base at 80, 80 and 70 ◦C in dioxane appeared to
be best, respectively. We initially tested the catalytic activity of
the complexes 1d–3d for the coupling of p-bromoacetophenone
with phenylboronic acid and the control experiments showed
that the coupling reaction does not occur in the absence of
the catalyst. Under these conditions, p-bromoacetophenone,
Table 4. The Heck coupling reactions of aryl bromides with styrene
Entry
R
Cat
Product
Conv.(%)
Yield(%)
1
2
4-CH3C(O)-
1d
2d
96.61
93.84
94.31
91.90
3
4
5
3d
1d
2d
94.25
96.14
98.28
93.37
95.92
96.71
4-CH(O)-
6
7
8
3d
1d
2d
92.62
75.45
74.39
90.49
70.35
71.18
4-H
9
3d
1d
2d
80.05
53.55
58.82
74.80
51.29
50.63
10
11
4-CH3O-
12
13
14
3d
1d
2d
55.06
64.05
72.30
53.30
62.48
64.56
4-CH3-
15
3d
66.18
60.55
Reaction conditions: 1.0 mmol of p-R-C6H4Br aryl bromide, 1.5 mmol of styrene, 2.0 mmol K2CO3 0.01 mmol catalyst, DMF (3.0 ml) for 1-3d. Purity of
compounds was checked by NMR and yields are based on arylbromide. All reactions were monitored by GC: 120 ◦C, 2.0 h for 1d; 120 ◦C, 4.0 h for 2d;
and 120 ◦C, 2.5 h for 3d.
c
Appl. Organometal. Chem. 2010, 24, 17–24
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
www.interscience.wiley.com/journal/aoc

M. Aydemir et al.
Conclusions
References
[1] P. C. J. Kamer, P. W. N. M. Leeuwen, J. N. H. Reek, Acc. Chem. Res.
2001, 34, 895.
[2] J. F. Young, J. A. Osborn, F. A. Jardine, G. Wilkinson, J. Chem. Soc.
Chem. Commun. 1965, 131.
[3] K. G. Gaw, M. B. Smith, A. M. Z. Slawin, New J. Chem. 2000, 24, 429.
[4] P. Bhattacharyya, J. D. Woollins, Polyhedron 1995, 14, 3367.
In conclusion, we have shown the facile synthesis of versatile
and inexpensive aminophosphine ligands 1,2 and3, based on 2-
isopropylaniline, 4- isopropylaniline or 2,6-diisopropylaniline and
their derivatives including oxides, sulfides and selenides. All these
new compounds were characterized using multinuclear NMR,
IR and microanalysis and also one representative structure was
studiedbysinglecrystalX-raydiffractionanalysis.Thecoordination
behaviors of ligands1–3 towards Pd(II) and Pt(II) have been
described. The ligands show clear tendencies to coordinate in
[5] K. R. Reddy,
K. Surekha,
G. H. Lee,
S. M. Peng,
S. T. Lui,
Organometallics 2000, 19, 2637.
[6] D. P. Catsoulocas, B. R. Steele, G. A. Herapoulos, M. Micha-Screttas,
C. G. Screttas, Tetrahedron Lett. 2003, 44, 4575.
[7] T. Schareima, R. Kepme, Angew. Chem. Int. Ed. 2002, 41, 1521.
[8] S. Urgaonkar, M. Nagarajan, J. G. Verkade, Tetrahedron Lett. 2002,
43, 8921.
[9] B. Cornils, W. A. Hermann, Applied Homogeneous Catalysis with
Organometallic Compounds. Wiley-VCH: Weinheim, 1996, 712.
[10] R. B. Bedford, C. S. J. Cazin, D. Holder, Coord. Chem. Rev. 2004, 248,
2283.
1
a cis-fashion to these transitions metals, as indicated by 31P–{ H}
NMR spectroscopy. However, for complexes 2d and 2e, from
1
the data 31P–{ H} NMR spectroscopy, it was observed that a
mixture of cis and trans isomers formed. Furthermore, we have
demonstrated the application of these aminophosphine ligands
in the Suzuki coupling and Heck reactions of aryl halides. Because
of the strength of the Pt–C bonds, the Pt(II)-bis(phosphino)amine
1–3e system exhibited no catalytic activity.[37] Only the palladium
complexes were found to show catalytic activity in both the
Suzuki coupling and Heck reactions of aryl bromides. In both
cases, the catalytic activities of complexes 1–3d were found to be
higher in reactions of aryl bromides with an electron-withdrawing
substituent than those with an electron-releasing substituent.
The catalytic activity and the yield of coupling reactions could
be controlled over a wide range by variation of the coupling
parameters. The procedure is quite simple and efficient towards
various aryl bromides and does not require an induction period.
It is likely that palladium(0) nanoclusters are formed from the
reduction of palladium(II) complexes. Palladium(0) nanoclusters
are active catalyst in the Suzuki and Heck reactions; however, they
undergo rapid deactivation. As the only stabilizers present in the
reaction medium, the aminophosphine ligands cannot provide
enough stabilization for the palladium(0) nanoclusters against
the aggregate to bulk palladium metal, which are catalytically
inactive.
[11] P. Loyd-Williams, E. Giralt, Chem. Soc. Rev. 2001, 30, 145.
[12] C. Najera, J. Gil-Molto, S. Karlstro¨m, L. R. Falvello, Org. Lett. 2003, 5,
1451.
¨
[13] N. Biricik, F. Durap, C. Kayan, B. Gu¨mgu¨m, N. Gu¨rbu¨z, Y. Ozdemir,
Wee Han. Ang, Zhaofu. Fei, Rosario. Scopelliti, J. Organomet. Chem.
2008, 693, 2693.
[14] V. V. Grushin, H. Alper, Top. J. Organomet. Chem. 1999, 3, 193.
[15] M. Aydemir, A. Baysal, B. Gu¨mgu¨m, J. Organomet. Chem. 2008, 693,
3810.
¨
[16] M. Aydemir, A. Baysal, G. Oztu¨rk, B. Gu¨mgu¨m, Appl. Organometal.
Chem. 2009, 23, 108.
[17] D. Drew, J. R. Doyle, Inorg. Synth. 1972, 13, 47.
[18] J. X. McDermott, J. F. White, G. M. Whitesides, J. Am. Chem. Soc.
1976, 98, 6521.
[19] K. Harms, S. Wocadlo, XCAD4. University of Marburg, Germany
1995.
[20] SHELX: G. M. Sheldrick, Acta Crystallogr. 2008, A64, 112.
[21] WinGX: L. J. Farrugia, Acta Crystallogr. 1999, 32, 837.
[22] A. C. T. North, D. C. Phillips, F. S. Mathews, Acta Crystallogr. 1968,
A24, 351.
[23] PLATON: A. L. Spek, J. Appl. Crystallogr. 2003, 36, 7.
[24] ORTEP-3: L. J. Farrugia, J. Appl. Crystallogr. 1997, 30, 565.
[25] MERCURY: C. F. Macrae, P. R. Edgington, P. McCabe, E. Pidcock,
G. P. Shields,R. Taylor,M. Towler,J. vandeStreek, J.Appl.Crystallogr.
2006, 39, 453.
[26] K. G. Gaw, M. B. Smith, J. W. Steed, J. Organomet. Chem. 2002, 664,
294.
[27] M. R. I. Zubiri, H.I. Milton, A. M. Z. Slawin, J. D. Woollins, Inorg. Chim.
Acta 2004, 357, 1243.
Supporting Information
[28] Z. Fei, R. Scopelliti, P. J. Dyson, Inorg. Chem. 2003, 42, 2125.
[29] A. D. Burrows, M. F. Mahon, M. T. Palmer, J. Chem. Soc., Dalton Trans.
2000, 2, 1669.
[30] M. S. Balakrishna, S. S. Krishnamurthy, R. Murugavel, M. Netaji,
I. I. Mathews, J. Chem. Soc., Dalton Trans. 1993, 477.
[31] W. Keim, H. Maas, J. Organomet. Chem. 1996, 514, 271.
[32] D. Jayasinghe, H.-B. Kraatz, Inorg. Chem. Acta 2006, 359, 3054.
[33] G. R. Newkome, D. W. Evans, F. R. Fronczek, Inorg. Chem. 1987, 26,
3500.
Supporting information can be found in the online version
of this article. CCDC holds the supplementary crystallographic
data 720017 . These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; Fax (+44) 1223-336-033; or email de-
posit@ccdc.cam.ac.uk.
[34] G. K. Anderson, H. C. Clark, J. A. Davias, G. Ferguson, M. Parvez, J.
Crystallogr. Spectrosc. Res. 1982, 12, 449.
Acknowledgment
[35] Z. Fei, R. Scopelliti, P. J. Dyson, Eur. J. Inorg. Chem. 2004, 530.
˙
¨
[36] I. Ozdemir, S. Yas¸ar, S. Demir and B. C¸etinkaya, Heteroatom. Chem.
Partial support from Turkish Academy of Sciences and Dicle
University (project number DUAPK 05-FF-27) is gratefully acknowl-
edged
2005, 16(7), 557.
¨
[37] E. Negishi, Handbook of Organopalladium Chemistry for Organic
Synthesis. John Wiley & Sons: New York, 2002, 1 17.
c
www.interscience.wiley.com/journal/aoc
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2010, 24, 17–24