Synthesis and characterizations of N,N-bis(diphenylphosphino)ethylaniline derivatives and X-ray crystal structure of palladium (II), platinum (II) complexes

Article abstract of DOI:10.1016/j.poly.2007.09.011

N,N-Bis(diphenylphosphino)ethylaniline compounds, [Ph₂P]₂N-C₆H₄-C₂H₅, with ethyl groups at the ortho- and para-positions have been synthesized. Oxidation of the aminophosphines with hydroge

Full text of DOI:10.1016/j.poly.2007.09.011

Available online at www.sciencedirect.com
Polyhedron 27 (2008) 196–202
www.elsevier.com/locate/poly
Synthesis and characterizations
of N,N-bis(diphenylphosphino)ethylaniline derivatives
and X-ray crystal structure of palladium (II),
platinum (II) complexes
a,
a
a
b
*
¨
Feyyaz Durap , Nermin Biricik , Bahattin Gumgum , Saim Ozkar ,
¨
¨
c
c
c
Wee Han Ang , Zhaofu Fei , Rosario Scopelliti
a
Department of Chemistry, University of Dicle, 21280 Diyarbakir, Turkey
b
Department of Chemistry, METU, 06531 Ankara, Turkey
Institut de Sciences et Inge´nierie Chimiques, Ecole Polytechnique Fe´de´rale de Lausanne, CH-1015 Lausanne, Switzerland
c
Received 27 July 2007; accepted 5 September 2007
Available online 5 November 2007
Abstract
N,N-Bis(diphenylphosphino)ethylaniline compounds, [Ph2P]2N-C6H4-C2H5, with ethyl groups at the ortho- and para-positions have
been synthesized. Oxidation of the aminophosphines with hydrogen peroxide, elemental sulfur and selenium gave the corresponding oxi-
des, sulfides and selenides [Ph2P(E)]2N-C6H4-C2H5 (E = O, S, Se). Complexes [MCl2{(Ph2P)2N-C6H4-(C2H5)}] (M = Pd, Pt) and
[Cu{(Ph2P)2N-C6H4-C2H5}2]PF6 were obtained by the reaction of N,N-bis(diphenylphosphino)ethylaniline with [MCl2(COD)]
(M = Pd, Pt) and [Cu(MeCN)4]PF6. The new compounds were characterized by NMR, IR spectroscopy and microanalysis. In addition,
representative solid-state structures of the palladium and platinum complexes were determined using single crystal X-ray diffraction
analyses.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Aminophosphine; Synthesis; Oxidation; Complexation; X-ray structures
1. Introduction
agents, as well as neuroactive agents [7,8]. The synthesis
of bis(diphenylphosphino)alkylaniline is usually achieved
in high yield via the aminolysis of aniline [9,10], which
allows for the incorporation of additional functional
groups such as O and N donors [11,12], or p-donors such
as allyl groups [13]. The presence of the bulky groups
attached to the phosphorus center renders the aminophos-
phine more stable against hydrolysis. The substituents at
the aniline backbone can also play an important role in
determining the outcome of the products [14]. In a recent
study [15], we found that electron-donating groups often
lead to the exclusive formation of aminophosphines
[P(III)–N–P(III)], whereas electron-withdrawing groups,
such as nitrile and trifluoromethyl at the ortho-position
can lead to formation of iminobiphosphine [P(III)–
P(V)@N] species.
The chemistry of aminophosphines containing direct
P–N bonds is one of the most challenging areas in main
group chemistry [1]. Among the numerous aminophos-
phines, bis(diphenylphosphino)alkylaniline derivatives are
particularly interesting due to their relatively high stability
and their ability to chelate transition metals such as palla-
dium, platinum and copper [2,3]. Many aminophosphine
ligands and their complexes have been investigated as
co-catalysts in a number of catalytic processes [4,5]. Some
aminophosphines and derivatives have also found applica-
tion as anticancer drugs [6], herbicides and antimicrobial
*
Corresponding author. Tel.: +90 4122488550; fax: +90 4122488300.
E-mail address: fdurap@dicle.edu.tr (F. Durap).
0277-5387/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.09.011

F. Durap et al. / Polyhedron 27 (2008) 196–202
197
Herein, we describe the synthesis of new N,N-bis(diph-
enylphosphino)ethylaniline with an ethyl group at the
ortho- and para-positions. In order to study their reactivi-
ties, we prepared their corresponding complexes with
selected transition metals (Cu, Pd, Pt), and also the amino-
phosphine oxides, sulfides and selenides. The compounds
were fully characterized using multi-nuclear NMR spectro-
scopic methods and the solid-state structures of two of the
products were established by single crystal X-ray diffrac-
tion analyses.
(ppm): 6.74–7.88 (m, 24H, Ar H), 2.32–2.38 (q, 2H, CH2,
3
3JHH = 7.8 Hz), 0.96–1.00 (t, 3H, CH3, JHH = 7.6 Hz).
31P–{1H} NMR (CDCl3) d (ppm): 24.3 (s). Selected IR, m
(cmꢀ1): 909 (P–N–P), 1213 (PO). Anal. Calc. for
C32H29NP2O2: C, 73.70; H, 5.56; N, 2.68. Found: C,
73.84; H, 5.36; N, 2.59%.
2.2.2. N,N-Bis(diphenylthiophosphino)ethylanilines
[(Ph2P(S))2N-C6H4-C2H5] (1b, 2b)
To
solid
N,N-bis(diphenylphosphino)ethylaniline
(0.20 g, 0.420 mmol) and S8 (0.027 g, 0.840 mmol) was
added THF (20 mL) and this was refluxed for 6 h. The vol-
ume was concentrated in vacuum to ca. 1–2 mL and addi-
tion of n-hexane (20 mL) gave 1b and 2b as white solids
which were collected by suction filtration.
2. Experimental
All reactions were performed under argon unless other-
wise stated. Ph2PCl and the ethyl anilines were purchased
from Fluka and used directly. The starting materials
[MCl2(COD)] (M = Pd, Pt, COD = 1,5-cyclooctadiene)
[16,17] and [Cu(MeCN)4]PF6 [18] were prepared according
to the literature procedures. Solvents were dried using the
appropriate reagents and distilled prior to use. Infrared
spectra were recorded as KBr pellets in the range 4000–
400 cmꢀ1 on a Mattson 1000 ATI UNICAM FT-IR spec-
N,N-Bis(diphenylthiophosphino)-2-ethylaniline
1
(1b):
Yield: 0.117 g, 52%, mp 172–174 °C. H NMR (CDCl3) d
(ppm): 6.85–8.13 (m, 24H, Ar H), 2.43–2.48 (q, 2H, CH2,
3
3JHH = 7.4 Hz), 0.85–0.89 (t, 3H, CH3, JHH = 7.5 Hz).
31P–{1H} NMR (CDCl3) d (ppm): 68.3 (s). Selected IR, m
(cmꢀ1): 862 (P–N–P), 650 (P–S). Anal. Calc. for
C32H29NP2S2: C, 69.44; H, 5.24; N, 2.53; S, 11.57. Found:
C, 69.63; H, 5.18; N, 2.73; S, 11.62%.
1
trometer. H NMR (400.1 MHz) spectra were recorded on
a Bruker AC 400 spectrometer, and 31P–{1H} NMR spec-
tra at 162 MHz with d referenced to external 85% H3PO4.
Microanalysis was carried out on a Fisons EA 1108
CHNS-O instrument.
N,N-Bis(diphenylthiophosphino)-4-ethylaniline
1
(2b):
Yield: 0.132 g, 58%, mp 196–197 °C. H NMR (CDCl3) d
(ppm): 6.68–8.09 (m, 24H, Ar H), 2.32–2.34 (q, 2H, CH2,
3
3JHH = 7.8 Hz), 0.97–1.00 (t, 3H, CH3, JHH = 7.6 Hz).
31P–{1H} NMR (CDCl3) d (ppm): 68.8 (s). Selected IR, m
(cmꢀ1): 882 (P–N–P), 658 (P–S). Anal. Calc. for
C32H29NP2S2: C, 69.44; H, 5.24; N, 2.53; S, 11.57. Found:
C, 69.31; H, 5.30; N, 2.24; S, 11.41%.
2.1. General procedure for the synthesis of
N,N-bis(diphenylphosphino)ethylanilines
2.1.1. [(Ph2P)2N-C6H4-C2H5] (1, 2)
N,N-Bis(diphenylphosphino)ethylanilines were prepared
by the aminolysis reaction of H2N-C6H4-C2H5 (1: 2-C2H5;
2: 4-C2H5) with two equivalents of Ph2PCl according to the
procedure given in the literature [19].
2.2.3. N,N-Bis(diphenylselenophosphino)ethylanilines
[(Ph2P(Se))2N-C6H4-C2H5] (1c, 2c)
To
solid
N,N-bis(diphenylphosphino)ethylaniline
(0.20 g, 0.420 mmol) and grey Se (0.064 g, 0.840 mmol)
was added THF (20 mL) and this was refluxed for 6 h.
The volume was concentrated in vacuum to ca. 1–2 mL
and addition of n-hexane (20 mL) gave 1c and 2c which
were collected by suction filtration.
2.2. General procedure for the synthesis of the chalcogenides
2.2.1. N,N-Bis(diphenyloxophosphino)ethylanilines
[(Ph2P(O))2N-C6H4-C2H5] (1a, 2a)
N,N-Bis(diphenylselenophosphino)-2-ethylaniline (1c):
A THF solution (10 mL) of N,N-bis(diphenylphosphi-
no)ethylaniline (0.20 g, 0.420 mmol) and aqueous H2O2
(30% w/w, 0.083 mL) was stirred for 2 h at room tempera-
ture. The solution was evaporated to dryness under
reduced pressure and the white solids 1a and 2a were
obtained.
1
Yield: 0.155 g, 59%, mp 174–175 °C. H NMR (CDCl3) d
(ppm): 6.87–8.15 (m, 24H, Ar H), 2.38–2.44 (q, 2H, CH2,
3
3JHH = 7.4 Hz), 0.88–0.91 (t, 3H, CH3, JHH = 7.4 Hz).
31P–{1H} NMR (CDCl3) d (ppm): 67.5, J(PSe): 788 Hz.
Selected IR, m (cmꢀ1): 855 (P–N–P), 579 (P–Se). Anal. Calc.
for C32H29NP2Se2: C, 59.35; H, 4.48; N, 2.16. Found: C,
59.34; H, 4.22; N, 2.03%.
N,N-Bis(diphenyloxophosphino)-2-ethylaniline
1
(1a):
Yield: 0.065 g, 25%, mp 180–181 °C. H NMR (CDCl3) d
N,N-Bis(diphenylselenophosphino)-4-ethylaniline (2c):
(ppm): 6.85–7.89 (m, 24H, Ar H), 2.72–2.78 (q, 2H, CH2,
1
3
3JHH = 7.4 Hz), 0.90–0.94 (t, 3H, CH3, JHH = 7.3 Hz).
Yield: 0.176 g, 67%, mp 182–184 °C. H NMR (CDCl3) d
31P–{1H} NMR (CDCl3) d (ppm): 23.6 (s). Selected IR, m
(cmꢀ1): 901 (P–N–P), 1219 (PO). Anal. Calc. for
C32H29NP2O2: C, 73.70; H, 5.56; N, 2.68. Found: C,
73.56; H, 5.47; N, 2.46%.
(ppm): 6.68–8.19 (m, 24H, Ar H), 2.32–2.35 (q, 2H, CH2,
3
3JHH = 7.5 Hz), 0.96–1.00 (t, 3H, CH3, JHH = 7.5 Hz).
31P–{1H} NMR (CDCl3) d (ppm): 69.6, J(PSe): 782 Hz.
Selected IR, m (cmꢀ1): 876 (P–N–P), 565 (P–Se). Anal. Calc.
for C32H29NP2Se2: C, 59.35; H, 4.48; N, 2.16. Found: C,
59.48; H, 4.53; N, 2.07%.
N,N-Bis(diphenyloxophosphino)-4-ethylaniline
1
(2a):
Yield: 0.18 g, 70%, mp 215–217 °C. H NMR (CDCl3) d

198
F. Durap et al. / Polyhedron 27 (2008) 196–202
2.3. General procedure for the synthesis of the complexes
2.3.3. Bis[N,N-bis(diphenylphosphino)ethylaniline]copper
(I) hexafluorophosphates (1f, 2f)
2.3.1. Dichloro{N,N-bis(diphenylphosphino)ethylaniline}-
palladium (II) (1d, 2d)
To a solution of [Cu(MeCN)4]PF6 (0.071 g, 0.191 mmol)
in CH2Cl2 (20 mL) was added N,N-bis(diphenylphosphi-
no)ethylaniline (0.185 g, 0.380 mmol) and the resulting
solution was stirred for 2 h. The volume was concentrated
in vacuum to ca. 1–2 mL and addition of diethyl ether
(20 mL) gave 1f and 2f as white solids which were collected
by suction filtration and dried in vacuum.
A solution of [PdCl2(COD)] (0.049 g, 0.172 mmol)
and N,N-bis(diphenylphosphino) ethylaniline (0.086 g,
0.175 mmol) in CH2Cl2 (10 mL) was stirred for 1.5 h. The
volume was concentrated in vacuum to ca. 1–2 mL and
addition of diethyl ether (20 mL) gave 1d and 2d as yellow
solids which were collected by suction filtration and dried
in vacuum.
Bis[N,N-bis(diphenylphosphino)-2-ethylaniline]copper (I)
hexafluorophosphate (1f ): Yield: 0.183 g, 83%, mp 204–
1
Dichloro{N,N-bis(diphenylphosphino)-2-ethylaniline}-
205 °C. H NMR (CDCl3) d (ppm): 6.87–8.15 (m, 24H,
1
3
palladium (II) (1d): Yield: 0.094 g, 85%, mp >300 °C. H
Ar H), 1.21–1.27 (q, 2H, CH2, JHH = 7.6 Hz), 0.02–0.05
3
NMR (CDCl3) d (ppm): 6.57–7.94 (m, 24H, Ar H), 1.38–
(t, 3H, CH3, JHH = 7.5 Hz). 31P–{1H} NMR (CDCl3) d
3
1.41 (q, 2H, CH2, JHH = 7.4 Hz), 0.91–0.95 (t, 3H, CH3,
(ppm): 87.7 (s), d(PF6): ꢀ144.3(m); J(PF6): 1418 Hz. Selected
IR, m (cmꢀ1): 843 (P–N–P). Anal. Calc. for C64H58N2-
P5F6Cu: C, 64.73; H, 4.89; N, 2.36. Found: C, 64.69; H,
5.02; N, 2.21%.
3JHH = 7.5 Hz). 31P–{1H} NMR (CDCl3) d (ppm): 37.2
(s). Selected IR, m (cmꢀ1): 900 (P–N–P). Anal. Calc. for
C32H29NP2PdCl2: C, 60.86; H, 4.59; N, 2.22. Found: C,
60.77; H, 4.39; N, 2.05%.
Bis[N,N-bis(diphenylphosphino)-4-ethylaniline]copper (I)
hexafluorophosphate (2f ): Yield: 0.20 g, 91%, mp 339–
Dichloro{N,N-bis(diphenylphosphino)-4-ethylaniline}-
1
1
palladium (II) (2d): Yield: 0.10 g, 97%, mp >300 °C. H
340 °C. H NMR (CDCl3) d (ppm): 6.68–8.19 (m, 24H,
3
NMR (CDCl3) d (ppm): 6.43–7.92 (m, 24H, Ar H); 2.52–
Ar H), 2.45–2.51 (q, 2H, CH2, JHH = 7.6 Hz), 1.08–1.12
3
3
2.54 (q, 2H, CH2, JHH = 7.5 Hz), 1.15–1.18 (t, 3H, CH3,
(t, 3H, CH3, JHH = 7.6 Hz). 31P–{1H} NMR (CDCl3) d
3JHH = 7.5 Hz). 31P–{1H} NMR (CDCl3) d (ppm): 34.8
(s). Selected IR, m (cmꢀ1): 913 (P–N–P). Anal. Calc. for
C32H29NP2PdCl2: C, 60.86; H, 4.59; N, 2.22. Found: C,
60.66; H, 4.38; N, 2.33%. Slow diffusion of diethyl ether
into a CH2Cl2 solution of 2d over 48 h gave crystals suit-
able for X-ray diffraction.
(ppm): 88.2 (s), d(PF ): ꢀ144.3(m); J(PF ): 1424 Hz. Selected
6
6
IR, m (cmꢀ1): 848 (P–N–P). Anal. Calc. for C64H58N2P5-
F6Cu: C, 64.73; H, 4.89; N, 2.36. Found: C, 64.79; H,
4.95; N, 2.41%.
2.3.4. Structure determination in the solid state
Data collection for 1e and 2d was performed on an
Oxford-Kuma Xcalibur diffractor with a Sapphire CCD
area detector at 140(2) K and data reduction was per-
formed using CrysAlis RED [20]. The structures were solved
by direct methods using SIR-92 [21], and refined by full-
matrix least-squares refinement (against F2) using SHELXTL
[22,23], with all non-hydrogen atoms refined anisotropi-
cally. The hydrogen atoms were placed in their geometri-
cally generated positions and treated as riding on their
parent atoms with Uiso(H) = 1.2Ueq(C), except for the ter-
minal H-atoms on C8 where Uiso(H) = 1.5Ueq(C). Empiri-
cal absorption corrections were applied using DELABS [24].
Relevant crystallographic data are compiled in Table 1
and graphical representations of the structures were made
with DIAMOND [25].
2.3.2. Dichloro{N,N-bis(diphenylphosphino)ethylaniline}-
platinum (II) (1e, 2e)
A solution of [PtCl2(COD)] (0.034 g, 0.0860 mmol) and
N,N-bis(diphenylphosphino)ethylaniline (0.0427 g, 0.0875
mmol) in CH2Cl2 (10 mL) was stirred for 1.5 h. The
volume was concentrated in vacuum to ca. 1–2 mL and
addition of diethyl ether (20 mL) gave 1e and 2e as white
solids which were collected by suction filtration and dried
in vacuum.
Dichloro{N,N-bis(diphenylphosphino)-2-ethylaniline}-
platinum (II) (1e): Yield: 0.056 g, 86%, mp 339–341 °C.
1H NMR (CDCl3) d (ppm): 6.48–7.93 (m, 24H, Ar H),
3
1.21–1.25 (q, 2H, CH2, JHH = 7.1 Hz), 0.23–0.27 (t, 3H,
3
CH3, JHH = 7.2 Hz). 31P–{1H} NMR (CDCl3) d (ppm):
22.3, J(PtP): 3348.6 Hz. Selected IR, m (cmꢀ1): 900 (P–N–
P). Anal. Calc. for C32H29NP2PtCl2: C, 50.86; H, 3.84; N,
1.85. Found: C, 50.84; H, 3.63; N, 1.67%. Slow diffusion
of diethyl ether into a CHCl3 solution of 1e over 48 h gave
crystals suitable for X-ray crystallography.
3. Results and discussion
N,N-Bis(diphenylphosphino)ethylanilines, (Ph2P)2N-C6H4-
C2H5 (1: 2-C2H5; 2: 4-C2H5) were prepared from H2-
N-C6H4-C2H5 and Ph2PCl by aminolysis in CH2Cl2 in
accordance with our previous reports [19] (Scheme 1).
The reaction was monitored by 31P–{1H} NMR spec-
troscopy. In contrast to reactions of diphenylphosphorus
chloride (Ph2PCl) with anilines bearing electron-withdraw-
ing groups [15], the reaction mixture of Ph2PCl with 2-ethy-
laniline or 4-ethylaniline gave a single resonance at d(P)
61.6 ppm for 1 and 68.5 ppm for 2, and no formation of
Dichloro{N,N-bis(diphenylphosphino)-4-ethylaniline}-
platinum (II) (2e): Yield: 0.057 g, 88%, mp 339–340 °C.
1H NMR (CDCl3) d (ppm): 6.36–7.90 (m, 24H, Ar H),
3
2.51–2.56 (q, 2H, CH2, JHH = 7.5 Hz), 1.14–1.17 (t, 3H,
3
CH3, JHH = 7.5 Hz). 31P–{1H} NMR (CDCl3) d (ppm):
20.6, J(PtP): 3324 Hz. Selected IR, m (cmꢀ1): 906 (P–N–P).
Anal. Calc. for C32H29NP2PtCl2: C, 50.86; H, 3.84; N,
1.85. Found: C, 50.71; H, 3.78; N, 1.76%.

F. Durap et al. / Polyhedron 27 (2008) 196–202
199
Table 1
Crystallographic data for compounds 1e Æ CHCl3 and 2d Æ CH2Cl2
E
E
Ph2P
PPh2
Ph2P
PPh2
N
Compound
1e Æ CHCl3
2d Æ CH2Cl2
N
Chemical
formula
Formula weight 874.86
C32H29Cl3NP2Pt Æ CHCl3 C32H29Cl3NP2Pd Æ CH2Cl2
THF
C2H5
+
2E
C2H5
751.73
monoclinic
P21/n
Crystal system
Space group
monoclinic
P21/c
Scheme 2. Oxidation of (Ph2P)2N-C6H4-C2H5 with aqueous H2O2
(1a, 2a), elemental sulfur (1b, 2b) and powder selenium (1c, 2c).
˚
a (A)
11.9722(6)
14.6887(4)
19.9617(10)
90
10.2901(10)
14.8786(15)
21.665(2)
90
˚
b (A)
˚
c (A)
68.8 ppm) and 1c, 2c (67.5 ppm and 69.6 ppm). The
composition of the oxidized derivatives 1a, 2a, 1b, 2b, 1c
and 2c were further confirmed by using microanalysis
and IR spectroscopy, and were found to be in good agree-
ment with the theoretical values [12,13,15].
Reactions of compounds 1 and 2 with [M(COD)Cl2]
(M = Pd, Pt; COD = 1,5-cyclooctadiene) and [Cu(CH3-
CN)4]PF6 in CH2C12 gave the corresponding complexes
1d, 2d, 1e, 2e [M{(Ph2P)2N-C6H4-C2H5}Cl2] (M = Pd; Pt)
and 1f, 2f [Cu{(Ph2P)2N-C6H4-C2H5}2]PF6 in good yields
(Scheme 3).
a (°)
b (°)
c (°)
106.536(5)
90
98.332(9)
90
3
˚
Volume (A )
3365.2(3)
4
3282.0(6)
4
Z
Dcalc (g cmꢀ3
F(000)
)
1.727
1.521
1712
1520
l (mmꢀ1
)
4.687
1.013
Temperature (K) 140(2)
140(2)
0.71073
19146
˚
Wavelength (A)
Measured
reflections
Unique
reflections
Unique
reflections
[I > 2r(I)]
Number of data/ 5737/0/380
restraints/
0.71073
19557
The 31P NMR chemical shifts of complexes 1d and 2d
(37.2 ppm and 34.8 ppm) are within the range expected
for structurally similar complexes where an electron-with-
drawing group is attached to the aniline ring [27]. The
chemical shifts of 1e, 2e, 1f and 2f in the 31P NMR spectra
are also within the expected range and they show minor
5737
4218
5489
1781
5489/192/371
parameters
1
solvent dependence [13]. In the H NMR spectra, these
Ra [I > 2r(I)]
wRa2 (all data)
Goodness-of-fit
(GOF)b
0.0264
0.0547
0.891
0.0480
0.1051
0.677
complexes display overlapped multiplets in the region
6.70–8.10 ppm for the aromatic H-atoms, and a quartet
at 2.50 ppm and a triplet at 1.15 ppm for the hydrogen
atoms of the ethyl group.
Single crystals of 1e and 2d suitable for X-ray diffraction
analyses were obtained by slow diffusion of diethyl ether
into a solution of the complexes in chloroform and dichlo-
romethane, respectively. They both crystallized as 1:1 sol-
vent adducts and the crystallographic data of 1e Æ CHCl3
and 2d Æ CH2Cl2 are listed in Table 1.
The molecular representation of complexes 1e and 2d
are shown in Figs. 1 and 2, with key bond parameters given
in the figure captions. In general, the key bond lengths and
angles of complexes 1e and 2d in the solid state are very
similar, with minimal structural differences due to the relo-
cation of the ethyl groups. The P–N bond distances of
P
P
P
P
a
R = iFoj ꢀ jFci/ jFoj, wR2 = { [w(F2o ꢀ Fc2)2]/ [w(Fo2)2]}1/2
.
P
b
GOF = { [w(F2o ꢀ F2c)2]/(n ꢀ p)}1/2 where n is the number of data and
p is the number of parameters refined.
C2H5
C2H5
Et3N/CH2Cl2
2Et3NHCl
+
2Ph2PCl
+
0 oC
N
NH2
Ph2P
PPh2
Scheme 1. Syntheses of N,N-bis(diphenylphosphino)ethylanilines by the
aminolysis reaction of H2N-C6H4-C2H5with Ph2PCl (1: 2-C2H5; 2:
4-C2H5).
˚
iminobiphosphine species (Ph2P–PPh2@NC6H4(C2H5))
could be observed. The 31P–{1H} NMR signal of com-
pound 1 is shifted upfield compared to that of 2, although
they both lie in the expected region of 60–70 ppm [26]. The
compounds are air-stable solids but gradually undergo
decomposition on exposure to moisture.
Oxidation of 1 and 2 with aqueous hydrogen peroxide,
elemental sulfur and selenium gave the corresponding oxi-
des 1a, 2a, sulfides 1b, 2b and selenides 1c, 2c (Scheme 2).
The 31P NMR spectrum of 1a and 2a displays one singlet
at 23.6 ppm and 24.3 ppm, respectively, suggesting the
two phosphorus atoms are chemically equivalent in both
compounds. Similarly, singlet resonances were also found
in the 31P NMR spectra of 1b and 2b (68.3 ppm and
1.734(7) and 1.738(6) A in complex 2d are essentially the
same, but they are longer than that of the platinum com-
˚
plex 1e [1.715(4) and 1.719(4) A], although they are within
the expected value range on comparison to similar struc-
tures [27]. Both complexes form metallacycles, i.e. P–N–
P–Pd and P–N–P–Pt, respectively, that are nearly planar
with torsion angles P–N–P–Pd of 0.5(4)° in 2d and P–N–
P–Pt of 5.78(17)° in 1e. Despite the difference of the two
metal atoms, the P–Pd–P angle in 2d [72.30(9)°] is not
too different from that of the P–Pt–P angle in 1e [72.80(4)°].
It is interesting to note that compounds 1e and 2d crys-
tallised under similar conditions, both forming 1:1 adducts
with solvent molecules, presumably driven by H-bonding
interactions with the solvent molecules. In both instances,

200
F. Durap et al. / Polyhedron 27 (2008) 196–202
Ph
P
C2H5
Ph
Cl
Cl
M
N
P
(I)
Ph
Ph
C2H5
M= Pd 1d, 2d; Pt 1e, 2e
PPh2
PPh2
N
(II)
C2H5
Ph
P
Ph
P
Ph
Ph
Ph
Cu
N
N
PF6
P
P
Ph
C2H5
Ph
Ph
1f, 2f
MCl2(COD), CH2Cl2
[Cu(CH3CN)4]PF6 , CH2Cl2
(II)
,
(I)
Scheme 3. Reactions of aminophosphines 1 and 2 with [M(COD)Cl2] (M = Pd, Pt) and [Cu(CH3CN)4]PF6 in CH2C12.
˚
Fig. 1. Solid-state structure of compound 2d; selected bond lengths (A)
and angles (°): Pd(1)–P(1), 2.212(3), Pd(1)–P(2), 2.215(3), Pd(1)–Cl(1),
2.373(2), Pd(1)–Cl(2), 2.379(3), N(1)–C(1), 1.419(11), N(1)–P(2), 1.734(7),
N(1)–P(1), 1.738(6); P(1)–Pd(1)–P(2), 72.30(9), P(1)–Pd(1)–Cl(1), 95.18(9),
P(2)–Pd(1)–Cl(1), 167.18(10), P(1)–Pd(1)–Cl(2), 165.81(9), P(2)–Pd(1)–
Cl(2), 94.28(9), Cl(1)–Pd(1)–Cl(2), 98.41(9), C(1)–N(1)–P(2), 132.8(6),
C(1)–N(1)–P(1), 129.5(6), P(2)–N(1)–P(1), 97.6(4).
˚
Fig. 2. Solid-state structure of compound 1e; selected bond lengths (A)
and angles (°): Pt(1)–P(1), 2.2096(12), Pt(1)–P(2), 2.2151(12), Pt(1)–Cl(2),
2.3592(12), Pt(1)–Cl(1), 2.3633(12), N(1)–C(1), 1.449(5)N(1)–P(1),
1.715(4), N(1)–P(2), 1.719(4), P(1)–Pt(1)–P(2), 72.80(4), P(1)–Pt(1)–Cl(2),
171.69(5), P(2)–Pt(1)–Cl(2), 98.97(4), P(1)–Pt(1)–Cl(1), 97.54(5), P(2)–
Pt(1)–P(1), 169.93(4), Cl(2)–Pt(1)–Cl(1), 90.74(4), C(1)–N(1)–P(1),
132.7(3), C(1)–N(1)–P(2), 126.9(3), P(1)–N(1)–P(2), 99.72(18).
the solvent molecule interacts via C–H bonds directly with
the metal chloride bonds, the C–Hꢁ ꢁ ꢁCl(Pd) distance in 2d
they exhibit similar reactivities towards different oxidants
due to the presence of the bulky diphenyl groups at the
phosphorus atom. In addition, they also show similar coor-
dination properties towards Pd, Pt and Cu. All these new
compounds were characterized using NMR and IR spec-
troscopy, with two representative structures studied by sin-
gle crystal X-ray diffraction analyses. Investigations of
these compounds as potential catalysts are ongoing and
will be reported separately.
˚
and C–Hꢁ ꢁ ꢁCl(Pt) distance in 1e being 2.589 and 2.471 A,
respectively. In addition, the chloride of the solvent mole-
cules also interacts with the C–H bonds of the aromatic
benzene ring, and the C–Hꢁ ꢁ ꢁCl values range from 2.80
˚
to 2.90 A (see Fig. 3).
4. Conclusion
In conclusion, we have prepared a series of aminophos-
phine compounds and their derivatives including oxides,
sulfides, selenides, as well as transition-metal complexes
containing Pd, Pt and Cu centers. Although the positions
of the ethyl groups in the aniline substituent are different,
5. Supplementary material
CCDC 643157 and 643158 contain the supplementary
crystallographic data for this paper. These data can be

F. Durap et al. / Polyhedron 27 (2008) 196–202
201
Fig. 3. Hydrogen bonding interactions in 2d (left) and 1e (right).
(b) P. Bhattacharyya, T.Q. Ly, A.M.Z. Slawin, J.D. Woollins,
Polyhedron 20 (2001) 1803.
[8] P. Kafarski, P. Mastalerz, Beitr. Wriskstorfforch 21 (1984).
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(b) Z. Fei, R. Scopelliti, Paul J. Dyson, Eur. J. Inorg. Chem. (2004)
530;
obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit@
ccdc.cam.ac.uk.
(c) N. Biricik, Z. Fei, R. Scopelliti, P.J. Dyson, Eur. J. Inorg. Chem.
(2004) 4232;
Acknowledgments
´
(d) I. Fernandez, F. Breher, P.S. Pregosin, Z. Fei, P.J. Dyson, Inorg.
Chem. 44 (2005) 7616.
We thank The Council of Dicle University (DUAPK-
05-FF-19 and DUAPK-06-FF-41 projects) for financial
[10] K.G. Gaw, M.B. Smith, A.M.Z. Slawin, New J. Chem. 24 (2000) 429.
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Inorg. Chem. 7 (2002) 1635;
´ ´
support and Ecole Polytechnique Federale de Lausanne
for X-ray structure analyses.
(b) M.L. Clarke, G.L. Holliday, A.M.Z. Slawin, J.D. Woollins, J.
Chem. Soc., Dalton Trans. 6 (2002) 1093;
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