Preparation and coordination chemistry of Ph2P(CH2)nNHPiPr2 (n = 2, 3)

Article abstract of DOI:10.1016/S0277-5387(02)01236-6

Unsymmetrical diphosphine ligands of the type Ph₂P(CH₂)nNHPPr₂ⁱ [n = 2 (1), 3 (2)] have been obtained by reacting the appropriate (diphenylphosphino)alkylamine, Ph₂P(CH₂)_n NH₂ with chlorodi-iso-propylphosphine, in the presence of triethylamine. Reaction of Ph₂P(CH₂)₂NHPPr₂ⁱ with PdCl₂(PhCN)₂, PtCl₂(PhCN)₂, PtMe₂(cod) and PtClMe(cod), NiCl₂ · 6H₂O and Fe(CO)₂(η⁵- C₅H₅)I gives the corresponding chelate complexes, PdCl₂L, PtX₂L, NiCl₂L and Fe(CO)(η⁵-C₅H₅)L. Reaction of Ph₂P(CH₂)₃NHPPr₂ⁱ with PtCl₂(PhCN)₂, PtMe₂(cod) and PdCl₂(PhCN)₂ yields the chelate complexes and reaction with PtClMe(cod) led to a 50:50 mixture of chelate isomers.

Full text of DOI:10.1016/S0277-5387(02)01236-6

Polyhedron 21 (2002) 2639Á2645
/
www.elsevier.com/locate/poly
Preparation and coordination chemistry of Ph2P(CH2)nNHPiPr2
(nꢀ2, 3)
/
Tracey Appleby, Stephen M. Aucott, Matthew L. Clarke, Alexandra M.Z. Slawin,
J. Derek Woollins *
School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, UK
Received 15 July 2002; accepted 9 September 2002
Abstract
Unsymmetrical diphosphine ligands of the type Ph2P(CH2)nNHPPri2 [nꢀ
appropriate (diphenylphosphino)alkylamine, Ph2P(CH2)nNH2 with chlorodi-iso-propylphosphine, in the presence of triethylamine.
/2 (1), 3 (2)] have been obtained by reacting the
Reaction of Ph2P(CH2)2NHPPri2 with PdCl2(PhCN)2, PtCl2(PhCN)2, PtMe2(cod) and PtClMe(cod), NiCl2×6H2O and Fe(CO)2(h5-
/
C5H5)I gives the corresponding chelate complexes, PdCl2L, PtX2L, NiCl2L and Fe(CO)(h5-C5H5)L. Reaction of
Ph2P(CH2)3NHPPr2i with PtCl2(PhCN)2, PtMe2(cod) and PdCl2(PhCN)2 yields the chelate complexes and reaction with
PtClMe(cod) led to a 50:50 mixture of chelate isomers.
# 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Ph2P(CH2)n NHPi Pr2; Diphosphine ligands; Chelate complexes
1. Introduction
H4PPh2 [7] with h6-aryl Ru(II), Os(II) and Cp* Rh(III),
Ir(III) chloride-bridged dimers leads to mono-metallic,
monodentate species where the ligand coordinates via
the amino-phosphine. Or cationic chelate complexes.
This hemilabile nature of unsymmetrical phosphines has
also been further illustrated [8] using Ph2PCH2NHC6-
H4PPh2.
Diphosphine ligands have been widely used through-
out organometallic and inorganic chemistry, and are
particularly important in homogeneous catalysis. Di-
phosphines in which the two phosphorus atoms are
linked by a carbon chain and have the same substituents
on each phosphorus such as bis-(diphenylphosphi-
no)ethane (dppe) and bis-(diphenylphosphino)methane
(dppm) have been extensively studied. Recently, there
has been an increased interest in diphosphines with a
hetero atom or bridge linking the two phosphorus
atoms. However, in comparison to dppe, dppm and
hetero-atom bridged diphosphines, unsymmetrical di-
The palladium [9] catalyst Pd(dippp)2 [dipppꢀ1,3-
/
bis(di-isopropylphosphino)propane] is an efficient cata-
lyst for direct formylation of aryl chlorides to aldehydes.
More recently the catalytic activity of palladium
dichloride complexes [10] with 1,3-bis(dialkylphosphi-
no)propane chelating ligands, PdCl2(R2PCH2CH2-
CH2PR2), and the cationic derivatives of these com-
phosphines have received relatively little attention [1Á6].
/
plexes,
[(NCCH3)2Pd(R2PCH2CH2CH2PR2)][BF4]2,
Unsymmetrical diphosphines represent an interesting
series of compounds because the difference in basicity or
steric properties of the two phosphorus atoms could be
exploited to obtain different coordination modes, i.e.
bidentate versus monodentate. For example, it has
already been reported that the reaction of Ph2PNHC6-
have been investigated for alkene/CO copolymerisation
reactions. All of these diphosphine catalysts have a three
carbon chain linking the two phosphorus atoms and
have either phenyl or isopropyl groups bonded to the
trivalent phosphorus. With this in mind and the lack of
reports on the synthesis and coordination of unsymme-
trical diphosphines of the type Pꢀ
/
Cꢀ
/
Cꢀ
/
Nꢀ
/
P we set
about synthesising the ligands Ph2PCH2CH2NHPPr2i
and Ph2P(CH2)3NHPPri2 .
* Corresponding author. Tel.: ꢁ
463-384
E-mail address: jdw3@st-and.ac.uk (J. Derek Woollins).
/
44-1334-463-861; fax: ꢁ44-1334-
/
0277-5387/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 1 2 3 6 - 6

2640
T. Appleby et al. / Polyhedron 21 (2002) 2639Á2645
/
2. Experimental
to form. The solvent was removed in vacuo until about 2
cm3 remained. Diethyl ether was added dropwise to fully
precipitate the cream solid which was collected by
suction filtration. Yield: 0.093 g, 54%. Anal. Found
(Calc. for C20H29Cl2NP2Pd): C, 45.67 (45.95); H, 5.51
2.1. General
Unless otherwise stated, all reactions were carried out
under an oxygen-free nitrogen atmosphere using stan-
dard Schlenk techniques. Diethyl ether and thf were
purified by reflux over sodium-benzophenone and dis-
tillation under nitrogen. Dichloromethane and MeCN
were heated to reflux over CaH2 and distilled under
nitrogen. ClPiPr2 was from Aldrich. 2-(Diphenylpho-
sphino)ethylamine [11] and 3-(diphenylphosphino)-1-
(5.59); N, 2.65 (2.68)%. 31P{H}NMR (CDCl3): d(PA)
2
20.9(d) ppm; d(PX) 90.3(d) ppm, J(31PÁ31
/
P)ꢀ
/
7 Hz.
MS: m/z 545 [Mꢁ
/
Na]ꢁ, 487 [Mꢂ
/
Cl]ꢁ. IR (KBr):
3244s (nNH), 3072w, 1638w, 287m, 217s cmꢂ1
.
2.1.4. PtCl2(Ph2PCH2CH2NHPPri2 ) (4)
Ph2PCH2CH2NHPPri2 (1) (0.079 g, 0.22 mmol) and
PtCl2(PhCN)2 (0.108 g, 0.22 mmol) were stirred in
CH2Cl2 (10 cm3) for 20 min. The solvent was removed
in vacuo until product just started to precipitate; ether
(10 cm3) was added dropwise to aid precipitation. The
cream solid was collected by suction filtration. Yield:
0.105 g, 75%. Anal. Found (Calc. for C20H29Cl2NP2Pt):
propylamine [12], MCl2(PhCN)2 (Mꢀ
PtMeX(cod) (XꢀMe, Cl) [14] were prepared according
to literature methods. IR spectra were recorded as either
KBr discs or solutions in the range 4000Á
200 cmꢂ1 on a
PerkinÁElmer 2000 FT spectrometer. NMR spectra
/
Pt, Pd) [13] and
/
/
/
were recorded on a Gemini 2000 spectrometer (operat-
ing at 121.4 MHz for 31P and 300 MHz for 1H).
Microanalyses were performed by the St. Andrews
University service and EI/FAB mass spectra by the
Swansea Mass Spectrometer Service.
C, 39.60 (39.29); H, 4.53 (4.78); N, 2.25 (2.29)%. 31P{H}
1
NMR (CDCl3): d(PA) ꢂ
/
1.4(d) ppm, J(195PtÁ31
/
PA)ꢀ
3595 Hz,
Cl]ꢁ. IR
/
3584 Hz; d(PX) 57.8(d) ppm, J(195PtÁ31
/
P)ꢀ
/
1
2J(31PAÁ31
/
PX)ꢀ
/
17 Hz. MS: m/z 576 [Mꢂ
/
(KBr): 3273s (nNH), 3027w, 303w, 278w cmꢂ1
.
2.1.1. Ph2PCH2CH2NHPPri2 (1)
Chlorodiisopropyl phosphine (1.04 cm3, 0.998 g, 6.54
mmol) was added dropwise over a period of 20 min to a
stirred solution of Ph2PCH2CH2NH2 (1.5 g, 6.54 mmol)
and Et3N (1.09 cm3, 0.794 g, 7.85 mmol) in Et2O (50
cm3). The mixture was stirred at room temperature (r.t.)
for 1 h. The white precipitate (triethylamine hydrogen
chloride) was filtered off and the solvent removed in
vacuo to produce a clear, viscous liquid. Yield: 2.03 g,
2.1.5. PtMe2(Ph2PCH2CH2NHPPri2 ) (5)
Ph2PCH2CH2NH2 (1) (0.117 g, 0.34 mmol) and
PtMe2(cod) (0.113 g, 0.34 mmol) were stirred in
CH2Cl2 (10 cm3) for 20 min. The solvent was removed
in vacuo until a white solid started to precipitate; then
Et2O was added dropwise to aid precipitation. The solid
was collected by suction filtration. Yield: 0.061 g, 32%.
Anal. Found (Calc. for C22H35NP2Pt): C, 46.06 (46.36);
H, 6.03 (6.18); N, 2.30 (2.45)%. 31P{H} NMR (CDCl3):
90%. 31P{H} NMR (CDCl3): d(PA) ꢂ
/
20.2(s) ppm;
7.45
d(PX) 66.0(s) ppm. 1H NMR (CDCl3): d 7.56Á
/
d(PA) 7.1(d) ppm, 1J(195PtÁ31
68.3(d) ppm,
1J(195PtÁ31
2J(31PAÁ31 22 Hz. 1H NMR (CDCl3): d 7.69Á
PX)ꢀ
7.39 (m, 10H, aromatics), 3.20 (m, 2H, CH2), 2.35 (m,
2H, CH2), 2.19 (m, 2H, CH2), 1.29Á1.03 (m, 12H, CH3),
0.78Á0.67 (m, 6H, CH3) ppm. MS: m/z 555 [Mꢂ
Me]ꢁ.
IR (KBr): 3384s (nNH), 3070w, 2959s, 2864s, 1589w,
1098s cmꢂ1
/
PA)ꢀ/1849 Hz; d(PX)
(m, 10H, aromatics), 3.23 (m, 2H, CH2), 2.41 (m, 2H,
CH2), 1.30 (m, 1H, NH), 1.34 (m, 2H, CH), 1.15 (m,
12H, CH3) ppm. MS: m/z 345 [Mꢁ].
/
PX)ꢀ/1990 Hz,
/
/
/
/
2.1.2. Ph2PCH2CH2CH2NHPPri (2)
/
/
Chlorodiisopropyl phosphine (1.01 cm3, 0.971 g, 6.37
mmol) was added dropwise over a period of 20 min to a
stirred solution of Ph2PCH2CH2CH3NH2 (1.548 g, 6.36
mmol) and Et3N (1.01 cm3, 0.773 g, 7.59 mmol) in Et2O
(50 cm3). The mixture was stirred at r.t. for 1 h. The
white precipitate (triethylamine hydrogen chloride) was
filtered off and the solvent removed in vacuo to produce
.
2.1.6. PtClMe(Ph2PCH2CH2NHPPri2 ) (6)
Ph2PCH2CH2NH2 (1) (0.113 g, 0.33 mmol) and
PtClMe(cod) (0.116 g, 0.33 mmol) were stirred in
CH2Cl2 (10 cm3) for 20 min. The solvent was removed
in vacuo until a white solid started to precipitate.
Diethyl ether was added dropwise to aid precipitation.
The solid was collected by suction filtration. Yield: 0.141
g, 73%. Anal. Found (Calc. for C21H32ClNP2Pt): C,
42.31 (42.68); H, 5.53 (5.46); N, 2.09 (2.37)%. 31P{H}
a white solid. Yield: 1.359 g, 60%. 31P{H} NMR
(CDCl3): d(PA) ꢂ
NMR (CDCl3): d 7.52Á
(m, 2H, CH2), 2.17 (m, 2H, CH2), 1.67 (m, 2H, CH2),
1.10 (m, 12H, CH3) ppm.
1
14.7(s) ppm; d(PX) 66.9(s) ppm. H
/
/
7.43 (m, 10H, aromatics), 3.13
NMR (CDCl3): d(PA) 6.4(d) ppm, 1J(195PtÁ31
1879 Hz; d(PX) 63.8(d) ppm, 1J(195PtÁ31
PX)ꢀ
Hz, 2J(31PAÁ31 18 Hz. 1H NMR (CDCl3): d
PX)ꢀ
7.85Á7.38 (m, 10H, aromatics), 3.45 (m, 2H, CH2),
2.25 (m, 2H, CH2), 1.38 (m, 2H, CH), 1.2 (m, 12H,
/
PA)ꢀ
/
2.1.3. PdCl2(Ph2PCH2CH2NHPPri2 ) (3)
Ph2PCH2CH2NH2 (1) (0.113 g, 0.327 mmol) and
PdCl2(PhCN)2 (0.125 g, 0.327 mmol) were stirred in
CH2Cl2 (10 cm3) for 20 min. A cream precipitate started
/
/
4626
/
/
/

T. Appleby et al. / Polyhedron 21 (2002) 2639Á
/
2645
2641
CH3), 0.76 (m, 3H, CH3) ppm. MS: m/z 555 [Mꢂ
IR (KBr): 3277s (nNH), 3052w, 2962s, 2867s, 1435s,
1100s, 274w cmꢂ1
/
Cl]ꢁ.
g, 92%. Anal. Found (Calc. for C21H31Cl2NP2Pt): C,
40.24 (40.41); H, 4.42 (5.01); N, 2.58 (2.24)%. MS: m/z
.
590 [Mꢂ
/
Cl]ꢁ, 552 [Mꢂ2Cl]ꢁ. IR (KBr): 3330s (nNH),
/
3053w, 1700w, 1653w, 304m, 297, 282 n(Mꢀ
/
Cl) cmꢂ1
.
2.1.7. Fe(CO)(h5-C5H5)(Ph2PCH2CH2NHPPri2 )I
(7)
Ph2PCH2CH2NHPr2 (1) (0.114 g, 0.33 mmol),
Fe(CO)2(h5-C5H5)I (0.091 g, 0.30 mmol) and catalyst
Fe(CO)2(h5-C5H5) (0.010 g, 0.057 mmol) were refluxed
in MeCN (15 cm3). Reaction followed by IR to
completion. The reaction mixture was allowed to cool
to r.t., before the solvent was removed in vacuo,
producing a green precipitate. The precipitate was re-
2.1.11. PtMe2[Ph2P(CH2)3NHPPri2 ] (11)
Ph2P(CH2)3NHPPri2 (2) (0.105 g, 0.29 mmol) and
PtMe2(cod) (0.097 g, 0.29 mmol) were stirred at r.t. in
CH2Cl2 (10 cm3) for 60 min. Solvent was removed in
vacuo until precipitate started to form. Diethyl ether
was added to aid precipitation. White solid was collected
by suction filtration. Yield: 0.122 g, 71%. Anal. Found
(Calc. for C23H37NP2Pt): C, 47.05 (47.29); H, 6.12
(6.38); N, 2.48 (2.4)%. 31P{H} NMR (CDCl3): d(PA)
dissolved in CH2Cl2 and precipitated with 60Á80 pet
/
ether. The solid was collected by suction filtration.
Yield: 0.107 g, 57%. Anal. Found (Calc. for C26H34FeI-
NOP2): C, 50.59 (50.27); H, 5.65 (5.52); N, 2.30 (2.25)%.
31P{H} NMR (CDCl3): d(PA) 53.0(d) ppm; d(PX)
7.3 ppm, 1J(195PtÁ31
1J(195PtÁ31 2164 Hz, J(31PAÁ31
PX)ꢀ
NMR (CDCl3): d 7.83Á7.46 (m, 10H, aromatics), 3.31Á
3.22 (m, 2H, CH2), 2.88Á2.75 (m, 2H, CH2), 2.41Á2.26
(m, 2H, CH2), 1.65Á1.52 (m, 2H, CH), 1.35Á1.24 (m,
12H, CH3), 0.77Á0.48 (m, 3H, CH3), 0.37Á0.08 (m, 3H,
CH3) ppm. MS: m/z 584 [M]ꢁ, 569 [MꢂMe]ꢁ, 554
[Mꢂ
2Me]ꢁ. IR (KBr): 3377s (nNH), 3073w, 1434s.
/
PA)ꢀ
/
1823 Hz; d(PX) 94.4 ppm,
2
1
/
/
/
PX)ꢀ15 Hz. H
/
/
/
119.8(d) ppm, 2J(31PAÁ31
(CDCl3): d 7.96Á7.37 (m, 10H, aromatics), 4.99 (m,
5H, Cp), 3.57 (m, 2H, CH2), 2.73 (m, 2H, CH2), 2.27 (m,
/
PX)ꢀ
/
67 Hz. 1H NMR
/
/
/
/
/
/
/
2H, CH), 1.50Á
/
1.21 (m, 12H, CH3) ppm. MS: m/z 494
[Mꢁ]. IR (KBr): 3179m (nNH), 3048m, 1954s.
/
/
2.1.8. NiCl2(Ph2PCH2CH2NHPPri2 ) (8)
Ph2PCH2CH2NHPr2 (1) (0.273 g, 0.79 mmol) and
2.1.12. PtMeCl[Ph2P(CH2)3NHPPri2 ] (12)
NiCl2×
/
6H2O (0.188 g, 0.79 mmol) were stirred in thf (10
Ph2P(CH2)3NHPPri2 (2) (0.126 g, 0.49 mmol) and
PtMeCl(cod) (0.124 g, 0.49 mmol) were stirred at r.t. in
CH2Cl2 (10 cm3) for 60 min. Solvent was removed in
vacuo until a precipitate started to form. Diethyl ether
was added dropwise to fully precipitate solid. The white
solid was collected by suction filtration. Yield: 0.155 g,
73%. Anal. Found (Calc. for C22H34ClNP2Pt): C, 43.75
(43.74); H, 5.51 (5.67); N, 2.41 (2.32)%. 31P{H} NMR
cm3) at r.t. for 20 min. A dark orange solid started to
precipitate. The solvent was removed in vacuo and Et2O
added dropwise to aid precipitation. The orange solid
was collected by suction filtration. Yield: 0.263 g, 70%.
Anal. Found (Calc. for C20H29Cl2NNiP2): C, 50.22
(50.57); H, 6.65 (6.15); N, 2.94 (2.95)%. IR (KBr):
3263s (nNH), 326m, 287m.
(CDCl3):
2J(31PÁ31
Hz; d 67.5 ppm, J(195PtÁ31
1J(195PtÁ31 4575 Hz, 2J(31PÁ31
P)ꢀ
d
8.8 ppm, 1J(195PtÁ31
/
P)ꢀ
/
1655 Hz,
P)ꢀ3042
2945 Hz; d 82.2 ppm,
P)ꢀ13 Hz. MS: m/z
Cl]ꢁ. IR (KBr): 3280s (nNH),
2.1.9. PdCl2[Ph2P(CH2)3NHPPri2 ] (9)
/
P)ꢀ
/
12 Hz; d 23.2 ppm, J(195PtÁ31
/
/
1
Ph2P(CH2)3NHPPri2 (2) (0.125 g, 0.45 mmol) and
PdCl2(PhCN)2 (0.133 g, 0.45 mmol) were stirred at r.t. in
CH2Cl2 (10 cm3) for 20 min. Cream solid started to
precipitate. Solvent was removed in vacuo until approxi-
mately 2 cm3 remained. Diethyl ether was added
dropwise to fully precipitate solid. The solid was
collected by suction filtration. Yield: 0.159 g, 85%.
Anal. Found (Calc. for C21H31Cl2NP2Pd): C, 47.03
(47.14); H, 5.61 (5.84); N, 2.78 (2.62)%. No NMR as
/
P)ꢀ
/
1
/
/
/
/
604 [M]ꢁ, 569 [Mꢂ
/
3052m, 1588w, 279w cmꢂ1
.
2.2. Crystallography
X-ray diffraction studies were performed at 293 K
using a Rigaku Mercury CCD for 8 and a Bruker
very insoluble. MS: m/z 500 [Mꢂ
2Cl]2ꢁ. IR (KBr): 3262s (nNH), 3052w, 1435s, 297m,
282m cmꢂ1
/
Cl]ꢁ, 463 [Mꢂ
/
SMART diffractometer for 11 with graphite-monochro-
˚
0.71073 A). The structures
.
mated Mo Ka radiation (lꢀ
/
were solved by direct methods, non-hydrogen atoms
were refined with anisotropic displacement parameters;
2.1.10. PtCl2[Ph2P(CH2)3NHPPri2 ] (10)
Ph2P(CH2)3NHPPri2 (2) (0.248 g, 0.69 mmol) and
PtCl2(PhCN)2 (0.326 g, 0.69 mmol) were stirred at r.t. in
CH2Cl2 (10 cm3) for 20 min. The solvent was removed in
vacuo until a white solid started to precipitate. Diethyl
ether was added dropwise to precipitate the white solid.
The solid was collected by suction filtration. Yield: 0.356
hydrogen atoms bound to carbon were idealised and
˚
fixed (CꢀH 0.95 A), the NH protons were located by DF
/
map. Structural refinements were by the full-matrix
least-squares method on F2 using SHELXTL [15]. Com-
pound 8 was only obtained as poorly diffracting very
thin plates.

2642
T. Appleby et al. / Polyhedron 21 (2002) 2639Á2645
/
1
2.2.1. NiCl2(Ph2PCH2CH2NHPPri2 ) (8)
C20H29Cl2N1Ni1P2, Mꢀ474.99, monoclinic, space
group P21/n, aꢀ8.979(3), bꢀ15.115(6), cꢀ16.688(6)
4, Dcalc 1.394
992, crystal sizeꢀ
0.02 mm. Of 14 456 measured data, 4774
were unique (Rint 0.0517) and observed to give R1
[I ꢀ2s(I)]ꢀ0.1153.
metry and 31P{H} and H NMR. MS gave a Mꢁ peak
/
at 345. 31P{H} NMR revealed the predicted AX
/
/
/
spectrum. The peak at d(PA) ꢂ
to the diphenyl phosphorus, as the peak in the starting
material was at ꢂ20.5 ppm and d(PX) 65.9 ppm was
assigned to the di-isopropyl phosphorus. There is no
observable coupling between the 2 inequivalent. phos-
phorus nuclei. Compound 2 is a white solid whilst 1 is a
clear, viscous liquid. In 2 the PA peak corresponding to
/20.2 ppm was assigned
3
˚
˚
A, bꢀ
Mg mꢂ3, mꢀ
0.23ꢃ0.10ꢃ
/
91.903(5)8, Uꢀ
/
2264(1) A , Zꢀ
/
ꢀ
/
/
1.239 mmꢂ1, F(000)ꢀ
/
/
/
/
/
ꢀ
/
/
/
2.2.2. PtMe2[Ph2P(CH2)3NHPPri2 ] (11)
C23H37N1P2Pt, Mꢀ584.57, monoclinic, space group
P21/c, aꢀ9.4476(2), bꢀ
bꢀ91.161(1)8, Uꢀ2386(1) A , Zꢀ
mꢂ3, mꢀ6.022 mmꢂ1, F(000)ꢀ
1160, crystal sizeꢀ
0.10ꢃ0.10ꢃ0.13 mm. Of 10 219 measured data, 2965
were unique (Rint 0.0192) and observed to give R1
[I ꢀ2s(I)]ꢀ0.0159.
the diphenyl phosphorus is at ꢂ
/
14 ppm [similar to the
starting material at ꢂ14.6 ppm]; the d(PX) peak
/
/
˚
assigned to the di-isopropyl phosphorus, like that of 1,
occurs at d(P) 67 ppm.
Further evidence for the above assignment is that 1
reacts with 1 equiv. of elemental selenium at the most
basic and therefore most reactive phosphorus atom, the
di-isopropyl phosphorus atom since d(PA) ꢂ20 ppm
remains in the same place, whilst d(PX) 65.9 ppm in 1
shifts to 89 ppm in Ph2PCH2CH2NHP(Se)Pri2 .
/
/
15.5972(3), cꢀ
/
16.1970(1) A,
3
˚
/
/
/
4, Dcalc 1.627 Mg
ꢀ
/
/
/
/
/
/
ꢀ
/
/
/
/
We examined some simple coordination chemistry of
1 and 2. Complexation reactions were straightforward,
with coordination to platinum, palladium and nickel all
being carried out at room temperature. Coordination to
iron required refluxing in acetonitrile in the presence of
a catalyst. All complexes were formed as fine powders.
The spectroscopic data for the complexes are readily
interpreted and consistent with chelate monomeric
systems though we noted some weak high value m/z
peaks in some of the mass spectra which could suggest
dimer formation in the mass spectrometer at least.
The palladium dichloride complex 3 was formed by
direct reaction of 1 with PdCl2(PhCN)2. Mass spectro-
3. Results and discussion
Surprisingly, there are relatively few examples of
unsymmetrical diphosphines in which the two phospho-
rus atoms have different substituents. One limiting
factor in the synthesis has been the inconvenient routes
involving highly air sensitive intermediates. Grim et al.
[15Á
the types RPhP(CH2)nPPh2 (nꢀ
Pri, But, Bu) and R2P(CH2)nPPh2 (nꢀ
nꢀ3, RꢀMe), but their route is experimentally diffi-
/
18] have synthesised a number of diphosphines of
1Á3, RꢀMe, Et, Pr,
1, Rꢀ
Me, Pri,
/
/
/
/
/
/
/
cult. Briggs and coworkers [19] reported an easier
synthesis of diphosphines of the type RPhP(CH2)nPPh2
scopy gave the Mꢁ
Naꢁ peak at 545, corresponding to
/
(nꢀ
/
3Á
/
6, RꢀMe, Et, c-C6H11) via the stepwise forma-
/
a monomeric complex and microanalysis was in good
agreement with the proposed structure. In its 31P{1H}
NMR the diphenyl phosphorus group is observed at
d(PA) 20.9 ppm whilst d(PX) 90.3 ppm, the coupling
tion of the mono- and di-phosphonium salts, using a
non-polar solvent in the first stage and a polar solvent
for the second stage, and on the loss of phenyl in
preference to alkyl at the hydrolysis stage. More recently
a one-pot synthesis to unsymmetrical 1,2-bis(phospha-
nyl)ethanes has been developed [20]. We have been
interested in the use of Pꢀ
phosphine synthesis and have developed strategies for
the synthesis of unsymmetrical aryl backbone phos-
constant, 2J(PXÁ
/
PA)ꢀ
/
7 Hz, is very small. The two
Cl) 297, 282
peaks in the IR spectrum assigned as n(Mꢂ
/
cmꢂ1 suggest the ligand coordinates in a cis-geometry
and therefore the complex has a six-membered PdP2NC2
chelate ring. The dichloro-, dimethyl- and chloromethyl-
platinum complexes were all formed by similar ligand
substitution reactions (Scheme 1).
/
N bond forming reactions for
phines from amines [21Á26]. Here we have extended our
/
methods to alkyl backbone systems. Thus Ph2PCH2-
CH2NHPPri2 (1) and Ph2P(CH2)3NHPPri2 (2), were
obtained by direct reaction of the appropriate amine,
and chlorodiisopropylphosphine. The presence of
slightly more than 1 M equivalent of triethylamine
ensures complete removal of the hydrogen chloride by-
product (Eq. (1)).
The geometry of complexes 4Á6 was confirmed by
/
examination of the PtÁP coupling constants in their
/
31P{H} NMR summarised below (Table 1). The mass
spectrum of 4 has a major peak at 576 corresponding to
[Mꢂ
6.4 ppm, 1J(PtÁ
1J(PtÁ
PX)ꢀ4626 Hz. The d(PA) peak is assigned to the
/
Cl]ꢁ. The 31P{H} NMR of complex 6 has d(PA)
/
PA)ꢀ1879 Hz and d(PX) 63.8 ppm,
/
/
/
i
Ph2P(CH2)nNH2 ꢁ Pr2PClꢁEt3N
diphenyl phosphorus group trans to methyl with the
PPri2 group is trans to chloride.
0 Ph2P(CH2)nNHPiPr2 ꢁNEt3HCl
(1)
Coville et al. [27] found [(h5-C5H5)Fe(CO)2I] reacts
nꢀ2 (1); 3 (2)
with diphosphines (Lꢀ
L) in the presence of [(h5-C5H5)-
/
/
The structure of 1 was confirmed by mass spectro-
Fe(CO)2]2 catalyst to produce [(h5-C5H5)Fe(CO)(Lꢀ

T. Appleby et al. / Polyhedron 21 (2002) 2639Á
/
2645
2643
Scheme 1. Formation of palladium and platinum complexes of 1.
L)]I. The reaction for each of the diphosphines, Lꢀ
Ph2P(CH2)nPPh2 (nꢀ1Á4), was followed by IR and in
each case [(h5-C5H5)Fe(CO)2(Lꢀ
L)]I was readily identi-
/
Lꢀ
/
bonds. We were unable to obtain a satisfactory NMR
spectrum of 8 since it is poorly soluble and appears to be
paramagnetic in solution which suggests at least some
tetrahedral character in solution. X-ray crystallography
reveals the solid state structure of 8 (Fig. 1) with the
nickel in an approximate square planar geometry and
the two phosphorus atoms coordinating in a cis fashion.
The diphosphine ligand forms a six-membered metalla-
cycle, which can best be described as having a half-boat
conformation, NiP2NC(13) are approximately coplanar
with C(14) at the prow of the boat. Hydrogen bonding
/
/
/
fied by the characteristic n(CO) at 2050, 2000 cmꢂ1. We
have found that reaction of 1 under the same conditions
as above gives [(h5-C5H5)Fe(CO)(Ph2PCH2CH2NHP-
Pri2 )]I (7) identified by n(CO) 1954 cmꢂ1, microanalysis
and mass spectrometry. The 31P NMR of 7 contains the
expected AX spectrum, with a large change in chemical
shift on coordination to the iron (d(PA) 53.0 ppm, d(PX)
119.8 ppm) compared to the free ligand values of d(PA)
ꢂ
/
20.2 ppm and d(PX) 66.0 ppm. The spectrum also
2
between the amine proton N(2) and Cl(2) of the adjacent
˚
shows a large PÁ
/
P coupling, J(PXÁ
/
PA)ꢀ/67 Hz. In a
complex [ClÁ Á ÁH 2.40, ClÁ Á ÁN 3.37 A, NꢀHÁ Á ÁCl 1708)
/
separate experiment in which no catalyst was used, the
[(h5-C5H5)Fe(CO)2(Ph2PCH2CH2NHP-
results in an infinite chain motif (Fig. 2).
As with 1 complexation of Ph2P(CH2)3NHPPri2 (2)
involves straight forward ligand substitution reactions,
we established coordination to platinum and palladium
for illustrative purposes. All complexes were produced
as fine powders. In the 31P NMR of 11 the spectrum is
again the expected AX type, with satellites due to
coupling to platinum. d(PA) 7.3 ppm is assigned to
intermediate
Pri2 )]I was observed after 16 h [n(CO) 2951, 2006
cmꢂ1] which is consistent with Coville’s work [27].
NiCl2×
/
6H2O reacts with 1 to give NiCl2(Ph2PCH2-
CH2NHPPri2 ) (8). Microanalyses are consistent with
this formulation and its IR spectrum contains peaks at
287 and 326 cmꢂ1, confirming the presence of cis Niꢀ
/Cl
Table 1
31P{H} NMR data
dPA (PPh2) (ppm) dPB (PPr2) (ppm) 1J(PA
Á/
Pt) (Hz) 1J(PX
Á/
Pt) (Hz) 2J(PA
ÁPX) (Hz)
/
Ph2PCH2CH2NHPPri2 (1)
ꢂ20.2
ꢂ14.7
20.9
ꢂ1.4
7.1
66.0
66.9
90.3
57.8
68.3
63.8
119.8
94.4
82.2
67.5
0
0
Ph2PCH3CH3CH3NHPPri (2)
PdCl2(Ph2PCH2CH2NHPPri2 ) (3)
PtCl2(Ph2PCH2CH2NHPPri2 ) (4)
PtMe2(Ph2PCH2CH2NHPPri2 ) (5)
PtClMe(Ph2PCH2CH2NHPPri2 ) (6)
Fe(CO)(h5-C5H5)(Ph2PCH2CH2NHPPri2 )I (7)
PtMe2[Ph2P(CH2)3NHPPri2 ] (11)
PtMeCl[Ph2P(CH2)3PPri2 ] (12A)
PtMeCl[Ph2P(CH2)3PPri2 ] (12B)
7
3584
1849
1879
3595
1990
4626
17
22
18
67
15
12
13
6.4
53.0
7.3
1823
1655
3042
2164
4575
2945
8.8
23.2
No spectra were obtained for 8, 9 and 10 because of insolubility.

2644
T. Appleby et al. / Polyhedron 21 (2002) 2639Á
/
2645
Fig. 4. Different isomers of 12.
PPh2 and d(PX) 94.4 ppm is assigned to PPri2 . The
proton NMR clearly shows the different environments
of the two methyl groups on the platinum, both methyl
groups are coupled to the phosphorus to give an
Fig. 1. X-ray structure of NiCl2(PH2PCH2CH2NHPPri2 ) (8). Selected
apparent quartet J(1HÁ31
/
P)ꢀ7.7 Hz with satellite
/
˚
bond lengths (A) and angles (8) Niꢀ
/
P(1) 2.173(2), Niꢀ
Cl(2) 2.226(2), P(1)ꢀC(13) 1.822(6), C(13)ꢀ
N(2) 1.448(8), N(2)ꢀP(2) 1.668(6); P(1)ꢀNiꢀ
NiꢀCl(2) 90.1(8), N(2)ꢀP(2)ꢀNi 117.3(2), C(14)ꢀ
/
P(2) 2.186(2),
Niꢀ
C(14) 1.524(9), C(14)ꢀ
P(2) 96.1(1), Cl(1)ꢀ
NiꢀP(2) 125.7(4).
/
Cl(1) 2.196(2), Niꢀ
/
/
/
peaks either side due to coupling to the platinum.
Crystallography confirmed the structure of 11 (Fig. 3)
to be monomeric with the diphosphine ligand coordi-
nating as a chelate. The geometry around the platinum
/
/
/
/
/
/
/
/
/
/
is distorted square planar, [P(1)ꢀ
/
Pt(1)ꢀP(2) 100.0(1)8
/
and C(28)ꢀPt(1)ꢀC(27) 82.8(1)8] with the ligand dis-
/
/
playing a significantly larger bite angle than 1 in 8 as a
consequence of the extra methylene group in the back-
bone here and since the trans methyl groups are less
sterically demanding than the chlorides in 8. The
conformation of the ring is a distorted ‘chaise longue’.
Complex 12 was formed by reaction of ligand 2 with
PtMeCl(cod). 31P NMR (Table 1) shows the presence of
equal proportions of two isomers (Fig. 4). If d(PA) is
assigned to PPh2 and d(PX) is assigned to PPri2 then in
isomer A the PPh2 moiety is trans to methyl and has a
small coupling constant to platinum, J(31PAÁ195
1
/
Pt)ꢀ
/
1665 Hz, and the PPri2 moiety is trans to chloride and
therefore has a large coupling constant with platinum,
1J(31PXÁ195
/
Pt)ꢀ4575 Hz.
/
This work clearly illustrates the ease of formation of
unsymmetrical phosphines and should allow the effect
of variation of the two phosphorus centres on a range of
catalytic processes to be studied.
Fig. 2. Hydrogen bonding between the amine proton and chloride of
the adjacent complex resulting in an infinite chain motif in
NiCl2(PH2PCH2CH2NHPPri2 ) (8).
4. Supplementary material
Full lists of structure refinement data, atomic coordi-
nates, bond lengths and angles, anisotropic displace-
ment parameters and hydrogen atom parameters have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 188819 (8), 188820 (11).
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (fax: ꢁ44-1223-336033; e-
/
mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
Fig. 3. The X-ray structure of PtMe2[Ph2P(CH2)3NHPPri2 ] (11).
˚
Selected bond lengths (A) and angles (8) Ptꢀ
/
P(1) 2.285(1), Ptꢀ
C(28) 2.110(3), P(1)ꢀCꢀ(!3) 1.844(3),
C(15) 1.508(5), C(15)ꢀN(2) 1.455(4),
P(2) 100.0(1), C(27)ꢀPtꢀC(28) 82.8(1),
Pt 115.5(1), C(15)ꢀN(6)ꢀP(2) 123.8(2).
/
P(2)
References
2.285(1), Ptꢀ
C(13)ꢀC(14) 1.524(5), C(14)ꢀ
N(2)ꢀP(2) 1.684(3); P(1)ꢀPtꢀ
N(2)ꢀP(2)ꢀ
/
C(27) 2.124(3), Ptꢀ
/
/
/
/
/
/
/
/
/
/
/
[1] C.A. McAuliffe, Comprehensive Coordination Chemistry, vol. 2,
/
/
/
/
Pergamon, Oxford, 1987, p. 989.

T. Appleby et al. / Polyhedron 21 (2002) 2639Á
/
2645
2645
[2] E. Drent, J.A.M. van-Brockhoven, M.J. Doyle, J. Organomet.
Chem. 417 (1991) 235.
[3] M.J. Joshi, J.S. Thornburn, S.J. Rettig, B.R. James, Inorg. Chim.
[14] H.C. Clarke, L.E. Manzer, J. Organomet. Chem. 59 (1973) 411.
[15] SHELXTL, Version 5.10, Bruker AXS, 1998.
[16] S.O. Grim, R.C. Barth, J. Organomet. Chem. 94 (1975) 327.
[17] S.O. Grim, J.D. Mitchell, Inorg. Chem. 16 (1977) 1762.
[18] S.O. Grim, J.D. Mitchell, Inorg. Chem. 16 (1977) 1770.
[19] F.R. Benn, J.C. Briggs, C.A. McAuliffe, J. Chem. Soc., Dalton
Trans. (1984) 293.
Acta 198Á200 (1992) 283.
/
[4] Y.B. Kang, M. Pabel, D.D. Pathak, A.C. Willis, S.B. Wild, Main
Group Chem. 1 (1995) 89.
[5] R. Ugo, Aspects of Homogenous Catalysis; A Series of Advances,
Reidel, Dordrecht, 1974.
[20] G. Fries, J. Wolf, M. Pfeiffer, D. Stalke, H. Werner, Angew.
Chem., Int. Ed. Engl. 3 (2000) 564.
[6] S. Ittel, G. Parshall, Homogeneous Catalysis: The Applications
and Chemistry of Catalysis by Soluble Transition Metal Com-
plexes, Wiley, New York, 1992.
[21] A.M.Z. Slawin, M. Wainwright, J.D. Woollins, New J. Chem. 24
(2000) 69.
[7] S.M. Aucott, A.M.Z. Slawin, J.D. Woollins, J. Organomet.
[22] A.M.Z. Slawin, J.D. Woollins, Q. Zhang, Inorg. Chem. Commun.
2 (1999) 386.
Chem. 582 (1999) 83Á89.
/
[8] Q. Zhang, S.M. Aucott, A.M.Z. Slawin, J.D. Woollins, Eur. J.
Inorg. Chem. (2002) 1635.
[23] S.M. Aucott, A.M.Z. Slawin, J.D. Woollins, J. Chem. Soc.,
Dalton Trans. (2000) 2559.
[9] Y. Ben-David, M. Portnoy, D. Milstein, J. Chem. Soc., Chem.
Commun. (1989) 1816.
[24] M.L. Clarke, G.L. Holliday, A.M.Z. Slawin, J.D. Woollins,
Inorg. Chem. Commun. 4 (2001) 115.
[10] E. Lindner, M. Schmid, J. Wald, J.A. Queisser, M. Geprags, P.
Wegner, C. Nachtigal, J. Organomet. Chem. 602 (2000) 173.
[11] K. Kashiwabara, I. Kinoshita, T. Ito, J. Fujita, Bull. Chem. Soc.
Jpn. 54 (1981) 725.
[25] S.M. Aucott, M.L. Clarke, A.M.Z. Slawin, J.D. Woollins, J.
Chem. Soc., Dalton Trans. (2001) 972.
[26] S.M. Aucott, A.M.Z. Slawin, J.D. Woollins, J. Chem. Soc.,
Dalton Trans. (2001) 2279.
[12] K. Kashiwabara, M. Jung, J. Fujita, Bull. Chem. Soc. Jpn. 64
(1991) 2372.
[13] G.K. Anderson, M. Lin, Inorg. Synth. 28 (1990) 60.
[27] N.J. Coville, E.A. Darling, A.W. Hearn, P. Johnston, J.
Organomet. Chem. 328 (1987) 375.