Synthesis and molecular structure of a new class of bi- and ter-dentate palladium complexes with iminophosphorane containing ligands

Article abstract of DOI:10.1039/b209242e

The Michael-type addition of a range of amines to the C=C bond of P,P,P-diphenylvinyl iminophosphoranes yielded a new class of N,N-bidentate ligands R¹ N=P(Ph₂)CH₂CH₂-NR²R³ (2). These mixed nitrogen-nitrogen donor ligands react with stoichiometric amounts of PdCl₂(PhCN)₂ to give σN, σN-palladium complexes 3 containing an iminophosphorane moiety. From primary amines and two vinyl iminophosphorane units, either identical or different, the new terdentate ligands R¹-N=P(Ph₂)CH₂CH₂-N(R³)-C H₂CH₂P(Ph₂)=N-R² (4), where R¹ = R² or R¹ ≠ R², could be efficiently synthesized. Reaction of these ligands with 1.5 equiv. of PdCl₂(PhCN)₂ yielded the cationic complexes 5 with the ligands coordinating in a N,N′,N′-terdentate fashion. Additionally, by the use of other nucleophiles such as diphenylphosphane and thiophenol this methodology has been applied to the synthesis of the new N,P-(R-N=P(Ph₂)CH₂CH₂PPh₂) (9) and N,S-bidentate (R N=P(Ph₂)CH₂CH₂SPh) (10) ligands, respectively, and of their corresponding Pd(II) complexes (11 and 12). All compounds have been characterized by spectroscopic methods and the X-ray crystal structures of 3c, 5b and 11b are reported.

Full text of DOI:10.1039/b209242e

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Synthesis and molecular structure of a new class of bi- and
ter-dentate palladium complexes with iminophosphorane containing
ligands†
Mateo Alajarín,*a Carmen López-Leonardo,a Pilar Llamas-Lorente,a Delia Bautista‡b
and Peter G. Jones§c
a Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia,
Campus de Espinardo, E-30100 Murcia, Spain. E-mail: alajarin@um.es
b Servicio Universitario de Instrumentación Científica, Edificio SACE,
Universidad de Murcia, Campus de Espinardo, E-30100 Murcia, Spain.
E-mail: dbc@um.es
c Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany.
E-mail: jones@xray36.anchem.nat.tu-bs.de
Received 25th September 2002, Accepted 28th October 2002
First published as an Advance Article on the web 7th January 2003
The Michael-type addition of a range of amines to the C᎐C bond of P,P,P-diphenylvinyl iminophosphoranes
᎐
yielded a new class of N,N-bidentate ligands R1–N᎐P(Ph )CH CH –NR2R3 (2). These mixed nitrogen–nitrogen
᎐
2
2
2
donor ligands react with stoichiometric amounts of PdCl2(PhCN)2 to give σN,σN-palladium complexes 3
containing an iminophosphorane moiety. From primary amines and two vinyl iminophosphorane units, either
identical or different, the new terdentate ligands R1–N᎐P(Ph )CH CH –N(R3)–CH CH P(Ph )᎐N–R2 (4), where
᎐
᎐
2
2
2
2
2
2
R1 = R2 or R1 ≠ R2, could be efficiently synthesized. Reaction of these ligands with 1.5 equiv. of PdCl2(PhCN)2
yielded the cationic complexes 5 with the ligands coordinating in a N,NЈ,NЈ-terdentate fashion. Additionally,
by the use of other nucleophiles such as diphenylphosphane and thiophenol this methodology has been applied
to the synthesis of the new N,P-(R–N᎐P(Ph )CH CH PPh ) (9) and N,S-bidentate (R–N᎐P(Ph )CH CH SPh)
᎐
᎐
2
2
2
2
2
2
2
(10) ligands, respectively, and of their corresponding Pd() complexes (11 and 12). All compounds have
been characterized by spectroscopic methods and the X-ray crystal structures of 3c, 5b and 11b are
reported.
There are only a few reports of transition metal complexes
of type I.4 In contrast, derivatives of type II have been stud-
ied in depth, with bis(iminophosphoranyl)methane derivatives
proving to be versatile ligands.5 Another class of well-studied
ligands are difunctional compounds that contain an imino-
phosphorane function and a second donor site, in most cases
a phosphorus atom from a phosphino group.6 However,
examples of transition metal complexes of type III, that
incorporate a nitrogen atom of an amine function as second
donor site, are scarce,7 and to the best of our knowledge
there is only one report7d on the structurally related com-
plexes of type IV, where the phosphorus atom occupies an
endocyclic position.
The small number of examples of type IV σN,σN-complexes
led us to undertake the study of this poorly explored area. In
this communication we present our results on the synthesis of
N,N-ligands with an iminophosphorane unit and an amino
group separated by an ethylene tether and their corresponding
palladium-complexes.
Introduction
In recent years, bidentate donor species containing sp2-hybrid-
ised nitrogen atoms have attracted much attention as ligands for
transition-metal-catalyzed transformations.1
Iminophosphoranes (λ5-phosphazenes), compounds with the
general structure R P᎐N–R, date back to 1919,2a but their
᎐
3
chemistry has been explored mainly in the last three decades.
They have found numerous applications, which include their
use as ylides in organic synthesis (aza-Wittig reaction) or as
building blocks for P–N-backbone polymers (polyphos-
phazenes).2 Iminophosphoranes possess a highly polarized P᎐N
᎐
bond and have been shown to coordinate to transition metals
via the approximately sp2-hybridized nitrogen atom to give
stable complexes.2,3 The most studied complexes incorporat-
ing the iminophosphorane moiety are the homobidentate
derivatives of type I and II (see below).
In common with other electron-withdrawing groups, di-
phenylphosphinoyl and diphenylthiophosphinoyl groups acti-
vate an olefinic residue to nucleophilic (Michael-type) additions
with simple nucleophilic species, such as phosphanes,8 alcohols9
or amines.10 The polarity of the P᎐N bond of an iminophos-
᎐
phorane derived from diphenylvinylphosphane makes the C᎐C
᎐
bond of these substrates a potential Michael acceptor unit. In
fact, the addition of amines to species of the type CH ᎐CH–
᎐
2
† Electronic supplementary information (ESI) available: ligand syn-
thesis details. See http://www.rsc.org/suppdata/dt/b2/b209242e/
‡ Corresponding author regarding the X-ray diffraction studies of
complexes 3c and 11b.
§ Corresponding author regarding the X-ray diffraction studies of
complex 5b.
P(Ph )᎐N–P(X)R has been described recently in the context of
᎐
2
2
the synthesis of dendrimers,11 and we have reported the addi-
tion of diphenylphosphane to CH ᎐CH–P(Ph )᎐N–R as a
᎐
᎐
2
2
method for the synthesis of monoiminophosphoranes derived
from 1,2-bis(diphenylphosphino)ethane.12
D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
426

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methylene resonances are detected, one in the interval δ 24.94–
Results and discussion
28.68 with a coupling constant (1JCP) of 66.7–72.0 Hz and
the other in the interval δ 43.17–52.13, with a 2JCP of 0–1.3 Hz
that are assigned to the CH2P and CH2N carbons, respec-
tively. These data are in agreement with others previously
published, showing that in P()-alkyl substituted compounds
the value of 1JCP coupling constant is of the order of 60–70 Hz,
In the context of our investigations and in conjunction with the
literature background in our hands, we envisaged that the
Michael-type additions of amines to P,P,P-diphenylvinyl
iminophosphoranes could be a potential source of N,N-ligands
for an easy access to complexes of type IV.
The iminophosphoranes 1a–c are readily prepared from
the stoichiometric reaction of aryl azides and diphenylvinyl-
phosphane under the standard conditions of the Staudinger
imination reaction2a,c (Scheme 1). They were isolated after a
simple work-up and obtained as crystalline solids in good yields
(79–92%, see ESI).†
2
whereas JCP is very small or non-observable.10g,11b,c The 1H
NMR spectra of 2a,b,d show a multiplet in the range δ 2.45–
2.73 as a result of the overlapping of the signals correspond-
ing to the methylene groups of the PCH2CH2N backbone,
whereas compounds 2c,e,f show two separated multiplets
centered close to δ 2.60 and 2.80. A bidimensional 13C–1H
COSY NMR experiment on compound 2e show that the multi-
plet at lower field is due to the CH2N group, whereas that at
higher field corresponds to the CH2P group. The nucleophilic
addition also induced the deshielding of the signal corre-
sponding to the Ph P᎐NAr phosphorus in the 31P NMR spectra
᎐
2
of 2a–f when compared with that of compounds 1 (∆δ = 5.58–
5.94 for R1 = 4-CH3C6H4, ∆δ = 6.33–7.26 for R1 = 4-CH3OC6H4
and ∆δ = 4.93 for R1 = 4-NO2C6H4).
Although the addition of secondary aliphatic amines to
the vinyl group of 1 took place successfully, the less basic
N-substituted anilines did not add under the same conditions.
The ligands 2a–f were allowed to react with an equimolar
amount of PdCl2(PhCN)2 in dichloromethane at room tem-
perature to give the σN,σN-complexes 3a–f, as orange
crystalline solids in very good yields (92–98%), the first Pd()
compounds built on an iminophosphorane-amine skeleton with
the atomic connectivity as shown in complexes of type IV
(Scheme 1).
An unequivocal proof of that coordination to palladium
took place involving the iminophosphorane group is provided
by the 31P{1H} NMR spectra of complexes 3. A signal is
observed in the range δ 24.44–30.26, remarkably deshielded in
relation to the corresponding ligands 2 (∆δ = 18.64–20.07).
These chemical shifts are in agreement with the ones described
for other iminophosphorane-palladium complexes.4d,6e,f On the
other hand, differences in chemical shifts and coupling constant
values are observed in the 13C{1H} NMR spectra of complexes
3 when compared with those of ligands 2. The doublet assigned
to the CH2P carbon in 3a–e is shifted downfield (∆δ 1.98–3.97)
and show a larger coupling constant (∆1JCP = 10.3–15.7 Hz)
than in the corresponding free ligands 2a–e. The signals attrib-
utable to the ipso carbons of the Ph2P group move to lower field
on going from 2 to 3 and their J values are smaller (∆1JCP = 3.0–
4.4 Hz). Another notorius difference between 2 and 3 is the
splitting of the signal due to the CH2N group of 3, with values
Scheme 1
The characterization of 1 was straightforward following their
analytical and spectral data. The 31P{1H} NMR spectra of 1a–c
show a singlet in the range Ϫ0.77 to 6.13 ppm. In their H
NMR spectra, the signals attributed to the vinylic protons
appear as the ABM portion of an ABMX system, due to their
coupling with the phosphorus nucleus (Fig. 1).
1
2
of JCP = 5.4–8.4 Hz, whereas for the free ligands no such
coupling constant is observed, with the exception of 2e.
The chiral nature of complex 3e due to its stereogenic amine
N atom is shown by the magnetic non-equivalence of its
diastereotopic phenyl groups of the Ph2P moiety in its 13C{1H}
Fig. 1 1H NMR data of P-vinyl iminophosphoranes 1.
1
The Michael-type addition over the vinyl group of
compounds 1 could be carried out efficiently with primary and
secondary amines. Thus, refluxing a benzene solution of com-
pounds 1 containing 1.1 equiv. of the cyclic amines pyrrolidine
and piperidine or an excess (10 equiv.) of volatile amines such
as dimethylamine (2 M solution in THF, bp 60 ЊC), diethyl-
amine (bp 55 ЊC) or propylamine (bp 48 ЊC) the corresponding
N,N-ligands 2a–f were obtained in practically quantitative
yields (Scheme 1). After the removal of the solvent and the
excess of amine under reduced pressure the residue was washed
with n-hexane and the crude 2 so obtained were not submitted
to further purification since NMR analysis showed a high
degree of purity. The occurrence of the addition was corrobor-
NMR spectrum (for instance Ci: δ 124.18, JCP 87.3 Hz and
δ 127.22, 1JCP 89.0 Hz).
Crystals of 3c (R1 = 4-CH3OC6H4, R2 = R3 = CH3CH2) were
grown from dichloromethane–n-hexane and its solid-state
structure was clarified by X-ray analysis (Fig. 2). Selected
crystallographic data are summarized in Table 3 (see Experi-
mental). In complex 3c the ligands coordinates in a bidentate
manner as a σN,σN-donor forming a puckered six-membered
chelate ring, showing a cis geometry around the metal with an
almost perfect square-planar structure; the mean deviation
from the plane Pd, N(1), N(2), Cl(1) and Cl(2) is 0.025 Å. The
Pd–Cl bond lengths [2.3109(13) and 2.3166(13) Å] and the
Pd–N distances [2.124(4) and 2.063(4) Å] are normal. The nat-
ural bite angle of 92.8(2)Њ for N–Pd–N is larger than the ideal
value of 90Њ. The trans angles N(1)–Pd–Cl(1) and N(2)–Pd–
Cl(2) of 178.66(11) and 176.75(12)Њ, respectively, show nearly
no deviation from ideality. In the asymmetric unit, molecules
ated by the disappearance of the signals of the CH᎐CH group
᎐
2
1
in the H and 13C{1H} NMR spectra of 2, as well as by the
appearance of the ones corresponding to the new ethylenic
group. Thus, in the 13C{1H} NMR spectra of 2a–f two
D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
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Table 1 Hydrogen bonds (Å and Њ)
Compound
D–H ؒ ؒ ؒ A
d(D ؒ ؒ ؒ H)
d(H ؒ ؒ ؒ A)
d(D ؒ ؒ ؒ A)
Є(DHA)
3c
5b
C(6)–H(6A) ؒ ؒ ؒ Cl(2)#1
0.99
0.95
0.95
0.95
0.95
0.95
0.95
0.99
2.622(0.005)
2.56
2.57
2.45
2.47
2.41
2.40
2.654(0.005)
3.510(0.05)
3.353(7)
3.298(6)
3.277(7)
3.270(6)
3.290(6)
3.206(7)
3.633(0.05)
149.32(0.12)
141.0
133.8
145.0
141.4
154.0
141.4
169.97(0.12)
C(345)–H(345) ؒ ؒ ؒ O(12)#2
C(546)–H(546) ؒ ؒ ؒ O(12)#3
C(514)–H(514) ؒ ؒ ؒ O(21)#4
C(246)–H(246) ؒ ؒ ؒ O(32)#5
C(513)–H(513) ؒ ؒ ؒ O(32)#5
C(213)–H(213) ؒ ؒ ؒ O(51)
C(98)–H(98A) ؒ ؒ ؒ Cl(2)#6
11b
a Symmetry transformations used to generate equivalent atoms: #1 x, 1 Ϫ y, Ϫ0.5 ϩ z; #2 Ϫx ϩ 1/2, y Ϫ 1/2, Ϫz Ϫ 1/2; #3 x ϩ 1/2, Ϫy ϩ 5/2, z ϩ 1/2;
#4 Ϫx ϩ 1/2, y ϩ 1/2, Ϫz ϩ 1/2; #5 Ϫx ϩ 1, Ϫy ϩ 2, Ϫz; #6 Ϫx, Ϫy, 2 Ϫ z.
Fig. 2 Thermal ellipsoid plot (50% probability level) of 3c. Selected
bond lenghts (Å) and angles (Њ): Pd–N(2), 2.063(4), Pd–N(1), 2.124(4),
Pd–Cl(1), 2.3109(13), Pd–Cl(2), 2.3166(13), P–N(2), 1.610(4); N(2)–
Pd–N(1), 92.8(2), N(2)–Pd–Cl(1), 88.51(12), N(1)–Pd–Cl(1),
178.66(11), N(2)–Pd–Cl(2), 176.75(12), N(1)–Pd–Cl(2), 89.36(11),
Cl(1)–Pd–Cl(2), 89.36(5), C(11)–N(2)–P, 124.0(3), C(11)–N(2)–Pd,
119.7(3), P, N(2)–Pd, 114.1(2).
of 3c associate through intermolecular C–H ؒ ؒ ؒ Cl hydrogen
bonding chains parallel to the y axis (Table 1).
Scheme 2
The iminophosphorane-amine 2e, obtained by reaction of
P,P,P-diphenylvinyl iminophosphorane 1b and propylamine,
was able of adding to a second molecule of P-vinyl imino-
phosphorane 1, to give the bis(iminophosphoranes) 4a and 4b,
that can be symmetrically or unsymmetrically substituted
depending on the substituents at the iminophosphorane func-
tion of each starting material. Thus, reaction of 1a and 1b with
2e in refluxing benzene solution for 5 days afforded 4a and 4b
in 77 and 80% yield, respectively (Scheme 2).† Alternatively,
symmetrically substituted 4 could also be prepared in only
one step by treatment of two equiv. of 1 with one equiv. of
a primary amine under the above reaction conditions. For
example, the addition of benzylamine to 1b (R1 = 4-CH3OC6H4)
complexes 5a and 5b were obtained, as expected for terdentate
coordination of 4, but only in 50 and 60% yield, respectively.
After essaying different ratios between both reactants, the best
results (87% for 4a and 92% yield for 4b) were obtained when
1.5 equiv. of PdCl2(PhCN)2 were used per equivalent of 4
(Scheme 2). Complexes 5 were isolated as its [PdCl4]2Ϫ salts by
crystallization of a dichloromethane solution layered with n-
pentane. The formation of 5 took place by means of triple
nitrogen coordination of the ligands 4 to palladium with dis-
placement of a chlorine atom from the Pd coordination sphere,
and two chloride anions so generated displaced the benzonitrile
ligands of a second molecule of PdCl2(PhCN)2 to form the
[PdCl4]2Ϫ anion. Compound 5b was also characterized by X-ray
diffraction. Selected crystallographic data are sumarized in
Table 3. The structure consists of four independent cations of
5b, one [PdCl4]2Ϫ and two ½[PdCl4]2Ϫ. The structure of one
cation is presented in Fig. 3. A selection of bond lengths and
angles is given in Table 2. In the four cations, the Pd-atom
[Pd(1), Pd(2), Pd(3) or Pd(5)] is bound to one Cl [Cl(11), Cl(21),
Cl(31) or Cl(51)] and to the three N-atoms of the 5b [N(11),
N(12), and N(13), N(21), N(22), and N(23), N(31), N(32), and
N(33) or N(51), N(52), and N(53)]. In each cation, the Pd-atom
is in a slightly distorted square-planar environment (the mean
deviation from the palladium-coordination plane is 0.0074 Å
cation I, 0.0448 Å cation II, 0.0467 Å cation III and 0.0512 Å
cation IV). Bonds angles around the Pd-atoms range from
177.87(11)–174.85(11)Њ trans NPdCl, 91.06(11)–88.43(11)Њ cis
afforded the corresponding bis(iminophosphorane) 4c (R1
R2 = 4-CH3OC6H4, R3 = C6H5CH2) in 72% yield.
=
The addition of 2e to vinyliminophosphoranes 1 took longer
reaction times (5 days) for completion than the addition of
simple secondary amines, such as pyrrolidine and piperidine
(6 h). The spectroscopic data of the symmetrically substituted
adducts 4b,c are very similar to those of 2, whereas those
unsymmetrical, e.g. 4a (R1 = 4-CH3C6H4, R2 = 4-CH3OC6H4,
R3 = CH3CH2CH2) displayed the expected splitting of signals
due to the presence of two different iminophosphoranylethyl-
ene arms. Thus two signals for the CH2P carbons are observed
in the 13C{1H} NMR spectrum of 4a, at δ 24.82 and 24.90, with
1JCP of 65.9 and 66.1 Hz respectively, whereas its 31P {1H}
NMR spectrum shows two singlets at δ 5.16 and 5.52.
When ligands 4a and 4b were reacted with 1 equiv. of
PdCl2(PhCN)2 in dichloromethane solution the cationic Pd
D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
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Table 2 Selected bond lengths (Å) and angles (Њ) of 5b
Pd(1)–N(11)
Pd(1)–N(12)
Pd(1)–N(13)
Pd(1)–Cl(11)
Pd(2)–N(22)
Pd(2)–N(21)
Pd(2)–N(23)
Pd(2)–Cl(21)
Pd(3)–N(32)
Pd(3)–N(31)
Pd(3)–N(33)
Pd(3)–Cl(31)
2.059(4)
Pd(5)–N(52)
Pd(5)–N(51)
Pd(5)–N(53)
Pd(5)–Cl(51)
P(11)–N(11)
P(12)–N(12)
P(21)–N(21)
P(22)–N(22)
P(31)–N(31)
P(32)–N(32)
P(51)–N(51)
P(52)–N(52)
2.042(4)
2.071(4)
2.126(4)
2.2935(12)
1.611(4)
1.623(4)
1.613(4)
1.612(4)
1.609(4)
1.613(4)
1.596(5)
1.606(4)
2.061(4)
2.125(4)
2.2996(11)
2.059(4)
2.068(4)
2.119(4)
2.2982(11)
2.050(4)
2.059(4)
2.129(4)
2.2970(12)
N(11)–Pd(1)–N(12)
N(11)–Pd(1)–N(13)
N(12)–Pd(1)–N(13)
N(11)–Pd(1)–Cl(11)
N(12)–Pd(1)–Cl(11)
N(13)–Pd(1)–Cl(11)
N(22)–Pd(2)–N(21)
N(22)–Pd(2)–N(23)
N(21)–Pd(2)–N(23)
N(22)–Pd(2)–Cl(21)
N(21)–Pd(2)–Cl(21)
N(23)–Pd(2)–Cl(21)
N(32)–Pd(3)–N(31)
N(32)–Pd(3)–N(33)
N(31)–Pd(3)–N(33)
N(32)–Pd(3)–Cl(31)
N(31)–Pd(3)–Cl(31)
N(33)–Pd(3)–Cl(31)
N(52)–Pd(5)–N(51)
N(52)–Pd(5)–N(53)
N(51)–Pd(5)–N(53)
N(52)–Pd(5)–Cl(51)
N(51)–Pd(5)–Cl(51)
N(53)–Pd(5)–Cl(51)
178.36(15)
88.95(14)
92.03(14)
89.01(11)
90.00(11)
177.87(11)
176.21(15)
87.94(14)
92.86(14)
88.93(11)
90.41(11)
176.20(11)
175.83(16)
92.76(14)
88.10(15)
90.67(11)
88.61(11)
176.16(11)
176.62(16)
87.88(15)
92.82(15)
88.43(11)
91.06(11)
174.85(11)
C(131)–N(11)–P(11)
C(131)–N(11)–Pd(1)
P(11)–N(11)–Pd(1)
C(161)–N(12)–P(12)
C(161)–N(12)–Pd(1)
P(12)–N(12)–Pd(1)
C(231)–N(21)–P(21)
C(231)–N(21)–Pd(2)
P(21)–N(21)–Pd(2)
C(261)–N(22)–P(22)
C(261)–N(22)–Pd(2)
P(22)–N(22)–Pd(2)
C(331)–N(31)–P(31)
C(331)–N(31)–Pd(3)
P(31)–N(31)–Pd(3)
C(361)–N(32)–P(32)
C(361)–N(32)–Pd(3)
P(32)–N(32)–Pd(3)
C(531)–N(51)–P(51)
C(531)–N(51)–Pd(5)
P(51)–N(51)–Pd(5)
C(561)–N(52)–P(52)
C(561)–N(52)–Pd(5)
P(52)–N(52)–Pd(5)
125.0(3)
119.5(2)
112.3(2)
121.3(2)
117.5(2)
114.7(2)
125.4(3)
116.0(2)
114.3(2)
126.1(3)
117.4(2)
109.6(2)
128.2(3)
117.4(2)
110.2(2)
123.0(3)
116.6(2)
116.0(2)
123.7(3)
116.6(3)
116.0(2)
127.4(3)
115.6(2)
110.0(2)
of signals are observed for the two phenyl groups in each arm,
that adopt differentiated positions (axial and equatorial) in
the six-membered rings. Similar observations are made in the
NMR spectra of 5c. The chiral nature of unsymmetrically sub-
stituted 5a is shown in its NMR spectra in CDCl3. For instance,
1
in its H MNR spectrum the methylenic protons of the propyl
group are observed as diastereotopic, and in its 13C{1H} NMR
spectrum two signals for CH2P carbons at δ 31.40 and 32.45,
with a coupling constant of 78.9 Hz in both cases, are clearly
differentiated, as well as four signals for the ipso carbons of
1
1
the Ph2P phenyl groups (124.51, JCP = 87.6 Hz; 124.89, JCP
=
88.2 Hz; 127.07, 1JCP = 97.9 Hz, and 127.54, 1JCP = 87.0 Hz).
As a further step in the study of ligands combining amine
and iminophosphorane functions we next prepared the tri-
s(iminophosphoranyl)amine 6, whose structure is closely
related to its mono (2) and bis (4) analogous ligands prepared
above. The potentially tetradentate ligand 6 was prepared
in 90% yield following a completely different method: the
Staudinger imination reaction2a,c of tris(diphenylphosphino-
ethyl)amine with 3 equiv. of 4-tolylazide (Scheme 3).†
Fig. 3 Thermal ellipsoid plot (50% probability level) of one of the
four independent cations of 5b. Hydrogen atoms are omitted for clarity.
NPdCl, 178.36(15)–175.83(16)Њ trans NPdN, and 92.86(14)–
87.88(15)Њ cis NPdN.
The crystal structure of compound 5b shows a bicyclic sys-
tem arising from the fusion of the two six-membered rings in
the four cations. The metallocycles adopt a boat conformation.
Hydrogen bond data are included in Table 1.
The reaction between ligand 6 and PdCl2(PhCN)2 in di-
chloromethane solution in different stoichiometric combin-
ations was first studied by 31P{1H} NMR spectroscopy and
revealed the following trends: (A) When the ratio of reactants is
1 : 1, in addition to the signal at δ 5.39 due to the starting
material (6), two sets of signals in an approximate 1 : 1 ratio are
observed which we attributed to species 7 and 8 (Scheme 3).
Putative complex 7 exhibits two phosphorus environments at
δ 4.37 and 25.44 in a 1 : 2 intensity ratio, respectively. The
high-field resonance falls in the usual range for free imino-
phosphorane and is therefore assigned to a dangling imino-
phosphorane arm, while the low-field one is attributed to
both equivalent arms coordinated to palladium. On the other
hand, the two signals attributed to 8 appear at δ 27.82 and 29.51
in a 2 : 1 intensity ratio. In this binuclear complex the three
The conformation of the C2h symmetrically substituted 5b in
the solid state seems to be kept in solution at 278 K, as shown
by its NMR data in CDCl3 at that temperature. The inequiva-
lence of the methylenic pairs of protons of the ethylene frag-
1
ments is observed in its H NMR spectrum where a complex
system of multiplets, centered at δ 3.57, 4.05 and 4.55, is clearly
shown. The first one is attributed to HA of each methylene
group, CH2P and CH2N, whereas the second and third ones are
due to HB of CH2P and CH2N, respectively. This assignment
has been made on the basis of bidimensional 13C–1H COSY
NMR experiments. In the 13C{1H} NMR spectra of 5b two sets
D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
429

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Scheme 3
iminophosphorane groups are coordinated to palladium(), but
two arms are equivalent (δ 27.82) and different in nature from
the third one (δ 29.51). (B) By increasing the amount of
PdCl2(PhCN)2 to 1.5 equiv., the ratio of products 7/8 was
approximately 1 : 2. (C) When the ratio of reactants is 1 : 2, the
exclusive formation of complex 8 is observed, which could be
isolated as a crystalline solid.
Microanalytical and spectroscopic data support the form-
ulation of complex 8. Its FABϩ-MS shows a peak correspond-
ing to the fragmentation Mϩ Ϫ PdCl3 in 48% relative intensity,
whereas the molecular ion is detected by the FABϪ-MS tech-
nique. Its NMR spectra show that the bicyclic moiety keeps a
close structural relation with 5b. In addition to the signals
corresponding to the bicyclic framework present in 5b, others
Scheme 4
phosphane units. In most of the cases the carbon portion on the
cycle is derived from a vinylene fragment (–CH᎐CH–)6k,n,q and
᎐
only in one case is derived from an ethylene fragment (–CH2–
CH2–).6e The absence of crystallographic data for this last
example, a N-trimethylsilyl derivative of 11, led us to study the
structure in the solid state of 11b (R = NCCH2) by X-ray dif-
fraction (Fig. 4). Selected crystallographic data are summarized
assignable to the dangling CH CH P(Ph )᎐N(Ar)–PdCl moi-
᎐
2
2
2
3
ety are observed. Thus, in its 13C{1H} NMR spectrum a doublet
1
at δ 33.47 with JCP = 79.5 Hz corresponding to the CH2P car-
bon, and another at δ 60.30 assignable to the CH2N carbon,
both due to the dangling arm are observed, besides those of the
bicycle.
On the other hand, we have previously communicated the
synthesis of the σN,σP-ligand 9a, containing iminophosphor-
ane and phosphane units, by means of the Michael-type
addition reaction of diphenylphosphane to the vinylimino-
phosphorane 1b.12 Here we now describe the preparation of
new examples of similar ligands, and the application of the
same methodology for obtaining new σN,σS-ligands.
The clean and fast addition of thiophenol to 1b in benzene
provided the iminophosphorane-sulfide 10 in quantitative yield
and a high degree of purity (Scheme 4).† The spectroscopic data
of 10 are comparable to that of ligands 2 and 9, with the pre-
sumed differences caused by the variation of the heteroatom
placed on the ethyl chain (S, N or P). In the 13C{1H} NMR
Fig. 4 Thermal ellipsoid plot (50% probability level) of 11b. Selected
bond lenghts (Å) and angles (Њ): Pd(1)–N(1), 2.046(3), Pd(1)–P(1),
2.2248(12), Pd(1)–Cl(1), 2.2992(10), Pd(1)–Cl(2), 2.3773(11); N(1)–
Pd(1)–P(1), 89.22(9), N(1)–Pd(1)–Cl(1), 178.12(9), P(1)–Pd(1)–Cl(1),
89.51(4), N(1)–Pd(1)–Cl(2), 90.27(9), P(1)–Pd(1)–Cl(2), 177.31(4),
C(3)–N(1)–P(2), 122.7(3), C(3)–N(1)–Pd(1), 117.0(2), P(2)–N(1)–Pd(1),
117.7(2).
2
spectrum of 10 the doublets at δ 26.05 with JCP = 2.1 Hz
1
and δ 28.58 with JCP = 63.2 Hz are attributed to the CH2S
and CH2P methylene groups, respectively. Its 31P{1H} NMR
spectrum shows a singlet at δ 4.97.
The effective coordination of palladium to bidentate ligands
9 and 10 allowed access to the new Pd() complexes 11 and 12,
respectively. The reaction of 9a or 9b with 1 equiv. of PdCl2-
(PhCN)2 at room temperature in dichloromethane led to the
formation of σN,σP-complexes 11a (R = 4-CH3OC6H4, 92%
yield) and 11b (R = NC–CH2, 95% yield). A similar transform-
ation converted 10 into the σN,σS-complex 12 in 91% yield.
These complexes (11 and 12) are obtained as stable solids that
can be stored for months under a nitrogen atmosphere without
noticeable decomposition. There are only a few six-membered
cyclic N,P-complexes constituted by iminophosphorane and
in Table 3. The mean deviation from the plane Pd, N(1),
P(1), Cl(1) and Cl(2) is 0.017 Å. The difference between the
palladium–chlorine bond lengths Pd(1)–Cl(1) [2.2992(10) Å]
and Pd(1)–Cl(2) [2.3773(11) Å] of 0.0781 Å reflects the stronger
trans influence of the tertiary phosphine compared with the
N-donor iminophosphorane group. The Pd–N bond length of
2.046(3) and the Pd–P of 2.2248(12) Å are common for this
type of complexes. The N–Pd–P bite angle is close to 90Њ
[89.22(9)Њ]. Hydrogen bond data are included in Table 1.
Each compound 11 shows two well-differentiated signals in
the aliphatic region of its 13C{1H} NMR spectrum, correspond-
D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
430

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ing to the P()CH2CH2P() portion. The double doublet
assigned to the CH2P() carbon appeared at δ 18.67 (1JCP()
was removed under vacuum and the residue was treated with
dry diethyl ether to give 3 as a solid which was isolated by
=
33.6 and 2JCP() = 6.4 Hz) for 11a and δ 19.81 (1JCP() = 32.5 and
2JCP() = 5.7 Hz) for 11b. The doublet assigned to the CH2P()
carbon was shifted downfield, at δ 25.01 for 11a and 25.29 for
11b, showing only a 1J coupling constant with the P() atom of
77.1 and 72.5 Hz, respectively. Additionally, in the 13C{1H}
NMR spectra of complexes 11 two differentiated sets of signals
for the phenyl rings of the two Ph2P groups are observed, which
show very similar chemical shifts and coupling constants. The
31P{1H} NMR spectrum of 11a shows two doublets (3JPP = 11.0
Hz) at δ 23.78 and 27.36, whereas for 11b these doublets appear
at δ 22.49 and 36.95 (3JPP = 14.9 Hz). Both compounds display
phosphorus resonances notably shifted downfield when com-
pared with those of the free ligands 9 [9a: δ Ϫ12.61 and 6.62
(3JPP = 46.7 Hz) and 9b: δ Ϫ11.42 and 24.63 (3JPP = 46.3 Hz)], as
expected for the coordination in a σN and σP chelate mode.
Microanalytical and spectroscopic data of 12 are consistent
with its formulation. Two multiplets at δ 2.92 and 3.20 in its 1H
NMR spectrum and two doublets at δ 28.41 (1JCP = 79.5 Hz,
CH2P) and 29.87 (2JCP = 7.5 Hz, CH2S) in its 13C{1H} NMR
spectrum are specially significant. The singlet at δ 25.73 in its
31P{1H} NMR spectrum along with the appearance of the peak
at m/z 642 (Mϩ ϩ 23) in its FABϩ-MS spectrum further
corroborate the proposed structure.
filtration and dried under reduced pressure.
3a (R1 = 4-CH3C6H4, R2 = R3 = CH3). Orange solid (0.155 g,
96%) that was recrystallized from CH2Cl2–n-pentane (orange
prisms); mp (decomp.) 167–171 ЊC. IR (Nujol)/cmϪ1: 1504,
1440, 1288, 1268, 1112, 1021, 876, 729. 1H NMR (CDCl3):
δ 2.10 (s, 3H, CH3), 2.98 [s, 6H, (CH3)2N], 2.84–2.88 (m, 4H,
PCH2CH2N), 6.76 (d, J = 8.1 Hz, 2H, Ar), 7.19 (d, J = 8.1 Hz,
2H, Ar), 7.25–7.54 (m, 4H, Ph2), 7.55–7.63 (m, 2H, Ph2),
7.76–7.83 (m, 4H, Ph2). 13C{1H} NMR (CDCl3): δ 20.83
1
(CH3), 29.06 (d, JCP = 81.4 Hz, CH2P), 52.24 (CH3N), 56.26
(d, 2JCP = 7.0 Hz,CH2N), 126.91 (d, 1JCP = 88.7 Hz, Ci), 127.30
3
3
(d, JCP = 10.4 Hz, C2), 128.74 (C3), 129.45 (d, JCP = 12.2 Hz,
2
Cm), 131.55 (C4), 132.90 (d, JCP = 9.9 Hz, Co), 133.43 (Cp),
145.01 (C1). 31P{1H} NMR (CDCl3): δ 25.25. FABϩ-MS m/z
(rel. intensity): 540 (Mϩ ϩ 2, 6), 538 (Mϩ, 6), 364 (Mϩ
ϩ
2-PdCl2, 31), 363 (Mϩ ϩ 1-PdCl2, 100), 362 (Mϩ Ϫ PdCl2, 31),
361 (Mϩ Ϫ 1-PdCl2, 94). Anal. calc. for C23H27Cl2N2PPd: C,
51.18; H, 5.04; N, 5.19. Found: C, 50.99; H, 5.21; N, 5.34%.
3b [R1 = 4-CH3C6H4, R2 = R3 = (CH2)4]. Orange solid (0.166
g, 98%) that was recrystallized from CH2Cl2–n-pentane (orange
prisms); mp (decomp.) 158–160 ЊC. IR (Nujol)/cmϪ1: 1504,
1437, 1285, 1265, 1114, 1023. 1H NMR (CDCl3): δ 1.89 (m, 2H,
CH2), 2.10 (s, 3H, CH3), 2.13 (m, 2H, CH2), 2.80–3.00 (m, 6H,
CH2), 4.22 (m, 2H, CH2), 6.76 (d, J = 8.1 Hz, 2H, Ar), 7.18 (d,
J = 8.1 Hz, 2H, Ar), 7.47–7.54 (m, 4H, Ph2), 7.59–7.65 (m, 2H,
Ph2), 7.78–7.84 (m, 4H, Ph2). 13C{1H} NMR (CDCl3): δ 20.82
Summary
1
(CH3), 22.17 (CH2), 30.25 (d, JCP = 82.3 Hz, CH2P), 52.17 (d,
The present investigation has explored the Michael-type addi-
tion reaction of different N-, P- and S- nucleophiles to P,P,P-
diphenylvinyl iminophosphoranes. By the concourse of several
amines, diphenylphosphane and thiophenol we have prepared
different N,N-, N,P-, and N,S-bidentate, and N,N,N-triden-
tate ligands. The corresponding Pd() complexes have been
obtained and characterized. We believe that this synthetic strat-
egy could be applicable to varied structural motifs. The assess-
ment of the catalytic activity of these complexes in different
processes, and additional experimental refinement to obtain
new ligands and their complexes with other metals is in progress
in our laboratory.
2JCP = 8.4 Hz, CH2N), 60.69 (CH2), 126.19 (d, JCP = 88.1 Hz,
1
Ci), 126.75 (d, 3JCP = 9.9 Hz, C2), 128.72 (C3), 129.36 (d, 3JCP
=
12.3 Hz, Cm), 131.11 (C4), 133.01 (d, 2JCP = 10.0 Hz, Co), 133.35
4
(d, JCP = 2.3 Hz, Cp), 145.05 (C1). 31P {1H} NMR (CDCl3):
δ 24.57. FABϩ-MS m/z (rel. intensity): 566 (Mϩ ϩ 2, 15),
564 (Mϩ, 16), 563 (Mϩ Ϫ 1, 12), 390 (Mϩ ϩ 2-PdCl2, 54), 389
(Mϩ ϩ 1-PdCl2, 100), 388 (Mϩ Ϫ PdCl2, 62), 387 (Mϩ
Ϫ
1-PdCl2, 96). Anal. calc. for C25H29Cl2N2PPd: C, 53.07; H, 5.17;
N, 4.95. Found: C, 53.24; H, 5.29; N, 5.13%.
3c (R1 = 4-CH3OC6H4, R2 = R3 = CH3CH2). Orange solid
(0.16 g, 92%) that was recrystallized from CH2Cl2–n-pentane
(orange prisms); mp (decomp.) 143–145 ЊC. IR (Nujol)/cmϪ1
:
1506, 1442, 1234, 1111, 1015, 748, 727. 1H NMR (CDCl3):
δ 1.57–1.60 (m, 6H, CH3CH2), 2.90–3.10 (m, 6H, CH3CH2 ϩ
CH2), 3.38 (m, 2H, CH2), 3.59 (s, 3H, OCH3), 6.45 (d,
J = 8.5 Hz, 2H, Ar), 7.15 (d, J = 8.5 Hz, 2H, Ar), 7.43–7.50 (m,
Experimental
All reactions were carried out under nitrogen and using solvents
that were dried by routine procedures. Diphenylvinylphosphane
and PdCl2(PhCN)2 were purchased from Aldrich Chemical
Co. and used as received. Ligand 9a12 and tris(diphenyl-
phosphinoethyl)amine13 were prepared as reported. Column
chromatography was performed with the use of silica gel
(70–200 µm) as the stationary phase. All melting points were
determined on a Kofler hot-plate melting point apparatus and
are uncorrected. IR spectra were determined as Nujol mulls
or films on a Nicolet Impact 400 spectrophotometer. NMR
spectra were recorder at 25 ЊC on a Bruker AC200 (200 MHz)
4H, Ph2), 7.55–7.66 (m, 2H, Ph2), 7.80–7.86 (m, 4H, Ph2).
13C{1H} NMR (CDCl3): δ 11.94 (CH2CH3), 28.91 (d, JCP
=
1
82.4 Hz, CH2P), 47.44 (d, 2JCP = 6.5 Hz,CH2N), 55.20 (OCH3),
1
55.28 (CH2CH3), 113.25 (C3), 126.79 (d, JCP = 88.1 Hz, Ci),
3
3
128.47 (d, JCP = 9.9 Hz, C2), 129.27 (d, JCP = 12.2 Hz, Cm),
2
132.89 (d, JCP = 9.9 Hz, Co), 133.18 (Cp), 140.69 (C1), 154.79
(C4). 31P{1H} NMR (CDCl3): δ 25.63. FABϩ-MS m/z (rel. inten-
sity): 584 (Mϩ ϩ 2, 22), 583 (Mϩ ϩ 1, 15), 582 (Mϩ, 18), 408
(Mϩ ϩ 2-PdCl2, 91), 407 (Mϩ ϩ 1-PdCl2, 65), 406 (Mϩ Ϫ PdCl2,
100), 405 (Mϩ Ϫ 1-PdCl2, 72). Anal. calc. for C25H31Cl2N2-
OPPd: C, 51.43; H, 5.35; N, 4.80. Found: C, 51.24; H, 5.49; N,
4.66%.
1
or a Varian Unity 300 (300 MHz). H and 13C chemical shifts
are reported in ppm downfield of internal tetramethylsilane and
31P chemical shifts were externally referenced to 85% H3PO4.
The mass spectra were recorded on a Hewlett-Packard 5993C
spectrometer (EI) or on a VG-Autospec spectrometer (FABϩ
and FABϪ). Microanalyses were performed on a EA 1108 Carlo
Erba instrument. The syntheses and data of ligands 1, 2, 4, 6, 9
and 10 are given in the ESI.†
3d [R1 = 4-CH3OC6H4, R2 = R3 = (CH2)5]. Orange solid (0.17
g, 96%) that was recrystallized from CH2Cl2–n-hexane (orange
prisms); mp (decomp.) 172–174 ЊC. IR (Nujol)/cmϪ1: 1506,
1
1436, 1234, 1120, 1023, 859, 732. H NMR (CD2Cl2): δ 1.54–
1.79 [m, 6H, N(CH2CH2)2CH2], 2.92 (m, 2H, CH2P), 3.09–3.20
[m, 4H, N(CH2CH2)2CH2], 3.64 (s, 3H, OCH3), 4.30 (m, 2H,
CH2N), 6.53 (d, J = 8.9 Hz, 2H, Ar), 7.18 (d, J = 8.9 Hz, 2H,
Ar), 7.50–7.56 (m, 4H, Ph2), 7.63–7.68 (m, 2H, Ph2), 7.76–7.84
(m, 4H, Ph2). 13C{1H} NMR (CD2Cl2): δ 21.09 [N(CH2CH2)2-
Synthesis
General procedure for the synthesis of compounds 3. To a
dry dichloromethane solution (15 mL) of the corresponding
iminophosphorane-amine 2 (0.3 mmol) was added 1 equiv. of
PdCl2(PhCN)2 (0.115 g, 0.3 mmol) under a nitrogen atmos-
phere. The solution was stirred at 25 ЊC for 0.5 h. The solvent
1
CH2], 23.39 [N(CH2CH2)2CH2], 29.03 (d, JCP = 84.1 Hz,
2
CH2P), 46.33 (d, JCP = 5.4 Hz, CH2N), 55.32 (OCH3), 57.41
[N(CH2CH2)2CH2], 113.34 (C3), 126.65 (d, 1JCP = 87.4 Hz, Ci),
3
3
128.05 (d, JCP = 10.4 Hz, C2), 129.42 (d, JCP = 12.2 Hz, Cm),
D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
431

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2
133.03 (d, JCP = 9.9 Hz, Co), 133.60 (br s, Cp), 140.88 (C1),
132.58 (d, 2JCP = 8.7 Hz, 2 Co), 132.86–133.02 (4 Cp), 133.63 (d,
2JCP = 10.4 Hz, 2 Co), 140.40 (C1), 144.97 (C1Ј), 154.81 (C4).
31P{1H} NMR (CDCl3): δ 25.75, 25.98. FABϩ-MS m/z (rel.
intensity): 852 [½(Mϩ–PdCl4) ϩ 2, 99], 851 [½(Mϩ Ϫ PdCl4) ϩ
1, 61], 850 [½(Mϩ Ϫ PdCl4), 100], 849 [½(Mϩ Ϫ PdCl4) Ϫ 1, 65],
815 [½(Mϩ Ϫ PdCl4) Ϫ Cl, 22], 306 (12), 290 (16). Anal. calc.
for C90H98Cl6N6O2P4Pd3: C, 55.39; H, 5.06; N, 4.21. Found: C,
55.25; H, 4.92; N, 4.31%.
155.13 (C4). 31P{1H} NMR (CDCl3): δ 25.28. FABϩ-MS m/z
(rel. intensity): 596 (Mϩ ϩ 2, 8), 594 (Mϩ, 8), 420 (Mϩ
ϩ
2-PdCl2, 42), 419 (Mϩ ϩ 1-PdCl2, 100), 418 (Mϩ Ϫ PdCl2, 48),
417 (Mϩ Ϫ 1-PdCl2, 89). Anal. calc. for C26H31Cl2N2OPPd: C,
52.41; H, 5.24; N, 4.70. Found: C, 52.59; H, 5.36; N, 4.64%.
3e (R1 = 4-CH3OC6H4, R2 = H, R3 = CH3CH2CH2). Orange
solid (0.163 g, 96%) that was recrystallized from CH2Cl2–n-
hexane (orange prisms); mp (decomp.) 198–200 ЊC. IR (Nujol)/
cmϪ1: 1504, 1440, 1237, 1114, 1041, 723, 667. 1H NMR
(CDCl3): δ 0.98 (t, J = 7.3 Hz, 3H, CH2CH2CH3), 2.12 (sextet,
J = 7.3 Hz, 2H, CH2CH2CH3), 2.62–2.88 (m, 3H, CH2), 3.07–
3.17 (m, 2H, CH2), 3.43 (m, 1H, CH2), 3.62 (s, 3H, OCH3), 4.84
(m, 1H, NH), 6.50 (d, J = 8.7 Hz, 2H, Ar), 7.13 (d, J = 8.7 Hz,
2H, Ar), 7.31–7.36 (m, 4H, Ph2), 7.43–7.65 (m, 4H, Ph2), 8.26–
8.33 (m, 2H, Ph2). 13C{1H} NMR (CDCl3): δ 11.57 (CH2-
5b (R1 = R2 = 4-CH3OC6H4, R3 = CH3CH2CH2). Yield (0.55
g, 92%); mp 184–186 ЊC. IR (Nujol)/cmϪ1: 1506, 1437, 1240,
1
1112, 1042, 669. H NMR (CDCl3): δ 1.16 (t, J = 7.2 Hz, 3H,
CH2CH2CH3), 2.66 (m, 2H, CH2CH2CH3), 3.48–3.65 (m, 6H,
CH2CH2CH3ϩ 2 CHAHBP ϩ 2 CHAHBN), 3.60 (s, 6H, OCH3),
4.05 (m, 2H, 2 CHAHBP), 4.55 (m, 2H, 2 CHAHBN), 6.50
(d, J = 8.7 Hz, 4H, H-3), 7.04 (d, J = 8.7 Hz, 4H, H-2), 7.22–7.26
(m, 8H, Ph2), 7.36–7.42 (m, 2H, Ph2), 7.49–7.61 (m, 6H, Ph2),
8.20–8.27 (m, 4H, Ph2). 13C{1H} NMR (CDCl3): δ 12.00
(CH2CH2CH3), 20.59 (CH2CH2CH3), 31.68 (d, 1JCP = 80.6 Hz,
1
CH2CH3), 22.19 (CH2CH2CH3), 30.97 (d, JCP = 82.3 Hz,
CH2P), 42.97 (d, JCP = 5.8 Hz, CH2N), 55.26 (OCH3), 56.49
2
1
2
(CH2CH2CH3), 113.45 (C3), 124.18 (d, JCP = 87.3 Hz, Ci),
CH2P), 54.53 (d, JCP = 6.4 Hz, CH2N), 55.27 (OCH3), 68.46
1
3
1
127.22 (d, JCP = 89.0 Hz, Ci), 127.52 (d, JCP = 10.8 Hz, C2),
(CH2CH2CH3), 113.70 (C3), 124.68 (d, JCP = 88.2 Hz, Ci),
3
3
3
1
129.22 (d, JCP = 10.9 Hz, Cm), 129.44 (d, JCP = 11.3 Hz, Cm),
132.59 (d, 2JCP = 8.9 Hz, Co), 133.11 (br s, Cp), 133.41 (br s, Cp),
133.52 (d, 2JCP = 10.7 Hz, Co), 140.53 (C1), 154.56 (C4). 31P{1H}
NMR (CDCl3): δ 24.44. FABϩ-MS m/z (rel. intensity): 570 (Mϩ
ϩ 2, 17), 569 (Mϩ ϩ 1, 23), 568 (Mϩ, 19), 394 (Mϩ ϩ 2-PdCl2,
32), 393 (Mϩ ϩ 1-PdCl2, 100), 392 (Mϩ Ϫ PdCl2, 37), 391 (Mϩ
Ϫ 1-PdCl2, 95). Anal. calc. for C24H29Cl2N2OPPd: C, 50.59; H,
5.13; N, 4.92. Found: C, 50.72; H, 5.40; N, 4.79%.
127.68 (d, JCP = 11.0 Hz, C2), 128.20 (d, JCP = 89.9 Hz, Ci),
3 3
128.90 (d, JCP = 12.2 Hz, Cm), 129.40 (d, JCP = 12.8 Hz, Cm),
132.62 (d, 2JCP = 9.3 Hz, Co), 132.88 (br s, Cp), 133.01 (br s, Cp),
133.62 (d, 2JCP = 11.0 Hz, Co), 140.46 (C1), 154.75 (C4). 31P{1H}
NMR (CDCl3): δ 25.89. FABϩ-MS m/z (rel. intensity): 868
[½(Mϩ Ϫ PdCl4) ϩ 2, 99], 867 [½(Mϩ Ϫ PdCl4) ϩ 1, 67], 866
[½(Mϩ Ϫ PdCl4), 100], 865 [½(Mϩ Ϫ PdCl4) Ϫ 1, 64], 833
[½(Mϩ Ϫ PdCl4) Ϫ Cl, 18], 417 (35), 334 (96), 322 (26). Anal.
calc. for C90H98Cl6N6O4P4Pd3: C, 54.49; H, 4.98; N, 4.24.
Found: C, 54.61; H, 5.11; N, 4.32%.
3f [R1 = 4-NO2C6H4, R2 = R3 = (CH2)5]. Orange solid (0.17 g,
93%) that was recrystallized from CH2Cl2 (orange prisms); mp
(decomp.) 195–197 ЊC. IR (Nujol)/cmϪ1: 1504, 1497, 1295,
1283, 1112, 732. 1H NMR (CDCl3): δ 1.46–1.72 [m, 6H, N(CH2-
CH2)2CH2], 2.95–3.1 [m, 6H, CH2P ϩ N(CH2CH2)2CH2], 4.19
(m, 2H, CH2N), 7.36 (d, J = 9.0 Hz, 2H, Ar), 7.52–7.55 (m, 4H,
Ph2), 7.63–7.72 (m, 6H, Ph2), 7.78 (d, J = 9.0 Hz, 2H, Ar).
31P{1H} NMR (CDCl3): δ 30.26. FABϩ-MS m/z (rel. intensity):
611 (Mϩ ϩ 2, 5), 609 (Mϩ, 5), 435 (Mϩ ϩ 2-PdCl2, 93), 434
Synthesis of complex 8. A solution of 2 equiv. of PdCl2-
(PhCN)2 (0.23 g, 0.6 mmol) in dry dichloromethane was added
slowly, under a nitrogen atmosphere, to a dry dichloromethane
solution (15 mL) of tris(iminophosphorane)
6 (0.29 g,
0.3 mmol). The solution was stirred at 25 ЊC for 0.5 h. The
solvent was removed under vacuum and the residue was treated
with dry diethyl ether to give 8 as a red solid which was isolated
by filtration and dried under reduced pressure. An analytically
pure sample was obtained by recrystallization from CH2Cl2–n-
pentane (red prisms). Yield (0.37 g, 94%); mp 199–201 ЊC. IR
(Mϩ ϩ 1-PdCl2, 48), 433 (Mϩ Ϫ PdCl2, 100), 432 (Mϩ
1-PdCl2, 54). Anal. calc. for C25H28Cl2N3O2PPd: C, 49.16; H,
4.62; N, 6.88. Found: C, 49.01; H, 4.49; N, 7.01%.
Ϫ
1
General procedure for the synthesis of compounds 5. To a dry
dichloromethane solution (15 mL) of the corresponding
bis(iminophosphorane) 4 (0.3 mmol) was added 1.5 equiv. of
PdCl2(PhCN)2 (0.17 g, 0.45 mmol) under a nitrogen atmos-
phere. The solution was stirred at 25 ЊC for 0.5 h. The solvent
was removed under vacuum and the residue was treated with
dry diethyl ether to give 5 as a red solid which was isolated by
filtration and dried under reduced pressure. Analytically pure
samples were obtained by recrystallization from CH2Cl2–
n-pentane (red prisms).
(Nujol)/cmϪ1: 1504, 1439, 1252 (m), 1111, 845, 722, 692. H
NMR (CD2Cl2): δ 2.09 (s, 6H, CH3), 2.12 (s, 3H, CH3), 2.97–
3.07 (m, 2H, CH2), 3.45–3.58 (m, 2H, CH2), 3.69–3.83
(m, 2H, CH2), 4.03–4.27 (m. 4H, CH2), 5.40 (m, 2H, CH2), 6.66
(d, J = 8.1 Hz, 4H, Ar), 6.77 (d, J = 8.4 Hz, 2H, Ar), 6.96 (d,
J = 8.1 Hz, 4H, Ar), 7.25–7.39 (m, 8H, Ph2), 7.41–7.48 (m, 6H,
Ph2), 7.54–7.75 (m, 8H, Ph2), 7.73 (d, J = 8.4 Hz, 2H, Ar),
7.99–8.15 (m, 8H, Ph2). 13C{1H} NMR (CD2Cl2): δ 20.26
(CH3), 20.46 (2 CH3), 32.18 (d, 1JCP = 82.4 Hz, 2 CH2P), 33.47
1
2
(d, JCP = 79.5 Hz, CH2P), 57.26 (d, JCP = 6.4 Hz, 2 CH2N),
5a (R1 = 4-CH3C6H4, R2 = 4-CH3OC6H4, R3 = CH3CH2CH2).
60.30 (CH2N), 123.44 (d, JCP = 89.9 Hz, 2 Ci), 125.03
1
Yield (0.51 g, 87%); mp 170–172 ЊC. IR (Nujol)/cmϪ1: 1504,
(d, 1JCP = 87.6 Hz, 2 Ci), 125.39 (d, 3JCP = 12.2 Hz, C2), 126.77
(d, 2JCP = 11.0 Hz, 2 C2), 127.02 (d, 1JCP = 86.5 Hz, 2 Ci), 128.62
(br s, 3 C3), 129.12–129.69 (m, Cm), 131.50 (br s, 3 C4), 133.06–
133.92 (m, Co ϩ Cp), 144.67 (2 C1), 145.93 (C1). 31P{1H} NMR
(CDCl3): δ 27.82 (2 P), 29.51 (1 P). FABϩ-MS m/z (rel. inten-
sity): 1109 (Mϩ Ϫ PdCl3, 48), 1074 (Mϩ Ϫ PdCl4, 15), 307 (100).
FABϪ-MS m/z (rel. intensity): 1320 (MϪ, 3), 188 (100). Anal.
calc. for C63H63Cl4N4P3Pd2: C, 57.16; H, 4.80; N, 4.23. Found:
C, 57.06; H, 4.68; N, 4.12%.
1
1439, 1265, 1241, 1114, 996, 834, 666 (m). H NMR (CDCl3):
δ 1.18 (t, J = 7.2 Hz, 3H, CH2CH2CH3), 2.11 (s, 3H, CH3),
2.59 (m 1H, CH2CH2CH3), 2.73 (m, 1H, CH2CH2CH3),
3.45–3.77 (m, 6H, CH2CH2CH3ϩ 2 CHAHBP ϩ 2 CHAHBN),
3.61 (s, 3H, OCH3), 3.88–4.17 (m, 2H, 2 CHAHBP), 4.40–
4.60 (m, 2H, 2 CHAHBN), 6.52 (d, J = 8.8 Hz, 2H, H-3),
6.76 (d, J = 8.2 Hz, 2H, H-3Ј), 7.06 (d, J = 8.2 Hz, 4H, H-2 ϩ
H-2Ј), 7.23–7.30 (m, 8H, Ph2), 7.38–7.46 (m, 2H, Ph2),
7.51–7.64 (m, 6H, Ph2), 8.17–8.32 (m, 4H, Ph2). 13C{1H}
NMR (CDCl3): δ 11.97 (CH2CH2CH3), 20.54 (CH2CH2CH3),
General procedure for the synthesis of compounds 11. To a dry
dichloromethane solution (15 mL) of the corresponding
iminophosphorane-phosphane 9 (0.3 mmol) was added 1 equiv.
of PdCl2(PhCN)2 (0.115 g, 0.3 mmol) under a nitrogen atmos-
phere. The solution was stirred at 25 ЊC for 0.5 h. The solvent
was removed under vacuum and the residue was treated with
dry diethyl ether to give 10 as a yellow solid which was isolated
by filtration and dried under reduced pressure. Analytically
1
1
20.72 (CH3), 31.40 (d, JCP = 78.9 Hz, CH2P), 32.45 (d, JCP
78.9 Hz, CH2P), 54.48 (2 CH2N), 55.26 (OCH3), 68.56
=
1
(CH2CH2CH3), 113.70 (C3), 124.51 (d, JCP = 87.6 Hz, Ci),
1
3
124.89 (d, JCP = 88.2 Hz, Ci), 126.10 (d, JCP = 11.6 Hz, C2Ј),
1
1
127.07 (d, JCP = 97.9 Hz, Ci), 127.54 (d, JCP = 87.0 Hz, Ci),
3
3
128.05 (d, JCP = 10.4 Hz, C2), 128.98 (C3Ј)129.02 (d, JCP
=
3
12.2 Hz, 2 Cm), 129.36 (d, JCP = 14.5 Hz, 2 Cm), 130.87 (C4Ј),
D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
432

View Article Online
Table 3 Crystallographic data for compounds 3c, 5b and 11b
3cؒ0.5CH2Cl2
5bؒ10CH2Cl2
11bؒ2CH2Cl2
Empirical formula
Formula weight
Temperature/K
Wavelength/Å
Crystal system
Space group
a/Å
b/Å
c/Å
C25.50H32Cl3N2OPPd
626.25
173(2)
0.71073
Monoclinic
C2/c
21.920(2)
19.798(2)
16.2440(10)
129.06
5473.8(8)
8
1.051
2552
C95H108Cl16N6O4P4Pd3
2408.15
133(2)
0.71073 Å
Monoclinic
P21/n
22.316(2)
25.460(3)
36.865(4)
101.293(5)
20540(4)
8
1.051
9776
C30H30Cl6N2P2Pd
799.60
173(2)
0.71073
Orthorhombic
Pbca
13.6655(12)
22.307(2)
22.333(2)
90
β/Њ
Volume/Å3
6808.1(10)
8
1.134
Z
Absorption coefficient/mmϪ1
F(000)
3216
Crystal size/mm
Reflections collected
Independent reflections
Refinement method
Data/restraints/parameters
Final R indices [I > 2σ(I )]a
R indices (all data)b
Absorption correction
0.38 × 0.25 × 0.11
5260
4821 [R(int) = 0.0361]
Full-matrix least-squares on F 2
4820/250/323
R1 = 0.0458, wR2 = 0.1151
R1 = 0.0685, wR2 = 0.1252
Psi-scans
0.55 × 0.28 × 0.10
277026
0.30 × 0.20 × 0.10
6894
5990 [R(int) = 0.0317]
Full-matrix least-squares on F 2
5990/0/360
R1 = 0.0378, wR2 = 0.0510
R1 = 0.0852, wR2 = 0.0585
—
50104 [R(int) = 0.0505]
Full-matrix-block least-squares on F 2
50104/1858/2306
R1 = 0.0598, wR2 = 0.1470
R1 = 0.1069, wR2 = 0.1777
Semi-empirical from equivalents
2
2
a R1 = Σ||Fo| Ϫ |Fc||/Σ|Fo| for reflections with I > 2σ(I ). b wR2 = [Σ[w(Fo Ϫ Fc2)2]/Σ[w(Fo )2]0.5 for all reflections; wϪ1 = σ2(F 2) ϩ (aP)2 ϩ bP, where
2
P = (2Fc2 ϩ Fo )/3 and a and b are constants set by the program.
pure samples were obtained by recrystallization from dichloro-
methane (yellow prisms).
solution was stirred at 25 ЊC for 0.5 h. The solvent was removed
under vacuum and the residue was treated with dry diethyl
ether to give 12 as a red solid which was isolated by filtration
and dried under reduced pressure. After recrystallization from
dichloromethane–n-pentane an analytically pure sample was
obtained in 91% yield. Mp 154–156 ЊC. IR (Nujol)/cmϪ1: 1503,
1441, 1236, 1120, 753, 720. 1H NMR (CDCl3): δ 2.92 (m,
2H, CH2), 3.20 (m, 2H, CH2), 3.60 (s, 3H, OCH3), 6.46 (d,
J = 8.9 Hz, 2H, Ar), 6.98 (dd, 3JHH = 8.9 Hz, HAr, JHP = 1.3 Hz,
2H, Ar), 7.38–7.50 (m, 7H, Ph2 ϩ PhS), 7.56–7.61 (m, 2H,
Ph2), 7.69–7.76 (m, 4H, Ph2), 8.03–8.06 (m, 2H, PhS). 13C{1H}
11a (R = 4-CH3OC6H4). Yield (0.19 g, 92%); mp 202–204 ЊC.
IR (Nujol)/cmϪ1: 1504, 1436, 1239, 1113, 724, 693, 665. 1H
NMR (CDCl3): δ 2.66 (m, 2H, CH2), 2.88 (m, 2H, CH2), 3.61 (s,
3
3H, OCH3), 6.43 (dd, JHH = 8.9 Hz, JHP = 0.5 Hz, 2H, Ar),
3
6.84 (dd, JHH = 8.9 Hz, JHP = 1.3 Hz, 2H, Ar), 7.44–7.58 (m,
10H, Ph2), 7.61–7.67 (m, 2H, Ph2), 7.81–7.96 (m, 8H, Ph). 13C
{1H} NMR (CDCl3): δ 18.67 [dd, 1JCP() = 33.6 Hz, 2JCP() = 6.4
1
Hz, CH2P()], 25.01 [d, JCP() = 77.1 Hz, CH2P()], 55.16
1
(OCH3), 113.14 (C3), 126.94 (d, JCP = 92.8 Hz, Ci), 128.83 (d,
3
1
3JCP = 11.6 Hz, Cm), 129.30 (d, JCP = 12.2 Hz, Cm), 129.43
NMR (CDCl3): δ 28.41 (d, JCP = 79.5 Hz, CH2P), 29.87
3
4
2
(d, JCP = 7.5 Hz, C2), 131.70 (d, JCP = 2.3 Hz, Cp), 132.91
(d, JCP = 7.5 Hz, CH2S), 55.34 (OCH3), 114.46 (C3), 126.67
2
4
1
3
(d, JCP = 9.9 Hz, Co), 133.42 (d, JCP = 2.3 Hz, Cp), 133.60 (d,
2JCP = 10.4 Hz, Co), 139.98 (C1), 155.39 (C4). One Ci not
(d, JCP = 92.2 Hz, Ci), 129.53 (d, JCP = 12.8 Hz, Cm), 129.75
3
(d, JCP = 7.0 Hz, C2), 129.80 (CH), 130.80 (CH), 132.97 (d,
observed. 31P{1H} NMR (CDCl3): δ 23.78 [d, JPP = 11.0 Hz,
2JCP = 9.9 Hz, Co), 133.19 (CH), 133.74 (d, JCP = 2.5 Hz, Cp),
3
4
P()], 27.36 [d, 3JPP = 11.0 Hz, P()]. FABϩ-MS m/z (rel. inten-
sity): 662 (Mϩ ϩ 2-Cl, 97), 661 (Mϩ ϩ 1 Ϫ Cl, 50), 660 (Mϩ Ϫ
Cl, 100), 659 (Mϩ Ϫ 1 Ϫ Cl, 66), 625 (Mϩ Ϫ 2Cl, 69), 519 (Mϩ
Ϫ PdCl2, 15). Anal. calc. for C33H31Cl2NOP2Pd: C, 56.88; H,
4.48; N, 2.01. Found: C, 57.02; H, 4.63; N, 2.15%.
139.71 (C1Ј), 152.47 (C1), 155.83 (C4).31P{1H} NMR (CDCl3):
δ 25.73. FABϩ-MS m/z (rel. intensity): 642 (Mϩ ϩ Na, 6), 640
(Mϩ ϩ Na Ϫ 1, 8), 444 (Mϩ ϩ 1 Ϫ PdCl2, 16), 289 (22), 136
(100). Anal. calc. for C27H26Cl2NOPPdS: C, 52.23; H, 4.22; N,
2.26. Found: C, 52.31; H, 4.08; N, 2.12%.
11b (R = NC–CH2). Yield (0.18 g, 95%); mp 212–214 ЊC. IR
(Nujol)/cmϪ1: 2342, 1438, 1158, 1119, 1102, 869, 724, 665. H
1
X-Ray structure determinations
NMR (CDCl3): δ 2.60–2.71 (m, 4H, PCH2CH2P), 4.06 (d, 3JHP
= 19.2 Hz, 2H, CH2N), 7.31–7.37 (m, 4H, Ph2), 7.43–7.49 (m,
2H, Ph2), 7.53–7.59 (m, 4H, Ph2), 7.65–7.79 (m, 10H, Ph2).
X-Ray intensities of compounds 3c and 11b were measured on
a Siemens P4 instrument with a LT2 low-temperature attach-
ment. Compound 5b was measured on a Bruker SMART 1000
CCD/LT3 machine. Data were collected using monochromated
Mo-Kα radiation in ω (3c and 5b) and ω/θ (11b) modes.
The structures were solved by direct methods, and all
were refined anisotropically on F 2 (compound 5b program
SHELX-97; 3c and 11b program SHELX-93, G. M. Sheldrick.
University of Göttingen). Restraints to local aromatic ring
symmetry or light atom displacement factor components were
applied in some cases. Hydrogens were refined using a riding
method. Full details are given in Table 3.
Particular features: 3c contains half a disordered dichloro-
methane molecule; 5b contains ten dichloromethane molecules,
one of them disordered; and11b contains two dichloromethane
molecules.
CCDC reference numbers 194361–194363.
See http://www.rsc.org/suppdata/dt/b2/b209242e/ for crystal-
lographic data in CIF or other electronic format.
13C{1H} NMR (CDCl3): δ 19.81 [dd, 1JCP() = 32.5 Hz, 2JCP()
=
1
5.7 Hz, CH2P()], 25.29 [d, JCP() = 72.5 Hz, CH2P()], 38.65
(CH2N), 120.29 [d, 3JCP() = 5.0 Hz, CN], 126.55 (d, 1JCP = 132.8
Hz, Ci), 127.57 (d, 1JCP = 95.3 Hz, Ci), 128.81 (d, 3JCP = 11.6 Hz,
Cm), 129.93 (d, 3JCP = 12.8 Hz, Cm), 131.92 (d, 4JCP = 2.9 Hz, Cp),
2
2
132.66 (d, JCP = 10.4 Hz, Co), 134.01 (d, JCP = 10.4 Hz, Co),
134.34 (d, 4JCP = 2.9 Hz, Cp). 31P{1H} NMR (CDCl3): δ 22.49 [d,
3JPP = 14.9 Hz, P()], 36.95 [d, 3JPP = 14.9 Hz, P()]. FABϩ-MS
m/z (rel. intensity): 595 (Mϩ ϩ 2 Ϫ Cl, 95), 594 (Mϩ ϩ 1 Ϫ Cl,
60), 593 (Mϩ Ϫ Cl, 100), 592 (Mϩ Ϫ 1 Ϫ Cl, 83), 558 (Mϩ
Ϫ
2Cl, 62), 452 (Mϩ–PdCl2, 32). Anal. calc. for C28H26Cl2N2P2Pd:
C, 53.40; H, 4.16; N, 4.45. Found: C, 53.32; H, 4.29; N, 4.58%.
Synthesis of complex 12. A solution of PdCl2(PhCN)2 (0.115
g, 0.3 mmol) in dry dichloromethane (5 mL) was added to a dry
dichloromethane solution (15 mL) of the iminophosphorane-
sulfide 10 (0.133 g, 0.3 mmol) under a nitrogen atmosphere. The
D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
433

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Acknowledgements
This work was supported by MCYT and FEDER (Project
BQU2001–0010) and Fundación Séneca-CARM (Project PI-1/
00749/FS/01). P. L.-L. thanks Fundación Séneca-CARM for a
fellowship.
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D a l t o n T r a n s . , 2 0 0 3 , 4 2 6 – 4 3 4
434