Mono- and di-nuclear complexes of ortho-palladated and -platinated 4,4′-dimethylazobenzene with bis(diphenylphosphino)methane More data on transphobia

Article abstract of DOI:10.1016/S0022-328X(02)01729-1

Complexes [Pd(κ²-R)(μ-Cl)]₂ [κ²-R = is(diphenylphosphino)methane (2)] have been used to prepare new palladium derivatives containing dppm. Thus, complex 1 reacts with one equivalent of dppm to afford [{Pd(κ²-R)Cl}₂(μ-dppm)] (3) and with AgClO₄ and dppm (1:2:2 molar ratios) to give [Pd(κ²-R)(κ²-dppm)]ClO₄ (4·ClO₄). The triflate salt of this complex (4·TfO) reacts with PPh₃ to yield [Pd(κ¹-R)(PPh₃)(k²-dppm)]TfO (5). Dinuclear complexes were obtained by reacting 2, (i) with [AuCl(PPh₃)] or [AuCl(tht)] (tht = tetrahydrothiophene) (1:1, -60 °8C) and (ii) with 1 (2:1) to give, respectively, [Pd(κ¹-R)Cl(μ-dppm)₂Au] TfO (6) and the A-frame complex [{Pd(κ¹-R) (μ-dppm)} ₂(μ-Cl)]TfO (7). The latter decomposes in solution to give, among other products, [Pd(κ²-R) (κ²-P,O-dppmO)]TfO (8), containing the monoxide of dppm (dppmO). Complex 8 can be obtained by refluxing a toluene solution of 4ΤfO under aerial conditions. The platinum complex trans -[Pt(κ¹-R)Cl(PPh₃)₂] reacts with an excess of dppm to give [Pt(κ¹-R) (κ¹-dppm)(κ²-dppm)]Cl (10·Cl) which reacts with TlOTf to give 10Τ.fO. The crystal structures of complexes 3, 8 and 10·TfO have been determined by Xray diffraction studies. The structure of complex 3 consists of a dimer formed by a dppm ligand bridging two Pd(κ²-R)Cl units. The structure of the cation of complex 8 shows both the aryl and dppmO acting as chelating ligands with the O atom trans to the C atom. The structure of 10·TfO shows the κ¹-R ligand, one chelating and one monocoordinate dppm ligand.

Full text of DOI:10.1016/S0022-328X(02)01729-1

Journal of Organometallic Chemistry 663 (2002) 164ꢃ172
/
www.elsevier.com/locate/jorganchem
Mono- and di-nuclear complexes of ortho-palladated and -platinated
4,4?-dimethylazobenzene with bis(diphenylphosphino)methane. More
data on transphobia
Jose´ Vicente a,ꢀ, Aurelia Arcas a, Delia Bautista a, M. Carmen Ram´ırez de Arellano b,ꢀ
a
´ ´ ´ ´ ´
Grupo de Quımica Organometalica, Departamento de Quımica Inorganica, Facultad de Quımica, Universidad de Murcia, Apartado 4021, Murcia
30071, Spain
´ ´
Departamento de Quımica Organica, Facultad de Farmacia, Universidad de Valencia, 46100 Valencia, Spain
b
Received 31 May 2002; accepted 18 July 2002
Dedicated to Professor Pascual Royo on the occasion of his 65th birthday
Abstract
Complexes [Pd(k2-R)(m-Cl)]2 [k2-Rꢁ
[dppmꢁbis(diphenylphosphino)methane (2)] have been used to prepare new palladium derivatives containing dppm. Thus, complex
1 reacts with one equivalent of dppm to afford [{Pd(k2-R)Cl}2(m-dppm)] (3) and with AgClO4 and dppm (1:2:2 molar ratios) to give
[Pd(k2-R)(k2-dppm)]ClO4 (4× TfO) reacts with PPh3 to yield [Pd(k1-R)(PPh3)(k2-
ClO4). The triflate salt of this complex (4×
dppm)]TfO (5). Dinuclear complexes were obtained by reacting 2, (i) with [AuCl(PPh3)] or [AuCl(tht)] (thtꢁtetrahydrothiophene)
(1:1, ꢂ
60 8C) and (ii) with 1 (2:1) to give, respectively, [Pd(k1-R)Cl(m-dppm)2Au]TfO (6) and the A-frame complex [{Pd(k1-R)(m-
dppm)}2(m-Cl)]TfO (7). The latter decomposes in solution to give, among other products, [Pd(k2-R)(k2-P,O-dppmO)]TfO (8),
containing the monoxide of dppm (dppmO). Complex 8 can be obtained by refluxing a toluene solution of 4×TfO under aerial
conditions. The platinum complex trans-[Pt(k1-R)Cl(PPh3)2] reacts with an excess of dppm to give [Pt(k1-R)(k1-dppm)(k2-dppm)]Cl
/
k2-C,N?-C6H3(Nꢀ
/
NC6H4ꢁ
/
Me-4?)-2-Me-5 (1)] and [Pd(k1-R)Cl(k1-dppm)(k2-dppm)]TfO
/
/
/
/
/
/
(10×
/
Cl) which reacts with TlOTf to give 10×
/
TfO. The crystal structures of complexes 3, 8 and 10×
/
TfO have been determined by X-
ray diffraction studies. The structure of complex 3 consists of a dimer formed by a dppm ligand bridging two Pd(k2-R)Cl units. The
structure of the cation of complex 8 shows both the aryl and dppmO acting as chelating ligands with the O atom trans to the C
atom. The structure of complex 10×
TfO shows the k1-R ligand, one chelating and one monocoordinate dppm ligand.
# 2002 Elsevier Science B.V. All rights reserved.
/
Keywords: Palladium complexes; Platinum complexes; Transphobia
1. Introduction
[6ꢃ18]. This ligand has a bite size suitable to hold two
/
metals atoms in close proximity and hence promote
reactions involving two metal centers [8,10,13,19]. Such
reactions are often invoked in catalysis. The role of the
phosphine is to prevent dissociation of dimer to mono-
mer, to promote bridging by other groups and reactions
The chemistry of the bis(diphenylphosphino)methane
ligand (dppm) has developed tremendously over the last
25 years due its ability to act as a mono- or di-
coordinating ligand as well as to adopt a chelating or
bridging mode leading to the synthesis of di-, tri- or
involving formation and cleavage of metalꢃmetal bonds
/
poly-, homo- or hetero-nuclear complexes [1ꢃ5]. The
interest in the synthesis of palladium(II) and plati-
num(II) dppm complexes persists in the recent literature
/
[1]. In this paper, we describe the preparation of new
organo-palladium and -platinum complexes with dppm.
We have reported the use of the orthopalladation
products of azotoluene and azobenzene, [Pd(k2-R)(m-
Cl)]2
R?ꢁ
phosphino, perchlorato, triflato and aquo-2-(aryla-
(Rꢁ
/
k2-C,N?-C6H3(Nꢀ
/
NC6H4ꢁR?-4?)-2-R?-5,
H, Me), in the synthesis of a family of palladium
/
ꢀ Corresponding authors. http://www.scc.um.es/gi/gqo/
E-mail addresses: jvs@um.es (J. Vicente), mcra@uv.es (M.C.
Ram´ırez de Arellano).
/
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 7 2 9 - 1

J. Vicente et al. / Journal of Organometallic Chemistry 663 (2002) 164ꢃ
/172
165
zo)aryl palladium complexes [20] and a new method of
synthesis of iminophosphorane complexes which result
from the attack of organic azides at the noncoordinated
phosphorus atom in the complex [Pd(k1-R)(k1-P-
dppm)(k2-P,P-dppm)]TfO
(k1-Rꢁ
/
k1-C-C6H3(Nꢀ
/
NC6H4ꢁMe-4?)-2-Me-5) [21]. In this paper, we describe
/
an extension of the use of these complexes to the
preparation of new azotoluene palladium complexes
with dppm. In particular, we describe the synthesis of
mononuclear and dinuclear complexes, including homo-
bimetallic complexes (one of them is an A-frame species
that contain a Cl bridging ligand) and a heterobimetallic
complex with palladium and gold. The only reported
heterobimetallic compounds containing dppm and gold
are platinum complexes [15,22ꢃ
synthesis of some azotolyl platinumꢁ
Diphosphine monoxides (R1R2Pꢁ
Yꢁ
/
27]. We also report the
dppm complexes.
P(O)R3R4, Yꢁ
/
/
/
/
divalent spacer) constitute one of the most important
classes of hemilabile ligands [28,29]. Grushin has
recently reported a highly selective Pd-catalyzed mono-
oxidation of diphosphines, including dppm [30]. We
reported the first aerial mono-oxidation of dppm from a
complex containing a chelating dppm [20] and explained
the selective oxidation of the phosphorus atom trans to
the aryl ligand as a consequence of the arylꢃphosphine
/
transphobia, a term that we proposed and that have
been used for many authors since then [20,31,32].
Afterwards, we have described the insertion of oxygen
Scheme 1.
When a CH2Cl2 solution of complex 2 was treated at
room temperature with [AuCl(PPh3)] in a 1:1 molar
ratio, a mixture of compounds that could not be
separated was obtained. When this reaction was carried
out in the presence of TlOTf in acetone as solvent (1:1
molar ratio), and the resulting mixture was separated by
crystallization, the products [Au(dppm)]2(TfO)2 and
into a Cꢁ
/
Pd bond trans to a P-donor ligand [32]. In this
paper we report a new example of a selective aerial
mono-oxidation of chelating dppm and new data on
transphobia.
2. Results
We have reported that complex [Pd(k2-R)(m-Cl)]2 [k2-
Rꢁ
/
k2-C,N?-C6H3(Nꢀ
/
NC6H4ꢁ
/
Me-4?)-2-Me-5]
(1)
(Scheme 1)] reacts with bis(diphenylphosphino)methane
(dppm) to give trans-[Pd(k1-R)Cl(k1-dppm)2] [k1-Rꢁ
k1-C-C6H3(Nꢀ
NC6H4ꢁMe-4?)-2-Me-5] that in turn re-
acts with TlOTf (TfOꢁCF3SO3) in an 1:1 molar ratio
/
/
/
/
to give [Pd(k1-R)(k1-dppm)(k2-dppm)]TfO (2) [20].
Now, we describe that treatment of a CH2Cl2 suspen-
sion of 1 with one equivalent of dppm affords complex
[{Pd(k2-R)Cl}2(m-dppm)] (3). This complex does not
react with TlOTf but it does with AgClO4 to give a
mixture that, according to its 1H- and 31P-NMR spectra,
contains mainly [Pd(k2-R)(k2-dppm)]ClO4 (4×
another product that could not be separated. However,
4×ClO4 could be obtained by treating 1 with AgClO4
and dppm (1:2:2 molar ratios). We have previously
reported the preparation of complexes 4×X (XꢁSbF6,
TfO [20]. The
/ClO4) and
/
/
/
TfO), and the crystal structure of 4×
/
analogous complex derived from azobenzene has been
reported [33].
Scheme 2.

166
J. Vicente et al. / Journal of Organometallic Chemistry 663 (2002) 164ꢃ172
/
[Pd(k1-R)(PPh3)(k2-dppm)]TfO (5) (see Scheme 2) were
obtained. Complex 5 can also be obtained by reacting 4×
of the complex similar to 8 derived from azobenzene was
obtained when attempting to obtain single crystals of
/
[Pd(k2-R?)(k2-dppm)]SbF6 (R?ꢁ
/
C6H4Nꢀ/NPh-2) [20].
TfO with PPh3. Because complex 2 shows at ꢂ60 8C a
/
first-order 31P-NMR spectrum corresponding to the
static structure shown in Scheme 2, we reasoned that
In both cases, the oxidation takes place at the phospho-
rus atom trans to the aryl ligand. This unusual reactivity
and the selectivity observed can be explained as a
consequence of the high transphobia of aryl and P-
donor ligands [20,31,32].
at ꢂ
/
60 8C an 1:1 reaction of 2 with a gold complex like
tetrahydrothiophene)
[AuCl(PPh3)] or [AuCl(tht)] (thtꢁ
/
could give an heterodinuclear complex avoiding the
interchange process observed in the previous reaction.
In accord with our expectation, such reaction led to
[Pd(k1-R)Cl(m-dppm)2Au]TfO (6), which was character-
ized by elemental analysis, NMR spectroscopy and
FABꢄ. We are not aware of related ‘Pd(m-dppm)2Au’
We attempted to prepare a heterobimetallic complex
of palladium and platinum by reacting complex 2 with
[PtCl2(NCMe)2] in acetone at low temperature
(ꢂ60 8C). However, this reaction gave a mixture of
/
compounds, which we could not separate. In this
1
mixture was detected (by H- and 31P-NMR spectro-
complexes but heterobimetallic platinumꢃ
and ꢃmercury complexes have been reported [15,22ꢃ
27,34].
/
gold, ꢃsilver
/
scopy) [PdRCl(m-dppm)]2 [20], [PtCl2(dppm)] and a little
amount of [PdCl2(dppm)].
/
/
When an excess of dppm was added to trans-[Pt(k1-
R)Cl(PPh3)2] (9), which we prepared from [Hg(k1-R)Cl]
and [Pt(PPh3)3] [20], (Scheme 4), the PPh3 ligand was
The reaction of 2 with 1 (2:1 molar ratio) afforded the
A-frame complex [{Pd(k1-R)(m-dppm)}2(m-Cl)]TfO (7)
(see Scheme 3) which contains a Cl bridge, in agreement
displaced to give [Pt(k1-R)(k1-dppm)(k2-dppm)]Cl (10×
/
1
with its elemental analyses, H- and 31P-NMR spectra.
Cl) which reacts with TlOTf to give 10×/TfO, homo-
A
family of chloro-bridged A-frame complexes
[{RPd(m-dppm)2PdR?}(m-Cl)]ꢄ have been reported.
The symmetric ones with RꢁR?ꢁEt, Bu, CH2Ph and
logous to the palladium complex 2. However, all
attempts to prepare homo- and heterobimetallic plati-
/
/
num(II) complexes from 10×
that could be resolved. The following reactions were
TfO with
/
Cl or 10×/TfO gave mixtures
C6H2Me3 (the latest was characterized by X-diffraction
studies) were obtained by reacting [PdX2(k2-P,P-dppm)]
attempted: 10×
/
Cl with [AuCl3(tht)]; 10×
/
with RMgX (Xꢁ
R?ꢁ
dppm)]ꢄ with [PdCl(Me)(cod)] (codꢁ
/
Cl, Br) [12] and the complex with Rꢁ
/
Me by reacting [PdMe(k1-P-dppm)(k2-P,P-
1,5-cycloocta-
[AuCl3(tht)] or 1 or [PdCl2(NCPh)2] or [AuCl(tht)].
The synthesis of iminophosphorane platinum(II) com-
/
/
plexes was also unsuccessfully attempted by reacting 10×
/
diene) [35]. Using the last method a series of unsymme-
trical complexes were also reported [35].
TfO with N3C6H4Me-4.
In an attempt to obtain single crystals of 7 a few
crystals of [Pd(k2-R)(k2-P,O-dppmO)]TfO (8), contain-
ing the monoxide of dppm (dppmO), were obtained.
This complex could be obtained by refluxing a toluene
3. Discussion
solution of [Pd(k2-R)(k2-dppm)]TfO (4×
/
TfO) under
aerial conditions. We have reported that the SbF6ꢂ salt
3.1. X-ray structure determinations
The crystal structures of complexes 3, 8 and 10×
/
TfO
have been determined by X-ray diffraction (Figs. 1ꢃ
/3;
Tables 1ꢃ4). The molecular structure of 3 consists of a
/
dimer formed by a dppm ligand bridging two Pd(k2-
R)Cl units. The dimer has a two fold symmetry with
Scheme 3.
Scheme 4.

J. Vicente et al. / Journal of Organometallic Chemistry 663 (2002) 164ꢃ
/172
167
Fig. 3. Thermal ellipsoid plot (50% probability level) of 10×
/TfO.
Hydrogen atoms have been omitted for clarity.
sponding bond length in trans-[Pd(k1-R)Cl(k1-dppm)2]
[2.4119(8) A][20] in spite of being both trans to the same
aryl ligand.
˚
Fig. 1. Thermal ellipsoid plot (50% probability level) of 3. Hydrogen
atoms have been omitted for clarity.
The structure of the cation of complex 8 shows both
the aryl and dppmO acting as chelating ligands. As far
as we aware, the only other X-ray crystal structures of
palladium complexes with the dppmO ligand is that of
[Pd(Me)Cl(k2-P,O-dppmO)] [37] and that of the homo-
logous of 8, [Pd(k2-R)(k2-P,O-dppmO)]SbF6 (where R
is derived from azobenzene) [20]. The three structures
show the O atom trans to the C atom. This geometry
can also be explained having in mind the transphobia of
the ligands with P- and C-donor atoms [20,31,32].
The molecular structure of 10×
/
TfO shows a platinum
center with a k1-R ligand, one chelating and one
monocoordinate dppm ligand. The square-planar co-
ordination at platinum is slightly distorted with the
planes determined for P(1)P(2)Pt and P(3)PtC(1) form-
ing an angle of 6.18. The Ptꢁ
/
P bond trans to the aryl
group [2.337(2) A] is longer than those trans to a P atom
˚
˚
[2.299(2) and 2.310(2) A] as a consequence of the
stronger trans influence of the aryl group than the
phosphine ligands. We have reported the crystal struc-
ture of the homologous palladium complex [20]. The
two Mꢁ
[PdꢁCꢁ
bonds lengths are. Thus, the Pdꢁ
2.3592(15) (trans to C), 2.3181(15) and 2.3243(15) A
whereas the corresponding PtꢁP bond lengths in 10×
TfO are shorter: 2.337(2), 2.299(2) and 2.310(2) A,
respectively. These data suggest that, although the scale
of trans influence of ligands does not change with the
metal (that of the aryl ligand is greater than that of
PPh3) its weakening influence depends on the metal. The
above data clearly point that the trans influence of the
aryl ligand, as well as the mutual trans influence of the
phosphorus ligands, are greater in Pd than in Pt. The
/
C bond distances are not significantly different
˚
/
/
2.040(5), Ptꢁ
/
Cꢁ
/
2.058(5) A] but the Mꢁ
/
P
/
P distances are
˚
Fig. 2. Thermal ellipsoid plot (50% probability level) of the cation of
8. Hydrogen atoms have been omitted for clarity.
/
/
˚
respect to the methylene carbon atom of the dppm
ligand. Each Pd atom is in a highly distorted square-
planar coordination with 19.78 dihedral angle between
the ClPdP and N(2)PdC(11) planes. The cis position of
C and P around the palladium atom can be explained as
a consequence of the transphobia of ligands with such
donor atoms [20,31,36]. The Pdꢁ
/
Cl bond length
Mꢁ
/
C bond distances do not appear affected by the
nature of the metal. We have recently concluded,
˚
[2.3941(9) A] is significantly shorter than the corre-

168
J. Vicente et al. / Journal of Organometallic Chemistry 663 (2002) 164ꢃ172
/
Table 1
Crystal data for complexes 3, 8×CH2Cl2 and 10×TfO
Compound
3
8×CH2Cl2
10×TfO
Crystal color
Crystal habit
Orange
Prism
Yellow
Tablet
Orange
Tablet
Triclinic
Crystal system
Space group
Monoclinic
C2/c
Monoclinic
P21/c
¯
P
/1/
Crystal size (mm)
Chemical formula
Unit cell parameters
0.48ꢅ0.24ꢅ0.18
C53H48Cl2N4P2Pd2
0.47ꢅ0.32ꢅ0.14
C41H37Cl2F3N2O4P2PdS
0.26ꢅ0.24ꢅ0.08
C65H57F3N2O3P4PtS
˚
a (A)
17.860(2)
14.985(1)
18.943(2)
90
10.769(1)
21.186(2)
18.147(3)
90
11.610(1)
13.368(2)
19.641(2)
100.145(5)
91.882(7)
105.177(5)
2886.0(6)
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
112.958(7)
90
4668.2(8)
91.38(1)
90
4139.3(8)
3
˚
V (A )
Radiation
˚
l (A)
Moꢃ
/
Ka
Moꢃ
/
Ka
MoꢃKa
/
0.71073
173(2)
4
0.71073
173(2)
4
0.71073
173(2)
2
T (K)8
Z
Diffractometer
Scan method
Number of data collected
Number of unique data
Rint
Siemens P4
v
Siemens P4
v
Siemens P4
v
6191
3089
7906
7268
13 443
10 108
0.0429
50
0.0456
50
0.0439
50
2u max (8)
Absorption correction
C -scans
0.0370
0.0676
284
C -scans
0.0572
0.1430
476
C -scans
0.0416
0.0836
712
a
R1
b
wR2
Number of parameters
Form of refinement
Treatment of hydrogen atoms
F2
F2
F2
Riding
Riding
Riding
a
R1ꢁajjFojꢂjFcjj/ajFoj for reflections with I ꢀ2sI.
b
wR2ꢁ[a[w(Fo2ꢂF2c)2]/a[w(Fo2)2]]0.5 for all reflections; wꢂ1ꢁs2(F2)ꢄ(aP)2ꢄbP, where Pꢁ(2Fc2ꢄFo2)/3 and a and b are constants set by the
program.
Table 2
Table 3
˚
˚
Selected bond lengths (A) and bond angles (8) for compound 3
Selected bond lengths (A) and bond angles (8) for compound 8
Bond lengths
Bond lengths
PdꢁC(11)
PdꢁCl
N(2)ꢁN(1)
PꢁC(41)
1.997(3)
2.3941(9)
1.299(4)
1.828(3)
PdꢁP
2.2729(10)
2.116(3)
1.828(3)
1.842(2)
PdꢁC(1)
1.971(6)
2.163(4)
1.270(7)
1.787(6)
1.821(6)
1.839(6)
PdꢁP(2)
2.262(2)
2.146(5)
1.798(6)
1.811(6)
1.794(6)
PdꢁN(2)
PꢁC(31)
PꢁC(3)
PdꢁO(1)
PdꢁN(2)
N(2)ꢁN(1)
P(1)ꢁC(31)
P(2)ꢁC(51)
P(2)ꢁC(20)
P(1)ꢁC(21)
P(2)ꢁC(41)
P(1)ꢁC(20)
Bond angles
C(11)ꢁPdꢁP
N(2)ꢁPdꢁCl
95.48(10)
97.31(8)
C(11)ꢁPdꢁN(2)
PꢁPdꢁCl
78.67(12)
91.26(3)
Bond angles
C(1)ꢁPdꢁP(2)
N(2)ꢁPdꢁO(1)
94.9(2)
98.7(2)
C(1)ꢁPdꢁN(2)
O(1)ꢁPdꢁP(2)
79.0(2)
87.48(1)
comparing 31P-NMR and X-ray structural data of
isostructural Pd and Pt complexes with the same ligands
3.2. Spectroscopic properties of complexes
(1,1-ethylenedithiolato and PPh3), that the Ptꢁ
/
P bonds
are stronger than their corresponding PdꢁP bonds [38].
/
In agreement with the proposed symmetric structure
of complex 3, the 31P{1H}-NMR spectrum exhibits a
All the above facts are in agreement with the observa-
tion that transphobia of any couple of ligands is greater
in Pd than in Pt complexes and that ligands with great
trans influence show strong transphobia when placed in
trans [20].
singlet at 30.68 ppm and the 1H-NMR spectrum a triplet
2
(5.02, JHP
ꢁ14 Hz) for the methylene protons of the
/
dppm ligand. A related complex shows these resonances
at 30.1 and 4.70 ppm, respectively [17].

J. Vicente et al. / Journal of Organometallic Chemistry 663 (2002) 164ꢃ
/172
169
Table 4
1H-NMR spectrum shows two singlets corresponding to
the methyl groups and a doublet of multiplets for the
methylene hydrogens of the dppm ligand.
˚
Selected bond lengths (A) and bond angles (8) for compound 10×TfO
Bond lengths
The 1H-NMR spectrum of 8 shows a doublet of
PtꢁC(1)
PtꢁP(2)
2.058(5)
2.337(2)
1.251(6)
1.800(6)
1.802(6)
1.817(6)
1.858(7)
1.853(6)
1.870(5)
PtꢁP(1)
PtꢁP(3)
2.299(2)
2.310(2)
1.813(6)
1.812(5)
1.819(5)
1.835(6)
1.827(5)
1.832(5)
2
doublets (4.18, JHP
ꢁ12 and 10 Hz) for the methylene
/
hydrogens of the dppmO ligand. The H- and 31P{1H}-
NMR spectra of 8 are similar to those in the analogous
1
N(1)ꢁN(2)
P(1)ꢁC(31)
P(2)ꢁC(51)
P(3)ꢁC(71)
P(4)ꢁC(91)
P(2)ꢁC(9)
P(4)ꢁC(8)
P(1)ꢁC(21)
P(2)ꢁC(41)
P(3)ꢁC(61)
P(4)ꢁC(81)
P(1)ꢁC(9)
P(3)ꢁC(8)
[Pd(h2-R)(h2-P,O-dppmO)]SbF6 (Rꢁ
/
azobenzene) de-
rivative [20]. The 31P{1H}-NMR spectrum of 8 exhibits
2
two doublets at 55.61 and 33.12 with JPP
ꢁ16 Hz. The
/
first one is attributed to Ph2Pꢀ
assignments reported for cis-[Pd(dppmO)2]ꢄ [59.2
(Ph2Pꢀ
O) and 36.0 (Ph2P) ppm] [39], [Pd(h3-
allyl)(dppmO)]ꢄ [62 (Ph2Pꢀ
O) and 22 (Ph2P) ppm]
and [Pd(Me)Cl(dppmO)] [45 (Ph2PꢀO) and 26.8
(Ph2P) ppm] [37].
The 31P-NMR spectra of the platinum complexes 10×
Cl and 10×TfO, like its homologous palladium complex
/O in agreement with the
Bond angles
C(1)ꢁPtꢁP(1)
P(1)ꢁPtꢁP(2)
93.2(2)
71.60(6)
C(1)ꢁPtꢁP(3)
P(3)ꢁPtꢁP(2)
93.5(2)
101.98(6)
/
/
/
In the 31P{1H}-NMR spectrum of 4×
let appearing at higher-field (ꢂ
/
ClO4, the doub-
/
2
31.17 ppm, JPP
/
ꢁ68
/
/
Hz) is assigned to the phosphorus trans to the aryl
ligand [based on the data obtained for complex 2 (ꢂ34
ppm [20]), 4×TfO (ꢂ30.60 ppm [20]), 5 (ꢂ35.77 ppm,
see below) and related complexes (ꢂ33 to -36 ppm [35])]
and the other one to the phosphorus trans to N (ꢂ5.70
ppm) [based on the data for 4×TfO (ꢂ5.35 ppm [20])
and 4×SbF6 (ꢂ4.76 ppm [20]). The H-NMR spectrum
shows the expected doublets of doublets (4.52 ppm,
2JPH
12 and 8 Hz) due to the methylene protons.
The 31P{1H}-NMR spectrum of 5 shows at room
temperature broad resonances around 19, ꢂ16 and ꢂ32
2, show broad signals at room temperature presumably
due to the intra- or intermolecular exchange of the
dppm ligands. Probably, in such exchange the anions do
/
/
/
/
/
not intervene because the 31P-NMR spectra of 10×
/
Cl
TfO are similar at room temperature. At
60 8C the spectra are first order. The resonance due
/
and 10×
/
/
/
ꢂ
/
1
/
/
to PA (see Chart) is recognized by its high frequency
(5.77, 6.13 ppm, respectively), corresponding to a
coordinated nonchelated dppm ligand, and its large
coupling to PM (373, 375 Hz, respectively). Similarly, the
resonance due to PM is assigned by its negative chemical
ꢁ
/
/
/
ppm. However, at -60 8C a first-order spectrum is
obtained. The doublets of doublets corresponding to
the phosphorus trans to the aryl ligand is again, as for 2
shift (ꢂ
/
35.49, ꢂ34.47 ppm, respectively) and its large
/
coupling to PA. The doublet of doublets corresponding
to PX was distinguished from that due to PQ by its larger
coupling constants and the platinum satellites. The 31P
resonances of these platinum complexes appear at lower
frequency than those in the homologous Pd complex 2.
The same has been observed previously [38,40]. The
[20] and 4×
(ꢂ35.77 ppm) and is recognized by its smaller JPP
values (67 and 25 Hz). The doublets of doublets
/
ClO4, that appearing at the highest-field
2
/
2
appearing at the lowest field (23.15 ppm, JPP
and 25 Hz) is assigned to PPh3 by comparison with the
ꢁ332
/
spectra of the complex [Pd(k1-R)Cl(PPh3)2] [20.6 ppm
(br) at room temperature and 21.66 ppm (s) at ꢂ60 8C]
/
[36]. Therefore, the intermediate doublet of doublets,
appearing at ꢂ23.49 ppm, must correspond to the
/
phosphorus of dppm trans to PPh3. It is reasonable to
assume that the broadening of signals at room tempera-
ture is due to the equilibrium 5l
/
4×
/
TfOꢄPPh3.
/
The 31P{1H}-NMR spectrum of 6 shows at room
temperature broad signals around at 32 and 11 ppm. At
ꢂ60 8C the first signal transforms into an apparent
/
triplet at 31.56 ppm (assigned to the P nuclei bonded to
Au) but the second one remains broad and moves to
13.39 ppm. The assignments are based on data reported
for complexes containing the unit ‘trans-Pd2(m-(dppm)2’
[d(P)Pd are in the range 21ꢃ
/
5 ppm [6,9,12,16,20]] and on
complexes [Pt(R)Cl(m-dppm)2Au]ꢄ (Rꢁ
/
Me, Et, Ph,
PhCÅ
/
C) [d(P)Au are around 30 ppm [15,25]].
The 31P{1H}-NMR spectrum of 7 exhibits a singlet at
7.35 ppm characteristic of an A-frame complex [12]. The

170
J. Vicente et al. / Journal of Organometallic Chemistry 663 (2002) 164ꢃ172
/
difference is in the range 5ꢃ
and coupling constants are similar to those in the
analogous [PtR(k1-dppm)(k2-dppm)]PF6 (Rꢁ
Me, Et,
Ph, mesityl) derivatives [35]. The small value of JPtPX
(around 1500 Hz) compared with the other two JPtP
(around 2800 and 2400 Hz) is due to the high trans
influence of the aryl ligand.
/
11 ppm. The chemical shifts
4.3. [Pd(k2-R)(k2-dppm)]ClO4 (4×
/
ClO4)
/
To a suspension of 1 (222 mg, 0.316 mmol) in acetone
(20 ml) was added AgClO4 (131 mg, 0.632 mmol) and
the resulting suspension was refluxed for 30 min and
then filtered through Celite. The ligand dppm (243 mg,
0.632 mmol) was added to the filtrate and the mixture
stirred for 1 h. The solution was concentrated and Et2O
1
(8 ml) was added to give 4×
/
ClO4 as an orange solid.
1
Yield: 410 mg, 81%. M.p.: 206 8C (dec). H-NMR (d
4. Experimental
3
4
8 Hz, JPH
ppm): 7.94 (dd, 1H, H13, JHH
7.84ꢃ
6.91 (d, 2H, H23, H25, JHH
ꢁ
/
ꢁ
/
3 Hz),
3
/
7.36 (m, 22H), 7.09 (d, 1H, H14, JHH
ꢁ
/
8 Hz),
3
4.1. General
ꢁ
/
8 Hz), 6.48 (t, 1H, H16,
4JHP
ꢁ
/
9 Hz), 4.52 [dd, 2H, CH2, JPH
ꢁ12 and 8 Hz],
/
2
2.30 [s, 3H, Me], 2.02 [s, 3H, Me]. 31P{1H}-NMR
All reactions were carried out under normal labora-
tory conditions. All solvents were distilled before use.
The conductivity of complexes sufficiently soluble in
2
5.70 (d, Ptrans to N, JPP
(d ppm): ꢂ
/
ꢁ
/
68 Hz), ꢂ31.17
/
(d, Ptrans to C). Anal. Calc. for C39H35ClN2O4P2Pd: C,
58.59; H, 4.41; N, 3.51. Found: C, 58.29; H, 4.27; N,
3.30%.
acetone was measured in solutions of ca. 5ꢅ
10ꢂ4 mol
/
lꢂ1 concentration. 1H-, 31P{1H}- and 13C-NMR spectra
were measured in CDCl3 solutions on a Varian Unity
300 spectrometer at room temperature unless otherwise
stated. Chemical shifts are referred to TMS (1H, 13C)
and H3PO3 (31P). The complex [Pd(k2-R)(m-Cl)]2 (1) was
prepared following a reported procedure [41]. [Pd(k1-
4.4. [Pd(k1-R)(PPh3)(k2-dppm)]TfO (5)
To a solution of 2 (150 mg, 0.12 mmol) in acetone (6
ml) were added [AuCl(PPh3)] (60 mg, 0.12 mmol) and,
after 1 h of stirring, TlOTf (50 mg, 0.14 mmol). The
reaction mixture was concentrated to dryness and
CH2Cl2 (16 ml) was added. The resulting suspension
was filtered through Celite, the filtrate was concentrated
to 4 ml and Et2O (11 ml) was added to give [Au(m-
dppm)2](TfO)2 (70 mg, 79%) as a yellow solid. The
filtrate was concentrated (1 ml) and addition of Et2O (14
R)Cl(k1-dppm)(k2-dppm)]TfO
dppm)]TfO (4×
(2),
[Pd(k2-R)(k2-
/
TfO), and trans-[PtRCl(PPh3)2] (9),
were prepared as we previously reported [20]. The
atom labeling for NMR assignments is shown in the
Chart.
4.2. [{Pd(k2-R)Cl}2(m-dppm)] (3)
ml) and n-hexane (1 ml) gave 5 as an orange solid. Yield:
1
To a suspension of 1 (105 mg, 0.15 mmol) in CH2Cl2
(10 ml) was added dppm (57 mg, 0.15 mmol) and the
resulting solution was stirred for 30 min. The solution
was concentrated (1 ml) under vacuum and Et2O (10 ml)
was added to give yellow complex 3. Yield: 145 mg,
77 mg, 50%. M.p. 108 8C. H-NMR (d ppm): 7.8ꢃ
/6.4
2
(m, 42H, aromatic protons), 4.54 [t, 2H, CH2, JHP
Hz], 2.40 (s, 3H, Me), 1.90 (s, 3H, Me). 31P{1H}-NMR
(d ppm): 19 (br), ꢂ16 (br), ꢂ
32 (br). 1H-NMR
(ꢂ60 8C): 7.9ꢃ5.9 (m, 42H, aromatic protons), 4.5
(m, 2H, CH2), 2.42 (s, 3H, Me), 1.73 (s, 3H, Me).
ꢁ9
/
/
/
/
/
89%. M.p. 195 8C. nmax (cmꢂ1) (Pdꢁ
NMR (d ppm): 8.11ꢂ8.05 (m, 8H, aromatic protons)
7.77ꢃ7.73 (m, 6H, aromatic protons), 7.38ꢃ
16H), 6.84 (d, 2H, H14, JHH
4JHP
/
Cl), 278 cmꢂ1. 1H-
2
/
31P{1H}-NMR (ꢂ
/
60 8C): 23.15 (dd, PAPh3, JAM
ꢁ
/
2
332 Hz, JAX
2
23.49 (dd, PM, JMX
Hz), 35.77 (dd, 1P, PX). Anal. Calc. for
/
/
7.20 (m,
ꢁ
/
25 Hz), ꢂ
/
ꢁ67
/
3
ꢁ
/
8 Hz), 5.73 (d, 2H, H16,
ꢂ
/
2
ꢁ
/
8 Hz), 5.02 [t, 2H, CH2, JHP
ꢁ
/
14 Hz], 2.42 (s,
C58H50F3N2O3P3PdS: C, 62.67; H, 4.54; N, 2.52; S,
2.88. Found: C, 62.41; H, 4.80; N, 2.48; S, 2.88%.
6H, Me), 1.71 (s, 6H, Me). 31P{1H}-NMR (d ppm):
30.68 (s). 13C-NMR (d ppm): 162.95 (s, C12), 156.79 (s,
C11), 149.83 (d, C21, 3JCP
6 Hz), 140.67 (s, C24), 137.99 (d, C16, JPC
ꢁ
/
5 Hz), 142.54 (d, C15, 4JCP
ꢁ
/
4.5. [Pd(k1-R)Cl(m-dppm)2Au]TfO (6)
3
ꢁ8 Hz),
13 Hz), 131.19 (d, C34,
/
2
135.74 (d, C32Å
4JPC
3 Hz), 130 27 (s, C13) 129.15 (d of the apparent
dd corresponding to C31, ‘J’ꢁ4 Hz), 128.48, 128.44,
128.33 (one signal of the apparent dd corresponding to
C31 plus C23ÅC25 and C33ÅC35), 125.99 (s, C14), 124.40
(s, C22ÅC26), 28.67 (t, CH2, JPC
/
C36, JPC
ꢁ
/
To a solution of 2 (202 mg, 0.164 mmol) at ꢂ60 8C
/
ꢁ
/
in CH2Cl2 (7 ml) was added [AuCl(PPh3)] (81 mg, 0.164
mmol) and stirred for 3 h while its temperature was
allowed to rise slowly up to 25 8C. The resulting
solution was evaporated to dryness, Et2O (4 ml) was
added and vigorous stirred for 5 min to give 6 as an
orange solid. Yield: 211 mg, 88%. M.p. 210 8C (dec).
/
/
/
1
/
ꢁ25 Hz), 22.17, 21.46
/
(4Me). Anal. Calc. for C53H48Cl2N4P2Pd2: C, 58.57; H,
4.46; N, 5.16. Found: C, 58.72; H, 4.51; N, 5.09%. Single
crystals of 3 were obtained by slow diffusion of n-
pentane into a solution of 3 in CH2Cl2.
1H-NMR (ꢂ
aromatic protons), 4.45ꢃ
3H, Me), 1.18 (s, 3H, Me). 31P{1H}-NMR (ꢂ
/
60 8C, d ppm): 8.06ꢃ
3.51 (m, 4H, CH2), 2.45 (s,
60 8C, d
/
6.53 (m, 47 H,
/
/

J. Vicente et al. / Journal of Organometallic Chemistry 663 (2002) 164ꢃ
/172
171
ppm): 31.56 (‘t’, P2Au, ½2JPPꢄ4
/
JPP½ꢁ
/
33 Hz), 13.39 (br,
5.0ꢃ
/
4.7 (m, 2H, CH2), 2.59 (s, 3H, Me), 2.5ꢃ
/
2.45 (m,
P2Pd). FABꢄ: m/zꢁ
/
1312 [Mꢄ], 965 [Au(dppm)2ꢄ], 699
2H, CH2), 1.98 (s, 3H, Me). 31P{1H}-NMR (ꢂ
/
60 8C, d
46 Hz,
33.50 (dd, PQ,
[PdR(dppm)ꢄ]. Anal. Calc. for C65H57AuClF3-
N2O3P4PdS: C, 53.25; H, 3.93; N, 1.91; S, 2.19. Found:
C, 53.15; H, 3.94; N, 1.76; S, 2.12%.
ꢁ
/
373 Hz, JAQ
ꢁ
/
2
ppm): 5.77 (ddd, PA, JAM
2JAX
4JMQ
1JPtPM
Anal. Calc. for C64H57ClN2P4Pt: C, 63.59; H, 4.76; N,
2.32. Found: C, 63.76; H, 4.69; N, 2.28%.
2
1
ꢁ
ꢁ
ꢁ
/
18 Hz, JPtPA
ꢁ
/
2800 Hz), ꢂ
/
2
/
not resolved), ꢂ
/
35.49 (ddd, PM, JMX
1
ꢁ
/
44 Hz,
1510 Hz).
/
2454 Hz), ꢂ39.74 (dd, PX, JPtPX
/
ꢁ
/
4.6. [{PdR(m-dppm)}2(m-Cl)]TfO (7)
To a suspension of 2 (137 mg, 0.11 mmol) in acetone
(15 ml) was added 1 (39 mg, 0.05 mmol) and the
resulting suspension was stirred for 6 h. The solvent was
partially evaporated (1 ml) and Et2O (10 ml) and n-
hexane (10 ml) were added to give 7 as an orange solid.
4.9. [PtR(dppm-k1-P)(dppm-k2-P,P)]TfO (10×
/
TfO)
To a solution of 10×Cl (224 mg, 0.185 mmol) in
/
CH2Cl2 (10 ml) was added TlOTf (66 mg, 0.187 mmol).
The resulting suspension was stirred for 1 h and then
filtered thorough Celite. The solution was concentrated
Yield: 154 mg, 88%. M.p. 198 8C. DM (Vꢂ1 cm2
molꢂ1)ꢁ
/
133. H-NMR (d ppm): 7.59ꢃ
/6.47 (m, 54H,
1
aromatic protons), 3.94 [dm, 4H, CH2), 2.47 (s, 6H,
Me), 1.96 (s, 6H, Me). 31P{1H}-NMR (d ppm): 7.35 (s).
13C{1H}-NMR (d ppm): 152.78, 151.71, 150.54 (C11,
C12, C21), 141.51, 140.37 (C15, C24), 138.99 (C16), 133.43
to 2 ml and addition of Et2O (20 ml) gave 10×
/
TfO as an
orange solid. Yield: 196 mg, 80%. M.p. 198 8C. DM
1
(Vꢂ1 cm2 molꢂ1)ꢁ
7.9ꢃ6.3 (m, 47H, aromatic protons), 5.0ꢃ
CH2), 2.60 (s, 3H, Me), 2.53ꢃ2.47 (m, 2H, CH2), 1.97 (s,
3H, Me). 31P{1H}-NMR (ꢂ
60 8C, d ppm): 6.13 (ddd,
/
131. H-NMR (ꢂ
/
60 8C, d ppm):
/
/4.5 (m, 2H,
(‘t’, one of the C32Å
132.51 (tƒ, the other C32Å
Hz), 130.58, 130.14, 129.39 (the pair of C34 carbons
plus C23ÅC25), 128.12 (‘t’, not resolved, one of the C33Å
C35 pairs), 127.94 (tƒ, the other C33ÅC35 pair,
[3JPCꢄ5
JPC]ꢁ3 Hz), 125.24 (C14), 124.55 (C13), 122.64
(C22ÅC26), 30.12 (‘t’, not resolved, CH2), 21.50 (2 Me),
/
C36 pairs, ½2JPCꢄ4
C36 pair, ½2JPCꢄ4
/
JPC½ꢁ
/
7 Hz,
/
/
/
JPC½ꢁ
/3
/
2
2
2
PA, JAM
1JPtPA
ꢁ
/
375 Hz, JAQ
ꢁ
/
46 Hz, JAX
ꢁ
/
19 Hz,
6 Hz),
2330 Hz),
1520 Hz). Anal. Calc. for
2
/
/
ꢁ
/
2780 Hz), ꢂ
/
33.53 (dd, PQ, JMQ
ꢁ
ꢁ
ꢁ
/
2
34.47 (ddd, PM, JMX
1
/
ꢂ
/
/45 Hz, JPtPM
ꢁ
/
1
39.08 (dd, PX, JPtPX
/
/
ꢂ
/
/
/
C65H57F3N2O3P4PtS: C, 59.04; H, 4.35; N, 2.12; S, 2.42.
Found: C, 59.15; H, 4.47; N, 2.12; S, 2.49%. Single
21.22 (2 Me). Anal. Calc. for C79H70ClF3N4O3P4Pd2S:
C, 59.87; H, 4.46; N, 3.54; S, 2.02. Found: C, 59.78; H,
4.50; N, 3.38; S, 2.19%.
crystals of 10×
/
TfO were obtained by slow diffusion of n-
TfO in chloroform.
hexane into a solution of 10×
/
4.7. [Pd(k2-R)(k2-P,O-dppmO)]TfO (8)
5. Supplementary material
A solution of 4×
/
TfO (72 mg, 0.08 mmol) in toluene
(20 ml) was refluxed for 8 h. The resulting suspension
was concentrated (5 ml) and Et2O (20 ml) was added to
give 8 as a yellow solid. Yield: 40 mg, 36%. M.p. 219 8C
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 186694, 186695 and 186696 for
(dec). 1H-NMR (d ppm): 8.28 (d, 2H, H22, H26, 3JHH
ꢁ
/
compounds 3, 8×
/
CH2Cl2 and 10×/TfO, respectively.
9 Hz), 7.90ꢃ7.36 (m, 23 H, aromatic protons), 6.98 (d,
/
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
3
4
1H, H14, JHH
ꢁ
/
8 Hz), 6.20 (d, 1H, H16, JHP
ꢁ
/
8 Hz),
12 and 10 Hz], 2.52 (s, 3H, Me),
1.85 (s, 3H, Me). 31P{1H}-NMR (d ppm): 55.61 (d,
Ph2Pꢀ 16 Hz), 33.12 (d, Ph2P). Anal. Calc. for
O, 2JPP
2
4.18 [dd, CH2, JPH
ꢁ
/
Cambridge CB2 1EZ, UK (Fax: ꢄ44-1223-336022;
/
email: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
/
ꢁ
/
C40H35F3N2O4P2PdS: C, 55.5; H, 4.08; N, 3.24; S, 3.70.
Found: C, 55.3; H, 4.04; N, 2.89; S, 3.47%. Single
crystals of 8 were obtained by slow diffusion of Et2O
into a solution of 7 in chloroform.
Acknowledgements
We thank Ministerio de Ciencia y Tecnologia (Spain)
and FEDER (BQU2001-0133) for finacial support.
4.8. [Pt(k1-R)(k1-dppm)(k2-dppm)]Cl (10×
/
Cl)
To a suspension of 9 (95 mg, 0.1 mmol) in acetone (25
ml) was added dppm (151 mg, 0.393 mmol) and the
resulting solution was stirred for 30 min. Concentration
of this solution (1 ml) and addition of Et2O (16 ml)
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M.p. 178 8C. DM (Vꢂ1 cm2 molꢂ1)ꢁ
(ꢂ60 8C, d ppm): 7.9ꢃ6.5 (m, 47H, aromatic protons),
/
Cl. Yield: 60 mg, 67%.
1
/110. H-NMR
/
/

172
J. Vicente et al. / Journal of Organometallic Chemistry 663 (2002) 164ꢃ172
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