Cyclometallated platinum complexes with heterocyclic ligands

Article abstract of DOI:10.1016/j.jorganchem.2004.01.026

The reactions of [Pt₂Me₄ (μ-SMe₂)₂] with imine ligands derived from 3-furaldehyde, 3- or 4-pyridinealdehyde and N,N-dimethylethylenediamine, and 3-furaldehyde and chlorobenzylamine are reported. The furane ligan

Full text of DOI:10.1016/j.jorganchem.2004.01.026

Journal of Organometallic Chemistry 689 (2004) 1496–1502
www.elsevier.com/locate/jorganchem
Cyclometallated platinum complexes with heterocyclic ligands
a,
b,
*
Craig Anderson *, Margarita Crespo
a
Department of Chemistry, Bard College, 30 Campus Road, Annandale-on-Hudson, NY 12504, USA
Departament de Quꢀımica Inorgꢁanica, Facultat de Quꢀımica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain
b
Received 24 December 2003; accepted 27 January 2004
Abstract
The reactions of [Pt2Me4(l-SMe2)2] with imine ligands derived from 3-furaldehyde, 3- or 4-pyridinealdehyde and N; N-di-
methylethylenediamine, and 3-furaldehyde and chlorobenzylamine are reported. The furane ligands coordinated to platinum
through the nitrogen donor and could be forced to orthometallate under severe conditions. The ligands with pyridine rings gave only
substitution of the ligand for the dimethylsulphide. The oxidative addition reactions of the orthometallated complexes with methyl
iodide as well as the complexesÕ reactions with triphenylphosphine are also reported. Correlation between aromaticity of the or-
thometallated ring and reactivity of the complexes is observed.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Cyclometallation; Platinum; Furane; Oxidative addition; Imine
1. Introduction
As shown in Chart 1, 3-substituted furanes or pyri-
dines can be cyclometallated at two non-equivalent po-
sitions. Previous studies for 3-substituted furanes
indicate that the preferred metallation site is ortho to the
oxygen atom [4]. On the other hand, examples of acti-
vation of C–H bonds in a meta position to the N atom
have been reported for 2,20-bipyridine [5] and 2,40-bi-
pyridine [6] systems. Moreover, double metallation at
the two meta positions of the inner pyridine has also
been reported for 2,20:60,200-terpyridine ligand [7]. In
addition, oxidative addition reactions involving transi-
tion metals are fundamental steps in stoichiometric and
catalytic processes. Therefore we also report the oxida-
tive addition of methyl iodide to the new cyclometal-
lated complexes.
Square planar platinum (II) and specifically cyclo-
metallated complexes are of interest for several reasons
including their interesting photochemical and photo-
physical properties, their potential use as molecular de-
vices, and more generally as products or intermediates in
catalytic reactions [1]. Cyclometallation reactions have
been widely investigated for benzene derivatives. How-
ever, heterocyclic analogues have been less explored.
The latter are attractive for regioselectivity studies due
to the presence of non-equivalent positions available for
metallation. Following our studies on intramolecular C–
H bond activation of benzene [2] and thiophene rings [3]
at platinum, we decided to study the activation of such
bonds in furanes and pyridines using a similar strategy.
The reactions of [Pt2Me4(l-SMe2)2] (1) with imine
ligands derived from 3-furaldehyde, 3- or 4-pyridineal-
dehyde and N; N-dimethylethylenediamine or 2-chlo-
robenzylamine are reported.
2. Results and discussion
2.1. Furane derivatives
Ligands 3-(Me2NCH2CH2NCH)C4H3O (2a) and 3-
(20-ClC6H4CH2NCH)C4H3O (2b) were prepared as
yellow oils from the condensation reaction of 3-fural-
dehyde and N; N-dimethylethylenediamine or 2-chlo-
* Corresponding authors. Tel.: +1-845-758-7293; fax: +1-845-758-
7628.
E-mail address: canderso@bard.edu (C. Anderson).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.01.026

C. Anderson, M. Crespo / Journal of Organometallic Chemistry 689 (2004) 1496–1502
1497
Possible metallation sites for the heterocycles under study
X
X
N
X
N
O
(a) 3 -substituted furane
(b) 3 -substituted pyridines (c) 4 -substituted pyridines
Chart 1.
Phosphine derivatives
Cyclometallated compounds
Coordination compounds
Ligands
c
b
b Me2
a
a
Me2
N
a
PPh3
PPh3
N
4
Me
Me
Me
d
e
e
d
Me
c
4
f
c
3
c
b
Pt
5
Pt
I
d
CH
Pt
a
2
CH
NMe2
2
5
d
N
2
NMe2
N
O
N
O
N
Pt
b
O
O
2
Me
O
CH=N
NMe2
Me
2
f
5
a
5
e
3
2a
b
e
5
3
d
c
4
4
3a
4
6a
4a
5a
b
a
a
SMe2
Me
PPh3
PPh3
Cl
Me
4
Pt
Pt
a
CH2
c
b
CH
2
2
N
CH2C6H4Cl
O
N
O
O
CH=NCH2C6H4Cl
d
5
3
5
c
2
b
2b
4
4
4b
6b
5
6
2
56
e
d
f
c
c
b
a
d
4
CH
NMe2
N
C
H
4
NMe2
N
Pt
N
Me
Me
N
2
b
a
3c
2c
e
d
f
c
b
c
d
a
CH
NMe2
N
N
CH
NMe2
N
N
Pt
Me
2
Me
3
a
b
3
2
2d
3d
Chart 2.
robenzylamine carried out in toluene at room tempera-
ture (see Chart 2 for the structures of all new species).
The resulting imines were characterized by H and 13C
(2a) NMR spectra.
appear in the methyl region, both coupled with 195Pt.
The one at higher field with a larger coupling to 195Pt is
assigned to the methyl trans to the NMe2 [2]. The co-
ordination of the ligand through the nitrogen atoms is
confirmed by the coupling of both amine and imine
protons to platinum. The chemical shifts observed for
195Pt are in the expected range [8] for a platinum (II)
center bound to two carbon and two nitrogen atoms.
For the purpose of comparison, 195Pt NMR spectra
were also taken for the previously reported compounds
[PtMe2{Me2NCH2CH2NCHC6H5}] [2] and [PtMe2{3-
(Me2NCH2CH2NCH)C4H3S}] [3] (Table 1).
1
The reaction of ligand 3-(Me2NCH2CH2NCH)-
C4H3O (2a) with [Pt2Me4(l-SMe2)2] (1) carried out in
acetone at room temperature produced compound
[PtMe2{3-(Me2NCH2CH2NCH)-C4H3O}] (3a) in which
the imine acts as a bidentate [N; N0] ligands (Scheme 1).
1
Compound 3a was characterized by H and 13C NMR
spectroscopies, elemental analysis and FAB-mass spec-
1
tra. In the H NMR spectra, two distinct resonances

1498
C. Anderson, M. Crespo / Journal of Organometallic Chemistry 689 (2004) 1496–1502
O
O
Me
Me
N
Me2
S
CH3
CH3
H3C
H3C
Pt
Pt
+
Pt
S
N
NMe2
NMe2
Me2
2a
1
3a
Heat
O
Me
O
Me
Me
MeI
Pt
Pt
N
NMe2
N
NMe2
I
4a
5a
PPh3
O
PPh3
PPh3
NMe2
Pt
N
Me
6a
Scheme 1.
Table 1
d(195Pt) values for compounds [PtMe2{3-(Me2NCH2CH2NCH)Ar}]
However, the cyclometallated compound [PtMe
{3-(Me2NCH2CH2NCH)C4H2O}] (4a) containing a
tridentate [C,N,N0] ligand could be obtained when a
toluene solution of 3a was refluxed for 2 h (Scheme 1)
and the resulting complex was characterized by multi-
nuclear NMR spectroscopies, elemental analysis and
FAB-MS.
(3) and [PtMe{3-(Me2NCH2CH2NCH)(Ar-H)}] (4)a
Aryl
Compound 3
Compound 4
Ddb
C4H3O
C4H3S
C6H5
)3520c
)3492d
)3466e
)3732c
)3669d
)3612e
212
177
146
a d(195Pt) in ppm referenced to H2PtCl6 in D2O.
b Dd ¼ d(195Pt for 3) – d(195Pt for 4).
c Prepared in this work.
As previously reported for thienyl systems [3], the site
of metallation was the C(2) position of the furane ring.
This is consistent with the J(H–H) value of 6 Hz ob-
tained for the two aromatic protons (H4 and H5). Values
between 5 and 6 Hz are expected for adjacent ring hy-
drogens confirming the C(2) metallation site [4]. The
proposed structure consisting of a three-fused ring sys-
tem containing a five-membered metallacycle is shown
in Chart 2. All spectral parameters for compound 4a are
in good agreement with the results obtained for analo-
gous aryl cyclometallated compounds [2,3]. As shown in
Table 1, the value obtained for d(195Pt) moves to higher
fields for cyclometallated complexes when compared to
the value for the corresponding non-cyclometallated
precursor, an effect which is larger for the furane de-
rivative (Dd ¼ 212 PPM) than for benzene or thiophene
analogues. These values are also correlated to the aro-
maticity of the cyclometallated rings.
d Synthesis reported in [3].
Compound 3a is stable in acetone solution at room
temperature for several days in contrast to the behavior
of compounds [PtMe2{Me2NCH2CH2NCHC6H5}] [2]
and [PtMe2{3-(Me2NCH2CH2NCH)C4H3S}] [3] which,
under these conditions, have been reported to yield the
corresponding cyclometallated compounds with elimi-
nation of methane. The lower tendency of the furane
derivative towards cyclometallation is attributed to the
lower degree of aromaticity of furane (16 kcal/mol)
versus benzene (36 kcal/mol) or thiophene (29 kcal/mol)
[9]. The aromaticity of a system containing a five-
member endo-metallacycle fused with an aryl ring has
been reported as the main driving force for the forma-
tion of platinum (II) and palladium (II) endo-metalla-
cycles [10].
Oxidative addition of methyl iodide to compound 4a
was achieved in acetone solution to give (Scheme 1) the

C. Anderson, M. Crespo / Journal of Organometallic Chemistry 689 (2004) 1496–1502
1499
resulting cyclometallated platinum (IV) compound
[PtMe2I{3-(Me2NCH2CH2NCH)C4H2O}] (5a) which
was characterized by NMR spectroscopy. The spectral
parameters are in good agreement to those reported for
analogous compounds arising from trans oxidative ad-
dition [11]. In particular, two examples: (1) the values of
the coupling constants of the methylplatinum and the
imine protons to 195Pt decrease and (2) the d(195Pt)
resonance is downfield shifted upon oxidation of plati-
num (II) to platinum (IV).
The reaction of ligand 3-(20-ClC6H4CH2NCH)
C4H3O (2b) with [Pt2Me4(l-SMe2)2] (1) carried out in
toluene for 16 h at room temperature produced the cy-
clometallated platinum (II) compound [PtMe{3-(20-
ClC6H4CH2NCH)C4H3O}SMe2] (4b) in which the im-
ine acts as a [C,N] ligand. Activation of the C–Cl bond
that would lead to an exo-platinum (IV) metallacycle
was not observed, which suggest that the reactivity or-
der: C–H (endo) >C–Cl (exo) previously reported for
phenyl systems [12] also holds for furane derivatives.
Compound 4b was characterized by NMR and mass
spectroscopies as well as elemental analysis. Analogous
to 4a, the J(H–H) values obtained for the two hydrogen
atoms of the furane ring indicate that metallation took
place at the C(2) position of the furane.
The reactions of compounds 4a and 4b with
triphenylphosphine in 1:1 and 1:2 molar ratio
were studied. In the latter case, compounds [PtMe{3-
(Me2NCH2CH2NCH)C4H2O}(PPh3)2] (6a) and [PtMe
{3-(20-ClC6H4CH2NCH)C4H3O}(PPh3)2] (6b) were
produced with cleavage of the metallacycles (Scheme 1),
while in the former a mixture of compounds 4 and 6 is
obtained. Attempts to obtain cyclometallated com-
pounds containing only one PPh3 were unsuccessful.
For analogous phenyl derivatives, opening of the met-
allated ring upon reaction with triphenylphosphine had
only been achieved when a chlorine [13] or a fluorine
[14,15] atom was present in the position adjacent to the
Pt–C(aryl) bond, while for analogous thienyl deriva-
tives, the triphenylphosphine replaced only either the
SMe2 ligand or the NMe2 moiety of the tridentate ligand
without cleaving the corresponding metallacycles [3,16].
The lower stability of the metallacycles obtained for the
furane derivatives when compared to the thiophene or
the phenyl analogues, again attributed to the lower
aromaticity of the furane ring, can account for the dif-
ferences in reactivity towards triphenylphosphine.
Compounds 6a and 6b were characterized by NMR
and mass spectroscopy and data are consistent with the
structures depicted in Chart 2. Compounds 6 could not
be isolated in a pure form due to decomposition pro-
cesses during attempted crystallization in several sol-
vents. The methylplatinum resonance is coupled to 195Pt
and to two non-equivalent phosphorous atoms. The
imine is not coupled with platinum which is taken as
evidence for the cleavage of the metallacycle. The 31P
NMR spectra show two sets of resonances due to non-
equivalent phosphorous atoms, in mutually cis-posi-
tions, both coupled to platinum. In each case, the larger
J(P–Pt) value (2141 (6a); 2147 (6b)) is assigned to the
phosphine trans to the furyl group due to the smaller
trans influence expected for this group compared to
methyl. The values of the coupling constants J(P–Pt)
from the 31P spectra were in agreement with the values
found in the 195Pt NMR spectra. d(195Pt) values are well
within the range expected for organoplatinum (II)
compounds with phosphine ligands [14,17].
2.2. Pyridine derivatives
Ligands 3-(Me2NCH2CH2NCH)C5H4N (2c) and 4-
(Me2NCH2CH2NCH)C5H4N (2d) were prepared as
yellow oils from the corresponding pyridinealdehyde
and N; N-dimethylethylenediamine and characterized by
1H and 13C NMR spectra. The reactions of 2c and 2d
with [Pt2Me4(l-SMe2)2] (1) were carried out under
similar conditions described above for 2a. The reactions
gave insoluble orange solids, which could not be prop-
erly characterized. Therefore, the reactions of ligands 2c
1
and 2d with 1 were monitored by H NMR in acetone-
d6. In the early stages, compounds [PtMe2{3-
(Me2NCH2CH2NCH)C5H4N}] (3c) and [PtMe2
{4-(Me2NCH2CH2NCH)C5H4N}] (3d) were detected
together with free ligand and quickly, within several
minutes insoluble orange compounds were produced.
Compound 3c was characterized by FAB-mass spec-
troscopy. The FAB-mass spectrum shows intense peaks
corresponding to loss of one and two methyl groups
from the proposed formula of 3c.
With the aim of obtaining cyclometallated com-
pounds, the reactions of 2c and 2d with 1 in refluxing
toluene were performed. Again, very insoluble orange
solids were obtained and the FAB-mass spectra for the
compound derived from 2c was identical to that ob-
tained for 3c (see above). Since peaks corresponding to
loss of methyl groups were observed for 3c, there is no
conclusive evidence whether or not cyclometallation
with loss of methane took place under any of these
conditions. As a whole, the poor solubility of the plat-
inum compounds obtained from ligands derived from
pyridines hindered their characterization. In spite of the
results obtained for the mass spectra, the formation of
polymeric species arising from coordination to platinum
centers through the pyridine nitrogen can not be ruled
out and this would explain the low solubility.
3. Concluding remarks
The heterocyclic furane and pyridine ligands de-
scribed above react somewhat differently than the thio-
phene and benzene ligands previously reported. The

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C. Anderson, M. Crespo / Journal of Organometallic Chemistry 689 (2004) 1496–1502
orthometalled furane complexes are more difficult to
synthesize, as more severe reaction conditions were
needed for their formation compared to the thiophene or
benzene derivatives. The complexes are also less stable as
witnessed by the easy cleavage of the metallocycle ring
with triphenylphoshine not regularly seen for analogous
complexes. These results and others, such as trends in the
platinum NMR spectra are attributed to the lower aro-
maticity of the furane ring compared to the other rings.
The bond energy of the C–H bonds being broken may
well have a role in the reactivity trends. It has been
shown that the selectivity and rates of intramolecular
oxidative addition for aryl halides vary inversely with
the Ar–X bond energy [2]. These results compare very
similar aryl systems where only the halide atom changes
and the bond energies of interest span a large range of
values (Ar–F ¼ 116 kcal/mol, Ar–Br ¼ 72 kcal/mol) [18].
However, this is much different for the furane and thi-
ophene cases. Calculated values for the energy of C–H
bonds of small heterocyclic rings exist and the difference
between furane and thiophene for the bond in question
is only 1.8 kcal/mol [19]. Therefore, any conclusion
made with respect to the C–H bond energy being the
rate-determining factor should be guarded with caution.
The mechanism probably initially includes partial co-
ordination of the heterocyclic ring followed by activa-
tion of the C–H bond through a tri-centered C–Pt–H
interaction, the proximity of the bond to be broken and
its approach to the metal being the most important
factor in the mechanism and not the bond energy of the
C–H bond. We therefore suggest that the transition state
may be stabilized when a more aromatic ring is being
metallated and this therefore makes thiophene faster
than furane. The initial step may also include partial
coordination of the sulfur in thiophene thus also in-
creasing the rate of thiophene versus furane as sulfur is a
better ligand than oxygen for platinum.
zyl alcohol matrix) were performed by the Serveis
ꢀ
ꢁ
Cientıfico-Tecnics de la Universitat de Barcelona.
Compound [Pt2Me4(l-SMe2)2] (1) was prepared as re-
ported [20].
4.2. Synthesis of ligands
Compound 2a was prepared by the reaction of 0.46 g
(5.2 mmol) of N; N-dimethylethylenediamine with an
equimolar amount (0.5 g) of 3-furaldehyde in toluene
(20 ml). The mixture was stirred for 30 min and dried
over Na2SO4. The solvent was removed in a rotary
evaporator to yield a yellow oil. Compounds 2b, 2c and
2d were similarly prepared from 0.74 g of 2-chloroben-
zylamine and the equimolar amount (0.5 g) of 3-fural-
dehyde (2b) or from 0.46 g (5.2 mmol) of N; N-
dimethylethylenediamine and the equimolar amount
(0.56 g) of the corresponding pyridinealdehyde (2c,
2d). 3-(Me2NCH2CH2NCH)C4H3O (2a). Yield: 0.7 g
1
(81%). H NMR (200 MHz, CDCl3): d ¼ 2:30 [s, Ha];
3
3
2.61 [t, J(Hb–Hc) ¼ 7, Hb]; 3.64 [t, J(Hc–Hb) ¼ 7, Hc];
6.81 [d, J(H–H) ¼ 2, H4]; 7.41 [d, J(H–H) ¼ 2, H2]; 7.70
[s, H5]; 8.25 [s, 1H, Hd]. 13C NMR (50 MHz, CDCl3):
d ¼ 45:81 [Ca]; {59.95, 60.04, Cb;c}; 107.77 [C4]; 125.34
[C3]; 143.84 [C5]; 145.00 [C2]; 153.37 [Cd]. 3-(20-
1
ClC6H4CH2NCH)C4H3O (2b). Yield: 0.9 g (79%). H
NMR (200 MHz, CDCl3): d ¼ 4:89 [s, Ha]; {6.87 [d,
J(H–H) ¼ 2, 1H], 7.24–7.44 [m, 5H]; 7.75 [s, 1H], aro-
matics}; 8.33 [s, 1H, Hb]. 3-(Me2NCH2CH2NCH)
1
C5H4N (2c). Yield: 0.8 g (87%). H NMR (200 MHz,
3
CDCl3): d ¼ 2:31 [s, Ha]; 2.66 [t, J(Hb–Hc) ¼ 7, Hb];
3
3.77 [t, J(Hc–Hb) ¼ 7, Hc]; 7.34 [dd, J(H–H) ¼ 8, J(H–
H) ¼ 5, H5]; 8.12 [dt, J(H–H) ¼ 8, J(H–H) ¼ 2, H4]; 8.36
[s, H2]; 8.65 [dd, J(H–H) ¼ 5, J(H–H) ¼ 2, H6]; 8.86 [d,
J(H–H) ¼ 2, 1H, Hd]. 13C NMR (50 MHz, CDCl3):
d ¼ 45:88 [Ca]; {59.94; 60.06, Cb;c}; {123.52, 134.39,
150.15, 151.34, aromatics}; 158.79 [Cd]. 4-(Me2NCH2-
CH2NCH)C5H4N (2d). Yield: 0.8 g (87%). 1H NMR
(200 MHz, CDCl3): d ¼ 2:31 [s, Ha]; 2.66 [t, 3J(Hb–
The pyridine ligands were suspected to give only co-
ordination compounds and it was inconclusive whether
any orthometallation had occurred. The complexes were
difficult to characterize due to their low solubility and
this is attributed to the formation of polymeric species.
3
Hc) ¼ 7, Hb]; 3.79 [t, J(Hc–Hb) ¼ 7, Hc]; {7.59 [d, J(H–
H) ¼ 6, 2H, H2], 8.68 [d, J(H–H) ¼ 6, 2H, H3], aromat-
ics}; 8.30 [s, 1H, Hd]. 13C NMR (50 MHz, CDCl3):
d ¼ 45:85 [Ca]; {59.75, 59.98, Cb;c}; 121.84 [C2]; 150.26
[C3]; 159.74 [Cd].
4. Experimental
4.3. Synthesis of compound 3a
4.1. General
Compound 3a was obtained by adding a solution of
65 mg (3.9 · 10ꢀ4 mol) of the imine 2a in acetone (10 ml)
to a solution of 100 mg (1.74 · 10ꢀ4 mol) of compound
[Pt2Me4(l-SMe2)2] (1) in acetone (10 ml). The mixture
was stirred for 30 min at room temperature and com-
pound 3 was obtained upon removal of the acetone in a
rotary evaporator. The orange-yellow solid was washed
1H, 13C, 31P and 195Pt NMR spectra were recorded at
the Unitat de RMN dÕAlt Camp de la Universitat de
Barcelona using Varian Gemini 200 (1H, 200 MHz; 13C,
50 MHz), Varian 500 (1H, 500 MHz), and Bruker 250
(31P, 101.25 MHz, 195Pt, 54 MHz) spectrometers, and
referenced to SiMe4 (1H, 13C), H3PO4 (31P) and H2PtCl6
in D2O (195Pt). d values are given in ppm and J values in
Hz. Microanalyses and mass spectra (FAB, 3-nitroben-
with ether (3 · 2 ml) and dried in vacuum. [PtMe2{3-
ꢀ
(Me2NCH2CH2NCH)C4H3O}] (3a). Yield: 110 mg

C. Anderson, M. Crespo / Journal of Organometallic Chemistry 689 (2004) 1496–1502
1501
(81%). 1H NMR (200 MHz, CDCl3): d ¼ 0:45 [s, 2J(Pt–
H) ¼ 91, Mea]; 0.58 [s, 2J(Pt–H) ¼ 84, Meb]; 2.62 [t,
J(H–H) ¼ 5, Hd]; 2.79 [s, 3J(Pt–H) ¼ 21, Hc]; 4.00 [t,
J(H–H) ¼ 5, He]; {7.35 [d, J(H–H) ¼ 2, 1H], 7.38 [d,
J(H–H) ¼ 2, 1H], H4;5}; 8.20 [s, H2]; 8.75 [s, 3J(Pt–
H) ¼ 49, Hf ]. 1H NMR (200 MHz, acetone-d6): d ¼ 0:30
[s, 2J(Pt–H) ¼ 93, Mea]; 0.39 [s, 2J(Pt–H) ¼ 85, Meb];
2.63 [t, J(H–H) ¼ 5, Hd]; 2.70 [s, 3J(H–Pt) ¼ 22, Hc];
3.99 [t, J(H–Pt) ¼ 12, J(H–H) ¼ 5, He]; {7.54 [d, J(H–
H) ¼ 2, 1H], 7.57 [d, J(H–H) ¼ 2, 1H], H4;5}; 8.43 [s, H2];
8.92 [s, 3J(Pt–H) ¼ 51, Hf ]. 195Pt NMR (54 MHz,
CDCl3): d ¼ ꢀ3520 [s]. FAB(+)-MS, m=z: 391 [M], 375
[M–Me], 359 [M–2Me]. Anal. Found: C, 33.4; H, 5.0; N,
6.6. Calc. for C11H20N2OPt: C, 33.76; H, 5.15; N,
7.16%.
Pt) ¼ 25, C4], 129.00 [C3], 140.98 [C2], 143.09 [J(C–
Pt) ¼ 72, C5], 159.96 [J (Pt–C) ¼ 45, Ce]. 195Pt NMR
(54 MHz, CDCl3): d ¼ ꢀ3732 [s]. FAB(+)-MS, m=z:
375 [M], 359 [M–Me]. Anal. Found: C, 32.2; H, 4.5;
N, 7.1. Calc. for C10H16N2OPt: C, 32.00; H, 4.30; N,
7.46%.
4.6. Synthesis of compound 4b
Compound 4b was obtained by adding a solution of
77 mg (3.9 · 10ꢀ4 mol) of 2b in toluene (10 ml) to a
solution of 100 mg (1.74 · 10ꢀ4 mol) of compound
[Pt2Me4(l-SMe2)2] (1) in toluene (10 ml). The mixture
was stirred for 16 h at room temperature. The toluene
was removed in a rotary evaporator and the residue was
washed with hexane (3 ꢁ 2 ml) and dried in vacuum.
[PtMe{3-(20-ClC6H4CH2NCH)C4H2O}] (4b). Yield: 96
ꢀ
4.4. Detection of compounds 3c and 3d
mg (70%). 1H NMR (200 MHz, acetone-d6): d ¼ 1:19 [s,
3
2J(Pt–H) ¼ 82, Mea]; 2.02 [s, J(Pt–H) ¼ 30, Meb]; 5.05
15 mg of compound [Pt2Me4(l-SMe2)2] and 10 mg of
the corresponding ligand were dissolved in 0.7 ml of
[s, J(Pt–H) ¼ 13, Hc]; {6.45 [d, J(H–H) ¼ 2, 1H], 7.23 [m,
2H], 7.37 [m, 2H], 7.48 [d, J(H–H) ¼ 2, J(Pt–H) ¼ 20,
1H], aromatics}; 8.19 [s, 3J(Pt–H) ¼ 32, Hd]. 195Pt NMR
(54 MHz, CDCl3): d ¼ ꢀ4099 [s]. FAB(+)-MS, m=z: 475
[M–Me], 428 [M–SMe2], 413 [M–Me–SMe2]. Anal.
Found: C, 37.2; H, 3.6; N, 3.1. Calc. for C15H18ClN-
OPtS: C, 36.70; H, 3.70; N, 2.85%.
1
acetone-d6 in an NMR tube and H NMR spectra were
taken. After several minutes, the formed orange solids
were collected by filtration, dried and analyzed by
FAB-mass spectroscopy (3c). [PtMe2{3-(Me2NCH2-
ꢀ
1
CH2NCH)C5H4N}] (3c): H NMR (200 MHz, CDCl3):
2
2
d ¼ 0:01 [s, J(Pt–H) ¼ 91, Mea]; 0.45 [s, J(Pt–H) ¼ 85,
Meb]; 2.73 [m, Hd]; 2.77 [s, J(H–Pt) ¼ 22, Hc]; 4.10 [t,
3
J(H–H) ¼ 5, He]; 7.36 [dd, J(H–H) ¼ 8, J(H–H) ¼ 5, 1H,
H5]; 8.70 [dd, J(H–H) ¼ 5, J(H–H) ¼ 2, 1H, H6]; 9.05
4.7. Synthesis of compound 5a
[dd, J(H–H) ¼ 8, J(H–H) ¼ 2, 1H, H4]; 9.26 [s, J(Pt–
An excess of methyl iodide (0.5 ml) was added to a
solution of 50 mg of compound 4a. After continuous
stirring at room temperature, an insoluble red residue
was filtered off and discarded. The solvent was removed
and the residue was recrystallized in dichloromethane-
hexane to yield an orange solid which was dried in
3
H) ¼ 47, Hf ]; 9.45 [s, H2]. FAB-MS(NBA): 385
[M–Me], 370 [M–2Me]. [PtMe2{4-(Me2NCH2CH2-
NCH)C5H4N}] (3d): 1H NMR (200 MHz, CDCl3):
ꢀ
2
2
d ¼ 0:01 [s, J(Pt–H) ¼ 92, Mea]; 0.48 [s, J(Pt–H) ¼ 85,
Meb]; 2.76 [m, Hd]; 2.77 [s, J(H–Pt) ¼ 22, Hc]; 4.12 [t,
3
J(H–H) ¼ 5, He]; {8.35 [d, J(H–H) ¼ 6], 8.62 [d, J(H–
vacuum.
(5a). Yield: 35 mg (43%). 1H NMR (200 MHz, CDCl3):
[PtMe2I{3-(Me2NCH2CH2NCH)C4H2O}]
ꢀ
H) ¼ 6], H2;3}; 9.29 [s, J(Pt–H) ¼ 46, Hf ].
3
2
2
d ¼ 0:85 [s, J(Pt–H) ¼ 69, Meb]; 1.40 [s, J(Pt–H) ¼ 65,
Mea]; {2.58 [s, J(H–Pt) ¼ 19], 3.24 [s, J(H–Pt) ¼ 14],
Mec}; {3.04 [m, 1H], 4.01–4.24 [m, 3H], Hd;e}; {6.49 [d,
J(H–H) ¼ 2], 7.43 [d, J(H–H) ¼ 2, J(Pt–H) ¼ 12], H4;5};
8.10 [s, 3J(Pt–H) ¼ 32, Hf ]. 195Pt NMR (54 MHz,
CDCl3): d ¼ ꢀ2657 [s]. FAB(+)-MS, m=z: 390 [M–I],
375 [M–I–Me], 360 [M–I–2Me]. Anal. Found: C, 25.3;
H, 3.8; N, 4.9. Calc. for C11H19IN2OPt: C, 25.54 ; H,
3.70; N, 5.42%.
3
3
4.5. Synthesis of compound 4a
Compound 4a was obtained by refluxing during two
hours a toluene solution (20 ml) containing 100 mg of
compound 3a. The solvent was removed in a rotary
evaporator and the red residue was washed with ether
(3 · 2 ml) to yield a brown-orange solid which was
washed with ether and dried in vacuum. [PtMe{3-
ꢀ
(Me2NCH2CH2NCH)C4H2O}] (4a). Yield: 75 mg
(78%). 1H NMR (200 MHz, acetone-d6): d ¼ 1:07 [s,
2J(Pt–H) ¼ 80, Mea]; 2.81 [s, 3J(Pt–H) ¼ 24, Meb];
{3.16 [t, J(H–H) ¼ 6], 3.95 [t, J(H–H) ¼ 6], Hc;d}; {6.36
[d, J(H–H) ¼ 2], 7.37 [d, J(H–H) ¼ 2, J(Pt–H) ¼ 18],
4.8. Reactions with triphenylphosphine
Compounds 6 were obtained by adding a solution of
two equivalents of triphenylphosphine to solutions of
the corresponding compound 4 in acetone (4a: 25 mg,
6.7 · 10ꢀ5 mol; 4b: 25 mg, 5.1 · 10ꢀ5 mol) and stirring
the resulting solutions at room temperature for 3 h. The
acetone was removed in a rotary evaporator and the
3
H4;5}; 8.18 [s, J(Pt–H) ¼ 36, He]. 13C NMR (75 MHz,
CDCl3): d ¼ ꢀ18:27 [J(Pt–C) ¼ 750, Mea]; 48.91 [Cb];
{51.40 [J(C–Pt) ¼ 24], 68.54 [s], Cc;d}; 107.05 [J(C–

1502
C. Anderson, M. Crespo / Journal of Organometallic Chemistry 689 (2004) 1496–1502
residue was washed with hexane (3 · 2 ml) and ether
(3 · 2 ml) and dried in vacuum.
(c) M. Hissler, J. McGarrah, W.B. Connick, D.K. Geiger, S.D.
Cummings, R. Eisenberg, Coord. Chem. Rev. 208 (2000) 115;
(d) M. Crespo, C. Grande, A. Klein, J. Chem. Soc., Dalton Trans.
(1999) 1629, and references within.
4.9. [PtMe{3-(Me2NCH2CH2NCH)C4H2O}(PPh3)2]
(6a)
[2] C.M. Anderson, M. Crespo, M.C. Jennings, A.J. Lough, G.
Ferguson, R.J. Puddephatt, Organometallics 10 (1991) 2672.
ꢀ
[3] C. Anderson, M. Crespo, M. Font-Bardıa, A. Klein, X. Solans, J.
1
Organomet. Chem. 601 (2000) 22.
[4] (a) M. Nonoyama, Transition Met. Chem. 15 (1990) 366;
Yield: 35 mg (58%). H NMR (200 MHz, CDCl3):
d ¼ 0:48 [dd, 2J(Pt–H) ¼ 66, J(P–H) ¼ 9; 7, Mea]; 2.33 [s,
Meb]; {2.53 [t, J(H–H) ¼ 8], 3.60 [t, J(H–H) ¼ 8], Hc; d};
{6.39 [d, J(H–H) ¼ 2, 1H], 7.03–7.72 [m], aromatics};
8.57 [s, He]. 31P NMR (101.25 MHz, CDCl3): d ¼ 24:20
[d, 1J(Pt–P) ¼ 1826, J(P–P) ¼ 14]; 26.25 [d, 1J(Pt–
P) ¼ 2141, J(P–P) ¼ 14]. 195Pt NMR (54 MHz, CDCl3):
d ¼ ꢀ4627 [dd, J(P–Pt) ¼ 2149; 1827]. FAB(+)-MS, m=z:
719 [Pt(PPh3)2], 455 [Pt(PPh3)], 377 [M-2 PPh3].
(b)
533.
M. Nonoyama, K. Nakajima, Polyhedron 18 (1998)
[5] (a) S. Dholakia, R.D. Gillard, F.L. Wimmer, Inorg. Chim. Acta
69 (1983) 179;
(b) A. Zucca, A. Doppiu, M.A. Cinellu, S. Stoccoro, G.
Minghetti, M. Manassero, Organometallics 21 (2002) 783–785.
[6] E.C. Constable, J. Chem. Soc., Dalton Trans. (1985) 1719.
[7] A. Doppiu, G. Minghetti, M.A. Cinellu, S. Stoccoro, A. Zucca,
M. Manassero, Organometallics 20 (2001) 1148.
[8] P.S. Pregosin, Coord. Chem. Rev. 44 (1982) 247.
[9] J. March, in: Advanced Organic Chemistry, Wiley, New York,
1985, pp. 37–45.
4.10. [PtMe{3-(20-ClC6H4CH2NCH)C4H2O}(PPh3)2]
(6b)
ꢀ
[10] (a) C. Navarro-Ranninger, I. Lopez-Solera, A. Alvarez-Valdes,
J.M. Rodrıguez-Ramos, J.R. Masaguer, J.L. Garcia-Ruano,
ꢀ
ꢀ
1
Yield: 30 mg (62%). H NMR (200 MHz, CDCl3):
2
Organometallics 12 (1993) 4104;
(b) A. Crispini, M. Ghedini, J. Chem. Soc., Dalton Trans. (1997)
d ¼ 0:48 [dd, J(Pt–H) ¼ 66, J(P–H) ¼ 9; 7, Mea]; 4.74
[s, Hb]; {6.46 [d, J(H–H) ¼ 2, 1H], 7.06–7.40 [m], aro-
matics}; 8.68 [s, He]. 31P NMR (101.25 MHz, CDCl3):
d ¼ 24:11 [d, 1J(Pt–P) ¼ 1824, J(P–P) ¼ 14]; 26.21 [d,
1J(Pt–P) ¼ 2147, J(P–P) ¼ 14]. 195Pt NMR (54 MHz,
CDCl3): d ¼ ꢀ4627 [dd, J(P–Pt) ¼ 2164; 1828]. FAB(+)-
MS, m=z: 734 [PtMe(PPh3)2], 719 [Pt(PPh3)2], 455
[Pt(PPh3)].
75.
[11] L.M. Rendina, R.J. Puddephatt, Chem. Rev. 97 (6) (1997)
1735.
ꢀ
[12] (a) M. Crespo, M. Martinez, J. Sales, X. Solans, M. Font-Bardıa,
Organometallics 11 (1992) 1288;
(b) M. Crespo, C. Grande, A. Klein, J. Chem. Soc., Dalton Trans.
(1999) 1629.
ꢀ
[13] (a) M. Crespo, X. Solans, M. Font-Bardıa, J. Organomet.Chem.
518 (1996) 105;
(b) M. Crespo, C. Grande, A. Klein, M. Font-Bardıa, X. Solans,
J. Organomet. Chem. 563 (1998) 179.
ꢀ
Acknowledgements
ꢀ
[14] M. Crespo, X. Solans, M. Font-Bardıa, Organometallics 14 (1995)
355.
[15] O. Lopez, M. Crespo, M. Font-Bardıa, X. Solans, Organometal-
ꢀ
lics 16 (1997) 1233.
ꢀ
This work was supported by the Ministerio de Cien-
ꢀ
ER) and by the Comissionat per a Universitats I
Recerca (project: 2001SGR-00054). We also acknowl-
edge the support of Orgometa.
cia y Tecnologıa (project: BQU2003-00906/50% FED-
ꢀ
[16] (a) C. Anderson, M. Crespo, M. Font-Bardıa, X. Solans, J.
Organomet. Chem. 604 (2000) 178;
(b) C. Anderson, M. Crespo, F. Rochon, J. Organomet. Chem.
631 (2001) 164.
[17] R. Benn, R.D. Reinhard, A. Rufinska, J. Organomet. Chem. 282
(1985) 291.
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