Di- and trinuclear phosphido-bridged platinum complexes. Crystal structures of [Pt{CH2=CHC(O)OMe}(PPh3)2], trans-[Pt 2(μ-PPh2)2I2(PPh 3)2] and cis,cis,cis-[

Article abstract of DOI:10.1039/b901563a

The readily available Pt(0) methyl acrylate complex [Pt{CH ₂CHC(O)OMe}(PPh₃)₂] (2) allows access to the known, mixed-valence trinuclear cluster [Pt₃(μ-PPh ₂)₃Ph(PPh₃)₂

Full text of DOI:10.1039/b901563a

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Di- and trinuclear phosphido-bridged platinum complexes. Crystal structures
of [Pt{CH2=CHC(O)OMe}(PPh3)2], trans-[Pt2(l-PPh2)2I2(PPh3)2] and
cis,cis,cis-[Pt3(l-I)2(l-PPh2)2Cl0.5I1.5(PPh3)2]†‡
Robert Bender,a Coco Okio,a Richard Welterb and Pierre Braunstein*a
Received 23rd January 2009, Accepted 14th April 2009
First published as an Advance Article on the web 12th May 2009
DOI: 10.1039/b901563a
=
The readily available Pt(0) methyl acrylate complex [Pt{CH2 CHC(O)OMe}(PPh3)2] (2) allows access
to the known, mixed-valence trinuclear cluster [Pt3(m-PPh2)3Ph(PPh3)2] (3) in 64% yield. Oxidation of 3
with 2 equivalents of I2 afforded the new trinuclear complex [Pt3(m-I)2(m-PPh2)2I2(PPh3)2] (4) whose
molecular structure is similar to that of the related compound of empirical formula
[Pt3(m-I)2(m-PPh2)2Cl0.5I1.5(PPh3)2] (5) which has been generated by oxidation of 3 with successively 1
equivalent of I2 and 1 equivalent of C6H5ICl2. In these complexes, the four halogen atoms lie on the
same side of the almost aligned platinum atoms and the nearly square-planar coordination planes of
the metal atoms adopt a “japanese screen”, chair-like conformation. The reaction of the dinuclear,
metal–metal bonded Pt(I)–Pt(I) complex [Pt2(m-PPh2)2(PPh3)2] with one equivalent of I2 afforded the
Pt(II) complex [Pt2(m-PPh2)2I2(PPh3)2] (6). The molecular structures of complexes 2·CH2Cl2,
[Pt3(m-I)2(m-PPh2)2(I1.3Cl0.7)(PPh3)2][Pt3(m-I)2(m-PPh2)2(I1.7Cl0.3)(PPh3)2]·C6H5Cl·3CH2Cl2
(5A·5B·C6H5Cl·3CH2Cl2) and 6 have been established by single crystal X-ray diffraction studies.
=
[Pt{CH2 CHC(O)OMe}(PPh3)2] (2) and report further studies
Introduction
on its oxidation and that of [Pt2(m-PPh2)2(PPh3)2] with halogens,
Thermolysis of triphenylphosphine Pt(0) complexes, such as
[Pt(PPh3)n]1,2 or [Pt(C2H4)(PPh3)2],3,4 has long been known to
produce red solutions which contain d9–d9 metal–metal bonded
dinuclear complexes, such as [Pt2(m-PPh2)2(PPh3)2]1,3,4 and [Pt2(m-
o-C6H4PPh2)(m-PPh2)(PPh3)2],2,5 and the triangular cluster [Pt3(m-
PPh2)3Ph(PPh3)2] (3)1–4 in poor to medium yield. The latter, mixed-
valence [2¥Pt(I) + Pt(II)] cluster has the remarkable property
of displaying different isomeric solid-state structures depending
on the solvent used for its crystallization.1,3,4,6 This translates in
which afforded new di- and trinuclear Pt(II) complexes.
Results and discussion
=
Synthesis of [Pt{CH2 CHC(O)OMe}(PPh3)2] (2) and its
transformation into [Pt3(l-PPh2)3Ph(PPh3)2] (3)
The transformations leading to 3 are summarized in Scheme 1.
considerable variations of the separation between the formally
1
Pt(I) centres, which ranges from 3.074(4)3,4 to 3.630(1) A.
˚
Polynuclear phosphido complexes of platinum continue to attract
considerable attention because of their diversified structures and
rich chemistry,7 including redox aspects.8 The reactivity of 3 has
been examined towards oxidation, which was shown to induce
reductive coupling of PPh2 and phenyl groups,9 and towards
various silanes and siloxanes which afforded the first platinum
clusters containing a direct Pt–Si bond.10 However, the limited
yields of its preparation have prevented extensive studies of this
cluster. Herein we describe a new and improved synthesis of
cluster 3 by thermolysis of the Pt(0) methyl acrylate complex
aLaboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177
CNRS), Universite´ de Strasbourg, 4 rue Blaise Pascal, F-67070, Strasbourg-
Ce´dex, France. E-mail: braunstein@chimie.u-strasbg.fr
bLaboratoire DECOMET, Institut de Chimie (UMR 7177 CNRS), Univer-
site´ de Strasbourg, 4 rue Blaise Pascal, F-67070, Strasbourg-Cedex, France
Scheme 1
† Dedicated to Professor Helmut Werner, on the occasion of his 75th
birthday, with our warmest congratulations.
‡ Electronic supplementary information (ESI) available: ORTEP plots of
the crystal structures and views of the crystal packing in 5A·5B. CCDC
reference numbers 71938–71940. For ESI and crystallographic data in CIF
or other electronic format see DOI: 10.1039/b901563a
Refluxing a suspension of the Pt(0) complex [Pt(C2H4)(PPh3)2]
(1) in acetone with an excess of methyl acrylate for 24 h afforded
=
[Pt{CH2 CHC(O)OMe}(PPh3)2] (2) in high yield. This and
analogous Pt(0) olefin complexes have been prepared similarly.11,12
1
The 31P{ H} NMR spectrum of 2 contains signals at d 30.85
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higher 1J(Pt–P) value is assigned to P(1) and a 1H/31P NMR 2D
experiment showed that P2, which has the smaller 1J(Pt–P) value,
is coupled to two different protons. This leads to the following
Table 1 Selected bond distances (A) and angles (◦) for
˚
[Pt{CH2=CHC(O)OMe}(PPh3)2]·CH2Cl2 (2·CH2Cl2)
Pt–P1
Pt–P2
2.2659(9)
2.2903(11)
2.099(3)
2.128(3)
1.438(4)
1.466(4)
1.347(4)
1.214(4)
1.450(4)
P1–Pt–P2
106.00(4)
105.82(10)
108.41(8)
39.76(12)
110.6(3)
126.3(3)
116.0(3)
123.0(3)
112.3(2)
1
assignment of the 31P{ H} NMR signals: P(1) at 30.85 ppm and
P1–Pt–C37
P2–Pt–C38
C37–Pt–C38
C38–C39–O1
C38–C39–O2
C39–O1–C40
O2–C39–O1
Pt–C38–C39
P(2) at 31.9 ppm. The methyl acrylate mean plane containing
C38, C39, O1 and O2 makes an angle of 79.37(13)◦ with respect
to the Pt coordination plane. All these data are consistent with
those found in the structures of related bis(phosphine) Pt(0) alkene
complexes.11,12,14
Pt–C37
Pt–C38
C37–C38
C38–C39
C39–O1
C39–O2
O1–C40
Whereas [Pt(C2H4)(PPh3)2] (1) is thermally transformed into
Pt2 and Pt3 complexes already in boiling acetone, refluxing an
acetone solution of 2 for 3 days did not lead to any transforma-
tion, indicating the stability of this complex. However, refluxing
a toluene solution of 2 for 5 h afforded the cluster [Pt3(m-
PPh2)3Ph(PPh3)2] (3), which has been isolated in an improved
and 31.9 ppm, typical of an AB system, attributed to the two
chemically different phosphorus atoms, with a J(P–P) coupling
2
of 42 Hz consistent with their mutual cis relationship and flanked
1
by 195Pt satellites with J(Pt–P) couplings of 4056 and 3559 Hz,
1
yield of 64% and characterized by 31P{ H} NMR spectroscopy.3
respectively. These data are consistent with those found for this
and related [Pt(olefin)(PPh3)2] complexes.11–13
1
According to 31P{ H} NMR spectroscopy, the mother liquor of 3
contained only the precursor 2. Further heating of this solution
for 12 h afforded the familiar red solution which contains di-
and trinuclear Pt complexes, from which 3 has been previously
isolated.2,3 Since in an independent reaction, we did not observe
any transformation of pure 3 when it was heated in toluene for a
few hours, we believe that the dinuclear complexes formed result
directly from 2. A detailed mechanism explaining the simultaneous
presence of di- and trinuclear complexes starting from various
bis(triphenylphosphine)platinum(0) complexes is still lacking but
it is most likely that the temperature at which the coordinatively
unsaturated Pt(PPh3)2 fragment is generated from the 16e complex
[Pt(PPh3)2(olefin)] plays a critical role.
An X-ray diffraction study was performed on a single crystal
of 2 obtained from a CH2Cl2 solution layered with pentane. Its
molecular structure is shown in Fig. 1 and selected bond lengths
and angles are given in Table 1. A molecule of CH2Cl2 crystallizes
in the unit cell for each molecule of complex.
A comparison of our results with those obtained by Ben-
nett et al.2 concerning the yields of the complexes [Pt2(m-o-
C6H4PPh2)(m-PPh2)(PPh3)2] and 3 after different times of thermol-
ysis of [Pt(C2H4)(PPh3)2] suggested that formation of this dinuclear
complex results from in situ transformation of 3. However, heating
an equimolar mixture of 3, [Pt(C2H4)(PPh3)2] and PPh3 for 3 h
did not afford any dinuclear complex (see Experimental section),
although thermolysis of [Pt(C2H4)(PPh3)2] alone does, which
confirms the importance of generating in situ the coordinatively
unsaturated 14e fragment Pt(PPh3)2.
Synthesis and characterization of cis,cis,cis-[Pt3(l-I)2(l-
PPh2)2I2(PPh3)2] (4) and molecular structure of cis,cis,cis-[Pt3(l-
I)2(l-PPh2)2(I1.3Cl0.7)(PPh3)2][Pt3(l-I)2(l-PPh2)2(I1.7Cl0.3)(PPh3)2]·
C6H5Cl·3CH2Cl2 (5A·5B·C6H5Cl·3CH2Cl2)
Fig. 1 ORTEP view of 2 in 2·CH2Cl2 with partial labelling scheme. The
ellipsoids enclose 50% of the electronic density. Hydrogen atoms and
solvent molecules are omitted for clarity.
The reactivity of cluster 3 towards the electrophiles I2 or H+ has
been studied and found to induce in the former case a reductive
coupling reaction between a PPh2 group and the phenyl ligand,
while retaining in the cationic product [Pt3(m-I)(m-PPh2)2(PPh3)3]+
the trinuclear nature of the original cluster.9 Since the two electron
oxidation of 3 by one equivalent of I2 did not alter the oxidation
states of the Pt atoms [2 Pt(I) + 1 Pt(II)], it should still be possible
to oxidize it further with a second equivalent of I2 and we have now
found that two equivalents of I2 transform 3 into the new complex
[Pt3(m-I)2(m-PPh2)2I2(PPh3)2] (4) which forms a yellow, air-stable
powder, poorly soluble in organic solvents (Scheme 2).
=
When considering the mid-point of the C C double bond
of the p-bonded CH2=CHC(O)OMe ligand, the Pt atom has a
Y-shape, planar coordination geometry, being further surrounded
by two PPh3 ligands. This is as expected for a 16e Pt(0)L3-type
complex. The coordination geometry around the Pt atom is almost
planar, the angle between the PtC2 and PtP2 planes being 3.4(2)◦.
=
The C C double bond of the methyl acrylate ligand is linked to
the Pt atom in a slightly asymmetric manner: Pt–C37 = 2.099(3)
˚
and Pt–C38 = 2.128(3) A. The longer platinum–phosphorus bond
1
˚
[Pt–P2 = 2.2903(11) A] is in trans position with respect to the
Despite the low solubility of this complex, its 31P{ H} NMR
˚
CH2 group and the shorter one [Pt–P1 = 2.2659(9) A] is trans
spectrum could be recorded and it contains two singlets of equal
intensities, at 12.2 and -75.0 ppm, with one and two sets of
195Pt satellites resulting from the 1J(Pt–P) coupling constants,
to the carbon atom bearing the carboxylate group, which has
a weaker trans-influence than the CH2 group. Consistently, the
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Table 2 Selected bond distances (A) and angles (◦) for 5A in
·5B·C6H5Cl·3CH2Cl2
˚
Pt1–I1
Pt1–I3
Pt1–P1
Pt1–P2
Pt2–I1
Pt2–I2
Pt2–P2
Pt2–P3
Pt3–I2
Pt3–X1
Pt3–P3
Pt3–P4
2.659(2)
2.602(2)
2.235(4)
2.284(4)
2.6694(15)
2.6896(19)
2.254(4)
2.265(3)
2.6773(18)
2.417(3)
2.267(4)
2.241(3)
I1–Pt1–I3
I3–Pt1–P1
P1–Pt1–P2
I1–Pt1–P2
I1–Pt2–I2
I1–Pt2–P2
P2–Pt2–P3
I2–Pt2–P3
I2–Pt3–P3
I2–Pt3–X1
X1–Pt3–P4
P3–Pt3–P4
Pt1–I1–Pt2
Pt2–I2–Pt3
Pt1–P2–Pt2
Pt2–P3–Pt3
88.93(7)
88.08(11)
103.48(14)
82.53(10)
90.02(5)
82.86(10)
106.12(12)
83.11(9)
83.36(9)
85.62(9)
90.94(12)
101.82(12)
78.75(5)
74.96(5)
96.31(14)
92.20(13)
followed by one equivalent of PhICl2, and complete conversion of
3 to a new compound occurred. These reactions were performed
with the original objective, which was not fulfilled (see below),
to monitor the oxidation steps by sequential introduction of first
iodide and then chloride ions as “tags”, the reverse sequence being
likely to give rise to anion metathesis of chlorides by iodides.
Crystals of the product suitable for X-ray diffraction were obtained
and an ORTEP view is shown in Fig. 2 and selected bond distances
and angles are given in Table 2. The asymmetric unit contains two
different molecules, 5A and 5B, whose main difference resides in
the occupancy factor of the terminal halogen atoms (iodine or
chlorine) of one site (see Fig. 2). A terminal halide position in
5A is occupied at 30% by iodine and at 70% by chlorine, while
in 5B it is occupied at 70% by iodine and at 30% by chlorine
(see ESI‡). The asymmetric unit contains also one molecule
of chlorobenzene and three molecules of dichloromethane. This
confers on this complex in the crystal the formula [Pt3(m-
I)2 (m-PPh2)2 (I1.3Cl0.7)(PPh3)2][Pt3 (m-I)2 (m-PPh2)2 (I1.7Cl0.3)(PPh3)2]·
C6H5Cl·3CH2Cl2 (5A·5B·C6H5Cl·3CH2Cl2).
Scheme 2
respectively. The former signal corresponds to terminal phos-
1
phines with J(Pt–P) = 4402 Hz and the latter to the phosphido
1
groups bridging two different Pt atoms, with J(Pt–P) = 3320
and 2639 Hz. There is no significant P–P coupling between these
signals, which indicates that these nuclei are in mutual cis positions.
Therefore, the structure of complex 4 is expected to contain the
following fragment:
The other substituents of the Pt atoms are the iodine atoms and
the complete ligand arrangement should be as shown in Scheme 2.
Suitable crystals of 4 for X-ray diffraction could not be
obtained. However, a closely related complex was obtained when
the oxidation reaction was performed by using one equivalent I2
Fig. 2 ORTEP view of the core atoms of 5A in 5A·5B·C6H5Cl·3CH2Cl2 with partial labelling scheme. Only the ipso carbon atoms of the phenyl groups
are shown. The position of the Pt(3)-bound halide in 5A is occupied at 30% by iodine and at 70% by chlorine, while in 5B it is occupied at 70% by iodine
and at 30% by chlorine. The ellipsoids enclose 50% of the electronic density. Hydrogen atoms and solvent molecules are omitted for clarity.
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Table 2 contains a selection of bond distances and angles for
molecule 5A only, since the data for molecule 5B are very similar
(for details see corresponding cif file‡). Each molecule contains
three, almost aligned and nearly square-planar Pt atoms, without
direct metal–metal bonding (Pt1–Pt2 = 3.380(1) and Pt2–Pt3 =
form a roof-angle of about 132◦, which gives a “japanese screen”-
type arrangement to the skeleton of 5A and 5B (Fig. 4).
˚
3.265(1) A in 5A). The corresponding Pt–Pt distances in 5B, Pt4–
˚
Pt5 = 3.516(1) and Pt5–Pt6 = 3.425(1) A, present the largest
differences between bond lengths in 5A and 5B. Each external Pt
atom bears a PPh3 and a halide ligand, both in terminal positions,
while the inner Pt2 is connected to Pt1 and Pt3 by two m-PPh2
groups and two bridging iodo ligands. All the halides lie on the
same side of the triplatinum line, and the phosphorus ligands on
the opposite side (Fig. 3), which results in a cis arrangement for
each Pt atom.
Fig. 4 “Japanese screen”-type arrangement formed by the three consec-
utive square planes around the Pt(II) centres in 5A.
Few trinuclear Pd or Pt complexes consisting of bridge-
connected square-planar units have been published7a,7c,7e,8a,17,18
and examples of both chair and boat conformations have been
identified by X-ray diffraction.18 The sequence of edge-sharing
square-planes in 5A forms a chair-type arrangement. In all the
platinum complexes containing four halogens and two phosphido
bridges, the halogens lie on the same side of the metal atoms
and the phosphides on the other side, as in 5. The number of
anionic ligands (4 halides and 2 phosphido groups) in 5 confirms
the oxidation of the two Pt(I) centres of 3 into Pt(II) in 4 and
5, in agreement with the absence of any Pt–Pt bond and the
coordination geometry around each metal atom.
Fig. 3 View of the core atoms of 5A in (5A·5B·C6H5Cl·3CH2Cl2)
emphasizing the nearly coplanar arrangement of the atoms Pt1, Pt2, Pt3,
I2, I3, P2 and P4 (orange plane) and Pt1, Pt2, Pt3, I1, I/Cl, P1 and P3
(blue plane), respectively.
The ligands around each Pt atom are almost coplanar, but
the coordination geometry of these metal atoms is not a regular
square, the angles around them vary from about 81◦ to more than
106◦. The mean-values for the angles in molecules 5A and 5B are
the following: P–Pt–P = 102.8◦, I–Pt–I = 89.3◦ and I–Pt–P = 83◦
for the angles at the Pt atoms, and Pt–P–Pt = 96.5◦, Pt–I–Pt = 79◦
for those at the bridging atoms. All these bond lengths and angles
have values similar to those found in analogous complexes.5,9,15–17
The Pt–I distances being longer than the Pt–P distances and
the PPh2 groups being sterically more demanding than an iodine
atom, explains why the P–Pt–P angles at Pt are larger than the
I–Pt–I angles and also why the Pt–P–Pt angles are larger than the
Pt–I–Pt ones.
The reaction of 3 with one equivalent of I2 followed by one
equivalent of PhICl2 as oxidants was expected to form a mixed
dichloro, diiodo triplatinum complex. However, the isolation
of compound 5 reveals that 4 electron oxidation occurs with
1
redistribution reactions between the halogen atoms. The 31P{ H}
NMR spectrum of this reaction mixture shows various signals
from 12 to 17 ppm in the range of terminal PPh3 ligands and
from -60 to -70 ppm for phosphido groups bridging Pt atoms not
linked by metal–metal bonds. These signals could be attributed to
different trinuclear complexes, with different Cl/I ratios.
Synthesis and molecular structure of [Pt2(l-PPh2)2I2(PPh3)2] (6)
The overall structure of complexes 5A and 5B is not flat. The
coordination planes of two consecutive Pt atoms in each molecule
For comparison, iodine oxidation was also applied to the dinuclear
complex [Pt2(m-PPh2)2(PPh3)2]1,3,4 which contains a Pt–Pt bond
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Scheme 3
Table 3 Selected bond distances (A) and angles (◦) for [Pt2(m-
˚
with I2 to give Pt(II) centres in 6. All the geometrical data
for this complex are consistent with those found in similar
complexes.4,5,15,16 The coordination planes of the platinum atoms
make a roof-angle of 164.4◦.
PPh2)2I2(PPh3)2] (6)
Pt–I
2.6536(16)
2.3221(16)
2.3374(17)
2.2688(19)
P1–Pt–P1¢
P1–Pt–I
P1¢–Pt–P2
P2–Pt–I
75.30(7)
94.19(5)
100.58(7)
91.18(5)
103.49(7)
Pt–P1
Pt–P2
Pt–P1¢
1
The 31P{ H} NMR spectrum of complex 6 belongs to a
AA¢MM¢XX¢ spin system in which A represents the 31P nuclei
of the phosphines, M that of the phosphido bridges and X the
195Pt nuclei. For the AA¢MM¢ subsystem, six lines appear for each
of the AA¢ and the MM¢ parts. Simulation of these signals gave
the following values: 2J(P–P) = 378.4, 199.5 and 7.7 Hz between
Pt–P1–Pt¢
bridged by two PPh2 groups. This compound reacted with one
equivalent I2 in a tetrahydrofuran solution, to yield [Pt2(m-
PPh2)2I2(PPh3)2] (6) in spectroscopic quantitative yield (Scheme 3).
Recrystallization from a mixture of CH2Cl2 and pentane
afforded pale yellow crystals of a new complex, whose molecular
structure was solved by X-ray diffraction (Table 3 and Fig. 5).
Complex 6 is constituted by two Pt atoms bridged by two
phosphido groups, each Pt bearing in addition a PPh3group and an
iodide ligand in terminal, mutually cis positions, in such a way that
the PPh3, and the iodide ligands, are anti to each other. The Pt2P4I2
skeleton has C2 symmetry with the twofold axis perpendicular to
the Pt, Pt¢, P1, P1¢ mean plane and intersecting the middle of the
Pt–Pt¢ axis. The ligands around the platinum atoms are almost
coplanar, but the angles between them are irregular, in particular
P1–Pt–P1¢ = 75.30(7)◦ and P1¢–Pt–P2 = 100.58(7)◦ are far from
90◦. In addition, the angle at the phosphido bridge, Pt–P1–Pt¢ =
103.49(7)◦, is larger than those found in 5. As a consequence, the
4
P1 and P2, P1 and P1¢, and P1¢ and P2, respectively, and J(P2–
P2¢) = -9.4 Hz. These values are consistent with those determined
for similar complexes.19 In addition, the signals of the phosphine
ligands at d 21.6 and of the phosphido groups at d -164.4 show
pseudo first order 195Pt satellite signals: a doublet with 1J(Pt–P) =
1
2165 Hz and two doublets with J(Pt–P) = 2384 and 1870 Hz,
respectively.
In conclusion, we have described here an improved synthesis
of the mixed-valence platinum cluster [Pt3(m-PPh2)3Ph(PPh3)2]
=
starting from [Pt{CH2 CHC(O)OMe}(PPh3)2] (2) and found
that its controlled oxidation afforded the trinuclear complex
cis,cis,cis-[Pt3(m-I)2(m-PPh2)2I2(PPh3)2] (4). The dinuclear Pt(II)
complex trans-[Pt2(m-PPh2)2I2(PPh3)2] (6) was obtained by oxida-
tion with I2 of the dinuclear, metal–metal bonded Pt(I) complex
[Pt2(m-PPh2)2(PPh3)2]. The crystal structures of 2·CH2Cl2, cis,cis,
cis-[Pt3(m-I)2(m-PPh2)2Cl0.5I1.5(PPh3)2]·0.5C6H5Cl·1.5CH2Cl2 (5·0.
5C6H5Cl·1.5CH2Cl2), which is similar to 4, and 6 unambiguously
established the structural details and revealed in the case of
˚
non-bonding Pt–Pt¢ distance, 3.605(1) A, is in the range of the
largest Pt–Pt distance in 5. This accounts for the rupture of
the Pt(I)–Pt(I) bond in [Pt2(m-PPh2)2(PPh3)2] upon oxidation
Fig. 5 ORTEP view of 6 with partial labelling scheme. Only the ipso carbon atoms of the corresponding phenyl groups are shown. The ellipsoids enclose
50% of the electronic density. Hydrogen atoms are omitted for clarity. Equivalent position¢ : -x + 1, y, -z + 1/2.
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5 an unusual “japanese screen”-type chair arrangement of the
skeleton.
second crop of crystals. Yield: 0.90 g (1.00 mmol, 75%). Anal.
Calcd for C41H38P2Cl2O2Pt: C, 55.29; H, 4.30. Found: C, 54.97;
1
H, 4.35. 31P{ H} NMR (CD2Cl2): d 30.85 (1J(Pt–P) = 4056 Hz,
2J(P–P) = 50 Hz), 31.9 (1J(Pt–P) = 3559 Hz), 2J(P–P) = 42 Hz).
Experimental
[Pt3(l-PPh2)3Ph(PPh3)2]·2CH2Cl2 (3·2CH2Cl2). A toluene so-
lution (30 mL) of [Pt{CH2=CHC(O)OMe}(PPh3)2]·CH2Cl2
(0.60 g, 0.67 mmol) was heated under reflux for 5 h. The red
solution was evaporated to dryness under vacuum. Recrystalliza-
tion from a mixture of CH2Cl2 and pentane at room temperature
afforded dark red crystals of 3·2CH2Cl2.4 Yield: 0.30 g (64% based
on Pt).
General
All manipulations were performed under nitrogen using standard
Schlenk techniques. The solvents employed were distilled from
appropriate drying agents prior to use. NMR spectra were
recorded on a Bruker AM 300 instrument, phosphorus chemical
shifts (in ppm) were referenced to 85% H3PO4 in H2O. All
coupling constants are in Hz. IR spectra were recorded in the
4000–400 cm-1 range on a Bruker IFS66 FT spectrophotome-
ter. [Pt(C2H4)(PPh3)2] was prepared according to a published
procedure.20 The complex [Pt2(m-PPh2)2(PPh3)2] was isolated from
the red mixtures obtained by thermolysis of [Pt(C2H4)(PPh3)2] in
acetone.1 Methyl acrylate was purchased from Aldrich and used
without further purification.
Attempt of transformation of [Pt3(l-PPh2)3Ph(PPh3)2] (3)
into [Pt2(l-o-C6H4PPh2)(l-PPh2)(PPh3)2]. A mixture of [Pt3(m-
PPh2)3Ph(PPh3)2]·2CH2Cl2 (0.191 g, 0.10 mmol), [Pt(C2H4)-
(PPh3)2] (0.075 g, 0.10 mmol) and PPh3 (0.026 g, 0.10 mmol) in
50 mL acetone was refluxed for 3 h and then cooled to room
temperature. The precipitated cluster [Pt3(m-PPh2)3Ph(PPh3)2]
(0.174 g, 0.10 mmol) was filtered and dried in vacuo. Evaporation
to dryness of the orange filtrate afforded a yellow solid (0.110 g).
1
Its 31P{ H} NMR spectrum in C6D6 showed a peak at 26.3 ppm
Syntheses
(OPPh3) and various signals in the range of terminal phosphines:
d 8.3 (s, 1J(Pt–P) = 3631 Hz), 11.8 (d, 1J(Pt–P) = 3592 Hz, J(P–
P) = 20 Hz), 12.7 (d, 1J(Pt–P) = 3573 Hz, 2J(P–P) = 18 Hz), 13.5
=
[Pt{CH2 CHC(O)OMe}(PPh3)2]·CH2Cl2 (2·CH2Cl2). To a
solution of [Pt(C2H4)(PPh3)2] (1.00 g, 1.34 mmol) in acetone
=
(30 mL) was added a large excess (1.2 mL) of CH2 CHC(O)OMe.
1
1
(d, J(Pt–P) = 3556 Hz, J(P–P) = 20 Hz), 13.9 (d, J(Pt–P) =
The solution was refluxed for 24 h and the solvent was evaporated
under reduced pressure. The residue was washed with diethylether,
dried under vacuum and recrystallized from a mixture of CH2Cl2
and pentane. Colourless crystals suitable for X-ray measurements
were grown at room temperature after a few days. The mother
liquor was again evaporated to dryness under vacuum, and
recrystallization of the residue from CH2Cl2/pentane afforded a
3497 Hz, 2J(P–P) = 20 Hz).
Cis,cis,cis-[Pt3(l-I)2(l-PPh2)2I2(PPh3)2] (4). To a solution of
[Pt3(m-PPh2)3Ph(PPh3)2]·2CH2Cl2 (0.096 g, 0.05 mmol) in 10 mL
of THF was added I2 (0.026 g, 0.10 mmol) and the red solution
rapidly darkened with formation of a yellow precipitate. After
the reaction mixture was stirred for 1 h at room temperature, the
Table 4 Crystal data and details of the structure determination for 2·CH2Cl2, 5A·5B·C6H5Cl·3CH2Cl2 and 6
2·CH2Cl2
5A·5B·C6H5Cl·3CH2Cl2
6
Formula
C40H36O2P2Pt,CH2Cl2
890.64
C129H111Cl8I7P8Pt6
4251.38
Triclinic
P-1 (No. 2)
17.028(2)
18.333(2)
22.087(2)
82.66(5)
74.61(5)
81.38(5)
6544.6(21)
2
2.157
C60H50I2P4Pt2
1538.86
FW [g mol-1]
Crystal system
Space group
Monoclinic
P21/n (No. 14)
12.160(2)
14.283(2)
21.322(2)
90
90.27(5)
90
3703.2(9)
4
1.597
Monoclinic
C2/c (No. 15)
17.684(5)
18.541(5)
17.775(5)
90
111.15(5)
90
5435(3)
˚
a [A]
˚
b [A]
˚
c [A]
a [◦]
b [◦]
g [◦]
V [A ]
Z
3
˚
4
D(calc) [g cm-3]
m(Mo-Ka) [mm-1]
F(000)
1.880
6.433
2928
0.04 ¥ 0.06 ¥ 0.08
173
0.71070
1.65, 30.01
-24:23;-26:23;-24:24
22342, 7915, 0.053
6526
4.054
1768
0.08 ¥ 0.10 ¥ 0.13
173
8.348
3960
0.10 ¥ 0.08 ¥ 0.08
173
Crystal size [mm3]
Temperature (K)
˚
Mo-Ka radiation [A]
0.71070
0.71070
q Min–max [◦]
2.38, 30.04
-17:17; 0:20; 0:30
10820, 10819, 0.000
7538
1.13, 27.88
-21:22; -23:24; 0:29
31118, 31118, 0.000
20399
Data set
Tot., uniq. data, R(int)
Observed data [I > 2.0 s(I)]
N
ref, Npar
10819, 433
0.0283, 0.0803, 0.98
31118, 1378
0.0768, 0.2310, 1.149
7915, 307
0.0462,0.1187, 1.185
R, wR2, S
w (with P = (Fo2+2Fc2)/3
1/[s (Fo2) + (0.0192P)2 + 0.3996P]
1/[s (Fo2) + (0.1391P)2 + 28.3253P]
1/[s (Fo2) + (0.0522P)2]
2
2
2
Max. and av. shift/error
0.00, 0.00
-2.09, 1.608
0.02, 0.00
-6.132, 4.000
0.00, 0.00
-2.94, 1.02
-3
˚
Min. and max. resd. dens. [e A ]
4906 | Dalton Trans., 2009, 4901–4907
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precipitate was filtered and washed with toluene. Attempts to grow
crystals suitable for X-ray analysis failed. Yield: 0.061 g, 60%.
Anal. Calcd for C60H50I4P4Pt3: C, 36.25; H, 2.54. Found: C,
Universitaire de la Francophonie for a post-doctoral grant to
C. O. We are grateful to Dr Clarisse Huguenard for the NMR
simulation using Windaisy software.
1
36.81; H, 3.07. 31P{ H} NMR (CH2Cl2/CD2Cl2): d 12.1 (PPh3,
1J(P–Pt) = 4402 Hz), -75.0 (m-PPh2, 1J(P–Pt) = 3320 and
References
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1
3.02. 31P{ H} NMR (CH2Cl2/CD2Cl2): d 21.6 (PPh3, 1J(P–Pt) =
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Single crystal X-ray diffraction analysis of 2·CH2Cl2,
(5A·5B·C6H5Cl·3CH2Cl2) and 6
Diffraction data were collected on a Kappa CCD diffractome-
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21
˚
0.71073 A). Crystallographic and experimental details are
summarized in Table 4. The structures were solved by direct
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procedures (based on F2, SHELXL-97) with anisotropic ther-
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Acknowledgements
21 Kappa CCD Operation Manual, Nonius BV, Delft, The Netherlands,
1997.
We thank the Centre National de la Recherche Scientifique
and the Ministe`re de la Recherche for support and the Agence
22 G. M. Sheldrick, SHELX97, Program for the refinement of crystal
structures, University of Go¨ttingen, Go¨ttingen, Germany, 1997.
This journal is
The Royal Society of Chemistry 2009
Dalton Trans., 2009, 4901–4907 | 4907
©