Thermal reactivity of cis- and trans-bis(triphenylgermyl)bis(tertiary phosphine)platinum(II)

Article abstract of DOI:10.1016/j.jorganchem.2006.05.065

The complex cis-Pt(Ph₃Ge)₂(PMe₂Ph)₂ underwent smooth isomerization to give the trans-isomer at room temperature via an associative five-coordinated intermediate. Thermodynamic parameters and activation energy for the cis to trans isomerization were obtained, ΔH^# = 105 kJ mol^-1, ΔS^# = 12.5 J mol^-1 K^-1, and Ea = 107 kJ mol^-1, respectively. Heating of trans-Pt(Ph₃Ge)₂(PMe₂Ph)₂ at 50 °C for 36 days produced trans-PtPh(Ph₃Ge)(PMe₂Ph)₂ followed by the formation of trans-PtPh₂(PMe₂Ph)₂, Pt(PMe₂Ph)₄, and Ph₄Ge finally via elimination of the phenyl group from Ph₃Ge ligand with liberation of the Ph₂Ge unit and subsequent reductive elimination of the remaining Ph₃Ge ligand at 80 °C for 1 month.

Full text of DOI:10.1016/j.jorganchem.2006.05.065

Journal of Organometallic Chemistry 692 (2007) 395–401
www.elsevier.com/locate/jorganchem
Thermal reactivity of cis- and
trans-bis(triphenylgermyl)bis(tertiary phosphine)platinum(II)
a,
a
a
a
Kunio Mochida *, Takashi Fukushima , Michiko Suzuki , Wakako Hatanaka ,
a
a
a
b
Mariko Takayama , Yoko Usui , Masato Nanjo , Kuniyoshi Akasaka ,
b
c
Takako Kudo , Sanshiro Komiya
a
Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
Department of Fundamental Studies, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
b
c
Department of Applied Chemistry, Faculty of Graduate school of Engineering, Tokyo University of Agriculture and Technology, 2-24-16,
Nakacho, Koganei, Tokyo 184-8588, Japan
Received 6 April 2006; received in revised form 8 May 2006; accepted 12 May 2006
Available online 3 September 2006
Abstract
The complex cis-Pt(Ph3Ge)2(PMe2Ph)2 underwent smooth isomerization to give the trans-isomer at room temperature via an associa-
tive five-coordinated intermediate. Thermodynamic parameters and activation energy for the cis to trans isomerization were obtained,
DH# = 105 kJ molꢀ1, DS# = 12.5 J molꢀ1 Kꢀ1, and Ea = 107 kJ molꢀ1, respectively. Heating of trans-Pt(Ph3Ge)2(PMe2Ph)2 at 50 ꢀC
for 36 days produced trans-PtPh(Ph3Ge)(PMe2Ph)2 followed by the formation of trans-PtPh2(PMe2Ph)2, Pt(PMe2Ph)4, and Ph4Ge finally
via elimination of the phenyl group from Ph3Ge ligand with liberation of the Ph2Ge unit and subsequent reductive elimination of the
remaining Ph3Ge ligand at 80 ꢀC for 1 month.
ꢁ 2006 Elsevier B.V. All rights reserved.
Keywords: Bis(triphenylgermyl)bis(phenyldimethylphosphine)platinum(II); cis–trans Isomerization; Phenyl migration; Diphenylgermylene; X-ray
diffraction
1. Introduction
structures, and reactivity of bis(silyl)- and bis(germyl)plat-
inum(II) complexes have been amply investigated, there
has been few reports regarding both cis and trans isomers
having the same chemical formula. Moreover, many
papers of these complexes are limited to the insertion
and reductive elimination processes that provide a car-
bon-group 14 element bond. To elucidate the role of
bis(germyl)platinum(II) complexes as key intermediates
in platinum-catalyzed processes [4], we examined the
thermolysis of both cis- and trans-Pt(Ph3Ge)2(PMe2Ph)2
that hitherto has not been observed. We describe herein
(1) cis–trans isomerization at platinum for cis-Pt(Ph3Ge)2-
(PMe2Ph)2, and (2) unexpected Ge–Ph bond cleavage and
formation via germylene intermediate for trans-
Pt(Ph3Ge)2(PMe2Ph)2.
Bis(silyl)- and bis(germyl)platinum(II) complexes are
important intermediates in Pt-catalyzed synthetic reac-
tions such as the bis-silylation and bis-germylation of
C–C triple and double bonds and the dehydrocoupling
of group 14 element compounds [1–4]. These complexes
also act as useful starting materials for group 14 ele-
ment-containing compounds. In order to develop new
metal catalysts for the synthesis of such compounds a
good understanding of the reactivity of metal–silyl and
metal–germyl bonds is needed. While the preparation,
*
Corresponding author.
E-mail address: kunio.mochida@gakushuin.ac.jp (K. Mochida).
0022-328X/$ - see front matter ꢁ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.05.065

396
K. Mochida et al. / Journal of Organometallic Chemistry 692 (2007) 395–401
2. Results and discussion
2.1. Thermal reactivity of cis-Pt(Ph3Ge)2(PMe2Ph)2
The complex cis-Pt(Ph3Ge)2(PMe2Ph)2 (cis-1), prepared
by photo-isomerization of trans-1 with a Xenon lamp
(k > 450 nm) at room temperature for 30 min [5], was sta-
ble in solid state, but the dissolution of cis-1 in CH2Cl2
or benzene caused a smooth isomerization to give a cis-1/
trans-1 equilibrium mixture.
PhMe2P
PhMe2P
GePh3
GePh3
Ph3Ge
PMe2Ph
GePh3
k
Pt
Pt
PhMe2P
k'
cis-1
trans-1
ð1Þ
The isomerization of cis-1 to trans-1 in CD2Cl2 at 30–
50 ꢀC was followed by monitoring the change in the two
methyl signals of the PMe2Ph ligands by means of 1H
NMR spectroscopy. Fig. 1 shows the decay of cis-1 and
the build up of trans-1 at 30–50 ꢀC. From the concentra-
tions of cis and trans isomers after equilibria were reached,
the following thermodynamic parameters were obtained:
Fig. 2. The kinetics of isomerization of cis-1.
The addition of free PMe2Ph (0.6 equiv. of PMe2Ph per
mol of cis-1) to the system caused acceleration of the isom-
erization of the cis isomer: 103 k/s = 1.12 (30 ꢀC). Thus, 80
times acceleration effect by addition of PhMe2Ph was
observed. These results suggest that the isomerization of
cis-1 proceeds through an associative pathway involving
a five-coordinate intermediate formed upon association of
cis-1 with PMe2Ph. The cis to trans isomerization observed
for the cis-1 dissolved in benzene along with an entropy
increase may be due to the effect of releasing the steric
repulsion between the bulky ligands in the cis form by
isomerization into the trans form.
Ab initio molecular orbital calculation using the HF/
LANL2DZ method supported the associative five-coordi-
nated mechanism with a Berry pseudo-rotation and located
the transition state for model compound Pt(GeH3)2(PH3)2
[7].
Although many reductive elimination processes of cis-
bis(silyl)- and cis-bis(germyl)platinum complexes have been
reported [3,4], there has been little study of cis–trans isom-
erization of these Pt-complexes [4a,4d]. Relative thermody-
namic stability between cis and trans isomers of Pt(ER3)2L2
(E = Si, Ge, and Sn) has been briefly described [8]. The
intramolecular twist-rotational motion between two ER3
groups was observed with cis-Pt(ER3)2L2 (E = Si, Sn) [9].
DH#, 105 kJ molꢀ1 and DS#, 12.5 J molꢀ1 Kꢀ1
.
The assumption of the equilibration reaction (Eq. (1))
following the first-order rate law leads to a kinetic expres-
sion, Eq. (2), where K represents to k/k0 [6]
K
K þ 1
½cis-1ꢂ ꢀ ½cis-1ꢂ0
½cis-1ꢂ ꢀ ½cis-1ꢂ0
kt ¼
ꢁ ln
K ¼ k=k0
ð2Þ
The isomerization of cis-1 exhibited first-order kinetics,
as shown in Fig. 2. From the plots shown in Fig. 2, the fol-
lowing isomerization rate constants were estimated by
using Eq. (2) at the early stage of the reaction. The follow-
ing first-order isomerization rate constants (k) at 30–50 ꢀC
in benzene-d6 were obtained from Fig. 2: 105 k/s = 1.94
(30 ꢀC), 9.67 (40 ꢀC), 20.3 (45 ꢀC), 35.2 (50 ꢀC). From the
Arrhenius plots, the energy of apparent activation (Ea) in
the isomerization of cis-1 to trans-1 was estimated to be
107 kJ molꢀ1
.
2.2. Thermal reactivity of trans-Pt(Ph3Ge)2(PMe2Ph)2
The complex trans-Pt(Ph3Ge)2(PMe2Ph)2 (trans-1), pre-
pared by treatment of cis-PtCl2(PMe2Ph)2 with two molar
amounts of Ph3GeLi [4d], was stable both in solid state and
in solution, and did not isomerize to the corresponding cis
isomer, even at 70 ꢀC for 1 h. However, heating of the
benzene-d6 solution of trans-1 at 50 ꢀC for 36 days slowly
but unexpectedly gave trans-PtPh(Ph3Ge)(PMe2Ph)2 in
ca. 40% yield together with unidentified oligomers contain-
ing probably the Ph2Ge unit. Half of the trans-1 at this
stage unreacted. The phenylplatinum complex trans-
Fig. 1. The progress with time of isomerization of cis-1 to trans-1 at 30–
50 ꢀC.

K. Mochida et al. / Journal of Organometallic Chemistry 692 (2007) 395–401
397
PtPh(Ph3Ge)(PMe2Ph)2 was identified by comparing the
spectroscopic data of the authentic Pt-complex. The pres-
ence of oligomers was confirmed by their characteristic
broad signals in the range 7–8 ppm due to the phenyl
groups based on NMR spectroscopy as well as by GPC
spectrum.
The trans-PtPh2(PMe2Ph)2 has a square-planar geome-
try, and the sum of four angles about platinum was 360ꢀ.
The C–Pt–C and C–Pt–P bond angles are 179.999(1)ꢀ
and
88.54(8)ꢀ,
respectively.
The
Pt–C(phenyl)
˚
˚
(2.088(3)A) and Pt–P bond lengths (2.2861(18) A) for
trans-PtPh2(PMe2Ph)2 are slightly longer than that for
˚
Furthermore, heating of this sample at 80 ꢀC for 1
month gave formation of trans-PtPh2(PMe2Ph)2 and
Ph4Ge in 40% yields together with germylene oligomers
(Scheme 1). These products (trans-PtPh2(PMe2Ph)2 and
Ph4Ge) were identified by comparison with their spectro-
scopic data reported previously [10]. The formation of
trans-PtPhMe(PMe2Ph)2 (2.058(4) and 2.2773(av) A,
respectively) [10]. These results correspond to greater
trans influence of the phenyl group than the methyl
group.
A mechanism for the present unexpected formation of
trans-PtPh2(PMe2Ph)2, Ph4Ge, and Pt(PhMe2P)4 together
with oligomers containing Ph2Ge units is proposed as
shown in Scheme 2 from these results and related experi-
ments [4d].
The stepwise formation of trans-PtPh(Ph3Ge)(P-
Me2Ph)2 and trans-PtPh2(PMe2Ph)2 by degrees suggests
the generation of complexes having a germylene-platinum
bond in the thermal reaction of trans-1. Thus, the ther-
molysis of trans-1 may proceed with liberation of one
of the two PMe2Ph ligands in solution to give a coord-
inatively unsaturated, three-coordinate bis(germyl)plati-
num intermediate. Following a-elimination of the
phenyl group attached to the germanium by platinum
may yield a phenylplatinum complex having a germyl-
ene–platinum bond. Reductive elimination of the phenyl
1
Pt(PhMe2P)4 was also confirmed by its H and 31P NMR
spectra [11]. The yield of Pt(PhMe2P)4 was roughly esti-
mated (ca. 30%). The structure of PtPh2(PMe2Ph)2 was
established by X-ray diffraction analysis and the molecular
structure of trans-PtPh2(PMe2Ph)2 is shown in Fig. 3.
Selected bond lengths and angles of the trans-
PtPh2(PMe2Ph)2 are tabulated in Table 1. The crystallo-
graphic data are summarized in Section 3.
Ph3Ge
PMe2Ph
GePh3
Ph3Ge
PMe2Ph
Ph
-:GePh2
50 oC, 36 d
-:GePh2
Pt
Pt
PhMe2P
PhMe2P
80 oC, 1 month
trans-1
Ph
PMe2Ph
Pt
+
Ph4Ge + Pt(PMe2Ph)4
PhMe2P
Ph
Ph3Ge
PMe2Ph
GePh3
Ph3Ge
PMe2Ph
GePh3
-PMe2Ph
Pt
Pt
Scheme 1.
PhMe2P
trans-1
1) H2O, 2)+PMe2Ph
PMe2Ph
GePh3
Ph2(OH)Ge
Ph
Ph2Ge
Ph
PMe2Ph
Pt
Pt
GePh3
trans
1) -:GePh2
2) +PMe2Ph
Ph
PMe2Ph
GePh3
-PMe2Ph
Ph
PMe2Ph
Pt
Pt
PhMe2P
GePh3
trans
Ph
PMe2Ph
GePh2
Pt
Ph4Ge
+
Pt(PMe2Ph)4
Ph
1) -:GePh2
2) +PMe2Ph
Ph
PhMe2P
PMe2Ph
Pt
Ph
trans
Fig. 3. Molecular structure of trans-PtPh2(PMe2Ph)2. Thermal ellipsoids
are drawn at the 30% probability level.
Scheme 2.
Table 1
˚
Selected bond length (A) and bond angles (ꢀ) of trans-PtPh2(PMe2Ph)2
Pt1–P1
P1–C9
2.2861(18)
1.822(4)
Pt1–C1
2.088(3)
P1–C7
1.820(4)
88.54(8)
P1–C8
1.835(9)
C1–Pt1–C10
179.999(1)
C1–Pt1–P1

398
K. Mochida et al. / Journal of Organometallic Chemistry 692 (2007) 395–401
group with the remaining Ph3Ge ligand produces Ph4Ge,
and the rest of the germylene unit may be converted into
oligomers.
The trans-Pt(Ph2GeOH)(Ph3Ge)(PMe2Ph)2 has a dis-
torted square-planar geometry, with the dihedral angles
between the planes composed of Pt1–Ge1–P1 and Pt1–
Ge2–P2 being 4.92ꢀ. The sum of four angles about plati-
num was 353.2ꢀ. The P1–Pt1–Ge1 and P2–Pt1–Ge2 bond
angles are 86.37(3)ꢀ and 90.06(3)ꢀ, respectively. The Pt–
In order to detect the germylene–platinum intermediate
complex, PtPh3Ge(Ph)(Ph2Ge@)(PMe2Ph), we heated very
carefully trans-1 in C6D6 at 50 ꢀC by observing the change
1
of signals in the PMe2Ph ligand by means of H and 31P
Ge bond lengths (2.4739(5) and 2.5049(5) A) for trans-
˚
NMR spectroscopy. After 2 days, the signals for a new spe-
cies appeared at 1.45 ppm (t, JH–P = 6.8 Hz, JH–Pt
Pt(Ph2GeOH)(Ph3Ge)(PMe2Ph)2 are shorter than those
for trans-1 (2.5207(3) and 2.5239(4) A) The Pt–P bond
lengths for trans-Pt(Ph2GeOH)(Ph3Ge)(PMe2Ph)2 are sim-
ilar to those for trans-1[4d].
The formation of trans-Pt(Ph2GeOH)(Ph3Ge)(P-
Me2Ph)2 may be initiated by nucleophilic attack of H2O
as an impurity to the electrophilic germylene ligand [12].
It is consistent with the results of MO calculations for
germylene complexes, which predict that the Ge@M dou-
ble bond of germylene complexes is polarized in the sense
of Ged+–Mdꢀ similarly to the silylene complexes [13,14].
2
3
˚
1
= 31 Hz) in 1H NMR and ꢀ9.5 ppm (s, JPt–P
=
2585 Hz) in 31P{1H} NMR, suggesting the formation of
new species with the trans geometry. Half of the complex
trans-1 remained unreacted. Fortunately, the new species
was isolated by quick elution using preparative silica-gel
TLC with a mixture of hexane and benzene. Two times
recrystallization from a mixture of hexane and toluene
gave colorless crystals with a composition of Pt(Ph2GeOH)-
(Ph3Ge)(PMe2Ph)2. The structure of trans-Pt(Ph2GeOH)-
(Ph3Ge)(PMe2Ph)2 was unequivocally established by
spectroscopic methods coupled with X-ray diffraction anal-
ysis. The molecular structure of the trans Pt-complex is
shown in Fig. 4. Selected bond lengths and angles in the
Pt-complex are tabulated in Table 2. The crystallographic
data are summarized in Section 3.
3. Experimental
3.1. General methods
All manipulations of air-sensitive compounds were per-
formed under N2 or argon using standard Schlenk tech-
niques. 1H, 13C, 31P NMR spectra were recorded on a
Varian Unity Inova-400 MHz. GC–MS spectra were mea-
sured with a JEOL JMS-DX 303 mass spectrometer. The
UV and UV–vis spectra were recorded on a Shimadzu
UV 2200 spectrometer. IR spectra were recorded on a Shi-
madzu FT IR 4200 spectrometer. Gas chromatographic
analyses were performed with Shimadzu GC-8A equipped
with 1 m 20% SE30. X-ray crystallographic data and dif-
fraction intensities were collected on a MacScience
DIP2030 diffractometer utilizing graphite-monochromated
˚
Mo Ka (k = 0.71073 A) radiation. The structures were
solved by direct methods using the program system SIR-92
and refined with all data on F2 by means of SHELXL-97. A
refinement was performed by a SILICON Graphics O2 with
MAXUS (see Table 3).
3.2. Materials
Solvents were dried by refluxing over sodium benzophe-
none ketyl under a nitrogen atmosphere and were distilled
just before use. cis-PtCl2(PMe2Ph)2 and Pt(PMe2Ph)4
are commercially available. Ph4Ge [15], Ph3GeLi [16],
trans-Pt(Ph3Ge)2(PMe2Ph)2 [4d] and trans-PtCl(Ph3Ge)-
(PMe2Ph)2 [3o] were prepared according to the reported
procedures.
Fig. 4. Molecular structure of trans-Pt(Ph2GeOH)(Ph3Ge)(PMe2Ph)2.
Thermal ellipsoids are drawn at the 30% probability level.
Table 2
Selected bond length (A) and bond angles (ꢀ) of trans-Pt(Ph2GeOH)(Ph3Ge)(PMe2Ph)2
˚
Pt1–P1
2.3017(12)
Pt1–P2
2.3080(12)
Pt1–Ge1
2.4739(5)
Pt1–Ge2
2.5049(5)
Ge1–O1
P1–Pt1–Ge1
1.837(3)
86.37(3)
Ge1–C1
P2–Pt1–Ge1
1.968(5)
91.67(3)
P1–Pt1–P2
P1–Pt1–Ge2
175.19(4)
92.07(3)
Ge1–Pt1–Ge2
P2–Pt1–Ge2
177.235(17)
90.06(3)

K. Mochida et al. / Journal of Organometallic Chemistry 692 (2007) 395–401
399
Table 3
Then, the organic layer was filtered through filter-paper.
Upon allowing the organic layer to stand at room temper-
ature for 1 day, pure trans-PtPh(Ph3Ge)(PMe2Ph)2 was
Crystallographic data for of trans-PtPh2(PMe2Ph)2 and trans-Pt(Ph2-
GeOH)(Ph3Ge)(PMe2Ph)
1
trans-PtPh2-
(PMe2Ph)2
trans-Pt(Ph2GeOH)(Ph3Ge)-
(PMe2Ph)2
formed as yellow crystals. H NMR (d, C6D6) 1.08 (t with
two satellites, JH–P = 6.8 Hz, JH–Pt = 32 Hz, 12H), 6.86–
1
7.83 (m, 25H); 31P NMR (d, CD2Cl2) ꢀ9.6 (s, JP–Pt
Formula
C28H32P2Pt
625.57
0.25 · 0.2 · 0.2
Monoclinic
P21/n
C49H52OP2Ge2Pt
1059.12
0.1 · 0.1 · 0.1
Monoclinic
P21/c
Molecular weight
Crystal size (mm)
Crystal system
Space group
= 2725 Hz). Anal. Calc. for C40H42GeP2Pt: C, 61.61%;
H, 5.43%. Found: C, 61.85%; H, 5.73%.
Unit cell dimensions
˚
3.5. Kinetic studies of isomerization of
cis-Pt(Ph3Ge)2(PMe2Ph)2 (cis-1)
a (A)
10.3230(5)
7.7120(4)
16.9110(5)
90.00
105.547(3)
90.00
1297.04(10)
2
0.7170
9.8650(3)
36.5590(9)
12.7300(2)
90.00
106.74
90.00
4396.50(19)
4
0.7170
293(2)
˚
b (A)
˚
c (A)
a (ꢀ)
b(ꢀ)
c(ꢀ)
The cis-Pt(Ph3Ge)2(PMe2Ph)2 (cis-1) (11.0 mg, 0.011
mmol) was dissolved in dry CD2Cl2 (0.75 cm3) in an
NMR tube. The tube was degassed in vacuum and filled
with argon. The sample was placed in an NMR sample
probe controlled at 30, 40, 45, and 50 ꢀC, and examined
by 1H NMR. The time course of the isomerization was fol-
lowed by monitoringe the relative peak integration of the
methyl signals of cis-1 and trans-1.
3
˚
V (A )
Z
˚
Radiation Mo Ka (A)
Temperature (K)
293(2)
1.602
2716
Dcalc (g cmꢀ3
)
1.600
10476
Number of unique
reflections
Goodness-of-fit
R1 (I > 2r(I))
wR2
1.026
0.0361
0.1180
0.960
0.0428
0.1308
3.6. Kinetic studies of isomerization of
cis-Pt(Ph3Ge)2(PMe2Ph)2 (cis-1) with
Dimethylphenylphosphine
A mixture of cis-1 (11.0 mg, 0.011 mmol), PMe2Ph
(0.9 mg, 0.007 mmol) and CD2Cl2 (0.75 cm3) was heated
under argon in a sealed NMR tube at 30 ꢀC, and examined
by 1H NMR. The time course of the isomerization was fol-
lowed by measuring the relative peak integration of the
methyl signal of cis-1 and trans-1.
3.3. Preparation of cis-Pt(Ph3Ge)2(PMe2Ph)2 (cis-1)
The trans-Pt(Ph3Ge)2(PMe2Ph)2 (trans-1) (21.0 mg,
0.021 mmol) was dissolved in dry CD2Cl2 (1.5 cm3) in an
NMR tube. The tube was degassed in vacuum and filled
with argon. The sample was irradiated with a 500-W
Xenon lamp (Sen Tokushu Kogan Co., Ltd.) using Y-45
color filter (HOYA, k > 450 nm) at room temperature for
30 min. NMR analysis of the reaction showed ca. 95% con-
version of trans-1. Concentration of the reaction mixture
followed by preparative column chromatography (silica-
gel, hexane–CH2Cl2) and recrystallization from a mixture
of hexane and CH2Cl2. The pure cis-1 could be isolated
3.7. Thermolysis of trans-Pt(Ph3Ge)2(PMe2Ph)2 (trans-1)
at 50 ꢀC for 36 Days
The trans-Pt(Ph3Ge)2(PMe2Ph)2 (trans-1) (3.0 mg,
0.003 mmol) was dissolved in dry C6D6 (0.70 cm3) contain-
ing toluene (1 ll, 0.01 mmol) in an NMR tube. The tube
was degassed in vacuum and filled with argon. The pro-
gress of the reaction was monitored at 50 ꢀC for 36 days
by means of NMR spectroscopy. The NMR signals
assigned to trans-1 decayed (ca. 50% conversion yield),
and a buildup of new NMR signals of trans-PtPh(Ph3Ge)-
(PMe2Ph)2 (ca. 40% yield). trans-PtPh(Ph3Ge)(PMe2Ph)2
1
as yellow crystals (8.4 mg, 0.008 mmol, 40.0% yield). H
2
3
NMR (d, CD2Cl2) 0.72 (d, JH–P = 8.4 Hz, JH–
Pt = 20.2 Hz, 12 H, PCH3), 2.20 (s, 18H, GeC6H4CH3),
6.87–7.53 (m, 34H, GeC6H4CH3, PC6H5); 13C NMR (d,
CD2Cl2) 15.7, 21.9, 126.2, 128.0, 128.1, 129.3, 130.2,
132.7, 135.4, 137.0, 148.2; 31P NMR (d, CD2Cl2) ꢀ12.7
1
(s, JP–Pt = 2032 Hz). Anal. Calc. for C52H52Ge2P2Pt: C,
1
was observed. H NMR (d, C6D6) 1.08 (t with two satel-
52.88%; H, 4.86%. Found: C, 52.92%; H, 4.90%.
2
3
lites, JH–P = 16.1 Hz, JH–Pt = 3.3 Hz, 6H), 6.96–7.78 (m,
30H); 31P NMR (d, C6D6) ꢀ9.6 (1JPt–P = 2725 Hz).
3.4. Preparation of trans-PtPh(Ph3Ge)(PMe2Ph)2
The trans-PtCl(Ph3Ge)(PMe2Ph)2 (0.1 g, 0.12 mmol),
Ph2Zn (0.026 g, 0.12 mmol), and THF (2 ml) were placed
in a 5-ml Pyrex test tube. The solution was degassed in a
vacuum and stirred under argon in a sealed tube at 0 ꢀC
for 1 h. After MeOH was slowly added, the organic layer
was extracted with CH2Cl2 several times. After the solution
was concentrated to ca. 5 ml, hexane (10 ml) was added.
3.8. Thermolysis of a mixture of trans-Pt(Ph3Ge)2-
(PMe2Ph)2 (trans-1) and trans-PtPh(Ph3Ge)(PMe2Ph)2
at 80 ꢀC for 1 month
After heating a C6D6 solution of trans-1 (5.0 mg,
0.005 mmol) at 50 ꢀC for 36 days, this reaction mixture
was continuously heated at 80 ꢀC for 1 month. Complex

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K. Mochida et al. / Journal of Organometallic Chemistry 692 (2007) 395–401
(h) M. Suginome, Y. Ito, J. Organomet. Chem. 685 (2003) 218;
(i) H. Yoshida, J. Ikadai, M. Shudo, J. Ohshita, A. Kunai, J. Am.
Chem. Soc. 125 (2003) 6638;
trans-PtPh2(PMe2Ph)2 was formed together with oligomers
containing Ph2Ge units. Pure trans-PtPh2(PMe2Ph)2 could
be isolated by recrystallization from a mixture of hexane
and benzene at room temperature.
(j) J. Terao, A. Oda, N. Kame, Org. Lett. 6 (2004) 3341.
[3] (a) J. Chatt, C. Eaborn, P.N. Kapoor, J. Chem. Soc. A 881 (1970);
(b) J. Chatt, C. Eaborn, S.D. Ibekwe, P.N. Kapoor, J. Chem. Soc. A
1343 (1970);
3.9. Formation of trans-Pt(Ph2GeOH)(Ph3Ge)(PMe2Ph)2
by heating of trans-Pt(Ph3Ge)2(PMe2Ph)2 (trans-1)
(c) C. Eaborn, T.N. Metham, A. Pidcock, J. Organomet. Chem. 131
(1977) 377;
(d) T. Kobayashi, T. Hayashi, H. Yamashita, M. Tanaka, Chem.
Lett. 1411 (1988);
(e) T. Kobayashi, T. Hayashi, H. Yamashita, M. Tanaka, Chem.
Lett. 467 (1989);
(f) H. Yamashita, T. Kobayashi, T. Hayashi, M. Tanaka, Chem.
Lett. 1447 (1990);
(g) M. Tanaka, Y. Uchimaru, H.-J. Lautenschlager, Organometallics
10 (1991) 16;
(h) S.L. Grundy, R.D. Holmes-Smith, S.R. Stobart, M.A. Williams,
Inorg. Chem. 30 (1991) 3333;
(i) H. Yamashita, M. Tanaka, M. Goto, Organometallics 11 (1992)
3227;
(j) R.H. Heyn, T.D. Tilley, J. Am. Chem. Soc. 114 (1992) 1917;
(k) M.J. Michalczyk, C.A. Recatto, J.C. Calabrese, M.J. Fink, J.
Am. Chem. Soc. 114 (1992) 7955;
(l) S. Sasaki, M. Ieki, J. Am. Chem. Soc. 115 (1993) 2373;
(m) T. Hikida, K. Onitsuka, K. Sonogashira, T. Hayashi, F. Ozawa,
Chem. Lett. 985 (1995);
The trans-Pt(Ph3Ge)2(PMe2Ph)2 (trans-1) (5.0 mg,
0.005 mmol) was dissolved in dry C6D6 (0.70 cm3) contain-
ing toluene (1 ll, 0.01 mmol) in an NMR tube. The tube
was degassed in vacuum and filled with argon. The pro-
gress of the reaction was monitored at 50 ꢀC by means of
1H and 31P NMR spectroscopy. The NMR signals at
2
3
1.24 ppm (vt with two satellites, JH–P = 29.3 Hz, JH–Pt
= 6.6 Hz) and ꢀ11.0 ppm (1JPt–P = 2616 Hz) assigned to
trans-1 decayed (ca. 50% conversion yield), and a buildup
of new NMR signals at 1.45 ppm (t with two satellites,
3
2JH–P = 6.8 Hz, JH–Pt = 31 Hz) and ꢀ9.5 ppm (1JPt–
P = 2585 Hz) (approximately 1:1) was observed. The reac-
tion mixture was eluted by separative silica gel TLC, trea-
ted with Et3N (1%), with a 1:1 mixture of hexane and
benzene. Recrystallization from a mixture of hexane and
toluene two times gave colorless crystals with a composi-
tion of trans-Pt(Ph2GeOH)(Ph3Ge)(PMe2Ph)2.
(n) F. Ozawa, T. Hikida, Organometallics 15 (1996) 4501;
(o) F. Ozawa, T. Hikida, K. Hasebe, T. Mori, Organometallics 17
(1998) 1018;
(p) F. Ozawa, J. Kamite, Organometallics 17 (1998) 5630;
(q) B. Gehrhus, P.B. Hitchcock, M.F. Lappert, H. Maciejewski,
Organometallics 17 (1998) 5599;
Acknowledgement
(r) Y. Kang, S.O. Kang, J. Ko, Organometallics 18 (1999) 1818;
(s) F. Ozawa, J. Organomet. Chem. 611 (2000) 332;
(t) D. Kalt, U. Schubert, Inorg. Chim. Acta 301 (2000) 211;
(u) M. Tanabe, K. Osakada, J. Am. Chem. Soc. 124 (2002) 4550;
(v) Y.-J. Kim, E.-H. Choi, S.W. Lee, Organometallics 22 (2003) 2316.
[4] (a) H. Yamashita, T-a. Kobayashi, M. Tanaka, J.A. Samuels, W.E.
Streib, Organometallics 11 (1992) 2330;
This work was supported by a Grant-in-Aid for Priority
Area Research on ‘‘Dynamic Complex’’ from the Ministry
of Education, Culture, Science, Sports, and Technology,
Japan.
Appendix A. Supplementary data
(b) H. Komoriya, M. Kako, Y. Nakadaira, K. Mochida, Organo-
metallics 15 (1996) 2014;
(c) H. Komoriya, M. Kako, Y. Nakadaira, K. Mochida, J. Organo-
met. Chem. 611 (2000) 420;
(d) K. Mochida, T. Wada, W. Hatanaka, M. Nanjo, A. Sikine, Y.
Ohashi, M. Sakamoto, A. Yamamoto, Bull. Chem. Soc. Jpn. 74
(2001) 123;
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.
jorganchem.2006.05.065.
References
(e) K. Mochida, K. Hirakue, K. Suzuki, Bull. Chem. Soc. Jpn. 76
(2003) 1023;
(f) K. Mochida, H. Karube, M. Nanjo, Y. Nakadaira, J. Organomet.
Chem. 690 (2005) 2967;
(g) K. Mochida, H. Karube, M. Nanjo, Y. Nakadaira, Organomet-
allics 24 (2005) 4734.
[1] (a) R.D. Miller, J. Michle, Chem. Rev. 89 (1989) 1359;
(b) I. Beletskaya, C. Moberg, Chem. Rev. 99 (1999) 3435;
(c) M. Suginome, Y. Ito, Chem. Rev. 100 (2000) 3221.
[2] (a) R. West, in: G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.),
Comprehensive Organometallic Chemistry, vol. 2, Pergamon Press,
New York, 1982, p. 376;
[5] Y. Usui, T. Fukushima, K. Hagiwara, M. Nanjo, K. Mochida, S.
Komiya, K. Akasaka, T. Kudo, in: Proceedings of the 52nd
Symposium on Organometallic Chemistry, Japan, Kyoto, 2005
(Abstract pp. 4–5);
Y. Usui, T. Fukushima, K. Hagiwara, M. Nanjo, K. Mochida, S.
Komiya, K. Akasaka, T. Kudo, in press. .
[6] P.W. Atkins, Physical Chemistry, sixth ed., Oxford University Press,
Oxford, p. 771.
[7] All structures were optimized at the HF/LANL2DZ+6-31G(d) level.
For the basis set, LANL2DZ was employed for Pt while the 6-31(d)
basis sets were used for other atoms. The details of the results for the
reaction mechanism will be published by T. Kudo. The program code
is GAUSSIAN 03: M.J. Frisch, G.W. Trucks, J.B. Schlegel, G.E.
Scuseria, J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B.
Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A. Petersson, H.
(b) R. West, in: G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.),
Comprehensive Organometallic Chemistry, vol. 2, Pergamon Press,
New York, 1995, p. 77;
(c) I. Ojima, in: S. Patai, Z. Rappoport (Eds.), The Chemistry of
Organic Silicon Compounds, John Wiley & Sons, New York, 1989;
(d) T.D. Tilley, in: S. Patai, E. Rappoport (Eds.), The Silicon–
heteroatom Bond, John Wiley & Sons, Chichester, 1991 (Chapter 9);
(e) S. Murai, N. Chatani, J. Synth. Org. Chem. Jpn. 51 (1993) 421,
and references cited therein;
(f) H. Yamashita, M. Tanaka, Bull. Chem. Soc. Jpn. 68 (1995) 403,
and references cited therein;
(g) M. Suginome, H. Oike, S.-S. Park, Y. Ito, Bull. Chem. Soc. Jpn.
69 (1996) 1996, and references cited therein;

K. Mochida et al. / Journal of Organometallic Chemistry 692 (2007) 395–401
[9] Y. Tsuji, Y. Obora, J. Organomet. Chem. 611 (2000) 343.
401
Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitano, H. Nakai, M. Klene,
X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, C. Adamo, J.
Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austrin,
R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayla, K. Morokuma,
G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S.
Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D.
Rabuck, K. Raghavachari, J.B. Foresman, J.V. Oritz, Q. Cui, A.G.
Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A.
Liashenko, P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T.
Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M. Challa-
combe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C.
Gonzalez, J.A. Pople, Gaussian Inc., Pittsburg, PA, 2003.
[10] P. Nilsson, F. Plamper, O.F. Wendt, Organometallics 22 (2003) 5235.
[11] H.C. Clark, K. Itoh, Inorg. Chem. 10 (1971) 1707.
[12] H. Wada, H. Tobita, H. Ogino, Organometallics 16 (1997) 2200.
[13] (a) Y. Kawano, H. Tobita, H. Ogino, Angew. Chem., Int. Ed. 30
(1991) 843;
(b) Y. Kawano, H. Tobita, M. Simoi, H. Ogino, J. Am. Chem. Soc.
116 (1994) 8575.
[14] (a) C. Zybill, G. Muller, Organometallics 7 (1988) 1368;
¨
(b) S.D. Grumbine, T.D. Tilley, F.P. Arnold, A.I. Rheingold, J. Am.
Chem. Soc. 116 (1994) 5495.
[15] D.M. Harris, W.H. Nebergall, O.H. Johnson, Inorg. Synth. 5 (1957)
70.
[8] Y. Kim, J. Park, S. Lee, K. Osakada, M. Tanabe, J. Choi, T.
Koizumi, T. Yamamoto, Organometallics 18 (1999) 1349.
[16] A. Kawauchi, Y. Tanaka, K. Tamao, Eur. J. Inorg. Chem. 461
(1999).