Synthesis and organic group transfer of organodiplatinum complex with a 1,2-bis(diphenylphosphino)ethane ligand

Article abstract of DOI:10.1139/V08-111

Abstract: A series of homometallic alkyl- and phenyldinuclear complexes containing one platinum-platinum bond, (dppe)RPt-Pt(η⁵-Cp)(CO) (R = Me, Et, CH₂CMe₃, Ph), have been prepared by oxidative addition of the Pt-C bond of

Full text of DOI:10.1139/V08-111

176
Synthesis and organic group transfer of
organodiplatinum complex with a 1,2-
bis(diphenylphosphino)ethane ligand1
Nobuyuki Komine, Tomoko Ishiwata, Jun-ya Kasahara, Erino Matsumoto,
Masafumi Hirano, and Sanshiro Komiya
Abstract: A series of homometallic alkyl- and phenyldinuclear complexes containing one platinum–platinum bond,
5
(dppe)RPt–Pt(η -Cp)(CO) (R = Me, Et, CH2CMe3, Ph), have been prepared by oxidative addition of the Pt–C bond of
5
PtR(η -Cp) to Pt(styrene)(dppe), and were characterized by spectroscopic methods and (or) X-ray structure analysis.
5
The geometry at Pt with a dppe ligand is square planar, and the carbonyl and Cp ligand of the Pt(η -Cp)(CO) moiety
lie orthogonal to the coordination plane of former platinum. Competitive organic group transfer reactions along the Pt–
5
1
Pt bond in these complexes took place to give PtR(η -Cp)(CO) and PtR(η -Cp)(dppe) on thermolysis. Alkyl or aryl
transfer from Pt with a dppe ligand were enhanced by addition of olefin, whereas treatment with CO and tertiary phos-
phine ligands causes Cp transfer from Pt(η -Cp)(CO).
5
Key words: organoplatinum–platinum complex, organic group transfer.
Résumé : On a préparé une série de complexes alkyl- et phényldinucléaires homométalliques contenant une liaison pla-
5
tine-platine, (dppe)RPt-Pt(η -Cp)(CO) (R = Me, Et, CH2CMe3, PH) par le biais d’une réaction d’addition oxydante de
5
la liaison Pt-C du PtR(η -Cp) sur du Pt(styrène)(dppe) et on les a caractérisés par des méthodes spectroscopiques ainsi
que par des analyses de structure par diffraction des rayons X. La géométrie au niveau du Pt portant un ligand dppe
5
est plan carré et le groupement carbonyle et le ligand Cp de la portion Pt(η -Cp)(CO) se trouve en position orthogonale
par rapport au plan de coordination du premier atome de platine. Il se produit des réactions compétitives de transfert
5
des groupes organiques le long de la liaison Pt-Pt de ces complexes et elles conduisent à la formation de PtR(η -
5
Cp)(CO) et PtR(η -Cp)(dppe) par thermolyse. Les transferts de groupes alkyles ou aryles à partir des dérivés de Pt por-
tant le ligand dppe sont rendus plus fréquents par l’addition d’oléfine alors que des traitements par du CO ou des li-
5
gands phosphines tertiaires provoquent des transfert de Cp du Pt(η -Cp)(CO).
Mots-clés : complexe organique de platine–platine, transfert de groupe organique.
[Traduit par la Rédaction] Komine et al. 182
Introduction
sis and some reactions of heterodinuclear organometallic
complexes containing group 10 metals, having both M–R
and M–M′ bonds, LnRM–M′L′m (M = Pt, Pd; M′ = Mo, W,
Co, Fe, Mn, Re; R = Me, Et, Ph, H, Ac, allyl; Ln = cod,
The cooperative effect in multimetallic catalysis is one of
the most intriguing and interesting unsolved problems at the
molecular level both in homo- and heterogeneous catalyses
(1). As the simplest model for active intermediates in vari-
ous transition metal catalyzed reactions promoted by
heterometallic catalysts, we previously reported the synthe-
5
dppe, bpy, phen, tmeda; L′ = η -Cp, CO) (2). They show
unique reactions such as organic group transfer between dif-
ferent metal centers (2a, 2c, 2d, 2e, 2h, 2k, 2q), significant
acceleration of β-hydrogen elimination (2f, 2i), enhanced CO
insertion reactions into the Pd–C bond (2g, 2l), and regio-
and stereoselective insertion reactions of thiiranes into the
Pt–Mn (or –Re) bond controlled by an ancillary alkyl ligand
(2j). On the other hand, organoplatinum- (or palladium-) co-
balt complexes show catalytic activities in carbonylation of
thietane (2m) and copolymerization of aziridine and CO (2p,
2s). Among these reactions, organic group transfer reactions
attract interest as a simple model for easy σ-organic group
movement on the heterometallic catalyst surface. The pro-
cess is found to be essentially reversible and is regarded as
reductive elimination of transition metal and organic groups
at the transition metal. In most of the complexes we have in-
vestigated, an organic group on the platinum metal moves to
other metals with small electronegativity. In this work, we
investigated the synthesis and reaction of homometallic
Received 3 April 2008. Accepted 20 May 2008. Published on
the NRC Research Press Web site at canjchem.nrc.ca on
9 September 2008.
This paper is dedicated to Professor Richard Puddephatt for
his great contributions in Organometallic Chemistry.
N. Komine, T. Ishiwata, J. Kasahara, E. Matsumoto,
M. Hirano, and S. Komiya.2 Department of Applied
Chemistry, Graduate School of Engineering, Tokyo University
of Agriculture and Technology, 2–24–16 Nakacho, Koganei,
Tokyo.
1This article is part of a Special Issue dedicated to Professor
R. Puddephatt.
2Corresponding author (e-mail: komiya@cc.tuat.ac.jp).
Can. J. Chem. 87: 176–182 (2009)
doi:10.1139/V08-111
© 2008 NRC Canada

Komine et al.
177
5
Fig. 1. Molecular structures of (dppe)MePt–Pt(η -Cp)(CO) (3a)
alkyl- and aryl-dinuclear complexes containing one
platinum–platinum bond (3). These complexes were synthe-
sized by oxidative addition of the Pt–C bond of PtR(η -
Cp)(CO) to a platinum(0) complex containing a 1,2-
bis(diphenylphosphino)ethane ligand (dppe). In these
dinuclear complexes, two competitive organic group trans-
fers took place simultaneously and the reaction selectivity
was controlled by additives such as olefins, carbon monox-
ide, and phosphine lignads.
5
and (dppe)(Me3CCH2)Pt–Pt(η -Cp)(CO) (3c). All hydrogen atoms
and solvent are omitted for clarity. Elipsoids represent 50% prob-
ability. Selected bond distances (Å) for 3a: Pt(1)–Pt(2)
5
2.6415(10), Pt(1)–P(1) 2.210(5), Pt(1)–P(2) 2.290(5), Pt(1)–C(1)
1.98(2), Pt(2)–C(33) 1.73(2), C(33)–O(1) 1.20(3). Selected bond
angles (°) for 3a: Pt(2)–Pt(1)–C(1) 86.8(6), P(1)–Pt(1)–P(2)
86.51(18), P(1)–Pt(1)–C(1) 91.3(7), Pt(2)–Pt(1)–P(2) 95.50(13),
Pt(2)–C(33)–O(1) 177(2). Selected bond distances (Å) for 3c:
Pt(1)–Pt(2) 2.6489(5), Pt(1)–P(1) 2.221(2), Pt(1)–P(2) 2.298(2),
Pt(1)–C(1) 2.136(9), Pt(2)–C(37) 1.777(10), C(37)–O(1)
1.151(12). Selected bond angles (°) for 3c: Pt(2)–Pt(1)–C(1)
91.6(2), P(1)–Pt(1)–P(2) 85.63(8), P(1)–Pt(1)–C(1) 88.9(2),
Pt(2)–Pt(1)–P(2) 93.77(6), Pt(2)–C(37)–O(1) 176.5(8).
Results and discussion
Synthesis and characterization of alkyl- (or phenyl-)
platinum–platinum complexes
2
Treatment of the zero-valent platinum complex, Pt(η -
5
CH2=CHPh)(dppe) (1) with carbonyl(η -cyclopenta-
5
dienyl)methylplatinum, PtMe(η -Cp)(CO) (2a) (4), prepared
1
by treatment of PtMe(η -Cp)(cod) with CO, smoothly gave
5
methyldiplatinum complex, (dppe)MePt–Pt(η -Cp)(CO)
(3a), in 62% yield in benzene at room temperature (eq. [1]).
Similar reactions with other organoplatinum complexes PtR(
5
η -Cp)(CO) (R = Et (2b), CH2CMe3 (2c), Ph (2d)) also gave
the corresponding organodiplatinum complexes, (dppe)RPt–
5
Pt(η -Cp)(CO) (R = Et (3b), CH2CMe3 (3c), Ph (3d)). These
1
complexes 3a–3d were characterized by H and 31P{1H}
NMR and IR spectroscopies and elemental analysis. Single
crystals of complexes 3a and 3c suitable for X-ray structure
analysis were obtained by recrystallization from Et2O or to-
luene–hexane. Figure 1 depicts an ORTEP drawing of 3a
and 3c showing the formation of both Pt–Pt and C–Pt bonds
by oxidative addition of the Pt–C bond to Pt(0). The Pt(1)–
Pt(2) bond distances for 3a and 3c are 2.6415(10) and
2.6489(5) Å, respectively. The Pt(1)–C(1) bond distances for
3c (2.136(9) Å) is slightly longer than for 3a (1.98(2) Å).
The geometry of the Pt metal coordinated by 1,2-
bis(diphenylphosphino)ethane is essentially square planar,
these data, the actual oxidation state of the Pt metal with
dppe and an organic group and of the Pt metal with CO and
Cp ligands were calculated to be close to two and zero, re-
spectively, though the formal oxidation state of each is one.
The 31P{1H} NMR spectrum of 3a shows two sets of reso-
nances centered at δ 43.0 and 51.1, both of which are ac-
companied by two 195Pt satellite peaks. No apparent P–P
coupling is observed. The P–Pt coupling constants for the
resonance at δ 43.0 (3377 and 950 Hz) are smaller than
those for the resonance at δ 51.1 (1733 and 125 Hz), sug-
gesting that the former signal is assigned to the P nucleus
trans to the methyl ligand and the latter trans to Pt, since the
trans influence of the methyl is larger than that of Pt metal
(2b, 2c, 2d). A large second coupling constant (950 Hz) for
the resonance at δ 51.1 is also consistent with the trans con-
figuration between this P and Pt nuclei. 31P{1H} NMR spec-
tra of complexes 3b–3d showed similar patterns. All
observations of two 195Pt satellites in 31P nuclei are consis-
tent with the dinuclear structure with a Pt–Pt bond.
5
where the Pt(η -Cp)(CO) moiety and the methyl or
neopentyl group are placed cis to each other. This square
planar geometry is consistent with the d8 configuration of
Pt(II). The carbonyl and Cp ligands in these complexes lie
orthogonal to the coordination plane of the Pt metal bearing
a
1,2-bis(diphenylphosphino)ethane ligand. The Pt(2)–
C(33)–O(1) [177(2)°] linkage in 3a and Pt(2)–C(37)–O(1)
[176.5(8)°] linkage in 3c are linear compared with the corre-
sponding linkages of heterodinuclear complexes, suggesting
that these carbonyl ligands have no bridging interaction with
Pt metal coordinated with dppe.
1
The H NMR spectrum of 3a in benzene-d6 shows a dou-
ble doublet with 195Pt satellite for the methyl group, owing
to couplings with two different P nuclei at room tempera-
ture. Cp protons in 3a appear as a singlet at δ 5.58. The
ortho protons of Ph in the dppe ligand are observed as two
separated sets of multiplets at δ 7.7 and 7.9, each with 4H
intensity. Inequivalency of the two phosphorus nuclei in
dppe of 3a is consistent with the structural result. The
phenyl analogue 3d also show similar results. On the other
hand, the ethyl complex 3b shows broad signals for the ethyl
and the ortho protons of phenyl in the dppe ligand at room
temperature. When the temperature is raised to 70 °C, clear
signals consisting of a double quartet (2H) and a double trip-
let (3H) with Pt satellites owing to the ethyl ligand and two
multiplets (4H each) for the ortho protons are observed. The
[1]
The IR spectra of 3a–3d show a strong ν(CO) band at ca.
1940 cm–1. The value is considerably lower than that for the
known Pt(II) complex PtMe(η -Cp)(CO) (2036 cm–1) (3a),
5
suggesting strong π back-donation from the Pt metal. From
© 2008 NRC Canada

178
Can. J. Chem. Vol. 87, 2009
Scheme 1. Rotation of platinum–platinum bond.
Scheme 2. Controlled organic group transfer along platinum–
platinum bond.
results indicate that these complexes involve some
fluxionality in solution without Pt–P bond rupture. When
these complexes in acetone-d6 are cooled to –40 °C, two
multiplets for the ortho protons further split to four
multiplets with 2H intensity, though unfortunately the ethyl
signals are not well resolved. The result suggests that four
aryl groups in dppe become magnetically inequivalent at
low temperature. Such a situation becomes more clear for
the 1H NMR of neopentyl derivative 3c: four separated
ortho protons are observed at room temperature. Further-
more, methylene signals owing to the neopentyl group ap-
pear as an AB quartet that further splits into double doublets
by coupling with two P nuclei with Pt satellites. Observation
of the diastereotopic methylene signals indicates that 3c is
stereochemically rigid as shown by X-ray structure analysis,
where CO and Cp ligands are fixed above and below the
square planar coordination plane of Pt metal with dppe
ligand. Therefore the observed fluxionality in 3a and 3b is
considered to be due to the rotation of the Pt–Pt bond with-
out any bond dissociation (Scheme 1). The qualitative ease
of the Pt–Pt bond rotation decreases in the order 3a≈3d > 3b
> 3c, reflecting the increase of steric bulkiness of the alkyl
ligands. The importance of steric bulk in the dinuclear sys-
tem is also previously reported in the structural study of
alkyl, acyl, and hydrido heterodinuclear complexes (2r).
To clarify the polarization of the platinum–platinum bond,
reactions of methyl and ethylplatinum–platinum complexes
with an electrophile were investigated (eq. [2]). The reaction
of methylplatinum–platinum complex 3a with methyl iodide
led to the migration of the Cp ligand to the other Pt atom
1
giving PtMe(η -Cp)(dppe) (5a) in 55% yield with a small
5
amount of PtMe(η -Cp)(CO) (2a) (Table 1, entry 1). The
1
progress of the thermolysis of 3a monitored by H NMR in-
dicated that 2a and 5a were formed simultaneously in the
same ratio. Thermolysis of ethyl complex 3b at 70 °C also
1
gave PtEt(η -Cp)(dppe) (30%) accompanied by the evolu-
tion of ethylene (59%) (entry 2). Only a trace of 2b was de-
tected. In contrast, heating of neopentyl derivative 3c in
C6D6 at 70 °C led to the migration of the neopentyl ligand to
5
the other Pt atom giving Pt(CH2CMe3)(η -Cp)(CO) (2c) (Ta-
ble 1, entry 3) preferentially. Phenyl derivative 3d was rela-
tively stable and when thermolysis of 3d was performed
1
under similar conditions, PtPh(η -Cp)(dppe) (5d) was
formed in lower yield and no 2d was detected (entry 4).
These results show that reductive elimination occurs at both
5
1
Pt metals giving PtR(η -Cp)(CO) and PtR(η -Cp)(dppe). 3c
favors the organic transfer from square planar Pt but Cp
ligand selectively moves to square planar Pt in the cases of
3a, 3b, and 3d. In other words, reductive elimination at
square planer Pt is preferred for the former, but that of Pt
and Cp at the Pt(CO) site for the latter. These results are in
sharp contrast with the previously reported thermal reductive
elimination of the alkyl or aryl and transition metal at Pt in
5
in acetone-d6 gave PtMe(η -Cp)(CO) (1a, 86%) and
5
PtMeI(dppe) (4a, 95%) but no PtI(η -Cp)(CO) or
PtMe2(dppe) (eq. [2]). A similar result was obtained for the
reaction of 3a with EtI and 3b with MeI. These results indi-
cate that Pt with dppe is essentially electrophilic and Pt with
CO is nucleophilic in both cases, being consistent with
Pt(II)–Pt(0) formalism, and also with IR and X-ray structural
data.
5
5
L2RPt–M(η -Cp)Ln giving only MR(η -Cp)Ln (2a, 2c, 2d,
2e), in which β-hydrogen elimination of ethylplatinum–
molybdenum (or –tungsten) complexes (2d, 2i) and no Cp
transfer were observed. Unfortunately, corresponding Pt(0)
products were not identified. The stronger electron-donating
property of the neopentyl ligand may accelerate the
reductive elimination (5). The origin of the present selectiv-
ity difference of organic group transfer is not clear at present
and further detailed kinetic and theoretical studies are re-
quired.
[2]
Organic group transfer assisted by olefins, carbon
monoxide, or phosphine ligands
When the organodiplatinum complexes 3a–3d were
treated with olefins, CO, and tertiary phosphine ligands, or-
ganic transfer reactions were enhanced. Results of the reac-
tions at room temperature are also summarized in Table 1.
Treatment of 3a with 5 equiv. of acrylonitrile in C6D6
gave 2a (35%) and 5a (19%) in 2 h, showing acceleration of
methyl transfer at the square planar platinum site (Table 1,
entry 5) (6). Reaction with methyl acrylate also produced a
similar result, though the rate was relatively slow (Table 1,
entry 6). Styrene showed no large effect on reductive elimi-
Controlled organic group transfer along the platinum–
platinum bond
Thermolysis of 3a–3d
Thermolysis of organodiplatinum complexes 3a–3d
(Scheme 2) was carried out and the results are summarized
in Table 1. Heating of methyl complex 3a in C6D6 at 70 °C
© 2008 NRC Canada

Komine et al.
179
Table 1. Organic group transfer of organoplatinum–platinum complex with a 1,2-
bis(diphenylphosphino)ethane ligand.
Yield (%)
Entry Complex Additive
Temp.
Time
Conv. (%)
2
5
83
92
74
53
65
7
1
3a
3b
3c
3d
3a
None
None
None
None
70 °C
70 °C
70 °C
70 °C
RT
25 h
25 h
6 h
24 h
2 h
55
2a
3
Trace 43
47
0
Trace
18
19
4
5
CH2=CHCN (5 eq)
35
6
3a
3a
3b
3c
3d
CH2=CH(CO2Me) (5 eq)
CH2=CHPh (5 eq)
CH2=CHCN (5 eq)
CH2=CHCN (5 eq)
CH2=CHCN (5 eq)
RT
RT
RT
RT
RT
24 h
24 h
22 h
24 h
1.5 h
50
16
55
24
56
21
2
19
10
13
4
7
8
37
15
56
9
10
1
11
12
13
14
15
3a
3c
3d
3a
3a
CO (1 atm)
CO (1 atm)
CO (1 atm)
dppe (5 eq)
PPh3 (10 eq)
RT
RT
RT
RT
RT
Instant
4 h
2 h
Instant
Instant
100
76
97
0
13
20
25
0
59
41
67
52
94
2
0
Note: Reactions were performed in C6D6.
aEvolution of ethylene (59%).
Scheme 3. A possible mechanism for controlled organic group transfer along platinum–platinum bond.
nation (Table 1, entry 7). A similar trend was also observed
in the reactions of 3b and 3d (Table 1, entries 8 and 10). No
significant effect was observed for the neopentyl derivative
3c (Table 1, entry 9). These results can be reasonably under-
stood by the coordination of these substituted olefins to the
square planar platinum atom enhancing the reductive elimi-
(Table 1, entries 11–13). When 3a was treated with a
tertiary phosphine ligand such as 1,2-bis(diphenyl-
phosphino)ethane (dppe) or PPh3 in C6D6 at room tempera-
ture, selective Cp group transfer took place to give only
PtMe(η -Cp)(dppe) (5a) in high yield (Table 1, entries 14,
15).
1
5
nation of PtR(η -Cp)(CO) complexes, similar to the organic
transfer of heterodinuclear organoplatinum complexes as-
sisted by electron deficient olefins, which was previously re-
ported by us (2a, 2c, 2d, 2e). Coordination of electron-
deficient olefins to the square planar platinum complexes
enhances the reductive elimination. Therefore the relatively
electron-rich styrene showed no significant effect. The low
acceleration by added acrylonitrile to the neopentyl complex
3c could be due to the fact that the sterically bulky
neopentyl ligand discourages coordination. The importance
of steric bulkiness of the neopentyl ligand is also discussed
in the NMR study (vide supra).
Possible mechanism for controlled organic group transfer
along platinum–platinum bond
As shown in Scheme 3, competitive organic group transfer
reactions along the Pt–Pt bond in organodiplatinum com-
5
5
plexes (dppe)RPt–Pt(η -Cp)(CO) take place to give PtR(η -
1
Cp)(CO) and PtR(η -Cp)(dppe) on thermolysis. The reaction
was enhanced by the coordination of additives such as ole-
fin, CO, and tertiary phosphine ligands. The selectivity of
the reaction is affected by the coordination site of the added
substrate. Specifically, the organic group transfer at square
planar platinum is favored by interaction with electron-
5
In contrast, reaction of a C6D6 solution of 3a, 3c, 3d with
deficient olefin, whereas Cp group transfer from Pt(η -
1
CO (1 atm) at room temperature afforded PtR(η -Cp)(dppe)
Cp)(CO) to PtR(dppe) is enhanced by tertiary phosphine lig-
ands or carbon monoxide. Probably, these ligands favor the
(R = Me (5a), CH2CMe3 (5c), Ph (5d)) as the major product
© 2008 NRC Canada

180
Can. J. Chem. Vol. 87, 2009
5
2
coordination at the Pt(η -Cp)(CO) site to enhance the Cp mi-
gration, while preferred coordination of π-accepting ligands
such as acrylonitrile to the Pt metal with an electron-
3JPH = 7.4, 5.1 Hz, JPtH = 64.9 Hz, 3H, PtCH3), 5.58 (m,
5H, Cp), 6.8–7.3 (m, 12H, m,p-Ph), 7.66 (m, 4H, o-Ph),
1
7.80 (m, 4H, o-Ph). H NMR (acetone-d6, RT, 300.4 MHz)
5
3
2
donating dppe ligand gives PtR(η -Cp)(CO). The accelera-
δ: 1.01 (dd, JPH = 7.6, 4.9 Hz, JPtH = 66.4 Hz, 3H, PtCH3),
2.15–2.42 (m, 4H, dppe CH2), 5.25 (m, 5H, Cp), 7.40–7.65
(m, 12H, m,p-Ph), 7.70–7.95 (m, 8H, o-Ph). 31P{1H} NMR
tion effect of added olefin on the alkyl transfer reaction is
well established in the reductive elimination of square planar
diorganonickel (or palladium) complexes (7) and hetero-
dinuclear organometallic complexes containing platinum
(2a, 2c, 2d). The observed selective reaction caused by lig-
ands could be due to the thermodynamic stability of prod-
ucts. For example, reductive elimination at the (dppe)Pt site
favors Pt(0) product such as Pt(olefin)(dppe) rather than a
putative complex Pt(olefin)(CO)n with ligands with all
strong π-back-donation. Further detailed study including a
theoretical approach is required to clarify the origin of this
selectivity.
1
2
(C6D6, RT, 121.6 MHz) δ: 41.7 (s, JPtP = 3289 Hz, JPtP
=
1010 Hz), 51.7 (s, JPtP = 1702 Hz, JPtP = 132 Hz). 31P{1H}
1
2
1
NMR (acetone-d6, RT, 121.6 MHz) δ: 43.0 (s, JPtP = 3377
Hz, JPtP = 950 Hz), 51.1 (s, JPtP = 1733 Hz, JPtP
125 Hz). Anal. calcd. for C39H38OP2Pt2: C 48.05, H 3.93;
found: C 47.69, H 3.99.
2
1
2
=
(dppe)EtPt–Pt(␩5-Cp)(CO) (3b)
140.3 mg (0.1372 mmol, 73%). IR (KBr, cm–1) ν(CO):
1
1934. H NMR (C6D6, 70 °C, 300.4 MHz) δ: 1.55–2.00 (m,
3
2
4H, dppe CH2), 1.56 (dt, JPtH = 45.6 Hz, JHP = 10.8 Hz,
3JHH = 7.8 Hz, 3H, PtCH2CH3), 2.62 (dq, JPtH = 71.5 Hz,
2
Experimental
2JPH = 14.7 Hz, JHH = 7.2 Hz, 2H, PtCH2CH3), 5.61 (m,
2
General
5H, Cp), 7.02–7.23 (m, 12H, m,p-Ph), 7.60–7.87 (m, 8H, o-
Ph). 31P{1H} NMR (C6D6, 70 °C, 121.6 MHz) δ: 42.0 (s,
All manipulations were carried out under dry nitrogen or
argon atmosphere using standard Schlenk and vacuum line
techniques. Solvents (benzene, toluene, hexane, and THF)
were refluxed over and distilled from sodium benzophenone
ketyl under N2. Deuterated solvents were degassed by three
freeze-pump-thaw cycles and then vacuum-transferred from
appropriate drying agents (C6D6 from sodium wire, acetone-
2
3
1JPtP = 3453 Hz, JPtP = 977 Hz, JPP = 3.6 Hz), 49.3 (s,
1JPtP = 1480 Hz, JPtP = 141 Hz, JPP = 3.6 Hz). Anal. calcd.
2
3
for C41H42OP2Pt2: C 48.72, H 3.79; found: C 49.10, H 4.22.
(dppe)(Me3CCH2)Pt–Pt(␩5-Cp)(CO) (3c)
106.5 mg (0.1119 mmol, 64%). IR (KBr, cm–1) ν(CO):
2
1
d6 from drierite). The zero-valent platinum complex, Pt(η -
1941. H NMR (C6D6, RT, 300.4 MHz) δ: 1.28 (s, 9H,
2
CH2=CHPh)(dppe) was prepared by the reaction of
PtI2(dppe) with NaBH4 in the presence of a large excess of
the styrene according to the analogous literature method
CH2CMe3), 1.4–1.9 (m, 4H, dppe CH2), 2.75 (td, JHH
=
3JPH = 11.7 Hz, JPH = 8.4 Hz, JPtH = 52.3 Hz, 1H,
3
2
2
3
CH2CMe3), 2.92 (ddd, JHH = 11.7 Hz, JPH = 7.8, 3.3 Hz,
2JPtH = 72.7 Hz, 1H, CH2CMe3), 5.56 (m, 5H, Cp), 7.0–7.2
(m, 12H, m, p-Ph), 7.53 (m, 2H, o-Ph), 7.63 (m, 2H, o-Ph),
7.70 (m, 2H, o-Ph), 7.79 (m, 2H, o-Ph). 31P{1H} NMR
1
(2k). PtR(η -Cp)(cod) were prepared by the reaction of
PtRCl(cod) and NaCp according to the analogous literature
1
methods with modifications (3). PtR(η -Cp)(dppe) (R = Me
1
2
(5a), Et (5b), CH2CMe3 (5d), Ph (5e)) were prepared for as-
signment, according to the analogous literature methods (8).
NMR spectra were recorded on a JEOL LA-300 spectrome-
(C6D6, RT, 121.6 MHz) δ: 40.7 (d, JPtP = 3408 Hz, JPtP
=
=
2
1
2
1860 Hz, JPP = 3.6 Hz), 50.8 (d, JPtP = 1508 Hz, JPtP
2
175 Hz, JPP = 3.6 Hz).
ter (300.4 MHz for H, 121.6 MHz for 31P). Chemical shifts
1
1
(dppe)PhPt–Pt(␩5-Cp)(CO) (3d)
were reported in ppm downfield from TMS for H and from
85% H3PO4 in D2O for 31P. IR spectra were recorded on a
JASCO FT–IR-410 spectrometer using KBr disks. Elemental
analyses were carried out with a Perkin-Elmer 2400 series II
CHN analyzer.
49.9 g (0.052 mmol, 31%). IR (KBr, cm–1) ν(CO): 1947.
1H NMR (C6D6, RT, 300.4 MHz) δ: 1.6–1.8 (m, 4H, dppe
CH2), 5.42 (m, 5H, Cp), 6.9–7.3 (m, 15H, m,p-Ph, dppe m,
3
3
p-Ph), 7.47 (m, 4H, dppe o-Ph), 7.68 (t, JHH = JPH = 7.1
3
1
Hz, JPtH= 45.7 Hz, 2H, o-Ph), 7.96 (m, 4H, dppe o-Ph). H
NMR (acetone-d6, RT, 300.4 MHz) δ: 2.15–2.42 (m, 4H,
dppe CH2), 5.61 (m, 5H, Cp), 6.45 (t, JHH = 7.4 Hz, 1H, p-
Synthesis of organoplatinum–platinum complexes
As a typical procedure, the oxidative addition of
3
5
3
methyl(η -cyclopentadienyl)(monocarbonyl)platinum com-
Ph), 6.67 (td, JH3H = 7.4, 1.7 Hz, 2H, m-Ph), 7.11 (td, JHH
=
2
3JPH = 7.4 Hz, JHH = 1.7 Hz, JPtH= 45.4 Hz, 2H, o-Ph),
7.54–7.62 (m, 16H, dppe o,m,p-Ph), 7.90–8.05 (m, 4H, dppe
o-Ph). 31P{1H} NMR (C6D6, RT, 121.6 MHz) δ: 37.4 (s,
3
plex (2a) to the zero-valent platinum complex, Pt(η -
5
CH2=CHPh)(dppe) (1) to afford (dppe)MePt–Pt(η -Cp)(CO)
5
(3a) is described. PtMe(η -Cp)(CO) was first prepared by
1
1JPtP = 3185 Hz, JPtP = 995 Hz), 48.2 (s, JPtP = 1645 Hz,
2
1
treating PtMe(η -Cp)(cod) (69.9 mg, 0.169 mmol) with CO
2JPtP = 127 Hz). 31P{1H} NMR (acetone-d6, RT, 121.6 MHz)
and dissolving it in benzene (3 mL). This was then added to
2
1
2
1
a
solution of Pt(η -CH2=CHPh)(dppe) (105.2 mg,
δ: 43.0 (s, JPtP = 3272 Hz, JPtP = 960 Hz), 47.6 (s, JPtP
=
2
0.1507 mmol) in benzene (10 mL). The reaction mixture
was stirred at room temperature for 1 h. After the solution
was concentrated under reduced pressure, excess hexane was
added to give a yellow powder. The product was filtered,
washed with hexane, and dried under vacuum at room tem-
perature. Recrystallization from ether gave yellow crystals
1655 Hz, JPtP = 127 Hz).
Reactions with alkyl halide
A typical procedure for 3a with methyl iodide in acetone-
d6 is given. Acetone-d6 (0.5 mL) was vacuum-transferred to
an NMR tube (5 mmφ × 180 mm) containing 3a (5.3 mg,
5.9 × 10–3 mmol), and 1,4-dioxane was added as an internal
standard to the solution. Then 1 equivalent of methyl iodide
(yield: 62%). IR (KBr, cm–1) ν(CO): 1933. H NMR (C6D6,
1
RT, 300.4 MHz) δ: 1.6–1.8 (m, 4H, dppe CH2), 1.80 (dd,
© 2008 NRC Canada

Komine et al.
181
was introduced into the NMR tube. NMR spectra were peri-
odically measured to follow the reactions. Results are sum-
marized in Table 1.
Crystallographic data: 3aqEt2O: C37H42O2P2Pt2, FW: 970.83,
triclinic. P1 (No. 2) a: 11.952(7) Å, b: 18.217(16) Å, c:
8.955(2) Å, α: 101.24(5)°, β: 99.72(3)°, γ: 71.37(7)°. V:
1800.1(19) Å3. Z: 2. Dcalcd: 1.791 g cm–3. 5356 unique re-
flections with I > 3σ(I). R1: 0.080, wR2: 0.099.
Thermolysis
A typical procedure for 3a in C6D6 is given. C6D6
(0.5 mL) was vacuum-transferred to an NMR tube contain-
ing 3a, and 1,4-dioxane was added as an internal standard to
the solution. Then the NMR tube was heated on oil bath.
NMR spectra were periodically measured to follow the reac-
tions. Results are summarized in Table 1.
(dppe)(Me3CCH2)Pt–Pt(␩5-Cp)(CO) (3c)
For complex 3c, all non-hydrogen atoms were refined with
anisotropic displacement parameters except for one of the
phenyl rings of dppe and the incorporated solvent molecule.
The solvent molecule was refined with isotropic displace-
ment parameters, and one phenyl ring of dppe was treated as
a fixed group. Crystallographic data: 3cq2C6H6: C49H52OP2Pt2,
FW: 1109.08, monoclinic. P21/n (No. 14) a: 11.61(7) Å, b:
20.43(9) Å, c: 18.67(6) Å, β = 91.8(3)°. V: 4425.1(346) Å3.
Z: 4, Dcalcd: = 1.665 gqcm–3. 7679 unique reflections with I >
3σ(I). R1: 0.0462, wR2: 0.0622.
Reactions with olefin or phosphine ligand
A typical procedure for 3a in C6D6 is given. C6D6
(0.5 mL) was vacuum-transferred to an NMR tube contain-
ing 3a, and 1,4-dioxane was added as an internal standard to
the solution. Then olefin or phosphine ligand was introduced
into the NMR tube. NMR spectra were periodically mea-
sured to follow the reactions. Results are summarized in Ta-
ble 1.
Acknowledgement
This work was financially supported by a Grant-in-Aid for
Scientific Research from the Ministry of Education, Sports,
Culture, Science, and Technology, Japan.
Reactions with CO
A typical procedure for 3a is given. C6D6 (0.5 mL) was
vacuum-transferred to an NMR tube containing 3a, and 1,4-
dioxane was added as an internal standard to the solution.
The solution was degassed by freeze-pump-thaw cycles and
CO (0.1 MPa) was introduced. NMR spectra were periodi-
cally measured to follow the reaction. Results are summa-
rized in Table 1.
References
1. (a) Metal clusters in chemistry. P. Edited by Braunstein, L.A.
Oro, and P.R. Raithby. Wiley-VCH, Weinheim, Germany.
1999; (b) Catalysis by di- and polynuclear metal cluster com-
plexes. Edited by R.D. Adams and F.A. Cotton. Wiley-VCH,
New York. 1998; (c) M.J. Chetcuti. In Comprehensive
organometallic chemistry II. Vol. 10. Edited by R.D. Adams.
Pergamon Press, Oxford, UK. 1995; (d) The chemistry of
metal cluster complexes. Edited by D.F. Shriver, H. Kaesz, and
R.D. Adams. VCH, New York. 1990.
2. (a) S. Komiya and I. Endo. Chem. Lett. 1709 (1988); (b) K.
Miki, N. Kasai, I. Endo, and S. Komiya. Bull. Chem. Soc. Jpn.
62, 4033 (1989); (c) A. Fukuoka, T. Sadashima, I. Endo, N.
Ohashi, Y. Kambara, T. Sugiura, and S. Komiya.
Organometallics, 13, 4033 (1994); (d) A. Fukuoka, T.
Sadashima, T. Sugiura, X. Wu, Y. Mizuho, and S. Komiya. J.
Organomet. Chem. 473, 139 (1994); (e) S. Komiya, I. Endo,
A. Fukuoka, and M. Hirano. Trends Organomet. Chem. 1, 223
(1994); ( f ) A. Fukuoka, T. Sugiura, T. Yasuda, T. Taguchi, M.
Hirano, and S. Komiya. Chem. Lett. 329 (1997); (g) A.
Fukuoka, S. Fukagawa, M. Hirano, and S. Komiya. Chem.
Lett. 377 (1997); (h) T. Yasuda, A. Fukuoka, M. Hirano, and
S. Komiya. Chem. Lett. 29 (1998); (i) S. Komiya, T. Yasuda,
A. Fukuoka, and M. Hirano. J. Mol. Cat. A 159, 63 (2000);
( j ) S. Komiya, S. Muroi, M. Furuya, and M. Hirano. J. Am.
Chem. Soc. 122, 170 (2000); (k) N. Komine, H. Hoh, M.
Hirano, and S. Komiya. Organometallics, 19, 5251 (2000);
(l) A. Fukuoka, S. Fukagawa, M. Hirano, N. Koga, and
S. Komiya. Organometallics, 20, 2065 (2001); (m) M. Furuya,
S. Tsutsuminai, H. Nagasawa, N. Komine, M. Hirano, and
S. Komiya. Chem. Commun. (Cambridge), 2046 (2003); (n) S.
Tsutsuminai, N. Komine, M. Hirano, and S. Komiya.
X-ray structure data3
The crystallographic data were measured on a Rigaku
RASA-7R four-circle diffractometer using Mo Kα (λ =
0.710 69 Å) radiation with a graphite crystal monochromator
at –73 °C. A single crystal was selected by means of a polar-
ized microscope and mounted in a capillary tube (GLASS,
0.7 mmφ), which was sealed by small flame torch, or onto a
glass capillary with Paraton N oil. The unit cell dimensions
were obtained by a least-squares fit of 20 centered reflec-
tions. Intensity data were collected using the ω-2θ technique
to a maximum 2θ of 55.0°. The scan rates were
16.0 deg/min. Three standard reflections were monitored in
every 150 reflections. Intensities were corrected for Lorentz
and polarization effects. The data were processed using the
Crystal Structure (9, 10) crystallographic software package.
The structure of 3a and 3c was solved by Patterson methods
(DIRDIF99 PATTY). An absorption correction for 3c was
applied with the program PSI SCAN method. All non-
hydrogen atoms were found on difference maps.
(dppe)MePt–Pt(␩5-Cp)(CO) (3a)
For complex 3a, all non-hydrogen atoms were refined
with anisotropic displacement parameters except for one of
the phenyl rings of dppe, Cp ring atoms, and the incorpo-
rated solvent molecule, which were treated as a fixed group.
3 Supplementary data for this article are available on the journal Web site (canjchem.nrc.ca) or may be purchased from the Depository of
Unpublished Data, Document Delivery, CISTI, National Research Council Canada, Ottawa, ON K1A 0R6, Canada. DUD 3798. For more
information on obtaining material refer to cisti-icist.nrc-cnrc.gc.ca/cms/unpub_e.shtml. CCDC 683196 and 683197 contain the crystallo-
graphic data for this manuscript. These data can be obtained, free of charge, via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax +44 1223 336033; or deposit@ccdc.cam.ac.uk).
© 2008 NRC Canada

182
Can. J. Chem. Vol. 87, 2009
Organometallics, 22, 4238 (2003); (o) S. Tsutsuminai, N.
Komine, M. Hirano, and S. Komiya. Organometallics, 23, 44
(2004); (p) N. Komine, S. Tanaka, S. Tsutsuminai, Y.
Akahane, M. Hirano, and S. Komiya. Chem. Lett. 2004, 33,
858; (q) A. Kuramoto, K. Nakanishi, T. Kawabata, N.
Komine, M. Hirano, and S. Komiya. Organometallics, 25, 311
(2006); (r) N. Komine, S. Tsutsuminai, H. Hoh, T. Yasuda, M.
Hirano, and S. Komiya. Inorg. Chem. Acta 359, 3699 (2006);
(s) S. Tanaka, H. Hoh, Y. Akahane, S. Tsutsuminai, N.
Komine, M. Hirano, and S. Komiya. J. Organomet. Chem.
692, 26 (2007); (t) N. Komine, S. Tsutsuminai, M. Hirano, and
S. Komiya. J. Organomet. Chem. 692, 4486 (2007); (u) N.
Komine, T. Hirota, M. Hirano, and S. Komiya.
Organometallics, 27, 2145 (2008).
4. (a) H.C. Clark and A. Shaver. Can. J. Chem. 54, 2068 (1976);
(b) G.A. Anderson, Organometallics, 5, 1903 (1986).
5. (a) K. Tatsumi, R. Hoffmann, A. Yamamoto, and J.K. Stille.
Bull. Chem. Soc. Jpn. 54, 1857 (1981); (b) J.J. Low and W.A.
Goddard III. J. Am. Chem. Soc. 108, 6115 (1986); (c) J.J. Low
and W.A. Goddard III. Organometallics, 5, 609 (1986).
6. Acetonitrile (5 equiv.) showed no effect on reductive elimina-
tion; therefore the reaction was enhanced by coordination of
the C=C bond of acrylonitrile.
7. (a) T. Yamamoto, A. Yamamoto, and S. Ikeda. J. Am. Chem.
Soc. 93, 3350 (1971); (b) T. Yamamoto, A. Yamamoto, and S.
Ikeda. J. Am. Chem. Soc. 93, 3360 (1971); (c) J. Lau and R.
Sustmann. Tetrahedron Lett. 26, 4907 (1985); (d) R. Sustmann
and J. Lau. Chem. Ber. 119, 2531 (1986).
3. (a) J. Fornies, F. Martinez, R. Navarro, M.C. Frias, and R.
Usón. Inorg. Chimica Acta, 132, 217 (1987); (b) H. Jun and
R.J. Angelici. Organometallics, 13, 2454 (1994); (c) E.
Alonso, J. Casas, F.A. Cotton, X. Feng, J. Forniés, C. Fortuño,
and M. Tomas. Inorg. Chem. 38, 5034 (1999); (d) S.
Cristofani, P. Leoni, M. Pasquali, F. Eisentraeger, and A.
Albinati. Organometallics, 19, 4589 (2000); (e) J. Forniés, P.
Espinet, C. Fortuño, M. Tomas, and R. Usón. J. Chem. Soc.
Dalton Trans. 1583 (1989).
8. (a) T.G. Appleton and M.A. Bennett. Inorg. Chem. 17, 738
(1978); (b) G. K. Anderson. Organometallics, 5, 1903 (1986).
9. CrystalStructure [computer program]. Version 3.8.0.
Rigakuand Rigaku/MSC, The Woodlands, Tex., USA. 2000–
2007.
10. J.R. Carruthers, J.S. Rollett, P.W. Betteridge, D. Kinna, L.
Pearce, A. Larsen, and E. Gabe. CRYSTALS, Issue 11 [com-
puter program]. Chemical Crystallography Laboratory, Oxford,
UK. 1999.
© 2008 NRC Canada