Reactions of acetylene-bridged diplatinum complexes with tetracyanoethylene

Article abstract of DOI:10.1016/S0022-328X(98)01119-X

The treatment of the μ-ethynediyldiplatinum complex (1a) possessing trimethylphosphine with tetracyanoethylene (TCNE) in refluxing benzene results in the formation of s-cis-μ-butadiene-2,3-diyldiplatinum complex (2a), while the similar reaction of a triethylphosphine analog (1b) leads to the isolation of s-trans-μ-butadiene-2,3-diyldiplatinum complex (3b), which comes to slow equilibrium with s-cis complex 2b in solution. The μ-butadiynediyl-diplatinum (7) and -dipalladium complexes (9) react with TCNE at room temperature (r.t.) to give complexes 8 and 10, respectively. The p-diethynylbenzene-bridged diplatinum complex (11) and the mononuclear platinum-acetylide (13) also react with TCNE at r.t. to give complexes (12) and (14), respectively. The molecular structures of complexes 2a, 3b, 8a and 14 have been determined by X-ray crystallography.

Full text of DOI:10.1016/S0022-328X(98)01119-X

Journal of Organometallic Chemistry 578 (1999) 169–177
Reactions of acetylene-bridged diplatinum complexes with
tetracyanoethylene
Kiyotaka Onitsuka a, Nobuo Ose b, Fumiyuki Ozawa b,1, Shigetoshi Takahashi a,*
a The Institute of Scientific and Industrial Research, Osaka Uni6ersity, Ibaraki, Osaka 567-0047, Japan
b Department of Applied Chemistry, Faculty of Engineering, Osaka City Uni6ersity, Sumiyoshi-ku, Osaka 558-0022, Japan
Received 22 August 1998
Abstract
The treatment of the m-ethynediyldiplatinum complex (1a) possessing trimethylphosphine with tetracyanoethylene (TCNE) in
refluxing benzene results in the formation of s-cis-m-butadiene-2,3-diyldiplatinum complex (2a), while the similar reaction of a
triethylphosphine analog (1b) leads to the isolation of s-trans-m-butadiene-2,3-diyldiplatinum complex (3b), which comes to slow
equilibrium with s-cis complex 2b in solution. The m-butadiynediyl-diplatinum (7) and -dipalladium complexes (9) react with
TCNE at room temperature (r.t.) to give complexes 8 and 10, respectively. The p-diethynylbenzene-bridged diplatinum complex
(11) and the mononuclear platinum-acetylide (13) also react with TCNE at r.t. to give complexes (12) and (14), respectively. The
molecular structures of complexes 2a, 3b, 8a and 14 have been determined by X-ray crystallography. © 1999 Elsevier Science S.A.
All rights reserved.
Keywords: Acetylide complex; Platinum complex; Cycloaddition; Electron-deficient olefin
1. Introduction
to p-allyl complexes, through green charge-transfer
(CT) complexes.
Extensive studies have been focused on transition
metal acetylide complexes due to their unique proper-
ties and their potential in materials chemistry [1]. Since
the acetylenic group of a transition metal acetylide is
electron-rich, the reactivity towards electrophilic addi-
tions such as protonation and alkylation at b-position
seems to be high to generate vinylidene complexes [2].
On the other hand, when a transition metal acetylide is
treated with electron-poor olefins, cycloaddition to the
CꢀC bond occurs [3–7]. For example, tungsten or
ruthenium acetylide complexes react with tetracya-
noethylene (TCNE) to give s-cyclobutenyl complexes,
which isomerize to s-butadienyl complexes and further
We have been investigating the chemistry of m-
ethynediyl dinuclear complexes of platinum and palla-
dium, in which two metal atoms are linked by just one
acetylene unit [8]. Because the metal moiety M(PR3)2X
is known to be a good electron-donor [9], the reactivity
of the m-ethynediyl dinuclear complexes with an elec-
tron-poor olefin is of considerable interest. Thus, we
have examined the reaction of m-ethynediyldiplatinum
complexes with TCNE and found the formation of
s-cis- and s-trans-m-butadiene-2,3-diyldiplatinum com-
plexes, which may be the first examples of m-butadiene-
2,3-diyl dinuclear complexes, though a large number of
studies have been made on the chemistry of hydrocar-
bon-bridged multinuclear complexes [10], including m-
butadienediyl complexes [11]. We present here full
details of our work on the reaction of acetylene-bridged
dinuclear complexes with TCNE. A portion of this
work has already been communicated [12].
* Corresponding author.
1 Also corresponding author.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01119-X

170
K. Onitsuka et al. / Journal of Organometallic Chemistry 578 (1999) 169–177
2. Results and discussion
2.1. Reactions of acetylene-bridged diplatinum
complexes with TCNE
Fig. 2. Molecular structure of 3b. Hydrogen atoms and the solvent
molecules are omitted for clarity.
Although similar treatment of 1b bearing tri-
ethylphosphine ligands afforded orange crystals in 65%
yield, spectral data suggest that the product is a 1:1
mixture of m-s-cis-butadiene-2,3-diyldiplatinum com-
plex (2b) and another complex (3b). Fortunately we
were able to obtain a single crystal of 3b by the
recrystallization of the product from dichloromethane–
toluene and found 3b to be a m-s-trans-2,3-butadi-
enediyldiplatinum complex by X-ray crystallography
(Fig. 2). Complex 3b involves the first s-trans confor-
mation of 1,1,4,4-tetracyanobutadiene-2,3-diyl ligand
since the stereochemistry of the 1,1,4,4-tetracyanobuta-
dienyl ligand is s-cis in almost all examples previously
reported [4].
When m-ethynediyldiplatinum complex (1a) was
treated with TCNE in benzene at room temperature
(r.t.), no reaction occurred and complex 1a was recov-
ered quantitatively. However, treatment of complex 1a
with TCNE under reflux in benzene gave a green
solution, suggesting the formation of a CT complex [4].
The reaction mixture slowly changed to an orange
solution as the reaction progressed. After 5 h the reac-
tion was worked up and yellow crystals (2a) were
isolated in 56% yield. The structure of 2a was unequiv-
ocally identified to be a m-s-cis-butadiene-2,3-diyldiplat-
inum complex by spectral analyses and an X-ray
diffraction study (Fig. 1).
It should be noted that the 31P-NMR spectrum of the
chloroform-d1 solution of a single crystal of 3b showed
peaks due to both 2b and 3b in about a 1:1 molar ratio,
and no change was observed even at 120°C in tetra-
chloroethane-d2. These results suggest that two isomeric
complexes 2b and 3b in solution are in a very slow
equilibrium presumably by the rotation around the
C–C single bond of butadiene-2,3-diyl-bridge. The
bulky metal moieties and dicyanomethylene groups
bound to the butadiene-2,3-diyl skeleton must limit the
fast rotation of the C–C bond. It may be reasonable to
propose that complex 2 is produced by the cycloaddi-
Fig. 1. Molecular structure of 2a. Hydrogen atoms are omitted for
clarity.

K. Onitsuka et al. / Journal of Organometallic Chemistry 578 (1999) 169–177
171
tion of TCNE to the CꢀC triple bond of 1 followed by
the cleavage of the C–C single bond of cyclobutene-
1,2-diyl complex (4) [4]. Therefore, the s-cis complex 2
would be generated as a kinetically favored product.
Since no isomerization of 2a into an s-trans analog was
observed at ambient temperature and complex 3b easily
isomerized into 2b, the s-cis complexes 2 are thermody-
namically more stable than 3. Interestingly almost all
tetracyanobutadienyl complexes previously reported
have an s-cis conformation [4]. Steric repulsion between
metal moieties, however, was observed in the molecular
structure of complex 2a (vide infra). Strong steric repul-
sion between metal moieties due to larger triethylphos-
phine ligands may cause a destabilization of 2b in favor
of the less hindered complex 3b. High crystallinity of 3b
relative to 2b would cause the fractional crystallization
of 3b from the solution containing a mixture of 2b and
3b.
In contrast, the reversible dynamic behavior was
observed in the variable temperature 31P-NMR of 2a in
tetrachloroethane-d2 as shown in Fig. 3. At higher
temperatures, the sets of resonances broaden and coa-
lesce at 106°C. The singlet signal at higher temperature
may be ascribed to the formation of 4a by the retro
reaction. However, the steric repulsion between the two
platinum moieties, which would be severer than 2a
since the torsion angle Pt–C–C–Pt becomes much
smaller than that of 2a, may make 4a unstable. This
change of spectra may also be explained either by
rotation around the C–C bond of the butadienediyl
ligand or by rotation around the Pt–C bond. Consider-
ation using a CPK model based on the X-ray structure
of 2a suggests that the rotation around the Pt–C bond
receives severe steric repulsion between the two metal
moieties. In contrast, fast rotation around the C–C
bond of the butadienediyl ligand could occur at high
temperature to produce complex 3a, of which tri-
ethylphosphine analog has been isolated as described
above, as an intermediate. On cooling the NMR sample
to 20°C, the two sharp doublet signals assignable to 2a
appeared, indicating that complex 2a is a thermody-
namically stable isomer relative to complex 3a.
While treatment of the m-ethynediyldipalladium com-
plex (5) and the palladium–platinum complex (6) with
TCNE at r.t. in benzene resulted in no reaction, a
similar reaction in refluxing benzene resulted in the
decomposition of the complexes giving a complex mix-
ture containing colloidal metal species. In contrast to
the m-ethynediyl complexes, the reaction of the m-bu-
tadiynediyldiplatinum complex (7a) with TCNE pro-
ceeded smoothly at r.t. to give the yellow complex (8a)
Fig. 3. Variable temperature 31P-NMR of 2a in tetrachloroethane-d2.
(a) At 20°C; (b) at 85°C; (c) at 106°C; and (d) at 135°C.

172
K. Onitsuka et al. / Journal of Organometallic Chemistry 578 (1999) 169–177
show that the CꢀC bonds of 8 and 10 do not have
reactivity towards TCNE. Although the different re-
activity between 7 and 8 as well as 9 and 10 may be
explained by either the steric or electronic effect of
the tetracyanobutadienediyl group, the latter seems to
be more plausible on the basis of the result described
below. Recently Bruce and his coworkers reported the
reaction of
a
butadiynyltungsten complex with
TCNE, and showed that although the addition of
TCNE to the butadiynyltungsten complex selectively
occurs at the CꢀC bonds located further from the
metal atom, the second reaction with TCNE was not
observed. They also proposed that the electronic ef-
fect of the tetracyanobutadienediyl group precludes
the second addition of TCNE [6].
Fig. 4. Molecular structure of 8a. Hydrogen atoms are omitted for
clarity.
in 62% yield [5]. Complex 8a was characterized by a
combination of spectral analyses and X-ray crystal-
lography. The unit cell contains two independent
molecules; one of which is shown in Fig. 4. Though
complex 8a has an s-cis-tertacyanobutadienyl group,
conversion into s-trans isomer was not observed since
two platinum groups are located at a significant dis-
tance from each other. Similar treatment of a tri-
butylphosphine analog (7b) with TCNE gave complex
8b in 77% yield. Since the m-butadiynediyldiplatinum
complexes reacted with TCNE at r.t., the reaction
was successfully extended to a palladium analog (9).
m-Butadiynediyldipalladium complexes (9a) and (9b)
were treated with TCNE at r.t. to give similar prod-
ucts (10a) and (10b), respectively. The difference in
the reactivity of the m-ethynediyl and m-butadiynediyl
complexes with TCNE may be caused by the steric
factors around CꢀC bonds. A similar result was ob-
tained from the reaction with 7,7,8,8-tetra-
When p-diethynylbenzene-bridged diplatinum com-
plex (11) treated with TCNE at r.t., a similar reaction
took place to give a reddish–orange complex (12) in
70% yield. Treatment of 11 with two equivalents of
TCNE similarly gave 12. Since the CꢀC bond of 12 is
linked with the tetracyanobutadienediyl group
through a p-phenylene group, the steric influence of
tetracyanobutadienediyl would be weak. Therefore,
the great electron-withdrawing feature of the tetra-
cyanobutadienediyl group may decrease the reactivity
of the CꢀC bonds in 12 toward TCNE. Mononuclear
platinum acetylide (13) also reacted with TCNE at
r.t. to give a butadienyl complex (14), of which the
structure has been determined by X-ray crystallo-
graphic analysis (Fig. 5). The tetracyanobutadienediyl
group of 14 also adopts an s-cis conformation as
observed in 8a.
cyanoqunodimethane
(TCNQ).
While
the
mononuclear platinum acetylide reacts with TCNQ in
a similar fashion to that with TCNE to give a butadi-
enyl complex [3], no reaction was detected on treat-
ment of the m-ethynediyl and m-butadiynediyl
complexes with TCNQ. Since the m-butadiynediyl
complexes have two CꢀC bonds in the molecule, we
examined the reaction with an excess of TCNE.
Treatment of 7a with two equivalents of TCNE, how-
ever, also gave 8a and no other complexes could be
detected. No reaction occurred on treatment of 8a
with TCNE under reflux in benzene. Similarly reac-
tions of 7b and 9a with two equivalents of TCNE
gave 8b and 10a, respectively. These results clearly
2.2. Molecular structures of 2a, 3b, 5a and 14
Structural parameters for the tetracyanobutadienyl
ligands and around the Pt atom bound to the tetra-
cyanobutadienyl ligands are summarized in Tables 1
and 2, respectively. The C–C bond distances of tetra-

K. Onitsuka et al. / Journal of Organometallic Chemistry 578 (1999) 169–177
173
cyanobutadienyl ligands in these complexes 2a, 3b, 5a
and 14 are comparable to those of tetracyanobutadienyl
complexes [3,4] and m-butadienediyldiiron complexes
[11]. However, it may be of interest that the C2–C3
distance of the tetracyanobutadienediyl ligand in 3b is
slightly longer than in the other complexes 2a, 5a and
14 in spite of a structural advantage for the conjugation
of two CꢁC bonds. The torsion angles of Pt–C2–C3–Y
in three s-cis-tetracyanobutadienyl complexes are com-
parable to each other, but slightly smaller than those of
s-cis-tetracyanobutadienyl complexes containing metals
other than platinum [4]. The planes consisting of
CꢁC(CN)2 groups are located almost perpendicular to
the Pt coordination plane in all complexes to avoid
steric hindrance between the bulky phosphine ligands
on the Pt atom and the cyano groups of PtCꢁC(CN)2.
The coordination around the Pt atom linked to tetra-
cyanobutadienyl ligand adopts a square planer geome-
try. There are no significant differences for the bond
distances around platinum atoms of the tetracyanobu-
tadienylplatinum group in these complexes, but some
differences are observed relative to those of the
vinylplatinum complex trans-Pt[CHꢁCH2](PEt2Ph)2Cl
(15) [13] and the butadienylplatinum complex trans-
Pt[C(ꢁCH2)CMeꢁCH2](PPh3)2Cl (16) [14]. In the tetra-
cyanobutadienylplatinum complexes, the Pt–C and
Pt–Cl bond lengths are slightly longer and the Pt–Cl
bond lengths are slightly shorter than those of 15 and
16. These may be due to the great electron-withdrawing
feature of the tetracyanobutadienyl group. It is of
interest that two P–Pt–P axes in 2a are bent away due
to the steric repulsion between two bulky platinum
moieties. Therefore, it seems reasonable that tri-
ethylphosphine analog 2b with larger steric repulsion
results in the partial isomerization into 3b.
Two independent molecules of complex 8a are similar
but slightly different in their structural parameters.
Though two values are given for each structural
parameter as below and Tables 1 and 2, the former
belongs to the molecules illustrated in Fig. 4 and the
latter to another molecule. The tetracyanobutadienyl
group has an s-cis conformation [dihedral angles CꢁC–
CꢁC: 43(2), 50(2)°] while the reaction of a butadiynyl-
tungsten complex with TCNE gave a product involving
the s-trans-tetracyanobutadienyl group. The C3–C4
˚
and CꢀC bond distances [1.20(3) and 1.15(2) A] are in
the normal range though the CꢁC and CꢀC groups are
on the same plane. The Pt–CꢀC–C3 groups are slightly
bent [Pt–CꢀC: 174(2) and 173(2)°, C3–CꢀC: 165(2) and
170(2)°]. The P–Pt–P axes of both tetracyanobutadi-
enyl- and ethynyl-platinum groups are almost straight,
in contrast to those of 2a, suggesting that the steric
repulsion between two platinum moieties is relaxed by
the acetylene group between the tetracyanobutadienyl
ligand and the platinum atom. Therefore, no isomeriza-
tion into the s-cis analog would be observed in contrast
to 2b. Coordination planes of the ethynylplatinum
groups are almost perpendicular [dihedral angles: 90.5
and 97.7°] relative to the plane defined by the
CꢁC(CN)2 bound to the acetylene groups as observed
in the PtCꢁC(CN)2 groups of 8a and other tetra-
cyanobutadienyl complexes (see above). Though com-
plex 14 is a mononuclear s-cis-tetracyanobutadienyl-
platinum complex, structural parameters of the tetra-
cyanobutadienyl ligands closely resemble other s-cis-te-
tracyanobutadienyl dinuclear complexes 2a and 8a,
suggesting that the interaction between two metal
atoms in 2a and 8a is not so large.
3. Experimental
All reactions were carried out under an atmosphere
of argon, but the workup was performed in air. NMR
spectra were recorded on JEOL FX-100, JNM-A400,
JNM-LA600 and Brucker AM-360 spectrometers. 13C-
NMR were measured in CDCl3 using SiMe4 as an
internal standard, and an external reference of PPh3 in
C6D6 was used for 31P-NMR. IR spectra were obtained
on a Hitachi 295 infrared spectrophotometer and FAB
mass spectra on a JMX-DX300 spectrometer. Elemen-
tal analyses were performed by the Material Analysis
Center, ISIR, Osaka University.
Acetylene-bridged diplatinum [7,15] and platinum–
acetylide complexes [16], were prepared by the method
reported previously. TCNE was purchased from
Aldrich and used without further purification.
Fig. 5. Molecular structure of 14. Hydrogen atoms, and carbon atoms
C(25B) and C(26B), which are disordered models of C(25A) and
C(26A), are omitted for clarity.

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K. Onitsuka et al. / Journal of Organometallic Chemistry 578 (1999) 169–177
Table 1
Structural parameters for tetracyanobutadienyl ligands in 2a, 3b, 8a and 14
2a
3b
8a
14
˚
Bond lengths (A)
Pt–C2
C1–C2
C2–C3
C3–C4
C3–Y
C–CN
C–N
2.00(1), 2.005(10)
1.36(1), 1.37(1)
1.47(1)
–
–
2.00(1)
1.35(2)
1.54(3)
–
1.98(2), 1.95(2)
1.34(2), 1.42(2)
1.48(2), 1.46(2)
1.38(2), 1.34(2)
1.40(2), 1.44(3)
1.40(3)–1.46(3)
1.13(3)–1.17(2)
1.998(4)
1.361(5)
1.473(5)
1.362(6)
1.506(6)
1.424(6)–1.446(7)
1.141(6)–1.145(6)
–
1.42(1)–1.47(2)
1.13(1)–1.15(1)
1.45(2)–1.47(2)
1.14(2)–1.15(2)
Bond angles (°)
Pt–C2–C1
Pt–C2–C3
C1–C2–C3
C2–C3–C4
C2–C3–Y
119.2(8), 121.8(8)
118.1(7), 121.8(8)
119.4(10), 122.7(10)
–
118.6(10)
123(1)
117(1)
–
124(1), 123(1)
116(1), 120(1)
119(1), 115(1)
123(1), 123(1)
119(1), 120(1)
119(1)–125(1)
113(1)–116(1)
125.3(3)
115.5(3)
119.2(3)
124.2(4)
119.5(3)
–
–
C–C–CN
NC–C–CN
118(1)–129(1)
112(1), 112.1(10)
121(1), 129(1)
109(1)
120.8(4)–125.8(4)
113.3(4), 115.1(4)
Torsion angles (°)
Pt–C2–C3–C4
Pt–C2–C3–Y
123.8(10), 124(1)
0(2)
180
180
–
135(1), 132(1)
42(1), 40(2)
43(2), 50(2)
124.4(4)
54.3(5)
58.6(6)
122.8(4)
55.5(10)
55(1)
–
C1–C2–C3–C4
C1–C2–C3–Y
138(1), 136(1)
Dihedral angles (°)
PTa–[CꢁC(CN)2]
PT–PT
91.0, 91.5
45.4
91.9
0
89.1, 89.7
61.3, 69.5
93.6
–
a PT, coordination planes around Pt atom; CꢁC(CN)2, planes of dicyanoethylene group.
3.1. Reaction of Cl(Me3P)2PtCꢀCPt(PMe3)2Cl (1a)
with TCNE
3.2. Reaction of Cl(Et3P)2PtCꢀCPt(PEt3)2Cl (1b) with
TCNE
To a solution of complex 1a (237 mg, 0.3 mmol) in
20 ml of benzene was added TCNE (42 mg, 0.33 mmol)
and the mixture was stirred for 5 h under reflux. After
removal of the solvent in vacuo, the residue was
purified by alumina column chromatography using
dichloromethane. Recrystallization from dichloro-
methane–hexane gave yellow crystals 2a (157 mg,
56%); m.p. 265–270°C (dec.); IR (Nujol): w(CꢀN) 2195
This reaction was carried out by the method as
described above using complex 1b (287 mg, 0.3 mmol)
and TCNE (45 mg, 0.35 mmol) to give yellow crystals
3b (215 mg, 65%); m.p. 200–204°C (dec.); IR (Nujol):
w(CꢀN) 2205 cm−1
;
31P-NMR (CDCl3): l 13.06 (1JPt–
2
P=2495, JP–P=423 Hz), 8.00 (1JPt–P=2612 Hz), 7.68
(1JPt–P=2616, JP–P=423, JPt–P=38 Hz); 13C-NMR:
l; MS m/z=1083 (M+ −1); Anal. Calc. for
C32H60N4Cl2P4Pt2: C, 35.40; H, 5.57; N, 5.16; Cl, 6.53;
P, 11.41%. Found: C, 35.67; H, 5.40; N, 5.39; Cl, 6.27;
P, 11.43%.
2
4
cm−1
;
31P-NMR (CDCl3): l –5.64 (1JPt–P=2607 Hz,
2
2JP–P=423 Hz), −7.35 (1JPt–P=2616 Hz, JP–P=423
Hz, 4JPt–P=38 Hz); 13C-NMR: l 196.6 (JPt–C=989
Hz), 119.0 (JPt–C=76 Hz), 115.2 (JPt–C=117 Hz), 81.4
(t, JP–C=4 Hz, JPt–C=43 Hz), 15.3 (d, J=26 Hz),
14.2 (d, J=27 Hz); MS m/z=916 (M+); Anal. Calc.
for C20H36N4Cl2P4Pt2: C, 26.18; H, 3.95; N, 6.11; Cl,
7.73; P, 13.50%. Found: C, 26.38; H, 3.66; N, 5.97; Cl,
7.76; P, 13.58%.
3.3. Reaction of Cl(Et3P)2PtCꢀCCꢀCPt(PEt3)2Cl (7a)
with TCNE
Benzene solution (30 ml) containing complex 7a (491
mg, 0.5 mmol) and TCNE (70 mg, 0.55 mmol) was

K. Onitsuka et al. / Journal of Organometallic Chemistry 578 (1999) 169–177
175
Table 2
Structural parameters around the Pt atom bound to tetracyanobutadienyl ligands in 2a, 3b, 8a and 14 with those of related complexes 15 and 16
2a
3b
8a
14
15
16
˚
Bond lengths (A)
Pt–C
Pt–Cl
Pt–P
2.00(1), 2.005(10)
2.364(3), 2.363(3)
2.325(3), 2.320(3)
2.314(3), 2.314(3)
2.00(1)
1.98(2), 1.95(2)
1.998(4)
2.349(1)
2.349(2)
2.327(1)
2.032(23)
2.398(4)
2.295(3)
–
2.07(1)
2.367(4)
2.331(4)
2.328(4)
2.361(5), 2.357(6)
2.334(6), 2.322(6)
2.329(6), 2.320(6)
2.408(3)
2.296(9)
2.299(14)
Bond angles (°)
Cl–Pt–C
Cl–Pt–P
173.8(3), 177.9(3)
86.0(1), 84.6(1)
85.4(1), 84.6(1)
158.1(1), 162.0(1)
96.9(3), 97.3(3)
93.7(3), 93.8(3)
178.4(4)
87.2(1)
86.6(1)
169.9(1)
93.8(4)
92.6(4)
175.3(6), 176.3(5)
87.5(2), 88.1(2)
86.6(2), 85.8(2)
172.3(2), 172.9(2)
95.7(5), 95.1(5)
90.4(5), 91.1(5)
175.4(1)
86.50(5)
86.53(5)
168.08(4)
94.6(1)
169.9(7)
94.0(1)
–
171.9(1)
86.1(7)
–
165.1(4)
91.2(4)
89.7(4)
178.4(3)
89.7(4)
89.1(4)
P–Pt–P
P–Pt–C
93.3(1)
stirred for 5 h at r.t. After the solvent was removed
under reduced pressure, the residue was purified by
column chromatography on alumina with benzene–
dichloromethane (v/v=2/1). Recrystallization from
dichloromethane–hexane gave yellow crystals 8a (343
mg, 62%); m.p. 224–226°C; IR (Nujol): w(CꢀN) 2215,
3.5. Reactions of reaction of Cl(Et3P)2PdCꢀCCꢀCPd-
(PEt3)2Cl (9a) and Cl(Bu3P)2PdCꢀCCꢀCPd(PBu3)2Cl
(9b) with TCNE
These reactions were performed by the similar
method to those of platinum analog 7 to give com-
plexes 10a and 10b, respectively.
w(CꢀC) 2055 cm−1 13C-NMR: l 188.5 (t, JP–C=9 Hz),
;
159.3, 138.2 (t, JP–C=13 Hz), 118.0, 114.6, 114.5,
114.1, 107.0, 91.4 (t, JP–C=4 Hz), 82.0, 14.6 (vt, N=
17 Hz), 14.5 (vt, N=17 Hz), 8.1, 7.0; 31P-NMR
(CD2Cl2/CH2Cl2=1/2): l 21.7 (1JPt–P=2281 Hz), 18.4
(1JPt–P=2465 Hz); MS m/z=1109 (M+ +1); Anal.
Calc. for C34H60N4Cl2P4Pt2: C, 36.80; H, 5.45; N, 5.05;
Cl, 6.39; P, 11.16%. Found: C, 36.83; H, 5.15; N, 4.90;
Cl, 6.16; P, 11.21%.
10a: yellow–orange crystals; yield 59%; m.p. 180–
183°C (dec.); IR (Nujol): w(CꢀN) 2205, w(CꢀC) 2055
cm−1 13C-NMR: l 205.8 (t, JP–C=7 Hz), 156.0, 151.9
;
(t, JP–C=14 Hz), 116.7, 114.4, 114.0, 111.3, 109.3 (t,
J
P–C=5 Hz), 92.0 (t, JP–C=5 Hz), 81.6, 15.4 (vt,
N=14 Hz), 15.3 (vt, N=14 Hz), 8.4, 8.3; 31P-NMR
(CD2Cl2/CH2Cl2=1/2): l 26.2, 22.5; MS m/z=933
(M+ +3); Anal. Calc. for C34H60N4Cl2P4Pd2: C, 43.79;
H, 6.49; N, 6.01; Cl, 7.60; P, 13.29%. Found: C, 43.98;
H, 6.38; N, 6.22; Cl, 7.58; P, 13.18%.
3.4. Reaction of Cl(Bu3P)2PtCꢀCCꢀCPt(PBu3)2Cl (7b)
with TCNE
10b: yellow–orange crystals; yield 72%; m.p. 199–
111°C; IR (Nujol): w(CꢀN) 2210, w(CꢀC) 2055 cm−1
;
This reaction was carried out by the similar method
to that of 7a using complex 7b (527 mg, 0.4 mmol) and
TCNE (64 mg, 0.5 mmol) to give yellow crystals 8b
(454 mg, 77%). Hexane–benzene (v/v=2/1) was used
as an eluent of alumina column chromatography, and
recrystallization was performed from hexane; m.p.
119–121°C; IR (Nujol): w(CꢀN) 2210, w(CꢀC) 2055
13C-NMR: l 205.9 (t, JP–C=7 Hz), 155.6, 151.6 (t,
J
J
P–C=15 Hz), 116.7, 114.3, 114.2, 111.3, 108.5 (t,
P–C=5 Hz), 92.0 (t, JP–C=5 Hz), 82.1, 26.4, 26.3,
24.7 (vt, N=7 Hz), 24.4 (vt, N=7 Hz), 22.8 (vt,
N=13 Hz), 22.7 (vt, N=14 Hz), 13.8, 13.7; 31P-NMR
(CD2Cl2/CH2Cl2=1/2): l 17.3, 15.2; MS m/z=1270
(M+ +3); Anal. Calc. for C58H108N4Cl2P4Pd2: C,
54.88; H, 8.58; N, 4.41; Cl, 5.59; P, 9.76%. Found: C,
55.09; H, 8.39; N, 4.40; Cl, 5.79; P, 9.52%.
cm−1 13C-NMR: l 188.6 (t, JP–C=7 Hz), 159.0, 137.7
;
(t, JP–C=13 Hz), 118.2, 114.8, 114.6, 114.3, 106.4, 91.5
(t, JP–C=4 Hz), 82.5, 26.3, 26.1, 24.6 (vt, N=7 Hz),
24.3 (vt, N=7 Hz), 22.0 (vt, N=16 Hz), 21.9 (vt,
N=17 Hz), 13.9, 13.8; 31P-NMR (CD2Cl2/CH2Cl2=1/
2): l 13.0 (1JPt–P=2266 Hz), 11.1 (1JPt–P=2456 Hz);
MS m/z=1447 (M+ +2); Anal. Calc. for
C58H108N4Cl2P4Pt2: C, 48.16; H, 7.53; N, 3.87; Cl, 4.90;
P, 8.57%. Found: C, 48.28; H, 7.36; N, 3.87; Cl, 4.74; P,
8.70%.
3.6. Reaction of Cl(Et3P)2PtCꢀCC6H4CꢀCPt(PEt3)2Cl
(11) with TCNE
Complex 11 (317 mg, 0.3 mmol) was treated with
TCNE (51 mg, 0.4 mmol) in 30 ml of benzene for 25 h
at r.t. The solvent was removed under reduced pressure,
and the residue was purified by alumina column chro-

176
K. Onitsuka et al. / Journal of Organometallic Chemistry 578 (1999) 169–177
Table 3
Crystallographic data for 2a, 3b · 2C7H8, 8a and 14
2a
3b · 2C7H8
8a
14
Empirical formula
Formula weight
Crystal size (mm)
Crystal system
C20H36Cl2N4P4Pt2
917.51
0.25×0.20×0.20
Orthorhombic
C46H76Cl2N4P4Pt2
1270.11
0.45×0.35×0.30
Monoclinic
C34H60Cl2N4P4Pt2
1109.85
0.35×0.25×0.25
Monoclinic
C26H36ClN4P2Pt
696.08
0.50×0.50×0.20
Monoclinic
Unit cell dimensions
˚
a (A)
18.575(6)
21.909(7)
15.464(9)
13.549(3)
14.454(3)
13.770(2)
90.31(2)
2696(2)
P21/c (c 14)
2
1.564
54.12
6B2qB50
5212
5002
12.187(4)
24.769(2)
29.532(3)
92.25(2)
8908(3)
P21/c (c 14)
8
1.655
66.30
6B2qB50
16 561
16 504
10.911(6)
20.677(6)
13.914(7)
104.50(4)
3038(2)
P21/n (c 14)
4
1.521
48.12
6B2qB60
9526
9100
˚
b (A)
˚
c (A)
i (°)
3
˚
V (A )
6293(3)
Pbca (c 61)
8
1.937
92.35
6B2qB60
9975
9975
Space group
Z
Dcalc. (g cm−3
)
v(Mo–Ka) (cm−1
2q Range (°)
)
Reflections measured
Unique reflections
Rint
–
0.069
0.064
0.017
Reflections observed [I\2|(I)]
Number of variables
Residuals: R, Rw
4373
289
0.039, 0.042
1.18
0.89, −1.46
2370
262
0.041, 0.046
1.63
2.43, −1.02
8351
829
0.061, 0.068
1.90
1.77, −1.92
6083
325
0.029, 0.036
1.09
0.56, −1.07
Goodness of fit on F2
−3
˚
Max./min. transmission (e A
)
matography with dichloromethane to give a reddish–
made on a Rigaku AFC5R diffractometer with graphite
˚
orange paste 12 (256 mg, 70%); IR (Nujol): w(CꢀN)
monochromated Mo–Ka radiation (u=0.71069 A) us-
2215, w(CꢀC) 2115 cm−1
;
31P-NMR (CD2Cl2/
ing v-2u scan technique with a scan rate 16° min−1
.
CH2Cl2=1/2): l 21.2 (1JPt–P=2368 Hz), 15.2 (broad
signal, satellite signals were not detected); MS m/z=
1185 (M+ +1); Anal. Calc. for C40H64N4Cl2P4Pt2: C,
40.51; H, 5.44; N, 4.72; Cl, 5.99; P, 10.45%. Found: C,
40.36; H, 5.20; N, 4.83; Cl, 5.70; P, 10.23%.
Unit cells were determined and refined by a least-square
method using 25 reflections in the range 35°B2uB40°.
The data of weak reflections (IB10|(I)) were mea-
sured two times and averaged. Three standard reflec-
tions were monitored at every 150 measurements. No
damage was observed for 2a, 8a and 14, but the stan-
dards decreased by −8.2% during the data collection
for 3b · 2C7H8. Thus, a linear correction factor was
applied for 3b · 2C7H8. Intensities were collected for
Lorentz and polarization effects, and an empirical ab-
sorption collection was made using C-scan technique
for all complexes. Relevant crystal data are given in
Table 3.
3.7. Reaction of Cl(Et3P)2PtCꢀCC6H5 (13) with TCNE
To a solution of complex 13 (852 mg, 1.5 mmol) in
50 ml of dichloromethane was added TCNE (256 mg,
2.0 mmol) and the mixture was stirred for 8 h at r.t.
After the solvent was removed in vacuo, the residue
was purified by alumina column chromatography with
benzene. Recrystallization from methanol gave yellow–
orange crystals 14 (482 mg, 44%); m.p. 161–164°C; IR
The structures were solved by the Patterson method
in conjunction with subsequent difference Fourier syn-
thesis. All non-hydrogen atoms were refined anisotropi-
cally and all hydrogen atoms were included at the
calculated positions using isotropic thermal parameters.
All calculation were performed using the TEXSAN crys-
tallographic software package.
(Nujol): w(CꢀN) 2210 cm−1
;
31P-NMR (−50°C, d8-
toluene): l 24.0 (d, JP–P=367 Hz), 13.2 (2JP–P=367
Hz), satellite signals were not detected by the broaden-
ing of the signals; MS m/z=695 (M+ +1); Anal. Calc.
for C26H35N4ClP2Pt: C, 44.86; H, 5.07; N, 8.05; Cl,
5.09; P, 8.90%. Found: C, 44.58; H, 4.94; N, 7.78; Cl,
5.11; P, 8.75%.
2
4. Supplementary material
3.8. X-ray crystallographic studies
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 104509 and 104510 for com-
pounds 8a and 14, respectively. Copies of this informa-
Single crystals suitable for an X-ray diffraction anal-
ysis were mounted on a glass fiber with epoxy resin or
sealed in glass capillary. Diffraction measurements were

K. Onitsuka et al. / Journal of Organometallic Chemistry 578 (1999) 169–177
177
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CCDC, 12 Union Road, Cambridge, CB2 1EZ UK
(Fax: +44-1223-336-033; e-mail: deposit@ccdc.cam.
ac.uk. or www: http://www.ccdc.cam.ac.uk).
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This work was partly supported by a Grant-in-Aid
for Scientific Research on Priority Areas (No. 10149228
‘Metal-assembled Complexes’) from the Ministry of
Education, Science, Sports and Culture. We thank The
Material Analysis Center, ISIR, Osaka University, for
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