Using ligand exchange reactions to control the coordination environment of Pt(II) acetylide complexes: Applications to conjugated metallacyclynes

Article abstract of DOI:10.1016/S0022-328X(03)00792-7

Ligand exchange of cis-bis(diphenylphosphino)ethylene (dppee) with trans-(Ph₃P)₂Pt(C≡CR)₂ easily generates the cis-complexes (dppee)Pt(C≡CR)₂ in 64-95% yield. This transformation is used to convert pyridine-containing macrocycle 7 to its cis -analogue 8 and the macrocyclic bipyridine analogue 10 to the unique macrocyclic ligand 11. X-ray structural characterization of trans-complexes 5a and 5b and cis-complexes 6a and 6b are reported, as is the structure of the strained macrocycle 8.

Full text of DOI:10.1016/S0022-328X(03)00792-7

Journal of Organometallic Chemistry 683 (2003) 379ꢀ387
/
www.elsevier.com/locate/jorganchem
Using ligand exchange reactions to control the coordination
environment of Pt(II) acetylide complexes: applications to conjugated
metallacyclynes
Katie Campbell a, Robert McDonald b, Michael J. Ferguson b, Rik R. Tykwinski a,*
a Department of Chemistry, University of Alberta, Edmonton, Alta, Canada T6G 2G2
b X-ray Crystallography Laboratory, Department of Chemistry, University of Alberta, Edmonton, Alta, Canada T6G 2G2
Received 20 May 2003; received in revised form 24 July 2003; accepted 30 July 2003
Abstract
Ligand exchange of cis-bis(diphenylphosphino)ethylene (dppee) with trans-(Ph3P)2Pt(CÅ
/
CR)2 easily generates the cis-complexes
(dppee)Pt(CÅCR)2 in 64ꢀ95% yield. This transformation is used to convert pyridine-containing macrocycle 7 to its cis-analogue 8
/
/
and the macrocyclic bipyridine analogue 10 to the unique macrocyclic ligand 11. X-ray structural characterization of trans-
complexes 5a and 5b and cis-complexes 6a and 6b are reported, as is the structure of the strained macrocycle 8.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Alkynyl complexes; Metallacycles; Platinum acetylide; Platinacycles
1. Introduction
complexes to generate butadiynes has recently been
established, expanding the usefulness of complexes 1 [8].
Platinum acetylide complexes such as 1 or 2 are
readily available in high yields from the reaction of
terminal acetylenes with cis- or trans-(R3P)2PtCl2,
respectively [1,2]. With non-chelating phosphine ligands,
the stereochemistry of a cis-platinum center (1) can be
achieved if the reaction temperature is kept low
(ꢁ10 8C). At higher temperatures, isomerization of the
/
In the interest of generating varied supramolecular
building blocks from common precursors, we targeted
the conversion of trans-acetylides such as 2 to cis-
acetylides 1 via ligand exchange. We communicate
herein the results of this strategy, which has been
successfully tested with simple molecular systems such
cis-(R3P)2PtCl2 species to the thermodynamically more
stable trans-complex effectively competes with alkyny-
lation, affording the trans-product 2. Chelating phos-
phines such as Ph2PCH2CH2CH2PPh2 can prevent cis-
trans isomerization to give cis-acetylides (1) [3]. In
addition to small molecule complexes, these versatile
alkynylation reactions have been exploited for the
formation of carbon-rich oligomers [4], polymers [5],
macrocycles [6,7], and supramolecular complexes [3].
Furthermore, the reductive elimination by cis-platinum-
as 5aꢀ
/
c to generate the cis-derivatives 6aꢀc. We then
/
applied this methodology to the generation of a strained
macrocycle 8 and to the conversion of the bifunctional
macrocycle 10 to its cis-complex, 11. The solid state
characteristics of the trans- and cis-complexes are
compared via an analysis of the X-ray crystal structures
of the L2Pt(CÅ
derivatives 5a/6a and 5b/6b, respectively. A discussion of
the solidꢀstate structural features of the strained
platinacycle 8 is also presented.
/
CSiiPr3)2 and L2Pt(CÅ
/
Cꢀ
/
p-CNꢀC6H4)2
/
* Corresponding author. Tel.: ꢂ
/
1-780-492-5307; fax: ꢂ1-790-492-
/
/
8231.
E-mail address: rik.tykwinski@ualberta.ca (R.R. Tykwinski).
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00792-7

380
K. Campbell et al. / Journal of Organometallic Chemistry 683 (2003) 379ꢀ387
/
Table 1
Yields and NMR spectroscopic data for compounds 5a
/
c and 6a
/
c
ꢀ
ꢀ
2. Synthesis
column chromatography (alumina) gave the cis-bis(alk-
ynyl) complexes 6aꢀc as stable solids in good to
/
trans-Platinum alkynyl complexes 5aꢀ
pared as shown in Scheme 1 [1,2]. The appropriate
terminal acetylene 3aꢀc was added to a degassed
solution of (PPh3)2PtCl2 4 in Et2NH. A catalytic
amount of CuI was then added and the mixture was
stirred at 50 8C for a period of 14 h. After work-up, the
/
c were pre-
excellent yields. It is interesting to note that the cis-
bis(alkynyl) complexes were consistently more soluble
than the trans-analogues, significantly aiding their
isolation and characterization.
/
All of the bis(alkynyl) complexes, 5aꢀ
/
c and 6aꢀc,
/
were fully characterized using H- and 13C-NMR and
IR spectroscopies, electrospray mass spectral analysis,
and microanalysis, where possible. In addition to 31P-
NMR spectroscopy, convincing evidence for the con-
version from trans- to cis-stereochemistry came from
analysis of the 13C-NMR spectra. In the trans-com-
1
trans-(PPh3)2Pt(CÅ
/
CR)2 complexes, 5aꢀc, were all iso-
/
lated as stable, colorless solids in good yield (see Table
1).
The trans-bis(alkynyl) complexes were easily con-
verted to the cis-derivatives 6aꢀ
(or CD2Cl2) solution of the respective trans-complex
(5aꢀc) with one equivalent of cis-1,2-bis(diphenylpho-
sphino)ethylene (dppee). Analysis of the 31P-NMR
spectra of all of the trans-complexes 5aꢀc shows a
virtual triplet at ca. 20 ppm. Upon addition of the dppee
(d ꢁ22), a loss in intensity of the virtual triplet
corresponding to 5a
/c by treating a CH2Cl2
pounds 5aꢀ
/
c, the s-acetylide carbon (L2Pt(C Å
/CR)2)
/
appears as a triplet (d 128.9, 119.3 and 117.1, respec-
2
tively) with a two-bond cis-coupling JCꢀP
ꢃ15 Hz.
/
/
Upon chelation of the dppee ligand, the two phosphorus
nuclei are no longer magnetically equivalent, leading to
a more complex splitting pattern. This carbon resonance
appears as an apparent doublet of doublets at d 125.0
and 112.3 for 6a and 6b, respectively [9]. The cis-
/
/c is observed, concurrent with
ꢀ
the growth of a new psuedo-triplet further downfield at
2
ca. 54 ppm, attributed to 6aꢀ
/
c. The dissociated triphe-
4 ppm. In
coupling JCꢀP is still measured at 15 Hz in both cases,
but the trans-2JCꢀP coupling is significantly larger,
ranging from 137 Hz for 6a to 146 Hz for 6b [3].
nylphosphine is indicated by a resonance at ꢁ
/
addition to the deshielding of the phosphorus as the
trans-bis(phosphino)-species is converted to a cis-deri-
We next turned our attention toward the synthesis of
strained macrocycle 8 (Scheme 2). Beginning with
platinacycle 7 [6], treatment with one equivalent of
dppee in CH2Cl2 leads to the formation of 8 in 87%
isolated yield, subsequent to purification on an alumina
column. This stable, bright yellow solid was fully
characterized including single crystal X-ray analysis
vative, a decrease in the phosphorusꢀ
/
Pt coupling is also
observed, consistent with cis-bis(phosphino)ꢀ
/
Pt deriva-
2700 Hz for the trans-
1
tives [3]. The JPꢀPt is ca. 2600ꢀ
/
bis(alkynyl) derivatives 5aꢀ
/
c, whereas upon chelation of
1
the dppee to form 6aꢀ
/
c, JPꢀPt is ca. 2200ꢀ2300 Hz. In
/
all cases, the displacement of the triphenylphosphine
appeared to be greater than 90% complete in less than 2
h, but the mixtures were left overnight to ensure
complete reaction. Solvent removal and purification by
(vide infra). Like the acyclic complexes 6aꢀ
c, the 31P-
NMR spectrum provides convincing evidence for the
/
formation of 8: a single resonance is observed at 51.7
Scheme 1. Syntheses of cis- and trans-platinum bis(alkynyl) complexes.

K. Campbell et al. / Journal of Organometallic Chemistry 683 (2003) 379ꢀ
/387
381
Scheme 2. Synthesis of strained cis-platinacycle 8.
1
ppm with JPꢀPt
ꢃ
/
2267 Hz. The 13C-NMR spectrum
for the formation of 10 comes from the ESI mass
spectrum: a signal centered at m/z 2498.7 (100%
(125 MHz) of 8 is consistent with that observed in the
acyclic complexes and shows all 34 of the expected non-
equivalent carbon resonances.
This methodology has also been applied toward the
formation of a larger, bidentate, supramolecular build-
ing block, 11, as described in Scheme 3 [10]. Pyridine-
containing oligomer 9 [11] was desilylated using NaOH
intensity) corresponds to [Mꢂ
Hꢂ]ꢂ, and the isotopic
distribution of this signal is consistent with the calcu-
lated pattern for this complex [13].
/
The trans-platinacycle 10 was converted to the cis-
derivative 11 by treating with dppee in CH2Cl2. After
solvent removal, diethyl ether was used to extract out
the triphenylphosphine produced by the reaction, leav-
ing pure complex 11, isolated in 71% yield. The 31P-
NMR spectrum shows a single resonance at d 53.6 with
in THFꢀMeOH, and the deprotected oligomer was
/
treated with 4 under high dilution conditions in the
presence of a catalytic amount of CuI at 50 8C for 14 h.
After workup and solvent removal, the large platina-
1JPꢀPt
ꢃ2292 Hz, which is consistent with the other cis-
/
bis(alkynyl) species. Further support for the formation
of 11 comes from ESI mass spectral analysis, which
shows three significant signals at m/z 2281 (25%), 2265
cycle 10 was selectively precipitated out of a CH2Cl2ꢀ
/
acetone solution, in a reasonable yield for a macro-
cyclization [12]. This pale yellow solid, while quite
(75%) and 2243 (100%) corresponding to [Mꢂ
/
Kꢂ]ꢂ,
stable, showed limited solubility (B
3 mg mlꢁ1 in
/
[Mꢂ
/
Naꢂ]ꢂ and [MꢂHꢂ]ꢂ, respectively. Molecular
/
CH2Cl2), making purification by column chromatogra-
phy impractical. This fact contributed to the lower
isolated yield.
modeling for platinacycle 11 suggest that the syn- and
anti-conformations about platinum (syn conformation
is shown in Scheme 3) should be easily interconverted in
solution via bond rotation. Thus, it is unknown at
present which conformation is preferred.
The 31P-NMR spectrum of macrocycle 10 shows a
single resonance at 18.0 ppm, consistent with the
chemical shifts observed in the acyclic trans-acetylides.
Due to the limited solubility of 10, the signal/noise
resolution of the spectrum was insufficient for observa-
tion of the expected Pt satellite peaks. The 13C-NMR
spectrum of compound 10 showed similarly poor signal/
noise. While all of the 21 unique carbon resonances are
discernible, the alkynyl quaternary carbon peaks are of
especially low intensity, particularly those that are
coupled to phosphorus. The most convincing evidence
3. X-ray crystallographic analyses
Single crystals of air stable solids 5a, 5b, 6a and 6b for
crystallographic analysis were grown from solutions as
described in the experimental section. Key crystallo-
graphic details can be found in Table 2, and ORTEP
Scheme 3. Synthesis of trans-platinacycle 10 and cis-complex 11.

382
K. Campbell et al. / Journal of Organometallic Chemistry 683 (2003) 379ꢀ387
/
Table 2
Crystallographic data for 5a, 5b, 6a, 6b and 8
5a
5b
6a
6b
8
Formula
C
58H72P2PtSi2
1082.37
0.40ꢄ0.16ꢄ
Triclinic
C56H42Cl4N2P2Pt
1141.75
C48H64P2PtSi2
954.20
C45H32Cl2N2P2Pt
928.66
C103H75Cl4NOP2Pt
1741.47
Formula weight
Crystal dimensions (mm3)
Crystal system
/
/0.08
0.44ꢄ
/
0.33ꢄ
/
0.07
0.46ꢄ/0.18ꢄ/0.12
0.41ꢄ/0.09ꢄ/0.06
0.49ꢄ
/
0.20ꢄ0.19
/
Monoclinic
P21/c (no. 14)
Orthorhombic
Pbca (no. 61)
Monoclinic
P21/c (no. 14)
Triclinic
¯
P1 (no. 2)
¯
P1 (no. 2)
Space group
Unit cell dimensions
˚
a (A)
9.0547(6)
11.6651(8)
14.2860(10)
67.069(1)
87.606(1)
75.287(1)
1341.36(16)
1
13.3751(7)
11.1464(6)
16.6531(9)
25.3967(10)
24.6617(10)
30.4032(13)
17.0043(8)
14.1145(7)
17.0083(8)
10.1674(4)
15.3820(6)
27.2200(12)
97.089(1)
98.465(1)
99.225(1)
4108.8(3)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
94.9834(10)
103.8327(10)
ꢀ/
ꢀ/
3
˚
V (A )
2473.3(2)
2
1.533
19042.3(13)
16
3963.7(3)
4
1.556
Z
rcalc (g cmꢁ3
)
1.340
2.755
1.331
3.095
1.408
1.928
m (mmꢁ1
Reflections collected
Independent reflections (Rint
)
3.157
13590
3.790
21725
8589
5385 (0.0232)
5376
126311
19465 (0.0506)
13174
25786
16535 (0.0194)
14840
)
5050 (0.0222)
4258
8102 (0.0372)
6584
Observed reflections [F2o]2s(Fo2)]
/
Data/restraints/parameters
R1 [F2o]2s(F2o)]
wR2 [F2o] 3s(F2o)]
5385/6/376
0.0308
0.0804
5050/0/295
0.0329
0.0947
19465/3/947
0.0366
0.0979
8102/0/478
0.0280
0.0659
16535/2/1015
0.0342
0.0896
/
/
ꢁ
/
drawings are shown in Figs. 1ꢀ
/
4. Selected bond lengths
Single crystals of 8 were grown from a boiling 1,2-
dichloroethane solution upon cooling and form a coꢀ
/
and angles for 5a, 5b, 6a (two crystallographically
independent molecules) and 6b are summarized in Table
3 [14]. The only significant deviation in bond lengths
crystallite with two molecules of solvent. The solid-state
structure confirms the heavily distorted and non-planar
enyne framework, which would be expected due to the
cis-platinum linkage. Overall, the main core of the
macrocycle remains nearly planar, but then pivots
dramatically at alkylidene carbons C(17) and C(23) to
accommodate the square planar bonding to platinum.
The bonding about platinum is quite similar to that
observed for compounds 6. The majority of the distor-
tion and strain is therefore borne by the alkylidene and
acetylene framework. Little bond angle distortion oc-
between cis- and trans-derivatives is observed in the Ptꢀ
P bonds, which are consistently shorter for 6a and 6b
than for 5a and 5b. The PtꢀCC bond angles are typically
/
/
linear, with the notable exception of 6b, where a
significant distortion occurs in the solid state and
reduces these angles to 168.8(3) and 174.2(3)8. The
Å
/
Cꢀ
are all 1808. For complexes 6a and 6b, the Pꢀ
angles are quite consistent at 868 C, whereas the Å
PtꢀCÅ bond angles vary from 89 to 958.
/
Ptꢀ
/
CÅ
/
and Pꢀ
/
Ptꢀ
/
P bond angles for 5a and 5b
Ptꢀ
Cꢀ
/
/P
/
/
curs at the alkylidene bond angles C(16)ꢀ
/
C(17)ꢀC(19)
/
/
/
and C(22)ꢀC(23)ꢀC(25), which at 110.7(3) and
/
/
112.8(3)8 are comparable to those of 7 (ca. 112.58) [6].
In addition, the mean alkyne bond angle of 172.68 for 8
is only slightly less than that found for complex 7
CSii Pr3)2, 5a (20% probability
Fig. 2. Structure of trans-(Ph3P)2Pt(CÅ
/
Cꢀ
/
pꢀ
/
CNꢀ
/
C6H4)2×(CH2Cl2)2,
/
Fig. 1. Structure of trans-(Ph3P)2Pt(CÅ
/
5b (20% probability level, solvent omitted).
level).

K. Campbell et al. / Journal of Organometallic Chemistry 683 (2003) 379ꢀ
/387
383
Fig. 3. Structure of cis-(dppee)Pt(CÅ
/
CSii Pr3)2×
CH2Cl2, 6a (20%
/
probability level, solvent omitted).
˚
Fig. 5. Structure of 8. Selected bond lengths (A) and bond angles (8):
PtꢀP(1) 2.2686(8), PtꢀP(2) 2.2711(8), P(1)ꢀPtꢀP(2) 85.61(3), P(1)ꢀ
PtꢀC(20) 92.30(9), P(1)ꢀPtꢀC(21) 174.62(9), P(2)ꢀPtꢀC(20)
172.76(9), P(2)ꢀPtꢀC(21) 93.65(9), C(20)ꢀPtꢀC(21) 89.07(13), C(2)ꢀ
C(11)ꢀC(12) 177.0(4), C(11)ꢀC(12)ꢀC(13) 178.9(4), C(13)ꢀC(15)ꢀ
C(16) 174.2(4), C(15)ꢀC(16)ꢀC(17) 172.3(3) C(17)ꢀC(19)ꢀC(20)
166.8(4), PtꢀC(20)ꢀC(19) 169.9(3), PtꢀC(21)ꢀC(22) 171.5(3),
C(21)ꢀC(22)ꢀC(23) 173.8(4), C(23)ꢀC(25)ꢀC(26) 172.9(4), C(25)ꢀ
C(26)ꢀC(27) 171.1(4), C(27)ꢀC(29)ꢀC(30) 168.5(4), C(4)ꢀC(30)ꢀ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C(29) 174.5(4) (20% probability level; solvent and all but the ispo
carbon atoms of the phenyl groups removed for clarity).
Fig. 4. Structure of cis-(dppee)Pt(CÅ
/
Cꢀ
/
p ꢀ/
CNꢀ
/
C6H4)2×CH2Cl2, 6b
/
(20% probability level, solvent omitted).
150 mesh) from Aldrich Chemical Company Inc. Thin
layer chromatography (TLC): aluminum sheets coated
with alumina oxide N/UV254 or plastic sheets coated
(173.88) [6]. Thus, while platinacycle 8 appears to be
much more strained than 7, bond length analyses shows
that this is not actually the case (Fig. 5).
with silica gel G UV254 from Machereyꢀ
lization by UV light. M.p. Gallencamp apparatus;
Plan IR microscope (as
/Nagel: visua-
In conclusion, trans-bis(acetylide) complexes of Pt(II)
are easily converted to their cis-counterparts via ligand
exchange with dppee. These reactions proceed easily at
room temperature when triphenylphosphine is displaced
from the trans-complex. The ability to form the strained
macrocycle 8 gives an indication of a significant predis-
position toward chelation versus bridging for the dppee
ligand. Conversion of the platinacycle 10 to 11 demon-
strates the potential usefulness of this exchange reaction
for the formation of valuable supramolecular building
blocks.
uncorrected. IR spectra: Nicꢀ
/
solids or cast from CH2Cl2, as noted). H-, 13C-, and
31P-NMR: Varian Gemini 400 or 500 instruments at
room temperature in CD2Cl2. ESIMS (m/z): micromass
Zabspec oaTOF or PE Biosystems Mariner TOF
instruments; solvents as noted.
1
4.2. trans-(Ph3P)2Pt(CÅ
/
CSiiPr3)2 (5a)
An excess of TIPS acetylene (112 mg, 0.615 mmol)
was added to a degassed solution of 4 (114 mg, 0.144
mmol) in Et2NH (50 ml). A catalytic amount of CuI (5
mg, 0.03 mmol) was added and the mixture was stirred
4. Experimental
at r.t. for 12 h and then heated to 50 8C for 4 h. Etherꢀ
CH2Cl2 (100 ml, 1:1 v/v) were added, and the resulting
solution was washed with water (2ꢄ50 ml), sat. NH4Cl
(4ꢄ50 ml) and dried (MgSO4). Solvent removal and
subsequent precipitation from concentrated CH2Cl2
afforded 5a (121 mg, 78%) as an off-white solid. M.p.
/
4.1. General
/
Reagents were purchased reagent grade from com-
mercial suppliers and used without further purification.
Degassing of solvents was accomplished by vigorously
bubbling N2 through the solutions for greater than 45
min. All transmetallation reactions were performed in
dry glassware under an inert atmosphere of N2. Column
chromatography: alumina oxide (neutral, Brockman 1,
/
205 8C (dec.). Rfꢃ
/
0.68 (hexanesꢀ/CH2Cl2 2:1, alumina).
IR (mscope) 3079, 3052, 2939, 2887, 2859, 2031, 1573,
1
1481 cmꢁ1; H-NMR (400 MHz, CD2Cl2) d 7.85ꢀ
/7.80
(m, 12H), 7.38ꢀ7.31 (m, 18H), 0.57 (d, Jꢃ3.2 Hz, 36H),
/
/

384
K. Campbell et al. / Journal of Organometallic Chemistry 683 (2003) 379ꢀ
/387
Table 3
˚
A comparison of selected bond lengths (A) and bond angles (8) for 5a, 5b, 6a and 6b
b
5a
5b
6a
6a c
6b
Bond lengths
Ptꢀ
/
C(1)
C(3)
2.005(4)
2.024(4)
1.994(4)
2.004(5)
1.219(6)
1.207(7)
2.2622(12)
2.2600(13)
2.014(5)
2.011(5)
1.203(7)
1.213(7)
2.2587(13)
2.2599(13)
2.006(4)
2.009(3)
1.212(5)
1.205(5)
2.2583(9)
2.2545(9)
Ptꢀ
/
ꢀ/
ꢀ/
C(1)ꢀ
C(3)ꢀ
/C(2)
1.207(6)
1.152(6)
/C(4)
ꢀ/
ꢀ/
Ptꢀ
/
P(1)
P(2)
2.2973(8)
2.3161(10)
Ptꢀ
/
ꢀ/
ꢀ/
Bond angles
Ptꢀ
Ptꢀ
C(1)ꢀ
C(3)ꢀ
PꢀPtꢀ
CꢀPtꢀ
PꢀPtꢀC(1) [or P(1)ꢀ
PꢀPtꢀC(1?) [or P(2)ꢀ
/
C(1)ꢀ
/
C(2)
176.2(4)
176.2(4)
177.8(5)
176.2(5)
176.6(5)
178.4(5)
86.44(5)
88.77(18)
176.48(14)
177.06(15)
177.7(5)
177.1(5)
178.5(5)
174.6(5)
86.18(5)
89.24(18)
177.04(13)
177.42(14)
168.8(3)
174.2(3)
175.6(4)
176.0(4)
86.29(3)
95.32(14)
174.36(10)
176.40(10)
/
C(3)ꢀ
/
C(4)
ꢀ
ꢀ/
/
ꢀ/
a
/C(2)ꢀ
/
X
X
173.8(5)
/C(4)ꢀ
/
ꢀ/
180.0
ꢀ/
180.0
/
/P
Å
/
/
/
CÅ
/
180.0
93.75(10)
86.25(10)
180.0
87.26(11)
92.74(11)
/
/
/
Ptꢀ
/
C(1)]
/
/
/Ptꢀ
/C(3)]
a
b
c
Positional disorder at Si precludes accurate determination.
Crystallographically independent molecule A.
Crystallographically independent molecule B.
0.37 (septet, Jꢃ
/
7.3 Hz, 6H); 13C-NMR (100 MHz,
Hz, 4H); 13C-NMR (100 MHz, CD2Cl2, APT) d 135.1
CD2Cl2, APT) d 135.4 (psuedo-t, 2JCꢀP
ꢃ
/
6.3 Hz), 132.7
(psuedo-t, JCꢀP
131.3, 131.2 (t, JCꢀP
1JCꢀP
29 Hz), 130.9 (psuedo-t, JCꢀP
128.3 (psuedo-t, JCꢀP
2JCꢀP
15 Hz), 112.8 (t, JCꢀP
NMR (162 MHz, CD2Cl2) d 19.8 (psuedo-t, JPꢀPt
2601 Hz); ESMS (NO2MeꢀClCH2CH2Cl) m/z 1004
([Mꢂ
HꢂꢂMeOH]ꢂ, 100); ES HRMS m/z Calc. for
C55H43N2OP2Pt ([Mꢂ
HꢂꢂMeOH]ꢂ) 1004.2494,
Found 1004.2499. Anal. Calc. for C54H38N2P2Pt×
ꢃ
/
6.0 Hz), 133.2 (t, JCꢀP
ꢃ
/
1.3 Hz),
2
4
1
1
5
(psuedo-t, JCꢀP
ꢃ
/
29 Hz), 130.3, 128.9 (t, JCꢀP
ꢃ
/
15
5.3 Hz), 112.5, 18.8, 12.0;
31P-NMR (162 MHz, CD2Cl2) d 21.2 (psuedo-t,
JPꢀPt 2719 Hz); ESMS (NO2MeꢀClCH2CH2Cl) m/z
1082 ([Mꢂ
Hꢂ]ꢂ, 14), 900 ([MꢀCCSiiPr3ꢂHꢂ]ꢂ,
ꢃ
/
1.3 Hz), 131.1 (psuedo-t,
3
4
Hz), 128.1 (psuedo-t, JCꢀP
ꢃ
/
ꢃ
/
ꢃ
/1.0 Hz),
3
ꢃ
/
5.4 Hz), 119.6, 119.3 (t,
3
ꢃ
/
/
ꢃ
/
ꢃ
2.3 Hz), 107.8; 31P-
/
/
/
/
ꢃ
/
100); ES HRMS m/z Calc. for C58H73Si2P2Pt ([Mꢂ
/
/
Hꢂ]ꢂ) 1082.4374, Found 1082.4373. Anal. Calc. for
C58H72P2PtSi2: C, 64.36; H, 6.70. Found: C, 64.05; H,
6.64%. Single crystals for X-ray crystallography grown
by slow evaporation from a CD2Cl2 solution at r.t.
/
/
/
/
/
CH2Cl2: C, 62.51; H, 3.81; N, 2.65. Found: C, 63.28;
H, 3.64; N, 2.62%. Single crystals for X-ray crystal-
lography were grown by layering a CH2Cl2 solution
with hexanes and allowing slow diffusion at 4 8C.
4.3. trans-(Ph3P)2Pt(CÅ
/
Cꢀ
/
p-CNꢀC6H4) (5b)
/
TMS-protected ethynylbenzonitrile (60 mg, 0.30
mmol) was dissolved in THFꢀMeOH (20 ml) and
treated with NaOH [15]. After stirring at r.t. for 1 h,
/
4.4. trans-(Ph3P)2Pt(CÅ
/
Cpyrꢀ
/
meta-(CÅ
/
CSiiPr3))2
(5c)
ether (15 ml) was added and the resulting solution was
washed with sat. NH4Cl (2ꢄ
/
15 ml), dried over MgSO4
3-(Trimethylsilylethynyl)-5-(triisopropylsilylethy-
nyl)pyridine (28 mg, 0.079 mmol) was mono-depro-
and the solvent was removed. The resulting deprotected
alkyne was added, with no further purification, to a
degassed solution of 4 (120 mg, 0.152 mmol) in Et2NH
(50 ml). A catalytic amount of CuI (5 mg, 0.03 mmol)
was added and the mixture was stirred at 50 8C for 14 h.
tected by dissolving in THFꢀMeOH (20 ml) and
/
treating with K2CO3 (10 mg). After stirring at r.t. for
2 h, ether (15 ml) was added and the resulting solution
was washed with sat. NH4Cl (2ꢄ15 ml), dried over
/
Etherꢀ
resulting solution was washed with water (2ꢄ
sat. NH4Cl (4ꢄ50 ml) and dried (MgSO4). Solvent
removal and subsequent precipitation from concen-
trated CH2Cl2 afforded 5b (90 mg, 62%) as an off-white
/
CH2Cl2 (100 ml, 1:1 v/v) were added, and the
MgSO4 and the solvent was removed. The resulting
deprotected alkyne was added, with no further purifica-
tion, to a degassed solution of 4 (31 mg, 0.039 mmol) in
Et2NH (40 ml). A catalytic amount of CuI (3 mg, 0.02
mmol) was added and the mixture was stirred at 50 8C
/
50 ml),
/
solid. M.p. 228 8C (dec.). Rfꢃ
(CH2Cl2, cast) 3053, 2223, 2105, 1595, 1495 cmꢁ1; H-
NMR (400 MHz, CD2Cl2) d 7.80ꢀ7.75 (m, 12H), 7.47ꢀ
7.38 (m, 18H), 7.19 (d, Jꢃ8.6 Hz, 4H), 6.31 (d, Jꢃ8.6
/
0.25 (CH2Cl2, silica). IR
for 14 h. Etherꢀ
and the resulting solution was washed with water (2ꢄ
ml), sat. NH4Cl (4ꢄ50 ml) and dried (MgSO4). Solvent
removal and purification via column chromatography
/
CH2Cl2 (100 ml, 1:1 v/v) were added,
1
/
50
/
/
/
/
/

K. Campbell et al. / Journal of Organometallic Chemistry 683 (2003) 379ꢀ
/387
385
(CH2Cl2, alumina) afforded 5c (38 mg, 76%) as an off-
white solid. M.p. 191 8C (dec.). Rfꢃ0.78 (CH2Cl2,
alumina). IR (CH2Cl2, cast) 3056, 2942, 2864, 2155,
JCꢀPt
4JCꢀP
bons), 119.4 112.3 (psuedo-dd, JCꢀP
2JCꢀP
15 Hz (cis)), 110.7 (psuedo-dt, JCꢀP
2JCꢀPt 308 Hz), 108.6; 31P-NMR (162 MHz, CD2Cl2)
d 53.93 (psuedo-t, Jꢃ2276 Hz); ESMS (NO2Meꢀ
ClCH2CH2Cl) m/z 1710 ([2Mꢂ
Naꢂ]ꢂ, 61), 866
([Mꢂ
Naꢂ]ꢂ, 30); ES HRMS m/z Calc. for
C44H31N2P2Pt ([Mꢂ
H]ꢂ) 844.1610, Found 844.1613.
Anal. Calc. for C44H30N2P2Pt×CH2Cl2: C, 58.20; H,
ꢃ
ꢃ
/
270 Hz), 131.9, 131.8, 131.5 (psuedo-t,
/
/
5 Hz), 129.9ꢀ129.1 (m, two coincident car-
/
2
ꢃ146 Hz (trans),
/
3
2106, 1573, 1463 cmꢁ1; 1H-NMR (400 MHz, CD2Cl2) d
ꢃ
ꢃ
/
ꢃ31 Hz,
/
8.17 (br d, 2H, Jꢃ
7.40 (m, 20H), 6.50 (psuedo-t, 2H, Jꢃ
NMR (100 MHz, CD2Cl2, APT) d 150.8, 148.2, 140.6,
/
1.5 Hz), 7.82ꢀ
/
7.77 (m, 12H), 7.47ꢀ
/
/
/
2.0 Hz); 13C-
/
/
/
2
135.3 (psuedo-t, JCꢀP
1JCꢀP
29 Hz), 131.0, 128.4 (psuedo-t, JCꢀP
Hz), 124.5, 119.3, 117.1 (t, JCꢀP
104.1, 93.9, 18.8, 11.7; 31P-NMR (162 MHz, CD2Cl2)
d 19.9 (psuedo-t, JPꢀPt 2607 Hz); ESMS (NO2Meꢀ
ClCH2CH2Cl) m/z 1285.5 ([Mꢂ
Hꢂ]ꢂ, 100).
ꢃ
/
6.0 Hz), 131.4 (psuedo-t,
/
3
ꢃ
/
ꢃ
/
5.3
/
2
ꢃ
/
15 Hz), 109.0,
/
3.47; N, 3.01. Found: C, 58.13; H, 3.20; N, 2.96%. Single
crystals for X-ray crystallography were grown by
layering a CH2Cl2 solution with hexanes and allowing
slow diffusion at 4 8C.
ꢃ
/
/
/
4.5. cis-(dppee)Pt(CÅ
/
CSiiPr3)2 (6a)
4.7. cis-(dppee)Pt(CÅ
/
Cpyrꢀ
/
meta-(CÅ
/
CSiiPr3))2 (6c)
cis-1,2-bis(Diphenylphosphino)ethylene (18 mg, 0.045
mmol) was added to a solution of 5a (50 mg, 0.046
mmol) in CH2Cl2 (5 ml) and the mixture was stirred at
r.t. for 14 h. Solvent removal followed by purification
cis-1,2-bis(Diphenylphosphino)ethylene (8 mg, 0.02
mmol) was added to a solution of 6a (25 mg, 0.019
mmol) in CH2Cl2 (2 ml) and the mixture was stirred at
r.t. for 2 h. Solvent removal followed by purification via
via column chromatography (hexanesꢀ
alumina) afforded 6a (42 mg, 95%) as a colorless solid.
M.p. 250 8C (dec.). Rfꢃ0.68 (hexanesꢀCH2Cl2 2:1,
alumina). IR (CH2Cl2, cast) 2938, 2888, 2860, 2057,
1462, 1436 cmꢁ1 1H-NMR (400 MHz, CD2Cl2) d
7.89ꢀ7.83 (m, 8H), 7.50ꢀ7.31 (m, 14H), 0.98ꢀ0.93 (m,
/CH2Cl2 2:1,
gradient column chromatography (CH2Cl2 to CH2Cl2ꢀ
acetone 5:1, alumina) afforded 6c (14 mg, 64%) as a pale
blue transparent solid. M.p. 93 8C. Rfꢃ0.20 (neat
CH2Cl2, alumina). IR (CH2Cl2, cast) 2942, 2890, 2864,
2156, 2113, 1574, 1462 cmꢁ1 1H-NMR (400 MHz,
CD2Cl2) d 8.35 (br s, 2H), 8.26 (br s, 2H), 7.82ꢀ7.76 (m,
8H), 7.59ꢀ7.34 (m, 16H) 1.13ꢀ
1.12 (m, 42 H); 13C-
NMR (100 MHz, CD2Cl2) d 151.1, 148.8, 146.8
/
/
/
/
;
/
/
/
;
42H); 13C-NMR (100 MHz, CD2Cl2) d 146.9 (psuedo-
/
dd, 1JCꢀP
130.3 (psuedo-dt, JCꢀP
ꢃ
/
48, 2JCꢀP
ꢃ
/
26 Hz), 134.1ꢀ
/
133.9 (m), 131.5,
/
/
1
2
57, JCꢀPt
ꢃ
/
ꢃ
/
24 Hz), 129.2ꢀ
/
2
2
1
2
129.1 (m), 125.0 (dd, JCꢀP
15 Hz (cis), 111.3ꢀ108.4 (psuedo-dt, JCꢀP
2JCꢀPt 273 Hz), 19.1, 12.3; 31P-NMR (162 MHz,
CD2Cl2) d 52.0 (psuedo-t, JPꢀPt 2208 Hz); ESMS
(NO2MeꢀClCH2CH2Cl) m/z 976 ([Mꢂ
Naꢂ]ꢂ, 100),
955 ([Mꢂ
Hꢂ]ꢂ, 37); ES HRMS m/z Calc. for
C48H64NaSi2P2Pt ([Mꢂ
Naꢂ]ꢂ) 976.3562, Found
976.3560. Anal. Calc. for C48H64P2PtSi2×0.5H2O: C,
ꢃ/137 Hz (trans), JCꢀP
ꢃ
/
(psuedo-dd, JCꢀP
ꢃ
/
48 Hz, JCꢀP
ꢃ/26 Hz), 140.6,
3
/
ꢃ/30 Hz,
133.8ꢀ133.5 (m), 132.0, 130.0ꢀ
/
/
129.2 (m, two coincident
carbons), 124.1 119.8, 103.9, 94.5, 18.4, 11.7 (two
ꢃ
/
ꢃ
/
carbons not observed); 31P-NMR (162 MHz, CD2Cl2)
/
/
d 53.9 (psuedo-t, Jꢃ
ClCH2CH2Cl) m/z 1179 ([Mꢂ
([Mꢂ
Hꢂ]ꢂ, 100);
/
2277 Hz); ESMS (NO2Meꢀ
/
/
/
Naꢂ]ꢂ, 70), 1157
/
/
/
59.85; H, 6.80. Found: C, 59.83; H, 6.61%. Single
crystals for X-ray crystallography were grown by
layering a CH2Cl2 solution with hexanes and allowing
slow diffusion at 4 8C.
4.8. cis-Macrocycle 8
cis-1,2-bis(Diphenylphosphino)ethylene (6 mg, 0.02
mmol) was added to a solution of platinacycle 7 (25 mg,
0.015 mmol) in CH2Cl2 (2 ml) and the mixture was
stirred at r.t. for 14 h. Solvent removal followed by
4.6. cis-(dppee)Pt(CÅ
/
Cꢀ
/
p-CNꢀC6H4)2 (6b)
/
purification via column chromatography (hexanesꢀ
CH2Cl2 1:2, alumina) afforded 8 (20 mg, 87%) as a
bright yellow solid. M.p. 201 8C (dec.). Rfꢃ0.38
(hexanesꢀCH2Cl2 1:2, alumina). IR (CH2Cl2, cast)
3053, 2157, 2093, 1658, 1597, 1486 cmꢁ1 1H-NMR
(400 MHz, CD2Cl2) d 8.12 (d, Jꢃ2.0 Hz, 2H), 8.08 (t,
Jꢃ2.0 Hz, 1H), 7.85ꢀ7.78 (m, 8H), 7.50ꢀ7.00 (m, 54H);
13C-NMR (125 MHz, CD2Cl2, APT) d 153.8, 149.7,
148.7, 146.9 (psuedo-dd, 1JCꢀP 48 Hz, 2JCꢀP
26 Hz),
143.1, 142.1, 141.2, 140.9, 140.1, 133.9ꢀ133.7 (m), 131.6,
130.9 (two coincident carbons), 130.8, 130.4, 130.0
/
cis-1,2-bis(Diphenylphosphino)ethylene (10 mg, 0.025
mmol) was added to a solution of 5b (25 mg, 0.026
mmol) in CH2Cl2 (2 ml) and the mixture was stirred at
r.t. for 14 h. Solvent removal followed by purification
via column chromatography (CH2Cl2, alumina) af-
forded 6b (20 mg, 91%) as a light brown solid. M.p.
/
/
;
/
/
/
/
164 8C (dec.). Rfꢃ
/
0.70 (CH2Cl2, alumina). IR (CH2Cl2,
1H-
cast) 3054, 2223, 2112, 1597, 1495, 1483 cmꢁ1
;
ꢃ
/
ꢃ
/
NMR (400 MHz, CD2Cl2) d 7.81ꢀ
/
7.74 (m, 8H), 7.58ꢀ
/
/
7.35 (m, 18H), 7.22 (d, Jꢃ
/
8.6 Hz, 4H); 13C-NMR (100
1
MHz, CD2Cl2) d 146.7 (psuedo-dd, JCꢀP
1
ꢃ
/
48 Hz,
(psuedo-t, JCꢀP
ꢃ
/
58 Hz), 129.3ꢀ
/
129.2 (m), 129.0,
128.9, 128.1 (two coincident carbons), 127.9 (two
2JCꢀP
ꢃ
/
25 Hz), 133.6ꢀ133.3 (m), 132.6 (psuedo-t,
/

386
K. Campbell et al. / Journal of Organometallic Chemistry 683 (2003) 379ꢀ387
/
1
(m), 131.5, 130.8, 130.5, 129.7 (psuedo-t, JCꢀP
coincident carbons), 127.8, 127.6, 120.3, 112.1 (psuedo-
ꢃ57
/
2
2
dd, JCꢀP
(psuedo-d, 3JCꢀP
88.2; 31P-NMR (162 MHz, CD2Cl2) d 51.7 (psuedo-t,
Jꢃ2267 Hz); ESMS (NO2MeꢀClCH2CH2Cl) m/z 1548
([Mꢂ
Naꢂ]ꢂ, 100), 1525 ([MꢂHꢂ]ꢂ, 64). Anal. Calc.
ꢃ/118 Hz (trans), JCꢀP
ꢃ/12 Hz (cis)), 110.5
Hz), 129.1ꢀ129.0 (m), 127.9, 127.7, 127.4 (two coin-
/
ꢃ
/
27 Hz), 105.8, 102.9, 94.9, 93.9, 88.3,
cident carbons), 119.9, 95.6, 85.8 (4 carbons not
observed); 31P-NMR (162 MHz, CD2Cl2) d 53.6
/
/
(psuedo-t,
ClCH2CH2Cl) m/z 2265 ([Mꢂ
([Mꢂ
Hꢂ]ꢂ, 100).
Jꢃ
/
2292
Hz);
ESMS
(NO2Meꢀ
/
/
/
/
Naꢂ]ꢂ, 75), 2243
for C99H65NP2Pt: C, 77.94, H, 4.29, N, 0.92. Found: C,
77.75, H, 4.22, N, 0.95.
/
4.9. trans-Macrocycle 10
5. Supplementary material
Oligomer 9 (62 mg, 0.082 mmol) was deprotected by
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
dissolving in THFꢀMeOH (20 ml) and treating with
/
saturated NaOH solution (3 ml) [11]. After stirring at
r.t. for 4 h, ether (15 ml) was added and the resulting
Data Centre, CCDC nos. 210797ꢀ210801 for com-
/
pounds 5a, 5b, 6a, 6b and 8, respectively. Copies of
this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
solution was washed with sat. NH4Cl (2ꢄ15 ml), dried
/
over MgSO4 and the solvent was removed. The resulting
deprotected alkyne was added, with no further purifica-
tion, to a degassed solution of 4 (65 mg, 0.082 mmol) in
Et2NH (150 ml). A catalytic amount of CuI (5 mg, 0.03
mmol) was added and the mixture was stirred at 50 8C
1EZ, UK (Fax: ꢂ44-1223-336033; e-mail: deposit@
/
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
for 14 h. Etherꢀ
and the resulting solution was washed with water (2ꢄ
ml), sat. NH4Cl (4ꢄ50 ml) and dried (MgSO4). Solvent
removal (using no heat) followed by precipitation from
CH2Cl2ꢀacetone afforded 10 (45 mg, 45%) as a bright
yellow solid. M.p. 166 8C (dec.). Rfꢃ0.08 (hexanesꢀ
/
CH2Cl2 (150 ml, 1:1 v/v) were added,
Acknowledgements
/
50
/
We are grateful for financial support provided by the
University of Alberta and the Natural Sciences and
Engineering Research Council of Canada (NSERC).
K.C. thanks NSERC for a graduate scholarship. We
thank Gerdy Aarts and Glen Bigam for generous
assistance with the NMR analyses and Dr. Angelina
/
/
/
CH2Cl2 1:1, alumina). IR (CH2Cl2, cast) 3050, 2201,
2083, 1581, 1481 cmꢁ1; 1H-NMR (400 MHz, CD2Cl2) d
7.77 (d, 4H, Jꢃ
/
2.0 Hz), 7.65ꢀ
/
7.59 (m, 24H), 7.42ꢀ
/
7.37
6.82 (m,
MoralesꢀIzquierdo for ESI MS analyses.
/
(m, 12H), 7.35 (psuedo-t, 2H, Jꢃ
/
2.0 Hz), 7.31ꢀ
/
64H); 13C-NMR (125 MHz, CD2Cl2) d 150.3, 149.1,
2
142.3, 140.6, 139.1, 135.4 (psuedo-t, JCꢀP
ꢃ6.2 Hz),
/
References
1
131.2 (psuedo-t, JCꢀP
ꢃ/29 Hz), 130.9, 130.8, 130.4,
3
128.2 (psuedo-t, JCꢀP
ꢃ
/
6.6 Hz), 127.8 (two coincident
[1] (a) K. Sonogashira, T. Yatake, Y. Tohda, S. Takahashi, N.
Hagihara, J. Chem. Soc. Chem. Commun. (1977) 291;
(b) K. Sonogashira, Y. Fujikura, T. Yatake, N. Toyoshima, S.
Takahashi, N. Hagihara, J. Organomet. Chem. 145 (1978) 101.
[2] T.B. Peters, Q. Zheng, J. Stahl, J.C. Bohling, A.M. Arif, F.
Hampel, J.A. Gladysz, J. Organomet. Chem. 641 (2002) 53.
[3] J.A. Whiteford, C.V. Lu, P.J. Stang, J. Am. Chem. Soc. 119
(1997) 2524.
carbons), 127.5, 127.2, 120.7, 118.9 (signal too weak to
observe P or Pt coupling), 111.2 (signal too weak to
observe P or Pt coupling), 105.9, 95.7, 85.5; 31P-NMR
(162 MHz, CD2Cl2) d 18.0 (coupling to Pt not observed
due to poor signal/noise); ESMS (NO2Meꢀ
/
ClCH2CH2Cl) m/z 2498.7 ([Mꢂ
/
Hꢂ]ꢂ, 100).
[4] (a) Y. Liu, S. Jiang, K. Glusac, D.H. Powell, D.F. Anderson, K.S.
Schanze, J. Am. Chem. Soc. 124 (2002) 12412;
(b) P. Siemsen, U. Gubler, C. Bosshard, P. Gunter, F. Diederich,
¨
4.10. cis-Macrocycle 11
Chem. Eur. J. 7 (2001) 1333.
[5] (a) S. Takahashi, M. Kariya, T. Yatake, K. Sonogashira, N.
Hagihara, Macromolecules 11 (1978) 1063;
cis-1,2-bis(Diphenylphosphino)ethylene (5 mg, 0.01
mmol) was added to a solution of 10 (16 mg, 0.0064
mmol) in CH2Cl2 (5 ml) and the mixture was stirred at
r.t. for 14 h. Solvent reduction followed by washing with
(b) M.S. Khan, M.R.A. Al-Mandhary, M.K. AlꢀSuti, N. Feeder,
/
S. Nahar, A. Kohler, R.H. Friend, P.J. Wilson, P.R. Raithby, J.
¨
Chem. Soc. Dalton Trans. (2002) 2441.
[6] K. Campbell, R. McDonald, M.J. Ferguson, R.R. Tykwinski,
Organometallics 22 (2003) 1353.
diethyl ether (2ꢄ2 ml) and subsequent filtration
/
afforded 11 (10 mg, 71%) as a pale yellow solid. M.p.
160 8C (dec.). IR (CH2Cl2, cast) 3050, 2090, 1575, 1483
[7] (a) R. Faust, F. Diederich, V. Gramlich, P. Seiler, Chem. Eur. J. 1
(1995) 111;
1
cmꢁ1; H-NMR (400 MHz, CD2Cl2) d 7.95 (d, Jꢃ
/
2
(b) W.J. Youngs, C.A. Tessier, J.D. Bradshaw, Chem. Rev. 99
(1999) 3153;
Hz, 4H), 7.62ꢀ
7.18 (m, 48H), 7.05 (psuedo-t, Jꢃ
6.84 (m, 4H), 6.65ꢀ
6.61 (m, 8H); 13C-NMR (100 MHz,
CD2Cl2) d 151.6, 150.1, 141.9, 141.2, 139.6, 133.7ꢀ133.6
/
7.57 (m, 16H), 7.49ꢀ
/
7.45 (m, 8H), 7.37ꢀ
/
/
2.1 Hz, 2H), 6.88ꢀ
/
(c) S.M. Al-Qaisi, K.J. Galat, M. Chai, D.G. Ray, III, P.L.
Rinaldi, C.A. Tessier, W.J. Youngs, J. Am. Chem. Soc. 120 (1998)
12149;
/
/

K. Campbell et al. / Journal of Organometallic Chemistry 683 (2003) 379ꢀ
/387
387
(d) J.J. Pak, T.J.R. Weakley, M.M. Haley, Organometallics 16
(1997) 4505;
(e) E. Bosch, C.L. Barnes, Organometallics 19 (2000) 5522.
resulting trans-acetylide complex (analogous to 10) did not
convert to cis-derivative upon reaction with dppee, presumably
due to the reduced lability of the Et3P ligand.
[14] (a) For structures of comparable trans-complexes, see ref. [2]. For
cis-complexes see: L.R. Falvello, J. Fornie´s, J. Go´mez, E. Lalinde,
A. Mart´ın, M.T. Moreno, J. Sacrista´n, Chem. Eur. J. 5 (1999)
474;
[8] G. Fuhrmann, T. Debaerdemaeker, P. Bauerle, J. Chem. Soc.
¨
Chem. Commun. (2003) 948.
[9] This resonance is not observed in the 13C-NMR spectrum of
compound 6c due to insolubility and an insufficient signal/noise
ratio. In addition, the one-bond carbonꢀ
/
Pt coupling is not clearly
(b) M.I. Bruce, K. Costuas, J.F. Halet, B.C. Hall, P.J. Low, B.K.
Nicholson, B.W. Skelton, A.H. White, J. Chem. Soc. Dalton
Trans. (2002) 383;
discernible in the 13C-NMR spectra of complexes 5ꢀ
/6.
[10] See, for example: K. Campbell, C.J. Kuehl, M.J. Ferguson, P.J.
Stang, R.R. Tykwinski, J. Am. Chem. Soc. 124 (2002) 7266.
[11] K. Campbell, R. McDonald, R.R. Tykwinski, J. Org. Chem. 67
(2002) 1133.
(c) J.D. Bradshaw, L. Guo, C.A. Tessier, W.J. Youngs, Organo-
metallics 15 (1996) 2582.
[15] K.A. Hirsch, S.R. Wilson, J.S. Moore, J. Am. Chem. Soc. 119
(1997) 10401.
[12] C. Grave A.D. Schluter, Eur. J. Org. Chem. (2002) 3075.
¨
[13] We attempted to improve the solubility of this complex through
the use of Et3P rather than Ph3P ligands, but found that the