Step-controlled synthesis of platinum(II) acetylide frameworks from conjugated polyaromatic modules

Article abstract of DOI:10.1016/j.tetlet.2006.04.131

A simple synthetic route for the efficient preparation of mono- and dinuclear platinum(II) derivatives containing σ-bonded ethynyl aryl groups is described. A dinuclear complex pointing its two Pt-Cl dipoles in opposite directions is prepared either by co

Full text of DOI:10.1016/j.tetlet.2006.04.131

Tetrahedron Letters 47 (2006) 4687–4692
Step-controlled synthesis of platinum(II) acetylide frameworks
from conjugated polyaromatic modules
*
´
Raymond Ziessel and Stephane Diring
´
Laboratoire de Chimie Mole´culaire, Ecole de Chimie, Polymeres, Materiaux (ECPM), Universite Louis Pasteur (ULP),
`
25 rue Becquerel, 67087 Strasbourg Cedex 02, France
´
´
Received 20 March 2006; revised 18 April 2006; accepted 26 April 2006
Abstract—A simple synthetic route for the efficient preparation of mono- and dinuclear platinum(II) derivatives containing
r-bonded ethynyl aryl groups is described. A dinuclear complex pointing its two Pt–Cl dipoles in opposite directions is prepared
either by complexation of a back-to-back terpyridine ligand with platinum salts or by cross-coupling [(40-ethynylterpyridine)PtCl]
with dibromodidodecylphenyl derivatives. FT-IR, UV–vis absorption and cyclic voltammetry are used as spectroscopic tools to
characterize these new complexes.
ꢀ 2006 Elsevier Ltd. All rights reserved.
The design and synthesis of luminescent molecular
materials is one of the most attractive challenges at the
frontier of fundamental research, applications such as
light emitting devices and energy management. Ex-
tended p-systems have received particular attention
due to their multiple potential applications as advanced
electronic and photonic materials.1 The development of
such sophisticated systems still suffers from time-con-
suming empirical processes because structure–property
relationships are often not predictable in material sci-
ence. The rapid construction of highly luminescent
architectures remains an open avenue.2 Paramount in
such a design is the need to incorporate transition metals
(e.g., Ru(II), Os(II), Re(I), Pt(II), etc.), into the back-
bone in order to favour phosphorescence due to spin–
orbit coupling with heavy metals.3,4
development of this first generation of complexes was
limited by their non-emissive or short-lived metal-to-
ligand-charge-transfer electronic transitions (MLCT) in
solution at room temperature.8 This lack of emission
originates from low-lying d–d excited states, which
provide facile non-radiative deactivation pathways by
molecular distortion. One successful strategy used to
construct long-lived and emissive terpyridyl-plati-
num(II) complexes involves utilizing substituted terpyri-
dines ligands with low-lying LUMOs and/or ancillary
acetylide ligands with large electron-donating abilities
to raise the HOMO of the metal centre, resulting in a
reduction of the MLCT excited state energy.9 As a
result, the energy gap between the MLCT and the d–d
states increases favourably. This trend is confirmed in
many platinum(II) acetylide complexes and high quan-
tum yield and long life-time photoluminescence likely
due to Pt ! diimine MLCT.10 Recently, such a strategy
has proven to also be suitable in bipyridine based
Pt(II)–acetylide complexes.11 Theoretical investigations
confirm that the substituent effects on the terpyridyl-
platinum(II) acetylide ligand play a major role in the
tailoring of the optical properties of such complexes.12
Recently, there has been increasing interest in the prop-
erties of d8-platinum(II) complexes such as [Pt(di-
imine)L2] [L = halide, nitrile, thiolate, isocyanide and
acetylide].5 Terpyridine platinum(II) complexes and
analogues are among the best luminescent labels, widely
used as DNA intercalators6 and biological probes.7
Their spectroscopic properties and low-energy absorp-
tions also arise from MLCT transitions. However, the
Herein we describe our synthetic efforts to develop an
efficient procedure for the rapid construction of soluble
mononuclear and dinuclear platinum(II) complexes
bearing alkyne substituted polyaromatic fragments,
some of which contain uncomplexed terpyridine, bipyri-
dine and bipyrimidine units. The strategy consists in
*
Corresponding author. Tel.: +33 3 90 24 26 89; fax: +33 3 90 24 26
35; e-mail: ziessel@chimie.u-strasbg.fr
0040-4039/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2006.04.131

4688
R. Ziessel, S. Diring / Tetrahedron Letters 47 (2006) 4687–4692
producing in a single step the alkyne substituted Pt(II)
complex from the alkyne grafted organic fragments. By
following this method, we succeeded in rapidly making
complexes with extended p-systems (Chart 1), by cross-
coupling [(tert-terpy)PtCl](BF4), tert-terpy accounts
for 4,40,400-tert-butyl-2,20:60,200-terpyridine, with several
highly luminescent materials (1-ethy-ethynylperylene,13
2-ethynyl-9,90-dibutylfluorene,14 1-ethynylpyrene15) in
DMF under anaerobic conditions and mediated by
catalytic amounts of CuI (3 mol %). In our hands the
use of large amounts of copper (>10 mol %) resulted in
intractable mixture of polar complexes.
Similarly, complex 4a was readily prepared in good yield
from 1-ethynyl-6-triethylsilylacetylenpyrene. Deprotec-
tion of the silyl group with KF in protic conditions
produces 4b which has been cross-coupled with 1-
bromopyrene in the presence of low valent palladium(0).
The formation of complex 5 (Scheme 1) is confirmed by
ES–MS which exhibit a molecular peak at 1045.5
[MꢀBF4]+. This reaction is very sensitive to the reaction
conditions and the presence of the Pt–terpy subunit does
not tolerate strong bases and temperature above 60 ꢁC.
The proof-of-principle of our strategy is illustrated in
Scheme 2 and Chart 2. Various mononuclear (6, 7,168)
and dinuclear complexes (9b and 10b) bearing empty
coordination sites were prepared either using 1 equiv
of the mono- or 0.5 equiv of the diethynyl building
blocks, with respect to the Pt precursor. However, the
scope of this reaction suffered severely from low reactiv-
ity when the preparation of dinuclear complexes was
envisaged. The low yield (20%) obtained under stoichi-
ometric conditions was increased to 35% by using a
two-fold excess of the platinum(II) starting material.
During the preparation of complexes 9b and 10b, forma-
tion of the mononuclear complexes 9a and 10a are
clearly evidenced by TLC and could ultimately be
isolated in modest yields (25%). This is an interesting
situation because hybrid complexes bearing various
donor–acceptor spacing units could be envisaged for
+
-
BF4
N
N
N
Pt
1
2
3
Chart 1.
+
+
-
-
BF4
BF4
N
N
N
(i)
N
Pt
N
Pt
N
X
5
4a X = SiEt3
4b X = H
i
Scheme 1. Reagents and conditions: (i) 1-bromopyrene, [Pd(PPh3)4] (6 mol %), PrNH2, 60 ꢁC, 4 h.
+
-
BF4
N
N
N
Pt
+
-
N
BF4
N
6
(i)
+
N
N
-
BF4
N
N
Pt Cl
N
N
(ii)
N
Pt
N
+
-
BF4
N
7
N
N
N
N
N
(iii)
Pt
N
N
8
Scheme 2. Reagents and conditions: (i) 5-ethynyl-2,20-bipyridine, CuI (3 mol %); (ii) 4-ethynyl-2,20:60,200-terpyridine, CuI (3 mol %); (iii) 3-ethynyl-
2,20-bipyrimidine, CuI (10 mol %). All cases in DMF, TEA.

R. Ziessel, S. Diring / Tetrahedron Letters 47 (2006) 4687–4692
4689
C12H25
O
+
C12H25
O
H
Br
(i)
+
-
Br
BF4
N
N
(ii)
OC12H25
H
OC12H25
N
11
N
Pt
12
(iii)
N
2+
9a
N
N
N
N
N
OC12H25
-
N
2 BF4
N
N
N
N
H
N
Pt Cl
N
N
Pt
Pt
N
N
N
OC12H25
N
14
13
9b
(iv)
+
2+
N
N
OC12H25
N
N
N
N
-
(v)
BF4
Cl
Pt
N
N
Pt Cl
N
N
Pt
-
N
2 BF4
OC12H25
10a
N
15
2+
(vi)
N
N
-
N
2+
2 BF4
N
N
N
OC12H25
N
N
-
2 BF4
Pt
Pt
N
10b
N
C14H29
Pt
N
Pt
C14H29
N
N
N
N
OC12H25
16
Scheme 3. Reagents and conditions: (i) 2-methyl-3-butyn-2-ol,
Pd(PPh3)4 (12 mol %), nPrNH2, 65 ꢁC, 48 h, 88%; (ii) NaOH, C6H6,
70 ꢁC, 14 h, 75%; (iii) terpy–OTf, Pd(PPh3)4 (6 mol %), iPr2NH,
toluene, 70 ꢁC, 24 h, 85%; (iv) complex 14, CuI (6 mol %), TEA,
DMF, rt, 48 h, 87%; (v) K2PtCl4, CH3CN, H2O, CH2Cl2, 60 ꢁC CuI
(6 mol %), 23 h, 64%; (vi) C14H29C„CH, CuI (6 mol %), TEA, DMF,
rt, 24 h, 80%.
Chart 2.
specific applications in light emitting diodes. Indeed
the use of 2 equiv of 5,50-diethynyl-2,20-bipyridine or
2 equiv of 5,500-diethynyl-2,20:60,200-terpyridine versus
1 equiv of [(tert-terpy)PtCl](BF4) produces the mono-
nuclear complexes with acceptable yields (ꢁ75%).
Another way to extend the dimentionality of the di-
nuclear complexes and to inverse the directionality of
the MLCT transition (along the main axis in complex
15 versus the periphery in complexes 9b and 10b)
is to engineer back-to-back terpyridine ligands and
complexes (Scheme 3).
The desired solubility is imported by the use of building
block 11 carrying two dodecyloxy paraffin chains. Dou-
ble cross-coupling of 12 with [{(40-trifluoromethyl)sulfo-
nyl}oxy]-2,20:60,200-terpyridine and catalytic amounts of
palladium(0) afforded the ditopic ligand 13 in 85% yield.
A perspective view of ligand 13 determined by X-ray dif-
fraction is shown in Figure 1. As surmised from the
NMR studies, all three nitrogen atoms of a single terpy
moiety lie in a transoidal position that minimizes elec-
trostatic interactions between the neighbouring lone
pairs, a situation frequently found in oligopyridine
ligands. The crystal structure confirmed the flat arrange-
ment of the terpy fragments (around a 1ꢁ tilt) and the
complete planarity of all the ditopic ligand in the solid
state. A slight distorsion between the flat terpy and the
diphenoxyphenyl is evidenced by a weak dihedral angle
of 4–5ꢁ. A striking result revealed by the crystal packing
Figure 1. Top: ORTEP view of ligand 13 with atom labelling.
Probability displacement ellipsoids are shown at 50% level. Selected
distances and angles: C1A–C2A 1.186(10), C2–O1 1.361(8), C1–C1A
1.438(12), C2A–C1B 1.439(13) A; C1–C1A–C2A 177.6(3)ꢁ and C1A–
C2A–C1B 176.2(4)ꢁ. Bottom: crystal packing showing the planar
˚
organization of the molecules.
ꢀ
is the organization of the molecules in layers ½111ꢂ with
Complexation of 13 with K2PtCl4 in CH3CN/CH2Cl2/
H2O provides the insoluble complex 15 in 64% isolated
a graphite like-network and an average inter-layer dis-
˚
tance of 3.4 A (Fig. 1).

4690
R. Ziessel, S. Diring / Tetrahedron Letters 47 (2006) 4687–4692
yield. Interestingly, this dinuclear complex was also pre-
pared from complex 1417 by a double cross-coupling of
the dibromo derivative 11 with low valent palladium(0).
This chemistry on the complex is very efficient under the
(LLCT).19 This band is found near 470 nm in the fluo-
rene and pyrene complexes 2 and 3, whereas in the per-
ylene derivatives 1 it appears above 500 nm. This
bathochromic shift is induced by the increase of elec-
tronic density imported by the perylene moiety. Notice
that when a chloride is coordinated in place of an ethy-
nylaryl (compd 14) the MLCT is much weaker and
shifted to higher energies. Importing a second pyrene
residue in 5 with respect to complexes 4a and 4b resulted
in the increase of the absorptivity and a decrease of the
transition energy. Interestingly by grafting a second
alkyne–terpy–Pt unit on complex 6 leading to 9b the
absorption of the MLCT is not shifted but a non-linear
increase of the absorption coefficient is observed
(Fig. 2b). Finally, connecting two hexadecyne units in
place of the chloro ligands in complex 15 also resulted
in a bathochromic shift and an increase of the absorp-
tion coefficient in complex 16 (Table 1).
described conditions (87%). Complex 14 (dC„CH
=
3.17 ppm in DMSO-d6) was originally prepared in
77% yield from 40-ethynyl-2,20:60,200-terpyridine and
[Pt(DMSO)2Cl2]18 in THF at 80 ꢁC.
In DMF solution at 298 K, all the complexes show
intense multiple absorption peaks in the range 250–
500 nm (Fig. 2). On the basis of earlier studies of related
compounds,11,19 the high-energy structured absorption
bands are ascribed to p–p* transitions of the terpy units
and of the ethynylaryl moiety. In cases 1 and 3, the
intense additional absorption centred, respectively, at
463 and 400 nm is due to absorption of the perylene
and pyrene fragments. As expected such low energy
transitions are not present in the fluorene derivative 2
(Fig. 2a). The low energy absorption band in the visible
region is assigned to a platinum-to-ligand charge trans-
fer transition (MLCT) probably mixed with an alkynyl-
to-terpyridine ligand-to-ligand charge transfer character
Complexes 2 and 4a showed two quasi reversible coup-
les at ꢀ1.02 (DEp = 60 mV) and ꢀ1.51/56 V (DEp =
60 mV) versus ferroccene (+0.38 V) in CH2Cl2 and
nBuNPF6. The first reduction must arise from the
50000
60000
(a)
(b)
6
9b
1
2
50000
40000
4a
40000
30000
20000
10000
0
30000
20000
10000
0
250
350
450
550
250
300
350
400
450
500
550
Wavelength (nm)
Wavelength (nm)
Figure 2. Overlay of absorption spectra recorded for various complexes in dimethylformamide solution.
Table 1. Selected data for the novel Pt(II) complexes
mC„C (cmꢀ1
)
ES-MS (nature of the cluster)b
kmax (nm), e (Mꢀ1 cmꢀ1 c
)
a
Complex
Isolated yield (%)
1
2
3
4a
4b
5
6
7
73
85
92
69
92
62
67
88
76
35d
36d
77
64
80
2095
2110
2099
2155/2098
2139/2100
2206/2102
2115
2122
2119
2117
2192
2112
2203
871.4e+
507 (sh; 12,500); 463 (37,600); 437 (29,600)
466 (6800)
474 (7300)
470 (8600); 406 (51,500)
486 (12,500); 408 (56,200)
494 (13,200); 410 (99,300)
420 (6000)
403 (8450)
428 (7900)
424 (16,700)
465 (17,200)
897.5e+
821.4e+
959.5e+
845.4e+
1045.e5+e+
775.4
852.4e+
8
777.4e+
9b
10b
14
15
16
1481.7e+ ; 697.4e2+
1558.e7+e+; 735.5e2+
487.2
405 (3300)
439 (9200)
450 (19,400)
708.5e2+
895.1e2+
2202/2071
a One drop of CH2Cl2 containing the sample was evaporated on a KBr disk.
b Electro-spray mass spectroscopy in methanol/acetonitrile at Vc = 110 V. The molecular peaks correspond to [MꢀBF4]+, for complexes 9b, 10b, 15
and 16, [MꢀCl]+, for complexes 14, the 2+ peak correspond to [Mꢀ2BF4]2+. All isotopic profiles correspond to the expected sequence.
c Averaged value determined from at least two different solutions of non-degassed DMF solution.
d The corresponding mononuclear complexes have been obtained as side-products with an average yield of 25%.

R. Ziessel, S. Diring / Tetrahedron Letters 47 (2006) 4687–4692
4691
8.00
3.00
of this work in the form of an Allocation de Recherche
for S.D.
2
4a
Fc+/Fc
-2.00
-7.00
-12.00
References and notes
1. Kraft, A.; Grimsdale, A. C.; Holmes, A. B. Angew. Chem.
Int. Ed. 1998, 37, 402; Martin, R. E.; Diederich, F. Angew.
Chem. Int. Ed. 1999, 38, 1350; Segure, J. L.; Martin, N. J.
Mater. Chem. 2000, 10, 2403.
(a)
2000
1500
1000
500
0
-500
-1000
-1500
-2000
Potential/mV
2. Ziessel, R. Synthesis 1999, 1839.
3. Juris, A.; Balzani, V.; Barigelletti, F.; Campagna, S.; Beser,
P.; Von Zelewsky, A. Coord. Chem. Rev. 1988, 84, 85.
4. Chan, C. W.; Cheng, L. K.; Che, C. M. Coord. Chem. Rev.
1994, 132, 87; Paw, W.; Cummings, S. D.; Mansour, M.
A.; Connick, W. B.; Geiger, D. K.; Eisenberg, R. Coord.
Chem. Rev. 1998, 171, 125.
5. Hissler, M.; McGarrah, J. E.; Connick, W. B.; Geiger, D.
K.; Cummings, S. D.; Eisenberg, R. Coord. Chem. Rev.
2000, 208, 115.
6. Arena, G.; Monsu Scolaro, L.; Pasternack, R. F.; Romeo,
R. Inorg. Chem. 1995, 34, 2994.
7. Ratilla, E. M. A.; Brothers, H. M.; Kostic, N. M. J. Am.
Chem. Soc. 1987, 109, 4592.
15.00
10.00
5.00
6
9b
Fc+/Fc
0.00
-5.00
-10.00
(b)
2000
1500
1000
500
0
-500
-1000
-1500
-2000
Potential/mV
8. Michalec, J. F.; Bejune, S. A.; Cuttell, D. G.; Summerton,
G. C.; Gertenbach, J. A.; Field, J. S.; Haines, R. J.;
McMillin, D. R. Inorg. Chem. 2001, 40, 2193.
Figure 3. Cyclic voltammetry in dichloromethane containing 0.1 M
tetrabutylammonium hexafluorophosphate at rt, scan rate 200 mV sꢀ1
Ferrocene was used as internal reference +0.38 V versus SCE.
.
9. Yam, V. W. W.; Tang, R. P. L.; Wong, K. M. C.; Cheung,
K. K. Organometallics 2001, 20, 4476.
10. Yang, Q. Z.; Wu, L. Z.; Zhang, L. P.; Tung, C. H. Inorg.
Chem. 2002, 41, 5653.
11. Ha, F.; Kinayyigit, S.; Cable, J. R.; Castellano, F. N.
Inorg. Chem. 2005, 44, 471.
12. Liu, X.-J.; Feng, J.-K.; Meng, J.; Pan, Q.-J.; Ren, A.-M.;
Zhou, X.; Zhang, H.-X. Eur. J. Inorg. Chem. 2005, 1856.
13. Inouye, M.; Hyodo, Y.; Nakazumi, H. J. Org. Chem.
1999, 64, 2704.
14. Prepared by an adapted procedure from Thomas, K. R. J.;
Lin, J. T.; Lin, Y.-Y.; Tsai, C.; Sun, S.-S. Organometallics
2001, 20, 2262.
terpy-based reduction and the second reduction is tenta-
tively assigned to a metal-centred reduction whereas the
irreversible oxidation are likely assigned to fluorine and
pyrene based oxidation (Fig. 3a).20 In the bipyridine
complexes 6 and 9b, no such oxidation could be detected
within the given oxidation window but two reversible
reductions are also found at ꢀ0.99 (DEp = 60 mV) and
ꢀ1.50 V (DEp = 60 mV) in both complexes (Fig. 3b).
In summary, a series of mononuclear terpyridine–plati-
num(II) acetylide complexes bearing various appended
moieties (perylene, fluorene, pyrene, bipyridine, bipyri-
midine, terpyridine) and dinuclear complexes bridged
by a bipyridine, terpyridine or a back-to-back bis-ter-
pyridine ligand has been successfully synthesized using
a rational protocol. High solubility has been ensured
by the use of tert-butyl substituents on the terpy–Pt cen-
tre or by linear dodecyloxy chains grafted at the central
phenoxy moiety. The nature of the acetylide residues has
a strong influence on the absorption of the 3MLCT state
with a strong bathochromic shift observed for the elec-
tron-rich perylene module. This trend is confirmed by
increasing the number of pyrene nucleus. Preliminary
electrochemical studies showed two reversible redox
processes (ligand and Pt based) for the key complexes
2, 6 and 9b. Further work is directed towards the com-
plexation of the empty terpyridine and bipyridine sites
by luminescent transition metal salts in order to study
energy or electron transfer processes.
15. Harriman, A.; Hissler, M.; Khatyr, A.; Ziessel, R. Chem.
Commun. 1999, 735; Hissler, M.; Harriman, A.; Khatyr,
A.; Ziessel, R. Chem. Eur. J. 1999, 11, 3366.
16. Compound 7. The preparation began with the dissolution
of [(tBu3–terpy)PtCl](Cl) (0.163 g, 0.244 mmol) in a mix-
ture of DMF (3 mL) and triethylamine (1 mL), followed
by the addition of 4-ethynyl-2,20:60,600-terpyridine (0.063 g,
0.244 mmol). The solution was degassed vigorously by
bubbling argon through the solution. The addition of CuI
(0.001 g, 0.005 mmol) to the yellow solution resulted in the
instantaneous colour change to red. After stirring at rt for
one night, the deep-red solution is concentrated to roughly
1 mL and filtrated over Celite and dropped into an
aqueous solution (10 mL) containing NaBF4 (1.200 g).
The complex was recovered by filtration over paper,
washed with water (3 · 100 mL) and the red solid dried
under high vacuum. Purification was insured by column
chromatography using alumina as solid support and a
gradient of methanol (0–1%) in dichloromethane as
mobile phase. Ultimate recrystallization by slow evapora-
tion of dichloromethane from
a dichloromethane/
hexane solution afforded complex 7 (0.202 g, 88%). 1H
(200.1 MHz) NMR d 9.12 (d, 3J = 6.0 Hz, 2H), 8.97 (s,
2H), 8.96 (s, 2H), 8.89 (d, 3J = 8.0 Hz, 4H), 8.69 (dm,
3
3J = 4.8 Hz, 1H), 8.61 (d, J = 8.0 Hz, 1H), 8.47 (s, 2H),
Acknowledgements
7.87 (td, 3J = 8.0 Hz, 4J = 1.9 Hz, 1H), 7.60 (7 lines m,
2H), 7.34 (8 lines m, 1H), 1.65 (s, 9H), 1.52 ppm (s, 18H).
13C{1H} (100.6 MHz) d 169.3, 169.1, 168.3, 167.7, 162.5,
`
The Ministere de la Recherche et des Nouvelles Tech-
nologies is gratefully acknowledged for financial support

4692
R. Ziessel, S. Diring / Tetrahedron Letters 47 (2006) 4687–4692
158.9, 158.5, 156.1, 155.2, 154.2, 153.9, 150.9, 149.1, 125.2,
4J = 1.5 Hz), 7.97 (dd, 2H, 3J = 5.7 Hz, 4J = 1.3 Hz), 3.17
(s, 1H); 13C {1H} NMR (DMSO-d6 100.1 MHz): 157.6,
154.4, 151.0, 142.6, 134.8, 129.4, 126.6, 126.1, 91.9, 80.2;
UV–vis (DMF): k nm (e, Mꢀ1 cmꢀ1) = 405 (3300), 387
(3100), 360 (5500), 337 (9900), 320 (9700), 287 (19400);
FT-IR (KBr): m = 3252 (m), 3049 (m), 2911 (m), 2112 (m,
124.5, 124.3, 123.9, 123.5, 122.9, 122.6, 121.4, 30.8, 30.4,
37.9, 36.6 ppm. UV–vis (DMF): k nm (e, Mꢀ1 cmꢀ1) =
403 (8500), 334 (23,300), 323 (24,400), 287 (70,600); FT-IR
(KBr): m = 3338 (m), 2960 (m), 2122 (m, mC„C), 1614 (s),
1582 (s), 1563 (s), 1466 (s), 1392 (m), 1261 (m), 880 (m),
792 (m). ES–MS m/z 852.4 (100%, [MꢀBF4]+) in CH2Cl2.
Anal. Calcd for C44H45N6PtBF4 (Mr = 939.75): C, 56.24;
H, 4.83; N, 8.94. Found: C, 55.75; H, 4.62; N, 8.63.
m
C„C), 1605 (s), 1475 (s), 1417 (s), 1132 (s), 1019 (s), 785
(s); ES-MS m/z: 487.2 (100%, [MꢀCl]+) in DMSO. Anal.
Calcd for C17H11Cl2N3Pt (Mr = 523.27): C, 39.02; H,
2.12; N, 8.03. Found: C, 38.72; H, 1.69; N, 7.76.
18. Price, J. H.; Birk, J. P.; Wayland, B. B. Inorg. Chem. 1978,
17, 2245.
17. Compound 14. 4-ethynyl-2,6-di(pyridin-2-yl)pyridine
(40 mg, 0.15 mmol) was dissolved in THF (10 ml). cis-
[PtCl2(dmso)2] (100 mg, 0.24 mmol) was added and the
mixture heated up to 60 ꢁC for 18 h. The yellow precipitate
was filtered off and washed with THF than acetonitrile to
afford 60 mg (77%) of 14. 1H NMR (DMSO-d6
300.1 MHz): d 8.91 (d, 2 H, 3J = 5.5 Hz), 8.82 (s, 2H),
8.70 (d, 2H, 3J = 7.3 Hz), 8.53 (dd, 2H, 3J = 7.9 Hz,
19. Michalec, J. F.; Bejune, S. A.; Cuttell, D. G.; Summerton,
G. C.; Gertenbach, J. A.; Field, J. S.; Haines, R. J.;
McMillin, D. R. Inorg. Chem. 2001, 40, 2193.
20. Hill, M. G.; Bailey, J. A.; Miskowski, V. M.; Gray, H. B.
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