Carbene complexes of cycloplatinated 1H-indole-1-methyl-2-(2′-pyridine). The crystal and molecular structure of σ-{Pt[1H-indole-1-methyl-2-2′-pyridinyl-C 3,N′]-(DMSO)Cl} and of σ-{Pt[1H-indole-1-methyl-2-(2′pyridinyl-C 3,N′)][=C(OCH2CH3)(CH2C 6H5)]Cl}

Article abstract of DOI:10.1016/S0022-328X(00)00343-0

Reaction of 1-methyl-2-(2′-pyridinyl)-1H-indole (1) with PtCl₂(DMSO)₂ (DMSO = dimethylsulfoxide) gave the cycloplatinated product 2; X-ray structure determination of 2 showed a metallation to platinum via the C3 carbon of the indole nucleus, which is chelated to the metal via the pyridine nitrogen atom. Compound 2 reacts with neutral ligands such as CO, Bu^tNC, styrene and phenylacetylene, to give compounds 3-6 respectively, where DMSO is replaced by the neutral ligands. The phenylacetylene derivative 6 reacts with ethanol to give the carbene complex 7, whose X-ray structure has been determined. Related carbene complexes with other alcohols and other acetylenic derivatives have also been synthesised.

Full text of DOI:10.1016/S0022-328X(00)00343-0

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 608 (2000) 34–41
Carbene complexes of cycloplatinated
1H-indole-1-methyl-2-(2%-pyridine). The crystal and molecular
structure of s-{Pt[1H-indole-1-methyl-2-(2%-pyridinyl-C3,N%]-
(DMSO)Cl} and of s-{Pt[1H-indole-1-methyl-2-
(2%-pyridinyl-C3,N%)][ꢀC(OCH2CH3)(CH2C6H5)]Cl}
S. Tollari b,*, S. Cenini a, A. Penoni a, G. Granata a, G. Palmisano b, F. Demartin c
a Dipartimento di Chimica Inorganica, Metallorganica ed Analitica and CNR Center, Uni6ersita’ degli Studi di Milano, Via Venezian 21,
20133 Milan, Italy
b Dipartimento di Scienze Chimiche, Fisiche e Matematiche, Uni6ersita’ degli Studi dell’Insubria, Via Valleggio 11, 22100 Como, Italy
c Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Uni6ersita’ degli Studi di Milano, Via Venezian 21, 20133 Milan, Italy
Received 18 April 2000; received in revised form 26 May 2000
Abstract
Reaction of 1-methyl-2-(2%-pyridinyl)-1H-indole (1) with PtCl2(DMSO)2 (DMSO=dimethylsulfoxide) gave the cycloplatinated
product 2; X-ray structure determination of 2 showed a metallation to platinum via the C3 carbon of the indole nucleus, which
is chelated to the metal via the pyridine nitrogen atom. Compound 2 reacts with neutral ligands such as CO, ButNC, styrene and
phenylacetylene, to give compounds 3–6 respectively, where DMSO is replaced by the neutral ligands. The phenylacetylene
derivative 6 reacts with ethanol to give the carbene complex 7, whose X-ray structure has been determined. Related carbene
complexes with other alcohols and other acetylenic derivatives have also been synthesised. © 2000 Elsevier Science S.A. All rights
reserved.
Keywords: 1H-indole-1-methyl-2-(2%-pyridinyl); Ligand substitution; Platinum carbene complexes
plex gives a b-alkoxyalkenyl derivative [2,3]. It has been
argued that in this latter case, the more electrophilic
1. Introduction
nature of the reacting complex would stabilise a p-
Terminal alkynes and alkynyl ligands coordinated to
alkyne intermediate rather than a vinylidene, which
electrophilic metal centres react with alcohols to give
would explain the observed product. As part of a
(alkoxy)alkyl carbene complexes of the type
program to study the cyclometallation reactions of
LnM{ꢀC(OR¦)CH2R%} [1]. It has been pointed out re-
cently that the reactions of cationic solvento platinu-
m(II) species of the type [PtR(PPh3)2(solv)]BF4 with
terminal alkynes and alcohols are strongly influenced
indole derivatives [4], we have studied the reactions of
Pt(DMSO)2Cl2 with 1-methyl-2-(2%-pyridinyl)-1H-in-
dole (1), obtaining the {Pt[1H-indole-1-methyl-2-(2%-
pyridinyl-C3,N%](DMSO)Cl} derivative 2. The presence
by the electronic properties of the alkyl ligand present
in this complex of a chelated C,N ligand and of a labile
in the cation [2]. When alkyl is a methyl group, the
DMSO species, prompted us to investigate its reactivity
reaction leads to cationic carbene complexes of plat-
inum, whereas the corresponding trifluoromethyl com-
towards neutral ligands, in particular terminal alkynes,
and the following reactions with alcohols in order to
verify the influence of the metallated indole derivative
on the outcome of the reactions.
* Corresponding author.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00343-0

S. Tollari et al. / Journal of Organometallic Chemistry 608 (2000) 34–41
35
2. Results and discussion
When CO was bubbled into a solution of 2 in
methylene chloride at room temperature overnight, the
complex 3 was isolated by silica gel flash-chromatogra-
phy of the reaction mixture.
2.1. Cyclometallated compounds
Reaction of 1-methyl-2-(2%-pyridinyl)-1H-indole (1)
with Pt(DMSO)2Cl2 in propan-2-ol and in the presence
of AcONa, readily gave the monomeric, cycloplatinated
product 2 (Eq. (1)):
A strong and sharp absorption at 2102 cm−1 in the
IR spectrum (nujol) as well as a signal at 176.86 ppm in
the 13C-NMR spectrum indicate a terminal carbonyl
ligand. An additional absorption at 293 cm−1 in the
spectrum of 3 is consistent with a Pt–Cl bond trans to
the indole ring.
Similarly, in the IR spectrum of 4 absorptions were
observed at 2207 cm−1 (w(–NꢀC)) and 291 cm−1
(w(Pt–Cl)). The presence in complex 5 of 1H-NMR signals
for three protons at 6.39 ppm (dd, J=13.2, 7.9 Hz),
5.33 ppm (d, J=13.2 Hz) and 4.91 ppm (d, J=7.9 Hz)
and two signals at 75.02 and 94.28 ppm in the 13C-
NMR spectrum indicate the coordination of styrene to
the metal through the double bond. In compound 6 the
position of w(CꢁC) was observed at 1781 cm−1 in the IR
spectrum together with a broad absorption at 4.15 ppm
in the 1H-NMR spectrum, and signals at 64.61 and
71.64 ppm in the 13C-NMR spectrum. These data sup-
port a coordination of the 1-alkyne to platinum via the
triple bond. Finally, in compounds 5 and 6 absorptions
in the IR spectra at 291 and 298 cm−1, respectively,
confirm the presence of a Pt–Cl bond trans to the
cyclometallated indole ring.
(1)
The halogen ligand in 2 is in a trans position with
respect to the carbon s-donor, as evidenced by the low
frequency of w(Pt–Cl) at 278 cm−1 which confirms un-
equivocally the X-ray structural determination (see be-
low). When reaction (1) was conducted with
2-(2%-pyridinyl)-1H-indole, where the indole nitrogen is
not protected by the methyl group against electrophilic
attack by the metal, a monomeric h2-N,N%-bonded
2-(2%-pyridinyl)-indolyl derivative was obtained [5,6].
When the reaction of 2 with phenylacetylene was
conducted in a CH2Cl2–ethanol mixture we obtained
the platinum(II) carbene complex 7 (Eq. (3)):
(3)
Complex 2 reacts at room tempeature with neutral
ligands such as carbon monoxide and But-NC, leading
to the substitution products 3 and 4 (Eq. (2)) and
similar products with L=Ph–CHꢀCH2 (5) and L=
Ph–CꢁCH (6) have been obtained analogously in warm
CH2Cl2:
The benzyl methylene group of the alkoxy(ben-
zyl)carbene gives rise to an AB pattern (2JH–H=17.4
Hz), with only one of these protons showing coupling
to 195Pt (JPt–H=4.5 Hz) in agreement with that re-
ported in ref. [7] and this is indicative of hindered
(2)

36
S. Tollari et al. / Journal of Organometallic Chemistry 608 (2000) 34–41
Table 1
diastereotopic. The chemical shift difference between
the two methylene protons is significant (ca. 0.5 ppm),
suggesting that on average they occupy very different
magnetic environments. The presence of a singlet at
278.35 ppm in the 13C-NMR spectrum is indicative of
the presence of a PtꢀC group and, finally, the X-ray
determination confirms unequivocally the structure of
7. Attempted reactions of 6 with ethanol, in the pres-
ence of AgBF4, gave a complex mixture of products.
A series of analogous products was synthesised from
different alkynes and alcohols under the same reaction
conditions (Table 1).
When we used the (trimethylsilyl)acetylene as alkyne
we were unable to isolate the corresponding platinum
carbene derivative. The NMR spectrum of the crude
reaction mixture showed the presence of a trimethylsilyl
group, but after flash chromatography the final product
was the corresponding methyl derivative, arising from
protonolysis of the C–Si bond (products 11 and 12). In
the case of the alkynes HCꢁCC(CH3)ꢀCH2 and
HCꢁCC(CH3)2OH we obtained the same platinum car-
bene complex (15), probably via dehydration of the
initial hydroxyplatinum carbene (Eq. (4)):
Series of products synthesised under the same reaction conditions
7
8
9
10
11
12
13
14
15
16
R=ꢂC6H5
R=ꢂC6H5
R=ꢂC6H5
R=ꢂ(CH2)5CH3
R=ꢂSi(CH3)3
R=ꢂSi(CH3)3
R=ꢂ(CH2)4CꢁCH
R=ꢂC(CH3)3
R=ꢂC(CH3)ꢀCH2
R=ꢂC(CH3)2OH
R%=ꢂCH2CH3
R%=ꢂCH(CH3)2
R%=ꢂC(CH3)3
R%=ꢂCH2CH3
R%=ꢂCH2CH3
R%=ꢂCH2(CH3)14CH3
R%=ꢂCH2CH3
R%=ꢂCH2CH3
R%=ꢂCH2CH3
R%=ꢂCH2CH3
a
a
a In the platinum carbene complex R=H.
rotation about the Pt–C bond in solution. The OCH2
protons of the ethoxy–carbene complexes are
Analytical and IR data of compounds 2–15 are
shown in Table 2.
(4)
Table 2
Analytical and IR data
b
Complex
Colour
M.p. (°C)
Analysis a (%)
Yield (%)
IR nPt–Cl (cm−1
)
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Orange
197–199
185–186
143–144
\290
245–247
189–190
C 37.1 (37.2), H 3.3 (3.3), N 5.7 (5.4)
C 38.8 (38.7), H 2.5 (2.4), N 6.1 (6.0)
C 43.7 (43.8), H 3.7 (3.9), N 7.9 (8.1)
C 48.5 (48.8), H 3.4 (3.5), N 5.0 (5.2)
C 48.7 (48.9), H 3.1 (3.2), N 5.1 (5.2)
C 49.0 (49.2), H 3.9 (4.0), N 4.7 (4.8)
C 49.9 (50.0), H 4.0 (4.2), N 4.6 (4.7)
C 50.8 (50.9), H 4.3 (4.4), N 4.5 (4.6)
71
81
51
53
61
65
39
68
50
61
54
34
48
45
278
2102 c, 293
2207 d, 291
291
Yellow–orange
Yellow–orange
Orange
Orange
Orange
Orange
Orange
Orange
Yellow–orange
Yellow–orange
Orange
Yellow–orange
Orange
1781 e, 298
288
195–197 (dec)
193–195
291
293
287
292
287
291
289
291
178–179
158–159
163–165 (dec)
173–174
130–132 (dec)
C 41.9 (42.4), H 3.5 (3.8), N 5.2 (5.5)
C 54.1 (54.4), H 6.6 (6.7), N 3.8 (3.9)
C 48.3 (48.9), H 4.3 (4.6), N 4.6 (4.7)
C 46.2 (46.7), H 4.4 (4.8), N 4.7 (4.9)
C 45.2 (45.9), H 4.0 (4.2), N 5.0 (5.1)
a Given as found (required).
b Nujol mull.
c wCO
d wNC
e wCꢁC
.
.
.

S. Tollari et al. / Journal of Organometallic Chemistry 608 (2000) 34–41
37
Table 3
Crystallographic data
having an alkyne and a chelated C,N compound as
ligand. To the best of our knowledge, these are the
first examples of carbene complexes having such a
co-ligand. The isolation of compound 6 having a p-
bonded alkyne, and its easy transformation into car-
bene complexes by reaction with alcohols, seems to
exclude that the stabilisation of a p-alkyne intermedi-
ate, rather than a vinylidene, is a situation which
favours the formation of b-alkoxyalkenyl derivatives
by reaction with alcohols [2,3]. At the moment we
have no evidence that the p-alkyne intermediate
evolves to a hydride-acetylide species prior to the re-
action with alcohol, a step which seems to be essen-
tial ‘en route’ to vinylidene [8] and carbene complexes
[9].
Compound
FW (amu)
Space group
Unit cell dimensions
C16H17ClN2OPtS C24H23ClN2OPt
515.93
586.00
(
P21/c (no. 14)
P1 (no. 2)
,
a (A)
10.533(6)
16.167(8)
9.956(3)
90
94.43(3)
90
8.583(3)
9.379(2)
14.106(2)
74.82(1)
79.26(2)
78.03(2)
1061.5(5)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
1690(1)
4
F(000)
984
568
Dcalc (g cm−3
)
2.027
85.85
ꢀ
1.833
67.53
v(Mo–Ka) (cm−1
)
Scan mode
ꢀ
Scan speed (° min−1
Scan width (°)
q range (°)
)
2–3
2–3
2.2. Crystal structure determination of 2 and 7
1.8+0.350 tan q
3–25
1.0+0.35 tan q
3–23
Independent reflections
Observed reflections
[I\2|(I)]
2969
1827
2584
1881
A summary of the crystallographic data and details
of the refinement procedure are given in Table 3. In-
tensity data were collected on a Enraf–Nonius CAD4
diffractometer with graphite-monochromated Mo–Ka
radiation. Lorentz, polarisation and an empirical ab-
sorption correction [11] were applied to the data.
Both structures were solved by Patterson and Fourier
methods and refined with full-matrix least-squares
Transmission factors
Parameters refined
0.36–1.00
199
0.55–1.00
262
0.045, 0.106
1.85, −1.61
Final R and wR2 indices a 0.060, 0.144
Largest difference peak
1.95, −1.14
−3
,
and hole (e A
)
a R=[ꢀ(Fo−kꢁFcꢁ)/ꢀFo], wR2=[ꢀw(Fo2−kꢁFcꢁ ) /ꢀw(F2o)2]1/2
2 2
.
(SHELX-93) [12]. Anisotropic displacement parameters
were assigned to all non-hydrogen atoms. Hydrogens
were riding on their carbon atoms.
In conclusion, a series of carbene complexes of
platinum(II) can be easily obtained from a precursor
Fig. 1. A perspective view of compound 2. Hydrogen atoms have been omitted for clarity.

38
S. Tollari et al. / Journal of Organometallic Chemistry 608 (2000) 34–41
Table 4
dimethylsulfoxide molecule respectively trans to the in-
dolic C8 (C3 atom in indole ring) and pyridinic N1
atoms of the ligand; the metal atom is essentially in the
,
Selected interatomic distances (A) and angles (°) for compound 2
Pt–Cl
Pt–S
Pt–N1
Pt–C8
S–O
2.398(5)
2.207(5)
Cl–Pt–S
Cl–Pt–N1
Cl–Pt–C8
S–Pt–N1
91.6(2)
93.2(4)
172.9(4)
175.1(4)
95.4(5)
,
coordination plane (0.006(1) A out of the plane). The
2.063(16)
2.038(14)
1.465(14)
1.728(21)
1.796(21)
1.378(25)
1.345(24)
1.388(22)
1.391(22)
1.373(29)
1.409(31)
1.362(29)
1.431(28)
1.451(25)
1.382(24)
1.404(21)
1.437(24)
platinum environment can be compared with that
found in
a similar indole-fused platinacycle, s-
S–Pt–C8
[Pt(C8H4NHCH2NMe2)(DMSO)Cl] [4]. Here a Pt–N1
S–C1s
S–C2s
N1–C2
N1–C6
N11–C7
N11–C10
C2–C3
C3–C4
C4–C5
C5–C6
C6–C7
C7–C8
C8–C9
C9–C10
N1–Pt–C8
Pt–N1–C2
Pt–N1–C6
C2–N1–C6
C7–N11–C10
C7–N11–C12
C10–N11–C12
N1–C6–C5
N1–C6–C7
C5–C6–C7
N11–C7–C6
N11–C7–C8
C6–C7–C8
Pt–C8–C7
79.7(6)
,
,
distance of 2.063(16) A with respect to 2.124(5) A in
s-[Pt(C8H4NHCH2NMe2)(DMSO)Cl] is observed; this
shortening is probably due to p-back donation from the
metal to the pyridinic moiety, which is absent in the
case of the aminic nitrogen atom. Accordingly, the
Pt–S distance is slightly but significantly elongated,
124.7(12)
117.0(12)
118.2(16)
106.6(14)
130.5(15)
122.9(15)
121.5(18)
111.6(15)
127.0(16)
128.0(16)
112.3(15)
119.5(16)
111.9(11)
143.0(12)
105.0(14)
108.9(14)
133.9(15)
117.2(15)
107.0(14)
129.1(16)
123.9(16)
,
2.207(5) versus 2.180(2) A. The Pt–Cl distance is the
,
same in both compounds (2.398(4) and 2.394(2) A),
whereas an elongation of the Pt–C interaction is ob-
,
served here (2.038(14) versus 1.973(7) A) probably due
to electron withdrawing performed by the pyridinic
ring, which renders the electron pair on C8 (C3 atom in
the 1-methyl-2-(2%-pyridinyl)-1H-indole ring) less avail-
able, as well as to the conformational rigidity of the
Pt–C8–C9
C7–C8–C9
C8–C9–C10
C8–C9–C13
C10–C9–C13
N11–C10–C9
N11–C10–C16
C9–C10–C16
,
two different moieties. The metal atom is 0.020(1) A
out of the platinacycle ring. All the rings of the
pyridinyl-indolyl ligand are planar within experimental
error; the torsion angle C8–C7–C6–N1 (respectively
C3, C2, C2% and N1 atoms in the 1-methyl-2-(2%-
pyridinyl)-1H-indole ring) is 5.6(24)°.
2.3. Structure of compound 2
A perspective view of compound 2 is shown in Fig. 1.
Selected interatomic distances and angles are reported
in Table 4. The complex contains a Pt atom in square
planar coordination surrounded by a chloride ion and a
2.4. Structure of compound 7
A perspective view of compound 7 is shown in Fig. 2.
Selected interatomic distances and angles are reported
Fig. 2. A perspective view of compound 7. Hydrogen atoms have been omitted for clarity.

S. Tollari et al. / Journal of Organometallic Chemistry 608 (2000) 34–41
39
Table 5
Selected interatomic distances (A) and angles (°) for compound 7
ligand. The geometrical features of the indolic ligand
are very similar to those found in complex 2.
,
Pt–Cl
Pt–C20
Pt–N1
2.370(5)
Cl–Pt–C20
Cl–Pt–N1
Cl–Pt–C8
C20–Pt–N1
C20–Pt–C8
N1–Pt–C8
87.2(5)
93.9(4)
171.8(5)
177.8(5)
100.8(6)
78.2(5)
124.0(11)
115.9(8)
1.869(14)
2.120(11)
1.977(15)
1.322(23)
1.449(34)
1.501(26)
1.326(28)
1.357(17)
1.375(20)
1.353(23)
1.388(29)
1.372(28)
1.345(26)
1.392(19)
1.426(21)
1.377(18)
1.428(25)
1.397(23)
3. Experimental
Pt–C8
C20–O19
O19–C18
C20–C21
N1–C2
N1–C6
N11–C7
N11–C10
C2–C3
C3–C4
C4–C5
C5–C6
C6–C7
C7–C8
C8–C9
C9–C10
3.1. General
Pt–N1–C2
Pt–N1–C6
All reactions were carried out under a dinitrogen
atmosphere. All starting materials were used as re-
ceived. Compound 1 was prepared according to a liter-
ature procedure [10]. IR: Perkin–Elmer 1310, Nicolet
MX-1FTIR. MS: VG 7070/EQ (70 eV). MR: Varian
XL-200 (200 MHz and 50.3 MHz, for 1H and 13C,
C2–N1–C6
C7–N11–C10
C7–N11–C12
C10–N11–C12
N1–C6–C5
N1–C6–C7
C5–C6–C7
N11–C7–C6
N11–C7–C8
C6–C7–C8
Pt–C8–C7
119.9(15)
106.3(16)
127.4(13)
126.0(13)
118.6(12)
111.1(14)
130.3(13)
129.3(16)
111.6(12)
119.1(13)
115.7(10)
139.2(15)
105.2(13)
106.5(17)
135.4(18)
118.1(14)
110.4(14)
127.1(21)
122.4(20)
127.0(12)
125.1(10)
107.8(15)
1
respectively). For H- and 13C-NMR, CDCl3 was used
as solvent, and TMS as internal standard.
3.2. |-{Pt[1H-1-methyl-2-(2%-pyridinyl)-
indolyl-C3,N%](DMSO)Cl} (2)
Pt–C8–C9
C7–C8–C9
C8–C9–C10
C8–C9–C13
C10–C9–C13
N11–C10–C9
N11–C10–C16
C9–C10–C16
Pt–C20–O19
Pt–C20–C21
O19–C20–C21
208 mg of 1 (1×10−3 mol) were suspended in 10 ml
of degassed propan-2-ol under dinitrogen and 422 mg
of Pt(DMSO)2Cl2 (1×10−3 mol) with 80 mg (1×10−3
mol) of sodium acetate were added. The reaction was
refluxed for 1 h. The solution became orange and after
cooling to room temperature an orange product 2
precipitated. It was filtered off, washed with propan-2-
1
ol (3×5 ml), then dried in vacuo. H-NMR l (ppm):
3.52 (s, 3H, S–CH3, JPt–H=22), 3.85 (s, 3H, N–CH3),
7.01–8.05 (m, 7H, aromatic), 9.56 (dt, 1H, H-6%,
J
H–H=7.2, JPt–H=40). 13C-NMR l (ppm): 32.56,
in Table 5. The structure of complex 7 contains a Pt
atom in square planar coordination surrounded by a
chloride ion and the alkoxy(benzyl)carbene ligand re-
spectively trans to indolic C8 (C3 atom in the 1-methyl-
2-(2%-pyridinyl)-1H-indole ring) and the pyridinic N1 of
the ligand; the metal atom is essentially in the coordina-
tion plane. The orientation of the carbene ligand
around the Pt–C20 bond is similar to that generally
found in other platinum complexes containing non-
chelating carbene ligands with the C8–Pt–C20–O19
torsion angle of −70.4(16)°. The values of the bond
distances and angles within the carbene moiety are very
similar to those found in cis-[PtCl2-(PMe2Ph)(C(OEt)-
(CH2Ph))] [13].The C20–C21 and O19–C18 distances
are indicative of single bond character and that for the
C20–O19 interaction shows double bond character; the
ligand displays a trans arrangement about the C20–
O19 bond, the C21–C20–O19–C18 torsion angle being
48.75 (JPt–C=63), 109.98, 118.01, 121.01, 124.69,
125.13, 125.36, 127.65, 130.25, 137.98, 141.37, 150.79,
154.03, 157.12.
3.3. |-{Pt[1H-1-methyl-2-(2%-pyridinyl)-indolyl-
C3,N%](CO)Cl} (3)
129 mg (0.25×10−3 mol) of 2 dissolved in 20 ml of
dichloromethane were carbonylated under magnetic
stirring, overnight at room temperature with CO at
atmospheric pressure in the presence of 0.2 ml of
triethylamine. The solution became red and the solvent
was evaporated to dryness. The residue was purified on
silica gel column eluting with dichloromethane–chloro-
1
form (2:8). H-NMR l (ppm): 3.98 (s, 3H, N–CH3),
6.89–7.85 (m, 7H, aromatic), 9.49 (dt, 1H, H-6%, JH–H
=7.2, JPt–H=40). 13C-NMR l (ppm): 32.11, 110.7,
121.11, 124.19, 124.93, 125.66, 128.65, 131.55, 137.78,
141.01, 142.36, 150.71, 153.93, 156.18, 176.86 (CO).
,
178.8(17)°. The Pt–C20 bond length (1.869(14) A) is
substantially in line with the corresponding distances
found in analogous complexes, where values in the
3.4. |-{Pt[1H-1-methyl-2-(2%-pyridinyl)-indolyl-
C3,N%](ButNC)Cl} (4)
,
range 1.92–2.02 A have been observed, according to
the different extent of Pt“C backbonding. The Pt–N1
distance is significantly longer than that found in com-
plex 2 due to the different trans influence of the carbene
To a solution of 154 mg (0.3×10−3 mol) of 2 in 20
ml of dichloromethane under dinitrogen, were added 34

40
S. Tollari et al. / Journal of Organometallic Chemistry 608 (2000) 34–41
mg (0.4×10−3 mol) of tert-butyl isocyanide. The solu-
tion became deep-orange and was stirred at room tem-
perature for 2 h. The solvent was evaporated to dryness
and the residue was purified on silica gel column eluting
1H-NMR, 13C-NMR and MS spectra data for the
compounds obtained are as follows.
7. 1H-NMR l (ppm): 1.22 (t, 3H, OCH2CH3), 4.04 (s,
3H, N–CH3), 4.54 (d, 1H, Pt–CꢀCH2–Ph, JH–H
=
with dichloromethane. 1H-NMR
l
(ppm): 1.71
17.4), 4.68 (dt, 1H, Pt–CꢀCH2–Ph, H–H=17.4,
J
(s,9H,C–CH3), 4.02 (s, 3H, N–CH3), 6.82–7.85 (m,
JH–Pt=4.5), 5.25 (dq, 1H, OCH2–CH3, JH–H=10.4,
JH–Pt=7.2), 5.61 (dq, 1H, OCH2–CH3, JH–H=10.4,
JH–Pt=7.2), 6.75–7.75 (m, 12H, aromatic), 9.38 (dt,
7H, aromatic), 9.51 (dt, 1H, H-6%, JH–H=7.1, JPt–H
=
40). 13C-NMR l (ppm): 30.94, 31.32, 32.38, 117.34,
119.85, 120.36, 123.65, 124.61, 131.45, 140.99, 142.1,
144.53, 151.18, 153.41, 155.8.
1H, H-6%, JH–H=8.2, JPt–H=14.7). 13C-NMR l (ppm):
14.41, 32.54, 64.21 (JC–Pt=52), 82.37 (JC–Pt=58),
110.06, 117.01, 119.27, 119.92, 120.43, 122.53, 124.06,
127.52, 128.85, 130.9, 131.9, 133.83, 139.88, 141.34,
144.21, 150.23, 156.37, 278.35 (PtꢀC). MS m/z (%): 586
(25), 466 (34), 438 (100), 430 (32), 401 (45), 386 (65), 206
(54), 130 (22), 91 (13).
3.5. |-{Pt[1H-1-methyl-2-(2%-pyridinyl)-indolyl-
C3,N%](C6H5–CHꢀCH2)Cl} (5)
To a stirred solution of 154 mg (0.3×10−3 mol) of
2 in 20 ml of dichloromethane under dinitrogen, were
added 42 mg (0.4×10−3 mol) of styrene. The solution
was refluxed under stirring for 2 h and gave an orange
solution. The solvent was evaporated to dryness and
the residue was purified on silica gel column eluting
1
8. H-NMR l (ppm): 1.37 (d, 3H, OCH(CH3)2), 1.64
(d, 3H, OCH(CH3)2), 4.03 (s, 3H, N–CH3), 4.51 (d,
1H, Pt–CꢀCH2–Ph, JH–H=17.4), 4.61 (dt, 1H, Pt–
CꢀCH2–Ph, JH–H=17.4, JH–Pt=4.5), 6.54 (sept, 1H,
OCH(CH3)2), 6.75–7.75 (m, 12H, aromatic), 9.38 (dt,
1H, H-6%, JH–H=8.6, JPt–H=14.7). 13C-NMR l (ppm):
21.09, 22.05, 32.04, 68.81 (JC–Pt=52), 91.9 (JC–Pt=58),
109.76, 117.71, 119.27,119.9, 120.43, 122.53, 123.96,
127.13, 128.55, 130.55, 130.91, 133.53, 139.48, 141.01,
144.11, 149.22, 156.18, 277.28 (PtꢀC). MS m/z (%): 466
(41), 438 (91), 414 (100), 401 (41), 386 (51), 372 (43), 207
(24), 130 (22).
1
with dichloromethane. H-NMR l (ppm): 3.95 (s, 3H,
N–CH3), 4.91 (d, 1H,=CH, J=7.9), 5.33 (d, 1H,=
CH, J=13.3), 6.39 (dd, 1H, ꢀCH, J=7.9, 13.2), 7.65–
8.01 (m, 12H, aromatic), 9.49 (dt, 1H, H-6%, JH–H=7.2,
J
Pt–H=40). 13C-NMR l (ppm): 31.04, 75.02, 94.28,
110.45, 117.24, 120.46, 120.72, 122.55, 124.31, 127.96,
129.19, 131.18, 132.33, 132.77, 134.03, 140.14, 141.6,
143.25, 150.48, 156.78.
1
9. H-NMR l (ppm): 1.55 (s, 9H, OC (CH3)3), 4.04
3.6. |-{Pt[1H-1-methyl-2-(2%-pyridinyl)-indolyl-
C3,N%](C6H5–CHꢁCH)Cl} (6)
(s, 3H, N–CH3), 4.61 (d, 1H, Pt–CꢀCH2–Ph, JH–H
17.3), 4.69 (dt, 1H, Pt–CꢀCH2–Ph, H–H=17.3,
H–Pt=4.4), 6.75–7.75 (m, 12H, aromatic), 9.38 (dt,
=
J
J
To a stirred solution of 154 mg (0.3×10−3 mol) of
2 in 20 ml of dichloromethane under dinitrogen, were
added 41 mg (0.4×10−3 mol) of phenylacetylene. The
solution was refluxed under stirring for 2 h. The solvent
was evaporated to dryness and the residue was purified
1H, H-6%, JH–H=8.4, JPt–H=14.7). 13C-NMR l (ppm):
20.03, 32.04, 68.81 (JC–Pt=52), 92.01 (JC–Pt=57),
109.21, 118.01, 119.21,119.87, 120.15, 122.21, 124.01,
127.32, 128.05, 130.75, 134.11, 133.53, 139.02, 141.05,
144.32, 149.01, 156.28, 279.12 (PtꢀC). MS m/z (%): 614
(83), 557 (100), 549 (48), 466 (91), 430 (80), 401 (41), 386
(51), 209 (33), 131 (25).
1
on silica gel column eluting with dichloromethane. H-
NMR l (ppm): 3.98 (s, 3H, N–CH3), 4.15 (brs, 1H,
ꢁCH), 6.78–7.98 (m, 12H, aromatic), 9.45 (dt, 1H,
H-6%, JH–H=7.3, JPt–H=40). 13C-NMR l (ppm):
32.51, 64.61, 71.64, 110.34, 117.31, 120.36, 120.75,
122.51, 124.41, 127.91, 129.21, 131.21, 132.25, 132.74,
133.92, 140.24, 141.58, 143.21, 150.51, 156.65.
1
10. H-NMR l (ppm): 0.95 (t, 3H, –(CH2)5–CH3),
1.27 (m, 10H, –(CH2)5–CH3), 1.62 (t, 3H, OCH2CH3),
3.15 (t, 1H, PtꢀCCH2–(CH2)5–CH3, JH–H=17.1), 3.19
(t, 1H, PtꢀCCH2–(CH2)5–CH3, JH–H=17.1), 4.05 (s,
3H, N–CH3), 5.38 (dq, 1H, OCH2–CH3, JH–H=10.2,
J
J
H–Pt=7.4), 5.58 (dq, 1H, OCH2–CH3, JH–H=10.2,
H–Pt=7.4), 6.75–7.75 (m, 7H, aromatic), 9.46 (dt, 1H,
3.7. General synthesis of cyclometallated platinum(II)
carbenes (7–15)
H-6%, JH–H=8.5, JPt–H=14.6). 13C-NMR l (ppm):
13.34, 14.31, 26.48, 32.04, 36.23, 37.18, 38.7, 63.98
(JC–Pt=52), 109.91, 118.32, 124.12, 125.13, 125.34,
128.45, 129.43, 138.91, 141.22, 151.33, 154.33, 156.92,
276.38 (PtꢀC). MS m/z (%): 594 (66), 512 (100), 466 (91),
437 (22), 386 (45), 332 (24), 207 (13), 130 (48).
To a stirred solution of 0.3×10−3 mol of 6 in 10 ml
of dichloromethane–alcohol (1:1) under dinitrogen,
were added (0.9×10−3 mol) of the corresponding
alkyne. The solution was stirred for 2–10 h until start-
ing material disappeared in TLC (eluent CH2Cl2–hex-
ane). The solvent was evaporated to dryness and the
residue was purified on silica gel column eluting with
the same eluent.
11. 1H-NMR l (ppm): 1.21 (t, 3H, OCH2–CH3), 2.99
(t, 3H, PtꢀC–CH3, JH–Pt=13.2), 4.02 (s, 3H, N–CH3),
5.37 (dq, 1H, OCH2–CH3, JH–H=10.2, JH–Pt=7.3),

S. Tollari et al. / Journal of Organometallic Chemistry 608 (2000) 34–41
41
5.41 (dq, 1H, OCH2–CH3, JH–H=10.2, JH–Pt=7.3),
6.81–7.77 (m, 7H, aromatic), 9.39 (dt, 1H, H-6%, JH–H
124.22, 125.23, 128.42, 129.66, 138.93, 139.07, 150.12,
151.43, 156.02, 271.31 (PtꢀC). MS m/z (%): 550 (37), 513
(27), 484 (32), 466 (100), 430 (31), 401 (57), 208 (26), 130
(68).
=
8.2, JPt–H=14.1). 13C-NMR l (ppm): 15.32, 26.91,
33.15, 64.21 (JC–Pt=52), 110.67, 120.31, 124.46, 125.01,
125.93, 128.91, 131.42, 136.68, 141.51, 142.06, 150.22,
154.05, 155.97, 276.38 (PtꢀC). MS m/z (%): 509 (42), 466
(100), 438 (41), 430 (23), 414 (31), 401 (13), 387 (45), 207
(24), 130 (29).
4. Supplementary material
1
12. H-NMR l (ppm): 0.94 (t, 3H, OCH2–(CH2)14–
Tables giving details of the data collection and refin-
ement, atomic coordinates, displacement parameters,
bond lengths and angles have been deposited at the
Cambridge Crystallographic Data Centre, CCDC nos.
142060 and 142061. Copies of this information may be
obtained free of charge from The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (Fax: +44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
CH3), 1.26 (m, 28H, OCH2–(CH2)14–CH3), 2.98 (t, 3H,
PtꢀC–CH3, JH–Pt=13.4), 4.08 (s, 3H, N–CH3), 5.34
(dq, 1H, OCH2–(CH2)14–CH3, JH–H=10.3, JH–Pt
7.1), 5.49 (dq, 1H, OCH2–(CH2)14–CH3, JH–H=10.3,
H–Pt=7.1), 6.81–7.71 (m, 7H, aromatic), 9.39 (dt, 1H,
=
J
H-6%, JH–H=8.2, JPt–H=14.1). 13C-NMR l (ppm): 15.8,
23.08, 26.14, 28.94, 29.54, 29.79, 30.06, 32.36, 45.66,
64.35 (JC–Pt=52), 110.13, 116.99, 120.03, 120.42, 122.27,
124.11, 132.01, 139.84, 141.41, 150.14, 156.37, 275.8
(PtꢀC). MS m/z (%): 706 (53), 466 (100), 444 (22), 430
(32), 401 (23), 386 (41), 206 (31), 130 (26).
Acknowledgements
1
13. H-NMR l (ppm): 1.27 (m, 8H CCH2–(CH2)4–
CꢁCH), 1.62 (t, 3H, OCH2CH3), 3.17 (t, 1H, PtꢀCCH2–
(CH2)4–CꢁCH, JH–H=17.1), 3.19 (t, 1H,, PtꢀCCH2–
(CH2)4 –CꢁCH, JH–H=17.1), 3.84 (s,1H, CCH2–
(CH2)4–CꢁCH), 4.1 (s, 3H, N–CH3), 5.48 (dq, 1H,
OCH2–CH3, JH–H=10.2, JH–Pt=7.4), 5.61 (dq, 1H,
OCH2–CH3, JH–H=10.2, JH–Pt=7.4), 6.81–7.79 (m,
Thanks are due to MURST (ex 40%) for financial
support.
References
7H, aromatic), 9.41 (dt, 1H, H-6%, JH–H=8.5, JPt–H
=
[1] M.I. Bruce, Chem. Rev. 91 (1991) 97 and refs. therein.
[2] V. Belluco, R. Bertani, S. Fornasiero, R.A. Michelin, M. Moz-
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[3] R.A. Michelin, M. Mozzon, B. Vialetto, R. Bertani, G. Bandoli,
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[5] (a) S. Tollari, G. Palmisano, F. Demartin, S. Cenini, unpub-
lished results. (b) The X-ray structural determination of this
compound confirmed an h2-N,N%-coordination of the organic
ligand, giving an indolato derivative. In a previous work, where
the catalytic synthesis of indoles from the carbonylation of
ortho-nitrostyrenes catalysed by Rh6(CO)16 has been investi-
gated, a complex of formula Rh(CO)2(indolato) with this type of
coordination was isolated and characterised by X-rays [6].
[6] C. Crotti, S. Cenini, B. Rindone, S. Tollari, F. Demartin, J.
Chem. Soc. Chem. Commun. (1988) 784.
14.6). 13C-NMR l (ppm): 14.31, 26.48, 32.04, 36.23,
37.18, 38.7, 44.13, 46,18, 63.98 (JC–Pt=52), 109.91,
118.32, 124.12, 125.13, 125.34, 128.45, 129.43, 138.91,
141.22, 151.33, 154.33, 156.92, 276.38 (PtꢀC). MS m/z
(%): 466 (100), 436 (34), 386 (57), 207 (21), 130 (41).
1
14. H-NMR l (ppm): 1.21 (s, 9H C(CH3)3), 1.67 (t,
3H, OCH2CH3), 2.98 (d, 1H, PtꢀCCH2–C(CH2)3,
J
H–H=16.1), 3.60 (t, 1H, PtꢀCCH2–C(CH2)3, JH–H
=
16.4), 4.04 (s, 3H, N–CH3), 5.49(dq, 1H, OCH2–CH3,
J
J
H–H=10.4, JH–Pt=7.2), 5.51 (dq, 1H, OCH2–CH3,
H–H=10.4, JH–Pt=7.2), 6.71–7.79 (m, 7H, aromatic),
9.38 (dt, 1H, H–6%, JH–H=8.9, JPt–H=14.7). 13C-NMR
l (ppm): 14.71, 32.4, 33.91, 71.25, 82.19 (JC–Pt=51),
110.14, 116.99, 118.32, 123.99, 124.12, 125.34, 128.45,
129.43, 138.81, 141.02, 151.33, 153.63, 156.52, 275.18
(PtꢀC). MS m/z (%): 566 (53), 530 (67), 514 (56), 466
(100), 438 (29), 430 (45), 401 (54), 387 (51), 207 (16), 130
(45).
[7] R.J. Cross, M.F. Davidson, M. Rocamora, J. Chem. Soc. Dal-
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[8] E. Perez-Carren˜o, P. Paoli, A. Ienco, C. Mealli, Eur. J. Inorg.
Chem. (1999) 1315.
[9] C. Bianchini, N. Mantovani, A. Marchi, L. Marvelli, D. Masi,
M. Peruzzini, M. Rossi, A. Romerosa, Organometallics 18
(1999) 4501.
1
15. H-NMR l (ppm): 1.63 (t, 3H, OCH2CH3), 1.96
(s, 3H, –C(CH3)ꢀCH2), 3.87 (d, 1H, –CH2C(CH3)ꢀCH2,
JH–H=7.8), 3.98 (d, 1H, –CH2C(CH3)ꢀCH2, JH–H=
7.8), 4.06 (s, 3H, N–CH3), 5.03 (s, 1H, –C(CH3)ꢀCH2),
5.28 (s, 1H, –C(CH3)ꢀCH2), 5.38 (dq, 1H, OCH2–CH3,
[10] J. Herbich, C.-Y. Hung, R.P. Thummel, J. Waluk, J. Am. Chem.
Soc. 118 (1996) 3508.
[11] A.C.T. North, D.C. Phillips, F.S. Mathews, Acta Crystallogr.
Sect. A 24 (1968) 351.
[12] G.M. Sheldrick, SHELX93, Program for the refinement of crystal
structure, University of Go¨ttingen, Germany, 1993.
[13] G.K. Anderson, R.J. Cross, L. Manojlovic-Muir, K.W. Muir,
R.A. Wales, J. Chem. Soc. Dalton Trans. (1979) 684.
J
H–H=10.4, JH–Pt=7.2), 5.51 (dq, 1H, OCH2–CH3,
H–H=10.4, JH–Pt=7.2), 6.99–7.77 (m, 7H, aromatic),
J
9.38 (dt, 1H, H-6%, JH–H=8.7, JPt–H=14.7). 13C-NMR
l (ppm): 14.56, 21.89, 33.87, 64.21 (JC–Pt=48), 78.19
(JC–Pt=51), 109.21, 110.21, 117.0, 118.03, 123.79,