Syntheses of platinum(II) complexes of cyclo-octenyl group and isolation of a self-assembled oxo-bridged macrocyclic complex [Pt4(Spy) 4(C8H12-O-C8H12) 2

Article abstract of DOI:10.1016/j.jorganchem.2011.07.025

Reactions of [Pt₂(μ-Cl)₂(C₈H ₁₂OMe)₂ (1) (C₈H₁₂OMe = 8-methoxy-cyclooct-4-ene-1-yl) with various anionic chalcogenolate ligands have been investigated. The reaction of 1 with Pb(Spy)₂ (HSpy = pyridine-2-thiol) yielded a binuclear complex [Pt₂(Spy) ₂(C₈H₁₂OMe)₂ (2). A trinuclear complex [Pt₃(Spy)₄(C₈H₁₂OMe) ₂ (3) was isolated by a reaction between 2 and [Pt(Spy) _2n. The reaction of 1 with HSpy in the presence of NaOMe generated 2 and its demethylated oxo-bridged tetranuclear complex [Pt ₄(Spy)₄(C₈H₁₂-O-C₈H ₁₂)₂ (4). Treatment of 1 with ammonium diisopropyldithiophosphate completely replaced C₈H₁₂OMe resulting in [Pt(S₂P{OPrⁱ}₂)₂ (5), whereas non-rigid 5-membered chelating ligand, Me₂NCH ₂CH₂E^-, produced mononuclear complexes [Pt(ECH₂CH₂NMe₂)(C₈H ₁₂OMe) (E = S (6), Se (7)). These complexes have been characterized by elemental analyses, NMR (¹H, ¹³C{¹H}, ¹⁹⁵Pt{¹H}) and absorption spectroscopy. Molecular structures of 2, 3, 4, 5 and 7 were established by single crystal X-ray diffraction analyses. Thermolysis of 2, 6 and 7 in HDA gave platinum nanoparticles.

Full text of DOI:10.1016/j.jorganchem.2011.07.025

Journal of Organometallic Chemistry 696 (2011) 3491e3498
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Syntheses of platinum(II) complexes of cyclo-octenyl group and isolation
of a self-assembled oxo-bridged macrocyclic complex [Pt (Spy) (C H -O-C H ) ]
4
4
8 12
8 12 2
*
*
Ninad Ghavale, Sandip Dey , Amey Wadawale, Vimal K. Jain
Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 July 2011
Received in revised form
Reactions of [Pt2(
m
-Cl) (C H OMe) ] (1) (C H OMe ¼ 8-methoxy-cyclooct-4-ene-1-yl) with various
2
8
12
2
8 12
anionic chalcogenolate ligands have been investigated. The reaction of 1 with Pb(Spy)
2
(HSpy ¼ pyridine-
] (2). A trinuclear complex [Pt (Spy) (-
] (3) was isolated by a reaction between 2 and [Pt(Spy) . The reaction of 1 with HSpy in the
(Spy) (C
8 12 2
H ) ] (4). Treatment of 1 with ammonium diisopropyldithiophosphate completely replaced
2
C
-thiol) yielded a binuclear complex [Pt
12OMe)
2
(Spy)
2
(C
8
H12OMe)
2
3
4
12 July 2011
8
H
2
2 n
]
Accepted 20 July 2011
presence of NaOMe generated 2 and its demethylated oxo-bridged tetranuclear complex [Pt
O-C
4
4
8 12
H -
Keywords:
Platinum
i
C
CH
8
H
12OMe resulting in [Pt(S
2
P{OPr }
2
)
2
] (5), whereas non-rigid 5-membered chelating ligand, Me
2 2-
NCH
ꢀ
2
E , produced mononuclear complexes [Pt(ECH
2
CH NMe )(C
2
2
8
H
12OMe)] (E ¼ S (6), Se (7)). These
8-Methoxy-cyclooct-4-ene-1-yl
1
13
1
195
1
complexes have been characterized by elemental analyses, NMR ( H, C{ H},
Pt{ H}) and absorption
Cyclometalation
Pyridine-2-thiolate
spectroscopy. Molecular structures of 2, 3, 4, 5 and 7 were established by single crystal X-ray diffraction
analyses. Thermolysis of 2, 6 and 7 in HDA gave platinum nanoparticles.
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
nature of L (N or P) and the size of the metalacycle greatly influ-
enced the reactivity as well as the structural features of the
The chemistry of cyclometalated palladium and platinum
complexes has been extensively explored for about five decades.
There are several obvious reasons for this sustained interest as
these complexes find numerous applications in many fields such as
organic synthesis [1e3], metallomesogens [4e6], solar cells [7,8],
opto-electronic devices [9e11] and materials science [12e14], etc.
resulting complex. In pursuance of our work on cyclometalated
platinum complexes and development of platinum group metal
chalcogenolates as precursors for the synthesis of platinum group
metal chalcogenides [19,20], we have chosen a precursor with
a very large metalacycle ring (6-membered) and a weak L ligand (
p-
olefinic group) as in [Pt -Cl) (C 12OMe) ] and explored its
2
(
m
2
8
H
2
Platinum complexes such as [Pt
14] and PtMe
used to prepare platinum thin films and nanoparticles.
2
(
m
-OR)
2
(C
8
H
12OMe)
2
] (R ¼ Me, Ac)
reactions with a variety of chalcogenolate ligands. The results of
this work are reported herein.
[
2
(COD) (COD ¼ cycloocta-diene) [15,16] have been
Cyclometalated binuclear palladium and platinum complexes
2
. Experimental
X
[M
2
(
m
-X)
2
(L C)
2
] (M ¼ Pd or Pt; X ¼ Cl or OAc; L ¼ N, P, etc.),
undergo a wide range of reactions. These can broadly be clubbed
into (i) bridge cleavage reactions by neutral donor ligands; (ii)
reaction at the metalecarbon bond, and (iii) substitution of the
bridging Cl/OAc with another ionic ligand. The latter reaction yields
a myriad of complexes. Structure of the resulting complex is gov-
erned by the nature of L, metal atom and the incoming anionic
2.1. General procedures
Solvents were dried and distilled prior to use by standard
methods. All reactions were carried out in Schlenk flasks under
nitrogen atmosphere. The compounds 2-mercaptopyridine
HSpy), Me NCH CH SH∙HCl and other reagents were procured
from commercial sources. The compounds, (Me
PtCl [22], PtCl (COD) [23] and [Pt -Cl) (C
a
(
2
2
2
ligand. Recently we have described reactions of [Pt
Cl) PC(Me )CH ] [17] and [Pt -Cl) (ppy)
{But
] (ppy ¼ meta-
lated 2-phenylpyridine) [18] with a variety of anionic ligands. The
2
(m-
2
NCH
H12OMe)
2
CH
2
Se)
] (1) [24]
2
[21],
2
2
2
2
}
2
2
(m
2
2
K
2
4
2
2
(m
2
8
2
were prepared according to the literature methods. Syntheses
and analytical data for [Pb(Spy) ] and [Pt(Spy) ] are given in
Supplementary information, Fig. S2.
2
2
Melting points were determined in capillary tubes and are
uncorrected. Elemental analyses were carried out on a Carlo-Erba
*
Corresponding authors. Tel.: þ91 22 25592589; fax: þ91 22 25505151.
E-mail address: dsandip@barc.gov.in (S. Dey).
0
022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.07.025

3492
N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498
EA-1110 CHN-O instrument. Electronic spectra were recorded on
a Chemito Spectrascan UV 2600 spectrophotometer. Mass spectra
were recorded on a Waters Q-TOF micro (YA-105) time of flight
stirred. After 30 min, benzene solution (10 mL) of [Pt
2 2
(Spy) (-
C
8
H
12OMe) ] (0.060 g, 0.067 mmol), was added and the contents
2
were further stirred for 3 h. The reaction mixture was dried by
evaporating the solvents under vacuum, washed with ether
(2 ꢂ 2 mL) and hexane (2 ꢂ 2 mL), and extracted from dichloro-
methane. The latter on volume reduction to 3 mL followed by
refrigeration gave reddish solid of 3 (0.043 g, 0.032 mmol, 48%), m.p.
mass spectrometer. 1H, C{ H}, P{ H}, Se{ H} and
13
1
31
1
77
1
195
Pt{ H}
1
NMR spectra were recorded on a Bruker Avance II-300 NMR spec-
trometer operating at 300, 75.47, 121.5, 57.24 and 64.29 MHz,
respectively. Chemical shifts are relative to internal chloroform
peak (
d
7.26 1H and 77.0 for C), external Me
13
2
Se for Se{ H}
463 ppm) and Na PtCl in
Pt{ H}. TG curves were obtained at a heating rate of
77
1
145 C. Anal. Calcd. for C38
ꢁ
H
46
N
4
O
2
Pt
3
S
4
: C, 35.0; H, 3.5; N, 4.3; S, 9.8.
Cl ): 275
(21,000), 297 nm (16,000 M cm ); H NMR (300 MHz, CDCl ):
¼ 8.46, 8.35 (br m, 4H, H-6), 7.63 (br s, 4H, H-4), 7.15 (m, 4H, H-5),
(
secondary reference Ph
2
Se
2
in CDCl
3
d
2
6
Found: C, 34.8; H, 3.5; N, 4.3; S, 9.2%; UV/Vis (CH
2
2
)
l
max
(
3
195
1
ꢀ1
ꢀ1
1
D
1
2
O for
3
ꢁ
ꢀ
1
0 C min under flowing argon on a Setaram Setsys evolution-
d
2
1750 instrument. Powder XRD patterns were recorded on a Phi-
6.95, 6.57 (m, 4H, H-3), 5.61 (s, JHPt ¼ 66.9 Hz, 4H, CH]CH), 3.71 (br,
lips PW1820 using Cu-K radiation.
a
2H, MeOCH), 3.50, 3.48, 3,36 (s, 6H, OMe), 2.92e2.40 (m, 8H, CH
2
),
3
195
1
2
.27 (d, JHH ¼ 9 Hz, PtCH), 2.05e1.55 (m, 8H, CH
2
);
Pt{ H} NMR
2
2.2. Synthesis of [Pt (Spy)
2
(C
8
H
12OMe)
2
] (2)
(64 MHz, CDCl
3
):
d
¼ ꢀ3470 (Δ1/2 ¼ 458 Hz), ꢀ3333, other minor
broad peaks at ꢀ3447, ꢀ3454 and ꢀ3481 ppm; ESI-MS, m/z (%): 859
þ
(
a) To a benzene solution (20 mL) of [Pt
0.206 g, 0.278 mmol), solid Pb(Spy) (0.122 g, 0.285 mmol) was
added and stirred for 2 h. A yellow solution containing a white
precipitate of PbCl was obtained. The reaction mixture was filtered
2
(
m
-Cl)
2
(C
8
H
12OMe)
2
]
[M ꢀ Pt(Spy)(C
8
H12OMe)]
(5%),
415
[{Pt(Spy)
2
}]
(100%)
(
2
(Supplementary information, Fig. S2).
Data of [Pt (Spy) (C 12-O-C
Calcd. for C56 Pt (4∙OEt
Found: C, 38.3; H, 4.0; N, 3.1; S, 7.7%. H NMR (300 MHz, CDCl
¼ 8.10 (m, 4H, 6-H), 7.46 (m, 4H, H-4), 7.07 (m, 4H, H-5), 6.54 (m,
4H, H-3), 5.58 (br s, 8H, CH]CH), 3.68 (br s, 4H, OCH), 2.85e1.45
(m, 36H, CH 4.12 (q), 1.26 (t) are due to the
þ PtCH). The peaks at
solvated Et
ꢁ
4
4
8
H
8
H
12
)
2
] (4). M.p. 198 C (dec.). Anal.
2
H
74
N
4
O
3
S
4 4
2
): C, 38.2; H, 4.2; N, 3.2; S, 7.3.
1
through celite and the filtrate was concentrated to 3 mL and 1 mL of
3
):
ꢁ
hexane was added and cooled at 10 C to yield yellow crystals of 2
d
(
0.172 g, 0.193 mmol, 69%). [In some preparations a few red crystals
were also formed which were separated manually and character-
2
d
13
1
ized as [Pt
3
(Spy)
4
(C
8
H
12OMe)
2
] (3) (see later).]
2
O in the crystals of 4; C{ H} NMR (75 MHz, CDCl
3
):
ꢁ
ꢁ
Data of 2. m.p. 182 C (darkens above 165 C). Anal. Calcd. for
d
¼ 170.1 (br s, C-2), 150.3 (s), 149.5, 149.0 (br s, C-6), 134.62 (s),
C
28
H
38
N
2
O
2
Pt
2
S
2
: C, 37.8; H, 4.3; N, 3.1; S, 7.2. Found: C, 37.9; H, 4.3;
134.60 (br s, C-4), 129.8, 128.8 (br s, C-3), 119.6, 119.5 (br s, C-5), 87.3
1
N, 3.0; S, 7.3%. H NMR (300 MHz, C
s) (2H, H-6), 7.45 (m, 2H, H-4), 6.56 (m, 2H, H-5), 6.13, 6.02 (br s, 2H,
6
D
6
):
d
¼ 8.26 (m), 8.03, 7.88 (br,
(s, MeOCH), 80.6, 79.7 (s, C]C), 35.8, 30.0, 29.7, 28.3, 26.8 (s,
195
1
CH
¼ ꢀ3495 (major, Δ1/2 ¼ 312 Hz), other minor broad peaks
at ꢀ3523, ꢀ3554, ꢀ3607 (each approx. of Δ1/2 ¼ 624 Hz) ppm.
2
), 25.05, 24.9 (br s, PtC);
3
Pt{ H} NMR (64 MHz, CDCl ):
2
2
H-3), 5.58 (br s, JHPt ¼ 73.2 Hz), 5.48 (br s, JHPt ¼ 67.8 Hz), 4.84 (br s,
d
3
J
HPt ¼ 53.1 Hz), 3.99 (br s) (4H, CH]CH), 4.49, 4.12 (br s, 2H,
MeOCH), 3.70, 3.64, 3.61 (each s, 6H, OMe), 2.85e1.80 (m, 8H, CH );
¼ 171.5, 170.3 (br s, Δ1/2 ¼ 40 Hz, C-
), 150.6, 150.1, 149.8 (s, C-6), 134.9, 134.8 (s, C-4), 131.0, 130.6, 130.0
s, C-3), 120.3, 119.9, 119.5 (s, C-5), 88.9, 87.6, 86.6, 86.3, 85.0, 84.7,
3.9, 83.6, 81.0, 80.6 (C]C, COMe) (The platinum satellites could not
2
13
1
2.4. Synthesis of [Pt(S ] (5)
P{OPri}
C{ H} NMR (75 MHz, C
6
D
6
):
d
2
2 2
)
2
(
8
To a dichloromethane (10 mL) solution of [Pt
2
(m
-Cl)
2 8 12
(C H
i
OMe) ] (0.104 g, 0.140 mmol), methanolic (5 mL) NH
2
4
S
2
P(OPr )
2
3
be assigned), 56.4, 56.2 (s, COMe), 36.2 (s, JCPt ¼ 38.1 Hz; CH
4.8 (s, CH CH COMe), 31.0, 30.6 (s, CH CH CHPt), 29.4 (m,
CH
CHPt), 25.4, 24.1, 23.2 (each s, JCPt ¼ 628, 620, 632 Hz respec-
tively; PteC);
2
COMe),
(0.065 g, 0.280 mmol) was added. The color of the solution turned
yellow and the whole reaction mixture was stirred for 2 h. The
solvents were evaporated under reduced pressure and the residue
was extracted with dichloromethane (2 ꢂ 5 mL) and passed through
a Florisil column. The filtrate was concentrated to 3 mL and 1 mL of
3
2
2
2
2
1
2
195
1
Pt{ H} NMR (64 MHz,
C
6
D
6
): ꢀ3508 (Δ1/
2
¼ 272 Hz); ꢀ3541 (Δ1/2 ¼ 679 Hz) ppm (2:1) ratio; UV/Vis
(
CH
2
Cl
2
)
l
max
ꢀ1
(
3
): 277 (18,000), 324 (8000), 371 nm (sh,
hexane was added to yield yellow crystals of 5 (0.125 g, 0.201 mmol,
ꢀ
1
þ
ꢁ
3
000 M cm ); ESIeMS, m/z (%): 778 ([M ꢀ (Spy)] , 100%), 748
71%), m.p. 123 C (dec.). Anal. Calcd. for C12
H
28
O
4
P
2
PtS
4
: C, 23.2; H,
þ
1
(
[Pt
2
(Spy)
2
(C
8
H
12OMe) ꢀ H] , 20%), 638 ([Pt2(Spy)(C8H12OMe) ꢀ
4.5; S, 20.6. Found: C, 23.2; H, 4.4; S, 20.0%; H NMR (300 MHz,
þ
3
3
H]þ,13%), 413 ([Pt(Spy)
2
ꢀ 2H] , 49%) (Supplementary information,
CDCl
24H, CHMe
3
):
d
¼ 4.98 (hep, JHH ¼ 6 Hz, 4H, CHMe
2
), 1.41 (d, JHH ¼ 6 Hz,
1
3
1
Fig. S1).
2
); C{ H} NMR (75 MHz, CDCl
3
):
d
¼ 74.2 (s, CHMe
2
),
3
1
1
(
b) To a methanolic solution (15 mL) of NaSpy (freshly prepared
23.8 (s, CHMe
2
);
P{ H} NMR (121 MHz, CDCl
PPt ¼ 441 Hz);
3
):
d
¼ 97.4 (t,
4
2
195
1
by reaction between HSpy (0.062 g, 0.563 mmol) and NaOMe in
methanol (1.1 mL, 0.53 N, 0.572 mmol)), a dichloromethane solu-
tion (10 mL) of [Pt (m-Cl) (C H12OMe) ] (0.209 g, 0.282 mmol) was
2 2 8 2
J
PP ¼ 10.2 Hz,
J
Pt{ H} NMR (64 MHz, CDCl
3
):
2
d
¼ ꢀ3981 ( JPPt ¼ 441 Hz) ppm.
added and stirred for 3 h. The solvents were evaporated under
reduced pressure and the residual solid was chromatographed on
a silica gel column (3 ꢂ 40 cm), 30:70 v/v ethylacetate/hexane to
2 2 2 8
2.5. Synthesis of [Pt(SCH CH NMe )(C H12OMe)] (6)
To a methanolic solution of Me
0.508 mmol), NaOMe in methanol (1.95 mL, 0.52 N) was added and
stirred for 15 min. To this reaction mixture [Pt -Cl) (C 12OMe)
2 2 2
NCH CH SH∙HCl (0.072 g,
4 4 8 8 12 2
elute [Pt (Spy) (C H12-O-C H ) ] (4) and 10:90 v/v methanol/
chloroform to elute 2. The solvent was removed from the product
2
(m
2
8
H
2
]
containing fractions by rotary evaporation and oil pump vacuum to
(0.187 g, 0.248 mmol) was added and the whole was further stirred
for 2 h. The solvent was evaporated to dryness and the residual
solid was extracted with dichloromethane (3 ꢂ 6 mL) to yield 6 as
give yellow crystalline solid of 2 (0.160 g, 0.180 mmol, 64%), m.p.
ꢁ
1
84 C. The volume of fraction containing 4 was made up to 5 mL,
ꢁ
few drops of diethylether added to yield pale yellow crystals of
a colorless solid (0.184 g, 0.419 mmol, 83%), m.p. 178 C (dec.). Anal.
4
$OEt
2
(0.037 g, 0.021 mmol, 15%).
(Spy) (C 12OMe)
calcd for C13
H
25NOPtS: C 35.6, H 5.7, N 3.2, S 7.3; found: C 35.6, H
Cl ): 275 (sh) (4400), 293 nm
):
¼ 4.23 (t,
CH]CH), 3.90e3.87 (m,
5
.7, N 3.0, S 6.3%; UV/Vis (CH
2
2
)
l
max
(
3
ꢀ
1
ꢀ1
1
2.3. Synthesis of [Pt
3
4
8
H
2
] (3)
(5400 M cm );
H
NMR (300 MHz, CDCl
3
d
3
HH ¼ 8.7 Hz, 2JHPt ¼ 70 Hz, 1H, CH
J
J
2
2
To
a
benzene solution (15 mL) of PtCl
2
(COD) (0.027 g,
HPt ¼ 62 Hz, 1H, CH
2
CH]CH), 3.50 (m, 1H, MeOCH), 3.24 (s, 3H,
3
0
.072 mmol), solid Pb(Spy)
2
(0.030 g, 0.070 mmol) was added and
OMe), 2.92 (m, 2H, NCH
2
), 2.84 (t,
J
HH ¼ 5.4 Hz, 2H, SCH
2
),

N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498
3493
2
.65e2.79 (m, 4H, CH
2
); 2.48, 2.42 (each s, 3
J
HPt ¼ 13.4 Hz, 6H,
noting that
(ppy ¼ metalated 2-phenylpyridine) with Pb(Spy)
a platinum(III) complex [Pt Cl (Spy) (ppy) ] [18]. The NMR spectra
Pt{ H}) of 2 revealed the existence of more than
a
similar reaction between [Pt
2
(
m
-Cl)
2 2
(ppy) ]
3
13
NMe
2
), 2.15 (q, JHH ¼ 8.4 Hz, 1H, PtCH), 1.72e1.80 (m, 4H, CH
2
);
C
2
readily yields
1
1
{
H} NMR (75 MHz, CDCl
3
):
d
¼ 86.6 (s, JCPt ¼ 159 Hz, CH
2
CH]CH),
CH]CH), 71.1 (s,
), 55.8 (s, OMe), 49.2, 46.5 (each s, NMe ), 33.7 (s,
CH COMe),
2
2
2
2
1
1
13
1
195
1
8
3.5 (s, MeOCH), 81.9 (s,
J
CPt ¼ 170 Hz, CH
2
( H, C{ H},
2
J
CPt ¼ 53 Hz, NCH
2
2
one isomeric species in solution (Supplementary information,
3JCPt ¼ 15 Hz, CH
CHOMe), 29.4 (s,
CH
2
J
CPt ¼ 14 Hz, CH
Figs. S3eS5). The H NMR spectrum showed three peaks due to
1
2
2
2
2
2
13
1
2
2
8.9 (s, JCPt ¼ 16 Hz, CH
2
2
CHPt), 27.8 (s, JCPt ¼ 18 Hz, CH
2
CHPt);
Pt{ H}
OMe protons. Similarly the C{ H} NMR spectrum displayed three
sets of resonances for the pyridyl group and -bonded carbon
Pt{ H} NMR spectrum
6.9 (s, 2
J
CPt ¼ 29 Hz, SCH
), 17.9 (s, JCPt ¼ 647 Hz; PtC);
1
195
1
s
2
195
195
1
NMR (64 MHz, CDCl
3
):
d
¼ ꢀ3722 (s) ppm.
atom (with
Pt couplings). The
exhibited two resonances in 1:2 ratio.
2
.6. Synthesis of [Pt(SeCH CH NMe )(C 12OMe)] (7)
2
2
2
8
H
The complex 2 may exist in different geometrical and optical
configurations. In case of geometrical configurations cis and trans
isomers are possible [34] (Supplementary information, Fig. S6). For
trans isomer only one set of olefinic, OMe and pyridyl ring proton/
carbon resonances are expected whereas cis isomer, in which the
relative disposition of the ligands around Pt centers is different,
would display two sets of olefinic, OMe and pyridyl ring proton/
carbon resonances in the NMR spectra. Also the OMe groups can be
endo or exo or at the same or different side with respect to the plane
passing by the mid points of the two olefinic bonds and the
PtCeC(OMe) bonds which would generate different isomeric forms.
In addition to above geometrical isomers, the presence of two chiral
centers in octenyl group, the complex 2 is capable to generate
various diastereomers having different chemical shifts in NMR
spectra. All the above isomeric forms may not give at different
To
NaSeCH
.486 mmol) and solid NaBH
Pt -Cl) (C 12OMe) (0.357 g, 0.482 mmol). The reaction
a
freshly prepared methanolic solution (5 mL) of
CH NMe (prepared from (SeCH CH NMe (0.147 g,
(0.040 g, 1.057 mmol)) was added
2
2
2
2
2
2 2
)
0
[
4
2
(m
2
8
H
2
]
mixture was stirred for 2 h. The solvent was evaporated to dryness
and the residual solid was extracted with dichloromethane
(
3 ꢂ 10 mL) to yield a pale yellow solid 7 (0.385 g, 0.793 mmol, 82%),
ꢁ
m.p. 187 C (dec.). Anal. Calcd. for C13
H25NOPtSe: C, 32.2; H, 5.2; N,
2
.9. Found: C, 32.1; H, 5.1; N, 2.3%; UVevis (CH
2
Cl
2
)
l
max
(
3
): 274
):
2
CH]CH), 4.01e3.90
ꢀ
1
ꢀ1
1
(
4400); 302 nm (7700 M cm ); H NMR (300 MHz, CDCl
3
3
2
d
¼ 4.27 (t, JHH ¼ 7.4 Hz, JHPt ¼ 69.9 Hz,1H, CH
2
(
(
m, JHPt ¼ 61.2 Hz,1H, CH
2
CH]CH), 3.51e3.45 (m,1H, MeOCH), 3.24
s, 3H, OMe); 3.01e3.53 (m, 2H, NCH
2
), 2.90e2.65 (m, 4H, CH
, the peak due to SeCH merged in
);
CH]
2
), 2.48,
3
195
1
2
.39 (each s, JHPt ¼ 13.5 Hz; NMe
2
2
chemical shifts as for example the broadness of one of the Pt{ H}
NMR resonance (ꢀ3541 ppm, Δ1/2 ¼ 679 Hz) indicates the pres-
ence of mixtures of similar but different species.
3
the base), 2.13 (q, JHH ¼ 8.7 Hz, 1H, PtCH), 1.90e1.55 (m, 4H, CH
2
13
1
1
C{ H} NMR (75 MHz, CDCl
3
):
d
¼ 87.3 (s, JCPt ¼ 157 Hz, CH
2
1
CH), 83.6 (s, MeOCH), 82.2 (s, JCPt ¼ 170 Hz, CH
2
CH]CH), 71.9 (s,
In some reactions between 1, when slightly contaminated with
2
J
CPt ¼ 47 Hz, NCH
2
), 55.9 (s, OMe), 49.2, 46.6 (each s, NMe
2
), 34.0 (s,
COMe), 29.0
CHPt), 15.0
PtCl
[Pt (Spy)
poor yield together with 2 as a major product. The structure of 3 can
be compared with an allyl complex [Pd (SMes) (C ] [35]. The
latter could be isolated by refluxing [Pd(SMes) with
[Pd (SMes) (C in dichloromethane. Thus the reaction
between 2 and freshly prepared [Pt(Spy) ] (as the sample showed
poor solubility on aging) in refluxing benzene afforded 3, structure
2
2
(COD), and Pb(Spy) , a red crystalline trinuclear complex
3JCPt ¼ 15 Hz, CH
COMe), 29.4 (s, JCPt ¼ 16 Hz, CH
2
CH
(C 12OMe) ] (3) (by X-ray analysis) was also formed in
H
2
2
2
3
4
8
2
2
2
(
s, JCPt ¼ 17 Hz, CH
2
CH
2
CHPt), 27.7 (s, JCPt ¼ 18 Hz, CH
2
1
2
1
(
s, JCPt ¼ 634 Hz, PtC); 13.4 (s, SeCH
2
,
J
CPt ¼ 28 Hz, JCSe ¼ 58 Hz);
3
4
4 7 2
H )
7
7
1
1
195
1
Se{ H} NMR (57 MHz, CDCl
3
):
d
¼ 214 ( JSePt ¼ 157 Hz);
Pt{ H}
2 n
]
NMR (64 MHz, CDCl ):
3
d
¼ ꢀ3720 ppm.
2
2
4 7 2
H ) ]
2
2
.7. Crytallography experiments
1
of which was again ascertained by X-ray crystallography. The
H
Single crystal X-ray diffraction measurements were made on
Rigaku AFC 7S diffractometer at room temperature (298 ꢃ 2 K)
NMR spectrum of 3 showed different resonances for OMe group
195
1
and the
Pt{ H} NMR spectrum displayed two major peaks at
ꢀ
using graphite monochromated Mo-K
a
(l
¼ 0.71069 A) radiation.
d
ꢀ3470 ppm (terminal Pt) and ꢀ3333 ppm (central Pt) together
The structures were solved by direct methods [25] and refinement
was on F2 [26] using data corrected for Lorentz and polarization
effects with an empirical procedure [27,28]. The non-hydrogen
atoms were refined with anisotropic displacement parameters
and hydrogen atoms were fitted in their calculated positions and
refined in isotropic approximation using riding model. Neutral
atom scattering factors were taken from Cromer and Waber [29].
All calculations were performed using crystal structure crystallo-
graphic software package [30,31]. Molecular structures were drawn
using ORTEP [32].
with other small peaks indicative of the existence of other isomeric
forms in solution (Supplementary information, Fig. S7).
In an attempt to prepare 2 by an alternative route, reaction of 1
with 2-mercaptopyridine in the presence of sodium methoxide was
carried out. The reaction gave a mixture of products as revealed by
195
1
Pt{ H} NMR spectroscopy. From this mixture at least two
complexes, viz. 2 (64% yield) and a self-assembled tetranuclear
complex [Pt (Spy) (C 12-O-C ] (4) (15% yield) could be
4
4
8
H
8 12 2
H )
separated by column chromatography on silica gel. The 4 appears to
be formed by demethylation of 2 during the reaction in the presence
2 2
of 2-mercaptopyridine and NaOMe in CH Cl eMeOH mixture.
3
. Results and discussion
Demethylation of aliphatic as well as aromatic methylethers is well
documented in literature [36e38]. Demethylation of ether involving
metal complex, to our knowledge, is the first example. Other prob-
3.1. Synthesis and spectroscopy
able route, i.e. first demethylation of 1 to form [Pt
4
(
m
-Cl)
4
(C
8
H12-O-
ꢀ
Reactions of 1 with various anionic chalcogenolate ligands
differing in mode of coordination to metal atom and the ligand
bite have been investigated (Scheme 1). Treatment of 1 with
C
8
H
12
)
2
], followed by substitution of chloro-bridge by pyS , is ruled
ꢀ
out in the presence of strong nucleophilic pyS . The reaction at
higher temperature was not attempted to improve the yield of 4 due
to decomposition of thermodynamically unstable metalated octenyl
groups which is discussed in thermal studies. The decomposition of
2 begins at 80 C. The
tively sharp resonance at
at
ꢀ3523, ꢀ3554 and ꢀ3607 ppm due to the existence of other
possible isomeric forms with different coordination environment
freshly prepared Pb(Spy)
complex [Pt (Spy) (C 12OMe)
The 2, unlike 1 which converts in PtCl
solvents [33], was quite stable both in polar and non-polar
solvents like benzene, CH Cl , CHCl at least for a week without
any decomposition or disproportionation (by NMR). It is worth
2
afforded
] (2) as a yellow crystalline solid.
(COD) in halogenated
a binuclear Spy-bridged
2
2
8
H
2
ꢁ
195
1
2
Pt{ H} NMR spectrum of 4 showed a rela-
d
ꢀ3495 ppm and three small broad peaks
2
2
3
d

3494
N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498
OMe
N
S
S
N
N
S
S
Pt
Pt
Pt
N
OMe
3
(48%)
[
Pt(Spy)2]
benzene
OMe
S
N
Pt
Pt
N
S
MeO
2
(69%)
Pb(Spy)2
benzene
OMe
E
i
NH {S P(OPr ) }
2 NaECH
CH NMe
2 2 2
4
2
2
i
i
i
i
OPr
OPr
S
S
S
S
OPr
OPr
MeOH
MeOH
P
Pt
P
1
Pt
N
5
(71%)
2 pySH, 2 NaOMe
E = S (6, 83%); Se (7, 82%)
MeOH, CH Cl2
2
N
S
N
Pt
Pt
N
N
O
O
2
(64%)
S
S S
Pt
Pt
4
(15%)
Scheme 1.
around platinum in solution (Supplementary information, Fig. S8).
analyses. The ORTEP drawings with crystallographic numbering
scheme are shown in Figs. 1e5, and the selected interatomic
parameters are given in Table 1. The complexes 3 and 4 were
crystallized each with a molecule of dichloromethane and dieth-
ylether, respectively.
1
The resonance due to OMe group, as expected, was absent in the H
13
1
and C{ H} NMR spectra of 4.
The reaction of 1 with a large bite thiolate ligand, diisopro-
i
pyldithiophosphate, gave [Pt{S
2
P(OPr )
2
}
2
] (5), formed by extrusion
of metalated octenyl ligand. Extrusion of metalated dienylmethoxy
moiety in platinum complexes by neutral and anionic ligands is not
uncommon [39e41].
The metalated C
boat conformation and is bonded to platinum atom through a
olefinic bond. The olefinic bond and the platinum coordination
plane are at an angle varying between 73.76 and 83.66 . The
8
H
12OMe group in 2, 3, 4 and 7 has a distorted
s
and
ꢁ
The reaction of 1 with non-rigid 5-membered chelating ligands,
ꢀ
Me
Pt(ECH
colorless (6)/pale-yellow (7) crystalline solids. These complexes
2
NCH
2
CH
2
E
afforded mononuclear platinum complexes
methoxy group of cyclooctene adopts an exo configuration with
[
2
CH
2
NMe
2
)(C
8
H12OMe)] (E ¼ S (6), Se (7)) in w82% yield as
respect to the platinum. The PteC
similar to those observed in [PtCl(py)(C
[Pt (OMe) (C 12OMe) ] [43,44]. The PteC(olefin) bond in the case
of 7 is, however, significantly shorter (w2.05 A) than those
s
and PteC(olefin) distances are
8
H12OMe)] [42] and
1
13
1
showed expected resonances in the H and C{ H} NMR spectra.
2
2
8
H
2
1
95
1
ꢀ
The
Pt{ H} NMR spectra of 6 and 7 displayed a sharp singlet at
wꢀ3720 ppm.
observed for 2, 3, 4 and also [PtCl(py)(C
The pyridine-2-thiolate ion (pyS ) in 2, 3 and 4 acts as a bridging
ligand and binds two platinum atoms through S N coordination.
8
H
12OMe)] [42].
ꢀ
X
3.2. Crystal structures
The thiolate sulfur in these complexes occupies a position trans to
Crystal and molecular structures of 2, 3, 4, 5 and 7 have been
olefinic bond while the nitrogen atom is trans to the PteC
s
bond.
established unambiguously by single crystal X-ray diffraction
Such a trend e a strong trans influencing ligand (e.g. PPh )
3

N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498
3495
2 2 8 2
Fig. 1. Molecular structure of [Pt (Spy) (C H12OMe) ] (2), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity.
occupying a position trans to olefinic bond, has been reported in
bridge splitting reactions of [Pt -Cl) (C 12OMe) ] with neutral
donor ligands [45]. The PteS distances (2.277(5)e2.323(4) A) are
the large trans influence of the
s
-bonded carbon atom and are
CH(Me)NMe )(P-
] (2.142(7) A) [51].
The complex 2 is a Spy-bridged binuclear platinum(II) com-
2
(m
2
8
H
2
slightly longer than those reported in [PtCl(SCH
2
2
ꢀ
ꢀ
ꢀ
2 2 2 2
Me Ph)] (2.130(9) A) [50] and [Pt (ppy) (Spy)
well within the range reported in platinum(II) thiolate complexes,
e.g., [Pt
OMe)] [47], [Pt{(SPPh
Spy) ] [49]. The PteN distances (2.160(15)e2.239(17) A) reflects
3
(Stol)
4
(dppm)
2
][SO
3
CF
3
]
2
[46], [Pt{(OPPh
2
)N(PPh
2
S)}(C
8
H
12
plex with a trans or anti configuration. The molecule adopts
a head-to-tail configuration similar to the other cyclometalated
binuclear platinum complexes containing bridging Spy ligands,
2
)N(PPh
2
S)}(C 12OMe)] [48] and [PtMe
8
H
2
ꢀ
(
2
3 4 8 2
Fig. 2. Molecular structure of [Pt (Spy) (C H12OMe) ] (3), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity.

3496
N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498
Fig. 3. Molecular structure of [Pt
4
(Spy)
4
(C
8
H12-O-C
8
H )
12
2
] (4), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity.
þ
e.g. [Pt
2
(Spy)
2
(ppy)
2
] [51], [Pt
2
(Spy)
2
(bipy)
2
]2 [52], [Pt
2
(Spy)
2
structure can be compared with the structure of chloro(allyl)
2
þ
0
0
(
dtby)
2
]
(dtby ¼ 4,4 -di-tert-butyl-2,2 -bipyridine) [53]. The
platinum(II) [54] and tetranuclear palladium complexes
ꢀ
X
Pt/Pt separation in 2 is much larger (3.448 A) than those reported
in Spy-bridged binuclear platinum complexes, e.g. [Pt (Spy)
[Pd
4
(OAc)
4
(C N)
2
] formed by double metalation of organic ligands
2
2
by palladium acetate [20]. The Pd/Pd separation in the latter is
ꢀ
ꢀ
(
ppy)
2
] (2.849(4) A) [51].
2 2
w2.9 A while in 4 the two platinum atoms in ‘Pt (Spy) ’ units are
ꢀ
The 3 is a trinuclear complex in which three platinum atoms are
3.804 A apart possibly to relieve crowding of the two bulkier ether
ligands. The molecule has a two-fold axis perpendicular to the
Pt/Pt axis containing two platinum atoms of the same binuclear
unit. The angle between the two Pt square planes (four atom least
square plane [55]) decreases as Pt/Pt separation decreases in
complexes 4, 2 and 3, which agrees well with the literature [56].
The two dithiophosphate ligands in 5 are coordinated to plat-
inum atom in a chelating bidentate fashion. The platinum coordi-
nation plane and the two four-membered chelate rings all lie in
a plane. The PteS distances are as expected [57].
held together by double-edge bridges of Spy ligand. The trinuclear
complex has a two-fold axis on the central Pt square plane passing
between SePteS and NePteN angles. The coordination environ-
ment around the central platinum atom is defined by trans
disposed S and N donor atoms.
In the tetranuclear complex 4, the two “Pt
2 2
(Spy) ” units are held
together by bridging dicyclooctene-yl groups. The molecular
The complex 7 is a discrete monomer having distorted square
planar platinum atom. The chalcogenolate ligand is coordinated to
the metal atom in a bidentate mode. The PteSe distance is
ꢀ
unusually short (2.266(11) A). The PteSe distances in
[
PtCl(SeCH )(PMe
2
CH(Me)NMe
2
2 2 2
Ph)] [50] and [Pt Cl (m-Cl)(m-
ꢀ
SeCH CH COOMe)(PPr ) ] [58] are w2.38 A. This may be due to
2
2
3 2
very weak trans influence of olefin. The five-membered “PtSCCN”
ring is puckered.
3.3. Thermal studies
Recently we have employed binuclear platinum complexes
[
Pt
2
(OR)
2
(C
8
H
12OMe)
2
] (R ¼ Me, Ac) for the preparation of platinum
nanoparticles (w10 nm) by thermolysis in HDA (1-
hexadecylamine) [14]. The complexes with chalcogenolate ligands
may yield platinum chalcogenides on pyrolysis as several palladium
chalcogenolate complexes have been used as single source molec-
ular precursors for the synthesis of palladium chalcogenides
[35,19,59,60]. The complexes described here may serve as precur-
sors for the preparation of platinum chalcogenides as the presence
of comparatively stronger PteE bond in these complexes than the
PteO bond in the earlier complexes [14]. The complex
P{OPri}
2
)] (5), ellipsoids drawn at 50% probability.
Fig. 4. Molecular structure of [Pt(S
2
Hydrogen atoms are omitted for clarity.
2 2 8 2
[Pt (Spy) (C H12OMe) ] (2) underwent a three-step decomposition

N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498
3497
2 2 2 8
Fig. 5. Molecular structure of [Pt(SeCH CH NMe )(C H12OMe)] (7), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity.
as revealed by TG curve (Supplementary information, Fig. S9). The
information, Figs. S11eS13) as prepared samples corresponds to 20
(from 2); 4 (from 6); 7 (from 7) nm.
weight loss in the first step corresponds to the loss of methoxy
ꢁ
groups at 80 C (wt. loss found 6.9%, calcd. 7.0%). The second step of
ꢁ
decomposition (at 180 C) can be attributed to the loss of cyclo-
4. Conclusions
octenyl group (wt. loss found 23%, calcd. 24.3%). The final step of
ꢀ
decomposition corresponds to the loss of pyS ligand (wt. loss
Mono-, bi- and trinuclear complexes 7, 2 and 3, respectively
with weakly coordinated octenyl group and strongly bonded
chalcogenolate ligand have been synthesized and structurally
found 23%, calcd. 24.5%) leading to the formation of platinum metal.
The TG curve of 6 (Supplementary information, Fig. S10) showed
a two-step decomposition wherein the first step corresponds to the
characterized.
A new oxo-bridged tetranuclear macrocyclic
loss of (C
SCH CH NMe
decomposition corresponding to the loss of (C
8
H
12OMe) and the second step corresponds to the loss of
group. The TG curve of 7 showed a single step of
12OMe) group.
complex 4 has been isolated and structurally characterized. Ther-
molysis of mono- or binuclear complexes of platinum containing
strong PteE bond in HDA yields fcc phase of platinum
nanoparticles.
2
2
2
8
H
When 2, 6 and 7 are thermolysed in HDA in the temperature range
ꢁ
2
10e250 C platinum nanoparticles, rather than platinum chalco-
genides, were formed. The observed lattice planes in the XRD
pattern indicate the formation of fcc phase of platinum particles
Acknowledgments
[
61]. The average size estimated from XRD pattern (Supplementary
We thank Drs. T. Mukherjee and D. Das for encouragement of
this work. One of the authors (NG) is thankful to the DAE-Mumbai
University Collaborative Scheme for the award of a Senior Research
Fellowship (SRF).
Table 1
Selected interatomic distances [A] and angles [ ].
ꢀ
ꢁ
2
3$CH Cl
2
2
4$OEt
2
7
Appendix. Supplementary information
Pt(1)eC(10)
Pt(1)eC(6)
2.15(2)
2.15(2)
2.11(2)
2.282(5)
2.15(2)
2.02(2)
2.13(2)
2.277(5)
1.332
2.046(19)
2.151(19)
2.18(2)
2.323(4)
e
2.033(15)
2.124(19)
2.10(2)
2.308(5)
2.145(17)
2.009(15)
2.113(19)
2.297(5)
1.350
2.039(9)
2.061(9)
2.045(8)
2.2660(11)
e
Details of synthesis of [Pb(Spy)
2 2
], [Pt(Spy) ], crystallographic
Pt(1)eC(13)
Pt(1)eS(1)/Se(1)
Pt(2)eC(19)
Pt(2)eC(23)
Pt(2)eC(26)
Pt(2)eS(2)
and structure refinement data tables of all complexes, mass spectra
1
13
1
195
1
195
1
of 2 and 3;
H
C{ H} and
Pt{ H}NMR spectra of 2;
Pt{ H}
NMR spectra of 3 and 4; TG curves of 2 and 6 and powder XRD
pattern of platinum nanoparticles, single crystal X-ray diffraction
studies (cif file) of 2, 3, 4, 5 and 7 are provided in supplementary
information. CCDC 801696, 801697, 801698, 801695 and 801694
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from the Cambridge
Crystallographic Data Centre via HYPERLINK “http://www.ccdc.
cam.ac.uk/data_request/cif ” www.ccdc.cam.ac.uk/data_request/cif.
Supplementary data associated with this article can be found in
the on-line version at doi:10.1016/j.jorganchem.2011.07.025.
e
e
e
e
2.295(5)
1.411
e
C(6)eC(13)
1.411(14)
C(13)ePt(1)eC(6)
C(13)ePt(1)eC(10)
C(13)ePt(1)eS(1)
C(23)ePt(2)eC(26)
C(26)ePt(2)eC(19)
C(26)ePt(2)eS(2)
Pt/Pt
36.4(8)
81.8(10)
153.4(9)
82.1(9)
38.2(9)
165.8(9)
3.448
38.1(7)
80.2(7)
168.7(7)
e
37.4(8)
81.2(8)
153.8(6)
82.2(7)
38.9(7)
154.0(5)
3.832 (Pt1)
40.2(4)
82.2(4)
158.8(3)
e
e
e
e
e
e
3.136
3
.775 (Pt2)
69.44 (Pt1)
3.41 (Pt2)
Pt sq. planea
52.75
33.37
e
References
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a
The angle between two platinum square planes. As the metal planes are dis-
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