Reactivity of platina-β-diketones towards chelating nitrogen and sulfur donors: Formation of acyl(hydrido)platinum(IV) and acyl(chloro) platinum(II) complexes

Article abstract of DOI:10.1016/j.ica.2003.11.045

The platina-β-diketone [Pt₂{(COMe)₂H} ₂(μ-Cl)₂] (1) was found to react with chelating N,N-ligands 2(R^′N=CR)C₅H₄N (R/R ^′=Ph/OH, H/Ph, Me/Ph) to form acyl(hydrido)platin

Full text of DOI:10.1016/j.ica.2003.11.045

Inorganica Chimica Acta 357 (2004) 1781–1788
www.elsevier.com/locate/ica
Reactivity of platina-b-diketones towards chelating nitrogen
and sulfur donors: formation of acyl(hydrido)platinum(IV)
and acyl(chloro)platinum(II) complexes
*
Tushar Gosavi, Eduard Rusanov, Harry Schmidt, Dirk Steinborn
Institut fu€r Anorganische Chemie, Martin-Luther-Universit€at Halle-Wittenberg, Kurt-Mothes-Straße 2, Halle D-06120, Germany
Received 22 September 2003; accepted 19 November 2003
Dedicated to Professor Helmut Werner on the occasion of his 70th birthday
Abstract
The platina-b-diketone [Pt2{(COMe)2H}2(l-Cl)2] (1) was found to react with chelating N,N-ligands 2(R0N@CR)C5H4N (R/
R0 ¼ Ph/OH, H/Ph, Me/Ph) to form acyl(hydrido)platinum(IV) complexes [Pt(COMe)2Cl(H){2-(R0N@CR)C5H4N}] (R/R0 ¼ Ph/
OH 2a; H/Ph 2b; Me/Ph (2c)). Reactions of complex 1 with chelating S,S- and N,S-donors (RS–CH2–CH2–SR, 2-(RSCH2)C5H4N,
R ¼ Et, Ph, t-Bu) afforded acyl(chloro)platinum(II) complexes [Pt(COMe)Cl(RSCH2CH2SR)] (R ¼ Et, 3a; Ph, 3b; t-Bu, 3c) and
[Pt(COMe)Cl{2-(RSCH2)C5H4N}] (R ¼ Et, 4a; Ph, 4b; t-Bu, 4c), respectively. All complexes were fully characterized by micro-
analysis, IR and NMR (1H, 13C) spectroscopy. Furthermore, molecular structures of complexes 3b and 4b were determined by
single-crystal X-ray diffraction analyses revealing close to square-planar configuration. In complex 4b the acetyl ligand is trans to
pyridine N atom (configuration index SP-4-2). The reactions are discussed in terms of consecutive oxidative addition and reductive
elimination reactions.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Platina-b-diketones; Platinum complexes; Acyl complexes; Hydroxycarbene complexes; Hydrido complexes
1. Introduction
the case of FischerÕ s carbene complexes. On the other
hand, dimeric platina-b-diketones (B, Scheme 1) being
electronically unsaturated (16 ve), kinetically labile
complexes exhibit completely different reactivity than
LukehartÕ s complexes A [3,4].
Metalla-b-diketones are (formally) derived from
enolic forms of 1,3-diketones by replacing the central
methine group by a transition metal fragment LxM
(Scheme 1). Just as 1,3-diketones are hydrogen-bridged
vinyl alcohol/ketone species, so metalla-b-diketones may
be regarded as hydroxycarbene complexes intramolec-
ularly stabilized by hydrogen bridges to acyl ligands.
Stability and reactivity of metalla-b-diketones cover a
wide range: LukehartÕ s metalla-b-diketones [1,2] (A,
Scheme 1) having carbonyl and cyclopentadienyl co-li-
gands are electronically saturated and kinetically inert
complexes. They can be easily deprotonated and nucle-
ophiles attack typically the carbene carbon atoms as in
Typically, the platina-b-diketone 1 (B, R ¼ Me) reacts
with chelating N and P nucleophiles in an oxidative ad-
dition forming acetyl(hydrido)platinum(IV) complexes
followed by reductive elimination of acetaldehyde yield-
ing acetyl(chloro)platinum(II) complexes (1 ! C ! D,
Scheme 2). In the case of N_N donors of the bipyridine
and phenanthroline type the platinum(IV) complexes C
are thermally extraordinarily stable and undergo reduc-
tive eliminations (C ! D) only at temperatures above
140 °C in the solid state [5]. On the other hand, with di-
phosphines P_P the intermediate complexes C could not
be observed, not even at )30 °C [6]. With bipyridine in the
presence of TlPF6, new types of hydroxycarbene com-
plexes intermolecularly stabilized by hydrogen bridges to
* Corresponding author. Tel.: +49-345-55-25620; fax: +49-345-55-
27028.
E-mail address: steinborn@chemie.uni-halle.de (D. Steinborn).
0020-1693/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2003.11.045

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T. Gosavi et al. / Inorganica Chimica Acta 357 (2004) 1781–1788
2. Results and discussion
2.1. Reactions of platina-b-diketone with chelating N,N-
ligands
The platina-b-diketone 1 was found to react with
chelating N,N-ligands (E)-2-(R0N@CR)C5H4N (R/
R0 ¼ Ph/OH, H/Ph, Me/Ph) having pyridine type and
Schiff base/oxime donor centers in a molar ratio 1:2 in
tetrahydrofuran as solvent to give acyl(hydrido)plati-
num(IV) complexes [Pt(COMe)2Cl(H){2-(R0N@CR)
C5H4N}](2a–c) in yields between 36% and 48% (Scheme
3). Under the same reaction conditions, the analogous
reaction with an aldoxime, (E)-2-(HO–N@CH)C5H4N,
did not proceed so selective: The acyl(hydrido)plati-
num(IV) complex [Pt(COMe)2Cl(H){2-(HO–N@CH)
C5H4N}] and platinum(II) complexes (most likely
Scheme 1.
[Pt(COMe)Cl{2-(HO–N@CH)C5H4N}]
and
[Pt-
(COMe)2{2-(HO–N@CH)C5H4N}]) were obtained in
various amounts in an erratic manner.
The platinum(IV) complexes 2a–c were isolated as
slightly air-sensitive off-white (2a) or pale yellow (2b/c)
microcrystalline substances. In the solid state they de-
compose with melting between 104 and 168 °C while in
chloroform solution they undergo decomposition within
several hours at room temperature. Identities of com-
plexes 2a–c were confirmed by microanalysis as well as
by IR and NMR (1H, 13C) spectroscopy.
Scheme 2.
The presence of hydrido ligand in 2a–c is clearly
1
confirmed by their H NMR and IR spectra, showing
highfield Pt–H resonances from )17.50 to )18.67 ppm
and sharp IR absorption bands between 2225 and 2264
cmꢀ1, being consistent with data in analogous com-
plexes [Pt(COMe)2Cl(H)(N_N)] (5, N_N ¼ bipyridine/
phenanthroline type ligand) [5] and with data of other
complexes with terminal hydrido ligands [10]. The large
values of the 1J(Pt,H) coupling constant (1563–1585 Hz)
are characteristic for hydrido ligands trans to nitrogen
ligands in platinum(IV) complexes [5,11–13]. The two
acetyl groups are NMR spectroscopically non-equiva-
lent, 1H and 13C chemical shifts of acetyl ligands in
complexes 2 (d(1HMe) 2.22–2.96 ppm; d(13CMe) 43.8–
46.5 ppm; d(13CCO) 190.3–206.6 ppm) are in the ex-
pected range as compared with other Pt(IV) complexes
of this type [5]. By means of HMBC experiments it was
shown for complexes 2b and 2c that acetyl group pro-
acetyl ligands were obtained (E, F; Scheme 2) [7]. Reac-
tions with diazadiene type ligands RN@CR0–CR0@NR
afforded in dependence on substituents R and R0 either
type D complexes (via intermediates of type C) or com-
plexes G. These complexes contain en-amine-amide type
ligands that are formally obtained by 1,4-addition of
MeC(O)–H (a tautomer of hydroxycarbene Me–C–OH
that is a building block of platina-b-diketone 1) to
diazadienes [8].
To get further insight into the reactivity, we investi-
gated reactions of the platina-b-diketone 1 with biden-
tate donors having hard/hard, soft/soft and hard/soft
donor centers. We used here chelating N,N-donors 2-
(R0N@CR)C5H4N (R/R0 ¼ Ph/OH, H/Ph, Me/Ph) hav-
ing a pyridine type and a Schiff base/oxime donor site,
chelating S,S-donors RS–CH2–CH2–SR (R ¼ Et, Ph, t-
Bu) being bis(thioethers) and chelating N,S-ligands 2-
(RSCH2)C5H4N (R ¼ Et, Ph, t-Bu). These are ‘‘mixed’’
ligands of the former two types having a pyridine N
atom and a thioether S atom as donor sites. The results
gave evidence that hard donors like N tend to react
yielding stable platinum(IV) type C complexes whereas
soft donors like S tend to react yielding platinum(II)
type D complexes. Part of this work has been prepub-
lished in a Conference Issue [9].
Scheme 3.

T. Gosavi et al. / Inorganica Chimica Acta 357 (2004) 1781–1788
1783
1
Me
Pt
Me
Pt
tons which are higher shifted in H NMR spectra cor-
respond to higher-field shifted methyl and acyl carbon
atoms in 13C NMR spectra as it is also the case in
analogous complexes [Pt(COMe)2Cl(H)(N_N)] (5,
N_N ¼ bipyridine/phenanthroline type ligand) [5].
3J(Pt,H) coupling constants of acetyl hydrogens are in
O
H
O
O
O
Cl
Cl
R
S
S
R
S
S
R
H
1/2
R
thf
Pt
Cl
COMe
Me
Me
3
1
3b
Ph
35
3c
3a
Et
41
R
t
-Bu
yield/%
43
1
2
the range of 26–34 Hz. J(Pt,C) and J(Pt,C) coupling
constants are in the range of 836–895 and 209–305 Hz,
respectively. Differences in coupling constants between
the two acetyl groups (trans to N versus trans to Cl)
amount to D1J(Pt,C) 17–43 Hz and D2J(Pt,C) 55–77 Hz.
On the basis of the well-known dependence of the
magnitudes of 1J(Pt,C) and 2J(Pt,C) coupling constants
on trans influence of ligands [14] the acetyl groups with
lower carbon–platinum coupling constants are trans to
N atom and those with higher carbon–platinum cou-
pling constants trans to chloro ligand. The Pt–Cl and
C@O stretching vibrations were found in the range of
252–264 and 1592–1702 cmꢀ1, respectively.
Scheme 4.
pected range as compared with other Pt(II) complexes of
the type [Pt(COMe)(Cl)L2] (L2 ¼ Ph2P(CH2)nPPh2,
n ¼ 2, 3 (6) [6]; L2 ¼ 4,40-R2bpy, R ¼ H, Me, t-Bu (7))
[5,15]. The donor capability of sulfur atoms in ligands
RS–CH2–CH2–SR is expected to be R ¼ t-Bu > Et > Ph
1
2
but the magnitudes of J(Pt,C) and J(Pt,C) coupling
constants (844–869 and 114–122 Hz, respectively) in
complexes 3a–c are not clearly dependent on that.
Full assignment of all hydrogen and carbon atoms in
complex 3a (R ¼ Et) was done by means of COSY
(1H,1H; 1H,13C) and NOE experiments (see formula,
chemical shifts dC are given, dH, see Section 3).
Thus, from NMR investigations it follows undoubt-
less that the hydrido ligand is trans to N and the chloro
ligand trans to an acetyl ligand. The narrow range of
hydride chemical shifts ()17.50 to )18.67 ppm) and
1J(Pt,H) coupling constants (1563–1585 Hz) and the
close correspondence of these values to those in com-
30.5
4
36.5
3
H2C
CH2
13.6 29.5
31.6 13.2
6
5
2
1
1
plexes 5 (d(PtH) )17.50 to )18.77 ppm; J(Pt,H) 1474–
CH2 CH3
CH3 CH2
S
S
3a
1582 Hz [5]) indicates that the hydrido ligand is trans to
the pyridine N atom (2 in Scheme 1) but the diastereo-
mer 20 in Scheme 3 (H ligand trans to Schiff base/oxime
N atom) cannot strictly be ruled out. Reactions ac-
cording to Scheme 3 proved to be strongly regioselective
as in all cases only one diastereomer (probably 2,
Scheme 3) was obtained. In contrast, analogous reac-
tions with non-symmetrically substituted bipyridine/
phenanthroline ligands yielding complexes [Pt(COMe)2-
Cl(H)(N_N)] (5) proved to be regioselective only with
ortho-substituted bipyridine/phenanthroline ligands [5].
Pt
Cl
COCH3
214.8 41.9
Formula 3a
Irradiation in the resonance frequency of acetyl protons
led to distinguish between the two methyl groups (nos. 1
and 6, see formula; positive NOE for C1H3) of the ethyl
substituents which was confirmed by irradiation in the
resonances of these protons. Irradiation in the resonances
of methyl protons of ethyl groups led to distinguish be-
tween the methylene protons 2/3 and 4/5. H,1H COSY
1
2.2. Reactions of platina-b-diketone with chelating S,S-
ligands
experiments made clear which methylene protons belong
to the ethyl substituents (2 and 5) and which ones to the
ethylene bridge CH2–CH2 (3 and 4). Finally, 1H,13C
COSY experiments gave the assignments of the carbon
atoms. The highly electronegative chloro ligand gives rise
to lowfield shift of carbon atoms attached to S trans to Cl
by 2.1 ppm (2 versus 5) and 6.0 ppm (3 versus 4).
Reactions of the platina-b-diketone 1 with chelating
S,S-ligands RS–CH2–CH2–SR (R ¼ Et, Ph, t-Bu) in a
molar ratio 1:2 in tetrahydrofuran as solvent afforded
acyl(chloro)platinum(II) complexes [Pt(COMe)Cl(RS-
CH2CH2SR)] (3) in yields of 35–43% (Scheme 4). The
platinum(II) complexes 3a–c were isolated as slightly
air-sensitive off-white microcrystalline substances. They
melt with decomposition between 110 and 133 °C. Their
identities were confirmed by microanalysis, IR (m(Pt–Cl)
316–325 cmꢀ1, m(C@O) 1633–1657 cmꢀ1), and NMR
(1H, 13C) spectroscopic measurements and for 3b by X-
ray structure analysis, too.
Molecular structure of complex 3b was determined by
single-crystal X-ray diffraction analysis, see Fig. 1. Se-
lected bond lengths and angles are listed in Table 1. The
complex crystallizes as discrete molecules without unusual
intermolecular contacts (shortest intermolecular contact
0
ꢀ
between non-hydrogen atoms: Oꢁ ꢁ ꢁC7 3.327(6) A).
The geometry at platinum center is close to square
planar (angles at Pt: 87.3(1)–93.09(3) °; sum of angles
360.0 °; greatest deviation of the mean square plane
1H and 13C chemical shifts of the acetyl ligands in
complexes 3 (d(1HMe) 2.36–2.47 ppm; d(13CMe) 41.4–
42.1 ppm; d(13CCO) 209.1–214.8 ppm) are in the ex-
ꢀ
Pt,S1,S2,Cl,C1 for the Pt atom by 0.0195(2) A). The Pt–
ꢀ
C1 bond length (2.012(4) A) as well as the C–O bond

1784
T. Gosavi et al. / Inorganica Chimica Acta 357 (2004) 1781–1788
Me
Me
Pt
O
H
O
O
O
Cl
Cl
N
S
R
N
S
R
Pt
Me
H
1/2
thf
Pt
Cl
COMe
Me
4
1
4b
Ph
47
4c
4a
Et
47
R
t-Bu
yield/%
47
Scheme 5.
microcrystalline substances that melt with decomposi-
tion between 110 and 144 °C. Their identities were
confirmed by microanalysis, IR, and NMR (1H, 13C)
spectroscopy and for 4b also by X-ray structure analysis.
The Pt–Cl and C@O stretching vibrations were ob-
served at 318–320 and 1634–1642 cmꢀ1, respectively.
The methylene protons of the py–CH2–S bridge are not
chemical shift equivalent. They show AB spin patterns
Fig. 1. Molecular structure of [Pt(COMe)Cl(PhSCH2CH2SPh)] (3b)
showing the numbering scheme (displacement ellipsoids at 30%
probability).
2
Table 1
with magnitudes of J(HA,HB) coupling constants be-
tween 16 and 17 Hz. The lines of the highfield shifted
protons (HA) are flanked by platinum satellites
ꢀ
Selected bond lengths (A) and angles (°) for [Pt(COMe)Cl
(PhSCH2CH2SPh)] (3b)
3þ4J(Pt,HA) 66–71 Hz). The carbon chemical shifts
Pt–C1
Pt–Cl
C1–O
2.012(4)
2.3207(9)
1.188(5)
Pt–S1
Pt–S2
2.2563(9)
2.457(1)
(
d(13CCO) (207.3–209.7 ppm) and the couplings J(Pt,C)
(867/890 Hz) in complexes 4 with N,S co-ligands show
greater differences both to the corresponding values in
the analogous complexes with S,S co-ligands (3) and to
those with the bipyridine complex [Pt(COMe)Cl(bpy)]
(8) [15] chosen as a representative for N,N co-ligands:
1
C1–Pt–S1
S1–Pt–S2
S1–Pt–Cl
90.1(1)
89.50(3)
177.08(3)
C1–Pt–Cl
S2–Pt–Cl
S2–Pt–C1
87.3(1)
93.09(3)
178.8(1)
d(13CCO) N_S (4) < S_S (3) < N_N (8); J(Pt,C) S_S
1
(3) < N_S (4) ꢂ N_N (8). Thus, from these measure-
ments it cannot be decided unambiguously whether the
acetyl ligand in complexes 4 is trans to N (configuration
index SP-4-2) or to S (configuration index SP -4-3). For
4b X-ray diffraction analysis revealed that the acetyl li-
gand is trans to N. Furthermore, in no experiment was
found any indication of formation of isomeric mixtures.
The molecular structure of complex 4b is shown in
Fig. 2. Selected bond lengths and angles are listed in
Table 2. The complex crystallizes as discrete molecules
without unusual intermolecular contacts between them
(shortest intermolecular contact between non-hydrogen
ꢀ
length (1.188(5) A) are in the range of those found in
other acylplatinum(II) complexes (Pt–C: median 2.029
ꢀ
A, lower/higher quartile 1.988/2.056 A; C–O 1.221 A,
ꢀ
ꢀ
ꢀ
lower/higher quartile 1.193/1.242 A; 37 observations)
[16]. The five-membered PtS2C2-ring has a half-chair
conformation twisted on C3–C4; the phenyl substituents
occupy axial positions. The plane of the acetyl ligand is
nearly perpendicular to the complex plane (interplanar
angle: 86.9(5)°). In accord with the trans influence
Cl ꢂ COMe, the Pt–S bond trans to chloro ligand is
distinctly shorter than that trans to the acetyl ligand
ꢀ
(2.2563(9) versus 2.457(1) A).
0
ꢀ
atoms: Oꢁ ꢁ ꢁC7 3.16(2) A). The complex exhibits a
square-planar geometry (angles at Pt: 83.2(1)–94.5(1)°,
sum of angles 360.1°; greatest deviation of the mean
2.3. Reactions of platina-b-diketone with chelating N,S-
ligands
ꢀ
square plane Pt,N,S,Cl,C1 for the S atom by 0.057(2) A)
Finally, we investigated the reactivity of the platina-
b-diketone 1 with chelating N,S-ligands 2-(RSCH2)-
C5H4N (R ¼ Et, Ph, t-Bu) built up of a pyridine type
and a thioether donor center, thus being the ‘‘mixed’’
ligands between the former two chelate ligands. The
reactions proceeded in a molar ratio 1:2 in tetrahydro-
furan yielding acyl(chloro)platinum(II) complexes
[Pt(COMe)Cl{2-(RSCH2)C5H4N}] (4) in yields of 47%
(Scheme 5).
with the acetyl ligand trans to the pyridine N atom. The
five-membered PtNSC2-ring has an envelope confor-
mation on S; the phenyl substituent is axially oriented.
The interplanar angle between the acetyl ligand and the
complex plane is 65.9(8)°.
As for complex 3b, in complex 4b the Pt–C1 and C–O
ꢀ
bond lengths (1.997(6) and 1.185(8) A, respectively) are
in the expected range. As expected, the Pt–S bond in
complex 4b has the same length as the Pt–S bond trans
ꢀ
to Cl in complex 3b (2.257(2) versus 2.2563(9) A). On
the other hand, the Pt–C1 bond length is not strongly
The platinum(II) complexes 4a–c were isolated as
slightly air-sensitive off-white (4a/c) or pale yellow (4b)

T. Gosavi et al. / Inorganica Chimica Acta 357 (2004) 1781–1788
1785
dried (Et2O and thf over Na–benzophenone) and dis-
1
tilled prior to use. H and 13C NMR spectra were re-
corded on Varian Gemini 200 and Varian VXR 400
NMR spectrometers. Chemical shifts are relative to
CHCl3 (d 7.24) and CDCl3 (d 77.0) as internal refer-
ences. Assignments of NMR signals were partly revealed
1
by COSY experiments (1H,1H; H,13C) and by running
spectra in APT mode. IR spectra were recorded on a
Galaxy FT-IR spectrometer Mattson 5000 using CsBr
pellets. Microanalysis were performed by the University
of Halle microanalysis laboratory using CHNS-932
(LECO) and Vario EL (elementar Analysensysteme)
elemental analyzers. The complex [Pt2{(COMe)2H}2(l-
Cl)2] (1) was synthesized according to a published
method [3]. Phenyl(pyridin-2-yl)ketone-(E)-oxime, 2-
pyridine aldoxime and 1,2-bis(phenylthio)ethane were
commercially available, the other N_N [18–20], S_S
[21] and N_S ligands [22,23] were prepared according to
published methods.
Fig. 2. Molecular structure of [Pt(COMe)Cl{2-PhSCH2)C5H 4N}](4b)
showing the numbering scheme (displacement ellipsoids at 30%
probability).
3.2. Syntheses
Table 2
ꢀ
Selected bond lengths (A) and angles (°) for [Pt(COMe)Cl{2-
PhSCH2)C5H4N}](4b)
3.2.1. Preparation of complexes [Pt(COMe)2Cl(H){2-
(R0N@CR)C5H4N)}] (2)
Pt–C1
Pt–Cl
C1–O
1.997(6)
2.320(2)
1.185(8)
Pt–N
Pt–S
2.190(5)
2.257(2)
To a suspension of [Pt2{(COMe)2H}2(l-Cl)2] (1) (50
mg, 0.08 mmol) in thf (4 ml) cooled down to )40 °C
ligand 2-(R0N@CR)C5H4N (0.16 mmol) was added. The
pale yellow suspension immediately changed the color to
intense yellow colored solution. The reaction mixture
was warmed up to room temperature. Seventy percent
of total volume of thf was removed in vacuo. Then di-
ethyl ether (10–15 ml) was added resulting in an off-
white/pale yellow precipitate that was filtered off,
washed with diethyl ether (5 ml) and dried briefly in
vacuo.
C1–Pt–S
N–Pt–S
S–Pt–Cl
92.8(2)
83.2(1)
176.15(6)
C1–Pt–Cl
N–Pt–Cl
N–Pt–C1
89.6(2)
94.5(1)
175.2(2)
ꢀ
dependent on the trans ligand: Pt–Ctrans to py 1.997(6) A
ꢀ
(4b) ꢃ Pt–Ctrans to SPh 2.012(4) A (3b).
In many reactions, platina-b-diketones were found to
react as hydroxycarbene complexes stabilized by hydro-
gen bridges. Thus, formation of acyl(hydrido)plati-
num(IV) complexes 2 can be understood as ligand
induced oxidative addition reaction of a hydroxycarbene
ligand. Likely, formation of acylplatinum(II) complexes
3 and 4 using chelating S_S and N_S ligands proceeded
via (unseen) platinum(IV) intermediates that underwent
readily reductive elimination of acetaldehyde analo-
gously to Scheme 2 (1 ! C ! D; L_L ¼ RS–CH2–
CH2–SR, 2-(RSCH2)C5H4N). The marked contrast of
reactions using N_N ligands on the one side and S_S/
N_S ligands on the other side gives further support for
the generalization that platinum(IV) complexes are more
stable with hard co-ligands than with soft ones [17].
Complex 2a (R ¼ Ph, R0 ¼ OH). Yield: 30 mg (36%);
m.p. 166–168 °C (dec.). Anal. Calc. for C16H17ClN2O3Pt
(515.87): C, 37.25; H, 3.32; N, 5.43. Found: C, 36.08; H,
3.49; N, 5.24%. IR(CsBr): m(Pt–H) 2260, m(C@O) 1702,
1
1679, m(Pt–Cl) 264 cmꢀ1. H NMR (400 MHz, CDCl3):
d ¼ ꢀ17:50 (s + d, 1J(Pt,H) ¼ 1566.92 Hz, 1H, PtH),
2.34 (s + d, 3J(Pt,H) ¼ 26.29 Hz, 3H, COCH3), 2.96
(s + d, 3J(Pt,H) ¼ 33.84 Hz, 3H, COCH3), 7.46–7.58 (m,
7H,
o,m,p-HPh + 3-CHpy + 5-CHpy),
7.91
(ddd,
3J(H4,H5) ¼ 3J(H4,H3) ¼ 7.85 Hz, 4J(H4,H6) ¼ 1.54
Hz, 1H, 4-CHpy), 8.93 (dd, 3J(H6,H5) ¼ 5.36 Hz,
4J(H6,H4) ¼ 0.97 Hz, 1H, 6-CHpy), 13.28 (s + d,
3J(Pt,H) ¼ 20.93 Hz, 1H, N–OH). 13C NMR (101 MHz,
2
CDCl3): d ¼ 43:8 (s + d, J(Pt,C) ¼ 283.1 Hz, COCH3),
2
46.2 (s + d, J(Pt,C) ¼ 208.7 Hz, COCH3), 126.8/126.9
3. Experimental
(s/s, 3/5-Cpy), 128.9 (s, i-CPh), 129.0/130.8 (s/s, o,m,p-
CPh), 139.6 (s, 4-Cpy), 152.6 (s, 2-Cpy), 152.7 (s, 6-Cpy),
157.4 (s, C@NOH), 190.3 (s + d, 1J(Pt,C) ¼ 835.9 Hz,
3.1. General
1
COCH3), 206.6 (s + d, J(Pt,C) ¼ 872.8 Hz, COCH3).
All reactions were performed under an Ar atmo-
sphere using standard Schlenk techniques. Solvents were
Complex 2b (R ¼ H, R0 ¼ Ph). Yield: 38 mg (48%);
m.p. 104–106 °C (dec.). Anal. Calc. for C16H17ClN2O2Pt

1786
T. Gosavi et al. / Inorganica Chimica Acta 357 (2004) 1781–1788
(499.87): C, 38.45; H, 3.43; N, 5.60. Found: C, 38.55; H,
3.44; N, 5.23%. IR(CsBr): m(Pt–H) 2264, m(C@O) 1663,
added. Stirring the reaction mixture for two days (3b,
R ¼ Ph) and one day (3c, R ¼ t-Bu), respectively, re-
sulted in formation of a white powdery precipitate (3b/c)
that was filtered off, washed with diethyl ether (5 ml) and
dried briefly in vacuo. In the case of 3a (R ¼ Et) an oily
mass sticked on the walls of the Schlenk tube was ob-
tained. The mixture was kept at )40 °C for 3 days
yielding a white powdery precipitate that was isolated as
described above.
1
1592, m(Pt–Cl) 257 cmꢀ1. H NMR (400 MHz, CDCl3):
d ¼ ꢀ18:54 (s + d, 1J(Pt,H) ¼ 1584.59 Hz, 1H, PtH),
2.22 (s + d, 3J(Pt,H) ¼ 30.36 Hz, 3H, COCH3), 2.95
(s + d, 3J(Pt,H) ¼ 30.69 Hz, 3H, COCH3), 7.37–7.44 (m,
3H, o,p-HPh), 7.64–7.67 (m, 3H, m-HPh + 5-CHpy), 7.96–
8.02 (m, 2H, 3-CHpy + 4-CHpy), 8.80 (s + d, 3þ4J
(Pt,H) ¼ 24.05
Hz,
1H,
CH@N),
9.42
(d,
3J(H6,H5) ¼ 5.05 Hz, 1H, 6-CHpy). 13C NMR (126
MHz, CDCl3): d ¼ 43:9 (s + d, 2J(Pt,C) ¼ 294.1 Hz,
COCH3), 46.3 (s + d, 2J(Pt,C) ¼ 239.0 Hz, COCH3),
122.8 (s, m-CPh), 128.8 (s, 5-Cpy), 129.3/129.5 (s, o,p-
CPh + 3-Cpy), 139.5 (s, 4-Cpy), 147.4 (s, i-CPh), 150.7 (s,
6-Cpy), 154.1 (s, 2-Cpy), 163.7 (s, CH@N), 191.2 (s + d,
Complex 3a (R ¼ Et). Yield: 28 mg (41%); m.p. 110–
112 °C (dec.). Anal. Calc. for C8H17ClOPt S2 (423.90):
C, 22.67; H, 4.04. Found: C, 22.55; H, 3.87%.
1
IR(CsBr): m(C@O) 1633, m(Pt–Cl) 320 cmꢀ1. H NMR
(500 MHz, CDCl3): d 1.32 (t, 3H, H1), 1.40 (t, 3H,
H6), 2.40 (s, 3H, COCH3), 2.60–2.68 (m, 1H, H4a),
2.71–2.79 (m, 1H, H4b), 2.82–2.91 (m, 3H, H5a/5b,
H2a), 2.93–2.99 (m, 1H, H3a), 3.00–3.05 (m, 1H, H3b),
3.07–3.13 (m, 1H, H2b). 13C NMR (126 MHz, CDCl3):
d 13.2 (s + d, 3J(Pt,C) ¼ 69.9 Hz, C1, one of the two
platinum satellites is partially overlapped with neigh-
boring signal at d 13.6), 13.6 (s, C6), 29.5 (s, C5), 30.5
(s, C4), 31.6 (s, C2), 36.5 (s, C3), 41.9 (s + d,
1J(Pt,C) ¼ 885.8 Hz, COCH3), 194.9 (s + d, J(Pt,C) ¼
1
869.0 Hz, COCH3). Overnight measurement at room
temperature to identify Pt–C coupling constants resulted
in partly decomposition due to restricted stability of
complex.
Complex 2c (R ¼ Me, R0 ¼ Ph). Yield: 38 mg (46%);
m.p. 128–130 °C (dec.). Anal. Calc. for C17H19ClN2O2Pt
(513.90): C, 39.73; H, 3.73; N, 5.45. Found: C, 39.87; H,
3.72; N, 5.48%. IR(CsBr): m(Pt–H) 2225, m(C@O) 1663,
2J(Pt,C) ¼ 121.7
Hz,
COCH3),
214.8
(s + d,
1J(Pt,C) ¼ 869.2 Hz, COCH3). Assignments were ad-
ditionally verified by NOE experiments. Numbering
scheme see formula on p. xx.
1
1594, m(Pt–Cl) 252 cmꢀ1. H NMR (400 MHz, CDCl3):
d ¼ ꢀ18:67 (s + d, 1J(Pt,H) ¼ 1562.67 Hz, 1H, PtH),
3
2.24 (s + d, J(Pt,H) ¼ 32.21 Hz, 3H, COCH3), 2.42 (s,
Complex 3b (R ¼ Ph). Yield: 29 mg (35%); m.p. 131–
133 °C (dec.). Anal. Calc. for C16H17ClOPtS2 (519.99):
C, 36.96; H, 3.30. Found: C, 35.90; H, 3.48%. IR(CsBr):
3
3H, C(CH3)@N), 2.88 (s + d, J(Pt,H) ¼ 28.63 Hz, 3H,
COCH3), 7.22 (broad, 2H, o-HPh), 7.28–7.32 (m, 1H, p-
HPh), 7.41–7.45 (m, 2H, m-HPh), 7.76 (ddd, 3J(H5,
1
m(C@O) 1657, m(Pt–Cl) 325 cmꢀ1. H NMR (400 Hz,
3
4
H4) ¼ 7.58 Hz, J(H5,H6) ¼ 5.37 Hz, J(H5,H3) ¼ 1.37
CDCl3): d ¼ 2:36 (s, 3H, COCH3), ca. 2.6/3.0/3.2 (m/m/
m, 1H/2H/1H, CH2CH2), 7.40–7.49 (m, 6H, HPh), 7.93–
7.99 (m, 4H, HPh). 13C NMR (100 Hz, CDCl3): d ¼ 36:4
(s, CH2), 41.4 (s + d, 2J(Pt,C) ¼ 114.1 Hz, COCH3), 44.8
(s, CH2), 128.9 (s, i-CPh), 129.0 (s, i-CPh), 129.7/132.7/
133.1 (s/s/s, 2 ꢄ o,m-C), 130.0/131.3 (s/s, 2 ꢄ p-C), 209.1
3
Hz, 1H, 5-CHpy), 8.01 (d, J(H3,H4) ¼ 7.37 Hz, 1H, 3-
CHpy), 8.13 (ddd, 3J(H4,H5) ¼ 3J(H4,H3) ¼ 7.79 Hz,
4J(H4,H6) ¼ 1.54 Hz, 1H, 4-CHpy), 9.50 (ddd, J(H6,
3
4
5
H5) ¼ 4.21 Hz, J(H6,H4) ¼ 2.64 Hz, J(H6,H3) ¼ 1.16
Hz, 1H, 6-CHpy). 13C NMR (126 MHz, CDCl3): d ¼
18:5 (s, C(CH3)@N), 44.2 (s + d, 2J(Pt,C) ¼ 304.7 Hz,
COCH3), 46.5 (s + d, 2J(Pt,C) ¼ 227.4 Hz, COCH3),
121.3 (s, o-CPh), 127.2 (s, p-CPh), 127.6 (s, 3-Cpy), 128.1
(s, 5-Cpy), 129.4 (s, m-CPh), 139.5 (s, 4-Cpy), 148.1 (s, i-
CPh), 150.6 (s, 6-Cpy), 154.7 (s, 2-Cpy), 172.3 (s,
C(CH3)@N), 191.9 (s + d, 1J(Pt,C) ¼ 894.9 Hz, CO-
CH3), 197.5 (s + d, 1J(Pt,C) ¼ 852.2 Hz, COCH3).
Overnight measurement resulted in partly decomposi-
tion, see 2b.
1
(s + d, J(Pt,C) ¼ 851.1 Hz, COCH3).
Complex 3c (R ¼ t-Bu). Yield: 33 mg (43%); m.p.
120–122 °C (dec.). Anal. Calc. for C12H25ClOPtS2
(480.00): C, 30.03; H, 5.25. Found: C, 29.86; H, 5.27%.
1
IR(CsBr): m(C@O) 1638, m(Pt–Cl) 316 cmꢀ1. H NMR
(400 MHz, CDCl3): d ¼ 1:41 (s, 9H, C(CH3)3), 1.55 (s,
9H, C(CH3)3), 2.47 (s, 3H, COCH3), 2.58–2.70 (broad,
2H, CH2), 2.83–2.97 (broad, 2H, CH2). 13C NMR (101
MHz, CDCl3): d ¼ 28:9 (s, CMe3), 30.0 (s, C(CH3)3),
30.6 (s, C(CH3)3), 35.6 (s + d, 2J(Pt,C) ¼ 28.6 Hz,
2
CMe3), 42.1 (s + d, J(Pt,C) ¼ 120.2 Hz, COCH3), 50.8
(s, CH2), 52.8 (s, CH2), 212.7 (s + d, 1J(Pt,C) ¼ 843.7
Hz, COCH3).
3.2.2. Preparation of complexes [Pt(COMe)Cl(RS-
CH2CH2SR)] (3)
To a suspension of [Pt2{(COMe)2H}2(l-Cl)2] (1) (50
mg, 0.08 mmol) in thf (4 ml) cooled down to )40 °C
ligand RS–CH2–CH2–SR (0.16 mmol) was added. The
pale yellow suspension immediately changed the color to
colorless. The reaction mixture was warmed up to room
temperature. Seventy percent of total volume of thf was
removed in vacuo. Then diethyl ether (10–15 ml) was
3.2.3. Preparation of complexes [Pt(COMe)Cl{2-
(RSCH2)C5H4N}] (4)
To a suspension of [Pt2{(COMe)2H}2(l-Cl)2] (1) (50
mg, 0.08 mmol) in thf (4 ml) cooled down to )40 °C
ligand 2-(RSCH2)C6H4N (0.16 mmol) was added. The

T. Gosavi et al. / Inorganica Chimica Acta 357 (2004) 1781–1788
1787
Table 3
Crystallographic and data collection parameters for compounds 3b
and 4b
pale yellow suspension immediately changed the color to
colorless. The reaction mixture was warmed up to room
temperature. Seventy percent of total volume of thf was
removed in vacuo. Then diethyl ether (10–15 ml) was
added resulting in formation of an oily mass. The mix-
ture was kept at )40 °C for 3 days yielding an off-white/
pale yellow powdery precipitate that was filtered off,
washed with diethyl ether (5 ml) and dried briefly in
vacuo.
3b
4b
Empirical formula
Mr
C16H17ClOPtS2
519.96
C14H14ClNOPtS
474.86
Crystal size (mm)
Crystal system
Space group
0.18 ꢄ 0.10 ꢄ 0.04 0.20 ꢄ 0.20 ꢄ 0.10
monoclinic
P21c
monoclinic
C2=c
ꢀ
a (A)
14.3497(15)
8.8594(10)
13.3439(14)
90.131(2)
1696.1(3)
4
21.855(3)
8.670(1)
15.770(2)
90.42(3)
2988.1(7)
8
ꢀ
b (A)
Complex 4a (R ¼ Et). Yield: 32 mg (47%); m.p. 110–
112 °C (dec.). Anal. Calc. for C10H14ClNOPtS (426.84):
C, 28.14; H, 3.31; N, 3.28. Found: C, 28.05; H, 3.34; N,
ꢀ
c (A)
b (°)
V (A )
3
ꢀ
1
3.34%. IR(CsBr): m(C@O) 1634, m(Pt–Cl) 320 cmꢀ1. H
Z
3
Dcalc (g cmꢀ1
)
2.036
8.672
992
2.111
9.700
1792
NMR (400 MHz, CDCl3): d ¼ 1:30 (t, J(H,H) ¼ 7.42
l(Mo Ka) (mmꢀ1
)
Hz, 3H, CH2CH3), 2.42 (s, 3H, COCH3), 2.84 (m, 2H,
S–CH2CH3), 4.14 (HA)/4.43 (HB) (AB pattern + dd for
HA,2J(HA,HB) ¼ 16.60 Hz, 3 þ 4J(Pt,HA) ¼ 68.06 Hz,
2H, CHAHBSEt), 7.41 (t, 3J(H,H) ¼ 6.54 Hz, 1H, 5-
F ð000Þ
h range (°)
1.42–28.01
10 757
3277
2.84–25.94
8517
2601
Reflections collected
Reflections observed
[I > 2rðIÞ]
3
CHpy), 7.50 (d, J(H,H) ¼ 7.62 Hz, 1H, 3-CHpy), 7.86
(td, 3J(H,H) ¼ 7.71 Hz, 4J(H,H) ¼ 1.69 Hz, 1H, 4-
CHpy), 9.28 (dd, 3J(H,H) ¼ 5.47, 4J(H,H) ¼ 0.98 Hz,
1H, 6-CHpy). 13C NMR (126 MHz, CDCl3): d ¼ 13:2
(s + d, 3J(Pt,C) ¼ 63.2 Hz, CH2CH3), 34.0 (s + d,
2J(Pt,C) ¼ 25.4 Hz, CH2CH3), 42.7 (s, CH2SEt), 43.2
Reflections independent
3989 (0.0379)
2845 (0.0728)
(Rint
)
Data/restraints/parameters 3850/0/190
2805/0/172
0.984
Goodness-of-fit on F 2
R1; wR2½I > 2rðIÞꢅ
R1; wR2 (all data)
0.968
0.0234, 0.0484
0.0336, 0.0515
0.0464, 0.1195
0.0499, 0.1262
2
Largest diffꢀer3ence peak and 0.908 and )0.886 3.592 and )2.624
(s + d, J(Pt,C) ¼ 109.8 Hz, COCH3), 123.1 (s, 3-Cpy),
ꢀ
hole (e A
)
(near Pt atom)
124.1 (s, 5-Cpy), 138.8 (s, 4-Cpy), 149.4 (s, 6-Cpy), 157.1
(s + d, 2J(Pt,C) ¼ 64.7 Hz, 2-Cpy), 208.5 (s + d,
1J(Pt,C) ¼ 889.9 Hz, COCH3).
4.88 Hz, 1H, 6-CHpy). 13C NMR (101 MHz, CDCl3): d
29.9 (s + d, 3J(Pt,C) ¼ 32.5 Hz, C(CH3)3), 42.0 (s + d,
2J(Pt, C) ¼ 23.6 Hz, CH2S), 43.9 (s + d, 2J(Pt,C) ¼ 103.8
Hz, CMe3), 53.6 (s, COCH3), 122.7 (s, 3-Cpy), 124.3 (s,
5-Cpy), 139.4 (s, 4-Cpy), 149.5 (s, 6-Cpy), 158.4 (s + d,
3J(Pt,C) ¼ 72.6 Hz, 2-Cpy), 209.7 (s + d, 1J(Pt,C) ¼ 866.9
Hz, COCH3).
Complex 4b (R ¼ Ph). Yield: 36 mg (47%); m.p. 142–
144 °C (dec.). Anal. Calc. for C14H14ClNOPtS (474.88):
C, 35.41; H, 2.97; N, 2.95. Found: C, 35.40; H, 3.15; N,
1
3.04%. IR(CsBr): m(C@O) 1642, m(Pt–Cl) 319 cmꢀ1. H
NMR (400 MHz, CDCl3): d ¼ 2:35 (s, 3H, COCH3),
4.31 (HA)/4.74 (HB) (AB pattern + dd for HA, 2J
(HA,HB) ¼ 16.30 Hz, 3 þ 4J(Pt,HA) ¼ 66.45 Hz, 2H,
CHAHBSPh), 7.31–7.44 (m, 5H, m,p-HPh + 3-CHpy + 5-
CHpy), 7.74 (d, 3J(H,H) ¼ 7.10 Hz, 2H, o-HPh), 7.84 (td,
4
3J(H,H) ¼ 7.73, J(H,H) ¼ 1.25 Hz, 1H, 4-CHpy), 9.34
3.3. X-ray structure determinations
(d,3J(H,H) ¼ 5.02 Hz, 1H, 6-CHpy). 13C NMR (101
MHz, CDCl3): d ¼ 43:5 (s + d, 2J(Pt,C) ¼ 98.9 Hz,
CH2S), 50.4 (s, COCH3), 123.4 (s, 3-Cpy), 124.7 (s, 5-
Cpy), 130.1 (s, m-CPh), 130.8 (s, i-CPh), 131.5 (s, p-CPh),
132.3 (s + d, 3J(Pt,C) ¼ 79.6 Hz, o-CPh), 139.3 (s, 4-Cpy),
Crystals suitable for X-ray diffraction analyses were
grown from mother liquor at room temperature (3b) and
by slow diffusion of diethyl ether into a solution of 4b in
chloroform, respectively. Intensity data were collected
on a Siemens SMART CCD area-detector diffractome-
ter at 218(2) K (3b) and on a STOE IPDS diffractometer
at 203(2) K (4b) using graphite monochromatized Mo-
2
150.0 (s, 6-Cpy), 156.9 (s + d, J(Pt,C) ¼ 67.1 Hz, 2-Cpy),
207.3 (s, COCH3).
Complex 4c (R ¼ t-Bu). Yield: 34 mg (47%); m.p.
140–142 °C (dec.). Anal. Calc. for C12H18ClNOPtS
(454.89): C, 31.69; H, 3.99; N, 3.08. Found: C, 31.12; H,
4.28; N, 3.03%. IR(CsBr): m(C@O) 1637, m(Pt–Cl) 318
cmꢀ1.1H NMR (400 Hz, CDCl3): d ¼ 1:25 (s, 9H,
C(CH3)3), 2.43 (s, 3H, COCH3), 4.19 (HA)/4.49 (HB)
(AB pattern + dd for HA, 2J(HA,HB) ¼ 17.19 Hz,
3 þ 4J(Pt,HA) ¼ 71.10 Hz, 2H, CHAHBS(t-Bu)), 7.38 (t,
3J(H,H) ¼ 6.55 Hz, 1H, 5-CHpy), 7.52 (d,3J(H,H) ¼ 7.81
Hz, 1H, 3-CHpy), 7.85 (td, 3J(H,H) ¼ 7.72 Hz,
4J(H,H) ¼ 1.49 Hz, 1H, 4-CHpy), 9.25 (d, 3J(H,H) ¼
ꢀ
Ka radiation (k ¼ 0:71073 A). A summary of the crys-
tallographic data, the data collection parameters and the
refinement parameters is given in Table 3. The structures
were solved by direct methods with SHELXS 86 [24] and
refined using full-matrix least-squares routines against
F 2 with SHELXL 93 [25]. Non-hydrogen atoms were
refined with anisotropic displacement parameters. All H
atoms were found in the difference Fourier maps and
2
ꢀ
refined isotropically with fixed Uiso ¼ 0:08 A according
to the riding model.

1788
T. Gosavi et al. / Inorganica Chimica Acta 357 (2004) 1781–1788
[6] M. Gerisch, F.W. Heinemann, C. Bruhn, J. Scholz, D. Steinborn,
Organometallics 18 (1999) 564.
4. Supplementary material
[7] D. Steinborn, M. Gerisch, C. Bruhn, J.A. Davies, Inorg. Chem. 38
(1999) 680.
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been de-
posited at the Cambridge Crystallographic Data Center
(CCDC) as Supplementary Publication No. CCDC-
223982 (3b) and No. CCDC-223983 (4b). Copies of the
data can be obtained free of charge on application to the
CCDC, 12 Union Road, Cambridge, CB2 1EZ, U.K.
(fax (internat.): +44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk).
[8] A. Vyater, C. Wagner, K. Merzweiler, D. Steinborn, Organomet-
allics 21 (2002) 4369.
[9] T. Gosavi, C. Wagner, E. Rusanov, H. Schmidt, D. Steinborn,
Monogr. Ser., Int. Conf. Coord. Chem. 6 (2003) 59.
[10] D.M. Roundhill, Adv. Organomet. Chem. 13 (1975) 273.
[11] V. de Felice, A. de Renzi, A. Panunzi, D. Tesauro, J. Organomet.
Chem. 488 (1995) C13.
[12] M.W. Holtcamp, J.A. Labinger, J.E. Bercaw, J. Am. Chem. Soc.
119 (1997) 848.
[13] I.C.M. Wehman-Ooyevaar, D.M. Grove, P. de Vaal, A. Dedieu,
G. Van Koten, Inorg. Chem. 31 (1992) 5484.
[14] T.G. Appleton, H.C. Cark, L.E. Manzer, Coord. Chem. Rev. 10
(1973) 335.
Acknowledgements
[15] M. Gerisch, C. Bruhn, A. Vyater, J.A. Davies, D. Steinborn,
Organometallics 17 (1998) 3101.
We gratefully acknowledge support by the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen
Industrie. We also thank the companies Merck
(Darmstadt) and Degussa (Hanau) for gifts of
chemicals.
[16] Cambridge Structural Database (CSD): Cambridge Crystallo-
graphic Data Centre, University Chemical Laboratory, Cam-
bridge, UK.
[17] R.L. Rendina, R.J. Puddephatt, Chem. Rev. 97 (1997) 1735.
[18] R.W. Hay, K. Nolan, J. Chem. Soc., Dalton Trans. (1976) 548.
[19] B. Schnell, J. Heterocyclic Chem. 36 (1999) 541.
€
[20] E. Denecke, K. Muller, T. Bluhm, Org. Magn. Reson. 18 (1982)
68.
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