Synthesis and properties of the first disulfur and diselenium complexes of platinum

Article abstract of DOI:10.1080/10426500490428906

The reactions of overcrowded platinum(0) complexes [Pt{P(Ar)Me ₂}₂] (Ar = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt), 2,6-bis[bis-(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt)) with elemental sulfur and selenium resulted in the formation of the first platinum disulfur and diselenium complexes, [Pt(S₂){P(Ar)Me ₂}₂] (4a (Ar = Tbt), 4b (Ar = Bbt) and [Pt(Se ₂){P(Ar)Me₂}₂] (5a (Ar = Tbt), 5b (Ar = Bbt)) respectively. The x-ray crystallographic analyses of 4b and 56 showed a novel three-membered PtE₂ (E = S, Se) ring structure with a square planar geometry around the platinum center. The oxidation of 4b and 5b with an equimolar amount of m-chloroperbenzoic acid or tert-butyl hydroperoxide in dichloromethane yielded the corresponding disulfur and diselenium monoxide complexes [Pt(E₂O){P(Bbt)Me₂}₂] (6 (E = S), 7 (E = Se)). The further reactions of 6 and 7 with an excess of oxidants gave the corresponding O,S-coordinated thiosulfato complex [Pt(S₂O ₃){P(Bbt)Me₂}₂] (8) and the O,O-coordinated selenito complex [Pt(SeO₃){P(Bbt)Me₂}₂] (11), respectively. The dynamic behavior in solution was revealed by the variable-temperature NMR spectroscopy for 4b, 5b, 8, and 11, which indicates the existence of the intramolecular CH...E (E = O, S, Se) interactions between the methine hydrogens of the o-bis(trimethylsilyl)methyl groups and the Pt-bonded chalcogen atoms.

Full text of DOI:10.1080/10426500490428906

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Phosphorus, Sulfur, and Silicon and the Related
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SYNTHESIS AND PROPERTIES OF THE FIRST DISULFUR
AND DISELENIUM COMPLEXES OF PLATINUM
Norihiro Tokitoh a , Kazuto Nagata a & Nobuhiro Takeda a
a Kyoto University , Kyoto, Japan
Published online: 12 Aug 2010.
To cite this article: Norihiro Tokitoh , Kazuto Nagata & Nobuhiro Takeda (2004) SYNTHESIS AND PROPERTIES OF THE FIRST
DISULFUR AND DISELENIUM COMPLEXES OF PLATINUM, Phosphorus, Sulfur, and Silicon and the Related Elements, 179:4-5,
915-927
To link to this article: http://dx.doi.org/10.1080/10426500490428906
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Phosphorus, Sulfur, and Silicon, 179:915–927, 2004
ꢀC
Copyright Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500490428906
SYNTHESIS AND PROPERTIES OF THE FIRST
DISULFUR AND DISELENIUM COMPLEXES
OF PLATINUM
Norihiro Tokitoh, Kazuto Nagata, and Nobuhiro Takeda
Kyoto University, Kyoto, Japan
(Received August 18, 2003; accepted October 3, 2003)
The reactions of overcrowded platinum(0) complexes [Pt{P(Ar)Me2}2]
(Ar = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt), 2,6-bis[bis-
(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt)) with
elemental sulfur and selenium resulted in the formation of the first
platinum disulfur and diselenium complexes, [Pt(S2){P(Ar)Me2}2] (4a
(Ar = Tbt), 4b (Ar = Bbt) and [Pt(Se2){P(Ar)Me2}2] (5a (Ar = Tbt), 5b
(Ar = Bbt)) respectively. The x-ray crystallographic analyses of 4b and
5b showed a novel three-membered PtE2 (E = S, Se) ring structure with
a square planar geometry around the platinum center. The oxidation
of 4b and 5b with an equimolar amount of m-chloroperbenzoic acid or
tert-butyl hydroperoxide in dichloromethane yielded the corresponding
disulfur and diselenium monoxide complexes [Pt(E2O){P(Bbt)Me2}2]
(6 (E = S), 7 (E = Se)). The further reactions of 6 and 7 with an excess
of oxidants gave the corresponding O,S-coordinated thiosulfato complex
[Pt(S2 O3){P(Bbt)Me2}2] (8) and the O,O-coordinated selenito complex
[Pt(SeO3){P(Bbt)Me2}2] (11), respectively. The dynamic behavior in so-
lution was revealed by the variable-temperature NMR spectroscopy for
4b, 5b, 8, and 11, which indicates the existence of the intramolecular
. . .
CH E (E = O, S, Se) interactions between the methine hydrogens of the
o-bis(trimethylsilyl)methyl groups and the Pt-bonded chalcogen atoms.
Keywords: Bulky phosphine ligand; CH–chalcogen interaction; oxida-
tion; platinum–diselenium complex; platinum–disulfur complex
We thank Ms. Toshiko Hirano and Ms. Tomoko Terada of the Microanalytical
Laboratory of the Institute for Chemical Research of Kyoto University for the elemen-
tal analysis and HRMS spectra. This work was partially supported by Grants-in-Aid
for COE Research on Elements Science (No. 12CE2005), Scientific Research on Priority
Area (A) (No. 14078213), 21st Century COE on Kyoto University Alliance for Chemistry,
and “Nanotechnology Support Project” from the Ministry of Education, Culture, Sports,
Science, and Technology of Japan.
Address correspondence to Norihiro Tokitoh, Institute for Chemical Research, Kyoto
University, Gokasho, Uji, Kyoto 611-0011, Japan. E-mail: tokitoh@boc.kuicr.kyoto-u.ac.jp
915

916
N. Tokitoh et al.
The chemistry of complexes having a diatomic chalcogen ligand has
been of much interest from the viewpoints of not only their structure
and reactivity but also their synthetic utility.1 However, there have
been few examples of mononuclear metal complexes of diatomic chalco-
gen, since sulfur and selenium ligands have a strong propensity for
bridging metal atoms. To our knowledge, the disulfur and diselenium
complexes of platinum remain unknown in contrast to the extensive
studies on the dioxygen analogues. In addition, the larger PtEn (n =
4, 5; E = S, Se) ring systems, e.g., [Pt(S5)3(NH4)2],2 [Pt(S4)(PPh3)2],3
and [Pt(Se4)(dppe)] (dppe = 1,2-bis(diphenyl-phosphino)ethane),4 and
chalcogenido-bridged bimetallic complexes, e.g., [Pt2(µ-E)2(PPh3)4]
(E = S, Se), have been extensively studied.5
We have previously reported the synthesis of cyclic poly-
chalcogenides containing a heavier main group element such as
[Tbt(R)ME4] (M = Si, Ge, Sn, or Pb; E = S or Se; Tbt = 2,4,6-
tris[bis(trimethylsilyl)methyl]phenyl),6 [Tbt(R)MSe2] (M = Si or Sn),7
and [TbtSbSn] (n = 5, 7)8 having an extremely bulky substituent,
Tbt group. These results prompted us to develop a new phosphine
ligand bearing a Tbt group, which should be useful for the synthe-
sis of novel classes of transition metal polychalcogenides. The Tbt
group would be expected to protect the metal center to avoid the
formation of polynuclear complexes or cluster compounds. In this
paper, we describe the synthesis and characterization of the first
disulfur and diselenium complexes of platinum [Pt(E2){P(Ar)Me2}2]
(Ar = Tbt, Bbt; E = S, Se) by utilizing the new bulky phos-
phine ligands bearing a Tbt or 2,6-bis[bis(trimethylsilyl)methyl]-4-
[tris(trimethylsilyl)methyl]phenyl (Bbt) group and their oxidation
reaction.9 The dynamic behavior of the novel dichalcogen com-
plexes of platinum and their oxidation products in solution is also
described.
RESULTS AND DISCUSSIONS
Bulky phosphine ligands 1 were readily prepared by the treatment of
a THF solution of ArLi (Ar = Tbt, Bbt) with an equimolar amount of
phosphorous trichloride, followed by the addition of a solution of MeLi
(2.2 equiv.) in diethyl ether (Scheme 1). The ligand exchange reaction
of 1a,b with K2PtCl4 in benzene/H2O at room temperature was very
sluggish to afford gray precipitates of trans-[PtCl2{P(Ar)Me2}2] (2a,b),
which were practically insoluble in common organic solvents except for
halogenated solvent.

Disulfur and Diselenium Complexes of Platinum
917
SCHEME 1
When platinum dichlorides 2a,b were reduced with an excess
amount of lithium naphthalenide in THF, the 31P NMR spectra of
the mixtures showed signals with 195Pt satellites, which are assigned
1
to those of [Pt{P(Ar)Me2}2] (3a: δP = 0.9, JPtP = 3974 Hz, 3b: δP =
1
3.7, JPtP = 3869 Hz). The successive treatment of the mixtures
with elemental sulfur (3 equiv. as S) resulted in the formation of the
first platinum disulfur complexes [Pt(S2){P(Ar)Me2}2] (4a,b) as pur-
ple crystalline solids together with ArMe2P S and a trace amount of
unidentified platinum polysulfido complexes, which could be converted
into 4a,b by further reaction with triphenylphosphine. The use of
6 molar amounts of elemental sulfur (as S) in the reaction of 3a
also gave the disulfur complex 4a as a main product (54%) de-
spite the slight decrease in the yield. The diselenium analogues
[Pt(Se2){P(Ar)Me2}2] (5a,b), the first platinum diselenium complexes,
were also obtained as green crystalline solids when elemental sele-
nium was used instead of elemental sulfur (Scheme 1). These dichalco-
gen complexes, 4 and 5, are both air-stable in the solid state, while
they decomposed to the corresponding phosphine chalcogenides and
metallic platinum on standing in solution at room temperature for
several days. Complexes 4 and 5 showed satisfactory spectral and
analytical data, and the molecular structures of 4b and 5b were
finally determined by x-ray crystallographic analysis (Figure 1 for
4b).1

918
N. Tokitoh et al.
FIGURE 1 ORTEP drawing of [Pt(S2){P(Bbt)Me2}2] (4b) with thermal ellip-
◦
˚
soid plot (50% probability). Selected bond lengths (A) and angles ( ): Pt1 S1
2.348(3), Pt1 S2 2.337(3), S1 S2 2.077(3), Pt1 P1 2.271(2), Pt1 P2 2.265(3);
S1 Pt1 S2 52.63(9), Pt1 S1 S2 63.41(11), Pt1 S2 S1 63.96(11), P1 Pt1 S1
102.07(9), P2 Pt1 S2 98.47(9), P1 Pt1 P2 106.87(8).
Crystallographic analysis showed that 4b and 5b are isomorphous;
their geometries are very similar to each other. The two Bbt groups
are situated in opposite positions with regard to the PtP2 planes to
decrease the steric congestion, and the central Pt atoms of 4b and
5b have tetracoordinated, planar geometries. These dichalcogen com-
plexes, 4b and 5b, have three-membered structures containing Pt(II)
rather than Pt(0) dichalcogen resonance forms which would have higher
double bond character between both chalcogen atoms. It is noteworthy
that the P Pt P bond angles (106.87(8)◦ in 4b and 107.85(7)◦ in 5b)
are larger than those for other related platinum polychalcogenido com-
plexes and an analogous dioxygen complex [Pt(O2)(PPh3)2], reflecting
the severe steric repulsion between two Bbt groups. We suppose the
steric repulsion enlarges the bond angles of P Pt P and hence nar-
rows the angles of E Pt E, thus favoring the selective formation of the
three-membered ring.
The monooxidation of 4b with an equimolar amount of
m-chloroperbenzoic acid (mCPBA) in dichloromethane (CH2Cl2) was
completed within 2 h at −20◦C and gave the corresponding disulfur
monoxide complex [Pt(S2O){P(Bbt)Me2}2] (6) in 65% yield (Scheme 2).11
The diselenium monoxide complex [Pt(Se2O){P(Bbt)Me2}2] (7) also
was obtained cleanly from 5b in 79% yield by the use of an equimolar
amount of tert-butyl hydroperoxide (TBHP).

Disulfur and Diselenium Complexes of Platinum
919
SCHEME 2
An attempt at further oxidation of
6 with an excess of
TBHP in CH2Cl2 yielded the platinum thiosulfato complex
[Pt(S2O3){P(Bbt)Me2}2] (8) in 30% yield together with trans-
[PtCl(OH){P(Bbt)Me2}2] (9) (14%) and phosphine oxide (10) (16%).
The conversions of the S2O ligand to the S2O3 ligand on platinum is
in sharp contrast to the reported exhaustive oxidation of a disulfur
complex of iridium [Ir(S2)(dppe)2]+ to the corresponding disulfur
dioxide complex [Ir(S2O2)(dppe)2]+ via the disulfur monoxide complex
[Ir(S2O)(dppe)2]+.12 Complexes 8 and 9 showed satisfactory spectral
and analytical data, and their molecular structures were finally
determined by x-ray crystallographic analyses (Figure 2 for 8).10 In the
FIGURE 2 ORTEP drawing of [Pt(S2O3){P(Bbt)Me2}2] (8) with thermal el-
◦
˚
lipsoid plot (50% probability). Selected bond distances (A) and angles ( ):
Pt1 O1 2.21(3), Pt1 P1 2.263(16), Pt1 S1 2.312(16), O1 S2 1.54(3), S1 S2
2.079(13), S2 O2 1.43(2), S2 O3 1.43(2); P1 Pt1 P1∗ 105.4(2), O1 Pt1 S1
77.3(6), Pt1 O1 S2 98.1(15), Pt1 S1 S2 81.3(5), O1 S2 S1 101.4(10).

920
N. Tokitoh et al.
molecular structure of 8, the platinum atom has essentially square-
planar geometry and the S2O3 ligand coordinates to the platinum with
O,S fashion.13 The PtSSO ring is slightly bent, and the dihedral angle
between S1–Pt1–O1 and S1–S2–O1 planes is 15.2◦.
Interestingly, further reaction of 7 with an excess of mCPBA in
CH2Cl2 yielded not the Se2O3 complex but the selenite complex
[Pt(SeO3){P(Bbt)Me2}2] (11) together with 10 (16%) and a trace amount
of 9 (6%). The composition and structure of 11 were determined by
HRMS, elemental analysis, and multinuclear NMR spectroscopy. In the
NMR spectra of 11, the 31P resonance was observed as a singlet having
a coupling with 195Pt nuclei at δ = −41.7 (1 JPtP = 3639 Hz) and the 195Pt
resonance appeared as a triplet at δ = −3176 resulting from coupling
to two equivalent phosphorus atoms. In the 77Se NMR spectrum, only
one sharp signal was observed at δ = 1504 in contrast to the broadened
signals of 5b (δ = 689, 1135) and 7 (δ = 582); no satellite peaks due
to the 77Se 195Pt couplings could be found. Consequently, the coordina-
tion of the SeO3 ligand can be considered to have the O-bound geometry
rather than Se-bound one, and we describe the geometry of 11 as the
chelating structure with O,O fashion.14
Of particular note among the structural features of the novel
platinum complexes obtained here is a dynamic process in solution,
as revealed by the variable-temperature NMR spectroscopy. In the
1H NMR spectra of 4b, for example, four methine protons of the
o-bis(trimethylsilyl)methyl (disyl) groups resonate equally at 25◦C (δ =
3.32, Figure 3a). On cooling, the resonance was broadened and then sep-
arated into two signals below about −50◦C. At −60◦C, the resonances
were observed at a much lower field (δ = 4.75) and at a higher field
(δ = 1.79) than that at 25◦C (Figure 3). Although the latter peak is
almost overlapped to the neighboring peak, it could be confirmed by
decoupling experiments in 1H NMR spectroscopy indicating that these
signals at 4.75 and 1.79 ppm should be assigned to the methine protons
of the o-disyl groups. The separation into the two peaks is probably
due to the restricted rotation of the P C and/or P Pt bonds leading to
the non-equivalency of the four methine protons, and the lower shift at
4.75 ppm can be explained in terms of the existence of a considerable
15
. . .
interaction (i.e., C H S interaction) between the Pt-bonded sulfur
and the methine hydrogens of the o-disyl group which are directed to
the PtS2 ring. As in the case of the o-disyl methine protons, a similar
spectral change was observed for the protons of methyl groups bound to
the phosphorus atoms, in the variable temperature NMR study. Thus,
one broad singlet at 25◦C (δ = 2.19) was also separated into two regions
below −20◦C, and At −60◦C, two signals were observed at higher field
(δ = 1.90) and at lower field (δ = 2.30) relative to that observed at 25◦C.

Disulfur and Diselenium Complexes of Platinum
921
FIGURE 3 1H NMR spectra of 4b measured in CDCl3 at (a) 25◦C, (b) 0◦C,
(c) −20◦C, (d) −40◦C, and (e) −60◦C and proposed rotational behavior.
1
Similarly, 5b, 8, and 11 showed the peak separation in the H NMR
spectra at lowered temperature, which can be explained in terms of the
restricted rotation of the P C and/or P Pt bonds.
In all fluxional processes, the spin-spin coupling between the 31P
and 195Pt nuclei was almost totally retained, which indicated that the
bond characters between the P and Pt atoms are intramolecularly con-
served. Within the time scale of the NMR experiments, a dissociative
displacement involving Pt P or Pt E bond cleavage can be excluded.
1
In addition, the low-temperature H NMR measurements on 6 and 7
resulted in the observation of the broadening of the methine signals,
which suggests the occurrence of a similar dynamic process. However,
no clear separation of the signals was observed even at −60◦C.
. . .
˚
In the crystalline states, the C S distances of 4.114–5.132 A in 4b
. . .
˚
and C Se distances of 4.115–5.172 A in 5b are somewhat longer than
the corresponding sums of van der Waals radii (3.70 A and 3.85 A).
On the basis of these findings, we suppose that the observed C H
16
˚
˚
. . .
E
(E = O, S, Se) interaction might be weak, and the restricted rotation in

922
N. Tokitoh et al.
. . .
solution should be attributed not only to the C H E interaction but
also to the steric effects of the bulky substituents. It is interesting that
. . .
the existence of specific C H E interactions, which have been rare in
transition metal complexes, was indicated by the variable-temperature
NMR experiments for these novel platinum complexes.
In addition, the o-benzyl proton signal coalesced at 227
2 K for
4b and at 241
estimated: ꢀG‡ = 10.4
(5b).
2 K for 5b, and the activation parameters could be
0.1 kcal mol−1 (4b), 11.0
0.1 kcal mol−1
EXPERIMENTAL
All experiments were performed under an argon atmosphere unless oth-
erwise noted. All solvents were dried by standard methods and freshly
distilled prior to use. As typical examples, the experimental details for
the series of compounds bearing P(Bbt)Me2 ligands are shown below.
Disulfur Complex of Platinum [Pt(S2){P(Bbt)Me2}2] (4b)
A THF suspension (3 mL) of trans-[PtCl2{P(Bbt)Me2}2] (2b; 123 mg,
0.075 mmol) was treated with a THF solution of lithium naphthalenide
(0.82 M, 0.37 mL, 0.30 mmol) at −78◦C. The reaction mixture was
stirred for 1 h while being warmed up to room temperature. After stir-
ring for 1 h, the solution of [Pt{P(Bbt)Me2}2] (3b) thus obtained was
cooled down to −78◦C again and treated with S8 (7.2 mg, 0.028 mmol,
3eq. as S). The reaction mixture was stirred for 4 h while being warmed
up to room temperature. After removal of the solvent, chloroform was
added to the residue and the mixture was filtered through Celite. The
filtrate was evaporated; then the crude product was dissolved again in
chloroform (3 mL). After the solution was treated with triphenylphos-
phine (39 mg, 0.15 mmol) at 50◦C for 1.5 h, the solvent was evaporated.
The residue was purified by preparative gel permeation liquid chro-
matography (eluent; CHCl3) to afford 4b as a pale purple crystalline
solid (86 mg, 71%) along with BbtMe2P S (11 mg, 10%). 4b: m.p. 162.3–
163.5◦C; 1H NMR (300 MHz, CDCl3, 25◦C): δ 0.16 (s, 72H), 0.21 (s, 54H),
1
2.19 (br s, 12H), 3.32 (s, 4H), 6.65 (s, 4H); 13C{ H} NMR (75 MHz,
CDCl3): δ 2.85 (CH3), 5.57 (CH3), 22.05, 27.6 (br m, P CH3), 28.08
(CH), 125.1 (m, AAꢁX spin system, 1/2[1 JPC
+
3 JPC] = 24.0 Hz), 128.59
4
(CH), 148.26, 151.10 (t, AAꢁX spin system, 1/2[2 JPC + JPC] = 4.9 Hz);
1
31P{ H} NMR (120 MHz, CDCl3, 25◦C, 85% H3PO4): δ −32.2 (1 JPtP
=
1
3909 Hz); 195Pt{ H} NMR (64 MHz, CDCl3, 25◦C, Na2PtCl6): δ −4983
1
(t, JPPt = 3909 Hz); UV-vis (CH2Cl2): 366 nm (sh, ε = 1100), 559 nm

Disulfur and Diselenium Complexes of Platinum
923
(ε = 110); FAB MS m/z: 1628 (M)+; Anal. Calcd for C64H146P2PtS2Si14:
C, 47.15; H, 9.03. Found: C, 47.09; H, 9.28.
Diselenium Complex of Platinum
[Pt(Se2){P(Bbt)Me2}2] (5b)
To a THF solution of [Pt{P(Bbt)Me2}2] (3b), which were prepared from
trans-[PtCl2{P(Bbt)Me2}2] (2b; 82 mg, 0.050 mmol) and lithium naph-
thalenide (1.06 M, 0.19 mL, 0.20 mmol) in THF (2 mL) using the
above-mentioned method, was added Se powder (11.8 mg, 0.15 mmol)
at −78◦C. The reaction mixture was stirred for 4 h while being warmed
up to room temperature. After removal of the solvent, chloroform was
added to the residue; the mixture was next filtered through Celite. Af-
ter the filtrate was evaporated, the residue was purified by preparative
gel permeation liquid chromatography (eluent; CHCl3) to afford 5b as
a green crystalline solid (60 mg, 70%) along with TbtMe2P Se (13 mg,
17%). 5b: m.p. 170.6–171.8◦C; 1H NMR (300 MHz, CDCl3, 25◦C): δ 0.17
1
(s, 72H), 0.22 (s, 54H), 2.23 (br s, 12H), 3.33 (s, 4H), 6.64 (s, 4H);13C{ H}
NMR (75 MHz, CDCl3): δ 2.99 (CH3), 5.60 (CH3), 22.03, 28.11 (CH),
3
29.7 (br m, P CH3), 125.0 (m, AAꢁX spin system, 1/2[1 JPC + JPC] =
23.8 Hz), 128.67 (CH), 148.20, 150.80 (t, AAꢁX spin system, 1/2[2 JPC
+
4 JPC] = 4.9 Hz); 31P NMR (120 MHz, CDCl3, 25◦C, 85% H3PO4):
δ −44.1 (1 JPtP = 3865 Hz); 77Se NMR (57 MHz, CDCl3, 25◦C): δ 582;
195Pt NMR (64 MHz, CDCl3, 25◦C, Na2PtCl6): δ −5030 (t, 1 JPPt = 3865
Hz, 1 JSePt = 262 Hz); UV-vis (CH2Cl2): 407 nm (sh, e = 1700), 465 nm
(sh, e = 120), 633 nm (e = 130); FAB MS m/z: 1723 (M)+; Anal. Calcd
for C64H146P2PtSe2Si14: C, 44.59; H, 8.54. Found: C, 44.32; H, 8.59.
Disulfur Monoxide Complex of Platinum
[Pt(S2O){P(Bbt)Me2}2] (6)
To a CH2Cl2 solution (10 mL) of [Pt(S2){P(Bbt)Me2}2] (4b; 195 mg,
0.12 mmol) was added a CH2Cl2 solution (2.5 mL) of mCPBA (purity:
73%; 31.2 mg, 0.13 mmol) at −20◦C. After the mixture was stirred for
2 h at the same temperature, the reaction was quenched by aqueous
NaHCO3. The organic layer was separated, and then the aqueous
layer was extracted with CH2Cl2. The combined organic layers were
washed with brine and dried over MgSO4. After removal of the solvent,
the residue was reprecipitated from CH2Cl2/n-hexane to afford the
corresponding disulfur monoxide complex 6 (128 mg, 65%) as a yellow
crystalline solid. 6: m.p. 175.0–176.5◦C; 1H NMR (300 MHz, CDCl3): δ
0.13 (s, 18H), 0.14 (s, 18H), 0.15 (s, 18H), 0.18 (s, 18H), 0.22 (s, 54H),

924
N. Tokitoh et al.
1.94 (d,2 JPH = 7.5 Hz, 3H), 2.10 (d, 2 JPH = 8.0 Hz, 3H), 2.14 (d, 2 JPH
=
2
4
8.2 Hz, 3H), 2.24 (d, JPH = 8.9 Hz, 3H), 3.06 (d, JPH = 2.5 Hz, 2H),
1
3.14 (d, 4 JPH = 2.9 Hz, 2H), 6.68 (d, 4 JPH = 3.1 Hz, 4H); 13C{ H} NMR
(75 MHz, CDCl3): δ 2.84 (CH3), 2.93 (CH3), 3.03 (CH3), 5.61 (CH3), 21.5
(m, P CH3), 22.09, 25.91 (dd, 1 JPC = 32.4 Hz, 3 JPC = 2.5 Hz, P CH3),
28.47 (d, 3 JPC = 6.2 Hz, CH), 28.9 (m, P CH3), 29.9 (m, P CH3), 28.69
3
1
1
(d, JPC = 7.5 Hz, CH), 126.64 (d, JPC = 43.6 Hz), 126.68 (d, JPC
=
=
2
44.8 Hz) 128.56 (CH), 128.61 (CH), 148.29, 148.40, 150.47 (d, JPC
3.7 Hz), 150.61 (d, JPC = 3.8 Hz); 31P{ H} NMR (120 MHz, CDCl3):
2
1
1
2
1
δ 29.7 (d, JPtP = 4263 Hz, JPP = 8 Hz), −32.8 (d, JPtP = 3254 Hz,
2 JPP = 8 Hz); 195Pt{ H} NMR (64 MHz, CDCl3): δ −4708 (dd, JPPt
=
1
1
3254, 4263 Hz); IR (KBr): ν (SO) = 1042 cm−1; UV-vis (CH2Cl2): 379 nm
(sh, ε = 2640). FAB MS m/z: 1645 (M + H)+, 1629 (M − O+H)+; Anal.
Calcd for C64H146OP2PtS2Si14: C, 46.69; H, 8.94. Found: C, 46.53; H,
9.11.
Diselenium Monoxide Complex of Platinum
[Pt(Se2O){P(Bbt)Me2}2] (7)
To a stirred solution of [Pt(Se2){P(Bbt)Me2}2] (5b; 207 mg, 0.12 mmol)
in CH2Cl2 (10 ml) was added dropwise a 5.6 M n-decane solution of
TBHP (26 µl, 0.14 mmol) at 0◦C. After 1 hour, the reaction mixture
was stirred for 2 h while being warmed up to room temperature. After
removal of the solvent, the residue was separated by silica gel column
chromatography (CHCl3) and subsequent preparative gel permeation
liquid chromatography (eluent; CHCl3) to afford the corresponding dis-
elenium monoxide complex 7 as a yellow crystalline solid (165 mg, 79%).
7: m.p. 158.2–159.5◦C; 1H NMR (300 MHz, CDCl3): δ 0.12 (s, 36H), 0.13
(s, 18H), 0.17 (s, 18H), 0.20 (s, 54H), 1.99 (d,2 JPH = 7.5 Hz, 3H), 2.10
(d,2 JPH = 8.0 Hz, 3H), 2.14 (d,2 JPH = 8.2 Hz, 3H), 2.24 (d,2 JPH = 8.9 Hz,
1
3H), 3.06 (s, 2H), 3.18 (s, 2H), 6.66 (s, 4H); 13C{ H} NMR (75 MHz,
CDCl3): δ 2.97 (CH3), 3.09 (CH3), 5.60 (CH3), 22.16 (d, 1 JPC = 35.8 Hz,
1
3
P CH3), 22.17, 28.03 (d, JPC = 33.3 Hz, P CH3), 28.59 (d, JPC
=
6.8 Hz, CH), 28.82 (d, JPC = 6.8 Hz, CH), 29.86 (dd,1 JPC = 28.4 Hz,
3
3 JPC = 6.2 Hz, P CH3), 30.13 (dd,1 JPC = 36.4 Hz, JPC = 8.6 Hz,
3
P CH3), 125.68 (d, 1 JPC = 43.2 Hz), 126.21 (d, 1 JPC = 49.3 Hz), 128.68
(CH), 128.73 (CH) 148.50 (d, 4 JPC = 2.5 Hz), 148.68 (d, 4 JPC = 2.5 Hz),
150.40 (d, JPC = 9.9 Hz), 150.58 (d, JPC = 9.9 Hz); 31P{ H} NMR
2
2
1
(120 MHz, CDCl3): δ −34.8 (d, 1 JPtP = 3431 Hz, 2 JPP = 12 Hz), −38.7 (d,
1 JPPt = 3974 Hz, 2 JPP = 12 Hz); 77Se{ H} NMR (57 MHz, CDCl3, 25◦C):
1
δ 689, 1135 (1 JPtSe = 416 Hz); 195Pt{ H} NMR (64 MHz, CDCl3): δ −4768
1
(dd, 1 JPPt = 3431, 3974 Hz); UV-vis (CH2Cl2): 392 nm (ε = 1700); FAB

Disulfur and Diselenium Complexes of Platinum
925
MS m/z: 1739 (M)+, 1723 (M-O)+; Anal. Calcd for C64H146OP2PtSe2Si14:
C, 44.18; H, 8.46. Found: C, 44.27; H, 8.59.
Thiosulfito Complex of Platinum
[Pt(S2O3){P(Bbt)Me2}2] (8)
To a stirred solution of [Pt(S2O){P(Bbt)Me2}2] (6; 164 mg, 0.10 mmol)
in CH2Cl2 (5 ml) was added dropwise a 5.6 M n-decane solution of
TBHP (53 µl, 0.30 mmol) at −20◦C. The reaction mixture was stirred
for 20 h while being warmed up to room temperature. After removal
of the solvents, the residue was separated by preparative gel perme-
ation liquid chromatography (eluent; CHCl3) and subsequent silica
gel column chromatography (CHCl3) to afford O,S-coordinated thiosul-
fito complex 8 as a pale yellow crystalline solid (50 mg, 30%) along
with trans-[PtCl(OH){P(Bbt)Me2}2] (9) (23 mg, 14%) and phosphine
oxide BbtMe2P O (10) (23 mg, 16%). 8: m.p. 220.6–221.1◦C (decomp.);
1H NMR (300 MHz, CDCl3): δ 0.17 (s, 36H), 0.19 (s, 36H), 0.22 (s, 54H),
2
2
2.05 (d, JPH = 9.1 Hz, 6H), 2.19 (d, JPH = 9.5 Hz, 6H), 3.01 (s, 2H),
4
4
3.42 (s, 2H), 6.67 (d, JPH = 3.8 Hz, 2H), 6.70 (d, JPH = 3.6 Hz, 2H);
13C{ H} NMR (75 MHz, CDCl3): δ 2.92 (CH3), 3.06 (CH3), 5.61 (CH3),
1
3
5.65 (CH3), 22.48, 22.59, 26.6 (br m, P CH3), 29.47 (d, JPC = 5.5 Hz,
3
1
CH), 29.59 (d, JPC = 5.5 Hz, CH), 120.05 (d, JPC = 64.7 Hz), 122.75
1
3
3
(d, JPC = 54.9 Hz), 128.77 (d, JPC = 8.0 Hz, CH), 129.11 (d, JPC
=
8.6 Hz, CH), 149.47 (d, 4 JPC = 2.5 Hz), 150.05 (d, 4 JPC = 3.1 Hz), 151.06
(d, 2 JPC = 10.5 Hz), 151.38 (d, 2 JPC = 9.9 Hz); 31P{ H} NMR (120 MHz,
1
CDCl3): δ −31.5 (d, 1 JPtP = 3240 Hz, 2 JPP = 21 Hz), −48.1 (d, 1 JPtP
=
4137 Hz, 2 JPP = 21 Hz); 195Pt{ H} NMR (64 MHz, CDCl3): δ −3995 (dd,
1 JPPt = 3240, 4137 Hz). FAB MS m/z: 1677 (M+H)+; Anal. Calcd for
C64H146O3P2PtS2Si14: C, 45.80; H, 8.77. Found: C, 45.74; H, 8.80.
1
Selenito Complex of Platinum
[Pt(SeO3){P(Bbt)Me2}2] (11)
To a CH2Cl2 solution (10 mL) of [Pt(Se2O){P(Bbt)Me2}2] (7; 209 mg,
0.12 mmol) was added a CH2Cl2 solution (2.5 mL) of mCPBA (purity:
73%; 85.1 mg, 0.36 mmol) at −50◦C. The reaction mixture was stirred
for 4 h while being warmed up to room temperature. After removal of the
solvent, the residue was separated by silica gel column chromatography
(CHCl3: Et2O = 5:1) and subsequent preparative gel permeation liq-
uid chromatography (eluent; CHCl3) to afford O,O-coordinated selenito
complex 11 (103 mg, 51%) as a pale yellow crystalline solid along with
9 (12 mg, 6%) and 10 (27 mg, 16%). 11: m.p. 222.4–223.8◦C (decomp.);
1H NMR (300 MHz, CDCl3): δ 0.18 (s, 72H), 0.20 (s, 54H), 1.98 (t, AA’X

926
N. Tokitoh et al.
4
spin system, 1/2[2 JPH + JPH] = 9.3 Hz, 12H), 3.49 (s, 4H), 6.66 (s, 4H);
1
13C{ H} NMR (75 MHz, CDCl3): δ 2.88 (CH3), 3.03 (CH3), 5.51 (CH3),
22.2 (br m, P CH3), 22.32, 29.44 (CH), 121.2 (m, AAꢁX spin system,
3
1/2[1 JPC + JPC] = 29.3 Hz), 128.67 (CH), 149.12, 151.01 (t, AA’X spin
4
1
system, 1/2[2 JPC + JPC] = 4.5 Hz); 31P{ H} NMR (120 MHz, CDCl3):
δ −41.7 (1 JPtP = 3639 Hz); 77Se{ H} NMR (57 MHz, CDCl3, 25◦C):
1
δ 1504; 195Pt{ H} NMR (64 MHz, CDCl3): δ −3176 (t, JPPt
=
1
1
3639 Hz); HRMS m/z calcd for C64H146O3P2PtSeSi14: 1691.6330, found
1691.6316; Anal. Calcd for C64H146O3P2PtSeSi14: C, 45.40; H, 8.69.
Found: C, 45.29; H, 8.67.
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