Synthesis and X-ray structural analysis of hydrido(thiolato) platinum(II) complexes

Article abstract of DOI:10.1246/cl.2009.400

The oxidative addition of [Pt(η²-nb)(PPh₃) ₂] with a sterically hindered thiol, TripSH (4, Trip = 9-triptycyl) in toluene afforded cis-hydrido(thiolato) Pt^II complex [PtH(STrip)(PPh₃)₂] (5)

Full text of DOI:10.1246/cl.2009.400

400
Chemistry Letters Vol.38, No.5 (2009)
Synthesis and X-ray Structural Analysis of Hydrido(thiolato) Platinum(II) Complexes
Norio Nakata, Suzuka Yamamoto, Wataru Hashima, and Akihiko Ishiiꢀ
Department of Chemistry, Graduate School of Science and Engineering, Saitama University,
Shimo-okubo, Sakura-ku, Saitama 338-8570
(Received February 2, 2009; CL-090116; E-mail: ishiiaki@chem.saitama-u.ac.jp)
1
2
1
The oxidative addition of [Pt(ꢀ2-nb)(PPh3)2] with a sterical-
21.3 (d, JP{P ¼ 15 Hz, JPt{P ¼ 2945 Hz) and 30.5 (d, JP{P
¼
¼
2
2
ly hindered thiol, TripSH (4, Trip = 9-triptycyl) in toluene af-
forded cis-hydrido(thiolato) PtII complex [PtH(STrip)(PPh3)2]
(5), as thermally and moisture-stable colorless crystals in 91%
15 Hz, JPt{P ¼ 1960 Hz) for cis-2 and 31.6 (s, JPt{P
3053 Hz) for trans-2. However, cis- and trans-2 were thermally
unstable and were converted gradually at room temperature to 3.
This conversion would occur by the reaction of cis- and/or
trans-2 with thiol 1 that remained in the reaction system. In fact,
the reaction of 1 with a half amount of [Pt(ꢀ2-nb)(PPh3)2] in
toluene afforded only 3 in 35% isolated yield. The molecular
structure of 3 was fully determined by NMR spectroscopic data7
and X-ray crystallography.9 The 31P{1H} NMR spectrum for 3
demonstrated a singlet signal with the 195Pt satellites at ꢁ 27.0
(1JPt{P ¼ 2827 Hz). In the X-ray analysis of 3 (Figure 1), two
thiolato ligands were coordinated in cis position to the platinum
center. The Pt–S bond lengths were 2.3500(15) and
1
yield. Complex 5 was fully characterized by H, 13C{1H}, and
31P{1H} NMR and IR spectroscopies, and the molecular struc-
ture of 5 was determined by X-ray crystallography.
Transition metal catalyzed hydrothiolation and thiocarbon-
ylation of alkynes are among the most attractive methods for
the preparation of vinyl sulfides, which are valuable as synthetic
intermediates in total syntheses and as precursors to a wide range
of functionalized molecules.1,2 In the Pt0-catalyzed thiocarbon-
ylations, hydrido(thiolato) PtII complexes are proposed as key
intermediates.3 Although the hydrido(thiolato) PtII complexes
are readily obtained by the oxidative addition of thiol to Pt0 com-
plex, their full spectroscopic characterizations and crystal struc-
ture analyses have not been performed owing to their thermal
˚
2.3816(15) A, which are slightly elongated compared with those
of the aliphatic cis-dithiolato PtII complex [Pt(S2C7H8)-(PPh3)2]
˚
(C7H8 = 1,3-cycloheptadiene-5,6-diyl) [2.339(4), 2.308(4) A]
10
because of the steric influence of the bulky 1-adamantyl groups.
To obtain a stable hydrido(thiolato) PtII complex, we next
examined the oxidative addition of the thiol having an extremely
bulky Trip group with a Pt0 complex. Thus, treatment of TripSH
(4) with [Pt(ꢀ2-nb)(PPh3)2] in toluene resulted in the immediate
formation of cis-hydrido(thiolato) PtII complex [PtH(STrip)-
(PPh3)2] (5), which was isolated as colorless crystals in 91%
1
instability. Only H NMR and IR spectroscopic data of trans-
[PtH(SPh)(PPh3)2] have been reported so far by Ugo et al.4
and Ogawa et al.3a
Meanwhile, we have recently succeeded in the first isolation
of stable hydrido(selenolato) platinum(II) complex cis-
[PtH(SeTrip)(PPh3)2] (Trip = 9-triptycyl), which is postulated
as the key intermediate in the Pt-catalyzed hydroselenation of
alkynes.5 In this paper, we report the synthesis of the stable
cis-hydrido(thiolato) PtII complex by the reaction of an over-
crowded alkanethiol with Pt0 complex and its X-ray crystallo-
graphic analysis.
yield (Scheme 2).11 In the H NMR of 5, the platinum hydride
1
resonated as a doublet of doublets at ꢁ ꢂ5:96 (2JP{H ¼ 189,
1
18 Hz, JPt{H ¼ 947 Hz), which is shifted downfield relative to
that of trans-[Pt(H)(SPh)(PPh3)2] [ꢁ ꢂ10:01 (2JP{H ¼ 14 Hz,
1JPt{H ¼ 961 Hz)]. The 31P{1H} NMR spectrum of 5 displayed
two doublets with the 195Pt satellites at ꢁ 23.1 (1JPt{P
¼
We first examined the reaction of 1-AdCH2SH (1, 1-Ad =
1-adamantyl)6 with 1 equiv of [Pt(ꢀ2-nb)(PPh3)2] (nb = norbor-
3189 Hz) and 32.4 (1JPt{P ¼ 1963 Hz), which were assigned to
the signals due to the phosphorus atoms lying trans to the thio-
1
nene)7 in toluene at 0 ꢁC for 30 min (Scheme 1). The H NMR
spectrum of the reaction mixture showed characteristic high-
field shifted signals at ꢁ ꢂ8:69 (s, JPt{H ¼ 851 Hz) and ꢂ5:11
(dd, JP{H ¼ 195, 23 Hz, JPt{H ¼ 1004 Hz), indicating the gener-
ation of trans- and cis-hydrido(thiolato) PtII complexes (trans-2:
cis-2 = 10:1), together with a singlet assignable to the methyl-
ene protons (ꢁ 3.25–3.33) of cis-(dithiolato) PtII complex
[Pt(SCH2-1-Ad)2(PPh3)2] (3).8 In the 31P{1H} NMR spectrum,
the signals assigned to cis-2 and trans-2 were observed at ꢁ
S1
P1
Pt1
P2
S2
H
PPh3
Ph3P
Ph3P
H
[Pt(η2-nb)(PPh3)2]
toluene, 0 °C
Pt
Pt
1-AdCH2SH
Ph3P
SCH2-1-Ad
SCH2-1-Ad
1
cis-2
trans-2
NMR ratio cis-2 : trans-2 = 1 : 10
Figure 1. ORTEP drawing of 3 (30% thermal ellipsoids). Two solvated
toluene molecules and hydrogen atoms are omitted for clarity. Selected
˚
bond lengths (A) and angles (deg): Pt1–S1 = 2.3500(15), Pt1–S2 =
Ph3P
Ph3P
SCH2-1-Ad
SCH2-1-Ad
nb = norbornene
Pt
warm up to RT
1-Ad =
2.3816(15), Pt1–P1 = 2.2738(16), Pt1–P2 = 2.2924(15), S1–Pt1–S2 =
92.50(5), P1–Pt1–P2 = 98.18(6), P1–Pt1–S1 = 88.69(6), P2–Pt1–S2 =
81.77(5), P1–Pt1–S2 = 177.47(6), P2–Pt1–S1 = 173.14(6).
3 (35%)
Scheme 1.
Copyright Ó 2009 The Chemical Society of Japan

Chemistry Letters Vol.38, No.5 (2009)
401
H
S
5
Ph3P
Ph3P
Ph3P
Ph3P
H
S
reflux, 10 h
toluene
Ph3P
[Pt(η2-nb)(PPh3)2]
Pt
Pt
Pt
S
Ph3P
toluene, RT
SH
6 (44%)
4
5 (91%)
Scheme 3.
Scheme 2.
This work was supported by a Grant-in-Aid for Scientific
Research (Nos. 18750026, 19027014, and 20036013) from the
Ministry of Education, Culture, Sports, Science and Technology
of Japan.
References and Notes
1
H1
P2
For reviews on catalytic hydrothiolations, see: a) I. Beletskaya, C.
Moberg, Chem. Rev. 1999, 99, 3435. b) T. Kondo, T. Mitsudo, Chem.
Rev. 2000, 100, 3205. c) A. Ogawa, J. Organomet. Chem. 2000, 611,
463. d) H. Kuniyasu, N. Kambe, Chem. Lett. 2006, 35, 1320. e) I. P.
Beletskaya, V. P. Ananikov, Eur. J. Org. Chem. 2007, 3431.
C. Cao, L. R. Fraser, J. A. Love, J. Am. Chem. Soc. 2005, 127, 17614.
a) A. Ogawa, J. Kawakami, M. Mihara, T. Ikeda, N. Sonoda, T. Hirao,
J. Am. Chem. Soc. 1997, 119, 12380. b) A. Ogawa, N. Kawabe, J.
Kawakami, M. Mihara, T. Hirao, N. Sonoda, Organometallics 1998,
17, 3111. c) J. Kawakami, M. Mihara, I. Kamiya, M. Takeba, A.
Ogawa, N. Sonoda, Tetrahedron 2003, 59, 3521.
R. Ugo, G. L. Manica, S. Cenini, A. Segre, F. Conti, J. Chem. Soc. A
1971, 522.
A. Ishii, N. Nakata, R. Uchiumi, K. Murakami, Angew. Chem., Int.
Ed. 2008, 47, 2661.
T. Kitagawa, Y. Idomoto, H. Matsubara, D. Hobara, T. Kakiuchi, T.
Okazaki, K. Komatsu, J. Org. Chem. 2006, 71, 1362.
Pt1
P1
S1
2
3
Figure 2. ORTEP drawing of 5 (30% thermal ellipsoids). Two solvated
CH2Cl2 molecules and hydrogen atoms are omitted for clarity. Selected
˚
bond lengths (A) and angles (deg): Pt1–S1 = 2.3172(12), Pt1–H1 =
1.684(10), Pt1–P1 = 2.3411(12), Pt1–P2 = 2.2511(12), S1–Pt1–H1 =
88(2), P1–Pt1–P2 = 103.25(4), P1–Pt1–S1 = 90.51(4), P2–Pt1–H1 =
78(2), P2–Pt1–S1 = 165.75(4), P1–Pt1–H1 = 178(2).
4
5
6
7
8
lato ligand and the hydride, respectively. In the IR spectrum, the
absorption due to the Pt–H stretching vibration for 5 was ob-
served at a somewhat lower wavenumber (2100 cmꢂ1) compared
to that of stable hydrido(selenolato) PtII complex cis-
[PtH(SeTrip)(PPh3)2] (2093 cmꢂ1).5 The molecular structure of
5 was determined by X-ray crystallography as depicted in
Figure 2.9 In the crystalline state, the platinum core lies at the
centre of a distorted square-planar coordination sphere consist-
ing of two PPh3 ligands, sulfur, and hydrogen atoms. The P1–
Pt1–P2 angle of 103.25(4)ꢁ considerably deviated from the ideal
90ꢁ of square-planar geometry. The Pt1–S1 bond length was
H. Petzold, H. Gorls, W. Weigand, J. Organomet. Chem. 2007, 692,
2736.
¨
3: mp 148 ꢁC, 1H NMR (C6D6, 400 MHz, ꢁ): 1.70 (br s, 24H), 2.00 (br
s, 6H), 3.25–3.33 (m, 4H), 6.88–7.00 (m, 18H), 7.58–7.60 (m, 12H);
1
31P{1H} NMR (C6D6, 162 MHz, ꢁ): 27.0 (s, JPt{P ¼ 2827 Hz). Anal.
Calcd for C58H64P2PtS2: C, 64.37; H, 5.96%. Found: C, 63.68; H,
6.06%.
9
Crystallographic data have been deposited with Cambridge Crystallo-
graphic Data Centre as supplementary publication nos. CCDC-721303
for 3 and CCDC-721304 for 5.
10 A. Ishii, S. Kashiura, Y. Hayashi, W. Weigand, Chem.—Eur. J. 2007,
13, 4326.
˚
2.3172(12) A, which is in the range of typical values of reported
11 5: mp 136–138 ꢁC, 1H NMR (CDCl3, 400 MHz, ꢁ): ꢂ5:96 (dd,
dithiolato PtII complexes cis-[Pt(1,8-S2-Np)(PPh3)2] (Np =
1
2JP{H ¼ 189, 18 Hz, JPt{H ¼ 947 Hz, 1H), 5.28 (s, 1H), 6.91–7.04
naphthalene) [2.320(1), 2.326(1) A],12 and [Pt(S2C7H8)(Ph3P)2]
˚
(m, 12H), 7.13–7.35 (m, 24H), 7.60–7.64 (m, 6H); 31P{1H} NMR
10
2
1
˚
[2.339(4), 2.308(4) A]. The Pt1–P1 bond length [2.3411(12) A]
˚
was slightly longer than that of the Pt1–P2 [2.2511(12) A], sug-
gesting the lower trans influence of the hydride compared to the
thiolato ligand.
˚
(CDCl3, 162 MHz, ꢁ): 23.1 (d, JP{P ¼ 15 Hz, JPt{P ¼ 3189 Hz),
32.4 (d, 2JP{P ¼ 15 Hz, 1JPt{P ¼ 1963 Hz). IR (KBr) (ꢂ, cmꢂ1): 2100.
.
Anal. Calcd for C56H44P2PtS 2(CH2Cl2): C, 59.24; H, 4.11%. Found:
C, 59.29; H, 3.99%.
12 S. M. Aucott, H. L. Milton, S. D. Robertson, A. M. Z. Slawin, G. D.
Walker, J. D. Woollins, Chem.—Eur. J. 2004, 10, 1666.
While complex 5 is thermally stable in the solid state (Mp:
136–138 ꢁC), heating a toluene solution of 5 at 100 ꢁC for 10 h
gave a five-membered thiaplatinacycle 6,13 which is formed by
an intramolecular C–H activation leading to the cyclometalation
(Scheme 3). The 1H NMR spectrum of 6 exhibited a characteris-
tic signal due to the aromatic proton neighboring the Pt atom at ꢁ
5.92, which is similar to that of the corresponding selenaplatina-
cycle (ꢁ 5.85).5 The 31P{1H} NMR spectrum of 6 showed two
doublets with the 195Pt satellites at ꢁ 24.5 (2JP{P ¼ 21 Hz,
13 6: mp 253–254 ꢁC, 1H NMR (CDCl3, 400 MHz, ꢁ): 5.24 (s, 1H), 5.92
(dt, J ¼ 8:1 Hz, 1H), 6.52 (t, J ¼ 8 Hz, 1H), 6.73 (d, J ¼ 7 Hz, 1H),
6.88–6.98 (m, 12H), 7.12–7.40 (m, 18H), 7.62–7.69 (m, 6H), 7.89
(d, J ¼ 8 Hz, 2H); 31P{1H} NMR (CDCl3, 162 MHz, ꢁ): 24.5
2
1
2
(d, JP{P ¼ 21 Hz, JPt{P ¼ 1852 Hz), 26.2 (d, JP{P ¼ 21 Hz,
1JPt{P ¼ 3183 Hz). Anal. Calcd for C56H42P2PtS: C, 66.99; H, 4.22.
Found: C, 66.68; H, 4.11.
14 a) J. J. Garcia, P. M. Maitlis, J. Am. Chem. Soc. 1993, 115, 12200.
b) D. A. Vicic, W. D. Jones, Organometallics 1998, 17, 3411. c) C. A.
Dullaghan, X. Zhang, D. L. Greene, G. B. Carpenter, D. A. Sweigart,
C. Camiletti, E. Rajaseelan, Organometallics 1998, 17, 3316. d) H. Li,
G. B. Carpenter, D. A. Sweigart, Organometallics 2000, 19, 1823.
1JPt{P ¼ 1852 Hz) and 26.2 (2JP{P ¼ 21 Hz, JPt{P ¼ 3183 Hz).
1
While there are some reports on six-membered thiaplatinacycles
prepared by the insertion reactions of Pt0 complexes into the C–S
bond of thiophene derivatives,14 this result is the first example
of five-membered thiaplatinacycles.
´
e) G. Picazo, A. Arevalo, S. Bernes, J. J. Garcıa, Organometallics
`
´
2003, 22, 4734.
Published on the web (Advance View) March 28, 2009; doi:10.1246/cl.2009.400