Arylchlorobis(dialkyl sulfide)platinum(II) Complexes
Inorganic Chemistry, Vol. 36, No. 20, 1997 4515
oil from which crystals separated at -30 °C. These were filtered off,
washed with cold MeOH, and dried yielding 0.416 g (61%) of crude
3. A 0.172 g amount of this precipitate was dissolved in a minimum
amount of CHCl3, MeOH being added until the solution became cloudy.
After 24 h at -30 °C the white crystals formed were filtered off and
dried giving 0.126 g (44%) of 3. Mp ) 200-210 °C (dec). Anal.
Calcd for C22H34PtS2: C, 47.4; H, 6.1. Found: C, 47.1; H, 6.5. 1H-
responsible for the reactivity differences observed between some
related cyclometalated and bis(phosphine) complexes.21,22
Experimental Section
General Procedures and Chemicals. Reactions involving lithium
or Grignard reagents were carried out in dried glass under nitrogen or
argon in solvents dried with activated molecular sieves. Other solvents
were of pa quality and used directly except for light petroleum which
was distilled prior to use. Ligand solutions were prepared from sodium
iodide (Merck, pa), sodium bromide (Mallinckrodt, AnalaR), sodium
azide (BDH, AnalaR), potassium cyanide (Merck, pa), and sodium
thiocyanate (MCB). Concentrations of lithium reagents were deter-
mined by titration with i-BuOH in xylene using 1,10-phenantroline as
indicator.23 Elemental analysis was performed by Mikro Kemi AB,
Uppsala, Sweden. UV spectra were recorded on a Milton-Roy 3000
diode-array spectrophotometer. Melting points (uncorrected) were taken
on an Electrothermal melting point apparatus. IR spectra were recorded
on a Nicolet 20 SXC FT-IR spectrometer as Nujol mulls between CsI
windows.
3
NMR (CDCl3, 300 MHz): δ 1.97 (s, JPt-H ) 59 Hz, 12 H), 2.20 (s,
6 H), 2.63 (s, 12 H), 6.69 (s, 4 H). 13C-NMR (CDCl3, 75.4 MHz): δ
20.8 (q, JC-H ) 125 Hz, p-CH3), 23.9 (q, JC-H ) 142 Hz, 2JPt-C ) 17
2
Hz, CH3-S), 25.1 (q, JC-H ) 124 Hz, JPt-C ) 31 Hz, o-CH3), 126.6
3
(d, JC-H ) 150 Hz, JPt-C ) 26 Hz, m-C), 131.8 (s, p-C), 144.5 (s,
1
o-C), 156.7 (s, JPt-C ) 621 Hz, i-C).
trans-[Pt(mesityl)Cl(SMe2)2] (4). A 0.139 g (0.25 mmol) amount
of 3 was dissolved in 50 mL of acetone, and 0.3 mL of 1.0 M aqueous
hydrochloric acid was added. The reaction mixture was stirred for 1
h whereafter the solvent was evaporated. The residue was recrystal-
lized from MeOH and filtered off and washed with ice-cold MeOH,
giving 0.079 g (67%) of 4. Mp ) 157-163 °C (dec). Anal. Calcd
for C13H23ClPtS2: C, 32.9; H, 4.9; Cl, 7.5. Found: C, 32.6; H, 4.7;
Cl, 8.7. 1H-NMR (CDCl3, 300 MHz): δ 2.19 (s, 3 H), 2.32 (s, 3JPt-H
trans-[PtPhCl(SMe2)2] (1) was prepared according to Kukushkin
et al., and its 1H-NMR spectrum was in accordance with that reported.24
trans-[PtPhCl(SEt2)2] (2). An 8.2 mL (76.1 mmol) volume of
diethyl sulfide (Janssen Chimica, 98%) was added to a solution of 1.031
g (2.48 mmol) of K2PtCl4 (Johnson Matthey) in 50 mL of water. The
mixture was stirred at room temperature for 24 h. The unreacted diethyl
sulfide separated and was removed, and a solution of 0.959 g (5.21
mmol) of KPF6 (Janssen Chimica, 98%) in water was added. The
mixture was stirred vigorously for a few hours, and a yellow oil
precipitated. The water was evaporated, and the residue was washed
with water several times whereafter it was filtered off, washed with
water again, and dried in air, yielding 1.14 g (71%) of crude yellow
[PtCl(SEt2)3]PF6. Without further purification, 0.618 g (0.957 mmol)
of this salt was dissolved in a mixture of 8 mL of acetone and 12 mL
of water, and a solution of 0.413 g (1.21 mmol) of NaBPh4 (Aldrich,
99.5+%) in 95% EtOH was added dropwise. A white precipitate
formed and stirring was continued for 10 min whereafter the precipitate
was collected on a glass filter, washed with water and dried in air. The
yield of crude [PtCl(SEt2)3]BPh4 was 0.695 g (89%). A 0.687 g (0.838
mmol) amount of the solid product was heated at 105 °C for 3 h. The
residue was recrystallized from 95% EtOH, and the off-white crystals
formed were collected on a glass filter and washed twice with ice-cold
EtOH. The yield was 0.262 g (64%). Mp ) 85-89 °C. Anal. Calcd
for C14H25ClPtS2: C, 34.5; H, 5.2; Cl, 7.3. Found: C, 34.1; H, 5.1;
Cl, 7.6. 1H-NMR (CDCl3, 300 MHz): δ 1.36 (t, J ) 7.3 Hz, 12 H),
2.83 (br, 8 H), 6.85-6.98 (m, 3 H), 7.17-7.35 (m, 2 H). 13C-NMR
4
) 57 Hz, 12 H), 2.56 (s, JPt-H ) 6.9 Hz, 6 H), 6.65 (s, 2 H). 13C-
NMR (CDCl3, 75.4 MHz): δ 20.5 (q, JC-H ) 124 Hz, p-CH3), 23.0
2
(q, JC-H ) 142 Hz, JPt-C ) 14.6 Hz, CH3-S) 26.1 (q, JC-H ) 126
3
3
Hz, JPt-C ) 49.8 Hz, o-CH3), 127.2 (d, JC-H ) 153 Hz, JPt-C ) 44
Hz, m-C), 132.1 (s, ipso-C), 133.4 (s, p-C), 141.0 (s, o-C).
trans-[Pt(p-anisyl)Cl(SMe2)2] (5). cis-[Pt(p-anisyl)Cl(Me2SO)2] was
prepared according to a modification of the method of Eaborn et al.5
from equivalent amounts of K2PtCl4 and Me3Sn(p-anisyl) in Me2SO
(Mallinckrodt pa). The tin compound was prepared from p-anisyl-
lithium and Me3SnCl (Aldrich) according to Buchman et al.26 A 0.214
g amount of the Me2SO compound was dissolved in 4 mL of Me2S
(Merck pa), and the solution was stirred at room temperature for 3 h.
Under continued stirring light petroleum was added until the white
product precipitated. It was collected on a glass filter and washed with
light petroleum, giving 0.104 g (52%) of 5. Mp ) 142-145 °C (dec).
Anal. Calcd for C11H19ClPtOS2: C, 28.6; H, 4.2; Cl, 7.7. Found: C,
3
28.4; H, 4.2; Cl, 7.4. 1H-NMR (CDCl3, 300 MHz): δ 2.33 (s, JPt-H
) 57 Hz, 12 H), 3.74 (s, 3 H), 6.63-7.21 (AA′BB′, J ) 8 Hz, 3J ) 46
Hz). 13C-NMR (CDCl3, 75.4 MHz): δ 22.9 (qq, JC-H ) 142 Hz, 3JC-H
) 4.0 Hz, 2JPt-C ) 14 Hz, CH3-S), 55.0 (q, JC-H ) 143 Hz, CH3-O),
2
2
114.2 (dd, JC-H ) 157 Hz, JC-H ) 4.6 Hz, JPt-C ) 60 Hz, o-C),
123.4 (t, 2JC-H ) 7.4 Hz, JPt-C ) 929 Hz, i-C), 135.9 (dd, JC-H ) 157
Hz, JC-H ) 9.2 Hz, m-C), 156.6 (s, p-C).
2
Kinetics. The kinetics were monitored on either a modified Durrum-
Gibson stopped-flow instrument, a homebuilt stopped-flow spectro-
photometer, or an Applied Photophysics Bio Sequential SX-17MV
stopped-flow ASVD spectrofluorometer. The substitution of chloride
on complexes 1, 2, 4, and 5 by various nucleophiles was studied in
methanol solvent by observing the increase in absorbance at wave-
lengths between 280 and 330 nm. All reactions were studied under
pseudo first-order conditions with at least a 10-fold excess of nucleo-
phile (10-1-5 × 10-3 M) with respect to the complex (5 × 10-4 M).
Data were analyzed by means of the OLIS program Model 4000 Data
System Stopped-flow, version 9.04,27 or the software provided by
Applied Photophysics.28 All kinetic traces fitted well to first-order
exponentials. The observed rate constants were not affected by an
increase of the ionic strength to 0.1 M or an addition of 1% water to
the methanol. Variable-temperature experiments were performed
between 278 and 313 K. Variable-pressure measurements were made
between 1 and 1500 bar on a Hi-Tech high-pressure stopped-flow
spectrophotometer, HPSF-56, connected to a Hi-Tech high-performance
hydraulic pressurizing system (Hydratron) with digital recording of the
pressure,29 and with water as pressurizing medium.
(CDCl3, 75.4 MHz): δ 12.9 (q, JC-H ) 129 Hz, 3JPt-C ) 35 Hz, CH3-),
2
29.9 (t, JC-H ) 140 Hz, JPt-C ) 14 Hz, CH2S-), 123.2 (d, JC-H
)
2
159 Hz, p-C), 128.0 (d, JC-H ) 163 Hz, JPt-C ) 57 Hz, o-C), 133.4
(s, i-C), 136.7 (d, JC-H ) 155 Hz, m-C).
trans-[Pt(mesityl)2(SMe2)2] (3). A 2.0 mL (13.1 mmol) volume of
2-bromomesitylene (Janssen Chimica, 99%) was dissolved in 20 mL
of dry ether in a flask fitted with a condenser. The solution was cooled
on ice, 8.0 mL of 1.6 M (12.8 mmol) n-BuLi in hexane (Merck, z.S.)
was added, and the mixture was stirred at room temperature for 18 h.
This solution of mesityllithium was cooled on ice and 0.476 g (1.22
mmol) of [PtCl2(SMe2)2] (cis/trans mixture prepared according to Cox
et al.25) partly dissolved in dry benzene was added. Stirring was
continued for 3 h at 0 °C and an additional 1 h at room temperature,
after which the reaction mixture was hydrolyzed with 25 mL of water.
The phases were separated, and the aqueous phase was extracted twice
with ether. The combined organic phases were washed with water and
dried over anhydrous MgSO4. Evaporation of the solvent gave a brown
(21) Elding, L. I.; Romeo, R. J. Chem. Soc., Dalton Trans. 1996, 1471-
NMR Measurements. NMR spectra were recorded on a Varian
1472.
Unity 300 spectrometer. 195Pt-NMR spectra were recorded in a 10-
(22) Schmu¨lling, M.; Ryabov, A. D.; van Eldik, R. J. Chem. Soc., Dalton
Trans. 1996, 1472-1473.
(23) Watson, S. C.; Eastham, J. F. J. Organomet. Chem. 1967, 9, 165-
168.
(24) Kapoor, P.; Kukushkin, V. Y.; Lo¨vqvist, K.; Oskarsson, Å. J.
Organomet. Chem. 1996, 517, 71-79.
(25) Cox, E. G.; Saenger, H.; Wardlaw, W. J. Chem. Soc. 1934, 182-
186.
(26) Buchman, O.; Grosjean, M.; Nasielski, J. Bull. Soc. Chim. Belg. 1962,
71, 467-472.
(27) OLIS 4300S Spectroscopy User’s Manual; OLIS: Jefferson, GA.
(28) Applied Photophysics Bio Sequential SX-17MV Stopped Flow ASVD
Spectrofluorimeter, software manual; Applied Photophysics Ltd.: 203/
205 Kingston Road, Leatherhead KT22 7PB, U.K.