Synthesis of halfsandwich ruthenium complexes of sulfinic acid esters [1]

Article abstract of DOI:10.1515/znb-2000-0614

A series of halfsandwich ruthenium sulfinato complexes [CpRu(PR′₃)₂(SO₂R)] (R = Me, CH₂Ph, C₂H₄Ph, Ph, 4-C₆H₄Me; PR′₃ = PMe₃, 1/2 dppm) with various electronic and steric environments around the ruthenium centre, have been prepared by insertion of SO₂ into a ruthenium carbon bond, by a direct ligand exchange reaction, or by oxidation of thiolato complexes with 3-chloroperoxybenzoic acid. The chiral complexes [CpRu(CO)(PPh₃)(SO₂R)] (R = Me, CH₂Ph, Ph) were obtained similarly by oxidation of the corresponding thiolates with magnesium monoperoxyphthalate. Alkylation of the sulfinato complexes with oxonium salts [R″₃O]X (R″ = Me, Et; X = BF₄, PF₆) gave ruthenium complexes of sulfinic acid esters, [CpRu(L)(L′)(S(O)(OR″)R)]X in high yields and, for the chiral complexes, up to 82% de. The esters may be detached from the metal by ligand exchange with acetonitrile. Stronger nucleophiles such as I^- or SMe^- dealkylate the coordinated sulfinic acid esters.

Full text of DOI:10.1515/znb-2000-0614

Synthesis of Halfsandwich Ruthenium Complexes of Sulfinic Acid Esters [1]
Wolfdieter A. Schenk and Nikolai Kuhnerta
Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg
a Current address: Department of Chemistry, University of Surrey, Guildford, GU2 5XH, UK
Reprint requests to Prof. Dr. W. A. Schenk. E-mail: wolfdieter.schenk@mail.uni-wuerzburg.de
Dedicated to Prof. Dr. Dr. h.c. Max Schmidt on the occasion o f his 75th birthday
Z. Naturforsch. 55 b, 527-535 (2000); received March 20, 2000
Ruthenium Complexes, Sulfur Ligands, Diastereoselective Alkylations
A series of halfsandwich ruthenium sulfinato complexes [CpRu(PR'3)2(SO:R)] (R = Me,
CH2Ph, C2H4Ph, Ph, 4-CöH4Me; PR'3 = PMe3, 1/2 dppm) with various electronic and steric
environments around the ruthenium centre, have been prepared by insertion of SO2 into a
ruthenium carbon bond, by a direct ligand exchange reaction, or by oxidation of thiolato
complexes with 3-chloroperoxybenzoic acid. The chiral complexes [CpRu(C0 )(PPh3)(S02R)]
(R = Me, CH2Ph, Ph) were obtained similarly by oxidation of the corresponding thiolates
with magnesium monoperoxyphthalate. Alkylation of the sulfinato complexes with oxonium
salts [Rm30]X (R" = Me, Et; X = BF4 , PF6) gave ruthenium complexes of sulfinic acid esters,
[CpRu(L)(L')(S(0)(0R")R)]X in high yields and, for the chiral complexes, up to 82% de.
The esters may be detached from the metal by ligand exchange with acetonitrile. Stronger
nucleophiles such as I~ or SMe~ dealkylate the coordinated sulfinic acid esters.
Introduction
ligands. We chose sulfinate anions which are more
challenging substrates due to the fact that the poten-
tially nucleophilic oxygen atom is separated by two
bonds from the metal centre. In addition the sulfi-
nate anion when coordinated to a stereogenic ruthe-
nium centre offers the potential of a diastereoselec-
tive functionalisation of one of either diastereotopic
oxygen atoms. We have shown previously that chi-
ral ruthenium complexes can be efficiently used as
chiral auxiliaries in a variety of highly diastereos-
elective transformations [9 - 14]. Hence we should
be able to obtain esters of sulfinic acids stereos-
electively in the coordination sphere of a ruthe-
nium complex. Such systems are valuable building
blocks with sulfur centered chirality [15]. Earlier
work by Wojcicki and co-workers has shown that the
corresponding iron sulfinato complex [CpFe(CO)-
(PPh3)(S 0 2Me)] can be protonated as well as alky-
lated at oxygen and forms stable adducts with BF3
[16, 17]. No reports on the diastereoselectivities of
these transformations were, however, included.
In this contribution we describe the effect of the
electron rich transition metal fragments [CpRu(L)-
(PR3)]+ (L = CO, PR3) on the nucleophilicity of
a coordinated sulfinate anion and the exploitation
of this effect in the synthesis of cationic ruthenium
One of the most notable features of transition
metal complexes is their ability to activate coordi-
nated substrates to undergo reactions not observed
with the free ligands [2, 3], This fascinating aspect
of transition metal chemistry is usually rationalised
by taking into account the framework of a and n
bonding as well as backbonding between the metal
centre and the ligand [4 -6 ]. Electron-rich transi-
tion metal fragments tend to increase the electron
density on the ligand, hence activating it for elec-
trophilic additions.
Electron-rich ruthenium thiolate complexes [Cp-
Ru(PR'3)2(SR)] are readily alkylated under mild
conditions to give cationic thioether complexes
[CpRu(PR'3)2(RSR")]+ [7]. The same class of com-
plexes was even shown to form stable adducts
[CpRu(PR'3)2(S(S0 2)R)] with the weak Lewis acid
S 0 2 [8]. We have discussed this unusual reactivity
in terms of the ability of the ruthenium centre to
increase the electron density on the thiolate sulfur
atom and hence to considerably increase its nucle-
ophilicity. In this context it seemed interesting to
study the effect of complexes of the type [CpRu(L)-
(PR'3)]+ (L = CO, PR'3) on other sulfur-containing
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W. A. Schenk and N. Kuhnert • Ruthenium Complexes of Sulfinic Acid Esters
528
C O >
C O >
C O )
RMgCI, Et20
S02, toluene' ‘ i
Q
Me3P"/Ru^C|
Me3P
20 °C 12 h* Me3P"^Ru^R
Me3P-yRu^R
Me3p
*
Me3PB,/Ru^^_R (2)
i^n
M03p
u, i n
Me3p
n
2a (82%)
2b (80%)
2a, b
3a (95%)
3b (95%)
R
Me CH2Ph
2a 2b
R
Me CH2Ph
3a 3b
complexes of sulfinic acid esters. Furthermore, we
will discuss the factors influencing the diastereose-
lectivity of the alkylation reaction.
Na[S02C6H4Me]
Q
EtOH/THF, 65 °C, 3 h
'V“ Me
Me3P
g
W
/
Synthesis of the Sulfinato Complexes
[CpRu(L)(PR'3)(S02R)]
3c (92%)
(3)
The use of this particularly polar solvent mixture
is crucial for the success of the reaction and points
towards a dissociative ligand substitution mecha-
nism involving a cationic 16 valence electron ruthe-
nium species.
Initially we decided to start our investigation us-
ing the highly electron rich ruthenium fragment
[CpRu(PMe3)2]+. As a common starting mate-
rial we chose [CpRu(PMe3)2(Cl)] (la), which had
been shown earlier to react readily with Grignard
reagents [18]. Similarly, the alkyl complexes 2a, b
were obtained in excellent yields (eq. ( 1)).
It is worth noting that chloro Grignard reagents
are preferred over their bromo or iodo analogs, since
with these heavier halide ions considerable amounts
of the bromo or iodo complexes [CpRu(PMe3)2(X)]
are formed as side products, which are inseparable
from the desired compounds. The alkyl complexes
are air sensitive yellow oils, which are readily sol-
uble in hexane, benzene, or halogenated solvents.
The NMR spectroscopic data of 2a, b are in perfect
accordance with the proposed structures. The most
notable features are the couplings 2J(PRuC) and 3J
(PRuCH) which split the l3C and 'H NMR signals
of the metal bound alkyl groups into triplets. The
methyl resonances of the PMe3 ligands appear as
virtual triplets in the 1H NMR spectra and as char-
acteristic X parts of ABX spin systems [19] in the
l3C NMR spectra.
The sulfinato complexes are pale yellow crys-
talline substances which are readily soluble in
toluene and chlorinated solvents. Compared to their
alkyl counterparts 2a, b, they are fairly air stable
and can be stored for weeks. The solids 3a-c are
apparently quite hygroscopic and therefore do not
give reproducible analytical data. In the NMR spec-
tra the q carbon as well as the a SO2CH proton
resonances are shifted to lower field as expected.
The most notable features of these complexes are
their v (S=0) absorptions in the infrared spectra at
1156 - 1132 and 1028 - 1020 cm-1 , respectively. A
direct comparison between these values of the sul-
finato complexes, which can formally be regarded
as metalla-sulfones, and those of a diorgano-sul-
fone (Me2S 0 2; v (S=0): 1314 and 1134 cm“ 1 [20])
reveal that the S = 0 bond order is significantly re-
duced.
We then turned our attention to the less electron-
rich arylphosphine sulfinato complexes [CpRu-
(dppm)(SÜ2R)] (5a-d). In order to cut the previous
Passing dry gaseous SO2 through solutions of
2a, b in toluene results in quantitative formation
of the desired sulfinato complexes [CpRu(PMe3)2 synthetic route by one step we decided to use the thi-
olate complexes [CpRu(dppm)(SR)] (4a-d) as pre-
cursors. Compound 4d has not been reported before
and was obtained in good yield using our standard
one-pot synthesis [7]. We have recently reported
that this class of compounds can be selectively oxi-
dised with dimethyldioxirane [2 1 ] to give the corre-
sponding sulfinato complexes. In the present case,
(SO2R)] (3a, b) (eq. (2 )).
Sulfinato complexes are also available by a di-
rect ligand substitution reaction as shown in the
following example. Reaction of la with Na[SC>2(4 -
CöFLtMe)] in a 1:1 EtOH/THF solvent mixture un-
der reflux gives [CpRu(PMe3)2(S0 2 (4 -C6H4Me))]
(3c) in almost quantitative yield (eq. (3)).
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W. A. Schenk and N. Kuhnert • Ruthenium Complexes of Sulfinic Acid Esters
^
o
O
[Et30]PF6, CH2CI2
-60 °C, 10 min
I
Ph'w3rP../-Ru
Ph3P
PFr
Me3P"yRu''s —R
Me3P
Me3P,"yRUv's —R
CI
Me3P
H
OEt
(4)
1b
3a-c
8a (90%)
8b (92%)
8c (89%)
EtOH/THF
NaSR
R
Me CH2Ph 4-C6H4Me
dppm
65 °C, 2 h
(6)
< ^ 7
mCPBA
[Et30]PF6, CH2CI2
p y
f
'
0
Ph2
Ph2 L
p... ■Ru.
p,.-RU\ ll
I /
PFR
PhPi L
Z.p
^
'S—R
S—R
SR
-60 °C, 10 min
r R
CH2CI2
-60 °C, 15 min
II
^-P
^~P
OEt
O
Ph,
Ph2
Ph2
Ph2
5a-d
9a (93%)
9b (86%)
9c (93%)
9d (86%)
5a (24%)
5b (71%)
5c (73%)
5d (76%)
4a-d
R
Me CH2Ph Ph C2H4Ph
Me CH2Ph Ph C2H4Ph
(7)
7a-c show v (S=0) bands at somewhat higher wave-
numbers indicating a reduced back bonding of the
metal HOMO into the sulfinato LUMO. The de-
creased S= 0 bond order should result in an increase
in electron density at the sulfinato oxygen atoms
and, therefore, in an enhanced nucleophilicity. Sub-
sequent investigations have shown this to be the
case.
MMPP
I
OC"yRU'
Ph^P
O
„II
(5)
OC"/Ru'
Ph-jP
S—R
SR
CH2CI2
40 °C, 2 h
II
O
7a (72%)
7b (88%)
7c (72%)
6a-c
Me CH2Ph Ph
Synthesis of Cationic Sulfinic Acid Ester
Complexes [CpRu(LXPR,3)(SO(ORM)R)]X
however, a commercially available peracid such as
mCPBA (3-chloroperoxybenzoic acid) can be used
as a substitute which cleanly oxidises the complexes
4a-d to the corresponding sulfinato complexes 5a-d
in good yields (eq. (4)).
Following earlier work of Wojcicki [17] we chose
oxonium salts [R"3 0 ]X as alkylating agents. Treat-
ment of the sulfinato complexes 3a-c and 5a-d with
[Et3 0 ]PFö in dichloromethane at -6 0 °C resulted
in clean reactions to produce cationic sulfinic acid
ester complexes 8a-c and 9a-d in excellent yields
(eqs (6 ), (7)).
The new sulfinic acid ester complexes were ob-
tained as colourless solids which are soluble in
polar media such as chlorinated hydrocarbons or
A similar oxidation protocol using MMPP (mag-
nesium monoperoxyphthalate) gave sulfinato com-
plexes with metal-centred chirality (eq. (5)).
The new sulfinato complexes 5a-d and 7a-c again
are air-stable yellow crystalline solids which are
soluble in toluene and chlorinated solvents. All of acetone. In alcoholic solvents they decompose to
them exhibit the expected spectroscopic properties
featuring low field !H and 13C resonances for both
a -carbon and CH groups. The carbonyl complexes
7a-c show infrared v (CO) absorptions between
1960 and 1980 cm-1 indicating that the sulfinato
anion is a less electron donating ligand in compar-
ison with the thiolate group. The u(S=0) absorp-
tions are in the range expected for S-bound sulfi-
nato complexes [22, 23]. The carbonyl complexes
give back the sulfinato complexes. The 31P NMR
spectra exhibit AB spin systems indicating the in-
equivalence of the phosphorus nuclei due to the
stereogenic centre at sulfur. Similarily the methy-
lene protons of the ethyl groups appear as dis-
tinct AB parts of ABX3 spin systems. The chem-
ical shifts in both the 'H and l3C NMR spectra
are very similar to those of the free ligands [15].
The infrared spectra of the complexes show
a
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530
^
W. A. Schenk and N. Kuhnert • Ruthenium Complexes of Sulfinic Acid Esters
2 ?
^
2 ?
[Me30]BF4, CH2CI2
-60 °C, 10 min
NaX
I
o
I
O
O
i
o
PFc
BF,
OC"yRU'-g/_ R
Me3P "/ U^ s -C H 2Ph
Me3P "/ U^ S -C H 2Ph
Me3P
°C"/ ''s —r
- EtX
ph3p
Me3P
M
Ph3P
OMe
O
OEt
J
O
7a-c
8b
3b
10a (89%, 0% de)
10b (91%, 40% de)
10c (91%, 32% de)
X = I, SMe
(10)
Me CH2Ph Ph
(8)
i
o
.
PfhP
....RU\ //
PFp
Me3P "/R LK S -M e
OL J
CH2Ph
OEt
11a
[Et30]PF6, CH2CI2
-60 °C, 10 min
o
0
Me3P
II
s n
oc-;Ru-
s—R
PFc
OC"yRU-
Ph^P
'S —R
II
O
ph3p
1
OEt
3a
7b, c
11a (91%, 82% de)
11b (92%, 20% de)
40 °C, 4 h
c h 2ci2
(11]
R
CH2Ph
11a
Ph
11b
(9)
medium strong S = 0 Stretching absorption around
1145 cm “ 1.
O
O
33P„ iu . vII
vII
PFp
Me-sP"
Me3P
oc
Me
S—CH2Ph
O
Stereochemistry is an important issue in the alky-
lation reaction, since in compounds with an ad-
ditional element of chirality, the sulfinato oxygen
atoms are diastereotopic. Therefore, we turned our
attention to the CO substituted complexes 7a-c. In
the corresponding iron series an extensive variety
of highly diastereoselective transformations of var-
ious substrates [CpFe(CO)(PPh3)(X)] have been re-
ported, in particular by Davies et al. [24- 26]. Alky-
lation of 7a-c with either [Me^OJBF.; or [Et3 0 ]PF6
gave the diastereomeric sulfinic acid ester com-
plexes lOa-c andlla, b in excellent yields and vary-
ing diastereoselectivities (eqs (8), (9)).
The products are pale yellow crystalline solids
which are soluble in chlorinated hydrocarbons and
acetone. In the infrared spectra the S= 0 stretching
absorption could not be identified unambiguously.
The CO stretching frequency is shifted to still higher
values if compared to the starting materials, which is
a result of the decreased electron density at the metal
centre due to the cationic nature of these complexes.
ph3p
OEt
8a
7b
O
MeCN
80 °C, 15 h
I
II
BF4
10c
P h-S -O M e
OC..-Ru
NCMe
ph,p
(12)
13
12
sulfinato complex 3b and presumably EtI or EtSMe
which were lost during workup (eq. (10)).
In order to further demonstrate the capability of
the new sulfinic acid ester complexes to act as alky-
lating agents, a crossover experiment between the
ester complex 11a and the electron rich and there-
fore more nucleophilic sulfinato complex 3a was
carried out. After 4h under reflux a 10% transfer
of the ethyl group was observed giving the ex-
pected crossover products 7b and 8a respectively
(eq. (11)).
Refluxing a solution of 10c in acetonitrile re-
sulted in an abstraction of the sulfinic acid ester
ligand, yielding the acetonitrile complex 12 [27]
and PhS(0)0M e (13) (eq. (12)).
Reactivity of Cationic Sulfinic Acid Ester
Complexes
In order to gain some preliminary insight into the
reactivity of the new complexes we studied the re-
action of compound 8b with nucleophiles. Reaction
with NaSMe and Nal resulted in complete dealkyla-
tion of the complex, giving back the corresponding
13 was identified by its known spectroscopic
properties [28]. It should be mentioned that we have
recently reported such a demetalation procedure and
suggested a cycle to efficiently recover the quite pre-
cious ruthenium starting materials [1, 14].
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W. A. Schenk and N. Kuhnert • Ruthenium Complexes of Sulfinic Acid Esters
531
162 MHz, H 3PO 4). Chemical shifts b in [ppm], coupling
constants J in [Hz], Signals of aryl groups and signals of
the CH2group of the dppm ligand are uncharacteristic and
have been omitted from the lists of spectral data. PF6-
salts exhibit a septet at b = -144.0 ppm (J = 710 Hz) in
their 31P NMR spectra. Melting or decomposition points
were determined in closed capillaries in a copper block
and are uncorrected.
0
Ä 9®
ll
©
T
Ru—S—R
--------
►
Ru=S—R
(13)
II
II
v
'
O
O
Discussion
Electron-rich ruthenium sulfinato complexes,
which can be formally regarded as metalla-sulfones,
are characterised by a significantly reduced S=0
bond order if compared to regular diorgano-sul-
fones. This reduced bond order is not only expressed
in their low S = 0 stretching frequencies but also in
their enhanced nucleophilicity at oxygen. It should
be kept in mind that sulfones can only be arylated
at oxygen using diazonium salts [29]. The two me-
someric structures shown in equation 13 adequately
describe these properties.
The reason behind this change of structure and re-
activity can be explained in terms of back bonding
from the metal HOMO into the ligand LUMO. By
taking advantage of this metal activating effect we
have been able to synthesise esters of sulfinic acids
in the coordination sphere of a ruthenium complex.
Alkylation of the diastereotopic sulfinato oxygen
atoms can proceed with moderate to good diastere-
oselectivity, depending on the steric demand of the
alkylating agent and, more importantly, on the na-
ture of the chiral ruthenium complex. In particular,
the combination of a very small ligand such as CO
and the bulky triphenylphosphine can give rise to a
selectivity of up to 91:9.
[CpRu(PMe3)2(R)] (2a, b)
To a solution of la (0.69 g, 1.95 mmol) in diethylether
(50 ml), 4 ml of a 0.5 M RMgCl solution (2.00 mmol) in
diethylether was added at room temperature. After 12 h
the reaction mixture was quenched with methanol (1 ml)
and evaporated under vacuum. The residue was extracted
with hexanes (100 ml) and filtered over celite. Removal
of the solvent under vacuum yielded the alkyl complexes
as yellow oils.
2a: Yield 0.53 g (82%), yellow oil. - ]H NMR (C6D6):
4.20 (s, 5H, Cp), 1.11 (vt,N = 9.4 Hz, 18H, PCH3),0.13
(t,7 = 6.7 Hz, 3H, RuCH3). - 13C NMR (C6D6): 80.3 (s,
Cp), 23.0 (X-part of ABX system, N = 26 Hz, PCH3),
-28.50, J= 14H z,R uC H O .-31PN M R (C 6D6): 13.5 (s ).
2b: Yield 0.64 g (80%), yellow oil. - 'H NMR (C6D6):
4.21 (s, 5H, Cp), 2.31 (t, 7 = 6.9 Hz, 2H, RuCH2) 1.08 (vt,
N = 8.2 Hz, 18H, PCH3) . - 31P N M R (C 6D6): 12.4 ( s ).
[CpRu(PMe3)2(S 0 2R)J (3a, b)
A solution of the alkyl complex (1.00 mmol) in toluene
(50 ml) was treated for 5 min with dry gaseous SO2. A
color change to red and back again to yellow was ob-
served. The mixture was stirred for 1 h at room tempera-
ture and then evaporated to 5 ml under vacuum. Addition
of hexane caused the product to crystallize.
The cationic sulfinic acid ester complexes are
readily dealkylated by nucleophiles. This suggests
that they might be useful reagents, having the po-
tential to act as enantioselective alkylating agents.
3a: Yield: 0.36 g (95%), yellow crystalline powder,
m.p. 151 °C (dec). - IR (Nujol): 1132, 1020 cm-1 (SO).
-
'H NMR (CDCI3): 4.37 (s, 5H, Cp), 3.03 (s, 3H,
Experimental Section
SO2CH3), 1.21 (vt, N = 8.8 Hz, 18H, PCH3). - 13C NMR
(CDCI3): 82.9 (s, Cp), 62.6 (s, SCH3), 22.8 (X part of
ABX system, N = 31 Hz, PCH3). - 3,P NMR (CDCI3):
11.4 (s).
3b: Yield: 0.43 g (95%), yellow crystalline powder,
m.p. 181 °C (dec). - IR (Nujol): 1156, 1028 cm-1 (SO).
- 1H NMR (CDCI3): 4.64 (s, 5H, Cp), 4.06 (s, 2H, SCH2),
1.49 (vt, N = 9.3 Hz, 18H, PCH3). - I3C NMR (CDCI3):
82.7 (s, Cp), 78.9 (s, SCH2), 22.8 (X part of ABX system,
N = 32 Hz, PCH3). - 31P NMR (CDCI3): 10.5 (s).
All experiments were carried out in Schlenk tubes
under an atmosphere of dry nitrogen using suit-
ably purified solvents. [CpRu(PMe3)2(Cl)] (la) [30],
[CpRu(PPh3)2(Cl)] (lb) [31] and the thiolato complexes
[CpRu(dppm)(SR)] (R = Me (4a), CH2Ph (4b), Ph (4c)),
[CpRu(CO)(PPh3)(SR)] (R = Me (6a), CH2Ph (6b), Ph
(6c)) [7] were obtained as described in the literature.
3-Chloroperoxybenzoic acid (mCPBA) was dried under
vacuum at 80 °C and titrated iodometrically. Magnesium-
monoperoxyphthalate hexahydrate (MMPP) and all other
reagents were used as purchased.
[CpRu(PMe3)2(S02(4-C6H4Me))] (3c)
The following analytical instruments were used: IR:
Perkin-Elmer 283, Bruker IFS 25; NMR: Bruker AMX
400 ('H , 400 MHz, TMS; 13C, 100 MHz, TMS; 3IP,
A solution of la (0.33 g 1.00 mmol) and sodium tolue-
nesulfinate (0.20 g 1.12 mmol) in a mixture of ethanol
(10 ml) and THF (10 ml) was heated under reflux for 3 h.
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532
W. A. Schenk and N. Kuhnert • Ruthenium Complexes of Sulfinic Acid Esters
The solvent was removed under vacuum, the residue ex-
tracted with benzene (10 ml) and filtered over celite. The
filtrate was taken to dryness and the residue recrystallised
from benzene/hexane.
5c: Yield: 100 mg (73%), yellow crystalline powder,
m.p. 221 - 223 °C (dec). C36H320 2P2RuS (691.7): Calcd
C 62.51, H 4.66. Found C 62.76, H 4.61%.
IR (Nujol): 1132, 1016 cm-1 (SO).
-
'H NMR
(CDCI3): 4.87 (s, 5H, Cp). - 31P NMR (CDC13): 12.5 (s).
5d: Yield: 110 mg (76%), yellow crystalline powder,
m.p. 238 °C (dec). C38H360 2P2RuS (719.8): Calcd C
63.41, H 5.04. Found C 63.12, H 5.13%.
Yield 0.43 g (92%), yellow crystalline powder, m. p.
176 °C (dec). - IR (Nujol): 1144, 1020 cm“ 1 (SO). - 'H
NMR (CDC13): 4.52 (s, 5H, Cp), 2.32 (s, 3H, CH3), 1.51
(vt, N = 9.2 Hz, 18H, PCH3). - 13C NMR (CDCI3): 83.7
(s, Cp), 22.8 (X part of ABX system, N = 32 Hz, PCH3),
21.1 (s, CH3) . - 31PN M R (CDCI3): 11.2 (s).
IR (Nujol): 1144, 1020 cm“ 1 (SO).
-
’H NMR
(CDC13): 4.89 (s, 5H, Cp), 3.24, (AA'XX' system, N =
16.9 Hz, 2H, SCH2), 2.85 (AA'XX’system, N = 16.9 Hz,
2H, PhCH2). - l3C NMR (CDC13): 81.8 (s, Cp), 72.6 (s,
SCH2), 31.7 (s, PhCH2). - 31P NMR (CDC13): 13.9 (s).
[CpRu(dppm)(SCH2CH2Ph)] (4d>
A solution of lb (0.73 g 1.00 mmol), NaSCH2CH2Ph
(0.19 g 1.20 mmol), and dppm (0.46 g 1.20 mmol) in a
mixture of THF (20 ml) and ethanol (15 ml) was heated
for 2 h under reflux. The solvent was removed under vac-
uum and the residue purified by column chromatography
(silica gel, eluent Et20/TH F 2:1). The broad yellow band
was collected, evaporated, and the residue further purified
by recrystallisation from toluene/hexane.
Yield: 0.58 g (84%), yellow crystalline powder, m.p.
163 °C (dec). C38H36P2RuS (687.8): Calcd C 66.36, H
5.28. Found C 66.36, H 5.26%.
'H NMR (CDC13): 4.82 (s, 5H, Cp), 2.85 (AA'XX'
system, N = 16.9 Hz, 2H, SCH2), 2.65 (AA'XX' system,
N = 17.1 Hz, 2H, PhCH2). - 13C NMR (CDC13): 78.5
(s, Cp), 41.5 (s, SCH2), 37.9 (s, PhCH2). - 31P NMR
(CDC13): 15.8 (s).
[CpRu(CO)(PPhj)(S02R)] (7a-c)
A solution of the thiolate complex (0.86 mmol) and
magnesium monoperoxyphthalate hexahydrate (0.50 g,
1.00 mmol) in dichloromethane (20 ml) was heated under
reflux for 2 h. The solvent was removed in vacuum and the
residue filtered over a 5 cm A120 3plug, eluting with 30 ml
CH2Cl2/acetone 2:1. The filtrate was taken to dryness
and the product further purified by crystallisation from
benzene/hexane.
7a: Yield: 0.33 g (72%), yellow crystalline powder,
m. p. 189 -191 °C (dec). The spectroscopic data are iden-
tical to those previously reported [21].
7b: Yield: 0.46 g (88%), yellow crystalline powder,
m.p. 173 - 174 °C (dec). C3,H 270 3PRuS (611.7): Calcd
C 60.87, H 4.45. Found C 60.89, H 4.31%.
IR (Nujol): 1960 (CO), 1172, 1040 cm "1 (SO). - 'H
NMR (CDC13): 4.24 (s, 5H, Cp), 4.30, 4.20 (AB system,
J = 12.0 Hz, 2H, SCH2). - l3C NMR (CDC13): 203.2 (d,
J = 18 Hz, CO), 89.3 (s, Cp), 78.5 (s, SCH2). - 31P NMR
(CDC13): 47.3 (s).
7c: Yield: 0.37 g (72%), yellow crystalline powder,
m.p. 168 - 171 °C (dec). C30H25O3PRuS (597.6): Calcd
C 60.29, H 4.22. Found C 60.04, H 4.24%.
[CpRu(dppm)(SO2R)] (5a-d)
A suspension of 3-chloroperoxybenzoic acid (85%,
82 mg, 0.42 mmol) in dichloromethane (5 ml) was slowly
added at -60 °C to a solution of the thiolate complex
(0.20 mmol) in dichloromethane (5 ml). The mixture was
stirred for 15 min at that temperature with the colour
changing from orange via dark red / yellow to pur-
ple. The solvent was removed under vacuum and the
crude product purified by column chromatography eluting
with CH2Cl2/acetone 2:1 (two components-column: up-
per layer 10 cm A120 3, basic, activity grade I; lower layer
10 cm A120 3, neutral, activity grade I). The first yellow
band contained the product which was further purified by
crystallisation from benzene/hexane.
5a: Yield 37 mg (24%), yellow crystalline powder.
The spectroscopic data are identical to those previously
reported [23].
5b: Yield: 100 mg (71%), yellow crystalline powder,
m.p. 212 °C (dec). C37H340 2P2RuS (705.8): Calcd C
62.97, H 4.86. Found C 63.25, H 4.88%.
IR (Nujol): 1980 (CO), 1176, 1036 cm "1 (SO). - 'H
NMR (CDC13): 4.70 (s, 5H, Cp). - 31P NMR (CDC13):
47.3 (s).
Alkylation o f the sulfinato complexes
To a solution of the sulfinato complex (0.10 mmol)
in dichloromethane (5 ml) either [E t30 ]P F 6 (24 mg,
0.09 mmol) or [Me30]BF4 (14 mg, 0.09 mmol) was
added at -60 °C. The mixture was allowed to warm
slowly to room temperature. The solvent was re-
moved under reduced pressure, the residue washed
three times with benzene (3 ml) and recrystallised from
dichloromethane/hexane.
IR (Nujol): 1156, 1024 cm-1 (SO). - 'H NMR
(CDCI3): 4.82 (s, 5H, Cp), 3.45 (s, 2H, SCH2). - 13C
NMR (CDC13): 82.6 (s, Cp), 74.1 (s, SCH2). - 31P NMR
(CDC13): 13.4 (s).
[CpRu(PMe3)2(S(0)(OEt)Me)]PF6 (8a)
Yield: 50 mg (90%), colourless crystalline powder,
m. p. 76 - 79 °C (dec).
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W. A. Schenk and N. Kuhnert • Ruthenium Complexes of Sulfinic Acid Esters
533
C,4H3iF602P3RuS (571.4): Calcd C 29.43, H 5.47. Found
C 30.02, H 5.54%.
IR (Nujol): 1168 cm 1 (SO). - 1H NMR (acetone-dö):
5.32 (s, 5H, Cp), 4.29, 3.89 (AB system, 7 = 13.4 Hz, 2H,
SCH2), 2.95 - 2.89 (m, 2H, OCH2), 0.79 (t, 7 = 7.1 Hz,
3H, CH3). - 13C NMR (acetone-dö): 85.1 (s, Cp), 75.0
(s, SCH2), 63.5 (s, OCH2), 14.2 (s, CH3). - 31P NMR
(acetone-dö): 6.6, 4.7 (AB system, 7 = 84 Hz).
IR (Nujol): 1133 cm-1 (SO). - 'H NMR (acetone-
dö): 5.32 (s, 5H, Cp), 4.31, 4.11 (ABX3 system, 7 = 9.7,
7.1 Hz, 2H, OCH2), 3.58 (s, 3H, SCH3), 1.71 (vt, N =
8.8 Hz, 18H, PCH3), 1.38 (t, 7 = 7.1 Hz, 3H ,CH 3) . - 13C
NMR (acetone-d6): 85.6 (s, Cp), 60.5 (s, OCH2), 57.4
(s, SCH3), 20.9 (m, PCH3), 14.5 (s, CH3). - 31P NMR
(acetone-dö): 7.6, 7.3 (AB system, 7 = 40 Hz).
[CpRu(dppm)(S(0)(OEtjPh)]PF(, (9c)
Yield: 80 mg (93%), colourless crystalline powder,
m.p. 137 - 140 °C (dec). C38H37F6O2P3RUS (865.8):
Calcd C 52.72, H 4.31. Found C 53.07, H 4.58%.
IR (Nujol): 1148 cm-1 (SO). - 'H NMR (acetone-d6):
5.40 (s, 5H, Cp), 3.21,3.16 (ABX3system, 7 = 9.9,7.1 Hz,
2H, OCH2), 0.95 (t, 7 = 7.1 Hz, 3H, CH3). - 13C NMR
(acetone-dö): 151.9 (s, SC), 85.7 (s, Cp), 63.5 (s, OCH2),
14.5 (s, CH3). - 31P NMR (acetone-d6): 6.0 (s).
[CpRu(PMe3)2(S(0)(0Et) CH2Ph)]PF6 (8b)
Yield: 60 mg (92%), colourless crystalline powder,
m. p. 76 - 79 °C (dec). C2oH35F602P3RuS (647.5): Calcd
C 37.10, H 5.45. Found C 37.08, H 5.69%.
IR (Nujol): 1168 cm' 1 (SO). - 'H NMR (acetone-dö):
5.27 (s, 5H, Cp), 5.01,4.68 (AB system, 7 = 13.4 Hz, 2H,
SCH2), 4.11, 3.83 (m, 2H, OCH2), 1.70 (d, 7 = 10.0 Hz,
9H, PCH3), 1.50 (d, 7 = 9.9 Hz, 9H, PCH3), 0.79 (t,
7 = 7.1 Hz, 3H, CH3). - 13C NMR (acetone-d6): 86.6 (s,
Cp), 77.4 (s, SCH2), 63.0 (s, OCH2), 22.4 (d, 7 = 32 Hz,
PCH3), 22.3 (d, 7 = 31 Hz, PCH3), 15.6 (s, CH3). - 31P
NMR (acetone-dö): 7.3, 5.3 (AB system, 7 = 41 Hz).
[CpRu(dppm)(S(0)(0Et)CH2CH2Ph)]PF6 (9d)
Yield: 77 mg (86%), colourless crystalline powder,
m.p. 139 - 140 °C (dec). C4oH4iF602P3RuS (893.8):
Calcd C 53.75, H 4.62. Found C 53.44, H 4.65%.
IR (Nujol): 1154 cm-1 (SO). - 'H NMR (acetone-
d6): 5.56 (s, 5H, Cp), 3.49 (m, 2H, OCH2), 3.42 (m, 1H,
SCH2), 3.24 (m, 1H, SCH2), 2.57 (m, 2H, PhCH2), 1.08
(t, 7 = 7.0 Hz, 3H, CH3). - 13C NMR (acetone-d6): 85.0
(s, Cp), 73.0 (s, SCH2), 62.8 (s, OCH2), 28.0 (s, PhCH2),
14.5 (s, CH3). - 31P NMR (acetone-d6): 6.4, 5.1 (AB
system, 7 = 86 Hz).
[CpRu(PMe3)2(S(0 )(0 Et)(4 -C6H4Me))]PF6 (8c)
Yield: 58 mg (89%), colourless crystalline powder,
m. p. 79 - 80 °C (dec). C2oH35F60 2P3RuS (647.54): Calcd
C 37.10, H 5.45. Found C 36.83, H 5.26%.
IR (Nujol): 1144 cm-1 (SO). - ’H NMR (acetone-dö):
5.13 (s, 5H, Cp), 3.97,3.49 (ABX3system, 7 = 9.9,7.1 Hz,
2H, OCH2), 2.44 (s, 3H, CH3), 1.78 (d, 7 = 10.0 Hz, 9H,
PCH3), 1.54 (d, 7 = 10.0 Hz, 9H, PCH3), 1.25 (t, 7 =
7.1 Hz, 3H, CH 3 ). - 13C NMR (acetone-d6): 151.5, (s,
SC), 85.3 (s, Cp), 63.7 (s, OCH2), 22.8 (d, 7 = 34 Hz,
PCH3 ), 22.2 (d, 7 = 34 Hz, PCH3 ), 21.9 (s, C H 3), 15.9 (s,
C H3 ). - 31P NMR (acetone-dö): 7.7, 7.5 (AB system, 7 =
41 Hz).
[CpRu(PPh3)(C0)(S(0)(0M e)M e)]BF4 (10a)
This compound was obtained as a 50:50 mixture of
diastereoisomers. Yield: 57 mg (89%), colourless crys-
talline powder, m.p. 113 °C (dec). C26H26BF4O3PRUS
(637.4): Calcd C 48.99, H 4.11. Found C 48.13, H 4.13%.
IR (Nujol): 2008 (CO) cm-1. Both diastereoisomers:
'H NMR (acetone-d6): 5.57 (s, 5H, Cp), 5.27 (s, 5H, Cp),
3.57 (s, 3H, CH3), 3.50 (s, 3H, CH3), 3.47 (s, 3H, CH3),
3.40 (s, 3H, CH3). - ,3C NMR (acetone-d6): 203.2 (s, br,
CO), 200.8 (s, br, CO), 92.1 (s, Cp), 91.3 (s, Cp), 69.3
(s, SCH3), 52.9 (s, OCH3), 52.7 (s, OCH3). - 31P NMR
(acetone-dö): 43.1 (s), 42.2 (s).
[CpRu(dppm)(S(())(OEt)Me)]PF(, (9a)
Yield: 75 mg (93%), colourless crystalline powder,
m.p. 109 °C (dec). C33H35F6O2P3RUS (803.7): Calcd C
49.32, H 4.39. Found C 47.02, H 4.18%.
IR (Nujol): 1151cm-1 (S O ).-'H NMR (acetone-dö):
5.49 (s, 5H, Cp), 3.48 (ABX3 system, 7 = 9.6, 7.1 Hz, 2H,
OCH2), 3.02 (s, 3H, SCH3), 0.98 (t, 7 = 7.1 Hz, 3H, CH3).
- 13C NMR (acetone-dö): 85.1 (s, Cp), 60.3 (s, OCH2),
55.8 (s, SCH3 ), 14.5 (s, CH3 ). - 31P NMR (acetone-dö):
7.2, 6.2 (AB system, 7 = 86 Hz).
[CpRu(PPh3)(CO)(S(0)(OMe)CH2Ph)]BF4 (10b)
This compound was obtained as
ture of diastereoisomers. Yield: 65 mg (91%), colour-
less crystalline powder, m.p. 124 126 °C (dec).
a 70:30 mix-
-
C32H30BF4O3PRUS (713.5): Calcd C 53.87, H 4.24.
Found C 53.95, H 4.32%.
[CpRu(dppm)(S(0)(OEt)CH2Ph)]PF6 (9b)
Yield: 75 mg (86%), colourless crystalline powder,
m.p. 109 °C (dec). C39H39F6O2P3RUS (879.8) Calcd C
53.24, H 4.47. Found C 52.46, H 4.71%.
IR (Nujol): 2012 (CO) cm- 1.-Majordiastereoisomer:
'H NMR (acetone-d6): 5.41 (s, 5H, Cp), 5.11, 4.72 (AB
system, 7= 12.9 Hz, 2H, SCH2), 3.24 (s, 3H, OCH3). - 13C
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534
W. A. Schenk and N. Kuhnert • Ruthenium Complexes of Sulfinic Acid Esters
NMR (acetone-dö): 199.6 (d, J - 20 Hz, CO), 91.4 (s, Cp),
74.6 (s, SCHt), 52.8 (s, OCH3). - 31P NMR (acetone-dö):
42.0 (s). Minor diastereoisomer: 'H NMR (acetone-dö):
5.60 (s, 5H, Cp), 4.94,4.62 (AB system, J = 13.6 Hz, 2H,
SCH2), 3.49 (s, 3H, OCH3). - 13C NMR (acetone-d6):
200.3, (d, J= 20 Hz, CO), 90.9 (s, Cp), 75.1 (s, SCH2),
53.4 (s, OCH3). - 31P NMR (acetone-d6): 41.9 (s).
IR (Nujol): 2008 (CO) cm '. Major diastereoisomer:
1H NMR (acetone-d6): 5.46 (s, 5H. Cp), 3.82,3.49 (ABX3
system, J = 9.9, 7.0 Hz, 2H. OCH2), 1.09 (t, J = 7.0 Hz,
3H, CH3). - 31P NMR (acetone-dö): 42.6 (s). Minor di-
astereoisomer: 'H NMR (acetone-dö): 5.35 (s, 5H, Cp),
4.19, 4.17 (ABX3 system, J = 9.9, 7.1 Hz, 2H, OCH2),
0.96 (t, J = 7.1 Hz, 3H, CH3). - 31P NMR (acetone-d6):
43.3 (s).
[CpRu(PPh3)(C0)(S(0)(0Me)Ph)]BF4(10c)
Reaction o f [CpRu(PMe3)2(S(0)(0Et)CH2Ph)]PF6 (8b)
with Nal and NaSMe
This compound was obtained as
ture of diastereoisomers. Yield: 64 mg (91%), colour-
less crystalline powder, m.p. 124 126 °C (dec).
C31H28BF4O3PRUS (699.5): Calcd C 53.23, H 4.04.
Found C 52.95, H 3.82%.
IR (Nujol): 2008 (CO) cm- 1 . Major diastereoisomer:
'H NMR (acetone-dö): 5.28 (s, 5H, Cp), 2.98 (s, 3H,
OCH3). - 13C NMR (acetone-d6): 200.1 (s, br, CO), 91.9
(s, Cp), 52.6 (s, OCH3). - 31P NMR (acetone-dö): 42.5
(s). Minor diastereoisomer: 'H NMR (acetone-dö): 5.50
(s, 5H, Cp), 3.20 (s, 3H, OCH3). - 13C NMR (acetone-
d6): 200.1, (s, br, CO), 92.0 (s, Cp), 53.7 (s, OCH3) . - 31P
NMR (acetone-dö): 43.1 (s).
a 66:34 mix-
-
A suspension of 8b (65 mg, 0.10 mmol) and either
Nal (15 mg, 0.10 mmol) or NaSMe (7 mg, 0.10 mmol)
in dichloromethane (3 ml) was stirred for 24 h at 20 °C.
The solvent was removed under reduced pressure and the
residue examined by NMR spectroscopy to show [CpRu-
(PMe3)2(S02CH2Ph)] (3b) exclusively.
Crossover experiment betw'een [CpRu(CO)<PPh3)(S(O)-
(OEt)CH2Ph)]PF6 (11a) and [CpRu(PMe3)(S02CH3)]
(3a)
A solution of 11a (32 mg, 0.04 mmol) and 3a (20 mg,
0.05 mmol) in dichloromethane (5 ml) was heated for
4 h under reflux. The solvent was removed under re-
duced pressure and the residue examined by NMR spec-
troscopy to show, besides the starting materials, 10% of
the crossover products [CpRu(C0 )(PPh3)(S02CH2Ph)J
(7b) and [CpRu(PMe3)2(S(0 )(0 Et)CH3)]PF6 (8a)
[CpRu(PPh3)(C0)(S(0)(0Et)CH2Ph)]PF6 (1 1 a)
This compound was obtained as
of diastereoisomers. Yield: 71 mg (91%), colour-
less crystalline powder, m.p. 126 129 °C (dec).
a 91:9 mixture
-
C33H32F6O3P2RUS (785.7): Calcd C 50.45, H 4.11, S
4.08. Found C 49.53, H 3.97, S 3.97%.
IR (Nujol): 2009 (CO) cm-1 . Major diastereoisomer:
'H NMR (acetone-d6): 5.33 (s, 5H, Cp), 5.02, 4.76 (AB
system, J = 13.3 Hz. 2H, SCH2), 4.03, 3.67 (ABX3 sys-
tem, J = 9.6, 7.1 Hz, 2H, OCH2), 0.87 (t, J = 7.1 Hz,
3H, CH3). - 13C NMR (acetone-d6): 200.6 (d, J = 18 Hz,
CO), 91.7 (s, Cp), 74.8 (s, SCH2), 64.7 (s, OCH2), 17.4
(s, OCH3). - 31P NMR (acetone-dö): 42.1 (s). Minor di-
astereoisomer: 'H NMR (acetone-dö): 5.63 (s, 5H, Cp),
5.17, 4.76 (AB system, J = 13.0 Hz, 2H, SCH2), 3.99,
3.65 (m, 2H, OCH2), 1.25 (t, J = 7.0 Hz, 3H, CH3). - 31P
NMR (acetone-dft): 41.9 (s).
Ligand exchange reaction
A solution of 10c (50 mg, 0.07 mmol) in acetonitrile
(5 ml) was heated for 2 h under reflux. The solvent was re-
moved in vacuum and the residue dissolved in acetone-dö
and examined by NMR spectroscopy, which showed the
quantitative formation of [CpRu(CO)(PPh3)(NCCH3)]-
BF4 (12) {'H NMR (acetone-d6): 5.31 (s, 5H, Cp), 2.11
(s, 3H, NCMe). 3,P NMR (acetone-d6): 49.0 (s)} and
PhS(0)0M e (13). The sulfinic acid ester 13 was separated
from the reaction mixture by extraction with diethylether
(10 ml). It exhibited spectroscopic properties identical to
those described in [28].
[CpRu(PPh3)(C0)(S(0)(0Et)Ph)]PF6(lib )
This compound was obtained as
ture of diastereoisomers. Yield: 71 mg (92%), colour-
less crystalline powder, m.p. 121 122 °C (dec).
C32H3oF60 3P2RuS (771.7): Calcd C 49.81, H 3.92. Found
C 49.82, H 3.48%.
a 60:40 mix-
Acknowledgements
This work was funded by the Deutsche Forschungsge-
meinschaft within the Sonderforschungsbereich 347, and
by the Fonds der Chemischen Industrie, Frankfurt/Main.
-
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W. A. Schenk and N. Kuhnert • Ruthenium Complexes of Sulfinic Acid Esters
535
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