Thiaplatinacycles derived from dibenzothiophene-containing phosphites as auxiliary ligands and their role in homogeneous desulfurization reactions

Article abstract of DOI:10.1021/om034126r

The reaction of complex [Pt(η²-C,S-C₁₂ H₈)(PEt₃)₂], 1, with a variety of phosphites afforded compounds of the type [Pt(η²-C,S- C₁₂H₈)(PEt₃)(P(OR)₃)], where R = Et, ⁱPr, and Ph (2a, 2b, 3, and 4, respectively) and [Pt(η²-C,S-C₁₂H₈) (P(OR)₃)₂], where R = Et (5). Compounds 2-4 were used to model a desulfurization process and were compared with 1 and other similar compounds. Under comparable conditions, the amount of desulfurization depended on the σ-donor/π-acceptor properties and the steric effects of the ligands and of the use of alumina in the reaction media. X-ray crystal structures are reported for 2b and 3.

Full text of DOI:10.1021/om034126r

4734
Organometallics 2003, 22, 4734-4738
Th ia p la tin a cycles Der ived fr om
Diben zoth iop h en e-Con ta in in g P h osp h ites a s Au xilia r y
Liga n d s a n d Th eir Role in Hom ogen eou s Desu lfu r iza tion
Rea ction s
Graciela Picazo, Alma Are´valo, Sylvain Berne`s,† and J uventino J . Garc´ıa*
Facultad de Qu´ımica, Universidad Nacional Auto´noma de Me´xico, Me´xico, D. F. 04510
Received August 23, 2003
The reaction of complex [Pt(η2-C,S-C12H8)(PEt3)2], 1, with a variety of phosphites afforded
i
compounds of the type [Pt(η2-C,S-C12H8)(PEt3)(P(OR)3)], where R ) Et, Pr, and Ph (2a , 2b,
3, and 4, respectively) and [Pt(η2-C,S-C12H8)(P(OR)3)2], where R ) Et (5). Compounds 2-4
were used to model a desulfurization process and were compared with 1 and other similar
compounds. Under comparable conditions, the amount of desulfurization depended on the
σ-donor/π-acceptor properties and the steric effects of the ligands and of the use of alumina
in the reaction media. X-ray crystal structures are reported for 2b and 3.
In tr od u ction
produce the corresponding thiaplatinacycles. Such de-
rivatives have been demonstrated to be useful interme-
diates for organic transformations,7 for stoichiometric
hydrodesulfurizations4,8 and as active precursors in
homogeneous HDS catalytic reactions as well.9 Very few
other thiaplatinacycles derived from thiophenes have
The study of hydrodesulfurization (HDS) has been the
focus of high interest because of the need to improve
the process used to remove sulfur from organosulfur
molecules present in crude oil feedstocks.1 The com-
mercial HDS process currently uses the cobalt- or nickel-
doped molybdenum sulfide catalyst supported on alu-
mina; however, the highest activity has been shown by
platinum group metals, such as Ru, Os, Rh, Ir, Pd, and
Pt, at least in model reactor studies, but they are not
commercially used because of their higher cost.2 Thus,
a variety of organometallic compounds containing tran-
sition metals have been studied in homogeneous HDS
reactions with thiophenes.3 Although to date there are
several reports leading to a C-S bond cleavage for
thiophenes in complexes containing one metal and also
several metal centers, the use of phosphites as auxiliary
ligands in the organometallic modeling of HDS has been
virtually ignored.
10
been reported, such as J ones’ ring-opened 4,6-dimeth-
yldibenzothiophene reactions with [(dippe)Pt(H)]2 as a
model for deep HDS and also one by Sweigart,11 who,
using arene derivatives containing carbonyl-metal
moieties, “remote actived” π-coordinated thiophenes to
make the coordinated thiophene more susceptible to
nucleophilic cleavage than in the corresponding free
thiophene.
In the present study, we investigated the effect of
replacing a phosphine ligand (PEt3) by a phosphite in
the thiaplatinacycle [Pt(η2-C,S-C12H8)(PEt3)2] and its
result on the reactivity of the new complexes under HDS
conditions; the effect of acid and basic alumina on the
reaction media was also studied.
Our group, interested in the use of platinum metals
to activate thiophenes, particularly with the use of [Pt-
(PEt3)3], has found that it is possible to activate C-S
bonds in dibenzothiophene4 and other thiophenes5,6 to
Resu lts a n d Discu ssion
Rea ction of [P t(η2-C,S-C12H8)(P Et3)2], 1, w ith
Tr ieth yl P h osp h ite. The reaction at room temperature
of [Pt(η2-C,S-C12H8)(PEt3)2] with P(OEt)3 in toluene
yields three different compounds, two of them with the
formulation of [Pt(η2-C,S-C12H8)(PEt3)(P(OR)3)], 2a and
2b, and one more with the formulation [Pt(η2-C,S-
* To whom correspondence should be addressed. E-mail: juvent@
servidor.unam.mx.
† Current address: Centro de Qu´ımica, Instituto de Ciencias, BUAP,
Puebla, Me´xico.
(1) (a) Topsøe, H.; Clausen, B. S.; Massoth, F. E. Hydrotreating
Catalysis: Science and Technology; Springer-Verlag: Berlin, 1996. (b)
Kabe, T.; Ishihara, A.; Qian, W. Hydrodesulfurization and Hydrodeni-
trogenation: Chemistry and Engineering; Kondasa-Wiley-VCH: Tokyo,
1999.
(6) Are´valo, A.; Berne`s, S.; Garc´ıa, J . J .; Maitlis, P. M. Organome-
tallics 1999, 18, 1680.
(2) Pecoraro, T. A.; Chianelli, R. R. J . Catal. 1981, 67, 430.
(3) For recent reviews see: (a) Sanchez-Delgado, R. A. Organome-
tallic Modeling of the Hydrodesulfurization and Hydrodenitrogenation
Reactions; Kluwer Academic Publishers: Dordrecht, 2002. (b) Angelici,
R. J . Organometallics 2001, 20, 1259. (c) Angelici, R. J . Polyhedron
1997, 16, 3073.
(4) (a) Garc´ıa, J . J .; Mann, B. E.; Adams, H.; Bailey, N. A.; Maitlis,
P. M. J . Am. Chem. Soc. 1995, 117, 2179. (b) Garc´ıa, J . J .; Maitlis, P.
M. J . Am. Chem. Soc. 1993, 115, 12200.
(7) Garc´ıa, J . J .; Are´valo, A.; Montiel, V.; Del Rio, F.; Quiroz, B.;
Adams, H.; Maitlis, P. M. Organometallics 1997, 16, 3216.
(8) Iretskii, A.; Garc´ıa, J . J .; Picazo, G.; Maitlis, P. M. Catal. Lett.
1998, 51, 129.
(9) Herna´ndez, M.; Miralrio, G.; Are´valo, A.; Berne`s, S.; Garc´ıa, J .
J .; Lo´pez, C.; Maitlis, P. M.; Del R´ıo, F. Organometallics 2001, 20, 4061.
(10) Vicic, D. A.; J ones, W. D. Organometallics 1998, 17, 3411.
(11) (a) Dullagham, C. A.; Zhang, X.; Greene, D. L.; Carpenter, G.
B.; Sweigart, D. A.; Camiletti, C.; Rajaseelan, E. Organometallics 1998,
17, 3316. (b) Li, H.; Carpenter, G. B.; Sweigart, D. A. Organometallics
2000, 19, 1823. (c) Yu, K.; Li, H.; Watson, E. J .; Virkaitis, K. L.;
Carpenter, G. B.; Sweigart, D. A. Organometallics 2001, 20, 3550.
(5) Garc´ıa, J . J .; Are´valo, A.; Capella, S.; Chehata, A.; Herna´ndez,
M.; Montiel, V.; Picazo, G.; Del Rio, F.; Toscano, R.; Adams, H.; Maitlis,
P. M. Polyhedron 1997, 16, 3185.
10.1021/om034126r CCC: $25.00 © 2003 American Chemical Society
Publication on Web 10/11/2003

Thiaplatinacycles Derived from Phosphites
Organometallics, Vol. 22, No. 23, 2003 4735
Sch em e 1
C12H8)(P(OEt)3)2], 5 (Scheme 1). As expected, both
compounds 2a and 2b are isomeric forms, one with the
phosphite trans to carbon and the other with the
phosphite trans to sulfur of the thiaplatinacycle moiety,
respectively. The NMR spectra of crude reaction mix-
tures showed evidence of the formation of three different
compounds, all of which were isolated by differences in
solubility and further purification by column chroma-
tography. 31P NMR was especially useful to differentiate
each particular compound, compound 2a showing the
characteristic pattern expected for two nonequivalent
cis phosphorus atoms with resonances at δ 15.4 (1J (Pt-
P) ) 3084 Hz, 2J (P-P) ) 28 Hz) for the phosphine trans
2
to S and δ 123.3 (1J (Pt-P) ) 3065 Hz, J (P-P) ) 28
Hz) for the phosphite trans to C; complex 2b exhibited
a similar pattern, with resonances at δ 10.6 (1J (Pt-P)
2
) 1691 Hz, J (P-P) ) 28 Hz) for the phosphine trans
F igu r e 1. Molecular structure of complex 2b with thermal
ellipsoids at the 30% probability level.
2
to C and δ 104.7 (1J (Pt-P) ) 5405 Hz, J (P-P) ) 28
Hz) for the phosphite trans to S. These assignments are
in agreement with the values previously observed for
thiaplatinacycles containing only monodentate phos-
phines as auxiliary ligands.4-6 Complex 2b was also
characterized by an X-ray structure determination, the
latter confirming that the phosphite ligand was trans
to sulfur. Complex 5 was characterized considering the
above quoted chemical shifts and coupling constants;
the 31P NMR spectrum exhibited a pattern similar to
those described above, with resonances at δ 107.0
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 2b
Pt(1)-C(13)
Pt(1)-P(2)
S(5)-C(12)
C(10)-C(13)
2.076(5)
2.330(2)
1.771(6)
1.400(8)
Pt(1)-P(1)
Pt(1)-S(5)
C(6)-C(13)
2.210(2)
2.355(2)
1.391(8)
C(13)-Pt(1)-P(1)
P(1)-Pt(1)-P(2)
P(1)-Pt(1)-S(5)
C(12)-S(5)-Pt(1)
89.1(2)
C(13)-Pt(1)-P(2) 168.8(2)
100.98(6) C(13)-Pt(1)-S(5)
84.4(2)
172.86(6) P(2)-Pt(1)-S(5)
85.28(6)
C(6)-C(13)-Pt(1) 122.6(5)
95.7(2)
2
(1J (Pt-P) ) 2938 Hz, J (P-P) ) 44 Hz) for the phos-
C(10)-C(13)-Pt(1) 119.9(4)
phite trans to C and δ 123.3 (1J (Pt-P) ) 5160 Hz, 2J (P-
P) ) 44 Hz) for the phosphite trans to S. As can be seen
consequently, the three remaining angles are slightly
smaller, since the P-Pt-P angles are significantly
larger than 90°; this can be due to steric repulsion
between the phosphine and the phosphite. This is
slightly larger for 2b in the solid state. Key bond lengths
in complex 2b are Pt-S(5) ) 2.355(2) Å, Pt-C(13) )
2.076(5) Å, Pt-P(1), which is trans to S(5), ) 2.210(2)
Å, and Pt-P(2), which is trans to C(13), ) 2.330(2) Å.
Again the difference in distances is due to the trans
influence of the σ-bonded sp2 carbon. In general, the
distances quoted above are very similar to those seen
in the closely related platinum complexes, such as 1,5
where the Pt-P(1) distance, trans to sulfur, is 2.261(4)
Å, just a bit longer than the corresponding distance in
2b, probably due to the phosphite π-acceptor properties.
Rea ction s of [P t(η2-C,S-C12H8)(P Et3)2], 1, w ith
Tr iisop r op yl P h osp h ite. Similar to the reaction dis-
1
from the data quoted above, the value of J (Pt-P) for
the phosphite ligand trans to carbon is always smaller
1
than the corresponding value of J (Pt-P), where the
phosphite is trans to sulfur, as expected; this is due to
the higher trans influence of the σ-bonded sp2 carbon.
X-r a y Str u ctu r e of Th ia p la tin a cycle 2b. The thia-
platinacycle derived from dibenzothiophene-containing
triethylphosphine and triethyl phosphite is depicted in
Figure 1; selected bond lengths and angles are given in
Table 1. The thiaplatinacycle moiety in complex 2b is
severely twisted, in a very similar way to the previously
reported structure for 15 and similar to complex 3 (vide
infra). A few important structural features for 2b are
the following: the angle P(1)-Pt-P(2) ) 100.98(6)° is
a bit more open compared with the corresponding value
for 1, which is 99.1(2)°, and for 3, which is 97.76(4)°;

4736 Organometallics, Vol. 22, No. 23, 2003
Picazo et al.
Ta ble 3. Resu lts of Hyd r od esu lfu r iza tion
Exp er im en ts
products with
acid alumina
products with
basic alumina
products
compound
%Ph-Ph %DBT %Ph-Ph %DBT %Ph-Ph %DBT
1
9a
83
85
41
40
22a
89a
16
15
52
90
89
70
75
74a
31
10
11
30
25
16a
74
93
94
90
88
74
15
4
5
7
12
15
2a
2b
3
59
4
60
[Pt(DBT)(dppe)]
34a
a
Data from ref 8 for comparison purposes.
trans to S(5), ) 2.2771(12) Å, and Pt-P(2), which is
trans to C(13), ) 2.2794(12) Å, in contrast to complexes
1 and 2b. In this case both Pt-P distances are nearly
the same; that is, the strong trans influence of a
σ-bonded sp2 toward a phosphite results almost in the
same magnitude as the trans influence of a thiolate type
ligand toward an alkyl phosphine.
Rea ction s of [P t(η2-C,S-C12H8)(P Et3)2], 1, w ith
Tr ip h en yl P h osp h ite. Following the very same pro-
cedure used for 3, complex 1 reacted with P(OPh)3 to
yield a product with the formulation [Pt(η2-C,S-C12H8)-
(PEt3)(P(OPh)3)], 4 (Scheme 1), where the phosphite
ligand is in trans position to sulfur and the phosphine
is trans to carbon of the thiaplatinacycle moiety. The
spectroscopic evidence is in agreement with such a
proposal; for instance, in the 31P NMR complex 4
exhibited a pattern with resonances at δ 10.1 (1J (Pt-
P) ) 1645 Hz, 2J (P-P) ) 27 Hz) for the phosphine trans
to C and δ 94.3 (1J (Pt-P) ) 5623 Hz, 2J (P-P) ) 27 Hz)
for the phosphite trans to S. These assignments are in
agreement with the values previously observed for
complex 2b (vide supra). An important diagnostic signal
in the 13C NMR is the quaternary carbon directly
bonded to platinum at δ 153.1 (2J (C-trans-P) ) 108 Hz,
2J (C-cis-P) ) 7 Hz); no platinum satellites could be
observed due to the weakness of this signal of the
quaternary carbon.
Hyd r od esu lfu r iza tion Exp er im en ts. As earlier
mentioned, it has been shown that thiaplatinacycles are
useful precursors or intermediates in HDS reactions.
Considering this and following a procedure previously
reported,8 a series of experiments were performed to
evaluate the relevance of having a coordinated phos-
phite and the effect of alumina in such a process.
Complexes 1-4 undergo HDS with hydrogen alone
under relatively mild conditions (H2, 20 atm, 100 °C,
20 h, toluene, Table 3). In contrast with our previous
findings with thiaplatinacycles containing only alkyl
phosphines as auxiliary ligands, here all thiaplatina-
cycles containing a phosphite and a phosphine carry out
desulfurization in relatively good yields without the use
of alumina, complex 2b being the best (85%). HDS of
complexes 1-4 is significantly enhanced by the presence
of acid alumina, the complexes being of the type
[Pt(η2-C,S-C12H8)(PEt3)(P(OR)3)], the ones which afford
the best yields. In addition, the use of basic alumina
improves even more such yields, again complex 2b being
the best of the series (94%). However, comparable yields
can be attained with 3 (90%) and 4 (88%).
F igu r e 2. Molecular structure of complex 3 with thermal
ellipsoids at the 30% probability level.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 3
Pt(1)-C(13)
Pt(1)-P(2)
S(5)-C(12)
C(10)-C(13)
2.061(4)
2.2794(12)
1.765(6)
1.413(6)
Pt(1)-P(1)
Pt(1)-S(5)
C(6)-C(13)
2.2771(12)
2.3534(11)
1.391(6)
C(13)-Pt(1)-P(1)
P(1)-Pt(1)-P(2)
P(1)-Pt(1)-S(5)
C(12)-S(5)-Pt(1)
90.42(12) C(13)-Pt(1)-P(2) 169.51(12)
97.76(4)
C(13)-Pt(1)-S(5)
P(2)-Pt(1)-S(5)
84.46(12)
88.61(4)
168.52(5)
97.67(14) C(6)-C(13)-Pt(1) 119.5(4)
C(10)-C(13)-Pt(1) 124.1(3)
cussed above, but with a gentle warming to 80 °C,
complex 1 reacted with P(OiPr)3 in toluene to yield only
one product with the formulation [Pt(η2-C,S-C12H8)-
(PEt3)(P(OiPr)3)], 3 (Scheme 1), where the phosphite
ligand is in trans position to carbon and the phosphine
is trans to sulfur of the thiaplatinacycle moiety. No other
compound was detected by 31P NMR in the crude
reaction mixture. Simple evaporation and hexane wash-
ing yielded an analytically pure sample. 31P NMR
showed the expected pattern for two nonequivalent cis
phosphorus with resonances at δ 14.8 (1J (Pt-P) ) 3118
2
Hz, J (P-P) ) 29 Hz) for the phosphine trans to S and
2
δ 120.5 (1J (Pt-P) ) 3062 Hz, J (P-P) ) 29 Hz) for the
phosphite trans to C, which is all similar to the pattern
exhibited by complex 2a . An X-ray structure determi-
nation confirmed such a proposal. Further warming of
the reaction mixture up to 24 h produced no other
isomeric form that could be detected by NMR spectros-
copy.
X-r a y Str u ctu r e of Th ia p la tin a cycle 3. The thia-
platinacycle derived from dibenzothiophene-containing
triethylphosphine and triisopropyl phosphite is depicted
in Figure 2; selected bond lengths and angles are given
in Table 2. The thiaplatinacycle moiety in complex 3 is
severely twisted in a very similar way to the previously
reported structure for 15 and quite similar to complex
2b. Even when among the three thiaplatinacycles,
complex 3 presents the least distorted P(1)-Pt-P(2)
angle, 97.76(4)°, which is significantly larger than 90°
due to the phosphite-phosphine repulsion. Key bond
lengths for complex 3 are the following: Pt-S(5) )
2.3534(11) Å, Pt-C(13) ) 2.061(4) Å, Pt-P(1), which is
The higher HDS yields exhibited by thiaplatinacycles
with phosphites can be associated with the higher
stability of the Pt-P bond compared with that of the
thiaplatinacylces with two alkyl monophosphines.

Thiaplatinacycles Derived from Phosphites
Organometallics, Vol. 22, No. 23, 2003 4737
for 2a , C24H38O3P2PtS: C, 43.43; H, 5.73; S, 4.82. Found: C,
42.98; H, 5.68; S, 5.07. FAB+: m/z 664. Mp: 109-114 °C. NMR
Indeed, the use of diphosphines such as dppe (1,2-bis-
(diphenylphosphino)ethane) affords a better yield than
that with alkylic monophosphines, but a bit lower when
compared with phosphite-containing thiaplatinacycles.
For compounds 2b to 4 the observed trends seem to be
related to the corresponding cone angle for phosphites,
the best yield being observed for the complex containing
the phosphite with the smaller cone angle. Perhaps
associated with such small cone angle for P(OEt)3 all
the expected compounds derived from the phosphine
substitution were observed and isolated. In contrast, for
P(OiPr)3 and P(OPh)3 only one particular isomer could
be observed and isolated.
1
spectra were as follows. H: δ 0.85 (m, 9H, CH3-, Et-P); 1.2
(m, 9H, CH3-, EtO-P); 1.7 (m, 6H, -CH2-, Et-P); 4.15 (m,
6H, -CH2-, EtO-P); 6.85-7.1 (m, 4H); 7.4-7.6 (m, 4H). 31P-
{1H}: δ 15.4 (d, (1J (Pt-P) ) 3084 Hz, 2J (P-P) ) 28 Hz); 123.3
2
(1J (Pt-P) ) 3065 Hz, J (P-P) ) 28 Hz). 13C{1H}: δ 8.11 (d,
2
3
CH3, J (P-C) 15 Hz, Et-P); 16.5 (d, CH3, J (P-C) 2 Hz, EtO-
P); 16.7 (d, -CH2-, 1J (P-C) 33 Hz, Et-P); 61.4 (m, br, -CH2-,
EtO-P); 123.3 (s, CH); 124.2 (s, CH); 126.0 (s, CH); 126.2 (s,
CH); 126.3 (s, CH); 126.8 (d, CH, 4J (P-C) 8 Hz); 130.4 (s, CH);
135.9 (d, CH, 3J (P-C) 10 Hz); 136.8 (m, br, C); 143.1 (s, C);
148.9 (s, C), 164.0 (w, br, C).
Yield for 2b: 20%. Anal. Calcd for 2b, C24H38O3P2PtS: C,
43.43; H, 5.73; S, 4.82. Found: C, 42.99; H, 5.70; S, 5.00.
FAB+: m/z 664. Mp: 101-102 °C. NMR spectra were as
Con clu sion s
1
follows. H: δ 0.9-1.2 (m, 18H, CH3-, Et-P and EtO-P); 2.0
(m, 6H, -CH2-, Et-P); 3.8 (m, 6H, -CH2-, EtO-P); 6.85-7.1
(m, 4H); 7.4-7.6 (m, 4H). 31P{1H}: δ 10.6 (d, (1J (Pt-P) ) 1691
Hz, 2J (P-P) ) 28 Hz); 104.7 (1J (Pt-P) ) 5405 Hz, 2J (P-P) )
28 Hz). 13C{1H}: δ 8.28 (d, CH3, 2J (P-C) 14 Hz, Et-P); 14.8
(d, -CH2-, 1J (P-C) 29 Hz, Et-P); 15.7 (d, CH3-, 3J (P-C) 7
Hz, EtO-P); 61.4 (m, br, -CH2-, EtO-P); 123.2 (s, CH); 124.3
(s, CH); 125.9 (s, CH); 126.2 (s, CH); 126.4 (s, CH); 126.9 (s,
The phosphine substitution by a phosphite in [Pt(η2-
C,S-C12H8)(PEt3)2] is a feasible process to produce
complexes of the type [Pt(η2-C,S-C12H8)(PEt3)(P(OR)3)]
in good yields and purity, avoiding the reductive elimi-
nation of DBT. Even when the conditions for achieving
a complete HDS cycle for DBT have not yet been
established, these results do indicate the importance in
the reaction of the thiaplatinacycle as intermediates or
precursors. We have also demonstrated that the pres-
ence of at least one σ-donor/ π-acceptor ligand, with a
small cone angle, such as triethyl phosphite, is a key
factor for improvement of HDS and the promoter effect
of both acid and basic alumina.
3
2
CH); 130.7 (s, CH); 136.9 (d, CH, J (P-C) 9 Hz, J (Pt-C) 45
2
Hz); 138.9 (pt, C, J (Pt-C) 25 Hz); 143.1 (s, C); 148.6 (pt, C,
2
2J (Pt-C) 75 Hz), 154.4 (d, C, J (P-C) 90 Hz). For complex 5,
yield was 10% approximately determined in solution by 31P-
{1H} NMR, with signals at δ 107.0 (1J (Pt-P) ) 2938 Hz, 2J (P-
P) ) 44 Hz); 123.3 (1J (Pt-P) ) 5160 Hz, 2J (P-P) ) 44 Hz).
P r ep a r a tion of [P t(η2-C,S-C12H8)(P Et3)(P (OiP r )3)], 3. 3
was prespared by a procedure similar to that described above,
using 0.25 g (0.40 mmol) of 1 dissolved in toluene (10 mL),
adding tri-isopropyl phosphite (0.2 mL, 0.8 mmol) under argon.
The reaction mixture was heated to 80 °C for 3 h with stirring.
After this the reaction was evaporated to dryness to yield a
viscous residue, which was further dried for 2 h. Freshly
distilled dried hexane was added (3 × 3 mL) and filtered to
yield a yellow residue, which was dried for 2 h. Yield for 3:
95%. Anal. Calcd for 3, C27H44O3P2PtS: C, 45.95; H, 6.24; S,
4.54. Found: C, 45.57; H, 6.43; S, 4.61. FAB+: m/z 706. Mp:
165-167 °C with decomposition. NMR spectra were as follows.
1H: δ 0.85-1.0 (m, 9H, CH3-, Et-P); 1.2-1.4 (m, 18H, CH3-,
iPrO-P); 1.75 (m, 6H, -CH2-, Et-P); 5.0 (m, 3H, -CH-, iPrO-
P); 6.85-7.1 (m, 4H); 7.4-7.6 (m, 4H). 31P{1H}: δ 14.8 (d,
(1J (Pt-P) ) 3118 Hz, 2J (P-P) ) 29 Hz); 120.5 (1J (Pt-P) )
Exp er im en ta l Section
All reactions were carried out using standard Schlenk
techniques under argon. Solvents were dried and distilled
before use. Deuterated solvents (Aldrich) for NMR experiments
were dried over molecular sieves. All other chemicals, filter
aids, and chromatographic materials were reagent grade and
used as received. 1H, 13C{1H}, and 31P{1H} NMR spectra were
determined on a Varian Unity (300 MHz) or a Bruker (500
MHz) spectrometer in CDCl3, unless otherwise stated; chemi-
cal shifts (δ) are relative to the deuterated solvent, and 31P
NMR spectra are relative to external H3PO4. Infrared spectra
were obtained in a Perkin-Elmer 1600 FT spectrophotometer.
Mass determinations (FAB+) were performed on a J EOL SX-
102 A, using a nitrobenzilic alcohol matrix, and GC-MS
determinations were performed on a Varian Saturn 3. Gal-
braith Laboratories carried out elemental analyses. Melting
points were determined in a Electrothermal digital melting
point apparatus. The synthesis of [Pt(η2-C,S-C12H8)(PEt3)2] was
carried out using the previously reported procedure.4 All
phosphites were purchased from Strem and dried over molec-
ular sieves.
P r ep a r a t ion of [P t (η2-C,S-C12H8)(P E t3)(P (OE t )3)], 2a ,
2b, a n d [P t(η2-C,S-C12H8)(P (OEt)3)2], 5. All three compounds
were formed in the same reaction from [Pt(η2-C,S-C12H8)-
(PEt3)2] (0.5 g, 0.81 mmol), 1, dissolved in toluene (10 mL),
adding triethyl phosphite (0.55 mL, 3.25 mmol) under argon.
The reaction mixture was allowed to react at room tempera-
ture for 6 h with stirring. After this time the mixture was
evaporated to dryness with increasing vacuum (0.01 mmHg)
and further dried for 4 h. The residue was redisolved in the
minimum amount of acetone, complex 2a being precipitated
from the reaction mixture with ice cooling and addition of
hexane. The remaining mixture was purified by column
chromatography on silica gel with hexane/acetone as eluent
(from 9:1 to 1:1); the fourth colorless fraction was evaporated
to dryness to yield complex 2b. Complex 5 was detected only
in the original reaction mixture. Yield for 2a : 70%. Anal. Calcd
2
2
3062 Hz, J (P-P) ) 29 Hz). 13C{1H}: δ 8.1 (d, CH3, J (P-C)
1
24 Hz, Et-P); 16.6 (d, -CH2-, J (P-C) 33 Hz, Et-P); 24.3 (s,
CH3, iPrO-P); 69.9 (s, br, -CH-, iPrO-P); 123.2 (s, CH); 124.1
(s, CH); 125.8 (s, CH); 126.05 (s, CH); 126.1 (s, CH); 126.7 (d,
4
3
CH, J (P-C) 9 Hz); 130.3 (s, CH); 136.2 (d, CH, J (P-C) 6.5
Hz); 139.0 (m, br, C); 143.1 (s, C); 148.8 (s, C), 164.5 (w, br,
C).
P r ep a r a tion of [P t(η2-C,S-C12H8)(P Et3)(P (OP h )3)], 4. 4
was prepared following a procedure similar to that described
above, using 0.25 g (0.40 mmol) of 1 dissolved in toluene (10
mL), adding triphenyl phosphite (0.3 mL, 1.15 mmol) under
argon. The reaction mixture was heated to 80 °C for 3 h with
stirring. After this the reaction was evaporated to dryness to
yield a white viscous residue, which was further dried for 3 h.
Freshly distilled dried hexane was added (3 × 3 mL) and
filtered to yield an ivory residue, which was dried for 3 h. Yield
for 4: 92%. Anal. Calcd for 4, C36H38O3P2PtS: C, 53.53; H,
4.70; S, 3.96. Found: C, 53.44; H, 4.63; S, 3.97. FAB+: m/z
808. Mp: 150-152 °C. NMR spectra were as follows. 1H: δ
0.9-1.1 (m, 9H, CH3-, Et-P); 2.0 (m, br, 6H, -CH2-, Et-P);
6.85-7.3 (m, 19H); 7.5-7.65 (m, 4H). 31P{1H}: δ 10.15 (d,
(1J (Pt-P) ) 1645 Hz, 2J (P-P) ) 27 Hz); 94.3 (1J (Pt-P) ) 5623
Hz, 2J (P-P) ) 27 Hz). 13C{1H}: δ 8.3 (d, CH3, 2J (P-C) 12 Hz,
Et-P); 15.1 (d, -CH2-, 1J (P-C) 29 Hz, Et-P); 120.2 (s, CH,
PhO-P); 123.1 (s, CH); 124.4 (s, CH); 124.8 (s, CH, PhO-P);

4738 Organometallics, Vol. 22, No. 23, 2003
Picazo et al.
Ta ble 4. Su m m a r y of Cr ysta llogr a p h ic Resu lts for
2b a n d 3
Hyd r od esu lfu r iza tion Exp er im en ts. These experiments
were carried out in a stainless steel 300 mL Parr reactor. A
typical experiment was performed as follows: under argon the
reactor was charged with 0.10 g of the corresponding thia-
platinacycle, 30 mL of freshly distilled toluene, and 1.0 g of
alumina. The reactor was purged three times with hydrogen
and finally charged up to 294 psi at room temperature. The
reaction was heated to the desired temperature (100 °C) for
24 h. The final reaction mixtures were analyzed by GC-MS
on a 60 m DB-5 capillary column. The used acid alumina was
acid washed alumina or acidic alumina, pH of aqueous
suspension 4.5 ( 0.5; the used basic alumina was with a pH
of aqueous suspension of 9.5 ( 0.5.
Cr ysta llogr a p h ic Stu d ies. Single crystals suitable for
X-ray studies were obtained for compounds 2b and 3 by slow
evaporation of toluene solutions at room temperature and were
handled in a noncontrolled atmosphere. A summary of relevant
crystallographic results is listed in Table 4. Diffraction data
were collected at 298 K on a Siemens P4/PC diffractometer,
using graphite-monochromated Mo KR radiation (λ ) 0.71073
Å), following a standard procedure.12 The structure of 2b was
solved13 by Patterson methods and that for 3 by direct
methods, both completed with difference Fourier maps. Re-
finement was carried out by full-matrix least-squares analysis
with anisotropic thermal parameters for all non-hydrogen
atoms. H atoms were placed on ideal positions and refined
using a riding model with a fixed isotropic thermal parameter.
2b
3
formula
C
24H38O3P2Pt1S1
C
27H44O3P2PtS
fw
663.63
705.71
cryst size/mm
color, shape
0.6 × 0.4 × 0.4
pale yellow,
irregular block
1.598
0.60 × 0.45 × 0.25
pale yellow, prism
d(calc)/g cm-3
space group
a/ Å
b/ Å
c/ Å
1.526
P21/n
P21/c
9.104(2)
21.473(3)
14.635(2)
105.42(1)
2758.2(7)
4
5.30
3-56
8206
12.700(1)
16.715(2)
14.703(1)
100.14(1)
3072.4(5)
4
4.763
3-55
8465
â/deg
V/ Å3
Z
µ/mm-1
2θ range/deg
no. of reflns collected
no. of unique reflns
(Rint)/%a
6597 (3.91%)
6995 (3.18%)
no. of reflns with
Fo > 4σ(Fo)
no. of data/params
GOF on F2
R indices (I > 2σ(I))/%
R indices (all data)/%
4972
5413
6597/290
1.076
3.68, 7.97
6.16, 10.54
6995/308
1.030
3.30, 7.34
5.26, 8.01
0.823
max. resid density/e Å-3 1.10
system used
SHELXTL 5.03
SHELXTL 5.03 and
SHELX97
a
Rint
)
Ack n ow led gm en t. We thank DGAPA-UNAM for
grant IN-208101.
2
2
|Fo - Fo
|
||Fo| - |Fc||
∑
∑
, R1 )
, wR2 )
2
Fo
|Fo|
Su p p or tin g In for m a tion Ava ila ble: Experimental de-
tails and tables of complete crystallographic data for 2b and
3. This material is available free of charge via the Internet at
http://pubs.acs.org.
∑
∑
2
2
2
2
2 2
w(Fo - Fc
)
w(Fo - Fc
m - n
)
∑
∑
, S )
2
2
x
w(Fo
)
x
∑
OM034126R
125.8 (s, CH); 126.1 (s, CH); 127.0 (d, CH, 4J (P-C) 6 Hz); 127.5
(s, CH); 129.5 (s, CH, PhO-P); 130.2 (s, CH); 137.1 (d, CH,
3J (P-C) 10 Hz); 137.8 (s, C, PhO-P); 143.1 (s, br, C); 148.2 (s,
(12) Fait, J . XSCAnS, release 2.10b; Siemens Analytical X-ray
Instruments: Madison, WI, 1991.
(13) Sheldrick, G. M. SHELXTL-plus, release 5.03; Siemens Ana-
lytical X-ray Instruments Inc.: Madison, WI, 1995. Sheldrick, G. M.
SHELX97-2 Users Manual; University of Go¨ttingen: Germany, 1997.
3
2
C); 150.7 (d, C, J (P-C) 11 Hz), 153.1 (d, C, J (P-C) 70 Hz).