Oxidative addition of alkyl halides to chiral cyclometallated platinum(II) complexes with thienyl imines. X-ray crystal structure of [PtMe{3-((S)-PhCHMeNCH)C4H2S}SMe2]

Article abstract of DOI:10.1016/S0022-328X(00)00231-X

The reaction of [Pt₂Me₄(μ-SMe₂)₂] with ligand 3-((S)-PhCHMeNCH)C₄H₃S (1) produced the chiral cyclometallated compound [PtMe{3-((S)-PhCHMeNCH)C₄H₂S}SMe₂] (2) which was characterized structurally. The reactions of 2 with phosphines gave compounds [PtMe{3-((S)-PhCHMeNCH)C₄H₂S}L] (L = PPh₃ (3), P(2-MeC₆H₄)₃ (4), Ph₂PCH₂CH₂PPh₂ (5)). The oxidative addition of methyl iodide to compounds 2 and 3 gave two diastereoisomers each of compounds [PtMe₂I{3-((S)-PhCH-MeNCH)C₄H₂S)L] (L = SMe₂ (6a/6a′), PPh₃ (7a/7a′)) in a ratio 2.1:1 and 2.4:1, respectively. Subsequent isomerization gave, in each case, a new pair of diastereoisomers. Compounds 4 and 5 failed to react with methyl iodide, while platinum(II) compounds [PtX{3-((S)-PhCHMeNCH)C₄H₂S}PPh₃] (X = I (8), Br (9)) were obtained in the reactions of 3 with ethyl iodide or benzylbromide.

Full text of DOI:10.1016/S0022-328X(00)00231-X

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 604 (2000) 178–185
Oxidative addition of alkyl halides to chiral cyclometallated
platinum(II) complexes with thienyl imines. X-ray crystal structure
of [PtMe{3-((S)-PhCHMeNCH)C4H2S}SMe2]
Craig Anderson a,b, Margarita Crespo c,*, Merce` Font-Bard´ıa d, Xavier Solans d
a Orgometa Laboratories, 6254 St. Denis, Montreal, Canada H2S 2R7
b Research and De6elopment Di6ision, CRG Laboratory, PO Box 301, Succ. R, Montreal, Canada H2S 3K9
c Departament de Qu´ımica Inorga`nica, Facultat de Qu´ımica, Uni6ersitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain
d Departament de Cristal.lografia, Mineralogia i Dipo`sits Minerals, Uni6ersitat de Barcelona, Mart´ı i Franque`s s/n, E-08028 Barcelona, Spain
Received 28 February 2000; received in revised form 16 April 2000
Abstract
The reaction of [Pt2Me4(m-SMe2)2] with ligand 3-((S)-PhCHMeNCH)C4H3S (1) produced the chiral cyclometallated compound
[PtMe{3-((S)-PhCHMeNCH)C4H2S}SMe2] (2) which was characterized structurally. The reactions of 2 with phosphines gave
compounds [PtMe{3-((S)-PhCHMeNCH)C4H2S}L] (L=PPh3 (3), P(2-MeC6H4)3 (4), Ph2PCH2CH2PPh2 (5)). The oxidative
addition of methyl iodide to compounds 2 and 3 gave two diastereoisomers each of compounds [PtMe2I{3-((S)-PhCH-
MeNCH)C4H2S}L] (L=SMe2 (6a/6a%), PPh3 (7a/7a%)) in a ratio 2.1:1 and 2.4:1, respectively. Subsequent isomerization gave, in
each case, a new pair of diastereoisomers. Compounds 4 and 5 failed to react with methyl iodide, while platinum(II) compounds
[PtX{3-((S)-PhCHMeNCH)C4H2S}PPh3] (X=I (8), Br (9)) were obtained in the reactions of 3 with ethyl iodide or benzylbro-
mide. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Platinum; Thienylimines; Cyclometallation; Chirality; Crystal structure; Oxidative addition
1. Introduction
complexes are inherently achiral but due to increasing
interest in chiral inorganic compounds related to enan-
tiomeric catalysis, bioinorganic chemistry and
supramolecular chemistry, the introduction of chirality
in such compounds has been analyzed. This can be
achieved when chiral ligands are involved, or when
steric hindrance produced an helical distortion, as
shown for cis-bis-cyclometallated compounds [4,5].
Studies of oxidative addition reactions to both types of
chiral cyclometallated platinum(II) compounds have
been reported recently [6–8].
We have studied previously the oxidative addition
reactions of methyl iodide to compounds [PtMe{3-
(PhCH2NCH)C4H2S}L] (L=SMe2 or PPh3), and the
observed differences in the stereochemistry of the final
products were explained by the different bulk of the
ligand L [9]. In this paper we report the results obtained
for the analogous chiral complexes [PtMe{3-((S)-
PhCHMeNCH)C4H2S}L].
Oxidative addition reactions of organoplatinum com-
plexes with nitrogen-donor ligands have been reviewed
recently [1]. The reactions with organohalides usually
give the products of trans oxidative addition. Some-
times, the cis isomer is formed by a competitive cis
oxidative addition pathway, or it may be formed by
trans oxidative addition with subsequent isomerization
of the platinum(IV) product to the more stable cis
isomer. In particular, cyclometallated platinum(II)
compounds are good candidates in oxidative addition
reactions of alkylhalides due to the presence of PtꢀN
and PtꢀC s bonds which increase the electron density
at the metal center [2,3]. Square planar platinum(II)
* Corresponding author. Tel.: +34-93-4021273; fax: +34-93-
4907725..
E-mail address: mcrespo@kripto.qui.ub.es (M. Crespo).
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00231-X

C. Anderson et al. / Journal of Organometallic Chemistry 604 (2000) 178–185
179
2. Results and discussion
to the methyl substituent of the benzyl group. The
value of the coupling of the imine hydrogen to plat-
inum (2J(PtꢀH)=51 Hz) indicates the formation of a
metallacycle [10,11], while the observed J(HꢀH) value
for the mutual coupling of the thienyl hydrogens im-
plies that the activation of the CꢀH bond took place at
the a-position [12].
Suitable crystals of compound [PtMe{3-((S)-PhCH-
MeNCH)C4H2S}SMe2] (2) were grown in acetone solu-
tion. The crystal structure is composed of discrete
molecules separated by van der Waals interactions. The
structure is shown in Fig. 1, and confirms the geometry
expected. In particular, the methyl group is trans to the
nitrogen atom, the CꢁN group is endo to the cycle and
the stereochemistry of the asymmetric carbon is S. The
imine adopts an (E)-configuration, the torsion angle
C(6)ꢀNꢀC(5)ꢀC(2) being −176.4°. The platinum atom
displays a tetrahedral distorted planar coordination and
2.1. Syntheses and crystal structure of compound 2
Ligand 3-((S)-PhCHMeNCH)C4H3S (1) was pre-
pared from the condensation reaction of 3-thiophene-
carboxaldehyde and (S)-methylbenzylamine in ethanol.
The reaction of this ligand with [Pt2Me4(m-SMe2)2] pro-
duced cyclometallated compound [PtMe{3-((S)-PhCH-
MeNCH)C4H2S}SMe2] (2) as a single isomer arising
from intramolecular activation of a CꢀH bond of the
thiophene ring, followed by methane elimination in a
similar process to that reported for analogous systems
[10,11].
Compound 2 was characterized by elemental analyses
1
and H-NMR spectroscopy. Three distinct resonances
appeared in the methyl region corresponding to the
methyl group bound to platinum (2J(PtꢀH)=79 Hz),
to the dimethylsulfide ligand (2J(PtꢀH)=32 Hz), and
,
the following displacements (A) are observed from the
least-squares plane of the coordination sphere: Pt,
0.023; S(2), −0.055; N, 0.056; C(1), −0.075; C(16),
0.051. The metallacycle is approximately planar — the
largest deviation from the mean plane determined by
,
the five atoms is 0.018 A for C(2) — and nearly
coplanar with the coordination plane, the dihedral an-
gle being 3.20°. Molecular dimensions are listed in
Table 1. The angles between adjacent atoms in the
coordination sphere of platinum lie in the range 77.4–
95.4°, the smallest angle corresponding to the metalla-
cycle. Bond lengths in the coordination sphere of the
platinum and in the thiophene ring are in the usual
range for analogous compounds [7,13–15]. The metal-
lacycle is smaller than for compound [PtMe{3-
(PhCH2NCH)C4H2S}PPh3] [9] (perimeter 8.153 vs.
,
8.309 A) which is consistent with the smaller size of
SMe2 versus PPh3 ligand. Moreover, in the latter struc-
ture as well as in compound [PtMe{(S)-PhCHMe-
NCHC6H3F-2}PPh3], the benzyl group lies away from
the coordination plane in order to minimize the steric
crowding in the coordination sphere of the platinum,
whereas for 2, the benzyl group lies towards the small
SMe2 ligand.
Fig. 1. Molecular structure of compound [PtMe{3-((S)-PhCH-
MeNCH)C4H2S}SMe2] (2).
Table 1
,
Selected bond lengths (A) and angles (°) in compound (2)
Bond lengths
PtꢀC
PtꢀN
S(2)ꢀC(15)
NꢀC
C(1)ꢀC(2)
C(6)ꢀC(7)
1.975(9)
2.143(7)
1.739(11) S(2)ꢀC(14)
1.295(11) NꢀC(6)
1.322(13) C(2)ꢀC(5)
1.519(12) C(6)ꢀC(13)
PtꢀC(16)
PtꢀS(2)
1.997(9)
2.336(3)
1.801(10)
1.462(10)
1.418(11)
1.519(12)
2.2. Reactions with phosphines
As shown in Scheme 1, the reaction of 2 with
monodentate phosphines produced compounds [PtMe-
{3-((S)-PhCHMeNCH)C4H2S}L] (L=PPh3 (3), P(2-
MeC6H4)3 (4)) which were characterized by elemental
analysis and 1H- and 31P-NMR spectroscopies. The
phosphine replaced the SMe2 ligand, and even with an
excess of phosphine, the metallacycle is not cleaved.
A single isomer is detected for compound 3 while
compound 4 consists of two isomers (ratio 3:1), due to
the hindered rotation of the ortho-tolyl groups. In all
cases, the methylplatinum resonance appears as a dou-
Bond angles
C(1)ꢀPtꢀC(16)
C(16)ꢀPtꢀN
C(16)ꢀPtꢀS(2)
C(15)ꢀS(2)ꢀC(14)
C(14)ꢀS(2)ꢀPt
C(5)ꢀNꢀPt
C(2)ꢀC(1)ꢀPt
NꢀC(5)Cꢀ(2)
NꢀC(6)ꢀC(13)
92.9(4)
170.1(3)
94.4(3)
C(1)ꢀPtꢀN
C(1)ꢀPtꢀS(2)
NꢀPtꢀS(2)
C(15)ꢀS(2)ꢀPt
C(5)ꢀNꢀC(6)
C(6)ꢀNꢀPt
C(1)ꢀC(2)ꢀC(5)
NꢀC(6)ꢀC(7)
C(7)ꢀC(6)ꢀC(13)
77.4(4)
171.3(3)
95.4(2)
109.9(4)
121.9(8)
125.8(6)
115.6(9)
111.1(7)
108.9(8)
99.8(5)
106.9(3)
112.2(6)
117.7(7)
117.0(8)
114.1(7)

180
C. Anderson et al. / Journal of Organometallic Chemistry 604 (2000) 178–185
Scheme 1. (i) Reaction with [Pt2Me4(m-SMe2)2] in acetone; (ii) reaction with the corresponding phosphine in acetone.
blet due to coupling with the phosphorus atom and is
also coupled to platinum. The imine hydrogen is cou-
pled to platinum but not to phosphorus, which indi-
cates a cis arrangement of the imine and the phosphine.
For each isomer of compound 4, three distinct reso-
nances appear for the methyl groups of the ortho-
tolylphosphine.
Due to the chelating nature of the diphosphine, a
different result was obtained when the reaction of 2
with 1,2-bis(diphenylphosphino)ethane (dppe) was car-
ried out under the same experimental conditions. In this
case, both the SMe2 ligand and the nitrogen of the
imine ligand are displaced from the coordination sphere
of the platinum. Consequently, the metallacycle is
cleaved and the imine acts as a [C−] monodentate
stereochemistry, although products arising from cis ox-
idative addition can be formed in a subsequent isomer-
ization process [3,8]. There is an increasing interest for
the potential stereoselectivity of oxidative addition of
alkyl halides to chiral cyclometallated platinum(II)
compounds. Compounds containing the cyclometal-
lated chiral imine 3-((S)-PhCHMeNCH)C4H2S are ade-
quate substrates for such a study since the platinum
center is expected to have a high electronic density.
Moreover, the results obtained when either a SMe2 or a
phosphine ligand complete the coordination sphere of
the platinum could be compared.
Assuming a trans addition, two diastereoisomers (C,
S) and (A, S), in which C/A represents the absolute
stereochemistry (clockwise and anticlockwise) at the
platinum and S describes the chirality at carbon are
possible. We have reported previously that the oxida-
tive addition of methyl iodide to [PtMe2{(S)-
PhCHMeNCHC5H4N}], containing a [N, N%] chelate
ligand [17], and to the cyclometallated compound
[PtMe{(S)-PhCHMeNCHC6H3F-2}PPh3] gave [7], in
each case, two diastereoisomers in nearly equal
amounts (1:1 and 1.25:1, respectively).
It has been reported previously for compounds
[PtMe{3-(PhCH2NCH)C4H2S}L] (L=SMe2, PPh3),
that the oxidative addition takes place with trans stere-
ochemistry, and is followed by isomerization of the
resulting platinum(IV) compound. The isomerization,
shown in reaction (1), should proceed through a disso-
ciative pathway to yield a five-coordinate intermediate,
which rearranges in order to minimize steric effects in
the final platinum(IV) compound. For the bulky PPh3
ligand, isomerization is completed within a few hours,
while for SMe2, an equilibrium mixture of both isomers
is attained. Such an isomerization should lead in this
case to a new pair of diastereoisomers.
ligand.
Compound
[PtMe{3-((S)PhCHMeNCH)-
C4H2S}(Ph2PCH2CH2PPh2)] (5) was characterized by
elemental analysis and 1H- and 31P-NMR. Spectral data
are consistent with those for analogous compounds
with chelating dppe [16]. The methylplatinum resonance
is coupled with both phosphorus atoms and shows
platinum satellites. The coupling of the imine hydrogen
to platinum is considerably reduced (J(PtꢀH)=8 Hz).
In the 31P-NMR spectrum, two resonances due to the
non-equivalent phosphorus atoms appear and J(PꢀPt)
values (1660 and 2233 Hz) are consistent with the
presence of carbon atoms trans to the phosphorus. The
bigger value is assigned to the phosphorus trans to
thiophene, due to the low trans influence of this group
[9].
2.3. Oxidati6e addition reactions
It is generally accepted that the oxidative addition of
alkyl halides to platinum(II) compounds give trans

C. Anderson et al. / Journal of Organometallic Chemistry 604 (2000) 178–185
181
6a/6a%). When a 1H-NMR was registered just after
adding methyl iodide to a solution of 2 in deuterated
acetone, the isomers 6a/6a% and 6b/6b% were detected in
the same relative amounts as in the preparative synthe-
sis and their ratio remained constant in solution. The
mixture of isomers is composed as follows: 6a (19.4%),
6a% (9.3%), 6b (38.9%), and 6b% (32.4%). Thus, the main
products are the pair of diastereoisomers 6b/6b% arising
from isomerization of the initially formed 6a/6a%. The
ratio 6a:6a%=2.1:1 indicates a significant degree of
enantioselectivity in the initial trans oxidative addition,
although subsequent isomerization yields nearly equal
amounts of both diastereoisomers (6b:6b%=1.2:1).
When the mixture of isomers 6b/6b% was treated with
PPh3 in acetone, the substitution reaction of SMe2 for
PPh3 yielded isomers 7b/7b% in which the triphenylphos-
phine is trans to a methyl group, in the ratio 1.2:1, as
confirmed by 31P-NMR spectroscopy.
As shown in Scheme 2, the reaction of [PtMe{3-((S)-
PhCHMeNCH)C4H2S}SMe2] (2) with methyl iodide in
acetone at room temperature gave a mixture of two
pairs of diastereoisomers (6a/6a% and 6b/6b%) of the
cyclometallated platinum(IV) compound [PtMe2I{3-
((S)-PhCHMeNCH)C4H2S}SMe2] (6). From the
2J(HꢀPt) values for the methyl groups, a fac-PtC3
structure is assigned to all isomers. Isomers 6a/6a% differ
from isomers 6b/6b% in having a methyl group trans to
I or trans to SMe2, respectively. In agreement with
previous studies, the resonances at lower l were as-
signed to axial methyl groups trans to iodide (isomers
The reaction of racemic [PtMe{3-(PhCHMeNCH)-
C4H2S}SMe2] (2%) with methyl iodide was also moni-
1
tored by H-NMR. Again, four sets of resonances in
the same ratio as for chiral compound 2 are observed
and assigned to the two pairs of diastereoisomers, each
with its enantiomer.
The reaction of [PtMe{3-((S)-PhCHMeNCH)-
C4H2S}PPh3] (3) with methyl iodide in acetone at room
1
temperature was monitored by H- and 31P-NMR. In
the early stages of the reaction, resonances assigned to
a pair of diastereoisomers (7a/7a%) of the platinum(IV)
compound
[PtMe2I{3-((S)-PhCHMeNCH)C4H2S}-
PPh3] appeared in a ratio 2.4:1 in the 31P-NMR, to-
gether with signals due to unreacted platinum(II) com-
pound 3. In the corresponding 1H-NMR, only the
resonances due to the major of these isomers could be
assigned unambiguously. As the reaction proceeded,
resonances due to a second set of platinum(IV)
diastereoisomers (7b/7b%) appeared and fully replaced
the former resonances within 4 h. The isomer 7a (or
7a%) displays two methylplatinum resonances which ap-
pear as doublets due to coupling to the phosphorus
2
atom and with similar J(HPt) values (67 and 68 Hz,
respectively). As for analogous cyclometallated com-
pounds reported previously, the resonance at higher
fields is assigned to the axial methyl. A similar pattern
is observed for isomers 7b/7b%, except for the fact that a
reduced coupling to platinum (2J(HPt)=60 Hz) is now
observed for the axial methyl, which suggests a trans
arrangement of the axial methyl and the PPh3. 31P-
NMR supported the successive formation of two differ-
ent isomers, since the initial resonances assigned to
7a/7a% decreased its intensity, while two new resonances
due to the pair of diastereoisomers 7b/7b% grew. The
intensities of the signals in both 1H- and 31P-NMR
indicate that the ratio 7b:7b% is 2.2:1.
The reaction of racemic [PtMe{3-(PhCHMe-
Scheme 2.
NCH)C4H2S}PPh3] (3%) with methyl iodide was also

182
C. Anderson et al. / Journal of Organometallic Chemistry 604 (2000) 178–185
ously [7]. The bulk of ligand L does not significantly
affect the ratio of the diastereoisomers formed initially
but it is a decisive factor in the ratio of the diastereoiso-
mers arising from the subsequent isomerization process.
While for the bulky PPh3 derivatives, the proportion of
the diastereoisomers is practically maintained (7b:7b%=
2.2:1), for SMe2 an equilibration of the diastereoiso-
mers occurs (6b:6b%=1.2:1).
The diastereomeric ratios obtained for 6a/6a% and
7a/7a% are similar to those reported for the oxidative
addition of methyl iodide to compound [PtMe{trans-1-
(NꢁCHC6H4)-2-(NꢁCHC6H5)C6H10}] containing a [C,
N, N%] tridentate ligand [8], in spite of the fact that the
compounds reported here have the chiral center in a
dangling benzyl group two atoms away from the plat-
inum center.
Scheme 3.
monitored by H- and 31P-NMR and the results were
identical to those observed for the chiral compound 3.
Compounds [PtMe{3-((S)-PhCH2NCH)C4H2S}P(2-
MeC6H4)3] (4) and [PtMe{3-((S)-PhCH2NCH)C4H2S}-
(Ph2PCH2CH2PPh2)] (5) failed to react with methyl
iodide under the same experimental conditions used for
the reactions of compounds 2 and 3. The lack of
reactivity of compound 4 can be related to the results
reported for analogous iridium compounds [18], for
which the crystal structure revealed that one of the
ortho methyl groups in the phosphine is located above
the coordination plane and isolates the central atom
from attacking molecules. As for 5, the decrease in
electronic density at the platinum when the imine nitro-
gen is replaced by a phosphorus atom may account for
the result obtained.
1
3. Experimental
3.1. Instrumentation
1H- and 31P{1H}-NMR spectra were recorded by
using Varian Gemini 200 (1H, 200 MHz), Varian 500
(1H, 500 MHz) and Bruker 250 (31P, 101.25 MHz)
spectrometers, and referenced to SiMe4 (1H) and H3PO4
(31P). l values are given in ppm and J values in Hz. IR
spectra were recorded as KBr disks on a Nicolet 520
FTIR spectrometer. Microanalyses and mass spectra
(CI and FAB) were performed by the Serveis Cient´ıfico,
Te`cnics de la Universitat de Barcelona.
3.2. Preparation of the compounds
As shown in Scheme 3, the reactions of ethyl iodide
and benzyl bromide with compound [PtMe{3-((S)-
PhCHMeNCH)C4H2S}PPh3] (3) produced platinum(II)
Compound [Pt2Me4(m-SMe2)2] was prepared as re-
ported [21].
compounds
[PtI{3-((S)-PhCHMeNCH)C4H2S}PPh3]
3.2.1. Synthetic procedure for the compounds 1 and 2
3-((S)-PhCHMeNCH)C4H3S (1) was prepared by the
reaction of 0.5 g (4.46 mmol) of 3-tiophenecarboxalde-
hyde with the equimolar amount of (S)-methylbenzy-
lamine (0.54 g) in refluxing ethanol. After 4 h, the
solvent was removed in a rotary evaporator to yield a
white solid. Yield 0.8 g (83%). Racemic 3-(PhCH-
MeNCH)C4H3S (1%) was prepared in an analogous way
using (9)-methylbenzylamine. 1H-NMR (200 MHz,
CDCl3: l=1.58 [d, J(HaꢀHb)=7, Ha]; 4.48 [q,
J(HaꢀHb)=7, Hb]; {7.34 [m]; 7.60 [m, 1H], aromatics};
8.38 [s, Hc].
[PtMe{(3-((S)-PhCHMeNCH)C4H2S}SMe2] (2) was
obtained by adding a solution of 75 mg (3.5×10−4
mol) of the imine 1 in acetone (10 ml) to a solution of
100 mg (1.74×10−4 mol) of compound [Pt2Me4(m-
SMe2)2] in acetone (10 ml). The mixture was stirred for
1 h and the acetone was removed in a rotary evapora-
tor. The residue was washed with hexane and dried in
(8) and [PtBr{3-((S)-PhCHMeNCH)C4H2S}PPh3] (9),
respectively. The formation of a small amount of metal-
lic platinum indicates some degree of decomposition in
this process. Although it is most likely that compounds
8 and 9 arise from oxidative addition of the alkyl halide
followed by reductive elimination, the corresponding
platinum(IV) compounds could not be detected when
the reaction was monitored by 31P-NMR.
1
In the H-NMR of compounds 8 and 9, the coupling
of the imine nitrogen to phosphorus, within the same
range as reported for analogous palladium compounds
[19,20], indicates a trans arrangement of N and P
atoms, which is also supported by the J(PꢀPt) values.
In conclusion, a higher degree of stereoselectivity is
obtained for the oxidative addition of methyl iodide to
thienyl
derivatives
[PtMe{3-((S)-PhCHMeNCH)-
C4H2S}L] (L=SMe2, 6a:6a%=2.1:1; PPh3, 7a:7a%=
2.4:1) than for the phenyl analogues reported previ-

C. Anderson et al. / Journal of Organometallic Chemistry 604 (2000) 178–185
183
vacuum. Yield 120 mg (71%). Racemic [PtMe{(3-
3.2.3. Synthetic procedures for the oxidati6e addition
(PhCHMeNCH)C4H2S}SMe2] (2%) was prepared from
reactions
1
1% in an analogous way. H-NMR (200 MHz, CDCl3):
An excess of methyl iodide (0.1 ml) was added to
solutions of 50 mg of the compounds 2 and 3 in
acetone. The mixtures were stirred for 4 h, and the
solvent was removed under vacuum to yield light yel-
low solids.
2
l=1.09 [s, J(PtꢀH)=79, Mea]; 1.71 [d, J(HcꢀHd)=7,
3
Hc]; 1.93 [s, J(HbꢀPt)=32, Hb]; 5.28 [q, J(HcꢀHd)=6,
Hd]; {7.18 [d, 4J(PtꢀH)=35, J(HꢀH)=5]; 7.30 [m],
3
aromatics}; 8.49 [s, J(PtꢀHe)=51, He]. Anal. Found:
C, 39.2; H, 4.3; N, 2.9. Calc. for C16H21NPtS2: C, 39.50;
H, 4.35; N, 2.88%.
[PtMe2I{(3-((S)-PhCHMeNCH)C4H2S}SMe2] (6a/
6a%/6b/6b%). Yield 50 mg (77%). H-NMR (500 MHz,
1
3.2.2. Synthetic procedure for the phosphine deri6ati6es
[PtMe{(3-((S)-PhCHMeNCH)C4H2S}PPh3] (3) was
obtained by the reaction of 50 mg (1.03×10−4 mol) of
compound 2 with 25 mg (0.95×10−4 mol) of PPh3 in
acetone. After continuous stirring for 2 h, the solvent
was removed in a rotary evaporator and the resulting
yellow solid was filtered, washed with hexane, and
diethylether and dried in vacuum. Yield 55 mg (78%).
Racemic [PtMe{(3-(PhCHMeNCH)C4H2S}PPh3] (3%)
acetone-d6): (6a/6a%), major isomer: l=0.59 [s,
2
2J(PtꢀH)=68, Meb]; 1.41 [s, J(PtꢀH)=68, Mea]; 1.73
[d, J(HꢀH)=7, Hd]; 5.71 [qd, J(HꢀH)=7, J(HꢀH)=
1.5, He]; 8.67 [d, 3J(PtꢀH)=45, J(HꢀH)=1.5, Hf];
2
minor isomer: l=0.81 [s, J(PtꢀH)=68, Meb]; 1.54 [s,
2J(PtꢀH)=68, Mea]; 1.83 [d, J(HꢀH)=7, Hd]; 5.61 [q,
3
J(HꢀH)=7, He]; 8.10 [d, J(PtꢀH)=45, J(HꢀH)=1,
2
Hf]. (6b/6b%), major isomer: l=1.35 [s, J(PtꢀH)=70,
Meb]; 1.63 [s, 2J(PtꢀH)=68, Mea]; 1.74 [d, J(HꢀH)=7,
1
was prepared from 2% in an analogous way. H-NMR
3
Hd]; 6.14 [q, J(HꢀH)=7, He]; 8.40 [d, J(PtꢀH)=44,
(200 MHz, CDCl3): l=0.91 [d, 2J(PtꢀH)=80,
3J(PꢀH)=8, Mea]; 1.05 [d, J(HꢀH)=7, Meb]; 4.40 [q,
J(HꢀH)=7, Hc]; {6.93 [m, 2H]; 7.18 [m, 5H], 7.33 [m,
2
J(HꢀH)=2, Hf]; minor isomer: l=1.15 [s, J(PtꢀH)=
70, Meb]; 1.61 [s, 2J(PtꢀH)=68, Mea]; 1.76 [d,
3
J(HꢀH)=7, Hd]; 1.98 [s, J(PtꢀH)=12, Hc]; 2.14 [s,
3
10H]; 7.68 [m, 5H], aromatics}; 8.27 [s, J(PtꢀHd)=53,
3J(PtꢀH)=13, Hc]; 6.22 [q, J(HꢀH)=7, J(PtꢀH)=6.5,
He]; 8.52 [d, 3J(PtꢀH)=45, J(HꢀH)=1, Hf]. Anal.
Found: C, 32.4; H, 3.8; N, 2.2. Calc. for C17H24INPtS2:
C, 32.49; H, 3.85; N, 2.23%.
Hd]. 31P-NMR (101.26 MHz, CDCl3): l=31.29
[J(PtꢀP)=2586]. Anal. Found: C, 55.8; H, 4.4; N, 2.1.
Calc. for C32H30NPPtS: C, 55.97; H, 4.40; N, 2.04%.
[PtMe{(3-((S)-PhCHMeNCH)C4H2S}P(2-MeC6H4)3]
(4) was prepared in an analogous way using the corre-
sponding phosphine. Yield 60 mg (80%). 1H-NMR (200
[PtMe2I{(3-((S)-PhCHMeNCH)C4H2S}PPh3]
(7b/
1
3
7b%). Yield 45 mg (74%). Major isomer: H-NMR (500
MHz, CDCl3): major isomer: l=0.05 [d, J(PꢀH)=7,
MHz, acetone-d6): l=0.82 [d, 2J(PtꢀH)=60,
Meb]; 0.99 [d, 2J(PtꢀH)=82, 3J(PꢀH)=8, Mea];
{1.60[s], 1.95[s], 2.97[s], He}; 4.65 [q, J(HꢀH)=7, Hc];
2
J(HꢀP)=7, Meb]; 1.60 [d, J(PtꢀH)=69, J(HꢀP)=7,
3
Mea]; 1.05 [d, J(HꢀH)=7, Hc]; 6.02 [q, J(HꢀH)=7,
J(PtꢀH)=7, Hd]; {6.54 [d, J(HꢀH)=7], 7.10 [d,
J(HꢀH)=5.5, J(HꢀPt)=25], aromatics}, 8.75 [d,
3J(PtꢀH)=48, J(HꢀH)=2, He]. 31P-NMR (101.26
MHz, acetone-d6): l= −10.45 [J(PtꢀP)=983]. Minor
8.04 [s, J(PtꢀHd)=52, Hd]; 9.22 [dd, J(HꢀH)=16; 7,
Har]. 31P-NMR (101.26 MHz, CDCl3): l=25.17
[J(PtꢀP)=2473];
minor
isomer:
l=0.96
[d,
2J(PtꢀH)=82, 3J(PꢀH)=8, Mea]; 1.48 [d, 3J(PꢀH)=7,
Meb]; {1.57[s], 1.95[s], 2.81[s], He}; 8.37 [s, J(PtꢀHd)=
3
1
isomer: H-NMR (500 MHz, acetone-d6): l=1.35 [d,
52, Hd]; 9.15 [dd, J(HꢀH)=16; 7, Har]. 31P-NMR
(101.26 MHz, CDCl3): l=26.12 [J(PtꢀP)=2479].
Anal. Found: C, 57.6; H, 4.9; N, 1.9. Calc. for
C35H36NPPtS: C, 57.68; H, 4.98; N, 1.92%.
2
2J(PtꢀH)=60, J(HꢀP)=7, Meb]; 1.69 [d, J(PtꢀH)=
70, J(HꢀP)=8, Mea]; 1.82 [d, J(HꢀH)=7, Hc]; 5.72 [q,
J(HꢀH)=6, Hd]; {6.98 [d, J(HꢀH)=5], 7.03 [d,
J(HꢀH)=5], aromatics}, 7.78 [s, 3J(PtꢀH)=45, He].
31P-NMR (101.26 MHz, acetone-d6): l= −10.60
[J(PtꢀP)=1012]. Anal. Found: C, 47.4; H, 4.0; N, 1.9.
Calc. for C33H33INPtS: C, 47.83; H, 4.01; N, 1.69%.
The reactions of compounds 2 and 3 with methyl
iodide were monitored by NMR in the following way;
10 ml of methyl iodide were added to 20 mg of the
corresponding compound dissolved in 0.6 ml of ace-
tone-d6 in a 5 mm NMR tube and spectra were taken.
[PtMe{(3-((S)-PhCHMeNCH)C4H2S}Ph2PCH2CH2-
PPh2] (5) was obtained by the reaction of 50 mg
(1.03×10−4 mol) of compound 2 with 41 mg (1.03×
10−4 mol) of dppe in acetone. After continuous stirring
for 6 h, the solvent was removed in a rotary evaporator
and the resulting white solid was filtered, washed with
hexane, and diethylether and dried in vacuum. Yield 60
1
mg (71%). H-NMR (200 MHz, CDCl3): l=0.64 [t,
3
2J(PtꢀH)=69, J(PꢀH)=7, Mea]; 1.39 [d, J(HꢀH)=7,
Meb]; 2.25 [m, CH2P], 4.09 [q, J(HꢀH)=7, Hc]; {7.21
[m]; 7.35 [m], 7.49 [m]; 7.72 [m], aromatics}; 8.38 [s,
3J(PtꢀHd)=8, Hd]. 31P-NMR (101.26 MHz, CDCl3):
l=47.38 [J(PtꢀP)=2233], 44.28 [J(PtꢀP)=1660].
Anal. Found: C, 58.2; H, 4.8; N, 1.6. Calc. for
C40H39NP2PtS: C, 58.39; H, 4.78; N, 1.70%.
[PtMe2I{(3-((S)-PhCHMeNCH)C4H2S}PPh3]
(7a/
7a%). [PtMe2I{(3-((S)-PhCHMeNCH)C4H2S}PPh3] (7a/
7a%) was characterized spectroscopically in solution.
1
Major isomer: H-NMR (200 MHz, acetone-d6): l=
0.21 [d, 2J(PtꢀH)=66, J(HꢀP)=7, Meb]; 1.46 [d,

184
C. Anderson et al. / Journal of Organometallic Chemistry 604 (2000) 178–185
Table 2
method. Intensities were collected with graphite
monochromatized Mo–Ka radiation, using ꢀ/2q scan-
technique. 2321 reflections were measured in the range
2.37BqB29.95°; 2299 were non-equivalent by symme-
try and 2083 were assumed as observed applying the
condition [I\2|(I)]. Three reflections were measured
every 2 h as orientation and intensity controls; signifi-
cant intensity decay was not observed. Lorentz polariza-
tion and absorption corrections were made. Further
details are given in Table 2.
Crystallographic data and details of the refinements for compound 2
Formula
C16H21NPtS2
486.55
Formula weight
Crystal system
Space group
Orthorhombic
P212121
11.191(2)
11.974(7)
12.321(8)
90
90
90
1651(2)
2.076
4
,
a (A)
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
3.3.2. Structure solution and refinement
Dcalc (g cm−3
)
The structure was solved by direct methods, using
SHELXS computer program [22], and refined by the full-
matrix least-squares method, with the SHELX-93 com-
puter program [23] using 2249 reflections (very negative
intensities were not assumed). The function minimized
Z
F(000)
936
Crystal size (mm3)
0.1×0.1×0.2
0.71069
293(2)
2321
0.0321
0.0673
183
0.0
,
u(Mo–Ka) (A)
T (K)
2
2 2
was
ꢀ wꢁꢁFoꢁ −ꢁFcꢁ ꢁ ,
where
w=[|2(I)+
Reflections collected
R[I\2|(I)]
(0.0326P)2]−1, and P=(ꢁFoꢁ +2ꢁFcꢁ )/3. f, f % and f %%
were taken from international tables of X-ray crystal-
lography [24]. The chirality of the structure was defined
from the Flack coefficient [25], which is equal to 0.03(2)
for the given results. All hydrogen atoms were com-
puted and refined with an overall isotropic temperature
factor using a riding model. Further details are given in
Table 2.
2
2
Rw(F2)
Refined parameters
max. shift/estimated S.D.
max. and min. difference peaks (e A
−3
,
)
0.681 and −0.680
2J(PtꢀH)=68, J(HꢀP)=7, Mea]; 1.55 [d, J(HꢀH)=7,
Hc]; 5.35 [m, Hd]; 6.63 [d, J(HꢀH)=6, aromatics], 8.66
[d, 3J(PtꢀH)=46, He]. 31P-NMR (101.26 MHz, ace-
tone-d6): l= −6.03 [J(PtꢀP)=1544]. Minor isomer:
31P-NMR (101.26 MHz, acetone-d6): l= −3.92
[J(PtꢀP)=1553].
4. Supplementary material
An excess of ethyl iodide or benzylbromide (0.1 ml)
was added to solutions of 50 mg of compound 3 in ace-
tone. The mixtures were stirred for 48 h, and the solvent
was removed under vacuum to yield yellow solids.
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 140492 for compound 2.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: +44-1223-336033; e-
mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
[PtI{(3-((S)-PhCHMeNCH)C4H2S}PPh3] (8). 1H-
NMR (200 MHz, acetone-d6): l=1.73 [d, 2J(HꢀH)=7,
Mea]; 6.81 [m, Hb]; {7.35–7.50[m]; 7.71–7.82[m], aro-
3
matics}; 7.95 [d, J(HꢀPt)=89, J(HꢀP)=9.5, Hc]. 31P-
NMR
(101.26
MHz,
acetone-d6):
l=13.65
Acknowledgements
[J(PtꢀP)=3786]. Anal. Found: C, 46.5; H, 3.6; N, 1.7.
Calc. for C31H27INPPtS: C, 46.63; H, 3.41; N, 1.75%.
We acknowledge financial support from the DGICYT
(Ministerio de Educacio´n y Cultura, Spain) and from
the Generalitat de Catalunya.
[PtBr{(3-((S)-PhCHMeNCH)C4H2S}PPh3] (9). 1H-
NMR (200 MHz, acetone-d6): l=1.75 [d, 2J(HꢀH)=7,
Mea]; 6.50 [m, Hb]; {7.26–7.46[m]; 7.70–7.76[m],
aromatics}; 7.95 [d, 3J(HꢀPt)=90, J(HꢀP)=9.5,
Hc]. 31P-NMR (101.26 MHz, acetone-d6): l=15.02
[J(PtꢀP)=3836].
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