Synthesis, reactivity and crystal structures of platinum (II) and platinum (IV) cyclometallated compounds derived from 2- and 4-biphenylimines

Article abstract of DOI:10.1016/j.jorganchem.2005.09.011

The reaction of [Pt₂Me₄(μ-SMe₂) ₂] with ligands 4-C₆H₅C₆H ₄CHNCH₂CH₂NMe₂ (1a) and 2-C ₆H₅C₆H₄

Full text of DOI:10.1016/j.jorganchem.2005.09.011

Journal of Organometallic Chemistry 691 (2006) 444–454
www.elsevier.com/locate/jorganchem
Synthesis, reactivity and crystal structures of platinum (II)
and platinum (IV) cyclometallated compounds derived from
2- and 4-biphenylimines
a,
b
b
*
`
´
Margarita Crespo , Merce Font-Bardıa , Xavier Solans
a
`
Departament de Quı´mica Inorganica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
`
b
´
`
Departament de CristalÆlografia, Mineralogia i Diposits Minerals, Universitat de Barcelona, Martıi Franques s/n, 08028 Barcelona, Spain
Received 20 July 2005; received in revised form 31 August 2005; accepted 6 September 2005
Available online 14 October 2005
Abstract
The reaction of [Pt2Me4(l-SMe2)2] with ligands 4-C6H5C6H4CHNCH2CH2NMe2 (1a) and 2-C6H5C6H4CHNCH2CH2NMe2 (1b)
carried out in acetone at room temperature produced compounds [PtMe2{4-C6H5C6H4CHNCH2CH2NMe2}] (2a) and [PtMe2
{2-C6H5C6H4CHNCH2CH2NMe2}] (2b), respectively, in which the imines act as bidentate [N,N0] ligands. Cyclometallated [C,N,N0]
compounds [PtMe{4-C6H5C6H3CHNCH2CH2NMe2}] (3a) and [PtMe{2-C6H5C6H3CHNCH2CH2NMe2}] (3b), were obtained by
refluxing toluene solutions of compounds 2a or 2b. Reaction of [Pt2Me4(l-SMe2)2] with ligands 4-C6H5C6H4CHNCH2Ph (1c) and
2-C6H5C6H4CHNCH2Ph (1d) produced compounds [PtMe{4-C6H5C6H3CHNCH2Ph}SMe2] (5c) and [PtMe{2-C6H5C6H3CHNCH2Ph}-
SMe2] (5d) containing a [C,N] ligand, from which triphenylphosphine derivatives 6c and 6d were also prepared. In all cases, metallation
took place to yield five-membered endo-metallacycles and formation of seven-membered or of exo-metallacycles was not observed. The
reactions of 3a, 3b, 6c and 6d with methyl iodide were studied in acetone and gave the corresponding cyclometallated platinum (IV) com-
pounds. All compounds were characterised by NMR spectroscopy and compounds 3b, 4a, 6c and 6d were also characterised
crystallographically.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Platinum; Imines; Biphenyl; Cyclometallation; Crystal structure
1. Introduction
biphenyl cyclometallated moiety have been reported as
shown in Chart 1. These include six-membered cycles
derived from amines (structure A) [2] or imines (structure
B) [3,4], as well as 10-membered rings derived from the
latter through bis-insertion of alkynes [5]. Seven-membered
platinacycles (structures C [6] and D [7]) containing the
C@N group (endo-cycles) have been recently obtained in
a process involving formal insertion of a phenyl ligand into
Cyclometallated compounds attract a great deal of
interest due to their numerous applications in several fields,
such as organic and organometallic synthesis, the design of
new metallomesogens and biologically active compounds
[1]. The most widely studied examples are platinum and
palladium compounds with nitrogen donors in which
C–H activation takes place at phenyl ortho positions to
produce five-membered metallacycles. Although metalla-
tion sites other than benzene ring carbon have been less
explored, several examples of compounds containing a
a
Pt–C bond. In addition, doubly cyclometallated
compounds have also been reported (structures E [8] and
F [9]). Apart from examples mentioned above which
contain nitrogen donor ligands, five-membered platinacy-
cles derived from the 2,20-biphenyl dianion are also an
interesting class of compounds [10].
*
Following our studies of imines containing aromatic
groups such as benzene [11], thiophene [12], furane [13],
Corresponding author. Tel.: +34 934039132; fax: +34 934907725.
E-mail address: margarita.crespo@qi.ub.es (M. Crespo).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.09.011

M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
445
X
L
X
L
Ligands containing two (1a and 1b) and one (1c and 1d)
nitrogen atoms have been studied since in some cases
striking differences [12] have been observed in the prepara-
tion of cycloplatinated compounds from these two types of
ligands. As shown in Chart 2, two non-equivalent metalla-
tion sites leading to either five- or seven-membered endo-
metallacycles (containing the C@N group) are available
for ligands derived from 2-biphenyl while ligands derived
from 4-biphenyl can only produce five-membered metalla-
cycles. Moreover, ligands derived from benzylamine (1c
and 1d) may lead to formation of exo-metallacycles
although these are generally less prone to form than the
most prevalent endo-cycles [16].
Pd
Pd
RHC
H2N
N
B
A
Me2
N
X
L
X
Pt
Pt
R
N
N
Additional interest arise from the fact that the resulting
platinum (II) compounds are suitable substrates for study-
ing the oxidative addition of alkyl halides [17] and there-
fore the influence in this process of the position (ortho or
para) of the phenyl substituent can be evaluated.
D
C
L
2+
Me2N
Pt
NMe2
O
O
Pd
N
2. Results and discussion
N
O
Pd
Ligands 4-C6H5C6H4CHNCH2CH2NMe2 (1a), 2-
C6H5C6H4CHNCH2CH2NMe2 (1b), 4-C6H5C6H4CHN-
CH2Ph (1c) and 2-C6H5C6H4CHNCH2Ph (1d) were
prepared from the condensation reactions of the corre-
sponding aldehyde and N,N-dimethylethylenediamine or
benzylamine carried out in toluene at room temperature.
The resulting imines were characterised by 1H NMR
spectroscopy.
O
E
Me2N
Pt
L
NMe2
F
Chart 1. Several examples of compounds containing a biphenyl cyclo-
metallated moiety.
2.1. Cyclometallation in [C,N,N0] systems
naphthalene [14], phenanthrene- and anthracene [15], we
now report the reactions of [Pt2Me4(l-SMe2)2] with imines
derived from 2-biphenyl and 4-biphenylcarboxaldehydes.
The reactions of [Pt2Me4(l-SMe2)2] with potentially
tridentate ligands 1a and 1b carried out in acetone at room
temperature produced compounds [PtMe2{4-C6H5C6H4-
H
H
endo 5 memb.
NMe2
C
N
NMe2
C
N
endo 5 memb.
1a
1b
endo 7 memb.
H
H
endo 5 memb.
C
N
C
N
exo 5 memb.
exo 5 memb.
endo 5 memb.
1c
1d
endo 7 memb.
Chart 2. Possible metallation sites for ligands 1a–d studied in this work.

446
M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
CHNCH2CH2NMe2}] (2a) and [PtMe2{2-C6H5C6H4CHN-
CH2CH2NMe2}] (2b), respectively in which the imines act
as bidentate [N,N0] ligands. Compounds 2 were character-
ised by NMR spectroscopy and elemental analyses. In the
1H NMR spectra, two distinct resonances appear in the
methyl region, both coupled with 195Pt. The one at higher
field with a larger coupling to 195Pt is assigned to the
methyl trans to the NMe2 moiety. This assignment was
confirmed by a cross-peak between NMe2 and Meb ob-
served in the 2D NOESY NMR spectra. In addition, the
cross-peak between imine and methylene protons indicates
an E conformation around the C@N bond. The coordina-
tion of the ligand through both nitrogen atoms is con-
firmed by the coupling of both amine and imine protons
to platinum. The chemical shifts observed for 195Pt are in
the expected range [18] for a platinum(II) centre bound
to two carbon and two nitrogen atoms see Scheme 1.
Intramolecular activation of C–H bonds followed by
methane elimination as reported for analogous systems
[11–15] was achieved when toluene solutions of compounds
2 were refluxed for 2 h. Work-up of the resulting solutions
revealed in each case formation of a single isomer of a
[C,N,N0] cycloplatinated compound as depicted in Scheme
2. Compounds 3 were characterised by NMR spectroscopy
e
d
Hf
Hd
c
b
c
R2
a
C
N
NMe2
R2
NMe2
C
N
Pt
a
b
Me
Me
1a R2 = H; R4 = Ph
1b R2 = Ph; R4 = H
R4
2a R2 = H; R4 = Ph
2b R2 = Ph; R4 =H
R4
(ii)
d,d'
e,e'
c
d
b
Meb
Pt
I
c,c'
N
NMe2
N
NMe2
f
e
R2
Pt
R2
a
Me
Mea
2
(iii
)
2
5
3
3
5
4
R4
4
R4
4a R2 = H; R4 = Ph
4b R2 = Ph; R4= H
3a R2 = H; R4 = Ph
3b R2 = Ph; R4 = H
Scheme 1. (i): +[Pt2Me4(l-SMe2)2], in acetone RT, 30 min; (ii): Refluxing toluene, 2 h; (iii): +MeI, acetone, 20 min.
c
CH2Ph
R2
b
N
SMe2
b
a
d
(i)
Pt
R4
CH=NCH2Ph
R2
Mea
1c R2 = H; R4 = Ph
1d R2 =Ph; R4 = H
5c R2 = H; R4 = Ph
5d R2 = Ph; R4 = H
R4
c
c
(ii)
CH2Ph
CH2Ph
Meb
N
N
I
PPh3
d
d
(iii)
Pt
Pt
R2
R2
Mea
PPh3
Mea
3
5
3
5
R4
6c R2 = H; R4 = Ph
6d R2 = Ph; R4 = H
R4
7c R2 = H; R4 = Ph
7d R2 =Ph; R4= H
Scheme 2. (i): +[Pt2Me4(l-SMe2)2], acetone RT, 16 h.; (ii): +PPh3 (1:1), acetone, 2 h; (iii): +MeI, acetone, 10 min.

M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
447
and elemental analyses. In the 1H NMR spectra, the methyl
ligand and the dimethylamino group are coupled to
platinum and the values of the coupling constants are in
the usual range for analogous compounds. In agreement
with previous data, the J(H–Pt) values of the imine group
increase from the coordination compounds 2 to the cyclo-
metallated compounds 3. In addition, the aromatic proton
adjacent to the metallation site is also coupled to platinum
[J(H–Pt) ca. 60 Hz]. The presence of resonances
corresponding to 8 aromatic C–H confirms the metallation
process. The values obtained for d (195Pt) are in each case
shifted towards lower frequency when compared to the cor-
responding compound 2 which indicates a decrease in the
electronic density of the platinum centre upon metallation.
As previously indicated, for ligand 1b two non-
equivalent metallation sites leading to either five- or
seven-membered endo-metallacycles are available. How-
ever, all data suggest that formation of a five-membered
platinacycle takes place exclusively. Therefore, this process
is more favoured than the formation of a seven-membered
metallacycle, although the latter has been obtained in
stable cyclometallated compounds (see structure D of
Chart 1 [7]). Seven-membered platinacycles display distinct
spectral features derived from the formation of a non-
planar metallacycle [7] which allow us to disregard
formation of such species in the present case. Ultimate
confirmation of formation of a five-membered metallacycle
is obtained from crystallographic characterization for 3b
described below.
esting to note that steric crowding in the coordination
sphere of platinum has been shown to favour the cleav-
age of metallacycles upon reaction with triphenylphos-
phine [20].
Compounds 5 and 6 were characterised by NMR
spectroscopy and elemental analyses and compounds 6c
and 6d were also characterised crystallographically. All
spectral parameters are in good agreement with the re-
sults obtained for analogous aryl cyclometallated com-
pounds. In the 1H NMR spectra, the methyl ligand as
well as the methylene and the imine groups are coupled
to platinum; in addition for compounds 5 the dimethyl-
sulfide is also coupled to 195Pt while for compounds 6
the methyl group is also coupled to 31P. The aromatic
proton adjacent to the metallation site (H5) appears as
a singlet for 5c and as a doublet for 5d, in both cases
coupled to platinum; in addition, H5 is also coupled to
31P in compounds 6. J(P–Pt) values are in the range ex-
pected for a trans arrangement of the phosphine and a
phenyl group [12]. The values obtained for d(195Pt) are
shifted towards lower frequency as the ligand covalence
increases from S-donor (compounds 5) to P-donor (com-
pounds 6).
2.3. Oxidative addition reactions
Previous studies of the oxidative addition of alkyl ha-
lides to platinum (II) compounds indicate that nitrogen
donor ligands impart high nucleophilicity to the metal
centre, increasing its reactivity, which is, however, mod-
erated by the presence of bulky ligands that might hinder
or even inhibit the reaction [17]. In order to evaluate the
effect of the phenyl substituent in the metallated ring as
well as the effect of the bulky PPh3 ligand the reactions
of 3a, 3b, 6c and 6d with methyl iodide were studied in
acetone. In all cases, the reactions proceed to yield the
corresponding cyclometallated platinum (IV) compounds
containing either a [C,N,N0] (4a and 4b) or a [C,N] (7c
and 7d) ligand. The obtained compounds were character-
ized by elemental analyses and NMR spectroscopies and
4a was also characterized crystallographically.
2.2. Cyclometallation in [C,N] systems
The reactions of [Pt2Me4(l-SMe2)2] with ligands 4-
C6H5C6H4CHNCH2Ph (1c) and 2-C6H5C6H4CHNCH2Ph
(1d) were also studied. As depicted in Chart 2, for these li-
gands formation of exo-cyclic structures, in addition to five-
or seven-membered endo-cycles is possible. The reactions of
ligands 1c and 1d with [Pt2Me4(l-SMe2)2] carried out in ace-
tone at room temperature produced cyclometallated plati-
num compounds [PtMe{4-C6H5C6H3CHNCH2Ph}SMe2]
(5c) and [PtMe{2-C6H5C6H3CHNCH2Ph}SMe2] (5d) in
which the imines act as bidentate [C,N] ligands. The
cyclometallation process, which occurs along with methane
formation, takes place under milder conditions than those
reported for ligands 1a and 1b. In both cases, metallation
took place to yield the five-membered endo-metallacycles
depicted in Scheme 2. Formation of seven-membered
metallacycles (for 1d) or of exo-metallacycles was not
observed.
The reactions of compounds 5c and 5d with PPh3
were also carried out and produced cyclometallated com-
pounds [PtMe{4-C6H5C6H3CHNCH2Ph}PPh3] (6c) and
[PtMe{2-C6H5C6H3CHNCH2Ph}PPh3] (6d), respectively,
in which the phosphine replaces the SMe2 ligand. Even
with an excess of phosphine the metallacycles are not
cleaved, which can be taken as an indication of the high
stability of the formed endo-metallacycles [19]. It is inter-
1
For 4b, the H NMR spectrum reveals the formation
of a minor isomer (ca. 8% of the mixture) with spectral
data very close to those observed for the major isomer
which possibly arises from different orientations of the
phenyl substituent. Previous studies indicated that the
increased bulk of octahedral platinum (IV) versus
square-planar platinum (II) centres led to conformational
changes related to the steric requirements of the final
1
compounds [21]. In the H NMR spectra of 4a and 4b,
both the dimethylamino and methylene groups are
diastereotopic as a result of the chirality resulting from
octahedral coordination around the platinum. In both
1H and 13C NMR spectra the couplings to 195Pt
observed for methyl and imine are considerably reduced
when compared to those of the corresponding platinum
(II) substrates, in agreement with the increase of the

448
M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
oxidation state of the platinum centre. Consistently, the
values obtained for d(195Pt) are shifted towards
higher frequency when compared to those of compounds
3.
interactions. Selected bond lengths and angles are
given in Table 1 and molecular views are shown in Figs.
1–4.
In all cases the structures deduced from NMR studies
are confirmed. For 3b and 4a, the ligand behaves as
[C,N,N0]-tridentate and three fused [6,5,5] ring systems
For compounds 7c and 7d, a reduced coupling to plat-
inum is observed for the axial methyl, which suggests a
trans arrangement of the axial methyl and the PPh3.
The J(P–Pt) values, which are considerably reduced from
those of the corresponding platinum (II) compounds, are
in the range expected for platinum (IV) derivatives [12].
The results obtained indicate that the oxidative addition
takes place with trans stereochemistry and is followed by
isomerization of the resulting platinum (IV) compound in
order to minimise the unfavourable steric effects of the
bulky triphenylphosphine ligand.
containing
a
five-membered endo metallacycle are
formed. For 3b, a methyl ligand completes the square-
planar coordination of the platinum atom, while for 4a
an octahedral coordination with the usual fac-PtC3
arrangement [11] is displayed. For 6c and 6d, the ligand
behaves as [C,N]-bidentate leading to a fused [5,6] bicy-
clic system containing a five-membered metallacycle; a
methyl group, trans to the nitrogen atom, and a triphe-
nylphosphine ligand complete the coordination around
the platinum.
2.4. Crystal structures
In all cases the metallacycles are approximately planar
as suggested by the sum of internal angles of the five-mem-
bered metallacycles which are in all cases close to 540ꢁ [22]
and nearly coplanar with both the metallated phenyl and
the mean coordination plane. Bond lengths and angles lie
in the usual range for analogous compounds [11,14,20].
Most bond angles at platinum are close to the ideal value
of 90ꢁ, and the smallest angles correspond to those involv-
ing the ligand: ‘‘bite’’ angles C(phenyl)–Pt–N of 80.59(11)ꢁ
(3b), 81.4(2)ꢁ (4a), 78.89(15)ꢁ (6c) and 78.5(2)ꢁ (6d)
and N(1)–Pt–N(2) of 83.38(11)ꢁ (3b) and 80.0(2)ꢁ (4a).
Conversely, the largest angles correspond to N–Pt–P
(104.21(10)ꢁ (6c) and 107.23(14)ꢁ (6d)) in agreement with
the steric effects associated with the bulk of the
triphenylphosphine.
An interesting feature for these compounds containing
biphenyl fragments is the dihedral angle between both
phenyl groups which are mainly related to steric effects,
although packing effects cannot be disregarded. For anal-
ogous platinum (II) compounds containing a triphenyl-
phosphine, the two phenyl rings are tilted 10.4(2)ꢁ (6c)
or 49.9(3)ꢁ (6d) from each other; these values suggest
that for the 2-biphenyl system in 6d the phenyl substitu-
ent in the ortho position produces a larger congestion in
the platinum coordination sphere which is minimised by
rotation around the C–C bond. On the other hand, a
comparison between the fairly similar values obtained
for 2-biphenyl systems (43.5(2)ꢁ (3b) and 49.9(3)ꢁ (6d))
indicate that the bulky triphenylphosphine in 6d is suffi-
ciently far away as to have a significant effect in the po-
sition of the phenyl substituent. However, a comparison
of the values obtained for 4-biphenyl systems (10.4(2)ꢁ
(6c) and 40.4(2)ꢁ (4a)) suggest that the increased bulk
of octahedral platinum (IV) versus square-planar plati-
num (II) centres may play a significant role in the rela-
tive position of the phenyl substituent.
Suitable crystals of 3b, 4a, 6c and 6d were grown from
acetone solutions. The crystal structures are composed of
discrete molecules separated by van der Waals
Table 1
˚
Selected bond lengths (A) and angles (ꢁ) with estimated standard
deviations
Compound 3b
Pt–C(1)
Pt–N(1)
1.964(3)
1.990(3)
1.262(4)
1.492(6)
1.460(5)
80.59(11)
83.38(11)
Pt–C(18)
Pt–N(2)
2.064(3)
2.138(3)
1.432(4)
1.403(4)
1.444(5)
97.95(14)
98.06(13)
N–C(13)
N(1)–C(14)
C(1)–C(6)
C(14)–C(15)
C(1)–Pt–C(18)
C(18)–Pt–N(2)
N(2)–C(15)
C(6)–C(13)
C(1)–Pt–N(1)
N(1)–Pt–N(2)
Compound 4a
Pt–C(9)
Pt–C(19)
2.002(6)
2.076(6)
2.268(6)
1.283(8)
1.507(9)
1.445(9)
81.4(2)
86.6(3)
86.6(4)
100.2(2)
87.81(17)
90.5(3)
Pt–N(1)
Pt–C(18)
Pt–I
2.067(5)
2.082(8)
2.7947(11)
1.450(9)
1.430(7)
1.524(11)
98.4(3)
91.1(3)
80.0(2)
94.7(3)
91.83(15)
92.19(16)
Pt–N(2)
N(1)–C(13)
N(2)–C(15)
C(10)–C(13)
C(9)–Pt–N(1)
C(9)–Pt–C(18)
C(19)–Pt–C(18)
C(19)–Pt–N(2)
C(9)–Pt–I
N(1)–C(14)
C(9)–C(10)
C(14)–C(15)
C(9)–Pt–C(19)
N(1)–Pt–C(18)
N(1)–Pt–N(2)
C(18)–Pt–N(2)
N(1)–Pt–I
C(19)–Pt–I
N(2)–Pt–I
Compound 6c
Pt–C(1)
Pt–N
2.059(4)
2.128(3)
1.283(5)
1.395(5)
90.60(16)
86.35(13)
Pt–C(39)
Pt–P
N–C(14)
C(12)–C(13)
C(1)–Pt–N
N–Pt–P
2.062(4)
2.3022(12)
1.476(6)
1.445(6)
78.89(15)
104.21(10)
N–C(13)
C(1)–C(12)
C(1)–Pt–C(39)
C(39)–Pt–P
Compound 6d
Pt–C(9)
Pt–N
2.056(6)
2.134(5)
1.292(7)
1.389(8)
89.2(3)
Pt–C(39)
Pt–P
N–C(14)
C(8)–C(13)
C(9)–Pt–N
N–Pt–P
2.054(8)
2.2979(17)
1.474(7)
1.477(8)
78.5(2)
Although stacked structures are common for platinum
complexes, and they become increasingly favoured with
increasing arene size [23], significant pꢀ ꢀ ꢀp interactions
have not been found for these compounds derived from
biphenyl systems.
N–C(13)
C(8)–C(9)
C(9)–Pt–C(39)
C(39)–Pt–P
85.5(2)
107.23(14)

M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
449
Fig. 1. Molecular structure of compound 3b.
Fig. 2. Molecular structure of compound 4a.
2.5. Conclusions
does not inhibit the oxidative addition of methyl iodide.
However, indication of the steric crowding comes from
the fact that while the two phenyl groups are nearly
coplanar in 4-biphenyl system 6c, a larger dihedral angle
is observed for 2-biphenyl systems 3b and 6d and even
for platinum (IV) compound 4a containing a 4-biphenyl
system. In the latter cases, rotation around the C–C
bond of the biphenyl systems tends to minimise the steric
repulsion in the coordination sphere of platinum (II) (3b,
6d) or platinum (IV) (4a).
In spite of the fact that seven-membered metallacycles
have been described [6,7], this type of compound could
not be obtained from direct reaction of [Pt2Me4(l-
SMe2)2] with ligands 2-C6H5C6H4CHNCH2CH2NMe2
(1b) and 2-C6H5C6H4CHNCH2Ph (1d) derived from 2-
biphenylcarboxaldehyde. Instead, these reactions led
selectively to formation of the more favoured five-mem-
bered metallacycles. The obtained [C,N,N0] and [C,N]
cyclometallated platinum (II) compounds along with
their analogues derived from 4-biphenylcarboxaldehyde
and in some cases the phosphine derivatives were fully
characterized including crystal structures. Interestingly,
an ortho phenyl substituent does not affect the stability
of the five-membered metallacycle – since this is not
cleaved upon reaction with triphenylphosphine – and
3. Experimental
3.1. General
NMR spectra were performed at the Unitat de RMN
1
dꢀAlt Camp de la Universitat de Barcelona. H, 13C, 31P

450
M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
Fig. 3. Molecular structure of compound 6c.
Fig. 4. Molecular structure of compound 6d.
and 195Pt NMR spectra were recorded by using Varian
Gemini 200 (1H, 200 MHz), Bruker 250 (31P,
101.2 MHz;195Pt, 54 MHz), Mercury 400 (1H, 400 MHz;
13C, 100 MHz; 1H–1H NOESY; 1H–13C gHSQC) and Var-
1
ian 500 (1H and H–1H COSY, 500 MHz) spectrometers,
and referenced to SiMe4 (1H, 13C), H3PO4 (31P) and

M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
451
H2PtCl6 in D2O (195Pt). d values are given in ppm and J
values in Hz. Microanalyses were performed by the Servei
2J(Pt–H) = 88.8, Mea]; 0.61 [s, 2J(Pt–H) = 84.0, Meb];
3
2.65 [m, J(H–H) = 5.0, Hd], 2.84 [s, J(H–Pt) = 20.8, Hc];
3
de Recursos Cientıfics i Tecnics de la Universitat Rovira i
3.89 [m, J(H–H) = 5.0, He]; {7.36–7.44 [m, 7H], 7.54 [m,
´
`
Virgili de Tarragona.
2H], aromatics}; 8.69 [s, 3J(Pt–H) = 44.4, Hf]. 195Pt
NMR (54 MHz, CDCl3): d = ꢁ3463.0 [s]. Anal. Calc. for
C19H26N2Pt Æ 2H2O: C, 44.44; H, 5.89; N, 5.45. Found:
C, 45.0; H, 5.6; N, 5.5%.
3.2. Preparation of the compounds
Compounds 3 were obtained by refluxing during 2 h a
toluene solution (20 mL) containing 100 mg of the corre-
sponding compound 2. The solvent was concentrated in a
rotary evaporator to a small volume (2–3 mL) and orange
crystals of 3b were formed. 3a was obtained as an orange
solid when toluene was totally removed and the residue
was washed with ether (3 · 2 mL). [PtMe{4-C6H5C6H3CH-
NCH2CH2NMe2}] (3a). Yield 65 mg (67%). 1H NMR
(400 MHz, CDCl3): d = 1.02 [s, 2J(Pt–H) = 78.8, Mea];
2.85 [s, 3J(H–Pt) = 20.0, Hb]; {3.17 [t, 3J(H–H) = 6.0],
4.06 [t, 3J(H–H) = 6.0], Hc,d}; 7.17 [dd, J(H–H) = 7.6;
2.0, 1H, H2 or H3]; 7.31 [d, 3J(H–H) = 7.6, 1H, H2 or
H3]; 7.40 [t, 3J(H–H) = 7.6, 2H, Phmeta]; 7.49 [t, 3J(H–
Compound [Pt2Me4(l-SMe2)2] was prepared as reported
[24].
3.2.1. Synthetic procedure for the ligands
Compounds 1 were prepared by the reaction of 0.24 g of
N,N-dimethylethylenediamine or 0.29 g of N-benzylamine
(2.7 · 10ꢁ3 mol) with an equimolar amount (0.5 g) of the
corresponding aldehyde in toluene (20 mL). The mixture
was stirred for 1 h and dried over Na2SO4. The solvent
was removed in a rotary evaporator to yield yellow oils
(1a, 1b and 1d) or a white solid (1c). 4-C6H5C6H4-
CHNCH2CH2NMe2 (1a). Yield 0.6 g (87%). 1H NMR
(200 MHz, CDCl3): d = 2.33 [s, Ha]; 2.66 [t, 3J(Hb–
Hc) = 7.0, Hb]; 3.77 [t, 3J(Hc–Hb) = 7.0, Hc]; {7.18 [t,
3
H) = 7.2, 1H, Phpara]; 7.63 [d, J(H–H) = 8.0, 2H, Phortho];
3
7.84 [d, J(H–H) = 2.0, J(H–Pt) = 58.8, 1H, H5]; 8.60 [s,
3
3J(H–H) = 7.0, 1H], 7.44 [t, J(H–H) = 7.0, 2H], 7.63 [m,
3J(Pt–H) = 58.8, He]. 13C NMR (100 MHz, CDCl3):
d = ꢁ12.25 [Mea]; 48.96 [Cb]; {52.27 [2J(C–Pt) = 30.2],
68.12, Cc, Cd}; {121.55, 127.32, 127.62 [2C, J(C–
Pt) = 59.2], 128.18, 128.68 [2C], 132.57 [J(C–Pt) = 101.2],
aromatic C–H}; 167.44 [2J(Pt–C) = 94.7, Ce]. 195Pt NMR
(54 MHz, CDCl3): d = ꢁ3625.9 [s]. Anal. Calc. for
C18H22N2Pt: C, 46.85; H, 4.80; N, 6.07. Found: C, 47.4;
H, 5.0; N, 5.9%. [PtMe{2-C6H5C6H3CHNCH2CH2NMe2}]
(3b). Yield 57 mg (59%). 1H NMR (400 MHz, CDCl3):
d = 0.99 [s, 2J(Pt–H) = 78.8, Mea]; 2.83 [s, 3J(H–
Pt) = 19.6, Hb]; {3.12 [t, 3J(H–H) = 6.0], 3.97 [t, 3J(H–
H) = 6.0], Hc,d}; 6.87 [dd, 3J(H–H) = 7.6; 1.2, 1H, H3];
7.23 [t, 3J(H–H) = 7.6, 1H, H4]; 7.34 [t, 3J(H–H) = 7.6,
4H], 7.80 [d, 3J(H–H) = 8.0, 2H], aromatics}; 8.35 [s,
Hd]. 2-C6H5C6H4CHNCH2CH2NMe2 (1b). Yield 0.58 g
(84%). 1H NMR (200 MHz, CDCl3): d = 2.27 [s, Ha];
2.61 [t, 3J(Hb–Hc) = 7.0, Hb]; 3.63 [t, 3J(Hc–Hb) = 7.0,
3
Hc]; {7.18 [t, J(H–H) = 7.0, 1H], 7.34–7.48 [m, 7H], 8.07
[dd, J(H–H) = 7.0; 2.0, 1H], aromatics}; 8.26 [s, Hd]. 4-
C6H5C6H4CHNCH2Ph (1c). Yield 0.67 g (90%). 1H
NMR (200 MHz, CDCl3): d = 4.85 [s, Ha]; {7.37 [m, 5H],
3
3
7.46 [t, J(H–H) = 7.0, 3H], 7.63 [d, J(H–H) = 7.0, 2H],
3
7.65 [d, J(H–H) = 8.0, 2H], 7.86 [d, J(H–H) = 8.0, 2H],
aromatics}; 8.44 [s, Hd]. 2-C6H5C6H4CHNCH2Ph (1d).
Yield 0.60 g (81%). 1H NMR (200 MHz, CDCl3):
d = 4.71 [s, Ha]; {7.32–7.48 [m, 13H], 8.16 [dd, J(H–
H) = 7.0; 2.0, 1H], aromatics}; 8.36 [s, Hd].
3
2H, Phmeta]; 7.38 [d, J(H–H) = 8.0, 2H, Phortho]; 7.39 [t,
3J(H–H) = 7.6, 1H]; 7.60 [d, 3J(H–H) = 7.6, 3J(H–
Pt) = 63.6, 1H, H5]; 8.59 [s, 3J(Pt–H) = 61.6, He]. 13C
NMR (100 MHz, CDCl3): d = ꢁ12.25 [1J(C–Pt) = 791.8,
Mea]; 49.23 [Cb]; {52.94 [2J(C–Pt) = 30], 68.33, Cc, Cd};
{124.20, 127.48, 128.61 [2C], 130.03 [2C], 131.80 [1C,
3J(C–Pt) = 73.6, C3], 133.35 [1C, 2J(C–Pt) = 90.3, C2], aro-
matic C–H}; {142.37, 143.46, 143.59, 148.16, aromatic C};
167.41 [2J(Pt–C) = 93.6, Ce]. 195Pt NMR (54 MHz,
CDCl3): d = ꢁ3609.4 [s]. Anal. Calc. for C18H22N2Pt: C,
46.85; H, 4.80; N, 6.07. Found: C, 46.8; H, 4.8; N, 6.1%.
Compounds 5c and 5d were obtained by adding a solu-
tion of 94 mg (3.5 · 10ꢁ4 mol) of the corresponding imine
3.2.2. Synthetic procedure for the platinum (II) compounds
Compounds 2 were obtained by adding a solution of
88 mg (3.49 · 10ꢁ4 mol) of the corresponding imine in ace-
tone (10 mL) to a solution of 100 mg (1.74 · 10ꢁ4 mol) of
compound [Pt2Me4(l-SMe2)2] in acetone (10 mL). The
mixture was stirred for 30 min at room temperature. Com-
pounds 2a and 2b were obtained upon removal of the ace-
tone in a rotary evaporator. The yellow solids were washed
with ether (3 · 2 mL) and dried in vacuo. [PtMe2{4-
C6H5C6H4CHNCH2CH2NMe2}] (2a). Yield 120 mg
1
2
(72%). H NMR (200 MHz, CDCl3): d = 0.27 [s, J(Pt–
in acetone (10 mL) to
a
solution of 100 mg
H) = 90.0, Mea]; 0.63 [s, J(Pt–H) = 84.0, Meb]; 2.69 [m,
(1.74 · 10ꢁ4 mol) of compound [Pt2Me4(l-SMe2)2] in ace-
tone (10 mL). The mixture was stirred for 16 h at room
temperature and compounds 5 were obtained as orange
(5c) or yellow (5d) solids upon removal of the acetone in
a rotary evaporator. The products were washed with hex-
ane (3 · 2 mL) and dried in vacuo. [PtMe{4-C6H5C6-
H4CHNCH2Ph}SMe2] (5c). Yield 110 mg (58%). 1H
NMR (400 MHz, CDCl3): d = 1.06 [s, 2J(Pt–H) = 82.4,
2
Hd]; 2.84 [s, J(H–Pt) = 22.0, Hc]; 4.07 [m, He]; {7.44 [m,
3
3H], 7.63 [m, 4H], 8.36 [d, J(H–H) = 8.0, 2H], aromatics};
9.00 [s, 3J(Pt–H) = 46.0, Hf]. 195Pt NMR (54 MHz,
CDCl3): d = ꢁ3461.5 [s]. Anal. Calc. for C19H26N2Pt: C,
47.79; H, 5.49; N, 5.87. Found: C, 47.3; H, 5.8 N, 5.6%.
[PtMe2{2-C6H5C6H4CHNCH2CH2NMe2}] (2b). Yield
1
127 mg (76%). H NMR (200 MHz, CDCl3): d = 0.19 [s,

452
M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
Mea]; 2.02 [s, 3J(H–Pt) = 26.4, Hb]; 5.22 [s, 3J(Pt–
H) = 12.8, Hc], {7.33 [m, 5H], 7.43 [m, 4H], 7.66 [m, 3H],
7.99 [s, 3J(H–Pt) = 62.4, H5], aromatics}; 8.62 [s, 3J(H–
Pt) = 54.4, Hd]. 195Pt NMR (54 MHz, CDCl3):
d = ꢁ3633.2 [s]. Anal. Calc. for C23H25NPtS: C, 50.91;
H, 4.64; N, 2.58. Found: C, 51.4; H, 4.7; N, 2.7%.
[PtMe{2-C6H5C6H4CHNCH2Ph}SMe2] (5d). Yield 100
mg (53%). 1H NMR (200 MHz, CDCl3): d = 1.01 [s,
J(H–H) = 12.0; 5.0, 1H], Hd;d0
}
{4.05 [ddd, J(H–
H) = 12.0; 4.0; 2.0, 1H], 4.13 [m, 1H], He;e0}; 7.26 [dd,
J(H–H) = 8.0; 1.6, 1H, H2]; 7.35 [t, J(H–H) = 7.2, 1H,
3
Phpara]; 7.41 [d, 3J(H–H) = 7.6; 1H, H3]; 7.43 [t, 3J(H–
H) = 7.6; 2H, Phmeta]; 7.53 [d, J(H–H) = 1.6, 3J(H–
3
Pt) = 46.4, 1H, H5]; 7.66 [d, J(H–H) = 7.2, 2H, Phortho];
8.42 [s, 3J(Pt–H) = 48.0, Hf]. 13C NMR (100 MHz,
CDCl3): d = ꢁ5.49 [1J(C–Pt) = 622.7, Mea]; 9.57 [1J(C–
Pt) = 662.2, Meb]; {47.32, 53.46, Cc;c0}; 51.96 [2J(C–
Pt) = 15.2, Ce]; 67.85 [Cd]; 122.87 [C2]; 127.79 [2C, Phmeta];
128.01 [Phpara]; 128.87 [2C, Phortho]; 129.71 [2J(C–
Pt) = 47.1, C5]; 129.77 [4J(C–Pt) = 34.6, C3]; 167.92
[2J(Pt–C) = 52.3, Ce]. 195Pt NMR (54 MHz, CDCl3):
d = ꢁ2653.72 [s]. Anal. Calc. for C19H25IN2Pt: C, 37.82;
H, 4.17; N, 4.64. Found: C, 37.5; H, 4.2; N, 4.3%. Com-
pounds 4b, 7c and 7d were obtained following the same
procedure from 3b, 6c and 6d, respectively. [PtMe2I{2-
C6H5C6H3CHNCH2CH2NMe2}] (4b). Yield 18 mg (69%).
1H NMR (400 MHz, CDCl3): major isomer, d = 0.85 [s,
2J(Pt–H) = 71.6, Meb]; 1.26 [s, 2J(Pt–H) = 64.0, Mea];
{2.57 [s, 3J(H–Pt) = 15.2], 3.21 [s, 3J(H–Pt) = 10.8],
Mec}; {2.99 [m, 1H], 3.97 [m, 1H], 4.08 [m, 1H], 4.18 [td,
J(H–H) = 12.0; 5.0, 1H], Hd;d0;e;e0}; {6.96 [dd, J(H–
H) = 7.0; 1.2, 1H], 7.27–7.32 [m, 2H], 7.38–7.43 [m, 5H],
aromatics}; 8.41 [s, 3J(Pt–H) = 49.2, Hf]. minor isomer,
d = 0.68 [s, 2J(Pt–H) = 74.4, Meb]; 1.06 [s, 2J(Pt–
3
2J(Pt–H) = 80.2, Mea]; 1.99 [s, J(H–Pt) = 26.6, Hb]; 5.14
[s, 3J(Pt–H) = 13.8, Hc], {7.01 [d, 3J(H–H) = 8.0, 1H],
7.29–7.40 [m, 11H], 7.75 [d, 3J(H–H) = 7, 3J(H–
3
Pt) = 62.8, 1H, H5], aromatics}; 8.67 [s, J(H–Pt) = 56.4,
Hd]. 195Pt NMR (54 MHz, CDCl3): d = ꢁ3972.9 [s]. Anal.
Calc. for C23H25NPtS: C, 50.91; H, 4.64; N, 2.58. Found:
C, 50.5; H, 4.8; N, 2.8%.
Compounds 6c and 6d were obtained by adding 24 mg
(0.9 · 10ꢁ4 mol) of PPh3 to
a solution of 50 mg
(0.9 · 10ꢁ4 mol) of the corresponding compound 5 in
acetone (10 mL). The mixture was stirred for 1 h at room
temperature and the acetone was removed in a rotary
evaporator. The yellow solids were washed with hexane
(3 · 2 mL) and ether (3 · 2 mL) and dried in vacuo.
[PtMe{4-C6H5C6H4CHNCH2Ph}PPh3] (6c). Yield 40 mg
1
2
(58%). H NMR (200 MHz, CDCl3): d = 0.87 [d, J(Pt–
3
3
H) = 82.4, J(P–H) = 7.4, Mea]; 4.29 [s, J(Pt–H) = 10.0,
Hc], {6.81–6.86 [m, 1H], 7.17–7.20 [m, 1H], 7.34–7.44 [m,
4
3
3
3
15H], 7.64–7.74 [m, 10H], 8.13 [d, J(H–P) = 7.0, J(H–
H) = 62.8, Mea]; {2.57 [s, J(H–Pt) = 15.2], 2.97 [s, J(H–
Pt) = 9.0], Mec}; 7.00 [d, J(H–H) = 7.2; 1H]; 8.46 [s,
3J(Pt–H) = 49.6, Hf]. 13C NMR (100 MHz, CDCl3):
d = ꢁ5.26 [1J(C–Pt) = 620.6, Mea]; 9.67 [1J(C–
Pt) = 665.1, Meb]; {47.27, 53.46, Cc;c0}; 52.30 [2J(C–
Pt) = 15.0, Ce]; 67.73 [Cd]; {125.30, 127.79, 128.52 [2C],
129.90 [2C], 130.36 [J(C–Pt) = 40.9], 132.41 [J(C–
Pt) = 58.5], aromatics C–H}; {139.55, 140.62, 143.24,
144.37, aromatic C}; 168.02 [2J(Pt–C) = 50.0, Ce]. 195Pt
NMR (54 MHz, CDCl3): d = ꢁ2662.9 [s]. Anal. Calc. for
C19H25IN2Pt: C, 37.82; H, 4.17; N, 4.64. Found: C, 38.1;
H, 4.4; N, 4.6%. [PtMe2I{4-C6H5C6H4CHNCH2Ph}PPh3]
(7c). Yield 20 mg (84%). 1H NMR (200 MHz, CDCl3):
d = 1.27 [d, 2J(Pt–H) = 59.8, 3J(P–H) = 7.6, Meb]; 1.64
Pt) = 48.6, H5], aromatics}; 8.33 [s, J(H–Pt) = 55.2, Hd].
3
31P NMR (101.2 MHz, CDCl3): d = 30.13 [s, 1J(Pt–
P) = 2189.0]. 195Pt NMR (54 MHz, acetone-d6): d =
ꢁ4248.5 [s, 1J(Pt–P) = 2196.0]. Anal. Calc. for
C39H34NPPt Æ 2H2O: C, 60.15; H, 4.92; N, 1.80. Found:
C, 59.8; H, 4.7; N, 2.0%. [PtMe{2-C6H5C6H4CHNCH2-
1
Ph}PPh3] (6d). Yield 40 mg (58%). H NMR (200 MHz,
CDCl3): d = 0.82 [d, 2J(Pt–H) = 82.0, 3J(P–H) = 7.0,
Mea]; 4.25 [s, 3J(Pt–H) = 10.2, Hc], {6.70–6.75 [m, 1H],
7.07–7.10 [m, 1H], 7.30–7.34 [m, 15H], 7.59–7.68 [m,
10H], 7.94 [dd, 3J(H–H) = 6, 4J(H–P) = 5.0, 3J(H–
3
Pt) = 50.8, H5], aromatics}; 8.46 [s, J(H–Pt) = 57.4, Hd].
31P NMR (101.2 MHz, CDCl3): d = 29.87 [s, 1J(Pt–
P) = 2168.0]. 195Pt NMR (54 MHz, acetone-d6):
d = ꢁ4245.5 [s, 1J(Pt–P) = 2164.0]. Anal. Calc. for
C39H34NPPt Æ H2O: C, 61.57; H, 4.6; N, 2.0. Found: C,
61.1; H, 4.6; N, 2.0%.
2
[d, J(Pt–H) = 70.2, 3J(P–H) = 7.8, Mea]; {4.70 [d], 5.55
[d], 3J(H–H) = 17.0, Hc}, {6.69 [s, 3J(H–Pt) = 46.6, 1H,
H5], 6.88–6.91 [m, 1H], 7.20–7.47 [m, 26H], aromatics};
7.71 [d, J(H–P) = 1.6, 3J(H–Pt) = 48.2, Hd]. 31P NMR
(101.2 MHz, CDCl3): d = ꢁ9.20 [s, 1J(Pt–P) = 1009.7].
Anal. Calc. for C40H37INPPt Æ 2H2O: C, 52.18; H, 4.49;
N, 1.52. Found: C, 52.6; H, 4.7; N, 1.5%. [PtMe2I{2-
C6H5C6H4CHNCH2Ph}PPh3] (7d). Yield 18 mg (75%).
1H NMR (200 MHz, CDCl3): d = 1.25 [d, 2J(Pt–
3.2.3. Synthetic procedure for the platinum (IV) compounds
An excess of methyl iodide (0.5 mL) was added to a
solution of 20 mg of compound 3a in acetone and the mix-
ture was stirred at room temperature. After 15 min, the
solution colour changed from red to yellow. The solvent
was removed and the residue was washed with hexane to
yield 4a as a light yellow solid which was dried in vacuo.
[PtMe2I{4-C6H5C6H3CHNCH2CH2NMe2}] (4a). Yield
18 mg (69%). 1H NMR (400 MHz, CDCl3): d = 0.84 [s,
2J(Pt–H) = 71.6, Meb]; 1.30 [s, 2J(Pt–H) = 64.8, Mea];
{2.58 [s, 3J(H–Pt) = 15.2], 3.22 [s, 3J(H–Pt) = 11.2],
Mec}; {3.02 [ddd, J(H–H) = 12.0; 5.0; 3.0, 1H], 4.23 [td,
3
2
H) = 60.4, J(P–H) = 7.6, Meb]; 1.56 [d, J(Pt–H) = 69.6,
3J(P–H) = 7.8, Mea]; {4.79 [d], 5.53 [d], J(H–H) = 16.4,
3
Hc}, {6.61 [m, 1H], 6.83–6.85 [m, 2H], 6.92–6.95 [m, 3H],
7.18–7.45 [m, 22H], aromatics}; 7.80 [d, J(H–P) = 1.6,
3J(H–Pt) = 49.6, Hd]. 31P NMR (101.2 MHz, CDCl3):
d = ꢁ8.96 [s, 1J(Pt–P) = 991.4]. Anal. Calc. for
C40H37INPPt Æ 2H2O: C, 52.18; H, 4.49; N, 1.52. Found:
C, 52.6; H, 4.7; N, 1.6%.

M. Crespo et al. / Journal of Organometallic Chemistry 691 (2006) 444–454
453
Table 2
Crystallographic and refinement data for compounds 3b, 4a, 6c and 6d
Compound 3b
Compound 4a
Compound 6c
Compound 6d
Formula
Fw
C18H22N2Pt
461.47
C19H25IN2Pt
603.40
C39H34NPPt
742.73
C39H34NPPt
742.73
Temperature (K)
Wavelength (A)
293(2)
0.71073
293(2)
0.71073
293(2)
0.71073
293(2)
0.71073
˚
ꢀ
Crystal system, space group
Orthorhombic, Pbca
11.212(4)
25.578(2)
11.121(4)
90
Monoclinic, P21/n
7.886(4)
17.270(7)
15.105(6)
90
101.95(2)
90
2012.6(15); 4
1.991
Triclinic P1
Monoclinic, P21/c
8.708(12)
20.364(4)
17.473(9)
90
90.57(7)
90
3098(5); 4
1.592
˚
a (A)
12.215(6)
12.488(5)
12.746(5)
99.52(2)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
115.15(2)
106.78(3)
1589.2(12); 2
1.552
3
˚
V (A ); Z
3189.3(16); 8
1.922
8.794
d (calcd) (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
)
8.507
1136
4.493
736
4.609
1472
1776
Number of refections collected/unique (Rint
Data/restraints/parameters
Goodness-of-fit F2
)
22,949/4503 (0.0241)
4503/0/190
0.975
18,925/5640 (0.0460)
5640/0/209
1.224
18,008/9327 (0.0284)
9327/0/380
1.208
9021/9021 (0.0310)
9021/0/423
0.850
R1(I > 2r(I))
0.0341
0.0473
0.0358
0.0363
wR2 (all data)
Peak and hole (e A
0.1105
0.895 and ꢁ0.702
0.0932
0.869 and ꢁ0.663
0.0790
0.881 and ꢁ0.768
0.0862
0.771 and ꢁ0.847
ꢁ3
˚
)
3.3. X-ray structure analysis
3.3.1. Data collection
(0.1530P)2]ꢁ1 (3b), w = [r2(I) + (0.0187P)2 + 7.0257P]ꢁ1
(4a), w = [r2(I) + (0.0143P)2 + 3.0417P]ꢁ1 (6c) and w =
[r2(I) + (0.0269P)2]ꢁ1 (6d) and P = (jFoj + 2jFcj )/3. f, f0
and f00were taken from International Tables of X-ray Crys-
tallography [26]. For 6d, 11 H atoms were located from a
difference synthesis and refined with an overall isotropic
temperature factor. Twenty three hydrogen atoms (6d)
and all H atoms (3b, 4a and 6c) were computed and refined,
using a riding model, with an isotropic factor equal to 1.2
times the equivalent temperature factor of the atom to
which they are linked. Further details are given in Table 2.
2
2
Crystals of 3b, 4a, 6c and 6d were obtained from slow
evaporation of acetone solution. Prismatic crystals were se-
lected and mounted on an MAR345 diffractometer with an
image plate detector (3b, 4a and 6c) or on a Enraf-Nonius
diffractometer (6d). Unit cell parameters were determined
from 117 (3b), 97 (4a), 108 (6c) reflections (3ꢁ < h
< 31ꢁ) or from automatic centering of 25 reflections
(12ꢁ < h < 21ꢁ) (6d) and refined by least-squares method.
Intensities were collected with graphite monochromatized
Mo Ka radiation. For 3b, 22,949 reflections were measured
in the range 3.52ꢁ < h < 33.46ꢁ; 4503 of which were non-
equivalent by symmetry (Rint = 0.024). For 4a, 18,925
reflections were measured in the range 3.60ꢁ < h < 33.17ꢁ;
5640 of which were non-equivalent by symmetry
(Rint = 0.046). For 6c, 18,008 reflections were measured
in the range 3.49ꢁ < h < 33.23ꢁ; 9327 of which were non-
equivalent by symmetry (Rint = 0.028). For 6d, 9021 reflec-
tions were measured in the range 2.00ꢁ < h < 29.97ꢁ. 3211
(3b), 5189 (4a), 8387 (6c) and 4113 (6d) reflections were as-
sumed as observed applying the condition I > 2r(I). Lor-
entz polarisation and absorption corrections were made.
Further details are given in Table 2.
4. Supplementary material
The crystallographic data of compounds 3b, 4a, 6c and 6d
have been deposited with the Cambridge Crystallographic
Data Centre, CCDC 278492, 278493, 278490 and 278491.
Acknowledgements
This work was supported by the Ministerio de Ciencia y
´
Tecnologıa (project: BQU2003-00906/50% FEDER) and
by the Comissionat per a Universitats i Recerca (project:
2001SGR-00054).
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