Biaryl formation in the synthesis of endo and exo-platinacycles

Article abstract of DOI:10.1039/c1dt10664c

The reactions of cis-[Pt₂(4-MeC₆H₄) ₄(μ-SEt₂)₂] with bifunctional ligands ArCHNCH₂(2-XC₆H₄) containing a C-X bond at the ortho positions of the benzyl ring

Full text of DOI:10.1039/c1dt10664c

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PAPER
Biaryl formation in the synthesis of endo and exo-platinacycles†
Margarita Crespo,a Merce` Font-Bardiab,c and Teresa Calvetb
Received 14th April 2011, Accepted 5th July 2011
DOI: 10.1039/c1dt10664c
The reactions of cis-[Pt2(4-MeC6H4)4(m-SEt2)2] with bifunctional ligands ArCH NCH2(2-XC6H4)
containing a C–X bond at the ortho positions of the benzyl ring (Ar = 4-ClC6H4, X = Br (1d);
Ar = 2,4,6-(CH3)3C6H2, X = Br (1e); Ar = 2,4,6-(CH3)3C6H2, X = Cl (1f); Ar = 2-CH3C6H4, X = Br (1h);
Ar = 2,6-F2C6H3, X = Br (1i)) in refluxing toluene were studied. Several types of platinum(II)
cyclometallated compounds containing a biaryl linkage were obtained: i) endo-five-membered with a
Pt–C(sp2) bond (2d, 2h), ii) endo-six-membered with a Pt–C(sp3) bond (2e, 2f), and iii) exo-five
membered with a Pt–C(sp2) bond (2i). The formed biaryl linkage involves the metallated ring for 2i and
the non-metallated ring for the endo-metallacycles. The reaction of compounds 2 with PPh3 produced
the corresponding phosphine derivatives, some of which (3d, 3e, 3h and 3i) were characterised
crystallographically. In addition, compound [PtBr{2-CH3C6H3C6H4CH NCH2(2-C6H4Br)}SEt2] (2c)
containing a seven-membered endo-metallacycle was also obtained and characterised
crystallographically.
ArCH NCH2(4-ClC6H4) [Ar = 2-BrC6H4 (1a) or 2,6-Cl2C6H3
Introduction
(1b) shown in Scheme 1] or with the corresponding potentially
terdentate ligands ArCH NCH2CH2NMe2. It has been shown
that these reactions take place through initial intramolecular C–X
(X = Br or Cl) bond activation to produce an endo cyclometallated
platinum(IV) compound as intermediate.6 In the final products
2a and 2b a biaryl linkage between a platinum-bound tolyl
ligand and the benzylidene ring of the imine, as well as a seven-
membered metallacycle containing the imine functionality (endo-
metallacycle) are formed. All related C–C coupling processes
leading to either seven-7 or five-membered8 platinacycles also
involve endo-metallacycles.
As part of a project aimed at analyzing the scope of the forma-
tion of biaryl linkages in the coordination sphere of platinum, we
decided to study the behaviour in front of cis-[Pt2(4-MeC6H4)4(m-
SEt2)2] of N-benzylidenebenzylamines for which formation of
exo-metallacycles (in which the imine moiety is not included in
the metallacycle) is favoured. The obtained results will disclose
whether formation of a biaryl linkage is possible in this case
or if the rigidity associated with endo metallacycles (containing
the imine functionality) is required. The imines selected for this
study contain a C–Br bond at one ortho position of the more
C–C bond formation is one of the most important processes in
organic synthesis. Palladium catalyzed cross-coupling reactions
such as those initially reported by Heck,1 Negishi,2 and Suzuki,3
are of great importance in the formation of new pharmaceuticals
and bioactive compounds and this field is still being developed
after 40 years.4 It is becoming clear that in addition to Pd(0)/Pd(II)
cycles, involvement of Pd(II)/Pd(IV) systems might play a decisive
role, and that parallel studies with organoplatinum compounds are
often useful in providing more stable species.5
We have previously reported a process involving C–C coupling
and formation of seven-membered platinum(II) metallacycles
in the reactions of cis-[Pt2(4-MeC6H4)4(m-SEt2)2] with ligands
aDepartament de Qu´ımica Inorga`nica, Universitat de Barcelona, Diag-
onal 647, 08028, Barcelona, Spain. E-mail: margarita.crespo@qi.ub.es;
Fax: +34934907725; Tel: +34934039132
bDepartament de Cristal·lografia, Mineralogia i Dipo`sits Minerals, Univer-
sitat de Barcelona, Mart´ı i Franque`s s/n, 08028, Barcelona, Spain
cUnitat de difraccio´ de RX, Serveis Cient´ıfico-Te`cnics, Universitat de
Barcelona, Sole´ i Sabar´ıs, 1-3, 08028, Barcelona, Spain
† CCDC reference numbers 822500–822503. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/c1dt10664c
Scheme 1 Previously reported formation of seven-membered platinacycles (ref. 6).
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flexible benzyl ring (1c, 1d, 1e, 1h and 1i), so that formation of
exo-metallacycles is favoured, and different substituents at the
benzylidene ring so that different types of metallacycles could
be obtained as final products. In addition, we thought that for
imines 1f and 1g, in which the ortho positions of the benzylidene
group are blocked with methyl substituents, the reaction could
also be driven towards formation of an exo-metallacycle even by
activation of stronger C–Cl or C–H bonds, instead of C–Br, at the
ortho positions of the benzyl ring. A preliminary communication
of part of this work involving imines 1e, 1f and 1g and leading to
unusual six-membered platinacycles has been already published.9
The structures of all the N-benzylidenebenzylamines used in this
work are shown in Chart 1 and compared with those previously
studied.
range of values obtained for analogous compounds.6 The obtained
result indicates that intramolecular C–Br bond activation takes
place selectively at the benzylidene ring which is consistent with
the higher tendency to form endo versus exo metallacycles.10
Therefore, further work was planned using imines which contain
a C–Br bond exclusively in the benzyl group, in order to drive
the reaction towards formation of exo-platinacycles. It has been
previously reported for the reactions of the compound cis-
[Pt2Me4(m-SMe2)2] with N-benzylidenebenzylamines that, in spite
of the more favoured formation of endo-metallacycles, activation
of a C–Br bond leading to an exo-cycle is preferred over activation
of a C–H bond leading to an endo-cycle.11
As shown in Scheme 2, the reaction of cis-[Pt2(4-MeC6H4)4(m-
SEt2)2] with imine 4-ClC6H4CH NCH2(2-BrC6H4) (1d) in re-
fluxing toluene produced compound 2d, which contains a five-
membered endo-platinacycle and a newly formed C–C bond.
Formation of compound 2d suggests a process consisting of
activation of the C–Br bond leading to a platinum(IV) compound
with a five-membered exo-metallacycle followed by C–C bond
formation between the benzyl group of the imine ligand and one
of the para-tolyl ligands leading to a biaryl linkage. The subsequent
C–H activation does not take place at the biaryl system; instead,
a C–H bond of the benzylidene group is activated to produce
a five-membered endo-metallacycle with elimination of a toluene
Chart 1
Results and discussion
Initial work was carried out with bifunctional imine 2-
C6H4BrCH NCH2(2-BrC6H4) (1c) which contains bromo sub-
stituents on both benzylidene and benzyl rings. In the re-
action with cis-[Pt2(4-MeC6H4)4(m-SEt2)2] under the previously
reported conditions,6 only compound 2c containing an endo
seven-membered platinacycle could be isolated (see reaction (1)).
Compound 2c was characterised by usual techniques and its
NMR parameters are similar to those reported for analogous
seven-membered compounds.6 The molecular structure confirms
formation of a non-planar seven-membered metallacycle in which
the imine functionality and two aryl rings tilted 53.5(2)◦ from each
other are included. Bond lengths and angles are well within the
Scheme 2 Synthetic method (i): + 0.5 [Pt2(4-MeC6H4)4(m-SEt2)2] in
refluxing toluene or benzene for 4h; (ii): + PPh3 (1 : 1) in acetone at RT for
2 h.
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Fig. 1 Molecular structures of compounds showing 50% probability ellipsoids: (a): 2c; (b): 3d; (c): 3e; (d): 3h and (e): 3i.
molecule. The reaction of compound 2d with triphenylphosphine
in a 1 : 1 ratio produced derivative 3d which was characterized
cyclometallation step produced an endo-metallacycle. In view of
this result, imine 2,4,6-(CH3)3C6H2CH NCH2(2-BrC6H4) (1e)
was tested. The mesityl group was chosen in order to block
the ortho positions of the benzylidene group and to drive the
cyclometallation reaction towards the benzyl ring of the ligand.
As shown in Scheme 2, C–C bond formation does indeed take
place between the benzyl group of the imine ligand and one of the
para-tolyl groups leading to a biaryl linkage. However, in contrast
to previous results, the subsequent C–H bond activation does
not take place at an aromatic site but instead an aliphatic C–H
bond of the mesityl group is activated to produce a six-membered
endo-metallacycle (compound 2e). Due to the low stability of 2e,
the triphenylphosphine derivative 3e was also prepared and fully
characterised using one- and two-dimensional NMR techniques.
As reported in a previous communication,9 crystals of 3e, just good
enough for structure resolution, were obtained and the formation
of an aryl–aryl bond and of a six-membered platinacycle was
confirmed (Fig. 1). The resulting biaryl linkage is pointing away
from the platinum centre and the two phenyl rings are tilted
66.3(4)◦ from each other. As for 3d, the reaction with an excess of
phosphine does not produce cleavage of the metallacycle.
Ligand 2,4,6-(CH3)3C6H2CH NCH2(2-ClC6H4) (1f) was also
tested and produced an analogous reaction to that reported for
1e while ligand 2,4,6-(CH3)3C6H2CH NCH2C6H5 (1g) failed to
react. These results confirm that intramolecular oxidative addition
of the C–X bond (X = Br (1e) or Cl (1f)) to produce a platinum(IV)
metallacycle is required for the process to take place, and the
reaction does not proceed when there is not a C–X bond at
the ortho positions of the benzyl group as for 1g. On the other
hand, formation of a six-membered platinacycle through sp3 C–H
1
using one- (1H, 31P, 195Pt) and two-dimensional ({ H-1H}-COSY
1
and NOESY, { H-13C}-gHSQC) NMR spectroscopy. The molec-
ular structure shown in Fig. 1 confirmed formation of both a
five-membered endo-metallacycle and an aryl–aryl bond between
one of the para-tolyl ligands and the benzyl ring which are tilted
63.9(4)◦ from each other. The resulting biaryl linkage is pointing
away from the platinum centre in order to avoid steric crowding in
the coordination sphere. No further reaction, such as cleavage of
the metallacycle, took place when an excess of triphenylphosphine
was used and, in agreement with previous results for analogous
cyclometallated compounds, this result indicates high stability of
the metallacycle.12
For previously studied reactions usingcis-[PtCl2(dmso)2] as plat-
inum precursor and imines such as 2,6-C6H3Cl2CH NCH2Ph, it
has been reported that arene solvents such as benzene, toluene
or xylenes were involved as reagents in the biaryl formation.7b,d
However, for the precursor cis-[Pt2(4-MeC6H4)4(m-SEt2)2], it has
been confirmed that the tolyl group involved in the biaryl
formation arises exclusively from a tolyl ligand of the platinum
precursor, while the other tolyl ligand is eliminated as toluene
in the final cyclometallation step.6 In order to confirm that this
is also the case in the reaction of cis-[Pt2(4-MeC6H4)4(m-SEt2)2]
with imine 1d here reported, the reaction was also carried out in
benzene as solvent and it was confirmed that compound 2d was
exclusively formed.
The results obtained for the reaction with imine 1d indicated
that biaryl formation may take place at the saturated arm of the
N-benzylidenebenzylamine ligand, but, in spite of this, the final
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bond activation is remarkable, since a strong tendency to form
five- versus six membered rings, as well as a preference for the
activation of sp2 over sp3 C–H bonds, are generally observed in
cyclometallation reactions.13 In particular, platinacycles formed
through aliphatic C–H bond activation are uncommon.14 While
activation of a methyl C–H bond of a mesityl group with formation
of six membered metallacycles is well known at palladium,15 such
a process has not been observed in the reactions of imines 1d or
1e with platinum substrates cis-[PtCl2(dmso)2]16 or cis-[PtMe2(m-
SMe2)]2,11 which instead gave exo-metallacycles through activation
of aromatic C–H or C–Cl bonds.
formed, leaving the para-tolyl ring unchanged. The molecular
structure (Fig. 1) confirms the formation of both a five-membered
exo-metallacycle and a biaryl linkage involving the metallated ring
[tilt angle: 55.4(3)◦]. Bond lengths and angles are similar to those
obtained for five-membered endo-metallacycles 3d and 3h. The
sum of internal angles of the five-membered metallacycles is 530.7◦
which suggests a deviation from planarity, in contrast to the values
◦
◦
obtained for the endo-cycles 3d (539.4 ) and 3h (539.9 ) which
are close to 540◦, thus suggesting a planar arrangement.16,18 The
imine adopts a Z conformation which allows an intramolecular
˚
C(15)–H(15) ◊ ◊ ◊ Br interaction [d(C ◊ ◊ ◊ Br) = 3.289(6) A] involving
Our attention was then turned to imine 2-(CH3)C6H4CH
NCH2(2-BrC6H4) (1h) which contains just one methyl group in
the benzylidene group, so that competition between aromatic or
aliphatic C–H bond activation can be addressed. In this case,
upon reaction with cis-[Pt2(4-MeC6H4)4(m-SEt2)2], compound 2h
was formed exclusively and the corresponding mono-phosphine
derivative 3h was also obtained and characterised. As for 3d, the
molecular structure (Fig. 1) confirms the formation of both a five-
membered endo-metallacycle and a biphenyl moiety (tilt angle:
52.0(2)◦). In this case, the biaryl linkage is pointing towards the
bromo ligand as a result of the presence of a methyl substituent
in the ortho position and the planarity of the metallacycle. As
for imines 1d–1f, the process consists of initial C–X (X = Br or
Cl) bond activation, formation of a biaryl linkage and a final
cyclometallation step which, in this case, takes place at the sp2 C–
H bond exclusively. It is therefore concluded that activation of an
aromatic C–H bond is more favourable than that of an aliphatic
C–H bond, and that activation of either of these bonds leading to
an endo-metallacycle is more favourable than activation of an sp2
C–H bond leading to an exo-metallacycle, which was not observed
in these reactions.
Finally, the reaction of imine 2,6-F2C6H3CH NCH2(2-
BrC6H4) (1i) with cis-[Pt2(4-MeC6H4)4(m-SEt2)2] was tested with
the aim that the fluorine atoms could efficiently block the
cyclometallation at the benzylidene ring, and drive the reaction
towards formation of an exo-metallacycle. Although C–F acti-
vation at platinum(II) has been reported for analogous systems,
such a process is most favourable for polyfluorophenyl groups,
and is not expected for the 2,6-difluoroaryl group.17 Under the
conditions reported for imines 1d–1h, compound 2i was obtained
as a yellow oil, which could not be purified due to its low stability,
along with moderate amounts of metallic platinum. Further
reaction with triphenylphosphine led to the expected compound
3i, containing an exo-five-membered metallacycle (shown in
Scheme 2), along with formation of [PtBr(4-CH3C6H4)(PPh3)2] as
a minor component. In order to confirm that the toluene solvent
was not involved in the reaction, and in an attempt to reduce
the decomposition process—evidenced by formation of metallic
platinum—the reaction was also carried out in benzene, a solvent
with a lower boiling point. In this case, compound 3i was also
obtained and the yield was only slightly improved. Compound
3i was characterised using one- and two-dimensional NMR
techniques. A Z conformation of the imine bond, minimising
the steric effects around the platinum, is deduced based on the
position and coupling of the imine resonance (d = 9.79 [3J(H–
Pt) = 40.4 Hz]). The presence of an aromatic AB system, showing
cross-peak signals with the methyl and the CH2 resonances in
the NOESY experiment, indicates that a five-membered ring is
the imine group.
The reaction pathway shown in Scheme 3 is proposed for
the formation of compound 2i. Initial C–Br bond activation
produces a platinum(IV) derivative (intermediate A) and is
followed by reductive elimination with formation of an aryl–
aryl bond (intermediate B). Assuming that C–F activation is not
favoured, the final cyclometallation step could lead to either exo-
five- or exo-seven-membered platinacycles through aromatic C–H
bond activation (at positions indicated in Scheme 3 as a and b,
respectively). The results reported here reveal that the first option
is the most favoured and this can be related to the higher stability
generally reported for five-membered metallacycles.13 In contrast,
as reported in this work (compound 2d) and elsewhere6 formation
of a seven-membered metallacycle is favoured when the imine
moiety is included in the metallacycle (endo-cycles). Therefore, the
presence of the imine bond is decisive in the formation of seven-
membered platinacycles.
On the other hand, formation of [PtBr(4-CH3C6H4)(PPh3)2]—
arising from intermediate B—along with 3i in the reaction with
PPh3 can be taken as an indication that the final cyclometallation
step is slower than for the endo-metallacycles (2d, 2e, 2f and 2h).
In addition, formation of metallic platinum could indicate a lower
stability for 2i compared to the endo-metallacycles. However, the
reaction of 3i with an excess of PPh3 does not produce cleavage of
the metallacycle, as for the more stable endo-metallacycles 3d and
3e.
Conclusions
The results reported here indicate that intramolecular C–X
(X = Br or Cl) bond activation at the saturated arm of N-
benzylidene-benzylamines may promote, upon reaction with cis-
[Pt2(4-MeC6H4)4(m-SEt2)2], the formation of a biaryl linkage
between one of the tolyl ligands and the benzyl group of the imine
ligand. In contrast to initially reported reactions,6–8 the biaryl
linkage is not necessarily involved in the subsequent metallation
which leads to either endo-five (2d, 2h), endo-six- (2e, 2f) or exo-five
(2i) membered platinacycles.
The proposed reaction path outlined for 2i in Scheme 3 can be
considered a general route for all the reactions reported here. The
mechanism consists of: i) initial C–X (X = Br, Cl) bond activation
to produce a platinum(IV) derivative A, ii) reductive elimination
with formation of an aryl–aryl bond leading to intermediate B, iii)
a final cyclometallation step with elimination of a toluene molecule
arising from the tolyl ligand. The results here presented confirm
that formation of intermediate A is required, since when there is
not a C–X bond available for intramolecular oxidative addition
the reaction fails, as observed for 1g. In addition, formation of
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Scheme 3 Proposed reaction pathway for the formation of 2i and phosphine derivatives (i): Intramolecular C–Br bond activation; (ii): Reductive
elimination with formation of an aryl–aryl bond; (iii): Cyclometallation at the a position; (iv): Reaction with PPh3.
intermediate B allows cyclometallation at either the benzylidene
(1d, 1e, 1f and 1h) or the benzyl (1i) arms of the bifunctional
imine. In addition, the following trends in reactivity could be
deduced: Activation of an aromatic C–H bond is more favoured
than that of an aliphatic C–H bond as shown for imine 1h, and
activation of either of these bonds leading to an endo-metallacycle
is more favoured than activation of a sp2 C–H bond leading
to an exo-metallacycle, which was only achieved for imine 1i in
which two fluorine atoms block efficiently the ortho positions of
the benzylidene ring. These results can be related to the higher
stability of the endo versus exo-metallacycles (the so-called endo
effect) which allows to overcome the low tendency to form six-
membered rings and to activate a sp3 C–H bond as shown for
imines 1e and 1f.
In summary, platinum-mediated C–C coupling between a
coordinated para-tolyl group and the saturated arm of a N-
benzylidene-benzylamine can be achieved. In addition, the process
here reported produces several novel types of platinum(II) cy-
clometallated compounds containing a biaryl linkage: i) endo-five-
membered with a Pt–C(sp2) bond (2d–2h), ii) endo-six-membered
with a Pt–C(sp3) bond (2e–2f), and iii) exo-five membered with
a Pt–C(sp2) bond (2i). As a whole, the results here presented
expand the scope of a sequential intramolecular process in which
biaryl formation and cycloplatination take place in one pot via a
platinum(IV) intermediate.
Experimental section
General
Microanalyses were performed at the Serveis Cientifico-Te`cnics
(Universitat de Barcelona). Electrospray mass spectra were per-
formed at the Servei d’Espectrometria de Masses (Universitat de
Barcelona) in a LC/MSD-TOF spectrometer using H2O-CH3CN
1 : 1 to introduce the sample. NMR spectra were performed at
the Unitat de RMN d’Alt Camp de la Universitat de Barcelona
using Bruker DRX-250 (195Pt, 54 MHz), Varian Unity 300 (1H,
1
300 MHz; 31P-{ H}, 121.4 MHz; 19F, 282.4 MHz), Mercury-400
(1H, 400 MHz; 1H-1H-NOESY; 1H-1H-COSY; 1H-13C-gHSQC;
19F, 376.5 MHz) and Varian Inova DMX-500 (13C) spectrometers,
and referenced to SiMe4 (1H, 13C), H3PO4 (31P) and H2PtCl6 in D2O
(
195Pt). d values are given in ppm and J values in Hz. Abbreviations
used: s = singlet; d = doublet; t = triplet; m = multiplet; br = broad.
Preparation of the compounds
cis-[Pt2(4-MeC6H4)4(m-SEt2)2]19 and ligands 1c, 1e, 1f and
1g10,11,16,20 were prepared as reported elsewhere.
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Ligand 4-ClC6H4CH NCH2(2-BrC6H4) (1d). This ligand
was prepared from 0.30 g (1.35 mmol) of 2-bromobenzylamine
hydrochloride which was treated with 75 mg of KOH in water. The
mixture was extracted with diethyl ether, and the resulting organic
layer was treated with sodium sulphate, filtered and evaporated to
dryness. A solution of 0.19 g (1.35 mmol) of 4-chlorobenzaldehyde
in 20 mL of ethanol was added to the residue and the resulting
mixture was heated under reflux for 2 hours. The solvent was
removed in vacuo to produce a white solid. Yield 300 mg (72%).
1H NMR (400 MHz, CDCl3): d = 8.37 [s, 1H, CHN]; 7.73 [d,
3J(H–H) = 6.8, 2H, H1 or H2]; 7.57 [dd, J(H–H) = 7.6, 1.0, 1H,
H3]; 7.42 [m, H6]; 7.39 [d, 3J(H–H) = 6.8, 2H, H1 or H2]; 7.30 [td,
was heated for 4 hours under refluxing conditions. The solvent
was removed in a rotary evaporator to yield a red oil which could
not be purified due to its low stability. The reaction was also
carried out using benzene as a solvent and the same product was
1
obtained. H NMR (400 MHz, CDCl3): d = 7.73 [s, 1H, CHN];
3
5.40 [s, J(H–H) = 22.2, 2H, NCH2]; 3.36 [m, 2H, SCH2]; 2.98
[m, 2H, SCH2]; 2.38 [s, 3H, CH3]; 1.38 [t, J(H–H) = 8.0, 6H,
SCH2CH3].
Compound [PtBr{4-ClC6H3CH NCH2C6H4(4-CH3C6H4)}-
PPh3] (3d). This compound was obtained from 66 mg
(0.21 mmol) of imine 1d and 100 mg (0.11 mmol) of compound
cis-[Pt2(4-MeC6H4)4(m-SEt2)2] in 20 mL of toluene. The mixture
was heated for 4 hours under refluxing conditions. The solvent was
removed in a rotary evaporator and a solution of 56 mg of PPh3
(0.21 mmol) in 20 mL of acetone was added to the residue. After
stirring at room temperature for 2 hours, the solvent was removed
and the residue was recrystallised in dichloromethane/methanol
3
3J(H–H) = 7.6, 1.2, 1H, H4 or H5]; 7.14 [td, J(H–H) = 7.6, 1.2,
1H, H4 or H5]; 4.88 [s, 2H, CH2]. ESI-MS, m/z: 309.98 [M+H]+.
Ligand 2-MeC6H4CH NCH2(2-BrC6H4) (1h). This ligand
was prepared from ortho-tolualdehyde following the same proce-
dure as for 1d. Yield 250 mg (64.2%). 1H NMR (400 MHz, CDCl3):
3
4
1
d = 8.75 [s, 1H, CHN]; 7.95 [dd, J(H–H) = 7.6, J(H–H) = 1.2,
to produce a yellow solid. Yield: 126 mg (69%). H NMR (400
1H]; 7.57 [dd, 3J(H–H) = 8.0, 4J(H–H) = 1.2, 1H]; 7.45 [dd, 3J(H–
4
3
MHz, CDCl3): d = 7.91 [d, J(H–P) = 9.6, J(H–Pt) = 92, 1H,
CHN]; 7.75–7.71 [m, 6H, PPh3ortho]; 7.56–7.53 [m, 1H, H9];
7.44–7.42 [m, 3H, H6,7,8]; 7.37 [td, 3J(H–H) = 8.0, 4J(H–H) =
2.0, 9H, PPh3meta, para]; {7.22 [3J(H–H) = 8.0]; 7.19 [3J(H–H) =
8.0], 4H, AB system, H4,5}; 7.03 [d, 3J(H–H) = 8.0, 1H, H3]; 6.85
4
H) = 7.6, J(H–H) = 1.6, 1H]; 7.31 [m, 2H], 7.26 [m, 1H,]; 7.19
3
3
4
[d, J(H–H) = 7.6, 1H]; 7.13 [td, J(H–H) = 7.6, J(H–H) = 1.6,
1H]; 4.90 [s, 2H, CH2]; 2.53 [s, 3H, CH3]. ESI-MS, m/z: 290.04
[M+H]+.
3
4
4
[dd, J(H–H) = 8.0, J(H–H) = 2.0, 1H, H2]; 6.36 [t, J(H–H) =
2, 3JJ(H–Pt) = 55.6, 1H, H1]; 5.52 [br. s, 3J(H-Pt) ca. 20 Hz,
2H, CH2]; 2.38 [s, 3H, CH3]. 13C NMR (125.9 MHz, CDCl3):
Ligand 2,6-F2C6H3CH NCH2(2-BrC6H4) (1i). This ligand
was prepared from 2,6-difluorobenzaldehyde following the same
procedure as for 1d. Yield 320 mg (76.4%). 1H NMR (400 MHz,
CDCl3): d = 8.63 [s, 1H, CHN]; 7.57 [dd, 3J(H–H) = 8.0, 4J(H–H) =
2
2
d = 177.24 [s, J(C–Pt) = 84.6, CHN]; 148.38 [d, J(C–P) = 5.8,
1J(C–Pt) = 1103.4, C–Pt]; singlets at 144.96, 142.30, 137.68,
137.02, 130.53, 129.49 [aromatic carbon atoms]; 136.05 [d,
3
4
1.2, 1H, H3 or H6]; 7.46 [dd, J(H–H) = 7.6, J(H–H) = 1.6, 1H,
H3 or H6]; 7.36 [t, 3J(H–H) = 7.2, 1H, H2]; 7.32 [td, 3J(H–H) = 7.6,
4J(H–H) = 1.6, 1H, H4 or H5]; 7.14 [td, 3J(H–H) = 7.6, 4J(H–H) =
3J(C–P) = 5.7, J(C–Pt) = 96.0, C1]; 135.35 [d, J(C–P) = 11.3,
PPh3, Cortho]; singlets at 130.88; 130.86; 130.39; 130.04 [C6,7,8,9];
singlets at 129.18, 129.84 [C4,5]; 128.55 [s, C3]; 127.95 [d, 3J(C–P) =
2
2
3
3
1.6, 1H, H4 or H5]; 6.96 [t, J(H–F) = J(H–H) = 8.8, 2H, H1];
4.95 [s, 2H, CH2]. 19F NMR (376.5 MHz, CDCl3): d = -113.58 [t,
3J(H–F) = 7.5]; ESI-MS, m/z: 312.02 [M+H]+.
10.5, PPh3, Cmeta]; 127.72 [d, J(C–P) = 2.5, PPh3, Cpara]; 122.93
4
[s, C2]; 59.99 [s, J(C–Pt) = 35.0, CH2]; 21.21 [s, CH3]. 31P NMR
2
(121.4 MHz, CDCl3): d = 20.50 [s, 1J(P–Pt) = 4107.7]. 195Pt NMR
Compound [PtBr{2-CH3C6H3C6H4CH NCH2(2-C6H4Br)}-
SEt2](2c). This compound was obtained from76mg(0.21 mmol)
of imine 1c and 100 mg (0.11 mmol) of compound cis-[Pt2(4-
MeC6H4)4(m-SEt2)2] in 20 mL of toluene. The mixture was heated
for 4 hours under refluxing conditions. Insoluble materials were
filtered off, the solvent was removed in a rotary evaporator and
the residue was recrystallised in CH2Cl2/CH3OH to yield white
1
(54 MHz, CDCl3): d = -4243.0 [d, J(P–Pt) = 4131.5]. ESI-MS,
m/z: 776.17 [M-Br]+. Anal. calc. for C39H32BrClNPPt·H2O: C:
53.58; H: 3.92; N: 1.60%. Found: C: 53.3; H: 3.6; N: 1.7%.
Compound
[PtBr{CH2C6H2 (CH3 )2CH NCH2C6H4 (4-
CH3C6H4)}SEt2] (2e). This compound was obtained from
68 mg (0.21 mmol) of imine 1e using the same procedure as for 2d.
A yellow oil which could not be purified due to its low stability
1
crystals. Yield: 90 mg (58%). H NMR (400 MHz, CDCl3): d =
3
4
8.70 [d, J(H–Pt) = 119.6, J(H–H) = 1.6, 1H, CHN]; 7.99 [dd,
1
3J(H–H) = 7.2, 4J(H–H) = 1.6, 1H, H7]; 7.48–7.45 [m, 1H];
was obtained. H NMR (400 MHz, CDCl3): d = 8.23 [s, br., 1H,
CHN]; {7.39 [m, 3H]; 7.23 [m, 1H]; 7.14 [m, 4H]; 6.72 [s, 1H, H1
or H2]; 6.57 [s, 1H, H1 or H2], aromatics}; 5.56 [s, 3J(H–Pt) = 27.2,
2H, NCH2]; 3.10 [m, 2H, SCH2]; 2.70 [m, 2H, SCH2]; 2.35 [s, 3H,
3
4
7.41–7.35 [m, 3H]; 7.30 [dd, J(H–H) = 8.0; J(H–H) = 1.2, 2H];
3
4
3
7.23 [td, J(H–H) = 7.6, J(H–H) = 1.6, 1H]; 6.81 [d, J(H–H) =
7.6, 1H, H3]; 6.71 [dd, J(H–H) = 7.6, J(H–H) = 1.2, 1H, H2];
3
4
c
a,b
5.96 [d, 3J(H–Pt) = 55.2, 4J(H–H) = 1.0, 1H, H1]; 5.76 [dd,
CH3 ]; 2.32 [m, 2H, CH2Pt]; {2.18 [s, 3H]; 1.92 [s, 3H], CH3 };
1.24 [t, 3J(H–H) = 7.2, 6H, SCH2CH3].
2J(H–H) = 12.4; J(H–H) = 2.0, 1H, CH2N]; 4.99 [d, J(H–H) =
4
2
3
12.4, J(H–Pt) = 57.6, 1H, CH2N]; {3.01 [s, br, 1H]; 2.66 [s, br,
Compound
[PtBr{CH2C6H2 (CH3 )2CH NCH2C6H4 (4-
2H]; 2.38 [s, br, 1H], SCH2}; 2.08 [s, 3H, CH3]; 1.19 [s, br., 3H,
SCCH3]; 0.92 [s, br., 3H, SCCH3]. ESI-MS, m/z: 648.55 [M-Br]+.
Anal. calc. for C25H27Br2NSPt: C: 41.22; H: 3.73; N: 1.92; S:
4.40%. Found: C: 41.3; H: 3.9; N: 2.2; S: 4.3%.
CH3C6H4)}PPh3] (3e). This compound was obtained from
68 mg (0.21 mmol) of imine 1e using the same procedure as for 3d.
After partial removal of the solvent, yellow crystals were formed.
1
Yield: 97 mg (54%). H NMR (400 MHz, CDCl3): d = 8.30 [br.
Compound [PtBr{4-ClC6H3CH NCH2C6H4(4-CH3C6H4)}-
SEt2] (2d). This compound was obtained from 66 mg
(0.21 mmol) of imine 1d and 100 mg (0.11 mmol) of compound
cis-[Pt2(4-MeC6H4)4(m-SEt2)2] in 20 mL of toluene. The mixture
m, 1H, CHN]; 7.57–7.52 [m, 6H, PPh3ortho]; 7.49–7.47 [m, 2H];
7.40–7.31 [m, 11H, PPh3 meta, para + 2H]; {7.16 [3J(H–H) = 8.0]; 7.13
[3J(H–H) = 8.0], 4H, AB system, H3,4}; 6.51 [s, 1H, H2]; 5.67 [d,
4J(H–H) = 2.0, 3J(H–Pt) = 32.0, 2H, CH2N]; 5.62 [s, 1H, H1]; 2.35
9436 | Dalton Trans., 2011, 40, 9431–9438
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[s, 3H, CH3 ]; 2.06 [d, 4J(H–P) = 4.0, 3J(H–Pt) = 96.0, CH2Pt]; 2.02
31P NMR (121.4 MHz, CDCl3): d = 18.54 [s, J(P–Pt) = 4482.1].
ESI-MS, m/z: 783.26 [M–Cl]+. Anal. calc. for C42H39ClNPPt: C:
61.57; H: 4.80; N: 1.71%. Found: C: 61.3; H: 5.3; N: 2.0%.
c
b
a
[s, 3H, CH3 ]; 1.92 [s, 3H, CH3 ]. 13C NMR (125.9 MHz, CDCl3):
d = 160.27 [s, CHN]; singlets at 145.10, 142.99, 141.63, 138.22,
137.84, 136.95, 133.11, 130.97, 130.49 [aromatic carbon atoms];
Compound [PtBr{2-CH3C6H3CH NCH2C6H4(4-CH3C6H4)}-
SEt2] (2h). This compound was obtained from 62 mg
(0.21 mmol) of imine 1h using the same procedure as for 2d using
toluene as a solvent. An orange oil which could not be purified
due to its low stability was obtained. 1H NMR (400 MHz, CDCl3):
2
4
134.86 [d, J(C–P) = 11.0, PPh3, Cortho]; 130.16 [d, J(C–P) = 2.0,
PPh3, Cpara]; 129.15 [s, C3,4]; 127.75 [d, 3J(C–P) = 11.0, PPh3, Cmeta];
singlets at 130.06; 129.95; 128.04; 127.42 [C5,6,7,8]; 126.80 [s, C2];
125.37 [s, C1]; 63.77 [s, NCH2]; 21.36 [s, CH3 ]; 21.07 [s, CH3 ];
b
c
a
1
18.40 [CH3 ]; 14.70 [d, J(C–P) = 4.0, J(C–Pt) = 630.0, CH2Pt].
31P NMR (121.4 MHz, CDCl3): d = 19.09 [s, J(P–Pt) = 4484.5].
195Pt NMR (54 MHz, CDCl3): d = -4266.3 [d, J(P–Pt) = 4474.0].
HR-ESI-MS, m/z: 783.2458, calculated for C42H39NPPt [M-Br]
783.2462; 824.2721, calculated for C44H42N2PPt [M-Br+CH3CN]
824.2727. Anal. calc for C42H39BrNPPt·CH2Cl2: C: 54.44; H: 4.35;
N: 1.48%. Found: C: 54.2; H: 4.2; N: 1.6%.
3
d = 8.05 [s, J(H–Pt) = 124.8, 1H, CHN]; {7.64 [m, 1H]; 7.43 [d,
3J(H–H) = 7.8, 1H]; 7.33 [m, 2H]; 7.26 [m, 4H], 7.17 [t, 3J(H–H) =
7.2, 1H]; 7.04 [t, 3J(H–H) = 7.8, 1H], 6.77 [d, 3J(H–H) = 7.8, 1H],
3
aromatics}; 5.45 [s, J(H–Pt) = 27.3, 2H, NCH2]; 3.38 [m, 2H,
SCH2]; 2.95 [m, 2H, SCH2]; 2.38 [s, 3H, CH3]; 2.29 [s, 3H, CH3];
1.36 [t, 3J(H–H) = 7.5, 6H, SCH2CH3].
Compound [PtBr{2-CH3C6H3CH NCH2C6H4(4-CH3C6H4)}-
PPh3] (3h). This compound was obtained from 62 mg
(0.21 mmol) of imine 1h using the same procedure as for 3d. After
partial removal of the solvent, yellow crystals were formed. Yield:
Compound
[PtCl{CH2C6H2(CH3)2CH NCH2C6H4(4-CH3-
C6H4)}PPh3] (3f). This compound was obtained as yellow
crystals from 58 mg (0.21 mmol) of imine 1f using the same
1
1
4
procedure as for 3d. Yield: 110 mg (63%). H NMR (400 MHz,
135 mg (75%). H NMR (400 MHz, CDCl3): d = 8.30 [d, J(H–
3
CDCl3): d = 8.26 [s, br., m, 1H, CHN]; 7.58–7.53 [m, 6H]; 7.46 [m,
P) = 9.6, J(H–Pt) = 94, 1H, CHN]; 7.77–7.72 [m, 6H, PPh3ortho];
2H]; 7.40–7.30 [m, 11H]; 7.14 [m, 4H]; 6.52 [s, 1H, H2]; 5.71 [s, 1H,
7.64 [dd, 3J(H–H) = 6.8, 4J(H–H) = 2.4, 1H]; 7.40–7.34 [m, 12H,
H1]; 5.59 [d, 4J(H–H) = 2.0, 2H, CH2N]; 2.35 [s, 3H, CH3 ]; 2.05
PPh3
+ 3H]; {7.27 [3J(H–H) = 8.4]; 7.21 [3J(H–H) = 8.4],
c
meta, para
[d, 4J(H–P) = 4.0, CH2Pt]; 2.04 [s, 3H, CH3 ]; 1.93 [s, 3H, CH3 ].
4H, AB system, H4,5}; 6.60 [d, J(H–H) = 7.2, 1H, H3]; 6.42 [t,
b
a
3
˚
Table 1 Selected bond lengths (A) and angles (deg.) for compounds 2c, 3d, 3e, 3h and 3i with estimated standard deviations
Compound 2c
Compound 3d
Compound 3e
Compound 3h
Compound 3i
Pt–C(1)
Pt–S
Pt–N(1)
Pt–Br(1)
C(1)–Pt–N(1) 86.22(15)
C(1)–Pt–S 88.60(11)
N(1)–Pt–Br(1) 90.09(11)
S–Pt–Br(1) 95.09(4)
1.994(4)
Pt(1)–C(20)
2.071(6)
Pt–C(22)
1.988(6)
Pt–C(1)
2.048(3)
2.2477(11) Pt–P
2.094(3)
2.4994(10) Pt–Br
80.68(12)
95.15(10)
90.63(8)
93.51(4)
Pt–C(1)
2.041(5)
2.2386(16)
2.055(4)
2.2746(14) Pt(1)–P(1)
2.025(3) Pt–N(1)
2.5732(12) Pt–Br(1)
C(20)–Pt(1)–N(1) 80.1(2)
C(20)–Pt(1)–P(1) 95.53(16)
N(1)–Pt–Br(1) 93.27(15)
P(1)–Pt(1)–Br(1) 91.65(5)
2.2427(16) Pt–P
2.090(5) Pt–N
2.5021(11) Pt–Br
2.1801(16) Pt–P
2.055(4) Pt–N
2.4417(10) Pt–Br
Pt–N(1)
2.5017(13)
C(22)–Pt–N
C(22)–Pt–P
N–Pt–Br
86.8(2)
C(1)–Pt–N
C(1)–Pt–N(1) 81.4(2)
90.32(17)
87.73(13)
95.11(5)
C(1)–Pt–P
N–Pt–Br
P–Pt–Br
C(1)–Pt–P
N(1)–Pt–Br
P–Pt–Br
96.14(16)
87.53(12)
93.16(5)
P–Pt–Br
Table 2 Crystallographic and refinement data for compounds 2c, 3d, 3e, 3h and 3i
Compound 2c
Compound 3d
Compound 3e
Compound 3h
Compound 3i
Formula
C25H27Br2NPtS
C39H32BrClNPPt
C42H39BrNPPt·H2O
C40H35BrNPPt
C39H31BrF2NPPt·0.5
CH2Cl2·H2O
918.10
Fw
728.45
856.08
881.73
835.66
Temp, K
293(2)
0.71073
Triclinic
P-1
10.039(4)
10.075(6)
12.819(5)
90.85(2)
103.59(3)
90.42(3)
1260.0 (10); 2
1.920
8.834
696
13491/6984
[R(int) = 0.0435]
6984/0/272
1.129
0.0310
0.0934
1.250 and -1.040
173(2)
293(2)
0.71073
Triclinic
P-1
12.032(5)
12.230(4)
12.715(3)
81.08(2)
72.52(2)
79.01(2)
1742.3(10); 2
1.681
5.254
872
16366/8758
[R(int) = 0.0627]
8758/2/435
1.087
0.0550
0.1579
1.802 and -2.558
173(2)
173(2)
0.71073
Triclinic
P-1
˚
Wavelength, A
Crystal system
Space group
0.71073
Monoclinic
P21/c
21.026(8)
7.879(5)
21.075(8)
90
108.56(2)
90
3310(3); 4
1.718
5.605
1672
27088/9183
[R(int) = 0.0748]
9183/1/399
1.090
0.71073
Triclinic
P-1
˚
a, A
9.683(5)
9.885(4)
17.635(7)
85.59(2)
82.01(2)
82.75(2)
1655.2(13); 2
1.677
5.523
820
16162/8611
[R(int) = 0.0446]
8611/2/400
1.125
9.508(4)
˚
b, A
11.237(4)
18.529(6)
81.01(3)
82.46(2)
76.34(3)
1890.8(12);2
1.613
4.920
˚
c, A
a, deg
b, deg
g , deg
˚
V, A3; Z
d (calcd), Mg/m3
Abs coeff, mm-1
F(000)
898
Rflns coll./unique
16933/9453
[R(int) = 0.0587]
9453/1/453
1.080
0.0520
0.1526
Data/restraint/parameters
GOF on F2
R1(I>2s(I))
wR2 (all data)
Peak and hole, e.A
0.0563
0.1659
2.829 and -0.909
0.0344
0.0927
2.138 and -1.164
-3
˚
2.114 and -1.466
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Dalton Trans., 2011, 40, 9431–9438 | 9437
©

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3J(H–H) = 7.6, 1H, H2]; 6.33 [dd, 3J(H–H) = 7.6, 4J(H–P) = 3.2,
1H, H1]; 5.58 [d, 4J(H–P) = 3.6, 3J(H–Pt) = 15.0, 2H, CH2]; 2.38
[s, 3H, CH3]; 2.30 [s, 3H, Me]. 31P NMR (121.4 MHz, CDCl3): d =
22.85 [s, J(P–Pt) = 4169.7]. ESI-MS, m/z: 755.21, [M-Br]. Anal.
calc. for C40H35BrNPPt: C: 57.49; H: 4.22; N: 1.68%. Found: C:
57.8; H: 4.4; N: 1.7%.
refined using a riding model with an isotropic temperature 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.
Acknowledgements
We thank the Ministerio de Ciencia y Tecnolog´ıa (project
CTQ2009-11501) for financial support.
Compound
[PtBr{C6H3(4-CH3C6H4)CH2N CH(2,6-C6H3-
F2)}SEt2] (2i). This compound was obtained from 66 mg
(0.21 mmol) of imine 1i using the same procedure as for 2d in
toluene. In this case, a moderate amount of metallic platinum was
filtered off prior to solvent removal. A yellow oil which could not
be purified due to its low stability was obtained. An analogous
result was obtained when the reaction was carried out in benzene.
1H NMR (300 MHz, CDCl3): d = 8.71 [s, 1H, CHN]; 5.21 [s,
3J(H–Pt) = 30.0, 2H, NCH2]; 3.28 [m, 2H, SCH2]; 2.85 [m, 2H,
SCH2]; 2.41 [s, 3H, CH3]; 1.39 [t, 3J(H–H) = 7.5, 6H, SCH2CH3].
19F NMR (282.4 MHz, CDCl3): d = -107.54 [t, 3J(H–F) = 8.5].
References
1 R. F. Heck and J. P. Nolley Jr, J. Org. Chem., 1972, 37, 2320–2322.
2 E.-I. Negishi, A. O. King and N. Okukado, J. Org. Chem., 1977, 42,
1821–1823.
3 N. Miyaura and A. Suzuki, J. Chem. Soc., Chem. Commun., 1979,
866–867.
4 (a) D. Alberico, M. E. Scott and M. Lautens, Chem. Rev., 2007, 107,
174–238; (b) G. P. Mc Glacken and L. M. Bateman, Chem. Soc. Rev.,
2009, 38, 2447–2464.
5 A. J. Canty, Dalton Trans., 2009, 10409–10417.
6 R. Mart´ın, M. Crespo, M. Font-Bardia and T. Calvet, Organometallics,
2009, 28, 587–597.
Compound
[PtBr{C6H3(4-CH3C6H4)CH2N CH(2,6-C6H3-
F2)}PPh3] (3i). This compound was obtained from 66 mg
(0.21 mmol) of imine 1i using the same procedure as for 2d. In
this case, a moderate amount of metallic platinum was filtered
off prior to solvent removal. Recrystallisation in CH2Cl2/MeOH
mixtures led to [PtBr(4-CH3C6H4)(PPh3)2] (ca. 10 mg) which was
filtered off; further crystallisation produced a white-yellow solid
(3i). Yield: 61 mg (33%). When the reaction was carried out in
benzene the yield was 72 mg (39%). 1H NMR (400 MHz, CDCl3):
7 (a) M. Crespo, M. Font-Bard´ıa and X. Solans, Organometallics, 2004,
23, 1708–1713; (b) A. Capape´, M. Crespo, J. Granell, A. Vizcarro, J.
Zafrilla, M. Font-Bardia and X. Solans, Chem. Commun., 2006, 4128–
4130; (c) M. Font-Bard´ıa, C. Gallego, M. Mart´ınez and X. Solans,
Organometallics, 2002, 21, 3305–3307; (d) J. Albert, R. Bosque, M.
Crespo, J. Granell, J. Rodriguez and J. Zafrilla, Organometallics, 2010,
29, 4619–4627.
8 T. Calvet, M. Crespo, M. Font-Bardia, K. Go´mez, G. Gonza´lez and
M. Mart´ınez, Organometallics, 2009, 28, 5096–5106.
9 Part of this work appeared in a preliminary communication: M. Crespo,
T. Calvet and M. Font-Bardia, Dalton Trans., 2010, 39, 6936–6938.
10 P. W. Clark, S. F. Dyke, G. Smith and C. H. L. Kennard, J. Organomet.
Chem., 1987, 330(3), 447–460.
d = 9.79 [d, 4J(H–P) = 6.0, 3J(H–Pt) = 40.4, 1H, CHN]; 7.87–7.45
[m, 6H, PPh3ortho]; 7.44–7.38 [m, 10H, PPh3
+ 1HAr]; {7.14
meta, para
[3J(H–H) = 8.0]; 7.08 [3J(H–H) = 8.0], 4H, AB system, H6,7};
11 M. Crespo, M. Mart´ınez and J. Sales, Organometallics, 1992, 11, 1288–
1295.
3
3
6.90 [t, J(H–F) = 8.4, 2H, H1]; 6.80 [d, J(H–H) = 7.2, 1H];
6.54 [m, 1H]; 6.45 [t, 3J(H–H) = 7.6, 1H, H2]; 4.97 [s, 3J(H–Pt) =
12 (a) O. Lo´pez, M. Crespo, M. Font-Bard´ıa and X. Solans,
Organometallics, 1997, 16, 1233–1240; (b) M. Crespo, X. Solans and
M. Font-Bard´ıa, Organometallics, 1995, 14, 355–364.
13 For a recent review on cyclometallation using d-block transition metals,
see: M. Albrecht, Chem. Rev., 2010, 110, 576–623.
14 (a) S. H. Crosby, G. J. Clarkson and J. P. Rourke, J. Am. Chem. Soc.,
2009, 131, 14142–14143; (b) A. Zucca, S. Stoccoro, M. A. Cinellu, G.
Minghetti, M. Manassero and M. Sansoni, Eur. J. Inorg. Chem., 2002,
3336–3346; (c) A. W. Garner, C. F. Harris, D. A. K. Vezzu, R. D. Pyke
and S. Huo, Chem. Commun., 2011, 47, 1902–1904; (d) S. H. Crosby,
R. J. Deeth, G. J. Clarkson and J. P. Rourke, Dalton Trans., 2011, 40,
1227–1229.
15 See for instance: (a) J. Albert, J. Granell, J. Sales, X. Solans and M.
Font-Altaba, Organometallics, 1986, 5, 2567–2568; (b) J. Albert, R. M.
Ceder, M. Gomez, J. Granell and J. Sales, Organometallics, 1992, 11,
1536–1541; (c) R. Bosque, C. Lo´pez, J. Sales, D. Tramuns and X. Solans,
J. Chem. Soc., Dalton Trans., 1995, 2445–2452; (d) C. L. Chen, Y. H.
Liu, S. M. Peng and S. T. Liu, Tetrahedron Lett., 2005, 46, 521–523;
(e) J. Albert, J. M. Cadena, A. Gonzalez, J. Granell, X. Solans and M.
Font-Bardia, Chem.–Eur. J., 2006, 12, 887–894.
25.0, 2H, CH2]; 2.32 [s, 3H, CH3]. gHSQC-{ H,13C} NMR (1H:
1
400 MHz, CDCl3): d (13C) = 160.73 [CHN]; {136.31; 133.65;
125.53; 125.05, C2,3,4,5};135.54 [PPh3, Cortho]; 130.59 [PPh3, Cmeta];
{128.51; 128.93, C6,7}; 127.91 [PPh3, Cpara]; 111.99 [C1]; 66.83
[CH2]; 20.89 [CH3]. 19F NMR (376.5 MHz, CDCl3): d = -106.34
3
[t, J(H–F) = 8.4]. 31P NMR (121.4 MHz, CDCl3): d = 20.35 [s,
1J(P–Pt) = 4285.3]. 195Pt NMR (54 MHz, CDCl3): d = -4045.6 [d,
1J(P–Pt) = 4303.3]. ESI-MS, m/z: 777.18 [M-Br]+. Anal. calc.
C39H31BrF2NPPt·CH2Cl2: C: 50.97; H: 3.53; N: 1.49%. Found: C:
50.8; H: 3.5; N: 1.1%.
X-ray structure analysis
Prismatic crystals were selected and mounted on a MAR345
diffractometer with an image plate detector. Intensities were
collected with graphite monochromatized Mo Ka radiation. The
structures were solved by direct methods using SHELXS computer
program21 and refined by the full-matrix least-squares method,
with the SHELXL97 computer program using 6984 (2c), 27088
(3d), 16366 (3e), 16162 (3h) and 16933 (3i) reflections (very negative
intensities were not assumed). The function minimized was R w |
16 A. Capape´, M. Crespo, J. Granell, M. Font-Bardia and X. Solans,
Dalton Trans., 2007, 2030–2039.
17 C. M. Anderson, M. Crespo, G. Ferguson, A. J. Lough and R. J.
Puddephatt, Organometallics, 1992, 11, 1177–1181.
18 H. F. Klein, S. Camadanli, R. Beck and D. Leukel, Angew. Chem., Int.
Ed., 2005, 44, 975–977.
19 B. R. Steele and K. Vrieze, Transition Met. Chem., 1977, 2, 140–
144.
|Fo|2 - |Fc|2 |2, where w = [s (I) + (0.0447 P)2 + 0.2738 P]-1 (2c),
2
20 M. Font-Bardia, C. Gallego, G. Gonzalez, M. Mart´ınez, A. E. Merbach
and X. Solans, Dalton Trans., 2003, 1106–1113.
2
2
w = [s (I) + (0.0717 P)2 + 1.3414 P]-1 (3d), w = [s (I) + (0.0995
P)2 + 2.9343 P]-1 (3e), w = [s (I) + (0.0592 P)2+ 0.2478 P]-1 (3h)
2
21 G. M. Sheldrick, SHELXS97,
A Computer Program for Crys-
tal Structure Determination, University of Go¨ttingen, Germany,
1997.
2
or w = [s (I) + (0.0810 P)2 + 2.0463 P]-1 (3i) and P = (|Fo|2 +
2|Fc|2)/3. f , f ¢ and f ¢¢ were taken from International Tables of
22 International Tables of X-Ray Crystallography, Vol.IV, Kynoch Press,
X-ray crystallography.22 All hydrogen atoms were computed and
Birmingham, UK, (1974) pp 99–100, 149.
9438 | Dalton Trans., 2011, 40, 9431–9438
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The Royal Society of Chemistry 2011
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