Synthesis and molecular structures of platinum(II) and platinum(IV) diimine complexes possessing fluoroalkyl ligands

Article abstract of DOI:10.1139/v03-117

A range of Pt-diimine complexes possessing fluoroalkyl and hydrofluoroalkyl ligands were synthesized from the readily prepared [Pt(diimine)Me₂] complexes and the appropriate iodofluoroalkane. For complexes with diimine ligands containing substituents in the 2,6-positions of the aryl group, Pt(II) complexes were obtained due to in situ reductive elimination of MeI, while for complexes with diimine ligands of smaller steric demands (possessing substituents in the 3,5-positions or the 4-position), Pt(IV) complexes were obtained. Attempts to convert the Pt(IV) complexes to the desired Pt(II) species via reductive elimination of MeI, methane, or ethane resulted in either no reaction or degradation of the starting complex. Fluoroalkyl(methyl)platinum(II) complexes were then converted to the fluoroalkyliodoplatinum(II) complexes via addition of I₂ or by reaction with aq HI. Several complexes have been characterized crystallographically.

Full text of DOI:10.1139/v03-117

1270
Synthesis and molecular structures of platinum(II)
and platinum(IV) diimine complexes possessing
fluoroalkyl ligands1
Russell P. Hughes, Antony J. Ward, Arnold L. Rheingold, and Lev N. Zakharov
Abstract: A range of Pt-diimine complexes possessing fluoroalkyl and hydrofluoroalkyl ligands were synthesized from
the readily prepared [Pt(diimine)Me2] complexes and the appropriate iodofluoroalkane. For complexes with diimine lig-
ands containing substituents in the 2,6-positions of the aryl group, Pt(II) complexes were obtained due to in situ
reductive elimination of MeI, while for complexes with diimine ligands of smaller steric demands (possessing substitu-
ents in the 3,5-positions or the 4-position), Pt(IV) complexes were obtained. Attempts to convert the Pt(IV) complexes
to the desired Pt(II) species via reductive elimination of MeI, methane, or ethane resulted in either no reaction or deg-
radation of the starting complex. Fluoroalkyl(methyl)platinum(II) complexes were then converted to the
fluoroalkyliodoplatinum(II) complexes via addition of I2 or by reaction with aq HI. Several complexes have been char-
acterized crystallographically.
Key words: fluoroalkyl, organometallic synthesis, structure, platinum.
Résumé : Utilisant comme produit de départ des iodofluoroalcanes appropriés et des complexes [Pt(diimine)Me2] qui
peuvent facilement être préparés, on a préparé un éventail de complexes Pt-diimine portant des ligands fluoroalkyles et
hydrofluoroalkyles. Pour les complexes avec des ligands diimines portant des substituants dans les positions 2,6 du
groupe aryle, on a obtenu des complexes de Pt(II) en raison d’une élimination réductrice in situ de MeI alors qu’on a
obtenu des complexes de Pt(IV) avec pour les complexes avec des ligands diimines dont les demandes stériques sont
plus faibles (qui portent des substituants dans les positions 4 ou 3,5). Des essais en vue de transformer les complexes
de Pt(IV) en espèces Pt(II) désirées par le biais d’une élimination réductrice de MeI, de méthane ou d’éthane n’ont pas
donné de réaction ou une dégradation du complexe de départ. Les complexes fluoroalkyl(méthyl)platine(II) ont ensuite
été transformés en complexes fluoroalkyliodoplatine(II) par le biais d’une addition de I2 ou par une réaction avec du
HI aqueux. Plusieurs complexes ont été cristallisés par diffraction des rayons X.
Mots clés : fluoroalkyle, organométallique, synthèse, structure, platine.
[Traduit par la Rédaction] Hughes et al. 1279
Introduction
alkylation at ligand sites rather than at the metal center in
both early and late transition metals (19–22).
Much recent work within our research group has focussed
upon the synthesis of late transition metal–fluoroalkyl com-
plexes, particularly those of metals from groups 9 (1–9) and
10 (10–12), utilizing oxidative addition of iodoperfluoro-
alkanes (11). While many such complexes have been synthe-
sized previously using oxidative addition reactions (13–18),
we have shown that such a route can often lead to fluoro-
There have been many studies of oxidative addition of
alkyl halides to square-planar Pt(II) precursors (23–27). In
the majority of cases, the reaction of bromo- and iodo-
alkanes with dimethylplatinum(II) complexes occurs via a
polar SN2 mechanism to give a Pt(IV) complex with kineti-
cally controlled trans stereochemistry (23), although subse-
quent isomerization has been shown in some cases to afford
the cis product (28). On occasion, cationic five-coordinate
intermediates have been detected spectroscopically (29).
These five-coordinate species in the oxidative addition reac-
tion have also been shown to serve as key intermediates for
reductive elimination of methyl iodide or ethane from Pt(IV)
(30–32).
The oxidative addition reactions of iodofluoroalkanes to
transition metals is unlikely to proceed via polar SN2 attack
by the metal at carbon due to the unfavourable polarity of
the Cδ–—Iδ+ bond (33, 34). In previous systems involving re-
actions of primary iodoperfluoroalkanes, we have postulated
that the reactions proceeded via electron transfer to the iodo-
fluoroalkane, followed by rapid loss of iodide from the
Received 5 March 2003. Published on the NRC Research
Press Web site at http://canjchem.nrc.ca on 20 October 2003.
R.P. Hughes2 and A.J. Ward. Departments of Chemistry,
6128 Burke Laboratory, Dartmouth College, Hanover, NH
03755, U.S.A.
A.L. Rheingold and L.N. Zakharov. Department of
Chemistry and Biochemistry, University of California, San
Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, U.S.A.
1This article is part of a Special Issue dedicated to Professor
John Harrod.
2Corresponding author (e-mail: rph@dartmouth.edu).
Can. J. Chem. 81: 1270–1279 (2003)
doi: 10.1139/V03-117
© 2003 NRC Canada

Hughes et al.
1271
resultant radical anion, and very fast trapping of the fluoro-
alkyl radical at the metal (21, 22).
addition products proved unsuccessful due to the very simi-
lar solubilities exhibited by the starting materials, free
diimine ligand, and the oxidative addition products. The
subsequent choice of ethyl acetate was based solely upon its
slightly lower boiling point as compared to benzene, as pre-
vious experience within our research group has shown that
certain oxidative addition reactions can be very temperature
dependent (46). It may also have proven to be a fortuitous
choice for a reaction that may proceed via a fluoroalkyl radi-
cal, since electrostatic repulsion of the oxygen atoms of the
ethyl acetate has been shown to significantly inhibit hydro-
gen atom abstraction by fluoroalkyl radicals when compared
with rates of abstraction from alkanes (47), thereby perhaps
increasing the yield of organometallic product.
While most studies of oxidative addition – reductive elim-
ination to Pt(II) centers have involved complexes bearing
monodentate or bidentate phosphorus ligands, complexes
with chelating nitrogen ligands have also been examined
(23). cis-Dialkyl- and -diarylplatinum(II) complexes with
nitrogen donor ligands usually react with alkyl halides to
afford the trans oxidative addition product (35–38). The cor-
responding cis-isomer can be formed either by a competitive
cis oxidative addition pathway, or by trans oxidative addition
with subsequent isomerization of the platinum(IV) product
to a thermodynamically more stable cis-isomer (23).
Dimethylplatinum(II) complexes possessing pyridine (35),
2,2′-bipyridine (39), 1,10-phenanthroline (39, 40), bis(p-
tolylimino)acenaphthene (41), bis(phenylimino)camphane
(41), various diimine ligands (42, 43), and tetramethylethyl-
enediamine (tmeda) (44, 45) have been studied.
The Pt(IV) species obtained were invariably those in
which the perfluoroalkyl moiety was mutually trans to the
iodo ligand, giving rise to complexes with Cs symmetry, as
shown for complexes 3, 4, and 6. The 19F NMR spectrum of
3 reveals two resonances for the m-CF3 groups of the di-
imine ligand indicating that there is no free rotation about
the N-aryl bonds on the NMR timescale. However, the
19F NMR spectrum of 4 reveals only one resonance for the
m-CF3 groups of the diimine ligand indicating apparently
free rotation of the aryl moiety, or an accidental equivalence
of CF3 resonances. In the case of 5, the presence of a stereo-
center at the α-C of the fluoroalkyl group results in a com-
We have previously reported on the reactions of
[Pt(tmeda)Me2] with fluoroalkyl iodides to give Pt(IV) and
Pt(II) fluoroalkyl complexes (11). Here we report on the cor-
responding reactions of dimethylplatinum(II) complexes
bearing diimine ligands.
Results and discussion
1
plex with C1 symmetry. This is highlighted clearly in the H
Synthesis
NMR spectrum of this complex in which the Pt-bound
methyl groups, the CH3 groups of the diimine backbone, and
the m-CF3 substituents of the aryl rings display nonequiva-
lence (two of which are coincident), indicating that rotation
of the aryl rings is slow on the NMR timescale.
In contrast to the very facile oxidative addition reactions
of [Pt(tmeda)Me2] with fluoroalkyl iodides (11), the corre-
sponding reactions of the [Pt(diimine)Me2] complexes 1 and
2 required heating at reflux in ethyl acetate to afford the
fluoroalkyl Pt(IV)–diimine complexes 3–6 (Scheme 1). To
reduce the possibility of light-induced radical chemistry of
the fluoroalkyl iodides, the reactions were performed in the
dark, although no attempts were made to evaluate whether
light actually does cause problems in these cases. When
[Pt(diimine)Me2] complexes 7 and 8 were used, which pos-
sess a diimine ligand containing a 2,6-dimethylaryl frag-
ment, the products formed were always the Pt(II) complexes
9–12 (Scheme 2). This can be ascribed to steric congestion
around the Pt(IV) centre (initially formed by oxidative addi-
tion of the RfI to the [Pt(diimine)Me2] complex), resulting in
in situ reductive elimination of MeI to form the square pla-
nar Pt(II) complex.
Owing to the solubility of 7 in hexane, the desired per-
fluoroalkyl complexes could also be obtained by heating at
reflux in hexane for 8 h. The use of hexane, however, only
resulted in better yields when the perfluoroalkyl group was
C3F7. Hexane also afforded straightforward isolation of the
Pt(II) complexes, which are insoluble in hexane. Unfortu-
nately, the lack of hexane solubility for dimethyl complexes
possessing other diimine ligands (1, 2, and 8) precluded its
use as a general solvent for the synthesis of these complexes.
Before ethyl acetate was found to facilitate these oxidative
addition reactions of [Pt(diimine)Me2] complexes with iodo-
fluoroalkanes, attempts were made to use benzene as a sol-
vent. However, when benzene was used, the reaction was
incomplete after heating at reflux for 24 h, and there was
formation of elemental Pt. NMR of the crude reaction mix-
tures showed approximately 30%–40% conversion to the de-
sired products after 24 h. However, isolation of the oxidative
Attempts to convert the Pt(IV) complexes to Pt(II) species
with procedures that we have used successfully for such re-
ductions in cases when the ligands involved are tmeda, 1,2-
bis(diphenylphosphino)ethane, or 1,2-bis(dimethylphosphi-
no)ethane proved unsuccessful. The methods attempted to
achieve this reduction included: (i) removal of iodide using
AgBF4 and heating at reflux in acetone to eliminate ethane,
followed by addition of NaI to form the iodoplatinum(II)
complex (32); (ii) heating a solution of the complex in the
presence of NEt3, to form the insoluble [Et3NMe]I complex
upon thermal elimination of MeI (11); and (iii) reaction of
the complex with NaBH4 (to convert the iodo ligand to a hy-
dride) and then stirring at room temperature to allow the
complex to thermally eliminate methane. In the first case,
the starting complexes were obtained without any observable
isomerization, while degradation of the Pt(IV) complex to
elemental platinum occurred in the last two methods.
As discussed above, the only instances in which Pt(II)
complexes were obtained were from reactions in which the
diimine ligand possessed the 2,6-dimethylaryl substituent.
The NMR spectra of these complexes are very diagnostic as
the backbone protons (or methyl groups) of the diimine
ligand are inequivalent due to the Cs symmetry of the
square-planar complexes. In the 1H NMR spectrum, the
diimine backbone protons of complexes 9 and 10 exhibit Pt
3
satellites: in the case of 9, these JPtH coupling constants
were 36 Hz (δ 9.01 ppm) and 84 Hz (δ 8.93 ppm), while for
10 the coupling constants were 37 Hz (δ 9.20 ppm) and
42 Hz (δ 9.06 ppm), respectively. A similar coupling was
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Can. J. Chem. Vol. 81, 2003
Scheme 1.
Scheme 2.
previously seen in numerous unsymmetrical platinum
diimine complexes (42, 48–54). Tilset (49) assigned the pro-
tons on the diimine backbone using a variety of NMR tech-
niques, with the smaller coupling being ascribed to those
protons transoid to the methyl ligand. Thus, some indication
as to the relative trans-influence of the two different fluoro-
alkyl ligands in these complexes can be obtained: the par-
tially fluorinated ligand (CFHCF3) exerts a stronger trans
influence than the perfluorinated ligand (C3F7). The com-
plexes possessing methyl substitution of the diimine back-
bone (complexes 11 and 12) do not exhibit any coupling to
Pt.
The [Pt(diimine)(Rf)Me] complexes 9–12 are readily con-
verted to the iodo complexes 13–16 via two methods, each
of which results in selective cleavage of the Pt—CH3 bond
rather than the Pt—fluoroalkyl bond. The first involves the
reaction of the complex with I2 in CH2Cl2, possibly resulting
in the formation of a transient diiodo–Pt(IV) complex, which
undergoes thermal reductive elimination of MeI. The second
pathway involves reaction of the methyl complex with
1 equiv. of aq HI in toluene (Scheme 2), resulting in the gen-
eration of methane followed by trapping of the resulting
cationic Pt(II) fragment with iodide. Both methods afford
the iodo complexes in 70%–80% yield after recrystallization
from dichloromethane–hexane.
The NMR spectra of the iodo complexes are very similar
to those of the methyl analogues. As was the case for the
methyl complexes, the backbone protons of the diimine
ligand in complexes 13 and 14 display platinum coupling:
3
for 13, JPtH = 102 Hz (δ 9.00 ppm) and 40 Hz (δ 8.62 ppm),
3
while for 14, JPtH = 100 Hz (δ 9.16 ppm) and 38 Hz
(δ 8.68 ppm). Presumably, the large difference in the cou-
pling constants for both complexes may be explained by the
large cis-effect exerted by the iodo ligand. As was the case
in the methyl complexes, no platinum satellites were ob-
served for those complexes possessing methyl substitution
on the backbone of the diimine ligand.
Crystal structures
X-ray diffraction quality crystals were obtained for sev-
eral of the Pt(IV) complexes by slow recrystallization from
CH2Cl2–hexane. Crystal structures were obtained for com-
© 2003 NRC Canada

Hughes et al.
1273
Fig. 1. ORTEP diagram of the non-hydrogen atoms of 3, showing the atom labelling scheme. Thermal ellipsoids are shown at 30%
probability.
Fig. 2. ORTEP diagram of the non-hydrogen atoms of 4, showing the atom labelling scheme. Thermal ellipsoids are shown at 30%
probability.
plexes 3 (Fig. 1), 4 (Fig. 2), and 5 (Fig. 3). Details of the
crystal data and structure determinations of all complexes
are presented in Table 1. Selected bond lengths and angles
for the coordination sphere of Pt are given in Table 2. For
easy comparison, a common numbering scheme has been
adopted: in the Pt(IV) complexes, the equatorial plane corre-
sponds to the plane of N(1) and N(2) of the diimine ligand
and C(1) and C(2) of the two methyl groups, while C(3) (the
α-carbon of the perfluoroalkyl moiety) is always trans to I.
The structures obtained for complexes 3 and 4 display dis-
order in the CF3 groups of the diimine ligand, and, in the
case of the structures for 4 and 5, a small amount of disorder
is also observed in the perfluoroalkyl moiety.
The crystal structures of complexes 3, 4, and 5 show the
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1274
Can. J. Chem. Vol. 81, 2003
Fig. 3. ORTEP diagram of the non-hydrogen atoms of 5, showing the atom labelling scheme. Thermal ellipsoids are shown at 30%
probability.
Table 1. Summary of X-ray crystallographic data collection, solution, and refinement parameters for complexes 3, 4, 5, and 11.
Complex
Formula
3
4
5
11
C25H18F19IN2Pt
C24H19F16IN2Pt
C24H19F16IN2Pt
C24H27F7N2Pt
Space group
a (Å)
b (Å)
c (Å)
α (°)
β (°)
γ (°)
V (Å3)
P21/n
P21/n
P-1
P21/n
14.0822(6)
9.2888(4)
24.2972(1)
90.00
101.885(1)
90.00
14.5331(1)
9.3944(7)
23.4593(17)
90.00
101.229(1)
90.00
8.3105(5)
11.8465(8)
31.026(2)
95.757(1)
92.018(1)
108.0410(10)
2882.6(3)
4
8.3273(5)
13.0769(7)
23.0810(13)
90.00
90.109(1)
90.00
3110.1(2)
4
3141.6(4)
4
2513.4(2)
4
Z
Crystal colour, habit
D(calcd.) (g/cm3)
µ (mm–1)
T (K)
Yellow, block
2.198
5.639
Amber, block
2.033
5.562
Yellow, block
2.215
6.061
Red, block
1.775
5.649
100(2)
295(2)
100(2)
173(2)
Total data
Unique data (Rint)
R1, wR2 (I > 2σ(I))
All data
7346
6160
18 522
15 786
6757(0.0232)
0.0406, 0.0994
0.0441, 0.1015
4764(0.0262)
0.0513, 0.1496
0.0679, 0.1612
12 959(0.0207)
0.0405, 0.0948
0.0530, 0.1002
5856(0.0280)
0.0778, 0.2135
0.0979, 0.2551
Pt(IV) center to have approximate octahedral geometry.
There is only a subtle deviation from the ideal angle of 180°
for C(3)-Pt-I(1), with 5 showing the largest discrepancy with
an angle of 175.8(3)°. The deviation is also observed for the
C(3)-Pt-N(1) angle in 5, which exhibits a value of 96.7(3)°,
while complexes 3, and 4 have angles close to 90°. In all
structures, there is deviation from the expected angles in the
plane of the Pt atom: the C(1)-Pt-C(2) angles are reduced
substantially (especially in the case of 4 and 5), presumably
due to the bulk of the aryl groups on the diimine ligand. As
a consequence, the C(1)-Pt-N(2) and the C(2)-Pt-N(1) bond
angles are all in the region of 100°. The Pt—C(1) and Pt—
C(2) bond lengths for 3 and 5 are similar in all cases and are
identical for each complex, except for complex 4, in which
there is a significant variation between the two bond lengths
(2.072(11) Å and 2.031(12) Å, respectively). The source of
this bond length variation is not clear. The Pt—C(3) bond
lengths for 3 (2.129(8) Å) and 5 (2.076(8) Å) are signifi-
cantly different, with an unexpectedly shorter bond to the
partially hydrogenated α-CFH group. However, the Pt—I
bond lengths for 3 (2.6769(4) Å) and 5 (2.7447(5) Å) do dis-
play the expected trend for the trans-influence of the alkyl
group, with a greater degree of fluorination affording a
weaker trans-influence (10, 55). Because the Pt—N(1) and
© 2003 NRC Canada

Hughes et al.
1275
Fig. 4. ORTEP diagram of the non-hydrogen atoms of 11, showing the atom labelling scheme. Thermal ellipsoids are shown at 30%
probability.
Pt—N(2) bond lengths for 3, 4, and 5 are similar in all cases
and show no significant variation within each complex, there
is clearly no cis-effect in the differently fluorinated alkyl
groups.
Table 2. Selected bond lengths (Å) and angles (°) for the coordi-
nation sphere of platinum in complexes 3, 4, 5, and 11.
Complex
3
4
5
11
Bond angles (Å)
No meaningful comparisons between the Pt(IV)–diimine
complexes and the analogous Pt(IV)–tmeda complexes can
be made, as the tmeda complexes isomerize from the initial
trans-product to form the thermodynamically favored cis-
product.3
Crystallization of 11 from CH2Cl2–hexane afforded red
plates that were suitable for X-ray diffraction studies. The
ORTEP diagram for complex 11 is shown in Fig. 4. Selected
bond lengths and angles for the coordination sphere of Pt are
given in Table 2. The numbering scheme adopted for com-
plex 11 has N(1) trans to C(1) (the methyl group), while
N(2) is trans to C(2) (the α-carbon of the perfluoroalkyl
moiety).
The structure shows the complex is square planar, with no
significant deviations of the ligands from the plane, but with
significant bond angle deviations due to the steric bulk of
the perfluoroalkyl ligand. The C(2)-Pt-N(2) bond angle of
176.1(5)° is close to the ideal angle, however, there is signif-
icant deviation observed for the C(1)-Pt-N(1) which has a
bond angle of 171.0(6)°. Similarly, the C(2)-Pt-N(1) bond
angle (101.8(6)°) shows a large distortion that is attributable
to the steric requirements of the perfluoroalkyl moiety. Vari-
ations in the bond lengths to the Pt atom are also observed
which is a consequence of the relative magnitude of the
trans-influence for methyl and perfluoroalkyl ligands: the
Pt—C(1)
Pt—C(2)
Pt—C(3)
Pt—N(1)
Pt—N(2)
Pt—X
2.065(6)
2.072(11)
2.031(12)
2.228(9)
2.178(6)
2.183(7)
2.6963(8)
2.053(7)
2.055(7)
2.076(9)
2.187(5)
2.178(5)
2.7447(5)
2.047(9)
2.032(9)
—
2.133(7)
2.077(8)
—
2.066(5)
2.129(8)
2.175(4)
2.170(5)
2.6769(4)
Bond angles (°)
C(1)-Pt-C(2)
C(1)-Pt-C(3)
C(1)-Pt-N(1) 172.5(2)
C(1)-Pt-N(2)
C(1)-Pt-X
C(2)-Pt-C(3)
C(2)-Pt-N(1)
C(2)-Pt-N(2) 172.3(2)
88.2(2)
94.3(2)
85.4(5)
92.0(4)
173.3(4)
99.4(4)
89.5(3)
91.1(4)
100.7(4)
174.4(4)
88.0(3)
90.7(3)
91.5(3)
85.1(3)
88.1(4)
174.5(3)
100.2(2)
91.0(2)
87.2(6)
—
171.0(6)
93.9(6)
—
98.8(2)
87.53(18)
91.1(2)
98.7(2)
88.1(4)
—
100.2(2)
174.7(2)
91.3(2)
96.7(3)
92.4(3)
175.8(3)
74.48(18
87.57(13
88.49(13
101.8(4)
176.1(5)
—
—
—
—
77.1(4)
—
C(2)-Pt-X
88.81(16)
88.43(19)
91.4(2)
C(3)-Pt-N(1)
C(3)-Pt-N(2)
C(3)-Pt-X
178.12(16) 178.2(2)
N(1)-Pt-N(2)
N(1)-Pt-X
N(2)-Pt-X
74.08(17)
89.72(11)
88.46(12)
74.4(3)
87.91(17)
89.13(16)
—
3 Our initial observations on this reaction were that the cis-product was formed. More careful studies have shown that the trans-isomer is the
kinetic product. R.P. Hughes, M.A. Meyer, A.J. Ward, A. Williamson. Unpublished results.
© 2003 NRC Canada

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Can. J. Chem. Vol. 81, 2003
Pt—C(1) bond length is 2.047(9) Å, while the Pt—C(2)
bond length is slightly shorter at 2.032(9) Å. However, it is
in the Pt—N bond lengths that the trans-effect is most
clearly manifested: the Pt—N(1) bond length (trans to
methyl) is 2.133(7) Å, while the Pt—N(2) bond length (trans
to C3F7) is 2.077(8) Å.
CH2Cl2–hexane to afford the product as an orange powder
(86 mg, 71%). 1H NMR (CDCl3) δ (ppm): 8.44 (s, 2H, ArH),
4
7.96 (s, 2H, ArH), 7.37 (s, 2H, ArH), 2.49 (s, 6H, JPtH
=
5 Hz, N=C(CH3)), 1.37 (s, 6H, JPtH = 73 Hz, PtCH3). 19F
2
NMR (CDCl3) δ (ppm): –63.34 (s, 6F, m-ArCF3), –63.47 (s,
4
4
6F, m-ArCF3), –80.07 (t, 3F, JFF = 13 Hz, JPtF = 9 Hz,
2
CF2CF3), –90.08 (m, 2F, JPtF = 298 Hz, PtCF2), –122.03
Comparison of the structure obtained for 11 and that ob-
tained previously for [Pt(tmeda)(C3F7)Me] (11) reveals that
the presence of the diimine ligand results in significant steric
crowding around the Pt center, and thus, there is some varia-
tion in bond lengths and bond angles between the two com-
plexes. For example, the Pt—C(1) and Pt—C(2) bond
lengths for the tmeda complex are 2.148(18) Å and 2.01(2)
Å, respectively, compared to 2.047(9) Å and 2.032(9) Å for
the same bonds in complex 11. The Pt—N(1) and Pt—N(2)
are 2.14(2) Å and 2.172(19) Å, respectively, for the tmeda
complex, while they are 2.133(7) Å and 2.077(8) Å for 11.
Significant variation in bond angles is observed between the
two complexes: C(1)-Pt-C(2) for 11 is 87.2(6)° and for the
tmeda complex is 88.3(9)°; C(1)-Pt-N(2) for 11 is 93.9(6)°
and for the tmeda complex is 92.3(8)°; C(2)-Pt-N(2) for 11
is 101.8(6)° and for the tmeda complex is 97.7(9)°. While
these large variations are probably attributable solely to the
large steric bulk of the diimine aryl groups, the data for the
tmeda complex are of poor quality and preclude any more
meaningful comparisons.
(m, 2F, CF2CF3). Anal. calcd. for C25H18F19IN2Pt (%): C
29.17, H 1.77; found (%): C 29.37, H 1.65.
trans-[1,2-Bis(3,5-bis(trifluoromethylphenylimino)-1,2-
dimethylethane]iododimethyl-(2H-tetrafluoroethyl)plati-
num(IV) (4)
To a solution of 1 (100 mg, 0.14 mmol) in degassed ethyl
acetate (10 mL) was added iodo-2H-tetrafluoroethane
(23 µL, 0.20 mmol) and the reaction mixture was heated at
reflux in the absence of light for 2 h. The solution was
cooled and the solvent removed in vacuo. The residue was
extracted with hot hexanes until no colour persisted in the
washings. The volume of the combined extracts was reduced
in vacuo to 5 mL and cooled to –30 °C. The product was ob-
1
tained by filtration as a yellow powder (86 mg, 66%). H
NMR (CDCl3) δ (ppm): 8.42 (s, 2H, ArH), 7.94 (s, 2H,
2
ArH), 7.45 (s, 2H, ArH), 5.45 (tt, JFH = 55 Hz, 3JFF = 6 Hz,
4
2JPtH = 11 Hz CF2H), 2.47 (s, 6H, JPtH = 5 Hz, N=C(CH3)),
2
1.26 (s, 6H, JPtH = 72 Hz, PtCH3). 19F NMR (CDCl3) δ
3
(ppm): –63.30 (s, 12F, m-ArCF3), –90.98 (dt, 2F, JFF
=
3
3
3 Hz, JFH = 6 Hz, JPtF = 307 Hz, CF2CF2H), –131.69 (dt,
Experimental section
3
2
2
2F, JFF = 6 Hz, JFH = 55 Hz, JPtF = 27 Hz, CF2CF2H).
Anal. calcd. for C24H19F16IN2Pt (%): C 29.98, H 2.00; found
(%): C 30.21, H 1.87.
General considerations
Unless otherwise noted, all reactions were performed in
oven-dried glassware, using standard Schlenk techniques,
under an atmosphere of nitrogen (which had been deoxy-
genated over BASF catalyst), and dried using Aquasorb®.
Solvents were deoxygenated and dried over activated alu-
mina using an apparatus modified from that described in the
literature (56). 1H (300 MHz), 19F (282 MHz), and 31P
(121.4 MHz) NMR spectra were recorded on a Varian
Unity-300 spectrometer at 25 °C. Chemical shifts are re-
ported as ppm downfield of TMS (1H, referenced to solvent)
or internal CFCl3 (19F). Coupling constants are reported in
Hertz (Hz). Microanalyses were performed by Schwartzkopf
Microanalytical Laboratory (Woodside, N.Y.).
trans-[1,2-Bis(3,5-bis(trifluoromethylphenylimino)-1,2-
dimethylethane]dimethyliodo(1H-tetrafluoroethyl)plati-
num(IV) (5)
To a solution of 1 (100 mg, 0.14 mmol) in degassed ethyl
acetate (10 mL) was added iodo-1H-tetrafluoroethane
(23 µL, 0.20 mmol) and the reaction mixture was heated at
reflux in the absence of light for 2 h. The solution was
cooled and the solvent removed in vacuo. The residue was
extracted with hot hexanes until no colour persisted in the
washings. The volume of the combined extracts was reduced
in vacuo to 5 mL and cooled to –30 °C. The product was ob-
1
tained by filtration as a yellow powder (85 mg, 65%). H
Iodoperfluoroalkanes were purchased from PCR, (except
for CF3CFHI, which was purchased from ABCR)
treated with Na2S2O3 to remove residual I2, and vacuum
NMR (CDCl3) δ (ppm): 8.73 (bs, 1H, ArH), 8.39 (s, 1H,
ArH), 7.94 (s, 2H, ArH), 7.41 (bs, 2H, ArH), 4.72 (dq, 1H,
3
2
2JFH = 47 Hz, JFF = 10 Hz, JPtH = 410 Hz, CFH), 2.48 (s,
distilled
before
use.
The
complexes
[Pt(3,5-
4
4
3H, JPtH = 5 Hz, N=C(CH3)), 2.45 (s, 3H, JPtH = 5 Hz,
(CF3)2ArN=C(Me)C(Me)=N-3,5-(CF3)2Ar)Me2] (1) (57),
[Pt(4-MeArN=CHCH=N-4-MeAr)Me2] (2) (58), [Pt(2,6-
Me2ArN=CHCH=N-2,6-Me2Ar)Me2] (7) (59), and [Pt(2,6-
Me2ArN=C(Me)C(Me)=N-2,6-Me2Ar)Me2] (8) (59) were
prepared as reported previously.
4
2
N=C(CH3)), 1.27 (d, 3H, JFH = 1 Hz, JPtH = 70 Hz,
PtCH3), 1.12 (s, 3H, JPtH = 71 Hz, PtCH3). 19F NMR
2
(CDCl3) δ (ppm): –63.18 (s, 3F, m-ArCF3), –63.27 (s, 3F, m-
3
ArCF3), –63.32 (s, 6F, m-ArCF3), –72.95 (dd, 3F, JFF
=
3
3
11 Hz, JFH = 11 Hz, JPtF = 61 Hz, CFHCF3), –191.43 (dq,
3
3
2
1F, JFF = 11 Hz, JFH = 47 Hz, JPtF = 135 Hz, CFHCF3).
Anal. calcd. for C24H19F16IN2Pt (%): C 29.98, H 2.00; found
(%): C 29.87, H 1.99. X-ray diffraction quality crystals were
grown from CH2Cl2–hexane.
trans-[1,2-Bis(3,5-bis(trifluoromethylphenylimino)-1,2-
dimethylethane]dimethyl(heptafluoropropyl)iodoplatinum(IV)
(3)
To a solution of 1 (100 mg, 0.14 mmol) in degassed ethyl
acetate (10 mL) was added heptafluoropropyl iodide
(30 mL, 0.20 mmol) and the reaction mixture was heated at
reflux for 2 h in the absence of light. The solvent was re-
moved in vacuo. The residue was recrystallized from
trans-[1,2-Bis(4-methylphenylimino)ethane]dimethyl(hepta-
fluoropropyl)iodoplatinum(IV) (6)
To a suspension of 2 (100 mg, 0.22 mmol) in hexane
© 2003 NRC Canada

Hughes et al.
1277
4
4
(10 mL) was added C3F7I (47 µL, 0.33 mmol) and the reac-
tion mixture was refluxed for 8 h. The solution was cooled
and the solvent removed in vacuo. Recrystallization from
hot hexane afforded the product as an orange
4JFF = 10 Hz, JPtF = 19 Hz, CF3), –93.51 (tq, 2F, JFF
=
=
2
3
10 Hz, JPtF = 410 Hz, PtCF2), –119.74 (t, 2F, JPtF
119 Hz, CF2CF3). Anal. calcd. for C24H27F7N2Pt (%): C
42.92, H 4.06; found (%): C 43.1, H 4.12.
1
microcrystalline solid (104 mg, 63%). H NMR (CDCl3) δ
3
[1,2-Bis(2,6-dimethylphenylimino)-1,2-dimethyl-
(ppm): 8.67 (t, 2H, JPtH = 26 Hz, N=CH), 7.45 (m, 4H,
ethane]methyl(1H-tetrafluoroethyl)platinum(II) (12)
To a solution of 8 (100 mg, 0.19 mmol) in ethyl acetate
(10 mL) was added C3F7I (42 µL, 0.29 mmol) and the reac-
tion mixture was heated under reflux in the absence of light
for 24 h. The solution was cooled and the solvent reduced to
5 mL in vacuo. Hexane was added. Filtration afforded the
product as a purple microcrystalline powder (100 mg, 85%).
1H NMR (CDCl3) δ (ppm): 7.30–7.17 (m, 6H, ArH), 5.63
ArH), 7.31 (m, 4H, ArH), 2.44 (s, 6H, ArCH3), 1.77 (t, 6H,
2JPtH = 74 Hz, PtCH3). 19F NMR (CDCl3) δ (ppm): –80.01 (t,
3F, 4JFF = 12 Hz, 4JPtF = 18 Hz, CF3), –91.93 (qt, 2F, 2JPtF
362 Hz, JFF = 12 Hz, JFF = 3 Hz, PtCF2), –121.79 (m, 2F,
CF2CF3). Anal. calcd. for C21H22F7IN2Pt (%): C 33.29, H
2.93; found (%): C 33.83, H 3.12.
=
4
3
[1,2-Bis(2,6-dimethylphenylimino)ethane](heptafluoro-
propyl)methylplatinum(II) (9)
2
3
2
(dq, 1H, JFH = 49 Hz, JFH = 13 Hz, JPtH = 52 Hz, CFH),
2.28 (s, ArCH3), 1.66 (s, 3H, N=C(CH3)), 1.35 (s, 3H,
To a solution of 7 (100 mg, 0.20 mmol) in hexane
(10 mL) was added C3F7I (44 µL, 0.31 mmol) and the reac-
tion mixture was heated at reflux for 18 h. The solution was
cooled. Filtration and washing with hexane afforded the
product as a maroon microcrystalline solid (146 mg, 91%).
2
N=C(CH3)), 1.10 (s, 3H, JPtH = 86 Hz, PtCH3). 19F NMR
3
3
(CDCl3) δ (ppm): –70.73 (dd, 3F, JFH = 13 Hz, JFF
=
2
3
14 Hz, CF3), –211.64 (dq, 1F, JFH = 49 Hz, JFF = 14 Hz,
CFH). Anal. calcd. for C23H28F4N2Pt (%): C 45.76, H 4.69;
found (%): C 45.77, H 4.53.
3
1H NMR (CDCl3) δ (ppm): 9.01 (t, 1H, JPt-H = 36 Hz,
3
N=CH), 8.93 (t, 1H, JPtH = 84 Hz, N=CH), 7.21 (s, 4H, m-
[1,2-Bis(2,6-dimethylphenylimino)ethane](heptafluoro-
propyl)iodoplatinum(II) (13)
ArH), 7.14 (m, 2H, p-ArH), 2.28 (s, 12H, CH3), 1.21 (t, 3H,
2JPtH = 88 Hz, PtCH3). 19F NMR (CDCl3) δ (ppm): –79.98 (t,
4
4
2
3F, JPtF = 36 Hz, JFF = 10 Hz, CF3), –94.74 (q, 2F, JPtF
=
=
Method 1:
4
3
420 Hz, JFF = 10 Hz, PtCF2), –120.33 (s, 2F, JPtF
To a solution of 9 (100 mg, 0.16 mmol) in CH2Cl2
(10 mL) was added iodine (39 mg, 0.16 mmol) and the reac-
tion mixture was stirred in the dark for 12 h. The solvent
was reduced in volume to approximately 5 mL in vacuo.
Hexane was added to precipitate the product as a brown
powder. Recrystallization from CH2Cl2–hexane at –30 °C af-
forded the product as an umber microcrystalline solid
116 Hz, CF2CF3). Anal. calcd. for C22H23F7N2Pt (%): C
41.06, H 3.61; found (%): C 41.04, H 3.69.
[1,2-Bis(2,6-dimethylphenylimino)ethane](1H-tetrafluoro-
ethyl)methylplatinum(II) (10)
To a solution of 7 (100 mg, 0.20 mmol) in ethyl acetate
(10 mL) was added iodo-1H-tetrafluoroethane (70 mg,
0.31 mmol) and the reaction mixture was heated at reflux for
12 h in the absence of light. The solvent was removed in
vacuo and the residue was washed with hexane until no col-
our persisted in the washings. The product was obtained as
purple needles after recrystallization from chloroform–hex-
1
(94 mg, 80%). H NMR (CDCl3) δ (ppm): 9.00 (t, 1H,
3
3JPtH = 102 Hz, N=CH), 8.62 (t, 1H, JPtH = 40 Hz, N=CH),
7.23–7.15 (m, 6H, ArH), 2.33 (s, 6H, CH3), 2.30 (s, 6H,
4
CH3). 19F NMR (CDCl3) δ (ppm): –80.08 (t, 3F, JFF
=
2
4
11 Hz, CF3), –80.83 (tqd, 2F, JPtF = 288 Hz, JFF = 11 Hz,
5JFH = 4 Hz, PtCF2), –114.69 (t, 2F, JPtF = 72 Hz, CF2CF3).
5
1
ane (50 mg, 45%). H NMR (CDCl33) δ (ppm): 9.20 (s, 1H,
Anal. calcd. for C21H20F7IN2Pt (%): C 33.39, H 2.67; found
(%): C 32.65, H 2.57.
3JPtH = 37 Hz, N=CH), 9.06 (s, 1H, JPtH = 42 Hz, N=CH),
2
3
7.24–7.15 (m, 6H, ArH), 6.03 (dq, 1H, JFH = 50 Hz, JFH
=
2
11 Hz, JPtF = 61 Hz, CFH), 2.36 (s, 3H, ArCH3), 2.29 (s,
3H, ArCH3), 2.27 (s, 3H, ArCH3), 2.20 (s, 3H, ArCH3), 1.36
Method 2:
To a solution of 9 (100 mg, 0.16 mmol) in toluene
(10 mL) was added hydriodic acid (57% w/w, 20 µL,
0.16 mmol) and the reaction mixture was stirred at room
temperature for 4 h. The solvent was removed in vacuo and
the residue recrystallized from CH2Cl2–hexane to afford the
product as an umber microcrystalline powder (83 mg, 78%).
(s, 3H, JPtH = 86 Hz, PtCH3). 19F NMR (CDCl3) δ (ppm):
2
3
3
3
–70.69 (dd, 3F, JFH = 14 Hz, JFF = 14 Hz, JPtF = 141 Hz,
2
3
2
CF3), –212.28 (dq, 1F, JFH = 50 Hz, JFF = 14 Hz, JPtF
=
327 Hz, CFH). Anal. calcd. for C21H24F4N2PtC0.5CHCl3
(%): C 40.65, H 3.90; found (%): C 41.37, H 3.74.
[1,2-Bis(2,6-dimethylphenylimino)-1,2-dimethyl-
ethane](heptafluoropropyl)methylplatinum(II) (11)
[1,2-Bis(2,6-dimethylphenylimino)ethane](1H-tetrafluoro-
ethyl)iodoplatinum(II) (14)
To a solution of 8 (100 mg, 0.19 mmol) in ethyl acetate
(10 mL) was added C3F7I (42 µL, 0.29 mmol) and the reac-
tion mixture was heated under reflux in the absence of light
for 2 h. The solution was cooled and the solvent removed in
vacuo. The residue was recrystallized from CH2Cl2–hexane.
Filtration afforded the complex as a purple powder (66 mg,
51%). 1H NMR (CDCl3) δ (ppm): 7.19 (m, 4H, p-ArH), 7.12
To a solution of 10 (100 mg, 0.19 mmol) in toluene
(10 mL) was added HI (57% w/w, 33 µL, 0.29 mmol) and
the reaction mixture was stirred at room temperature for 4 h.
The solvent was removed in vacuo and the residue recrystal-
lized from CH2Cl2–hexane to afford the product as a black
1
powder (86 mg, 74%). H NMR (CDCl3) δ (ppm): 9.16 (s,
3
3
1H, JPtH = 100 Hz, N=CH), 8.68 (s, 1H, JPtH = 38 Hz,
2
(s, 2H, p-ArH), 2.21 (s, 12H, o-ArCH3), 1.73 (s, 3H,
N=CH), 7.25–7.15 (m, 6H, ArH), 6.09 (dq, 1H, JFH =
50 Hz, JFH = 11 Hz, JPtH = 61 Hz, Hz, CFH), 2.39 (s, 3H,
ArCH3), 2.36 (s, 3H, ArCH3), 2.29 (s, 3H, ArCH3), 2.25 (s,
2
3
2
N=C(CH3)), 1.63 ((s, 3H, N=C(CH3)), 0.70 (t, 3H, JPtH
=
86 Hz, PtCH3). 19F NMR (CDCl3) δ (ppm): –80.01 (tt, 3F,
© 2003 NRC Canada

1278
Can. J. Chem. Vol. 81, 2003
3H, ArCH3). 19F NMR (CDCl3) δ (ppm): –68.61 (dd, 3F,
tions. All software and sources of scattering factors are con-
tained in the SHELXTL (5.10) program libraries (61).
3
2
3JFH = 15 Hz, JFF = 11 Hz, JPtF = 91 Hz, CF3), –211.67
2
3
2
(dq, 1F, JFH = 50 Hz, JFF = 11 Hz, JPtF = 359 Hz, CFH).
Anal. calcd. for C20H21F4IN2Pt (%): C 34.94, H 3.09; found
(%): C 35.32, H 3.36.
Acknowledgements
R.P.H. is grateful to the National Science Foundation and
the Petroleum Research Fund, administered by the American
Chemical Society, for financial support.
[1,2-Bis(2,6-dimethylphenylimino)-1,2-dimethyl-
ethane](heptafluoropropyl)iodoplatinum(II) (15)
To a solution of 11 (100 mg, 0.15 mmol) in toluene
(5 mL) was added HI (57% w/w, 100 µL, excess) and the re-
action mixture was stirred at room temperature for 8 h. The
solvent was removed in vacuo. The residue was extracted
with CH2Cl2 and the supernatant solution filtered. The sol-
vent was reduced in vacuo to 5 mL and hexane was added.
Filtration afforded the product as a brick-red powder (82 mg,
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3. A.A. Bowden, R.P. Hughes, D.C. Lindner, C.D.
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1
71%). H NMR (CDCl3) δ (ppm): 7.23–7.13 (m, 6H, ArH),
2.26 (s, 6H, ArCH3), 2.23 (s, 6H, ArCH3), 2.22 (s, 3H,
N=C(CH3)), 1.84 (s, 3H, N=C(CH3)). 19F NMR (CDCl3) δ
4
3
2
(ppm): –79.65 (qt, 3F, JFF = 11 Hz, JFF = 4 Hz, JPtF
=
4
4
290 Hz, CF3), –93.46 (t, 2F, JFF = 11 Hz, JPtF = 38 Hz,
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3
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[1,2-Bis(2,6-dimethylphenylimino)-1,2-dimethyl-
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To a solution of 12 (100 mg, 0.17 mmol) in CHCl3
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mixture was stirred at room temperature overnight. The sol-
vent was removed in vacuo. The residue was recrystallized
from CH2Cl2–hexane to afford the product as a deep orange
powder (88 mg, 74%). 1H NMR (CDCl3) δ (ppm): 7.23–7.08
2
3
2
(m, 6H, ArH), 5.60 (dq, JFH = 50 Hz, JFH = 11 Hz, JPtH
=
51 Hz, CFH), 2.20 (s, 9H, 3 × ArCH3), 1.56 (s, 3H, ArCH3),
4
1.26 (s, 3H, C(CH3)), 1.02 (s, 3H, JPtH = 86 Hz, C(CH3)).
3
19F NMR (CDCl3) δ (ppm): –70.74 (dd, 3F, JFF = 11 Hz,
3
2
3JFH = 11 Hz, JPtF = 136 Hz, CF3), –211.69 (dq, 1F, JPH
=
3
2
50 Hz, JFF = 15 Hz, JPtF = 388 Hz, CFH). Anal. calcd. for
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3.40.
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Crystallographic structural determinations
Diffraction intensity data were collected with a Bruker
Smart Apex CCD diffractometer. Crystal data collection and
refinement parameters are provided in Table 1.4 The struc-
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quent difference Fourier syntheses and refined by full-matrix
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SADABS absorption corrections were applied to all struc-
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4 Supplementary material may be purchased from the Depository of Unpublished Data, Document Delivery, CISTI, National Research Coun-
cil Canada, Ottawa, ON K1A OS2, Canada. For information on obtaining material electronically go to http://www.nrc.ca/
cisti/irm/unpub_e.shtml. CCDC 204287 (3), 204288 (4), 204289 (5), and 204290 (11) contain the crystallographic data for this manuscript.
These data can be obtained, free of charge, via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data
Centre, 12, Union Road, Cambridge CB2 1EZ, U.K.; fax: +44 1233 336033; or deposit@ccdc.cam.ac.uk).
© 2003 NRC Canada

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