Stepwise degradation of trifluoromethyl platinum(II) compounds

Article abstract of DOI:10.1002/chem.201202648

The action of moisture on the homoleptic organoplatinum(II) compound [NBu₄]₂[Pt(CF₃)₄] (1) gives rise to the carbonyl derivative [NBu₄][Pt(CF₃)₃(CO)] (2), which is itself moisture stable. However, treatment of compound 2 with HCl(aq) results in the formation of [NBu₄][cis-Pt(CF ₃)₂Cl(CO)] (3), which undergoes degradation of an additional CF₃ group by further treatment with HCl(aq) in large excess, affording [NBu₄][cis-Pt(CF₃)Cl₂(CO)] (4). The carbonyl derivatives 2-4 are fairly stable species, in which the CO ligand, however, can be readily extruded by reaction with trimethylamine N-oxide (ONMe₃). Thus, compound 2 reacts with ONMe₃ in the presence of a number of neutral or anionic ligands affording a series of singly or doubly charged derivatives with the general formulae [NBu₄] [Pt(CF₃)₃(L)] [L=CNtBu (5), PPh₃ (6), P(o-tolyl)₃ (7), tht (8; tht=tetrahydrothiophene)] and [NBu ₄]₂[Pt(CF₃)₃X] [X=Cl (9), Br (10), I (11)], respectively. Compound 2 also reacts with ONMe₃ and pyridin-2-thiol (C₅H₅NS) giving rise to the five-membered metallacyclic derivative [NBu₄][Pt(CF₃) ₂(CF₂NC₅H₄S-κC,κS)] (12), which can be viewed as a difluorocarbene species stabilized by intramolecular base coordination. On the other hand, treatment of compound 3 with ONMe₃ in the presence of C₅H₅NS yields the four-membered metallacyclic compound [NBu₄][Pt(CF₃) ₂(NC₅H₄S-κN,κS)] (13). The geometries of the metallacycles in compounds 12 and 13 are compared. In the absence of any additional ligand, compound 3 undergoes dimerization producing the dinuclear species [NBu₄]₂[{Pt(CF₃) ₂}₂(μ-Cl)₂] (14). Halide abstraction in the latter compound with AgClO₄ in THF yields the solvento compound cis-[Pt(CF₃)₂(thf)₂] (15). The highly labile character of the THF ligands in compound 15 makes this species a convenient synthon of the cis-Pt(CF₃)₂ unit.

Full text of DOI:10.1002/chem.201202648

DOI: 10.1002/chem.201202648
Stepwise Degradation of Trifluoromethyl Platinum(II) Compounds
Sonia Martꢀnez-Salvador,[a] Juan Forniꢁs,*[a] Antonio Martꢀn,[a] Babil Menjꢂn,[a] and
Isabel Usꢂn[b]
Dedicated to Professor Pascual Romꢀn on the occasion of his 65th birthday
Abstract: The action of moisture on
the homoleptic organoplatinum(II)
anionic ligands affording a series of
singly or doubly charged derivatives
with the general formulae [NBu4][Pt-
base coordination. On the other hand,
treatment of compound 3 with ONMe3
in the presence of C5H5NS yields the
four-membered metallacyclic com-
compound [NBu4]2[Pt
rise to the carbonyl derivative [NBu4]-
[Pt(CF3)3(CO)] (2), which is itself
ACHTUGNTREN(UNNG CF3)4] (1) gives
AHCTUNGTRENNUNG
A
U
G
pound
[NBu4][PtACHTUGNETRN(NUG CF3)2(NC5H4S-
moisture stable. However, treatment of
compound 2 with HCl(aq) results in
U
kN,kS)] (13). The geometries of the
metallacycles in compounds 12 and 13
are compared. In the absence of any
additional ligand, compound 3 under-
goes dimerization producing the dinu-
the
formation
of
[NBu4]
N
2
A
degradation of an additional CF3 group
by further treatment with HCl(aq) in
G
G
clear species [NBu4]2[{PtACHTUNGRTENNU(G CF3)2}2ACHTUNGTRENNUNG(m-
large excess, affording [NBu4]
A
[cis-Pt-
G
Cl)2] (14). Halide abstraction in the
latter compound with AgClO4 in THF
yields the solvento compound cis-[Pt-
ACHUTNGRENN(UG CF3)2ACHTUNGTERN(NUGN thf)2] (15). The highly labile
character of the THF ligands in com-
atives 2–4 are fairly stable species, in
which the CO ligand, however, can be
readily extruded by reaction with tri-
methylamine N-oxide (ONMe3). Thus,
compound 2 reacts with ONMe3 in the
presence of a number of neutral or
À
À
Keywords: C F activation · C N
coupling · fluorinated compounds ·
platinum · transition metals
pound 15 makes this species a conven-
ient synthon of the “cis-PtACTHNUGTRNEG(UN CF3)2” unit.
À
Introduction
methyl (CF3). In this case, acidic treatment promotes C F
bond activation resulting in fluoride release and formation
of a difluorocarbene–metal unit (Scheme 1).[5] The involve-
ment of the [M]=CF2 unit has been established in several in-
stances by spectroscopic detection, isolation, and even struc-
tural determination of the corresponding species. Most usu-
ally, however, the [M]=CF2 unit is too unstable to be isolat-
ed or even detected and reacts readily with nucleophiles,
such as DOH2, evolving further into more stable species such
À
s-Organotransition-metal compounds, [M] R, typically
react with Brønsted acids, HA, by undergoing M C s-bond
À
cleavage.[1] As a result, RH is released and a vacant site at
the metal coordination environment is created, which, in the
absence of any better ligand, can be occupied by the anion
AÀ (if this is electrophilic enough) or the solvent. This pro-
cedure has been extensively used in transition-metal chemis-
try to create vacant coordination sites at the metal center.
The organyl groups R include the simplest alkyl group,
methyl (CH3), that releases methane upon protonation
(Scheme 1).[2–4] Sharply different behavior is observed, how-
ever, for the perfluorinated homologue, that is, trifluoro-
À
as [M] CO (hydrolysis).
Lewis acids as, for instance, SbF5 and even unsaturated
centers near the CF3 group are also able to bring about the
same reactivity pattern. Thus, compound [Ru] CF3, where
À
[Ru]=RuH
(PtBu2Me)2(CO), has been found to be in rapid
[a] Dr. S. Martꢀnez-Salvador, Prof. Dr. J. Forniꢁs, Dr. A. Martꢀn,
Dr. B. Menjꢂn
Instituto de Sꢀntesis Quꢀmica y Catꢃlisis Homogꢁnea (ISQCH)
Universidad de Zaragoza–CSIC
C/Pedro Cerbuna 12, E-50009 Zaragoza (Spain)
Fax: (+34)976-761-187
E-mail: juan.fornies@unizar.es
[b] Dr. I. Usꢂn
Instituciꢂ Catalana de Recerca i Estudis AvanÅats (ICREA)
Institut de Biologia Molecular de Barcelona–CSIC
C/Baldiri Reixach 13–15, E-08028 Barcelona (Spain)
Scheme 1. Reactions usually found in methyl- or trifluoromethyl deriva-
tives of transition metals (M) upon treatment with Brønsted acids.
324
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 324 – 337

FULL PAPER
À
equilibrium with F [Ru]=CF2
by spin saturation transfer tech-
niques (19F NMR spectroscopy),
whereby the unsaturated Ru
center acts as an intramolecular
Lewis acidic center.[6]
Scheme 2. Stepwise degradation of the CF3 groups in trifluoromethyl platinum(II) compounds starting from
the homoleptic derivative 1 ([NBu4]+ is the counterion in all cases).
The stability of trifluoro-
methyl derivatives of main-
À
group elements other than carbon, [E] CF3, may also be di-
minished by the action of Brønsted or Lewis acids. Thus, al-
though CF3OÀ salts of fairly large cations are reasonably
stable,[7] the corresponding protonated species CF3OH de-
composes at À208C into F2CO and HF.[8] Moreover, the in-
medium, compound 2 can be isolated as a white, air-stable
solid in 82% yield.
Compounds 1 and 2 provide a nice example evidencing
that transformation of an anionic CF3 ligand into a neutral
CO ligand involves a decrease in the electron charge on the
metal center and hence a deactivation of the resulting com-
plex species towards subsequent hydrolytic processes, as it
had already been noted by Appleton et al.[14]
stability of the homoleptic species BACTHNURGTNEG(UN CF3)3 has been attrib-
uted to the presence of a vacant p orbital on the boron
atom that would enable a fluorine 1,2-shift from the carbon
atom to the Lewis-acidic boron center.[9] In keeping with
this suggestion is the enhanced stability of the saturated,
We were not able to obtain single crystals of compound 2
that were suitable for X-ray diffraction purposes. Neverthe-
four-substituted (tetrahedral) species [B
(CF3)4]À, in which
less, the structure of the [Pt
lished by X-ray diffraction methods on single crystals of
[PPh4][Pt(CF3)3(CO)] (2’). This salt was readily obtained by
(CF3)3(CO)]À anion was estab-
ACHTUNGTRENNUNG
all valence orbitals are involved in chemical bonding. This
homoleptic species complying with the octet rule requires
treatment with concentrated H2SO4 to promote degradation
of just one CF3 group, thereby giving rise to the unusual car-
bonyl derivative (CF3)3B(CO).[10]
AHCTUNGTRENNUNG
following a simple metathetical process (see the Experimen-
tal Section). The PtII center is in a square-planar (SP-4) en-
vironment as expected for a four-coordinate d8 species
(Figure 1). The two mutually trans-standing CF3 groups are
virtually in line with the central atom, C(1)-Pt-C(3):
175.9(1)8, whereas the other two ligands deviate slightly
from linearity: C(2)-Pt-C(4): 171.9(1)8. This notwithstand-
ing, the sum of all angles between adjacent ligands amounts
Further to a previous communication,[11] here we report
on the stepwise degradation of trifluoromethyl groups in the
homoleptic organoplatinum(II) derivative [NBu4]2[Pt
(1) promoted by Brønsted acids, H2O or HCl(aq), affording
the complete series of mononuclear [NBu4][Pt-
ACHTUGNTERN(NUNG CF3)4]
À
(CF3)3ÀxClx(CO)] compounds (x=0–2). Indirect evidence
for the intermediacy of highly electrophilic [Pt]=CF2 species
has been attained through the isolation and structural char-
acterization of a donor-stabilized species of the type [Pt]=
CF2·L (see compound 12). The synthesis of the solvento de-
to 360.68. All three Pt CF3 bond lengths are indistinguisha-
ble within the experimental error (206.8(4) pm average
value) regardless of the different nature of the ligands in the
trans position (CF3 vs. CO). These distances do not signifi-
cantly depart from those observed in the homoleptic deriva-
tive 1 (205.0(5) pm average value).[12] The Pt CO bond dis-
tance, 191.3(4) pm, is the longest observed for any Q-
À
rivative cis-[Pt
G
N
lability of the THF ligand, the latter compound can be con-
sidered as a convenient synthon of the “cis-PtACHTNUGTRNEG(UN CF3)2” unit.
Results and Discussion
Stepwise degradation of CF3 groups: The square-planar, ho-
moleptic trifluoromethyl platinum(II) derivative [NBu4]2[Pt-
ACHTUNGTRENNUNG(CF3)4] (1) is a well-behaved species with a fairly high ther-
mal stability: in the solid state, it decomposes at about
2558C (thermogravimetrical analysis). This compound is
known to readily undergo oxidative addition of halogens
(Cl2, Br2, or I2)[12] as well as CF3I.[13] These reactions take
place quantitatively (19F NMR spectroscopy) and in a ster-
eoselective way, giving rise to the corresponding octahedral
organoplatinum(IV) derivatives [NBu4]2ACHTUNTRGENNUG[trans-PtAHCTUNGTRNEN(UGN CF3)4RX]
Figure 1. Displacement-ellipsoid diagram (50% probability) of [Pt-
AHCTUNGTRENNUNG
(CF3)3(CO)]À as found in single crystals of compound 2’. Selected bond
(R/X=Cl/Cl, Br/Br, I/I, CF3/I). Compound 1, however, has
been found to be water sensitive in solution, as it readily
suffers hydrolysis by the simple action of moisture. Thus,
compound 1 in moist Me2CO is quantitatively transformed
À
lengths [pm] and angles [8] with estimated standard deviations: Pt C(1)
À
À
À
À
207.5(4), Pt C(2) 206.3(3), Pt C(3) 206.5(3), Pt C(4) 191.3(4), C(4) O
À
113.4(4), average C F 136.8(4); C(1)-Pt-C(2) 91.1(1), C(1)-Pt-C(3)
175.9(1), C(1)-Pt-C(4) 89.7(1), C(2)-Pt-C(3) 89.5(1), C(2)-Pt-C(4)
171.9(1), C(3)-Pt-C(4) 90.3(1), Pt-C(4)-O 172.3(3), average Pt-C-F
115.1(2), average F-C-F’ 103.3(3).
(19F NMR spectroscopy) into [NBu4][Pt
ACHTUNGTRENNUNG
Chem. Eur. J. 2013, 19, 324 – 337
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
325

J. Forniꢁs et al.
A
(Table 1), thus denoting the least electron density on the
metal center in the case where R=CF3. This fact is in keep-
ing with the high electronegativity assigned to the CF3
group (c=3.49), which is even higher than that of Cl (c=
3.16).[20] The CF3 group also gives rise to the highest n˜(CO)
values within both the [PtivX5(CO)]À and the [AuX(CO)]
monocarbonyl series (X=CF3, Cl, Br).[13,21] All these obser-
vations are incompatible with the recently suggested idea
that the CF3 group should be an even better donor group
than a methyl group.[22]
ular structure is known (Table 1).[15–19] It is still significantly
shorter than that found in the octahedral (OC-6) PtIV car-
Table 1. Spectroscopic (IR) and structural data of the monocarbonyl
platinum(II) compounds QACTHNUTRGNEUNG[PtX3(CO)].
T
N
G
Compound 2 in Me2CO reacts at 08C with an excess of
concentrated HCl(aq) giving rise to [NBu4]ACHTUNGTRENNUNG
N
N
AHCTUNTGERG(NUNN CF3)2Cl(CO)] (3, Scheme 2) in a
(19F NMR spectroscopy). The reaction probably proceeds by
degradation of an additional CF3 group and formation of
[a] In CH2Cl2. [b] Reference [15]. [c] Reference [16]. [d] Reference [17].
[e] Reference [18]. [f] Reference [19].
the intermediate species cis-[PtACTHNUTRGNE(UNG CF3)2(CO)2] that would be
unstable in the presence of ClÀ and would eventually afford
compound 3. From the reaction medium, compound 3 can
be isolated as a white solid in 74% yield. It must be noted
that neutralization of the excess acid is required before at-
tempting to concentrate the initial solution, otherwise, the
product obtained is contaminated with significant amounts
(Ptiv CO:
À
bonyl
derivative
[PPh4][Pt
N
trans CF3-Pt-CO unit within the (SP-4)-[Pt
the (OC-6)-[Pt
(CF3)5(CO)]À anions are surprisingly similar.
The 19F NMR spectrum of compound
in CD2Cl2
(CF3)3(CO)]À and
ACHTUNGTRENNUNG
G
of [NBu4]ACHTNGUTRE[UNNG cis-PtACHTUGNRTNE(NUNG CF3)Cl2(CO)] (4). The latter compound can
2
be obtained in pure form and in good yield (67%) by pro-
longed treatment of compound 2 with a large excess of con-
centrated HCl(aq) at room temperature (Scheme 2). Com-
pound 4 had been previously obtained in 23% yield by reac-
(Figure 2) consists of a quartet at d=À22.1 ppm and a
septet at d=À31.9 ppm in 2:1 integrated ratio straightfor-
wardly assignable to each kind of chemically inequivalent
CF3 groups mutually coupled with J
(19F,19F)=3.9 Hz. Both
tion of [Pt
ACHUGTTRENN(UG CF3)2ACHTUNTGR(EUNNNG nbd)] (nbd=norbornadiene) with
signals are flanked by 195Pt satellites. The rather different
2J(195Pt,19F) values observed (518 vs. 769 Hz) evidence the
higher trans influence of the CF3 group compared with that
of the CO ligand. This difference is not reflected, however,
in the structural parameters (see above).
The IR spectrum of compound 2 (or 2’) in CH2Cl2 shows
a sharp signal at n˜ =2117 cmÀ1 assignable to the n(CO)
mode. This is the highest n˜(CO) value observed for any
known carbonyl derivative with [PtX3(CO)]À stoichiometry
[NBu4]Cl in an attempt to prepare [NBu4]2[{Pt
G
CHTUNGTRENNUNG
Cl)2] (14, see below) that resulted in undesired hydrolysis of
one of the CF3 groups.[14] Compound 4 is remarkably inert
towards acidic attack as noted earlier.[14]
The stereochemistry of compound 3 can be readily estab-
lished by spectroscopic methods. The 19F NMR spectrum of
compound 3 in CD2Cl2 (Figure 3) shows two equally intense
Figure 3. Room-temperature 19F NMR spectrum of compound
CD2Cl2 with spectral parameters indicated. Both signals belong to the
same spin system, as they are mutually coupled with 4J(19F,19F)=4.3 Hz.
The signal marked with an asterisk corresponds to a small amount of
compound 4 present in the sample.
3 in
Figure 2. Room-temperature 19F NMR spectrum of compound
CD2Cl2 with spectral parameters indicated. Both signals belong to the
same spin system, as they are mutually coupled with 4J(19F,19F)=3.9 Hz.
2
in
ACHTUNGTRENNUNG
N
326
www.chemeurj.org
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 324 – 337

Trifluoromethyl Platinum(II) Compounds
FULL PAPER
signals (d=À16.5, À34.9 ppm) that belong to the same spin
system as they are mutually coupled with a common 4J-
A
with decreasing electronegativity of the halogen (Figure 4).
This effect was also observed within the related [NBu4]
ACHTUNGTRENNUNG
2ACHTUNGTRENNUNG
[Ptiv-
(19F,19F)=4.3 Hz. These signals correspond to the two chem-
ically inequivalent CF3 groups in a cis arrangement. They
2
are flanked by 195Pt satellites with J(195Pt,19F) values of 833
and 722 Hz, respectively. By analogy with the spectroscopic
properties of compound 2 we assign the lower-frequency
signal to the CF3 group trans to the CO ligand. It is interest-
ing to note that the n˜(CO) value in the IR spectrum of com-
pound 3 in CH2Cl2 (n˜ =2119 cmÀ1) is not significantly differ-
ent than that observed for compound 2 (n˜ =2117 cmÀ1).
Thus, replacement of a CF3 group by a Cl ligand in a cis po-
À
sition has a little effect on the Pt CO unit. On the other
hand, the n˜(CO) value of compound 4 in CH2Cl2 shows a
distinct drop. The observed value (n˜ =2100 cmÀ1) is close to
that reported for the chloro-carbonyl derivative
[PtCl3(CO)]À under the same conditions (n˜ =2098 cmÀ1)[16]
and hence points to the CO ligand being located trans to Cl
in agreement with the cis geometry previously assigned to
compound 4.[14]
Figure 4. 19F NMR chemical shifts observed in the doubly charged species
(SP-4)-[Pt
(CF3)3X]2À (X=Cl, Br, I) with long bars representing the posi-
AHCTUNGTRENNUNG
tions of mutually trans-standing CF3 groups. The corresponding
2J(195Pt,19F) values [Hz] are given in parentheses.
increased electron density on the metal in the order Cl<
Br<I would favor the overlap between filled F(p) and M(d)
orbitals and hence the downfield shift of the resonance as
the result of paramagnetic screening.[23] However, the signals
corresponding to the CF3 group trans to X show the oppo-
site trend (Figure 4). The result is that the separation be-
tween the signals corresponding to the chemically inequiva-
lent CF3 groups, Dd, decreases with the decreasing electro-
negativity of X. Both signals become almost coincident and
even reverse their positions with the heaviest halogen atom
CO replacement reactions: Given the ease with which com-
pound 2 is obtained as well as its reasonable stability, we de-
cided to further examine its chemical behavior. Compound
2 was found to react with trimethylamine N-oxide, ONMe3,
in the presence of a number of neutral or anionic ligands
(Scheme 3) affording a series of singly or doubly charged
2
X=I. The J(195Pt,19F) values associated with the septet sig-
nals (ꢀ940 Hz) are substantially larger than those associat-
ed with the quartet ones (ꢀ520 Hz). This fact is assignable
to the much higher trans influence of the CF3 group in com-
parison with the halo ligands.[24]
The 19F NMR spectra of the singly charged [NBu4][Pt-
AHCTUNGTRENNG(UN CF3)3(L)] compounds (5–8) show less-defined trends, as ex-
pected from the diversity of the donor atoms as well as from
the different p-donor/-acceptor abilities of each kind of
ligand. Thus, in compound 8 containing the s- and p-donor
ligand THT, the quartet appears more shielded than the
septet, the latter signal showing a substantially larger
2J(195Pt,19F) value (868 Hz) than the former one (490 Hz). In
compound 5, which contains the s-donor and p-acceptor
ligand CNtBu, the signals appear in reverse order, that is,
the septet being more shielded than the quartet as in com-
Scheme 3. Synthesis of the mono- or di-anionic tris(trifluoromethyl)plati-
nate(II) derivatives 5–11 by replacement of the CO ligand in compound
2 ([NBu4]+ is the counterion in all cases).
derivatives with the general formulae [NBu4][Pt
[L=CNtBu (5), PPh3 (6), P(o-tolyl)3 (7), tht (8, tht=tetra-
hydrothiophene)] and [NBu4]2[Pt(CF3)3X] [X=Cl (9), Br
ACHTUGNERTN(NUNG CF3)3(L)]
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
(10), I (11)], respectively. All these compounds have been
isolated in reasonable yields and have been characterized by
analytical and spectroscopic methods.
2
pound 2 (L=CO). The J(195Pt,19F) value associated with the
septet is 725 Hz, whereas that associated with the quartet is
529 Hz. The 19F and 31P NMR spectra of compound 6 in sol-
ution are in keeping with those previously observed for the
The 19F NMR spectra of all those compounds but 7 show
a similar pattern to that observed for the parent species 2
(Figure 2) consisting of a quartet and a septet with a 2:1 in-
tegrated ratio. The specific spectral parameters for each
compound are given where appropriate in the Experimental
Section. The halo-compounds 9–11 provide a homogeneous
series that is particularly suited for the purposes of compari-
son. The signals corresponding to the mutually trans-stand-
ing CF3 groups are observed to appear at higher frequencies
(PPh3)].[25] The
tetramethylammonium salt [NMe4][PtACTHNUGTRENN(UG CF3)3ACHTUGNTRENNGUN
19F NMR spectrum of compound 7 shows three equally in-
tense signals, denoting that all three CF3 groups are chemi-
cally inequivalent. This would suggest that rotation of the o-
À
tolyl groups about the P C bonds is restricted. In order to
verify the diastereotopic character of the two mutually
trans-standing CF3 groups in compound 7, we sought to gain
Chem. Eur. J. 2013, 19, 324 – 337
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
327

J. Forniꢁs et al.
more detailed structural information on this chemical spe-
cies.
The crystal and molecular structures of [NBu4][Pt-
The dianionic species 9–11 are moisture sensitive and
need to be stored under anhydrous conditions in order to
prevent decomposition. Any of the ligands used other than
CO seems to increase the electron density on the metal
center, thereby enhancing the reactivity of the CF3 groups.
Thus, the action of moisture on compound 9, for instance,
resulted in hydrolytic degradation of one of the mutually
A
ACHTUNGTRENNUNG(o-tolyl)3}] (7) have been determined by single-crys-
A
ACHTUNGTRENNUNG
(Figure 5) is comparable to that observed for compound 2’
trans-standing CF3 groups affording compound
3
(Scheme 4).
Scheme 4. Hydrolytic process undergone by the dianionic tris(trifluoro-
methyl)platinate(II) derivative
9 caused by the action of moisture
([NBu4]+ is the counterion).
Stabilization of a difluorocarbene unit by base coordination:
From the results presented in the previous section it be-
comes clear that: 1) the CO molecule in compound 2 can be
replaced (Scheme 3) by a wide range of ligands, and 2) that
the resulting compounds are more prone to suffer CF3 deg-
radation than the parent species (see, e.g., Scheme 4).
Taking these two experimental features into account, we car-
ried out the reaction of compound 2 with pyridine-2-thiol,
C5H5NS, in the presence of ONMe3 aiming to prepare a
mononuclear[26] or possibly a dinuclear[27] trifluoromethyl
platinum(II) compound containing the deprotonated pyri-
din-2-thiolato, C5H4NSÀ, ligand. Instead, a compound with
Figure 5. Displacement-ellipsoid diagram (50% probability) of [Pt-
A
ACHTUNGTRENNUNG
(o-tolyl)3}]À as found in single crystals of compound 7. Selected
À
À
À
À
C(1) 207.4(2), Pt C(2) 207.7(2), Pt C(3) 207.3(2), Pt P 233.80(6), aver-
À
À
age P C 183.2(2), average C F 137.3(3); C(1)-Pt-C(2) 87.11(9), C(1)-Pt-
C(3) 171.36(9), C(1)-Pt-P 91.14(6), C(2)-Pt-C(3) 86.78(9), C(2)-Pt-P
176.55(6), C(3)-Pt-P 95.27(6), average C-P-Cꢅ 104.1(1), average Pt-P-C
114.48(7), average Pt-C-F 115.48(15), average F-C-Fꢅ 102.8(2).
(Figure 1). Replacement of CO in compound 2’ by a phos-
the formula [NBu4][PtACHTGUNTRENNU(G CF3)2(CF2NC5H4S)] (12) was ob-
À
phine ligand has no significant effect on the Pt CF3 distan-
tained (Scheme 5, upper path), which can be isolated as a
À
ces. In fact, the three Pt CF3 distances in compound 7
(207.5(2) pm average value) are not only indistinguishable
one from another, but also quite similar to those observed
in compound 2’ (see above). The much higher steric demand
of the PACHTUNGTRENNUNG(o-tolyl)3 ligand with respect to CO might be re-
sponsible for the more pronounced bending apart of the mu-
tually trans-standing CF3 groups in the corresponding [Pt-
ACHTUNGTRENNUNG ACHUTNGTERN(NUGN o-tolyl)3. Thus, the C(1)-Pt-
(CF3)3(L)]À with L=CO or P
C(3) angle in 7 (171.36(9)8) clearly departs from linearity.
À
The Pt P distance, 233.80(6) pm, is comparable to that ob-
served in [NMe4][Pt
A
G
cal arrangement of the aryl rings in the phosphine ligand
with approximate local C3 symmetry does not match the
binary local symmetry around the Pt atom and results in the
absence of any symmetry element within the [PtACTHNURGTENN(UG CF3)3{PACHTUTGNREN(NUGN o-
Scheme 5. Experimentally observed (upper path) formation of the five-
membered heterometallacyclic compound 12 together with the suggested
reaction mechanism (lower path) ([NBu4]+ is the counterion in all cases).
tolyl)3}]À species. This makes the two mutually trans-stand-
ing CF3 groups diastereotopic as, in fact, observed in the
19F NMR spectrum of compound 7 in CD2Cl2. Free rotation
À
of the o-tolyl groups about the P C bonds at a sufficiently
high rate (in the NMR time scale) would introduce an appa-
rent symmetry element and would render both mutually
trans-standing CF3 groups chemically and magnetically
equivalent. This point, however, could not be verified be-
cause decomposition of the sample occurred before even ap-
proaching the expected coalescence.
yellowish solid in 77% yield. The reaction outcome, al-
though unexpected, still follows the premises stated above.
The compound originally aimed for in this reaction was ob-
tained by a different procedure (see below).
The precise nature of compound 12 was established by
single-crystal X-ray diffraction methods. The anion [Pt-
328
www.chemeurj.org
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 324 – 337

Trifluoromethyl Platinum(II) Compounds
FULL PAPER
A
(py)-stabilized
E
compound
cis-[(h5-
fluorinated five-membered metallacycle (Figure 6). In the
crystal, although the cation is perfectly ordered, the complex
C5Me5)W(CO)2H(=SiPh2·py)],[35–38] which exhibits a short
À
W Si distance and a long Si N bond length. It is interesting
to note that the fluorinated metallacyclic organonickel(II)
compound I depicted in Scheme 6 was best described “as a
Scheme 6. Cationic five-membered metallacyclic compounds of Group 10
metals ([PF6]À is the counterion in both cases).
Figure 6. Displacement-ellipsoid diagram (50% probability) of [Pt-
ACHTUNGTRENNUNG
(CF3)2(CF2NC5H4S-kC,kS)]À as found in single crystals of compound 12.
The second component of the disorder is omitted for clarity. Selected
phosphine-stabilized carbenium complex rather than a phos-
phonium ylide complex”.[39] On the other hand, the non-flu-
orinated metallacyclic organoplatinum(II) compound II
(Scheme 6) has been described recently to arise by intermo-
À
bond lengths [pm] and angles [8] with estimated standard deviations: Pt
À
À
À
C(1) 200.1(9), Pt C(2) 202.9(9), Pt C(3) 185(2), Pt S 231.0(5), average
À
À
À
À
C FACHTUNGTRENNUNG(CF3) 137.8(14), C(3) N(1) 160(3), C(3) F(7) 142.2(15), C(3) F(8)
À
141.3(16), S C(4) 174(4); C(1)-Pt-C(2) 89.7(3), C(1)-Pt-C(3) 93.5(7),
C(1)-Pt-S 178.2(3), C(2)-Pt-C(3) 176.1(6), C(2)-Pt-S 88.6(3), C(3)-Pt-S
88.2(6), Pt-C(3)-F(7) 122.5(12), Pt-C(3)-F(8) 122.9(12), F(7)-C(3)-F(8)
98.0(13). Standard deviations are thought to be underestimated on ac-
count of the disorder.
À
lecular C N coupling between the carbene carbon-donor
atom of the corresponding alkylidene precursor species and
the heterocyclic nitrogen-donor atom of free 4-dimethylami-
À
nopyridine (py*). The resulting C N distance, 151.2(3) pm,
compares well with that found in N-alkyl pyridinium com-
pounds (see above) and thus points to a pyridinium ylide
structure in this case.[40] Both compounds I and II, as well as
compound 12, seem to benefit from the stabilizing chelate
effect.
anion is disordered over two discrete sites. The disorder con-
sists of a 1808 rotation around the axis bisecting the PtACHTNUGTRNEG(UN CF3)2
unit and thus leading to two alternative locations of the
ligand forming the metallacycle. The C and S donor atoms
of the heterocyclic ligand together with the terminal CF3
groups form a slightly distorted SP-4 environment for the
Ptii center, yet all the donor atoms and the Pt center are in
the same plane. The most salient feature of compound 12 is
the nature of the metallacycle: although, in principle, it
could be considered to be a Pt derivative of a fluorinated N-
ylide ligand,[28] the structural data would suggest that it
could be described as a Pt–difluorocarbene unit stabilized
The 19F NMR spectrum of compound 12 in CD2Cl2 shows
three signals in a 3:3:2 integrated ratio (Figure 7) and is in
keeping with the solid-state structure. The equally intense
signals are assignable to the terminal CF3 groups, whereas
the complex multiplet appearing at d=À55.85 ppm is as-
signed to the CF2 unit. We attribute the signal appearing at
d=À22.5 ppm with 2J(195Pt,19F)=525 Hz to the CF3 group
trans to a carbon atom due to its higher multiplicity. The
2
by base coordination. To begin with, the Pt CF2 distance,
signal appearing at d=À23.6 ppm with J(195Pt,19F)=788 Hz
À
À
185 pm, is shorter than the terminal Pt CF3 single bonds
within the same molecule (201 pm in average), being closer
À
to the Pt CO bond length found in the monocarbonyl deriv-
À
ative 2’, that is, 191.3(4) pm. The Pt CF2 distance in
À
compound 12 is in the range of the Ir CF2 distances
found in structurally characterized difluorocarbene–
iridium compounds such as [Ir
G
ACHTUGNTNERU(NGN =CF2)ACHTUNTREGG(NNUN CO)ACTHUNGTREN(NUGN PPh3)2]
(187.4(7) pm),[29] [(h5-C5Me5)Ir
ACHTUNGTRENNUNG
or [(h5-C5Me5)Ir
ACHTUNGTRENNUNG(=CF2)ACHTUNGTRENNUNG
À
the N(1) C(3) bond length, 160 pm, appears longer than
that typically found for a N C
(sp3) single bond in N-alkyl
À
pyridinium compounds, that is, 148.5(9) pm average.[32] The
latter value is not significantly altered on fluorination of the
(sp3) bond length of 146(1) pm
À
N-alkyl group. Thus, a N C
has been observed in the solid-state structure of 1-(4-dime-
thylaminopyridinium)-1,1,2,2-tetrafluoroethane bromide.[33]
À
The long N C bond found in compound 12 can be consid-
ered as evidence for some dative bond character.[34] Similar
structural features were found, for instance, in the pyridine
Figure 7. Room-temperature 19F NMR spectrum of compound 12 in
CD2Cl2 with spectral parameters indicated.
Chem. Eur. J. 2013, 19, 324 – 337
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
329

J. Forniꢁs et al.
shows lower multiplicity and can thus be assigned to the CF3
group trans to the S atom.
error in spite of the different nature of the donor atoms in
trans positions: a hard and neutral nitrogen atom versus a
À
The reaction of compound 3 with pyridin-2-thiol in the
soft and anionic sulphur atom. These Pt C bond lengths
presence of ONMe3 afforded [NBu4][Pt
G
N
(198.2(4) pm average value) are comparable to those ob-
served in compound 12 (201.5 pm average value). The four-
membered metallacycle in compound 13 is obviously more
strained than the five-membered one in compound 12. The
(13), which was isolated as a yellow solid in reasonable yield
(Scheme 7). This compound is instrumental in order to es-
tablish useful spectroscopic and structural comparisons with
the related metallacyclic derivative 12.
À
slightly elongated Pt S distance found in compound 13
(239.5(1) pm) compared to that observed in compound 12
(231.0 pm), can be assigned to the unfavorable ring strain in
the former case. The overall geometry of the Pt(NC5H4S-
kN,kS) unit in compound 13 is similar to those observed in
the related [Pt(NC5H4S-kN,kS)ACHTUNGTRNEUNG
(PR3)2]+ salts (PR3 =PPh3,[41]
1
= 1,1’-bis(diphenylphosphino)ferrocene.[42]
2
The 19F NMR spectrum of compound 13 in [D6]acetone
(Figure 9) shows two quartet signals at d=À19.8 and
À22.0 ppm, which we respectively assign to the CF3 groups
Scheme 7. Synthesis of the four-membered heterometallacyclic compound
13 ([NBu4]+ is the counterion).
The crystal and molecular structures of compound 13
were established by single-crystal X-ray diffraction methods.
A
ACHTUNGTRENNUNG
drawing of the mononuclear complex anion [Pt-
(CF3)2(NC5H4S-kN,kS)]À is given in Figure 8. The small bite
Figure 9. Room-temperature 19F NMR spectrum of compound 13 in
[D6]acetone with spectral parameters indicated. Both signals belong to
ACHTUNGTRENNUNG
the same spin system, as they are mutually coupled with 4J(19F,19F)=
2.5 Hz.
Figure 8. Displacement-ellipsoid diagram (50% probability) of [Pt-
(CF3)2(NC5H4S-kN,kS)]À as found in single crystals of compound 13. Se-
lected bond lengths [pm] and angles [8] with estimated standard devia-
ACHTUNGTRENNUNG
trans to the sulphur atom and to the nitrogen atom based on
2
the higher value of J(195Pt,19F) associated with the former
À
À
À
À
tions: Pt C(1) 197.4(4), Pt C(2) 199.1(4), Pt N(1) 209.2(3), Pt S
À
À
À
239.5(1), S C(3) 174.2(4), N(1) C(3) 136.9(4), average C F 137.3(4);
C(1)-Pt-C(2) 91.55(16), C(1)-Pt-N(1) 168.52(14), C(1)-Pt-S 100.00(12),
C(2)-Pt-N(1) 99.84(13), C(2)-Pt-S 168.12(11), N(1)-Pt-S 68.70(8), Pt-S-
C(3) 80.58(12), Pt-N(1)-C(3) 101.6(2), Pt-N(1)-C(7) 138.6(3), N(1)-C(3)-S
109.1(3), average Pt-C-F 115.9(3), average F-C-F’ 102.3(3).
signal (830 vs. 754 Hz). Both signals show a common cou-
4
pling constant of J
N
The synthetic procedures leading to compounds 12
(Scheme 5) and 13 (Scheme 7) can be considered to involve
similar chemical processes. In a first step, the CO ligand in
both precursor species 2 and 3 would be replaced by the
thione tautomer of the C5H5NS ligand (e.g., lower path in
Scheme 5). This is a reasonable assumption, because mono-
dentate kS coordination is the most widespread for the
C5H5S molecule throughout the periodic table.[43] The result-
ing pyridinium species would undergo deprotonation with
abstraction of a neighboring halide and formation of the
corresponding [NHMe3]X salt (X=F, Cl). Abstraction of an
a-fluorine atom in the former case[44] would render a highly
electrophilic difluorocarbene unit that would readily react
with the pyridine nucleophile resulting in an intramolecular
angle of the chelating pyridin-2-thiolato ligand results in an
acute N-Pt-S angle, 68.70(8)8, and consequently in heavy an-
gular distortions around the Pt center from an ideal SP-4 ge-
ometry. The metal coordination environment, although far
from square, is indeed planar, because the sum of the angles
between donor atoms in adjacent positions amounts to
360.1(1)8. The CF3 coordination sites are negligibly affected
by the aforementioned angular distortions, as these ligands
form almost a right angle: C(1)-Pt-C(2): 91.55(16)8. The
À
À
À
Pt C bond distances, Pt C(1): 197.4(4) and Pt C(2):
199.1(4) pm, are indistinguishable within the experimental
À
C N coupling and the eventual formation of the five-mem-
330
www.chemeurj.org
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 324 – 337

Trifluoromethyl Platinum(II) Compounds
FULL PAPER
bered metallacycle found in compound 12 (lower path in
Scheme 5). On the other hand, abstraction of the Pt-bound
Cl ligand in the latter case would result in the four-mem-
bered metallacycle found in compound 13, where the depro-
tonated C5H4NSÀ ligand is acting as a bifunctional ligand
through both its soft and hard donor atoms.
of repeated and alternating CF3 degradation and CO substi-
tution processes.
Synthesis of a “Pt
acted with ONMe3 in the absence of any added ligand, the
dinuclear species [NBu4]2[{Pt(CF3)2}2A(m-Cl)2] (14) is formed
ACHTUGNRTNE(NUNG CF3)2” synthon: When compound 3 is re-
A
CHTUNGTRENNUNG
Nucleophilic substitutions at the Fischer transition-metal
carbene compounds are important chemical processes usual-
ly assumed to proceed through a four-substituted intermedi-
ate.[45] Compound 12 provides a structural model for an
early stage in the referred process, namely that in which the
(Scheme 9). In the absence of any better ligand, the residual
nucleophile approaches the reactive CACTHNUTRGNEUNG
(sp2) center (A in
Scheme 8a). This may be extended to other chemical pro-
Scheme 9. Dimerization undergone by compound 3 under CO extrusion
in the absence of any better ligand ([NBu4]+ is the counterion) together
with the synthesis of the neutral solvent derivative 15.
nucleophilicity of the terminal Cl ligand is able to promote
dimerization of [PtACTHNUTRGNEUNG
(CF3)2Cl]À units giving rise to the double-
bridging system in 14. Compound 14 had purportedly been
detected in solution, but had not been isolated due to its
readiness to suffer hydrolysis.[14] We succeeded in isolating
compound 14 as a white, moisture-sensitive solid in approxi-
mately 60% yield. The 19F NMR spectrum of compound 14
shows a singlet at d=À22.9 ppm flanked by 195Pt satellites
Scheme 8. Suggested reaction paths for nucleophilic attack at metal-
bounded carbene carbon atoms resulting in a) nucleophilic substitution
(generic process) and b) hydrolysis of a difluorocarbene unit.
ACHTUNGTRENNUNGcesses involving nucleophilic attack at a metal-bounded car-
bene carbon atom.[46] In the particular case in which the car-
bene unit is DCF2 and the nucleophile is DOH2, we get a plau-
sible mechanism for the hydrolytic processes undergone by
the trifluoromethyl derivatives 1–3 presented above
(Scheme 2). All these processes can be rationalized with a
common overall reaction path entailing the following steps
(Scheme 8b): 1) acid-promoted activation of an a-fluorine
atom resulting in FÀ loss and formation of a highly electro-
philic difluorocarbene–metal unit; 2) nucleophilic attack at
the carbene carbon atom by the DOH2 molecule giving rise
first to a donor–acceptor adduct A and then to a tetrahedral
ylid species B—sometimes termed alternatively as onium or
zwitterionic; 3) the latter unstable species would further
evolve under formal loss of HF and formation of the metal-
coordinated carbonyl unit. Only the carbonyl derivative, 2,
resulting from the first degradation process in compound 1
seems to be sufficiently stable to be isolated. The dicarbonyl
species presumably resulting from the degradation of any
additional CF3 group would be unstable under the reaction
conditions and would undergo spontaneous replacement of
CO by ClÀ. As indicated above, the Pt-bound CO ligand can
in fact be replaced by a number of better ligands including
ClÀ (Scheme 3). Thus, the whole series of chlorocarbonyl
platinum(II) derivatives 2–4 can be understood as the result
with J(195Pt,19F)=907 Hz. This coupling constant has a simi-
2
lar value to that found for the CF3 group trans to Cl in com-
pound 5 (922 Hz). However, the spectroscopic parameters
observed for compound 14 significantly depart from those
previously reported[14] and thus, the latter most probably
correspond to a different chemical species. At this point, it
is interesting to note that compound 14 regenerates the
parent species 3 (19F NMR and IR spectroscopy) upon treat-
ment with CO at room temperature and under normal pres-
sure (Scheme 9). This fact strongly supports the formulation
of compound 14 as a dinuclear compound with a double-
bridging system that is reversibly formed and broken by CO
loss or uptake.
Compound 14 reacts with the stoichiometrically required
amount of AgClO4 in THF (Scheme 9) affording cis-[Pt-
ACHUTNGREN(NUG CF3)2ACHTUGNTREN(NUGN thf)2] (15). After the appropriate work up, this sol-
vento derivative can be isolated as a yellowish solid in 60%
yield. The 19F NMR spectrum in CD2Cl2 shows a singlet at
2
d=À26.6 ppm flanked by 195Pt satellites with J(195Pt,19F)=
929 Hz. This coupling constant is slightly larger than that
found in the dinuclear precursor species 14. The large
2J(195Pt,19F) value suggests that the CF3 group is trans to a
ligand with moderate trans influence, thus indicating that
compound 15 adopts a global cis geometry in solution.
Chem. Eur. J. 2013, 19, 324 – 337
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
331

J. Forniꢁs et al.
The solid-state stereochemistry of cis-[Pt
has been unambiguously established by single-crystal X-ray
diffraction methods (Figure 10). The sum of the angles be-
(CF3)
E
tion with norbornadiene at room temperature (Scheme 9),
whereby THF is cleanly replaced by the diene molecule,
(nbd)][14,54] in quantitative yield
giving rise to [PtACHTNUGTRNNEUG(CF3)2ACHTUTGNRENNUGN
(19F NMR spectroscopy). This reaction builds a link with
previously established results and qualifies compound 15 as
a convenient synthon of the “PtACHTUNTRGNEUNG(CF3)2” moiety—being even
more efficient than the previously used [Pt
ACHTUGTNERNNUG(CF3)2ACHTUNGTRENNUNG(nbd)]
compound.[14,54]
Conclusion
Increasingly harsher conditions are required (Scheme 2) to
achieve the stepwise degradation of CF3 groups in the ho-
moleptic trifluoromethyl platinum(II) derivative [NBu4]2[Pt-
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
latter compound with an excess of concentrated HCl(aq) at
08C produces degradation of a second CF3 group affording
the chloro-carbonyl derivative [NBu4]ACHTNUGRTENNUG[cis-PtAHCUTGNTREN(NUNG CF3)2Cl(CO)]
Figure 10. Displacement-ellipsoid diagram (50% probability) of cis-[Pt-
(3). An additional CF3 group can be degraded by the action
of an excess of concentrated HCl(aq) on compound 2 at
room temperature, resulting in the stereospecific formation
A
2ACHTUNGTRENNUNG(thf)2] as found in single crystals of compound 15. Selected bond
À
À
À
À
196(1), Pt C(2) 194(1), Pt O(1) 211.4(7), Pt O(2) 211.6(7); C(1)-Pt-C(2)
90.7(4), C(1)-Pt-O(1) 92.0(4), C(1)-Pt-O(2) 175.4(4), C(2)-Pt-O(1)
177.3(4), C(2)-Pt-O(2) 93.9(4), O(1)-Pt-O(2) 83.4(3).
of [NBu4]ACHTNUTRGENNUG[cis-PtACHTUNTGERN(NUGN CF3)Cl2(CO)] (4), which stands further
acidic attack. This provides a complete and, as far as we
know, unprecedented series of trifluoromethyl–metal com-
pounds obtained as the result of acid-promoted a-fluorine
abstraction processes immediately followed by hydrolysis of
the ensuing difluorocarbene–platinum(II) unit (Scheme 8b).
Indirect evidence of the involvement of the [Pt]=CF2 unit
in these degradative processes has been gained through in-
vestigation of the reaction of compound 2 with pydirin-2-
À
tween adjacent ligands amounts exactly to 3608. The Pt C
distances are indistinguishable within the experimental error
(195(1) pm average value) and considerably shorter than
those found in the anionic derivatives 2’ and 7 presented
above (ꢀ207 pm). The crystal and molecular structure of
the neutral species [Pt
G
G
thiol, C5H5NS, whereby [NBu4][PtACHTUGNTERNNU(G CF3)2(CF2NC5H4S-
ported,[47] but the large standard deviation estimated for the
kC,kS)] (12) was formed (Scheme 5). This gem-difluorinated
five-membered metallacyclic compound can, in fact, be con-
sidered as a difluorocarbene–metal derivative stabilized by
intramolecular base coordination in view of its molecular
structure (Figure 6). Moreover, compound 12 is a valid
model for the initial step operating in the many processes
involving nucleophilic attack at an electrophilic carbon atom
(Scheme 8a)—in particular in the hydrolysis of [M]=CF2 to
À
corresponding Pt CF3 bond lengths (202(4) and 207(4) pm)
precludes detailed comparison with the current results. The
À
Pt O distance (211.5(7) pm average value) is significantly
shorter than that found in the neutral zwitterionic species
[{Ph2B
is, in turn, comparable to the Pd O distance in the related
solvento compound cis-[Pd(C6F5)2A
(thf)2]: 212.1(3) pm.[49]
ACHTUNGTRENNUNG ACHTUNGTRENNUGN
(CH2PPh2)2-k2P}PtMe(thf)]·2THF: 217.0(4) pm.[48] It
À
N
CHTUNGTRENNUNG
À
This resemblance is in keeping with the similar covalent
give [M] CO (Scheme 8b).
radii assigned to Pd and Pt atoms when involved in single
The stability of the unusual species 12 may be mainly due
to the absence of substituents at the pyridine nitrogen atom
that might act as suitable leaving groups. The chelating
effect of the bidentate ligand will probably add to the global
stabilization of the metallacyclic compound. The synthesis
bonds: r1(Pd)=120 pm versus r1(Pt)=123 pm.[50] The Pt
À
À
CF3 distance in compound 15 is also similar to the Pd C6F5
distance in cis-[Pd
N
G
regardless of the presumably different hybridization of the
carbon donor atom in each case.
of compound [NBu4][PtACHTUNGTRNE(GNU CF3)2(NC5H4S-kN,kS)] (13) contain-
By using the Ahrland–Chatt–Davies classification,[51] Ptii
ing a more strained four-membered metallacycle is also re-
ported. The structural features of compounds 12 (Figure 6)
and 13 (Figure 8), which differ only in terms of the presence
or absence of a difluorocarbene CF2 unit inserted in the Pt
N bond, are suitably compared.
The CO ligand in the carbonyl derivative 2 can be re-
placed, in the presence of ONMe3, by a number of neutral
(L) or anionic (XÀ) ligands giving rise to a variety of mono-
is considered as a class b acidic center, whereas THF be-
ii
À
longs to the class a ligands. This means that the Pt OC4H8
bond should not be particularly strong.[52] Furthermore, the
THF ligand would be expected to be highly labile as it has
been found, for instance, in the related perhalophenyl deriv-
À
atives cis-[Pt
THF ligands in compound 15 has been confirmed by reac-
ACHTUNGTRENNUNG(C6X5)2ACHTUNGTRENNUNG
(thf)2] (X=F, Cl).[53] The lability of the
332
www.chemeurj.org
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 324 – 337

Trifluoromethyl Platinum(II) Compounds
FULL PAPER
(0.75 g, 1.11 mmol) in Me2CO (25 cm3) at 08C (ice bath). After four days
of stirring at that temperature, the reaction medium was neutralized with
an aqueous solution of K2CO3 and the white precipitate formed was fil-
tered off. The filtrate was concentrated to dryness and the resultant resi-
due was washed with H2O (3ꢆ5 cm3), vacuum dried, and re-dissolved in
CH2Cl2 (10 cm3). The solution was dried with anhydrous MgSO4, which
was subsequently filtered off. The filtrate was concentrated to dryness
and by treating the resultant residue with Et2O (5 cm3) a white solid
formed, which was filtered, washed with n-hexane (2ꢆ3 cm3) and vacuum
nuclear trifluoromethyl platinum(II) derivatives with the
general formulae [NBu4][Pt
ACHTUNGNERT(UNNG CF3)3(L)] (5–8) and [NBu4]2[Pt-
ACHTUNGTRENNUNG
ONMe3-assisted extrusion of the CO ligand in the carbonyl
derivative 3 gives rise, in the absence of any added ligand,
to the dinuclear species [NBu4]2[{Pt
which is itself a suitable precursor of the solvento derivative
cis-[Pt(CF3)2A(thf)2] (15). The THF ligands in the latter com-
pound are more labile than the diene ligands in the well-
known species [Pt(CF3)2A
(cod)][55] (cod=1,5-cyclooctadiene)
and [Pt(CF3)2A
(nbd)].[14,47] Compound 15 can thus be consid-
ACHTUNTGRNENGU(CF3)2}2HCATUNGTRENN(GUN m-Cl)2] (14),
A
CHTUNGTRENNUNG
dried to give compound
3
(0.53 g, 0.83 mmol, 74%). 19F NMR
(282.231 MHz, CD2Cl2): d=À16.5 (q, 4J
AHCTUNGTRENNUNG
(19F,19F)=4.3, 2J(195Pt,19F)=
A
U
833 Hz, 3F; CF3 trans to Cl), À34.9 ppm (q, 2J(195Pt,19F)=722 Hz, 3F;
ꢁ
CF3 trans to CO); IR (KBr): n˜ =2967 (s), 2878 (m), 2117 (s, C O), 1486
A
CHTUNGTRENNUNG
(s), 1467 (m), 1383 (m), 1261 (w), 1141 (vs), 1092 (vs), 1029 (vs), 1007
ered as a more convenient synthon of the “cis-PtACHTNUGTRNEG(UN CF3)2”
unit.
(vs), 997 (vs), 880 (m, [NBu4]+), 800 (m), 741 (m, [NBu4]+), 712 (w), 543
(w), 493 (w), 319 cmÀ1 (w, Pt Cl); IR (CH2Cl2): n˜ =2119 cm (s, CO); el-
À1
À
emental analysis calcd (%) for C19H36ClF6NOPt: C 35.7, H 5.7, N 2.2;
found: C 35.6, H 5.5, N 2.3.
Synthesis of [NBu4]ACHTUNTRGENN[GU cis-PtACHTUGNTREN(NUGN CF3)Cl2(CO)] (4): An excess of concentrated
HCl(aq) (0.46 cm3, 5.57 mmol) was added to a solution of compound 2
(0.25 g, 0.37 mmol) in Me2CO (10 cm3) at room temperature and the mix-
ture was stirred for 12 h at room temperature. The reaction medium was
concentrated to dryness. By treating the resulting residue with iPrOH
(5 cm3) a white solid formed, which was filtered, washed with n-hexane
(2ꢆ3 cm3), and vacuum dried to yield compound 4 (0.15 g, 0.25 mmol,
67%). Multinuclear NMR spectroscopic properties in solution are in
keeping with literature values;[14] IR (KBr): n˜ =2967 (s), 2874 (w), 2096
Experimental Section
General procedures and materials: Unless otherwise stated, the reactions
and manipulations were carried out under purified argon by using
Schlenk techniques. Solvents were dried by using an MBraun SPS-800
System. Compound [NBu4]2[PtACTHNUTRGNE(UGN CF3)4] (1) was obtained as described else-
where.[12] Elemental analyses were carried out by using a Perkin–Elmer
2400 CHNS/O Series II microanalyzer. IR spectra of KBr discs were re-
corded on the following Perkin–Elmer spectrophotometers: 883 (4000–
200 cmÀ1) or Spectrum One (4000–350 cmÀ1); an ATR device was used
to register the IR spectrum of compound 15 in order to avoid substitu-
tion of the highly labile THF ligand. NMR spectra were recorded on any
of the following spectrometers: Varian Gemini-300, Bruker ARX 300, or
Bruker ARX 400. Unless otherwise stated, the spectroscopic measure-
ments were carried out at room temperature. Chemical shifts of the
measured nuclei (d in [ppm]) are given with respect to the standard refer-
ences in use: SiMe4 (1H and 13C), CFCl3 (19F), and 85% aqueous H3PO4
(31P). NMR parameters associated with the cations are unexceptional and
are therefore omitted.
ꢁ
(vs, C O), 1485 (m), 1465 (w), 1383 (w), 1142 (m), 1108 (vs), 1030 (vs),
881 (m, [NBu4]+), 800 (w), 741 (m, [NBu4]+), 553 (w), 504 (w), 492 (w),
À1
À1
À
À
ꢁ
344 (w, Pt Cl), 304 cm (w, Pt Cl); IR (CH2Cl2): n˜ =2100 cm (s, C
O); elemental analysis calcd (%) for C18H36Cl2F3NOPt: C 35.7, H 6.0, N
2.3; found: C 35.8, H 5.8, N 2.3.
Synthesis of [NBu4][PtACHTNURGTNENUG(CF3)3CAHTUNGTRNEN(UGN CNtBu)] (5): ONMe3 (28 mg, 0.37 mmol)
was added to a solution of compound 2 (0.25 g, 0.37 mmol) and CNtBu
(0.21 cm3, 1.86 mmol) in CH2Cl2 (15 cm3) at room temperature. After 2 h
of stirring, the solution was concentrated to dryness. By treating the re-
sulting residue with iPrOH (2 cm3) at 08C, a white solid formed, which
was filtered, washed with cold iPrOH (2 cm3) and n-hexane (3 cm3), and
vacuum dried to give compound 5 (0.19 g, 0.26 mmol, 70%). 1H NMR
(300 MHz, CD2Cl2): d=1.51 ppm (CMe3); 19F NMR (282.231 MHz,
Synthesis of [NBu4][PtACHTUNGTRENNUNG(CF3)3(CO)] (2): Compound 1 (1.50 g, 1.57 mmol)
was dissolved in wet Me2CO (25 cm3) and after four days at room tem-
perature under air, the solvent was evaporated to dryness. Treatment of
the resulting residue with iPrOH (5 cm3) gave rise to a white solid, which
was filtered, washed with n-hexane, and vacuum dried to give compound
2
4
CD2Cl2): d=À22.22 (q, J(195Pt,19F)=529, J
G
ly trans-standing CF3), À27.28 ppm (septet, J(195Pt,19F)=725 Hz, 3F; CF3
2
trans to CNtBu); IR (KBr): n˜ =2970 (m), 2880 (w), 2218 (s, C N), 1481
2 (0.86 g, 1.28 mmol, 82%). 13C
N
(m), 1461 (w), 1376 (w), 1146 (vs), 1084 (vs), 1024 (m), 993 (vs), 959 (m),
883 (w, [NBu4]+), 799 (w), 739 cmÀ1 (w, [NBu4]+); elemental analysis
calcd (%) for C24H45F9N2Pt: C 39.6, H 6.2, N 3.85; found: C 39.4, H 6.0,
N 3.8.
ACHTUNGTRENNUNG
2J(195Pt,19F)=518, 4J(19F,19F)=3.9 Hz, 6F; mutually trans-standing CF3),
Synthesis of [NBu4][PtACHTUNGTRENN(UG CF3)3ACHTUNGTREN(NUGN PPh3)] (6): ONMe3 (28 mg, 0.37 mmol) was
À31.90 ppm (septet, 2J(195Pt,19F)=769 Hz, 3F; CF3 trans to CO); IR
added to a solution of compound 2 (0.25 g, 0.37 mmol) and PPh3 (0.29 g,
1.11 mmol) in CH2Cl2 (15 cm3) at room temperature. After 2 h of stirring,
the solution was concentrated to dryness. By treating the resulting resi-
due with Et2O (3ꢆ5 cm3), a white solid formed, which was filtered and
vacuum dried to give compound 6 (0.26 g, 0.29 mmol, 77%). The NMR
(KBr): n˜ =2968 (s), 2879 (m), 2121 (s, C O), 1475 (s), 1381 (w), 1255
(m), 1158 (s), 1135 (m), 1096 (vs), 1081 (s), 1014 (vs), 977 (s), 895 (w),
880 (w, [NBu4]+), 801 (w), 738 (w, [NBu4]+), 547 cmÀ1 (w); IR (CH2Cl2):
n˜ =2117 cmÀ1 (s, C O); elemental analysis calcd (%) for C20H36F9NOPt:
ꢁ
(PPh3)]À in
spectroscopic properties associated with the anion [PtACHTNUGTRENN(UG CF3)3ACHTUTGNRENNUGN
C 35.7, H 5.4, N 2.1; found: C 35.9, H 5.45, N 2.1.
solution are in keeping with those reported for the [NMe4]+ salt;[25] IR
(KBr): n˜ =2965 (m), 2935 (w), 2876 (m), 1482 (m), 1458 (sh), 1438 (m),
1382 (w), 1315 (w), 1139 (s), 1099 (m), 1073 (vs), 988 (vs), 938 (w), 893
(w), 881 (w, [NBu4]+), 803 (w), 744 (m), 698 (m), 532 (m), 511 (w), 498
(w), 375 (w), 363 cmÀ1 (w); elemental analysis calcd (%) for
C37H51F9NPPt: C 49.0, H 5.7, N 1.5; found: C 48.9, H 5.6, N 1.6.
Synthesis of [PPh4][PtACHTUNGTRENNUNG(CF3)3(CO)] (2’): Compound 2’ was obtained in
92% yield by metathesis of compound 2 with [PPh4]Br in Me2CO/iPrOH
at room temperature. 19F NMR data in CD2Cl2 are coincident with those
ꢁ
of compound 2; IR (KBr): n˜ =2106 (vs, C O), 1587 (w), 1485 (m), 1438
(s), 1340 (w), 1316 (w), 1189 (w), 1149 (vs), 1110 (vs), 1094 (vs), 1033 (s),
1019 (vs), 1008 (vs), 995 (s), 975 (s), 848 (w), 754 (m), 751 (m), 724 (s),
689 (s), 527 (vs), 444 (w), 294 cmÀ1 (w); IR (CH2Cl2): n˜ =2117 cmÀ1 (s,
CO); elemental analysis calcd (%) for C28H20F9OPPt: C 43.7, H 2.6;
found: C 43.55, H 2.5.
Synthesis of [NBu4][Pt
N
ACHTUNGTRENNUNG
pared from compound
2
PACHTUNGTRENNUNG
1.11 mmol), and ONMe3 (28 mg, 0.37 mmol) by using a similar procedure
to that just described for the synthesis of compound 6. Complex 7 was
obtained as a white solid (0.24 g, 0.25 mmol, 68%). 1H NMR (400 MHz,
CD2Cl2): d=7–9 (overlapping m, 12H; aromatic), 1.84 (brs, 3H; CH3),
1.42 ppm (brs, 6H; CH3); 19F NMR (376.308 MHz, CD2Cl2): d=À21.47
(brd, 2J(195Pt,19F)=467 Hz, 3F; one of the mutually trans-standing CF3),
Crystals suitable for X-ray diffraction analysis were obtained by slow dif-
fusion of a layer of iPrOH (15 cm3) into a solution of 15 mg of compound
2’ in Me2CO (15 cm3) at 48C.
Synthesis of [NBu4]
ACHTUNGTRENNUNG[cis-PtAHCTUNTGRNE(NUGN CF3)2Cl(CO)] (3): An excess of concentrated
HCl(aq) (1.38 cm3, 16.72 mmol) was added to a solution of compound 2
Chem. Eur. J. 2013, 19, 324 – 337
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
333

J. Forniꢁs et al.
À23.62 (brd, 2J(195Pt,19F)=468 Hz, 3F; one of the mutually trans-stand-
and C5H5NS (45 mg, 0.41 mmol) in CH2Cl2 (15 cm3) at room temperature.
After 3 h of stirring, the solution was concentrated to dryness. By treating
the resulting residue with iPrOH (3 cm3) at 08C, a yellowish solid
formed, which was filtered, washed with cold iPrOH (2ꢆ2 cm3) and n-
hexane (3 cm3), and vacuum dried to yield compound 12 (0.21 g,
0.28 mmol, 77%). 1H NMR (400 MHz, CD2Cl2): d=8.11 (ddd, 3J-
ing CF3), À24.54 ppm (d, 3J
(31P, 19F)=56, 2J(195Pt,19F)=728 Hz, 3F; CF3
ACHTUNGTRENNUNG
trans to P); 31P{1H} NMR (161.923 MHz, CD2Cl2): d=20.47 ppm (q of
not well-resolved septets, 3J
G
G
1J(195Pt,31P)=2169 Hz); IR (KBr): n˜ =2964 (m), 2935 (sh), 2877 (m), 1592
(w), 1566 (w), 1473 (m), 1469 (m), 1382 (m), 1279 (w), 1204 (w), 1136 (s),
1074 (vs), 1018 (m), 994 (vs), 883 (w, [NBu4]+), 803 (w), 757 (m), 722 (w),
562 (w), 539 (w), 517 (w), 481 (m), 466 cmÀ1 (sh); elemental analysis
calcd (%) for C40H57F9NPPt: C 50.6, H 6.05, N 1.5; found: C 49.8, H 6.5,
N 1.1.
A
R
ACHTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
Crystals suitable for X-ray diffraction analysis were obtained by slow dif-
fusion of a layer of n-hexane (10 cm3) into a solution of compound 7
(15 mg) in CH2Cl2 (5 cm3) at 48C.
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
Synthesis of [NBu4][Pt
ACHTUNGTRENNUNG(CF3)3ACHTUNGTREN(NGUN tht)] (8): Compound 8 was prepared from
(282.231 MHz, CD2Cl2): d=À22.5 (br, 2J(195Pt,19F)=525 Hz, 3F; CF3
trans to C), À23.6 br, 2J(195Pt,19F)=788 Hz, 3F; CF3 trans to S),
À55.85 ppm (br, 2J(195Pt,19F)=392 Hz, 2F; CF2); IR (KBr): n˜ =2965 (s),
2877 (m), 1618 (s), 1546 (s), 1480 (s), 1463 (s), 1419 (s), 1380 (w), 1270
(m), 1262 (m), 1180 (w), 1130 (vs), 1107 (m), 1073 (vs), 1051 (s), 1014
(vs), 985 (vs), 959 (vs), 881 (w; [NBu4]+), 841 (m), 801 (w), 776 (m), 749
(w), 738 (w, [NBu4]+), 666 (w), 597 (w), 493 (w), 478 (w), 372 cmÀ1 (w);
elemental analysis calcd (%) for C24H40F8N2PtS: C 39.2, H 5.5, N 3.8, S
4.4; found: C 40.15, H 5.7, N 4.0, S 5.0.
compound
2
(0.25 g, 0.37 mmol), THT (0.16 cm3, 1.86 mmol), and
ONMe3 (28 mg, 0.37 mmol) by using a similar procedure to that just de-
scribed for the synthesis of compound 5. Complex 8 was obtained as a
white solid (0.20 g, 0.27 mmol, 73%). Elemental analysis calcd (%) for
C23H44F9NPtS: C 37.7, H 6.05, N 1.9, S 4.4; found: C 37.4, H 5.9, N 2.0, S
4.3. IR (KBr): n˜ =2966 (m), 2878 (w), 1525 (w), 1474 (w), 1383 (w), 1257
(w), 1146 (s), 1082 (vs), 1051 (w), 1021 (sh), 995 (s), 883 (w, [NBu4]+),
805 (w), 739 (w, [NBu4]+), 504 cmÀ1 (w); 1H NMR (400 MHz, CD2Cl2):
d=3.08 (m, 3J 195Pt,1H)=25 Hz, 4H; a-CH2), 1.90 ppm (m, 4H; b-CH2);
ACHTUNGTRENNUNG(
19F NMR (376.308 MHz, CD2Cl2): d=À22.0 (septet, 4J
(19F,19F)=3.8,
ACHTUNGTRENNUNG
Crystals suitable for X-ray diffraction analysis were obtained by slow dif-
fusion of a layer of n-hexane (15 cm3) into a solution of compound 12
(15 mg) in CH2Cl2 (5 cm3) at 48C.
2J(195Pt,19F)=868 Hz, 3F; CF3 trans to THT), À24.1 ppm (q,
2J(195Pt,19F)=490 Hz, 6F; mutually trans-standing CF3).
Synthesis of [NBu4][PtACHTUNTRGNEUNG(CF3)2(NC5H4S-kN,kS)] (13): Compound 13 was
Synthesis of [NBu4]2[PtACHTUNGTRNEU(NG CF3)3Cl] (9): ONMe3 (28 mg, 0.37 mmol) was
prepared from compound 3 (0.25 g, 0.39 mmol), pyridin-2-thiol (48 mg,
0.43 mmol), and ONMe3 (30 mg, 0.39 mmol) by using a similar procedure
to that just described for the synthesis of compound 5. Upon mixing the
reagents, a slight precipitate formed (probably [NHMe3]Cl), which was
filtered off before proceeding farther. Complex 13 was obtained as a
added to a solution of compound 2 (0.25 g, 0.37 mmol) and [NBu4]Cl
(0.52 g, 1.86 mmol) in CH2Cl2 (15 cm3) at room temperature. After 2 h of
stirring, the solution was concentrated to dryness. By treating the result-
ing residue with iPrOH (3 cm3) at 08C, a white solid formed, which was
filtered, washed with cold iPrOH (2ꢆ2 cm3) and n-hexane (3 cm3) and
vacuum dried to give compound 9 (0.24 g, 0.26 mmol, 70%). 19F NMR
1
yellow solid (0.15 g, 0.22 mmol, 56%). H NMR (400 MHz, [D6]acetone):
d=7.91 (ddd, 3J(H5,H6)=5.3, 4J(H4,H6)=1.7, 3J(195Pt,1 H)=31 Hz, 1H;
ACTHNUTRGENNUG CAHTUNGTRENNUGN
4
2
(282.231 MHz, CD2Cl2): d=À16.49 (septet, J
(19F,19F)=3.8, J(195Pt,19F)=
ACHTUNGTRENNUNG
H6), 7.26 (ddd, 3J
(H3,H5)ꢀ0.8 Hz, 1H; H5), 6.49 ppm (ddd, 1H; H3); 13C
(100.577 MHz, [D6]acetone): d=182.03 (CS), 145.46 (d, 1J
177 Hz, C4H), 136.24 (d, 1J(1 H,13C)=162 Hz; C6H), 127.45 (d, 1J-
(1 H,13C)=174 Hz; C3H), 124 (s, 1J(195Pt,13C)=1921 Hz; CF3 trans to S),
116.07 (d, 1J(1 H,13C)=168 Hz; C5H), 114.95 ppm (s, 1J(195Pt,13C)=
(H3,H4)=8.2, 3J
ACHUTGTNRENNUG CAHTUNGTRENNUNG
922 Hz, 3F; CF3 trans to Cl), À24.72 ppm (q, 2J(195Pt,19F)=517 Hz, 6F;
mutually trans-standing CF3); IR (KBr): n˜ =2964 (vs), 2876 (s), 1482 (vs),
1419 (w), 1383 (m), 1349 (w), 1169 (w), 1139 (s), 1071 (vs), 1063 (vs),
1006 (s), 985 (vs), 957 (vs), 907 (m), 892 (m), 877 (m, [NBu4]+), 797 (w),
A
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
+
À1
À
ACHTUNGTRENNUNG
748 (m, [NBu4] ), 327 (m, Pt Cl), 314 cm (w); elemental analysis calcd
AHCTUNGTRENNUNG
(%) for C35H72ClF9N2Pt: C 45.6, H 7.9, N 3.0; found: C 45.6, H 8.0, N
3.0.
1923 Hz; CF3 trans to N); 19F NMR (376.308 MHz, [D6]acetone): d=
À19.8 (q, 4J
(19F,19F)=2.5, 2J(195Pt,19F)=830 Hz; CF3 trans to S),
ACHTUNGTRENNUNG
Synthesis of [NBu4]2[Pt
ACHTUNGTRENNUNG(CF3)3Br] (10): Compound 10 was prepared from
À22.02 ppm (q, J(195Pt,19F)=754 Hz; CF3 trans to N); IR (KBr): n˜ =2962
(s), 2877 (s), 1613 (w), 1582 (vs), 1552 (w), 1483 (s), 1459 (m), 1445 (m),
1427 (s), 1381 (m), 1275 (w), 1243 (w), 1128 (vs), 1100 (m), 1070 (vs),
1041 (m), 1017 (vs), 982 (vs), 957 (sh), 882 (m; [NBu4]+), 801 (w), 761 (s),
739 (w, [NBu4]+), 729 (m), 652 (w), 494 (w), 462 (w), 420 cmÀ1 (w); ele-
mental analysis calcd (%) for C23H40F6N2PtS: C 40.3, H 5.9, N 4.1, S 4.7;
found: C 40.1, H 5.7, N 4.4, S 4.7.
2
compound (0.25 g, 0.37 mmol), [NBu4]Br (0.60 g, 1.86 mmol), and
2
ONMe3 (28 mg, 0.37 mmol) by using a similar procedure to that just de-
scribed for the synthesis of compound 9. Complex 10 was obtained as a
white solid (0.27 g, 0.28 mmol, 75%). 19F NMR (282.231 MHz, CD2Cl2):
4
2
d=À18.31 (septet, J
ACHTUNGTRENNUNG
(19F,19F)=4.1, J(195Pt,19F)=947 Hz, 3F; CF3 trans to
Br), À23.86 ppm (q, 2J(195Pt,19F)=519 Hz, 6F; mutually trans-standing
CF3); IR (KBr): n˜ =2962 (vs), 2875 (s), 1482 (vs), 1420 (w), 1382 (m),
1348 (w), 1166 (w), 1137 (s), 1071 (vs), 1060 (vs), 1010 (s), 985 (vs), 960
(vs), 906 (m), 886 (m), 877 (m, [NBu4]+), 802 (w), 786 (w), 740 cmÀ1 (m,
[NBu4]+); elemental analysis calcd (%) for C35H72BrF9N2Pt: C 43.5, H
7.5, N 2.9; found: C 43.6, H 7.85, N 2.8.
Crystals suitable for X-ray diffraction analysis were obtained by slow dif-
fusion of a layer of n-hexane (15 cm3) into a solution of compound 13
(15 mg) in CH2Cl2 (5 cm3) at 48C.
Synthesis of [NBu4]2[{Pt
N
2ACHTUNGERTN(NUNG m-Cl)2] (14): Compound 14 was pre-
pared from compound
3
Synthesis of [NBu4]2[PtACHTUNGTRENNUNG(CF3)3I] (11): Compound 11 was prepared from
0.78 mmol) by using a similar procedure to that just described for the
synthesis of compound 5. Complex 14 was obtained as a white solid
(0.28 g, 0.23 mmol, 58%).19F NMR (282.231 MHz, CD2Cl2): d=
À22.89 ppm (s, 2J(195Pt,19F)=907 Hz); IR (KBr): n˜ =2966 (m), 2877 (w),
1470 (s), 1383 (w), 1261 (w), 1127 (vs), 1096 (m), 1069 (vs), 1046 (vs), 987
(vs), 926 (w), 878 (m, [NBu4]+), 801 (w), 739 (s), 711 (w), 482 (w), 328
compound (0.25 g, 0.37 mmol), [NBu4]I (0.69 g, 1.86 mmol), and
2
ONMe3 (28 mg, 0.37 mmol) by using a similar procedure to that just de-
scribed for the synthesis of compound 9. Complex 11 was obtained as a
white solid (0.31 g, 0.31 mmol, 82%). 19F NMR (282.231 MHz, CD2Cl2):
d=À19.48 (central signal heavily overlapped with the other one,
2J(195Pt,19F)=520 Hz, 6F; mutually trans-standing CF3), À19.53 ppm (cen-
tral signal heavily overlapped with the other one, 2J(195Pt,19F)=947 Hz,
3F; CF3 trans to I); IR (KBr): n˜ =2959 (vs), 2874 (s), 1481 (s), 1420 (w),
1382 (m), 1348 (w), 1166 (w), 1134 (s), 1109 (m), 1069 (vs), 1012 (s), 983
(vs), 969 (vs), 897 (m), 893 (m), 880 (m, [NBu4]+), 798 (w), 738 (m,
[NBu4]+), 506 cmÀ1 (w); elemental analysis calcd (%) for C35H72F9IN2Pt:
C 41.5, H 7.2, N 2.8; found: C 41.5, H 7.5, N 3.0.
(m, Pt Cl), 310 cmÀ1 (m); elemental analysis calcd (%) for
À
C18H36ClF6NPt: C 35.4, H 5.9, N 2.3; found: C 35.1, H 6.05, N 2.2.
Synthesis of cis-[PtACTHUNTRGENN(UG CF3)2AHCTUNGTREN(NUGN thf)2] (15): AgClO4 (85 mg, 0.41 mmol) was
added to a solution of compound 14 (0.25 g, 0.20 mmol) in THF (20 cm3)
at 08C under light exclusion and the mixture was stirred at the same tem-
perature for 1 h. The resulting suspension was evaporated to dryness, the
residue was extracted with Et2O (30 cm3), and the insoluble components
(AgCl and [NBu4]ClO4) were filtered off. The filtrate was evaporated to
Synthesis of [NBu4][Pt
ACHTUNGTRENNUNG(CF3)2(CF2NC5H4S-kC,kS)] (12): ONMe3 (28 mg,
0.37 mmol) was added to a solution of compound 2 (0.25 g, 0.37 mmol)
334
www.chemeurj.org
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 324 – 337

Trifluoromethyl Platinum(II) Compounds
FULL PAPER
Table 2. Crystal data and structure refinement for compounds 2’, 7, 12, 13, and 15.
2’
7
12
13
C23H40F6N2PtS
15
formula
Mr
C28H20F9OPPt
769.50
C40H57F9NPPt
948.93
C24H40F8N2PtS
735.73
C10H16F6O2Pt
477.32
685.72
T [K]
100(2)
100(2)
100(2)
100(2)
100(2)
crystal system
space group
a [pm]
b [pm]
c [pm]
b [8]
orthorhombic
Pca21
2494.52(4)
709.00(2)
1484.80(3)
90
2.62604(10)
4
1.946
5.490
1480
7.6–57.9
15965
5103
monoclinic
P21/n
monoclinic
P21/n
monoclinic
P21/n
monoclinic
C2/c
1006.43(1)
2547.30(2)
1554.01(1)
97.605(1)
3.94894(6)
4
1.596
3.666
1912
7.6–50.2
37360
1140.7(7)
1643.9(10)
1472.7(10)
92.553(11)
2.759(3)
4
1.771
5.232
1456
3.7–50.0
14271
924.89(1)
1739.14(3)
1670.28(3)
91.052(2)
2.68621(7)
4
1.696
5.356
1360
7.7–53.2
17509
1912.99(6)
919.96(3)
1531.49(5)
92.752(3)
2.69212(15)
8
2.355
10.489
1784
7.8–50.2
8778
V [nm3]
Z
1calcd [gcmÀ3
]
m [mmÀ1
(000)
2q range [8]
]
F
A
reflns collected
unique reflns
7001
4865
5603
2391
R
(int)
0.0204
0.0210
0.0753
0.0370
0.0585
transmission max/min
0.8526/0.3294
5103/1/361
R1 =0.0172
wR2 =0.0373
R1 =0.0223
wR2 =0.0379
1.016
0.3149/0.4609
7001/0/469
R1 =0.0168
wR2 =0.0425
R1 =0.0190
wR2 =0.0433
1.065
0.8180/0.4527
4865/553/408
R1 =0.0502
wR2 =0.1007
R1 =0.0865
wR2 =0.1119
1.028
0.8143/0.2232
5603/0/298
R1 =0.0263
wR2 =0.0632
R1 =0.0338
wR2 =0.0672
1.046
0.3022/0.1088
2391/242/238
R1 =0.0357
wR2 =0.0883
R1 =0.0454
wR2 =0.0916
1.016
data/restraints/parameters
final R indices [I>2s(I)][a]
R indices (all data)
GOF[b] on F2
absolute structure parameter
0.011(5)
–
–
–
–
[a] R1 =S(|Fo|À|Fc|)/S|Fo|; wR2 =[Sw(F2oÀF2c)2/Sw(Fc2)2]1/2
;
w=[s2(Fo2)+(g1P)2+g2P]À1
;
P=(1/3)[max{F2o,0}+2Fc2]. [b] Goodness-of-fit=[Sw(Fo2ÀF2c))2/
(nobsÀnparam)]1/2
.
approximately 5 cm3 and n-hexane (30–40 cm3) was added. By allowing
the mixture to stand at À358C for over one day, a yellow solid was ob-
tained, which was filtered and vacuum dried to give compound 15
all the atoms making up one site and the final values adopted were 0.56/
0.44. It has to be considered that correlation among alternative atoms oc-
cupying close sites is bound to induce some distortion in the geometry
determined, yet the connectivity and bond length range are clearly estab-
lished. One of the CF3 groups was disordered adopting two different ro-
1
(0.12 g, 0.25 mmol, 61%). H NMR (300 MHz, CD2Cl2): d=4.02 (m, 4H;
a-CH2), 1.97 ppm (m, 4H; b-CH2); 19F NMR (282.231 MHz, CD2Cl2):
d=À26.6 ppm (s, 2J(195Pt,19F)=929 Hz); IR (ATR): n˜ =2971 (w), 2905
(w), 1484 (w), 1473 (w), 1461 (w), 1367 (w), 1349 (w), 1248 (w), 1142 (s),
À
tational positions around the Pt C bond, as has frequently been encoun-
tered. The occupation for the alternative sites was refined while restrain-
ing the atomic displacement parameters to be similar. In the structure of
compound 15, both the a-CH2 units of the THF ligands and the F atoms
were disordered over two sets of positions. Weak restraints were used in
the geometry and thermal parameters of these disordered atoms. Full-
matrix least-squares refinement of these models against F2 converged to
final residual indices given in Table 2.
À
1111 (m), 1078 (s), 1047 (s), 999 (sh), 978 (vs), 917 (m), 866 (s, THF: C
À
O C),
[56]
826 (m), 716 (w), 689 (w), 542 (w), 532 cmÀ1 (w); elemental
analysis calcd (%) for C10H16F6O2Pt: C 25.2, H 3.4; found: C 25.35, H
3.23.
Crystals suitable for X-ray diffraction analysis were obtained by slow dif-
fusion of a layer of n-hexane (15 cm3) into a solution of compound 15
(15 mg) in CH2Cl2 (5 cm3) at À358C.
X-ray structure determinations: Crystal data and other details of the
structure analyses are presented in Table 2. Suitable crystals for X-ray
diffraction studies, obtained as indicated in the corresponding experimen-
tal entry, were mounted at the end of quartz fibers. The radiation used in
all cases was graphite monochromated MoKa (l=71.073 pm). X-ray in-
tensity data were collected on an Oxford Diffraction Xcalibur diffractom-
eter. The diffraction frames were integrated and corrected for absorption
by using the CrysAlis RED program.[57]
CCDC-749438 (2’), 893040 (7), 749437 (12), 893038 (13), and 893039 (15)
contain the supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge Crystallograph-
ic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements
The structures were solved by Patterson and Fourier methods and refined
by full-matrix least squares on F2 with SHELXL-97.[58] All non-hydrogen
atoms were assigned anisotropic displacement parameters and refined
without positional constraints. All hydrogen atoms were constrained to
idealized geometries and assigned isotropic displacement parameters
equal to 1.2 times the Uiso values of their attached parent atoms (1.5
times for the CH3 atoms). In the structure of compound 12, the electron-
density map clearly showed that the anion was disordered by a twofold
rotation over two sets of positions, apparent at the sites of the atoms of
the CF2NC5H4S ligand as the disorder leads the CF3 groups to practically
coincide with their counterparts. The geometry of the CF2NC5H4S ligand
as well as the atomic displacement parameters were tightly restrained to
be equal in both sites. A common occupation parameter was refined for
This work was supported by the Spanish MICINN (DGPTC)/FEDER
(Project CTQ2008-06669-C02-01/BQU) and the Gobierno de Aragꢂn
(Grupo Consolidado E21: Quꢀmica Inorgꢃnica y de los Compuestos Or-
ganometꢃlicos).
À
[1] Proton is the simplest reagent enabling electrophilic cleavage of M
C bonds: J. F. Hartwig, Organotransition Metal Chemistry, University
Science Books, Sausalito, California, 2010, Section 12.2, pp. 454–
462; M. D. Johnson, Acc. Chem. Res. 1978, 11, 57.
[2] A s-methane metal complex has been recently observed to form in
i
À
solution by protonation of a [Rh] CH3 precursor at À1108C before
Chem. Eur. J. 2013, 19, 324 – 337
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
335

J. Forniꢁs et al.
dissociation of CH4 takes place: W. H. Bernskoetter, C. K. Schauer,
K. I. Goldberg, M. Brookhart, Science 2009, 326, 553.
[25] D. Naumann, N. V. Kirij, N. Maggiarosa, W. Tyrra, Y. L. Yagupolskii,
M. S. Wickleder, Z. Anorg. Allg. Chem. 2004, 630, 746.
[26] E. S. Raper, Coord. Chem. Rev. 1996, 153, 199.
[3] For kinetic isotope effects observed upon protonolysis of various
À
[27] E. S. Raper, Coord. Chem. Rev. 1997, 165, 475.
types of M CH3 bonds and their relevance to determine the reac-
tion mechanism, see: V. J. Scott, J. A. Labinger, J. E. Bercaw, Orga-
nometallics 2011, 30, 4374, and Refs. therein.
[28] Nitrogen is known to be the least effective Group 15 heteroatom to
stabilize an adjacent ylidic anion (following the order P>As>N), a
fact that has been attributed to the absence of dp–pp interaction:
D. J. Burton, Z.-Y. Yang, W. Qiu, Chem. Rev. 1996, 96, 1641.
[29] P. J. Brothers, A. K. Burrell, G. R. Clark, C. E. F. Rickard, W. R.
Roper, J. Organomet. Chem. 1990, 394, 615.
[30] C. J. Bourgeois, R. P. Hughes, J. Yuan, A. G. di Pasquale, A. L.
Rheingold, Organometallics 2006, 25, 2908.
[31] R. P. Hughes, R. B. Laritchev, J. Yuan, J. A. Golen, A. N. Rucker,
A. L. Rheingold, J. Am. Chem. Soc. 2005, 127, 15020.
[32] F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen,
R. Taylor, J. Chem. Soc. Perkin Trans. 2 1987, S1.
[33] R. M. Schoth, E. Lork, A. A. Kolomeitsev, G.-V. Rçschenthaler, J.
Fluorine Chem. 1997, 84, 41.
[34] A. Haaland, Angew. Chem. 1989, 101, 1017; Angew. Chem. Int. Ed.
Engl. 1989, 28, 992.
[35] H. Sakaba, M. Tsukamoto, T. Hirata, C. Kabuto, H. Horino, J. Am.
Chem. Soc. 2000, 122, 11511.
[36] For additional examples of donor-stabilized silylene metal com-
plexes, see: E. Suzuki, T. Komuro, Y. Kanno, M. Okazaki, H.
Tobita, Organometallics 2010, 29, 5296; E. Suzuki, T. Komuro, M.
Okazaki, H. Tobita, Organometallics 2009, 28, 1791; R. Waterman,
P. G. Hayes, T. D. Tilley, Acc. Chem. Res. 2007, 40, 712; E. Suzuki,
M. Okazaki, H. Tobita, Chem. Lett. 2005, 34, 1026; M. Okazaki, H.
Tobita, H. Ogino, Dalton Trans. 2003, 493; T. Sato, M. Okazaki, H.
Tobita, H. Ogino, J. Organomet. Chem. 2003, 669, 189; H. Tobita, T.
Sato, M. Okazaki, H. Ogino, J. Organomet. Chem. 2000, 611, 314;
R. J. P. Corriu, B. P. S. Chauhan, G. F. Lanneau, Organometallics
1995, 14, 1646; S. K. Grumbine, D. A. Straus, T. D. Tilley, A. L.
Rheingold, Polyhedron 1995, 14, 127; H. Jacobsen, T. Ziegler, Orga-
nometallics 1995, 14, 224; S. K. Grumbine, T. D. Tilley, F. P. Arnold,
A. L. Rheingold, J. Am. Chem. Soc. 1994, 116, 5495; P. D. Lickiss,
Chem. Soc. Rev. 1992, 21, 271; D. A. Straus, S. D. Grumbine, T. D.
Tilley, J. Am. Chem. Soc. 1990, 112, 7801; C. Zybill, G. Mꢈller,
Angew. Chem. 1987, 99, 683; Angew. Chem. Int. Ed. Engl. 1987, 26,
669.
[37] For selected examples of donor-stabilized germylene metal com-
plexes, see: a) D. J. Brauer, C. Krꢈger, Abstracts of the 2nd Europe-
an Crystallographic Meeting, Keszthely, Hungary, 1974, 435; b) T. J.
Marks, J. Am. Chem. Soc. 1971, 93, 7090.
[38] For selected examples of donor-stabilized stannylene metal com-
plexes, see: Y. Cabon, H. Kleijn, M. A. Siegler, A. L. Spek,
R. J. M. K. Gebbink, B.-J. Deelman, Dalton Trans. 2010, 39, 2423;
M. D. Brice, F. A. Cotton, J. Am. Chem. Soc. 1973, 95, 4529; see also
reference [37b].
[4] For recent theoretical studies on the mechanism by which protonol-
À
ysis of Pt CH3 bonds may take place at dimethylplatinum(II) com-
plexes, see: G. Mazzone, N. Russo, E. Sicilia, Inorg. Chem. 2011, 50,
10091, where sample reference to previous and valuable experimen-
tal work is also to be found.
[5] M. A. Garcꢀa-Monforte, S. Martꢀnez-Salvador, B. Menjꢂn, Eur. J.
Inorg. Chem. 2012, 31, 4945; R. P. Hughes, Eur. J. Inorg. Chem.
2009, 4591; P. J. Brothers, W. R. Roper, Chem. Rev. 1988, 88, 1293.
[6] D. Huang, P. R. Koren, K. Folting, E. R. Davidson, K. G. Caulton, J.
Am. Chem. Soc. 2000, 122, 8916; D. Huang, K. G. Caulton, J. Am.
Chem. Soc. 1997, 119, 3185.
[7] W. B. Farnham, B. E. Smart, W. J. Middleton, J. C. Calabrese, D. A.
Dixon, J. Am. Chem. Soc. 1985, 107, 4565; M. E. Redwood, C. J.
Willis, Can. J. Chem. 1965, 43, 1893.
[8] K. O. Christe, J. Hegge, B. Hoge, R. Haiges, Angew. Chem. 2007,
119, 6267; Angew. Chem. Int. Ed. 2007, 46, 6155; G. Kloeter, K. Sep-
pelt, J. Am. Chem. Soc. 1979, 101, 347; K. Seppelt, Angew. Chem.
1977, 89, 325; Angew. Chem. Int. Ed. Engl. 1977, 16, 322; the decom-
position of CF3OH might take place following an intermolecular
path: M. T. Nguyen, M. H. Matus, V. T. Ngan, R. Haiges, K. O.
Christe, D. A. Dixon, J. Phys. Chem. A 2008, 112, 1298.
[9] M. Finze, E. Bernhardt, M. Zꢇhres, H. Willner, Inorg. Chem. 2004,
43, 490.
[10] M. Finze, E. Bernhardt, A. Terheiden, M. Berkei, H. Willner, D.
Christen, H. Oberhammer, F. Aubke, J. Am. Chem. Soc. 2002, 124,
15385.
[11] S. Martꢀnez-Salvador, B. Menjꢂn, J. Forniꢁs, A. Martꢀn, I. Usꢂn,
Angew. Chem. 2010, 122, 4382; Angew. Chem. Int. Ed. 2010, 49,
4286.
[12] B. Menjꢂn, S. Martꢀnez-Salvador, M. A. Gꢂmez-Saso, J. Forniꢁs,
L. R. Falvello, A. Martꢀn, A. Tsipis, Chem. Eur. J. 2009, 15, 6371.
[13] S. Martꢀnez-Salvador, J. Forniꢁs, A. Martꢀn, B. Menjꢂn, Chem. Eur.
J. 2011, 17, 8085.
[14] T. G. Appleton, R. D. Berry, J. R. Hall, D. W. Neale, J. Organomet.
Chem. 1989, 364, 249.
[15] R. Usꢂn, J. Forniꢁs, M. Tomꢃs, I. Ara, B. Menjꢂn, J. Organomet.
Chem. 1987, 336, 129.
[16] J. Browning, P. L. Goggin, R. J. Goodfellow, M. G. Norton, A. J. M.
Rattray, B. F. Taylor, J. Mink, J. Chem. Soc. Dalton Trans. 1977,
2061.
[17] D. R. Russell, P. A. Tucker, S. Wilson, J. Organomet. Chem. 1976,
104, 387.
[18] M. Berkei, J. F. Bickley, B. T. Heaton, Z. Naturforsch. Teil B 2002,
57, 610.
[39] R. R. Burch, J. C. Calabrese, S. D. Ittel, Organometallics 1988, 7,
1642, where the related neutral compound [Ni{CF
ACHTNUGNERTN(UGN PEt3)CF2CF2CF2-
k2C}
N
ACHTUNGTRENNUNG
[19] S. Gautron, N. Lassauque, C. le Berre, L. Azam, R. Giordano, P.
Serp, G. Laurenczy, J. C. Daran, C. Duhayon, D. Thiꢁbaut, P. Kalck,
Organometallics 2006, 25, 5894.
[40] J. Campos, R. Peloso, E. Carmona, Angew. Chem. 2012, 124, 8380;
Angew. Chem. Int. Ed. 2012, 51, 8255.
[20] J. E. Huheey, E. A. Keiter, R. L. Keiter, Inorganic Chemistry, 4th
ed., Harper Collins, New York, 1993, pp. 182–199. See also: S. G.
Bratsch, J. Chem. Educ. 1985, 62, 101; A. L. Allred, J. Inorg. Nucl.
Chem. 1961, 17, 215.
[21] S. Martꢀnez-Salvador, J. Forniꢁs, A. Martꢀn, B. Menjꢂn, Angew.
Chem. 2011, 123, 6701; Angew. Chem. Int. Ed. 2011, 50, 6571.
[22] A. G. Algarra, V. V. Grushin, S. A. Macgregor, Organometallics
2012, 31, 1467; J. Goodman, V. V. Grushin, R. B. Larichev, S. A.
Macgregor, W. J. Marshall, D. C. Roe, J. Am. Chem. Soc. 2010, 132,
12013.
[23] E. Pitcher, A. D. Buckingham, F. G. A. Stone, J. Chem. Phys. 1962,
36, 124.
[24] R. A. Michelin, R. Ros, J. Chem. Soc. Dalton Trans. 1989, 1149;
T. G. Appleton, H. C. Clark, L. E. Manzer, Coord. Chem. Rev. 1973,
10, 335.
[41] S. Wang, R. J. Staples, J. P. Fackler, Jr., Acta Crystallogr. Sect. C
1994, 50, 889.
[42] V. D. de Castro, G. M. de Lima, A. O. Porto, H. G. L. Siebald, J. D.
de Souza Filho, J. D. Ardisson, J. D. Ayala, G. Bombieri, Polyhedron
2004, 23, 63.
[43] E. S. Raper, Coord. Chem. Rev. 1985, 61, 115.
[44] a-Fluoride elimination at a CF3 group promoted by moderately
acidic pyridinium salts has been documented in Ir chemistry: see
reference [31].
[45] D. M. Andrada, J. O. C. Jimenez-Halla, M. Solꢉ, J. Org. Chem. 2010,
75, 5821; M. Ali, A. Dan, A. Ray, K. Ghosh, Inorg. Chem. 2005, 44,
5866; C. F. Bernasconi, Adv. Phys. Org. Chem. 2002, 37, 137; F. R.
Kreißl, E. O. Fischer, Chem. Ber. 1974, 107, 183; F. R. Kreißl, E. O.
Fischer, C. G. Kreiter, K. Weiß, Angew. Chem. 1973, 85, 617; Angew.
Chem. Int. Ed. Engl. 1973, 12, 564; H. Werner, E. O. Fischer, B.
336
www.chemeurj.org
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 324 – 337

Trifluoromethyl Platinum(II) Compounds
FULL PAPER
Heckl, C. G. Kreiter, J. Organomet. Chem. 1971, 28, 367; B. Heckl,
H. Werner, E. O. Fischer, Angew. Chem. 1968, 80, 847; Angew.
Chem. Int. Ed. Engl. 1968, 7, 817.
[54] T. G. Appleton, J. R. Hall, D. W. Neale, M. A. Williams, J. Organo-
met. Chem. 1984, 276, c73.
[55] H. C. Clark, L. E. Manzer, J. Organomet. Chem. 1973, 59, 411.
[56] L. J. Bellamy, The Infra-Red Spectra of Complex Molecules, Vol. 1,
3rd ed., Chapman and Hall, London, 1975, Chapter 7, pp. 129–140;
G. M. Barrow, S. Searles, J. Am. Chem. Soc. 1953, 75, 1175.
[57] CrysAlis RED, Program for X-ray CCD camera data reduction, Ver-
sion 1.171.32.19, Oxford Diffraction, Oxford, 2008.
[58] G. M. Sheldrick, SHELXL-97, Program for the refinement of crystal
structures from diffraction data, University of Gçttingen, Germany,
1997.
[46] M. A. Sierra, I. Fernꢃndez, F. P. Cossꢀo, Chem. Commun. 2008, 4671.
[47] T. G. Appleton, J. R. Hall, C. H. L. Kennard, M. T. Mathieson, D. W.
Neale, G. Smith, T. C. W. Mak, J. Organomet. Chem. 1993, 453, 299.
[48] J. C. Thomas, J. C. Peters, J. Am. Chem. Soc. 2001, 123, 5100.
[49] I. Ara, J. Forniꢁs, A. Martꢀn, L. F. Martꢀn, B. Menjꢂn, H. Miedes,
Dalton Trans. 2010, 39, 7301.
[50] P. Pyykkç, M. Atsumi, Chem. Eur. J. 2009, 15, 186.
[51] S. Ahrland, J. Chatt, N. R. Davies, Q. Revs. Chem. Soc. 1958, 12,
265.
[52] J. A. Davies, F. R. Hartley, Chem. Rev. 1981, 81, 79.
[53] R. Usꢂn, J. Forniꢁs, M. Tomꢃs, B. Menjꢂn, Organometallics 1986, 5,
1581; R. Usꢂn, J. Forniꢁs, M. Tomꢃs, B. Menjꢂn, Organometallics
1985, 4, 1912.
Received: July 25, 2012
Published online: November 20, 2012
Chem. Eur. J. 2013, 19, 324 – 337
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
337