Divalent platinum complexes of the carbanion 2-C6F 4AsPh2: Monodentate or bidentate coordination?

Article abstract of DOI:10.1021/om400961z

The reaction of [PtI₂(1,5-COD)] with 2-LiC₆F ₄AsPh₂ affords the planar platinum(II) fluoroaryl complex [PtI(κC-2-C₆F₄AsPh₂)(1,5-COD)] (7), in which the arsenic atom is not coordinated to the metal atom. Attempts to prepare the bis(chelate) complex [Pt(κ²As,C-2-C₆F ₄AsPh₂)₂] analogous to the known phosphorus compound failed. Removal of iodide ion from 7 with TlPF₆ gave [Pt(κ²As,C-2-C₆F₄AsPh₂)(1,5- COD)]PF₆ (8), in which 2-C₆F₄AsPh₂ is now coordinated as a bidentate ligand, giving a four-membered chelate ring. Alternatively, protonolysis (with triflic acid) of the methyl complex [PtMe(κC-2-C₆F₄AsPh₂)(1,5-COD)] (15), which is obtained from 7 and dimethylzinc, gives the triflate salt 16 of the same chelate cation. The chelate As,C ring in 8 is readily reopened when the complex is treated with pyridine or with halide ions, forming respectively [Pt(py)(κC-2-C₆F₄AsPh₂)(1,5-COD)]PF ₆ (9) and [PtX(κC-2-C₆F₄AsPh ₂](1,5-COD)] (X = Cl (10), Br (11), I (7)). The appearance of two pairs of olefinic COD resonances in the proton NMR spectra of 7, 10, 11, and 15 may indicate that there is restricted rotation about the Pt-κC-2-C ₆F₄AsPh₂ bond; the additional signals are not evident in the spectra of 8 or 16. Complexes 7 and 10 form the 1:1 adducts [PtX(μ-2-C₆F₄AsPh₂)(1,5-COD)AuY] (X = Cl, Y = I (12); X = Y = I (13); X = Y = Cl (14)) by attachment of gold(I) halides to their dangling arsenic atoms. In 12 the halides are scrambled between platinum and gold. The X-ray structures of 7, 8, 9, 12, 15, and 16 are reported, and possible reasons for the poorer chelating ability of 2-C₆F ₄AsPh₂ in comparison with that of 2-C₆H ₄PPh₂ are discussed.

Full text of DOI:10.1021/om400961z

Article
pubs.acs.org/Organometallics
Divalent Platinum Complexes of the Carbanion 2‑C6F4AsPh2:
Monodentate or Bidentate Coordination?
Nedaossadat Mirzadeh,† Steven H. Priver,† Martin A. Bennett,‡ Jorg Wagler,§ and Suresh K. Bhargava*,†
́
̈
†Centre for Advanced Materials & Industrial Chemistry, School of Applied Sciences, RMIT University, GPO Box 2476 V, Melbourne,
Victoria 3001, Australia
‡Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 0200, Australia
§Institut fur Anorganische Chemie, Technische Universitat Bergakademie, Freiberg D-09596, Germany
̈
̈
S
* Supporting Information
ABSTRACT: The reaction of [PtI2(1,5-COD)] with 2-
LiC6F4AsPh2 affords the planar platinum(II) fluoroaryl
complex [PtI(κC-2-C6F4AsPh2)(1,5-COD)] (7), in which
the arsenic atom is not coordinated to the metal atom.
Attempts to prepare the bis(chelate) complex [Pt(κ2As,C-2-
C6F4AsPh2)2] analogous to the known phosphorus compound
failed. Removal of iodide ion from 7 with TlPF6 gave
[Pt(κ2As,C-2-C6F4AsPh2)(1,5-COD)]PF6 (8), in which 2-
C6F4AsPh2 is now coordinated as a bidentate ligand, giving a
four-membered chelate ring. Alternatively, protonolysis (with
triflic acid) of the methyl complex [PtMe(κC-2-C6F4AsPh2)(1,5-COD)] (15), which is obtained from 7 and dimethylzinc, gives
the triflate salt 16 of the same chelate cation. The chelate As,C ring in 8 is readily reopened when the complex is treated with
pyridine or with halide ions, forming respectively [Pt(py)(κC-2-C6F4AsPh2)(1,5-COD)]PF6 (9) and [PtX(κC-2-C6F4AsPh2](1,5-
COD)] (X = Cl (10), Br (11), I (7)). The appearance of two pairs of olefinic COD resonances in the proton NMR spectra of 7,
10, 11, and 15 may indicate that there is restricted rotation about the Pt−κC-2-C6F4AsPh2 bond; the additional signals are not
evident in the spectra of 8 or 16. Complexes 7 and 10 form the 1:1 adducts [PtX(μ-2-C6F4AsPh2)(1,5-COD)AuY] (X = Cl, Y = I
(12); X = Y = I (13); X = Y = Cl (14)) by attachment of gold(I) halides to their dangling arsenic atoms. In 12 the halides are
scrambled between platinum and gold. The X-ray structures of 7, 8, 9, 12, 15, and 16 are reported, and possible reasons for the
poorer chelating ability of 2-C6F4AsPh2 in comparison with that of 2-C6H4PPh2 are discussed.
dimerize. The increased stability conferred by fluorine
substitution in the aromatic ring is also evident from the fact
that analogous nickel and palladium bis(chelate) complexes
trans-[M(κ2P,C-2-C6F4PPh2)2] (M = Ni, Pd) can be prepared,3
whereas the protio analogues are unknown.
INTRODUCTION
■
Ortho-metalated complexes containing the bidentate carbanion
[2-C6H4PPh2]− are known for most of the transition metals and
are usually prepared by C−H bond activation of coordinated
PPh3.1 Other methods based on transmetalation of 2-
LiC6H4PPh2 and on oxidative addition of 2-BrC6H4PPh2 are
also known.1 The resulting complexes are often mononuclear
and contain a four-membered M(κ2P,C-2-C6H4PPh2) chelate
ring, although examples are also known where the 2-C6H4PPh2
group acts as a bifunctional bridging ligand spanning two metal
centers. For example, the reaction of 2-LiC6H4PPh2 with
[PtCl2(SEt2)2] gives the mononuclear bis(chelate) complex cis-
[Pt(κ2P,C-2-C6H4PPh2)2] (1), which dimerizes in refluxing
toluene to give [Pt2(μ-2-C6H4PPh2)2(κ2P,C-2-C6H4PPh2)2]
(2), derived by opening of half the available four-membered
chelate rings (Scheme 1).
Metal−perfluoroaryl complexes are usually much more stable
than their aryl counterparts and show distinctly different
chemistry.2 Although the fluorine-substituted bis(chelate)
complex [Pt(κ2P,C-2-C6F4PPh2)2]3 is prepared similarly to its
protio analogue, cis-[Pt(κ2P,C-2-C6H4PPh2)2], the former is
isolated as a cis/trans mixture that is converted into the more
stable trans isomer on heating and shows no tendency to
In contrast to the extensive range of ortho-metalated tertiary
phosphine species, relatively few examples of ortho-metalated
tertiary arsine species have been reported. Early work showed
that heating a solution of the iridium(I) complex [IrCl-
(AsPh3)3] gave the cyclometalated iridium(III) complex
[IrHCl(κ2As,C-2-C6H4AsPh2)(AsPh3)2].4 More recently, treat-
ment of [AuBr(AsPh3)]5 or [PtCl2(SEt2)2]6 with LiC6H3-5-
Me-2-AsPh2 has been reported to give the dinuclear gold(I)
complex 3 and a mixture of the dinuclear platinum(II)
complexes 4 and 5, respectively, as shown in Scheme 2.
Compound 4 is analogous to the phosphine compound 2,
whereas the lantern compound 5 has no known phosphine
analogue. The two isomeric diplatinum(II) complexes undergo
oxidative addition of halogens to give metal−metal-bonded
dihalodiplatinum(III) species (Scheme 3), and the photo-
Received: September 30, 2013
Published: December 5, 2013
© 2013 American Chemical Society
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Scheme 1
Scheme 2
Scheme 3
physical properties of the complexes in both oxidation states
have been investigated. At room temperature and at 77 K, the
parent 5d8−5d8 diplatinum(II) dimer 5 exhibits intense green
phosphorescence in the range 501−532 nm, whereas the 5d7−
5d7 dihalodiplatinum(III) complexes are emissive in the near-
RESULTS
■
The required ligand precursor, (2-bromotetrafluorophenyl)-
diphenylarsine (6), was prepared similarly to its phosphine
analogue by low-temperature monolithiation of 1,2-dibromote-
trafluorobenzene and subsequent treatment with chlorodiphe-
nylarsine.8 The ESI-mass spectrum of 6 showed a parent ion
peak, and the 1H NMR spectrum contained the expected
aromatic multiplets. The 19F NMR spectrum consisted of four
peaks, each a well-resolved doublet of doublets of doublets
arising from F−F coupling, at δ −119.6, −126.2, −151.0, and
−153.9. The least shielded resonance at δ −119.6 is assigned to
the fluorine atom ortho to the bromine atom. The chemical
shifts are similar to those observed for 2-BrC6F4PPh2 but the
F−F couplings in the latter are less well resolved owing to
superimposed P−F coupling.9
infrared region.7
In view of the different coordination behaviors of [C6H3-5-
Me-2-AsPh2]− and [2-C6H4PPh2]− toward platinum(II), we
were interested in exploring the chemistry and reactivity of
platinum(II) complexes containing the carbanion [2-
C6F4AsPh2]− for comparison with those of [2-C6F4PPh2]−.
The results are presented herein.
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As shown in Scheme 4, treatment of 2-LiC6F4AsPh2 in ether
with [PtI2(1,5-COD)] in a 1:1 molar ratio at low temperature
Scheme 5
Scheme 4
constants with the trans influence of the ligand atom in the
trans site, and the fact that As donors are above iodide in the
trans-influence series,24 the observed value of 64.7 Hz seems
surprisingly high.
gave [PtI(κC-2-C6F4AsPh2)(1,5-COD)] (7), which could be
isolated as a white powder in ca. 80% yield. Attempts to make
the bis(chelate) compound analogous to 1 by use of a 2:1
molar ratio of reactants gave the same product; there was no
evidence for the formation of compounds analogous to 1 and 2
(Scheme 1) or 4 and 5 (Scheme 2).
Heating toluene solutions of 8 led to extensive decom-
position; there was no evidence for the formation of dinuclear
complexes containing bridging C6F4AsPh2, in contrast to the
behavior of complex 1 containing 2-C6H4PPh2 (Scheme 1) or
complex 4 containing 5-Me-2-C6H3AsPh2 (Scheme 2). The
As,C chelate ring in 8 was opened on addition of 1 equiv of
pyridine to give [Pt(py)(κC-C6F4AsPh2)(1,5-COD)]PF6 (9)
(Scheme 6). Under similar conditions, MeCN did not react
The ESI-mass spectrum of compound 7 showed a peak at
m/z 829.9 corresponding to the [M + Na]+ ion. The 19F NMR
spectrum showed the expected four multiplets, each flanked by
1
1
195Pt satellites (see the Experimental Section). The H NMR
with 8. The H NMR spectrum of 9 contained a pair of
resonances with 195Pt satellites at δ 5.28 (2JPtH = 64.1 Hz) and
5.71 (2JPtH = 38.6 Hz), assigned to the olefinic COD protons
trans to pyridine and C(aryl), respectively, in addition to three
different pyridine proton signals in the expected region.
The chelate ring in 8 was also opened by the addition of
halide ions. Thus, the reaction of 8 with NaI regenerated 7, and
the chloro (10) and bromo (11) analogues were prepared by
use of LiCl and LiBr, respectively (Scheme 6). The chemical
shifts and Pt−H coupling constants of the olefinic COD
protons in 7, 10, and 11 are similar, the Pt−H coupling
constants being in the ranges of 39−44 and 64−73 Hz for the
protons trans to C(aryl) and halide, respectively.
spectrum contained four multiplets, accompanied by 195Pt
satellites, at δ 4.34 (2JPtH = 64.3 Hz), 5.08 (2JPtH = 71.8 Hz),
5.89 (2JPtH = 43.6 Hz), and 6.09 (2JPtH = 42.7 Hz), which can be
assigned to the olefinic protons of coordinated 1,5-COD,
together with four multiplets in the range δ 1.8−2.8 due to the
methylene protons of COD. The 195Pt coupling constants of ca.
40 Hz to the less shielded pair of olefinic protons are similar to
those trans to the σ-bonded organo group R in compounds of
the type [PtRX(1,5-COD)] (R = Me, Ph, C6F5; X = halide),
while the 195Pt coupling constants of ca. 70 Hz to the more
shielded pair are typical of those trans to the halide X.10 Thus,
the perfluoro group and iodide must be coordinated to
platinum and, if we assume that the metal atom adopts its usual
planar coordination, the arsenic atom must be uncoordinated.
These features have been confirmed by the X-ray structure
determination of 7 discussed below. The observed inequiva-
lence of all the olefinic protons of COD presumably arises from
restricted rotation about the Pt−C(aryl) bond. There are
numerous examples of restricted rotation about the metal−
carbon bonds in Pt−C6F5 complexes,11−20 and there is
evidence for slowed rotation about M−P and M−C bonds in
complexes of (C6F5)3P.21−23
The 19F NMR spectra of 7, 10, and 11 differ in the chemical
shift of the ortho fluorine atom, which decreases over a range of
2.5 ppm in the order Cl < Br < I.
The free arsenic atom in compound 7 can coordinate to
gold(I) to give heterobimetallic species. The solid isolated from
the reaction of 7 with [AuCl(tht)] analyzed satisfactorily as a
1:1 adduct (12; Scheme 7), but its 19F NMR spectrum showed
four sets of four multiplets due to C6F4AsPh2 groups, indicative
of a mixture, and the ESI-mass spectrum showed [M + Na]+
peaks corresponding to the sodium adducts of [PtX(μ-2-
C6F4AsPh2)(1,5-COD)AuY] (X = Y = I (13), Cl (14); X, Y =
Cl, I, X ≠ Y (12)) arising from halide scrambling. Attempts to
separate the mixture by fractional crystallization were
unsuccessful, but structure determination of a selected X-ray-
quality crystal confirmed the presence of 12, in which the halide
positions are occupied by both chloride and iodide (∼2/3 I at
Attempted reactions of 2-LiC6F4AsPh2 with other precursors
such as [PtCl2(SEt2)2], [PtCl2(1,5-COD)], and [PtCl2(NBD)]
gave complex mixtures, as shown by 19F NMR spectroscopy,
and no tractable products could be isolated.
To achieve coordination of the free arsenic atom to the
metal, 7 was treated with TlPF6 to give the salt [Pt(κ2As,C-
C6F4AsPh2)(1,5-COD)]PF6 (8) (Scheme 5), in which the
presence of a four-membered As,C chelate ring was confirmed
by X-ray crystallography (see below). In addition to aromatic
and methylene resonances, the 1H NMR spectrum of 8
contained a pair of olefinic COD resonances with 195Pt
satellites at δ 6.04 (2JPtH = 43.2 Hz) and 6.58 (2JPtH = 64.7 Hz).
The Pt−H coupling constant for the signal at δ 6.04 suggests
that this resonance should be assigned to the olefinic protons
trans to the σ-bonded carbon atom of 2-C6F4AsPh2; hence, the
resonance at δ 6.58 must be due to the olefinic protons trans to
AsPh2. Given the inverse correlation of these coupling
2
gold and /3 Cl at platinum). The diiodo complex 13 was
prepared by treatment of the mixture with an excess of NaI; its
19F NMR spectrum matched that of one of the components of
the mixture. Treatment of [PtCl(κC-2-C6F4AsPh2)(1,5-COD)]
(10) with [AuCl(tht)] gave the corresponding 1:1 dichloro
complex, whose 19F NMR spectrum agreed with that of a
second component of the original mixture.
Reaction of complex 7 with dimethylzinc gave the methyl
compound [PtMe(κC-2-C6F4AsPh2)(1,5-COD)] (15; Scheme
8), which was isolated as a white solid in almost quantitative
1
yield. The H NMR spectrum of 15 shows a singlet with
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Scheme 6
crystallography and are shown in Figures 1−5 (except for
complex 16); selected bond distances and angles are
summarized in the caption to the relevant figure or in Tables
1−3. For compound 7 we found two modifications
(orthorhombic, Pna21, and monoclinic, P21, with one and
two independent molecules in the asymmetric unit, respec-
tively). Only the structure of the orthorhombic modification
will be discussed in the following as a representative example;
the metrical parameters for the monoclinic modification are
very similar. In 7 (shown in Figure 1), the platinum atom is
Scheme 7
Scheme 8
satellites due to Pt−Me at δ 0.78 (2JPtH = 78.7 Hz), together
with multiplet aliphatic COD peaks at δ 2.10−2.76. As with the
halo complexes 7, 10 and 11, all of the olefinic COD protons
are inequivalent and give rise to resonances at δ 4.57 (2JPtH
=
54.1 Hz), 5.06 (with unresolved platinum satellites), and 5.24
(2JPtH = 43.7 Hz) in a 1:2:1 intensity ratio. The Pt−methyl
bond in 15 was selectively cleaved by addition of a
stoichiometric amount of triflic acid, generating the cationic
complex [Pt(κ2As,C-2-C6F4AsPh2)(1,5-COD)]OTf (16), the
1H and 19F NMR parameters of which are similar to those of
the PF6 salt 8. As in the case of 8, attempts to form dimeric
species by heating toluene solutions of 16 resulted in
decomposition; there was no evidence for ring opening or for
the formation of compounds containing bridging 2-C6F4AsPh2.
X-ray Crystal Structures. The molecular structures of
compounds 7−9, 12, 15, and 16 have been confirmed by X-ray
Figure 1. Molecular structure of compound 7. Ellipsoids are shown at
the 50% probability level, and hydrogen atoms have been omitted for
clarity.
coordinated in an approximately square planar array by iodide,
COD, and the aromatic carbon atom of 2-C6F4AsPh2, while the
arsenic atom is not coordinated (d(Pt···As) = 3.264 Å).
Table 1. Selected Bond Lengths (Å) and Angles (deg) in 7
Pt(1)−I(1)
As(1)−C(1)
Pt(1)−C(6)
Pt(1)−C(19)
Pt(1)−C(6)−C(1)
C(6)−C(1)−As(1)
I(1)−Pt(1)−C(24)
I(1)−Pt(1)−C(23)
I(1)−Pt(1)−C(19)
I(1)−Pt(1)−C(20)
2.6170(4)
1.972(4)
2.015(4)
2.249(6)
120.2(3)
115.4(3)
167.53(16)
155.67(17)
94.12(15)
95.25(15)
Pt(1)−C(20)
Pt(1)−C(23)
Pt(1)−C(24)
2.309(7)
2.147(5)
2.190(5)
C(6)−Pt(1)−C(19)
C(6)−Pt(1)−C(20)
C(6)−Pt(1)−C(23)
C(6)−Pt(1)−C(24)
C(23)−Pt(1)−C(24)
C(20)−Pt(1)−C(19)
157.1(2)
167.7(2)
92.1(2)
92.8(2)
36.8(2)
34.8(3)
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The Pt−I distances in 7 (2.6170(4) Å) and in [PtI2(1,5-
COD)] (2.6094(5) and 2.6130(5) Å) are almost identical.25
The Pt−C(COD) distances fall into two sets: Pt(1)−C(19)
and Pt(1)−C(20) trans to C6F4 (2.249(6) Å, 2.309(7) Å) and
Pt(1)−C(23) and Pt(1)−C(24) trans to I (2.147(5) Å,
2.190(5) Å), the trend clearly reflecting the higher trans
influence of the fluoroaryl ligand relative to that of iodide. The
difference within each set arises because the coordinated 1,5-
COD adopts its usual twist-boat conformation.
containing ortho-metalated PPh3 and AsPh3.1 The Pt−C(aryl)
bond distances (2.033(2) Å, 8; 2.032(4) Å. 16) are slightly
longer than that of 2.015(4) Å in 7. In compounds 8 and 16,
the Pt−C(COD) bond distances trans to carbon (2.2675 (av)
and 2.2645 (av) Å, respectively) are longer than those trans to
arsenic (2.2255 (av) and 2.2220 (av) Å, respectively).
The molecular structures of the cation of [Pt(py)(κC-2-
C6F4AsPh2)(1,5-COD)] (9) and [PtMe(κC-2-C6F4AsPh2)(1,5-
COD)] (15) are shown in Figures 3 and 4, respectively;
selected bond lengths and angles in 9 and 15 are shown in the
relevant caption.
The molecular structure of the cation in 8 is shown in Figure
2. Selected bond distances and angles in 8 and in the
corresponding triflate salt 16 are summarized in Table 2.
Figure 3. Molecular structure of the cation in 9. Ellipsoids are shown
at the 50% probability level. Hydrogen atoms and the PF6 counterion
have been omitted for clarity. The phenyl rings of the AsPh2 groups
only show the ipso carbons. Selected bond lengths (Å) and angles
(deg) in 9: Pt(1)−C(1) 2.033(3), Pt(1)−N(1) 2.078(3), Pt(1)−
C(19) 2.186(3), Pt(1)−C(22) 2.263(3), Pt(1)−C(23) 2.306(3),
Pt(1)−C(26) 2.175(3), As(1)−C(2) 1.965(3); Pt(1)−C(1)−C(2)
120.9(2), As(1)−C(2)−C(1) 115.7(2), N(1)−Pt(1)−C(1)
91.02(11).
Figure 2. Molecular structure of the cation in 8. Ellipsoids are shown
at the 50% probability level. Hydrogen atoms and the PF6 counterion
have been omitted for clarity.
Table 2. Selected Bond Lengths (Å) and Angles (deg) in 8
and 16
Compounds 9 and 15 are structurally similar to 7. The Pt−
C(aryl) bond lengths in 9 and 15 are similar to but slightly
longer than the corresponding bonds in 7. The Pt−C(COD)
bond lengths trans to C(aryl) in 9 (2.2845 (av) Å) are similar
to those in 7 (2.2790 (av) Å) but longer than the
corresponding bonds in 15 (2.2276 (av) Å). The Pt−C(COD)
bond lengths trans to iodide, nitrogen, and C(methyl) in 7
(2.1685 (av) Å), 9 (2.1805 (av) Å), and 15 (2.26045 (av) Å),
respectively, reflect the trans influence in the order I < N < C.
The Pt−N(pyridine) bond length (2.078(3) Å) in 9 is
smaller than the Pt−N(bpy) bond lengths in [PtPh(bpy)(1,5-
COD)]PF6 (2.238(8) and 2.211(8) Å).26 The Pt−C(methyl)
bond length (2.0655(17) Å) in 15 is similar to that of
2.057(10) Å in [PtMe(CCC6H4-4-F)(1,5-COD)]27 and
shorter than those in [PtMe(OH)(1,5-COD)] (2.126(7) Å),
[PtMe2(1,5-COD)] (2.134(6) Å), and [PtMeCl(1,5-COD)]
(2.164(8) Å).28
The X-ray structural analysis of 12 confirms that the halogen
positions are occupied by both chlorine and iodine atoms. The
molecular structure of 12 is shown in Figure 5; selected bond
distances and angles are given in Table 3. In 12, the Au···Pt
separation (3.19993(17) Å) is consistent with the presence of a
weak attractive interaction between the metal centers.29 The
As(1)−C(2) bond distance (1.936(3) Å) in 12 is shorter than
8
16
Pt(1)−C(1)
Pt(1)−As(1)
Pt(1)−C(19)
Pt(1)−C(22)
Pt(1)−C(23)
Pt(1)−C(26)
As(1)−C(2)
C(2)−As(1)−Pt(1)
As(1)−Pt(1)−C(1)
C(1)−Pt(1)−C(19)
C(1)−Pt(1)−C(22)
C(1)−Pt(1)−C(23)
C(1)−Pt(1)−C(26)
As(1)−Pt(1)−C(19)
As(1)−Pt(1)−C(22)
As(1)−Pt(1)−C(23)
As(1)−Pt(1)−C(26)
2.033(2)
2.4308(3)
2.220(2)
2.281(2)
2.254(2)
2.231(2)
1.910(2)
79.76(7)
70.20(6)
95.61(9)
163.42(9)
160.41(9)
99.63(9)
154.38(6)
106.41(8)
103.87(8)
162.86(7)
2.032(4)
2.4145(5)
2.224(4)
2.258(4)
2.271(4)
2.220(4)
1.909(4)
79.98(12)
70.29(12)
100.42(16)
160.58(17)
163.43(17)
95.63(17)
163.35(12)
103.52(12)
106.01(13)
154.58(12)
The bond lengths and angles in 8 and 16 are generally
comparable, and the angles subtended at platinum by the four-
membered rings (70.20(6) and 70.29(12)°, respectively) are
similar to those observed in transition-metal complexes
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DISCUSSION
■
The only tractable complex containing [2-C6F4AsPh2]− that we
have been able to isolate is [PtI(κC-2-C6F4AsPh2)(1,5-COD)]
(7), the notable features of which are that 1,5-COD is retained
in the coordination sphere and that the arsenic atom is not
coordinated. In these respects, [2-C6F4AsPh2]− differs from
[C6H3-5-Me-2-AsPh2]− (see Introduction). When the iodide is
removed (either by reaction with TlPF6 or by reaction with
dimethylzinc and subsequent protonolysis of the Pt−Me
bond), the arsenic atom binds to the resulting cationic center
to give [Pt(κ2As,C-2-C6F4AsPh2)(1,5-COD)]+, isolated as its
PF6 (8) or triflate salt (16), containing the As,C-four-
membered ring. Moreover, the ring is readily reopened, with
displacement of the coordinated arsenic atom, by reaction with
halide ions to give [PtX(κC-2-C6F4AsPh2)(1,5-COD)] (X = Cl
(10), Br (11), I (7)) and with pyridine to give the cation of 9,
[Pt(py)(κC-2-C6F4AsPh2)(1,5-COD)]+.
The fluorine substituents in 2-C6F4AsPh2 probably stabilize
the platinum(II)−carbon bond, but they can also be expected
to reduce the coordinating ability of the arsenic atom. Thus,
although a limited number of complexes of (C6F5)3P with
Pd(II), Pt(II), Rh(I), and Ir(I) are known, the ligand itself,
unlike triphenylphosphine, displays no basic properties.30−32
The available evidence indicates that (C6F5)3P is a large,
sterically bulky, poor σ-donor ligand with little or no π-acceptor
ability.33 Since tertiary arsines are weaker bases than
corresponding tertiary phosphines, (C6F5)3As is likely to be
an even poorer ligand than (C6F5)3P and indeed only two of its
complexes, [AgClO4.As(C6F5)3] and [Ag{As(C6F5)3}2]ClO4,
are known.34 Our results indicate that the chelate four-
membered-ring complexes of the carbanion [2-C6F4AsPh2]−
are more labile than those of [2-C6F4PPh2]− and that they are
most likely to be observed at a cationic center. Although no
evidence was found for a chelate to bridging transformation in
the salts 8 and 16, the isolation of the Pt(II)−Au(I) complexes
12−14 demonstrates that [2-C6F4AsPh2]− is capable of acting
as a bridging ligand. However, this behavior is likely to be
limited by both steric constraints and the poor donor ability of
the arsenic center.
Figure 4. Molecular structure of 15. Ellipsoids are shown at the 50%
probability level, and hydrogen atoms have been omitted for clarity.
The phenyl rings of the AsPh2 groups only show the ipso carbons.
Selected bond lengths (Å) and angles (deg) in 15: Pt(1)−C(1)
2.0328(16), Pt(1)−C(27) 2.0655(17), Pt(1)−C(19) 2.2719(17),
Pt(1)−C(22) 2.2160(16), Pt(1)−C(23) 2.2392(17), Pt(1)−C(26)
2.2490(16), As(1)−C(2) 1.9691(16); Pt(1)−C(1)−C(2) 121.27(11),
As(1)−C(2)−C(1) 115.95(12), C(1)−Pt(1)−C(27) 87.33(7).
EXPERIMENTAL SECTION
■
Syntheses were performed under an atmosphere of dry argon with the
use of standard Schlenk techniques, although the solid complexes,
once isolated, were air stable. The compounds [AuCl(tht)],35
[PtI2(1,5-COD)],10a and chlorodiphenylarsine36 were prepared by
the appropriate literature procedure. All other chemicals were
commercially available.
Figure 5. Molecular structure of 12. Ellipsoids are shown at the 50%
probability level. Hydrogen atoms have been omitted for clarity. The
halide positions are occupied by both chlorine and iodine atoms. The
ratios are 0.67 I, 0.33 Cl at Au(1) and 0.67 Cl, 0.33 I at Pt(1).
Physical Measurements. Melting points were determined on a
Gallenkamp melting point apparatus in open glass capillaries. 1H (300
MHz) and 19F (282 MHz) NMR spectra were recorded on a Bruker
Avance 300 spectrometer in CDCl3, unless otherwise stated. Coupling
constants (J) are given in Hertz, and chemical shifts (δ) are given in
ppm, internally referenced to residual solvent signals (1H) or internal
CFCl3 (19F). Elemental analyses were performed by the Micro-
the corresponding bond in 7 (1.972(4) Å), as a consequence of
coordination of the arsenic atom. The metal−halide bond
lengths in 12 will not be discussed, as they are influenced by the
Cl vs I occupancy disorder.
Table 3. Selected Bond Lengths (Å) and Angles (deg) in 12
Pt(1)−C(1)
As(1)−C(2)
As(1)−Au(1)
Au(1)−Pt(1)
Au(1)−As(1)−C(2)
Cl(1)−Au(1)−Pt(1)
2.027(3)
Pt(1)−C(19)
Pt(1)−C(26)
Pt(1)−C(22)
2.162(3)
2.172(3)
2.297(3)
2.251(3)
79.753(8)
1.936(3)
2.3496(3)
3.19993(17)
116.21(8)
108.7(3)
Pt(1)−C(23)
Pt(1)−Au(1)−As(1)
7456
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Organometallics
Article
analytical Unit of the Research School of Chemistry at the Australian
National University (ANU), Canberra, Australia. Mass spectra were
recorded on a Bruker Apex 3 FTICR mass spectrometer.
X-ray Crystallography. Crystals suitable for single-crystal X-ray
diffraction were obtained by layering a CH2Cl2 solution with hexane
(7−9 and 16) or methanol (12 and 15).
X-ray diffraction data were collected on a D8 Bruker diffractometer
with an APEX2 area detector using graphite-monochromated Mo Kα
radiation (λ = 0.71073 Å) from a 1 μS microsource. Geometric and
intensity data were collected using SMART software.37 The data were
processed using SAINT,38 and corrections for absorption were applied
using SADABS.39 The structures were solved by direct methods and
refined with full-matrix least-squares methods on F2 using the SHELX-
TL package.40 For the structures of 7 data collection was performed on
a Stoe IPDS-2/2T diffractometer with Mo Kα radiation. For the COD
olefinic C/H atoms an sp2 model was used to attach the H atoms to
the respective C atoms.
= 5.1, 18.0, 22.7 Hz), −146.2 (ddd, JFF = 5.0, 18.0, 23.5 Hz, JPtF = 68.7
Hz), −149.9 (ddd, JFF = 5.5, 18.2, 22.4 Hz). ESI-MS (m/z): 680.1 [M
− PF6]+. Anal. Calcd for C26H22AsF10PPt: C, 37.83; H, 2.69; F, 23.02.
Found: C, 37.90; H, 2.63; F, 23.26.
[Pt(py)(κC-2-C6F4AsPh2)(1,5-COD)]PF6 (9). To solution of [Pt-
(κ2As,C-2-C6F4AsPh2)(1,5-COD)]PF6 (8; 113 mg, 0.14 mmol) in
dichloromethane (5 mL) was added pyridine (11 μL, 0.14 mmol), and
the mixture was stirred overnight. Hexane was added to the colorless
solution, and the volume was reduced in vacuo. The precipitated
colorless solid was separated by filtration, washed with hexane, and
dried in vacuo to give 9 (118 mg, 95%).
1H NMR (CD2Cl2): δ 2.38−2.96 (m, 8H, aliphatic COD), 5.28 (m,
2H, JPtH = 64.1 Hz, olefinic COD), 5.71 (m, 2H, JPtH = 38.6 Hz,
olefinic COD), 7.24−7.62 (m, 11H, aromatic/py), 7.95 (t, 1H, JHH
=
7.8 Hz, py), 8.74 (d, 2H, JHH = 5.2 Hz, py). 19F NMR (CD2Cl2): δ
−73.1 (d, JPtF = 711 Hz), −122.9 (ddd, JFF = 5.8, 15.0, 21.7 Hz,
unresolved JPtF), −123.9 (br. s, JPtF ≈ 230 Hz), −151.1 (m), −156.1
(m). ESI-MS (m/z): 759.1 [M − PF6]+. Anal. Calcd for
C31H27NAsF10PPt: C, 41.16; H, 3.01; N, 1.55; F, 21.00. Found: C,
40.87; H, 2.99; N, 1.69; F, 20.60.
Syntheses. 2-BrC6F4AsPh2 (6). To a solution of 1,2-dibromotetra-
fluorobenzene (9.28 g, 30 mmol) in ether (100 mL), cooled to −78
°C, was added nBuLi (1.6 M in hexanes, 20.0 mL, 30 mmol) dropwise.
After the mixture had been stirred for 30 min, chlorodiphenylarsine
(5.6 mL, 30 mmol) was slowly added. The solution was stirred at −78
°C for 2 h and then warmed to room temperature overnight. The
resulting suspension was hydrolyzed, the ether layer was separated,
and the aqueous phase was extracted with ether (3 × 50 mL). The
combined organic phases were dried (MgSO4) and filtered, and the
solvent was removed in vacuo. The yellow gummy solid was
recrystallized from methanol to give the title product as a colorless
solid (9.8 g, 71%).
[PtCl(κC-2-C6F4AsPh2)(1,5-COD)] (10). To a solution of [Pt(κ2As,C-
2-C6F4AsPh2)(1,5-COD)]PF6 (8; 150 mg, 0.18 mmol) in dichloro-
methane (5 mL) was added a solution of LiCl (10 mg, 0.24 mmol) in
methanol (5 mL). The mixture was stirred for 10 min, during which
time a white precipitate formed, and the solvent was removed in vacuo.
The residue was extracted with dichloromethane, and the suspension
was filtered through Celite. Addition of methanol to the filtrate and
evaporation in vacuo caused the product to precipitate as a colorless
solid, which was isolated by filtration, washed with methanol, and dried
in vacuo. The yield of 10 was 125 mg (97%).
1
Mp: 64−66 °C. H NMR: δ 7.34−7.42 (m, 6H, aromatic), 7.42−
7.49 (m, 4H, aromatic). 19F NMR: δ −119.6 (ddd, JFF = 5.7, 11.5, 24.5
Hz), −126.2 (ddd, JFF = 3.1, 11.4, 21.5 Hz), −151.0 (ddd, JFF = 5.8,
20.1, 21.4 Hz), −153.9 (ddd, JFF = 3.2, 19.6, 24.4 Hz). ESI-MS (m/z):
455.9 [M]+. Anal. Calcd for C18H10BrAsF4: C, 47.30; H, 2.21; F, 16.63.
Found: C, 47.46; H, 2.24; F, 16.57.
1H NMR: δ 2.01−2.62 (m, 6H, aliphatic COD), 2.62−2.98 (m, 2H,
aliphatic COD), 4.26 (m, 1H, JPtH = 64.9 Hz, olefinic COD), 4.94 (m,
1H, JPtH = 73.1 Hz, olefinic COD), 5.87 (m, 1H, JPtH = 39.3 Hz,
olefinic COD), 6.06 (m, 1H, JPtH = 38.9 Hz, olefinic COD), 7.26−7.36
(m, 3H, aromatic), 7.38−7.50 (m, 5H, aromatic), 7.50−7.61 (m, 2H,
aromatic). 19F NMR: δ −122.1 (dd, JFF = 14.9, 27.4 Hz, JPtF = 270
Hz), −122.4 (ddd, JFF = 4.9, 14.8, 23.5 Hz, JPtF ≈ 38 Hz), −153.1
(ddd, JFF = 5.0, 18.9, 27.4 Hz, JPtF = 82.8 Hz), −158.5 (dd, JFF = 18.9,
23.5 Hz, JPtF ≈ 19 Hz). ESI-MS (m/z): 739.0 [M + Na]+. Anal. Calcd
for C26H22AsClF4Pt: C, 43.67; H, 3.10; Cl, 4.95; F, 10.62. Found: C,
43.42; H, 3.06; Cl, 5.13; F, 10.54.
[PtI(κC-2-C6F4AsPh2)(1,5-COD)] (7). To a solution of 2-
BrC6F4AsPh2 (1.17 g, 2.56 mmol) in ether (20 mL), cooled to −78
°C, had been added nBuLi (1.6 M, 1.6 mL, 2.56 mmol) dropwise. After
the mixture was stirred for 30 min, [PtI2(1,5-COD)] (1.28 g, 2.3
mmol) was added. The mixture was stirred at −78 °C for several hours
and warmed to room temperature overnight. The orange solution was
removed by cannula from the off-white solid, which was washed with
Et2O (5 mL) and MeOH (5 mL) and recrystallized from CH2Cl2/
MeOH to give complex 7 as a colorless solid (1.53 g, 83%).
1H NMR: δ 1.81−2.03 (m, 1H, aliphatic COD), 2.03−2.32 (m, 3H,
aliphatic COD), 2.32−2.58 (m, 2H, aliphatic COD), 2.58−2.84 (m,
2H, aliphatic COD), 4.34 (m, 1H, JPtH = 64.3 Hz, olefinic COD), 5.08
(m, 1H, JPtH = 71.8 Hz, olefinic COD), 5.89 (m, 1H, JPtH = 43.6 Hz,
olefinic COD), 6.09 (m, 1H, JPtH = 42.7 Hz, olefinic COD), 7.24−7.35
(m, 3H, aromatic), 7.38−7.43 (m, 3H, aromatic), 7.43−7.50 (m, 2H,
aromatic), 7.50−7.58 (m, 2H, aromatic). 19F NMR: δ −119.6 (dd, JFF
= 14.1, 27.8 Hz, JPtF = 282 Hz), −122.7 (ddd, JFF = 5.1, 14.7, 23.7 Hz,
JPtF = 38.9 Hz), −153.3 (ddd, JFF = 5.2, 19.1, 27.7 Hz, JPtF = 83.4 Hz),
−158.8 (dd, JFF = 19.0, 23.7 Hz, JPtF = 17.6 Hz). ESI-MS (m/z): 829.9
[M + Na]+. Anal. Calcd for C26H22AsF4IPt: C, 38. 68; H, 2.75; F, 9.41.
Found: C, 38.85; H, 2.67; F, 9.21.
[PtBr(κC-2-C6F4AsPh2)(1,5-COD)] (11). Complex 11 was made
analogously to complex 10 from 8 (150 mg, 0.18 mmol) and LiBr (20
mg, 0.23 mmol) to give the product as a colorless solid (130 mg,
95%).
1H NMR: δ 1.86−2.12 (m, 1H, aliphatic COD), 2.12−2.40 (m, 3H,
aliphatic COD), 2.40−2.60 (m, 2H, aliphatic COD), 2.68−2.90 (m,
2H, aliphatic COD), 4.29 (m, 1H, JPtH = 68.6 Hz, olefinic COD), 4.98
(m, 1H, JPtH = 72.2 Hz, olefinic COD), 5.88 (m, 1H, JPtH = 42.6 Hz,
olefinic COD), 6.08 (m, 1H, JPtH = 36.6 Hz, olefinic COD), 7.26−7.36
(m, 4H, aromatic), 7.38−7.50 (m, 4H, aromatic), 7.50−7.61 (m, 2H,
aromatic). 19F NMR: δ −121.4 (dd, JFF = 14.8, 27.6 Hz, JPtF = 272
Hz), −122.6 (ddd, JFF = 5.2, 14.6, 23.6 Hz, JPtF ≈ 38 Hz), −153.1
(ddd, JFF = 5.1, 19.2, 27.6 Hz, JPtF = 80.8 Hz), −158.6 (dd, JFF = 19.0,
23.6 Hz, JPtF ≈ 17 Hz). ESI-MS (m/z): 783.0 [M + Na]+. Anal. Calcd
for C26H22AsBrF4Pt: C, 41.07; H, 2.92; Br. 10.51; F, 9.99. Found: C,
40.96; H, 2.91; Br. 10.72; F, 9.45.
[Pt(κ2As,C-2-C6F4AsPh2)(1,5-COD)]PF6 (8). To a solution of [PtI-
(κC-2-C6F4AsPh2)(1,5-COD)] (7; 400 mg, 0.50 mmol) in CH2Cl2
(40 mL) was added TlPF6 (260 mg, 0.74 mmol). The mixture was
shielded from light and stirred overnight. The resulting orange
suspension was filtered through Celite, and the solvent was removed in
vacuo. The residue was dissolved in the minimum amount of
dichloromethane, and ether was slowly added, precipitating a colorless
solid. The volume was reduced in vacuo, and more ether was added.
The colorless solid was isolated by filtration, washed with ether, and
dried. The yield of 8 was 381 mg (93%).
[PtI(μ-2-C6F4AsPh2)(1,5-COD)AuCl] (12). To a stirred solution of
[PtI(κC-2-C6F4AsPh2)(1,5-COD)] (7; 151 mg, 0.19 mmol) in
dichloromethane (150 mL) cooled to 0 °C was added [AuCl(tht)]
(60 mg, 0.19 mmol). After the mixture had been stirred for 10 min,
MeOH (20 mL) was added and the solution was filtered through
Celite. The filtrate was evaporated under reduced pressure, and the
precipitated colorless solid was isolated by filtration, washed with
MeOH, and dried. The yield of 12 was 174 mg (90%).
1H NMR: δ 1.80−3.25 (m, 8H, aliphatic COD), 4.23 (m, 0.5H, JPtH
= 61.5 Hz, olefinic COD), 4.37 (m, 0.5H, JPtH = 68.5 Hz, olefinic
COD), 4.53−4.88 (m, 1H, unresolved JPtH, olefinic COD), 6.21−6.65
(m, 2H, unresolved JPtH, olefinic COD), 7.35−7.70 (m, 8H, aromatic),
7.73−7.92 (m, 2H, aromatic). 19F NMR: δ −109.5 (ddd, JFF = 2.4,
1H NMR: δ 2.64 (br. s, 8H, aliphatic COD), 6.04 (m, 2H, JPtH
=
43.2 Hz, olefinic COD), 6.58 (m, 2H, JPtH = 64.7 Hz, olefinic COD),
7.56−7.68 (m, 10H, aromatic). 19F NMR: δ −73.1 (d, JPF = 713 Hz),
−128.2 (ddd, JFF = 5.3, 18.1, 23.7 Hz, JPtF = 82.3 Hz), −132.5 (ddd, JFF
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Organometallics
Article
12.8, 28.8 Hz, JPtF = 312 Hz), −110.0 (ddd, JFF = 2.4, 12.9, 29.0 Hz,
JPtF = 309 Hz), −111.9 (ddd, JFF = 2.6, 12.8, 28.8 Hz, JPtF = 302 Hz),
−112.3 (ddd, JFF = 2.4, 12.8, 28.8 Hz, JPtF = 302 Hz), −121.1 (m),
−121.4 (m), −148.7 (ddd, JFF = 6.8, 19.5, 28.7 Hz, unresolved JPtF),
−148.9 (ddd, JFF = 6.7, 19.2, 28.5 Hz, unresolved JPtF), −149.2 (ddd,
JFF = 6.4, 19.4, 28.9 Hz, unresolved JPtF), −149.4 (ddd, JFF = 6.5, 19.5,
29.1 Hz, unresolved JPtF), −156.6 (ddd, JFF = 2.6, 19.8, 22.3 Hz,
unresolved JPtF), −156.7 (ddd, JFF = 2.8, 19.6, 22.5 Hz, unresolved
JPtF), −156.8 (ddd, JFF = 2.5, 19.6, 22.4 Hz, unresolved JPtF), −157.0
(ddd, JFF = 2.4, 19.6, 22.2 Hz, unresolved JPtF). ESI-MS (m/z): 1061.9
[M + Na]+ for 12, 1153.8 and 970.9 [M + Na]+ for 13 and 14,
respectively. Anal. Calcd for C26H22AsAuClF4IPt: C, 30.03; H, 2.13; F,
7.31; I, 12.20. Found: C, 29.50, H, 2.11; F, 7.13; I, 12.05.
the residue, and the suspension was stirred for 10 min. After the
mixture had been set aside for 1 h, the solid was filtered off and
dissolved in a small amount of dichloromethane and ether was slowly
added, precipitating a colorless solid. The volume was reduced in
vacuo, more ether was added, and the solid was isolated by filtration.
The colorless precipitate was washed with ether and dried in vacuo.
The yield of 15 was 340 mg (79%).
1H NMR: δ 2.67 (br. s, 8H, aliphatic COD), 6.17 (m, 2H, JPtH = 39
Hz, olefinic COD), 6.70 (m, 2H, JPtH = 63 Hz, olefinic COD), 7.55−
7.73 (m, 10H, aromatic). 19F NMR: δ −78.2 (s), −128.5 (m), −132.4
(m), −146.7 (ddd, JFF = 5.8, 19.1, 22.7 Hz, JPtF = 67.4 Hz), −150.3
(apparent t, JFF = 20.1 Hz, unresolved JPtF). ESI-MS (m/z): 680.1 [M
− OTf]+. Anal. Calcd for C27H22AsF7O3PtS: C, 39.09; H, 2.67; F,
16.03; S, 3.86. Found: C, 39.27; H, 2.67; F, 16.02; S, 3.77.
[PtI(μ-2-C6F4AsPh2)(1,5-COD)AuI] (13). To a solution of [PtI(κC-2-
C6F4AsPh2)(1,5-COD)AuCl] (12; 130 mg, 0.13 mmol) in CH2Cl2 (5
mL) was added NaI (55 mg, 0.37 mmol) in MeOH (5 mL). Workup
as described for 10 gave complex 13 as a colorless solid (131 mg,
93%).
ASSOCIATED CONTENT
■
S
* Supporting Information
1H NMR: δ 1.81−2.12 (m, 3H, aliphatic COD), 2.12−2.36 (m, 1H,
aliphatic COD), 2.41−2.64 (m, 1H, aliphatic COD), 2.64−2.81 (m,
2H, aliphatic COD), 2.83−3.09 (m, 1H, aliphatic COD), 4.35 (m, 1H,
JPtH = 62.2 Hz, olefinic COD), 4.66 (m, 1H, JPtH = 70.2 Hz, olefinic
COD), 6.30−6.58 (m, 2H, unresolved JPtH, olefinic COD), 7.33−7.68
(m, 8H, aromatic), 7.81−7.93 (m, 2H, aromatic). 19F NMR: δ −110.0
(ddd, JFF = 2.3, 12.8, 29.0 Hz, JPtF = 307 Hz), −121.4 (6.4, 12.8, 22.4
Hz, JPtF = 42.4 Hz), −149.4 (ddd, JFF = 6.3, 19.5, 28.9 Hz, JPtF = 80
Hz), −156.8 (ddd, 2.5, 19.6, 22.3 Hz, JPtF ≈ 13 Hz). ESI-MS (m/z):
1153.8 [M + Na]+. Anal. Calcd for C26H22AsAuI2F4Pt: C, 27.61; H,
1.96; F, 6.72; I, 22.44. Found: C, 27.38; H, 2.02; F, 6.87; I, 22.30.
[PtCl(μ-2-C6F4AsPh2)(1,5-COD)AuCl] (14). This complex was made
similarly to 12 from [PtCl(κC-2-C6F4AsPh2)(1,5-COD)] (10; 154 mg,
0.22 mmol) and [AuCl(tht)] (69 mg, 0.22 mmol) and obtained as a
colorless solid (194 mg, 95%).
CIF files giving crystallographic data and a table giving crystal
data and details of data collection and structure refinement for
compounds 7 (two modifications), 8, 9, 12, 15, and 16. This
material is available free of charge via the Internet at http://
pubs.acs.org. The CCDC entries 963185 (7, in Pna21), 963184
(7, in P21), 963187 (8), 963190 (9), 963186 (12), 963188
(15), and 963189 (16) also contain supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
AUTHOR INFORMATION
■
Notes
1H NMR: δ 1.96−2.23 (m, 2H, aliphatic COD), 2.23−3.98 (m, 5H,
aliphatic COD), 3.02−3.25 (m, 1H, aliphatic COD), 4.24 (m, 1H, JPtH
= 63.6 Hz, olefinic COD), 4.67 (m, 1H, JPtH = 73.5 Hz, olefinic COD),
6.32 (m, 1H, JPtH ≈ 45 Hz, olefinic COD), 6.54 (m, 1H, JPtH ≈ 41 Hz,
olefinic COD), 7.37−7.54 (m, 5H, aromatic), 7.54−7.68 (m, 3H,
aromatic), 7.74−7.87 (m, 2H, aromatic). 19F NMR: δ −111.9 (ddd, JFF
= 2.7, 12.9, 28.8 Hz, JPtF = 303 Hz), −121.1 (ddd, JFF = 6.5, 12.7, 22.2
Hz, JPtF ≈ 37 Hz), −148.7 (ddd, JFF = 6.7, 19.5, 28.8 Hz, JPtF = 80.4
Hz), −156.7 (ddd, JFF = 2.6, 19.6, 22.0 Hz). ESI-MS (m/z): 970.9 [M
+ Na]+. Anal. Calcd for C26H22AsAuCl2F4Pt: C, 32.93; H, 2.34; Cl,
7.48; F, 8.01. Found: C, 32.96; H, 2.40; Cl, 7.79; F, 8.10.
[PtMe(κC-2-C6F4AsPh2)(1,5-COD)] (15). To an ice-cooled solution
of [PtI(κC-2-C6F4AsPh2)(1,5-COD] (7; 500 mg, 0.62 mmol) in
dichloromethane (40 mL) was added ZnMe2 (2.0 M solution in
toluene, 200 μL, 0.4 mmol). The turbid solution was stirred for 15 min
and then warmed to room temperature and evaporated to dryness.
The residue was dissolved in dichloromethane and the solution filtered
through Celite. Methanol was added to the filtrate, and the volume of
the solution was reduced in vacuo. The precipitated colorless solid was
filtered off, washed with methanol, and dried. The yield of 15 was 408
mg (95%).
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank Mr. Erik Wachtler for his help in the structural
̈
analysis of compound 12.
REFERENCES
■
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̈
1H NMR: δ 0.78 (s, 3H, JPtH = 78.7 Hz, methyl), 2.10−2.76 (m, 8H,
aliphatic COD), 4.57 (m, 1H, JPtH = 54.1 Hz, olefinic COD), 5.06 (m,
2H, unresolved JPtH, olefinic COD), 5.24 (m, 1H, JPtH = 43.7 Hz,
olefinic COD), 7.28−7.44 (m, 8H, aromatic), 7.46−7.54 (m, 2H,
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Hz), −123.3 (ddd, JFF = 4.4, 16.2, 23.7 Hz, JPtF = 67.2 Hz), −155.2
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