Bismuth-halide oxidative addition and bismuth-carbon reductive elimination in platinum complexes containing chelating diphosphine ligands

Article abstract of DOI:10.1021/ic4018745

Reaction of BiX₃ (X = Cl, Br, I) with [PtMe₂(P-P)], (1a, P-P = dppm; 1b, P-P = dppe), occurs easily to yield a mixture of platinum(II) complexes [PtMeX(P-P)], 2, and [PtX₂(P-P)], 3, and the binuclear complex [Pt₂Me₂(μ-X)(μ-dppm) ₂]X, 4. On the basis of ³¹P NMR and UV-vis spectroscopy, a mechanism is proposed in which the rate determining step is conversion of the yellowish Pt(II)-BiX₃ adduct BiI₃·[PtMe ₂(dppm)], A, into the Pt(IV)-Bi(III) intermediate [PtMe ₂(BiX₂)X(P-P)], IM1. Density functional theory (DFT) studies suggest that intermediate IM1 may be formed in acetone solution which undergoes the Bi-C reductive elimination process before formation of complexes 2 and 3. The structures of intermediates IM1 were theoretically determined using DFT calculations. In dilute acetone solution, as monitored by UV-vis spectroscopy, the oxidative addition processes follow first order kinetics. The overall reaction is slower for heavier halide.

Full text of DOI:10.1021/ic4018745

Article
pubs.acs.org/IC
Bismuth−Halide Oxidative Addition and Bismuth−Carbon Reductive
Elimination in Platinum Complexes Containing Chelating
Diphosphine Ligands
S. Masoud Nabavizadeh,*,† Fatemeh Niroomand Hosseini,*,‡ Negar Nejabat,† and Zahra Parsa†
†Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran
‡Department of Chemistry, Shiraz Branch, Islamic Azad University, Shiraz 71993-37635, Iran
ABSTRACT: Reaction of BiX3 (X = Cl, Br, I) with [PtMe2(P−P)], (1a, P−P = dppm; 1b, P−P = dppe), occurs easily to yield a
mixture of platinum(II) complexes [PtMeX(P−P)], 2, and [PtX2(P−P)], 3, and the binuclear complex [Pt2Me2(μ-X)(μ-
dppm)2]X, 4. On the basis of 31P NMR and UV−vis spectroscopy, a mechanism is proposed in which the rate determining step is
conversion of the yellowish Pt(II)-BiX3 adduct BiI3·[PtMe2(dppm)], A, into the Pt(IV)−Bi(III) intermediate [PtMe2(BiX2)-
X(P−P)], IM1. Density functional theory (DFT) studies suggest that intermediate IM1 may be formed in acetone solution
which undergoes the Bi−C reductive elimination process before formation of complexes 2 and 3. The structures of intermediates
IM1 were theoretically determined using DFT calculations. In dilute acetone solution, as monitored by UV−vis spectroscopy, the
oxidative addition processes follow first order kinetics. The overall reaction is slower for heavier halide.
Lewis acidity, low toxicity, air stability, low cost, and ease of
handling.7
INTRODUCTION
■
Oxidative addition reaction of different polar and nonpolar
reagents to transition metal complexes has been extensively
investigated and is considered as a key step in many catalytically
important chemical processes.1 In particular, the related
reactions involving Pt complexes with a wide variety of
reagents have been studied in detail.2 Oxidative addition of
heavy metal compounds to transition metal complexes has also
been investigated, and the addition of reagents including Sn−X,
Hg−X, Te−X, and Ge−X bonds (X = halogen), to electron
rich platinum(II) centers have been reported.3 Besides,
Braunschweig and co-workers have recently reported the
oxidative addition of the bismuth-chloride bond to a Pt(0)
complex.4 As such, the BiCl3 reagent acts as a Lewis-acid
because of the relativistic contraction of the valence 6s Bi AO,5
and the nucleophilic Pt(0) center in the first place attacks the
Bi−Cl σ*-orbital.4
On the other hand, reductive elimination reactions are
among the most fundamental organometallic processes. In
contrast to many reports on reductive elimination of R−R, R−
H, Ar−Ar, and C−X,6 on the basis of our knowledge, no studies
on reductive elimination of Bi−C bonds from Pt(IV)
complexes have been reported, although organobismuth
compounds are useful in organic synthesis because of mild
In continuation of our interest in the investigation of
oxidative addition reactions of different types of reagents to
organoplatinum complexes,8 in the present work, we have
studied the reactions of platinum(II) complexes [PtMe2(P−
P)], 1, in which P−P = 1,1−bis(diphenylphosphino)methane
(dppm) or 1,2-bis(diphenylphosphino)ethane (dppe), with
bismuth trihalides, BiX3 (X = Cl, Br, I). This seems to be the
first example of bismuth−halide oxidative addition to
organoplatinum(II) complexes and bismuth−carbon reductive
elimination from Pt(IV) complexes.
EXPERIMENTAL SECTION
■
The NMR spectra were recorded as CDCl3 or acetone-d6 solutions on
a Bruker Avance DRX 500 MHz spectrometer. The operating
frequencies and references, respectively, are shown in parentheses as
1
follows: H (500 MHz, TMS) and 31P (202 MHz, 85% H3PO4). All
the chemical shifts and coupling constants are given in units of ppm
and Hz, respectively. The absorption spectra and kinetic studies were
measured using a Perkin−Elmer Lambda 25 UV−vis spectrometer
with temperature control using an EYELA NCB−3100 constant-
temperature bath. The complexes [PtMe2(dppm)]9 and
Received: July 20, 2013
© XXXX American Chemical Society
A
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Scheme 1
Figure 1. Reaction of complex [PtMe2(dppm)], 1a, with BiI3 as monitored by variable-temperature 31P NMR spectroscopy in acetone-d6; (a) Pure
1a at −28 °C, (b) immediately after addition of BiI3 at −28 °C, (c) 6 min after addition of BiI3 at −28 °C, (d) 12 min after addition of BiI3 at −8 °C,
(e) 18 min after addition of BiI3 at 16 °C, (f) 25 min after addition of BiI3 at 27 °C, and (g) 1 h after addition of BiI3 at 27 °C. Peak assignments are
shown; platinum satellites are observed and shown for all involved species.
[PtMe2(dppe)]10 were prepared as reported. The Pt(II) compounds
[PtMe(X)(P−P)] (PP = dppm9 or dppe11), 2, [Pt(X)2(P−P)],12 3,
and [Pt2Me2(μ-X)(μ-dppm)2]X, 4,9b,13 were characterized by
Reaction of [PtMe2(dppm)] with BiI3. Selected NMR data for 3c
in CDCl3: δ(31P) −71.1 [s, 1JPtP = 2880 Hz]; δ(1H) 4.60 [t, 2JPH = 22.0
3
Hz, JPtH = 34.1 Hz; 2H, CH2P2].
1
comparing their H and 31P NMR spectra with those of the authentic
Reaction of [PtMe2(dppe)] with BiCl3. Selected NMR data for
2d in CDCl3: δ(31P) 44.0 [s, 1JPtP = 1725 Hz, P trans to Me], 43.1 [s,
samples. The byproducts of the reactions were BiMeX2 and BiMe2X
14
3
1JPtP = 4264 Hz, P trans to Cl]; δ(1H) 0.62 [dd, JP(trans)H = 8.1 Hz,
1
which were identified from their reported H NMR data.
2
3JP(cis)H = 3.9 Hz, JPtH = 54.0 Hz, 3H, Pt−Me], 2.41 [br, 4H,
Reaction of [PtMe2(dppm)] with BiCl3. To a solution of
[PtMe2(dppm)] (50 mg, 0.08 mmol) in 20 mL of acetone was added
BiCl3 (25.9 mg, 0.08 mmol). The solution was stirred for 2 h. The
solvent was removed, and the resulting residue was dried to form a
PCH2CH2P].
Reaction of [PtMe2(dppe)] with BiBr3. Selected NMR data in
CDCl3, 2e (70%): δ(31P) 41.2 [s, 1JPtP = 1745 Hz, P trans to Me], 36.2
[s, 1JPtP = 4241 Hz, P trans to Br]; δ(1H) 0.75 [dd, 3JP(trans)H = 8.2 Hz,
white solid as a mixture of 3a and 4a (see Scheme 1). Selected NMR
1
data for 3a (30%, minor product) in CDCl3: δ(31P) −64.0 [s, JPtP
=
2
3JP(cis)H = 4.1 Hz, JPtH = 55.9 Hz, 3H, Pt−Me], 2.33 [br, 4H,
3070 Hz]; δ(1H) 4.62 [br, 2H, CH2P2]. Selected NMR data for 4a
(70%, major product): δ(31P) 13.6 [s, 1JPtP = 3033 Hz]; δ(1H) 0.50 [t,
1
PCH2CH2P]; 3e (30%): 44.8 [s, JPtP = 3560 Hz].
Reaction of [PtMe2(dppe)] with BiI3. Selected NMR data in
3JPH = 8.1 Hz, JPtH = 88.0 Hz, 6H, Pt−Me], 4.15 [br, 2H, CH2P2].
2
CDCl3, 2f (50%): δ(31P) 45.2 [s, 1JPtP = 1725 Hz, P trans to Me], 45.9
1
3
[s, JPtP = 4072 Hz, P trans to I]; δ(1H) 0.80 [dd, JP(trans)H = 7.0 Hz,
The following reactions were done similarly by using the
appropriate starting complexes 1a or 1b and BiX3 (X = Cl, Br, I).
Reaction of [PtMe2(dppm)] with BiBr3. Selected NMR data for
3JP(cis)H = 3.1 Hz, JPtH = 54.1 Hz, 3H, Pt−Me], 2.25 [br, 4H,
2
1
PCH2CH2P]; 3f (50%): 46.0 [s, JPtP = 3375 Hz].
1
3b (50%) in CDCl3: δ(31P) −63.8 [s, JPtP = 3030 Hz]; δ(1H) 4.58
Monitoring the Reaction of [PtMe2(dppm)] with BiI3 by 31P
NMR Spectroscopy. To a solution of [PtMe2(dppm)] (10 mg, 0.016
mmol) in acetone-d6 (0.7 mL) in an NMR tube was added BiI3 (9.7
mg, 0.016 mmol). The tube was then placed in the probe of the NMR
[br, 2H, CH2P2]. Selected NMR data for 4b (50%): δ(31P) 13.5 [s,
3
2
1JPtP = 3024 Hz]; δ(1H) 0.52 [t, JPH = 7.0 Hz, JPtH = 85.0 Hz, 6H,
Pt−Me], 4.21 [br, 2H, CH2P2].
B
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Scheme 2. Suggested Mechanism for the Reactions of Complexes 1 with BiX3
spectrometer, and 31P NMR spectra were obtained at appropriate
intervals.
Theoretical Methods. Geometry optimizations were performed
with the program suite Gaussian03 at the DFT/B3LYP level.15 The
effective core potential of Hay and Wadt with a double-ξ valence basis
set (LANL2DZ)16 was chosen to describe Pt, Bi, Cl, Br, and I. The 6-
31G* basis set was used for C, H, and P atoms. To evaluate and ensure
the optimized structures of the molecules, frequency calculations were
carried out using analytical second derivatives. The bond orders were
calculated using the Chemissian program.17
RESULTS AND DISCUSSION
■
Reactions of Dimethylplatinum(II) Complexes with
BiX3. As is depicted in Scheme 1, reaction of the complexes
[PtMe2(P−P)], 1, with BiX3 in 1:1 molar ratio gave a mixture
of the monomeric complexes [PtMe(X)(P−P)], 2, and
[Pt(X)2(P−P)], 3, and the binuclear complex [Pt2Me2(μ-
Figure 3. Absorbance (at 490 nm)−time curves for the reaction of
[PtMe2(dppm)], 1a, with BiI3 in acetone at temperatures of 10, 20, 25,
30, and 40 °C (temperature increases reading downward).
X)(μ-dppm)2]X, 4. The products were characterized using 31P
1
and H NMR spectroscopy, details of which are described in
the Experimental Section.
The reaction of chelating dppm complex 1a with BiI3 was
monitored using variable-temperature 31P NMR spectroscopy,
as shown in Figure 1. On the basis of the results obtained from
the 31P NMR and UV−vis spectroscopies (see next section), a
mechanism described in Scheme 2 is suggested to occur during
the reaction progress. Note that complexes 1a, 2c, and 3c were
characterized by comparing their 1H and 31P NMR spectra with
those of the authentic samples and so their characteristic 31P
NMR data were used to indicate the complexes. Thus,
immediately after the addition of BiI3 at −28 °C, a broad
1
singlet signal at δ −40.3 (with JPtP = 1455 Hz) which is
assigned to a Pt(II)→Bi(III) adduct BiI3·[PtMe2(dppm)], A
(see Scheme 2), was observed.18 The formation of adduct A
was further confirmed using UV−vis studies (see next section).
Meanwhile, a Pt(II) species assigned as the complex [PtMeI-
Figure 2. Changes in the UV−vis spectrum during the reaction of
[PtMe2(dppm)] with BiI3 (each 1.0 × 10−4 M) in acetone at 25 °C:
(a) pure 1a; (b) pure BiI3; (c) spectrum immediately after addition of
BiI3; successive spectra recorded at intervals of 30 s.
C
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a
1JPtP = 1279 Hz, due to the P atom locating trans to Me with
Table 1. Rate Constants and Activation Parameters for
Oxidative Addition of Bi−X Bonds to Complex 1a in
Acetone Solvent
comparatively higher trans influence than I,19 and JPP = 45
2
Hz). As time passed and the temperature increased, the signal
due to adduct A disappeared while those due to the complex 2c
grew and then later started to decrease, and meanwhile a
reagent
BiCl3
T/°C
102 k/s−1
ΔH⧧/kJ mol−1
ΔS⧧/J K−1 mol−1
−98 14
10
20
25
30
40
10
20
25
30
40
10
20
25
30
40
0.90
1.52
2.86
4.12
7.89
0.51
1.00
1.53
2.56
5.19
0.17
0.30
0.43
0.75
1.45
52.8 4.3
1
comparatively weak singlet signal, at δ −69.8 with JPtP = 2866
Hz, due to the monomeric complex [PtI2(dppm)], 3c, was also
observed. As the reaction progressed, only complex 3c obtained
pure which was found by DFT to be more stable as compared
1
to complex 2c (see theory section). The H NMR spectrum
BiBr3
55.7 2.9
−99 10
was recorded at the end of the reaction, and the observation of
one singlet signal at δ 2.27 ppm confirmed the formation of
BiMe2I.
UV−visible Studies of the Reaction of [PtMe2(dppm)],
1a, with BiX3. The kinetics of the reaction of equimolar
amounts of complex [PtMe2(dppm)], 1a, and bismuth
trihalides in acetone solution were studied by using UV−vis
spectroscopy. A series of spectra, recorded during the reaction
of complex 1a with BiI3, is shown in Figure 2. The complex 1a
is colorless, and no MLCT band in the visible region was
observed for this complex. Immediately after addition of BiI3 to
a solution of complex 1a under second-order 1:1 stoichiometric
conditions, a new broad absorption band at 490 nm was
observed. It is worthy to mention that when we performed the
reaction in the presence of excess BiI3, the reaction was too fast
for any reasonable measurement. The absorption at 490 nm is
ascribed to the 5dπ (Pt)→(Bi−I σ*-orbital) charge transfer
band, which is suggested to be responsible for the yellowish
color of the adduct A and is used to study the kinetics of the
oxidative addition reaction. The assignment of this absorption
to other complexes, shown in Scheme 2, is ruled out because
the intermediates IM1 and IM2 containing Pt(IV) center are
not expected to contain any charge transfer and complexes 1, 2,
3, and 4 are colorless. Notice that it has been reported that the
complex [PtCl(PCy3)2{BiCl2}], having a Pt(II)−Bi(III) bond,
has an orange color in tetrahydrofuran (THF) solution.4 Also
formation of such adducts for Pt(II) complexes has been
reported in the reaction of [PtMe2(bipy)] with iodine.8e On the
basis of a fully optimized ground-state structure (see theory
section), time-dependent TDF (TD-DFT) has been also used
to predict the absorbance spectra of adduct A and intermediate
IM1c. For adduct A, the TD-DFT calculation predicts one
intense electronic transition at 477 nm in good agreement with
the observed experimental data (λexp. = 490 nm in acetone).
The calculated electronic spectrum of complex IM1c shows
one electronic transition at 384 nm. As is clear from TD-DFT
calculation, the observed experimental wavelength at 490 nm is
in good agreement with the calculated one for adduct A, giving
more support for the assignment of yellowish color to adduct
A.
BiI3
51.9 3.9
−115 13
a
Estimated errors in k values are 5%.
Figure 4. Eyring plots for the oxidative addition of complex 1a with
(a) BiCl3; (b) BiBr3; (c) BiI3 in acetone.
From the 31P NMR and UV−vis observations, the formation
of the adduct A was too fast for monitoring, but the conversion
of the adduct A to form Pt(IV) intermediate IM1c could be
studied by monitoring the decay of the absorption band of the
adduct A at 490 nm. Typical plots of absorbance at λ = 490 nm
versus time are shown in Figure 3. The disappearance of the
adduct A to form the intermediate complex IM1c followed
good first-order kinetics, as confirmed by fitting the data with
the first order equation At = (A0 − A∞) exp(−kt) + A∞. The
first order rate constants at different temperatures are given in
Table 1. Activation parameters were then obtained in the usual
way from the Eyring equation (Figure 4), and the data are
collected in Table 1.
Figure 5. Absorbance−time curve for the reaction of [PtMe2(dppe)],
1b, with BiBr3, under 1:1 stoichiometric condition, in acetone at 25
°C. The monoexponential fit for the reaction is shown.
(dppm)], 2c, was also detected with two doublet signals at δ
1
2
−46.5 (with JPtP = 3702 Hz and JPP = 45 Hz, due to P atom
trans to I) and at δ −47.3 (having a significantly lower value of
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Scheme 3. Structural Changes in Oxidative Addition of BiCl3 to Complex [PtMe2(dppm)], 1a, and the Optimized Geometries in
Acetone Solvent
Table 2. Computed Reaction Enthalpies and Free Energies (Values in kcal mol−1) for Each Step Reaction of BiX3 (X = Cl, Br, I)
with [PtMe2(P−P)], P−P =dppm, 1a; P−P =dppe,1b, in Acetone
X = Cl
X = Br
X = I
a
a
a
reaction
ΔH
ΔG
ΔH
P−P = dppm
ΔG
ΔH
ΔG
1a + BiX3→IM1
IM1→2 + MeBiX2
2 → (1/2) 4
−22.5
−12.4
2.6
−8.4
−26.7
7.3
−20.9
−15.3
0.9
−6.4
−29.6
5.7
−17.9
−17.6
0.7
−1.8
−32.8
5.8
2 + XBiMeX→IM2
IM2→3 + Me2BiX
10.9
24.8
12.2
26.3
13.3
28.1
−18.9
−32.0
−20.2
−34.0
−22.0
−36.4
P−P = dppe
1b + BiX3→IM1
IM1→2 + MeBiX2
2 + XBiMeX→IM2
IM2→3 + Me2BiX
−17.8
−16.2
6.0
−5.4
−30.4
28.1
−15.7
−19.2
19.0
−3.4
−33.7
36.9
−12.2
−22.2
21.8
1.1
−37.3
38.3
−24.3
−36.4
−27.1
−45.3
−29.7
−45.5
a
At 298.15 K and 1 atm.
Figure 6. Free energy profiles for reaction of BiX3 (X = Cl, Br, I) with [PtMe2(dppm)] (left) and [PtMe2(dppe)] (right) in acetone.
When the reaction of complex [PtMe2(dppe)], 1b, with
BiBr3 was performed in acetone at 25 °C, the oxidative addition
process (see Figure 5) occurred at a slower rate, with k = 0.38
( 0.03) × 10−2 s−1, as compared with the value of k = 1.53
( 0.07) × 10−2 s−1 for the related reaction involving dppm
complex [PtMe2(dppm)], 1a, at the same condition.
DFT Investigation of the Product Formation. The
oxidation state +2 (d8) is undoubtedly the most common
oxidation state for Pt metal. The stereochemistry of Pt(II) four
coordinate complexes is square planar especially with strong
field ligands such as methyl. The oxidative addition process is
considered here with an emphasis on the differences between
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Table 3. Energies (eV) and Main Compositions (%) of the Relevant Frontier Orbitals of Species Involved in the Reaction of
Complex 1a with BiCl3 (X = Cl, Br, I)
composition (%)
a
orbital
E (eV)
Pt
Bi
X
[PtMe2(dppm)]
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
−5.137
−1.002
−8.720
−3.370
−8.117
−3.648
−7.534
−3.989
−6.056
−1.961
−5.789
−2.271
−5.527
−2.591
−5.447
−1.237
−5.247
−1.263
−4.979
−1.306
−5.808
−2.301
−5.577
−2.529
−5.319
−2.727
−5.763
−1.502
−5.513
−1.696
−5.099
−1.740
70
3
BiCl3
100
40
100
44
100
44
52
9
60
56
BiBr3
BiI3
56
10
41
5
[PtCl(BiCl2)Me2(dppm)], IM1a
[PtBr(BiBr2)Me2(dppm)], IM1b
[PtI(BiI2)Me2(dppm)], IM1c
[PtMe(Cl)(dppm)], 2a
[PtMe(Br)(dppm)], 2b
[PtMe(I)(dppm)], 2c
[Pt(Cl)2(BiMeCl)Me(dppm)], IM2a
[Pt(Br)2(BiMeBr)Me(dppm)], IM2b
[Pt(I)2(BiMeI)Me(dppm)], IM2c
[Pt(Cl)2(dppm)], 3a
[Pt(Br)2(dppm)], 3b
[Pt(I)2(dppm)], 3c
16
23
9
70
10
78
10
41
1
21
6
43
3
19
25
3
44
18
2
58
1
12
5
71
1
21
27
8
15
20
1
46
14
83
16
86
20
68
11
77
13
86
18
26
5
22
1
25
26
26
1
22
24
2
25
a
Coordinated to Pt in platinum complexes.
the nature of the halides (Cl, Br, and I) in three bismuth(III)
halides. The processes shown in Scheme 2 will be explored on
the basis of DFT calculations.
trans to a BiMeX group with different bond lengths. For
example, in complex IM2a, these Pt−Cl bond distances are
2.522 and 2.581 Å, respectively. During the oxidative addition
of Cl−BiClMe bond to complex 2a, the Pt−Me, Pt−P (trans to
Me), Pt−P (trans to Cl), and Pt−Cl bond distances increase
from 2.085, 2.430, 2.257, and 2.455 Å in complex 2a to 2.098,
2.540, 2.318, and 2.522 Å in complex IM2a, respectively (see
Scheme 3). The Pt−Bi distance decreases from far apart in
reactant 2a and Cl−BiClMe to 2.802 Å in intermediate IM2a.
Finally, the Me−BiMeX reductive elimination from IM2 occurs
easily to form more stable complex 3.
Free energy changes along these paths are given in Figure 6.
We found that the first oxidative addition of BiX3 to the Pt(II)
complexes 1 to yield the complexes IM1 is exergonic for most
of halides and span a range of 1.1 kcal mol−1 to −8.4 kcal mol−1
as shown in Table 2 and Figure 6. When P−P = dppm, the free
energies of this process (1 + BiX3→IM1) are slightly lower
than the related free energies calculated for P−P = dppe which
is due to presence of ring strain in 4-membered rings of dppm
complexes. The second oxidative addition reactions (i.e., 2 +
XBiMeX →IM2) are endergonic for all halides and P−P. This
suggests that the second oxidative addition is more difficult
compared to the first oxidative addition, probably because of
the presence of a halide ligand which reduces the electron
In the related reaction profile in acetone solvent, shown in
Scheme 3 (see Table 2 for calculated results), the metal center
of [PtMe2(P−P)] attacks the bismuth atom of the oxidative
addition reagent BiX3 while the X atom leaves and the Pt(IV)
complex, IM1, is formed. As such, the Pt−Me and Pt−Bi bond
distances vary more substantially than any other bond lengths.
For example as shown in Scheme 3, in the case of P−P = dppm
and X = Cl, the Pt−C(Me) distance increases from 2.090 Å in
complex 1a to 2.123 Å in intermediate IM1a, whereas the Pt−
Bi distance decreases from far apart in reactant 1a and BiCl3 to
2.693 Å in intermediate IM1a. In the intermediate IM1, one of
the Bi−X bonds is completely broken while the Pt−Bi bond is
formed. The resulting d6 complex [PtX(BiX2)Me2(P−P)] (X =
Cl, Br, I) adopts an octahedral conformation with the bismuth
group BiX2 and X being in the trans position. The Pt(IV)
complexes [PtX(BiX2)Me2(dppm)], IM1, easily undergo
X2Bi−Me reductive elimination to produce complexes 2.
Then the Pt(II) center of complex 2 attacks to the bismuth
atom of X−BiXMe under a second oxidative addition process
to form the Pt(IV) intermediates IM2. The complex IM2
contains two Pt−X bonds, one trans to a P atom and another
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energies for the reaction 1 + BiX3→IM1 are −8.4, −6.4, and
−1.8 kcal mol−1 for X = Cl, Br, and I, respectively. On the basis
of HSAB (hard and soft acids and bases) principles, the Pt(IV)
center is harder than the Pt(II) center, and the preference for
halides toward the Pt(IV) center follows the order Cl > Br > I.
Conversely, the free energies for the reductive elimination
reactions IM1→2 + MeBiX2 are −26.7, −29.6, and −32.8 kcal
mol−1 for X = Cl, Br, and I, respectively. This can also be
explained on the basis of the HSAB principle, which suggests
the preference for the halides as Cl < Br < I for the soft Pt(II)
center of complexes 2.
Scheme 4. Suggested Mechanism for Oxidative Addition of
BiI3 to Complex 1a and Bi−C Reductive Elimination Form
Complex IM1c
The HSAB principle can also be used to explain the
experimental product ratios in the reactions of BiX3 with
complexes 1. The percentage of complexes 3, compared to
complexes 2, increases according to Cl < Br < I. For example in
the reaction 1a with BiX3, the percentage of complexes 3 is 30,
70, and 100% for X = Cl, Br, and I, respectively. The same was
observed in the reaction of 1b with BiX3 as 0, 30, and 50% for X
= Cl, Br, and I, respectively. The preference of X toward the
soft Pt(II) center is I > Br > Cl, so due to the greater tendency
of I to bind the soft Pt(II) center, the ratio of complexes 3 with
two X ligands will be increased as I > Br > Cl. The free energies
for reductive elimination processes have large negative values
(ranging from −26.7 to −36.4 kcal mol−1 for P−P = dppm and
from −5.4 to −45.5 kcal mol−1 when P−P = dppe).
While the Pt(IV)−M complexes (M = Sn, Hg, Te, and Ge)
can simply be prepared,3b,d,e,i the related Pt(IV)−Bi(III)
analogues are not stable and easily undergo Bi−C reductive
elimination. To verify this, we calculated the reaction profiles
and energies for the Bi−I oxidative addition to complex 1a and
Bi−C reductive elimination from the intermediate complex
IM1c in acetone solution (see Scheme 4 and Figure 7). The
calculation indicates an easy reaction to give the adduct A,
followed by a slower reaction to give B and IM1c. Note that, in
the kinetic experiments, the loss of adduct A is measured so
that the rates refer to formation of IM1c. The calculation of the
energy of the transition state TS1 (+15.2 kcal mol−1) is in
reasonable agreement with the observed value of ΔH⧧ = 12.4
kcal mol−1. It is suggested that the reductive elimination from
5-coordinate d6 metal complexes occurs more easily than from
the corresponding 6-coordinate complexes.20 So, the Me-BiI2
reductive elimination from the saturated d6 six-coordinate
complex IM1c may occur via initial loss of iodide ligand. The
BiMeI2 reductive elimination from intermediate B proceeds
through transition state TS2, (Scheme 4), in which the bonds
between Pt and leaving groups (Me and BiI2) are elongated and
the Me−Pt-Bi bond angle is reduced. The free energy of
activation for reductive elimination process is 6.4 kcal mol−1. As
BiMeI2 dissociates, the Pt(II)−I bond is formed giving the
complex 2c. Our calculations show that following oxidative
addition, the Bi−C reductive elimination barrier is rather small
suggesting that the Pt(IV)−Bi(III) complex is very prone to
undergo the reductive elimination decreasing the possibility of
identifying the Pt(IV) complexes from the experimental point
of view which is consistent with the experimental observations.
Figure 6 shows free energy profiles for reaction of BiX3 (X = Cl,
Br, I) with [PtMe2(dppm)] (left) and [PtMe2(dppe)] (right)
in acetone.
Figure 7. Relative energies (kcal mol−1) for product 2c, adduct A,
intermediate IM1c and B, and transition states TS1 and TS2, arising
from the reaction of 1a + BiI3 (E = 0) in acetone solution.
density of Pt(II) center in complexes 2. As shown in Table 3
(see next section), in [PtMe2(dppm)] as an example, the
highest occupied molecular orbital (HOMO) is localized on the
2
platinum atom (70% Pt) with significant contribution of the dz
orbital, but in complex [PtMe(Cl)(dppm)], 2a, the composi-
tion of the HOMO is 25% Pt + 41% X, showing a transmission
of electron density from the Pt atom to the X atom.
While the free energy for both steps of oxidative addition (1
+ BiX3→IM1 and 2 + XBiMeX→IM2) decreases in the order
X = Cl > Br > I, both reductive elimination reactions (IM1→2
+ MeBiX2 and IM2→3 + Me2BiX) are exergonic for all halides,
and the trend for free energy of these reactions decreases in the
order X = Cl < Br < I. For example when P−P = dppm, the free
Structural Investigation of Pt(IV)−Bi(III) Intermedi-
ates. Since dihalobismuth complexes of platinum(IV) are not
known so far, we discuss here the structures of these Pt(IV)−
BiX2 (X = Cl, Br, I) intermediate complexes (IM1a−f). Upon
going from X = Cl to X = I, the trend for the calculated Pt−Bi
G
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Figure 8. (a) HOMO of [PtMe2(dppm)], (b) LUMO of BiCl3, (c) interactions of Lewis acidic bismuth center of BiX3 with electron-rich Pt(II)
center of [PtMe2(dppm)] and (d) HOMO of [PtCl(BiCl2)Me2(dppm)], IM1a.
bond distance in the complexes [PtX(BiX2)Me2(dppm)]
increases as 2.693 Å (IM1a) < 2.719 Å (IM1b) < 2.752 Å
(IM1c). The well−known trans influence of the halides (bound
to M) follows the order I− > Br− > Cl− ; that is, the strength of
the Pt−Bi bond decreases on going from X = Cl to X = I in the
complexes [PtX(BiX2)Me2(dppm)]. This is in agreement with
the bond orders calculated for Pt−Bi bonds in complexes 2
(0.712, 0.677, and 0.638 for X = Cl, Br, and I, respectively).
The same behaviors have been observed for complexes
[Pt(X)2(BiMeX)Me(dppm)], IM2a−c, and dppe complexes
(IM1d−f and IM2d−f). The Pt−X optimized bond distances,
2.565, 2.721, and 2.916 Å, for X = Cl, Br, and I in IM1a, IM1b,
and IM1c, respectively, are longer than that expected for the
single Pt−X bond on the basis of covalent radii predictions
(Pt−Cl = 2.28 Å, Pt−Br = 2.43 Å, Pt−I = 2.62 Å). The
calculated bond orders of the optimized Pt−X bond distances
in these complexes are 0.83 (X = Cl; IM1a), 0.79 (X = Br;
IM1b), and 0.76 (X = I; IM1c). The optimized Bi−X bond
distances, 2.525, 2.764, and 2.915 Å in complexes IM1a, IM1b,
and IM1c, respectively, are slightly longer than that expected
for the single Bi−X bond on the basis of covalent radii
predictions (Bi−Cl = 2.51 Å, Bi−Br = 2.66 Å, Bi−I = 2.85 Å).
The X−Pt−Bi bond angles in these complexes are almost
linear. The geometry at bismuth is that of a distorted trigonal
pyramid with the X−Bi−X and Pt−Bi−X bond angles in the
range 95−106°.
CONCLUSION
■
The reaction of organoplatinum(II) complexes [PtMe2(P−P)],
P−P = dppm or dppe, with bismuth trihalides proceeds
Scheme 5
through bismuth−halide oxidative addition and bismuth−
carbon reductive elimination reactions to yield a mixture of
the platinum(II) complexes [PtMeX(P−P)], 2, and [Pt-
(X)2(P−P)], 3 (X = Cl, Br, I). These reactions, which are
the first examples of addition of bismuth trihalides to
organoplatinum(II) complexes, were monitored using 31P
NMR and UV−vis spectroscopy, and a mechanism shown in
Scheme 2 is proposed for the reaction. As such, immediately
after the addition of BiX3 to the starting complex [PtMe2(P−
P)], 1, the platinum(II) center, which is electron rich, orients
Frontier Molecular Orbitals. Qualitative representations
of the HOMO of [PtMe2(dppm)] and lowest unoccupied
molecular orbital (LUMO) of BiCl3 are presented in Figure 8,
and their composition and energy of the starting materials,
intermediates, and products are reported in Table 3. The
HOMO−LUMO gap of [PtMe2(dppm)] is equal to 4.135 eV.
In [PtMe2(dppm)], platinum is formally d8 and as expected the
HOMO is localized on the platinum atom with significant
2
its filled dz orbital to the empty σ* (Bi−X) orbital of BiX3 to
form a yellowish Pt(II)→Bi(III) adduct, A, with λ = 490 nm in
acetone solvent. The rate of this step is too fast to measure, but
the rate of conversion of the yellowish adduct A to the colorless
Pt(IV)−Bi(III) intermediate IM1 was easily monitored by the
decay of the absorption band of the Pt(II)→Bi(III) adduct (see
Figure 2). Note that the addition occurs by loss of X from A,
followed by attack by X opposite the BiX2 group. The nature of
halide has an effect on the rates of oxidative addition of BiX3 to
Pt(II) complexes; the process becomes slower as the halide
becomes larger (see Table 1). This complies with the suggested
2
contribution of the dz orbital. The value of the energy
separations between the HOMO and LUMO of [PtX(BiX2)-
Me2(dppm)], IM1, are equal to 4.095 (X = Cl), 3.518 (X = Br),
and 2.936 (X = I) eV. The main contribution to the Pt−Bi in
2
the Pt(IV) complexes, IM1, comes from the overlap of the dz
2
HOMO of the platinum complex with the LUMO of BiX2
(which is σ* orbital of Bi−X bond). So it is reasonable to view
the oxidation process formally as the removal of electrons from
the HOMO of the [PtMe2(dppm)] complex into the LUMO of
BiX3.
mechanism in a way that when the dz orbital of Pt(II) center
donates its electron density into the empty σ*(Bi−Cl) orbital
of BiCl3, which is a stronger Lewis acid as compared with BiBr3
and BiI3, the Bi−Cl becomes weaker, as compared to Bi−Br
and Bi−I, which makes transfer of Cl− to the Pt center, to form
H
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Table 4. Enthalpy Changes for Reductive Elimination of Some C−Y Bonds from Pt(IV) Complexes
reaction
C−Y
ΔH/kcal mol−1
ref.
[PtMe3I(dppe)] → [PtMe2(dppe)] + MeI
C−I
14.4
6a
6a
[PtMe3I(dppe)] → [PtMeI(dppe)] + C2H6
[PtI(BiI2)Me2(dppm)] → [PtIMe(dppm)] + BiI2Me
[PtI(BiI2)Me2(dppe)] → [PtIMe(dppe)] + BiI2Me
C−C
C−Bi
C−Bi
−25.1
−17.6
−22.2
this work
this work
IM1, easier with a greater rate (see Scheme 5). The same line
of reasoning goes with the other two halides BiBr3 and BiI3.
Consistent with this mechanism, the rate of conversion
involving the starting dppm complex [PtMe2(dppm)], 1a, in
reaction with BiBr3 [k = 1.53 ( 0.07) × 10−2 s−1] at 25 °C is
nearly 3 times greater than that involving the starting dppe
complex [PtMe2(dppe)], 1b, at the same condition [k = 0.38
( 0.03) × 10−2 s−1]. Here, according to DFT calculations, the
Pt center of adduct A containing dppm is less positive and
more electron rich, as compared to that containing dppe. This
makes the Pt−Bi bond weaker in adduct A with a dppm ligand
(with the greater rate of conversion) than that involving a dppe
ligand (with the smaller rate of conversion).
REFERENCES
■
(1) (a) Chauhan, R. S.; Prabhu, C. P.; Phadnis, P. P.; Kedarnath, G.;
Golen, J. A.; Rheingold, A. L.; Jain, V. K. J. Organomet. Chem. 2013,
723, 163. (b) Safa, M.; Puddephatt, R. J. J. Organomet. Chem. 2013,
724, 7. (c) Momeni, B. Z.; Rashidi, M.; Jafari, M. M.; Patrick, B. O.;
Abd-El-Aziz, A. S. J. Organomet. Chem. 2012, 700, 83. (d) Bette, M.;
Ruffer, T.; Bruhn, C.; Schmidt, J.; Steinborn, D. Organometallics 2012,
̈
31, 3700. (e) Calvet, T.; Crespo, M.; Font-Bardía, M.; Jansat, S.;
Martínez, M. Organometallics 2012, 31, 4367. (f) Mazzone, G.; Russo,
N.; Sicilia, E. Inorg. Chem. 2011, 50, 10091. (g) Margiotta, N.;
Ranaldo, R.; Intini, F. P.; Natile, G. Dalton Trans. 2011, 40, 12877.
(h) La Deda, M.; Crispini, A.; Aiello, I.; Ghedini, M.; Amati, M.;
Belviso, S.; Lelj, F. Dalton Trans. 2011, 40, 5259. (i) Clot, E.;
Eisenstein, O.; Jasim, N.; Macgregor, S. A.; McGrady, J. E.; Perutz, R.
N. Acc. Chem. Res. 2011, 44, 333. (j) Hamilton, M. J.; Puddephatt, R. J.
Inorg. Chim. Acta 2011, 369, 190. (k) Bonnington, K. J.; Jennings, M.
C.; Puddephatt, R. J. Organometallics 2008, 27, 6521.
(2) (a) Kim, S.; Boyle, P. D.; McCready, M. S.; Pellarin, K. R.;
Puddephatt, R. J. Chem. Commun. 2013, 49, 6421. (b) Mitzenheim, C.;
Braun, T. Angew. Chem., Int. Ed. 2013, 52, 8625. (c) Braunschweig, H.;
Damme, A. Chem. Commun. 2013, 49, 5216. (d) Maidich, L.; Zucca,
A.; Clarkson, G. J.; Rourke, J. P. Organometallics 2013, 32, 3371.
(e) Rendina, L. M.; Puddephatt, R. J. Chem. Rev. 1997, 97, 1735.
(3) (a) Momeni, B. Z.; Moradi, Z.; Rashidi, M.; Rominger, F.
Polyhedron 2009, 28, 381. (b) Levy, C. J.; Puddephatt, R. J.; Vittal, J. J.
Organometallics 1994, 13, 1559. (c) Janzen, M. C.; Jenkins, H. A.;
Rendina, L. M.; Vittal, J. J.; Puddephatt, R. J. Inorg. Chem. 1999, 38,
2123. (d) Janzen, M. C.; Jennings, M. C.; Puddephatt, R. J.
Organometallics 2001, 20, 4100. (e) Levy, C. J.; Puddephatt, R. J. J.
Am. Chem. Soc. 1997, 119, 10127. (f) Van der Ploeg, A. F. M. J.; Van
Koten, G.; Vrieze, K.; Spek, A. L. Inorg. Chem. 1982, 21, 2014.
(g) Janzen, M. C.; Jennings, M. C.; Puddephatt, R. J. Inorg. Chem.
2001, 40, 1728. (h) Levy, C. J.; Vittal, J. J.; Puddephatt, R. J.
Organometallics 1996, 15, 2108. (i) Janzen, M. C.; Jennings, M. C.;
Puddephatt, R. J. Inorg. Chem. 2003, 42, 4553.
(4) Braunschweig, H.; Brenner, P.; Cogswell, P.; Kraft, K.; Schwab, K.
Chem. Commun. 2010, 46, 7894.
(5) (a) Sanderson, J.; Bayse, C. A. Tetrahedron 2008, 64, 7685.
(b) Lange, K. C. H.; Klaptoke, T. M. The Chemistry of Organic Arsenic,
Antimony and Bismuth Compounds; J. Wiley: New York, 1994.
(c) Pyykko, P. Chem. Rev. 1988, 88, 563.
(6) (a) Goldberg, K. I.; Yan, J. Y.; Breitung, E. M. J. Am. Chem. Soc.
1995, 117, 6889. (b) Williams, B. S.; Goldberg, K. I. J. Am. Chem. Soc.
2001, 123, 2576. (c) Jensen, M. P.; Wick, D. D.; Reinartz, S.; White, P.
S.; Templeton, J. L.; Goldberg, K. I. J. Am. Chem. Soc. 2003, 125, 8614.
(d) Pawlikowski, A. V.; Getty, A. D.; Goldberg, K. I. J. Am. Chem. Soc.
2007, 129, 10382. (e) Yahav-Levi, A.; Goldberg, I.; Vigalok, A. J. Am.
Chem. Soc. 2006, 128, 8710. (f) Reinartz, S.; White, P. S.; Brookhart,
M.; Templeton, J. L. Organometallics 2000, 19, 3854. (g) Khusnutdi-
nova, J. R.; Newman, L. L.; Zavalij, P. Y.; Lam, Y. F.; Vedernikov, A. N.
J. Am. Chem. Soc. 2008, 130, 2174. (h) Crespo, M.; Anderson, C. M.;
Kfoury, N.; Font-Bardia, M.; Calvet, T. Organometallics 2012, 31,
A theoretical study is presented where the structure of all
intermediates containing neutral bismuth complexes of
platinum are investigated. It is shown that the oxidative
addition of BiX3 to the Pt(II) complex is exergonic for all
bismuth halides. The operative mechanism is suggested to
2
involve nucleophilic attack of platinum(II) center (occupied dz
orbital) on the bismuth atom of BiX3 (σ* orbital of Bi−X
bond) to give the platinum(IV) intermediates, [PtX(BiX2)-
Me2(P−P)], which undergo reductive elimination. The free
energies for oxidative addition steps involved in the reactions
decrease in the order X = Cl > Br > I and dppe > dppm, while it
increases for the reductive elimination step as I < Br < Cl. The
reductive elimination of X2Bi−CH3 from the Pt(IV)−Bi(III)
complex is thermodynamically favored by heavier halides,
largely because of a change in enthalpy. The enthalpy changes
for reductive elimination of some C−Y (Y = C, Bi, and I)
bonds from Pt(IV) complexes are shown in Table 4. The
reductive elimination of C−C and C−Bi bonds are clearly
favored over C−I, and enthalpy values decrease as C−I > C−Bi
> C−C. DFT calculations show that the Pt(IV)−Bi(III)
complexes are not stable and immediately would undergo Bi−C
reductive elimination. Note that no Pt(IV)−Bi(III) octahedral
complex has been reported so far.
AUTHOR INFORMATION
Corresponding Authors
*E-mail: nabavi@chem.susc.ac.ir (S.M.N.).
*E-mail: niroomand@iaushiraz.ac.ir (F.N.H.).
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank the Iran National Science Foundation (Grant No.
90004861), the Shiraz University Research Council, and the
Islamic Azad University, Shiraz Branch, for financial support.
We gratefully acknowledge Professor Mehdi Rashidi’s scientific
influence on our investigations, and his valuable discussion and
encouragement. We wish to thank SUSC Computer Center for
providing computer facilities, Dr. N. Mogharab and M.
Abdolahi for assisting us in our use of these facilities and for
help with our day-to-day computer related tasks at SUSC
computer Center.
́
4401. (i) Zhao, S. B.; Wang, R. Y.; Nguyen, H.; Becker, J. J.; Gagne, M.
R. Chem. Commun. 2012, 48, 443. (j) Grice, K. A.; Kaminsky, W.;
Goldberg, K. I. Inorg. Chim. Acta 2011, 369, 76.
(7) (a) Braunschweig, H.; Cogswell, P.; Schwab, K. Coord. Chem. Rev.
2011, 255, 101. (b) Sun, H. B.; Li, B.; Hua, R.; Yin, Y. Eur. J. Org.
Chem. 2006, 4231.
(8) (a) Nabavizadeh, S. M.; Habibzadeh, S.; Rashidi, M.; Puddephatt,
R. J. Organometallics 2010, 29, 6359. (b) Jamali, S.; Nabavizadeh, S.
I
dx.doi.org/10.1021/ic4018745 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
M.; Rashidi, M. Inorg. Chem. 2008, 47, 5441. (c) Aseman, M. D.;
Rashidi, M.; Nabavizadeh, S. M.; Puddephatt, R. J. Organometallics
2013, 32, 2593−2598. (d) Nabavizadeh, S. M.; Shahsavari, H. R.;
Sepehrpour, H.; Hosseini, F. N.; Jamali, S.; Rashidi, M. Dalton Trans.
2010, 39, 7800. (e) Nabavizadeh, S. M.; Amini, H.; Rashidi, M.;
Pellarin, K. R.; McCready, M. S.; Cooper, B. F. T.; Puddephatt, R. J. J.
Organomet. Chem. 2012, 713, 60. (f) Hoseini, S. J.; Nasrabadi, H.;
Nabavizadeh, S. M.; Rashidi, M.; Puddephatt, R. J. Organometallics
2012, 31, 2357. (g) Nabavizadeh, S. M.; Aseman, M. D.; Ghaffari, B.;
Rashidi, M.; Hosseini, F. N.; Azimi, G. J. Organomet. Chem. 2012, 715,
73. (h) Nabavizadeh, S. M.; Sepehrpour, H.; Shahsavari, H. R.;
Rashidi, M. New J. Chem. 2012, 36, 1739. (i) Rashidi, M.;
Nabavizadeh, S. M.; Akbari, A.; Habibzadeh, S. Organometallics
2005, 24, 2528.
(9) (a) Appleton, T. G.; Bennett, M. A.; Tomkins, I. B. J. Chem. Soc.,
Dalton Trans. 1976, 439. (b) Cooper, S. J.; Brown, M. P.; Puddephatt,
R. J. Inorg. Chem. 1981, 20, 1374.
(10) Smith, D. C., Jr.; Haar, C. M.; Stevens, E. D.; Nolan, S. P.;
Marshall, W. J.; Moloy, K. G. Organometallics 2000, 19, 1427.
(11) (a) Romeo, R.; D’Amico, G. Organometallics 2006, 25, 3435.
(b) Belluco, U.; Bertani, R.; Coppetti, S.; Michelin, R. A.; Mozzon, M.
Inorg. Chim. Acta 2003, 343, 329.
(12) Momeni, B. Z.; Kazmi, H.; Najafi, A. Helv. Chim. Acta 2011, 94,
1618.
(13) Jain, V. K.; Jain, L. Coord. Chem. Rev. 2005, 249, 3075.
(14) Benjamin, S. L.; Levason, W.; Reid, G.; Rogers, M. C.; Warr, R.
P. J. Organomet. Chem. 2012, 708, 106.
(15) Frisch, M. J.; Rega, N.; Petersson, G. A.; Trucks, G. W.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa,
J.; Ishida, M.; Burant, J. C.; Nakajima, T.; Honda, Y.; Kitao, O.;
Schlegel, H. B.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H.
P.; Cross, J. B.; Millam, J. M.; Bakken, V.; Adamo, C.; Jaramillo, J.;
Gomperts, R.; Scuseria, G. E.; Stratmann, R. E.; Yazyev, O.; Austin, A.
J.; Cammi, R.; Pomelli, C.; Iyengar, S. S.; Ochterski, J. W.; Ayala, P. Y.;
Morokuma, K.; Voth, G. A.; Salvador, P.; Robb, M. A.; Dannenberg, J.
J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Tomasi, J.; Strain,
M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J. B.; Cheeseman, J. R.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.;
Barone, V.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Montgomery Jr, J. A.; Martin,
R. L.; Fox, D. J.; Mennucci, B.; Keith, T.; Al-Laham, M. A.; Peng, C.
Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.;
Chen, W.; Vreven, T.; Wong, M. W.; Cossi, M.; Gonzalez, C.; Pople, J.
A.; Kudin, K. N.; Scalmani, G. Gaussian 03, Revision C.02; Gaussian,
Inc.: Wallingford, CT, 2004.
(16) (a) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 270.
(b) Wadt, W. R.; Hay, P. J. J. Chem. Phys. 1985, 82, 284.
(17) Chemissian V3.3; http://www.chemissian.com
(18) The change in the Pt coordination (from four coordinate to five
coordinate) has led to a minor change in phosphorus NMR. Note that
a similar minor change has been observed in a four coordinate
cycloplatinated(II) versus the five coordinated analogoue; see Frezza,
M.; Dou, Q. P.; Xiao, Y.; Samouei, H.; Rashidi, M.; Samari, F.;
Hemmateenejad, B. J. Med. Chem. 2011, 54, 6166.
(19) Zhu, J.; Lin, Z.; Marder, T. B. Inorg. Chem. 2005, 44, 9384.
(20) (a) Niroomand Hosseini, F.; Ariafard, A.; Rashidi, M.; Azimi,
G.; Nabavizadeh, S. M. J. Organomet. Chem. 2011, 696, 3351.
(b) Ariafard, A.; Ejehi, Z.; Sadrara, H.; Mehrabi, T.; Etaati, S.;
Moradzadeh, A.; Moshtaghi, M.; Nosrati, H.; Brookes, N. J.; Yates, B.
F. Organometallics 2011, 30, 422.
J
dx.doi.org/10.1021/ic4018745 | Inorg. Chem. XXXX, XXX, XXX−XXX