Oxidative addition of MeI to some cyclometalated organoplatinum(II) complexes: Kinetics and mechanism

Article abstract of DOI:10.1016/j.jorganchem.2011.10.028

New cyclometalated platinum(II) complexes [PtMe(C^N)L], 1, in which C^N = deprotonated 2-phenylpyridine (ppy), benzo[h]quinoline (bhq) or 2-(p-tolyl)pyridine (tpy) and L = PPh₃ or PMePh₂, were synthesized by the reaction of [PtMe(C^N

Full text of DOI:10.1016/j.jorganchem.2011.10.028

Journal of Organometallic Chemistry 698 (2012) 53e61
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Oxidative addition of MeI to some cyclometalated organoplatinum(II)
complexes: Kinetics and mechanism
,
a
a
a
S. Masoud Nabavizadeh a , Hashem Amini , Fatemeh Jame , Sedigheh Khosraviolya ,
*
Hamid R. Shahsavari a, Fatemeh Niroomand Hosseini b, Mehdi Rashidi a
,
*
a Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454, Iran
b Department of Chemistry, Shiraz Branch, Islamic Azad University, Shiraz 71993-37635, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
New cyclometalated platinum(II) complexes [PtMe(C^N)L], 1, in which C^N ¼ deprotonated 2-
phenylpyridine (ppy), benzo[h]quinoline (bhq) or 2-(p-tolyl)pyridine (tpy) and L ¼ PPh3 or PMePh2,
were synthesized by the reaction of [PtMe(C^N)(SMe2)] with 1 equiv of L. The reaction of complexes 1
with MeI gave the cyclometalated Pt(IV) complexes [PtMe2I(C^N)L], 3. On the basis of kinetic studies,
using Uvevisible spectroscopy, it was suggested that the latter oxidative addition reactions were pro-
ceeded by an SN2 mechanism. The rates of the reactions at different temperatures were measured and
Received 15 June 2011
Received in revised form
25 October 2011
Accepted 26 October 2011
Keywords:
consistent with the proposed mechanism, large negative
D
Sz values were found for each reaction.
Organoplatinum
Cyclomatalated
Oxidative addition
Kinetics
Besides, rate of reactions (in CHCl3) involving the PPh3 complexes [PtMe(C^N)(PPh3)], were almost 3e5
times slower than those involving the PMePh2 complexes [PtMe(C^N)(PMePh2)]. This was attributed to
the electronic and steric effects of PPh3 ligand as compared with that of PMePh2 ligand which was
further confirmed using density functional theory (DFT) calculations through finding approximate
structures for the described complexes.
Mechanism
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
few decades have clearly demonstrated that the reaction mecha-
nism involving square-planar complexes is commonly SN2 [13e16]
Oxidative addition reaction of carbonehalogen (CeX) bonds to
low valent transition metal complexes is a fundamental step in
both chemistry and applied chemistry with particular relevance to
the petrochemical industry [1e8]. The contribution of Pt(II) d8
organometallic complexes in the activation of organic substrates
and in catalytic cycles is well known, [9] examples being the Shilov,
Wacker and Heck reactions [10e12]. The majority of these
processes involve an initial CeX (X ¼ Cl, Br, I) addition and oxida-
tion of Pt(II) to Pt(IV). Furthermore, there has been a great interest
in recent decades to investigate oxidative addition reactions of
square-planar Pt(II) complexes due to the importance of these
reactions in chemistry. Mechanistic studies on oxidative addition
reactions at square-planar centres of d8 transition metals, e.g. Pt(II),
complexes have been extensively reviewed [13e22] and remain
among the most investigated dynamic processes in chemistry.
Detailed mechanistic studies and kinetic data collected in the last
and only a limited number of complexes exhibit a mechanistic
changeover under specific conditions [13,17e19]. The inner-sphere
electron-transfer/caged radical-pair mechanism becomes possible
when a formal two electron oxidation is available. This pathway, via
cage collapse, can lead to the same product obtained from SN2
pathway, but escape of the radical pair gives free radicals which can
form by-products [13].
On the other hand, cyclometalation has become one of the most
popular organometallic reactions, providing an easy entry to
organometallic compounds by forming new metalecarbon s bonds.
Cyclometalated compounds attract a great deal of interest due to
their numerous applications in several fields. Nearly all transition
metals have been successfully employed for cyclometalation. The
most widely studied examples are platinum and palladium
compounds with nitrogen donors in which CeH activation takes
place at phenyl ortho positions to produce five-membered metal-
lacycles [23e39].
The cyclometalated ligands involving 2-phenylpyridyine have
attracted attention because their Ir and Pt complexes show
good fluorescent properties [40e48]. We have recently been
studying the synthesis and reactivity of some cyclometalated
* Corresponding authors. Department of Chemistry, College of Sciences, Shiraz
University, Shiraz 71454, Iran. Tel.: þ98 711 2284822; fax: þ98 711 2286008.
E-mail
addresses:
nabavi@chem.susc.ac.ir,
nabavizadeh@yahoo.com
(S.M. Nabavizadeh), rashidi@chem.susc.ac.ir (M. Rashidi).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.10.028

54
S.M. Nabavizadeh et al. / Journal of Organometallic Chemistry 698 (2012) 53e61
Me
Pt
L
Me
C
N
Me
I
trans-cis
+ 1 eq L
C
N
Me
L
C
N
Me
L
C
N
Me
Excess MeI
Pt
Pt
I
Pt
isomerization
SMe2
A: C^N=ppy
B: C^N=bhq
C: C^N=tpy
1a: C^N=ppy ; L=PPh3
1b: C^N=ppy ; L=PMePh2
1c: C^N=bhq ; L=PPh3
1d: C^N=bhq ; L=PMePh2
1e: C^N=tpy ; L=PPh3
1f: C^N=tpy ; L=PMePh2
3a: C^N=ppy ; L=PPh3
3b: C^N=ppy ; L=PMePh2
3c: C^N=bhq ; L=PPh3
3d: C^N=bhq ; L=PMePh2
3e: C^N=tpy ; L=PPh3
3f: C^N=tpy ; L=PMePh2
2a: C^N=ppy ; L=PPh3
2b: C^N=ppy ; L=PMePh2
2c: C^N=bhq ; L=PPh3
2d: C^N=bhq ; L=PMePh2
2e: C^N=tpy ; L=PPh3
2f: C^N=tpy ; L=PMePh2
deprotonated 2-phenylpyridine (ppy)
N
-
C
=
N
deprotonated benzo[h]quinoline (bhq)
deprotonated 2-(p-tolyl)pyridine (tpy)
N
N
-
Me
-
Scheme 1. Synthesis of complexes 1 and their reactions with MeI.
organoplatinum complexes aiming to prepare more complex
structures for potential applications as molecular materials
[49e52]. Cyclometalated platinum(II) complexes have been shown
to be good candidates in oxidative addition reactions of alkyl
2. Results and discussion
2.1. Synthesis and characterization of the complexes
The synthetic procedures are summarized in Scheme 1. The
halides due to the presence of PteN and PteC
s bonds which
increase the electron density at the metal centre [53e59]. However,
surprisingly no attention has been placed on the kinetic and
mechanistic aspects of these oxidative addition reactions. In the
present work, a number of new cyclometalated platinum(II)
complexes are synthesized and characterized and their oxidative
addition reactions with MeI are investigated. It will be shown,
through a systematic temperature-dependence study, that the
reactions proceed according to an SN2 mechanism. Effect of the
ligands presented in the Pt(II) complexes on rate of oxidative
addition reactions will be discussed. DFT calculations are per-
formed in order to find approximate structures for the described
complexes.
starting complexes [PtMe(C^N)(SMe2)], A or B, in which
C^N ¼ deprotonated 2-phenylpyridine, ppy, or deprotonated benzo
[h]quinoline, bhq, respectively, were prepared as reported previ-
ously [52]. The analogous complex [PtMe(tpy)(SMe2)], C, where
tpy ¼ deprotonated 2-(p-tolyl)pyridine, was synthesized similarly
by the reaction of [PtMe2(m-SMe2)]2 with 2 equiv of 2-(p-tolyl)
pyridine. The structure of complex C was readily deduced from its
1H NMR spectrum. The protons of methyl ligand were appeared as
a singlet signal at
d
¼ 1.03 which is coupled to 195Pt to give satellites
2
with JPtH ¼ 83.4 Hz. A singlet signal at
d
¼ 2.35 with platinum
satellites with 3JPtH ¼ 25.0 Hz was attributed to protons of terminal
SMe2 ligand. The methyl substituent of tpy appeared at
d
¼ 2.47 as
a singlet. A doublet signal at
d
¼ 8.87 with platinum satellites with
3JPtH ¼ 13.3 Hz and 3JH5H6 ¼ 5.6 Hz was assigned to H6 proton of tpy
ligand.
Reaction of the dimethylsulfide complexes AeC with the phos-
phines L ¼ PPh3 or PMePh2 in a 1:1 molar ratio gave the corre-
sponding organoplatinum(II) complexes [PtMe(C^N)L], 1, as shown
in Scheme 1. They were isolated as stable yellowish solids which
were characterized by their 1H, 31P and 195Pt NMR spectra. Typi-
cally, in the 1H NMR spectrum of [PtMe(bhq)(PMePh2)],1d, in CDCl3
at room temperature (see Fig. 1), the methylplatinum resonance
appeared at
d
¼ 1.15 as a doublet due to coupling to phosphorus
3
(with JPH ¼ 7.7 Hz) which is further coupled to 195Pt (with
2JPtH ¼ 83.4 Hz). The protons of methyl group on PMePh2 ligand
3
were observed at
d
¼ 2.15 as a doublet signal (with JPH ¼ 8.3 Hz)
that is also coupled to Pt with JPtH ¼ 34.1 Hz. In the 31P{1H} NMR
3
spectrum of 1d, as expected, a singlet at
d
¼ 14.4 having 195Pt
1
satellites with JPtP ¼ 2105 Hz was observed and consistently
1
a doublet at
d
¼ ꢀ2582 with JPtP ¼ 2109 Hz was appeared in the
195Pt NMR spectrum of 1d.
The methylplatinum(II) complexes, 1ae1f, were reacted cleanly
with an excess of MeI in acetone at room temperature to give very
pale yellow solutions, from which air-stable solid products having
the general formula [PtMe2I(C^N)L] (C^N ¼ ppy, bhq or tpy;
L ¼ PPh3 or PMePh2) were obtained. The Pt(IV) products of each
reaction contained almost exclusively the thermodynamic 3ae3f
isomers, and only very small traces of the kinetic 2ae2f isomers
Fig. 1. 1H NMR spectrum of complex [PtMe(bhq)(PMePh2)], 1d, in the Me region.
Assignments are shown. Impurities of CDCl3 solvent are shown by *.

S.M. Nabavizadeh et al. / Journal of Organometallic Chemistry 698 (2012) 53e61
55
Table 1
were in some cases observed. This indicates that the thermody-
ꢀ
DFTcalculated bond lengths (A) of complexes 1e3 and charges on platinum centre of
complexes 1 based on the optimized structures.
namic isomers 3 are more stable than the related kinetic isomers 2,
as further confirmed by the theoretical studies (see next section),
and describes that rapid isomerization of the kinetic complexes 2 to
the thermodynamic complexes 3 has occurred.
Complexes 1
1a
1b
1c
1d
1e
1f
The synthesized Pt(IV) complexes were fully characterized using
1H and 31P{1H} NMR spectroscopy and elemental analysis. Full data
are collected in the experimental section. Typically, in the 1H NMR
spectrum of [PtMe2I(ppy)(PMePh2)], 3b, (see Fig. 2), the two
PteP
PteN
PteC(Me)
PteC(C^N)
Pt chargea ꢁ 10
2.406
2.229
2.067
2.046
0.772
2.389
2.214
2.069
2.048
0.689
2.402
2.247
2.065
2.047
0.763
2.386
2.237
2.066
2.048
0.685
2.406
2.230
2.067
2.047
0.765
2.389
2.221
2.068
2.047
0.685
3
2
doublets at
d
¼ 1.03 (with JPH ¼ 7.7 Hz and JPtH ¼ 59.1 Hz) and
3 2
Complexes 2
d
¼ 1.48 (with JPH ¼ 8.2 Hz and JPtH ¼ 70.3 Hz) were assigned to
the Me ligand trans to P and the Me ligand trans to N, respectively
2a
2b
2c
2d
2e
2f
[15]. The methyl group of PMePh2 ligand was appeared as a doublet
PteP
PteN
PteC(Me trans to N)
PteC(C^N)
PteC(Me trans to I)
PteI
2.626
2.261
2.083
2.041
2.105
2.906
2.546
2.256
2.088
2.048
2.105
2.902
2.615
2.280
2.080
2.044
2.108
2.903
2.532
2.280
2.086
2.048
2.107
2.903
2.618
2.265
2.081
2.044
2.106
2.909
2.544
2.262
2.087
2.046
2.105
2.908
2
3
at
d
¼ 1.75 with JPH ¼ 8.5 Hz and JPtH ¼ 11.6 Hz. The hydrogen
related to the CH group adjacent to ligating N atom of the C^N
ligand appeared as a doublet at
d
¼ 9.50 with JHH ¼ 5.1 Hz and
3JPtH ¼ 10.8 Hz. In the 31P{1H} NMR spectrum of the Pt(IV) complex
3b (see Fig. 2), a singlet signal at
d
¼ ꢀ25.2 was appeared with a 1JPtP
Complexes 3
value of 1052, which as expected is much lower than the corre-
sponding value of 2044 Hz found for the starting Pt(II) complex
[PtMe(ppy)(PMePh2)], 1b (see the experimental section).
3a
3b
3c
3d
3e
3f
PteP
PteN
PteC(Me trans to N)
PteC(C^N)
PteC(Me trans to P)
PteI
2.634
2.244
2.081
2.039
2.103
2.891
2.563
2.254
2.087
2.039
2.105
2.884
2.620
2.259
2.083
2.042
2.105
2.882
2.572
2.267
2.080
2.046
2.107
2.863
2.634
2.244
2.102
2.040
2.102
2.890
2.567
2.253
2.086
2.040
2.104
2.884
2.2. DFT-computed geometries for complexes 1e3
The possible geometries for complexes 1e3 were calculated
theoretically [60e66]. The calculated bond distances and bond
angles from DFT-optimized structures at B3LYP level for complexes
1e3 are included in Tables 1 and 1S, respectively. The DFT-
optimized structures for these complexes are shown in Fig. 3 and
Fig. 1S (see Supporting Information).
a
Pt charge applies to the natural populations analysis (NPA) charge of platinum
atoms in complexes 1 at B3LYP level of theory.
complexes 1e3 having PPh3 ligand are longer than those with
PMePh2 ligand. This is probably due to the stronger donor ability of
the PMePh2 group as compared with that of the PPh3 group. Also
from Table 1, it can be deduced that the differences between bond
lengths of Pt(II)ePMePh2 and Pt(II)ePPh3 (0.016e0.017 A) are
usually less than those between Pt(IV)ePMePh2 and Pt(IV)ePPh3
(0.048e0.083 A). This can be attributed to the absence or lowering
of p-acceptance through the P ligating atom of phosphine ligand in
Pt(IV) complexes. It is also observed that the calculated PteI and
PteP bonds for complexes 3 are, respectively, shorter and longer
than those for complexes 2, which can be attributed to a greater
trans influence of the Me group as compared with metallated C
As can be seen from Table 1, for complex 1d, the PteCH3 bond
ꢀ
ꢀ
length (2.066 A) is within the expected range for a Pt(II)eMe
moiety [67]. Bond lengths of the C^N ligand with Pt, i.e. PteC trans
ꢀ
ꢀ
ꢀ
to the phosphorus and PteN trans to Me, are 2.048 A and 2.237 A,
respectively. Also, as expected, the bond lengths of platinum(II)
complexes 1 are shorter than those of the corresponding plati-
num(IV) products 2 and 3. For example the PteP bond in 1d is
ꢀ
ꢀ
shorter (2.386 A) than those in 2d and 3d (2.532 and 2.572 A,
respectively), complying with the larger 1JPtP value for the complex
1d as compared with that of the complex 3d. Also, the PteP bond
1
atom of C^N ligands. This is in agreement with the JPtP values
found for these complexes in the related 31P NMR spectra (for
example 1226 and 1052 Hz for complexes 2f and 3f, respectively).
The PteP bond lengths for Pt(IV) complexes 3 with PPh3 ligand are
longer than those with PMePh2 ligand complying with the smaller
1JPtP values in the PPh3 complexes (3a, 3c and 3d) as compared with
those in the PMePh2 complexes (3b, 3d and 3f), see Fig. 4b.
However, in the case of Pt(II) complexes 1, the trend is reversed and
lengths for complexes
1 containing PPh3 follow the order
1a z 1e > 1c and for complexes 1 containing PMePh2 follow the
order 1b z 1f > 1d which are in agreement with the trends found
for 1JPtP values in their 31P NMR spectra. These results suggest that
the trans influence of the metallated C atom of ppy or tpy derivative
is higher than that of the bhq analogue. The PteP bond lengths for
1
the PtePPh3 bonds with longer bond lengths have larger JPtP
values as compared with those of PtePMePh2 bonds. Indeed,
a relationship between bond lengths and coupling constants has
been queried [68e70] and in the present case it seems to hold only
for the Pt(IV) complexes 3. However, as reported by Rigamonti et al.
[71,72], bond distances reflect factors such as crystal packing,
covalent or ionic radii and steric hindrance, whereas the PteP
coupling constants are mainly receptive to the effects of other
presented ligands on the 6s orbital of Pt and, accordingly, on
bonding interactions, i.e. on the amount of P / Pt donation. Riga-
monti et al. [71,72] also reports that in the Pt(II) complexes, e.g. cis-
[PtX2(PPh3)2] and cis-[PtXY(PPh3)2], the PteP bonds become
weaker as the platinum atom becomes less positively charged. The
same trend has been observed in the present work by natural bond
orbital (NBO) [73] analysis on the optimized Pt(II) structures (see
Fig. 4a). Thus, the relationship between 1JPtP values and PteP bond
lengths in Pt(II) complexes 1 is probably due to electronic (bonding)
Fig. 2. 1H NMR spectrum (on the left, in the Me region) and 31P NMR spectrum (on the
right) of complex 3b. Assignments are shown.

56
S.M. Nabavizadeh et al. / Journal of Organometallic Chemistry 698 (2012) 53e61
Fig. 3. Optimized structures of complexes 1d, 1e, 2d, 2e, 3d and 3e. The H atoms are omitted for clarity.
factors, whereas in Pt(IV) complexes, 3, are influenced by both
steric and electronic effects, which are difficult to discriminate.
As notified in the last section, the products of oxidative addition
reactions contained almost exclusively the thermodynamic 3ae3f
isomers, and only very small traces of the kinetic 2ae2f isomers
were in some cases observed. This indicates that the thermody-
namic isomers 3 are more stable than the kinetic isomers 2 and this
is in agreement with the theoretical calculations. According to our
calculations (see Table 2), for the [PtMe2I(C^N)L] complexes the cis
addition isomers (i.e. 3) are predicted to be slightly more stable
than the trans addition isomers (i.e. 2).
evaluated by nonlinear least-squares fitting of the absorbance-time
profiles to a first-order equation.
Graphs of these first-order rate constants against the concen-
tration of MeI gave good straight-line plots passing through the
origin, showing a first-order dependence of the rate on the
concentration of MeI (Fig. 6), and the slope gave the overall second-
order rate constant. The activation parameters were also obtained
from measurement at different temperatures using Eyring equation
(see Fig. 6). The resulting data are collected in Table 3.
These reactions followed second-order kinetics, first order in
both platinum(II) and MeI reagent, with remarkable reproducibility
(ꢂ5%). These observations suggest an SN2 mechanism of oxidative
addition of methyl iodide to the cyclometalated platinum(II)
2.3. Kinetic and mechanism of the reaction of complexes 1 with MeI
complex. Also, the large negative values of D
Sz are typical of
oxidative addition by a common SN2 mechanism which involves
nucleophilic attack of the metallic centre to methyl group of MeI
(see Scheme 2). Although an inner-sphere electron-transfer/caged
radical-pair mechanism is a possibility, MeI addition is thought to
be an SN2 reaction on the basis of its clean second-order kinetics
and the failure of radical traps to inhibit it. Also no by-products
have been detected in the reactions of complexes 1 with MeI,
The oxidative addition reactions of MeI with the cyclometalated
platinum complexes 1ae1f in chloroform were studied using
UVevisible spectroscopy. In each case, excess MeI was used and the
disappearance of the MLCT band for the cyclometalated Pt(II)
complexes (see Table 3 for lmax) in CHCl3 were used to monitor the
reaction (Fig. 5). The pseudo-first-order rate constants (kobs) were

S.M. Nabavizadeh et al. / Journal of Organometallic Chemistry 698 (2012) 53e61
57
the operation of the SN2 mechanism in the oxidative addition of
alky halides to some organoplatinum(II) complexes [20e22]. So it is
well established that these reactions proceed by an SN2
mechanism.
2180
2160
2140
2120
2100
2080
2060
2040
a
1c
C^N = bhq
The electronic spectra of solutions of [PtMe(bhq)(PMePh2)], 1d,
and [PtMe(tpy)PPh3], 1e, during the reaction with MeI are shown in
Fig. 5. The repetitive scan spectra in each case indicate that the first
spectrum does not go through the isosbestic point, suggesting an
initial step that should be a very fast equilibrium lying far to the left
(because of the linearity of kobs-[MeI] plot). Referring to Fig. 5, one
may conclude that any intermediate formed by the initial attack of
MeI on Pt(II) complex (see Scheme 2) should have no significant
absorption in the spectral range studied, or that its concentration
may never be enough to significantly contribute to the spectrum.
As shown in Table 3, in reactions of the cyclometalated Pt(II)
complexes with MeI at different temperatures, the complexes
containing PMePh2 ligand reacted more than 3e5 times faster than
the corresponding PPh3 analogues. For example, MeI at 25 ꢃC
Pt-PPh3
1e 1a
1d
C^N = tpy
C^N = ppy
Pt-PMePh2
1f
1b
0.068 0.07 0.072 0.074 0.076 0.078
Charge on Pt atom in complexes 1
reacted nearly 3.5 times faster with 1f (k2 ¼ 4.34 ꢁ10ꢀ2 L molꢀ1 sꢀ1
)
than with 1e (k2 ¼ 1.25 ꢁ10ꢀ2 L molꢀ1 sꢀ1). The same behaviour has
been seen in the reaction of ppy or bhq analogues with MeI. It is
shown [13] that two of the factors, among others, affecting the rate
of oxidative addition reactions are electronic and steric effects.
b
1060
1040
1020
1000
980
Pt-PMePh2
PMePh2 has higher
s-donor ability and lower p-acceptance
ability than PPh3. Therefore, in the associative process suggested
for the present oxidative addition reactions of complexes 1, one
might expect that the platinum centre in the cyclometalated plat-
inum(II) complexes [PtMe(C^N)(PMePh2)] is more electron rich
than the platinum centre in cycloplatinated(II) complexes
[PtMe(C^N)(PPh3)]. This feature is theoretically studied by the
application of density functional theory (DFT) to calculate the
natural population analysis (NPA) charges on the involved
platinum centre (See Table 1). As is clear from Table 1, the positive
charge on the platinum atom in the complexes [PtMe(C^N)
(PMePh2)] is lower than that on the platinum atom in the
complexes [PtMe(C^N)(PPh3)]. This lower positive charge on the
platinum atom in the former complexes, which means higher
electron density at the platinum centre, complies with the higher
reaction rates of the PMePh2 platinum(II) complexes as compared
with those of the analogues PPh3 complexes towards their nucle-
ophilic attack on MeI operating by an SN2 mechanism. Besides, as in
the SN2 reaction the Rþ approaches the platinum centre of the
complex from a direction perpendicular to the Pt(C^N)CP square-
planar arrangement, it is reasonable to assume that steric difference
between PPh3 and PMePh2 (by comparing the Tolman cone angles
of PPh3 (145ꢃ) and PMePh2 (136ꢃ)) would be influential in the
formation of the penta-coordinated transition states and thus
significantly help in increasing the related reaction rates involving
the PMePh2 complexes as compared with those involving the PPh3
analogues. As is clear from Table 3, no considerable change in
reaction rate is observed upon changing the nature of the cyclo-
metalated ligand. Thus, the values of k2 for reactions of complexes
1a, 1c and 1e with MeI at 15 ꢃC are estimated to be very close, i.e.
0.40, 0.34 and 0.60 L molꢀ1 sꢀ1, respectively. The results are in
consistent with the calculated natural population analysis (NPA)
(see Table 1), describing that the positive charge on platinum atom
in the complexes 1a, 1c and 1e are very close being 0.772, 0.763 and
0.765, respectively.
Pt-PPh3
960
2.56 2.57 2.58 2.59 2.6 2.61 2.62 2.63 2.64
Pt-P bond length (Å) in Pt(IV) complexes, 3
1
Fig. 4. Plots showing correlations between the JPtP values and (a) Pt charges in
complexes 1 and (b) the PteP bond lengths in complexes 3.
thus further supporting the SN2 mechanism. The reactions were
also performed in acetone and benzene. The rates in acetone were
similar to those in CHCl3, but very slow in benzene, confirming
the presence of cationic intermediate throughout the course of
each reaction. The reactions of organoplatinum(II) complexes
[PtR2(NN)], in which R ¼ Me or Ar and NN is various diimine ligands
such as 2,20-bipyridine and 1,10-phenanthroline, with MeI have
been extensively investigated [13e19]. In all cases, an SN2 mecha-
nism has been suggested. A secondary deuterium KIE study
involving the reaction of MeI/CD3I or C2H5I/C2D5I with some
organoplatinum(II) complexes has also been reported to confirm
Table 2
Gas phase energy differences between geometrical isomers of [PtMe2I(C^N)L]
complexes.
Complex
C^N
D
E (kJ molꢀ1
)
As was mentioned before, the oxidative addition of MeI to
complexes 1 yielded almost quantitatively the cis addition isomers,
3, which are the stable thermodynamic products. A likely mecha-
nism for the isomerization of 2e3 and the formation of both minor
and major products is shown in Scheme 2. The oxidation of 1 occurs
in the first step to give the five-coordinate, 16-electron plati-
num(IV) intermediate complex M. The reversible trapping of M by
L
ppy
ppy
bhq
bhq
tpy
PPh3
PMePh2
PPh3
PMePh2
PPh3
PMePh2
D
D
D
D
D
D
E ¼ E3a ꢀ E2a ¼ ꢀ21.5
E ¼ E3b ꢀ E2b ¼ ꢀ15.2
E ¼ E3c ꢀ E2c ¼ ꢀ21.8
E ¼ E3d ꢀ E2d ¼ ꢀ7.0
E ¼ E3e ꢀ E2e ¼ ꢀ20.6
E ¼ E3f ꢀ E2f ¼ ꢀ17.1
tpy

58
S.M. Nabavizadeh et al. / Journal of Organometallic Chemistry 698 (2012) 53e61
Table 3
Second-order rate constantsa and activation parametersb for reaction of [PtMe(C^N)L] (C^N ¼ deprotonated 2-phenylpyridine (ppy), benzo[h]quinoline (bhq) and 2-(p-tolyl)
pyridine (tpy), L ¼ PPh3 and PMePh2) with MeI in CHCl3.
Complex
C^N
L
l
/nmc
102k2/L molꢀ1 sꢀ1 at different temperatures
10 ꢃ 15 ꢃ 20 ꢃ
D
Hz/kJ molꢀ1
D
Sz/J Kꢀ1 molꢀ1
C
C
C
25 ꢃ
C
30 ꢃ
C
1a
1b
1c
1d
1e
1f
ppy
ppy
bhq
bhq
tpy
PPh3
PMePh2
PPh3
PMePh2
PPh3
PMePh2
359
356
400
405
365
367
0.28
1.28
0.26
1.15
0.44
1.94
0.40
1.77
0.34
1.62
0.60
2.71
0.66
0.85
2.87
0.78
2.49
1.25
4.34
1.10
3.84
1.07
2.84
1.68
5.66
47.9 ꢂ 0.4
35.8 ꢂ 0.2
49.4 ꢂ 0.5
29.6 ꢂ 0.4
46.5 ꢂ 0.2
34.9 ꢂ 0.1
ꢀ124 ꢂ 2
ꢀ154 ꢂ 1
ꢀ120 ꢂ 2
ꢀ177 ꢂ 1
ꢀ125 ꢂ 1
ꢀ154 ꢂ 1
0.45
0.91
3.40
tpy
a
Estimated errors in k2 values are ꢂ5%.
b
c
Activation parameters were calculated from the temperature dependence of the second-order rate constant in the usual way using Eyring equation.
l
specifies the wavelength used for fitting data from kinetics studies.
a
b
Fig. 5. The changes in the UVevis spectrum during the reaction of (a) [PtMe(bhq)(PMePh2)], 1d, and (b) [PtMe(tpy)PPh3], 1e, with MeI in CHCl3 at T ¼ 25 ꢃC: successive spectra
recorded at intervals of 1 min.
Fig. 6. Left: Plots of first-order rate constants (kobs/sꢀ1) for the reaction of [PtMe(tpy)(PMePh2)], 1e, with MeI in CHCl3 at different temperatures versus concentration of MeI. Right:
Eyring plots for the reaction of (a) [PtMe(tpy)PPh3] þ MeI and (b) [PtMe(tpy)(PMePh2)] þ MeI in CHCl3.
I
+
+
iodide can then give the complex 2. Alternatively, M can be iso-
merised by pseudo-rotation to give N [22], which can also be
trapped by iodide to give 3. We suggest that formation of the
thermodynamic isomer 3 is favoured over the kinetic isomer 2 as in
former the more sterically demanding L ligands are situated in the
“axial” positions as compared with the latter in which they are
located in the “equatorial” position. Thus, the five-coordinate
cation M, formed by iodide dissociation from 2, isomerizes to the
more stable thermodynamic cation N and this is consistent with
our DFT calculations (see Scheme 2 and Fig. 7); for example where
L ¼ PPh3 and C^N ¼ ppy, the cation N is 6.5 kJ/mol more stable than
the cation M in acetone solvent. We therefore suggest that M and N
are potential intermediates involved in the isomerization of 2e3 in
polar acetone solvent.
C
Me
Pt
N
L
Me
I -
C
N
Me
CH3
Pt
I -
Pt
C
N
Me
L
Me
L
M
N
MeI
Me
Me
Pt
I
C
Me
C
N
Me
C
N
Me
L
Pt
L
Pt
I
N
L
3
1
2
Scheme 2. Mechanism of oxidative addition by the SN2 mechanism and isomerization
at platinum(IV) centre.

S.M. Nabavizadeh et al. / Journal of Organometallic Chemistry 698 (2012) 53e61
59
in acetone (20 mL) at room temperature. The solution immediately
turned yellow, and small bubbles formed. The solution was stirred
for 20 h and then the solvent was evaporated from the resulting
solution to give a solid that was washed with cold ether and
acetone and dried under vacuum. Yield 240 mg; 78%, mp ¼ 176 ꢃC
2
(decomp). NMR in CDCl3:
d
(1H) ¼ 1.03 [s, 3H, JPtH ¼ 83.4 Hz,
3
MePt]; 2.35 [s, 6H, JPtH ¼ 25.0 Hz, MeS]; 2.47 [s, 3H, Me group of
3
tpy]; 6.90e8.00 [aromatic protons]; 8.87 [d, 1H, JPtH6 ¼ 13.3 Hz,
3JH6H5 ¼ 5.6 Hz, H6 of tpy].
4.1.2. [PtMe(ppy)(PMePh2)], 1b
PMePh2 (22.58 mL, 0.12 mmol) was added to a solution of
[PtMe(ppy)(SMe2)], A, (50 mg, 0.12 mmol) in acetone (20 mL). The
mixture was stirred at room temperature for 1 h. After removal of
the solvent by evaporation, a residue was obtained which was
further purified by repeated washing with ether. The product, as
a yellow solid, was dried under vacuum. Yield 46 mg; 68%,
mp ¼ 180 ꢃC (decomp). Anal. Calcd. for C25H24NPPt: C, 53.2; H, 4.3;
N, 2.5; Found: C, 53.4; H, 4.4; N, 2.3. NMR data in CDCl3: d
(1H) 0.97
2
3
Fig. 7. Calculated structures and relative energies of starting materials (1a þ MeI),
potential intermediates (M and N) and products of oxidative addition (2a and 3a) in
acetone solvent. The H atoms are omitted for more clarity.
[d, 3H, JPtH ¼ 82.9 Hz, JPH ¼ 7.5 Hz, Me ligand]; 2.13 [d,
3JPtH ¼ 31.6 Hz, JPH ¼ 8.1 Hz, Me group of the PMePh2 ligand];
2
3
4
aromatic protons: 6.56 [m, 1H, JPtH ¼ 12.9 Hz, JPH ¼ 1.5 Hz, CH
group adjacent to coordinated C atom]; 7.21e7.83 [overlapping
3
multiplets]; 8.04 [m, 1H, JPtH ¼ 11.6 Hz CH group adjacent to
3. Conclusions
coordinated N atom];
d
(
31P) 14.9 [s, 1JPtP ¼ 2044 Hz, 1P of PMePh2];
d
(
195Pt) ꢀ2552 [d, 1JPtP ¼ 2040 Hz, 1Pt].
New cyclometalated platinum(II) complexes [PtMe(C^N)L], 1,
(C^N ¼ deprotonated 2-phenylpyridine (ppy), benzo[h]quinoline
(bhq) or 2-(p-tolyl)pyridine (tpy) and L ¼ PPh3 or PMePh2) are
synthesized by the reaction of [PtMe(C^N)(SMe2)] with 1 equiv of L.
The reactions of MeI with complexes 1 to form [PtMe2I(C^N)L]
follow good second-order kinetics, first order with respect to both
The following complexes were made similarly by using the
appropriate starting complex B or C and PPh3 or PMePh2:
4.1.3. [PtMe(bhq)(PPh3)], 1c
Yield 77%, mp ¼ 180 ꢃC (decomp). Anal. Calcd. for C32H26NPPt: C,
59.0; H, 4.0; N, 2.1; Found: C, 58.5; H, 4.3; N, 2.1. NMR in CDCl3:
reactants. The entropy of activation, D
Sz, has a large negative value
2
3
d
(1H) ¼ 0.98 [d, 3H, JPtH ¼ 83.5 Hz, JPH ¼ 7.9 Hz, Me ligand];
in each reaction consistent with an SN2-type mechanism. The
operative mechanism involves nucleophilic attack of platinum(II)
on the carbon atom of MeI to give the transient cationic plati-
num(IV) intermediate, [PtMe2(C^N)L]þIꢁ, which rapidly rearranges
to [PtMe2I(C^N)L]. It is interesting to note that the observed rate
constants for the reaction of PPh3 complexes [PtMe(C^N)(PPh3)]
with MeI are lower than those for PMePh2 complexes
[PtMe(C^N)(PMePh2)]. This is attributed to electronic and steric
effects of the related phosphine groups as supported by DFT
calculations.
aromatic protons: 6.90 [m, 1H, CH group adjacent to coordinated C
atom]; 7.05e8.18 [overlapping multiplets]; 8.23 [m, 1H, CH group
adjacent to coordinated N atom];
of PPh3].
d
(
31P) 32.7 [s, 1JPtP ¼ 2164 Hz, 1P
4.1.4. [PtMe(bhq)(PMePh2)], 1d
Yield 90%, mp ¼ 164 ꢃC (decomp). Anal. Calcd. for C27H24NPPt: C,
55.1; H, 4.1; N, 2.4; Found: C, 54.7; H, 4.2; N, 2.2. NMR in CDCl3:
2
3
d
(1H) ¼ 1.15 [d, 3H, JPtH ¼ 83.4 Hz, JPH ¼ 7.7 Hz, Me ligand]; 2.15
3
2
[d, JPtH ¼ 34.1 Hz, JPH ¼ 8.3 Hz, Me group of the PMePh2 ligand];
aromatic protons: 6.89 [m, 1H, CH group adjacent to coordinated C
atom]; 7.42e7.81 [overlapping multiplets]; 8.22 [m, 1H, CH group
4. Experimental section
adjacent to coordinated N atom];
of PMePh2];
d
(
31P) 14.4 [s, 1JPtP ¼ 2105 Hz, 1P
4.1. General remarks and synthesis
d
(
195Pt) ꢀ2582 [d, 1JPtP ¼ 2109 Hz, 1Pt].
The 1H NMR spectra were recorded on a Bruker Avance DPX
250 MHz spectrometer. The 31P and 195Pt NMR spectra were
recorded on a Bruker Avance DRX 500 MHz. References were TMS
4.1.5. [PtMe(tpy)(PPh3)], 1e
Yield 89%, mp ¼ 186 ꢃC (decomp). Anal. Calcd. for C31H28NPPt: C,
58.1; H, 4.4; N, 2.2; Found: C, 58.0; H, 4.3; N, 2.5. NMR in CDCl3:
(1H), H3PO4
(
31P), and aqueous K2PtCl4
(
195Pt). CDCl3 was used as
d
(1H) ¼ 0.69 [d, 3H, 2JPtH ¼ 83.3 Hz, 3JPH ¼ 7.9 Hz, MePt]; 2.30 [s, 3H,
solvent. All the chemical shifts and coupling constants are in ppm
and Hz, respectively. Kinetic studies were carried out by using
a PerkineElmer Lambda 25 spectrophotometer with temperature
control using an EYELA NCB-3100 constant-temperature bath. The
microanalyses were performed using a Thermofinnigan Eager 300
Me of tpy]; aromatic protons: 6.37 [d, 1H, 3JPtH ¼ 13.2 Hz, CH group
adjacent to coordinated C atom]; 6.91e7.70 [overlapping multi-
plets];
d
(
31P) 33.1 [s, 1JPtP ¼ 2103 Hz, 1P of PPh3].
4.1.6. [PtMe(tpy)(PMePh2)], 1f
CHNeO elemental analyzer. The complexes [PtMe2(m-SMe2)]2, [59]
Yield 67%, mp ¼ 165 ꢃC (decomp). Anal. Calcd. for C26H26NPPt: C,
53.9; H, 4.5; N, 2.4; Found: C, 53.7; H, 4.1; N, 2.7. NMR in CDCl3:
[PtMe(ppy)(SMe2)], A, or [PtMe(bhq)(SMe2)], B, [52] and [PtMe(p-
py)(PPh3)], 1a, or [PtMe2I(ppy)(PPh3)], 2a, [49] were prepared as
described previously.
2
3
d
(1H) ¼ 0.90 [d, 3H, JPtH ¼ 83.3 Hz, JPH ¼ 8.2 Hz, Me ligand]; 2.08
3
2
[d, JPtH ¼ 31.5 Hz, JPH ¼ 11.2 Hz, Me group of the PMePh2 ligand];
2.38 [s, 3H, Me of tpy]; aromatic protons: 6.44 [m, 1H,
4.1.1. [PtMe(tpy)(SMe2)], C
3JPtH ¼ 12.8 Hz, CH group adjacent to coordinated
C atom];
Pure 2-(p-tolyl)pyridine (120
mL, 0.7 mmol) was added dropwise
6.74e7.76 [overlapping multiplets];
d
(
31P) 14.8 [s, 1JPtP ¼ 2042 Hz,
via syringe to a solution of [PtMe2(m-SMe2)]2 (200 mg, 0.35 mmol)
1P of PMePh2].

60
S.M. Nabavizadeh et al. / Journal of Organometallic Chemistry 698 (2012) 53e61
4.1.7. [PtMe2I(ppy)(PMePh2)], 3b
atom];
isomer 2f was observed;
PMePh2].
d
(
31P) ꢀ24.8 [s, 1JPtP ¼ 1052 Hz, 1P of PMePh2]. A trace of the
1
An excess of MeI (100
mL) was added to a solution of complex
d
(
31P) ꢀ21.5 [s, JPtP ¼ 1226 Hz, 1P of
[PtMe(ppy)(PMePh2)], 1b, (50 mg, 0.09 mmol) in 20 mL of acetone
at room temperature. The mixture was allowed to stand at this
condition for 2 h, and then the solvent was removed under reduced
pressure. The residue was washed twice with ether, and the
product was dried under vacuum. Yield: 54 mg; 86%, mp ¼ 185 ꢃC
(decomp). Anal. Calcd. for C26H27INPPt: C, 44.2; H, 3.9; N, 2.0;
4.2. Kinetic study
Typically, a solution of complex 1c in CHCl3 (3 mL, 1.0 ꢁ 10ꢀ4 M)
in a cuvette was thermostated at 25 ꢃC and a known excess of MeI
was added using a microsyringe. After rapid stirring, the absor-
Found: C, 44.5; H, 3.8; N, 1.9. NMR data in CDCl3: d
(1H) 1.03 [d, 3H,
3
2JPtH ¼ 59.1 Hz, JPH ¼ 7.7 Hz, Me ligand trans to P]; 1.48 [d, 3H,
bance at
l
¼ 400 nm was collected with time. The absorbance-time
3
2JPtH ¼ 70.3 Hz, JPH ¼ 8.2 Hz, Me ligand trans to N]; 1.75 [d,
curves were analyzed by pseudo-first-order method. The same
method was used at other temperatures (10, 15, 20, and 30 ꢃC).
Similar methods were used to study the other reactions at the
corresponding lmax and the data are collected in Table 3.
2
3JPtH ¼ 11.6 Hz, JPH ¼ 8.5 Hz, Me group of the PMePh2 ligand];
aromatic protons: 6.85e7.87 [overlapping multiplets]; 9.50 [d, 1H,
3
JHH ¼ 5.1 Hz, JPtH ¼ 10.8 Hz, CH group adjacent to coordinated N
atom];
d
(
31P) ꢀ25.2 [s, 1JPtP ¼ 1052 Hz, 1P of PMePh2].
The following complexes were made similarly by using the
4.3. Computational details
appropriate starting complex 1ce1f and MeI.
Density functional calculations were performed with the
program suite Gaussian03 [60] using the B3LYP level of theory
[61e63]. The LANL2DZ basis set [64e66] was chosen to describe Pt
and I. The 6e31G(d) basis set was used for other atoms. The
geometries of complexes were fully optimized by employing the
density functional theory without imposing any symmetry
constraints. To evaluate and ensure the optimized structures of the
molecules, frequency calculations were carried out using analytical
second derivatives. In all cases only real frequencies were obtained
for the optimized structures. The solvation energies were calcu-
lated by CPCM model using a high-polarity solvent, acetone.
4.1.8. [PtMe2I(bhq)(PPh3)], 3c
Yield 71%, mp ¼ 170 ꢃC (decomp). Anal. Calcd. for C33H29INPPt:
C, 50.0; H, 3.7; N, 1.8; Found: C, 49.6; H, 3.8; N, 1.8. NMR in CDCl3:
d
(1H) ¼ 1.23 [d, 3H, 2JPtH ¼ 60.3 Hz, 3JPH ¼ 7.5 Hz, Me ligand trans to
2
3
P]; 1.83 [d, 3H, JPtH ¼ 71.2 Hz, JPH ¼ 7.6 Hz, Me ligand trans to N];
aromatic protons: 6.89e8.15 [overlapping multiplets]; 9.90 [m, 1H,
CH group adjacent to coordinated N atom];
d
(
31P) ꢀ9.0 [s,
1JPtP ¼ 970 Hz, 1P of PPh3]. A trace of the isomer 2c was observed;
d
(
31P) ꢀ3.1 [s, 1JPtP ¼ 1012 Hz, 1P of PPh3].
4.1.9. [PtMe2I(bhq)(PMePh2)], 3d
Yield 55%, mp ¼ 156 ꢃC (decomp). Anal. Calcd. for C28H27INPPt:
C, 46.0; H, 3.7; N, 1.9; Found: C, 46.4; H, 3.9; N, 2.0. NMR in CDCl3:
Acknowledgements
d
(1H) ¼ 1.16 [d, 3H, 2JPtH ¼ 60.0 Hz, 3JPH ¼ 7.5 Hz, Me ligand trans to
We thank the Shiraz University Research Council for financial
support, Mr. Sajedian for technical assistance and Prof. J. H. Espenson,
Dr. A. Ariafard and Dr. G. Azimi for helpful suggestions.
3
2
P]; 1.67 [d, JPtH ¼ 12.0 Hz, JPH ¼ 8.5 Hz, Me group of the PMePh2
ligand]; 1.71 [d, 3H, 2JPtH ¼ 70.9 Hz, 3JPH ¼ 8.1 Hz, Me ligand trans to
P]; aromatic protons: 6.81e8.18 [overlapping multiplets]; 9.74 [m,
1H, CH group adjacent to coordinated N atom];
d
(
31P) ꢀ24.8 [s,
Appendix. Supporting information
1JPtP ¼ 1055 Hz, 1P of PMePh2].
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2011.10.028.
4.1.10. [PtMe2I(tpy)(PPh3)], 3e
Yield 68%, mp ¼ 174 ꢃC (decomp). Anal. Calcd. for C32H31INPPt:
C, 49.1; H, 4.0; N, 1.8; Found: C, 49.2; H, 3.8; N, 2.0. NMR in CDCl3:
References
2
3
d
(1H) 1.21 [d, 3H, JPtH ¼ 60.8, JPH ¼ 7.5 Hz, Me ligand trans to P];
1.63 [d, 3H, 2JPtH ¼ 70.9 Hz, 3JPH ¼ 7.7 Hz, Me ligand trans to N]; 2.14
[s, 3H, Me of tpy]; aromatic protons: 6.50e9.25 [overlapping
multiplets]; 9.70 [m, 3JPtH z 11 Hz, CH group adjacent to coordi-
[1] B. Lippert, Cisplatin: Chemistry and Biochemistry of a Leading Anticancer
Drug. Wiley-VCH, Weinheim, 1999.
[2] P.J. Stang, M.D. Schiavelli, H.K. Chenault, J.L. Breidegam, Organometallics 3
(1984) 1133e1134.
[3] T.R. Griffin, D.B. Cook, A. Haynes, J.M. Pearson, D. Monti, G.E. Morris, J. Am.
Chem. Soc. 118 (1996) 3029e3030.
[4] J.P. Collman, L.S. Hegedus, J.R. Norton, R.G. Fink, Principles and Application of
Organotransition Metal Chemistry. University Science Books, Mill Valley, CA,
1987.
[5] R.H. Crabtree, Organometallic Chemistry of the Transition Metals, third ed.
John Wiley & Sons, New York, 2001.
[6] J.D. Atwood, Inorganic and Organometallic Reaction Mechanism, second ed.
Wiley-VCH, New York, 1997.
[7] C.S.A. Fraser, D.J. Eisler, M.C. Jennings, R.J. Puddephatt, Chem. Commun. (2002)
1224e1225.
[8] F. Barrios-Landeros, J.F. Hartwig, J. Am. Chem. Soc. 127 (2005) 6944e6945.
[9] Ch. Elschenbroich, A. Salzer, Organometallics: A Concise Introduction. VCH,
Weinheim, 1999.
nated N atom];
d
(
31P) ꢀ8.70 [s, 1JPtP ¼ 962 Hz, 1P of PPh3]. 1H NMR
2
3
data in dmso-d6: 1.08 [d, 3H, JPtH ¼ 60.7, JPH ¼ 7.5 Hz, Me ligand
trans to P], 1.48 [d, 3H, 2JPtH ¼ 70.7 Hz, 3JPH ¼ 7.5 Hz, Me ligand trans
to N], 2.05 [s, 3H, Me of tpy]; aromatic protons: 6.21e7.99 [over-
lapping multiplets], 9.52 [m, 3JPtH z 11 Hz, JH6H5 ¼ 5.9 Hz, CH
3
group adjacent to coordinated N atom]. 1H NMR data in C6D6: 1.73
2
3
[d, 3H, JPtH ¼ 61.0, JPH ¼ 7.6 Hz, Me ligand trans to P], 2.02 [d, 3H,
2JPtH ¼ 70.9 Hz, 3JPH ¼ 7.6 Hz, Me ligand trans to N], 1.87 [s, 3H, Me of
tpy]; aromatic protons: 6.21e7.60 [overlapping multiplets], 9.91 [m,
3JPtH z 11 Hz, JH6H5 ¼ 5.7 Hz, CH group adjacent to coordinated N
3
atom].
[10] J.F. Hartwig, Nature 455 (2008) 314e322.
[11] J.A. Labinger, J.E. Bercaw, Nature 417 (2002) 507e514.
[12] A.E. Shilov, G.B. Shul’pin, Chem. Rev. 97 (1997) 2879e2932.
[13] L.M. Rendina, R.J. Puddephatt, Chem. Rev. 97 (1997) 1735e1754.
[14] S.M. Nabavizadeh, S.J. Hoseini, B.Z. Momeni, N. Shahabadi, M. Rashidi,
A.H. Pakiari, K. Eskandari, Dalton Trans. (2008) 2414e2421.
[15] S.M. Nabavizadeh, E.S. Tabei, F. Niroomand Hosseini, N. Keshavarz, S. Jamali,
M. Rashidi, New J. Chem. 34 (2010) 495e499.
[16] S.M. Nabavizadeh, H.R. Shahsavari, H. Sepehrpour, F. Niroomand Hosseini,
S. Jamali, M. Rashidi, Dalton Trans. 39 (2010) 7800e7805.
[17] M. Rashidi, S.M. Nabavizadeh, R. Hakimelahi, S. Jamali, J. Chem. Soc., Dalton
Trans. (2001) 3430e3434.
4.1.11. [PtMe2I(tpy)(PMePh2)], 3f
Yield 67%, mp 150 ꢃC (decomp). Anal. Calcd. for C27H29NIPPt: C,
45.0; H, 4.1; N, 1.9; Found: C, 44.8; H, 3.7; N, 2.2. NMR in CDCl3:
2
3
d
(1H) 1.09 [d, 3H, JPtH ¼ 58.8 Hz, JPH ¼ 7.8 Hz, Me ligand trans to
P]; 1.51 [d, 3H, 2JPtH ¼ 69.9 Hz, JPH ¼ 8.3 Hz, Me ligand trans to N];
3
3
2
1.89 [d, JPtH ¼ 11.0 Hz, JPH ¼ 8.7 Hz, Me group of the PMePh2
ligand]; aromatic protons: 6.64e8.07 [overlapping multiplets];
3
9.60 [d, 1H, JHH ¼ 4.6 Hz, CH group adjacent to coordinated N

S.M. Nabavizadeh et al. / Journal of Organometallic Chemistry 698 (2012) 53e61
61
[18] C.M. Anderson, R.J. Puddephatt, G. Ferguson, A.J. Lough, J. Chem. Soc., Chem.
Commun. (1989) 1297e1298.
[19] C.M. Anderson, M. Crespo, M.C. Jennings, A.J. Lough, G. Ferguson,
R.J. Puddephatt, Organometallics 10 (1991) 2672e2684.
[20] M. Rashidi, S.M. Nabavizadeh, A. Akbari, S. Habibzadeh, Organometallics 24
(2005) 2528e2532.
[21] S. Habibzadeh, M. Rashidi, S.M. Nabavizadeh, L. Mahmoodi, F.M. Hosseini,
R.J. Puddephatt, Organometallics 29 (2010) 82e88.
[22] S.M. Nabavizadeh, S. Habibzadeh, M. Rashidi, R.J. Puddephatt, Organometallics
29 (2010) 6359e6368.
[50] S.M. Nabavizadeh, M. Golbon Haghighi, A.R. Esmaeilbeig, F. Raoof,
Z. Mandegani, S. Jamali, M. Rashidi, R.J. Puddephatt, Organometallics 29
(2010) 4893e4899.
ꢂ
[51] S. Jamali, Z. Mazloomi, S.M. Nabavizadeh, D. Milic, R. Kia, M. Rashidi, Inorg.
Chem. 49 (2010) 2721e2726.
[52] M. Golbon Haghighi, M. Rashidi, S.M. Nabavizadeh, S. Jamali, R.J. Puddephatt,
Dalton Trans. 39 (2010) 11396e11402.
[53] C. Anderson, M. Crespo, M. Font-Bardía, X. Solans, J. Organomet. Chem. 604
(2000) 178e185.
[54] A. von Zelewsky, A.P. Suckling, H. Stoeckli-Evans, Inorg. Chem. 32 (1993)
4585e4593.
[23] M. Crespo, M. Font-Bardía, X. Solans, J. Organomet. Chem. 691 (2006)
444e454.
[24] M. Albrecht, Chem. Rev. 110 (2010) 576e623.
[55] C. Anderson, M. Crespo, M. Font-Bardía, A. Klein, X. Solans, J. Organomet.
Chem. 601 (2000) 22e33.
[25] P. Espinet, M.A. Esteruelas, L.A. Oro, J.L. Serrano, E. Sola, Coord. Chem. Rev. 117
(1992) 215e274.
[56] R. Bosque, M. Crespo, E. Evangelio, M. Font-Bardía, X. Solans, J. Organomet.
Chem. 690 (2005) 2062e2070.
[26] F. Mohr, S.H. Privér, S.K. Bhargava, M.A. Bennett, Coord. Chem. Rev. 250 (2006)
1851e1888.
[57] J. Rodríguez, J. Zafrilla, J. Albert, M. Crespo, J. Granell, T. Calvet, M. Font-Bardía,
J. Organomet. Chem. 694 (2009) 2467e2475.
[27] J.P. Djukic, J.B. Sortais, L. Barloy, M. Pfeffer, Eur. J. Inorg. Chem. (2009)
817e853.
[58] C.M. Anderson, M. Crespo, J.M. Tanski, Organometallics 29 (2010) 2676e2684.
[59] G.S. Hill, M.J. Irwin, C.J. Levy, L.M. Rendina, R.J. Puddephatt, Inorg. Synth. 32
(1998) 149e153.
[28] J. Albert, J. Granell, G. Muller, J. Organomet. Chem. 691 (2006) 2101e2106.
[29] C. Anderson, M. Crespo, J. Organomet. Chem. 689 (2004) 1496e1502.
[30] J. Brooks, Y. Babayan, S. Lamansky, P.I. Djurovich, I. Tsyba, R. Bau,
M.E. Thompson, Inorg. Chem. 41 (2002) 3055e3066 and references within.
[31] M. Crespo, C. Grande, A. Klein, J. Chem. Soc., Dalton Trans. (1999) 1629e1638
and references therein.
[32] M. Lersch, M. Tilset, Chem. Rev. 105 (2005) 2471e2526 and references
therein.
[33] T.G. Driver, M.W. Day, J.A. Labinger, J.E. Bercaw, Organometallics 24 (2005)
3644e3654.
[34] M. Crespo, J. Granell, M. Font-Bradía, X. Solans, J. Organomet. Chem. 689
(2004) 3088e3092.
[35] A. Yahav, I. Goldberg, A. Vigalok, Organometallics 24 (2005) 5654e5659.
[36] V.G. Albano, V. De Felice, M. Monari, G. Roviello, F. Ruffo, Eur. J. Inorg. Chem.
(2005) 416e422.
[60] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb,
J.R. Cheeseman, J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant,
J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi,
G. Scalmani, N. Rega, G.A. Petersson, H. Nakatsuji, M. Hada, M. Ehara,
K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, V. Bakken,
C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin,
R. Cammi, C. Pomelli, J. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth,
P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels,
M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman,
J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu,
A. Liashenko, P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-
Laham, C.Y. Peng, A. Nanayakkara, M. Challacombe, P.M.W. Gill, B.G. Johnson,
W. Chen, M.W. Wong, C. Gonzalez, J.A. Pople, GAUSSIAN 03 (Revision A.1).
Gaussian, Inc., Wallingford, CT, 2004.
[37] J. Procelewska, A. Zahl, G. Liehr, R. van Eldik, N.A. Smythe, B.S. Williams,
K.I. Goldberg, Inorg. Chem. 44 (2005) 7732e7742.
[61] C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785e788.
[62] A.D. Becke, J. Chem. Phys. 98 (1993) 5648e5652.
[38] F. Ozawa, T. Tani, H. Katayama, Organometallics 24 (2005) 2511e2515.
[39] S. Shekhar, J.F. Hartwig, J. Am. Chem. Soc. 126 (2004) 13016e13027.
[40] J.I. Kim, I.S. Shin, H. Kim, J.K. Lee, J. Am. Chem. Soc. 127 (2005) 1614e1615.
[41] A.B. Tamayo, B.D. Alleyne, P.I. Djurovich, S. Lamansky, I. Tsyba, N.N. Ho, R. Bau,
M.E. Thompson, J. Am. Chem. Soc. 125 (2003) 7377e7378.
[42] A.J. Canty, G. van Koten, Acc. Chem. Res. 28 (1995) 406e413.
[43] S.K. Yen, D.J. Young, H.V. Huynh, L.L. Koh, T.S.A. Hor, Chem. Commun. (2009)
6831e6833.
[44] A.A. Rachford, F.N. Castellano, Inorg. Chem. 48 (2009) 10865e10867.
[45] M. Ghedini, T. Pugliese, M. La Deda, N. Godbert, I. Aiello, M. Amati, S. Belviso,
L. Lelj, G. Accorsi, F. Barigelletti, Dalton Trans. (2008) 4303e4318.
[46] C.K. Koo, K.L. Wong, K.C. Lau, W.Y. Wong, M.H.W. Lam, Chem. Eur. J. 15 (2009)
7689e7697.
[63] B. Miehlich, A. Savin, H. Stoll, H. Preuss, Chem. Phys. Lett. 157 (1989) 200e206.
[64] P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 270e283.
[65] W.R. Wadt, P.J. Hay, J. Chem. Phys. 82 (1985) 284e298.
[66] L.E. Roy, P.J. Hay, R.L. Martin, J. Chem. Theory Comput. 4 (2008) 1029e1031.
[67] C.M. Haar, S.P. Nolan, W.J. Marshall, K.G. Moloy, A. Prock, W.P. Giering,
Organometallics 18 (1999) 474e479.
[68] R. Muenzenberg, P. Rademacher, R. Boese, J. Mol. Struct. 444 (1998) 77e90.
[69] G.G. Mather, A. Pidcock, G.J.N. Rapsey, J. Chem. Soc., Dalton Trans. (1973)
2095e2099.
[70] G.J.J. Steyn, A. Roodt, I. Poletaeva, Y.S. Varshavsky, J. Organomet. Chem.
536e537 (1977) 197e205.
[71] L. Rigamonti, C. Manassero, M. Rusconi, M. Manassero, A. Pasini, Dalton Trans.
[47] N. Ghavale, A. Wadawale, S. Dey, V.K. Jain, J. Organomet. Chem. 695 (2010)
1237e1245.
[48] T. Calvet, M. Crespo, M. Font-Bardía, K. Gómez, G. González, M. Martínez,
Organometallics 28 (2009) 5096e5106.
(2009) 1206e1213.
[72] L. Rigamonti, A. Forni, M. Manassero, C. Manassero, A. Pasini, Inorg. Chem. 49
(2010) 123e135.
[73] E.D. Glendening, A.E. Reed, J.E. Carpenter, F. Weinhold, NBO Version 3.1.
Gaussian, Inc., Wallingford, CT, 2004, included in Gaussian 03.
[49] S. Jamali, S.M. Nabavizadeh, M. Rashidi, Inorg. Chem. 47 (2008) 5441e5452.