Regioselective competition between the formation of seven-membered and five-membered cyclometalated platinacycles preceded by Csp2-Csp3 reductive elimination

Article abstract of DOI:10.1016/j.jorganchem.2016.06.018

A mixture of seven-membered and five-membered platinacycle complexes are eventually formed after a series of substitution, oxidative addition, and reductive elimination reactions between the platinum dimer, cis-[Pt₂Me₄(μ-SMe₂)₂] and the naphthyl-derived ?N chelate ligands, (8-XC₁₀H₆CH = N-R), X = I, Br; R = phenyl and 4-Cl-benzyl. From the tethered ligand, either an sp² C-H bond can be activated forming a five-membered ring or an sp³ C-H bond can be activated forming a seven-membered ring. All compounds have the imine included in the platinacycle. The ratio of complexes as a function of ring size varies depending on ligand architecture of the chelate ligand and the nature of other ligands in the coordination sphere. The cyclometalated platinum complexes have been characterized by NMR spectroscopy. One complex with a seven-membered ring was characterized crystallographically. Reductive elimination reactions of isolated and/or identified cyclometalated, six-membered platinum(IV) compounds [PtMe₂Br{C₁₀H₆CH = NCH₂(4-ClC₆H₄)}L] and [PtMe₂Br{C₁₀H₆CH = N(C₆H₅)}L] (L = SMe₂) to form C_sp3-C_sp2 bonds, followed by competition between C_sp2-H and C_sp3-H bond activation are also reported.

Full text of DOI:10.1016/j.jorganchem.2016.06.018

Journal of Organometallic Chemistry 819 (2016) 27e36
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Regioselective competition between the formation of seven-
membered and five-membered cyclometalated platinacycles preceded
by Csp2eCsp3 reductive elimination
,
Craig M. Anderson a *, Matthew W. Greenberg a, Lucia Spano a, Labeeby Servatius a,
Joseph M. Tanski b
a Department of Chemistry, Bard College, 30 Campus Road, Annandale-on-Hudson, NY 12504, USA
b Department of Chemistry, Vassar College, Poughkeepsie, NY 12604, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A mixture of seven-membered and five-membered platinacycle complexes are eventually formed after a
Received 22 May 2016
Received in revised form
13 June 2016
Accepted 15 June 2016
Available online 17 June 2016
series of substitution, oxidative addition, and reductive elimination reactions between the platinum
dimer, cis-[Pt2Me4(
m
-SMe2)2] and the naphthyl-derived C^N chelate ligands, (8-XC10H6CH ¼ N-R), X ¼ I,
Br; R ¼ phenyl and 4-Cl-benzyl. From the tethered ligand, either an sp2 CeH bond can be activated
forming a five-membered ring or an sp3 CeH bond can be activated forming a seven-membered ring. All
compounds have the imine included in the platinacycle. The ratio of complexes as a function of ring size
varies depending on ligand architecture of the chelate ligand and the nature of other ligands in the
coordination sphere. The cyclometalated platinum complexes have been characterized by NMR spec-
troscopy. One complex with a seven-membered ring was characterized crystallographically. Reductive
elimination reactions of isolated and/or identified cyclometalated, six-membered platinum(IV) com-
pounds [PtMe2Br{C10H6CH ¼ NCH2(4-ClC6H4)}L] and [PtMe2Br{C10H6CH ¼ N(C6H5)}L] (L ¼ SMe2) to form
Keywords:
Platinum
Oxidative addition
Reductive elimination
CeC bond formation
Thermolysis
Csp3eCsp2 bonds, followed by competition between Csp2eH and Csp3eH bond activation are also reported.
X-ray diffraction
© 2016 Elsevier B.V. All rights reserved.
1. Introduction
ubiquitous hydrocarbons as fuel stock [16e19].
As noted, reductive elimination from metal centers is one way in
Reductive Elimination (RE)/Oxidative Addition (OA) are funda-
mental reactions in organometallic chemistry in both stoichio-
metric processes and catalytic cycles and involve the addition and
elimination of a large variety of bond types [1e11]. Some contend
that reductive elimination is of paramount importance as it is often
the step where the desired product is formed in essentially an
irreversible step [12e14]. However oxidative addition should be
considered no less important as it is often a preliminary step in a set
of reactions that generates a carbon-metal bond allowing for future
functionalization [15]. CeC bond formation by the reductive elim-
ination of two ligands or fragments from a metal center, and CeH
bond activation by oxidative addition are two important examples
of reactions of these types. CeH activation being particularly
interesting as it has generated much study over the years in the
area of specialty chemicals, CeH functionalization, and the use of
which CeC bonds may be formed. Reductive elimination from
platinum centers has centered on sp2-sp2 and sp3-sp3 couplings
[20e25] as well as other types, including CeO, CeH, and CeX
[12,26e29]. Recently reported are some mixed Csp2eCsp3 bond
couplings but they are much more rare in nature [30e32]. In this
work, we have studied a system in which either Csp2eCsp3 or
Csp2eCsp2 bond forming RE from a Pt (IV) metal center may occur,
ultimately, exclusively the former is observed. This leads to the
possibility of two different intramolecular CeH activation reactions
resulting in two different cyclometalated platinum complexes.
These potential reaction pathways are illustrated in Equation (1)
and Scheme 1. The selectivity of the CeC forming step thus plays a
role in the competition of the subsequent steps involving ring-size
formation of the newly formed cyclometalated species.
Cyclometalated complexes, often formed by oxidative addition
or CeH activation, have many practical applications in materials
science and as artificial photosynthetic devices [33e36]. The ring
size of the cyclometalated platinacycle has been of interest in
* Corresponding author.
E-mail address: canderso@bard.edu (C.M. Anderson).
http://dx.doi.org/10.1016/j.jorganchem.2016.06.018
0022-328X/© 2016 Elsevier B.V. All rights reserved.

28
C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
Scheme 1. Synthesis of platinum(II) products by thermolysis of ligands with PtA.
recent years. Habitually, five-membered rings predominate over-
whelmingly over any other size [37]. Recently larger platinacycle
rings have been reported by us and others, including six-membered
rings [38e43], and some seven-membered rings [44]. It can be
speculated that different ring sizes may lead to different reactivities
due to subtle changes in ligand architecture. Consequently, the
regioselectivity of cylometalation reactions by CeH activation is an
important subject of study, since knowing the factors which in-
fluence this regioselectivity will enable different ring-sizes to be
selectively targeted. In this report we have managed to regiose-
lectively synthesize seven-membered platinacycles using
naphthyl-based ligands. The reaction of the appropriately-designed
nature of the halide coordinated to the metal center [21,46,47].
The many reactions reported in this manuscript include a vari-
ety of OA and RE steps towards the final products. These OA addi-
tion reactions include CeX and CeH addition depending on the
stage of the overall reaction. Many of the RE reactions are those
where Csp3eCsp2 bonds are formed preferentially over Csp3eCsp3
bonds, as might be expected, whereas certain CeH activation re-
actions have Csp3 bonds preferentially activated over Csp2 bonds,
contrary to the vast majority of reported cases [37]. Finally an
attempt to explore the study of the speculated reaction in-
termediates by examining isolated platinum (IV) complexes formed
in the overall proposed process was undertaken.
ligands with
a platinum-methyl precursor proceeds through
several OA and RE reactions to afford the products.
2. Results and discussion
The final ratio of products and/or isomers is determined by the
“competitive choice” (in the next to final step), of activating either
an sp2 CeH bond on the naphthyl ring or activating an sp3 CeH
bond on a methyl that became available, dangling as it were, after
the reductive elimination of the naphthyl and a methyl group (CeC
bond formation) [45]. The regioselectivity of five-membered versus
seven-membered rings in the final stages of the system are
examined and shown to be a function of the ligand structure.
Recently, five-membered ring versus seven-membered ring selec-
tivity was studied with compounds containing CeH sp2 aryl sys-
tems with the conclusion that the rate determining step depends
on the nature of the aryl-Pt bond and ring size determined by the
{C10H6(8-Br)CH]N(C6H5)}, L1, {C10H6(8-I)CH]N(C6H5)}, L2,
{C10H6(8-Br)CH]NCH2(4-ClC6H4)}, L3, {C10H6(8-I)CH]NCH2(4-
ClC6H4)}, L4 were synthesized from condensation reactions be-
tween the appropriate aldehydes and amines. All were character-
ized by 1H and 13C NMR spectroscopies. The NMR spectra clearly
indicate the formation of each of the four imine ligands. These li-
gands were designed to generate at first, a six-membered ring by
oxidative addition. Our recent publications reported that C^N^N
pincer complexes were inert to subsequent thermolysis reactions
once a new Pt (IV) cyclometalated compound was formed, but C^N
chelate-type compounds with five-membered rings were not

C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
29
[41,42]. In addition, naphthyl derived ligands, when appropriately
designed, could “force” the more rare six-membered cyclo-
metalated ring [39].
L1 and L2 differ from L3 and L4 mainly in the methylene group
that separates the imine nitrogen from the pendant phenyl group
(Chart 1). L1 and L3 have bromo at the 8-position on the naphthyl
ring whereas L2 and L4 have an iodo substituent. It is speculated
that the greater reactivity of CeX bonds over CeH bonds can be
exploited to form, initially a six-membered platinacylce by oxida-
tive addition of the CeX bond, resulting in a six-coordinate, Pt (IV)
species, which then will undergo several subsequent reactions
when subjected to thermolysis.
2.1. Reactions of ligands L1 and L2 with cis-[Pt2Me4(m-SMe2)2, PtA
The sets of products related to Pt1 and Pt2 were formed by
refluxing cis-[Pt2Me4 ( -SMe2)2], PtA and L1 and L2, respectively, in
m
anhydrous toluene for 2 h. Upon heating to reflux, the solution
changed color from light yellow to dark red within 10 min, and a
small of amount of black precipitate formed which was assumed to
be the result of decomposition to metallic platinum. These products
were determined to be platinum (II) products (Scheme 1) where
several reactions must have occurred, including oxidative addition
of an aromatic CeX from the naphthyl ring, reductive elimination to
form a CeC sp2/sp3 bond, subsequent oxidative addition of CeH
from the dangling, tethered ligand, finishing with reductive elimi-
nation of methane. The possible reaction sequence is shown in
Scheme 1. However, with the naphthyl ligands, the second oxida-
tive addition, the CeH activation step, has a “choice” to activate an
aliphatic CeH bond or an aromatic CeH bond, each rendering an
endo metalacycle (containing the imine double bond), which are
known to preferentially form [41,48], thus giving products with
either a seven or a five membered ring, respectively (Fig. 1). Spec-
troscopic data indicates that both possibilities occur for both L1 and
L2.
Fig. 1. Ligand design and possible sites for CeH metalation.
An ORTEP from an XRD study of the seven-membered ring, Pt2-
7(SP-4-4) is included in Fig. 2. The structure has one puckered
seven-membered ring (the chelate C^N ligand), with the coordi-
nation sphere being completed with the dimethyl sulfide (dms) and
an iodide. The iodide is trans to the strong sigma donor carbon
ligand. The angles and bonds lengths about the metal center are in
the accepted range for platinum (II) cyclometalated complexes [49].
Fig. 2. ORTEP of Compound Pt2-7(SP-4-4) (50% probability thermal ellipsoids).
Selected bonds lengths (Å) and angles (º): PteN: 2.025(2); PteC(1): 2.063(2); PteI:
2.718(1); PteS: 2.267(1); NeC(12): 1.292(3); C(1)eC(2): 1.491(3); NeC(13): 1.441(2);
C(1)ePteN: 82.12(8); C(1)ePteS: 89.25(7); NePteS: 166.53(5); C(1)ePteI: 162.29(5);
NePteI: 95.45(6); PteC(1)eC(2): 99.8(1); C(3)eC(2)eC(1): 118.2(2); C(11)eC(2)eC(1):
123.6(2); C(9)eC(10)eC(12): 112.2(2); C(11)eC(10)eC(12): 128.2(2).
N
N
I
Br
The pucker in the seven-membered ring is observed with the
methylene angle of PteC (1)eC (2) ¼ 99.8 (1)º, clearly indicating sp3
hybridization, but being strained to some degree. There are rela-
tively very few known seven-membered C^N platinacycles that
have been characterized crystallographically. To date we have
found 16 such published structures [44,46,47,50e57].
The proton NMR spectra of the complexes derived from ligands
L1 and L2 show the clean formation of both five-membered and
seven-membered cyclometalated complexes, with the seven-
membered complex forming as the major isomer, as determined
by NMR integration, and show a product distribution of approxi-
mately 3:1 for L1, while L2 shows a slight but appreciably different
product distribution of approximately 4:1. Both isomers have no
methyl ligands and possess characteristically large 3J (HePt)
L2
L1
Cl
Cl
N
N
Br
I
L3
L4
Chart 1. Structures of the four ligands.

30
C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
coupling constants for their SMe2 and CHN platinum satellite res-
onances consistent with Pt (II) species [3]. The imine 3J (HePt)
coupling constants for L1 were 124 Hz and 120 Hz for the seven-
membered and five-membered isomers, respectively, while the
dimethyl sulfide 3J (HePt) coupling constants are 52 Hz for the five-
membered ring and 52 Hz and 60 Hz for the two sets of SeMe
protons on the seven-membered ring, which have been rendered
inequivalent in this isomer.
addition, aryl substitutions on an ancillary ligand can support
either benzylic or aryl intermolecular CeH activation depending on
whether the aryl substitutions point in towards or away from the
coordination sphere of the metal [65]. However, a different means
by which one could alter steric hindrance in the coordination
sphere that might affect changes in the regioselectivity of the CeH
activation step would be to simply employ a ligand with increased
space between the bulky aryl substituent and the imine nitrogen.
L3 and L4 (Chart 1) differ from L1 and L2 by the CH2 “spacer” be-
tween the imine nitrogen and the aryl ring that is present in these
ligands.
Similar values for these coupling constants were observed for
the platinum products of L2. The magnitude of these coupling
constants is diagnostic of a Pt (II) oxidation state in our complexes,
and these values compare favorably to those found in recent pub-
lications [41,49,58e61]. While these spectroscopic features of the
proton NMR spectra allow us to conclude that we are observing two
different Pt (II) complexes, the identity of the five vs. seven
membered product as major or minor isomer was determined by
relative integration of the different peaks in the upfield methyl/
methylene region to the imine resonance in the NMR spectrum. The
five-membered ring contains a methyl group attached to the
naphthyl group as a result of the Csp2eCsp3 carbon-carbon bond
forming reductive elimination, while the seven-membered ring has
two methylene protons on the carbon bonded to the platinum. In
the case of Pt2-5, the five membered ring, we observe a methyl
peak and a dimethyl sulfide peak with a relative integrations of 0.75
and 1.50, respectively, with respect to the largest imine peak of the
seven-membered ring (major isomer). For the seven-membered
ring, Pt2-7, we observe two dimethyl sulfide peaks with relative
integrations of 3.00 and two inequivalent methylene doublets with
relative integrations of 1.00 (with respect to the imine) in which
both 2J (HeH) and 2J (PteH) coupling is observed, such that each of
these peaks appears as a doublet with satellites that are also dou-
blets thus indicating the inequivalency of the methylene protons
and the methyls of the dms. In order to confirm our structural as-
signments of the seven-membered ring, a 2-D COSY NMR experi-
ment was run. In particular, we wanted additional support that the
two doublets with (PteH) and (HeH) coupling could be assigned as
the CH2ePt protons. In the spectra for Pt1 and Pt2, strong cross-
peaks are observed between the two doublets that have been
assigned as the inequivalent methylene protons in our 1D spectra,
thus supporting said assignment. In addition, cross peaks are
observed between the inequivalent methylenes and methyls in the
NOESY spectrum.
The mixtures of complexes were allowed to react with PPh3 in
order to substitute it for the labile dms ligand. Usually, the reaction
is complete at room temperature within minutes. However heating
the mixtures to reflux is needed to the drive the reaction to
completion for the products Pt1 and Pt2 to give Pt1eP and Pt2eP,
respectively (Scheme 2). The 31P NMR spectra of these complexes
have 195Pt coupling constants consistent with Pt (II) species with
the stereochemistry at the platinum center having phosphine trans
to the imine [41]. For example for Pt1e7P and Pt1e5P, the 1J (PteP)
coupling constants are 4440 and 4190 Hz, respectively. Other side
and/or unidentified products are observed as decomposition when
phosphine is introduced. However, one product crystalized from
the reaction mixture and was identified by XRD to be trans-
[PtBr2(PPh3)2] [62,63]. A diagram of its structure is included in the
S.I. (Fig. S1).
When L3 or L4 was reacted with PtA, using the same procedure
used in the reaction of L1 and L2 with PtA, the result is that pri-
marily a five-membered cyclometalated platinum complex from
aromatic CeH activation is formed, reversing the regioselectivity
observed for products derived from ligands L1 and L2. Aside from
this, another distinction of the products from ligands L3 and L4, is
that in these cases, both diastereomeric forms of the major isomer
(five-membered ring) are observed in the proton NMR spectra. For
example, the reaction of L3 and PtA shows the formation of three Pt
(II) products, in a ratio of 2:1:1 (Pt3-5(SP-4-4): Pt3-5(SP-4-3): Pt3-
7(SP-4-4)), based on NMR peak integration (Scheme 1). The inte-
gration of the methyl group peak bound to the naphthalene ring, of
the five-membered ring (major product) resulting from Csp3eCsp2
reductive elimination had a relative integration of three with
respect to the largest imine, while each PteCH2 doublet peak (of
the seven-membered ring product) has a relative integration of 0.5
with respect to the largest imine peak. All imine peaks in these
compounds showed characteristic Pt (II) 3J (HePt) coupling con-
stants of around 128 Hz. Furthermore, the SMe2 resonances of the
five-membered isomers show 3J (HePt) coupling constants of
around 50 Hz. The seven membered ring showed the same two
PteCH2 doublets as observed for L1 and L2. However, the small
relative abundance of these isomers in the overall product distri-
bution, in this case, and the presence of substantial overlap of peaks
in this region did not allow for determination of all possible
coupling constants. Nevertheless, it is certainly clear from the
proton NMR spectrum of the mixture of Pt3 Pt (II) products that
this reaction yields three different Pt (II) compounds. Additionally,
the benzyl-methylene protons in the seven-membered cyclo-
metalated complexes show up as two inequivalent doublets. 2D
COSY NMR was a useful tool for assigning the resonances in the
proton spectra. As expected, for the minor seven-membered isomer
in Pt3-7(SP-4-3), both of the expected methylene cross-peaks are
seen in 2D COSY NMR. For the five-membered ring, cross peaks can
be seen between the imine proton and the benzyl methylene for
both isomers of Pt3-5. L4 also preferentially forms aromatic over
aliphatic CeH activation products, and the product distribution in
this case is even further weighted towards the five-membered
cyclometalated compound resulting from aromatic CeH activa-
tion. We observe a distribution of approximately 4:1:1 (Pt4-5(SP-4-
4):Pt4-5(SP-4-3):Pt4-7(SP-4-4)). Aside from the difference in dis-
tribution of products, the proton spectra associated with the
products from the reactions with ligand L4 are similar to those for
ꢀ
L3 vis-a-vis coupling constants and chemical shifts. Furthermore, a
2D COSY NMR successfully showed the expected methylene cross
peaks for the seven-membered ring product, which shows that
aliphatic CeH bond activation is still competitive to some degree in
this system.
2.2. Reactions of ligands L3 and L4 with PtA
The driving force behind the observed regioselectivity is
thought to be the proximity of the sterically bulky benzene ring to
the coordination sphere. Stereoelectronic factors are thought to
influence the selectivity of formation of different ring sizes and of
intramolecular sp3 versus sp2 CeH activation [42,45,64]. In
2.3. Characterization of Pt(IV) CeX oxidative addition
intermediates
In order to identify the putative Pt (IV) CeX oxidative addition
intermediates that would precede Csp2eCsp3 bond-forming

C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
31
Scheme 2. Reactions of L1, Pt1, and Pt1-6 at room temperature and with PPh3. Pt1-6 is a mixture of two diastereomers. For clarity, only one isomer is shown.
reductive elimination, the ligands were stirred with PtA overnight
for 24 h in toluene. Identifiable Pt (IV) products from all of the li-
gands L1, L2, L3, and L4 were observed. For example, stirring ligand
L1 with PtA afforded two six coordinate products as a result of CeBr
oxidative addition in an approximate 1:1 ratio, identified by the
dms and imine peaks. L2 and PtA also gave a mixture of two di-
astereomers but in an approximate 3:1 ratio.
were observed and not the products observed when PtA was
refluxed in toluene solution, with the ligands, in the one-pot syn-
thesis. However, in the case of Pt3-6dimer, phosphine could be
used to break the bromide-bridged dimer to give a monomeric Pt
(IV) species (Scheme 3) with coordinated phosphine. Finally, when
the ligands L3 and L4 were combined with PtA in toluene-d8, and
proton NMR spectra immediately taken, monomeric Pt (IV) prod-
ucts with coordinated dimethyl sulfide ligands were observed,
analogous to products observed in reactions with ligand L1. The
dms peak integrated to six protons with respect to the imine
resonance as expected. In contrast to the halide-bridged dimers,
when this solution with the observed product Pt3-6 was refluxed in
toluene-d8, the result shows the formation of the products Pt3-5
and Pt3-7 analogous to the thermolysis of Pt1-6 and reaction of L1
and PtA. In this NMR tube experiment the halide bridged dimers
were not observed within 4 h. We attribute this to the fact that the
tube, being sealed would not allow evaporation of the dms from
solution, which would drive the equilibrium to the dms-free di-
mers. Importantly, for these two ligands (L3 and L4) a Pt (IV) CeX
oxidative addition intermediate can be identified and made to
undergo the same CeH activation reactivity that is witnessed in the
one-pot synthesis where the ligand PtA are heated to reflux for an
extended period of time. We therefore conclude that CeX oxidative
addition is the initial mechanistic step following coordination of
the imine ligand that eventually leads to aromatic or aliphatic CeH
bond activation.
Mixtures of diastereomers are not always observed in similar
systems, however, they have been reported [39,66]. For example,
one of the isomers of Pt1-6 was identified with the presence of two
PteMe ligands, which are observed upfield at 0.98 and 1.38 PPM
and the 2J (HePt) coupling constants observed are reduced as ex-
pected for Pt (IV) as compared to Pt (II) [66,67]. Both PteSeMe and
PteN]CH coupling constants are also reduced compared to Pt (II)
products thus supporting the assignment. The assigned stereo-
chemistry of the six coordinate compounds has all three strong
carbon donors fac as supported by previous work [66,68].
Furthermore, when Pt1-6 was refluxed in toluene, the products,
Pt1-5/Pt1-7 were generated, supporting the notion that mecha-
nistically the Pt (IV) is indeed an intermediate in the overall reac-
tion that eventually results in the final Pt (II) complex. The product
distribution ratio in this case being essentially the same as
compared to the original thermolysis reaction. Phosphine could be
used to substitute for dms in the case of Pt1-6 to generate only one
diastereomer, Pt1e6P, from the mixture. The bulky phosphine
ligand coordinates in the axial position, trans to a methyl and thus
the bromide ligand is trans to the aryl ligand. A low quality crystal
of Pt1e6P, the bromo/PPh3 analogue, was obtained and subjected
to X-ray diffraction study, from which only connectivity could be
determined (SI, Fig. S2), which corroborates this stereochemical
assignment.
In contrast, the room temperature reaction of platinum dimer
PtA with L3 and L4 yielded a curious result; for both reactions a Pt
(IV) complex with two methyl ligands was identified, but no
dimethyl sulfide peaks were observed. All other expected peaks for
the heteroatom-assisted oxidative addition product of Pt3-6 or
Pt4-6 were accounted for, with Pt (IV) oxidation state-appropriate
coupling constants. The structures of these complexes were
assigned as platinum dimers with bridging halides (Scheme 3).
Once again, a connectivity only (due to crystal quality) XRD study
(SI, Fig. S3) was obtained supporting this assignment and corrob-
orating the NMR data. When these Pt/halide dimers were subse-
quently heated to reflux, undetermined products of decomposition
2.4. Concluding remarks
In summary, we have shown that the variation of ligand sterics
in the coordination sphere can affect the regioselectivity of intra-
molecular platinum CeH activation. We have pursued the isolation
of the Pt (IV) intermediates that we assumed must be part of this
reactivity and have demonstrated their existence and ability to
reductively eliminate towards the final CeH activation product.
3. Experimental section
3.1. General
The solvents and reagents were purchased from Sigma Aldrich
unless otherwise noted. K2PtCl4 was purchased from the Pressure
Chemical Company. NMR spectra were recorded at Bard College

32
C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
Scheme 3. Reactions of L3 at room temperature and substitution with triphenylphosphine.
using Varian MR-400 MHz spectrometer (1H, 400 MHz; 13C,
100.6 MHz; 31P-{1H}, 161.8 MHz) and referenced to SiMe4 (1H, 13C)
(400 MHz, CDCl3):
d
¼ 7.29e7.47 (m, 6H), 7.57 (t, J(HeH) ¼ 5.6 Hz,
1H) 7.88 (t, J (HeH) ¼ 6.6 Hz, 2H), 7.94 (d, J (HeH) ¼ 10.6 Hz, 1H),
and H3PO4
breviations used:
(
31P).
d
values are given in ppm and J values in Hz. Ab-
singlet; doublet; triplet;
8.08 (d, J (HeH) ¼ 7.4 Hz, 1H), 9.81 (s, 1H, CHN). 13C NMR
s
¼
d
¼
t
¼
(100.3 MHz, CDCl3):
d
¼ 118.9,121.2,126.0,126.2,126.4,129.0,129.2,
m ¼ multiplet. Electrospray mass spectra were performed at Vassar
College using an LC/MSD-TOF spectrometer. Reported yields refer
to total mass of isolated solid mixture of all isomers present.
129.2, 130.0, 131.6, 133.1, 134.7, 135.9, 151.9, 161.6 (CHN).
3.3.2. [(C10H6I)CH]N(C6H5)], L2
3.2. X-ray diffraction (XRD)
L2 was prepared similarly to L1 using 0.198 g of 8-iodo-1-
napthaldehdyde (0.697 mmol) and 0.065
(0.697 mmol). The yield was 0.185 g of resulting imine product
(0.517 mmol, 74% yield) 1H NMR (400 MHz, CDCl3):
J ¼ 7.9 Hz, 1H), 7.28 (dd, J ¼ 8.6 Hz, 4.27, 1H), 7.43e7.46 (m, 4H), 7.56
(t, J ¼ 7.2 Hz, 1H), 7.91 (dd,J ¼ 8.0, 4.30 Hz, 2H), 8.06 (d, J ¼ 7.6 Hz,
1H), 8.27 (d, J ¼ 8.0 Hz,1H),10.00 (s, 1H, CHN). 13C NMR (100.3 MHz,
CDCl3): 90.3 (CeI), 121.3, 126.1, 126.1, 127.0, 129.2, 129.8, 130.0,
132.0, 133.2, 135.2, 135.5, 141.2, 151.7, 160.4 (CHN).
g
of aniline
X-ray diffraction data were collected on a Bruker APEX 2 CCD
platform diffractometer (Mo Κ
a
(
l
¼ 0.71073 Å)) at 125 K Pt2-7(SP-
d
¼ 7.17 (t,
4-4) was crystallized using vial-in-a-vial vapor diffusion. ~3 mg of a
mixture of isomers of Pt2-5 and Pt2-7 was dissolved in 2 mL MeOH
and filtered through diatomaceous earth into a 1 dram vial. This vial
was placed into a 20 mL scintillation vial containing pentane,
capped, sealed, and left undisturbed for approximately 2 weeks. A
crystal was mounted in a nylon loop with Paratone-N cryoprotec-
tant oil. The structure was solved using direct methods and stan-
dard difference map techniques, and was refined by full-matrix
least-squares procedures on F2 with SHELXTL2014 [69]. All non-
hydrogen atoms were refined anisotropically. Hydrogen atoms on
carbon were included in calculated positions and were refined
using a riding model. See Fig. 2 and the caption for ORTEP drawing,
labels, bond lengths, and bond angles. CIF for compound Pt2-7(SP-
4-4) is included in the supporting information.
3.3.3. [(C10H6Br)CH]NCH2(C6H4Cl)], L3
L3 was prepared similarly to L1 using 0.361 g of 8-bromo-1-
napthaldehdyde (1.53 mmol) and 0.217
g of 4-chloro-1-
benzylamine (1.53 mmol). The yield was 0.376 g of resulting
imine product (1.05 mmol, 68% yield). 1H NMR (400 MHz, CDCl3):
d
¼ 4.85 (s, 2H), 7.28e7.37 (m, 5H), 7.51 (t, J ¼ 7.8 Hz, 1H), 7.82e7.91
(m, 4H), 9.68 (s, 1H, CHN). 13C NMR (100.3 MHz, CDCl3):
d
¼ 64.4
(CH2), 118.9, 124.8, 126.1, 126.3, 128.5, 128.6, 129.0, 129.5, 129.8,
131.2, 133.0, 134.7, 135.8, 137.6, 143.9, 164.1 (CHN).
3.3. Preparation of the compounds
Platinum dimer, cis-[Pt2Me4 (m-SMe2)2], PtA, was prepared as
reported elsewhere [70].
3.3.4. [(C10H6I)CH]NCH2(C6H4Cl)], L4
L4 was prepared similarly to L1 using 0.437 g (1.55 mmol) of 8-
iodo-1-napthaldeyhde and 0.219 g of 4-chloro-1-benzylamine
(1.55 mmol). The reaction mixture was filteredand the solvent
evaporated to yield an off white solid. Final yield was 0.385 g of
resulting imine product (0.94 mmol, 61.4% yield). 1HNMR
3.3.1. [(C10H6Br)CH]N(C6H5)], L1
Both 8-bromo-1-napthaldehdyde (0.508 g, 2.16 mmol) and an-
iline (0.201 g, 2.16 mmol) were dissolved in 10 mL anhydrous
methylene chloride. MgSO4 was added to the flask and the mixture
was allowed to stir at room temperature for 24 h. The solution was
then filtered and the solvent evaporated yielding an orange oil
which was washed with 10. mL anhydrous pentane. The resulting
compound crystallized into a yellow solid after one week. Final
yield was 0.442 g of imine (1.42 mmol, 65% yield). 1H NMR
(400 MHz, CDCl3):
(m, 4H), 7.49 (t, J ¼ 7.8 Hz, 1H), 7.83e7.89 (m, 3H), 8.24 (d, J ¼ 7.4 Hz,
1H), 9.90 (s, 1H, CHN). 13C NMR (100.3 MHz, CDCl3):
d
¼ 4.87 (s, 2H), 7.13, (t, J ¼ 8.6 Hz, 1H), 7.31e7.42
d
¼ 64.4 (CH2),
90.3,125.9,126.0,126.9,128.5,129.5,129.8,129.8,131.6,132.6,132.7,
134.9, 135.4, 137.5, 141.2, 163.4 (CHN).

C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
33
3.3.5. [PtMe2Br{C10H6CH ¼ N(C6H5)}SMe2], Pt1-6 (Pt1-6 (OC-6-54)
and Pt1-6 (OC-6-54))
3.3.9. [PtMe2-
[PtMe2-
-I{C10H6CH ¼ NCH2(4-ClC6H4)}]2, was obtained by
dissolving 0.037 (0.091 mmol) of L4 with 0.026 PtA
(0.0452 mmol) in 15 mL anhydrous toluene. The solution was then
allowed to stir for 24 h. The resulting solution was a cloudy orange
which showed a precipitate which was filtered with diatomaceous
earth. The solvent was then evaporated to yield a dark orange solid.
Final yield was 0.038 g (66% yield, 0.030 mmol). 1H NMR (400 MHz,
m
-I{C10H6CH ¼ NCH2(4-ClC6H4)}]2, Pt4-6dimer
m
[PtMe2Br{C10H6CH ¼ N(C6H5)}SMe2] was obtained by dissolving
0.24 g (0.077 mmol) of L1 and 0.022 g PtA (0.038 mmol) in 15 mL
anhydrous toluene. The solution was then allowed to stir for 24 h.
The resulting solution was light orange and the solvent was evap-
orated to yield an orange oil which was then washed with ice cold
diethyl ether to yield a dark orange solid. Final yield was 0.034 g
(0.057 mmol, 73%). 1H NMR (400 MHz, CDCl3): Major isomer:
g
g
CDCl3):
d
¼ 1.55, (s, 2J (HePt) ¼ 77.4, 6H, PteMe), 2.34, (s, 2J
d
¼ 0.98, (s, 2J (HePt) ¼ 70.4 Hz, 3H, PteMe), 1.38 (s, 2J
(HePt) ¼ 70.0, 6H, PteMe), 5.74, (d, J (HeH) ¼ 16.0, 2H, CH2), 6.01,
(d, J (HeH) ¼ 14.0, 2H, CH2), 7.12e8.05, (CH, aromatics), 8.41 (s, 3J
(HePt) ¼ 21.9, 2H, CHN). HR-ESI-(þ)-MS: m/z 502.0833 calcd for
(HePt) ¼ 68.0 Hz, 3H, PteMe), 1.80, (s, 3J (HePt) ¼ 14.1 Hz, 6H,
SMe2), 7.12e7.78 (m, CH, aromatics), 8.11 (d, J ¼ 8.4 Hz, CH, aro-
matic), 8.51 (s, 3J(HePt) ¼ 26.3 Hz, 1H, CHN). Minor isomer:
C
20H19ClNPt; [MꢀI,I]þ 502.0825. Anal. calcd for C40H38Cl2I2N2Pt2: C,
d
¼ 2.08, (s, 3J (HePt) ¼ 11.3 Hz, 6H, SMe2), 7.12e7.78 (m, CH, ar-
38.1; H, 3.04; N, 2.22. Found: C, 40.0; H, 3.03; N, 1.88.
omatics), 8.11 (d,
J
¼
8.4 Hz, CH, aromatic), 8.67 (s,
3J(HePt) ¼ 22.7 Hz, 1H, CHN). HR-ESI-(þ)-MS: m/z 454.1066 calcd
3.3.10. [PtMe2Br{C10H6CH ¼ NCH2(4-ClC6H4)}]PPh3], Pt3e6P
[PtMe2Br{C10H6CH ¼ NCH2(4-ClC6H4)}]PPh3], was obtained by
for
C
C
19H18NPt; [M
ꢀ
Br, dms]þ 454.1061. Anal. calcd for
21H24BrNPtS: C, 42.2; H, 4.05; N, 2.34. Found: C, 42.14; H, 3.89; N,
stirring
[PtMe2-m-Br{CH]NCH2(4-ClC6H4)}]2
(15.0
mg,
2.06.
0.0128 mmol) and triphenylphosphine (6.9 mg, 0.026 mmol) in dry
toluene for 1 h at room temperature. The solvent was then evap-
orated leaving a light brown solid. Yield: 12.2 mg (0.0137 mmol,
3.3.6. [PtMe2Br{C10H6CH ¼ N(C6H5)}PPh3], Pt1e6P
[PtMe2Br{C10H6CH ¼ N(C6H5)}PPh3] was obtained by adding
[PtMe2Br{C10H6CH ¼ N(C6H5)}SMe2] (15.4 mg, 0.0258 mmol) and
triphenylphosphine (6.7 mg, 0.023 mmol) together in toluene
(10 mL) at room temperature and stirring for 1 h. The solvent was
then evaporated to produce a brownish green powder. Yield:
55.5%). 1H NMR (400 MHz, CDCl3):
d
¼ 1.61 [d, 2J (PeH) ¼ 8.8, J
(PteH) ¼ 60.3, 3H, PteMe]; 1.62 [d, 2J (P-Hd¼) ¼ 7.5, J (PteH) ¼ 60.9,
3H, PteMe]; 4.89 [d, J (HeH) ¼ 16.1, 1H, CH2]; 5.97, J (HeH) ¼ 16.3,
1H, CH2]; {6.84e8.02, aromatics}; 7.77 [s, 3J (PteH) ¼ 25.6, 1H,
CHN]. 31P NMR (161.8 MHz, CDCl3):
d
¼ ꢀ7.6 (s, 1J (PePt) ¼ 853).
11.3 mg (0.0137 mmol, 53.1%). 1H NMR (400 MHz, CDCl3):
d
¼ 1.64
HR-ESI-(þ)-MS: m/z 764.1744 calcd for C38H34ClNPPt; [MꢀBr]þ
764.1763. Anal. calcd for C38H34BrClNPPt: C, 53.94; H, 4.05; N, 1.66.
Found: C, 54.96; H, 4.28; N, 1.33.
(d, 3H, 3J (HeP) ¼ 9.0, 2J (HePt) ¼ 66.5, PteMe); 1.69 (d, 3H, 3J
(HeP) ¼ 7.4, 2J (HePt) ¼ 62.0, PteMe); 6.40e7.96 (aromatics); 8.35
(s,1H, 3J(HePt) ¼ 25.1, CHN). 31P NMR (161.8 MHz, CDCl3):
¼ ꢀ8.16
d
(s, 1J (PePt) ¼ 841). HR-ESI-(þ)-MS: m/z 454.1066 calcd for
3.3.11. [PtBr{CH2C10H6CH ¼ NC6H5}SMe2]:[PtBr{8-
MeC10H5CH ¼ NC6H5}SMe2], Pt1-7:Pt1-5 (3:1)
C
19H18NPt; [M ꢀ Br, PPh3]þ 454.1063. Anal. calcd for C37H33BrNPPt:
C, 55.42; H, 4.17; N, 1.76. Found: C, 55.45; H, 4.27; N, 1.48.
[PtBr{CH2C10H6CH
¼
NC6H5}SMe2]:[PtBr{8-
MeC10H5CH ¼ NC6H5}SMe2] (3:1) was obtained by dissolving
0.020 g (0.066 mmol) of L1 and 0.019 g PtA (0.033 mmol) in 15 mL
anhydrous toluene. The solution was then heated to reflux for 2 h.
The resulting solution was dark red alongside whch contained
some visible black platinum precipitate, which was filtered with
diatomaceous earth. The solvent was removed under vacuum
resulting in a red powder. Final yield was 0.023 g (59% yield,
0.039 mmol). Alternatively, [PtMe2Br{C10H6CH ¼ N(C6H5)}SMe2],
Pt1-6, when heated to reflux gave a similar mixture of products. 1H
3.3.7. [PtMe2I{C10H6CH ¼ N(C6H5)}SMe2], Pt2-6 (Pt2-6 (OC-6-54)
and Pt2-6 (OC-6-54))
[PtMe2I{C10H6CH ¼ N(C6H5)}SMe2] was obtained by stirring a
solution of PtA (25.0 mg, 0.044 mmol) and L2 (31.4 mg,
0.088 mmol), in toluene, for 1 h, at room temperature. The solvent
was then evaporated to produce a yellow solid. Yield: 34.1 mg
(0.053 mmol, 60.1%). 1H NMR (400 MHz, CDCl3): Major isomer:
d
¼ 1.17 [s, 2J (PteH) ¼ 68.3, 3H, PteMe]; 1.50 [s, 2J (PteH) ¼ 69.0,
3H, PteMe]; 2.13 [s, 3J (PteH) ¼ 13.7, 6H, SMe2]; {7.14e7.82, aro-
NMR (400 MHz, CDCl3): Major Isomer:
d
¼
2.19, (s, 3J
matics}; 8.12 [d, J (HeH) ¼ 8.33, 1H, aromatic]; 8.46 [s, 3J
(HePt) ¼ 52.3 Hz, 3H, SMe2), 2.62 (s, 3J (HePt) ¼ 60.2 Hz, 3H, SMe2),
3.21, (d, 2J (HeH) ¼ 9.7 Hz, 2J (HePt) ¼ 120.9 Hz,1H, CH2), 3.50, (d, 2J
(HeH) ¼ 7.3 Hz, 2J (HePt) ¼ 77.1 Hz, CH2), 7.10e8.14 (CH, aro-
matics), 9.15 (s, 3J(HePt) ¼ 124.1 Hz, 1H, CHN); Minor Isomer: 2.75,
(s, 3H, CH3), 2.80, (s, 3J (HePt) ¼ 52.0 Hz, 6H, SMe2), 7.10e8.70 (m,
CH, aromatics), 9.27 (s, 3J(HePt) ¼ 120.2, 1H, CHN). 13C NMR
(100.3 MHz, CDCl3): (Major Isomer Only) 15.8 (PteCH2), 22.6
(SeMe), 23.5 (SeMe), 123.8, 123.9, 123.9, 124.6, 125.2, 126.9, 127.8,
127.9, 128.7, 128.9, 136.0, 138.1, 152.0, 153.1, 169.6 (CHN). (1HeH)-
2D-COSY-NMR-Cross Peaks-(3.27e3.60)-[Major Isomer Methy-
lenes] (1HeH)-2D-NOESY-NMR-Cross Peaks-(7.85e9.16)-[Major
Isomer Methylenes], (2.20e2.63)-[Major Isomer SMeeSMe]. HR-
(PteH)
¼
27.2, 1H, CHN]. Minor isomer:
d
¼
1.87 (s, 3J
(HePt) ¼ 9.5 Hz, 6H, SMe2), 7.12e7.78 (m, CH, aromatics), 8.27 (d,
J ¼ 8.0 Hz, CH, aromatic), 8.63 (s, 3J(HePt) ¼ 24.5 Hz, 1H, CHN). HR-
ESI-(þ)-MS: m/z 454.1066 calcd for C19H18NPt; [M ꢀ Br, dms]þ
454.1062. Anal. calcd for C21H24INPtS: C, 39.14; H, 3.75; N, 2.17.
Found: C, 40.37; H, 3.46; N, 2.22.
3.3.8. [PtMe2-
m
-Br{C10H6CH ¼ NCH2(4-ClC6H4)}]2, Pt3-6dimer
[PtMe2-
m
-Br{C10H6CH ¼ NCH2(4-ClC6H4)}]2 was obtained by
dissolving 0.034 g (0.095 mmol) of L3 and 0.027 g PtA (0.047 mmol)
in 15 mL anhydrous toluene. The solution was then allowed to stir
for 24 h. The resulting solution was light yellow and the solvent was
evaporated to yield a bright yellow solid. Final yield was 0.048 g
ESI-(þ)-MS: m/z 500.0943 calcd for
C
20H20NPtS; [MꢀBr]þ
500.0956. Anal. calcd for C20H20BrNPtS: C, 41.3; H, 3.47; N, 2.41.
Found: C, 40.3; H, 3.31; N, 2.15.
(87% yield, 0.041 mmol). 1H NMR (400 MHz, CDCl3):
d
¼ 1.41, (s, 2J
(HePt) ¼ 78.0 Hz, 6H, PteMe), 1.97, (s, 2J (HePt) ¼ 68.2 Hz, 6H,
PteMe), 5.48, (d, J (HeH) ¼ 14.5 Hz, 2H, CH2), 5.86, (d, J
(HeH) ¼ 15.3 Hz, 2H, CH2), 7.10e8.04, (CH, aromatics), 8.53, (s, 3J
(HePt) ¼ 19.6 Hz, 2H, CHN). HR-ESI-(þ)-MS: m/z 502.0833 calcd for
3.3.12. [PtBr{CH2C10H6CH ¼ NC6H5}PPh3]:[PtBr{8-
MeC10H5CH ¼ NC6H5}PPh3], Pt1e7P: Pt1e5P (3:1)
[PtBr{CH2C10H6CH
¼
NC6H5}PPh3]:[PtBr{8-
C
C
20H19ClNPt; [M
ꢀ
Br, Br]þ 502.0831. Anal. calcd for
MeC10H5CH ¼ NC6H5}PPh3] (3:1) was obtained by refluxing an
acetone solution of [PtBr{CH2C10H6CH ¼ NC6H5}SMe2]:[PtBr{8-
MeC10H5CH ¼ NC6H5}SMe2] (3:1) (15.0 mg, 0.0250 mmol) and
40H38Cl2Br2N2Pt2: C, 41.1; H, 3.28; N, 2.40. Found: C, 40.02; H, 3.28;
N, 1.73.

34
C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
triphenylphosphine (6.8 mg, 0.026 mmol) under nitrogen for 1 h.
The resulting solution was concentrated using rotary evaporation to
produce a copper colored solid. Unidentified decomposition prod-
ucts were also present. Refluxing a toluene solution of Pt1e6P also
resulted in a similar mixture of products. 1H NMR (400 MHz,
2D-COSY
NMR:
Cross
Peaks:
(3.18e3.09)-[Methylenes],
(5.80e7.07)-[Upfield Aromatic-Aromatic]. (1HeH)-2D-NOESY NMR
Cross Peaks: (2.79e9.54)-[methyl-imine], (3.11e3.17)-[Methy-
lenes], (3.11e5.80)-[Methylene-Upfield Aromatic], (5.80e7.07),
(5.80e7.07)-[Upfield Aromatic-Aromatic]. HR-ESI-(þ)-MS: m/z
828.0730 calcd for C36H29INPPt; [M]þ 828.0785. Anal. calcd for
CDCl3): Major Isomer:
d
¼ 2.95 [dd, J (HeH) ¼ 8.8 hz, J (HeP) ¼ 8.8
hz, 1H, PteCH2], 3.13 [d, J (HeH) ¼ 8.8 hz, 1H, PteCH2], 5.70 [d, J
(HeH) ¼ 7.4 hz, 1H, Upfield Aromatic], 6.97e8.20, [aromatics], 9.20
[d, 3J (PteH) ¼ 85.3 hz, 4J (PeH) ¼ 10.3, 1H, CHN]. Minor Isomer:
C36H29INPPt: C, 52.18; H, 3.53; N, 1.69. Found: C, 51.91; H, 3.78; N,
1.55.
d
¼ 2.81 [s, 3H, CH3], 9.50 [d, 3J (PteH) ¼ 88.6, 4J (PeH) ¼ 9.0 hz, 1H,
3.3.15. Pt3-5(SP-4-4): Pt3-5(SP-4-3): Pt3-7(SP-4-4); [PtBr{8-
MeC10H5CH ¼ NCH2(4ClC6H4)}SMe2] and [PtBr
CHN]. 31P NMR (161.8 MHz, CDCl3):
d
¼ 13.8, [s, 1J (PePt) ¼ 4438 hz,
Major Isomer], 23.4, [s, 1J (PePt) ¼ 4194, Minor Isomer]. (1HeH)-
2D-COSY NMR Cross Peaks-(3.13e2.98)-[Major Isomer Methy-
lenes], (5.69e6.99)-[Upfield Aromatic-Aromatic]. HR-ESI-(þ)-MS:
m/z 779.0848 calcd for C36H29BrNPPt; [M]þ 779.0822. Anal. calcd
for C36H29BrNPPt: C, 55.3; H, 3.74; N,1.79. Found: C, 54.0; H, 3.98; N,
1.60.
{CH2C10H6CH ¼ NCH2(4-ClC6H4)}SMe2] (2:1:1)
Pt3-5(SP-4-4): Pt3-5(SP-4-3): Pt3-7(SP-4-4) (2:1:1) was ob-
tained by dissolving 0.022 g (0.063 mmol) of L3 with 0.018 g PtA
(0.032 mmol) in 15 mL anhydrous toluene. The solution was then
heated to reflux for 2 h. The resulting solution was brownish with
some black precipitate. The solution was filtered with diatoma-
ceous earth and the solvent evaporated to yield a dark brown solid.
Yield was 0.018 g (42%, 0.027 mmol). When an NMR tube con-
taining a toluene-d8 solution of Pt3-6 was heated at 100 ꢁC for 2 h a
similar mixture of products was observed. 1H NMR (400 MHz,
3.3.13. [PtI{CH2C10H6CH ¼ NC6H5}SMe2]:[PtI{8-
MeC10H5CH ¼ NC6H5}SMe2], Pt2-7:Pt2-5 (4:1)
[PtI{CH2C10H6CH ¼ NC6H5}SMe2]:[PtI{8-MeC10H5CH ¼ NC6H5}
SMe2], (4:1) was obtained by dissolving 0.020 g (0.056 mmol) of L2
and 0.016 g PtA (0.028 mmol) in 15 mL anhydrous toluene. The
solution was then heated to reflux for 2 h. The resulting solution
was black, which was filtered with diatomaceous earth to yield a
dark brown solution. The solvent was evaporated to yield a dark
brown solid. Final yield was 0.013 g (38%, 0.021 mmol). 1HNMR
(400 MHz, CDCl3): Refluxing a toluene solution of Pt2-6 also
CDCl3): Five-Membered Ring, Major Isomer:
d
¼ 2.46, (s, 3H, Me),
2.79, (s, 3J (HePt)
¼
50.0 Hz, 6H, SMe2), 5.46, (s, 3J
(HePt) ¼ 23.6 Hz, 2H, CH2), 7.10e8.19, (CH, aromatics), 9.00 (s, 3J
(HePt) ¼ 128.2, 1H, CHN). Five-Membered Ring, Minor Isomer:
d
¼ 2.35, (s, 3H, Me), 2.80, (s, 3J (HePt) ¼ 52.0 Hz, 6H, SMe2), 5.45,
(s, 2H, CH2), 7.10e8.19, (CH, aromatics), 8.55 (s, 3J
(HePt) ¼ 128.4 Hz,1H, CHN). Seven-Membered Ring, Major Isomer:
resulted in a similar mixture of products. Major Isomer:
d
¼ 2.23, (s,
d
¼ 2.22, (s, 3H, SMe2), 2.56, (s, 3H, SMe2), 2.63, (d, 1H, J
3J (HePt) ¼ 49.6, 3H, SMe2), 2.68 (s, 3J (HePt) ¼ 61.4, 3H, SMe2),
3.27, (d, 2J (HeH)¼8.7, 2J (HePt) ¼ 118.2.1H, CH2), 3.58, (d, 2J
(HeH) ¼ 9.6, 2J (HePt) ¼ 77.1, CH2), 7.15e8.15 (CH, aromatics), 9.16
(HeH) ¼ 8.84, CH2), 3.10, (d, 1H, J (HeH) ¼ 9.99, CH2), 5.07, (d, J
(HeH) ¼ 12.3 Hz, 1H, CH2), 6.08, (d, J (HeH) ¼ 12.6 Hz, 1H, CH2),
7.10e8.19, (CH, aromatics), 9.09 (s, J (HePt) ¼ 128.2 Hz, 1H, CHN).
(s, 3J(HePt) ¼ 119.3, 1H, CHN). Minor Isomer:
d
¼ 2.76, (s, 3H, CH3),
13C NMR (100 MHZ, CD2Cl2) Major Isomer Only:
d
¼ 15.0 [CH3],
2.88, (s, 3J (HePt) ¼ 53.8, 6H, SMe2), 7.15e8.18 (CH, aromatics), 9.26
23.8 [SMe2], 70.0 [CH2],123.7, 124.5, 124.8,127.7, 128.1, 128.5, 128.8,
129.7, 131.5, 132.7, 133.6, 135.5, 137.1, 143.0, 168.2 [CHN]. (1HeH)-
2D-COSY-NMR
(s, 3J(HePt) ¼ 120.9, 1H, CHN). 13C NMR (100.3 MHz, CDCl3): (Major
Isomer only)
d
¼ 21.3 (PteCH2), 26.2 (SeMe), 26.7 (SeMe), 123.7,
Cross
Peaks:
(2.63e3.09)-[PtCH2ePtCH2],
123.8, 123.9, 124.0, 124.6, 125.1, 127.8, 128.0, 128.5, 129.4, 130.1,
141.2, 142.4, 153.6, 169.2 (CHN). (1HeH)-2D-COSY-NMR Cross
Peaks-(3.27e3.60)-[Major Isomer Methylenes]. (1HeH)-2D-NOESY-
NMR Cross Peaks-(3.27e3.60)-[Hc-Hd], (2.24e2.69)-[SMe2eSMe2].
(6.09e5.07)-[CH2eCH2], (8.55e5.44)e(CHNeCH2), (9.00e5.46)
e(CHNeCH2). HR-ESI-(þ)-MS: m/z 548.0710 calcd for
C21H21ClNPtS;
[MꢀBr]þ
548.0722.
Anal.
calcd
for
C21H21BrClNPtS: C, 40.0; H, 3.36; N, 2.22. Found: C, 42.3, H, 3.19; N,
2.0.
HR-ESI-(þ)-MS: m/z 500.0943 calcd for
C
20H20NPtS; [MꢀI]þ
500.0962. Anal. calcd for C20H20INPtS: C, 38.2; H, 3.2; N, 2.23.
Found: C, 39.66; H, 2.8; N, 1.92.
3.3.16. [PtI{8-MeC10H5CH ¼ NCH2(4ClC6H4)}SMe2] and [PtI
{CH2C10H6CH ¼ NCH2(4-ClC6H4)}SMe2], Pt4e5(SP-4-4):Pt4-
5(SP-4-3):Pt4-7(SP-4-4) (4:1:1)
3.3.14. [PtI{CH2C10H6CH ¼ NC6H5}PPh3]:[PtI{8-
MeC10H5CH ¼ NC6H5}PPh3], Pt2e7P:Pt2e5P (4:1)
Pt4-5(SP-4-4):Pt4-5(SP-4-3):Pt4-7(SP-4-4), (4:1:1), was ob-
tained by dissolving 0.022 g (0.054 mmol) of L4 and 0.015 g
(0.026 mmol) PtA in 15 mL anhydrous toluene. The solution was
then heated to reflux for 2 h. The resulting solution was brown with
black precipitate. The solution was filtered with diatomaceous
earth and the solvent evaporated to yield a dark brown solid. Yield
was 0.019 g (0.028 mmol, 52% yield). When an NMR tube con-
taining a toluene-d8 solution of Pt4-6 was heated at 100 ꢁC for 2 h a
similar mixture of products was observed. 1H NMR (400 MHz,
[PtI{CH2C10H6CH ¼ NC6H5}PPh3]:[PtI{8-MeC10H5CH ¼ NC6H5}
PPh3], (4:1) was obtained by refluxing a benzene solution of [PtI
{CH2C10H6CH ¼ NC6H5}SMe2]:[PtI{8-MeC10H5CH ¼ NC6H5}SMe2],
(4:1) (15.0 mg, 0.0238 mmol) and triphenylphosphine (6.24 mg,
0.0238 mmol) for 1 h under nitrogen. The resulting solution was
concentrated under rotary evaporation to produce a copper colored
solid. Unidentified decomposition products were also present. 1H
NMR (400 MHz, CDCl3): Major Isomer:
d
¼ 3.10 [dd, J (HeH) ¼ 9, J
(HeP) ¼ 9, 1H, Major Isomer Methylene], 3.17 [d, J (HeH) ¼ 9, 1H,
Major Isomer Methylene], 5.80 [d, J (HeH) ¼ 7.4, 1H, Upfield Aro-
matic], 6.97e8.20, [aromatics], 9.21 [d, 3J (PteH) ¼ 88.7, 4J
CDCl3): Five-Membered Ring, Major Isomer:
d
¼ 2.44, (s, 3H, Me),
2.86, (s, 3J (HePt) ¼ 52.2 Hz, 6H, SMe2), 5.68, (s, 3J (HePt) ¼ 26.6 Hz,
2H, CH2), 7.11e8.11, (CH, aromatics), 9.02 (s, 3J (HePt) ¼ 128.8, 1H,
(PeH) ¼ 10.4, 1H, CHN]. Minor Isomer:
d
¼ 2.80 [s, 3H, CH3, Me],
CHN). Five-Membered Ring, Minor Isomer:
d
¼ 2.34, (s, 3H, Me),
9.54 [d, 3J (PteH) ¼ 88.5, 4J (PeH) ¼ 9.0, 1H, CHN]. 13C NMR
2.87, (s, 3J (HePt) ¼ 51.76 Hz, 6H, SMe2), 5.64, (s, 2H, CH2), 7.11e8.11
(CH, aromatics), 8.63 (s, 3J(HePt) ¼ 127.5 Hz, 1H, CHN). Seven-
(100.6 MHz, CDCl3): Major Isomer:
d
¼ 25.4 [CH2ePt], 123.9, 124.3,
124.7, 125.4, 127.2, 127.4, 127.7, [d, J (CeP) ¼ 10.5, Cmeta, PPh3], 127.9,
128.5, 129.7, 130.1, [d, J (CeP) ¼ 2.2, Cpara, PPh3], 130.6, 131.2, 135.5,
135.7, 135.3, [d, J (CeP) ¼ 10.5, Cortho, PPh3], 137.3, 141.9, 153.3, 169.3
Membered Ring, Major Isomer:
d
¼ 2.47, (s, 3H, SMe2), 2.49, (s,
3H, SMe2), 2.67, (d, 1H, J (HeH) ¼ 7.70, CH2), 3.16, (d, 1H, J
(HeH) ¼ 8.40, CH2), 5.13, (d, J (HeH) ¼ 12.47 Hz, 1H, CH2), 6.19, (d, J
(HeH) ¼ 14.1 Hz, 1H, CH2), 7.11e8.11, (CH, aromatics), 9.11 (s, J
(HePt) ¼ 126.5 Hz, 1H, CHN). (1HeH)-2D-COSY-NMR Cross Peaks:
[CHN]. 31PNMR (161.8 MHz, CDCl3):
d
¼ 13.65, [s, 1J (PePt) ¼ 4388,
Major Isomer], 22.86, [s, 1J (PePt) ¼ 4145, Minor Isomer]. (1HeH)-

C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
35
synthesis and Catalysis, Chem. Rev. 110 (2010) 824e889, http://dx.doi.org/
10.1021/cr9003242.
(2.67e3.11)-[PtCH2ePtCH2], (5.15e6.20)-[CH2eCH2], (8.63e5.65)
e(CHNeCH2), (9.02e5.68)e(CHNeCH2). HR-ESI-(þ)-MS: m/z
548.0710 calcd for C21H21ClNPtS; [MꢀI]þ 548.0721. Anal. calcd for
C21H21ClINPtS: C, 37.3; H, 3.13; N, 2.07. Found: C, 39.2; H, 2.97; N,
1.75.
[5] E.P.A. Couzijn, I.J. Kobylianskii, M.-E. Moret, P. Chen, Experimental gas-phase
thermochemistry for alkane reductive elimination from Pt(IV), Organome-
tallics 33 (2014) 2889e2897, http://dx.doi.org/10.1021/om500478y.
ꢁ
[6] M.J. Geier, M. Dadkhah Aseman, M.R. Gagne, Anion-dependent switch in CeX
reductive elimination diastereoselectivity, Organometallics 33 (2014)
4353e4356, http://dx.doi.org/10.1021/om5006929.
[7] Y. Shiba, A. Inagaki, M. Akita, CeC bond forming reductive elimination from
diarylplatinum complexes driven by visible-light-mediated photoredox re-
actions, Organometallics 34 (2015) 4844e4853, http://dx.doi.org/10.1021/
om501080v.
[8] A.L. Liberman-Martin, D.S. Levine, W. Liu, R.G. Bergman, T.D. Tilley, Biaryl
reductive elimination is dramatically accelerated by remote lewis acid binding
to a 2,20-bipyrimidyleplatinum complex: evidence for a bidentate ligand
dissociation mechanism, Organometallics (2016), http://dx.doi.org/10.1021/
acs.organomet.5b01003 acs.organomet.5b01003e6.
[9] R. Das, A. Hepp, C.G. Daniliuc, F.E. Hahn, Synthesis of complexes with protic
NH,NH-NHC ligands via oxidative addition of 2-Halogenoazoles to zero-valent
transition metals, Organometallics 33 (2014) 6975e6987, http://dx.doi.org/
10.1021/om501120u.
[10] C. Tschersich, B. Braun, C. Herwig, C. Limberg, PBiP pincer complexes of
platinum, palladium, and iridium featuring metalemetal bonds synthesized
by oxidative addition of bismuthehalide bonds, Organometallics 34 (2015)
3782e3787, http://dx.doi.org/10.1021/acs.organomet.5b00439.
[11] J.A. Labinger, Tutorial on oxidative addition, Organometallics 34 (2015)
4784e4795, http://dx.doi.org/10.1021/acs.organomet.5b00565.
[12] J.M. Racowski, M.S. Sanford, Carboneheteroatom bond-forming reductive
elimination from palladium(IV) complexes, in: Topics in Organometallic
Chemistry, Springer Berlin Heidelberg, Berlin, Heidelberg, 2011, pp. 61e84,
http://dx.doi.org/10.1007/978-3-642-17429-2_3.
[13] D.M. Crumpton, K.I. Goldberg, Five-coordinate intermediates in carbon-
ꢀcarbon reductive elimination reactions from Pt(IV), J. Am. Chem. Soc. 122
(2000) 962e963, http://dx.doi.org/10.1021/ja9912123.
[14] D.M. Crumpton-Bregel, K.I. Goldberg, Mechanisms of CꢀC and CꢀH alkane
reductive eliminations from octahedral Pt(IV): reaction via five-coordinate
intermediates or direct elimination? J. Am. Chem. Soc. 125 (2003)
9442e9456, http://dx.doi.org/10.1021/ja029140u.
[15] J.A. Labinger, J.E. Bercaw, The role of higher oxidation state species in
platinum-mediated CeH bond activation and functionalization, in: Topics in
Organometallic Chemistry, Springer Berlin Heidelberg, Berlin, Heidelberg,
2011, pp. 29e59, http://dx.doi.org/10.1007/978-3-642-17429-2_2.
[16] M. Lersch, M. Tilset, Mechanistic aspects of CꢀH activation by Pt complexes,
Chem. Rev. 105 (2005) 2471e2526, http://dx.doi.org/10.1021/cr030710y.
[17] R.H. Crabtree, Organometallic alkane CH activation, J. Organomet. Chem. 689
(2004) 4083e4091, http://dx.doi.org/10.1016/j.jorganchem.2004.07.034.
[18] J.A. Labinger, J.E. Bercaw, Understanding and exploiting C-H bond activation,
Nature 417 (2002) 507e514, http://dx.doi.org/10.1038/417507a.
[19] R.J. Puddephatt, Platinum (IV) hydride chemistry, Coord. Chem. Rev. 219
(2001) 157e185.
[20] T. Wang, L. Keyes, B.O. Patrick, J.A. Love, Exploration of the mechanism of
platinum(II)-catalyzed CeF activation: characterization and reactivity of
platinum(IV) fluoroaryl complexes relevant to catalysis, Organometallics 31
(2012) 1397e1407, http://dx.doi.org/10.1021/om2007562.
[21] P.V. Bernhardt, T. Calvet, M. Crespo, M. Font-Bardía, S. Jansat, M. Martínez,
New insights in the formation of five- versus seven-membered platinacycles:
3.4. NMR tube experiments
3.4.1. [PtMe2Br{C10H6CH ¼ NCH2(4-ClC6H4)}SMe2], Pt3e6
Pt3-6 was obtained by dissolving 0.010 g of L3 (0.028 mmol) and
0.008 g (0.014 mmol) of PtA in 5 mL of toluene-d8. This solution
was transferred to an NMR tube. An 1H NMR spectrum of the re-
action was taken approximately 10 min after making the solution
and the formation of the product, Pt3-6, was observed. No halide-
bridged dimer was observed. 1H NMR (400 MHz, toluene-d8):
d
¼ 1.36, (s, 6H, SMe2), 1.61, (s, 2J (HePt) ¼ 67.5 Hz, 3H, PtMe),
1.86, (s, 2J (HePt) ¼ 69.7 Hz, PtMe), 5.59, (d, J (HeH) ¼ 14.6 Hz,
CH2), 5.73, (d, J (HeH) ¼ 15.3 Hz, CH2), 6.78e7.59, (m, aromatics),
7.90 (s, 3J (HePt) ¼ 24.6, CHN).
3.4.2. [PtMe2I{C10H6CH ¼ NCH2(4-ClC6H4)}SMe2], Pt4e6
Pt4-6 was obtained by dissolving 0.026 g of L4 (0.064 mmol)
and 0.018 g (0.031 mmol) of PtA in 5 mL of toluene-d8. This solution
was transferred to an NMR tube. An 1H NMR spectrum of the re-
action was taken approximately 10 min after making the solution
and the formation of the product, Pt4-6, was observed. No halide-
bridged dimer was observed. 1H NMR (400 MHz, toluene-d8):
d
¼ 1.40, (s, 6H, SMe2),1.77, (s, 2J (HePt) ¼ 73.3 Hz, 3H, PteMe), 2.07,
(s, 2J (HePt) ¼ 73.4 Hz, PteMe), 5.79, (m, 2H, CH2), 6.65e7.35 (m,
aromatics), 7.84 (s, 3J(HePt) ¼ 22.2, CHN).
Acknowledgments
This material is based upon work supported by the US National
Science Foundation under CHEe1362858 (Craig M. Anderson
(CMA), P.I.). We also thank Bard Summer Research Institute for
support and The Camille and Henry Dreyfus Foundation for sup-
porting CMA with a Henry Dreyfus Teacher-Scholar Award. X-ray
facilities were provided for by the US National Science Foundation
(grant No. 0521237 to JMT, P.I.). Mass spectrometry run at Vassar
College was performed using instrumentation supported by fund-
ing from a US National Science Foundation Major Research
Instrumentation Grant (#1039659, Teresa A. Garrett, P.I.). Thank
you to Jessica A. Geer and James Morris for assistance with
computational work. Bard College student Bradley Whitaker is also
acknowledged for his help preparing samples.
a
kinetico-mechanistic study, Inorg. Chem. 52 (2013) 474e484, http://
dx.doi.org/10.1021/ic3023584.
[22] M. Crespo, M. Font-Bardía, T. Calvet, Biaryl formation in the synthesis of endo
and exo-platinacycles, Dalton Trans. 40 (2011) 9431e9438, http://dx.doi.org/
10.1039/c1dt10664c.
[23] R. DiCosimo, G.M. Whitesides, Reductive elimination of a carbon-carbon bond
from bis (trialkylphosphine)-3, 3-dimethylplatinacyclobutanes produces bis
(trialkylphosphine) platinum (0), J. Am. Chem. Soc. 104 (1982) 3601e3607,
http://dx.doi.org/10.1021/ja00377a011.
[24] G.S. Hill, G. Yap, R.J. Puddephatt, Electrophilic platinum complexes: methyl
transfer reactions and catalytic reductive elimination of ethane from a tet-
ramethylplatinum (IV) complex, Organometallics (1999), http://dx.doi.org/
10.1021/om9809419.
[25] G.S. Hill, R.J. Puddephatt, Electrophilic platinum complexes: catalytic reduc-
tive elimination of ethane from a tetramethylplatinum (IV) complex, Organ-
ometallics 16 (1997) 4522e4524, http://dx.doi.org/10.1021/om970741h.
[26] A. Vigalok, Electrophilic halogenationereductive elimination chemistry of
organopalladium and -platinum complexes, Acc. Chem. Res. 48 (2015)
238e247, http://dx.doi.org/10.1021/ar500325x.
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2016.06.018.
Notes
The authors declare no competing financial interest.
References
[27] N.A. Smythe, K.A. Grice, B.S. Williams, K.I. Goldberg, Reductive elimination and
dissociative
b-hydride abstraction from Pt(IV) hydroxide and methoxide
ꢁ
[1] N. Selander, K.J. Szabo, Catalysis by palladium pincer complexes, Chem. Rev.
complexes, Organometallics 28 (2009) 277e288, http://dx.doi.org/10.1021/
om800905q.
111 (2011) 2048e2076, http://dx.doi.org/10.1021/cr1002112.
[2] L. Souillart, N. Cramer, Catalytic CeC bond activations via oxidative addition to
Transition metals, Chem. Rev. 115 (2015) 9410e9464, http://dx.doi.org/
10.1021/acs.chemrev.5b00138.
[3] L.M. Rendina, R.J. Puddephatt, Oxidative addition reactions of organo-
platinum(II) complexes with nitrogen-donor ligands, Chem. Rev. 97 (1997)
1735e1754.
[28] F. Zhang, E.M. Prokopchuk, M.E. Broczkowski, M.C. Jennings, R.J. Puddephatt,
Hydridodimethylplatinum(IV) complexes with bis(pyridine) ligands: effect of
chelate ring size on reactivity, Organometallics 25 (2006) 1583e1591, http://
dx.doi.org/10.1021/om050982m.
[29] E.M. Prokopchuk, R.J. Puddephatt, Hydrido(methyl)carbene complex of plat-
inum(IV), Organometallics 22 (2003) 563e566, http://dx.doi.org/10.1021/
[4] P. Sehnal, R.J.K. Taylor, I.J.S. Fairlamb, Emergence of palladium(IV) chemistry in

36
C.M. Anderson et al. / Journal of Organometallic Chemistry 819 (2016) 27e36
om0205400.
J. Organomet. Chem. 723 (2013) 188e197, http://dx.doi.org/10.1016/
j.jorganchem.2012.10.027.
[50] R. Martín, M. Crespo, M. Font-Bardía, T. Calvet, Five- and seven-membered
metallacycles in [C, N,N0] and [C,N] cycloplatinated compounds, Organome-
tallics 28 (2009) 587e597, http://dx.doi.org/10.1021/om800864f.
[30] H.L. Buckley, A.D. Sun, J.A. Love, User-friendly precatalyst for the methylation
of polyfluoroaryl imines, Organometallics 28 (2009) 6622e6624, http://
dx.doi.org/10.1021/om9008229.
[31] B.L. Madison, S.B. Thyme, S. Keene, B.S. Williams, Mechanistic study of
competitive sp3-sp3and sp2-sp3 carbonꢀcarbon reductive elimination from a
platinum (IV) center and the isolation of a CꢀC agostic complex, J. Am. Chem.
Soc. 129 (2007) 9538e9539, http://dx.doi.org/10.1021/ja066195d.
[32] E.G. Bowes, S. Pal, J.A. Love, Exclusive Csp3eCsp3vs Csp2eCsp3 reductive
elimination from Pt IV governed by ligand constraints, J. Am. Chem. Soc. 137
(2015) 16004e16007, http://dx.doi.org/10.1021/jacs.5b10993.
[33] S. Jamali, S.M. Nabavizadeh, M. Rashidi, Binuclear cyclometalated organo-
platinum complexes containing 1,10-Bis(diphenylphosphino)ferrocene as
spacer ligand: kinetics and mechanism of MeI oxidative addition, Inorg. Chem.
47 (2008) 5441e5452, http://dx.doi.org/10.1021/ic701910d.
[34] J.H. Alstrum-Acevedo, M.K. Brennaman, T.J. Meyer, Chemical approaches to
artificial photosynthesis. 2, Inorg. Chem. 44 (2005) 6802e6827, http://
dx.doi.org/10.1021/ic050904r.
[35] J. Boixel, V. Guerchais, H. Le Bozec, D. Jacquemin, A. Amar, A. Boucekkine, et al.,
Second-order NLO switches from molecules to polymer films based on
photochromic cyclometalated platinum(II) complexes, J. Am. Chem. Soc. 136
(2014) 5367e5375, http://dx.doi.org/10.1021/ja4131615.
[36] J. Kalinowski, V. Fattori, M. Cocchi, J.A.G. Williams, Light-emitting devices
based on organometallic platinum complexes as emitters, Coord. Chem. Rev.
255 (2011) 2401e2425, http://dx.doi.org/10.1016/j.ccr.2011.01.049.
[37] M. Albrecht, Cyclometalation using d-block transition metals: fundamental
aspects and recent trends, Chem. Rev. 110 (2010) 576e623, http://dx.doi.org/
10.1021/cr900279a.
[51] A. Capap, M. Crespo, J. Granell, A. Vizcarro, J. Zafrilla, M. Font-Bard a, et al.,
Unprecedented intermolecular C-H bond activation of
a solvent toluene
molecule leading to a seven-membered platinacycle, Chem. Commun. (2006)
4128, http://dx.doi.org/10.1039/b608666g.
[52] M. Crespo, M. Font-Bardía, X. Solans, Compound [PtPh2(SMe2)2] as a versatile
metalating agent in the preparation of new types of [C, N,N’] cyclometalated
platinum compounds, Organometallics 23 (2004) 1708e1713, http://
dx.doi.org/10.1021/om030674t.
[53] M. Crespo, M. Font-Bardía, T. Calvet, Biaryl formation in the synthesis of endo
and exo-platinacycles, Dalton Trans. 40 (2011) 9431, http://dx.doi.org/
10.1039/c1dt10664c.
[54] S. Anabuki, H. Shinokubo, N. Aratani, A. Osuka, A meso-spiro[cyclopentadiene-
isoporphyrin] from a phenylethynyl porphyrin platinum(II) pincer complex,
Angew. Chem. Int. 51 (2012) 3174e3177, http://dx.doi.org/10.1002/
anie.201109091.
[55] M. Font-Bardía, C. Gallego, M. Martínez, X. Solans, Unexpected formal aryl
insertion in a cyclometalated diphenylplatinum(IV) complex: the first seven-
membered cyclometalated platinum compound structurally characterized,
Organometallics
om020260k.
21
(2002)
3305e3307,
http://dx.doi.org/10.1021/
[56] C.R. Baar, M.C. Jennings, J.J. Vittal, R.J. Puddephatt, Activation of imines by
platinum(II) to give aminoalkyl complexes: scope and limitations of the re-
action, Organometallics 19 (2000) 4150e4158, http://dx.doi.org/10.1021/
om000401n.
[38] L. Keyes, T. Wang, B.O. Patrick, J.A. Love, Pt mediated C-H activation: formation
of a six membered platinacycle via Csp3-H activation, Inorg. Chim. Acta 380
(2012) 284e290, http://dx.doi.org/10.1016/j.ica.2011.09.030.
ꢀ
ꢁ
[57] A. Escola, M. Crespo, J. Quirante, R. Cortes, A. Jayaraman, J. Badia, et al.,
Exploring the scope of [Pt2(4-FC6H4)4( -SEt2)2] as precursor for new
m
a
[39] C.M. Anderson, M.W. Greenberg, T.A. Balema, L.M. Duman, N. Oh, A. Hashmi,
et al., Regioselective formation of six-membered platinacycles by C-X and C-H
oxidative addition, Tetrahedron Lett. 56 (2015) 6352e6355, http://dx.doi.org/
10.1016/j.tetlet.2015.09.121.
[40] C.M. Anderson, M. Crespo, J.M. Tanski, Synthesis and reactivity of coordination
and six-membered, cyclometalated platinum complexes containing a bulky
diimine ligand, Organometallics 29 (2010) 2676e2684, http://dx.doi.org/
10.1021/om100068j.
organometallic platinum(II) and platinum(IV) Antitumor agents, Organome-
tallics 33 (2014) 1740e1750, http://dx.doi.org/10.1021/om5000908.
[58] M. Crespo, C.M. Anderson, J.M. Tanski, Synthesis of platinum (II) cyclo-
metallated compounds derived from imines containing pyridyl or pyrimidyl
groups, Can. J. Chem. (2009) 80e87, http://dx.doi.org/10.1139/v08-084.
[59] C. Anderson, M. Crespo, Cyclometallated platinum complexes with hetero-
cyclic ligands, J. Organomet. Chem. 689 (2004) 1496e1502, http://dx.doi.org/
10.1016/j.jorganchem.2004.01.026.
[41] C.M. Anderson, M. Crespo, N. Kfoury, M.A. Weinstein, J.M. Tanski, Regiose-
lective CeH activation Preceded by C sp2eC sp3 reductive elimination from
cyclometalated platinum(IV) complexes, Organometallics 32 (2013)
4199e4207, http://dx.doi.org/10.1021/om400398g.
[42] M. Crespo, C.M. Anderson, N. Kfoury, M. Font-Bardía, T. Calvet, Reductive
elimination from cyclometalated platinum(IV) complexes to form
Csp2eCsp3Bonds and subsequent Competition between C sp2eH and C sp3eH
bond activation, Organometallics 31 (2012) 4401e4404, http://dx.doi.org/
10.1021/om300303a.
[60] C. Anderson, M. Crespo, J. Morris, J.M. Tanski, Reactivity of cyclometallated
platinum complexes with chiral ligands, J. Organomet. Chem. 691 (2006)
5635e5641, http://dx.doi.org/10.1016/j.jorganchem.2006.09.012.
[61] C. Anderson, M. Crespo, F.D. Rochon, Stereoselective oxidative addition of
methyl iodide to chiral cyclometallated platinum (II) compounds derived from
(R)-(þ)-1-(1-naphthylethylamine), J. Organomet. Chem. 631 (2001) 164e174,
http://dx.doi.org/10.1016/S0022-328X(01)01043-9.
[62] L. Rigamonti, A. Forni, M. Manassero, C. Manassero, A. Pasini, Cooperation
between cis and trans influences in cis-PtII(PPh3)2 complexes: structural,
spectroscopic, and computational studies, Inorg. Chem. 49 (2010) 123e135,
http://dx.doi.org/10.1021/ic901510m.
[43] K.A. Grice, J.A. Kositarut, A.E. Lawando, R.D. Sommer, Intramolecular C-H
activation by air-stable Pt(II) phosphite complexes, J. Organomet. Chem.
799e800
j.jorganchem.2015.09.031.
(2015)
201e207,
http://dx.doi.org/10.1016/
[63] L. Rigamonti, M. Rusconi, C. Manassero, M. Manassero, A. Pasini, Quantifica-
tion of cis and trans influences in [PtX(PPh3)3]þ complexes. A 31P NMR study,
Inorg. Chim. Acta 363 (2010) 3498e3505, http://dx.doi.org/10.1016/
j.ica.2010.07.002.
[64] M. Crespo, T. Calvet, M. Font-Bardía, Platinum-mediated arylearyl bond for-
mation and sp3 CeH bond activation, Dalton Trans. 39 (2010) 6936, http://
dx.doi.org/10.1039/c0dt00631a.
[65] H.A. Zhong, J.A. Labinger, J.E. Bercaw, CꢀH bond activation by cationic plati-
num(II) complexes: ligand electronic and steric effects, J. Am. Chem. Soc. 124
(2002) 1378e1399, http://dx.doi.org/10.1021/ja011189x.
[44] R. Cascante, M. Crespo, L. Davin, R. Martín, J. Quirante, D. Ruiz, et al., Seven-
membered cycloplatinated complexes as a new family of anticancer agents. X-
ray characterization and preliminary biological studies, Eur. J. Med. Chem. 54
(2012) 557e566, http://dx.doi.org/10.1016/j.ejmech.2012.06.002.
[45] S.H. Crosby, G.J. Clarkson, J.P. Rourke, A delicate balance between sp2and
sp3CꢀH bond activation: a Pt(II) complex with a dual agostic interaction,
J. Am. Chem. Soc. 131 (2009) 14142e14143, http://dx.doi.org/10.1021/
ja905046n.
[46] M. Crespo, M. Font-Bardía, M. Martínez, Kinetico-mechanistic studies on the
formation of seven-membered [C,N]-platinacycles: the effect of methyl or
fluoro substituents on the aryl ancillary ligands, Dalton Trans. 44 (2015)
19543e19552, http://dx.doi.org/10.1039/C5DT01926E.
[66] C.M. Anderson, M. Crespo, M.C. Jennings, A.J. Lough, G. Ferguson,
R.J. Puddephatt, Competition between intramolecular oxidative addition and
ortho metalation in organoplatinum (II) compounds: activation of aryl-
halogen bonds, Organometallics 10 (1991) 2672e2679.
[67] C.M. Anderson, M. Crespo, G. Ferguson, A.J. Lough, R.J. Puddephatt, Activation
of aromatic carbon-fluorine bonds by organoplatinum complexes, Organo-
metallics 11 (1992) 1177e1181.
[68] M. Lashanizadehgan, M. Rashidi, J.E. Hux, R.J. Puddephatt, S.S.M. Ling, The
synthesis, characterization and reactions of a binuclear tetramethylplatinum
complex, J. Organomet. Chem. 269 (1984) 317e322.
[69] G.M. Sheldrick, A short history of SHELX, Acta Crystallogr. A, Found. Crys-
tallogr. 64 (2008) 112e122, http://dx.doi.org/10.1107/S0108767307043930.
[70] J.D. Scott, R.J. Puddephatt, Ligand dissociation as a preliminary step in methyl-
for-halogen exchange reactions of platinum (II) complexes, Organometallics
(1983) 1643e1648.
ꢁ
[47] G. Aullon, M. Crespo, M. Font-Bardía, J. Jover, M. Martínez, J. Pike, A combined
kinetico-mechanistic and computational study on the competitive formation
of seven- versus five-membered platinacycles; the relevance of spectator
halide ligands, Dalton Trans. 44 (2015) 17968e17979, http://dx.doi.org/
10.1039/C5DT02657A.
[48] M. Crespo, M. Martinez, J. Sales, X. Solans, Syntheses and mechanistic studies
in the formation of endo-and exo-cyclometalated platinum compounds of N-
benzylidenebenzylamines, Organometallics 11 (1992) 1288e1295, http://
dx.doi.org/10.1021/om00039a038.
[49] C.M. Anderson, M.A. Weinstein, J. Morris, N. Kfoury, L. Duman, T.A. Balema, et
al., Biscyclometalated platinum complexes with thiophene ligands,