General strategy for the synthesis of rigid weak-link approach platinum(II) complexes: Tweezers, triple-layer complexes, and macrocycles

Article abstract of DOI:10.1021/ic302855f

Air-stable, heteroligated platinum(II) weak-link approach (WLA) tweezer and triple-layer complexes that possess P,X-Aryl hemilabile ligands (P = Ph ₂PCH₂CH₂-, X = chalcoethers or amines) have been synthesized via the halide-induced ligand rearrangement (HILR) reaction, using a one-pot, partial chloride-abstraction method. The approach is general and works with a variety of phosphine-based hemilabile ligands; when a P,S-Ph ligand is used as the relatively strongly chelating ligand, heteroligated complexes are formed cleanly when an ether- (P,O-Ph), amine- (P,N-Ph ₂), or fluorinated thioether-based (P,S-C₆F₄H) hemilabile ligand is used as the weakly chelating counterpart. The HILR reaction has also been used to synthesize bisplatinum(II) macrocycles free of oligomeric material without having to resort to the high-dilution conditions typical for macrocycle synthesis. This approach is complementary to the traditional WLA to the synthesis of macrocyclic complexes which typically proceeds via fully closed, chloride-free intermediates. The structures of the complexes may be toggled between semiopen (with only one chelating ligand) and fully closed (with both ligands chelating) via the abstraction and addition of chloride.

Full text of DOI:10.1021/ic302855f

Article
pubs.acs.org/IC
General Strategy for the Synthesis of Rigid Weak-Link Approach
Platinum(II) Complexes: Tweezers, Triple-Layer Complexes, and
Macrocycles
Robert D. Kennedy,† Charles W. Machan,† C. Michael McGuirk, Mari S. Rosen, Charlotte L. Stern,
Amy A. Sarjeant, and Chad A. Mirkin*
Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston,
Illinois 60208, United States
S
* Supporting Information
ABSTRACT: Air-stable, heteroligated platinum(II) weak-link
approach (WLA) tweezer and triple-layer complexes that possess
P,X−Aryl hemilabile ligands (P^ = Ph2PCH2CH2−, X =
chalcoethers or amines) have been synthesized via the halide-
induced ligand rearrangement (HILR) reaction, using a one-pot,
partial chloride-abstraction method. The approach is general and
works with a variety of phosphine-based hemilabile ligands; when
a P,S−Ph ligand is used as the relatively strongly chelating ligand,
heteroligated complexes are formed cleanly when an ether-
(P,O−Ph), amine- (P,N−Ph2), or fluorinated thioether-based
(P,S−C6F4H) hemilabile ligand is used as the weakly chelating
counterpart. The HILR reaction has also been used to synthesize bisplatinum(II) macrocycles free of oligomeric material without
having to resort to the high-dilution conditions typical for macrocycle synthesis. This approach is complementary to the
traditional WLA to the synthesis of macrocyclic complexes which typically proceeds via fully closed, chloride-free intermediates.
The structures of the complexes may be toggled between semiopen (with only one chelating ligand) and fully closed (with both
ligands chelating) via the abstraction and addition of chloride.
preventing the formation of polymeric and oligomeric by-
products.1 A reaction often used in conjunction with the WLA
is the halide-induced ligand rearrangement (HILR) reac-
tion,5,42−45 in which a ligand-sorting process between
electron-rich and electron-poor hemilabile ligands leads
exclusively to heteroligated structures, thus allowing for an
extra level of complexity to be incorporated into WLA
architectures (2, 3, 6, 7, 8, and 9, Scheme 1).
Functional allosteric enzyme mimics synthesized via the
WLA rely on the precise positioning of active groups that are
incorporated into the hemilabile ligand. This is achieved by
using rigid ligands in which the weakly coordinating atom
(Scheme 1) is bound directly to an aryl group. In the case of
rhodium(I), rigid, heteroligated aryl−aryl complexes may be
synthesized cleanly and reliably using P,S−aryl and P,O−aryl
ligands as the strong and weak binders, respectively. However,
the sensitivity of rhodium(I) WLA complexes to air limits their
compatibility with certain reaction environments, and accord-
ingly, a recent focus of our work has been the expansion of the
WLA to include the chemistry of more stable d8 metals such as
nickel(II), palladium(II), and platinum(II).32,43,44,46−50 We
have demonstrated that heteroligated tweezers and triple-layer
INTRODUCTION
■
Within the discipline of coordination chemistry, the weak-link
approach (WLA)1−6 has emerged as a powerful means to
assemble complicated supramolecular structures (Scheme 1).
Unlike the symmetry-interaction approach (SIA)7−11 and
directional bonding approach (DBA),12−26 which lead to static,
rigid structures, the WLA results in dynamic complexes that
may be toggled between rigid and flexible states via the
introduction and removal of elemental anions or small-
molecule “effectors”. Functional units such as catalytic sites,
redox-active moieties, host−guest recognition sites, and
fluorophores may be incorporated into the ligands in such a
way that the structural change results in a marked change in the
properties of the complex.27−33 Allosteric regulation of this type
resembles the behavior of many enzymes, and examples of this
aspect of biomimicry are otherwise rare in coordination
chemistry.6,34−37
The WLA for the synthesis of macrocyclic complexes
employs symmetric homoditopic ligands that possess rigid
cores and two hemilabile38−41 phosphino−chalcoether (P,X; X
= S, O, Se) or phosphino−amine (P,N) moieties (Scheme
1).2,3,5,6 Upon chelation to a d8 metal center [e.g., rhodium(I),
palladium(II)] and in the absence of coordinating anions, the
favored cis geometry of the phosphine ligands promotes the
clean formation of bimetallic macrocyclic assemblies while
Received: December 28, 2012
© XXXX American Chemical Society
A
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
a
Scheme 1. Weak-Link Approach to the Synthesis of Macrocycles and Heteroligated Tweezer and Triple-Layer Complexes
a
(a) The traditional WLA for the synthesis of macrocycles utilizes ditopic bidentate ligands (1) and d8 metal precursors (M) paired with
noncoordinating anions (XNC−). The synthesis proceeds via the templated formation of a condensed intermediate (2) that may be opened reversibly
by various coordinating ligands (XC−) to form the fully open species (3). (b and c) The HILR reaction results in a ligand sorting process that cleanly
produces heteroligated species. These may be toggled between semiopen (6, 8) and closed structures (7, 9) via the removal and addition of
coordinating anions. E, Y, and Z represent the weak-link ligands, which are usually chalcoethers or amines. A, B, and C can be functional groups (e.g.,
catalysts, recognition sites, redox active moieties).
complexes form cleanly and spontaneously with palladium(II)
and platinum(II) when alkyl- and aryl-based hemilabile ligands
are used in combination (e.g., Scheme 2; compound
22).43,44,46,47 One shortcoming of this assembly technique is
that alkyl-based ligands are inherently flexible and thus
unsuitable for the construction of rigid architectures in which
supramolecular properties are controlled with structural
changes. A general, modular route to rigid, heteroligated
aryl−aryl′ palladium(II) and platinum(II) complexes, which is
compatible with many functional ligands, is highly desirable.
However, typical synthetic approaches to aryl−aryl′ palladium-
(II) and platinum(II) complexes have failed so far, resulting in
dynamic mixtures which contain multiple species. Herein we
report a new method for the clean and quantitative synthesis of
rigid, platinum(II) WLA assemblies (Scheme 1; 2, 3, 6, 7, 8, 9)
via partial abstraction of chloride in either protic or nonpolar
solvents. Using this method, heteroligated tweezers, triple layer
complexes, and binuclear macrocycles have been obtained from
a variety of aryl-based hemilabile P,S, P,O, and P,N ligands.
These complexes serve as models for functional, air-stable WLA
systems.
combinations of aryl-based hemilabile ligands that fulfilled
two principal criteria: (a) the difference in chelating strength
between the ligands is sufficiently high to favor the clean
formation of heteroligated species and (b) the ligands are
synthetically accessible, i.e., their incorporation into more
complex molecules is relatively straightforward. Thus, the
phenyl-terminated thioether ligand Ph2PCH2CH2SPh (P,S−
Ph; 10) was chosen as the strongly chelating ligand (Scheme
2), and three different weakly binding ligands (Scheme 2) were
evaluated in order to increase the potential generality of the
s y s t e m : 2 , 3 , 5 , 6 - t e t r a fl u o r o p h e n y l t h i o e t h e r ,
Ph2PCH2CH2SC6F4H (P,S−C6F4H; 11); phenyl ether,
Ph2PCH2CH2OPh (P,O−Ph; 12); and the diphenylamine
derivative, Ph2PCH2CH2NPh2 (P,N−Ph2; 13). Importantly,
the chemical attachment of these P,X moieties onto functional
molecules, for example, porphyrins and salens or large sterically
hindering groups, is relatively simple via established synthetic
procedures.51,52
The dynamic behavior of d8 metal complexes which possess
two hemilabile ligands has been investigated in detail by our
group and others.53−63 For the specific cases of platinum(II)-
based tweezer complexes with the general formula
PtCl2(Ph2PCH2CH2SR)2 (R = aryl, alkyl), the equilibria
describing the distribution of chloride anions between the
inner and outer coordination spheres is shown in Scheme 2b.
In general, aprotic solvents such as dichloromethane shift the
RESULTS AND DISCUSSION
■
Heteroligated Tweezer Compounds. We focused on
simple heteroligated tweezer complexes constructed from
phosphine-based (P,X) hemilabile ligands. We explored
B
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
PtCl2(P,S−C6F4H)2 (19), which possesses weakly coordinating
ligands, exists as a static, semiopen species in methanol and as a
static, fully open species in dichloromethane. On the other
hand, closed species are favored when strongly chelating
hemilabile ligands (e.g., R = Me; 20) are used. For example, the
homoligated complex [Pt(P,S−Me)2]Cl2 (20), which possesses
strongly chelating ligands, exists exclusively as the fully closed
species in methanol as determined by 31P{1H} NMR
spectroscopy, whereas in dichloromethane, a fast “windshield
wiper” exchange67 between equivalent semiopen structures is
observed. When ligands of intermediate chelating strength are
involved, the behavior lies somewhere between these two
extremes. For example, the homoligated complex PtCl2(P,S−
Ph)2 (21) dissolved in dichloromethane undergoes dynamic
equilibrium between fully open (16) and semiopen (17)
structures as the outer-sphere chloride ion competes with the
weakly chelating ligand, whereas in methanol the chlorides are
solvated to the extent that dynamic equilibrium between
semiopen (17) and fully closed (18) structures is ob-
served.64−66
Scheme 2. (a) Model Ligands 10−15 Used in This Study; (b)
Distribution of Chloride Anions between the Inner and
Outer Coordination Spheres [Fully Open (16), Semiopen
(17), and Fully Closed Species (18)]; (c) Examples of
Platinum(II) WLA Tweezer Complexes with Weak (19),
Strong (20), and Intermediate Strength (21) Chelating P,S
a
Ligands
When a strongly chelating ligand is paired with a relatively
weakly chelating ligand (e.g., P,S−Me and P,S−Ph; 22) in
dichloromethane, the equilibrium favors the formation of
heteroligated semiopen species (e.g., 17); the system is stabilized
via the maximization of the number of strong Pt−S interactions
formed through the chelation of the P,S−Me ligand.44,47
Importantly, in dichloromethane, the chelation of the P,S−Me
ligand is strong enough to prevent the second chloride anion
from binding to the platinum center, and no contribution from
the fully open species is observed.44,45
Because we were targeting the formation of heteroligated
aryl−aryl′ complexes, we hypothesized that they could be made
by pairing P,S−Ph (10) with comparatively weakly chelating
ligands such as P,S−C6F4H (11), P,O−Ph (12), or P,N−Ph2
(13). As a point of entry we decided to explore the chemistry of
the fluorinated ligand 11. The fluorinated P,S ligand system was
of particular interest to us because of the synthetic accessibility
of the fluorinated hemilabile subunit, [(Ph2PCH2CH2S)-
C6F4−].51,52
The combination of ligands 10 and 11 with PtCl2(cod) (cod
= 1,5-cyclooctadiene) in a 1:1:1 ratio in dichloromethane
resulted in an unresolvable and dynamic mixture of species, as
determined by in situ 31P{1H} NMR spectroscopy.68
Presumably, this is due to the presence of fully open species
which interfere with the thermodynamically controlled ligand
sorting process. The cod byproduct was removed via
precipitation with hexanes to give a white solid that was used
for all subsequent reactions. Further evidence that ligand
sorting does not occur satisfactorily in dichloromethane
solution was obtained via the abstraction of both chloride
anions using silver hexafluorophosphate. The abstraction, which
essentially traps the various species present in solution, resulted
in a mixture of closed homoligated and heteroligated
complexes. In contrast, when the white solid that was obtained
from the hexane precipitation was dissolved in methanol, the
semiopen heteroligated tweezer 23a formed quantitatively
(Scheme 3). The in situ 31P{1H} NMR spectrum exhibits
defined doublets and associated 195Pt satellites at δ 10.20 (1JPt−P
a
Complex 22 is a heteroligated alkyl−aryl complex.
equilibria to the left as drawn, favoring fully open species (16,
Scheme 2b), in which there are two inner-sphere chlorides and
both ligands are nonchelating, or semiopen species (17) that
possess one chelating ligand and one outer-sphere chloride. In
protic solvents such as methanol, outer-sphere chloride anions
are stabilized by hydrogen bonding, thus shifting the
equilibrium to the right and favoring closed species
(18).64−66 The distribution of products in solution is also
related to the strength of the thioether coordination. In the
cases of complexes with weakly coordinating hemilabile ligands
(e.g., R = C6F4H; 19), the equilibrium favors fully open or
semiopen species. For example, the homoligated complex
2
= 3235 Hz, JP−P = 14 Hz), which is consistent with a
nonchelated ligand with the phosphorus trans to a S-bound
2
phenyl thioether, and δ 45.74 (1JPt−P = 3486 Hz, JP−P = 14
Hz), which is consistent with a chelated ligand with the
phosphorus atom trans to a chloride. The coupling constants
C
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 3. Synthesis of Heteroligated Tweezer Compounds
23a, 23b, and 24
Figure 1. Molecular structures of compounds 23b (a) and 24 (b and
c) determined via single-crystal X-ray diffraction. Thermal ellipsoids
are drawn at 50% probability. Hydrogen atoms, occluded solvent
molecules, and anions are omitted for clarity. Atom color code: Pt =
black; P = magenta; S = orange; Cl = green; F = yellow-green; C =
gray.
are consistent with a mutual cis coordination of the phosphorus
atoms to the platinum center.68 Removal of the methanol
followed by dissolution in dichloromethane regenerated the
unresolvable mixture, demonstrating the highly dynamic nature
of the system. Importantly, the addition of a methanolic
solution of ammonium hexafluorophosphate to the semiopen
complex, also in methanol, resulted in the immediate
precipitation of the heteroligated hexafluorophosphate salt
23b in high yield. Unlike the parent dichloride complex 23a,
compound 23b retains its semiopen structure when redissolved
in dichloromethane, as discussed below. Slow diffusion of
hexanes into a solution of 23b in dichloromethane resulted in
the growth of crystals suitable for single-crystal X-ray diffraction
analysis (Figure 1a). In the solid state, the platinum center has a
square planar geometry. The nonfluorinated ligand 10 is
chelating whereas the fluorinated ligand 11 is coordinated only
through the phosphine. The phosphines have a mutual cis
orientation, and the remaining coordination site is occupied by
a chloride.
To improve the generality of the approach, we sought a route
to the stable, semiopen complex 23b that did not involve the
precipitation of the complex from methanol. We reasoned that
a major factor in the spontaneous formation of heteroligated
complexes in methanol is the solvation and effective removal of
a single chloride anion from the inner to the outer coordination
sphere. With only one chloride available for inner-sphere
coordination and no contribution from fully open dichloride
species, a HILR ligand sorting process can occur that leads to
well-defined products. The HILR process does not occur in
aprotic dichloromethane because of the greater coordinating
strength of the chloride to the platinum center in this solvent.
This results in the formation of fully open species that have two
chloride ions coordinated to the platinum center, thus
disrupting the thermodynamic landscape of the reaction. We
hypothesized that the chemical removal of a single chloride ion
in a nonprotic solvent such as dichloromethane using a single
equivalent of a silver-based abstraction agent would mimic the
action of methanol, thus leading to heteroligated complexes.
Indeed, as mentioned earlier, the semiopen complex 23b, which
is synthesized in methanol and possesses only a single chloride
anion, retains its semiopen structure when dissolved in
dichloromethane. Thus, the addition of a single equivalent of
silver hexafluorophosphate to the mixture of species formed
from P,S−Ph and P,S−C6F4H in dichloromethane resulted in
the precipitation of silver chloride and the clean formation of
the semiopen, heteroligated complex 23b over several hours
(Scheme 3). The in situ 31P{1H} NMR spectrum is essentially
identical to that of compound 23b isolated from methanol. As
mentioned above, if both chlorides are removed simultaneously,
the HILR process does not have time to operate, and a mixture
of fully chelated species is obtained.
The fully closed, heteroligated complex 24 could be
synthesized via the addition of 1 equiv of silver hexafluor-
ophosphate to a solution of semiopen complex 23b in
dichloromethane. In situ 31P{1H} NMR spectroscopy indicated
a quantitative conversion: the spectrum contains only two
downfield doublets (δ 45.46 and δ 46.36) with a mutual
coupling of 13 Hz and 195Pt−31P coupling constants of 3087
and 3252 Hz, respectively, which is consistent with a fully
closed complex. The 195Pt−31P coupling constants may be used
to assign the NMR signals: the signal δ 45.46 exhibits a
coupling constant of 3087 Hz, thus suggesting that the
corresponding phosphorus atom is trans to the phenyl
thioether. The signal at δ 46.36, which exhibits a larger
coupling constant of 3252 Hz, corresponds to the phosphorus
atom trans to the weakly coordinating tetrafluorophenyl
thioether. Subsequent single-crystal X-ray diffraction analysis
revealed that, in the solid state, complex 24 has a fully closed,
heteroligated structure with a square planar coordination
geometry (Figure 1b). Similar to other closed tweezer
complexes, the planes of the sulfur-bound aryl groups are
approximately parallel and the groups are staggered; i.e., the
C1−S1−S2−C2 dihedral angle is 87.6(5)° (Figure 1c). All
other characterization data are consistent with this structural
assignment. In methanol or dichloromethane, the semiopen
D
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
complex 23b may be regenerated from the fully closed
compound 24 upon the addition of a single equivalent of
tetraethylammonium chloride, demonstrating the reversibility
of the system.
Scheme 5. Synthesis of Heteroligated Tweezer Compounds
29−32 that Contain P,O−Ph and P,N−Ph2 Ligands
To confirm that the HILR reaction is operating in this Pt(II)
system, equimolar quantities of the homoligated semiopen
complexes 25 and 26 were stirred together in dichloromethane
at room temperature. Over the course of 24 h, complete
rearrangement to the heteroligated species occurred (Scheme
4a). In the case of the fully closed species 27 and 28, on the
Scheme 4. Formation of Heteroligated Tweezer 23b from
Homoligated Species 25 and 26 (a) via the Halide-Induced
Ligand Rearrangement Reaction while (b) No Reaction
Occurs between Fully Closed Complexes 27 and 28
Figure 2. Molecular structures of compounds (a) 29b and (b) 30b
determined via single-crystal X-ray diffraction. Thermal ellipsoids are
drawn at 50% probability. Hydrogen atoms, occluded solvent
molecules, and anions are omitted for clarity. Atom color code: Pt =
black; P = magenta; S = orange; O = red; N = blue; Cl = green; F =
yellow-green; C = gray.
crystal X-ray diffraction analyses (Figure 2). Similar to
compound 23b (Figure 1), both 29b and 30b have semiopen
heteroligated structures in the solid state. The platinum centers
of all three complexes have square planar coordination
geometries with a cis disposition of the phosphine ligands. In
29b and 30b, the P,S−Ph ligand 10 is chelating whereas the
P,O−Ph ligand 12 and P,N−Ph2 ligand 13 are monodentate,
and a single chloride occupies the fourth coordination site.
Attempts to generate the heteroligated, fully closed phos-
phine−phenyl ether complex 31, using a variety of chloride-
abstracting agents (silver hexafluorophosphate, silver tetrafluor-
oborate, trimethylsilyl trifluoromethanesulfonate, and trimethy-
loxonium tetrafluoroborate) in dichloromethane, failed. In all
cases, in situ 31P{1H} NMR spectroscopy revealed that no
reaction had taken place. Presumably, the observation that 29b
(Scheme 5) does not form the fully closed species is
attributable to the very low affinity of the phenyl ether for
the platinum center. In contrast, the fully closed, heteroligated
diphenylamino species 32 was obtained from the semiopen
species 30b cleanly and quantitatively via the reaction with a
single equivalent of silver hexafluorophosphate in dichloro-
methane, as evidenced by spectroscopic analyses.
other hand, no ligand sorting occurred (Scheme 4b). Thus, it
appears from the aforementioned reactions that the chemistry
of the platinum(II) system with a single chloride removed from
the inner coordination sphere closely resembles that of the
analogous Rh(I) system.
To expand the scope and explore the potential generality of
the reaction, we performed an analogous series of reactions
using the related phosphine−phenyl ether and phosphine−
diphenylamino ligands 12 and 13, respectively, as the weak
chelators (Scheme 5). Indeed, the reactions proceeded in a
manner similar to those performed with the P,S−C6F4H ligand
11 (Scheme 3), and heteroligated, semiopen complexes were
obtained cleanly and in good yields. In both cases, methanol
was required to induce the ligand sorting process, and the
addition of methanolic ammonium hexafluorophosphate
resulted in the precipitation of pure semiopen species as the
hexafluorophosphate salts 29b and 30b (Scheme 5). The
semiopen complexes maintained their composition in dichloro-
methane, as determined by 31P{1H} NMR spectroscopy. The
solid-state structures were determined in both cases via single-
Triple-Layer Complexes. We have previously shown that
WLA complexes based on rhodium(I) can be the basis for
E
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 6. Synthesis of Triple Layer Complexes 33−34
powerful allosteric systems in which monometallic catalysts that
are buried in the central layer of a triple-layer assembly may be
reversibly exposed by addressing allosteric “hinge” sites with
small-molecule or elemental effectors (Scheme 1c).33 These
allosteric catalysts display no background activity in the “off”
state, and considering the large amount of synthetically
accessible monometallic catalysts, we are eager to further
explore this particular avenue of research. At present, this
chemistry is restricted by the air-sensitivity of rhodium(I), and
there is a need to develop the chemistry of platinum(II)-based
systems in order to exploit their higher stability and use a
greater scope of allosteric effector.47 For these studies we
focused on the combination of fluorinated and nonfluorinated
thioether ligands (Scheme 6) and assumed that, as in the case
of the heteroligated tweezers, the related P,N triple-layer
complex would behave in an essentially identical manner.
Thus, in an analogous fashion to the synthesis of the
heteroligated tweezers, the combination of fluorinated ditopic
ligand 14, nonfluorinated ligand 10, and PtCl2(cod) in a 1:2:2
ratio in dichloromethane produced a dynamic and unresolvable
mixture of compounds (Scheme 6). The cod byproduct was
removed via precipitation with hexanes to give a white solid
that was used for all subsequent reactions. When this solid was
dissolved in methanol, the mixture equilibrated over a period of
minutes to produce a single semiopen species 33a, as
characterized using in situ 31P{1H} NMR spectroscopy. The
spectrum closely resembles that of the related tweezer complex
23a (Scheme 3), with a doublet at δ 9.10 (1JPt−P = 3257 Hz,
2JP−P = 15 Hz), which corresponds to the nonchelating ligand,
Figure 3. Molecular structures of compounds (a) 33b and (b) 34
determined via single-crystal X-ray diffraction. Thermal ellipsoids are
drawn at 50% probability. Hydrogen atoms, occluded solvent
molecules, and counteranions are omitted for clarity. Atom color
code: Pt = black; P = magenta; S = orange; Cl = green; F = yellow-
green; C = gray.
2
and a doublet at δ 43.30 (1JPt−P = 3452 Hz, JP−P = 15 Hz),
which corresponds to the chelating ligand. This indicates the
clean formation of the semiopen triple-layer complex. The
addition of a methanolic solution of ammonium hexafluor-
ophosphate to the solution resulted in the immediate
precipitation of semiopen hexafluorophosphate salt 33b
(Scheme 6). Similar to the tweezer complex 23a (Scheme 3),
the replacement of chloride with the hexafluorophosphate
anion stabilizes the structure; the 31P{1H} NMR spectrum of
33b in dichloromethane is essentially identical to that of the
nonabstracted complex 33a in methanol. The semiopen triple-
layer structure of 33b was subsequently confirmed using single-
crystal X-ray diffraction analysis (Figure 3a). The ditopic ligand
14 bridges the two platinum centers, and both of the P,S
moieties are coordinated only through phosphine. Both the
P,S−Ph ligands in 33b are chelating, and there is a mutual cis
arrangement of phosphines at each platinum center. Chloride
anions occupy the remaining coordination sites. All other
characterization data for 33b are consistent with the proposed
structure.
triple-layer complex 34 (Scheme 6). The choice of nitro-
methane is important in the case of the condensed,
tetracationic model complexes described in this report because
of their low solubility in common solvents such as dichloro-
methane, methanol, and acetonitrile. Furthermore, the
solubility of silver chloride is sufficiently low in nitromethane
for effective abstraction and simple purification via filtration.
Similar to the fully closed tweezer complex 24, the in situ
31P{1H} NMR spectrum of 34 contains closely spaced doublets
at δ 46.76 (1JPt2−P = 3129 Hz, 2JP−P = 13 Hz) and δ 47.06 (1JPt−P
= 3229 Hz, JP−P = 13 Hz), indicating that the reaction
proceeds quantitatively. The magnitudes of the 195Pt−31P
coupling constants suggest that the signals at δ 46.76 and 47.06
correspond to the phosphorus atoms trans to the phenyl
thioether and tetrafluorophenyl thioether, respectively. Com-
pound 34 was separated from silver chloride by filtration and
isolated via precipitation with diethyl ether (Scheme 6). Single-
crystal X-ray diffraction analysis confirmed the fully closed
triple-layer structure (Figure 3b). The ditopic ligand (14)
Abstraction of the remaining chlorides from 33b using silver
hexafluorophosphate in nitromethane generates the fully closed
F
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 7. Syntheses of Macrocyclic Complexes 35−37
Scheme 8. Syntheses of Macrocyclic Complexes 38 and 39
Figure 4. Molecular structures of compounds (a) 36, (b) 35b, (c) 37, and (d) 39 (PF6 salt) determined via single-crystal X-ray diffraction. Thermal
ellipsoids for a−c are drawn at 50% probability. Thermal ellipsoids for d are drawn at 30% probability. Hydrogen atoms, occluded solvent molecules,
and counteranions are omitted for clarity. Atom color code: Pt = black; P = magenta; S = orange; Cl = green; F = yellow-green; C = gray.
G
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
bridges the platinum centers, and the central tetrafluorophe-
nylene ring and phenyl groups are arranged in a staggered,
parallel fashion.
Na[BArF] in 1,2-dichloroethane ([BArF] = tetrakis(3,5-bis-
[trifluoromethyl]phenyl)borate). The in situ 31P{1H} NMR
spectrum of this solution resembles that of the unabstracted
complex 35a in methanol, and contains two defined doublets
with associated 195Pt satellites at δ 42.52 (1JPt2−P = 3419 Hz,
2JP−P = 14 Hz) and δ 9.02 (1JPt−P = 3409 Hz, JP−P = 15 Hz)
that indicate the formation of a single semiopen species (35b):
the signal at δ 45.52 is consistent with a chelating ligand in
which the phosphorus atom is trans to a chloride, and the signal
at δ 9.02 is consistent with a nonchelating ligand in which the
phosphorus atom is trans to a tetrafluorophenylene thioether.
Single crystals were obtained via the slow diffusion of hexanes
into a solution of 35b in dichloromethane. X-ray diffraction
analysis confirmed the macrocyclic, semiopen structure of 35b
(Figure 4b). The coordination sphere of each platinum center
has a square planar geometry and contains one chelating ligand
and one nonchelating phosphine-bound ligand in a cis
arrangement. The remaining site is occupied by a chloride
ligand, which is directed into the center of the macrocycle. Each
ligand bridges the two platinum centers and is chelating
through one P,S moiety and nonchelating through the other.
The molecule possesses a quasi-C2 symmetry axis that is aligned
perpendicularly to the plane of the macrocycle.
Treatment of fully open macrocycle 36 with 4 equiv of silver
tetrafluoroborate in nitromethane resulted in the clean
formation of the condensed tetracationic macrocycle 37
(Scheme 7). The 31P{1H} NMR spectrum of 37, measured in
nitromethane-d3, contains a single, sharp singlet at δ 51.01 with
corresponding 195Pt satellites (1JPt−P = 3209 Hz), indicative of a
highly symmetrical molecule that possesses only chelating
ligands. The structure was confirmed using single-crystal X-ray
diffraction analysis (Figure 4c). The macrocycle 37, which is
isostructural with its rhodium(I) and iridium(I) analogues
[(κ2:μ:κ2-(1,4-bis[(2′-(diphenylphosphino)ethyl)-thio]-2,3,5,6-
tetrafluorobenzene)2M2][BF4]2 (M = Rh, Ir),1,69 is centrosym-
metric and possesses cofacial fluorophenylene rings.
Bisplatinum(II) Macrocycles. As mentioned in the
Introduction, the original WLA to the synthesis of macrocylic
supramolecular complexes proceeds via a fully closed
“condensed” intermediate (Scheme 1a).1 This intermediate
forms cleanly because a cis ligand geometry is produced around
the first metal center, thus positioning the remaining chelating
moieties of the symmetrical, ditopic ligands rigidly and
mutually adjacent and favoring cyclization. Strongly coordinat-
ing ligands such as chloride disrupt this templating effect
because they compete more effectively for the metal center than
the weak-link heteroatom. To avoid this, d8 metal precursors
with noncoordinating counteranions, such as [Rh(nbd)2][BF4]
(nbd = norbornadiene) or [Pd(CH3CN)4][BF4]2), are typically
used to synthesize WLA macrocycles.1−3 Our observation that
the HILR reaction was operating in platinum(II) tweezer and
triple-layer complexes led us to consider if bisplatinum(II)
macrocycles could be obtained in the presence of chloride with
a greater degree of thermodynamic control. We hypothesized
that the reversibility inherent in the HILR reaction would result
in the degradation of oligomeric and polymeric material, and
favor the concomitant formation of discrete macrocycles.
Model systems based on fluorinated and nonfluorinated ditopic
ligands 14 and 15 (Schemes 7 and 8), respectively, were chosen
to investigate this possibility for the reasons of synthetic
accessibility previously stated.
The reaction of equimolar quantities of fluorinated ditopic
ligand 14 and PtCl2(cod) in dichloromethane at room
temperature resulted in the complete consumption of the
starting materials, as determined by in situ 31P{1H} NMR
spectroscopy. The cod byproduct was removed via precipitation
with diethyl ether to give a white solid mixture of products
(vide infra) that was used for subsequent reactions.
A solution of this mixture of products in methanol was
heated for several hours at 40 °C. The in situ 31P{1H} NMR
spectrum of the solution exhibits two symmetrical, slightly
broadened signals with associated 195Pt satellites at δ 44.81
The semiopen macrocycle 35b was regenerated from closed
complex 37 in nitromethane via the addition of 1 equiv of
tetraethylammonium chloride per platinum atom (Scheme 7).
Similarly, the addition of tetraethylammonium chloride to a
solution of the semiopen complex 35b in dichloromethane
cleanly generated the fully open complex 36.
2
(1JPt−P = 3452 Hz) and δ 9.58 (1JPt−P = 3402, JP−P = 14 Hz)
that indicate the clean conversion to a single semiopen species
with cis phosphines (35a). In a similar fashion to the other
semiopen species in this study, the downfield signal
corresponds to the chelating ligand, and the upfield signal
corresponds to the nonchelating ligand. The addition of diethyl
ether to this solution resulted in the precipitation of a white
crystalline solid. Single-crystal X-ray diffraction analysis (Figure
4a) revealed that, upon crystallization, the outer-sphere chloride
anions coordinate to the platinum to produce the fully open
complex (36) in which the ligands are coordinated through the
phosphorus atoms only, and a square planar cis coordination
geometry around each platinum is observed. A crystallographic
inversion center is located at the center of the macrocycle, and
the tetrafluorophenylene rings are parallel planar (Figure 4a).
The 31P{1H} NMR spectrum of a solution of the white
crystalline solid 36 in dichloromethane displays a single, sharp
Importantly, when the initial heating step in methanol was
not performed, thus effectively bypassing the semiopen
complex 35a (Scheme 7), subsequent chloride-abstraction
reactions resulted in mixtures of complexes. Because ligand 14
is weakly chelating, the chloride ligands bind strongly to the
platinum centers in dichloromethane thus preventing the HILR
reaction from occurring. The initial products of the reaction,
which form a mixture of fully open species that includes the
desired macrocycle 36 along with presumably oligomeric
material and larger macrocyclic species, are thus trapped. As
successive chloride anions are abstracted, the mixture of
oligomers and macrocycles is conserved. For example, when
one chloride per platinum atom was abstracted from a sample
of compound 36 that had not been heated in methanol, several
products were observed via 31P{1H} NMR spectroscopy. In
addition to the resonances arising from compound 35b (vide
supra), pairs of doublets are also observed at approximately δ
10 and 44, indicating the presence of other species that possess
semiopen coordination geometries at the platinum cen-
ters.68,43,44,47
resonance at δ 6.45 with corresponding 195Pt satellites (1JPt−P
=
3615 Hz), indicating that, in dichloromethane, the solution
structure resembles the solid-state structure (Figure 4a); i.e.,
two chloride ligands are coordinated to each platinum center,
and the ligands are nonchelating with a mutual cis geometry.
To stabilize the semiopen macrocycle in nonprotic solvents,
one chloride anion per platinum was abstracted from 36 using
H
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
A similar set of reactions was conducted with the
nonfluorinated ligand 15 (Scheme 8). Unlike in the case of
the fluorinated ligand, the combination of equimolar quantities
of 15 and PtCl2(cod) in dichloromethane resulted in fluxional
species as indicated by the presence of a single, very broad
signal centered at δ 14 in the 31P{1H} NMR spectrum (Scheme
8). The cod was removed by precipitation with hexanes to give
a white solid. Similar to the abstraction of chloride in the
fluorinated system, if a methanol-induced HILR reaction was
not performed, the abstraction of chloride from 38a using 2
equiv of Na[BArF] produced a mixture of species with
semiopen coordination, whereas abstraction with 4 equiv of
silver tetrafluoroborate in nitromethane produced a mixture of
complexes with fully closed coordination. This suggests that the
initial reaction in dichloromethane produces a mixture of
oligomeric and polymeric materials. However, when the initial
mixture of species was stirred in methanol at 50 °C for several
hours, subsequent abstraction reactions proceeded cleanly and
in high yields (Scheme 8). Thus, in methanol at room
temperature, two broad signals are present in the 31P{1H}
NMR spectrum at δ 45.48 (1JPt−P = 3500 Hz) and δ 10.84
(1JPt−P = 3270 Hz), indicative of a fluxional semiopen species
(38a): the signal at δ 45.48 is consistent with a chelating ligand
in which the phosphorus atom trans to a chloride, and the
signal at δ 10.84 is consistent with a nonchelating ligand in
which the phosphorus atom is trans to a phenylene thioether.
Removal of the methanol under reduced pressure produced
38a as a yellow oil that was used in subsequent reactions. The
addition of 2 equiv of Na[BArF] to a solution of 38a in
dichloromethane resulted in the clean formation of semiopen
complex 38b that could be separated from the sodium chloride
byproduct by filtration and then isolated via precipitation with
hexanes (Scheme 8). The 31P{1H} NMR spectrum recorded in
dichloromethane contains signals at δ 44.44 (1JPt−P = 3508 Hz)
and δ 9.57 (1JPt−P = 3231 Hz), which is consistent with the
proposed semiopen structure. The fully closed species 39 was
obtained from the semiopen complex 38a via the complete
abstraction of chloride using silver tetrafluoroborate or
hexafluorophosphate in nitromethane. The 31P{1H} NMR
spectrum of the tetrafluoroborate salt of 39 recorded in
nitromethane contains a single signal at δ 49.51 (1JPt−P = 3103
Hz), which is consistent with a condensed structure.68 The
structural assignments for the fully closed complexes were
confirmed by single-crystal X-ray diffraction on crystals of the
hexafluorophosphate salt (Figure 4d) and tetrafluoroborate salt
(see SI) of 39.
Another important aspect of this work is the development of a
dynamic, nontemplated synthesis of WLA macrocycles. The
formation of macrocyclic species via the inherently reversible
HILR reaction, which necessarily occurs in the presence of
halide, is a fundamentally different approach to the traditional
stepwise, templated WLA synthesis70 that must be conducted
in the absence of halide (Scheme 1a). Work toward the next
generation of air-stable enzyme mimics based on platinum(II)
WLA complexes is underway in our laboratories.
EXPERIMENTAL SECTION
■
General Methods/Instrument Details. The syntheses of
platinum(II) complexes and all manipulations were done under
ambient conditions. All solvents were anhydrous grade, purchased
from Sigma-Aldrich, and used as received. Deuterated solvents were
purchased from Cambridge Isotope Laboratories and used as received.
Compounds 10,65 11,45 12,71 13,33 15,70 and 25−2849 were prepared
according to literature procedures or adaptations thereof. All other
chemicals were purchased from Aldrich Chemical Co. and were used
as received. NMR spectra were recorded on a Bruker Avance 400 MHz
1
spectrometer. H NMR spectra were referenced internally to residual
protons in the deuterated solvents (dichloromethane-d2 = δ 5.32; 1,2-
dichloroethane-d4 = δ 3.72; nitromethane-d3 = δ 4.33; methanol-d4 =
3.31). 31P and 31P{1H} NMR spectra were referenced to an external
85% H3PO4 standard (δ 0), and 19F{1H} NMR spectra were
referenced an external CFCl3/CDCl3 standard (δ 0). Elemental
analyses were performed by Intertek Pharmaceutical Services,
Whitehouse, NJ. Electrospray ionization (ESI) mass spectra were
recorded on an Agilent 6120 LC−TOF instrument in positive ion
mode.
Synthesis. 1,4-Bis[(2-(diphenylphosphino)ethyl)thio]-2,3,5,6-tet-
rafluorobenzene (14). 2-(Diphenylphosphino)ethylthiol (500 mg,
2.03 mmol), hexafluorobenzene (120 μL, 193 mg, 1.04 mmol), cesium
carbonate (1.323 g, 4.06 mmol), and tetrabutylammonium bromide
(11 mg, 34 μmol) were dissolved in degassed tetrahydrofuran (7 mL)
and stirred under nitrogen at room temperature for 18 h. The reaction
was monitored using TLC (silica, 1:1 dichloromethane/hexanes, Rf =
0.5). The mixture was filtered through a glass frit, and the retentate
was washed with dichloromethane. The solvent was removed from the
filtrate under reduced pressure to give a crystalline off-white solid.
Column chromatography (silica, 200 mL, ϕ = 5 cm, 1:1 dichloro-
methane/hexanes, Rf = 0.5) gave compound 14 as a white crystalline
solid. Yield = 97% (632 mg, 0.990 mmol). 1H NMR (400 MHz,
CD2Cl2) δ 2.32 (m, 4H), 2.99 (m, 4H), 7.35 (m, 20H); 31P{1H} NMR
(162 MHz, CD2Cl2) δ −16.68; 19F NMR (376 MHz, CD2Cl2) δ
−134.07. Spectral data match those previously reported.69
[cis-PtCl(Ph2PCH2CH2SC6HF4-κP)(Ph2PCH2CH2SPh-κ2)][PF6] (23b).
A solution of cis-PtCl2(cod) (190 mg, 0.507 mmol) in dichloro-
methane (10 mL) was added to a solution of 10 (164 mg, 0.507
mmol) and 11 (201 mg, 0.507 mmol) in dichloromethane (5 mL) in a
50 mL oven-dried Schlenk flask. The resulting mixture was stirred
vigorously for 15 min and then concentrated to ca. 3 mL under
reduced pressure. Hexanes (50 mL) were added, and the resulting
cloudy suspension was stored at −20 °C for one hour. The suspension
was then filtered using a fritted funnel, and the white retentate was
washed with hexanes (3 × 10 mL). The retentate was dissolved in
methanol (10 mL) and stirred vigorously for 30 min. To this solution
was added a solution ammonium hexafluorophosphate (490 mg, 3.0
mmol) in methanol (3 mL). The resulting suspension was stirred
vigorously for 30 min. The mixture was filtered using a fritted funnel,
and the retentate was washed with diethyl ether (3 × 10 mL). The
retentate (23b) was dried in vacuo. Yield = 93% (506 mg, 0.463
mmol). 1H NMR (400 MHz, CD2Cl2) δ 2.77−3.09 (br m, 8H), 7.22−
7.81 (br m, 26H); 31P{1H} NMR (162 MHz, CD2Cl2) δ 9.13 (d, 2JP−P
CONCLUSIONS
■
The work described in this report effectively brings the
chemistry of the WLA out of the glovebox and onto the bench.
Over the past several years we have made a thorough study of
the WLA chemistry of rhodium(I) and used this chemistry to
develop a platform for allosteric catalysis that is both tailorable
and predictable. Nevertheless, rhodium(I)-based WLA chem-
istry is fundamentally limited in that it must be performed in
the absence of air. In contrast, the platinum(II) complexes
described in this report are stable to air and moisture and can
be synthesized with no special precautions. The ability to
synthesize heteroligated aryl−aryl platinum(II)-based WLA
complexes using a variety of hemilabile ligands not only allows
us to make all of our previously reported rhodium(I) systems
stable to air, but also allows for the exploration of new allosteric
oxidation catalysts that are incompatible with rhodium(I).
1
2
1
= 15 Hz [d, JPt−P = 3207 Hz]), 44.29 (d, JP−P = 15 Hz [d, JPt−P
=
3474 Hz]). Anal. Calcd for C40H34ClF10P3PtS2: C 43.98, H 3.14.
Found: C 43.67, H 2.79. HRMS (ESI+) m/z Calcd for [M − PF6]+:
947.0847. Found: 947.0866.
I
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
[cis-Pt(Ph2PCH2CH2SC6HF4-κ2)(Ph2PCH2CH2SPh-κ2)][PF6]2 (24). A
solution of 23b (250 mg, 0.228 mmol) in dichloromethane (15 mL)
was added to a solution of silver hexafluorophosphate (58 mg, 0.228
mmol) in dichloromethane (5 mL) in a 25 mL vial covered in
aluminum foil. The resulting mixture was stirred vigorously for 1 h and
then filtered through a Celite pad in a fritted funnel. The Celite was
washed with dichloromethane (3 × 10 mL). The filtrate was collected
and concentrated to ca. 3 mL under reduced pressure. Hexanes (50
mL) were added and the cloudy suspension was stored at −20 °C for 1
h. The suspension was filtered using a fritted funnel, and the white
retentate was washed with hexanes (3 × 10 mL). The retentate (24)
and concentrated to ca. 3 mL under reduced pressure. Hexanes (50
mL) were added, and the cloudy suspension was stored at −20 °C for
1 h. The suspension was filtered using a fritted funnel, and the
retentate was washed with hexanes (3 × 10 mL). The retentate (32)
1
was dried in vacuo. Yield = 94% (103 mg, 0.086 mmol). H NMR
(400 MHz, CD2Cl2) δ 2.69−3.13 (br m, 8H), 6.92−7.52 (br m, 35H);
2
31P{1H} NMR (162 MHz, CD2Cl2) δ 28.37 (d, JP−P = 14 Hz [d,
2
1
1JPt−P = 3279 Hz]), 32.97 (d, JP−P = 14 Hz [d, JPt−P = 3355 Hz]).
Anal. Calcd for C46H43F12NP4PtS: C 46.47, H 3.65, N 1.18. Found: C
+
46.54, H 3.39, N 1.17. HRMS (ESI+) m/z Calcd for [M − PF6] :
933.1928. Found: 933.1927.
1
was dried in vacuo. Yield = 96% (264 mg, 0.219 mmol). H NMR
[cis-Pt2Cl2(κP:μ:κP-1,4-{Ph2PCH2CH2S}2C6F4)(Ph2PCH2CH2SPh-
κ2)2][PF6]2 (33b). A solution of cis-PtCl2(cod) (234 mg, 0.626 mmol)
in dichloromethane (15 mL) was added to a solution of 10 (202 mg,
0.626 mmol) and 14 (200 mg, 0.313 mmol) in dichloromethane (10
mL) in a 50 mL oven-dried Schlenk flask. The resulting mixture was
stirred vigorously for 15 min before being concentrated to ca. 5 mL
under reduced pressure. Hexanes (50 mL) were added, and the cloudy
suspension was stored at −20 °C for 1 h. The suspension was filtered
using a fritted funnel, and the white retentate was washed with hexanes
(3 × 20 mL). The retentate was dissolved in methanol (15 mL) and
stirred vigorously for 30 min. To this solution was added a solution of
ammonium hexafluorophosphate (612 mg, 3.75 mmol) in methanol (3
mL). The resulting suspension was stirred vigorously for 30 min. The
mixture was filtered using a fritted funnel, and the retentate was
washed with diethyl ether (3 × 20 mL). The retentate (33b) was dried
(400 MHz, CD2Cl2) δ 2.72−3.09 (br m, 8H), 7.37−7.61 (br m, 26H);
2
31P{1H} NMR (162 MHz, CD2Cl2) δ 45.46 (d, JP−P = 13 Hz [d,
2
1
1JPt−P = 3087 Hz]), 46.36 (d, JP−P = 15 Hz [d, JPt−P = 3250 Hz]).
Anal. Calcd for C40H34F16P4PtS2·CH2Cl2: C 38.27, H 2.82. Found: C
38.61, H 2.64. HRMS (ESI+) m/z Calcd for [M − 2PF6 + Cl]+:
947.0847. Found: 947.0869.
[cis-PtCl(Ph2PCH2CH2OPh-κP)(Ph2PCH2CH2SPh-κ2)][PF6] (29b). A
solution of cis-PtCl2(cod) (254 mg, 0.679 mmol) in dichloromethane
(10 mL) was added to a solution of 10 (219 mg, 0.679 mmol) and 12
(208 mg, 0.679 mmol) in dichloromethane (5 mL) in a 50 mL oven-
dried Schlenk flask. The resulting mixture was stirred vigorously for 15
min and then concentrated to ca. 3 mL under reduced pressure.
Hexanes (50 mL) were added, and the cloudy suspension was stored
at −20 °C for 1 h. This suspension was filtered using a fritted funnel,
and the white retentate was washed with hexanes (3 × 10 mL). The
retentate was dissolved in methanol (10 mL) and stirred vigorously at
50 °C overnight. This solution was cooled to room temperature, and a
solution of ammonium hexafluorophosphate (1.5 g, 9.2 mmol) in
methanol (3 mL) was added. The resulting suspension was stirred
vigorously for 3 h. The mixture was filtered using a fritted funnel, and
the white retentate was washed with diethyl ether (3 × 10 mL). The
retentate (29b) was dried in vacuo. Yield = 66% (450 mg, 0.448
1
in vacuo. Yield = 97% (617 mg, 0.303 mmol). H NMR (400 MHz,
CD2Cl2) δ 2.72−2.88 (br m, 16H), 7.17−7.53 (br m, 50H); 31P{1H}
2
1
NMR (162 MHz, CD2Cl2) δ 8.39 (d, JP−P = 14 Hz [d, JPt−P = 3037
2
1
Hz]), 43.10 (d, JP−P = 14 Hz [d, JPt−P = 3479 Hz]). Anal. Calcd for
C74H66Cl2F16P6Pt2S4·CH2Cl2: C 43.08, H 3.25. Found: C 43.21, H
3.09. HRMS (ESI) m/z calcd for [M − 2(PF6)]2+: 872.0794. Found:
872.0799.
[cis-Pt2(κ2:μ:κ2-1,4-{Ph2PCH2CH2S}2C6F4)(Ph2PCH2CH2SPh-κ2)2]-
[PF6]4 (34). A solution of 33b (200 mg, 0.098 mmol) in nitromethane
(10 mL) was added to a solution of silver hexafluorophosphate (50
mg, 0.196 mmol) in nitromethane (5 mL) in a 25 mL vial covered in
aluminum foil. The resulting mixture was stirred vigorously for 1 h and
then filtered through a Celite pad in a fritted funnel. The Celite was
washed with nitromethane (3 × 10 mL). The filtrate was collected and
concentrated to ca. 3 mL under reduced pressure. Ether (50 mL) was
added, and the cloudy suspension was stored at −20 °C for 1 h. The
suspension was filtered using a fritted funnel, and the white retentate
was washed with hexanes (3 × 10 mL). The retentate (34) was dried
1
mmol). H NMR (400 MHz, CD2Cl2) δ 2.76−3.13 (br m, 6H), δ
4.38−4.42 (br m, 2H), 6.81−7.49 (br m, 30H); 31P{1H} NMR (162
MHz, CD2Cl2) δ 12.06 (d, 2JP−P = 15 Hz [d, 1JPt−P = 3200 Hz]), 44.79
2
1
(d, JP−P = 15 Hz [d, JPt−P = 3513 Hz]). Anal. Calcd for
C40H38ClF6OP3PtS·0.25CH2Cl2: C 47.14, H 3.78. Found: C 47.27,
H 3.40. HRMS (ESI+) m/z Calcd for [M − (PF6)]+: 859.1449.
Found: 859.1453.
[cis-PtCl(Ph2PCH2CH2NPh2-κP)(Ph2PCH2CH2SPh-κ2)][PF6] (30b). A
solution of cis-PtCl2(cod) (98 mg, 0.262 mmol) in dichloromethane
(10 mL) was added to a solution of 10 (85 mg, 0.262 mmol) and 13
(100 mg, 0.262 mmol) in dichloromethane (5 mL) in a 50 mL oven-
dried Schlenk flask. The resulting mixture was stirred vigorously for 15
min and then concentrated to ca. 3 mL under reduced pressure.
Hexanes (50 mL) were added, and the cloudy suspension was stored
at −20 °C for 1 h. This suspension was filtered using a fritted funnel,
and the white retentate was washed with hexanes (3 × 10 mL). The
retentate was dissolved in methanol (10 mL) and stirred vigorously for
30 min. To this solution was added a solution of ammonium
hexafluorophosphate (256 mg, 1.57 mmol) in methanol (3 mL). The
resulting suspension was stirred vigorously for 30 min. The mixture
was filtered using a fritted funnel, and the white retentate was washed
with diethyl ether (3 × 10 mL). The retentate (30b) was dried in
1
in vacuo. Yield = 93% (198 mg, 0.087 mmol). H NMR (400 MHz,
CD2Cl2) δ 2.54−3.63 (br m, 16H), 7.39−7.71 (br m, 50H); 31P{1H}
NMR (162 MHz, CD2Cl2) δ 46.76 (d, 2JP−P = 13 Hz [d, 1JPt−P = 3129
2
1
Hz]), 47.06 (d, JP−P = 13 Hz [d, JPt−P = 3229 Hz]). Anal. Calcd for
C74H66F28P8Pt2S4·2.5CH2Cl2: C 37.26, H 2.90. Found: C 37.01, H
2.80. HRMS (ESI+) m/z Calcd for [M − 4(PF6) + 2Cl]2+: 871.0810.
Found: 871.0790.
[cis-Pt2Cl2(κP:μ:κ2-1,4-{Ph2PCH2CH2S}2C6F4)2]Cl2 (35a). A solution
of cis-PtCl2(cod) (58.7 mg, 0.157 mmol) in dichloromethane (2 mL)
was added to a solution of 14 (100.3 mg, 0.157 mmol) in
dichloromethane (3 mL) in a 20 mL vial. The vial was sealed, and
the solution was stirred at room temperature for 6 h. The solution was
concentrated to ca. 0.5 mL under reduced pressure, and diethyl ether
(20 mL) was added. The resulting suspension was stirred vigorously
overnight in the sealed vial. The suspension was filtered using a fritted
funnel, and the retentate was washed with diethyl ether (3 × 10 mL).
Methanol (7 mL) was added to the retentate, and the mixture was
stirred on the frit until the retentate dissolved (15 min). The solution
was transferred to a 25 mL round-bottomed flask, and a further 8 mL
of methanol was used to wash the frit. The methanolic solutions were
combined and stirred at 40 °C for 16 h. The solution was then
concentrated to ca. 2 mL under reduced pressure, and diethyl ether
(20 mL) was added. The mixture was allowed to stand for 24 h,
resulting in the precipitation of a white, microcrystalline solid. The
mixture was filtered using a fritted funnel, and the retentate was
washed with diethyl ether (2 × 5 mL). The retentate 35a was dried in
1
vacuo. Yield = 91% (257 mg, 0.238 mmol). H NMR (400 MHz,
CD2Cl2) δ 2.56−3.84 (br m, 8H), 6.64−7.53 (br m, 35H); 31P{1H}
2
1
NMR (162 MHz, CD2Cl2) δ 6.18 (d, JP−P = 15 Hz [d, JPt−P = 3182
2
1
Hz]), 44.31 (d, JP−P = 15 Hz [d, JPt−P = 3485 Hz]). Anal. Calcd for
C46H43ClF6NP3PtS: C 51.19, H 4.02, N 1.30. Found: C 51.07, H 4.03,
N 1.19. HRMS (ESI+) m/z calcd for [M − 2PF6]2+: 872.0793. Found:
872.0802.
[cis-Pt(Ph2PCH2CH2NPh2-κ2)(Ph2PCH2CH2SCPh-κ2)][PF6]2 (32). A
solution of 30b (100 mg, 0.092 mmol) in dichloromethane (10 mL)
was added to a solution of silver hexafluorophosphate (23 mg, 0.092
mmol) in dichloromethane (5 mL) in a 25 mL vial covered in
aluminum foil. The resulting mixture was stirred vigorously for 1 h and
then filtered through a Celite pad in a fritted funnel. The Celite was
washed with dichloromethane (3 × 10 mL). The filtrate was collected
J
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
1
vacuo. Yield = 94% (131.4 mg, 73.8 μmol). H NMR (400 MHz,
CD3OD) δ 2.8−3.5 (b, 16 H), 7.28−7.62 (br m, 40H); 31P{1H} NMR
(162 MHz, CD3OD) δ 9.60 (d, 2JP−P = 11 Hz [d, 1JPt−P = 3402 Hz]),
(br s, 4F). Anal. Calcd for C68H56B4F24P4Pt2S4·2CH3NO2: C 39.35, H
2.92. Found: C 39.16, H 2.78. Satisfactory mass spectra could not be
obtained for this compound. Single crystals suitable for X-ray
diffraction studies were grown by slow liquid−liquid diffusion of
diethyl ether into a solution of 37 in nitromethane in a 5 mm NMR
tube.
44.81 (s [d, JPt−P = 3452 Hz]); 19F NMR (376 MHz, CD3OD) δ
1
−131.0 (br s). HRMS (ESI+) m/z Calcd for [M − 2Cl]2+: 869.0398.
Found: 869.0400.
[cis-Pt2Cl2(κP:μ:κ2-1,4-{Ph2PCH2CH2S}2C6F4)2][BArF]2 (35b). A sol-
ution of 35a (33.6 mg, 18.9 μmol) in methanol (3 mL) was stirred in a
20 mL vial at 50 °C for 24 h. The solution was passed through a 0.2
μm PTFE filter, and 1,2-dichloroethane (4 mL) was added to the
filtrate. The solution was concentrated under reduced pressure to ca. 3
mL, and 1,2-dichloroethane (4 mL) was added. The solution was again
concentrated under reduced pressure to ca. 3 mL and the dilution/
concentration process repeated a further two times. The solution was
then transferred to a 20 mL vial containing sodium tetrakis(3,5-
bis[trifluoromethyl]phenyl)borate (Na[BArF]) (32.9 mg, 37.1 μmol),
and the mixture was sealed and stirred at room temperature for 16 h,
resulting in a small quantity of fine, white precipitate. The suspension
was passed through a 0.2 μm PTFE filter, and the filtrate was
concentrated in vacuo to give 35b as an off-white solid. Yield = 87%
(56.1 mg, 16.2 μmol). 1H NMR (400 MHz, 1,2-C2D4Cl2) δ 2.80−3.21
(br m, 16 H), 7.18, 7.35, 7.55, 7.74 (four m, 64H in total); 31P{1H}
[cis-Pt2Cl2(κP:μ:κ2-1,4-{Ph2PCH2CH2S}2C6H4)2][BArF]2 (38b). A sol-
ution of PtCl2(cod) (132.2 mg, 0.353 mmol) in dichloromethane (10
mL) was added to a solution of 15 (200.0 mg, 0.353 mmol) in
dichloromethane (10 mL) in a 30 mL vial. The solution was stirred
under nitrogen at room temperature for 2 h. The solution was
concentrated to ca. 1 mL under reduced pressure. To the solution was
added hexanes (20 mL), and the resulting suspension was filtered
using a fritted funnel. The retentate was washed with hexanes (2 × 10
mL) and dried in vacuo. The white solid was dissolved in methanol
(10 mL) and transferred to a 30 mL vial. The methanolic solution was
stirred at 50 °C for 1 h. The methanol was removed in vacuo to give a
yellow solid, which was dissolved in nitromethane (10 mL). To the
nitromethane solution was added a solution of NaBArF (310.2 mg,
0.35 mmol) in nitromethane (5 mL), and the resulting solution was
stirred overnight. A white solid precipitated, which was removed via
filtration through a 0.2 μm PTFE filter. The filtrate was collected, and
the nitromethane was removed under reduced pressure to afford 543.2
mg of compound 38b (92%, 0.164 mmol). 1H NMR (400 MHz,
CD2Cl2) δ 7.72 (s, 16H), 7.55 (s, 8H), 7.25−7.65 (br m, 40H), 2.69−
3.17 (br m, 16H); 31P{1H} NMR (162 MHz, CD2Cl2) δ 44.44 (br s
2
1
NMR (162 MHz, 1,2-C2D4Cl2) δ 9.02 (d, JP−P = 15 Hz [d, JPt−P
=
3397.1 Hz]), 42.52 (d, JP−P = 14 Hz [d, JPt−P = 3433.5 Hz]); 19F
NMR (376 MHz, 1,2-C2D4Cl2) δ −129.79 (br s, 8F), −63.11 (s, ca.
48F). Anal. Calcd for C132H80B2Cl2F56P4Pt2S4: C 45.76, H 2.33.
Found: C 45.85, H 2.16. HRMS (ESI) m/z Calcd for [M −
2(BArF)]2+: 867.5370. Found: 867.5386. Single crystals of 35b
suitable for X-ray diffraction studies were grown by slow liquid−
liquid diffusion of n-hexane into a solution of 35b in dichloromethane
in a 5 mm NMR tube
2
1
1
1
[d, JP−Pt = 3508 Hz]), 9.57 (br s [d, JP−Pt = 3230 Hz]). Anal. Calcd
for C132H88B2Cl2F48P4Pt2S4: C 47.74, H 2.67. Found: C 47.52, H 2.30.
HRMS (ESI+) m/z Calcd for [M − (BArF)]2+: 797.0746. Found:
797.0765.
[cis-Pt2Cl4(κP:μ:κP-1,4-{Ph2PCH2CH2S}2C6F4)2] (36). Compound 36
1
[cis-Pt2(κ2:μ:κ2-1,4-{Ph2PCH2CH2S}2C6H4)2][BF4]4 (39). A solution of
PtCl2(cod) (9.2 mg, 24.6 μmol) in dichloromethane (2 mL) was
added to a solution of 15 (13.9 mg, 24.6 μmol) in dichloromethane (2
mL) in a 20 mL vial. The solution was stirred under nitrogen at room
temperature for 2 h. The solution was concentrated to ca. 0.5 mL
under reduced pressure. To the solution was added hexanes (10 mL),
and the resulting suspension was filtered using a fritted funnel. The
retentate was washed with hexanes (2 × 5 mL) and dried. The white
solid was dissolved in methanol (5 mL) and transferred to a 20 mL
vial. The methanolic solution was stirred under nitrogen at 50 °C for 1
h. The methanol was removed in vacuo to give a yellow solid, which
was dissolved in nitromethane (3 mL). The nitromethane solution was
added dropwise to a solution of silver tetrafluoroborate (9.7 mg, 49.8
μmol) in nitromethane (1 mL). The mixture was stirred under
nitrogen at room temperature, protected from light, overnight. A white
solid precipitated, which was removed via filtration through a 0.2 μm
PTFE filter. The fitrate was collected and stirred overnight with
activated carbon. The mixture was filtered, and the nitromethane was
removed from the filtrate under reduced pressure to afford 15.2 mg of
compound 39 (66%, 8.1 μmol). 1H NMR (400 MHz, CD3NO2) δ 7.6
(br m, ca. 48H), 3.55 (br s, 8H), 3.14 (br s, 8H); 31P{1H} NMR (162
was obtained by dissolving 35a in dichloromethane: H NMR (400
MHz, CD2Cl2) δ 2.55 (br s, 8H), 3.08 (br s, 8H), 7.25−7.60 (m, 40
1
H); 31P{1H} NMR (162 MHz, CD2Cl2) δ 6.48 (s [d, JPt−P = 3617
Hz]); 19F NMR (376 MHz, CD2Cl2) δ −133.66 (s). Single crystals of
36 suitable for X-ray diffraction studies were grown by slow liquid−
liquid diffusion of diethyl ether into a solution of 35a in methanol in a
5 mm NMR tube.
[cis-Pt2(κ2:μ:κ2-1,4-{Ph2PCH2CH2S}2C6F4)2][BF4]4 (37). A solution of
cis-PtCl2(cod) (59.0 mg, 0.158 mmol) in dichloromethane (2 mL) was
added to a solution of 14 (100.8 mg, 0.158 mmol) in dichloromethane
(3 mL) in a 20 mL vial, and the resulting solution was capped and
stirred at room temperature for 4 h. The solution was concentrated to
ca. 1 mL under reduced pressure, and diethyl ether (20 mL) was
added. The resulting suspension was stirred vigorously for 1 h in the
sealed vial. The suspension was filtered using a fritted funnel, and the
retentate was washed with diethyl ether (10 mL) and n-pentane (10
mL). Warm methanol (10 mL) was added to the retentate, and the
mixture was stirred on the frit until the retentate dissolved (15 min).
The solution was transferred to a 25 mL round-bottomed flask and
stirred at 40 °C for 16 h. The solution was then concentrated to ca. 1
mL under reduced pressure, and nitromethane (3 mL) was added. The
solution was concentrated to ca. 2 mL under reduced pressure, and
nitromethane (1 mL) was added. The solution was added to solid
silver tetrafluoroborate (62.8 mg, 0.323 mmol) in a 10 mL vial. The
mixture was stirred in the sealed vial at room temperature, protected
from light, for 1 h. A white solid precipitated which was removed via
filtration through a 0.2 μm PTFE filter. The filtrate was allowed to
stand in a sealed vial, protected from light, for 24 h. A brown solid
precipitated which was removed via filtration through a 0.2 μm PTFE
filter. Diethyl ether (20 mL) was added to the filtrate, and the resulting
mixture was allowed to stand at room temperature for 24 h. The
crystalline material thus formed was isolated via filtration using a
fritted funnel, washed on the frit with diethyl ether (10 mL), and dried
1
MHz, CD3NO2) δ 49.54 (s [d, JP−Pt = 3102 Hz]). Anal. Calcd for
C68H64B4F16P4Pt2S4·CH3NO2: C 42.90, H 3.50, N 0.73. Found: C
43.10 H 3.39, N 0.86. (The slight discrepancy may be due to residual
activated carbon in sample.) Satisfactory mass spectra could not be
obtained for this compound.
X-ray Crystallography. Single crystals were mounted using oil
(Infineum V8512) on a glass fiber. All measurements were made on a
CCD area detector with graphite monochromated Mo Kα or Cu Kα
radiation. Data were collected using Bruker APEXII detector and
processed using APEX2 from Bruker. All structures were solved by
direct methods and expanded using Fourier techniques. The non-
hydrogen atoms were refined anisotropically. Hydrogen atoms were
included in idealized positions, but not refined. Their positions were
constrained relative to their parent atom.
1
in vacuo. Yield = 80% (127.0 mg, 63.0 μmol). H NMR (400 MHz,
CD3NO2) δ 3.0−3.7 (br m, 16H), 7.58, 7.72 (two m, 40H in total),
3.21−2.80 (br m, 16 H); 31P{1H} NMR (162 MHz, CD3NO2) δ 51.01
(s [d, 1JPt−P = 3209 Hz]); 19F NMR (376 MHz, CD3NO2) δ −151.41
(s, 11BF4, 13B), −151.36 (s, 10BF4, 3B), −123.80 (br s, 4F), −122.70
K
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
(24) Salgado, E. N.; Radford, R. J.; Tezcan, F. A. Acc. Chem. Res.
2010, 43, 661−672.
ASSOCIATED CONTENT
* Supporting Information
NMR spectra for all compounds. Crystallographic data for
complexes 23b, 24, 29b, 30b, 33b, 34, 35b, 36, 37, and 39 (BF4
and PF6 salts) in CIF format. This material is available free of
charge via the Internet at http://pubs.acs.org.
■
S
(25) Chakrabarty, R.; Mukherjee, P. S.; Stang, P. J. Chem. Rev. 2011,
111, 6810−6918.
(26) Thomas, J. A. Dalton Trans. 2011, 40, 12005−12016.
(27) Gianneschi, N. C.; Bertin, P. A.; Nguyen, S. T.; Mirkin, C. A.;
Zakharov, L. N.; Rheingold, A. L. J. Am. Chem. Soc. 2003, 125, 10508−
10509.
AUTHOR INFORMATION
Corresponding Author
*E-mail: chadnano@northwestern.edu.
(28) Gianneschi, N. C.; Nguyen, S. T.; Mirkin, C. A. J. Am. Chem.
■
Soc. 2005, 127, 1644−1645.
(29) Oliveri, C. G.; Gianneschi, N. C.; Nguyen, S. T.; Mirkin, C. A.;
Stern, C. L.; Wawrzak, Z.; Pink, M. J. Am. Chem. Soc. 2006, 128,
16286−16296.
Author Contributions
†These authors contributed equally to this work.
(30) Yoon, H. J.; Heo, J.; Mirkin, C. A. J. Am. Chem. Soc. 2007, 129,
14182−14183.
Notes
(31) Yoon, H. J.; Mirkin, C. A. J. Am. Chem. Soc. 2008, 130, 11590−
11591.
The authors declare no competing financial interest.
(32) Ulmann, P. A.; Braunschweig, A. B.; Lee, O.-S.; Wiester, M. J.;
Schatz, G. C.; Mirkin, C. A. Chem. Commun. 2009, 5121−5123.
(33) Yoon, H. J.; Kuwabara, J.; Kim, J.-H.; Mirkin, C. A. Science 2010,
330, 66−69.
ACKNOWLEDGMENTS
■
This material is based upon work supported by the DoD/
NSSEFF/NPS Awards N00244-09-1-0012 and N00244-09-1-
0071, U.S. Army Grant W911NF-11-1-0229, and NSF Award
CHE-1149314. Any opinions, findings, and conclusions or
recommendations expressed in this publication are those of the
authors and do not necessarily reflect the views of the sponsors.
(34) Rogers, C. W.; Wolf, M. O. Coord. Chem. Rev. 2002, 233−234,
341−350.
(35) Kovbasyuk, L.; Kramer, R. Chem. Rev. 2004, 104, 3161−3188.
(36) Stoll, R. S.; Hecht, S. Angew. Chem., Int. Ed. 2010, 49, 5054−
5075.
(37) Coskun, A.; Banaszak, M.; Astumian, R. D.; Stoddart, J. F.;
Grzybowski, B. A. Chem. Soc. Rev. 2012, 41, 19−30.
(38) Jeffrey, J. C.; Rauchfuss, T. B. Inorg. Chem. 1979, 18, 2658−
2666.
(39) Braunstein, P. J. Organomet. Chem. 2004, 689, 3953−3967.
(40) van der Vlugt, J. I. Eur. J. Inorg. Chem. 2012, 2012, 363−375.
(41) Bassetti, M. Eur. J. Inorg. Chem. 2006, 2006, 4473−4482.
(42) Brown, A. M.; Ovchinnikov, M. V.; Stern, C. L.; Mirkin, C. A. J.
Am. Chem. Soc. 2004, 126, 14316−14317.
(43) Spokoyny, A. M.; Rosen, M. S.; Ulmann, P. A.; Stern, C.;
Mirkin, C. A. Inorg. Chem. 2010, 49, 1577−1586.
(44) Rosen, M. S.; Spokoyny, A. M.; Machan, C. W.; Stern, C. L.;
Sarjeant, A. A.; Mirkin, C. A. Inorg. Chem. 2011, 50, 1411−1419.
(45) Brown, A. M.; Ovchinnikov, M. V.; Mirkin, C. A. Angew. Chem.,
Int. Ed. 2005, 44, 4207−4209.
(46) Ulmann, P. A.; Mirkin, C. A.; DiPasquale, A. G.; Liable-Sands, L.
M.; Rheingold, A. L. Organometallics 2009, 28, 1068−1074.
(47) Ulmann, P. A.; Brown, A. M.; Ovchinnikov, M. V.; Mirkin, C.
A.; DiPasquale, A. G.; Rheingold, A. L. Chem.Eur. J. 2007, 13,
4529−4534.
(48) Machan, C. W.; Spokoyny, A. M.; Jones, M. R.; Sarjeant, A. A.;
Stern, C. L.; Mirkin, C. A. J. Am. Chem. Soc. 2011, 133, 3023−3033.
(49) Spokoyny, A. M.; Machan, C. W.; Clingerman, D. J.; Rosen, M.
S.; Wiester, M. J.; Kennedy, R. D.; Sarjeant, A. A.; Stern, C. L.; Mirkin,
C. A. Nat. Chem. 2011, 3, 590−596.
(50) Machan, C. W.; Lifschitz, A. M.; Stern, C. L.; Sarjeant, A. A.;
Mirkin, C. A. Angew. Chem., Int. Ed. 2012, 51, 1469−1472.
(51) Langille, K. R.; Peach, M. E. J. Fluorine Chem. 1972, 1, 407−414.
(52) Peach, M. E.; Smith, A. M. J. Fluorine Chem. 1974, 4, 399−408.
(53) Anderson, G. K.; Cross, R. J. Chem. Soc. Rev. 1980, 9, 185−215.
(54) Issleib, K.; Gans, W. Z. Anorg. Allg. Chem. 1981, 475, 116−130.
(55) Sanger, A. Can. J. Chem. 1982, 61, 2214−2219.
(56) Anderson, G. K.; Kumar, R. Inorg. Chem. 1984, 23, 4064−4068.
(57) Anderson, G. K.; Lumetta, G. J. Organometallics 1985, 4, 1542−
1545.
REFERENCES
■
(1) Farrell, J. R.; Mirkin, C. A.; Guzei, I. A.; Liable-Sands, L. M.;
Rheingold, A. L. Angew. Chem., Int. Ed. 1998, 37, 465−467.
(2) Holliday, B. J.; Mirkin, C. A. Angew. Chem., Int. Ed. 2001, 40,
2022−2043.
(3) Gianneschi, N. C.; Masar, M. S.; Mirkin, C. A. Acc. Chem. Res.
2005, 38, 825−837.
(4) Slone, C. S.; Weinberger, D. A.; Mirkin, C. A. In Progress in
Inorganic Chemistry; Karlin, K. D., Ed.; John Wiley & Sons, Inc.:
Hoboken, NJ, 1999; pp 233−350.
(5) Oliveri, C. G.; Ulmann, P. A.; Wiester, M. J.; Mirkin, C. A. Acc.
Chem. Res. 2008, 41, 1618−1629.
(6) Wiester, M. J.; Ulmann, P. A.; Mirkin, C. A. Angew. Chem., Int. Ed.
2011, 50, 114−137.
(7) Albrecht, M. Chem. Soc. Rev. 1998, 27, 281−288.
(8) Stoddart, J. F. Chem. Soc. Rev. 2009, 38, 1521−1529.
(9) Faiz, J. A.; Heitz, V.; Sauvage, J.-P. Chem. Soc. Rev. 2009, 38,
422−442.
(10) Fiedler, D.; Leung, D. H.; Bergman, R. G.; Raymond, K. N. Acc.
Chem. Res. 2004, 38, 349−358.
(11) Flamigni, L.; Collin, J.-P.; Sauvage, J.-P. Acc. Chem. Res. 2008,
41, 857−871.
(12) Fujita, M. Chem. Soc. Rev. 1998, 27, 417−425.
(13) Sauvage, J.-P. Acc. Chem. Res. 1998, 31, 611−619.
(14) Fuiita, M. In Molecular Self-Assembly Organic Versus Inorganic
Approaches; Fuiita, M., Ed.; Springer: Berlin, 2000; Vol. 96, pp 177−
201.
(15) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. Rev. 2000, 100,
853−908.
(16) Seidel, S. R.; Stang, P. J. Acc. Chem. Res. 2002, 35, 972−983.
(17) Wurthner, F.; You, C.-C.; Saha-Moller, C. R. Chem. Soc. Rev.
2004, 33, 133−146.
(18) Schmittel, M.; Kalsani, V. In Functional Molecular Nanostruc-
tures; Schluter, A. D., Ed.; Springer: Berlin, 2005; Vol. 245, pp 1−53.
̈
(19) Amijs, C. H. M.; van Klink, G. P. M.; van Koten, G. Dalton
Trans. 2006, 308−327.
(58) Anderson, G. K.; Corey, E. R.; Kumar, R. Inorg. Chem. 1987, 26,
97−100.
(20) Kay, E. R.; Leigh, D. A.; Zerbetto, F. Angew. Chem., Int. Ed.
2007, 46, 72−191.
(59) Habtemariam, A.; Sadler, P. J. Chem. Commun. 1996, 1785−
1786.
(21) Lee, S. J.; Lin, W. Acc. Chem. Res. 2008, 41, 521−537.
(22) Spokoyny, A. M.; Kim, D.; Sumrein, A.; Mirkin, C. A. Chem. Soc.
Rev. 2009, 38, 1218−1227.
(60) Hou, D.-R.; Lin, T.-C.; Hsieh, T.-Y.; Cheng, M.-C.; Peng, S.-M.;
Liu, S.-T. Phosphorus Sulfur 1996, 108, 61−73.
(61) Margiotta, N.; Habtemariam, A.; Sadler, P. J. Angew. Chem., Int.
Ed. 1997, 36, 1185−1187.
(23) Klosterman, J. K.; Yamauchi, Y.; Fujita, M. Chem. Soc. Rev. 2009,
38, 1714−1725.
L
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
(62) Armstrong, S. K.; Cross, R. J.; Farrugia, L. J.; Nichols, D. A.;
Perry, A. Eur. J. Inorg. Chem. 2002, 141−151.
(63) Romeo, R.; Scolaro, L. M.; Plutino, M. R.; Romeo, A.; Nicolo’,
F.; Zotto, A. D. Eur. J. Inorg. Chem. 2002, 2002, 629−638.
(64) Basolo, F.; Johnson, R. C. Coordination Chemistry: The Chemistry
of Metal Complexes; W. A. Benjamin, Inc.: New York, 1964.
(65) Wiester, M. J.; Braunschweig, A. B.; Mirkin, C. A. Inorg. Chem.
2010, 49, 7188−7196.
(66) Macchioni, A. Chem. Rev. 2005, 105, 2039−2074.
(67) Burgess, J.; Hubbard, C. D. In Advances in Inorganic Chemistry:
Including Bioinorganic Studies; Van Eldik, R., Hubbard, C. D., Eds.;
Elsevier Academic Press, Inc.: San Diego, CA, 2003; Vol. 54, pp 71−
155.
(68) Garrou, P. E. Chem. Rev. 1981, 81, 229−266.
(69) Ovchinnikov, M. V.; Holliday, B. J.; Mirkin, C. A.; Zakharov, L.
N.; Rheingold, A. L. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 4927−4931.
(70) Dixon, F. M.; Eisenberg, A. H.; Farrell, J. R.; Mirkin, C. A.;
Liable-Sands, L. M.; Rheingold, A. L. Inorg. Chem. 2000, 39, 3432−
3433.
(71) Singewald, E. T.; Mirkin, C. A.; Levy, A. D.; Stern, C. L. Angew.
Chem., Int. Ed. 1995, 33, 2473−2475.
M
dx.doi.org/10.1021/ic302855f | Inorg. Chem. XXXX, XXX, XXX−XXX