Two-electron redox chemistry at the dinuclear core of a TePt platform: Chlorine photoreductive elimination and isolation of a TeVPt I complex

Article abstract of DOI:10.1021/ja3046074

As part of our interest in novel redox-active main group/transition metal platforms for energy applications, we have synthesized the chloride salt of [Te^IIIPt^ICl(o-dppp)₂]⁺ ([1] ⁺, o-dppp = o-(Ph₂P)C₆H₄) by reaction of the new bis(phosphino) telluroether (o-(Ph₂P)C ₆H₄)₂Te with (Et₂S) ₂PtCl₂. Complex [1]⁺ is chemically robust and undergoes a clean two-electron oxidation reaction in the presence of PhICl ₂ to afford ClTe^IIIPt^IIICl₃(o-dppp) ₂ (2), a complex combining a hypervalent four-coordinate tellurium atom and an octahedral platinum center. While the Te-Pt bond length is only slightly affected by the oxidation state of the TePt platform, DFT and NBO calculations show that this central linkage undergoes an umpolung from Te→Pt in [1]⁺ to Te←Pt in 2. This umpolung signals an increase in the electron releasing ability of the tellurium center upon switching from an eight-electron configuration in [1]⁺ to a hypervalent configuration in 2. Remarkably, the two-electron redox chemistry displayed by this new dinuclear platform is reversible as shown by the photoreductive elimination of a Cl₂ equivalent when 2 is irradiated at 350 nm in the presence of a radical trap such as 2,3-dimethyl-1,3-butadiene. This photoreductive elimination, which affords [1][Cl] with a maximum quantum yield of 4.4%, shows that main group/late transition metal complexes can mimic the behavior of their transition metal-only analogues and, in particular, undergo halogen photoelimination from the oxidized state. A last notable outcome of this study is the isolation and characterization of F(MeO) ₂Te^VPt^ICl(o-dppp)₂ (4), the first metalated hexavalent tellurium compound, which is formed by reaction of 2 with KF in the presence of MeOH.

Full text of DOI:10.1021/ja3046074

Article
pubs.acs.org/JACS
Two-Electron Redox Chemistry at the Dinuclear Core of a TePt
Platform: Chlorine Photoreductive Elimination and Isolation
of a TeVPtI Complex
Tzu-Pin Lin and Franco̧ is P. Gabbaï*
Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
S
* Supporting Information
ABSTRACT: As part of our interest in novel redox-active main
group/transition metal platforms for energy applications, we
have synthesized the chloride salt of [TeIIIPtICl(o-dppp)2]+
([1]+, o-dppp = o-(Ph2P)C6H4) by reaction of the new bis-
(phosphino) telluroether (o-(Ph2P)C6H4)2Te with
(Et2S)2PtCl2. Complex [1]+ is chemically robust and undergoes
a clean two-electron oxidation reaction in the presence of
PhICl2 to afford ClTeIIIPtIIICl3(o-dppp)2 (2), a complex com-
bining a hypervalent four-coordinate tellurium atom and an
octahedral platinum center. While the Te−Pt bond length is
only slightly affected by the oxidation state of the TePt platform,
DFT and NBO calculations show that this central linkage
undergoes an umpolung from Te→Pt in [1]+ to Te←Pt in 2. This umpolung signals an increase in the electron releasing ability of
the tellurium center upon switching from an eight-electron configuration in [1]+ to a hypervalent configuration in 2. Remarkably,
the two-electron redox chemistry displayed by this new dinuclear platform is reversible as shown by the photoreductive elimination
of a Cl2 equivalent when 2 is irradiated at 350 nm in the presence of a radical trap such as 2,3-dimethyl-1,3-butadiene. This photo-
reductive elimination, which affords [1][Cl] with a maximum quantum yield of 4.4%, shows that main group/late transition metal
complexes can mimic the behavior of their transition metal-only analogues and, in particular, undergo halogen photoelimination
from the oxidized state. A last notable outcome of this study is the isolation and characterization of F(MeO)2TeVPtICl(o-dppp)2
(4), the first metalated hexavalent tellurium compound, which is formed by reaction of 2 with KF in the presence of MeOH.
Chart 1. Two-Electron Redox Processes in Selected Dinuclear
Complexes
INTRODUCTION
■
Dinuclear complexes which feature two non-bonded electron-
rich elements in close proximity are typically prone to two-
electron oxidation reactions.1 These reactions are facilitated by
(i) electron−electron repulsions which destabilize the reduced
form and (ii) formation of a covalent element−element bond
which stabilizes the oxidized form. This descriptor is general and
can be employed to account for the behavior of numerous
dinuclear compounds including main group and transition metal
derivatives. Examples of such dinuclear main group complexes
include dichalcogenide derivatives in which the two group 16
elements are held in close proximity within cyclic structures and/
or using rigid linkers.1a,b An example of such a compound is
1,5-ditelluracyclooctane (A, Chart 1), a compound that under-
goes a facile two-electron oxidation reaction with halogen to
afford the corresponding TeIIITeIII ditellurane.1c,d Remarkably,
these oxidation reactions are chemically reversible as in the case
of [TeI(CH2)3]2 which undergoes reduction when treated with
PhSH.2 This reversible two-electron redox chemistry bears a
strong similarity with that observed for dinuclear late transition
metal complexes including A-frame AuIAuI complexes such as
[Au(CH2)2PPh2]2 (B, Chart 1).1e Indeed, analogously to the
tellurium systems, these complexes react with halogens to afford
AuIIAuII complexes.1f,g These systems also react with alkyl halides
such as MeBr.1h In this case, the oxidative addition can be reversed
by simple elevation of the temperature or by UV irradiation.
Received: May 11, 2012
Published: June 18, 2012
© 2012 American Chemical Society
12230
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238

Journal of the American Chemical Society
Article
The reversibility of these reactions and in particular the
thermal or light activation of strong metal−halide bond is an
important phenomenon because it provides a pathway for the
regeneration of the reduced and thus reactive form of the
complex. As previously shown, such reduction reactions are also
of relevance to the photocatalytic production of H2 from HX
molecules (X = halogen) and dinuclear transition metal
catalysts.3 In the context of this last application, the Nocera
group has recently surveyed several complexes and found that X2
photoelimination reactions can be sustained by a variety of late
transition metal binulcear complexes4 including AuPt complexes
(C, Chart 1).5
(ii) a 125Te NMR signal at 1023 ppm split into a triplet (JTe‑P = 62
Hz) and flanked by 195Pt satellites (1JTe‑Pt = 649 Hz). These
spectroscopic features, and in particular the observed P−Pt and
Te−Pt coupling, indicate coordination of the tellurium and
phosphorus atoms to the platinum center. This coordination
mode is confirmed by the crystal structure of this complex which
features a platinum center in a distorted square planar geometry
(P(1)−Pt−P(2) = 168.19(4)°, Te−Pt−Cl(1) = 175.33(3)°)
(Figure 1). The tellurium atom is coordinated to the platinum
Because of the analogy that exists between the redox prop-
erties of dinuclear gold and tellurium complexes as illustrated in
Chart 1, it occurred to us that heteronuclear complexes
combining tellurium and a late transition metal element may
also sustain reversible two-electron redox chemistry. In pursuit of
this idea, we have decided to explore the synthesis and redox
properties of TePt complexes (D, Chart 1). In this article, we
describe the synthesis and characterization of such complexes.
We also show that such complexes display unusual redox prop-
erties and in particular support the addition and photoreductive
elimination of a X2 equivalent. Another important aspect of this
article is the synthesis and characterization of the first tellur-
oxanyl-metal complex.
Figure 1. Left: Solid-state structure of [1][Cl]. Thermal ellipsoids are
drawn at the 50% probability level. Phenyl groups are drawn in
wireframe. Hydrogen atoms and solvent molecules are omitted for
clarity. Pertinent metrical parameters can be found in the text. Right:
NLMO plot (isovalue = 0.05) of the Te−Pt bond in [1]+ obtained from
NBO analysis. Hydrogen atoms are omitted for clarity.
RESULTS AND DISCUSSION
■
Synthesis and Characterization of a TeIIIPtI ([1]+) and
TeIIIPtIII Complex (2). We have recently observed that late
transition metal complexes featuring the triphosphanylstibine
ligand [(o-(Ph2P)C6H4)3Sb] are structurally robust and can, in
some cases, sustain reversible redox reactions.6 Encouraged by
these observations, we targeted the tellurium analogue, namely
[(o-(Ph2P)C6H4)2Te], which could be conveniently prepared by
treatment of o-lithio-diphenylphosphinobenzene with TeCl4.
Reaction of [(o-(Ph2P)C6H4)2Te] with (Et2S)2PtCl2 afforded
the cationic complex [1]+ as a chloride salt (Scheme 1). This
center via a Te−Pt bond of 2.5281(5) Å which is comparable to
the value of 2.5747(6) Å observed in the dicationic complex
[Pt{(o-PPh2C6H4)TePh}2]2+.7 A further examination of the
structure indicates that the chloride counteranion is weakly
interacting with the tellurium center (Te−Cl(2) = 3.1759(12) Å).
The Te−Cl(2) separation exceeds the sum of the covalent radii
by almost 0.8 Å,8 leading us to describe this compound as the ion-
paired salt [1][Cl]. By analogy with formal oxidation state
assignments in dinuclear transition metal complexes such as
those shown in Chart 1, we describe [1]+ on the basis of two
resonance structures that correspond to a TeIIIPtI and TeIIPtII
complex, respectively (resonance forms a and b, Scheme 1). A
consistent formalism is used to describe the other compounds
reported in this study.9
Scheme 1. Synthesis of [1][Cl] and 2
With this new compound in hand, we decided to investigate its
oxidation. Reaction of [1][Cl] with PhICl2 afforded complex 2 as
a yellow solid. The 31P NMR spectrum of 2 displays a singlet at
26.5 ppm featuring 195Pt and 125Te satellites (1JPt‑P = 1777 Hz,
J
Te‑P = 86 Hz). When compared to [1][Cl] (1JPt‑P = 2480 Hz), the
1JPt‑P value of 2 appears to be notably reduced, a phenomenon
that is commonly observed for phosphine−platinum complexes
upon oxidation.10 The 125Te NMR signal of 2 at 1217 ppm is split
into a triplet by coupling to phosphorus (JTe‑P = 86 Hz). This
signal is also coupled to the 195Pt nucleus via a coupling constant
(1JTe‑Pt) of 1112 Hz which is larger than that measured for
[1][Cl] (1JTe‑Pt = 649 Hz). Since platinum oxidation typically
leads to a decrease in coupling constants,11 we propose that the
larger coupling in 2 illustrates a stabilization of the Te−Pt linkage
caused by the enhanced donicity of the tellurium atom toward
platinum. A final assignment of this structure was derived from a
single-crystal X-ray diffraction analysis (Figure 2). While the
basic features of the central TePt dinuclear core of 2 including
the Te−Pt bond distance (2.6349(7) Å) are analogous to those
in [1][Cl] (2.5281(5) Å), inspection of the coordination sphere
of the platinum center indicates oxidative addition of a Cl2
molecule, leading to a TeIIIPtIII complex. As a result, the platinum
complex gives rise to (i) a 31P NMR signal at 42.5 ppm with 195Pt
and 125Te satellites (1JPt‑P = 2480 Hz, JTe‑P = 62 Hz) and
12231
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238

Journal of the American Chemical Society
Article
in agreement with the description of the bond as a classical Te→Pt
coordination bond. The polarization of the bonding pair in [1]+
can be reconciled by considering the partial contribution of a
TeIIPtII resonance form (form b, Scheme 1) to the electronic
structure of the molecule.9a By contrast, the bonding pair in 2
features a notably larger orbital contribution from the platinum
atom (Te, 35%/Pt, 63%), indicating an umpolung of the Pt−Te
bonding pair from Te→Pt in [1]+ to Te←Pt in 2. Such a bond
umpolung is not unprecedented and is reminiscent of that
observed at the dinuclear core of related AuSb complexes6 upon
oxidation.19 Additional insights into the electronic structure of 2
can be derived from an inspection of the natural charges (Te
0.93, Pt 0.03 in [1]+ and Te 1.23, Pt 0.29 in 2; see SI) which
suggests that oxidation affects both central atoms. These NBO
results, including the Pt−Te bond umpolung, indicate that both
the TeIIIPtIII (form a, Scheme 1) and TeIVPtII (form b, Scheme 1)
resonance forms make important contributions to the electronic
structure of 2. We also note that resonance form b corresponds
to a telluronium-platinate species in which the telluronium ion is
poised to act as a σ-acceptor or Z-ligand.9b,c,20 The implication of
tetravalent tellurium species as Z-ligands is not unprecedented
and has been advanced once before in the case of [(CO)5Mn→
TeCl4]−, a complex prepared by reaction of the metalloanion
[(CO)5Mn]− with TeCl4.21
Figure 2. Left: Solid-state structure of 2. Thermal ellipsoids are drawn at
the 50% probability level. Phenyl groups are drawn in wireframe.
Hydrogen atoms and solvent molecules are omitted for clarity. Pertinent
metrical parameters can be found in the text. Right: NLMO plot
(isovalue = 0.05) of the Te−Pt bond in 2 obtained from NBO analysis.
Hydrogen atoms are omitted for clarity.
atom adopts an octahedral geometry characteristic of the
tetravalent state and with only small angular distortions
(Cl(1)−Pt−Te = 171.90(6)°, Cl(2)−Pt−P(1) = 168.26(9)°,
Cl(3)−Pt−P(2) = 168.76(8)°). It is interesting to note that the
bond distance of 2.451(2) Å separating the platinum atom and
the chlorine atom (Cl(1)) trans from the tellurium atom is
slightly longer than the Pt−Cl bond distances involving the
chlorine atoms trans from the phosphino ligands (Pt−Cl(2) =
2.396(2) Å and Pt−Cl(3) = 2.388(2) Å). This noticeable
difference suggests that the tellurium ligand is a stronger σ-donor
than the diphenylphosphino ligands. It could be argued that
oxidation only affects the platinum center of this complex.
However, changes are also observed in the coordination sphere
of the tellurium center with, in particular, a drastic shortening of
the Te−Cl(2) bond from 3.1759(12) Å in [1][Cl] to 2.712(3) Å
in 2. With this new chlorine ligand in its coordination sphere, the
tellurium atom is four-coordinate and adopts a seesaw geometry
(Pt−Te−Cl(4) = 178.83(6)° and C(1)−Te−C(19) = 96.4(3)°)
reminiscent of that displayed by compounds such as TePh2Cl2.
This analogy is reinforced by the fact that the Te−Cl bond
distance in 2 approaches that determined for TePh2Cl2 (2.51 Å).12
Thus, complex 2 represents a rare example of a transition metal
complex bearing a tetravalent, four-coordinate tellurium atom13
as opposed to a telluroether ligand.11,14 The closest analogue of 2
is a complex (E) isolated by Puddephat et al. by reaction of
Ph2TeCl2 with [PtMe2(bu2bpy)] (bu2bpy = 4,4′-di-tert-butyl-
2,2′-bipyridine).15 This complex features a Pt−Te bond (2.57 Å)
of length comparable to that found in 2. Unlike
in 2, the tellurium center of E is best described as three-
coordinate, with the chloride ligand forming only a very weak
contact of 3.43 Å.
Photoreductive Elimination of Cl2 from the TeIIIPtIII
complex 2. As described in the Introduction, the photo-
activation of metal−halide bonds is an important process because
of its possible implication in catalytic cycles including those for
the production of solar fuels.3 While a significant amount of
knowledge has been accumulated for the occurrence of such
reactions at the core of transition metal-only bimetallic com-
plexes, dinuclear complexes that combine a main group and
transition metal element in their core have never been shown to
support such photochemical processes. Bearing in mind that the
presence of a main group element at the core of this dinuclear
complexes could ultimately result in lower catalyst cost, we
decided to determine if 2 could undergo elimination of a Cl2 equi-
valent under photolytic conditions. Before testing this hypothesis,
the optimized structure of 2 was subjected to a time-dependent
density functional theory (TD-DFT) calculation (functional,
MPW1PW91; mixed basis set: Te/Pt, aug-cc-pVTZ-PP; P/Cl,
6-31g(d); C/H, 6-31g) using the SMD implicit solvation model
with CH2Cl2 as a solvent.22 As shown in Figure 3a, the simulated
absorption spectrumnicely matchestheexperimentalone(CH2Cl2)
thus pointing to the adequacy of this method. As suggested by the
TD-DFT calculations, the low energy band centered at 350 nm
(25 600 M−1 cm−1) originates from electronic transitions from filled
orbitals to both LUMO and LUMO+1 (see SI). Examination of
these two orbitals (Figure 3b) reveals a set of eg*-like orbitals which
are separated by only 0.003 eV in energy. These orbitals bear
significant Te−Cl and Pt−Cl antibonding characters, suggesting that
irradiation of the complex at 350 nm may induce chlorine atom
dissociation not only from platinum but also possibly from tellurium.
To investigate this possibility, a solution of 2 in CH2Cl2
containing 2,3-dimethyl-1,3-butadiene (DMBD) as a radical trap
was irradiated with 350 nm light. Such conditions have been
previously employed by Nocera and were thus selected to allow
for a facile comparison of our results with existing ones.4 As
shown in Figure 4, the absorption band at 350 nm decreases with
increasing irradiation times. These spectral changes are assigned
to the photochemical conversion of 2 into [1][Cl], a
phenomenon which is consistent with the 31P NMR observation
of [1][Cl] as the sole phosphorus-containing species when the
To understand how the nature of the Te−Pt bond is affected
by oxidation, the structures of [1]+ and 2 have also been studied
computationally using the Gaussian program16 (functional,
BP86;17 mixed basis sets: Te/Pt, aug-cc-pVTZ-PP; P/Cl, 6-
31g(d); C/H, 6-31g).18 The resulting structures, which are in
excellent agreement with those determined experimentally (see SI),
were subjected to a Natural Bond Orbital analysis. This analysis
reveals that the Pt−Te bonding pair in [1]+ bears a larger orbital
contribution from tellurium than platinum (Te, 57%/Pt, 39%),
12232
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238

Journal of the American Chemical Society
Article
This quantum yield moderately increases at higher DMBD
concentration to reach a maximum value of 4.4% (at [DMBD] =
3.31 M). The quantum yield measured for the conversion of 2 into
[1][Cl] is comparable to that measured for the AuPt system
(C, Chart 1) reported by the Nocera group.5 The photoreduction of
2 is, however, not as efficient as that of the diplatinum complex
Pt2(tfepma)2Cl6 (tfepma = {(CF3CH2O)2P}2NCH3) which
approaches a quantum efficiency of almost 40% at high DMBD
concentrations.4c We also note that when 2 is photolyzed in the
absence of a radical trap, formation of unidentified photoproducts
slowly occurs thus pointing to the chemical vulnerability of the
ligand system employed in our study.
The Buffering Role of Tellurium. The umpolung of the
Te−Pt bond observed during the conversion of [1][Cl] into 2
also signifies a greater extent of σ-donation from the tellurium to
the platinum atom upon oxidation. Thus, the tellurium atom acts
as an electron reservoir which can alleviate, through increased
σ-donation, the electron deficiency caused by oxidative addition
of Cl2. This effect indicates that the two heavy atoms are
electronically intimate and operate in a unique synergic fashion.
Crucial to the ability of tellurium to donate more extensively
to platinum is also the ability of tellurium to accept a chloride
anion as an inner sphere ligand trans from the platinum atom
(Figure 5). Thus, the tellurium atom and its compatibility with a
Figure 3. (a) Experimental (CH2Cl2) and calculated ultraviolet−visible
spectra for 2. The calculated spectra were obtained by TD-DFT
calculations using the MPW1PW91 functional and a mixed basis set
(simulated peak half-width = 0.25 eV). In addition to the simulated
spectrum, the computed excitations are shown as thin lines with heights
proportional to the calculated oscillator strengths. The excitations
labeled as Ea and Eb are the main contributors to the low-energy
absorption band observed in the absorption spectrum of 2. A total of
80 singlet excited states were calculated. (b) Plots of the LUMO
(−0.092 eV) and LUMO+1 (−0.089 eV) of 2 (at 0.03 isosurface value).
Figure 5. Schematic drawing showing how coordination of a chloride
ligand to the tellurium atom serves to modulate the σ-donating prop-
erties of the tellurium atom toward the transition metal fragment [M].
hypervalent configuration serves as a relay for a “chloride-push/
platinum-pull” effect that allows for a greater degree of electron-
pair transfer to the platinum center. The reversibility of the
reaction and the photoconversion of 2 into [1][Cl] shows that
the tellurium atom can step back its donation toward the
platinum atom upon photoreduction. Thus, the tellurium atom
functions as an electron reservoir that can modulate the electron
density of the neighboring platinum atom. We suggest that this
buffering effect facilitates, if not enables, the reversibility of the
two-electron redox chemistry sustained by this TePt platform.
Reaction of the TeIIIPtIII Complex 2 with Other Halides:
Isolation of a TeVPtI Complex. Having established that 2 can
be efficiently photoreduced, albeit in the presence of a radical
trap, we decided to investigate its stability upon exchange of the
chloride ligands with other halides. While 2 underwent partial
halide exchange when mixed with NaBr in MeOH, we observed
the occurrence of a rapid reaction when NaI was employed. This
reduction reaction leads to the formation of [3][I3], a salt
containing the iodo analogue of [1]+ (Scheme 2). Accordingly,
the 1H, 13C, 31P, and 125Te NMR spectroscopic features of [3]+
are close to those of [1]+. We will note, in particular, the
similarity of the 31P (42.5 ppm for [1]+ vs 37.5 ppm for [3]+) and
125Te NMR chemical shifts (1023 ppm for [1]+ vs 1018 ppm for
Figure 4. Absorption spectra () obtained from the photolysis reaction
of 2 in CH2Cl2 (2.65 × 10−5 M) with monochromatic 350 nm light in
the presence of 2,3-dimethyl-1,3-butadiene (0.29 M). The final
spectrum (---) is identical to that of [1][Cl]. The inset shows the
correlation between the quantum yield and DMBD concentration.
photolysis is carried out in an NMR tube (see SI). GC-MS
analysis of the resulting solution also reveals the formation of
chlorinated DMBD derivatives referred to as DMBD“Cl2” (see
SI). To assess the efficiency of this photoreduction, quantum
yield measurements were carried out. At a DMBD concentration
of 0.29 M, a quantum yield of 3.0% can be determined using
freshly prepared potassium ferrioxalate as a standard actinometer.23
[3]+) which are also coupled by comparable constants (1JTe‑Pt
=
649 Hz for [1]+ vs 1JTe‑Pt = 542 Hz for [3]+). The crystal structure
of [3][I3] (see SI), confirms its ionic nature, with the [I3]− anion
12233
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238

Journal of the American Chemical Society
Article
a
measured in 4 is much larger than that observed for [1][Cl]
(1JTe‑Pt = 649 Hz) and 2 (1JTe‑Pt = 1112 Hz), a phenomenon that
we assign to the greater covalent character of the Pt−Te bond
Scheme 2. Synthesis of [3][I3] and 4
1
(vide infra). Lastly, the H NMR spectrum of 4 features a
resonance at 2.77 ppm coupled to 19F (4JH‑F = 1.49 Hz) and 125Te
(3JH‑Te = 51.47 Hz) and can be assigned to two tellurium-bound
methoxy groups.
The structure of this new derivative was confirmed by a single-
crystal X-ray diffraction analysis which shows that 4 is a TeVPtI
complex9a featuring a telluroxanyl ligand (Figure 7). The
a
Only one resonance structucture is shown for [3]+. A PtIITeII
resonance form is also relevant.
well separated from [3]+. The structure of the latter is close to
that of [1]+ as indicated by the similarities observed in the Te−Pt
distances (2.5163(11) Å in [3]+ vs 2.5281(5) Å in [1]+) as well as
the Te−Pt−X (173.54(4)° in [3]+ vs 175.33(3)° in [1]+) and P−
Pt−P (162.84(14)° in [3]+ vs 168.19(4)° in [1]+) angles.
Formation of this compound indicates that iodide can be used to
reduce the complex by two electrons, a process also driven by the
formation of [I3]− anion.
Having tested the behavior of 2 toward bromide and iodide, we
turned our attention toward the lighter halide, namely fluoride.
Reaction 2 with KF in THF/MeOH (v/v = 8/2) led to the
formation of a new compound (4) which features a singlet 19F
resonance at −58.7 ppm (Figure 6) flanked by a set of 125Te
Figure 7. Left: Solid-state structure of 4. Thermal ellipsoids are drawn at
the 50% probability level. Phenyl groups are drawn in wireframe.
Hydrogen atoms and solvent molecules are omitted for clarity. Pertinent
metrical parameters can be found in the text. Right: NLMO plot
(isovalue = 0.05) of the Te−Pt bond in 4 obtained from NBO analysis.
Hydrogen atoms are omitted for clarity.
structure of this complex is characterized by (i) a tellurium
center in a distorted octahedral geometry as indicated by the Pt−
Te−F, O(1)−Te−O(2), and C(1)−Te−C(19) angles of
178.75(6)°, 163.78(11)°, and 165.04(14)°, respectively, and
(ii) a platinum center in a square planar geometry as indicated by
the Te−Pt−Cl (178.93(3)°) and P(1)−Pt−P(2) (177.81(3)°)
angles. The presence of a Te−Pt bond is unambiguously
confirmed by a Te-Pt bond distance of 2.5238(5) Å which is
almost identical to that in [1]+ (2.5281(5) Å). The short Te−F
(1.954(2) Å), Te−O(1) (1.993(3) Å), and Te−O(2) (1.988(2)
(2) Å) bonds are comparable to those observed for other
hexavalent tellurium species with similar linkages (Te−F = 2.011
(2) Å in Ph5TeF,24 Te−O = 1.930(3) and 1.945(4) Å in
(Ph3SnO)2Te(OMe)4).27 To our knowledge, compound 4 is the
first example of a hexavalent tellurium ligand in the coordination
sphere of a metal. Indeed, while telluroether complexes are well
known,11,14 complexes featuring hypervalent tellurium species as
ligands are extremely scarce and limited to tetravalent tellurium
species.13,21 According to computations carried out at the same
level of theory as for [1]+ and 2 (vide supra), platinum and
tellurium make a very balanced orbital contribution to the Pt−Te
bond (Pt, 46%/Te, 46%) indicative of a dominating covalent
character. This situation contrasts with the Te→Pt and Te←Pt
bond polarization observed in [1]+ and 2, respectively.
Conversion of 2 into 4 can be viewed as resulting from an
internal two-electron redox reaction in which the platinum
center is converting from the formal +III to the +I oxidation state
while the tellurium center switches from +III to the +V oxidation
state. This internal redox reaction is driven by the preference of
tellurium and platinum for hard and soft ligands, respectively.
Formation of 4 as a bis(methoxy) derivative is serendipitous
since the reaction was carried out with an excess of NaF.
Presumably, the weakly basic fluoride anion promotes depro-
tonation of the methanol solvent, leading to complex 4 as a
monofluorobis(methoxide)- rather than a trifluoro-tellurium
species. The strength of the hexavalent tellurium oxygen or
Figure 6. 125Te NMR spectrum of 4 in CDCl3. The inset shows the 19
NMR spectrum.
F
satellite peaks (1JTe‑F = 1893 Hz). The 19F chemical shift as well as
1
the JTe‑F coupling constant is comparable to that observed for
Ph5TeF24 (−42.0 ppm, 1379 Hz) thus pointing to the formation
of a tellurium−fluoride bond. This is confirmed by the 125Te
resonance of 4 at 1117 ppm which shows coupling of the fluorine
nucleus (Figure 6). By analogy with the 125Te NMR chemical
shift trend observed in the PhnTe series (δ = 727, 509, 467 for n =
2, 4, 6, respectively),25 the high-valent tellurium nucleus of 4
could have been expected to resonate at high field, when
compared to [1]+ (1023 ppm) or 2 (1217 ppm). Bearing in mind
that electronegative substituents such as fluorine have a
deshielding effect,26 we speculate that the anomalous chemical
shift of 4 results from the balancing of two opposing influences,
namely the deshielding induced by the electronegative fluoride
and methoxide ligands and the shift to high field typically
observed for hexavalent tellurium nucleus. The multiplicity of the
125Te NMR signal also shows coupling of the tellurium nucleus of
4 to two phosphorus nuclei (JTe‑P = 48 Hz) as well as to one 195Pt
nucleus (1JTe‑Pt = 9044 Hz), thus suggesting an intact PtTe
(o-Ph2PC6H4)2 core. This view is supported by the detection of a
single 31P NMR signal at 64.9 ppm coupled to the 19F (JF‑P = 6.5
Hz), 125Te (JTe‑P = 48 Hz), and 195Pt (1JPt‑P = 2845 Hz) nuclei. It
is important to note that the 1JTe‑Pt coupling constant of 9044 Hz
12234
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238

Journal of the American Chemical Society
Article
fluorine bond is reflected by the stability of 4 to UV irradiation.
Formation of 4 is, however, chemically reversible. Indeed, 4
reacts with trimethylsilyl chloride (TMSCl) to produce 2 as well
as TMSF and TMSOMe, two silyl products that are readily
detected by NMR spectroscopy (see SI). When the reaction is
carried out on a preparative scale, 2 can be recovered in 82% yield
(Scheme 2).
(399.59 MHz; CDCl3): δ 6.85 (d, 2H, o-P(Te)C6H4, 3JH‑H = 7.63
Hz), 6.98 (pseudo t, 2H, m-P(Te)C6H4, 3JH‑H = 7.63 Hz), 7.09
(pseudo t, 2H, m-P(Te)C6H4, 3JH‑H = 7.63 Hz), 7.16−7.29 (m,
3
20H), 7.39 (d, 2H, o-P(Te)C6H4, JH‑H = 7.63 Hz). 13C{1H}
NMR (100.45 MHz; CDCl3): δ 128.0 (s), 128.5 (d, JC‑P = 6.87
Hz), 128.6 (s), 129.9 (s), 133.5 (s), 133.8 (d, JC‑P = 19.45 Hz),
134.1 (s), 137.0 (d, JC‑P = 11.00 Hz), 138.5 (d, JC‑P = 8.40 Hz),
143.4 (d, JC‑P = 3.77 Hz). 31P{1H} NMR (161.74 MHz; CDCl3):
δ -0.3 (s, JTe‑P = 416 Hz). 125Te{1H} NMR (126.14 MHz;
CDCl3): δ 580 (t, JTe‑P = 416 Hz).
CONCLUSION
■
In summary, we report that the TeIIIPtI coordination complex
[1]+ is readily oxidized by a Cl2 equivalent to afford the cor-
responding TeIIIPtIII complex 2. This oxidative addition reaction
can be reversed by simple UV irradiation in the presence of a
radical trap. By uncovering these new reversible two-electron
redox reactions, we show, for the first time, that main group/late
transition metal complexes can mimic the behavior of their
transition metal-only analogues and, in particular, undergo
halogen photoelimination from the oxidized state. A unique facet
of this new redox-active TePt platform originates from the
capacity of the tellurium atom to buffer the electron density of
the redox-active platinum center. These buffering properties are
made possible by the ability of the tetravalent tellurium center
to switch between a regular eight-electron and hypervalent
configuration. These effects and their impact on the reversibility
of the two-electron chemistry displayed by this new platform are
not only of fundamental importance but may also be of relevance
to the field of HX splitting photocatalysis. Finally, we describe
that compound 2 undergoes an internal two-electron redox
reaction in the presence of hard anions to afford complex 4, the
first metalated hexavalent tellurium compound.
Synthesis of [1][Cl]. A solution of PtCl2(Et2S)2 (27.5 mg,
0.062 mmol) in CH2Cl2 (2 mL) was added to a solution of
[(o-(Ph2P)C6H4)2Te] (40 mg, 0.062 mmol) in CH2Cl2 (5 mL)
at ambient temperature. The resulting clear yellow solution was
stirred for 12 h and evacuated to dryness under reduced pressure.
The resulting residue was washed with Et2O (3 × 5 mL) to afford
a pure sample of [1][Cl] as a light yellow crystalline solid (55 mg,
97.4% yield). Yellow crystals of [1][Cl]−CH2Cl2 suitable for
X-ray diffraction analysis were obtained by diffusion of Et2O into
a CH2Cl2 solution of [1][Cl]. 1H NMR (499.42 MHz; CDCl3): δ
7.09 (d of t, 2H, o-P(Te)C6H4, 3JH‑H = 7.28 Hz, 3JH‑P = 4.49 Hz),
7.35−7.45 (m, 8H), 7.49−7.59 (m, 10H), 7.61-7.66 (m, 4H),
7.72 (pseudo t, 2H, m-P(Te)C6H4, 3JH‑H = 7.33 Hz), 9.38 (d, 2H,
3
o-P(Te)C6H4, JH‑H = 8.04 Hz). 13C{1H} NMR (125.58 MHz;
CDCl3): δ 127.0 (t, JC‑P = 31.74 Hz), 128.6 (t, JC‑P = 5.73 Hz),
129.7 (t, JC‑P = 5.73 Hz), 131.3 (t, JC‑P = 3.71 Hz), 132.2 (d, JC‑P
=
60.86 Hz), 133.7−133.9 (m, 2C), 135.8 (s), 137.3 (t, JC‑P = 6.76
Hz), 142.0 (t, JC‑P = 31.84 Hz). 31P{1H} NMR (161.74 MHz;
CDCl3): δ 42.5 (s, JTe‑P = 62 Hz, JPt‑P = 2480 Hz). 125Te{1H}
NMR (126.14 MHz; CDCl3): δ 1023 (t, JTe‑P = 62 Hz, 1JTe‑Pt
=
649 Hz). The 195Pt NMR resonance of this compound could not
be detected. Elemental analysis calculated (%) for [1][Cl]−
CH2Cl2 (C36H28Cl2P2PtTe + CH2Cl2): C, 44.39; H, 3.02; found
C, 44.31; H, 3.13.
EXPERIMENTAL SECTION
■
28
29
General Considerations. cis-PtCl2(Et2S)2 and PhICl2
were prepared according to the reported procedures. Solvents
were dried by passing through an alumina column (n-pentane
and CH2Cl2) or by reflux under N2 over Na/K (Et2O and THF).
All other solvents were used as received. TeCl4, NaI, KF, and
TMSCl were purchased from Aldrich and used as received.
Ambient temperature NMR spectra were recorded on a Varian
Unity Inova 400 FT NMR (399.59 MHz for 1H, 100.45 MHz for
13C, 375.89 MHz for 19F, 161.74 MHz for 31P, 126.14 MHz for
125Te) spectrometer. Chemical shifts (δ) are given in ppm and
are referenced against residual solvent signals (1H, 13C) or exter-
nal BF3−Et2O (19F), H3PO4 (31P), and Ph2Te2 (125Te). Elemental
analyses were performed at Atlantic Microlab (Norcross, GA).
Electrospray mass spectra were obtained with a SciexQstarr Pulsar
and a Protana Nanospray ion source.
Synthesis of 2. A solution of [1][Cl] (80 mg, 0.087 mmol) in
CH2Cl2 (2 mL) was added to a solution of PhICl2 (26 mg, 0.087
mmol) in CHCl3 (2 mL) at ambient temperature. A yellow
precipitate was formed immediately. After the mixture was stirred
for 2 h, 10 mL of Et2O was added. The resulting yellow pre-
cipitate was collected by filtration and dried under vacuum, to
afford 2 (81 mg, 94.0% yield). Compound 2, whose chemical
composition has been established by HRMS and elemental
analysis (see below), has low solubility in organic solvent. The
NMR spectra of 2 was recorded from a in situ reaction of [1][Cl]
(15 mg, 0.016 mmol) with PhICl2 (4.5 mg, 0.016 mmol) in
CDCl3. Yellow crystals of 2-THF suitable for X-ray diffraction
analysis were obtained from diffusing Et2O into a THF solution
1
of 2. H NMR (499.42 MHz; CDCl3): δ 7.11 (t, 2H, m-
Synthesis of [(o-(Ph2P)C6H4)2Te]. To an Et2O solution
(5 mL) of o-(Ph2P)C6H4Br (0.81 g, 2.374 mmol) was added a
n-hexane solution of n-BuLi (2.87 M, 0.99 mL, 2.849 mmol) at
ambient temperature. The mixture was stirred for 20 min,
resulting in the precipitation of o-(Ph2P)C6H4Li. This lithium
salt was washed with Et2O (3 × 5 mL) and suspended in an Et2O
solution (3 mL). To this suspension was added a THF solution
(3 mL) of TeCl4 (160 mg, 0.594 mmol) dropwise at ambient
temperature. After stirring for 12 h, the solvent was removed
under reduced pressure to afford a brown solid. The product was
re-dissolved in CH2Cl2 (30 mL) and filtered through
Celite. Removal of CH2Cl2 under reduced pressure afforded
[(o-(Ph2P)C6H4)2Te] as a light yellow solid which was washed
with Et2O (3 × 5 mL) and n-pentane (3 × 5 mL) and dried under
P(Te)C6H4, 3JH‑H = 7.61 Hz), 7.31−7.77 (m, 20H), 8.10−8.15
3
(m, 4H), 9.23 (d, 2H, o-P(Te)C6H4, JH‑H = 8.08 Hz). A
satisfactory 13C{1H} NMR spectrum could not be recorded due
to precipitation. 31P{1H} NMR (161.74 MHz; CDCl3): δ 26.5
(s, JTe‑P = 86 Hz, JPt‑P = 1777 Hz). 125Te{1H} NMR (126.14
MHz; CDCl3): δ 1217 (t, JTe‑P = 86 Hz, 1JTe‑Pt = 1112 Hz). The
195Pt NMR resonance of this compound could not be detected.
HRMS (ESI+) calcd for [M−Cl]+ (C36H28Cl3P2PtTe+): 950.9495,
found: 950.9479. Elemental analysis calculated (%) for 2
(C36H28Cl4P2PtTe): C, 43.81; H, 2.86; found C, 43.52; H, 2.94.
Reaction of 2 with NaBr. A sample of 2 dissolved in d4-
MeOH was mixed with an excess of NaBr in an NMR tube.
1
Analysis of the reaction mixture by H and 31P NMR spectro-
1
vacuum (169 mg, 43.8% yield based on TeCl4). H NMR
scopy after 2 and 12 h did not show any changes. ESI MS analysis
12235
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238

Journal of the American Chemical Society
Article
of the mixture showed peaks suggesting the possible formation of
mixed chloride/bromide species.
6-31g(d); F/O, 6-31g(d′); C/H, 6-31g).18 The optimized
structures, which are in excellent agreement with the solid-
state structures (see SI), were subjected to a NBO analysis.30 The
resulting Natural Localized Molecular Orbitals (NLMOs) were
visualized and plotted in Jimp 2 program.31 In addition, the
optimized structure of 2 was subjected to time-dependent den-
sity functional theory (TD-DFT) calculations (functional,
MPW1PW91; mixed basis set: Te/Pt, aug-cc-pVTZ-PP; P/Cl,
6-31g(d); C/H, 6-31g) using the SMD implicit solvation model
with CH2Cl2 as a solvent.22
Crystallographic Measurements. The crystallographic
measurements were performed at 110(2) K using a Bruker
APEX-II CCD area detector diffractometer (Mo Kα radiation,
λ = 0.71069 Å). In each case, a specimen of suitable size and
quality was selected and mounted onto a nylon loop. The
structures were solved by direct methods, which successfully
located most of the nonhydrogen atoms. Semi-empirical
absorption corrections were applied. Subsequent refinement
on F2 using the SHELXTL/PC package (version 6.1) allowed
location of the remaining non-hydrogen atoms.
UV−Vis Absorption Measurements. UV−vis spectra were
recorded at room temperature on an Ocean Optics USB4000
spectrometer with an Ocean Optics ISS light source.
Photolysis Reactions and Quantum Yield Measure-
ments. Photolysis reactions were performed using 350 nm light
generated from a 75 W xenon lamp with a PTI model 101 mono-
chromator integrated in a PTI QuantaMaster 40 fluorescence
spectrometer. Potassium ferrioxalate was freshly prepared as a
standard actinometer to determine the photon flux.23 For details
of the quantum yield measurements, see SI.
Synthesis of [3][I3]. To a THF (5 mL) solution of 2 (79 mg,
0.080 mmol) was added a MeOH (5 mL) solution of NaI (60 mg,
0.400 mmol) at ambient temperature. The mixture turned from a
yellow suspension to dark purple solution immediately. After
stirring for 30 min, the solvent was removed under reduced
pressure. The product was re-dissolved in CH2Cl2 (10 mL), and
the insoluble white precipitate was filtered off by passing through
a short plug of Celite. The solvent was then removed under
reduced pressure to give a purple crystalline solid which was
washed with with Et2O (3 × 5 mL) and dried under vacuum to
afford a pure sample of [1-I][I3] (90 mg, 83.1% yield). Purple
needle crystals of [3][I3]−CH2Cl2 suitable for X-ray diffraction
analysis were obtained by diffusion of Et2O into a CH2Cl2
solution of [3][I3]. 1H NMR (499.42 MHz; CDCl3): δ 7.08 (d of
t, 2H, o-P(Te)C6H4, 3JH‑H = 7.28 Hz, 3JH‑P = 4.49 Hz), 7.29−7.34
(m, 4H), 7.44−7.53 (m, 6H), 7.58−7.62 (m, 8H), 7.67−7.73 (m,
4H), 7.84 (pseudo t, 2H, m-P(Te)C6H4, 3JH‑H = 7.97 Hz), 8.70
(d, 2H, o-P(Te)C6H4, 3JH‑H = 7.94 Hz). 13C{1H} NMR (125.58
MHz; CDCl3): δ 127.3 (t, JC‑P = 27.85 Hz), 128.5 (t, JC‑P = 5.63
Hz), 130.1 (t, JC‑P = 5.63 Hz), 131.8 (t, JC‑P = 3.90 Hz), 132.5
(d, JC‑P = 87.83 Hz), 134.0 (t, JC‑P = 5.98 Hz), 134.1 (t, JC‑P = 7.26
Hz), 134.5 (s), 136.8 (t, JC‑P = 7.60 Hz), 137.7 (t, JC‑P = 3.09 Hz).
31P{1H} NMR (161.74 MHz; CDCl3): δ 37.5 (s, JTe‑P = 49 Hz,
JPt‑P = 2336 Hz). 125Te{1H} NMR (126.14 MHz; CDCl3): δ
1
1018 (t, JTe‑P = 49 Hz, JTe‑Pt = 542 Hz). The 195Pt NMR
resonance of this compound could not be detected. Elemental
analysis calculated (%) for [3][I3] (C36H28I4P2PtTe): C, 31.96;
H, 2.09; found C, 31.86; H, 2.14.
Synthesis of 4. To a THF (8 mL) solution of 2 (150 mg,
0.152 mmol) was added a MeOH (2 mL) solution of KF (44.1
mg, 0.760 mmol) at ambient temperature. The mixture turned
from a yellow suspension to a colorless suspension over 5 min.
After stirring for 2 h, the solvent was removed under reduced
pressure. The product was re-dissolved in CH2Cl2 (10 mL), and
the insoluble white precipitate was filtered off by passing through
a short plug of Celite. The solvent was again removed under
reduced pressure to give a white solid which was washed with
Et2O (3 × 5 mL) and dried under vacuum to afford a pure sample
of 3 (105 mg, 71.8% yield). Colorless crystals of 4 suitable for
X-ray diffraction analysis were obtained by diffusion of Et2O into
a CH2Cl2 solution of 4. 1H NMR (499.42 MHz; CDCl3): δ 2.77
(d, 6H, OMe, 4JH‑F = 1.49 Hz, 3JH‑Te = 51.47 Hz), 7.37−7.48 (m,
Gas Chromatography−Mass Spectrometry. GC-MS was
performed on Ultra GC/DSQ (ThermoElectron, Waltham, MA).
Rxi-5ms was used as a gas chromatographic column with
dimensions of 60 m length, 0.25 mm i.d., and 0.25 μm film
thickness (Restek, Bellefonte, PA). Helium was used as a carrier
gas at constant flow of 1.5 mL/min. Splitless and split (1:10)
injection were used. Transfer line and ion source were held at
250 °C. The column temperature was maintained at 50 °C for
5 min and raised to 320 °C at 20 °C/min. Mass spectra were
acquired in full scan mode in the range of 30-500 m/z. For details
of DMBD“Cl2” analysis, please see SI.
ASSOCIATED CONTENT
■
16H), 7.57−7.62 (m, 10H), 8.71 (d, 2H, o-P(Te)C6H4, 3JH‑H
=
S
* Supporting Information
3
7.65 Hz, JH‑Te = 44.60 Hz). 13C{1H} NMR (125.58 MHz;
CDCl3): δ 52.4 (s, OMe), 124.3 (t, JC‑P = 30.39 Hz), 128.5
(t, JC‑P = 5,61 Hz), 129.3 (t, JC‑P = 29.05 Hz), 130.4 (t, JC‑P = 3.06
Additional experimental and computational details; crystallo-
graphic data in CIF format. This material is available free of
charge via the Internet at http://pubs.acs.org.
Hz), 131.0 (s), 132.3 (s), 133.3 (d, JC‑P = 2.97 Hz), 133.9 (t, JC‑P
=
6.28 Hz), 134.1 (t, JC‑P = 7.84 Hz), 164.2 (d of t, JC‑P = 57.47 Hz,
JC‑P = 17.88 Hz). 19F{1H} NMR (375.89 MHz; CDCl3): δ -58.7
(s, 1JTe‑F = 1893 Hz). 31P{1H} NMR (161.74 MHz; CDCl3): δ
64.9 (d, JF‑P = 6.5 Hz, JTe‑P = 48 Hz, JPt‑P = 2845 Hz). 125Te{1H}
NMR (126.14 MHz; CDCl3): δ 1117 (d of t, 1JTe‑F = 1893 Hz,
JTe‑P = 48 Hz, 1JTe‑Pt = 9044 Hz). The 195Pt NMR resonance of
this compound could not be detected. Elemental analysis
calculated (%) for 3 (C38H34ClFO2P2Te): C, 47.46; H, 3.56;
found C, 46.31; H, 3.11.
Computational Details. Density functional theory (DFT)
structural optimizations were performed on the solid-state struc-
tures of complexes [1]+, 2, and 4 using Gaussian 09 suite of
programs with effective core potentials on all heavy atoms (func-
tional, BP86;17 mixed basis set: Te/Pt, aug-cc-pVTZ-PP; P/Cl,
AUTHOR INFORMATION
■
Corresponding Author
francois@tamu.edu
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the National Science Foundation
(CHE-0952912), the Welch Foundation (A-1423), and Texas
A&M University (Davidson Professorship). We also acknowl-
edge Dr. Yohannes Rezenom for the analysis of DMBD“Cl2”
derivatives.
12236
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238

Journal of the American Chemical Society
Article
38, 512−514. (d) Torubaev, Y.; Pasynskii, A.; Mathur, P. J. Organomet.
Chem. 2009, 694, 1781−1785. (e) Torubaev, Y. V.; Pasynskii, A. A.;
Galustyan, A. R.; Mathur, P. Russ. J. Coord. Chem. 2009, 35, 1−5.
(f) Torubaev, Y.; Pavlova, A.; Pasynskii, A. Russ. J. Coord. Chem. 2012,
38, 219−223. (g) Torubaev, Y.; Pasynskii, A.; Mathur, P. Coord. Chem.
Rev. 2012, 256, 709−721.
(14) (a) Murray, S. G.; Hartley, F. R. Chem. Rev. 1981, 81, 365−414.
(b) Gysling, H. J. Coord. Chem. Rev. 1982, 42, 133−244. (c) Singh, A. K.;
Sharma, S. Coord. Chem. Rev. 2000, 209, 49−98. (d) Singh, A. K. Focus
Organomet. Chem. Res. 2005, 79−109.
(15) Janzen, M. C.; Jennings, M. C.; Puddephatt, R. J. Inorg. Chem.
2003, 42, 4553−4558.
REFERENCES
■
(1) (a) Evans, D. H.; Gruhn, N. E.; Jin, J.; Li, B.; Lorance, E.; Okumura,
N.; Macías-Ruvalcaba, N. A.; Zakai, U. I.; Zhang, S.-Z.; Block, E.; Glass,
R. S. J. Org. Chem. 2010, 75, 1997−2009. (b) Nakayama, N.; Takahashi,
O.; Kikuchi, O.; Furukawa, N. Heteroat. Chem 2000, 11, 31−41.
(c) Fujihara, H.; Takaguchi, Y.; Ninoi, T.; Erata, T.; Furukawa, N. J.
Chem. Soc., Perkin Trans. 1 1992, 2583−2584. (d) Fujihara, H.; Ninoi,
T.; Akaishi, R.; Erata, T.; Furukawa, N. Tetrahedron Lett. 1991, 32,
4537−4540. (e) Fackler, J. P.; Murray, H. H.; Basil, J. D. Organometallics
1984, 3, 821−823. (f) Fackler, J. P. Inorg. Chem. 2002, 41, 6959−6972.
(g) Mazany, A. M.; Fackler, J. P. J. Am. Chem. Soc. 1984, 106, 801−802.
(h) Basil, J. D.; Murray, H. H.; Fackler, J. P.; Tocher, J.; Mazany, A. M.;
Trzcinska-Bancroft, B.; Knachel, H.; Dudis, D.; Delord, T. J.; Marler, D.
J. Am. Chem. Soc. 1985, 107, 6908−6915.
(2) Two-electron redox chemistry is also well precedented for
mononulcear tellurium derivatives. For examples, see: (a) Detty, M.
R.; Zhou, F.; Friedman, A. E. J. Am. Chem. Soc. 1996, 118, 313−318.
(b) You, Y.; Ahsan, K.; Detty, M. R. J. Am. Chem. Soc. 2003, 125, 4918−
4927.
(3) (a) Mann, K. R.; Lewis, N. S.; Miskowski, V. M.; Erwin, D. K.;
Hammond, G. S.; Gray, H. B. J. Am. Chem. Soc. 1977, 99, 5525−5526.
(b) Mann, K. R.; Bell, R. A.; Gray, H. B. Inorg. Chem. 1979, 18, 2671−
2673. (c) Maverick, A. W.; Gray, H. B. Pure Appl. Chem. 1980, 52,
2339−2348. (d) Sigal, I. S.; Mann, K. R.; Gray, H. B. J. Am. Chem. Soc.
1980, 102, 7252−7256. (e) Mann, K. R.; Dipierro, M. J.; Gill, T. P. J. Am.
Chem. Soc. 1980, 102, 3965−3967. (f) Gray, H. B.; Maverick, A. W.
Science 1981, 214, 1201−1205. (g) Eidem, P. K.; Maverick, A. W.; Gray,
H. B. Inorg. Chim. Acta 1981, 50, 59−64. (h) Esswein, A. J.; Nocera, D.
G. Chem. Rev. 2007, 107, 4022−4047. (i) Heyduk, A. F.; Nocera, D. G.
Science 2001, 293, 1639−1641.
(16) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.;
Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.;
Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J., J. A.; ;
Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin,
K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.;
Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.;
Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.;
Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.;
Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich,
̈
S.; Daniels, A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.;
Fox, D. J. Gaussian 09, Revision B.01; Gaussian, Inc.: Wallingford, CT,
2009.
(17) (a) Perdew, J. P. Phys. Rev. B 1986, 33, 8822−8824. (b) Becke, A.
D. Phys. Rev. A 1988, 38, 3098−3100.
(18) (a) Figgen, D.; Peterson, K. A.; Dolg, M.; Stoll, H. J. Chem. Phys.
2009, 130, 164108−164112. (b) Peterson, K. A.; Figgen, D.; Goll, E.;
Stoll, H.; Dolg, M. J. Chem. Phys. 2003, 119, 11113−11123.
(19) For other redox processes involving atrane complexes with
Metal→Lewis acid interactions, see: (a) Harman, W. H.; Peters, J. C.
(4) (a) Heyduk, A. F.; Macintosh, A. M.; Nocera, D. G. J. Am. Chem.
Soc. 1999, 121, 5023−5032. (b) Teets, T. S.; Nocera, D. G. J. Am. Chem.
Soc. 2009, 131, 7411−7420. (c) Cook, T. R.; Surendranath, Y.; Nocera,
D. G. J. Am. Chem. Soc. 2009, 131, 28−29. (d) Teets, T. S.; Lutterman,
D. A.; Nocera, D. G. Inorg. Chem. 2010, 49, 3035−3043. (e) Teets, T. S.;
Neumann, M. P.; Nocera, D. G. Chem. Commun. 2011, 47, 1485−1487.
(f) Teets, T. S.; Cook, T. R.; McCarthy, B. D.; Nocera, D. G. Inorg.
Chem. 2011, 50, 5223−5233. (g) Cook, T. R.; McCarthy, B. D.;
Lutterman, D. A.; Nocera, D. G. Inorg. Chem. 2012, 51, 5152−5163.
(5) Cook, T. R.; Esswein, A. J.; Nocera, D. G. J. Am. Chem. Soc. 2007,
129, 10094−10095.
J. Am. Chem. Soc. 2012, 134, 5080−5082. (b) Brendler, E.; Wachtler, E.;
̈
Heine, T.; Zhechkov, L.; Langer, T.; Pottgen, R.; Hill, A. F.; Wagler, J.
̈
Angew. Chem., Int. Ed. 2011, 50, 4696−4700. (c) Moret, M. E.; Peters,
J. C. Angew. Chem., Int. Ed. 2011, 50, 2063−2067. (d) Crossley, I. R.;
Hill, A. F. Organometallics 2004, 23, 5656−5658. (e) Figueroa, J. S.;
Melnick, J. G.; Parkin, G. Inorg. Chem. 2006, 45, 7056−7058.
(f) Crossley, I. R.; Hill, A. F.; Willis, A. C. Organometallics 2008, 27,
312−315. (g) Pang, K. L.; Tanski, J. M.; Parkin, G. Chem. Commun.
2008, 1008−1010. (h) Krogman, J. P.; Foxman, B. M.; Thomas, C. M.
J. Am. Chem. Soc. 2011, 133, 14582−14585.
(6) Wade, C. R.; Gabbaï, F. P. Angew. Chem., Int. Ed. 2011, 50, 7369−
7372.
(7) Gysling, H. J.; Luss, H. R. Organometallics 1984, 3, 596−598.
(8) (a) Pyykko, P.; Atsumi, M. Chem.Eur. J. 2009, 15, 186−197.
̈
(20) (a) Fontaine, F. G.; Boudreau, J.; Thibault, M. H. Eur. J. Inorg.
Chem. 2008, 5439−5454. (b) Braunschweig, H.; Dewhurst, R. D.;
Schneider, A. Chem. Rev. 2010, 110, 3924−3957. (c) Bouhadir, G.;
Amgoune, A.; Bourissou, D. Adv. Organomet. Chem. 2010, 58, 1−107.
(d) Amgoune, A.; Bourissou, D. Chem. Commun. 2011, 47, 859−871.
(b) Cordero, B.; Gomez, V.; Platero-Prats, A. E.; Reves, M.; Echeverria,
J.; Cremades, E.; Barragan, F.; Alvarez, S. Dalton Trans. 2008, 2832−
2838.
(9) (a) The Te−Pt bond of complexes [1]+, 2, and [3]+ are polar and
could be described using the dative formalism. However, because of the
formal oxidation state or d-electron count ambiguity that the dative
formalism sometimes engenders (for example, see refs 9b and c), we
have chosen to describe the Te−Pt bonding in these complexes using
resonance structures. In the case of 4, the Te−Pt bond is covalent such
that the compound can be properly described on the basis of a single
resonance structure. (b) Hill, A. F. Organometallics 2006, 25, 4741−
4743. (c) Parkin, G. Organometallics 2006, 25, 4744−4747.
́
(e) Lin, T.-P.; Wade, C. R.; Perez, L. M.; Gabbaï, F. P. Angew. Chem., Int.
Ed. 2010, 49, 6357−6360. (f) Wade, C. R.; Lin, T.-P.; Nelson, R. C.;
Mader, E. A.; Miller, J. T.; Gabbaï, F. P. J. Am. Chem. Soc. 2011, 133,
8948−8955. (g) Lin, T.-P.; Ke, I.-S.; Gabbaï, F. P. Angew. Chem., Int. Ed.
2012, 51, 4985−4988. (h) Wade, C. R.; Ke, I.-S.; Gabbaï, F. P. Angew.
Chem., Int. Ed. 2012, 51, 478−481. (i) Lin, T.-P.; Nelson, R. C.; Wu, T.;
Miller, J. T.; Gabbaï, F. P. Chem. Sci. 2012, 3, 1128−1136. (j) Rudd, P.
A.; Liu, S.; Gagliardi, L.; Young, V. G.; Lu, C. C. J. Am. Chem. Soc. 2011,
133, 20724−20727.
(10) (a) Oberhauser, W.; Bachmann, C.; Stampfl, T.; Bruggeller, P.
̈
Inorg. Chim. Acta 1997, 256, 223−234. (b) Hope, E. G.; Levason, W.;
Powell, N. A. Inorg. Chim. Acta 1986, 115, 187−192. (c) Oberhauser,
W.; Stampfl, T.; Bachmann, C.; Haid, R.; Langes, C.; Kopacka, H.;
(21) Liaw, W.-F.; Chiou, S.-J.; Lee, G.-H.; Peng, S.-M. Inorg. Chem.
1998, 37, 1131−1134.
(22) Marenich, A. V.; Cramer, C. J.; Truhlar, D. G. J. Phys. Chem. B
2009, 113, 6378−6396.
(23) (a) Hatchard, C. G.; Parker, C. A. Proc. R. Soc. London, Ser. A 1956,
235, 518−536. (b) Parker, C. A. Proc. R. Soc. London, Ser. A 1953, 220,
104−116. (c) Kuhn, H. J.; Braslavsky, S. E.; Schmidt, R. Pure Appl. Chem.
2004, 76, 2105−2146.
(24) Minoura, M.; Sagami, T.; Akiba, K.-y. Organometallics 2001, 20,
2437−2439.
Ongania, K.-H.; Bruggeller, P. Polyhedron 2000, 19, 913−923.
̈
(11) Hope, E. G.; Levason, W. Coord. Chem. Rev. 1993, 122, 109−170.
(12) Alcock, N. W.; Harrison, W. D. J. Chem. Soc., Dalton Trans. 1982,
251−255.
(13) (a) Ebsworth, E. A. V.; Holloway, J. H.; Watson, P. G. J. Chem.
Soc., Chem. Commun. 1991, 1443−1444. (b) Eveland, J. R.; Whitmire, K.
H. Angew. Chem., Int. Ed. 1996, 35, 741−743. (c) Dyson, P. J.; Hill, A. F.;
Hulkes, A. G.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. 1999,
12237
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238

Journal of the American Chemical Society
Article
(25) Minoura, M.; Sagami, T.; Akiba, K.-y.; Modrakowski, C.; Sudau,
A.; Seppelt, K.; Wallenhauer, S. Angew. Chem., Int. Ed. 1996, 35, 2660−
2662.
(26) Klapotke, T. M.; Krumm, B.; Polborn, K.; Schwab, I. J. Am. Chem.
̈
Soc. 2004, 126, 14166−14175.
(27) Herntrich, T.; Merzweiler, K. Z. Anorg. Allg. Chem. 2010, 636,
803−807.
(28) De Crisci, A. G.; Lough, A. J.; Multani, K.; Fekl, U. Organometallics
2008, 27, 1765−1779.
(29) Zhao, X.-F.; Zhang, C. Synthesis 2007, 551−557.
(30) Glendening, E. D.; Badenhoop, J. K.; Reed, A. E.; Carpenter, J. E.;
Bohmann, J. A.; Morales, C. M.; Weinhold, F. NBO 5.9; Theoretical
Chemistry Institute, University of Wisconsin, Madison, WI, 2011.
(31) (a) Hall, M. B.; Fenske, R. F. Inorg. Chem. 1972, 11, 768−775.
(b) Manson, J.; Webster, C. E.; Per
chem.tamu.edu/jimp2/index.html.
́
ez, L. M.; Hall, M. B., http://www.
12238
dx.doi.org/10.1021/ja3046074 | J. Am. Chem. Soc. 2012, 134, 12230−12238