Tungsten Ligand-Based Sulfur-Atom-Transfer Catalysts: Synthesis, Characterization, Sustained Anaerobic Catalysis, and Mode of Aerial Deactivation

Article abstract of DOI:10.1021/acs.inorgchem.0c02915

The synthesis, properties, X-ray structures, and catalytic sulfur-atom-transfer (SAT) reactions of W2(μ-S)(μ-S2)(dtc)2(dped)2 [1; dtc = S2CNR2-, where R = Me, Et, iBu, and Bn; dped = S2C2Ph22-] and W2(μ-S)2(dtc)2(dped)2 (2) are reported. These complexes represent the oxidized (1) and reduced (2) forms of anaerobic SAT catalysts operating through the bidirectional, ligand-based half-reaction (μ-S)(μ-S2) ? (μ-S)2 + S0. The catalysts are deactivated in air through the formation of catalytically inactive oxo complexes, (dtc)WO(μ-S)(μ-dped)W(dtc)(dped) (3), prompting us to recommend that group 6 SAT activity be assessed under strictly anaerobic conditions.

Full text of DOI:10.1021/acs.inorgchem.0c02915

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Tungsten Ligand-Based Sulfur-Atom-Transfer Catalysts: Synthesis,
Characterization, Sustained Anaerobic Catalysis, and Mode of Aerial
Deactivation
James P. Ward, Patrick J. Lim, David J. Evans, Jonathan M. White, and Charles G. Young*
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ABSTRACT: The synthesis, properties, X-ray structures, and catalytic sulfur-atom-transfer (SAT) reactions of W2(μ-S)(μ-
−
S2)(dtc)2(dped)2 [1; dtc = S2CNR2 , where R = Me, Et, iBu, and Bn; dped = S2C2Ph22−] and W2(μ-S)2(dtc)2(dped)2 (2) are
reported. These complexes represent the oxidized (1) and reduced (2) forms of anaerobic SAT catalysts operating through the
bidirectional, ligand-based half-reaction (μ-S)(μ-S2) ↔ (μ-S)2 + S0. The catalysts are deactivated in air through the formation of
catalytically inactive oxo complexes, (dtc)WO(μ-S)(μ-dped)W(dtc)(dped) (3), prompting us to recommend that group 6 SAT
activity be assessed under strictly anaerobic conditions.
tom-transfer reactions are an area of fundamental
importance in biology, chemical synthesis, and industry,
Scheme 1. Summary of Synthetic Transformations
A
and oxygen-1−4 and sulfur-atom4−7 transfers have received
much attention. Catalytic atom-transfer technologies are highly
prized, and many examples of catalytic oxygen-atom-transfer
have been described.1−4 However, catalytic sulfur-atom-transfer
(SAT) reactions are rare despite reports of unidirectional
reactions of this type.4−7 Catalytic SAT reactions in group 6
chemistry include the disulfidomolybdenum systems developed
by Bargon and co-workers,8−10 the sulfidotungsten systems
described by Young,11 Sugimoto,12 and their co-workers, and
the organometallic system reported by Sita and co-workers;13
most of these systems feature monomeric M(VI) ↔ M(IV)
complexes, active sulfido or disulfido ligands, and dithioacid or
dithiolene coligands.
Here, we report the synthesis, characterization, and catalytic
SAT reactions of dinuclear tungsten(V) complexes containing
sulfido, disulfido, dithiocarbamate, and dithiolene ligands
(Scheme 1). These complexes, W2(μ-S)(μ-S2)(dtc)2(dped)2
−
readily soluble in chlorinated solvents and partially soluble in
methanol and hydrocarbons. The amelioration of ligand
“melding” reactions15 through the use of a less-activated alkyne
is a significant aspect of the syntheses.
Microanalytical and electrospray ionization mass spectro-
metric results confirmed the formulations of 1. IR spectra
showed a broad, strong ν(CN) band at 1535−1500 cm−1, while
1H NMR spectra revealed a 1:1 dtc/dped ligand ratio and two
sets of dtc R-group resonances; compounds containing
diastereotopic groups exhibited distinctive multiline NMR
(1) and W2(μ-S)2(dtc)2(dped)2 (2) (dtc = S2CNR2 , where
Rdtc = Me, Et, iBu, and Bn; dped = S2C2Ph22−), represent the
oxidized (1) and reduced (2) forms of the catalysts, with the
bidirectional SAT “half-reaction” being ligand-based rather than
metal-based (eq 1). Significantly, both forms of the catalysts
have been isolated and unambiguously characterized. Further,
the generation of catalytically inactive oxo complexes, (dtc)-
WO(μ-S)(μ-dped)W(dtc)(dped) (3), is identified as the mode
of catalyst deactivation in air. This key result suggests that
strictly anaerobic conditions should be maintained in the
assessment of group 6 SAT catalysts.
Received: October 1, 2020
(μ‐S)(μ‐S2) ↔ (μ‐S)2 + S0
(1)
Ink-blue 1 are generated in the reactions of green WS(S2)-
(dtc)214 and PhCCPh in refluxing 1,2-dichloroethane under
anaerobic conditions (first reaction, Scheme 1). The air-stable
complexes were isolated by column chromatography and are
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spectra. 13C NMR spectra revealed resonances assignable to the
dtc [δ(CS2) ca. 200] and dped ligands.
Molecules of 1-Me and 1-Bn (Figure 1) are dinuclear with
severely distorted pentagonal-bipyramidal (PBP) tungsten(V)
anion of (PPh4)2[W2(μ-S)(μ-S2)Br8].16 A related molybdenum
complex, Mo2(NC6H3iPr2-2,6)2(μ-S)(μ-S2)(dtc)2 (Rdtc = Et),
has been reported by Coffey and Hogarth.17
The dped ligand S2C4 frameworks are close to planar, with
mean atom displacements (and S···S fold angles) of 0.004 Å
(0.9°) and 0.007 Å (5.7°) for the ligands containing S6 and S10,
respectively. The dtc ligand S2CNC2 frameworks are also planar,
with the corresponding parameters being 0.0218 Å (13.5°) and
0.0521 Å (8.3°) for the ligands containing S4 and S8,
respectively. The metrical parameters for the bidentate ligands
are in accordance with those reported for dithiocarbamate and
fully reduced dithiolene ligands (this is true of all structures
reported herein).18,19
Purple-brown 2 are produced in the reactions of 1 with 1
equiv of PPh3 in dichloromethane under anaerobic conditions
(second reaction, Scheme 1); their precipitation from the
reaction mixture facilitates isolation by simple filtration. They
are surprisingly insoluble in most solvents or sparingly soluble
with decomposition in very polar solvents such as dimethyl
sulfoxide and N,N-dimethylformamide. Aerial reactions with an
excess of PPh3 result in the formation of 3 (vide infra).
Complexes 2 were characterized by microanalysis, IR and
NMR spectroscopy, and X-ray crystallography. Their IR spectra
were very similar to 1 with ν(CN) ∼ 1530−1500 cm−1. The
NMR spectra were consistent with centrosymmetric structures
and a 1:1 dtc/dped ligand ratio; once again, the diastereotopic
groups of the dtc ligands exhibited distinctive multiline
resonances.
Dimeric 2-Bn (Figure 2) exhibits a centrosymmetric structure
with two bridging sulfido ligands linking W1 and W1′. This
produces a structure with a planar W2(μ-S)2 unit and symmetry-
related dtc and dped ligands on each tungsten. Interestingly, the
Figure 1. Structure of 1-Bn. Top: Partial structure showing only the
benzylic and phenyl C1 atoms of the dtc Bn groups. Bottom: Core unit
viewed perpendicular to the W1−W2−S1−S3 plane. Additional bond
distances (Å): W1−S1, W1−S2, W1−S3, W1−S8, W1−S9, W1−S10,
and W1−S11 = 2.316(1), 2.490(1), 2.431(1), 2.531(1), 2.500(1),
2.453(1), and 2.365(1), respectively; W2−S1, W2−S2, W2−S3, W2−
S4, W2−S5, W2−S6, and W2−S7 = 2.348(1), 2.503(1), 2.432(1),
2.500(1), 2.518(1), 2.357(1), and 2.435(1), respectively. All thermal
ellipsoids drawn in this paper are at the 50% probability level.
centers bridged by sulfido and disulfido ligands and coordinated
by bidentate dtc and dped ligands; a pseudomirror plane
containing the bridging sulfur atoms bisects the W−W vector.
The W1−W2 distance of 2.8451(3) Å and the diamagnetism of
these formally W(V) d1 complexes are indicative of W−W
bonding (likewise for 2 and 3).
In 1-Bn, the PBP geometry of W1 is defined by equatorial
atoms S2, S3, S8, S10, and S11 and axial atoms S1 and S9. For
W2, atoms S2, S3, S5, S6, and S7 occupy equatorial sites, while
S1 and S4 occupy axial sites. The W1 and W2 atoms lie
0.2491(6) and 0.2022(6) Å out of their respective equatorial
planes, each with mean sulfur-atom displacements of 0.19 and
0.24 Å, respectively, in the direction of the μ-sulfido ligand S1.
The disparate bite angles of the disulfido (ca. 49°) and dped (ca.
79°) ligands account for the major deviations from the ideal PBP
equatorial angle of 72°. The axial atoms lie off the perpendiculars
to the pentagonal planes by ca. 15°.
The W1, W2, S1, and S3 atoms are nearly planar with a mean
atom displacement of 0.053 Å, with atom S2 lying 1.781(3) Å
out of this plane. The W−μ-sulfido distances average at 2.33 Å,
while the in-plane and out-of-plane W−μ-disulfido distances
average 2.43 and 2.495 Å, respectively. The S2−S3 distance of
2.025(2) Å is typical of disulfido ligands. Structurally
characterized complexes containing the [W2(μ-S)(μ-S2-
κ2S,S′)]6+ core are rare, with the only other example being the
Figure 2. Structure of 2-Bn. Top: Complete centrosymmetric structure.
Bottom: Core unit viewed perpendicular to the W2(μ-S)2 plane.
Additional bond distances (Å): W−S1, W−S2, W−S3, and W−S4 =
2.360(3), 2.401(3), 2.493(4), and 2.487(3), respectively.
B
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disposition of the organic ligands has changed significantly
compared to 1-Bn, undergoing an approximate 90° twist around
the W−W bond. The tungsten centers display a coordination
geometry halfway between octahedral and trigonal-prismatic
(TP), with the TP triangular faces, viz., S1,S3,S5 and S2,S4,S5′,
being related by a trigonal twist of ca. 30°.18 The W−W vector
bisects the S5···S5′ edge of the TP structure. Additional
distortions from ideal geometries arise from the disparate bite
angles of the dtc and dped ligands.
The W−W distance of 2.8919(12) Å and the W−μ-S
distances of 2.343(3) and 2.360(3) Å are comparable to those
observed in related complexes (vide infra). There is a slight
asymmetry in the W−S distances within the dtc and dped
ligands, with the longer bonds being roughly trans to the W−μ-S
bonds. Similarly, the C−S bonds fall into two groups, with the
marginally shorter bond for each ligand being adjacent to the
longer W−S bond. The dtc and dped ligands are essentially
planar with marginal fold angles.
The [W2(μ-S)2]6+ core is relatively common, and structurally
characterized dithiolene complexes include (NEt4)2[W2(μ-
S)2(dped)4],20 (NEt4)2[W2(μ-S)2(dmed)4] (dmed =
S2C2Me22−),21 (cat)2[W2(μ-S)2{S2C2(CO2Me)2}4] (cat =
22
and NEt4 23), and {(Ph3P)2N}2[W2(μ-
+
+
NnPr4
S)2{S2C2(CN)2}4].24 None of these complexes appear to have
been tested for SAT activity.
Complexes 1 catalyze SAT from propylene sulfide to
triphenylphosphine according to eq 2 (cf. eq 1). The
Figure 3. Catalysis of SAT from propylene sulfide to PPh3 using 1-Bn.
(a) 31P{1H} NMR spectra recorded during monitoring of the reaction
from 5 to 85 mins at 10 min intervals. (b) Plot of the change in the
■
concentration of PPh3 (+) and SPPh3 ( ) with time. The spectra in
part a yield the data points shown to the left of the dashed green line
(with two representative data points thereafter).
Table 1. Turnover and Conversion for SAT Reactions
involvement of 2 is demonstrated by their independent synthesis
(vide supra); however, they are less effective starting catalysts
because of their limited solubility.
derivative
turnover (mol/mol cat/h)
conversion (%)
Me
Et
5.3
9.7
50
80
The progress of the SAT reactions catalyzed by 1 were
monitored by 31P NMR spectroscopy, and typical results are
shown in Figure 3. The samples monitored were 5 mol % in
catalyst and 100 and 140 mM in PPh3 and propylene sulfide,
respectively, in CDCl3. The spectra showed a decrease in the
concentration of PPh3 and a concomitant increase in the
concentration of SPPh3 at the turnovers and percent conversions
indicated in Table 1. The reactions involving the bulkier
dithiocarbamates reached ca. 80−85% completion, but the
benzyl derivative achieved complete conversion of PPh3 to
SPPh3. The methyl derivative was a slower and less stable/
reliable catalyst perhaps because of the reduced steric protection
of the dinuclear core against adventitious reagents. In other
cases, the catalysts remained active under anaerobic conditions,
and the addition of more PPh3 and propylene sulfide led to the
further production of SPPh3.
Catalytic SAT slowed and then ceased upon exposure of the
anaerobic reaction mixtures to air. This was accompanied by the
formation of OPPh3 (ca. 10%) and green 3, with the latter being
isolated by column chromatography (Rf ∼ 0.4 in 9:1 CH2Cl2/n-
hexane). Green 3 also formed when 1 was reacted with PPh3 in
air. These complexes result from the net exchange of a sulfido
ligand in 2 for an oxo ligand (third reaction, Scheme 1);
significantly, their formation is identified as the key mode of
catalyst deactivation in air.
iBu
Bn
11.7
17.1
85
100
Complexes 3 exhibited IR spectra very similar to 1 and 2 but
with the addition of a ν(WO) band at 945 cm−1. Mass
spectrometric results showed a strong signal due to the [M +
H]+ ion of 3.
Molecules of 3-Et and 3-iBu (Figure 4) exhibit asymmetric
structures with two distinctly different tungsten(V) centers
bridged by three sulfur atoms from sulfido and bidentate dped
ligands. In molecule 1 of 3-iBu, the W−μ-S distances fall into
three groups; W−S9 av. 2.364 Å < W−S3 av. 2.504 Å < W1−S4
= 2.530(2) Å and W2−S4 = 2.6094(18) Å. The last two sets of
bonds are lengthened by the organic nature of the ligand and, in
the case of W2−S4, the trans influence of the terminal oxo
ligand.25,26 The W−W distance is 2.8236(5) Å.
The coordination geometries of both tungsten atoms are
highly distorted. That of W1, defined by bidentate dtc and dped
ligands and bridging sulfido and dped ligands, is approximately
capped TP, with S5 as the capping atom. The dtc and
nonbridging dped ligands are nearly symmetrically coordinated
and essentially planar. However, both exhibit substantial ligand
fold angles of 6.5° and 22.5°, respectively.
C
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In conclusion, the novel mixed-ligand tungsten(V) complexes
1 and their reduced, desulfurized counterparts 2 catalyze SAT
from propylene sulfide to triphenylphosphine according to eq 2.
These complexes represent the oxidized (1) and reduced (2)
forms of a ligand-based SAT system that does not involve any
formal oxidation state changes at the metal centers, with the
bidirectional catalyst-based “half-reaction” being given by eq 1.
Catalyst deactivation in air, associated with the formation of
catalytically inactive 3, prompts us to recommend the
maintenance of anaerobic conditions in studies of group 6
SAT catalysis. Extension to other substrates and refinement of
this system through, e.g., the incorporation of chiral dtc or
related dithioacid ligands, should expand functionality and
facilitate the development of catalysts for asymmetric SAT.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c02915.
■
sı
Syntheses and analytical and spectroscopic data (PDF)
Accession Codes
CCDC 2019209−2019213 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge via www.ccdc.cam.ac.uk/data_request/cif, or by email-
ing data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: +44 1223 336033.
Figure 4. Structure of molecule 1 (of 2) of 3-iBu. Top: Full structure.
Bottom: Core unit. Additional bond distances (Å): W1−S1, W1−S2,
W1−S3, W1−S5, W1−S6, and W1−S9 = 2.363(2), 2.392(2),
2.513(2), 2.523(2), 2.536(2), and 2.369(2), respectively; W2−S3,
W2−S7, W2−S8, and W2−S9 = 2.496(2), 2.459(2), 2.444(2), and
2.359(2), respectively.
AUTHOR INFORMATION
Corresponding Author
■
Charles G. Young − Department of Chemistry and Physics, La
Trobe Institute of Molecular Sciences, La Trobe University,
Melbourne, Victoria 3086, Australia; orcid.org/0000-
0002-4019-9961; Email: charles.young@latrobe.edu.au
The distorted octahedral coordination sphere of W2 is
defined by a terminal oxo ligand, a bidentate dtc ligand, and the
sulfur atoms of the bridging sulfido and dped ligands. The W2−
O1 distance of 1.695(6) Å and the significant trans lengthening
of W2−S4 (vide supra) are typical of multiply bonded WO
moieties.25,26 The essentially planar dtc framework, also
coplanar with W2, is swiveled slightly away from the bulky
dped bridging ligand. The bridging dped ligand is slightly
distorted from planarity but is close to symmetrical with respect
to internal metrical parameters. The core unit of 3 is closely
related to that of the recently reported (NEt4)2[{WO-
(dmed)}2(μ-S)(μ-dmed)].27
Catalytic SAT in the MoO(S2)(dtc)2 (Rdtc = Et) system
described by Bargon and co-workers10 is adversely impacted by
the formation of an inactive dimeric oxomolybdenum(V)
complex. Here, SAT from MoO(S2)(dtc)2 to the substrate is
proposed to form MoOS(dtc)2, which then dimerizes to form
Mo2O2(μ-S)2(dtc)2 with concomitant elimination of thiuram
disulfide. In our system, the new WO ligand could originate
from autoxidation of a sulfido ligand, forming intermediate
sulfur oxide species28,29 with eventual transfer of an oxo
equivalent to tungsten, or through hydrolysis of a sulfido ligand.
We have been unable to ascertain the origin of the oxo group
through spiking experiments. Whatever the source of the oxo
group, it is clear that the generation of 3 results in deactivation of
the SAT catalysts. On the basis of these results, we propose that
catalyst deactivation via the formation of thermodynamically
stable, catalytically inactive oxo species is an intrinsic limitation
of molybdenum/tungsten-based SAT catalysis and that
protection from air may be a general requirement for sustained
catalytic SAT in these systems.
Authors
James P. Ward − School of Chemistry, University of Melbourne,
Victoria 3010, Australia
Patrick J. Lim − Department of Chemistry, University of San
Carlos, Cebu City, Philippines
David J. Evans − School of Chemistry, University of Melbourne,
Victoria 3010, Australia
Jonathan M. White − School of Chemistry and Bio21 Molecular
Science and Biotechnology Institute, University of Melbourne,
Victoria 3010, Australia; orcid.org/0000-0002-0707-
6257
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.inorgchem.0c02915
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank Ms. Sioe See Volaric and Drs. Christian J. Doonan,
Ryan J. Gilbert-Wilson, Victor W.-L. Ng, and Michelle K. Taylor
for experimental assistance. We gratefully acknowledge the
financial support of the Australian Research Council.
DEDICATION
■
Dedicated to Prof. John H. Enemark on the occasion of his 80th
birthday and in recognition of his significant contributions to
inorganic and bioinorganic chemistry.
D
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Dinuclear Tungsten(V) Complex of Dithiolene, (Pr4N)2[W2(μ-
S)2{S2C2(CO2Et)2}4]. J. Organomet. Chem. 2000, 611 (1−2), 370−
375.
REFERENCES
■
(1) Holm, R. H. Metal-centered Oxygen Atom Transfer Reactions.
Chem. Rev. 1987, 87 (6), 1401−1449.
́
(23) Mallard, A.; Simonnet-Jegat, C.; Lavanant, H.; Marrot, J.;
(2) Holm, R. H.; Donahue, J. P. A Thermodynamic Scale for Oxygen
Atom Transfer Reactions. Polyhedron 1993, 12 (6), 571−589.
(3) Young, C. G. Biomimetic Chemistry of Molybdenum. In
Biomimetic Oxidations Catalyzed by Transition Metal Complexes;
Meunier, B., Ed.; Imperial College Press: London, 2000; pp 415−459.
(4) Woo, L. K. Intermetal Oxygen, Sulfur, Selenium, and Nitrogen
Atom Transfer Reactions. Chem. Rev. 1993, 93 (3), 1125−1136.
(5) Donahue, J. P. Thermodynamic Scales for Sulfur Atom Transfer
and Oxo-for-Sulfido Exchange Reactions. Chem. Rev. 2006, 106 (11),
4747−4783.
́
Secheresse, F. Reactivity of Tetrathiometalates with Alkynes. Synthesis
and Characterisation of Dithiolene Complexes of Mo, W, and V by
ESMS and XRD. Transition Met. Chem. 2008, 33 (2), 143−152.
(24) Majumdar, A.; Mitra, J.; Pal, K.; Sarkar, S. Mono-oxo
Bis(dithiolene) Mo(IV)/W(IV) Complexes as Building Blocks for
Sulfide Bridged Bi- and Tri-Nuclear Complexes. Inorg. Chem. 2008, 47
(12), 5360−5364.
(25) Nugent, W. A.; Mayer, J. M. Metal−Ligand Multiple Bonds;
Wiley: New York, 1988.
(26) Parkin, G. Terminal Chalcogenido Complexes of the Transition
Metals. Prog. Inorg. Chem. 2007, 47, 1−165.
(6) Liu, H.; Jiang, X. Transfer of Sulfur: From Simple to Diverse.
Chem. - Asian J. 2013, 8 (11), 2546−2563.
(27) Seo, J.; Shearer, J.; Williard, P. G.; Kim, E. Reactivity of a
Biomimetic W(IV) Bis-dithiolene Complex with CO2 Leading to
Formate Production and Structural Rearrangement. Dalton Trans
2019, 48 (47), 17441−17444.
(7) Young, C. G. Models for the Xanthine Oxidase Family of Enzymes.
In Molybdenum and Tungsten Enzymes: Bioinorganic Chemistry; RSC
Metallobiology Series 6; Hille, R., Schulzke, C. E., Kirk, M. L., Eds.;
Royal Society of Chemistry: Cambridge, U.K., 2017; pp 194−238.
(8) Adam, W.; Bargon, R. M. Molybdenum−catalyzed Episulfidation
of (E)−Cycloalkenes with Elemental Sulfur. Chem. Commun. 2001,
1910−1911.
́
(28) Manoli, J.-M.; Bregeault, J.-M.; Potvin, C.; Chottard, G.
Structural and Spectroscopic Studies of the [Mo2(μ4-S2)(μ2-SO2)-
(CN)8]4− Anion, a Complex With a Mo-Mo Bond and a Distorted
Confacial Bis-bipyramidal Framework. Inorg. Chim. Acta 1984, 88 (1),
75−81.
(9) Adam, W.; Bargon, R. M.; Bosio, S. G.; Schenk, W. A.; Stalke, D.
Direct Synthesis of Isothiocyanates from Isonitriles by Molybdenum-
Catalyzed Sulfur Transfer with Elemental Sulfur. J. Org. Chem. 2002, 67
(20), 7037−7041.
(10) Adam, W.; Bargon, R. M.; Schenk, W. A. Direct Episulfidation of
Alkenes and Allenes with Elemental Sulfur and Thiiranes as Sulfur
Sources, Catalyzed by Molybdenum Oxo Complexes. J. Am. Chem. Soc.
2003, 125 (13), 3871−3876.
(29) Kubas, G. J. Chemical Transformations and Disproportionation
of Sulfur Dioxide on Transition Metal Complexes. Acc. Chem. Res.
1994, 27 (7), 183−190.
(11) Eagle, A. A.; Gable, R. W.; Thomas, S.; Sproules, S. A.; Young, C.
G. Sulfur Atom Transfer Reactions of Tungsten(VI) and Tungsten(IV)
Chalcogenide Complexes. Polyhedron 2004, 23 (2−3), 385−394.
(12) Sugimoto, H.; Tajima, R.; Sakurai, T.; Ohi, H.; Miyake, H.; Itoh,
S.; Tsukube, H. Reversible Sulfurization−Desulfurization of Tungsten
Bis(dithiolene) Complexes. Angew. Chem., Int. Ed. 2006, 45 (21),
3520−3522.
(13) Farrell, W. S.; Zavalij, P. Y.; Sita, L. R. Catalytic Production of
Isothiocyanates via a Mo(II)/Mo(IV) Cycle for the “Soft” Sulfur
Oxidation of Isonitriles. Organometallics 2016, 35 (14), 2361−2366.
(14) Pan, W.-H.; Halbert, T. R.; Hutchings, L. L.; Stiefel, E. I. Ligand
and Induced Internal Redox Transfer Pathways to New Mo−S and W−
S Dithiocarbamate Complexes. J. Chem. Soc., Chem. Commun. 1985,
927−929.
(15) Lim, P. J.; Cook, V. C.; Doonan, C. J.; Young, C. G.; Tiekink, E.
R. T. Transformations Leading to the Generation of Dithiolene Ligands
Initiated by Reactions of Sulfur−Rich WS(S2)(S2CNR2)2 Complexes
with Dimethyl Acetylenedicarboxylate and Phenylacetylene. Organo-
metallics 2000, 19 (26), 5643−5653.
̈
̈
(16) Klingelhofer, P.; Muller, U. Synthesis and Structure of μ-Sulfido-
μ-disulfido-octabromoditungsten(V) Ions [W2S3Br8]2−. Z. Anorg. Allg.
Chem. 1986, 542 (11), 7−12.
(17) Coffey, T. A.; Hogarth, G. Synthesis and Structure of
[Mo2(NR)2(η2-S2CNEt2)(μ-S)(μ-η2-η2-S2)] (R = 2,6-Pri2C6H3): a
Molecular Model for Molybdenum Trisulfide. Polyhedron 1997, 16 (1),
165−169.
(18) Beswick, C. L.; Schulman, J. M.; Stiefel, E. I. Structures and
Structural Trends in Homoleptic Dithiolene Complexes. Prog. Inorg.
Chem. 2004, 52, 55−110.
(19) Hogarth, G. Transition Metal Dithiocarbamates: 1978−2003.
Prog. Inorg. Chem. 2005, 53, 71−561.
(20) Goddard, C. A.; Holm, R. H. Synthesis and Reactivity Aspects of
the Bis(dithiolene) Chalcogenide Series [WIVQ(S2C2R2)2]2− (Q = O,
S, Se). Inorg. Chem. 1999, 38 (23), 5389−5398.
(21) Sung, K.-M.; Holm, R. H. Substitution and Oxidation Reactions
of Bis(dithiolene)tungsten Complexes of Potential Relevance to
Enzyme Sites. Inorg. Chem. 2001, 40 (18), 4518−4525.
(22) Umakoshi, K.; Nishimoto, E.; Sokolov, M.; Kawano, H.; Sasaki,
Y.; Onishi, M. Synthesis, Structure, and Properties of Sulfido-bridged
E
https://dx.doi.org/10.1021/acs.inorgchem.0c02915
Inorg. Chem. XXXX, XXX, XXX−XXX