Bioinspired Nucleophilic Attack on a Tungsten-Bound Acetylene: Formation of Cationic Carbyne and Alkenyl Complexes

Article abstract of DOI:10.1021/acs.inorgchem.1c00643

Inspired by the proposed inner-sphere mechanism of the tungstoenzyme acetylene hydratase, we have designed tungsten acetylene complexes and investigated their reactivity. Here, we report the first intermolecular nucleophilic attack on a tungsten-bound acetylene (C2H2) in bioinspired complexes employing 6-methylpyridine-2-thiolate ligands. By using PMe3 as a nucleophile, we isolated cationic carbyne and alkenyl complexes.

Full text of DOI:10.1021/acs.inorgchem.1c00643

pubs.acs.org/IC
Communication
Bioinspired Nucleophilic Attack on a Tungsten-Bound Acetylene:
Formation of Cationic Carbyne and Alkenyl Complexes
́
Madeleine A. Ehweiner, Lydia M. Peschel, Niklas Stix, Miljan Z. Corovic, Ferdinand Belaj,
́
and Nadia C. Mösch-Zanetti*
Cite This: https://doi.org/10.1021/acs.inorgchem.1c00643
Read Online
ACCESS
Metrics & More
Article Recommendations
*
sı Supporting Information
ABSTRACT: Inspired by the proposed inner-sphere mechanism of the tungstoenzyme acetylene hydratase, we have designed
tungsten acetylene complexes and investigated their reactivity. Here, we report the first intermolecular nucleophilic attack on a
tungsten-bound acetylene (C H ) in bioinspired complexes employing 6-methylpyridine-2-thiolate ligands. By using PMe as a
2
2
3
nucleophile, we isolated cationic carbyne and alkenyl complexes.
he anaerobic bacterium Pelobacter acetylenicus can grow
Scheme 1. Proposed Inner-Sphere Mechanism of the
Hydration of C H Performed by AH: Nucleophilic Attack
of a Hydroxide on Coordinated C H2
2
T
on acetylene (C H ) as a single carbon and energy
2 2
2
2
8
source. Its utilization is performed by the tungstoenzyme
acetylene hydratase (AH), which catalyzes the hydration of
1
−4
acetylene to acetaldehyde.
The coordination sphere of the
tungsten(IV) center in the active site consists of four sulfur
atoms from two molybdopterin cofactors, a thiolate from
5
cysteine, and a water molecule. Although several exper-
5
,6
7−10
imental and computational studies
have been carried out
to shed light on the reaction mechanism, it remains unclear
where C H is located during hydration. Because of lower
2
2
energetic barriers, density functional theory calculations favor a
mechanism where C H replaces the coordinated water and
2
2
subsequently undergoes nucleophilic attack by a hydroxide
7
−10
(
(
Scheme 1).
Apart from investigations on [Et N] [WO-
4 2
1
1−13
mnt) ] (mnt = maleonitriledithiolate),
synthetic ap-
2
proaches to elucidate the mechanism of AH have only included
14,15
systems with tungsten-coordinated C H .
In a recent
2
2
publication, the S,N-bidentate ligand pyridine-2-thiolate (PyS)
was introduced to the tungsten(II) center to model the active
15
site of AH as in Inter1 (Scheme 1). In contrast to previously
14
reported structural model compounds, the coordination of a
second C H and subsequent insertion into the W−N bond
2
2
occurred, showing that a second coordinated C H is
2
2
sufficiently activated to undergo a nucleophilic attack. A
similar behavior was observed in molybdenum and tungsten
complexes, where a nucleophilic attack on one of two
coordinated hexafluorobut-2-yne moieties took place, yielding
[
WBr (CO) (NCMe) ] with 2.1 equiv of Na(6-MePyS) in
2 3 2
CH Cl followed by stirring under a C H atmosphere for 1 h
allowed the isolation of 1 in 86% yield after silica gel filtration.
The intermediately formed tricarbonyl complex [W(CO) (6-
MePyS) ] was characterized by single-crystal X-ray diffraction
analysis (see the Supporting Information). Longer reaction
times led to the insertion of a second C H into the W−N
2
2
2
2
2
16−20
3
a η -vinyl complex.
Our aim is to facilitate an
2
intermolecular nucleophilic attack by inhibiting the coordina-
tion of a second C H and insertion as in the PyS system.
2
2
2
2
Therefore, we anticipated the introduction of a methyl group
next to the coordinating nitrogen atom in PyS (6-MePyS) so
that the metal center is more shielded against the coordination
of a second C H .
Received: March 3, 2021
2
2
For preparation of the redesigned tungsten complex
[
W(CO)(C H )(6-MePyS) ] (1), which contains the desired
2
2
2
6
-MePyS ligands and only one C H , a previously developed
2 2
14,15,21
procedure was modified.
The reaction of
©
XXXX The Authors. Published by
American Chemical Society
https://doi.org/10.1021/acs.inorgchem.1c00643
A
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Communication
Figure 1. Molecular structures of 1 (left), 2 (middle), and 3 (right) with probability ellipsoids drawn at the 50% probability level.
bond forming [W(CO)(C H )(HCCH-6-MePyS)(6-MePyS)]
Scheme 2. Synthesis of Complexes 1−3
2
2
(
2), as previously observed in the unsubstituted analogue
W(CO)(C H )(HCCH-PyS)(PyS)]. However, the addi-
15
[
2
2
tional methyl group significantly decreases intramolecular
insertion because even after 24 h and repeated addition of
C H only partial conversion is observed. Furthermore, in the
2
2
absence of additional C H , 2 reacts reversibly to 1 under the
2
2
elimination of acetylene or polyacetylene depending on the
solvent. Nevertheless, we were able to isolate 2 and
unambiguously confirm its structure by single-crystal X-ray
diffraction analysis (Figure 1) and by spectroscopic means. In
CD Cl , the sterically hindered C H protons of 1 resonate at
2
2
2
2
1
2
3.77 and 12.50 ppm and the carbon atoms at 205.73 and
04.14 ppm, suggesting that C H acts as a four-electron
2
2
2
2
1
2
donor. In H NMR spectra of 2 recorded in CD Cl , the η -
2
2
than that in 1 [1.306(7) Å], while the W−C bonds [W1−C1
of 2.022(5) Å for 1 vs 2.0693(15) Å for 3 and W1−C2 of
2.055(3) Å for 1 vs 2.1027(15) Å for 3] are essentially longer.
With compounds 1 and 3 exhibiting related structures but
different oxidation states of the metal center, a nucleophilic
attack of PMe on the coordinated C H was investigated. Of
C H protons appear as singlets at 12.90 and 12.03 ppm. The
2
2
protons of the inserted C H couple with each other thus
2
2
3
183
appear as doublets ( J = 10.9 Hz) flanked with W satellites
at 7.61 and 6.89 ppm. IR spectra of 1 and 2 show strong CO
−
1
bands at 1891 and 1897 cm , respectively. Single-crystal X-ray
diffraction analyses of 1 and 2 revealed almost identical W−
C1, W−C2, and C1−C2 bond distances (Figure 1) compared
to the literature values of tungsten(II) acetylene com-
3
2
2
particular interest to us was the potential formation of the
intermediate Inter2 (Figure 1). Treatment of a CH Cl
2
2
solution of 1 with 3 equiv of PMe led to an immediate
3
2
3,24
plexes.
The inserted C H in 2 is strongly activated and
2 2
color change from purple to orange-brown and full conversion
of the starting material. An X-ray diffraction study on single
crystals grown from a CH Cl /heptane solution revealed the
therefore has more ethylene character with a C−C bond length
2
of 1.349(3) Å compared to 1.310(3) Å in η -acetylene.
2
2
Compared to the unsubstituted analogue [W(CO)(C H )-
product to be an ion pair consisting of the tungsten carbyne
2
2
+
(
PyS) ] with W−N distances of 2.161 and 2.212 Å, 1 exhibits
complex [W(CO)(CCH PMe )(PMe ) (6-MePyS)] (4) and
2
2
3
3 2
15
slightly longer bonds [2.197(3) and 2.259(4) Å]. As was
already observed in [MoO (6-MePyS) ], the nitrogen atom in
a chloride deriving from the solvent (Figure 2). Indeed, a
nucleophilic attack of PMe at the coordinated C H under the
2
2
3
2
2
6
-MePyS is not able to bind to the metal center as tightly as it
formation of a P−C bond had occurred. However, the attack
also leads to the cleavage of one 6-MePyS, which reacts with
CH Cl to form 2-((chloromethyl)thio)-6-methylpyridine (6-
does in the unsubstituted version because of the methyl group
in the ortho position.
25
2
2
−
Considering that the tungsten center in AH is in the
oxidation state +IV, we oxidized 1 with pyridine N-oxide to
obtain the tungsten(IV) complex [WO(C H )(6-MePyS) ]
MePySCH Cl) and Cl . The coordination surrounding of
2
tungsten is completed by two PMe ligands preserving the
3
−
2
2
2
18e character of the complex and explaining the need for 3
(
3) according to Scheme 2. After filtration to remove insoluble
equiv of phosphine. After workup, pure 4 was obtained in 50%
yield (Scheme 3).
byproducts, 3 was crystallized in 84% yield. IR spectra show
−
1
14,26−28
The formation of 4 is also confirmed by 1H NMR
one strong band indicative of ν(WO) at 924 cm .
1
The H NMR spectrum of 3 in CD Cl shows two equally
spectroscopy, where the CH protons appear at 3.81 ppm as
2
2
2
sharp singlets flanked with 1 W satellites for the C H protons
83
2
4
a doublet of triplets ( J = 19.4 Hz; J = 5.9 Hz) and the
2
2
HP HP
at 11.23 and 10.99 ppm. Thus, they are shifted upfield
methyl groups of the two tungsten-coordinated PMe3
molecules at 1.44 ppm and those of the carbon-bound PMe3
at 2.12 ppm. To confirm that the carbyne carbon atom as well
as the adjacent methylene group indeed derive from the
coordinated C H , 1 was resynthesized using C D to generate
1
3
compared to 1. The same trend is observed in the C NMR
spectrum, with resonances at 159.69 and 159.05 ppm being
29
characteristic of a two- or three-electron-donor alkyne. Single
crystals suitable for X-ray diffraction analysis were grown from
a CH Cl /heptane solution. A molecular view of 3 is displayed
2
2
2
2
[W(CO)(C D )(6-MePyS) ] (1D). Upon reaction of 1D with
2
2
2
2
2
in Figure 1. The C1−C2 bond [1.279(2) Å] is slightly shorter
PMe , the signal at 3.81 ppm is absent, confirming a reaction of
3
B
https://doi.org/10.1021/acs.inorgchem.1c00643
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Communication
Scheme 3. Reaction of 1 and 3 with 3 equiv of PMe in
3
CH Cl to Yield 4 and 5, Respectively
2
2
30
the coordinated C H and no participation of CH Cl . While
2
2
2
2
Cummins et al. reported the reaction of a molybdenum-bound
2
(
trimethylsilyl)acetylene with Li[BHEt ] to a η -vinyl complex
3
and the subsequent formation of carbyne only after heating to
2
8
0 °C for several hours, the η -vinyl intermediate does not
31
seem to be stable at all in our case. It is only observed in the
H NMR spectrum when a reaction of 1 is carried out with less
1
than 3 equiv of PMe directly in a J. Young NMR tube. The
3
3
1
1
P{ H} NMR spectrum of 4 shows a triplet at 19.87 ppm for
the carbon-bound PMe and a doublet at −17.94 ppm being
3
1
83
1
flanked with W satellites ( J = 277.8 Hz) for the tungsten-
bound PMe . In the C NMR spectrum, the methylene carbon
resonates at 46.80 ppm (d, J = 49.5 Hz). CO (q at 250.98
WP
13
3
1
Figure 2. Molecular structures of 4 (top) and 5 (bottom) with
probability ellipsoids drawn at the 30% (4) and 50% (5) probability
levels, respectively.
CP
ppm) and WC (dt at 249.22 ppm) carbon atoms give signals
of a similar shift and coupling pattern and could only be
distinguished by heteronuclear multiple-bond correlation
coordinated C H had occurred, forming a P−C bond. In
(
HMBC) between the carbyne carbon and methylene protons.
2
2
contrast to 4, however, 5 remains with a coordinated ethenyl
ligand exhibiting a W−C single bond. Similar reactions were
The WC resonance is similar to that of [W(CCH )-
3
32
(
PMe ) Cl] (253.3 ppm) but shifted upfield compared to
3 4
already performed with chromium(0)-bound C H ; however,
those of similar compounds like [W(CCH Ph)(CO) (dppe)-
2
2
2
2
33
treatment with PMe predominantly led to an exchange with
Cl] (276.3 ppm), [Tp′(CO) WCCH W(CO)(C Ph )Tp]
3
2
2
2
2
45
3
4
the coordinated C H . The ethenyl protons of 5 are clearly
(
312 ppm), and [Mo(CCH B(C F ) )(dppe) ] (347.0
2
2
2
6
5
3
2
3
5
1
1
identified by H NMR spectroscopy with resonances at 11.42
and 4.26 ppm and coupling to each other with J = 17.5 Hz.
ppm). The byproduct 6-MePySCH Cl was identified by H
2
3
NMR and mass spectroscopy. When the reaction was carried
out in CD Cl , the singlet for the methylene protons was
Upon reaction of [WO(C D )(6-MePy ) ] (3D) with PMe in
2
2
S 2
3
2
2
CD Cl , the ethenyl proton resonances are absent. The
absent. To a lesser extent, also bis((6-methylpyridin-2-
yl)thio)methane [(6-MePyS) CH ] was found, which was
2
2
3
1
1
P{ H} NMR spectrum of 5 shows two rather broad singlets
2
2
formed by the reaction of another 6-MePyS with the formerly
at 4.73 and −22.14 ppm, with the latter being flanked with
1
83
generated 6-MePySCH Cl. The W−C bond length of 1.793(4)
W satellites. The ethenyl carbon bound to the tungsten
2
Å in 4 confirms the triple-bond character, yet falls toward the
shorter end of WC distances in recently published carbyne
center resonates at 222.99 ppm and thus exhibits a significant
downfield shift compared to the literature. The other gives a
doublet at 96.83 ppm and is thus considerably shifted upfield
3
6−42
complexes (ca. 1.76−1.86 Å).
The W1−C1−C2 angle of
4
6,47
1
79.4(4)° is almost perfectly linear, and the C1−C2 distance
compared to similar compounds.
The W−C distance of
43
of 1.486(6) Å indicates a single bond. The P1−C2 bond
2.068(3) Å is shorter than that in rare examples of tungsten
46
[
1.795(4) Å] is slightly longer than the other three P1−C
ethenyl complexes like [WO (CHCH )(Tp′)] (2.136 Å)
2 1 2
2
2
bonds [1.761(5)−1.779(5) Å] but shorter than the remaining
P−C bonds [1.807(6)−1.827(4) Å]. The W−S bond
and [W(Cp)(CHCHC(CH ) )(η -C(O)NR R )(NO)]
3 3
47
(2.161 Å), while the C1−C2 distance of 1.363(4) Å is
slightly longer compared to the aforementioned compounds
(1.305 and 1.332 Å). The W1−C1−C2 [135.8(2)°] and C1−
[
2.6605(16) Å] is considerably longer than those in 1 [W1−
S1 2.5834(12) Å; W1−S2 2.4073(12) Å], indicating a strong
44
2
trans influence of the carbyne ligand.
Treatment of a CH Cl solution of 3 with 3 equiv of PMe
3
C2−P1 [123.4(2)°] angle confirm a slight deviation from sp
hybridization on the carbon atoms. In contrast to 4, the P1−
C2 bond [1.745(3) Å] is slightly shorter than the other three
P1−C bonds [1.774(3)−1.796(3) Å].
2
2
led to an immediate color change from light yellow to dark
green. After workup, the ethenyl complex [WO(CHCHPMe )-
3
(
PMe ) (6-MePyS)]Cl (5; Scheme 3) was isolated in 90%
In conclusion, we report the synthesis of tungsten acetylene
complexes where intramolecular insertion of C H into the
3
2
yield as a black-green crystalline powder. Its structure was
unambiguously identified by single-crystal X-ray diffraction
analysis (Figure 2). Again, a nucleophilic attack at the
2
2
W−N bond is prevented by steric adjustment at the ancillary
ligand. This allowed the investigation of an intermolecular
C
https://doi.org/10.1021/acs.inorgchem.1c00643
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Communication
nucleophilic attack at the solely coordinated C H using PMe .
Notes
2
2
3
Starting from the tungsten(II) complex 1, a tungsten
ethylidyne complex is formed; hence, the four-electron-donor
C H converts to the four-electron-donor carbyne when
The authors declare no competing financial interest.
†
Email: madeleine.ehweiner@uni-graz.at.
‡
2
2
Email: lydia.peschel@uni-graz.at.
§
assuming retention of the metal oxidation state. When the
carbyne is considered to be a six-electron donor, oxidation to
tungsten(IV) is formally taking place. Regarding the oxido
ligand as a six-electron donor, the two-electron-donor C H in
Email: niklas.stix@edu.uni-graz.at.
⊥
Email: miljan.corovic@uni-graz.at.
∥
Email: ferdinand.belaj@uni-graz.at.
2
2
the tungsten(IV) complex 3 converts to a two-electron-donor
REFERENCES
■
ethenyl moiety. In both cases, the reactions proceed under
−
(1) ten Brink, F. Living on acetylene. Met. Ions Life Sci. 2014, 14,
preservation of the 18e character of the complexes. One 6-
1
5−35.
MePyS ligand is cleaved under reaction with CH Cl to form
2
2
(
2) Meckenstock, R. U.; Krieger, R.; Ensign, S.; Kroneck, P. M. H.;
−
6
-MePySCH Cl and the counterion Cl for the cationic
2
Schink, B. Acetylene hydratase of Pelobacter acetylenicus. Eur. J.
Biochem. 1999, 264, 176−182.
tungsten complexes; thus, the presence of CH Cl is crucial.
2
2
We assume that cleavage of the sulfur ligand relieves the charge
at tungsten accumulated as a result of the nucleophilic attack.
The attack of PMe on the tungsten(IV)-bound C H to form
(3) Rosner, B. M.; Schink, B. Purification and Characterization of
Acetylene Hydratase of Pelobacter acetylenicus, a Tungsten Iron-
Sulfur Protein. J. Bacteriol. 1995, 177, 5767−5772.
3
2
2
(
4) Schink, B. Fermentation of acetylene by an obligate anaerobe,
an ethenyl ligand resembles the step in which the Inter2
intermediate of the proposed mechanism of AH is formed.
Pelobacter acetylenicus sp. nov. Arch. Microbiol. 1985, 142, 295−301.
5) Seiffert, G. B.; Ullmann, G. M.; Messerschmidt, A.; Schink, B.;
(
Kroneck, P. M. H.; Einsle, O. Structure of the non-redox-active
tungsten/[4Fe:4S] enzyme acetylene hydratase. Proc. Natl. Acad. Sci.
U. S. A. 2007, 104, 3073−3077.
ASSOCIATED CONTENT
sı Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.inorgchem.1c00643.
■
*
(6) ten Brink, F.; Schink, B.; Kroneck, P. M. H. Exploring the active
site of the tungsten, iron-sulfur enzyme acetylene hydratase. J.
Bacteriol. 2011, 193, 1229−1236.
Experimental details, syntheses, crystallographic data,
and NMR spectra of all compounds (PDF)
(7) Liao, R.-Z.; Himo, F. Theoretical Study of the Chemoselectivity
of Tungsten-Dependent Acetylene Hydratase. ACS Catal. 2011, 1,
37−944.
8) Liao, R.-Z.; Yu, J.-G.; Himo, F. Mechanism of tungsten-
9
(
Accession Codes
CCDC 2050311−2050316 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
dependent acetylene hydratase from quantum chemical calculations.
Proc. Natl. Acad. Sci. U. S. A. 2010, 107, 22523−22527.
(9) Vincent, M. A.; Hillier, I. H.; Periyasamy, G.; Burton, N. A. A
DFT study of the possible role of vinylidene and carbene
intermediates in the mechanism of the enzyme acetylene hydratase.
Dalton Trans. 2010, 39, 3816−3822.
(10) Antony, S.; Bayse, C. A. Theoretical Studies of Models of the
Active Site of the Tungstoenzyme Acetylene Hydratase. Organo-
metallics 2009, 28, 4938−4944.
AUTHOR INFORMATION
Corresponding Author
Nadia C. Mösch-Zanetti − Institute of Chemistry, Inorganic
Chemistry, University of Graz, 8010 Graz, Austria;
orcid.org/0000-0002-1349-6725;
■
(11) Das, S. K.; Biswas, D.; Maiti, R.; Sarkar, S. Modeling the
Tungsten Sites of Inactive and Active Forms of Hyperthermophilic
Pyrococcus furiosus Aldehyde Ferredoxin Oxidoreductase. J. Am.
Chem. Soc. 1996, 118, 1387−1397.
(
12) Yadav, J.; Das, S. K.; Sarkar, S. A Functional Mimic of the New
Class of Tungstoenzyme, Acetylene Hydratase. J. Am. Chem. Soc.
997, 119, 4315−4316.
13) Schreyer, M.; Hintermann, L. Is the tungsten(IV) complex
NEt ) WO(mnt) a functional analogue of acetylene hydratase?
Email: nadia.moesch@uni-graz.at
1
Authors
(
Madeleine A. Ehweiner − Institute of Chemistry, Inorganic
Chemistry, University of Graz, 8010 Graz, Austria
Lydia M. Peschel − Institute of Chemistry, Inorganic
Chemistry, University of Graz, 8010 Graz, Austria
Niklas Stix − Institute of Chemistry, Inorganic Chemistry,
University of Graz, 8010 Graz, Austria
(
4
2
2
Beilstein J. Org. Chem. 2017, 13, 2332−2339.
(14) Peschel, L. M.; Belaj, F.; Mösch-Zanetti, N. C. Towards
Structural-Functional Mimics of Acetylene Hydratase: Reversible
Activation of Acetylene using a Biomimetic Tungsten Complex.
Angew. Chem., Int. Ed. 2015, 54, 13018−13021.
́
Miljan Z. Corovic
́
− Institute of Chemistry, Inorganic
(15) Vidovic, C.; Peschel, L. M.; Buchsteiner, M.; Belaj, F.; Mösch-
̌
Chemistry, University of Graz, 8010 Graz, Austria
Ferdinand Belaj − Institute of Chemistry, Inorganic Chemistry,
University of Graz, 8010 Graz, Austria
Zanetti, N. C. Structural Mimics of Acetylene Hydratase: Tungsten
Complexes Capable of Intramolecular Nucleophilic Attack on
Acetylene. Chem. - Eur. J. 2019, 25, 14267−14272.
(
16) Abu Bakar, W. A. W.; Carlton, L.; Davidson, J. L.; Manojlovic-
́
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.inorgchem.1c00643
Muir, L.; Muir, K. W. Metal-promoted insertion and cyclisation
reactions of alkynes. J. Organomet. Chem. 1988, 352, C54−C58.
(
17) Davidson, J. L.; Wilson, W. F.; Manojlovic-Muir, L.; Muir, K.
́
2
Author Contributions
The manuscript was written through contributions of all
authors.
W. Isomerism and fluxional beviour in η -vinyl complexes resulting in
inversion of configuration at an asymmetric carbon atom. J.
Organomet. Chem. 1983, 254, C6−C10.
(18) Davidson, J. L.; Green, M.; Stone, F. G. A.; Welch, A. J.
Funding
Syntheses involving Co-ordinatively Unsaturated Cyclopentadienyl-
molybdenum and -tungsten Complexes. J. Chem. Soc., Dalton Trans.
1977, 287−294.
Financial support by the Austrian Science Fund (Grant
P31583) and NAWI Graz is gratefully acknowledged.
D
https://doi.org/10.1021/acs.inorgchem.1c00643
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Communication
(
19) Davidson, J. L.; Vasapollo, G.; Manojlovic-
́
Muir, L.; Muir, K.
(37) Dewhurst, R. D.; Hill, A. F.; Willis, A. C. The Interplay of
Bis(tricarbido) and Dimetallaoctatetrayne Complexes of Platinum.
Organometallics 2009, 28, 4735−4740.
W. Stabilisation of Vinylic Intermediates in the Addition, cyclisation
and Oligomerisation Reactions of Alkynes by Co-ordination to
Molybdenum and Tungsten. J. Chem. Soc., Chem. Commun. 1982, 0,
(38) Frogley, B. J.; Hill, A. F. Flexible Platinum(0) Coordination to a
Ditungsten Ethanediylidyne. Angew. Chem., Int. Ed. 2019, 58, 8044−
1
(
025−1027.
8
048.
20) Davidson, J. L.; Murray, I. E. P.; Preston, P. N.; Russo, M. V.;
́
Manojlovic-Muir, L.; Muir, K. W. Formation of novel η -vinyl
complexes by nucleophilic attack at co-ordinated hexafluorobut-2-yne;
implications for the stereochemistry of addition and insertion
reactions of co-ordinated acetylenes. J. Chem. Soc., Chem. Commun.
2
(39) Caldwell, L. M. Alkylidyne Complexes Ligated by Poly-
(
pyrazolyl)borates. Adv. Organomet. Chem. 2008, 56, 1−94.
(
40) Tonzetich, Z. J.; Lam, Y. C.; Muller, P.; Schrock, R. R. Facile
̈
Synthesis of a Tungsten Alkylidyne Catalyst for Alkyne Metathesis.
Organometallics 2007, 26, 475−477.
1
(
981, 20, 1059−1061.
(41) Hill, A. F.; Kong, R. Y. High oxidation state bromocarbyne
21) Peschel, L. M.; Vidovic, C.; Belaj, F.; Neshchadin, D.; Mösch-
̌
complexes. Chem. Commun. 2017, 53, 759−762.
42) Han, Y.-S.; Hill, A. F.; Kong, R. Y. An unusual alkylidyne
homologation. Chem. Commun. 2018, 54, 2292−2295.
43) Yang, Y.; Fu, X.; Chen, J.; Zhai, H. Total synthesis of
−)-jiadifenin. Angew. Chem., Int. Ed. 2012, 51, 9825−9828.
44) Colebatch, A. L.; Hill, A. F. Coordination chemistry of
Zanetti, N. C. Activation and Photoinduced Release of Alkynes on a
Biomimetic Tungsten Center: The Photochemical Behavior of the W-
S-Phoz System. Chem. - Eur. J. 2019, 25, 3893−3902.
(
(
(
22) Templeton, J. L. Four-Electron Alkyne Ligands in
(
Molybdenum(II) and Tungsten(II) Complexes. Adv. Organomet.
Chem. 1989, 29, 1−100.
23) Ricard, L.; Weiss, R.; Newton, W. E.; Chen, G. J.-J.; McDonald,
J. W. Binding and Activation of Enzymatic Substrates by Metal
Complexes. 4. Structural Evidence for Acetylene as a Four-Electron
Donor in W(CO)(C H )(S CNEt ) . J. Am. Chem. Soc. 1978, 100,
(
phosphinocarbynes: phosphorus vs. carbyne site selectivity. Dalton
Trans. 2017, 46, 4355−4365.
(
(
45) Alt, H. G.; Engelhardt, H. E.; Filippou, A. C. Acetylen als
Baustein fur Carben- und Vinylidenliganden am Chrom. J. Organomet.
Chem. 1988, 355, 139−148.
̈
2
2
2
2 2
1
(
318−1320.
(46) Crane, T. W.; White, P. S.; Templeton, J. L. Deprotonation of
Cationic Tungsten(IV) Aqua−Oxo−Alkyne Complexes To Form
Dioxo−Vinyl Tungsten(VI) Complexes. Inorg. Chem. 2000, 39,
24) Helmdach, K.; Ludwig, S.; Villinger, A.; Hollmann, D.; Kösters,
J.; Seidel, W. W. Synthesis and activation potential of an open shell
diphosphine. Chem. Commun. 2017, 53, 5894−5897.
25) Ehweiner, M. A.; Wiedemaier, F.; Belaj, F.; Mösch-Zanetti, N.
1081−1091.
(47) Ipaktschi, J.; Uhlig, S.; Du
2
(
̈
lmer, A. η -Alkynyl and Vinylidene
C. Oxygen Atom Transfer Reactivity of Molybdenum(VI) Complexes
Transition Metal Complexes. Organometallics 2001, 20, 4840−4846.
Employing Pyrimidine- and Pyridine-2-thiolate Ligands. Inorg. Chem.
2
(
020, 59, 14577−14593.
26) Maatta, E. A.; Wentworth, R. A. D.; Newton, W. E.; McDonald,
J. W.; Watt, G. D. Reversible binding of acetylene by oxobis-
diethyldithiocarbamate)molybdenum. J. Am. Chem. Soc. 1978, 100,
320−1321.
27) Maatta, E. A.; Wentworth, R. A. D. Simple alkyne adducts of
(
1
(
MoO(S CNR ) . Inorg. Chem. 1979, 18, 524−526.
2
2
2
(
28) Vidovic,
̌
C.; Belaj, F.; Mösch-Zanetti, N. C. Soft Scorpionate
Hydridotris(2-mercapto-1-methylimidazolyl) borate) Tungsten-
Oxido and -Sulfido Complexes as Acetylene Hydratase Models.
Chem. - Eur. J. 2020, 26, 12431−12444.
(29) Ward, B. C.; Templeton, J. L. Nuclear Magnetic resonance
Studies of Alkynes as Four-Electron Donor Ligands in Monomeric
Tungsten(II) Complexes. J. Am. Chem. Soc. 1980, 102, 1532−1538.
(30) Furstner, A.; Mathes, C.; Lehmann, C. W. Alkyne Metathesis:
̈
Development of a Novel Molybdenum-Based Catalyst System and Its
Application to the Total Synthesis of Epothilone A and C. Chem. -
Eur. J. 2001, 7, 5299−5317.
(31) Tsai, Y.-C.; Diaconescu, P. L.; Cummins, C. C. Facile Synthesis
of Trialkoxymolybdenum(VI) Alkylidyne Complexes for Alkyne
Metathesis. Organometallics 2000, 19, 5260−5262.
(32) Atagi, L. M.; Critchlow, S. C.; Mayer, J. M. Formation of
tungsten-carbyne and tungsten-oxo-allyl complexes on reaction of
WCl (PR ) with unsaturated silanes. J. Am. Chem. Soc. 1992, 114,
2
3 4
1
(
483−1484.
33) Birdwhistell, K. R.; Burgmayer, S. J. N.; Templeton, J. L.
Tungsten vinylidenes and carbynes from terminal alkyne reagents. J.
Am. Chem. Soc. 1983, 105, 7789−7790.
(
34) Woodworth, B. E.; White, P. S.; Templeton, J. L.
Deprotonation and Oxidation of the WCCH −W Bridge To
2
Form a C -Biscarbyne WC−CW Bridge. J. Am. Chem. Soc. 1998,
2
1
(
20, 9028−9033.
35) Stennett, T. E.; Haddow, M. F.; Wass, D. F. Alkene to carbyne:
tandem Lewis acid activation and dehydrogenation of a molybdenum
ethylene complex. Angew. Chem., Int. Ed. 2013, 52, 11356−11359.
(36) Dewhurst, R. D.; Hill, A. F.; Smith, M. K. Heterobimetallic C3
complexes through silylpropargylidyne desilylation. Angew. Chem., Int.
Ed. 2004, 43, 476−478.
E
https://doi.org/10.1021/acs.inorgchem.1c00643
Inorg. Chem. XXXX, XXX, XXX−XXX