Coordination and oligomerization of alkynes at mononuclear tungsten aryloxide metal centers

Kriley, Charles E.; Kerschner, Judith L.; Fanwick, Phillip E.; Rothwell, Ian P.

doi:10.1021/om00030a014

Cited by 32 publications

(8 citation statements)

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“…The C–C bond lengths within the C 4 unit ranging from 1.412(2) to 1.447(3) Å are very similar, excluding an interpretation as rhenacyclopentadiene. Similar metallacyclopentatrienes have already been described for Mo(II), , W(II), and V(I) . Interestingly, all these examples and the Re(III) complex 4 + share the d 4 electron configuration.…”

Section: Results and Discussionsupporting

confidence: 71%

Spontaneous Formation of an η⁴-Ethylene Bis(carbene) Ligand by Alkyne Coupling at Rhenium(III)

et al. 2015

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The C/C coupling activity of the cationic Re(III) species [(C5H5)ReBr]+ with different heteroatom-substituted alkynes was investigated. By using the sulfide-substituted bis(benzylsulfanyl)acetylene an unprecedented rhenacyclopentatriene complex was obtained. An XRD structure determination of [(C5H5)ReBr(CSBn)4]+ uncovered the coordination of the remote ethylene moiety at Re leading to an η4-coordination mode of the C4(SBn)4 ligand and a folded five-membered metallacycle. In contrast, reaction of the monoalkyne complex [(C5H5)ReBr(CSBn)2]+ with diphenylacetylene as well as diiodoacetylene led to the mixed bis(alkyne) complexes. The different behavior is attributed to kinetic reasons according to DFT calculations. XRD as well as IR studies with the cationic bis(alkyne) complexes [(C5H5)ReBr(CSBn)2(C2Ph2)]+ and [(C5H5)ReBr(CSBn)2(C2I2)]+ revealed clear differences in the bond strengths of the coordinated alkynes at the same metal center. Further investigations on the coupling activity resulted in addition products with H2O and a trimerization of two diphenylacetylene molecules and one bis(benzylsulfanyl)acetylene, both as byproducts and involved in a sulfide bond cleavage.

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Section: Results and Discussionsupporting

confidence: 71%

Spontaneous Formation of an η⁴-Ethylene Bis(carbene) Ligand by Alkyne Coupling at Rhenium(III)

et al. 2015

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“…Complex 6 contains a metallacyclopentatriene, with an η 4 (6e) ligand derived from the diphenylacetylene and two of the isocyanide ligands. Several metallacyclopentatrienes have been reported, although only one system contains a six-electron donor ligand such as that in 6 . In all previous studies the organic part of the ring is planar, giving the metallacycle either a planar or envelope configuration; in every case, each of the two terminal carbon atoms of the ring donates two electrons to the metal.…”

Section: Discussionmentioning

confidence: 99%

Ligand-Induced and Reductively Induced Alkyne−Isocyanide Coupling Reactions of [Mo(CNBu^t)₃(PhC⋮CPh)(η⁵-C₅Me₅)][BF₄]

et al. 2002

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The complex [Mo(CO)(PhC⋮CPh)2(η5-C5Me5)][BF4] reacts with 3 equiv of CNBut to yield the mixed alkyne−isocyanide complex [Mo(CNBut)3(PhC⋮CPh)(η5-C5Me5)][BF4], 1. Reaction of 1 with a fourth equivalent of CNBut generates [Mo{C(NHBut)C(Ph)C(Ph)CN}(CNBut)2(η5-C5Me5)][BF4], 2, containing an η3-vinylcarbene ligand formed from the coupling of two of the coordinated isocyanide ligands with the diphenylacetylene, with concomitant protonation of one of these isocyanide fragments and dealkylation of the other. Complex 2 may be deprotonated to give [Mo{C(NBut)C(Ph)C(Ph)CN}(CNBut)2(η5-C5Me5)], 3. Protonation of 1 with HBF4·Et2O generates [Mo{C(Ph)C(Ph)CNHBut}(CNBut)2(η5-C5Me5)][BF4]2, 4, by inducing the coupling of a protonated isocyanide ligand with diphenylacetylene, and 4 reacts with CNBut to give 2. A similar reaction of 4 with P(OMe)3 generates [Mo{C(NHBut)C(Ph)C(Ph)CN}(CNBut){P(OMe)3}(η5-C5Me5)][BF4], 5, involving the same coupling and elimination pattern. The diphenylacetylene and CNBut ligands of 1 may also be reductively coupled. Thus, treatment of 1 with sodium−mercury amalgam and subsequent protonation with HBF4·Et2O gives the metallacyclopentatriene-like [Mo{C(NHBut)C(Ph)C(Ph)C(NHBut)}(CNBut)(η5-C5Me5)][BF4], 6, or [Mo{C(NHBut)C(Ph)C(Ph)CH−NHBut}(CNBut)(η5-C5Me5)][BF4], 7, depending upon the solvent. Complex 7 contains an N-protonated η4-monoazadiene ligand with a pendant carbene functionality that is also coordinated to the metal. The crystal structures of 1, 2, 3, 6, and 7 have been determined.

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“…The structures of three Brønsted acidic tungsten acetylene derivatives are shown in the ball and stick models in Figures 2-4 The W-C CtC and CtC bond lengths found in 5s2.031(24) and 1.238(31) Å, respectivelysinitially seem different from the related distances in 1b and 2, but these bond lengths are also well within the range observed for isoelectronic W(η 2 -R 2 C 2 ) and Mo(η 2 -R 2 C 2 ) species. [53][54][55][56][57][58][59][60][61] We might expect to see greater variations in bonding between the acetylene and tungsten when there are actual changes in the valence electron count at tungsten. There is an apparent trend toward lengthening of the CtC bonds in a pair of previously isolated d 3 and d 4 phosphine-substituted tungsten acetylene complexes, which could be explained by increasing backdonation into the π* orbitals of the acetylene.…”

Section: T H Imentioning

confidence: 99%

Supramolecular Assemblies Involving Organometallic Free Acids

et al. 1996

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Reactions between W(η2-Ph2C2)Cl4 and salicylic acid derivatives generate analytically pure free acids of formula W(η2-Ph2C2)Cl3(Hsal-R) (1) in high yields (Hsal = a salicylate monoanion). The products exist as hydrogen-bonded dimers in the solid state. The acid functionality on one molecule hydrogen bonds to one of the cis-chloride ligands of an adjacent complex at a 3.03 Å distance. The more electron-rich tungsten center renders these acetylene complexes less acidic than their oxo and arylimido analogs. As a result, W(η2-Ph2C2)Cl3(Hsal) exhibits partial dimerization in solution and have relatively weak hydrogen bonds to nitrogen- and oxygen-containing organic molecules. Among a range of possible phenol−phenoxide complexes of the W(η2-Ph2C2)Cl3 subunit, only the ether adduct of the catecholate, W(η2-Ph2C2)Cl3(Hcat···OEt2) (2), has been isolated and structurally characterized. The weaker hydrogen bond strength of larger chelating bis(phenolates) evidently destabilize the phenol−phenoxide structures in favor of simple chelating bis(phenoxides). The salicylate free acids form various supramolecular complexes in solution and the solid state, including [W(η2-Ph2C2)Cl3(Hsal)]4(18-crown-6) (5), one of a family of tetranuclear systems organized around hydrogen bonding to an 18-crown-6 template. This structure is characterized by π-stacking of the Hsal ligands between confacial free acid complexes and the steric screening of the two non-hydrogen-bonded 18-crown-6 oxygens by pairs of antarafacial W(Ph2C2) units.

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Coordination and oligomerization of alkynes at mononuclear tungsten aryloxide metal centers

Cited by 32 publications

References 1 publication

Spontaneous Formation of an η⁴-Ethylene Bis(carbene) Ligand by Alkyne Coupling at Rhenium(III)

Spontaneous Formation of an η⁴-Ethylene Bis(carbene) Ligand by Alkyne Coupling at Rhenium(III)

Ligand-Induced and Reductively Induced Alkyne−Isocyanide Coupling Reactions of [Mo(CNBu^t)₃(PhC⋮CPh)(η⁵-C₅Me₅)][BF₄]

Supramolecular Assemblies Involving Organometallic Free Acids

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Coordination and oligomerization of alkynes at mononuclear tungsten aryloxide metal centers

Cited by 32 publications

References 1 publication

Spontaneous Formation of an η4-Ethylene Bis(carbene) Ligand by Alkyne Coupling at Rhenium(III)

Spontaneous Formation of an η4-Ethylene Bis(carbene) Ligand by Alkyne Coupling at Rhenium(III)

Ligand-Induced and Reductively Induced Alkyne−Isocyanide Coupling Reactions of [Mo(CNBut)3(PhC⋮CPh)(η5-C5Me5)][BF4]

Supramolecular Assemblies Involving Organometallic Free Acids

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Spontaneous Formation of an η⁴-Ethylene Bis(carbene) Ligand by Alkyne Coupling at Rhenium(III)

Spontaneous Formation of an η⁴-Ethylene Bis(carbene) Ligand by Alkyne Coupling at Rhenium(III)

Ligand-Induced and Reductively Induced Alkyne−Isocyanide Coupling Reactions of [Mo(CNBu^t)₃(PhC⋮CPh)(η⁵-C₅Me₅)][BF₄]