Direct functionalisation of σ-aryl ligands: preparation of homoleptic functionalised aryls of osmium(iv)

Lau, Man-Kit; Zhang, Qian‐Feng; Chim, Joyce L.C.; Wong, Wing Tak; Leung, Wa‐Hung

doi:10.1039/b104075h

Cited by 17 publications

(12 citation statements)

References 10 publications

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“…bromination or acylation) without cleavage of the Os À C aryl s bond has been reported by Lau et al [26] Regioselective bromination of the para positions on each of the four 2,5-dimethylphenyl ligands of complex 8 (Scheme 3) has been carried out by reaction with pyridinium tribromide in the presence of a catalytic amount of iron powder. The resultant homoleptic tetrakis-(bromoaryl)osmium compound 11, which can be used to synthesize organometallic oligomers/polymers, has proven to be a good starting material for metal-catalyzed cross-coupling reactions.…”

Section: Angewandte Chemiementioning

confidence: 96%

“…Treatment of 23 a with nBuLi gave intermediate 24, which underwent further reactions typical of aryllithium reagents (Scheme 6). [30] This constitutes a valuable route to the introduction of a wide range of functional groups (see complexes [25][26][27].…”

Section: Regioselective Electrophilic Substitution Of Heterocyclic Pomentioning

confidence: 99%

“…The resultant homoleptic tetrakis-(bromoaryl)osmium compound 11, which can be used to synthesize organometallic oligomers/polymers, has proven to be a good starting material for metal-catalyzed cross-coupling reactions. [26] It undergoes Suzuki coupling with 4-XC 6 H 4 B(OH) 2 (X = F, tBu, NH 2 , CO 2 H) in the presence of [Pd(PPh 3 ) 4 ] to afford the respective osmium complexes 12.…”

Section: Angewandte Chemiementioning

confidence: 99%

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Organic Transformations on σ‐Aryl Organometallic Complexes

et al. 2007

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This work reviews recent developments in the field of organic transformations on sigma-aryl organometallic complexes. The general notion that M--C sigma bonds are kinetically labile, highly reactive, and incompatible with typical reaction conditions met in organic synthesis has limited the use of these synthetic strategies thus far. However, organic transformations on metal-bound sigma-aryl fragments are being used more and more by chemists in both industry and academia. In this Review, emphasis is put on the synthetic methods applied in this field up to now. The simplicity and generally good yields of these methods are very attractive for the construction of functionalized organometallic building blocks that are potentially useful as photochemical molecular devices, biosensors and -conjugates, or molecular switches. Thus, this Review has been tailored for a broader audience with the aim of encouraging the application of these strategies.

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Section: Angewandte Chemiementioning

confidence: 96%

Section: Regioselective Electrophilic Substitution Of Heterocyclic Pomentioning

confidence: 99%

Section: Angewandte Chemiementioning

confidence: 99%

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Organic Transformations on σ‐Aryl Organometallic Complexes

et al. 2007

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“…As stated by Wilkinson et al their stability is consistent with a d 4 low-spin electronic configuration, with the ligand methyl groups serving to inhibit decomposition pathways including reductive elimination and ortho-hydrogen abstraction. 15 These compounds can be purified using chromatography in air, and their aryl ligands can be chemically functionalized via different methods (including bromination, 18 Suzuki coupling, 18 and Friedel-Crafts acylation 19 ). Os(aryl)4 also have a particularly rich redox chemistry which facilitated the early isolation of a stable paramagnetic Os(V) complex.…”

Section: Introductionmentioning

confidence: 99%

An improved route to osmium(IV) tetraaryl complexes

Parr¹,

Olivar

Saal

et al. 2021

Preprint

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Investigations into the reactivity, properties, and applications of osmium(IV) tetraaryl complexes have been hampered by their low yielding syntheses from volatile and toxic OsO4 (typically ≤34%). Here we show that air-stable M(aryl)4 compounds (M = Os, Ru; aryl = 2-tolyl, 2,5-xylyl) can be prepared in improved yields (≤73%) starting from new, less hazardous (Oct4N)2[MX6] precursors (M = Os, Ru; X = Cl, Br). This approach also facilitates the preparation of Os(mesityl)4 (Os3), a complex comprising bulky 2,6-methyl substituted aryl ligands, for the first time (5% yield). We evaluate the X-ray crystal structures of Os(2,5-xylyl)4 (Os2) and Os3, employing a "tetrahedricity" metric that shows Os3 has a particularly distorted tetrahedral geometry compared to other Ru(aryl)4 and Os(aryl)4 materials. The 1H NMR spectrum of Os3 exhibits significantly broadened features at 298 K that split into distinct resonances at low temperatures, indicative of restricted rotation of the mesityl ligands around the Os-aryl 𝜎-bond. Solution cyclic voltammograms of Os(aryl)4 reveal that the potentials of their known reversible redox features can be fine-tuned by varying the number of ligand methyl substituents, and that Os3 exhibits an additional 1+/2+ redox event not previously observed in this class of compounds. This work aims to help advance the potential application of these relatively underexplored organometallic complexes in established and emerging areas of molecular materials science, such as extended molecular frameworks and self-assembled monolayers, where analogous tetraphenylmethane and silane species (M = C, Si) have been frequently targeted.

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“…1 Os(IV) [2][3][4] and Ru(IV) [3][4][5] compounds with ortho-methylated -aryl ligands are particularly robust (consistent with a stable d 4 low-spin electronic configuration), where the methyl groups provide steric protection from decomposition pathways such as reductive elimination and ortho-hydrogen abstraction. 3 They can be purified using chromatography in air, and their aryl ligands can be chemically functionalized via different methods (including bromination, 6 Suzuki coupling, 6 and Friedel-Crafts acylation 7 ). The osmium compounds have a particularly rich redox chemistry which facilitated the early isolation of a stable paramagnetic Os(V) complex.…”

mentioning

confidence: 99%

An Improved Route to Osmium(IV) Tetraaryl Complexes

Parr¹,

Haiges²,

Inkpen³

2020

Preprint

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Air-stable, redox-active osmium(IV) tetraaryl complexes can be prepared in yields ≤76% from the novel precursor (Oct4N)2[OsBr6], facilitating the synthesis of Os(mesityl)4 for the first time. This complex exhibits a distorted tetrahedral geometry and three reversible redox events including a 1+/2+ feature not previously observed in this family of materials.

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Direct functionalisation of σ-aryl ligands: preparation of homoleptic functionalised aryls of osmium(iv)

Cited by 17 publications

References 10 publications

Organic Transformations on σ‐Aryl Organometallic Complexes

Organic Transformations on σ‐Aryl Organometallic Complexes

An improved route to osmium(IV) tetraaryl complexes

An Improved Route to Osmium(IV) Tetraaryl Complexes

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