Improved Trianionic Pincer Ligand Synthesis for Cyclic Polymer Catalysts

Jakhar, Vineet K.; Shen, Yu-Hsuan; Hyun, Sung-Min; Esper, Alec; Ghiviriga, Ion; Abboud, Khalil A.; Lester, Daniel W.; Veige, Adam S.

doi:10.1021/acs.organomet.3c00060

Cited by 10 publications

(10 citation statements)

References 74 publications

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“…Recently, Grubbs et al reported the silica-supported ruthenium heterogeneous catalyst for the bulk REMP of cyclopentene, allowing catalyst recovery . These catalysts have provided access to cyclic variants of commercially relevant and historically important polymers, such as poly(propylene), poly(norbornene), − poly(methyl-1-pentene), poly(phenylacetylene), − and poly(acetylene) . Interestingly, upon doping, cyclic poly(acetylene) showed conductivity on the higher end of nonstretch aligned linear poly(acetylene), and cyclic poly(methyl-1-pentene) exhibited higher T g compared to its commercial linear counterpart while maintaining remarkable optical clarity. , Veige et al also reported the synthesis of cyclic(polyacetylene) via REMP of a soluble polymer precursor.…”

Section: Introductionmentioning

confidence: 99%

Functionalized Cyclic Polymers and Network Gels

Konar,

Jakhar,

Stewart

et al. 2024

Macromolecules

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Cyclic polymers exhibit different solution and bulk properties compared to their linear analogs of the same molecular weight, such as smaller hydrodynamic volumes and higher glass transition temperatures (T g ). Polymers having boron-centered Lewis acids as pendent groups have utility in sensors, biomaterials, and dynamic covalent materials. Conventional and controlled radical polymerization are the most common routes to synthesize polymers with pendent boronate ester and boronic acid functional groups. Herein, we expand the synthetic repertoire available for their synthesis by reporting the preparation of cyclic poly(4ethynylphenylboronate ester) (c-PEPB) by ring-expansion polymerization (REP) of 4-ethynylphenylboronate ester using a pincersupported tethered tetra-anionic tungsten alkylidene complex. The polymers were successfully characterized and compared to their linear analogs using light scattering measurements, solution viscometry, and thermal analysis. In all cases, the polymer interrogation experiments reveal key differences attributed to the cyclic topology. Deprotection of the polymeric boronate esters was performed by transesterification with methylboronic acid to furnish cyclic poly(4-ethynylphenyl boronic acid) (c-PEPB−OH). The reversible reaction of boronic acids with 1,2-and 1,3-diols to form boronate esters was used to cross-link c-PEPB−OH with a polyol crosslinker to form gels from cyclic polymers.

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Section: Introductionmentioning

confidence: 99%

Functionalized Cyclic Polymers and Network Gels

Konar,

Jakhar,

Stewart

et al. 2024

Macromolecules

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“…This strategy has been pioneered by Veige and co-workers utilizing a high-valent [W VI ] catalyst and a variety of terminal alkynes. [22][23][24][25][26][27][28][29] Likewise, Maeda and co-workers have also reported cyclic polyalkynes of tolanes invoking Nb, [30] Ta, [31] and W [32] alkyne adducts. More recently, we have identified [V V ] alkylidynes (Scheme 1, A) [33][34] as pre-catalysts for the cyclic polymerization of phenylacetylene (cyclic-PPA, B).…”

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confidence: 99%

Metallacyclobuta‐(2,3)‐diene: A Bidentate Ligand for Stream‐line Synthesis of First Row Transition Metal Catalysts for Cyclic Polymerization of Phenylacetylene

Russell,

Konar,

Keller

et al. 2024

Angewandte Chemie

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Described here is a direct entry to two the first examples of 3d transition metal catalysts that are active for the cyclic polymerization of phenylacetylene, namely, [(BDI)M{k2‐C,C‐(Me3SiC3SiMe3)}] (2‐M) (BDI = [ArNC(CH3)]2CH−, Ar = 2,6‐iPr2C6H3; M = Ti, V). Catalysts are prepared in one step by the treatment of [(BDI)MCl2] with 1,3‐dilithioallene [Li2(Me3SiC3SiMe3)]. Complexes 2‐M have been spectroscopically and structurally characterized and the polymers that are catalytically formed from phenylacetylene were verified to have a cyclic topology based on a combination of size‐exclusion chromatography (SEC) and intrinsic viscosity studies. Two‐electron oxidation of 2‐V with nitrous oxide cleanly yields a [VV] alkylidene‐alkynyl oxo complex [(BDI)V(=O){k1‐C‐(=C(SiMe3)CC(SiMe3))}] (3), which lends support for how this scaffold in 2‐M might be operating in the polymerization of the terminal alkyne. This work demonstrates how alkylidynes can be circumvented using 1,3‐dianionic allene as a segue into M–C multiple bonds.

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“…Inspired by the growing popularity of ring-opening metathesis polymerization (ROMP) methodologies − to synthesize linear macromolecules with complex sequences and rich functionalities, ring-expansion metathesis polymerization (REMP) − methodologies aim to expand the scope of analogous cyclic macromolecules and the ease by which they are made. The evolution of organometallic (e.g., Ru, W, Mo) REMP initiators ,,− has lagged compared to the advancements made in ROMP initiator development, likely due to the difficulties associated with synthesizing the former and analytical challenges in characterizing , putative cyclic macromolecules.…”

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confidence: 99%

Ancillary Ligand Lability Improves Control in Cyclic Ruthenium Benzylidene Initiated Ring-Expansion Metathesis Polymerizations

Levenson,

Morrison,

Huang

et al. 2023

ACS Macro Lett.

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The synthesis of well-defined cyclic polymers is crucial to exploring applications spanning engineering, energy, and biomedicine. These materials lack chain-ends and are therefore imbued with unique bulk properties. Despite recent advancements, the general methodology for controlled cyclic polymer synthesis via ring-expansion metathesis polymerization (REMP) remains challenging. Low initiator activity leads to high molar mass polymers at short reaction times that subsequently "evolve" to smaller polymeric products. In this work, we demonstrate that in situ addition of pyridine to the tethered ruthenium-benzylidene REMP initiator CB6 increases ancillary ligand lability to synthesize controlled and low dispersity cyclic poly(norbornene) on a short time scale without relying on molar mass evolution events.

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Improved Trianionic Pincer Ligand Synthesis for Cyclic Polymer Catalysts

Cited by 10 publications

References 74 publications

Functionalized Cyclic Polymers and Network Gels

Functionalized Cyclic Polymers and Network Gels

Metallacyclobuta‐(2,3)‐diene: A Bidentate Ligand for Stream‐line Synthesis of First Row Transition Metal Catalysts for Cyclic Polymerization of Phenylacetylene

Ancillary Ligand Lability Improves Control in Cyclic Ruthenium Benzylidene Initiated Ring-Expansion Metathesis Polymerizations

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