Expansion of the Ligand Knowledge Base for Chelating P,P-Donor Ligands (LKB-PP)

Jover, Jesús; Fey, Natalie; Harvey, Jeremy N.; Lloyd‐Jones, Guy C.; Orpen, A. Guy; Owen‐Smith, Gareth J. J.; Murray, Paul M.; Hose, David R. J.; Osborne, Robert; Purdie, Mark

doi:10.1021/om300312t

Cited by 82 publications

(69 citation statements)

References 24 publications

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“…2A). Selection of the ligands was based on a series of factors, specifically (i) performance in previous internal batch screens; (ii) an internal principal component analysis of ligand property space (19,20); (iii) coverage of the main ligand classes from the literature (21); and (iv) commercial availability. The bases selected span a range of both organic and inorganic commonly used in this transformation, and solvents were chosen to display a range of polarities and dipole moments and the presence or absence of hydrogen bond donors (22).…”

Section: Rapid Material-sparing Screening Of 5760 Reactionsmentioning

confidence: 99%

A platform for automated nanomole-scale reaction screening and micromole-scale synthesis in flow

Perera

Tucker

Brahmbhatt

et al. 2018

Science

377

364

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The scarcity of complex intermediates in pharmaceutical research motivates the pursuit of reaction optimization protocols on submilligram scales. We report here the development of an automated flow-based synthesis platform, designed from commercially available components, that integrates both rapid nanomole-scale reaction screening and micromole-scale synthesis into a single modular unit. This system was validated by exploring a diverse range of reaction variables in a Suzuki-Miyaura coupling on nanomole scale at elevated temperatures, generating liquid chromatography-mass spectrometry data points for 5760 reactions at a rate of >1500 reactions per 24 hours. Through multiple injections of the same segment, the system directly produced micromole quantities of desired material. The optimal conditions were also replicated in traditional flow and batch mode at 50- to 200-milligram scale to provide good to excellent yields.

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Section: Rapid Material-sparing Screening Of 5760 Reactionsmentioning

confidence: 99%

A platform for automated nanomole-scale reaction screening and micromole-scale synthesis in flow

Perera

Tucker

Brahmbhatt

et al. 2018

Science

377

364

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“…Complexes considered for LKB-PP and LKB-PPscreen. [124][125][126] Interaction energy between ligand in chelating conformation and wedge of 8 He atoms, a EHe8_wedge = E(He8(PP)) -E(He8) -E((PP)) (kcal mol -1 )…”

Section: Figurementioning

confidence: 99%

Computational Ligand Descriptors for Catalyst Design

2019

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Ligands, especially phosphines and carbenes, can play a key role in modifying and controlling homogeneous organometallic catalysts, and they often provide a convenient approach to fine-tuning the performance of known catalysts. The measurable outcomes of such catalyst modifications (yields, rates, selectivity) can be set into context by establishing their relationship to steric and electronic descriptors of ligand properties, and such models can guide the discovery, optimisation and design of catalysts.In this review we present a survey of calculated ligand descriptors, with a particular focus on homogeneous organometallic catalysis. A range of different approaches to calculating steric and electronic parameters are set out and compared, and we have collected descriptors for a range of representative ligand sets, including 30 monodentate phosphorus(III) donor ligands, 23 bidentate P,Pdonor ligands and 30 carbenes, with a view to providing a useful resource for analysis to practitioners. In addition, several case studies of applications of such descriptors, covering both maps and models, have been reviewed, illustrating how descriptor-led studies of catalysis can inform experiments and highlighting good practice for model comparison and evaluation.

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“…[76][77] The ligand knowledge base (LKB) approach developed in Bristol and described in detail elsewhere, [78][79][80][81] captures the properties of ligands in different coordination environments from relatively straightforward optimisations of ground state structures using standard density functional theory (DFT) calculations. 79 A range of structural parameters, energies and steric properties are extracted from these calculations (Table S5) and have been used in regression models, but also processed with a statistical projection technique, Principal Component Analysis (PCA), to optimally represent ligand similarities as distances on a so-called map of chemical space. 72 As shown recently for monodentate ligands, 82 such maps, where proximity indicates ligands with similar properties, can set unusual ligand designs, including phosphinines, [30][31][32]35 into context and so suggest possible applications in catalysis.…”

Section: Computational Insightmentioning

confidence: 99%

Accessing Alkyl- and Alkenylcyclopentanes from Cr-Catalyzed Ethylene Oligomerization Using 2-Phosphinophosphinine Ligands

Newland

Smith

et al. 2018

Organometallics

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Desilylation of the 2-phosphinophosphinine 2-PPh 2-3-Me-6-SiMe 3-PC 5 H 2 with HCl gave 2-PPh 2-3-Me-PC 5 H 3 , demonstrating the late-stage modification of this bidentate heterocyclic ligand. Group 6 metal carbonyl complexes of these ligands showed κ 2-binding and very small bite-angles of 65.1-68.3°, and also demonstrated that the donor properties of 2phosphinophosphinines can be tuned readily by the presence of the SiMe 3 group which gives a more π-accepting phosphinine ligand. The properties of 2-phosphinophosphinines were compared to bidentate diphosphorus ligands computationally, contextualizing them in the Ligand Knowledge Base for bidentate P,P donor ligands (LKB-PP) and were found to occupy an area of ligand space adjacent to Ar 2 PN(R)NAr 2 ligands that have been successfully used in ethylene oligomerization reactions, but with well-separated properties in the second principal component. Testing 2-phosphinophosphinines in Cr-catalyzed ethylene oligomerization reactions showed key differences to standard PNP ligands in that a high proportion of alkyl-and alkenyl-cyclopentanes were formed. This demonstrates that the different donor properties of 2-phosphinophosphinines influence the reactivity of the key 7-membered metallacycle postulated in the metallacyclic reaction mechanism, generating products from isomerization and subsequent ethylene insertion. Alkyl-and alkenyl-cyclopentanes represent new products for the key industrial feedstock ethylene, with the alkenes having potential as new monomers, comonomers or additives for plastics. Computational evaluation of ligand properties and the resulting property maps can play a role in suggesting future ligand developments to change the selectivity of this industriallyrelevant system in the pursuit of new products generated from ethylene.

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Expansion of the Ligand Knowledge Base for Chelating P,P-Donor Ligands (LKB-PP)

Cited by 82 publications

References 24 publications

A platform for automated nanomole-scale reaction screening and micromole-scale synthesis in flow

A platform for automated nanomole-scale reaction screening and micromole-scale synthesis in flow

Computational Ligand Descriptors for Catalyst Design

Accessing Alkyl- and Alkenylcyclopentanes from Cr-Catalyzed Ethylene Oligomerization Using 2-Phosphinophosphinine Ligands

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