Flexible SNS pincer complexes of copper: Synthesis, structural characterisation and application in n-octane oxidation

Soobramoney, Lynette; Bala, Muhammad D.; Friedrich, Holger B.; Pillay, Michael N.

doi:10.1016/j.poly.2019.02.016

Cited by 6 publications

(3 citation statements)

References 41 publications

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“…The replacement of PNP pincer ligands with SNS ligands that contain more weakly σ-donating thioether groups in place of the phosphine donors may be a useful approach to lowering the electron density at the metal. In fact, SNS pincer ligands have already been used to support base metal , and palladium , catalysts due to their relative air stability, facile synthesis, and potential hemilability compared to the PNP ligand platform. For example, palladium catalysts with either pyridyl or aliphatic SNS ligands can facilitate cross-coupling reactions that are proposed to involve homogeneous or heterogeneous active species.…”

Section: Introductionmentioning

confidence: 99%

Comparative Coordination Chemistry of PNP and SNS Pincer Ruthenium Complexes

et al. 2021

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Ruthenium carbonyl complexes supported by PNP pincer ligands are prominent catalysts for a range of hydrogenation and dehydrogenation reactions. Recently, Ru complexes with cheaper, more air stable SNS pincer ligands have emerged as attractive alternatives for the development of improved catalysts. However, there is currently a paucity of information on how the replacement of the phosphine donors in PNP ligands with the sulfur donors in SNS ligands influences the synthesis, structure, and electronic properties of the resulting metal complexes. Herein, the coordination chemistry of a series of Ru carbonyl complexes with SNS pincer ligands has been systematically compared with related PNP-ligated species. Three different SNS pincer ligands were explored including a pyridyl based NC 5 H 3 {CH 2 (S t Bu)} 2 ligand and two aliphatic ligands, HN{CH 2 CH 2 (S t Bu)} 2 and NCH 3 {CH 2 CH 2 (S t Bu)} 2 , along with different combinations of monodentate ancillary ligands. The geometric structures of the SNS and PNP Ru complexes were studied using NMR spectroscopy and X-ray crystallography. Additionally, the redox properties and electronic structures of these complexes were probed through a combination of cyclic voltammetry and DFT calculations. Overall, differences between SNS and PNP complexes extend well beyond simply modulating inductive donation to the metal and include changes in synthetic outcomes, as well as variations in geometry that impact redox behavior. Our study reveals fundamental information about the coordination chemistry of the SNS ligand, which may aid in interpreting catalytic results.

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Section: Introductionmentioning

confidence: 99%

Comparative Coordination Chemistry of PNP and SNS Pincer Ruthenium Complexes

et al. 2021

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“…On the contrary, the tridentate SNS ligands tend to be hemilabile because of the donor atoms in their structure (hard N and soft S) that can coordinate with a broad range of metals and are useful in many catalytic applications. [14] Because of its structure, the homogeneous catalyst has many advantages such as excellent selectivity and activity in organic reactions, easy mixing at low temperatures, mild reaction conditions, and no diffusion problem. In most cases, the variation in the ligands and central metal atoms can control the electronic and steric properties of the active species.…”

Section: Introductionmentioning

confidence: 99%

Influence of ionic liquid counterions on activity and selectivity of ethylene trimerization using chromium‐based catalysts in biphasic media

Marefat

Ahmadi

Mohamadnia

2020

Applied Organom Chemis

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In recent years ionic liquids (ILs) have attracted much interest because of their widespread use in various fields. Several trimerization and oligomerization catalysts have been evaluated in ILs with different organic–inorganic hybrid structures. High catalytic activity and selectivity, easy product separation, and recycling of the catalyst are the advantages of a biphasic catalyst system compared to the homogeneous catalysts. In this study, the influence of IL counter‐anions on activity and selectivity of the ethylene trimerization catalysts based on Cr‐SNS‐R was investigated. All synthesized materials were characterized using Fourier‐transform infrared spectroscopy, 1H NMR, 13C NMR, UV–Vis. spectroscopy, thin‐layer chromatography, and elemental analysis (CHNS). In ethylene trimerization reaction, the dodecyl substituent in the SNS ligand exhibited better activity and selectivity than the butyl substituent. The results revealed that the presence of BF4− as a counter‐anion in the IL led to an increase in activity and selectivity compared to Br− and I− counter‐anions. It was found that the BF4− counter‐anion plays a conclusive role in the development of 1‐hexene activity and selectivity to a maximum amount of 71,132 g1‐C6/(gCr × h) and more than 99%, respectively. Finally, the catalyst was reused thrice without losing its 1‐hexene selectivity.

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“…There is a current need and economic urgency to replace current petrochemical feedstocks (olefins) with easily accessible alkanes, which can result in more proficient use of energy and efficient strategies for fine chemical synthesis. [1][2][3][4][5][6][7][8][9][10] Terminally oxidized hydrocarbons are valuable starting materials in the pharmaceutical and chemical industries. 11 However, one of the main challenges in the activation of alkane C-H bonds is the low selectivity in forming the desired products, that is, the preferential activation of sp 2 over sp 3 hybridized C-H bonds.…”

Section: Introductionmentioning

confidence: 99%

The effects of metals and ligands on the oxidation of n-octane using iridium and rhodium “PNP” aminodiphosphine complexes

Naicker

Alapour

Friedrich

2020

Journal of Chemical Research

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Ir and Rh “PNP” complexes with different ligands are utilized for the oxidation of n-octane. Based on the obtained conversion, selectivity, and the characterized recovered catalysts, it is found that the combination of Ir and the studied ligands does not promote the redox mechanism that is known to result in selective formation of oxo and peroxo compounds [desired species for C(1) activation]. Instead, they support a deeper oxidation mechanism, and thus higher selectivity for ketones and acids is obtained. In contrast, these ligands seem to tune the electron density around the Rh (in the Rh-PNP complexes), and thus result in a higher n-octane conversion and improved selectivity for the C(1) activated products, with minimized deeper oxidation, in comparison to Ir-PNP catalysts.

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Flexible SNS pincer complexes of copper: Synthesis, structural characterisation and application in n-octane oxidation

Cited by 6 publications

References 41 publications

Comparative Coordination Chemistry of PNP and SNS Pincer Ruthenium Complexes

Comparative Coordination Chemistry of PNP and SNS Pincer Ruthenium Complexes

Influence of ionic liquid counterions on activity and selectivity of ethylene trimerization using chromium‐based catalysts in biphasic media

The effects of metals and ligands on the oxidation of n-octane using iridium and rhodium “PNP” aminodiphosphine complexes

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