Modular O- vs. N-coordination of pyridylidene amide ligands to iron determines activity in alcohol oxidation catalysis

Verhoeven, Dide G. A.; Albrecht, Martin (2020). Modular O- vs. N-coordination of pyridylidene amide ligands to iron determines activity in alcohol oxidation catalysis. Dalton transactions, 49(48), pp. 17674-17682. Royal Society of Chemistry 10.1039/d0dt02818e

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A family of polydentate pyridine-substituted pyridylidene amide (PYA) complexes bound to iron(II) was developed. The variation of the coordination set from NN-bidentate PYA to tridentate pincer-type pyPYA2 systems (pyPYA2 = 2,6-bis(PYA)pyridine) had a large influence on the binding mode to iron(II), including a change from the N- to rare O-coordination of the PYA site and a concomitant shift of the predominant ligand resonance structure. These binding mode variations invoke changes in the reactivity of the complexes, which were probed in the peroxide-mediated oxidation of 1-phenylethanol to acetophenone. A comparison with uncomplexed FeCl2 indicated that bidentate NN coordination is unstable and presumably leads to the dissociation of FeCl2. In contrast, the tridentate ligand binding is robust. Remarkably, the tridentate PYA pincer coordination inhibits catalytic activity in the NNN binding mode, while the ONO coordination greatly enhances catalytic performance. Under optimized conditions, the bis-ligated ONO pincer iron complex [Fe(pyPYA2)2][2PF6] reaches full conversion within one hour (0.5 mol% catalyst loading) and under dilute conditions turnover numbers over 20 000 (0.005 mol% catalyst loading).

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)

UniBE Contributor:

Verhoeven, Dide Gertruda and Albrecht, Martin

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

1477-9226

Publisher:

Royal Society of Chemistry

Funders:

[18] European Research Council ; [185] University of Bern: Seal of Excellence Fund ; [42] Schweizerischer Nationalfonds

Projects:

[1134] Exploiting Synergistic Properties of Mesoionic Carbene Complexes: Teaching Rusty Metals Challenging Catalysis
[1396] SELF 18-03
[1283] Designer ligands for oxidative bond activation catalysis

Language:

English

Submitter:

Eik Szee Goh Aschauer

Date Deposited:

20 Jan 2021 09:43

Last Modified:

20 Jan 2021 09:43

Publisher DOI:

10.1039/d0dt02818e

BORIS DOI:

10.48350/150129

URI:

https://boris.unibe.ch/id/eprint/150129

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