Photochemical Resolution of a Thermally Inert Cyclometalated Ru(phbpy)(N-N)(Sulfoxide) + Complex

L.N. Lameijer, C. Van De Griend, S.L. Hopkins, A.-G. Volbeda, S.H.C. Askes, M.A. Siegler, S. Bonnet

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

© 2018 American Chemical Society. In this work a photosubstitution strategy is presented that can be used for the isolation of chiral organometallic complexes. A series of five cyclometalated complexes Ru(phbpy)(N-N)(DMSO-κS)](PF 6 ) ([1]PF 6 -[5]PF 6 ) were synthesized and characterized, where Hphbpy = 6′-phenyl-2,2′-bipyridyl, and N-N = bpy (2,2′-bipyridine), phen (1,10-phenanthroline), dpq (pyrazino[2,3-f][1,10]phenanthroline), dppz (dipyrido[3,2-a:2′,3′-c]phenazine, or dppn (benzo[i]dipyrido[3,2-a,2′,3′-c]phenazine), respectively. Due to the asymmetry of the cyclometalated phbpy - ligand, the corresponding [Ru(phbpy)(N-N)(DMSO-κS)] + complexes are chiral. The exceptional thermal inertness of the Ru-S bond made chiral resolution of these complexes by thermal ligand exchange impossible. However, photosubstitution by visible light irradiation in acetonitrile was possible for three of the five complexes ([1]PF 6 -[3]PF 6 ). Further thermal coordination of the chiral sulfoxide (R)-methyl p-tolylsulfoxide to the photoproduct [Ru(phbpy)(phen)(NCMe)]PF 6 , followed by reverse phase HPLC, led to the separation and characterization of the two diastereoisomers of [Ru(phbpy)(phen)(MeSO(C 7 H 7 ))]PF 6 , thus providing a new photochemical approach toward the synthesis of chiral cyclometalated ruthenium(II) complexes. Full photochemical, electrochemical, and frontier orbital characterization of the cyclometalated complexes [1]PF 6 -[5]PF 6 was performed to explain why [4]PF 6 and [5]PF 6 are photochemically inert while [1]PF 6 -[3]PF 6 perform selective photosubstitution.
Original languageEnglish
Pages (from-to)352-362
JournalJournal of the American Chemical Society
Volume141
Issue number1
DOIs
Publication statusPublished - 9 Jan 2019
Externally publishedYes

Funding

NWO−CW (Netherlands Organization for Scientific Research) is kindly acknowledged for a VIDI grant to S.B. The European Research Council is kindly acknowledged for an ERC starting grant to S.B. The COST action CM1105 is acknowledged for stimulating scientific discussions. Dr. Jordi-Amat Cuello Garibo is kindly acknowledged for help with CD measurements. Prof. E. Bouwman is kindly acknowledged for support and scientific discussions.

FundersFunder number
Netherlands Organization for Scientific Research
European Research Council
Nederlandse Organisatie voor Wetenschappelijk Onderzoek

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