Enhanced Understanding of Structure-Function Relationships for Oxomanganese(IV) Complexes

A series of manganese(II) and oxomanganese(IV) complexes supported by neutral, pentadentate ligands with varied equatorial ligand-field strength (N3pyQ, N2py2I, and N4pyMe2) were synthesized and then characterized using structural and spectroscopic methods. On the basis of electronic absorption spectroscopy, the [MnIV(O)(N4pyMe2)]2+ complex has the weakest equatorial ligand field among a set of similar MnIV-oxo species. In contrast, [MnIV(O)(N2py2I)]2+ shows the strongest equatorial ligand-field strength for this same series. We examined the influence of these changes in electronic structure on the reactivity of the oxomanganese(IV) complexes using hydrocarbons and thioanisole as substrates. The [MnIV(O)(N3pyQ)]2+ complex, which contains one quinoline and three pyridine donors in the equatorial plane, ranks among the fastest MnIV-oxo complexes in C-H bond and thioanisole oxidation. While a weak equatorial ligand field has been associated with high reactivity, the [MnIV(O)(N4pyMe2)]2+ complex is only a modest oxidant. Buried volume plots suggest that steric factors dampen the reactivity of this complex. Trends in reactivity were examined using density functional theory (DFT)-computed bond dissociation free energies (BDFEs) of the MnIIIO-H and MnIV ≡ O bonds. We observe an excellent correlation between MnIV≡O BDFEs and rates of thioanisole oxidation, but more scatter is observed between hydrocarbon oxidation rates and the MnIIIO-H BDFEs.

Lee, YuriUniversity of Kansas Lawrence (författare)
Mayfield, Jaycee R.University of Kansas Lawrence (författare)
Singh, ReenaLund University,Lunds universitet,Kemisk fysik,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Chemical Physics,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)chem-res (författare)
Denler, Melissa C.University of Kansas Lawrence (författare)
Jones, Shannon D.University of Kansas Lawrence (författare)
Day, Victor W.University of Kansas Lawrence (författare)
Nordlander, EbbeLund University,Lunds universitet,Kemisk fysik,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,LU profilområde: Ljus och material,Lunds universitets profilområden,Chemical Physics,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH,LU Profile Area: Light and Materials,Lund University Profile areas(Swepub:lu)ook1-eno (författare)
Jackson, Timothy A.University of Kansas Lawrence (författare)
University of Kansas LawrenceKemisk fysik (creator_code:org_t)

Av författaren/redakt...: Singh, Priya; Lee, Yuri; Mayfield, Jaycee ...; Singh, Reena; Denler, Melissa ...; Jones, Shannon D ...; visa fler...; Day, Victor W.; Nordlander, Ebbe; Jackson, Timothy ...; visa färre...

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