Electronic fine-tuning of oxygen atom transfer reactivity of cis-dioxomolybdenum(VI) complexes with thiosemicarbazone ligands

Aurélien Ducrot, Bethany Scattergood, Ben Coulson, Robin N. Perutz, Anne K. Duhme-Klair*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A series of six cis-dioxomolybdenum(VI) complexes with thiosemicarbazone ligands was synthesized and characterized. The ligands were obtained by reacting ethyl thiosemicarbazide with salicylaldehydes substituted with a selection of electron-withdrawing and electron-donating groups. The crystal structures, IR, NMR spectroscopic data and oxygen atom transfer activities of the complexes revealed that the electronic effects of the substituents located in the para-position of the phenolate donor are transmitted through to the molybdenum center, as reflected by linear relationships between Hammett constants and key properties of the complexes, including the molybdenum-phenolate bond lengths and the coordination shift of the imine proton resonance. Compared with the unsubstituted catalyst, electron-withdrawing substituents increase the rate of oxygen atom transfer from dimethyl sulfoxide to triphenylphosphine, whereas electron-donating groups have the opposite effect. The highest rate enhancement was achieved through the introduction of a strongly electron-withdrawing NO2 substituent in the p-position of the phenolate donor.

Original languageEnglish
Pages (from-to)3562-3571
Number of pages10
Early online date2 Apr 2015
Publication statusPublished - 2015


  • Enzyme models
  • Ligand effects
  • Metalloenzymes
  • Molybdenum
  • Oxygen atom transfer

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