Trans‐Dioxidomolybdenum(VI) Porphyrins and their Catalytic Activity Mimicking Oxidative Bromination

trans-Dioxidomolybdenum(VI)-meso-tetraphenylporphyrin and trans-dioxidomolybdenum(VI)-meso-tetra(p-chlorophenyl)porphyrin have been synthesised and used as catalyst for the biomimetic haloperoxidases mimicking oxidative bromination of phenol and its derivatives.

Abstract

Synthesis of trans-dioxidomolybdenum(VI)-meso-tetraphenylporphyrin (trans-[Mo^VIO₂(TPP)], 1) and trans-dioxidomolybdenum(VI)-meso-tetra(p-chlorophenyl)porphyrin (trans-[Mo^VIO₂(TCPP)], 2) by reacting the corresponding free-base porphyrins with Mo(CO)₆ in 1,2,4-trichlorobenzene at 190 °C has been reported. These are the second examples in the literature where molybdenum-porphyrins have trans-[Mo^VIO₂] group, identified by single crystal X-ray study. Both complexes have been utilized as functional model of haloperoxidases for the oxidative bromination of various phenol derivatives using KBr, H₂O₂ and HClO₄ as green brominating reagents in aqueous medium. These complexes displayed very high TOF values (up to 16.2 s⁻¹ for catalyst 2) representing excellent catalytic activity. To the best of our knowledge, this is the first report presenting trans-dioxidomolybdenum(VI) based porphyrin as haloperoxidases mimicking oxidative bromination of various phenol derivatives.

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