Intramolecular Oxidative Addition Triggered by One-Electron Oxidation of Molybdenum( iii ) Tris(anilide): Generation of Molybdenum(v) Imido Aryl Bis(anilide) by Autocatalysis

Résumé fourni par la source

One-electron oxidation of molybdenum( iii ) tris(anilide) Mo(N[ t Bu]Ar) 3 (Ar: Ar Me = 3,5-Me 2 C 6 H 3 and Ar Ph = 3,5-Ph 2 C 6 H 3 ) led to intramolecular oxidative addition across the N–C ipso bond of a ligated anilide to form the cationic Mo( vi ) imido/aryl bis(anilide) complexes [Mo(N[ t Bu]Ar) 2 (═N t Bu)(Ar)][B(C 6 F 5 ) 4 ]. One-electron reduction of [Mo(N[ t Bu]Ar Me ) 2 (═N t Bu)(Ar Me )][B(C 6 F 5 ) 4 ] allowed access to the neutral Mo(v) species [Mo(N[ t Bu]Ar Me ) 2 (═N t Bu)(Ar Me )]. The d 1 electron configuration was confirmed through EPR spectroscopy and the Evans method. Compound [Mo(N[ t Bu]Ar Me ) 2 (═N t Bu)(Ar Me )] was experimentally and theoretically shown to be stable against reductive elimination which would form the energetically less favorable Mo(N[ t Bu]Ar) 3 . The high activation barrier has so far prevented Mo(N[ t Bu]Ar) 3 from isomerizing spontaneously to [Mo(N[ t Bu]Ar Me ) 2 (═N t Bu)(Ar Me )]. An autocatalytic process was developed to access [Mo(N[ t Bu]Ar Me ) 2 (═N t Bu)(Ar Me )] through reduction of [Mo(N[ t Bu]Ar Me ) 2 (═N t Bu)(Ar Me )][B(C 6 F 5 ) 4 ] by Mo(N[ t Bu]Ar) 3, which itself was converted into the oxidizing agent. Attempts to access stable Mo( iv ) cations with 4,4′-bipyridine only resulted in labile binding of 4,4′-bipyridine to one or two molybdenum( iii ) tris(anilide) complexes.

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