Metal-mediated hydrolysis of the oxime CN bond to produce RhIII-bound O-iminoacylated MeC(NH)ONH2 species

Abstract

Reaction of the acetonitrile complex [RhCl₃(MeCN)₃] with 2-propanone oxime, Me₂CNOH, or, alternatively, interaction of [RhCl₃(Me₂CNOH)₃] and acetonitrile led to the formation of two rhodium(III) products that contain newly formed chelated iminoacyl ligands, i.e. [RhCl₃{NH=C(Me)ON=CMe₂}(HON=CMe₂)] 1 and [RhCl₂{NH=C(Me)ON=CMe₂}₂]Cl 2. Complex 1 can be transformed to 2 by further reaction with acetonitrile. Metathesis of 2 and Na[SbF₆] in water gave [RhCl₂{NH=C(Me)ON=CMe₂}₂][SbF₆] 3 that was structurally characterized by single-crystal X-ray diffraction. In 0.1 M HCl, 2 is subject to a facile stepwise hydrolysis of the two usually stable oxime CN bonds giving [RhCl₃{NH=C(Me)ON=CMe₂}{NH=C(Me)ONH₂}]Cl·H₂O 4, as the monohydrolysed product, and ultimately furnished [RhCl₂{NH=C(Me)ONH₂}₂]Cl 5 that was characterized by X-ray diffraction. The latter complex can be converted into 2 on prolonged refluxing in an acetone–ethanol mixture.