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

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.