NO to NO2− conversion by divalent lanthanides: synthesis and crystal structure of [Sm(TpMe2,4-Et)2NO2]

Abstract The reaction of nitric oxide with the divalent lanthanide complex [Ln(Tp Me2 ) 2 ] and [Ln(Tp Me2,4-Et ) 2 ] (Ln = Sm, Eu, Yb) gives the corresponding seven-coordinate nitrites [Ln(Tp Me2,X ) 2 NO 2 ] in a smooth reaction. A possible mechanism is proposed for this NO disproportionation. A single crystal X-ray diffraction study of [Sm(Tp Me2,Et ) 2 NO 2 ] reveals a dodecahedral metal centre. However, as is customary for these species, the complex is fluxional in solution by NMR even at the lowest accessible temperatures.