Bulky Ytterbium Formamidinates Stabilise Complexes with Radical Ligands, and Related Samarium “Tetracyclone” Chemistry

Abstract

Divalent [Yb(DippForm)2(thf)n] (n=2 (1 a), or 1 (1 b), DippForm=N,N′-bis(2,6-diisopropylphenyl)formamidinate) complexes were treated with the ketones: 9-fluorenone (fn), or 2,3,4,5-tetraphenylcyclopentadienone (tpc, tetracyclone), giving ketyl complexes: [Yb(DippForm)2(fn.-O)(thf)] (2), and [Yb(DippForm)2(tpc.-O)] (3), respectively (ketyl=a radical anion containing a C.−O(−)group. By contrast, when perfluorobenzophenone (pfb) was treated with either 1 a or 1 b, transitory ketyl formation was followed by rapid decomposition through a C−F activation pathway, giving [YbF(DippForm)2(thf)] (4 a) and a highly unusual fluoride/oxide-bridged species: [Yb5F6O2(DippForm)5] (4 b). The reduction of dike..