Lanthanide complexes of a cross-bridged cyclam ligand: Isolation and structural characterization of unusual trinuclear μ 3-imido Yb(III) cluster cations and a mixed valence Yb(II/III) salt containing an Yb(II) anion

Abstract

The reaction of the cross-bridged cyclam ligand H 2CBC with divalent ytterbium precursors, Yb[N(SiMe 3) 2] 2[L] 2 (L = THF or Et 2O) or Yb(C 5Me 5) 2(OEt 2) afforded polymeric [Yb(CBC)] n ( 1), as the primary product. In addition, the Yb[N(SiMe 3) 2] 2[L] 2 reactions also afforded a small amount of an unusual mixed valence salt containing a trinuclear Yb(III) cluster cation featuring a triply bridging NH group and a mononuclear Yb(II) anion, {[Yb(CBC)] 3[μ 3-NH]} + {Yb[N(SiMe 3) 2] 3} − ( 2). A related cluster containing an iodide counterion, {[Yb(CBC)] 3[μ 3-NH]} + I − ( 3), was also isolated in one case. The structures of salts 2 and 3 were determined by X-ray crystallography. Reaction of [Yb(CBC)] n with p-tolyldisulfide, (C 6H 4MeS) 2, produced burgundy crystals of [Yb(CBC)(S-p-C 6H 4Me)] n ( 4). The 1H NMR spectra of 2 suggests that the trinuclear cation remains intact in THF-d 8 solution.