Reactivity of ytterbium(II) silylamide supported by a pyrrolyl-cyclopentadienyl ligand.

Reactivity of a divalent ytterbium amide LYbN(SiMe3)2 (1, L = Me4C5-SiMe2-NC4H4) supported by a pyrrolyl functionalized cyclopentadienyl ligand has been investigated. Reactions of 1 with the element sulfur led to the oxidation of the ytterbium to yield the disulfide-bridged ytterbium complex [LYbN(SiMe3)2]2(μ-η(2):η(2)-S2) (2) while that with AgBPh4 resulted in the oxidation of the amide ligand to yield the divalent ytterbium complex LYb(BPh4) (3) along with the formation of silver and the N-N coupling product [N(SiMe3)2]2. Reactions of 1 with phenol, phenylacetylene and aniline led to the formation of the corresponding ytterbium aryloxide [LYb(μ-OAr(1))]2 (4, Ar(1) = 2,6-tBu2-4-MeC6H2), ytterbium alkynyl complex [LYb(μ-C≡CAr(2))]2 (5, Ar(2) = 4-tBuC6H4) and ytterbium amide [(Me4C5-SiMe2-NHAr(3))Yb(μ-NHAr(3))]2 (6, Ar(3) = 2,6-iPr2C6H3), respectively. The structural analysis of the reaction products revealed that the silyl bridged pyrrolyl arm is not coordinated to the ytterbium center in compounds 2, 4 and 5. The formation of 6 involved the cleavage of the Si-Npyrrole bond, the same bond cleavage was also observed in the reaction of 1 with red phosphorus, leading to the pyrrolide bridged complex [LYb(μ-η(1):η(5)-NC4H4)]2 (7).