Reactivity of ytterbium(ii) silylamide supported by a pyrrolyl–cyclopentadienyl ligand

Abstract

Diverse and high reactivity of a divalent ytterbium amide with the labile pyrrolyl π arm has been demonstrated.

Abstract

Reactivity of a divalent ytterbium amide LYbN(SiMe ₃) ₂ ( 1, L = Me ₄C ₅-SiMe ₂-NC ₄H ₄) 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(SiMe ₃) ₂] ₂(μ–η ²:η ²-S ₂) ( 2) while that with AgBPh ₄ resulted in the oxidation of the amide ligand to yield the divalent ytterbium complex LYb(BPh ₄) ( 3) along with the formation of silver and the N–N coupling product [N(SiMe ₃) 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- tBu ₂-4-MeC ₆H ₂), ytterbium alkynyl complex [LYb(μ-CCAr ²)] ₂ ( 5, Ar ² = 4- tBuC ₆H ₄) and ytterbium amide [(Me ₄C ₅-SiMe ₂-NHAr ³)Yb(μ-NHAr ³)] ₂ ( 6, Ar ³ = 2,6-iPr ₂C ₆H ₃), 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–N _pyrrole 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-NC ₄H ₄)] ₂ ( 7).