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

Abstract

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–η²:η²-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-OAr¹)]₂ (4, Ar¹ = 2,6-tBu₂-4-MeC₆H₂), ytterbium alkynyl complex [LYb(μ-CCAr²)]₂ (5, Ar² = 4-tBuC₆H₄) and ytterbium amide [(Me₄C₅-SiMe₂-NHAr³)Yb(μ-NHAr³)]₂ (6, Ar³ = 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–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–η¹:η⁵-NC₄H₄)]₂ (7).