The behavior of pyrrolyl ligands within the rare-earth metal alkyl complexes. Insertion of C=N and C=O double bonds into Ln-sigma-C bonds

作者：Yang, Y,Cui, DM,Chen, XS
关键字：beta-diketiminato ligands; lactide polymerization; ethylene polymerization; structural-characterization; yttrium complexes; enantioselective hydroamination/cyclization; isospecific polymerization
论文来源：期刊
具体来源：http://pubs.rsc.org/en/Content/ArticleLanding/2010/DT/b926038b#!divAbstract
发表时间：2010年
 

This paper presents some unusual reactions of lanthanide tris(alkyl)s or lanthanide mono-Cp′ (Cp′ = (C5Me4)SiMe3) bis(alkyl)s with pyrrolyl ligands, and the η5- or η1-coordination mode of the pyrrolyl ring, as well as CN and CO double bonds insertion into Ln–σ-C moities. N,N,O-tridentate ligand HL1, 2-(2-CH3OC6H3NCH)–C4H3NH, was prepared. Treatment of HL1 with rare-earth metal tris(alkyl)s, Ln(CH2SiMe3)3(THF)2, generated centrosymmetric bimetallic (pyrrolylaldiminato)lanthanide mono(alkyl) complexes [{2-(2-CH3OC6H3NC(H)R)–C4H3N}LnR]2 (1a: Ln = Y; 1b: Ln = Lu) (R = CH2SiMe3). In this process, HL1 was deprotonated by the metal alkyl and its imino CN group was deactivated by the intramolecular alkylation, generating dianionic species that bridged the two metal alkyl units in η5/η1:κ1 modes. When the reaction was carried out in dimethoxyethane (DME), asymmetric complex [2-(2-CH3OC6H3NC(H)R)–C4H3N]2Y2R2(DME) (2) was given. Furthermore, the reaction of alkyl complex 1b and benzophenone (Ph2CO) afforded alkyl-insertion product [{2-(2-CH3OC6H3NC(H)R)–C4H3N}LuOC(R)Ph2]2 (3). Both the intermolecular alkylation and the pyrrole''s behavior as the hetero-cyclopentadienyl ligand were also observed in complexes 2 and 3. HL1reacted with (η5-Cp′)Y(CH2SiMe3)2(THF) (E) to form a mixed ligands supported alkyl complex [(η5-Cp′)(L1)]Y(CH2SiMe3)(THF) (4), whilst complex E was treated with 2-(2,6-iPr2C6H3NCH)–C4H3NH (HL2) to yield [(η5-Cp′)(L2)]Y(CH2SiMe3)(THF) (5). However, reaction of E and 2-(Me2NCH2)–C4H3NH (HL3) afforded Y[(η5-Cp′)(L3)2] (6), and ligand redistribution was found in this process. The molecular structures of complexes 5 and 6 were confirmed by X-ray diffraction, which indicated that the CN double bond survived and the pyrrolyl ring coordinated to the metal center in η1-mode.