Synthesis, Structure, and Reactivity of Monoguanidinate Rare‐Earth Metal Aminobenzyl Enolate Complexes

Abstract

Two monoguanidinate rare‐earth metal aminobenzyl enolate complexes LRE(CH2C6H4NMe2‐o)(OCH=CH2)(THF) (L = (PhCH2)2NC(NC6H3iPr2‐2,6)2; RE = Y (1a), Lu (1b)) were synthesized via two pathways of the ring‐opening of THF, and their reactivities with some molecules were also explored. Reaction of complex 1a with iPrNCNiPr gave the insertion product LY[(NiPr2)2CCH2C6H4NMe2‐o](OCH=CH2)(THF) (2). Whereas, in the case of PhNCS, LY[SC(CH2C6H4NMe2‐o)NPh](OCH=CH2)(THF) (3) and the ligands redistribution binuclear yttrium enolate complex [LY(µ‐OCH=CH2)(OCH=CH2)]2 (4) were obtained. The protonolysis products LY(NHPh)(OCH=CH2)(THF)2 (5), LY(NHPh)2(THF)2 (6) and LY(NPh2)(OCH=CH2)(THF)2 (7) were achieved by reaction of 1a with arylamine. Moreover, the THF ring‐opening insertion products with unique structures {LY[O(CH2)4PPh2][µ‐O(CH2)4PPh2]}2 (8) and {LY(SCH2C6H4NMe2‐o)[µ‐O(CH2)4SCH2C6H4NMe2‐o]}2 (9) were afforded through reactions of complex 1a with diphenylphosphine and elemental sulfur. It was the first example of THF activation promoted by rare‐earth metal thiolate complex. And some interesting chemical transformations were observed in our work. Complexes 1 could also serve as efficient initiators in the ring‐opening polymerization of rac‐lactide.