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

• Published in: European journal of inorganic chemistry Vol. 2020; no. 22; pp. 2153 - 2164
• Main Authors: Jiang, Wen, Zhang, Li‐Jun, Zhang, Li‐Xin
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 16-06-2020
• Subjects: Amines; Coordination compounds; Earth; Enolates; Initiators; Inorganic chemistry; Insertion; Organic compounds; Polymerization; rac‐Lactide; Rare‐earths; Ring opening polymerization; Small molecules; Yttrium
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202000148

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.
Two monoguanidinate aminobenzyl enolate complexes were synthesized by two new pathways, and their reactivity with some small molecules were investigated. During the reactions, some unique structural lanthanide complexes were achieved through interesting chemical transformations. The complexes also exhibited high catalytic activities in the ring‐opening polymerization of rac‐lactide.