936741-82-1Relevant academic research and scientific papers
Synthesis, reactivity, and structural characterization of sodium and ytterbium complexes containing new imidazolidine-bridged bis(phenolato) ligands
Xu, Xiaoping,Yao, Yingming,Zhang, Yong,Shen, Qi
, p. 3743 - 3751 (2007)
A new imidazolidine-bridged bis(phenol) [ONNO]H2 ([ONNO]H 2 = 1,4-bis(2-hydroxy-3,5-di-tert-butyl-benzyl)-imidazolidine) was prepared in relatively high yield by Mannish reaction of 2,4-di-tert- butylphenol, formaldehyde, and ethylenediamine in a 2:3:1 molar ratio. Reaction of the bis(phenol) with NaH in THF, after workup, afforded the sodium bis(phenolate) {[ONNO]Na2(THF)2}2·2THF (1) as a dimeric tetranuclear complex in an almost quantitative yield. Reaction of YbCl3 with complex 1 in a 2:1 molar ratio in THF, in the presence of HMPA, produced the desired bis(phenolate) ytterbium dichloride as bimetallic complex [ONNO]{YbCl2(HMPA)}2·2.5C7H 8 (2). Complex 2 can be used as a precursor for the synthesis of ytterbium derivatives by salt metathesis reactions. Reaction of complex 2 with NaOiPr in a 1:2 molar ratio in THF led to the formation of bimetallic alkoxide [ONNO]{Yb(μ-Oi-Pr)CI(HMPA)}2·THF (3). However, the residual chlorine atoms in complex 3 are inactive for the further substituted reaction. Further study revealed that the bulkiness of the reagent has profound effect on the outcome of the reaction. Complex 2 reacted with bulky NaOAr (ArO = 2,6-di-tert-butyl-4-methylphenoxo) or NaNPh2 in a 1:2 molar ratio under the same reaction conditions, after workup, to give the ligand redistributed products, (ArO)2YbCl-(HMPA)2 (4) and [ONNO]YbCI(HMPA)2 (5) for the former and complexes 5 and (Ph 2N)2YbCl(HMPA)2 (6) for the latter. If the molar ratio of complex 2 to NaNPh2 decreased to 1:4, the expected ligand redistributed products [ONNO]YbNPh2(HMPA) (7) and (Ph 2N)3Yb(HMPA)2·C7H 8 (8) can be isolated in high yields. All of the complexes were well characterized, and the definitive molecular structures of complexes 1-4, 7, and 8 were provided by single-crystal X-ray analysis.
