Sterically hindered tetrylenes based on new 1,10-phenanthroline-containing diols: initiators for ε-caprolactone polymerizationстатья
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Дата последнего поиска статьи во внешних источниках: 16 сентября 2020 г.
Аннотация:Previously unknown tetradentate ONNO-type ligands 1-5 (4,7-di(4-R'-phenoxy)-2,9-di(HOCR2CH)-1,10-phenanthrolines (R' = Me, R-R = -(CH2)(5)- (1), R = Me (2), R-R = 2,2-adamantylene (3); R' = Bu-t, R-R = -(CH2)(5)- (4), R = Me (5)) were synthesized by sequential treatment of 2,9-dimethyl-4,7-di(4-R'-phenoxy)-1,10-phenanthrolines 6 (R' = Me) and 7 (R' = Bu-t) with excess LDA and appropriate dialkyl ketone. The structure of compound 4 was determined by single-crystal X-ray diffraction. Previously uncharacterized phenanthroline 6 was synthesized by the treatment of 4,7-dichloro-2,9-dimethyl-1,10-phenanthroline with excess p-cresol in the presence of KOH. The reaction of compounds 1-5 with one equivalent of Lappert's germylene or stannylene, M[N(SiMe3)(2)](2) (M = Ge, Sn), gave the corresponding germylenes 8-12 (M = Ge, R' = Me, R-R = -(CH2)(5)- (8), R = Me (9), R-R = 2,2-adamantylene (10), R' = Bu-t, R-2 = -(CH2)(5)- (11), R = Me (12)) and stannylenes 13-17 (M = Sn, R' = Me, R-R = -(CH2)(5)- (13), R = Me (14), R-R = 2,2-adamantylene (15), R' = Bu-t, R-R = -(CH2)(5)- (16), R-2 = Me (17)) in satisfactory yields. According to H-1, C-13, and Sn-119 NMR data, the synthesized stannylenes are monomeric in solution, and the tin atom has a coordination number of 4. In the series of the compounds under consideration, stannylene 16 proved to be the most active initiator for epsilon-caprolactone polymerization, whereas the germylenes were shown to be inactive in this process.