Aminoarenethiolate Aluminum Complexes: Synthesis, Characterization, and Use in <scp>l</scp>-Lactide Polymerization
作者:Lorena Postigo、Marı́a del Carmen Maestre、Marta E. G. Mosquera、Tomás Cuenca、Gerardo Jiménez
DOI:10.1021/om400111f
日期:2013.5.13
Reaction of AlMe3 with S(SiMe3)(C6H3-2-CH2NRR'-5-Bu-t) (RR' = C5H10 (1a), C4H8 (1b), Me-2 (1c)), at ambient temperature, affords the amino adducts [AlMe3S(SiMe3)(C6H3-2-CH2NRR'-5-Bu-t)}-kappa N] (RR' = C5H10 (2a), C4H8 (2b), Me-2 (2c)), which undergo TMS elimination upon heating to give the monomeric aminoarenethiolate aluminum complexes [AlMe2S(C6H3-2-CH2NRR'-5-Bu-t)-kappa S-2,N}] (RR' = C5H10 (3a), C4H8 (3b), Me-2 (3c)). Following the same procedure, treatment of AlCl2Me and AlCl3 with 1 yields analogous aminoarenethiolate aluminum complexes with different degrees of methylation, the chloro methyl and dichloro complexes [AlClMeS(C6H3-2-CH2NRR'-5-Bu-t)-kappa S-2,N}] (RR' = C5H10 (4a), C4H8 (4b), Me-2 (4c)) and [AlCl2S(C6H3-2-CH2NRR'-5-Bu-t)}-kappa S-2,N] (RR' = C5H10 (5a), C4H8 (5b) Me2 (5c)), respectively. These complexes have been characterized by multinuclear NMR spectroscopy and elemental analysis. Moreover, the molecular structures of 3a,b have been determined by X-ray diffraction methods. Aluminum complexes 3 have been investigated for the ring-opening polymerization (ROP) of L-lactide, achieving high conversions in relatively short periods of time. The PLAs obtained feature an aminoarenethiolate end functionality, as inferred from MALDI-TOF mass analysis.