Anionic Polymerization of (Meth)acrylates in the Presence of Tetraalkylammonium Halide−Trialkyl Aluminum Complexes in Toluene. 2. † NMR and Quantum-Chemical Study on the Structure of Ester Enolate Complexes as Models of the Active Center

6Li and 13C NMR investigations on ethyl α-lithioisobutyrate (EiBLi) and quantum-chemical (DFT) calculations on methyl α-lithioisobutyrate (MiBLi) were performed to study the structure of active centers in anionic polymerization of methacrylates in toluene in the presence of tetramethylammonium chloride/triethylaluminum complexes NMe4[Al n Et3 n Cl] (n = 1, 2). The results support the existence of several complex species ([EiBLi·Al n Et3 n Cl]NMe4) m varying in composition (n = 1, 2) and degree of association (m = 1, 2). In the presence of methyl pivalate (MPiv), a model compound for monomer/polymer ester groups, a nonassociated complex NMe4[EiBLi·MPiv·AlEt3Cl] is preferably formed.