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Quantum chemical interpretation of the effects induced by tetramethylethylenediamine and dimethoxyethane in RLi non‐polar monomer systems
Author(s) -
Yakimansky Alexander V.,
Vinogradova Ludmila V.,
Erussalimsky Boris L.
Publication year - 1994
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/mats.1994.040030310
Subject(s) - chemistry , dimethoxyethane , denticity , tetrahydrofuran , tetramethylethylenediamine , steric effects , monomer , medicinal chemistry , photochemistry , crystallography , stereochemistry , organic chemistry , crystal structure , polymer , electrode , solvent , electrolyte
The energetic and electronic parameters of various mono‐ and bidentate complexes of CH 3 Li with N‐ and O‐containing electron donors were calculated by the MNDO method. It was shown that N , N , N ′, N′ ‐tetramethylethylenediamine (TMD) forms a more stable bidentate complex with CH 3 Li than 1,2‐dimethoxyethane (DME). However, DME, in contrast to TMD, may form a bis‐bidentate complex with CH 3 Li in which the CLi bond is weakened to a higher degree than in complexes of CH 3 Li with N‐containing electron donors. Much lower steric hindrance of DME, as compared to that of TMD, makes an easy formation of bis‐ and tris‐monodentate complexes of DME with CH 3 Li possible; in these bis‐ and tris‐monodentate complexes DME was simulated by (CH 3 ) 2 O. Parameters of the CLi bond in the tris‐monodentate complexes of (CH 3 ) 2 O and tetrahydrofuran (THF) with CH 3 Li are comparable to those of the bis‐bidentate complex CH 3 Li · 2 DME. These results are in qualitative agreement with experimental data, according to which THF and DME, in contrast to TMD, can favor the formation of separated ion pairs as active sites in anionic polymerization.