Study of the Growth Centres of the Anionic Polymerization of (Meth)acrylates. VI. MO LCAO SCF Study of the Model Dimer, Its Solvation and Aggregation States

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Title:Study of the Growth Centres of the Anionic Polymerization of (Meth)acrylates. VI. MO LCAO SCF Study of the Model Dimer, Its Solvation and Aggregation States
Creators:
Dybal, Jiří
Kříž, Jaroslav
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 60, 10, pp. 1609-1620

Abstract

<p>The nature of the intramolecular coordination in dimethyl 2-lithio-2,4,4-trimethylglutarate (<i>I</i>) as the model of living dimer of methyl methacrylate was studied by comparison with the specific solvation of methyl 2-lithioisobutyrate, using <i>ab initio</i> SCF calculations with the 3-21G basis set. In both cases, electron-density donation from the incident oxygen leads to a weak coordination bond (20 to 30% of full covalency) accompanied by polarization and weakening of the original O-Li bond. The directionality of any O-Li or C-Li bond in all the systems under study is poor and the position of Li results from a complex interplay of covalent and electrostatic interactions with its molecular environment. The covalent part of the bond system can be characterized as a system of polycentric electron-defficient bonds. Possible conformational geometries of <i>I</i> were examined by <i>ab initio</i> calculations and the results were compared to those of the semiempirical MNDO method. The inclination of MNDO to create artificial local energy minima in previously unsuspected cases was detected and shown to be avoidable if the valence sphere of Li is saturated by electron donors. The formation of aggregation dimers of <i>I</i> was studied by MNDO and the most stable conformers were found. The study was paralleled for the di-<i>tert</i>-butyl ester analogue of <i>I</i>. The tendency of <i>I</i> to intramolecular coordination and self-aggregation is discussed in view of the known kinetics of the first steps of anionic propagation.

Title:Study of the Growth Centres of the Anionic Polymerization of (Meth)acrylates. VI. MO LCAO SCF Study of the Model Dimer, Its Solvation and Aggregation States
Creators:
Dybal, Jiří
Kříž, Jaroslav
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:60
Number:10
Page Range:pp. 1609-1620
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19951609UNSPECIFIED
ID Code:856
Item Type:Article
Deposited On:06 Feb 2009 17:04
Last Modified:06 Feb 2009 16:04

Citation

Dybal, Jiří; Kříž, Jaroslav (1995) Study of the Growth Centres of the Anionic Polymerization of (Meth)acrylates. VI. MO LCAO SCF Study of the Model Dimer, Its Solvation and Aggregation States. Collection of Czechoslovak Chemical Communications, 60 (10). pp. 1609-1620. ISSN 0010-0765

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