Premium
Polymerizability of Cycloalkenes in “Living” Ring‐Opening Metathesis Polymerization Initiated by Schrock Complexes, 2. Effect of Initiator Structure
Author(s) -
Cazalis Chrystelle,
Héroguez Valérie,
Fontanille Michel
Publication year - 2001
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20010601)202:9<1513::aid-macp1513>3.0.co;2-7
Subject(s) - norbornene , chemistry , monomer , polymerization , metathesis , polymer chemistry , cyclohexane , reactivity (psychology) , ring opening metathesis polymerisation , alkoxy group , organic chemistry , polymer , medicine , alternative medicine , pathology , alkyl
The kinetics of ring‐opening metathesis polymerization of norbornene were investigated in cyclohexane using several Schrock complexes as initiators. Three different Schrock complexes were used: Mo(CHC(CH 3 ) 2 Ph)(NAr)(O‐ t ‐Bu) 2 (NAr = Ph (iPr) 2) ( I ), Mo(CHC(CH 3 ) 2 Ph)(NAr)(OC(CF 3 ) 2 CH 3 ) 2 (NAr = Ph (iPr) 2) ( II ) and W(CH‐ t ‐Bu)(NAr)(O‐ t ‐Bu) 2 (NAr = Ph (iPr) 2) ( III ). The presence of alkoxy‐fluorinated ligands on II and on the corresponding propagating species enhances the polymerizability of norbornene and modifies the kinetic scheme compared to that of polymerizations initiated by the tert ‐butoxy complex. The greater electropositive character of II compared to that of I results in a majority of metalla‐alkylidenic growing species being complexed to monomer; therefore, the coordination of the monomer is not the rate‐determining step for the process. In contrast, the major part of growing species, which are derived from the tert ‐butoxy complex are in a non‐coordinated state and, thus, the ability of the initiator to complex the monomer is decisive. In addition, this study allows to quantify the stronger reactivity of W‐based complexes compared to that of Mo‐based ones. These results were all corroborated by prior theoretical studies using ab initio calculations.