Details

Autor(en) / Beteiligte

• Champouret, Yohan
• MacLeod, K. Cory
• Smith, Kevin M
• Patrick, Brian O
• Poli, Rinaldo

Titel

Controlled Radical Polymerization of Vinyl Acetate with Cyclopentadienyl Chromium β-Diketiminate Complexes: ATRP vs OMRP

Ist Teil von

• Organometallics, 2010-07, Vol.29 (14), p.3125-3132

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2010

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The ability of compounds CpCrII(nacnacAr,Ar) (Ar = Dipp, 1; Xyl, 2) to catalyze the atom transfer radical polymerization (ATRP) of vinyl acetate has been explored using methyl 2-chloropropionate as initiator. Polymerizations were also carried out under reverse ATRP conditions with thermal initiation by 2,2′-azobis(4-methoxy2,4-dimethylvaleronitrile) (V-70) in the presence of compounds CpCrIII(nacnacAr,Ar)Cl (Ar = Dipp, 3; Xyl, 4). All data suggest that these processes are in fact proceeding by organometallic-mediated radical polymerization (OMRP). Stoichiometric reactions between complex 2 and the chlorinated compounds CH3CH(Cl)COOCH3, ClCH2COPh, CH3CHClOOCCH3, ClCH2OOCtBu, and ClCH2 tBu in the absence of monomer aid in the interpretation of the polymerization results. The first two substrates show rapid one-electron oxidative additions to generate 4 and O-bonded CrIII products, whereas the third and fourth substrates add much more slowly to generate 4 and C-bonded CrIII products; ClCH2 tBu does not react. DFT calculations on the competitive radical trapping processes (activation barriers and relative stability of the products) confirm the kinetic and thermodynamic preference for metal−carbon bond formation to generate the dormant species of OMRP.