title: Novel highly active niobium catalysts for ring opening metathesis polymerization of norbornene.
abstract: Ring-opening metathesis polymerization (ROMP) of norbornene catalyzed by niobium(V) N,N-dialkylcarbamates Nb(O(2) CNR(2) )(5) , R = Et (1), Me (2) was studied in the presence of methylaluminoxane (MAO) as a cocatalyst. These novel catalytic systems resulted very active in chlorobenzene: 1 in the presence of methylaluminoxane catalyzes the ROMP of norbornene with the highest activity (29 000 kg of polymer/mol of catalyst × hour) never reported up to now for niobium catalysts. The high productivity appears particularly attractive considering that these precursors are rather cheap and easy to synthesize and to handle. Polynorbornenes were characterized by FT-IR and NMR spectroscopies and by DSC calorimetry. A new FT-IR method for the swift determination of the cis/trans content of the polymer is presented.
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, University of Pisa, via Risorgimento 35, 56126 Pisa, Italy. roxy@dcci.unipi.it.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Raspolli Galletti
authors.forename: Guido
authors.initials: G
authors.lastname: Pampaloni
authors.forename: Aldo
authors.initials: A
authors.lastname: D'Alessio
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Patil
authors.forename: Filippo
authors.initials: F
authors.lastname: Renili
authors.forename: Simone
authors.initials: S
authors.lastname: Giaiacopi