TY - JOUR
T1 - Coordination of ϵ-Caprolactone to a Cationic Niobium(V) Alkoxide Complex: Fundamental Insight into Ring-Opening Polymerization via Coordination-Insertion
AU - Buchard, Antoine
AU - Davidson, Matthew G.
AU - Gobius du Sart, Gerrit
AU - Jones, Matthew D.
AU - Kociok-Köhn, Gabriele
AU - McCormick, Strachan N.
AU - Mckeown, Paul
N1 - Funding Information: We wish to thank the University of Bath for a studentship to S.N.M., and EPSRC (EP/L016354/1; Centre for Doctoral Training in Sustainable Chemical Technologies; EP/P016405/1, funded P.M. PDRA position) and TotalEnergies Corbion for supporting this work. A.B. acknowledges the Royal Society (UF/160021 fellowship). Analytical facilities and expertise were provided through the Material and Chemical Characterization Facility (MC) at the University of Bath ( https://www.bath.ac.uk/research-facilities/material-and-chemical-characterisation-facility-mc2/ ). 2
PY - 2023/9/25
Y1 - 2023/9/25
N2 - We report three niobium-based initiators for the catalytic ring-opening polymerization (ROP) of ϵ-caprolactone, exhibiting good activity and molecular weight control. In particular, we have prepared on the gram-scale and fully characterized a monometallic cationic alkoxo-Nb(V) ϵ-caprolactone adduct representing, to the best of our knowledge, an unprecedented example of a metal complex with an intact lactone monomer and a functional ROP-initiating group simultaneously coordinated at the metal center. At 80 °C, all three systems initiate the immortal solution-state ROP of ϵ-caprolactone via a coordination-insertion mechanism, which has been confirmed through experimental studies, and is supported by computational data. Natural bond orbital calculations further indicate that polymerization may necessitate isomerization about the metal center between the alkoxide chain and the coordinated monomer. The observations made in this work are expected to inform mechanistic understanding both of amine tris(phenolate)-supported metal alkoxide ROP initiators, including various highly stereoselective systems for the polymerization of lactides and of coordination-insertion-type ROP protocols more broadly.
AB - We report three niobium-based initiators for the catalytic ring-opening polymerization (ROP) of ϵ-caprolactone, exhibiting good activity and molecular weight control. In particular, we have prepared on the gram-scale and fully characterized a monometallic cationic alkoxo-Nb(V) ϵ-caprolactone adduct representing, to the best of our knowledge, an unprecedented example of a metal complex with an intact lactone monomer and a functional ROP-initiating group simultaneously coordinated at the metal center. At 80 °C, all three systems initiate the immortal solution-state ROP of ϵ-caprolactone via a coordination-insertion mechanism, which has been confirmed through experimental studies, and is supported by computational data. Natural bond orbital calculations further indicate that polymerization may necessitate isomerization about the metal center between the alkoxide chain and the coordinated monomer. The observations made in this work are expected to inform mechanistic understanding both of amine tris(phenolate)-supported metal alkoxide ROP initiators, including various highly stereoselective systems for the polymerization of lactides and of coordination-insertion-type ROP protocols more broadly.
U2 - 10.1021/acs.inorgchem.3c02491
DO - 10.1021/acs.inorgchem.3c02491
M3 - Article
SN - 0020-1669
VL - 62
SP - 15688
EP - 15699
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 38
ER -