Dual catalytic performance of arene-ruthenium amine complexes for norbornene ring-opening metathesis and methyl methacrylate atom-transfer radical polymerizations
Abstract: Arene ruthenium(II) complexes bearing the cyclic amines RuCl2(eta(6)-p-cymene)(pyrrolidine)] (1), [RuCl2(eta(6)-p-cymene)(piperidine)] (2), and [RuCl2(eta(6)-p-cymene)(peridroazepine)] (3) were successfully synthesized. Complexes 1-3 were fully characterized by means of Fourier transform infrared, UV-visible, and NMR spectroscopy, elemental analysis, cyclic voltammetry, computational methods, and one of the complexes was further studied by single crystal X-ray crystallography. These compounds were evaluated as catalytic precursors for ring-opening metathesis polymerization (ROMP) of norbornene (NBE) and atom-transfer radical polymerization (ATRP) of methyl methacrylate (MMA). NBE polymerization via ROMP was evaluated using complexes 1-3 as precatalysts in the presence of ethyl diazoacetate (EDA) under different [NBE]/[EDA]/[Ru] ratios, temperatures (25 and 50 degrees C), and reaction times (5-60 min). The highest yields of polyNBE were obtained with [NBE]/[EDA]/[Ru] = 5000/28/1 for 60 min at 50 degrees C. MMA polymerization via ATRP was conducted using 1-3 as catalysts in the presence of ethyl-alpha-bromoisobutyrate (EBiB) as initiator. The catalytic tests were evaluated as a function of the reaction time using the initial molar ratio of [MMA]/[EBiB]/[Ru] = 1000/2/1 at 95 degrees C. The increase in molecular weight as function of time indicates that complexes 1-3 were able to mediate the MMA polymerization with an acceptable rate and some level of control. Differences in the rate of polymerization were observed in the order 3 > 2 > 1 for the ROMP and ATRP.
Author(s): Cruz, TR; Silva, EA; Oliveira, DP; Martins, DM; Gois, PDS; Machado, AEH; Maia, PIS; Goi, BE; Lima-Neto, BS; Carvalho, VP
APPLIED ORGANOMETALLIC CHEMISTRY
Published: FEB 2020
DOI: 10.1002/aoc.5602
