Stereospecific Ring‐Opening Metathesis Polymerization of Norbornene Catalyzed by Iron Complexes
Dmitry S. Belov, Logesh Mathivathanan, Melanie J. Beazley, William Blake Martin, Konstantin V. Bukhryakov
Abstract
Abstract Developing well‐defined iron‐based catalysts for olefin metathesis would be a breakthrough achievement in the field not only to replace existing catalysts by inexpensive metals but also to attain a new reactivity taking advantage of the unique electronic structure of the base metals. Here, we present a two‐coordinate homoleptic iron complex, Fe(HMTO) 2 [HMTO=O‐2,6‐(2,4,6‐Me 3 C 6 H 2 ) 2 C 6 H 3 ], that is capable of performing ring‐opening metathesis polymerization of norbornene to produce highly stereoregular polynorbornene (99 % cis, syndiotactic). The use of heteroleptic Fe(HMTO)(RO) [RO=(CH 3 ) 2 CF 3 CO, CH 3 (CF 3 ) 2 CO, or Ph(CF 3 ) 2 CO] prepared in situ significantly increases the polymerization rate while preserving selectivity. The resulting polymers were characterized by 1 H and 13 C NMR spectroscopy and gel‐permeation chromatography.