Chemistry Weekly Seminar - Satavisha Bhattacharya, PhD Candidate, University of Saskatchewan

Topic:

Silicon-bridged [1]Metallocenophanes: Strained Monomers for Metallopolymers

Within a decade of the discovery of ferrocene in the 1950s, the first ansa-metallocenes, or [n]metallocenophanes (Figure 1), were prepared. These species possess n number of bridging atoms E between the cyclopentadienyl (Cp) rings, thereby tilting them about the metal centre (see tilt angle α in Figure 1). [n]Metallocenophanes with a large tilt angle α are highly strained and strongly susceptible to strain release by ring-opening polymerisation (ROP). The strain may be varied by changing the metal M and/or the bridging element E (Figure 1). Amongst the ones known so-far, [1]ferrocenophanes (M = Fe) represent the most widely explored class of strained sandwich compounds.

In 1992, Manners et al. reported access to high-molecular weight polymers from sila[1]ferrocenophanes (M = Fe; E = Si). This key discovery opened-up a new research field in polymer chemistry which has expanded ever since.

With a long-term interest in strained sandwich compounds research in the Müller group has been directed towards the development of new synthetic strategies and monomers for ROP. This presentation highlights the relevant aspects of my doctoral research aimed at developing strained monomers and exploring their ROP behaviour. Initially, sila[1]ferrocenophanes with diverse alkyl groups on the Cp rings were prepared and subjected to thermally and anionically induced ring-opening polymerisations. Progression was later made towards the synthesis of strained [1]ruthenocenophanes (M = Ru), specifically sila[1]ruthenocenophane. These most recent results fill a knowledge gap for “phanes” that exists for almost 30 years.

Date:    Friday, January 28

Time:    1:30 pm

Zoom link available by request to chem.dept@usask.ca