Role of torsional strain in the ring-opening polymerisation of low strain [n]nickelocenophanes.

ABSTRACT: Ring-opening polymerisation (ROP) of strained [1]- and [2]metallocenophanes and related species is well-established, and the monomer ring-strain is manifest in a substantial tilting of the cyclopentadienyl ligands, giving α angles of ∼14-32°. Surprisingly, tetracarba[4]nickelocenophane [Ni(η⁵-C₅H₄)₂(CH₂)₄] (2) undergoes ROP (pyridine, 20 °C, 5 days) to give primarily insoluble poly(nickelocenylbutylene) [Ni(η⁵-C₅H₄)₂(CH₂)₄] _n (12), despite the lack of significant ring-tilt. The exoenthalpic nature of the ROP was confirmed by DFT calculations involving the cyclic precursor and model oligomers (ΔH0ROP = -14 ± 2 kJ mo

SUBMITTER: Musgrave RA 

PROVIDER: S-EPMC6977548 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature