Molecular-mechanics study of oligomeric models for poly(ferrocenylsilanes) using the ESFF forcefield

Abstract

Molecular mechanics has been employed using the new generalised ESFF forcefield to study the conformations of the oligomeric metallocene species Fc[Fe(C₅H₄)₂SiMe₂]_nH [Fc = Fe(η-C₅H₅)(η-C₅H₄); n= 1 1, 2 2 or 4 3]; the calculations show that the isolated neutral molecules are conformationally flexible with the lowest energy configurations having close contacts between the positively charged iron atoms of the ferrocene units and the negatively charged cyclopentadienyl rings of their neighbours; the lowest energy conformations in the solid state are predicted to be very different due to the possibility of intermolecular iron ⋯ cyclopentadienyl contacts which is in excellent agreement with the crystal structure determinations.