Proton magnetic resonance spectra of partially oriented samples of cyclopentadienyl compounds

Abstract

Transition frequencies and intensities of oriented groups of five spin ½ nuclei with P₅ permutation-group symmetry are derived. The spectra from (cyclopentadienyl)nickel nitrosyl and bis(cyclopentadienyl)mercury as solutes in a nematic phase have been obtained and analysed. Vibrational averaging has been carried out for π bonded cyclopentadienyl systems, and doing so improves the agreement between observed and calculated ratios of dipolar coupling constants. The spectrum of bis(cyclopentadienyl)mercury is found to be consistent with that of a π bonded species, or with a σ-bonded molecule undergoing rapid internal motion.