Silicon-29 and carbon-13 longitudinal nuclear spin relaxation study on molecular dynamics of 1,4-bis(trimethylsilyl)1,3-butadiyne in solution

Abstract

The longitudinal nuclear spin relaxation times and NOE coefficients of 13C and 29Si nuclei of 1,4-bis(trimethylsilyl)-1,3-butadiyne have been measured in chloroform solution. The shielding anisotropy parameters for acetylenic carbons have been estimated on the basis of the 1H and 13C NMR spectra including the 29Si satellites in nematic solvents EBBA and ZLI1114. The chemical-shift anisotropy relaxation of acetylenic carbons has provided information on the rotational diffusion about the direction perpendicular to the long axis of the molecule. Two remaining diffusion coefficients characterizing the rotation of the trimethylsilyl group and the methyl groups could be calculated using data on the dipoledipole relaxation of 29Si and methyl 13C nuclei.