A structural and carbon-nitrogen bond rotation study of N,N,N',N',2,2-hexamethylpropanediamide

Abstract

The molecular structure of N,N,N',N',2,2-hexamethylpropanediamide has been determined in the solid state by X-ray diffraction methods. The structure of Me₂NCOCMe₂CONMe₂ may be broadly described as two planar Me₂NCO entities intersecting at the tetrahedral -CMe₂- site. The angle between the normals to the two Me₂NCO planes is 104.6º, and the two oxygen atoms are disposed outwards from the molecule and away from each other.

Proton (270-MHz) n.m.r. studies yield k(320 K) 32.0 ± 3.2 s^-1, ΔH^‡ 69.5 ± 0.4 kJ mol^-1 and ΔS^‡ 0.6 ± 1.1 J K^-1 mol^-1 for rotation of the N-methyl groups about the carbon-nitrogen bonds in CD₃NO₂ solution. Similar magnitudes for the kinetic parameters characterizing this process are obtained in CDCl₃, and CD₃CN solutions.