Cyclohexylamine

The amino group has a conformational energy of 1.40 kcal/mol, lower than that of methyl (1.75 kcal/mol), even though the C-N bond distance (0.147 nm) is slightly shorter than the C-C (0.154 nm). That is reasonable if we consider that NH₂ has fewer hydrogens than CH₃. The single C-N bond can rotate as all single bonds do and the NH₂ can easily place its two hydrogens outside the ring. The comparison between the conformational energies of NH₂ and CH₃ groups is proof that a hydrogen with a nucleus -as in CH₃⁻ is less diffuse than an electron pair -as in NH₂⁻ thus taking room in space.