A visualization of the anomeric effect from crystal structures.
Henry S. Rzepa · 2015
The anomeric effect is best known in sugars, occuring in sub-structures such as RO-C-OR.Its origins relate to how the lone pairs on each oxygen atom align with the adjacent C-O bonds.When the alignment is 180°, one oxygen lone pair can donate into the C-O σ* empty orbital and a stabilisation occurs.Here I explore whether crystal structures reflect this effect.The torsion angles along each O-C bond are specified, along with the two C-O distances.All the bonds are declared acyclic, and the usual R < 5%, no disorder and no errors specified.