N-Butyldiethanolamine (N-n-butyldiethanolamine) is a tertiary amine. It acts as an N-substituted diethanolamine ligand. It reacts with chromium(II) and lanthanide(III)/rare earth salts (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) in the presence of coligands to afford three series of isostructural 1:1 3d(Cr(III))/4f(Ln(III)) coordination cluster compounds.