Synthesis of an asymmetrical tripodal tetraamine ligand and its five-coordinate copper(II) complex

A simple synthesis has been devised for the tripodal 3,3,4-tetraamine ligand N{(CH2)3NH2}2{(CH2)4NH2} (L). This ligand forms a copper(II) complex, [Cu (LH)Cl2]ClO4 (7), the structure of which has been determined by X-ray diffraction. The cation contains a five-coordinate copper atom, bonded to two chloride ions, the two propylamine groups and the tertiary nitrogen atom of the ligand; the arrangement is a distorted trigonal bipyramid, in which the two primary amine groups occupy the axial positions. The butylamine group of the ligand does not coordinate to copper but is protonated. It is involved in hydrogen bonding to the perchlorate ion. The e.p.r. spectrum of [Cu(dpt)Cl2] is very similar to that of (7), suggesting that it also has a trigonal bipyramidal structure. This revised version was published online in June 2006 with corrections to the Cover Date.