A tripodal tris-8-aminoquinoline ligand was synthesised in high yield via the Bucherer reaction. The septa-dentate ligand was found to give isolable complexes when coordinated with transition metals. Complexes of zinc(ii), cadmium(ii) and cobalt(iii) were isolated and their solid state structures were determined by single crystal X-ray diffraction. The solid state structures of these complexes were compared to the solution (1)H NMR data which was obtained for each complex. The two first row metals both gave octahedral six coordinate structures, although the two metals were coordinated by a differing donor set of heteroatoms. The cadmium complex was found to contain a seven coordinate cadmium centre in the solid state. DFT calculations were carried out in order to give an indication as to why the two different six coordinate binding modes were encountered.

The title complex, [Cd 2 Cl 4 (C 13 H 17 N 3 ) 2 ]·H 2 O, is centrosymmetic and contains two Cd 2+ ions bridged by two Cl − ions, leading to a strictly planar Cd 2 Cl 2 core. Each Cd 2+ ion is further coordinated by an additional Cl − ion and three N atoms of a tridentate 8-[2-(di­methyl­amino)­ethyl­amino]­quinoline ligand in the form of a considerably distorted octa­hedron for the overall coordination sphere. A lattice water mol­ecule is located on a twofold rotation axis and links pairs of complexes through N—H⋯O and O—H⋯Cl hydrogen bonds.

In the title compound, [Ni(C13H17N3)2]Cl2·3.5H2O, the geom­etry of the NiN6 complex cation is slightly distorted octa­hedral, with a facial arrangement of the two tridentate N-[2-(di­­methyl­amino)­eth­yl]quinolin-8-amine ligands around the metal ion. The asymmetric unit consists of two independent complex half-mol­ecules located on centres of inversion, together with two chloride counter-anions and 3.5 water mol­ecules of solvation, one of which is disordered across an inversion centre. In the crystal, O—H⋯O, O—H⋯Cl and N—H⋯Cl hydrogen-bonding inter­actions form a three-dimensional network structure.

In the title compound, [Cd4Cl8(C6H16N2)4], the Cd2+ cations and Cl− anions form M 4Cl8 clusters with six of the Cl− ions bridging Cd2+ cations and two being pendant. Each Cd2+ cation has distorted octahedral coordination completed by four Cl− ions and two N atoms of the asymmetrical bidentate amino ligand. The cluster consists of pairs of face-sharing hexahedra linked by a shared edge.

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