Assembly of a Tetranuclear Host with a Tris(benzene-o-dithiolato) Ligand

The preparation of the first dinuclear triple-stranded helicates based on bis(benzene-o-dithiolato) and mixed benzene-o-dithiolato/catecholato ligands is analyzed. The analogous ligand reacts with Ti4+ to yield a dinuclear triple-stranded helicate. The use of the organic cations resulted in a red precipitate and allowed for the isolation of the complex as a red solid. The potassium cation resides on the twofold axis passing through the center of the octaanion. One half of a positive charge per asymmetric unit could not be located. It was assumed that each asymmetric unit either contains half of a discorded lithium cation or that a lithium cation is also located on the twofold axis. Both the highfield shift of the resonances of the benzimidazolium cation and the observed line broadening are indications for a fast exchange of benzimidazolium cations between the inside and the outside of the octanuclear octaanion.