The preparation and co-ordination chemistry of 2,2′: 6′,2″-terpyridine macrocycles. Part 3. Transient template effects involving dimethyltin(IV)

Complexes of a novel quinquedentate ligand L¹, which incorporates a 2,2′: 6′,2″-terpyridine moiety, are prepared via template condensations about nickel(II) or manganese(II). The crystal and molecular structure of [NiL¹(EtOH)₂][BF₄]₂ shows the metal to be in a pentagonal-bipyramidal N₅O₂ environment. The free ligand L¹ may be obtained as its dication from template condensations in which there is a mismatch between the donor properties of the ligand and the acceptor properties of the metal ion. Thus [H₂L¹] [PF₆]₂ may be isolated from the template condensation about Cr³⁺ or [SnMe₂]²⁺. The crystal and molecular structure of [H₂L¹][PF₆]₂ is reported, and the origin of this novel template effect is discussed.