Triangulo-pentahalotrimetal complexes of nickel(II) and cobalt(II) with N,N,N′,N′,N-tetramethylethane-1,2-diamine and related compounds

Nickel(II) and cobalt(II) form complexes [M3Cl5(neutral didentate ligand)3]+ containing the triangulo-trihalotrimetal moieties with considerable ease, and they are very similar in structure to the known titanium, vanadium, and iron homologues. However, chromium and copper are not. The supporting neutral ligand is almost invariably N,N,N′,N′-tetramethylethane-1,2-diamine. These compounds show a great affinity for water and react to lose one apical chloride to be replaced by hydroxide. The analogous bromide derivatives have also been prepared and characterised. For the first time, a triangulo-trihalotrimetal compound containing fluoride has also been prepared.