A Reactive Intermediate, [Ni5(C6H4N3)6(CO)4], in the Formation of Nonameric Clusters of Nickel, [Ni9(C6H4N3)12(CO)6] and [Ni9(C6H4N3)12(CO)6].2(C3H7NO)

Three new molecular compounds, [Ni5(bta)6(CO)4], I, [Ni9(bta)12(CO)6], II, [Ni9(bta)12(CO)6]. 2(C3H7NO), III, (bta = benzotriazole) were prepared employing solvothermal reactions. Of these, I have pentanuclear nickel, whereas II and III have nonanuclear nickel species. The structures are formed by the connectivity between the nickel and benzotriazole giving rise to the 5- and 9-membered nickel clusters. The structures are stabilised by extensive π…π and C-H... π interactions. Compound II and III are solvotamorphs as they have the same 9-membered nickel clusters and have different solvent molecules. To the best of our knowledge, the compounds I–III represent the first examples of the same transition element existing in two distinct coordination environment in this class of compounds. The studies reveal that compound I is reactive and could be an intermediate in the preparation of II and III. Thermal studies indicate that the compounds are stable upto 350∘C and at higher temperatures (∼ 800∘C) the compounds decompose into NiO. Magnetic studies reveal that II is anti-ferromagnetic.