Penta and hexanuclear nickel tiara-like clusters with two different thiolate bridges

Abstract

Six nickel tiara-like clusters, cyclo-[Ni(μ-EDT)]₅ (1), cyclo-{[Ni(μ-SiPe)₂]₆} (2), cyclo-[Ni₆(μ-StBu)₄(μ-EDT)₄] (3), cyclo-[Ni₆(μ-StBu)₄(μ-PDT)₄] (4), cyclo-[Ni₆(μ-SPh)₄(μ-EDT)₄] (5) and cyclo-[Ni₆(μ-SPh)₄(μ-PDT)₄] (6) (StBu = 2-methyl-2-propanethiol, EDT = 1,2-ethanedithiol, PDT = 1,3-propanedithiol, SiPe = isopentylthiol, SPh = thiophenol have been successfully synthesized and characterized. All the clusters were derived from a designed preparation by a direct synthetic route involving reactions of Ni(ClO₄)₂ with mixed thiolate or disulfide ligands which have discrepancy in their coordination ability. Intriguingly, cluster 1 is an infrequent pentanuclear tiara. Clusters 3 and 4 are hexanuclear tiaras with two different types of mono and bidentate aliphatic thiolates. Clusters 5 and 6 exhibit similar structures with monoaromatic thiolate and bidentate aliphatic thiolate ligands. The –SPh ligands were generated from an in situ reaction of the disulfide precursor through cleavage of the S–S bond. These heretofore unknown additions to the cyclo-[Ni(μ-SR)₂]_n tiara family are of particular interest, which are often constructed by just one kind of thiolate ligand.