Molecular Metal Sulfide Cluster Model for Substrate Binding to Oil-Refinery Hydrodesulfurization Catalysts

Reaction between [(η5-Cp‘)3Mo3S4]+ and [Ni(1,5-cod)2] (Cp‘ =
methylcyclopentadienyl; 1,5-cod = 1,5-cyclooctadiene) in THF at
ambient temperature yielded a coordinatively unsaturated cubane-like cluster cation, [(η5-Cp‘)3Mo3S4Ni]+. The ligand sphere at the
Ni atom could be saturated by coordinating dimethyl sulfide, diethyl
sulfide, di(tert-butyl) sulfide, tetrahydrothiophene, thiochroman-4-ol, 1,4-dithiane, pyridine, quinoline, or 4,4‘-bipyridine. The products
structurally model a mode of substrate coordination on proposed
binding sites of heterogeneous MoNi sulfide hydrotreating catalysts.
No stable coordination compounds could be isolated for thiophene
derivatives. X-ray crystal structures are reported for the ligand-bridged dicluster compounds [{(η5-Cp‘)3Mo3S4Ni}2(μ-C4H4S2)][pts]2
(C4H8S2 = 1,4-dithiane) and [{(η5-Cp‘)3Mo3S4Ni}2(μ-bipy)][pts]2
(bipy = 4,4‘-bipyridine).