New Heterometallic Cubane-Like Clusters [{(η⁵-Cp)Mo}₃S₄{M‘(CO)₃}](pts) (M‘ = Cr, Mo, W; pts = p-Toluenesulfonate) Obtained by Ligand Substitution Reactions and Insertion of {M‘(CO)₃} Fragments

A series of group 6 heterometallic sulfide clusters have been prepared to establish a route to potential models of hydrodesulfurization catalysts suitable for application in nonaqueous media. The cluster compound [{(H₂O)₃Mo}₃S₄](pts)₄·9H₂O (pts = p-toluenesulfonate) was treated with triethyl orthoformate in the presence of a catalytic amount of Hpts to yield an ethanol complex of the [Mo₃S₄]⁴⁺ cluster core. The complex was subsequently converted in situ to acetonitrile and tetrahydrofuran complexes before treatment with thallium cyclopentadienide to yield the new cluster compound [{(η⁵-Cp)Mo}₃S₄](pts) (1). Insertion of {M‘(CO)₃} fragments into 1 afforded the series of cubane-like, heterometallic clusters [{(η⁵-Cp)Mo}₃S₄{M‘(CO)₃}](pts) (M‘ = Cr (2a), Mo (2b), W (2c)). Single-crystal X-ray analysis established the heterometallic S₄-capped tetrahedral cluster core in the structure of 2c·¹/₂CH₃OH.