A unique ruthenium-thiolate molecular rhomboid ([square tilted open])-[Ru(SAr)2(CO)2]8, which consists of eight octahedra linked by alternate face- and vertex-sharing, was produced by isomerization of the molecular wheel (○)-[Ru(SAr)2(CO)2]8 at elevated temperature. The use of a (○)-[Ru(SAr)2(CO)2]6 wheel for catalytic aziridination of alkenes via nitrene transfer is also described.