Isocyanide substitution in octadecacarbonyl hexaosmium

The crystal structures of the two isocyanide substituted hexaosmium clusters, Os6 (CO)18 (CNC6 H4 Me)2 and Os6 (CO)16 (CNCMe3)2 are reported. The former involves both a triple bridging and a terminal isonitrile group whilst the latter is related to the parent carbonyl Os6 (CO)18. The molecular structures are discussed in terms of electronic inequivalences within the metal cluster framework.