A FACILE ENRICHMENT IN 13CO OF TETRAIRIDIUM CARBONYL CLUSTER COMPOUNDS PROMOTED BY TRIMETHYLAMINE OXIDE

Abstract The reactions of anionic clusters [Ir 4 (CO) 11 X] − (X=Br, I), with excess of 13 CO gave enriched Ir 4 ( * CO) 12 ; the level of 13 CO enrichment was 9.2%, corresponding to stoichiometric replacement of the labile ligand X − . From the enriched Ir 4 ( * CO) 12 the equi-enriched derivatives [Ir 4 ( * CO) 11 X] − can be prepared, on which the exchange of X − with 13 CO can be carried out again. This 12 CO–(X − )– 13 CO exchange cycle can be repeated until required. An alternative process for more profitable and general enrichment of Ir 4 (CO) 12 derivatives involves replacement of coordinated 12 CO by free 13 CO promoted by Me 3 NO, which acts as an oxidative decarbonylating reagent.