Cp*IrCl 2 ] 2 reacts with 2 equiv of Na 2 NCN to afford the NCN-bridged diiridium complex [Cp*Ir-(µ 2 -NCN-N,N)] 2 (5), which undergoes further reactions with donor molecules such as CO and phosphines. Complex 5 works as an excellent building block for the synthesis of the NCN-capped heterotrinuclear complexes [(Cp*Ir) 2 (ML)(µ 3 -NCN-N,N,N) 2 ] + (ML ) Rh(cod), CpRu, Pd(η 3 -C 3 H 5 )) on reactions with cationic group 8-10 metal complexes such as [Rh(cod)(acetone) n ] + , [CpRu-(MeCN) 3 ] + , and [Pd(η 3 -C 3 H 5 )(acetone) n ] + , while the dimerization of 5 leads to the cubane-type tetrairidium complex [Cp*Ir(µ 3 -NCN-N,N,N)] 4 .

Treatment of a sulfido- and thiolato-bridged diiridium complex [(Cp*Ir)2(μ-S)(μ-SCH2CH2CN)2] (3; Cp* = η5-C5Me5) with [CpRuCl(tmeda)] (Cp = η5-C5H5; tmeda = N,N,N‘,N‘-tetramethylethylenediamine) gave the Ir2Ru sulfido-thiolato cluster [(Cp*Ir)2(CpRu)Cl(μ3-S)(μ2-SCH2CH2CN)2] (4), the core structure of which is the same as that of the previously reported Cp*Ru analogue [(Cp*Ir)2(Cp*Ru)Cl(μ3-S)(μ2-SCH2CH2CN)2] (2), but the geometry around one Ir atom and the orientation of the cyanoethyl group in one thiolato ligand differ from those in 2. Cluster 4 reacted with L (L = CO and XyNC; Xy = 2,6-Me2C6H3) in the presence of KPF6 to afford [(Cp*Ir)2(CpRu)(L)(μ3-S)(μ2-SCH2CH2CN)2][PF6] (5), in which the ligand L is bonded to one Ir center in a terminal end-on fashion. On the other hand, the reaction of 4 with MeOCOC⋮CCOOMe (DMAD) resulted in the insertion of DMAD into the Ru−Ssulfido bond, yielding the cluster [(Cp*Ir)2(CpRu){μ3-SC(COOMe)CCOOMe}(μ2-SCH2CH2CN)2][PF6] (6). In 6, the DMAD molecule bridges the Ru and μ2-S atoms, and the resulting CC bond in the DMAD moiety further coordinates to one Ir atom in a side-on manner. To confirm the difference in the reactivities toward alkynes between the Ir sites in 4 and 2, reaction of DMAD with 2 was carried out, which resulted in the formation of the alkenylthiolato cluster [(Cp*Ir)2(Cp*Ru)(μ3-S){μ3-SC(COOMe)CHCOOMe}(μ2-SCH2CH2CN)][PF6] (8) containing the DMAD moiety bonded to the two Ir atoms. Cluster 6 dissolved in MeCN reacted further with CO (10 atm) at 80 °C and XyNC at 60 °C to give [(Cp*Ir)2(CpRu)(L){μ3-SC(COOMe)CCOOMe}(μ2-SCH2CH2CN)2][PF6] (9), where the migration of the DMAD moiety occurred to form the iridathiacyclobutene moiety, accompanied by the coordination of L to the other Ir site. The X-ray analyses have been undertaken to determine the detailed structures for five new clusters:  4, the BPh4 analogue of 5b (L = XyNC) [(Cp*Ir)2(CpRu)(XyNC)(μ3-S)(μ2-SCH2CH2CN)2][BPh4], 6, 8, and 9b (L = XyNC).