Ligand substitution reactions of bis(μ-acetato)dichlorodicarbonyldiiridium(II)

Seven diiridium(II) complexes were synthesized by ligand substitution reactions of [Ir2(μ-O2CMe)2Cl2(CO)2] (1) and [Ir2(μ-O2CMe)2Cl2(CO)2(py)2] (2).The reaction of 2 with the silver salt of a less coordinating anion, AgSbF6, gave a cationic complex [Ir2(μ-O2CMe)2Cl(CO)2(py)3]SbF6 (3).A tricarbonyl cationic complex [Ir2(μ-O2CMe)2(CO)3Cl(py)2]SbF6 (4) was obtained under a CO atmosphere.Complex 2 reacted with AgO2CCF3 to give [Ir2(μ-O2CMe)2Cl(O2CCF3)(CO)2(py)2] (5) in toluene.[Ir2(μ-hiq)2(CO)2Cl2] (Hhiq = 1-hydroxyisoquinoline, 6) was synthesized by the bridging-ligand substitution of 1 with Hhiq.Its axial adducts [Ir2(μ-hiq)2Cl2(CO)2L2] (L = Mepy (4-methylpyridine), 7 or PPh3, 8) were synthesized by addition of the ligands to a suspension of 6.In the structures of 7 and 8, two iridium atoms are bridged by two hiq ligands in a head-to-tail arrangement.The reaction of 1 with Hmhp (2-hydroxy-4-methylpyridine) led to triply bridged [Ir2(μ-mhp)3(CO)2Cl(Hmhp)] (9).In complex 9, all the mhp ligands bridge between the Ir atoms in a head-to-head manner.The Ir–Ir distances of 3, 4, 5, 7 and 8 are 2.6047(7), 2.6216(9), 2.5899(9), 2.5933(5) and 2.634(2) Å, respectively, which are similar to those observed in[Ir2(μ-O2CMe)2Cl2(CO)2L2]. The Ir–Ir distance of 2.5512(4) Å in 9 is shorter than in the other complexes.