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

Abstract

Seven diiridium(II) complexes were synthesized by ligand substitution reactions of [Ir 2(μ-O 2CMe) 2Cl 2(CO) 2] ( 1) and [Ir 2(μ-O 2CMe) 2Cl 2(CO) 2(py) 2] ( 2).The reaction of 2 with the silver salt of a less coordinating anion, AgSbF 6, gave a cationic complex [Ir 2(μ-O 2CMe) 2Cl(CO) 2(py) 3]SbF 6 ( 3).A tricarbonyl cationic complex [Ir 2(μ-O 2CMe) 2(CO) 3Cl(py) 2]SbF 6 ( 4) was obtained under a CO atmosphere.Complex 2 reacted with AgO 2CCF 3 to give [Ir 2(μ-O 2CMe) 2Cl(O 2CCF 3)(CO) 2(py) 2] ( 5) in toluene.[Ir 2(μ-hiq) 2(CO) 2Cl 2] (Hhiq = 1-hydroxyisoquinoline, 6) was synthesized by the bridging-ligand substitution of 1 with Hhiq.Its axial adducts [Ir 2(μ-hiq) 2Cl 2(CO) 2L 2] (L = Mepy (4-methylpyridine), 7 or PPh 3, 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 [Ir 2(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[Ir 2(μ-O 2CMe) 2Cl 2(CO) 2L 2]. The Ir–Ir distance of 2.5512(4) Å in 9 is shorter than in the other complexes.