Stepwise Formation of Half-Sandwich Iridium-Based Rectangles Containing 2,5-Diarylamino-1,4-benzoquinone Derivatives Linkers

Binuclear complexes [Cp*Ir-2(2)(mu-DB)Cl-2] (1-5) (Cp* = eta(5)-C5Me5, DB = 2,5-diarylamino-1,4-benzoquinone derivatives) were obtained by the reactions of [Cp*Ir(mu-Cl)Cl](2) with 2,5-diarylamino-1,4-benzoquinone derivatives in the presence of base. Treatments Of [Cp*Ir-2(2)(mu-DB)Cl-2] with bidentate ligands (L) such as pyrazine, 4,4'-bipyridine (bpy) in the presence of Ag(OTf) (OTf = CF3SO3) in CH3OH solution gave the corresponding tetranuclear complexes, with the general formulas [Cp*Ir-4(4)(mu-DB)(2)(mu-L)(2)](OTf)(4) [1a,b-5a,b: DB = 2,5-dianilino-1,4-benzoquinone (DABQ), L = pyrazine (1a); DB = DABQ, L = bpy (1b); DB = 2,5-dianilino-3,6-dichloro-1,4-benzoquinone (DCBQ), L = pyrazine (2a); DB = DCBQ, L = bpy (2b); DB = 2,5-bis(4'-chloroanilino)-3,6-dichloro-1,4-benzoquinone (BCBQ), L = pyrazine (3a); DB = BCBQ, L = bpy (3b); DB = 2,5-bis(4'-bromoanilino)-3,6-dichloro-1,4-benzoquinone (BBBQ), L = pyrazine (4a); DB = BBBQ, L = bpy (4b); DB = 2,5-bis(4'-methoxyanilino)-3,6-dichloro1,4-benzoquinone (BMBQ), L = pyrazine (5a); DB = BMBQ, L = bpy (5b)]. The molecular structures Of [Cp*Ir-2(2)(mu-DABQ)Cl-2] (1), [Cp*Ir-2(2)(mu-DCBQ)Cl-2] (2), [CP*Ir-4(4)(mu-BCBQ)(2)(mu-bpy)(2)](OTf)(4) (3b), and [CP*Ir-4(4)(mu-BBBQ)(2)(mu-bpy)(2)](OTf)(4) (4b) have been determined by single-crystal X-ray analysis.