Controlled Formation of Thiol‐Thiolate Hydrogen versus Disulfide Bonds between Two Iridium(III) Centers

AbstractHere, we report an iridium(III) coordination system with 2‐aminoethanethiolate (aet), which shows the formation of S−H⋅⋅⋅S hydrogen and S−S disulfide bonds in a controlled manner. Treatment of fac‐[Ir(aet)3] with aqueous HBF4 under aerobic conditions gave dinuclear [Ir2(aet)4(cysta)]2+ ([1]2+; cysta=cystamine) with a single S−S disulfide bond, while dimeric [Ir2(aet)3(Haet)3](BF4)3 ([2](BF4)3) with a triple S−H⋅⋅⋅S hydrogen bond was formed by similar treatment under anaerobic conditions. Upon exposure to air, [2]3+ was converted to dinuclear [Ir2(aet)2(Haet)2(cysta)]4+ ([3]4+), in which two IrIII centers are spanned by a double S−H⋅⋅⋅S hydrogen bond and a single S−S disulfide bond. Complex [3]4+ was interconvertible with [1]2+ via the removal/addition of protons on S donors, accompanied by the intermolecular exchange of the fac‐[Ir(aet)3] units. Complexes [1]2+, [2]3+, and [3]4+, isolated as BF4− salts, were fully characterized by single‐crystal X‐ray crystallography.