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

Here, 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.