Nucleophilic addition and substitution reactions on the sulfur atoms bound to two Ir atoms. Conversion of a hydrosulfido complex [(η5-C5Me5)2Ir2(μ-SH)3]Cl into a series of diiridium complexes with bridging thiolato ligands

Abstract

The hydrosulfido-bridged diiridium complex [Cp*Ir(μ-SH)₃IrCp*]Cl 2 (Cp* = η⁵-C₅Me₅) reacted with an excess of CH₂CHX (X = COMe, SO₂Ph, COOMe, CN) in the presence of NEt₃ (4 equiv) in MeCN to afford the diiridium complexes [Cp*Ir(μ-SCH₂CH₂X)₃IrCp*]Cl 4, which contain three bridging thiolato ligands derived from the Michael addition of the μ-SH ligands in 2 to the activated alkenes. In contrast, when only 2 equiv of CH₂CHX (X = SO₂Ph, CN) were allowed to react with 2 under analogous conditions, sulfido–thiolato complexes [Cp*Ir(μ-S)(μ-SCH₂CH₂X)₂IrCp*] 5 were obtained exclusively. Reaction of 5d (X = CN) with neat ClCH₂CH₂Cl and that of 2 with CH₂CHCN in ClCH₂CH₂Cl in the presence of NEt₃ both gave a mixed-thiolato complex [Cp*Ir(μ-SCH₂CH₂Cl)(μ-SCH₂CH₂CN)₂IrCp*]Cl 6. Diiridium complexes with bridging dithiolato ligands were also obtainable from 2, which include [Cp*Ir(μ-SCH₂CH₂S)(μ-SCH₂CH₂Cl)IrCp*]Cl 7 from the reaction with ClCH₂CH₂Cl/NEt₃ along with [Cp*Ir{μ-SCH₂CH₂CH(OH)S}(μ-SCH₂CH₂CHO)IrCp*]Cl and [Cp*Ir{μ-SCHPhCH₂CH(OH)S}(μ-S)IrCp*] 9 afforded by treatment with α,β-unsaturated aldehydes CH₂CHCHO and PhCHCHCHO, respectively. Reaction of 2 with ethylene sulfide in the presence of NEt₃ also yielded a diiridium complex with bridging dithiolato ligands [Cp*Ir(μ-SCH₂CH₂S)₂IrCp*] 10. Detailed structures have been determined by X-ray analyses for 4b (X = SO₂Ph), 5d, 9, and 10, as well as the PF₆ salts of 6 and 7.