A Binding Pocket for Coordinated Water Formed by the Metal Center and Two Heterocyclic Nitrogens in Chelating Bis-thioethers of the Complexes {Cp*M[Im‘S(CH₂)₂SIm‘](H₂O)}²⁺ (M = Rh, Ir; Im‘ = 1-alkyl-4-tert-butylimidazol-2-yl)

Two new chelating bis-thioethers of the form Im‘S(CH₂)₂SIm‘ were made, where Im‘ = 1-methyl and 1-isopropyl-4-tert-butylimidazol-2-yl (4-Me and 4-iPr, respectively). When coordinated to Cp*Ir²⁺ and Cp*Rh²⁺ fragments in the presence of water, complexes 2 of the form {Cp*M[Im‘S(CH₂)₂SIm‘](H₂O)}²⁺{OTf^-}₂ were isolated in high yields. In these species, hydrogen-bonding networks were formed between the O−H bonds of the coordinated water molecule and the imidazole nitrogens on each side, as revealed in X-ray diffraction structures of 2-Me-Ir and 2-Me-Rh. Proton NMR spectra of the complexes in the presence of varying amounts of D₂O and H₂O led to formation of the three possible isotopomers, of which the H₂O and HOD isotopomers were detected by ¹H NMR. Three of the complexes were evaluated as modestly active catalysts for transfer hydrogenation of acetophenone in the absence of added base. As a control, the Cp*Rh²⁺ complex from PhSCH₂CH₂SPh was made and shown to be an ineffective catalyst.