Reactivity of thiophosphinous acid bound to ruthenium

The thiophosphinous acid coordinated to ruthenium through the phosphorus atom in [CpRu(PPh₃)₂(PH₂SH)]CF₃SO₃ (1) is deprotonated in the presence of proton sponge to yield the neutral compound [CpRu(PPh₃)₂(PH₂S)] (2), where the thiophosphinite, PH₂S⁻, anion remains bound to the metal through the phosphorus atom. The parent complex 1 is easily restored in the presence of a weak acid. The sulfur of the coordinated anion may be alkylated with CF₃SO₃Me to yield [CpRu(PPh₃)₂(PH₂SCH₃)]CF₃SO₃ (3), the methyl thioester of the acid being bound to ruthenium through the phosphorus. The new compounds have been characterized by elemental analyses, IR and multinuclear NMR spectroscopy. The crystal structure of 2 · CH₃CN has been determined by X-ray diffraction methods.