Synthetic, X-ray structural and protonation studies of CpCr(CO)2SPy and CpCr(CO)2SPym (SPy = C5H4NS, SPym = C4H3N2S)

The facile reaction of CpCr(CO)₃]₂ (Cp = η⁵-C₅H₅) (1) with one mole equivalent of 2,2′-dithiodipyridine ((C₅H₄NS)₂(SPy)₂) at ambient temperature led to the isolation of dark brown crystalline solids of CpCr(CO)₂(η²-SPy) (2) in ca. 72% yield. 2 undergoes quantitative conversion to CpCrCl₂(η¹-SPyH) (3) with HCl. The reaction 1 with one mole equivalent of 2-mercaptopyrimidine (C₄H₃N₂SHHSPym) at ambient temperature led to the isolation of reddish-brown crystalline solids of CpCr(CO)₂(η²-SPym) (4) and green solids of CpCr(CO)₃H (5) in yields of ca. 42% and 46%, respectively. Reaction of 4 with HCl and subsequent workup in acetonitrile resulted in the cleavage of the thiolate ligand, giving the 15-electron chromium(III) species CpCrCl₂(CH₃CN) (6) and free 2-mercaptopyrimidine. The complexes 2-4 have been determined by single X-ray diffraction analysis.