Zwitterionic CS2 Adducts of Bis(dialkylphosphino)amines: Syntheses, Spectroscopy, and Structures*

Both bis(diisopropylphosphino)amine and bis(di-t-butylphosphino)amine react with CS2 to give bright red zwitterionic adducts of the form R2P(CS2)NP(R2)H (R = iPr or tBu). The P–H tautomer is the exclusive species present in solution, and there is no evidence of CS2 lability. The tautomeric hydrogen can undergo exchange with deuterium in protic solvents such as CD3OD. The products were characterized by single-crystal X-ray diffraction, IR and multinuclear (1H, 2H, 13C, 31P) NMR spectroscopies.