New versatile phosphorus ligands containing SPNSO skeleton – synthesis and characterization of (SPPh2)(O2SR)NH acids (R=Me, C6H4Me-4) and their alkaline metal salts. Crystal and molecular structures of (SPPh2)(O2SR)NH

New phosphorus ligands of the type (SPPh2)(O2SR)NH [R=Me (1), C6H4Me-4 (2)] were prepared as white crystalline solids using the reactions between Li[HN(S)PPh2] and RSO2Cl. They were easily converted into their alkali metal salts, M[(SPPh2)(O2SR)N] (M=Li, Na, K). Both the free acids and their alkali metal salts were characterised by multinuclear (1H, 13C, 31P) NMR spectroscopy. The molecular structures of the free acids were established by single crystal X-ray diffraction. They crystallize in the tetragonal space group I41/a (1) and the triclinic space group P−1 (2), respectively. In both compounds the acidic proton is attached to nitrogen and the molecular units are associated through SO⋯H–N intermolecular hydrogen bonding [H⋯O 2.216 in 1 and 2.029 Å in 2]. A supramolecular chain-like structure is formed in 1 and dimeric units are built in 2. For both compounds a conformation close to syn–syn can be considered for the SP(C)2–N–SC(O)2 fragment.