New versatile phosphorus-containing ligands -: asymmetric (XPR2)(YPR2′)NH (X, Y = O, S; R, R′ = Ph, OEt) and their potassium salts:: the crystal and molecular structures of (SPPh2)[OP(OEt)2]NH, K[(SPPh2){OP(OEt)2}N]•H2O and (OPPh2)[OP(OEt)2]NH•1/2HCl•1/4H2O

(XPPh2)[YP(OEt)(2)]NH (X, Y = O, S) were prepared as white crystalline solids using a new method of synthesis, i.e. the reaction between Li[HN(X)PR2] and R-2'P(Y)Cl in a benzene/n-hexane mixture. Both free acids and their K salts were characterised by IR and multinuclear (H-1, C-13, P-31) NMR spectroscopy. The monothio acid, (SPPh2)[OP(OEt)(2)]NH (1), crystallises in the monoclinic space group P2(1)/n. The molecule of 1 exhibits an anti conformation of the chalcogen atoms in the SPNPO system and the crystal contains dimeric pairs formed through N-H ... O(=P) hydrogen bonds. The potassium salt crystallises as a monohydrate, K[(SPPh2){OP(OEt)(2)}N] . H2O (2), in the triclinic space group P (1) over bar. There are two independent molecules in the cell unit. Four of them are associated to form a tetranuclear architecture through O-water and terminal O-phosphorus bridging atoms, and interactions between K(1) atoms and aromatic carbons of a phenyl group attached to phosphorus. Moreover, these tetranuclear units are linked together into a quite complicated polymeric structure through terminal O-phosphorus bridging atoms and KO-ethoxy interactions. The potassium ions of the two independent molecules exhibit a different coordination core. K(1) has the coordination number 9: a S,O-chelating phosphorus ligand, an O,O(Et) coordinated neighbouring phosphorus ligand, two oxygens from water molecules and three carbons of a phenyl group. K((2) has the coordination number 6: a S,O-chelating phosphorus ligand, an O,O(Et)-coordinated neighbouring phosphorus ligand, and two oxygens from water molecules. The dioxo acid crystallises as (OPPh2)[OP(OEt)(2)]NH . 1/2HCl . 1/4H(2)O (3), in the tetragonal space group P4(1)2(1)2. The molecule of 3 exhibits a syn conformation of the chalcogen atoms in the SPNPO system and the crystal contains chain polymers built through N-H ... Cl ... H-N and P=O ... H-O-H ... O=P hydrogen bonds. (C) 1999 Elsevier Science S.A. All rights reserved.