New versatile phosphorus-containing ligands—asymmetric (XPR 2)(YPR′ 2)NH (X, Y=O, S; R, R′=Ph, OEt) and their potassium salts: the crystal and molecular structures of (SPPh 2)[OP(OEt) 2]NH, K[(SPPh 2){OP(OEt) 2}N] · H 2O and (OPPh 2)[OP(OEt) 2]NH · 1/2HCl · 1/4H 2O

Abstract

(XPPh 2)[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)PR 2] and R′ 2P(Y)Cl in a benzene/n-hexane mixture. Both free acids and their K salts were characterised by IR and multinuclear ( 1H, 13C, 31P) NMR spectroscopy. The monothio acid, (SPPh 2)[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[(SPPh 2){OP(OEt) 2}N] · H 2O ( 2), in the triclinic space group P 1 . 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 K⋯O–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 (OPPh 2)[OP(OEt) 2]NH · 1/2HCl · 1/4H 2O ( 3), in the tetragonal space group P4 12 12. 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.