Syntheses and structures of four new mixed-amide phosphoric triamides

Phospho­ric tri­amides have extensive applications in biochemistry and are also used as O-donor ligands. Four new mixed-amide phospho­ric tri­amide structures, namely rac-N-tert-butyl-N′,N′′-di­cyclo­hexyl-N′′-methyl­phospho­ric tri­amide, C17H36N3OP, (I), rac-N,N′-di­cyclo­hexyl-N′-methyl-N′′-(p-tol­yl)phospho­ric tri­amide, C20H34N3OP, (II), N,N′,N′′-tri­cyclo­hexyl-N′′-methyl­phospho­ric tri­amide, C19H38N3OP, (III), and 2-[cyclo­hex­yl(meth­yl)amino]-5,5-dimethyl-1,3,2λ5-di­aza­phosphinan-2-one, C12H26N3OP, (IV), have been synthesized and studied by X-ray diffraction and spectroscopic methods. Structures (I) and (II) are the first diffraction studies of acyclic racemic mixed-amide phospho­ric tri­amides. The P—N bonds resulting from the different substituent –N(CH3)(C6H11), (C6H11)NH–, 4-CH3-C6H4NH–, (tert-C4H9)NH– and –NHCH2C(CH3)2CH2NH– groups are com­pared, along with the different mol­ecular volumes and electron-donor strengths. In all four structures, the mol­ecules form extended chains through N—H⋯O hydrogen bonds.