1,4,10,13-tetraoxa-7,16-diaza(diphenylphosphinylmethyl)cyclooctadecane (L). As a prototype of supramolecular machine: Synthesis, crystal structure, and vibrational spectra of the sodium thiocyanate complex with L [NaL](NCS)

A new method of synthesis of the lariat crown ether 1,4,10,13-tetraoxa-7,16-diaza(diphenylmethyl)cyclooctadecane (L) has been described. The sodium thiocyanate complex with L [NaL](NCS) has been studied by X-ray crystallography, and the major vibrational frequencies in its IR spectrum have been assigned. The crystals of the complex are monoclinic: a = 11.538(2) Å, b = 9.796(2) Å, c = 7.564(2), Å, β = 90.38(3)°, Z = 2, space group P21/c, R1 = 0.0486 for 1733 reflections with I > 2σ(I). The compound has an ionic structure. In the centrosymmetric cation [NaL]+, both the macrocyclic part and the side groups of the ligand L are involved in coordination with the metal atom. The coordination polyhedron of the Na atom is a hexagonal bipyramid in which the equatorial plane is formed by six donor atoms of the substituted diaza-18-crown-6 ether (DA18C6) (av. Na-Oether, 2.682 Å; Na-N, 2.861 Å). The phosphoryl oxygen atoms of the side chains of the ligand occupy the axial positions (Na-OP, 2.325 Å). It is demonstrated that the cationic complexes of L can be, in principle, used as components of supramolecular machines.