Synthesis, Vibrational Spectra, and Crystal and Molecular Structure of 1,5-Bis[2-(dihydroxyphosphinyl)phenoxy]-3-oxapentane Dihydrate [(HO)2(O)P(C6H4)(OCH2CH2)2O(C6H4)P(O)(OH)2(H2O)] • H2O

A modified method of synthesis of a phosphoryl podand, 1,5-bis[2-(dihydroxyphosphinyl)phenoxy]-3-oxapentane (L), has been developed. The IR spectra of this podand and its dehydrate (L [L center dot H2O] center dot H2O (I) have been studied, the structure of I has been determined by X-ray crystallography. The crystals are orthorhombic, a = 9.4006(19) angstrom, b = 25.494(5) angstrom, c = 8.4264(17) angstrom, V = 2019.5(7) angstrom(3), Z = 4, space group Pna2(1), R = 0.0512 for 3016 reflections with I > 2 sigma(I). Compound I is a host-guest molecular complex. Phosphoryl podand L acts as a host molecule, and one of the water molecules (H2O(11)) is a guest. This molecule forms one donor and one acceptor intramolecular hydrogen bond with hydroxyl groups of two phosphoryl groups (O(8)H(4) and O(3)H(2)) and combines them into an 18-membered macrocyclic ring, acting as a kind of "lock." The H2O(11) molecule forms a second donor intramolecular hydrogen bond with the O(5) ether atom. The neutral molecular complexes are linked by hydrogen bonds directly and through the second water molecule (H2O(10)) into chains running along the c axis.