Synthesis and Characterisation of an [18]Crown-5-Ligand and its NaNCS Complex

The new [18]crown-5 ligand -[18] ⟨O 5 -(2,2′)-diphenylmethano·2 4 -coronand-5⟩ [1] -, containing a benzylic CH2 group, was prepared by condensation of 2,2'-dihydroxydiphenylmethane with tetraethylene glycol dichloride. The ligand exhibits an endo-conformation and short O···H 2 C contacts. The macrocycle ligates Na + by contracting its cavity so that its five O atoms form an approximately regular pentagon.