The synthesis of a simple ambidentate ligand 1-(3-methylsulfanyl-phenyl)-3-pyridin-2-yl-urea (L) capable of binding metal ions via a pyridyl nitrogen atom or thioether sulfur donor is reported. The pyridyl functionality is located adjacent to an anion bindingurea group allowing this region of the ligand to bind contact ion-pairs by simultaneous coordination and hydrogen bonding interactions. This intimate ion-pair binding coordination mode is demonstrated by the X-ray crystal structures of [Ag(L)]X (X = CH3CO2−, 1; NO3−, 2). The non-coordinating PF6− anion is not bound as an ion-pair in [Ag(L)](PF6) (3) and the urea NH groups exhibit short contacts to carbonyl oxygen and π-systems. The X-ray crystal structure of [Ag(L)4]BF4 (4) is also reported, showing the ligand to be exclusively S-bound. Anion binding by L and its silver(I) complex is also explored by solution 1H NMR spectroscopic methods.
