Binding of Polyatomic Anions with Protonated Ureido-pyridyl Ligands

作者：Marivel S; Arunachalam M; Ghosh Pradyut^*

来源：Crystal Growth & Design, 2011, 11(5): 1642-1650.

DOI：10.1021/cg101595n

Two ureido-pyridyl ligands, 1-(4-nitro-phenyl)-3-pyridine-3-ylmethyl-urea (L-1) and 1-pentafluorophenyl-3-pyridine-4-yl-urea (L-2) were synthesized in good yields, and solid-state anion binding studies of (HL1)(+) and (HL2)(+) with polyatomic anions such as NO3-, AcO-, ClO4-; SO42-, and SiF62- were carried out in detail. Protonation of the pyridyl nitrogen center of L-1 with HNO3, HClO4, and HF in different solvent media yielded crystals of complexes 1 (HL1 center dot NO3), 2 (HL1 center dot ClO4), and 3 (HL1 center dot 0.5SiF(6)) suitable for single crystal X-ray diffraction studies; respectively. Similarly, protonation of L-2 with HNO3, CH3COOH, and H2SO4 yielded single crystals of complexes 4 [2(HL2 center dot NO3)center dot DMF], 5 (HL2 center dot AcO), and 6 [(HL2)(2)center dot SO4], respectively. X-ray crystallographic analysis of all these six complexes has been carried out and the details of anion binding with the urea functionality of ureido-pyridyl ligands were investigated. In all the complexes, the pyridyl moiety of the ligands is found to be protonated and the binding of anions are observed at the urea functionality of the ligands through the R-2(2)(8) hydrogen bonding motif irrespective of sizes and shapes of anions or the electron withdrawing ability of aryl substitutions (p-nitro phenyl vs pentafluoro phenyl) or the position of the pyridyl nitrogen center (protonation site) of the designed ligands.

• 出版日期2011-5