Crown ethers analogues and their complexes with NaSCN: Stoichiometry and stability constants determined by C-13 NMR spectroscopy

C-13 NMR spectroscopy was used to study the complexation reaction between s odium ion and 12-crown-4, 15-crown-5, methylurazolyl-12-crown-4 and methylu razolyl-15-crown-5 in CD3OD solutions. The type of complexes, the stability constants and the relative chemical shifts have been established by fittin g experimental titration curves with theoretical functions of the observed chemical shifts. The single-crystal X-ray diffraction measurements for a ne w crystalline complex confirmed the stoichiometry of the complex.