Spectrophotometric study of stability constants of cimetidine–Ni(II) complex at different temperatures

Cimetidine, a histamine H2-receptor, has a structure which enables it to act as a chelating agent. The formation of nickel(II) complex with cimetidine has been studied spectrophotometrically at an absorption maximum of 622 nm at different temperatures. The data show that nickel(II) and cimetidine combine in the molar ratio of 1:2. The stability constants of the complex were calculated to be 1.40–2.4 × 108 by continuous variation method and 1.24–2.4 × 108 by mole ratio method at 25 and 40 °C, respectively. The immediately formed complex shows stability with respect to time and temperature.