Synthesis, characterization, and spectral studies of lanthanide(III) nitrate complexes of promethazine

Abstract A new series of lanthanide(III) nitrate complexes of 10-(2-dimethylaminopropyl)phenothiazine (promethazine or PM) with the general formula [Ln(PM) 2 (NO 3 ) 2 ]NO 3 , where Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, have been prepared and characterized based on elemental analysis, molar conductivity, magnetic susceptibility, spectroscopic data, and thermal studies. Conductance study indicates a 1:1 ionic ratio for the complexes in solution. The infrared spectra show that promethazine acts as a bidentate ligand using the heterocyclic nitrogen atom and tertiary nitrogen atom of the side chain as the sites of coordination. Only two of the nitrate ions are coordinated bidentately to the central metal ion while another nitrate ion remains outside the coordination sphere. A tentative structure has been proposed for the complexes.