Synthesis and Spectrophotometric Properties of Sodium Metal Carboxylates

Abstract

While metal carboxylates are by no means rare or inaccessible, complete characterization with notable exception of acetates is largely neglected hence a deficiency within the carboxylate literature giving rise to discrepancies within the characterization data available thus, spectroscopic properties of synthesized sodium metal carboxylates of acetic acid and myristic acid were investigated using Atomic Absorption Spectroscopy (AAS), flame photometry, FTIR spectrophotometer and UV- Visible spectrophotometry. AAS and flame photometric results showed elemental abundance of the sodium metals in the carboxylate complexes. FTIR spectra data revealed ʋCOO- absorptions at 1636 cm-1 and 1558 cm-1 for sodium acetate and sodium myristate respectively. The free acid ligands showed absorptions at 1703 cm-1 for acetic acid which shifted to 1636 cm-1 for sodium acetate. FTIR absorption of myristic acid revealed a strong absorption band at 1696 cm-1 which shifted to 1558 cm-1 in sodium myristate. The geometry of the complexes were determined by the magnitude of separation, Δʋ, which is equal to ʋaym - ʋsym,. The values of Δʋ for the synthesized sodium acetate complex was found to be 231 cm-1 and 138 cm-1 for sodium myristate indicating monodentate and bridging bidentate bonding respectively. Force constants of the carboxylates which correspond to their bond energies were found to be 1495.94 K NM-1 and 1358 K NM-1 for sodium acetate and sodium myristate, respectively. The UV- Visible analysis shows ʎ max values of 201 nm and 195 nm for sodium acetate and sodium myristate respectively, which corresponds to the absorption of the COO chromophore which is due to n-π* transition.