Synthesis and physicochemical characterization of rhodium sulfosalicylate

Rhodium sulfosalicylate, prepared from 5-sulfosalicylic acid, distinguishes itself from most rhodium carboxylates by its high solubility in water. Magnetic resonance, infrared, ultraviolet, and visible spectroscopic techniques were used for structure determination and the resulting spectra suggested that the molecule bears the characteristic binuclear structure (two rhodium atoms complexing four equatorial ligand molecules) described for other transition metal carboxylates. Titrimetry, with a standardized base solution, indicated the presence of four free sulfonic acid functions in the molecule. Thermo analytical procedures (TG/DTG and DSC) indicated a loss of six water molecules by the complex at temperatures below 200 degrees C. The X-ray diffraction powder pattern for rhodium sulfosalicylate shows the end product of thermal decomposition as being metallic rhodium. (C) 2000 Elsevier Science Ltd. All rights reserved.