Study of ruthenium nitroso complexes some properties in sulfamate electrolytes during electrodeposition

Chemical state of ruthenium in the solutions of sulphamic acid during electrolysis (T 70 deg C) of ammonium nitrosopentachlororuthenate (NH4)2[RuNOCl5] and ruthenium 4 nitrosotrihydroxadiaqua [RuNO(OH)3(H2O)2] is studied on the base of UV electron absorption spectra. Quantitative distribution of ruthenium during electrodeposition among the deposit, solution and gaseous phase is obtained. Hydrolysis of the internal sphere of the coordination compound is stated to take place during electrodeposition. It results in release of [RuNO(OH)3(H2O)2] preformation chloroligands into the solution. Further oxidation up to volatible RuO4 takes place under the current effect. Accumulation of ruthenium tetraoxide in the electrolyte worsens the quality of coatings