Synthesis, Characterization, And Application Of Gold Complexes With Non-Cyanide

This thesis aims to research the synthesis of a new non-cyanide (nitrile) gold complex, show the characteristics of its structure and study about the gilded application performance it appears, expecting to replace the traditional cyanide gold plating technique.This complex took HAuCl4 as the raw material,2-mercaptopyridine as the non-cyanide ligand, and it produced the non-cyanide (nitrile) gold complex by the reduction of thiourea for the first time; it also demonstrated the structural features of the complexes and then obtained the formula, simultaneously going through the electric plating application testing.Content and methods of the study are as follows. Firstly, it synthesized a non-cyanide complex of gold by the method of selective reduction and ligand exchange and characterized its structure. Secondly, it explored the optimum condition for the intermediate Thiourea aurous to synthesize.Thirdly, it studied the influences of the concentration, pH, and temperature of raw material on the target product non-cyanide gold complexes, also, it explored its best synthesis technique. Fourth, it studied the electric plating process applications of the target product, analyzed the effects on apparent shape of coating and the rate of electroplating of these factors, such as gold salt concentration, current density, temperature, pH, plating time, brighteners etc, meanwhile, it obtained the optimal process condition through formal tests.The results are as follows:Firstly, it illustrated the characteristics of the new synthetic non-cyanide gold complex through the means of ultraviolet spectrum infrared spectroscopy, thermal gravimetric analysis, elemental analysis, and cycling voltammetry and etc, concluding that its molecular formula was NH4 [Au (MER) 2], the thermal decomposition temperature was 180 ℃. The material had good water solubility, and its molar conductivity was 0.75 S·m2·mol-1, belonging to ionic compound. Secondly, the ascending influential relationship to the synthetic Thiourea aurous was as follow, temperature< concentration ratio< reduction concentration< the concentration of HAuCl4. The optimum condition to synthesize was n (Au):n (Tu) = 1:3, concentration of HAuCl4 was 25mg/mL, concentration of Thiourea was 25mg/mL,concentration temperature was 45 ℃, concatenation factor was 2.5, the crystallization temperature was 0℃. Third, the ascending influential relationship to the synthetic NH4 [Au (MER) 2] was as follow, concentration ratio< pH< ligand concentration, The optimum condition to synthesize was n (Au):n (MER) = 1:2, concentration of 2 - mercapto pyridine was 25mg/mL, pH=10.5, concatenation factor was 2, concentration temperature was 45 ℃, the crystallization temperature was 0℃. Fourth, it studied the stability of the target product, finding that the product should be saved below the temperature of 40℃ and sealing environment without sunlight. Fifth, the optimum gold plating process was explored through the gilded gold plating experiment. The gold salt concentration was 15 g/L, the current density was 1.2 A/ dm2, brightener amount was 6mL / L, the bath temperature was 35 ℃, plating time was 120s, and pH value was 10.5, indicating that the quality of plating pieces obtained under these conditions was the best.Through the research to this subject, it produced the system of non-cyanide gold salt taking NH4 [Au (MER) 2] as the main composition, which also underwent the electrical plating gold application experiment. From the perspective of environmental protection, this method can replace cyanide gold-plated measures and reduce pollution, which was a highly promising and environmentally friendly product.