TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The catalyst is tris (dibenzylideneacetone) palladium, tetrakis (triphenylphosphine) palladium or bis (triphenylphosphine) palladium dichloride. The catalyst is present in an amount of 0.05-20%. The inert gas is nitrogen gas or argon gas. Preferred Method: The method comprises carrying out separating and purifying process by adding reaction liquid in deionized water and toluene, taking organic phase, distillating the product with mixed solution of toluene, then evaporating to dryness to 5 ml, dropwisely adding 400 ml of absolute ethanol, continuously stirring the mixture, settling and separating out the solid, filtering, then drying to obtain solid powder, dissolving the solid powder by chloroform, purifying by neutral aluminum oxide chromatographic column, decompression removing the organic solvent, depositing, filtering, extracting the obtained solid by acetone Soxhlet extractor, then depositing with alcohol, pumping and filtering. The compound A is prepared by (A) reacting 4-nitro-1,2-diamine and thionyl chloride in the presence of catalyst to solid-liquid ratio of 0.2295 g:1 ml, refluxing the mixture at 90 degrees C for 24 hours, steaming the thionyl chloride, cooling the mixture to room temperature to obtain 5-nitro-2,1,3 benzothiadiazole product, reacting 5-nitro-2,1,3 benzothiadiazole product with 40% of hydrobromic acid to solid liquid ratio of 0.69 g:1 ml to mix, heating the mixture at 127 degrees C to reflux, slowly dropping in liquid bromine for 4 hours and 30 minutes to obtain 4,7-dibromo-5-nitro-2,1,3 benzothiadiazole, where the ratio of 5-nitro-2,1,3 benzothiadiazole and liquid bromine 1 g:1.09 ml to obtain 4,7-dibromo-5-nitro-2,1,3 benzothiadiazole product, reacting 4,7-dibromo-5-nitro-2,1,3 benzothiadiazole product with copper powder in a mass ratio of 1.07:1, adding 4,7-dibromo-5-nitro-2,1,3 benzothiadiazole product with N,N-dimethyl formamide to solid-liquid ratio of 1 g: 8.82 ml to mix, heating the mixture to 12 degrees C for 3 hours, stopping reaction and cooling to room temperature, obtain the 4,4'- dibromo-6,6'-dinitro-2,1,3 benzothiadiazole, adding 4,4'- dibromo-6,6'-dinitro-2,1,3 benzothiadiazole, and tin dichloride in a molar ratio of 1:10, drying in tetrahydrofuran, raising the temperature to 100 degrees C, heating and refluxing for 10 hours, stopping reaction, cooling, dripping in sodium nitrite solution, adding potassium iodide solution to react at 5 degrees C for 30 minutes, acutely stirring the mixture to react for 12 hours, stopping reaction to obtain 4,4-dibromo-6,6-diiodo-2,1,3 benzothiadiazole, mixing 4,4-dibromo-6,6-diiodo-2,1,3 benzothiadiazole in potassium iodide according to mole ratio of 1.885:1, where the mole ratio of 4,4'- dibromo-6,6'-dinitro-2,1,3 benzothiadiazole and potassium iodide is 18.6:1, providing alkyl compound of formula (R1-CC-R2) (D), adding 4,4-dibromo-6,6-diiodo-2,1,3 benzothiadiazole and (D) in a mol ratio of 1:2 to mix, then adding 25-80 ml of N, N-dimethyl formamide, stirring for 20 minutes, adding tributylamine and acetic acid palladium, raising the temperature to 130 degrees C, heating for 4 hours and cooling, where the mole ratio of tributylamine and 4,4-dibromo-6,6-diiodo-2,1,3 benzothiadiazole is 2:1, and the acetic acid palladium and 4,4-dibromo-6,6-diiodo-2,1,3 benzothiadiazole is 1:10. The compound B is prepared by reacting compound of formula (C) with tetrahydrofuran as solvent under an inert atmosphere, reducing the temperature to 78 degrees C, then adding n-butyl lithium and butyl chloride, reacting for 1 hours, raising the temperature to room temperature for 6 hours, where the mole ratio of compound C and n-butyl lithium 1:2. The mole ratio of compound C and tributyl tin chloride is 1:2. Preferred Components: The solvent is tetrahydrofuran, ethylene glycol dimethyl ether, benzene or toluene.