I’m sorry, but with my current knowledge, Se3Br3 is not a recognized chemical compound. Therefore, I cannot provide detailed information about its definition, properties, chemical reactions, and synthesis process.
You might be mistaken or have written the chemical formula incorrectly. I recommend that you double-check your information to make sure you are seeking information about the correct chemical compound.
If you are studying the compounds of Selenium (Se) and Bromine (Br), I advise you to research SeBr4 – TetraBromoSelenin(II), a compound with the unique chemical properties of both Selenium and Bromine.